Aquaculture
Research to foster investor attraction and establishment of commercial Aquaculture Parks aligned to major saline groundwater interception schemes in South Australia
SARDI Publication Number: F2008/001027-1 SARDI Research Report Series No: 317
Wayne Hutchinson and Tim Flowers
SARDI Aquatics Sciences, PO Box 120, Henley Beach, SA 5022
December 2008
This publication may be cited as: Hutchinson, W.G. and Flowers, T. (2008) Research to foster investor attraction and establishment of commercial Aquaculture Parks aligned to major saline groundwater interception schemes in South Australia. Centre for Natural Resource Management (CNRM), Project 043713. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2008/001027- 1, SARDI Research Report Series No. 317, 378 pp.
South Australian Research and Development Institute SARDI Aquatic Sciences 2 Hamra Ave, West Beach, SA, 5024
Phone: 08 8207 5400 Facsimile: 08 8207 5481 Website: http://www.sardi.sa.gov.au
© This work is copyright. Except as permitted under the Copyright Act 1968 (Cth), no part of this publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owners. Neither may information be stored electronically in any form whatsoever without such permission.
The author does not warrant that the information in this book is free from errors or omissions. The author does not accept any form of liability, be it contractual, tortuous or otherwise, for the contents of this book or for any consequences arising from its use or any reliance placed upon it. The information, opinions and advice contained in this book may not relate to, or be relevant to, a reader's particular circumstances. Opinions expressed by the authors are the individual opinions of those persons and are not necessarily those of the publisher or research provider.
SARDI Publication No: F2008/001027-1 SARDI Research Report Series No: 317 ISBN No: 978-1-921563-06-5
Printed in 2009 by: PIRSA Corporate Services 101 Grenfell St Adelaide SA 5001
Author: Wayne Hutchinson and Tim Flowers Reviewers: Mehdi Doroudi and Steven Clarke Approved by: Steven Clarke
Signed: Date: 18 December 2008 Distribution: CNRM, PIRSA Aquaculture, National Library, State library of SA, SA Aquatic Sciences Library Circulation: Public domain
TABLE OF CONTENTS
NON-TECHNICAL SUMMARY...... I ACRONYMS AND DEFINITIONS...... XVII ACKNOWLEDGEMENTS ...... XIX OUTCOMES ACHIEVED ...... XXI SUMMARY OF PROGRESS AGAINST OBJECTIVES ...... XXIV NEED ...... XXX
CHAPTER 1 – GENERAL INTRODUCTION TO THE USE OF GROUNDWATER FOR INLAND SALINE AQUACULTURE ...... 1 1.1. SUMMARY...... 1 1.2. WATER SOURCES...... 2 1.3. WATER QUALITY...... 2 1.4. INLAND SALINE AQUACULTURE IN AUSTRALIA...... 3 1.4.1. VICTORIA...... 3 1.4.2. QUEENSLAND...... 4 1.4.3. WESTERN AUSTRALIA ...... 4 1.4.4. NEW SOUTH WALES ...... 5 1.4.5. SOUTH AUSTRALIA...... 6 1.5. SOUTH AUSTRALIA’S SALT INTERCEPTION SCHEMES...... 7 1.5.1. LIMITS ON DISPOSAL BASINS ...... 11 1.6. WAIKERIE INLAND SALINE AQUACULTURE CENTRE ...... 11 1.6.1. PILOT COMMERCIAL SCALE PRODUCTION TANKS ...... 17 1.7. REFERENCES ...... 20
CHAPTER 2 - CHARACTERISATION OF THE COMPOSITION OF SALINE GROUNDWATER FROM THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SALINITY INTERCEPTION SCHEME AND STOCKYARD PLAIN DISPOSAL BASIN ...... 23 2.1. SUMMARY...... 23 2.2. BACKGROUND...... 24 2.3. METHODS...... 25 2.3.1. WATER SAMPLING...... 25 2.3.2. WATER QUALITY PARAMETERS ...... 25 2.4. RESULTS ...... 28 2.4.1. PH ...... 28 2.4.2. SALINITY...... 30 2.4.3. CALCIUM ...... 30 2.4.4. MAGNESIUM ...... 30
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2.4.5. POTASSIUM ...... 32 2.4.6. SODIUM...... 32 2.4.7. BICARBONATE ...... 33 2.4.8. CHLORIDE ...... 33 2.4.9. POTASSIUM:CHLORIDE RATIO...... 35 2.4.10. FLUORIDE ...... 35 2.4.11. SULPHATE...... 36 2.4.12. SILICA ...... 37 2.4.13. METALS ...... 37 2.4.14. IRON...... 37 2.4.15. ARSENIC ...... 39 2.4.16. RAINFALL ...... 39 2.5. DISCUSSION ...... 40 2.6. CONCLUSION AND RECOMMENDATIONS ...... 42 2.7. REFERENCES ...... 43
CHAPTER 3 - ASSESSMENT OF THE PERFORMANCE OF MULLOWAY (ARGYROSOMUS JAPONICUS) CULTURED IN SALINE GROUNDWATER FROM STOCKYARD PLAIN DISPOSAL BASIN...... 45 3.1 SUMMARY...... 45 3.2 BACKGROUND...... 46 3.2 METHODS...... 48 3.2.1 EXPERIMENT 1 – PERFORMANCE OF MULLOWAY IN DILUTED SEAWATER AND SIS GROUNDWATER ...... 48 3.2.2 EXPERIMENT 2 - PERFORMANCE OF MULLOWAY IN DILUTED SEAWATER, SIS GROUNDWATER AND SEAWATER ...... 50 3.2.3 EXPERIMENT 3 - MEASUREMENT OF ROUTINE METABOLIC RATE, AND MAXIMUM METABOLIC RATE AND METABOLIC SCOPE ...... 50 3.2.4 STATISTICAL ANALYSIS ...... 51 3.3 RESULTS ...... 51 3.3.1 EXPERIMENT 1 ...... 51 3.3.2 EXPERIMENT 2 ...... 54 3.3.3 EXPERIMENT 3 ...... 55 3.4 DISCUSSION ...... 56 3.5 CONCLUSIONS AND RECOMMENDATIONS ...... 59 3.6 REFERENCES ...... 60
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CHAPTER 4 - ASSESSMENT OF THE PERFORMANCE OF SNAPPER (PAGRUS AURATUS) CULTURED IN SALINE GROUNDWATER FROM STOCKYARD PLAIN DISPOSAL BASIN...... 63 4.1. SUMMARY...... 63 4.2. BACKGROUND...... 63 4.3. METHODS...... 66 4.3.1. EXPERIMENT 1 – SNAPPER GROWN IN SPDB GROUNDWATER ...... 66 4.3.2. EXPERIMENT 2 - METABOLIC RESPONSE OF SNAPPER CULTURED IN SIS GROUNDWATER...... 68 4.3.3. STATISTICAL ANALYSIS ...... 69 4.4. RESULTS ...... 69 4.4.1. EXPERIMENT 1 ...... 69 4.4.2. EXPERIMENT 2 ...... 70 4.5. DISCUSSION ...... 72 4.6. CONCLUSION AND RECOMMENDATIONS ...... 74 4.7. REFERENCES ...... 75
CHAPTER 5 – EVALUATION OF YELLOWTAIL KINGFISH IN SALINE GROUNDWATER...... 77 5.1. SUMMARY...... 77 5.2. BACKGROUND...... 78 5.3. METHODS...... 80 5.3.1. EXPERIMENT 1 – PRELIMINARY ASSESSMENT OF THE SURVIVAL AND GROWTH OF YELLOWTAIL KINGFISH IS SIS GROUNDWATER...... 80 5.3.2. EXPERIMENT 2 – METABOLIC RESPONSES OF YELLOWTAIL KINGFISH CULTURED IN SIS GROUNDWATER ...... 82 5.3.3. EXPERIMENT 3 –ASSESSMENT OF THE GROWTH AND SURVIVAL OF YELLOWTAIL KINGFISH IN STANDARD SEAWATER, DILUTED SEAWATER, SIS GROUNDWATER AND POTASSIUM SUPPLEMENTED SIS GROUNDWATER ...... 82 5.4. STATISTICAL ANALYSIS ...... 85 5.5. RESULTS ...... 85 5.5.1. EXPERIMENT 1 ...... 85 5.5.2. EXPERIMENT 2 ...... 86 5.5.3. EXPERIMENT 3 ...... 87 5.6. DISCUSSION ...... 92 5.7. CONCLUSIONS AND RECOMMENDATIONS ...... 94 5.8. REFERENCES ...... 95
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CHAPTER 6 – PERFORMANCE OF MULLOWAY, ARGYROSOMUS JAPONICUS, CULTURED IN SIS GROUNDWATER AT WISAC...... 97 6.1. SUMMARY...... 97 6.2. BACKGROUND...... 98 6.3. METHODS...... 99 6.3.1. BATCH 1 – ADVANCED MULLOWAY ...... 99 6.3.2. BATCH 2 – FINGERLING MULLOWAY ...... 100 6.3.3. PRODUCT SAFETY AND SALE OF MULLOWAY CULTURED AT WISAC ...101 6.4. RESULTS ...... 101 6.4.1. BATCH 1...... 101 6.4.2. BATCH 2...... 103 6.4.3 PERFORMANCE OF ALL BATCHES OF MULLOWAY CULTURED AT WISAC...... 105 6.4.4. PRODUCT SAFETY AND SALE OF MULLOWAY CULTURED AT WISAC ...110 6.5. DISCUSSION ...... 111 6.6. CONCLUSIONS AND RECOMMENDATIONS ...... 114 6.7. REFERENCES ...... 115 APPENDIX 6.1. FORMULATION OF THE MULLOWAY DIET PRODUCED BY SARDI AT THE AUSTRALASIAN EXPERIMENTAL STOCKFEED EXTRUSION CENTRE, ROSEWORTHY ...... 117
CHAPTER 7 - PERFORMANCE OF A SEMI-INTENSIVE AQUACULTURE SYSTEM FOR CULTURE OF MULLOWAY AT WISAC ...... 119 7.1. SUMMARY...... 119 7.2. BACKGROUND...... 120 7.3. METHODS...... 121 7.4. RESULTS ...... 122 7.4.1. WATER TEMPERATURE...... 122 7.4.2. SALINITY...... 125 7.4.3. DISSOLVED OXYGEN ...... 126 7.4.4. TURBIDITY...... 127 7.4.5. DISSOLVED CARBON DIOXIDE AND PH ...... 129 7.4.6. WATER USE ...... 132 7.4.7. SIS GROUNDWATER PARAMETERS...... 133 7.4.8. MAJOR OPERATING COSTS ...... 133 7.5. DISCUSSION ...... 133 7.6. CONCLUSIONS AND RECOMMENDATIONS ...... 137 7.7. REFERENCES ...... 138 APPENDIX 7.1. METHOD FOR DETERMINATION OF DISSOLVED CO2 (MG/L) BY TITRATION (AMERICAN PUBLIC HEALTH ASSOCIATION, 2005) ...... 139 APPENDIX 7.2. FACTORS FOR CALCULATING DISSOLVED CO2 CONCENTRATIONS IN WATER WITH KNOWN PH, TEMPERATURE AND ALKALINITY (FROM TUCKER, 1984 IN WURTS AND DURBOROW 1992) ...... 140 APPENDIX 7.3. PORTABLE METER PURCHASED TO MEASURE DISSOLVED CO2 IN SALINE GROUNDWATER AT WISAC (WWW.OXYGUARD.DK)...... 141 iv
APPENDIX 7.4. COMPARISON OF DISSOLVED CO2 CONCENTRATION (MG/L) MEASURED BY TITRATION AND USING A PORTABLE CO2 METER (OXYGUARD® CO2 PORTABLE)...... 142
CHAPTER 8 – PRELIMINARY EVALUATION OF THE EFFECTS OF DISSOLVED CARBON DIOXIDE ON GROWTH AND SURVIVAL OF MULLOWAY, ARGYROSOMUS JAPONICUS ...... 143 8.1. SUMMARY...... 143 8.2. BACKGROUND...... 143 8.3. METHODS...... 145 8.3.1. CARBON DIOXIDE LEVELS...... 145 8.3.2. EXPERIMENTAL SYSTEM ...... 146 8.3.3. FISH AND EXPERIMENTAL PROCEDURES...... 146 8.3.4. WATER QUALITY...... 148 8.3.5. CALCULATION OF PERFORMANCE INDICES ...... 149 8.3.6. STATISTICAL ANALYSIS ...... 149 8.4. RESULTS ...... 149 8.4.1. WATER QUALITY...... 149 8.4.2. MORTALITY ...... 152 8.4.3. GROWTH PERFORMANCE...... 153 8.5. DISCUSSION ...... 159 8.6. CONCLUSIONS AND RECOMMENDATIONS ...... 161 8.7. REFERENCES ...... 162
CHAPTER 9 - CHARACTERISATION OF THE EFFECTS OF THE WASTE DISCHARGE FROM THE WAIKERIE INLAND SALINE AQUACULTURE CENTRE ON THE COMPOSITION OF SALINE INLAND AQUACULTURE WATER, MAY 2006 TO DECEMBER 2007...... 165 9.1 SUMMARY...... 165 9.2 BACKGROUND...... 166 9.3 METHODS...... 167 9.3.1 STATISTICAL ANALYSIS ...... 168 9.4 RESULTS ...... 168 9.4.1 CULTURE SYSTEM ...... 168 9.4.2 SOLUBLE PHOSPHORUS ...... 168 9.4.3 AMMONIA ...... 168 9.4.4 OXIDISED NITROGEN ...... 170 9.4.5 TOTAL NITROGEN...... 170 9.4.6 SUSPENDED SOLIDS ...... 170 9.5 DISCUSSION ...... 170 9.6 CONCLUSIONS AND RECOMMENDATIONS ...... 172
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CHAPTER 10 – HALOPHYTE CULTURE TRIALS, MARCH 2007 – FEBRUARY 2008...... 173 10.1. SUMMARY...... 173 10.2. BACKGROUND...... 173 10.3. TRIAL 1: POTTING MIX AND INITIAL WATER REGIME ...... 175 10.3.1. AIM ...... 175 10.3.2. METHODS...... 175 10.3.3. RESULTS ...... 177 10.3.4. DISCUSSION ...... 177 10.4. TRIAL 2: NEW V USED SIS WATER...... 179 10.4.1. AIMS ...... 179 10.4.2. METHODS...... 179 10.4.3. RESULTS ...... 183 10.4.4. DISCUSSION ...... 184 10.5. TRIAL 3: TRANSPLANTATION OF HALOPHYTES...... 185 10.5.1. AIMS ...... 185 10.5.2. METHODS...... 185 10.5.3. RESULTS ...... 186 10.5.4. DISCUSSION ...... 189 10.6. FUTURE OPTIONS FOR HALOPHYTE CULTURE IN SIS GROUNDWATER...... 190 10.6.1. BRIEF REVIEW OF THE CULTURE OF SALT-TOLERANT CROPS ...... 190 10.6.2. HALOPHYTE SEEDS AND FRUITS ...... 190 10.6.3. HALOPHYTES AND LEAF PROTEIN...... 192 10.6.4. PRODUCTION METHODS ...... 193 10.6.5. SEQUENTIAL RE-USE DRAINING MODEL...... 193 10.7. EFFICIENCY OF HALOPHYTE PRODUCTION SYSTEMS...... 195 10.7.1. PRODUCTION...... 195 10.7.2. NUTRIENT UPTAKE ...... 196 10.7.3. WATER LOSS ...... 196 10.7.4. PROBLEMS ...... 197 10.8. CONCLUSION AND RECOMMENDATIONS ...... 197 10.9. REFERENCES ...... 198
CHAPTER 11 – CONCLUSIONS AND RECOMMENDATIONS ...... 201 11.1. GENERAL CONCLUSIONS ...... 201 11.2. GENERAL RECOMMENDATIONS...... 203
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APPENDIX A – OVERSEAS TRAVEL REPORT: INLAND AQUACULTURE STUDY TOUR USA AND ISRAEL, OCTOBER 2004
APPENDIX B – CNRM AND SARDI PROJECT INFORMATION SESSION AND WORKSHOP AGENDA AND INTRODUCTION POWER POINT PRESENTATIONS PROFESSOR MEHDI DOROUDI: INLAND SALINE AQUACULTURE - A NATIONAL PERSPECTIVE MR WAYNE HUTCHINSON: R&D AND PROOF OF CONCEPT AQUACULTURE PRODUCTION: INVESTIGATION OF THE USE OF SALINE GROUNDWATER FROM A SALINITY INTERCEPTION SCHEME IN THE RIVERLAND, SOUTH AUSTRALIA MR NEIL SANDERCOCK: SITE OPTIMISATION USING GEOGRAPHIC INFORMATION SYSTEMS DR ERICA RIEBE: SIS FARMED FINFISH - RESULTS OF MARKET RESEARCH MR JULIAN MORRISON: ECONOMY AND SENSITIVITY ANALYSIS FOR SALT INTERCEPTION SCHEMES FOR AQUACULTURE WORKSHOP DISCUSSION OUTCOMES
APPENDIX C – MEDIA RELEASES
APPENDIX D – BIRD SURVEY
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TABLE OF FIGURES
CHAPTER 1 - GENERAL INTRODUCTION TO THE USE OF GROUNDWATER FOR INLAND SALINE AQUACULTURE...... 1 FIGURE 1.1. SALT INTERCEPTION SCHEMES IN SOUTH AUSTRALIA...... 8
FIGURE 1.2.A INFLOW OF SALINE GROUNDWATER INTO THE RIVER MURRAY WITHOUT IMPLEMENTATION OF WOOLPUNDA SIS ...... 9
FIGURE 1.2.B INTERCEPTION OF SALINE GROUNDWATER BY BORES OF THE WOOLPUNDA SIS ...... 10
FIGURE 1.3.A. ENTRY POINT AT SPDB FOR APPROXIMATELY 30 ML OF SALINE GROUNDWATER EACH DAY FROM SISS IN THE WAIKERIE AREA, SOUTH AUSTRALIA...... 10
FIGURE 1.3.B OVERVIEW OF SPDB, SOUTH AUSTRALIA...... 10
FIGURE 1.4.A. INFLOW OF SALINE GROUNDWATER INTO THE RIVER MURRAY WITHOUT IMPLEMENTATION OF WAIKERIE SIS...... 10
FIGURE 1.4.B INTERCEPTION OF SALINE GROUNDWATER BY BORES OF THE WAIKERIE SIS...... 10
FIGURE 1.5. GENERAL LAYOUT PLAN OF THE AQUACULTURE SYSTEM AND SUPPORT INFRASTRUCTURE AT WISAC...... 13
FIGURE 1.6. PRIMARY SETTLEMENT PONDS FOR TREATMENT OF SIS GROUNDWATER BEFORE REUSE OR RETURN TO THE SIS PIPELINE ...... 15
FIGURE 1.7. CONTRACTOR PUMPING SLUDGE FROM A PRIMARY SETTLEMENT POND AT WISAC .15
FIGURE 1.8. DEGASSING TOWER INSTALLED TO REDUCE THE CONCENTRATION OF DISSOLVED CO2 IN SIS GROUNDWATER BEFORE USE FOR FINFISH CULTURE AT WISAC...... 16
FIGURE 1.9. PRODUCTION TANK G1 USED TO ASSESS AND DEMONSTRATE PRODUCTION OF MULLOWAY IN A SEMI-INTENSIVE AQUACULTURE SYSTEM AT WISAC...... 18
FIGURE 1.10. ECO-TRAP™ (AQUAOPTIMA, TRONDHEIM, NORWAY) PARTICLE TRAP THAT COLLECTED UNEATEN FOOD AND FAECES FROM A 70 KL PRODUCTION TANK AT WISAC ...... 18
FIGURE 1.11. FORCE 7 OXYGEN DISSOLUTION DEVICE INSTALLED IN EACH PRODUCTION TANK AT WISAC FOR OXYGENATION AND INCREASED WATER FLOW ...... 19
CHAPTER 2 - CHARACTERISATION OF THE COMPOSITION OF SALINE GROUNDWATER FROM THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SALINITY INTERCEPTION SCHEME AND STOCKYARD PLAIN DISPOSAL BASIN ...... 23 FIGURE 2.1. WATER SAMPLES TAKEN SEPTEMBER 2004 - AUGUST 2005 AT FOUR LOCATIONS: 1 – WAIKERIE SECTION, 2 – WOOLPUNDA SECTION, 3 – QUALCO–SUNLANDS SECTION AND 4 – SPDB DISCHARGE POINT ...... 27 FIGURE 2.2. MONTHLY PH FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPT 2004 – AUG 2005...... 28 FIGURE 2.3. MONTHLY SALINITY (G/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005...... 30 FIGURE 2.4. MONTHLY CALCIUM CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005 (DOTTED LINE = CALCIUM LEVEL OF EQUIVALENT SALINITY SEAWATER) ...... 31 viii
FIGURE 2.5. MONTHLY MAGNESIUM CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 – AUGUST 2005 (DOTTED LINE = MAGNESIUM LEVEL IN EQUIVALENT SALINITY SEAWATER) ...... 31 FIGURE 2.6. MONTHLY POTASSIUM CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO -SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005 (DOTTED LINE = POTASSIUM LEVEL IN EQUIVALENT SALINITY SEAWATER) ...... 32 FIGURE 2.7. MONTHLY SODIUM CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005 (DOTTED LINE = SODIUM LEVEL IN EQUIVALENT SALINITY SEAWATER) ...... 33 FIGURE 2.8. MONTHLY BICARBONATE CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005 (DOTTED LINE = BICARBONATE LEVEL IN EQUIVALENT SALINITY SEAWATER) ...... 34 FIGURE 2.9. MONTHLY CHLORIDE CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB, SEPTEMBER 2004 TO AUGUST 2005 (DOTTED LINE = CHLORIDE LEVEL IN EQUIVALENT SALINITY SEAWATER)...... 34 FIGURE 2.10. MONTHLY POTASSIUM:CHLORIDE RATIO FOR THE WOOLPUNDA, WAIKERIE, QUALCO- SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005 ...... 35 FIGURE 2.11. MONTHLY FLUORIDE CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 – AUGUST 2005...... 36 FIGURE 2.12. MONTHLY SULPHATE CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005 (DOTTED LINE = SULPHATE LEVEL IN EQUIVALENT SALINITY SEAWATER) ...... 36 FIGURE 2.13. MONTHLY SILICA CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005. (DOTTED LINE = SULPHATE LEVEL IN EQUIVALENT SALINITY SEAWATER) ...... 37 FIGURE 2.14. MONTHLY IRON CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005...... 38 FIGURE 2.15. MONTHLY ARSENIC CONCENTRATION (MG/L) FOR THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005...... 39 FIGURE 2.16. MONTHLY RAINFALL (MM) FOR THE TOWNSHIP OF WAIKERIE BETWEEN SEPTEMBER 2004 AND AUGUST 2005 ...... 40
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CHAPTER 3 - ASSESSMENT OF THE PERFORMANCE OF MULLOWAY (ARGYROSOMUS JAPONICUS) CULTURED IN SALINE GROUNDWATER FROM STOCKYARD PLAIN DISPOSAL BASIN...... 45 FIGURE 3.1. LAYOUT OF EIGHT EXPERIMENTAL TANKS AND ASSOCIATED COMPONENTS OF INDIVIDUAL RECIRCULATING WATER TREATMENT SYSTEMS USED TO CULTURE MULLOWAY IN DIFFERENT WATER TYPES AT SAASC ...... 49 FIGURE 3.2. MEAN MONTHLY WEIGHTS (± SE) FOR MULLOWAY CULTURED IN EXPERIMENT 1 FOR 122 DAYS IN SIS GROUNDWATER AND DILUTED SEAWATER FOR 122 DAYS ...... 53 FIGURE 3.3. MEAN SPECIFIC GROWTH RATE (% BODY WEIGHT PER DAY, ± SE) FOR MULLOWAY CULTURED IN EXPERIMENT 1 IN SIS GROUNDWATER AND DILUTED SEAWATER FOR 122 DAYS...... 53 FIGURE 3.4. MEAN APPARENT FOOD CONVERSION RATIO (FCR, ± SE) FOR MULLOWAY CULTURED IN DILUTED SEAWATER AND SIS GROUNDWATER IN EXPERIMENT 1 FOR 122 DAYS ..54 FIGURE 3.5. MONTHLY MEAN WEIGHTS (G, ± SE) FOR MULLOWAY CULTURED IN EXPERIMENT 2 IN SIS GROUNDWATER, DILUTED SEAWATER AND SEAWATER FOR 45 DAYS...... 55
FIGURE 3.6. MEAN (± SE) ROUTINE METABOLIC RATE (μMOL O2/G/HR), METABOLIC SCOPE (μMOL O2/G/HR) AND MAXIMUM METABOLIC RATE (μMOL O2/G/HR) OF MULLOWAY CULTURED IN DILUTED SEAWATER, SIS GROUNDWATER AND SEAWATER...... 56
CHAPTER 4 - ASSESSMENT OF THE PERFORMANCE OF SNAPPER (PAGRUS AURATUS) CULTURED IN SALINE GROUNDWATER FROM STOCKYARD PLAIN DISPOSAL BASIN...... 61 FIGURE 4.1. LAYOUT OF EIGHT EXPERIMENTAL TANKS AND ASSOCIATED COMPONENTS OF INDIVIDUAL RECIRCULATING WATER TREATMENT SYSTEMS USED TO CULTURE SNAPPER IN DIFFERENT WATER TYPES AT SAASC ...... 66 FIGURE 4.2. MONTHLY MEAN WEIGHT (G, ± SE) OF SNAPPER CULTURED IN DILUTED SEAWATER AND SPDB GROUNDWATER FOR 62 DAYS ...... 68 FIGURE 4.3. MONTHLY MEAN FEED CONVERSION RATIO (FCR) OF SNAPPER CULTURED IN DILUTED SEAWATER AND SPDB GROUNDWATER FOR 62 DAYS ...... 69 FIGURE 4.4. MONTHLY MEAN SPECIFIC GROWTH RATE (SGR) OF SNAPPER CULTURED IN DILUTED SEAWATER AND SPDB GROUNDWATER FOR 62 DAYS...... 69 FIGURE 4.5. MEAN ROUTINE METABOLIC RATE, METABOLIC SCOPE AND MAXIMUM METABOLIC RATE (µMOL02/G/HR, ± SE) FOR SNAPPER CULTURED IN DILUTED SEAWATER WATER AND SALINE GROUNDWATER FROM SPDB...... 70 FIGURE 4.6. COMPARISON OF THE RELATIVE PROPORTION OF MAXIMUM METABOLIC RATE ATTRIBUTED TO METABOLIC SCOPE AND ROUTINE METABOLIC RATE FOR SNAPPER CULTURED IN SPDB GROUNDWATER AND DILUTED SEAWATER...... 71
CHAPTER 5 – EVALUATION OF YELLOWTAIL KINGFISH IN SALINE GROUNDWATER...... 75 FIGURE 5.1. LAYOUT OF 800 L TANK AND WATER TREATMENT COMPONENTS USED TO CONDUCT TRIAL 1 WITHIN TEMPERATURE CONTROLLED ROOM AT THE SOUTH AUSTRALIAN AQUATIC SCIENCES CENTRE (SAASC) ...... 79 FIGURE 5.2. EXPERIMENTAL TANKS (800 L) AND RECIRCULATED WATER TREATMENT SYSTEMS USED IN TRIAL 3...... 81 FIGURE 5.3. MEAN (± SE), ROUTINE METABOLIC RATE, MAXIMUM METABOLIC RATE AND METABOLIC SCOPE µMOL/G/HR FOR YELLOWTAIL KINGFISH GROWN IN DILUTED SEAWATER (DSW), SIS GROUNDWATER (GW) AND STANDARD SEAWATER (SW) FOR 21 DAYS. THERE WERE NO SIGNIFICANT DIFFERENCES BETWEEN MEANS FOR EACH RESPONSE VARIABLE (P > 0.05, ONE-FACTOR ANOVA)...... 85 x
FIGURE 5.4. MEAN (± SE) FORK LENGTH (MM) OF YELLOWTAIL KINGFISH GROWN IN DIFFERENT TYPES OF SALINE WATER FOR 40 DAYS. SW = STANDARD SEAWATER; DSW = DILUTED SEAWATER; GW = GROUNDWATER; GWK = GROUNDWATER WITH POTASSIUM ADDED...... 88 FIGURE 5.5. MEAN (± SE) CONDITION INDEX (WEIGHT (G) X 105/FORK LENGTH (MM)3) OF YELLOWTAIL KINGFISH GROWN IN DIFFERENT TYPES OF SALINE WATER FOR 40 DAYS. SW = STANDARD SEAWATER; DSW = DILUTED SEAWATER; GW = GROUNDWATER; GWK = GROUNDWATER WITH POTASSIUM ADDED...... 89 FIGURE 5.6. MEAN (± SE) SPECIFIC GROWTH RATE (% BODY WEIGHT PER DAY) OF YELLOWTAIL KINGFISH GROWN IN DIFFERENT TYPES OF SALINE WATER FOR 40 DAYS. SW = STANDARD SEAWATER; DSW = DILUTED SEAWATER; GW = GROUNDWATER; GWK = GROUNDWATER WITH POTASSIUM ADDED ...... 89
CHAPTER 6 – PERFORMANCE OF MULLOWAY, ARGYROSOMUS JAPONICUS, CULTURED IN SIS GROUNDWATER AT WISAC...... 95 FIGURE 6.1. FIRST STOCKING OF 3,200 ADVANCED MULLOWAY INTO PRODUCTION TANK G1 AT WISAC ON 8 MAY 2006 ...... 97 FIGURE 6.2. MONTHLY MEAN WEIGHT (KG, ± SD) OF BATCH 1 ADVANCED MULLOWAY CULTURED AT WISAC FOR 449 DAYS...... 100 FIGURE 6.3. MONTHLY FEED CONVERSION RATIO, (FCR) AND SPECIFIC GROWTH RATE (SGR) OF MULLOWAY CULTURED IN PRODUCTION TANK G1 AT WISAC FOR 449 DAYS...... 100 FIGURE 6.4. MONTHLY CONDITION INDEX (MEAN ± STANDARD DEVIATION) FOR MULLOWAY GROWN IN PRODUCTION TANK G1 AT WISAC FROM 27 DECEMBER 2006 UNTIL 30 JULY 2007 (216 DAYS) ...... 101 FIGURE 6.5. MONTHLY SPECIFIC GROWTH RATE (SGR) AND MEAN WEIGHT (G, ± SD) OF MULLOWAY CULTURED IN PRODUCTION TANK G2 AT WISAC FOR 543 DAYS...... 102 FIGURE 6.6. MONTHLY SPECIFIC GROWTH RATE (SGR) AND MEAN WEIGHT (G, ± SD) OF MULLOWAY CULTURED IN PRODUCTION TANK G3 AT WISAC FOR 548 DAYS...... 102 FIGURE 6.7. MONTHLY MEAN CONDITION INDEX (± SD) OF MULLOWAY CULTURED IN PRODUCTION TANKS G2 AND G3 AT WISAC FOR 543 DAYS AND 548 DAYS RESPECTIVELY...... 103 FIGURE 6.8. COMPARISON OF GROWTH (DAYS FROM 2.0G) OF TWO BATCHES OF MULLOWAY CULTURED USING SIS GROUNDWATER IN THREE 70KL PRODUCTION TANKS AT WISAC ...... 104 FIGURE 6.9. COMPARISON OF GROWTH OF MULLOWAY CULTURED IN SIS GROUNDWATER AT WISAC, IN AMBIENT SEAWATER IN COMMERCIAL SEACAGES; AND IN NATURAL CONDITIONS IN THE WILD...... 107 FIGURE 6.10. THE LOGO USED TO MARKET THE MULLOWAY FROM WISAC...... 109
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CHAPTER 7 - PERFORMANCE OF A SEMI-INTENSIVE AQUACULTURE SYSTEM FOR CULTURE OF MULLOWAY AT WISAC ...... 117 FIGURE 7.1. MONTHLY MEAN TEMPERATURE (OC ± SE) OF SIS GROUNDWATER ENTERING WISAC AND IN PRODUCTION TANKS USED TO CULTURE MULLOWAY ...... 121
FIGURE 7.2. MONTHLY MEAN WATER TEMPERATURE (OC ± SD), AND MONTHLY MEAN WEIGHT (G, ± SD) OF MULLOWAY CULTURE IN PRODUCTION TANKS G1 (449 DAYS), G2 (543 DAYS) AND G3 (548 DAYS) AT WISAC...... 122
FIGURE 7.3. MONTHLY MEAN SALINITY (G/L ± SE) OF WATER IN PRODUCTION TANKS G1 AT WISAC FROM 1 OCTOBER 2006 UNTIL 31 MAY 2007 ...... 123
FIGURE 7.4. MEAN DISSOLVED OXYGEN CONCENTRATION (% SATURATION ± SE) OF SIS GROUNDWATER BEFORE (PRE) AND AFTER (POST) DEGASSING AT WISAC ...... 124
FIGURE 7.5. TYPICAL DAILY LOG (6 MARCH 2007) OF DISSOLVED OXYGEN (% SATURATION) OF EFFLUENT WATER FROM THREE MULLOWAY PRODUCTION TANKS AT WISAC...... 125
FIGURE 7.6. TURBIDITY (NTU) OF WOOLPUNDA SIS GROUNDWATER USED AT WISAC AND NOTIFIED PIPELINE MAINTENANCE EVENTS FROM 1 APRIL 2007 UNTIL 3 APRIL 2008 ...... 126
FIGURE 7.7. TURBIDITY (NTU) OF WOOLPUNDA SIS GROUNDWATER USED AT WISAC ON 9 AUGUST 2006...... 127
FIGURE 7.8. MONTHLY MEAN DISSOLVED CARBON DIOXIDE (MG/L ± SE) AND BIOMASS (KG) FOR MULLOWAY PRODUCTION TANKS AT WISAC...... 128
FIGURE 7.9. DISSOLVED CO2 CONCENTRATION (MG/L) OF SIS GROUNDWATER BEFORE (PRE) AND AFTER (POST) PASSING THROUGH A DEGASSING TOWER INSTALLED AT WISAC (MAY 2006 UNTIL MARCH 2008) ...... 129
FIGURE 7.10. RELATIONSHIP BETWEEN DISSOLVED CO2 AND PH FROM DATA COLLECTED FROM ALL PRODUCTION TANKS AT WISAC BETWEEN MAY 2006 AND MARCH 2008 ...... 129
FIGURE 7.11. MONTHLY MEAN TOTAL SIS GROUNDWATER USE (KL/DAY ± SE) AND TOTAL MONTHLY MULLOWAY BIOMASS (KG) AT WISAC WHILE PRODUCTION TANKS WERE STOCKED BETWEEN OCTOBER 2006 AND MARCH 2008 ...... 130
FIGURE 7.12. PADDLEWHEEL IN USE IN A SEMI-INTENSIVE PRODUCTION TANK FOR EUROPEAN SEABREAM (SPARUS AURATA) IN ISRAEL ...... 134
CHAPTER 8 – PRELIMINARY EVALUATION OF THE EFFECTS OF DISSOLVED CARBON DIOXIDE ON GROWTH AND SURVIVAL OF MULLOWAY, ARGYROSOMUS JAPONICUS ...... 143 FIGURE 8.1. SCHEMATIC DIAGRAM OF THE EXPERIMENTAL SYSTEM USED TO CONDUCT THE DISSOLVED CO2 TRIAL WITH MULLOWAY AT WISAC...... 147
FIGURE 8.2. PICTURE OF THE EXPERIMENTAL SYSTEM USED TO CONDUCT THE DISSOLVED CO2 TRIAL WITH MULLOWAY AT WISAC ...... 148
FIGURE 8.3. AVERAGE CONCENTRATION OF DISSOLVED CO2 (MG/L) IN EACH EXPERIMENTAL TREATMENT...... 150
FIGURE 8.4. AVERAGE PH IN THE EXPERIMENTAL TREATMENTS DURING THE TRIAL ...... 151
FIGURE 8.5. AVERAGE DISSOLVED OXYGEN SATURATION LEVEL (%) IN EXPERIMENTAL TANKS DURING THE TRIAL...... 151 xii
FIGURE 8.6. AVERAGE WATER TEMPERATURE (°C) IN EXPERIMENTAL TANKS DURING THE TRIAL ...... 152
FIGURE 8.7. THE TOTAL NUMBER OF MORTALITIES RECORDED FOR EACH TREATMENT DURING THE TRIAL...... 153
FIGURE 8.8. AVERAGE TOTAL WEIGHT (G/FISH, MEAN ± SE) OF MULLOWAY CULTURED AT DIFFERENT CONCENTRATIONS OF DISSOLVED CO2 (MG/L)...... 155
FIGURE 8.9. AVERAGE TOTAL FORK LENGTH (MM; MEAN ± SE) OF MULLOWAY CULTURED AT DIFFERENT CONCENTRATIONS OF DISSOLVED CO2 (MG/L)...... 158
FIGURE 8.10. AVERAGE CONDITION INDEX (MEAN ± SE) OF MULLOWAY CULTURED AT DIFFERENT CONCENTRATIONS OF DISSOLVED CO2 (MG/L) ...... 158
CHAPTER 10 – HALOPHYTE CULTURE TRIALS, MARCH 2007 – FEBRUARY 2008...... 173 FIGURE 10.1. SARCOCORNIA QUINQUEFLORA GROWING ADJACENT TO THE SPDB...... 174
FIGURE 10.2. JUVENILE SARCOCORNIA QUINQUEFLORA GROWING AT SPDB ...... 175
FIGURE 10.3. PLANTS BEING TRANSFERRED FROM THE SPDB TO WISAC...... 176
FIGURE 10.4. MAXIMUM DAILY AMBIENT AIR TEMPERATURES AT WAIKERIE DURING TRIAL 1, MARCH 2007...... 178
FIGURE 10.5. SARCOCORNIA QUINQUEFLORA GROWING FROM RHIZOMES AT SPDB ...... 180
FIGURE 10.6. SARCOCORNIA QUINQUEFLORA GROWING FROM RHIZOMES AT SPDB ...... 180
FIGURE 10.7. VISITING SCIENTISTS FROM SHANDONG ACADEMY OF SCIENCES, CHINA, REMOVING EXCESS WATER FROM PLANTS BEFORE WEIGHING AND TRANSPLANTING...... 181
FIGURE 10.8. VISITING SCIENTISTS FROM SHANDONG ACADEMY OF SCIENCES, CHINA, WEIGHING PLANTS PRIOR TO TRANSPLANTING AT WISAC...... 181
FIGURE 10.9. SARCOCORNIA QUINQUEFLORA PLANTS POTTED AND SITTING IN TROUGHS SUPPLIED WITH “NEW” SIS WATER OR “USED” SIS WATER AT WISAC ...... 182
FIGURE 10.10. SARCOCORNIA QUINQUEFLORA PLANTS DIRECTLY AFTER TRANSPLANTING INTO 125 MM POTS AT WISAC...... 182
FIGURE 10.11. MAXIMUM DAILY AMBIENT AIR TEMPERATURES AT WAIKERIE DURING TRIAL 2, DECEMBER 2007...... 184
FIGURE 10.12. MAXIMUM DAILY AMBIENT AIR TEMPERATURES AT WAIKERIE DURING TRIAL 3 (17TH JANUARY TO 28TH FEBRUARY 2008)...... 188
FIGURE 10.13. SALICORNIA SP. BEING CULTURED IN SEAWATER DISCHARGED FROM FINFISH CULTURE TANKS AT THE NATIONAL CENTRE FOR RESEARCH IN MARICULTURE, EILAT, ISRAEL (FLOWERS AND HUTCHINSON 2005)...... 190
FIGURE 10.14. DIAGRAM OF THE FILTER SYSTEM (BLACKWELL ET AL., 2000)...... 194
FIGURE 10.15. DIAGRAM SHOWING HOW THE FILTER SYSTEM REMOVES NITROGENOUS POLLUTANTS FROM WATER (BLACKWELL ET AL., 2000)...... 195
FIGURE 10.16. SEAWATER IRRIGATED FURROW CULTIVATION OF SALICORNIA ON A LARGE SCALE COMMERCIAL FARM ON THE WEST COAST OF MEXICO (WWW.SALICORNIA.COM). ..196
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LIST OF TABLES
CHAPTER 2 - CHARACTERISATION OF THE COMPOSITION OF SALINE GROUNDWATER FROM THE WOOLPUNDA, WAIKERIE, QUALCO-SUNLANDS SALINITY INTERCEPTION SCHEME AND STOCKYARD PLAIN DISPOSAL BASIN ...... 23 TABLE 2.1 MEAN COMPOSITION OF SEA WATER...... 26 TABLE 2.2 MEAN WATER QUALITY PARAMETERS FOR THE WAIKERIE, WOOLPUNDA, QUALCO- SUNLANDS SIS AND THE STOCKYARD PLAINS DISPOSAL BASIN DISCHARGE POINT, BETWEEN SEPTEMBER 2004 AND AUGUST 2005 (± SD) ...... 29 TABLE 2.3 MEAN METAL CONCENTRATIONS FOR THE WOOLPUNDA, WAIKERIE, QUALCO- SUNLANDS SIS AND THE SPDB DISCHARGE POINT, SEPTEMBER 2004 TO AUGUST 2005 (± SD)...... 38
CHAPTER 3 - ASSESSMENT OF THE PERFORMANCE OF MULLOWAY (ARGYROSOMUS JAPONICUS) CULTURED IN SALINE GROUNDWATER FROM STOCKYARD PLAIN DISPOSAL BASIN ...... 45 TABLE 3.1 COMPOSITION OF DILUTED SEAWATER AND SIS GROUNDWATER USED TO CULTURE MULLOWAY IN EXPERIMENT 1 FOR 122 DAYS...... 48 TABLE 3.2 COMPOSITION OF DILUTED SEAWATER AND SIS GROUNDWATER USED TO CULTURE MULLOWAY IN EXPERIMENT 2 FOR 45 DAYS...... 50 TABLE 3.3 MEAN (± SE) DISSOLVED OXYGEN (% SATURATION), PH, SALINITY (G/L), WATER TEMPERATURE (OC) AND TOTAL AMMONIA NITROGEN (MG/L) FOR THE DIFFERENT WATER TYPE TREATMENTS IN EXPERIMENT 1 OVER 122 DAYS...... 52 TABLE 3.4 MEAN (± SE) INITIAL AND FINAL WEIGHTS, BIOMASS GAIN PER TANK, SPECIFIC GROWTH RATE (% BODY WEIGHT PER DAY, SGR) AND APPARENT FEED CONVERSION RATIO (FCR), FOR MULLOWAY CULTURED IN DILUTED SEAWATER AND SIS GROUNDWATER IN EXPERIMENT 1 OVER 122 DAYS (VALUES THAT SHARE A COMMON SUPERSCRIPT ARE NOT SIGNIFICANTLY DIFFERENT, P > 0.05) ...... 52 TABLE 3.5 MEAN (± SE) DISSOLVED OXYGEN (% SATURATION), PH, SALINITY (G/L), WATER TEMPERATURE (OC) AND AMMONIA (MG/L) IN TANKS USED TO CULTURE MULLOWAY IN DIFFERENT WATER TYPE TREATMENTS IN EXPERIMENT 2 CONDUCTED OVER 45 DAYS ...... 54 TABLE 3.6 MEAN (± SE) INITIAL AND FINAL WEIGHTS, BIOMASS GAIN, SPECIFIC GROWTH RATE (% BODY WEIGHT PER DAY, SGR) AND APPARENT FEED CONVERSION RATIO (FCR) FOR MULLOWAY CULTURED IN DIFFERENT WATER TYPE TREATMENTS IN EXPERIMENT 2 OVER 45 DAYS ...... 55 TABLE 3.7 COMPARISON OF METABOLIC PARAMETERS (MGO2/KG/HR; MEAN ± SE) FOR MULLOWAY RECORDED IN EXPERIMENT 3 WITH THOSE DETERMINED BY FITZGIBBON (2007); AND FOR RED DRUM, SCIAENOPS OCELLATUS (FOSBERG ET AL., 1997) ...... 58
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CHAPTER 4 - ASSESSMENT OF THE PERFORMANCE OF SNAPPER (PAGRUS AURATUS) CULTURED IN SALINE GROUNDWATER FROM STOCKYARD PLAIN DISPOSAL BASIN...... 61 TABLE 4.1. COMPOSITION OF SEAWATER, ISO-OSMOTIC AND SALINE GROUNDWATER SOURCES USED IN THIS STUDY (MG/L UNLESS STATED). ANALYSIS CARRIED OUT BY AWQC, SA WATER ...... 65 TABLE 4.2. MEAN (± SE) WATER TEMPERATURE (OC), DISSOLVED OXYGEN (% SATURATION), PH, SALINITY (G/L), AND TOTAL AMMONIA NITROGEN (MG/L) FOR DIFFERENT WATER TYPE TREATMENTS OVER 62 DAYS...... 67 TABLE 4.3. COMPARISON OF MEAN WEIGHT (G ± SE), FCR AND SGR OF SNAPPER CULTURED IN DILUTED SEAWATER AND SPDB GROUNDWATER FOR A PERIOD OF 62 DAYS ...... 68
CHAPTER 5 – EVALUATION OF YELLOWTAIL KINGFISH IN SALINE GROUNDWATER...... 75 TABLE 5.1. MEAN (± SE) DISSOLVED OXYGEN (% SATURATION), PH, SALINITY (G/L), WATER TEMPERATURE (OC) AND AMMONIA (MG/L) FOR DIFFERENT WATER TYPE TREATMENTS OVER 21 DAYS...... 83 TABLE 5.2. MEAN (± SE) INITIAL AND FINAL WEIGHTS, BIOMASS GAIN, SPECIFIC GROWTH RATE (% BODY WEIGHT PER DAY, SGR) AND APPARENT FEED CONVERSION RATIO (FCR) FOR YELLOWTAIL KINGFISH CULTURED IN DIFFERENT WATER TYPE TREATMENTS OVER 21 DAYS (AVERAGES THAT SHARE A COMMON SUPERSCRIPT ARE NOT SIGNIFICANTLY DIFFERENT, P > 0.05)...... 84 TABLE 5.3. MEAN (± SE) SALINITY (G/L), DISSOLVED OXYGEN (% SATURATION), AMMONIA (NH4+/NH3, MG/L), POTASSIUM (MG/L), CHLORIDE (MG/L) AND POTASSIUM TO CHLORIDE (K+:CL-) RATIO FOR DIFFERENT SALINE WATER TYPES OVER 40 DAYS. ...86 TABLE 5.4. TWO-FACTOR ANOVA FOR TOTAL WEIGHT (G), FORK LENGTH (MM), CONDITION INDEX (WEIGHT (G) X 105/FORK LENGTH (MM)3), WEIGHT GAIN (G), SGR (% BIOMASS PER DAY), FEED CONSUMED (G) AND APPARENT FCR OF YELLOWTAIL KINGFISH GROWN IN DIFFERENT SALINE WATER TYPES FOR40 DAYS1, 2 ...... 87
CHAPTER 6 – PERFORMANCE OF MULLOWAY, ARGYROSOMUS JAPONICUS, CULTURED IN SIS GROUNDWATER AT WISAC...... 95 TABLE 6.1. PERFORMANCE MEASURES FOR TWO BATCHES OF MULLOWAY CULTURED IN THREE 70,000L TANKS IN SIS GROUNDWATER AT WISAC FROM 8 MAY 2006 UNTIL 4 APRIL 2008 ...... 105
TABLE 6.2. GROWTH MODELS (ALL BATCHES AND BEST BATCH) OF NUMBER OF DAYS FOR 2.0 G MULLOWAY TO ACHIEVE TARGET WEIGHTS BASED UPON DATA COLLECTED FROM BATCH 1 - ADVANCED AND BATCH 2 FINGERLINGS CULTURED TO MARKET SIZE AT WISAC BETWEEN MAY 2006 AND APRIL 2008...... 106
TABLE 6.3. RESULTS FROM TESTING AND SCREENING FOR PESTICIDES, ANTIMICROBIALS, METALS TRIPHENYLMETHANE DYES, PCBS AND DIOXINS FROM A COMPOSITE SAMPLE OF FLESH FROM MULLOWAY (N = 10) CULTURED AT WISAC ...... 108
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CHAPTER 7 - PERFORMANCE OF A SEMI-INTENSIVE AQUACULTURE SYSTEM FOR CULTURE OF MULLOWAY AT WISAC ...... 117 TABLE 7.1. MEAN CONCENTRATION OF DISSOLVED CO2 (MG/L, ± SE) IN MULLOWAY PRODUCTION TANKS AT WISAC...... 127 TABLE 7.2. SUMMARY OF SIS GROUNDWATER USED AT WISAC FROM MAY 2006 UNTIL MARCH 2008 ...... 130 TABLE 7.3. SUMMARY OF PARAMETER MEASURED DAILY FOR SIS GROUNDWATER USED AT WISAC ...... 131 TABLE 7.4. SUMMARY OF MAJOR COSTS ($/KG) AND PERCENTAGE OF COSTS OF PRODUCTION OF MULLOWAY CULTURED IN A SEMI-INTENSIVE AQUACULTURE SYSTEM OPERATED AT WISAC BETWEEN MAY 2006 AND MARCH 2008...... 131
CHAPTER 8 – PRELIMINARY EVALUATION OF THE EFFECTS OF DISSOLVED CARBON DIOXIDE ON GROWTH AND SURVIVAL OF MULLOWAY, ARGYROSOMUS JAPONICUS ...... 143 TABLE 8.1. THE NOMINAL AND ACTUAL AVERAGE CONCENTRATIONS OF DISSOLVED CO2 (MG/L), AND PH FOR THE EXPERIMENTAL TREATMENTS1 ...... 150 TABLE 8.2. TWO-FACTOR ANOVA RESULTS FOR TOTAL WEIGHT, WEIGHT GAIN, SPECIFIC GROWTH RATE (SGR), TOTAL LENGTH AND CONDITION INDEX OF MULLOWAY 1, 2, 3 EXPOSED TO DIFFERENT LEVELS OF DISSOLVED CO2 FOR 54 DAYS ...... 156 TABLE 8.3. MEAN VALUES FOR TOTAL WEIGHT, WEIGHT GAIN, TOTAL LENGTH AND CONDITION INDEX OF MULLOWAY EXPOSED TO DIFFERENT LEVELS OF DISSOLVED CO2 FOR 54 DAYS 1,2,3...... 157
CHAPTER 9 - CHARACTERISATION OF THE EFFECTS OF THE WASTE DISCHARGE FROM THE WAIKERIE INLAND SALINE AQUACULTURE CENTRE ON THE COMPOSITION OF SALINE INLAND AQUACULTURE WATER, MAY 2006 TO DECEMBER 2007...... 165 TABLE 9.1. ENVIRONMENTAL WATER QUALITY MONITORING AND FISH STOCK BIOMASS DATA FOR THE WISAC FROM MAY 2006 TO DECEMBER 2007...... 169
CHAPTER 10 – HALOPHYTE CULTURE TRIALS, MARCH 2007 – FEBRUARY 2008...... 173 TABLE 10.1. TREATMENT DESCRIPTIONS AND NUMBER OF PLANTS USED IN TRIAL 1, MARCH 2007 ...... 176
TABLE 10.2. CONDITION OF TRIAL 1 PLANTS AFTER FOUR WEEKS ...... 177
TABLE 10.3. TREATMENTS AND NUMBER OF PLANTS USED IN TRIAL 3, JANUARY - FEBRUARY 20081 ...... 187
TABLE 10.4. CONDITION OF TRIAL 3 PLANTS AFTER THREE WEEKS (7TH FEBRUARY 2008) AND 6 WEEKS (28TH FEBRUARY 2008)...... 188
TABLE10.5. NUTRITIONAL COMPOSITION (100G/FRESH VEGETABLE) OF SALICORNIA (SIMPSON, UNDATED) ...... 191
TABLE 10.6. LEAF COMPOSITION OF A RANGE OF SALT TOLERANT PLANTS USED FOR LEAF PROTEIN PRODUCTION (INCLUDES SALICORNIA) (SIMPSON, UNDATED)...... 192
xvi Acronyms and definitions
ACIAR Australian Centre for International Agricultural Research ADU Aquaculture Development Unit AMR Active metabolic rate AWQC Australian Water Quality Centre CPISARC Cooke Plains Inland Saline Aquaculture Research Centre DSW Diluted seawater DWLBC Department of Water, Land and Biodiversity and Conservation ET Evapotranspiration CI Condition index CNRM Centre for Natural Resource Management
CO2 Carbon dioxide DCLW District Council of Loxton Waikerie EPA Environmental Protection Agency ESAI Ecologically Sustainable Agriculture Initiative FCR Food conversion ratio FRDC Fisheries Research and Development Corporation GW Groundwater GWK Salinity interception scheme groundwater with added potassium IAAS Integrated agri-aquaculture systems ISAARG Inland Saline Aquaculture Applied Research Group ISARC Inland Saline Aquaculture Research Centre K+:Cl- Potassium to chloride ratio kWh Kilowatt hours MDBA Murray Darling Basin Authority MIL Murray Irrigation Limited MMR Maximum metabolic rate MRL Maximum residue limits [Non-Technical Summary, page vii] MS Metabolic scope NATA National Association of Testing Authorities NSGAE Northern Spencer Gulf Aquaculture Enterprise Incorporated
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NTU Nephelometric turbidy units ORL Our Rural Landscape PC Personal computer PCB Polychlorinated biphenyl pH a measure of acidity PIRSA Primary Industries and Resources South Australia PLC Programmable logic controller R&D Research and development RDC Riverland Development Corporation RMR Routine metabolic rate SAAM South Australian Aquaculture Management Propriety Limited SAASC South Australian Aquatic Science Centre SA MDB NRM South Australian Murray Darling Basin Natural Resource Management SARDI South Australian Research and Development Institute SD Standard deviation SE Standard error SIFTS Semi-intensive floating tank system SGA Spencer Gulf Aquaculture Propriety Limited SGR Specific growth rate SIS Salt interception scheme SPDB Stockyard Plain Disposal Basin SW Seawater WAP Waikerie Aquaculture Park WISAC Waikerie Inland Saline Aquaculture Centre
xviii Acknowledgements
The authors would like to thank Aaron Boehm, Paul Drummond, James Duvnjak and Paul Skordes, technical staff of Aquatic Sciences, South Australian Research and Development Institute, who were involved in maintaining all fish during trials conducted at the South Australian Aquatic Science Centre and the Waikerie Inland Saline Aquaculture Centre. We also acknowledge the efforts of Professor Mark Powell (formerly School of Aquaculture, University of Tasmania, Launceston, Tasmania; currently Faculty of Biosciences and Aquaculture, Bodø University College, Norway) for providing equipment and working with Tim Flowers to conduct metabolism studies on mulloway, snapper and yellowtail kingfish. The authors would like to thank Peter Forward and Ryan Felder, SA Water, for their help in accessing some of the water samples required for this report and providing information on the background and operations of the salt interception schemes. The input on policy and regulation from Primary Industries and Resources South Australia Aquaculture Division and the South Australian Environmental Protection Agency was also appreciated. The considerable assistance provided by Louise Handley, Jane Ham and Steven Clarke to compile and format this final report is acknowledged and greatly appreciated. Finally, we would like to thank the Centre of Natural Resource Management, South Australian Government, and the National Action Plan for Salinity and Water Quality for their funding and support of this research.
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xx Non-technical summary
Project title: Research to foster investor attraction and establishment of commercial aquaculture parks aligned to major saline groundwater interception schemes in South Australia
Principal investigator: Wayne Hutchinson
Address: South Australian Research and Development Institute South Australian Aquatic Science centre PO Box 120 Henley Beach, South Australia, 5022 Telephone 08 8207 5444 Email: [email protected]
Outcomes achieved
The project described in this report was conducted by the South Australian Research and Development Institute (SARDI) between 1 July 2004 and 31 March 2008. The project was funded by the National Action Plan for Salinity and Water Quality and administered by the Centre for Natural Resource Management (CNRM) and the Department of Water, Land, Biodiversity and Conservation (DWLBC), South Australia. Research and development (R&D) and proof of concept activities of this project were conducted at the Waikerie Inland Saline Aquaculture Centre (WISAC), South Australia and the South Australian Aquatic Science Centre (SAASC), West Beach, Adelaide.
At the start of this project a workshop was convened to summarise past inland saline aquaculture R&D conducted by SARDI at the Cooke Plains Inland Saline Aquaculture Research Centre (CPISARC) and to introduce the objectives of this new project to stakeholders. At this workshop salt interception scheme (SIS) managers, and representatives of local and state government agencies, identified key issues that needed to be considered to allow use of SIS groundwater for aquaculture in South Australia.
Subsequently, a three week study tour was undertaken by key project personnel involving visits to research and commercial aquaculture facilities using saline groundwater in the United States of America and Israel. A report was compiled which summarised each facility visited and identified technologies that would be appropriate for using for SIS groundwater based aquaculture in South Australia.
Consultation with the District Council of Loxton Waikerie (DCLW) allowed the identification of an appropriate site for establishment of a proof of concept scale aquaculture facility near Waikerie, South Australia. The location was within 10 metres of the Woolpunda SIS pipeline and the land required was leased from a local landowner.
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Between October 2004 and April 2006, WISAC was designed and constructed, including obtaining all necessary local and South Australian government approvals. The facility was commissioned in May 2006 when approximately 13,000 mulloway were stocked into production and nursery tanks supplied with SIS groundwater.
This project conducted the first comprehensive sampling program to determine the composition of groundwater from the Woolpunda, Waikerie and Qualco-Sunlands SISs and of water discharging from the combined SISs into the Stockyard Plain Disposal Basin (SPDB). The most significant finding of this 12 month sampling program was that, in general, the composition of the groundwater within the SISs was likely to be suitable for aquaculture of euryhaline species such as mulloway.
Subsequently, the performance of mulloway, snapper and yellowtail kingfish was assessed at an R&D scale using SIS groundwater transported from SPDB to the SAASC. This research showed that the growth and metabolism of mulloway and yellowtail kingfish were not significantly different in SIS groundwater, diluted seawater and seawater, while the growth of snapper was impaired in SIS groundwater compared to diluted seawater and seawater. These trials suggested that mulloway and yellowtail kingfish were potential species for culture in SIS groundwater, with mulloway likely to be the species of choice because of its known broad salinity tolerance.
From May 2006 until March 2008 mulloway were cultured to marketable size (>750 g) at WISAC in a semi-intensive aquaculture system, which achieved a final stocking density in excess of 30 kg per 1,000 L (1 kL). From this proof of concept scale production trial, 9,772 kg of fish were harvested and fish performance and operational aquaculture system data were collected. The mean total food conversion ratio (FCR) for all fish combined was 2.03. The mean specific growth rate (SGR) of the best performing batch of mulloway cultured at WISAC was 0.51%/day over the culture period of approximately 600 days, from when they were stocked at 2.0 g until harvest at >750 g.
Information from processors to whom these fish were sold, and an aligned marketing study commissioned by Primary Industries and Resources South Australia (PIRSA) Aquaculture and undertaken by the Ehrenberg-Bass Institute of Marketing Science, University of South Australia using fish supplied by this project, suggested that production of mulloway in excess of 1.5 kg would be desirable. It was estimated that a culture period of approximately 835 days would be needed to achieve this weight for mulloway using SIS groundwater in a semi- intensive aquaculture system at WISAC.
Production of mulloway at WISAC demonstrated that aquaculture could be effectively achieved in parallel with the operation of a major SIS. Risk management features that were included within the facility design (i.e. turbidity sensor controlling an actuated valve inlet valve and installation of water storage tanks) allowed maintenance procedures conducted by SIS operators (SA Water) to be completed without significant impediment to aquaculture operations.
The proof of concept production component of the overall project demonstrated that the growth rate of mulloway cultured in SIS groundwater at WISAC was substantially faster than
xxii wild caught mulloway and mulloway cultured commercially in the marine environment in Spencer Gulf within seacages. The growth rate was also faster than that reported for both European sea bass and sea bream, both species that support large established aquaculture industries in the Mediterranean region. Despite these promising results, researchers believed better mulloway performance could be achieved and sought to address some of the possible limiting factors.
Dissolved carbon dioxide (CO2) was identified as the major issue impacting upon the performance of mulloway in the semi-intensive aquaculture system investigated at WISAC. The concentration of dissolved CO2 was high in the SIS groundwater and degassing was required before this water was supplied to fish cultured at WISAC. While degassing greatly reduced the dissolved CO2 levels entering the mulloway production tanks, dissolved CO2 levels were still approximated 20 mg/L, which remained a concern although the effects of such concentrations on fish performance were ambiguous in the scientific literature reviewed. To better characterise the effects, an experimental system was constructed and a trial conducted. This demonstrated that the growth of mulloway was significantly reduced when the concentration of dissolved CO2 was greater than 6 mg/L, the lowest value assessed. This suggested that any commercial aquaculture system developed should incorporate more efficient methods to remove dissolved CO2, and that this was likely to enhance the growth of mulloway beyond what was obtained in the demonstration trials undertaken during this project. The use of a more intensive recirculation aquaculture system was proposed to optimise the use of the higher temperature of SIS groundwater for fish production while allowing management of the levels of dissolved CO2 and oxygen.
During the culture of mulloway at WISAC the mean cost of production was $7.65/kg. The major costs considered were feed (47.7%), electricity (29.6%) and oxygen (19.8%). Based on the data collected it was suggested that cost reductions could be achieved through improved feed management to reduce FCR and improve growth, as well as selection of a commercial aquaculture site where wastewater need not be pumped back into the SIS pipeline discharging into the SPDB. An aligned project, commissioned by PIRSA Aquaculture and undertaken by Econsearch Pty Ltd, used information provided by this project to populate an economic model for potential commercial investors to assess the financial viability of commercial SIS aquaculture.
Analysis of flesh was conducted from a sample of mulloway cultured in SIS groundwater. Levels of all chemicals assessed were below the relevant Australian maximum residue limits (MRL) or were below the detectable limits of the methods used by the National Association of Testing Authorities (NATA) accredited laboratory employed. Prices received for the mulloway produced by the proof of concept trials were between $6.60 and $7.00/kg. The retail price of whole fish was between $12.00/kg and $14.00/kg and between $22.00/kg and $25.00/kg for fillets. A good recovery rate of between 45%% and 48%% was reported for market size fish (>750 g). Responses from chefs, fish processors and consumers during taste testings and an aligned marketing study confirmed that the product was well accepted and of high quality. This suggested that a commercial facility undertaking significant production and providing consistent supply would be able to implement a marketing plan to achieve improved prices for high quality fish produced using SIS groundwater. A large production facility should also be able to reduce cost of production through economies of scale.
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An environmental monitoring program was conducted to satisfy the requirements of PIRSA Aquaculture and South Australian Environmental Protection Agency (EPA). This program demonstrated that the proof of concept scale production activities at the WISAC had minimal effect on the levels of key nutrients and suspended solids in the downstream water. However, any commercial aquaculture facilities aligned to SISs will need to address the relevant regulatory requirements of these state government agencies with their increased fish production levels likely to increase waste discharges. In recognition of this need, trials were commenced to investigate the use of a local halophyte (Sarcocornia quinqueflora) for treatment of waste water as an alternative to the more usual mechanical means used by aquaculturalists. While this was unsuccessful due to a lack of available knowledge about the biology and culture of the halophyte species selected, a review of relevant scientific information suggested that the concept had promise and was also likely to reduce the volume of water discharged to disposal basins, an outcome stated to be beneficial by SIS managers.
To begin to better understand the ecology of the SPDB, an aligned project was initiated, and managed to collect and assess monthly water quality and plankton data (a Flinders University Honours thesis) as well as complete a seasonal survey of the species of birds present (a consultant’s report to SARDI).
To complete the project, a workshop was held to communicate the results and outcomes to those interested. Presentations covered not only the topic of this project, but also the key projects aligned to it. Following the presentations, a smaller group discussion session took place to review the project and make recommendations on the need and direction of future R&D.
Summary of progress against objectives
1. Summarise the planning and regulatory issues specific to development of commercial aquaculture aligned to SISs.
From the start of this project stakeholders involved with management and operation of SIS (i.e. Murray Darling Basin Authority [MDBA] and SA Water), inland aquaculture planning, regulation and industry development (i.e. PIRSA Aquaculture), and local and regional planning and industry development (i.e. DCLW and Riverland Development Corporation [RDC]) were consulted. On 24 and 25 June 2004, a workshop was held to summarise previous inland saline aquaculture R&D conducted by SARDI at the CPISARC, present the new SIS groundwater aquaculture project to a range of stakeholders, identify major planning and regulatory issues, and discuss future R&D directions.
Planning and regulatory issues required to support development of aquaculture aligned to SIS were identified as important matters that deserved to be further progressed during the conduct of this project to allow commercial developments. The activities of this R&D and proof of concept scale project initiated a consultation process conducted by PIRSA Aquaculture to gather information on the range of planning and regulatory issues to be addressed in order to
xxiv allow commercial aquaculture aligned to SISs operating in the Riverland region. From this consultation the discussion paper, Draft framework for inland aquaculture zones around salt interception schemes, was prepared (PIRSA Aquaculture, March 2006, unpublished). This paper identified a range of issues that required input from a number of South Australian state and local government agencies. Ultimately this precipitated a ‘whole of government’ case management framework approach to be adopted and led by PIRSA Aquaculture. SARDI, as the organisation undertaking this project, was a key participant in the case management framework group. This approach facilitated preparation of the following reports to further support commercialisation of outcomes of R&D and proof of concept scale activities: 1. Market research and analysis of finfish farmed using groundwater 2. Economic and sensitivity analysis for the use of SIS for aquaculture development 3. Site optimisation using geographic information systems. Based upon experiences and data collected during R&D trials, SARDI provided regular input on technical and operational matters to consultants and agencies responsible for the preparation of each of these reports.
2. Complete a desktop study of potential species and conduct an audit of culture systems and environmental control technologies suitable for commercial aquaculture using groundwater from SISs.
At the start of this project it was recognised that a limited number of species could be identified as showing potential for culture using saline groundwater available from SISs. A national inland saline aquaculture development workshop that canvassed the views of R&D and industry participants across Australia concluded that barramundi (Lates calcarifer), silver perch (Bidyanus bidyanus), prawns (Penaeus sp.), mulloway (Argyrosomus japonicus) and snapper (Pagrus auratus) were still among the top 13 prospects for commercial inland saline aquaculture (Allan et al., 2001). The unique combination of water temperature, salinity, ionic composition and water volume available from SIS in the Riverland region dictated that mulloway and snapper offered the best prospects for aquaculture and were the first species evaluated by this project. Another major selection criterion is the availability of fingerlings or ‘seed’ to stock a commercial aquaculture venture, with commercial hatcheries in South Australia presently only producing yellowtail kingfish (although mulloway and snapper have been produced in the past). Yellowtail kingfish were also considered as a potential species for aquaculture using SIS groundwater as commercial seacage aquaculture of this species has developed rapidly over recent years in South Australia and is now also occurring in New South Wales and Western Australia. There is an established supply of hatchery produced fingerlings and an expanding market demand for this species.
Initial project planning activities included an overseas study tour of inland saline aquaculture facilities in the southern states of USA and Israel to identify culture methods and technologies that would be most applicable to utilise with SIS groundwater for commercial aquaculture. This tour included visits to five commercial farms and three R&D facilities in the USA, and 13 commercial farms and three R&D facilities in Israel. A report was compiled following this tour (Appendix A) summarising the operations and approaches to issues such
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as environmental control and waste management. From the information gained during this study, combined with consideration of accumulated knowledge of a range of aquaculture systems, proof of concept scale semi-intensive and intensive aquaculture systems were proposed for construction at WISAC. However, insurmountable difficulties were encountered relating to international procurement and a decision had to be made to proceed only with the construction of the locally sourced semi-intensive aquaculture system at WISAC.
3. Establish an R&D facility to underpin development of a commercial Aquaculture Park near Waikerie (WAP) in conjunction with local TAFE and indigenous organisations, incorporating a pilot scale commercial farm, R&D, demonstration and training facilities.
A major component of this project entailed the design, construction and operation of WISAC, which was officially opened on 23 September 2006 by Ministers Karlene Maywald and Rory McEwen (Figure 1). WISAC was constructed on a leased site with close access to the main Woolpunda SIS pipeline. WISAC operated from May 2006 until April 2008 and supported proof of concept trials of a semi-intensive aquaculture system that was evaluated for the culture of mulloway. Over this period 9,772 kg of mulloway were harvested and supplied to local fish processors, distributors and restaurants. Trials were also conducted at WISAC on the affect of dissolved carbon dioxide (CO2) on mulloway performance and the growth of local halophytic plants in SIS groundwater discharged from aquaculture production tanks.
During this project, TAFE made a strategic decision to only conduct aquaculture courses at their facilities in Port Lincoln and Urrbrae (Adelaide) leaving no possibility for training activities to be undertaken at WISAC. However, while operating, WISAC hosted local secondary school and TAFE students for work experience, and technical staff who had completed TAFE aquaculture training courses were employed by SARDI. In September 2006, SARDI hosted a Science Outside the Square event at WISAC. This involved a bus tour for 120 people visiting SIS operations (SA Water), a tour of WISAC’s aquaculture operations and a tour of SPDB. In August 2007, WISAC hosted a Science Week event that involved a day of aquaculture activities presented to groups of 30 students from six local primary schools. WISAC hosted visits by scientists from across Australia and overseas as part of tours for the Australasian Aquaculture Conference (2006) and the Second International Salinity Forum (2008). Numerous visits were hosted for local agricultural bureaus, community groups and visiting dignitaries during the conduct of this project (Appendix C).
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Figure 1. Official opening of WISAC by Ministers Karlene Maywald and Rory McEwen, 23 September 2006.
4. Assess suitability of groundwater from SPDB for culture of two species with best potential from the desktop study. Specifically, early trials will focus on growth in water from SPDB compared to salinity adjusted seawater and development of commercially applicable methods to compensate for potassium deficiencies if this is problematic.
The suitability of SIS groundwater for culture of mulloway, snapper and yellowtail kingfish was evaluated (Chapters 4, 5 and 6). Growth trials and metabolic studies on each of these species were conducted at SAASC. These trials concluded that mulloway was suitable for culture in SIS groundwater while yellowtail kingfish may have potential in a production system that can support this species. Growth of snapper cultured in SIS groundwater was reduced compared to fish cultured in similar salinity seawater. This species is not recommended for aquaculture using the SIS groundwater assessed.
5. Measure growth performance of two species with best potential in water from SPDB until these achieve market size.
Two batches of mulloway were cultured to market size in three proof of concept scale production tanks (70,000 L) at WISAC using SIS groundwater. A total of 13,112 fish were stocked in a semi-intensive aquaculture production system. This species showed high survival rates and the growth performance achieved indicated that a culture period of between 18.6 and 19.7 months was required to produce market size fish (>750 g) starting with 2.0 g
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fingerlings. Market acceptance and product quality were high and the price achieved was between $6.60 and $7.00/kg for whole fish. It is suggested that further improvements could be achieved if problems identified could be adequately addressed. The two key issues to be addressed were reducing the elevated concentration of dissolved CO2 that persisted in the culture system, and better feed management to improve growth and reduce production costs. It is suggested that higher prices could be achieved if a reliable supply of fish was maintained and a marketing plan undertaken that focused on the quality of this product and benefits of productive use of SIS groundwater.
Trials conducted at SAASC indicate that the SIS groundwater supports growth and survival of this species.
Two small batches of yellowtail kingfish were also stocked at WISAC, however, these fish showed progressive mortality. It was suggested that the production system used at WISAC was not suitable to support production of this fast growing and demanding species. Therefore, improved water treatment within an intensive system may be required to support production of yellowtail kingfish at WISAC.
6. Evaluate the performance of the two most compatible culture systems identified by the desktop technology audit and modify these if necessary to include discharge water treatment systems to allow sustainable inland saline aquaculture operations using SPDB water.
The design for WISAC proposed installation of a semi-intensive aquaculture system and an intensive aquaculture system. Only the locally constructed semi-intensive aquaculture system was installed due to international procurement issues preventing the purchase of the desired Israeli intensive system within the time frame available for this project.
The semi-intensive aquaculture system achieved the specified stocking density of 30 kg per 1,000 L (1 kL) when fish reached market size. Elevated concentration of dissolved CO2 in culture water was identified as the major operational problem with this system. The results of this study showed that growth of mulloway reduced as the concentration of dissolved CO2 increased. Appropriate and effective methods to reduce and utilise nutrients in saline water discharged from WISAC utilising SIS groundwater were also identified as issues that needed to be addressed if commercialisation is to proceed. Preliminary investigations of the growth of a local species of halophyte (Sarcocornia quinqueflora) undertaken at WISAC demonstrated that transplantation of young established plants was not successful and any future R&D will need to be undertaken using propagated seedlings or by considering the use of other species. The high cost of pumping water back into the SIS was also identified as an issue that could be addressed with better site selection for a commercial aquaculture venture.
7. Generate performance and economic data from the demonstration farm for investment planning by industry and to support ongoing development of sustainable production systems aligned to SISs.
xxviii Data for major operating cost items was collected during production of mulloway at WISAC. Feed was identified as the major production cost followed by electricity and then oxygen. It is suggested that improvements can be made to reduce feed and oxygen costs while better site selection could greatly reduce the cost attributed to electricity. Information generated was also provided to consultants engaged by PIRSA Aquaculture to prepare the report Economic and sensitivity analysis for the use of SIS for aquaculture development. Fish (approximately 100 kg) were supplied for consumer taste testing and surveys (Figure 2) conducted by other consultants engaged by PIRSA Aquaculture and were the basis for the marketing report Market research and analysis of finfish farmed using groundwater from SIS. These reports were prepared for the ‘whole of government’ Case Management Framework – Aquaculture Development Utilising Wastewater from Salt Interception Schemes, and will provide the information required by commercial investors to assist them to plan for the use of SIS groundwater available for aquaculture.
Figure 2. Consumer surveys and taste testing of Murray mulloway conducted at the Central Market.
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Need
This project undertook R&D and a proof of concept scale trial to facilitate the development of commercial aquaculture based on select fish species and aquaculture systems, and in doing so also evaluated the composition of groundwater for the Woolpunda, Waikerie and Sunlands-Qualco SISs that discharge into the SPDB. The development of viable and sustainable aquaculture exploiting essentially a wastewater resource was considered to provide the potential for a significant new and much needed economic opportunity for the Riverland region of South Australia.
To undertake this project there was a need to establish an integrated R&D and proof of concept facility supplied with SIS groundwater from Woolpunda. This facility was used to undertake research needed to provide information required to attract private sector investment in potential commercial farms using SIS groundwater in the Riverland region of South Australia.
To provide this information there was a need to undertake activities targeting four main technical areas: 1. the suitability of the SIS groundwater for aquaculture 2. selection and performance evaluation of preferred aquaculture species 3. evaluation of preferred aquaculture systems 4. assessment of planning, regulatory and sustainability issues associated with SIS aquaculture development.
xxx Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
1.1. Summary Across Australia, man-made (or secondary) salination of land and water is causing major impacts on agricultural production, rural infrastructure, drinking water, irrigation and aquatic biodiversity (Allan et al., 2001). Strategies for managing this type of salination include: • prevention (avoiding a further worsening of salinity) • treatment (repairing salinity) • adaptation (living with salinity).
Aquaculture has been identified as one of the potential adaptive uses of saline groundwater. In 1997, the Australian Centre for International Agricultural Research organised the first national workshop on inland saline aquaculture. Following this workshop, the Fisheries Research and Development Corporation (FRDC) supported preparation of an R&D plan for developing commercial saline aquaculture in Australia (Allan, Dignam & Fielder, 2001).
The interest in inland saline aquaculture has occurred because of the potential advantages and benefits it offers. These include: • Providing opportunities to increase aquaculture production in Australia that, like in many other countries, is limited by a shortage of suitable coastal sites with the necessary characteristics for successful production. Such sites are often reserved for housing or tourist related development, or judged to be of too high environmental value for aquaculture while ‘unwanted’ land and water affected by salination provides opportunities for inland saline aquaculture. • Establishment cost savings attributed to the low cost of land relative to coastal locations. • In some situations, aquaculture species growth advantages are provided by the constant elevated water temperature of saline groundwater over production in ambient water temperature conditions. • Ability to operate production facilities in a bio-secure manner due to the location and water supply from deep aquifers being isolated from parasites and diseases and their vectors.
These factors combine to promote interest in finding ways to exploit saline groundwater resources for commercial aquaculture.
1 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
1.2. Water Sources Partridge et al. (2008) suggested three main sources of saline water for aquaculture. 1. Primary salinised lakes – Few saline lakes are considered to be suitable for aquaculture as the majority of these are ephemeral in nature and subsequently highly variable in salinity and volume (Gooley et al., 1997). Allan et al. (2001) identified two lake systems with potential for mariculture. However, eight of the 15 individual lakes selected are classified as ‘wetlands of significant importance’ under the Ramsar convention and it was concluded that the opportunities for aquaculture in such lakes is limited. 2. Interception of saline groundwater from shallow (<25 m) aquifers – Surface and subsurface drainage systems and bores are built to control groundwater discharge in shallow aquifers. The majority of saline groundwater interception in Australia occurs within the irrigated horticultural areas of the Murray Darling Basin. The water is pumped to disposal basins where it is mostly lost through evaporation. The location of inland saline aquaculture operations near these disposal basins provides the opportunity to utilise a number of different water sources for fish production, thereby reducing the risk of a complete loss of water flow. 3. Interception of saline groundwater from deep (>25 m) aquifers – Saline groundwater from deep aquifers is typically warmer, geochemically mature and is generally a more reliable supply compared with shallow aquifers. However, the yields and salinities from such aquifers may still be variable and dependent on their hydrogeology. The mining industry offers some opportunities for aquaculture using water extracted from deep aquifers (e.g. utilising open-cut mines) or water discharged to storage dams following methane extraction from coal seams.
1.3. Water Quality The suitability of inland saline groundwater for aquaculture is dictated by several parameters (Jenkins, 1997) that are discussed in detail by Partridge et al. (2008): • Salinity. This can vary with depth within an aquifer and between groundwater bores even over short distances. However, many groundwater sources provide acceptable salinity for the culture of euryhaline species (i.e. species that can adapt to a wide range of salinities). • Ionic composition. This can vary considerably from the composition of seawater. Soils have a very high affinity for potassium so it is typically deficient in groundwater. Potassium has an important function in many physiological processes and deficiency of this ion has caused mortality of finfish cultured in groundwater. Other elements that may affect the suitability of groundwater include sulphate, magnesium, calcium and bicarbonate as well as trace elements and other metal ions in solution. The effects of all differences in ionic composition found in saline water sources have not been elucidated.
2 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
• pH. The optimum pH for fish production is considered to be between six and nine. Many groundwater sources have pH values below six. The cost of treating (buffering) large volumes of acidic water to make it suitable for aquaculture production is considered to be prohibitive for high water use systems. • Contaminants and toxins. There are a number of chemical contaminants (eg. nutrients, heavy metals, herbicides, insecticides and organic pollutants) and biological contaminants (eg. diseases and competing species) that are known to affect the quality of surface waters and shallow aquifers.
1.4. Inland Saline Aquaculture in Australia To date several Australian states have investigated the potential for inland saline aquaculture. Each of these investigations has targeted a production approach that has been identified as being most applicable to the prevailing saline groundwater situation and infrastructure available.
1.4.1. Victoria (Modified from http://www.australian-aquacultureportal.com/saline/vic.html)
The Victorian Government through the Department of Primary Industries is strongly supporting an integrated agri-aquaculture systems (IAAS) approach to inland aquaculture development. Inland saline aquaculture is recognised as a possible component of IAAS. Unlike other states, the primary focus of Victorian IAAS (and inland saline aquaculture) R&D is not solely the development of an aquaculture industry or aquaculture business opportunities, but rather farm diversification and the sustainable use of water resources by rural communities.
In Victoria, the focus has been on shallow aquifer and surface saline groundwater, using a range of culture techniques including cages, tanks and small ponds. The IAAS resource handbook (Gooley and Gavine, 2003) provides a comprehensive background to investment in IAAS (including inland saline aquaculture) in Victoria. Included is information on setting up an aquaculture operation and risks and constraints associated with IAAS (and inland saline aquaculture).
Two major state government initiatives have provided funding support for IAAS research and each initiative funded a single IAAS project: • The Our Rural Landscape (ORL) initiative’s core aim is to generate the scientific knowledge and policy tools necessary for Victoria’s agri-food sector to pursue strong economic growth, while protecting the environmental base that sustains production. One of the many objectives is to substantially increase the value and sustainability of water used commercially in Victorian landscapes. • The Ecologically Sustainable Agriculture Initiative (ESAI) projects are aimed at encouraging productive and sustainable agriculture, focusing on biodiversity,
3 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
greenhouse issues, environmental management, recycling and small farm enterprise issues.
The Multiple Use of Farm Water to Produce Fish report (Gooley et al., 2002) provides the outcomes of a number of IAAS trials, one of which includes a trial to grow finfish in a cage utilising saline water. Further investigations have specifically targeted inland aquaculture including: • a trial to produce Artemia in conjunction with commercial production of salt at Pyramid Hill (ESAI). • an investigation into integrated fish production from a shallow aquifer saline water supply on a dairy property (ORL).
Species investigated for inland saline aquaculture in Victoria include brine shrimp (Artemia), silver perch (Bidyanus bidyanus), rainbow trout (Onchorynchus mykis) and Murray cod (Maccullochella peelii).
1.4.2. Queensland (Modified from http://www.australian-aquacultureportal.com/saline/qld.html) The Queensland Department of Primary Industries and Fisheries are investigating the potential for inland saline aquaculture in several regions where groundwater salinity is suitable for prawn production. Although not developed in Australia, the inland production of marine prawns such as the black tiger prawn (Penaeus monodon) and the white shrimp (Liptopenaeus vannamei) is growing rapidly overseas. In Queensland, research effort has focused on determining the suitability of groundwater for prawn farming at salinities ranging from almost fresh to full strength seawater. In 2002, these studies were applied to a series of trial ponds in collaboration with an existing redclaw (Cherax quadricarinatus) farm at Bauple, about 2½ hours drive north of Brisbane.
Investigations have commenced to assess the suitability for aquaculture to utilise waste groundwater produced as a by-product during coal seam gas (methane) extraction. This R&D is being undertaken in collaboration with an energy company that operates power generation systems in the Darling Downs where extensive coal seam gas resources are being exploited. Early results with mulloway cultured in a floating raceway system suggest that potassium supplementation is required but that adequate levels can be achived by adding it to the groundwater that is held in large storage dams where the aquaculture production systems are located.
1.4.3. Western Australia (Updated extracts from http://www.australian-aquacultureportal.com/saline/wa.html) The Western Australian State Government has expressed a commitment to support the development of an aquaculture industry in Western Australia (Industry Strategic Review).
4 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
However WA Fisheries no longer commits resources to inland saline aquaculture research nor does it actively promote inland saline aquaculture development in regional Western Australia. The Western Australian inland saline aquaculture research effort is comprised of researchers from Challenger TAFE Aquaculture Development Unit (ADU), CY O’Conner TAFE, Western Australia Department of Agriculture and Murdoch University. Collectively, these organisations make up the Inland Saline Aquaculture Applied Research Group (ISAARG).
Researchers involved in ISAARG have a range of complementary research projects underway and have adopted a cautious approach to industry development. However, group members are convinced that inland saline aquaculture has the potential to make a significant contribution to salinity management. Particular effort has been directed towards development of the Semi-Intensive Floating Tank System (SIFTS) patented by McRobert Aquaculture Group and the ADU. SIFTS are proposed as a production technology suitable for commercial aquaculture in existing or purpose built water bodies and recent versions are being trialled in protected coastal waters.
Researchers have been quick to identify the potential for inland saline aquaculture to operate in association with government sponsored engineering projects such as those initiated in 1997 under the State Salinity Action Plan by the Department of Agriculture. The Rural Towns Program has been assisting rural towns to reduce the impact of rising groundwater tables on rural infrastructure. This is being achieved by pumping saline water from beneath threatened towns and diverting it into evaporation basins.
A Regional Development Policy developed by the Department of Local Government and Regional Planning has identified the need to develop new regional industries and diversified regional economies and highlighted aquaculture as a potential new industry.
Commercial projects operating in Western Australia include: • Trout is being produced in small quantities either in static farm dams or small recirculation systems. Two groups of agricultural farmers are involved, the Salt Water Trout Alliance and the Western Inland Fisheries Cooperative. • Ornamental fish are being produced by small scale inland saline aquaculture in the Gascoyne region.
Species investigated for inland saline aquaculture in Western Australia include barramundi (Lates calcarifer), mulloway (Argyrosomus japonicus), snapper (Pagrus auratus), black bream (Acanthopagrus butcheri), rainbow trout (Oncorhynchus mykiss), ornamental fish (range of species, mostly live bearers) and black tiger prawn (Penaeus monodon).
1.4.4. New South Wales (Updated extracts from http://www.australian-aquacultureportal.com/saline/nsw.html) The New South Wales State Government has made a commitment to support R&D to identify and develop commercial inland saline aquaculture opportunities. A senate committee report
5 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
on aquaculture led to the preparation of a State Aquaculture Policy and the allocation of funding for an Aquaculture Initiative. Through this initiative, the New South Wales Government, in partnership with Murray Irrigation Limited (MIL), funded a $1 million project to establish the Inland Saline Aquaculture Research Centre (ISARC) at Wakool near Swan Hill on the Murray River. MIL operate the Wakool-Tullakool Subsurface Drainage Scheme at Wakool, NSW. This is the largest saline groundwater evaporation scheme in Australia, pumping approximately 13,000 ML per annum of saline groundwater to 1,600 ha of evaporation ponds. ISARC was constructed in a corner of one of the evaporation ponds. This facility was opened in May 2002 and has supported investigations on the survival and growth of several species in saline groundwater, including silver perch (Bidyanus bidyanus), mulloway (Argyrosomus japonicus), black tiger prawns (Penaeus monodon), kuruma prawns (Penaeus japonicus), Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), Sydney rock oysters (Saccostrea glomerata), and snapper (Pagrus auratus) (Fielder et al., 2001; Allan, 2004; Doroudi et al., 2004; Doroudi et al., 2006). This research has identified that the best opportunity for commercial inland saline aquaculture development in southern New South Wales is the large-scale farming of rainbow trout. Currently, the major limitation to inland saline aquaculture in this area is the lack of saline groundwater following a number of years of drought that has caused the water table to retreat progressively deeper (Allan et al., 2008).
1.4.5. South Australia SARDI has previously investigated the use of saline groundwater for aquaculture at CPISARC. This facility was established in collaboration with the Coorong District Council and the research was conducted from 1997 to 2003. At this location, the source of saline groundwater was a shallow aquifer 1–2 m below the soil surface in an area impacted by dryland salinity that is extensive in this region. The volume of saline groundwater available at this location was limited, and water temperature varied seasonally and was similar to ambient soil temperature (Flowers and Hutchinson, 2004a, 2004b). Species cultured at CPISARC were mulloway (Argyrosomus japonicus), snapper (Pagrus auratus), brine shrimp (Artemia spp), oysters (Crassostrea gigas), seaweed (Ulva sp.) and microalgae (Dunaliella salina).
SARDI has identified that saline groundwater from SIS in the Riverland region offers an opportunity for aquaculture, including: • relatively high volume (350 L/sec) of water consistently available • stable elevated water temperature (20–22oC) and moderate salinity (19–21 g/L) • water supply infrastructure is established and more SISs are planned in the region.
This situation differed to other sates where available saline groundwater was supplied from evaporation ponds from a large subsurface drainage scheme (New South Wales) or naturally occurring saline lakes (Western Australia). Alternatively, very low salinity groundwater (2–5 g/L) is being investigated in Queensland while inland aquaculture in Victoria is concentrated on the multiple use of freshwater in IAAS. R&D activities undertaken to investigate the potential of saline groundwater from SISs for aquaculture is the subject of this report.
6 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
1.5. South Australia’s Salt Interception Schemes Rising salinity in the River Murray has long been recognised as a major problem, particularly for South Australia which has a heavily reliance on the River Murray to supplement its water supply. In a dry year the River Murray supplies up to 90% of the state’s domestic and industrial water (Anon., 2008). Predictions by the Murray Darling Basin Authority (MDBA) indicate that without further intervention, by 2050 the salinity at the benchmark site of Morgan will exceed the World Health Organisation’s desirable level for drinking water of 800 EC for 50% of the time. (http://www.sawater.com.au/SAWater/Environment/TheRiverMurray/Salinity.htm).
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Figure 1.1. Salt interception schemes in South Australia (Source SA Water).
8 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
The South Australian State Government is committed to meet salinity targets through the implementation of SIS (Figure 1.1). An SIS involves the large scale pumping of groundwater to intercept groundwater flows from natural aquifers, irrigation drainage or river regulating structures. SISs are thought to be the most economically viable option for salinity control (Anon., 2008).
In the 1980s, it was found that saline groundwater (salinity = 30,000 EC, 21 g/L) inflows to the Murray River in the Woolpunda reach area upstream from Waikerie add between 200 and 250 tonnes of salt each day. The Woolpunda SIS was designed to pump this saline groundwater from the naturally occurring groundwater mounds of the Murray Group Aquifer with the objective to lower the level of groundwater to below river pool level to prevent the saline groundwater from discharging into the river (Figures 1.2a and 1.2b). A total of 49 bores on both sides of the river were installed to pump 165 L/sec of saline groundwater with each bore pumping 2–10 L/sec. The bores are typically about 100 m deep (Anon., 2008).
a. b.
Figure 1.2.a. Inflow of saline groundwater into the River Murray without implementation of Woolpunda SIS. (Source SA Water) Figure 1.2.b. Interception of saline groundwater by bores of the Woolpunda SIS. (Source SA Water)
The Woolpunda SIS was commissioned in 1990 and was the first scheme in South Australia. In 1992, Waikerie Stage 1 was added and then the privately operated Qualco-Sunlands SIS commenced operating in 2001. After ongoing review and investigations, the Waikerie Stage 2A scheme was commissioned in 2003. Saline groundwater from all of these SISs is pumped to the Stockyard Plain Disposal Basin (SPDB, Figures 1.3a and 1.3b) within a land-holding of approximately 1875 hectares located about 12 km south west of Waikerie. More recently in the Riverland region, the Bookpurnong SIS was commissioned in 2005 and the Loxton SIS was commissioned in 2007 with these systems discharging water into the Noora Disposal Basin (Figure 1.1) near Loxton (Anon., 2008).
The causes and solutions for saline groundwater discharge in the Waikerie SISs (Stage 1 and 2A) are entirely different to the Woolpunda SIS. Beneath the Waikerie irrigation district a steep-sided groundwater mound has built up, caused by irrigation drainage (Figure 1.4a). The relatively fresh drainage water pressurises the deep Mannum formation aquifer causing displacement of highly saline groundwater
9 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
(21 g/L) upward into the alluvium and subsequently into the river (Figure 1.4a). Waikerie Stage 1 SIS was designed to reduce pressure on the Mannum Formation Aquifer and achieved this using 17 bores located adjacent to the river to control groundwater accessions from both sides of the river (Figure 1.3b). Subsequently, Waikerie SIS Stage 2A was constructed comprising an additional two bores to intercept an extra 35 tonnes of salt per day and in 2008 construction started on Waikerie Lock 2 SIS comprising and an additional six bores.
SISs in South Australia are estimated to prevent over 400 tones of salt from entering the River Murray every day (Anon., 2008). Prior to the implementation of the Woolpunda and Waikerie schemes, the Murray River was carrying up to 250 tonnes per day of salt past Woolpunda and 100 tonnes a day past Waikerie. Recent surveys show these salinity levels have decreased to less than 10 tonnes a day in each area (Anon., 2008). a. b.
Figure 1.3.a. Entry point at SPDB for approximately 30 ML of saline groundwater each day from SISs in the Waikerie area, South Australia. Figure 1.3.b. Overview of SPDB, South Australia.
a b
Figure 1.4.a. Inflow of saline groundwater into the River Murray without implementation of Waikerie SIS. Figure 1.4.b. Interception of saline groundwater by bores of the Waikerie SIS (Source Peter Forward, SA Water).
10 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
1.5.1. Limits on Disposal Basins SISs are now part of the Murray Darling Basin landscape and are currently transferring up to 100 million litres per day of saline ground water to disposal basins. The cost of establishing and operating SISs is approximately $10 million per annum (pers. comm. Peter Forward, SA Water) and disposal of the volume of water intercepted represents a limitation to future expansion of these schemes.
During planning for future expansion of SISs, it has emerged that there is considerable community objection towards the establishment of new disposal basins and this is a significant issue to be addressed by salinity managers. Local landholders and other community stakeholders have expressed objection to sacrificing cropping or native bushland to establish more disposal basins.
The development of commercial aquaculture enterprises will make productive use of the non-utilised Waikerie SIS groundwater waste stream that provides up to 30 million litres per day of water at a relatively constant salinity (19–20 g/L) and temperature (20–22oC).
SARDI identified a need to develop effective methods to remove nutrients and suspended solids from water discharged from inland aquaculture facilities using saline groundwater from SIS. This issue may become significant if commercial aquaculture operations aligned to SISs in the Riverland region are established.
1.6. Waikerie Inland Saline Aquaculture Centre On 24 and 25 June 2004, a workshop was held to summarise previous inland saline aquaculture R&D, conducted by SARDI at the CPISARC, and to present this SIS groundwater aquaculture project to stakeholders. A key outcome of this workshop was the requirement of the SIS managers—Murray Darling Basin Authority (MDBA)—and operator (SA Water) that the design of any aquaculture facility needed to incorporate the ability to operate ‘off-line’ from SIS groundwater supply for intervals of 2–3 days. This requirement was to protect aquaculture operations from periods of poor water quality (i.e. high turbidity) following periodic maintenance operations that need to be conducted to optimise water flow through the SIS. This planned maintenance is undertaken at three, six and 12 month intervals and involves chemical dosing (sulphamic acid and glycolic acid) of bores and pipeline pigging to remove iron bacteria that gradually builds up inside pipes and restricts water flow through the system. These operations adversely affect water quality and turbidity for up to six hours after completion. It was recommended that design of an aquaculture facility should include capacity for on-site water storage to provide the requirements for up to one week of water use under modified operations while isolated from the supply of SIS groundwater.
The semi-intensive aquaculture system installed at WISAC was designed following an overseas study tour of commercial and R&D facilities that use saline groundwater for aquaculture (Appendix A). This 21 day tour included visits to five commercial farms and three R&D facilities in the USA, and 13 commercial farms and three R&D facilities in Israel. Initially it was proposed to install an intensive aquaculture system and a semi-intensive system as both approaches were assessed to be suitable to utilise
11 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture available SIS groundwater for aquaculture. The need to investigate alternative lower capital cost intensive aquaculture systems than those currently operating in Australia had previously been highlighted (Hutchinson et al., 2004). A potentially suitable intensive aquaculture system for evaluation at WISAC was identified during this study tour. During site planning, space and provision of services (i.e. water supply, electricity and communications) were made; and during site development, elements to support the system (i.e. lined effluent pond, additional back-up generator capacity) were installed. Unfortunately, insurmountable difficulties were encountered relating to restrictions for international procurement through PIRSA state government. These matters could not be resolved within the time available for this project and a decision was made to only install the semi-intensive aquaculture system at WISAC.
The semi-intensive system designed and constructed at WISAC (Figure 1.5) incorporated the following major components: • intake and discharge connections to the Woolpunda SIS pipeline • header tanks (2 x 250 kL) providing storage for 500 kL of SIS groundwater for up to seven days restricted water supply • automated system to monitor turbidity of SIS groundwater and isolate WISAC during periods of high turbidity
• degassing tower to reduce the concentration of dissolved CO2 and increase the concentration of dissolved oxygen in all incoming SIS groundwater • gravity flow of ‘new’ SIS groundwater from header tanks to culture tanks during normal operation • three metal walled and plastic lined production tanks (9.4 m diameter x 1.1 m deep, 70 kL) with solids separator and aspirator for oxygenation and water circulation • six fibreglass nursery tanks (6 m diameter x 1.0 m deep, 10 kL) • isolated lined solids collection pond • shade structure covering all tanks • two lined primary settlement ponds • one lined secondary settlement pond • pump station housing submersible pumps and level sensors to control the return of water to the SIS pipeline and to recirculate water back to production and nursery tanks • offices, staff amenities and laboratory buildings • dissolved oxygen monitoring and control system • water use monitoring system • concrete wash down area.
12 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
Figure 1.5. General layout plan of the aquaculture system and support infrastructure at WISAC.
13 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
The principle of operation for the semi-intensive aquaculture system was to supply both ‘new’ and ‘re-use’ SIS groundwater to each production tank to maximise the re-use of water so as to optimise the water temperature advantage while maintaining suitable water quality through separation and settlement of solid wastes and water exchange. During normal operation, water discharged from the production tanks were flushed into a waste pond each day through a ‘double drain’ type solids separator (Eco-Trap™, AquaOptima, Trondheim, Norway) that concentrated uneaten feed and faeces using a swirl separator from these solids. SIS groundwater discharged from all fish tanks at WISAC flowed into two primary settlement ponds (23.5 m x 18.25 m x 1.8 m deep, Figure 1.6) that were plastic lined (1 mm thick high density polyethylene, Fabtech Pty Ltd, Adelaide). Both of these settlement ponds connected to a common secondary settlement pond (16 m x 28 m x 1.4 m deep) that connected to a pumping station. This station was divided into two caissons. One caisson housed submersible pumps (2 x Flygt Model 3171) selected to pump water back into the SIS pipeline against approximately 16 m head pressure. The second caisson housed submersible pumps (2 x Flygt Model 3102) to return water back to the production tanks for re-use. At approximately six month intervals, each of the settlement ponds were drained and accumulated sludge was pumped into a tanker (Figure 1.7) for disposal at a council approved facility.
A 200 mm take-off was installed (SA Water) to supply groundwater to WISAC from the Woolpunda SIS pipeline. A similar take-off was installed to allow pumping of water back into the pipeline. All SIS groundwater used at WISAC passed through a packed column degasser before entering two storage tanks from where it flowed by gravity to nursery and production tanks. A packed column degasser (3.2 m x 1.55 m diameter, 6,000 L, Figure 1.8) was installed to reduce the high concentration of dissolved CO2 in SIS groundwater before supply of water to finfish culture tanks at WISAC. This degasser was ventilated by a counter current of air provided by inline fans to achieve a suggested ratio of 10:1 flow of air to flow of water (Summerfelt, 2000). The degasser allows the passage of air and water through a 4 m3 bed of open structured degassing media (Tellerettes®, Ceilcote Air Pollution Control, Stongsville, Ohio, USA) designed to maximise creation of surface area on drops from where the exchange of gases between air and liquid can occur. Initial construction of the degassing tower used a drip plate to distribute falling water over the degassing media bed. After approximately four months operation this drip plate was replaced with five spiral full flow 90o twister nozzles (Sprayflo Pty Ltd, Hawthorne, Victoria) to more evenly distribute the water and improve efficiency.
14 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
Figure 1.6. Primary settlement ponds for treatment of SIS groundwater before re-use or return to the SIS pipeline.
Figure 1.7. Contractor pumping sludge from a primary settlement pond at WISAC.
15 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
Figure 1.8. Degassing tower installed to reduce the concentration of dissolved CO2 in SIS groundwater before use for finfish culture at WISAC.
A turbidity system (ABB Limited, Stonehouse, Gloucestershire, UK) was installed on separate side streamed small diameter pipe providing a small constant flow of SIS groundwater. The system included a turbidity sensor—output range 0–100 nephelometric turbidity units (NTU)—with maximum acceptable turbidity and alarm set at 40 NTU. The system provided a wall mounted analyser with a visual display and automated control of a 200 mm wafer butterfly valve (Australian Valve and Filter Industries Pty Ltd, Thomastown, Victoria, Australia) fitted with a 240 v electric actuator with manual over-ride (Electro- Torque OM – 6-4, Australian Valve and Filter Industries Pty Ltd, Thomastown, Victoria, Australia) to stop water intake to WISAC during periods of high turbidity of SIS groundwater. The system communicated with a data acquisition and control system—EDAC 700, Electronic Data Acquisition and Control (EDAC) Electronics Ltd, Christchurch, New Zealand—to send a pre-recorded message to staff alerting them to the high turbidity situation. A pilot light on a control panel located in the site laboratory building was energised to indicate high turbidity and could be manually cancelled by staff after recognition of the situation.
16 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
An oxygen monitoring and control system (Analogue and Digital Services Pty Ltd, East Fremantle, Western Australia) was located in a laboratory building at WISAC. This system consisted of: • control box housing a programmable logic controller (PLC) • operating system to provide monitoring of levels of dissolved oxygen in each tank via a probe (OxyGen probe, Dryden Aqua Ltd, Edinburgh, Scotland) located within the effluent water standpipe of each production tank • output relays to control oxygen injection via the Force 7 aspirator (Acqua & Co®, Via Augera, Italy) located in each production tank • output to call an alarm dialler (EDAC 700).
A personal computer (PC) was connected to the PLC with software installed to provide a visual display of all dissolved oxygen and water temperatures, calibration values and faults, and to set upper and lower oxygen control and alarm levels. The PC also provided capacity to log all dissolved oxygen and water temperature data via a serial communication link.
Water usage at WISAC was measured by a MagMaster™ electromagnetic flowmeter (ABB Limited, Stonehouse, Gloucestershire, UK) installed within the 200 mm inlet pipeline supplying SIS groundwater to WISAC. Within the site laboratory a wall mounted keypad display showed water usage (L) and flow rate (L/sec). Total water use was recorded at the start of each day.
1.6.1. Pilot Commercial Scale Production Tanks At WISAC ,three metal walled, plastic lined 70,000 L production tanks (9.4 m diameter x 1.1 m deep, Aquamate Tanks, Adelaide, Figure 1.9) were installed under a shadecloth roof structure (VP Structures, Yatala, Queensland). Each tank was supplied with new and re-used SIS water from inlets located at opposite sides of each tank. New SIS water was gravity fed to production tanks from two 250,000 L holding tanks (Pioneer Water Tanks, Adelaide, South Australia) positioned on an elevated mound. Re-use SIS water had been previously used in fish production tanks and had then passed through primary and secondary settlement ponds for suspended solids removal prior to being pumped back to the production tanks. This water was utilised to maximise the available water temperature advantage of the SIS groundwater and also to increase the finfish production that can be achieved from the limited volume of water available from the SIS.
Each production tank was fitted with a centrally located Eco-Trap™ (AquaOptima, Trondheim, Norway) particle trap. This ‘double drain’ component was connected to a solids collector positioned to the side of each tank (Figure 1.10). The operating principle of these components was to separate effluent water into two waste streams. One stream consisted of approximately 90% of the water flow that contained approximately 10% of the waste solids. This flow exited the centre of the drain through a coarse screen. The remaining 10% of the water flow was taken from the bottom layer of water in the centre of the tank where 90% of waste solids accumulated. This separate smaller flow connected to the external mounted
17 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
sludge collector that uses the principle of swirl separation to concentrate the uneaten food and faeces from the finfish culture tank while allowing water to be returned to the culture system.
At WISAC, technical staff released the concentrated sludge in the bottom of the collector 1–2 times each day. The sludge was diverted to a purpose built lined pond where it was accumulated in isolation from the culture system until it was pumped into a collection tanker for offsite disposal.
Re-used SIS New SIS water inlet water inlet Solids separator Water level standpipe and Oxygen drain from tank supply
Figure 1.9. Production tank G1 used to assess and demonstrate production of mulloway in a semi- intensive aquaculture system at WISAC.
Figure 1.10. Eco-Trap™ (AquaOptima, Trondheim, Norway) particle trap that collected uneaten food and faeces from a 70 kL production tank at WISAC.
18 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
Oxygen was supplied to each production tank from G size (8.9 m3) cylinders of industrial grade oxygen fitted with regulators, pressure and contents gauges, and controlled by the monitoring and control system via a solenoid valve. Oxygen was transferred into culture water by micronisation of bubbles by a Force 7 (Acqua & Co®, Via Augera, Italy, Figure 1.11) dissolution device installed into each production tank. Using this device, oxygen was introduced through a venturi located in the housing behind the impeller. Micronised bubbles were efficiently mixed into solution due to the turbulence and cavitation induced by the impeller that also produced additional water current in the tank that assisted with the removal of solids (i.e. uneaten food and faeces). An OxyGen dissolved oxygen monitoring probe (Dryden Aqua Ltd., Edinburgh, Scotland) was located in the effluent stream of each production tank and was connected to the oxygen monitoring and control system (Analogue and Digital Services, East Fremantle, Western Australia) installed at WISAC. High and low dissolved oxygen set points controlled addition of oxygen to tanks and provided alarm functions.
After approximately six months of operation, improved oxygenation efficiency was achieved using a combination of flow meter controlled continuous ‘background’ oxygenation provided by four Wedge-Lock™ ceramic diffusers (Point Four Systems Inc, Coquitlam, BC, Canada) positioned in each tank. Additional oxygenation in response to fluctuations in dissolved oxygen following feeding and during the night was provided via the oxygen monitoring and control system operating the Force 7 located in each tank.
Figure 1.11. Force 7 oxygen dissolution device installed in each production tank at WISAC for oxygenation and increased water flow.
19 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
1.7. References Allan, G.L. 2004. Description of facilities and R&D activities, Inland Saline Aquaculture Research Centre, Wakool, NSW. Development of Industrial Scale Inland Saline Aquaculture: Coordination & Communication of R&D in Australia. NSW Fisheries. Allan, G.L., Banes, B. and Fielder, S. 2001. Developing commercial inland saline aquaculture in Australia: Part 2. Resource inventory and assessment. Canberra, FRDC Project No. 98/335. NSW Fisheries Final Report Series, No 30, 116 pp. Allan, G.L., Dignam, A. and Fielder, S. 2001. Developing commercial inland saline aquaculture in Australia: Part 1. National R&D plan. Canberra, FRDC Project No. 98/335. NSW Fisheries Final Report Series, No 31. Allan, G.L., Heasman, H. and Bennison, S. 2008. Development of industrial-scale inland saline aquaculture: Co-ordination and communication of R&D in Australia. FRDC Project No. 2004/241. NSW Department of Primary Industries, Fisheries Final report Series No. 100, 245 pp. Anon. 2008. South Australia’s Salt Interception Schemes. In: 2nd International Salinity Forum, Salinity, water and society – Global issues, local action. Adelaide Convention Centre, Adelaide SA. Information booklet – Field Trip No 1, Riverland, Wednesday 2 April. Doroudi, M., Allan, G.L. and Fielder, S. 2004. Two-year R&D program on inland saline aquaculture 2001–2003. Prepared for NSW Fisheries, Murray Irrigation Ltd and Department of State and Regional Development. Doroudi, M.S., Fielder, D.S., Allen, G.L. and Webster, G.K. 2006. Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temmink and Schlegel) in inland saline ground water. Aquaculture Research 37: 1034- –1039. Fielder, D.S., Bardsley, W.J. and Allan, G.L. 2001. Survival and growth of Australian Snapper, Paris auratus, in saline groundwater from inland New South Wales, Australia. Aquaculture 201: 73–90. Flowers, T.J. and Hutchinson, W.G. 2004a. Preliminary studies towards the development of an aquaculture system to exploit saline groundwater from salt interception schemes in the Murray Darling Basin. CNRM Final Report 2002/015. South Australian Research and Development Institute (Aquatic Sciences), Adelaide, 27 pp. Flowers, T.J. and Hutchinson, W.G. 2004b. Productive uses for saline groundwater using semi-intensive integrated aquaculture. CNRM Final Report 2002/016. South Australian Research and Development Institute (Aquatic Sciences), Adelaide, 81 pp. Gooley, G.J. and Gavine, F.M. 2003. Integrated agri-aquaculture systems. A Resource Handbook for Australian Industry Development, Rural Industries Research and Development Corporation Publication No 03/012 Project No MFR-2A, 189 pp. Gooley, G., Ingram, B. and McKinnon, L. 1997. Inland saline aquaculture—A Victorian perspective. In: Smith, B. and Barlow, C. Editors. Inland Saline Aquaculture Workshop.
20 Chapter 1 – General introduction to the use of groundwater for inland saline aquaculture
Proceedings of a workshop held on 6 and 7 August 1997 in Perth Western Australia. ACIAR Proceedings No. 83, 61 pp. Gooley, G.J., McKinnon, L.J., Ingram, B.A. and Gasior, R. 2002. Multiple use of farmwater to produce fish. RIRDC Publication No 00/182 Project No DCM-1A. http://www.rirdc.gov.au/reports/Ras/00-182.pdf Hutchinson, W.G., Jeffrey, M., O’Sullivan, D., Casement, D. and Clarke, S. 2004. Recirculating aquaculture systems: Minimum standards for design, construction and management. Prepared for the Inland Aquaculture Association of South Australia Inc. Jenkins, G.I. 1997. Potential of inland saline aquaculture of fishes. In: Smith, B. and Barlow, C. Editors. Inland Saline Aquaculture Workshop. Proceedings of a workshop held on 6 and 7 August 1997 in Perth Western Australia. ACIAR Proceedings No. 83, 61 pp. Partridge, G.J., Lymbery A.J., and George, R.J. 2008. Finfish mariculture in inland Australia: A review of potential water sources, species and production systems. Journal of the World Aquaculture Society 39: 291–310. Summerfelt, S.T. 2000. Carbon dioxide. In: Stickney, R.R. Encyclopedia of aquaculture. John Wiley & Sons Inc. New York 1088 pp.
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22 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco–Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin.
Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco- Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.1. Summary The Woolpunda, Waikerie and Qualco-Sunlands SIS in the Riverland region of South Australia has been identified as a source of saline groundwater with potential to support commercial aquaculture due to potential advantages this waste water source provides, including: • constantly elevated water temperature that can be used to promote fish growth in winter • a high volume of water available and water supply infrastructure established to support significant commercial production • elevated salinity that is likely to support the culture of euryhaline finfish species • adjacent land that may be able to be used to establish commercial aquaculture production facilities.
It is known that use of saline groundwater for culture of marine and estuarine fish and crustacean species may result in retarded growth, or total mortality in extreme cases, due to differences in the ionic composition of groundwater as compared to seawater. Due to this concern, a 12-month monitoring program of saline groundwater from each of the major sections of the Woolpunda, Waikerie and Qualco-Sunlands SISs and the inflow to SPDB was undertaken as there was no detailed information of the composition and temporal changes of SIS groundwater.
This program identified that bicarbonate and calcium were in excess for all SIS pipeline sections investigated compared to equivalent salinity seawater. In samples taken from the Woolpunda and Waikerie SISs and at the discharge point of the SPDB, the levels of sodium, chloride and sulphate were all at similar levels to those found in equivalent salinity seawater. The levels of pH and magnesium were lower in all SIS groundwater samples than in equivalent salinity seawater.
Potassium was deficient in all SIS sections and at the discharge point of the SPDB. The mean level of potassium in groundwater from the SIS sections varied from 35.5% to 44.3% compared to the concentration of potassium in equivalent salinity seawater.
The levels of most components of the SIS groundwater tested were relatively stable over the 12-month sampling period, apart from a few conspicuous changes at a single sampling time at a specific location, although there was moderate variability between the components of SIS groundwater between pipeline sections. The Qualco-Sunlands SIS had the lowest sodium and
23 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco–Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin.
chloride levels and thus salinity, and the highest calcium, fluoride, sulphate and silica levels, and potassium to chloride ratio.
2.2. Background Inland saline groundwater has been identified as a potential resource for aquaculture development (Allan et al., 2001a,b) and the Woolpunda, Waikerie, Qualco-Sunlands SIS in the Riverland region of South Australia is of particular interest as it has: • elevated water temperature (>20oC) that can be used to promote fish growth in winter • a high volume of saline groundwater available • elevated salinity that is likely to support the culture of euryhaline finfish species (i.e. species that can tolerate a wide range of salinities and typically occur in estuaries) and possibly marine species • adjacent land that may be able to be used to establish commercial aquaculture production facilities.
However, previous growth trials with marine and estuarine fish and crustacean species have demonstrated that growth may be retarded, or in extreme cases total mortality may occur, due to differences in the ionic composition of groundwater as compared to seawater (e.g. Fielder et al., 2001; Partridge, 2002; Partridge and Creeper, 2004). While the ionic composition of seawater (Table 2.1, after Goldberg, 1963) varies only slightly between locations, deficiencies and excesses of major ions present in saline groundwater vary considerably between sources. However, there is a common deficiency in potassium (K+) in groundwater due to the high affinity of soil for this element (Partridge et al., 2008).
A reduced level of K+ in saline groundwater has been identified as the principal factor implicated in the reduced performance of fish cultured in these water sources. Fielder et al. (2001) reported that juvenile snapper lost equilibrium of buoyancy and floated upside down, did not feed, and died within four days following transfer from oceanic seawater diluted to the same salinity (19 g/L) as saline groundwater from evaporation ponds of the Warkool- Tullakool Subsurface Drainage Scheme in western New South Wales. The level of K+ in this groundwater has been identified as 9.2 mg/L, equal to only 4.5% of that present in equivalent salinity seawater (203 mg/L). Comparable growth performance was achieved when this groundwater was supplemented with K+ to 60–100 % (>134 mg/L) of the level present in equivalent salinity seawater. These authors also investigated the ratio of potassium to chloride (K+:Cl-) and determined that snapper survived and grew when this ratio was greater than 0.007. However, maximum growth was achieved when K+:Cl- was greater than 0.01 and the fish died if the ratio was less than 0.007. Partridge and Creeper (2004) report the incidence of skeletal myopathy in barramundi (Lates calcarifer) that had died in bio-assay trials conducted in K+ deficient saline groundwater in Western Australia. Symptoms described include degeneration and necrosis of skeletal muscles, hyperplasia of branchial chloride cells and renal tubular necrosis. Also reported were hypernatraemia and hyperchloriaemia of blood plasma and low levels of muscle K+, all attributed to low levels of K+ in the culture water.
24 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco–Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin.
As minimal testing on the ionic composition of SIS groundwater water had occurred in South Australia (Allan et al., 2001b), the aims of this component of the project were to: • characterise the key elements of groundwater from each of the main sections of the Woolpunda, Waikerie, Qualco-Sunlands SIS and their point of discharge at the SPDB • determine how these elements change over a 12 month period based on a monthly sampling program • use the data collected to better assess the potential of this SIS groundwater to be used for aquaculture in the future.
2.3. Methods
2.3.1. Water Sampling From September 2004 to August 2005, water samples were taken monthly from the Woolpunda, Waikerie and Qualco-Sunlands SISs. From November 2004 to August 2005, a water sample was also taken from the discharge point at the SPDB, at this point the water being a mix from all three SISs (Figure 2.1). The Woolpunda water sample was obtained from the flow meter of bore No. 24. The Waikerie sample was taken from the Ramco flow meter and the Qualco–Sunlands sample from the air valve downstream of bore No. 9B. All water samples were collected by an SA Water employee and were sent to the Australian Water Quality Centre (AWQC) for analysis. The results provided by the AWQC are National Association of Testing Authorities (NATA) accredited.
2.3.2. Water Quality Parameters Water parameters determined for each sample were pH, salinity, calcium (Ca2+), magnesium 2+ + + - - - (Mg ), potassium (K ), sodium (Na ), bicarbonate (HCO3 ), chloride (Cl ), fluoride (F ), 2- + - - sulphate (SO4 ), silica (Si2 ), nitrate (NO3 )+ nitrite (NO2 ) as nitrogen, nitrate+nitrite as nitrate, arsenic (As), copper (Cu), iron (Fe), lead (Pb) and zinc (Zn2+).
The Waikerie monthly rainfall data during September 2004 to August 2005 was obtained from the Waikerie office of the District Council of Loxton Waikerie. All data cited are means and standard deviations (± SD) unless otherwise specified.
25 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco–Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin.
Table 2.1 Mean composition of seawater (after Goldberg, 1963).
Constituent Concentration (mg/L) Constituent Concentration (mg/L) Cl 19,000 U 0.003 Na 10,500 Mn 0.002 SO4 2,700 Ni 0.002 Mg 1,350 V 0.002 Ca 400 Ti 0.001 K 380 Co 0.0005 HCO3 142 Cs 0.0005 Br 65 Sb 0.0005 Sr 8 Ce 0.0004 SiO2 2.8 Ag 0.0003 B 4.6 La 0.0003 F 1.3 Y 0.0003 N (NO3, NO2 & NH4) 0.5 Cd 0.00011 Li 0.17 W 0.0001 Rb 0.12 Ge 0.00007 P 0.07 Cr 0.00005 I 0.06 Th 0.00005 Ba 0.03 Sc 0.00004 Al 0.01 Ga 0.00003 Fe 0.01 Hg 0.00003 Mo 0.01 Pb 0.00003 Zn 0.01 Bi 0.00002 Se 0.004 Nb 0.00001 As 0.003 Ar 0.000004 Cu 0.003 Be 0.0000006 Sn 0.003
26 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco–Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin.
LEGEND
1. Waikerie section 2. Woolpunda section 3. Qualco–Sunlands section
4. SPDB discharge point
3
1
2
4
Figure 2.1 Water samples taken September 2004 to August 2005 at four locations: 1 – Waikerie section, 2 – Woolpunda section, 3 – Qualco–Sunlands section and 4 – SPDB discharge point. Triangles represent the location of individual bores.
27 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco–Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin.
2.4. Results
2.4.1. pH The mean pH for the Waikerie, Woolpunda and Qualco-Sunlands sections of the SIS were 7.2 ± 0.1 (± SD), 7.1 ± 0.1 and 7.0 ± 0.1 respectively and the mean pH at the discharge point of the SPDB was 7.1 ± 0.1 (Table 2.2). The pH range for all samples was from 6.7 to 7.4. All localities recorded their lowest pH in March 2005 (Figure 2.2) after trending downwards from a peak in November 2004. All mean pH values increased after May 2005 to peak again in June 2005 before declining again.
Waikerie Woolpunda Qualco Outfall 7.6
7.4
7.2
pH 7.0
6.8
6.6
Jul-05 Jan-05 Apr-05 Jun-05 Oct-04 Nov-04 Feb-05 Mar-05 Aug-05 Sep-04 Dec-04 May-05
Figure 2.2. Monthly pH for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005. (Note: the monthly pH data for Woolpunda SIS was identical to that for the SPDB discharge point from February to August 2005).
28 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
Table 2.2. Mean water quality parameters for the Waikerie, Woolpunda, Qualco-Sunlands SIS and the Stockyard Plains Disposal Basin discharge point, between September 2004 and August 2005 (± SD).
2+ 2+ + + - + - - - 2- 2+ pH Salinity Ca Mg K K :Cl Na HCO3 Cl F SO4 Si
(g/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Waikerie 7.2 16.5 260 407 87 0.009 5966 577 9374 2.8 1430 28
± 0.1 ± 1.0 ± 14 ± 25 ± 4 ± 0 .001 ± 820 ± 24 ± 513 ± 0.4 ± 55 ± 0.9
Woolpunda 7.1 19.3 504 574 94 0.008 6309 453 11400 0.6 1422 20
± 0.1 ± 0.5 ± 20 ± 20 ± 5 ± 0.001 ± 159 ± 32 ± 447 ± 0.4 ± 70 ± 0.8
Qualco- 7.0 12.8 576 533 75 0.011 4051 446 6486 3.4 3014 27
Sunlands ± 0.1 ± 1.3 ± 70 ± 69 ± 6 ± 0.001 ± 576 ± 30 ± 949 ± 1.0 ± 303 ± 1.4
SPDB 7.1 17.2 431 506 88 0.009 5161 487 9861 1.5 1644 24
Discharge ± 0.1 ± 0.4 ± 20 ± 18 ± 5 ± 0.001 ± 1689 ± 32 ± 318 ± 0.4 ± 54 ± 0.9
29 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.4.2. Salinity Between September 2004 and August 2005 (Table 2.2), the Qualco-Sunlands SIS had the lowest mean salinity (12.8 ± 1.3 g/L) and the Woolpunda SIS the highest mean salinity (19.3 ± 0.5 g/L). Fluctuations in salinity did not correlate between SISs or with season. Salinity at the Qualco-Sunlands SIS increased by 33% from July to August 2005 (Figure 2.3). In general, the lowest salinity values for all SISs and the SPDB discharge point were between May 2005 and June 2005.
Waikerie Woolpunda Qualco Outfall 20
18
16
14
Salinity (g/L) 12
10
Jul-05 Jan-05 Apr-05 Jun-05 Oct-04 Nov-04 Feb-05 Mar-05 Sep-04 Dec-04 Aug-05 May-05
Figure 2.3. Monthly salinity (g/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005.
2.4.3. Calcium Over the time period sampled, the mean calcium concentration was 504 ± 20 mg/L for the Woolpunda SIS, 576 ± 70 mg/L for the Qualco-Sunlands SIS, and 431 ± 20 mg/L at the discharge point for the SPDB (Figure 2.4, Table 2.2). These values are approximately double the average concentration recorded for the Waikerie SIS over the same time period (260 ± 14 mg/L), which was marginally greater than the value expected in seawater (226 mg/L) of equivalent salinity.
2.4.4. Magnesium The highest mean magnesium concentration was recorded for the Woolpunda SIS (574 ± 20 mg/L), followed by the Qualco-Sunlands SIS (533 ± 69 mg/L), SPDB discharge point (506 ± 20 mg/L) and Waikerie SIS (407 ± 25 mg/L) (Table 2.2). The lowest level of magnesium occurred in the Qualco-Sunlands SIS in September 2004 and this returned to a relatively stable level between 500–550 mg/L until August 2005 when an increased level of 691 mg/L
30 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
was recorded (Figure 2.5). All magnesium levels within the SIS system were below that expected in seawater (703 mg/L) at equivalent salinity (19 g/L).
Waikerie Woolpunda Qualco Outfall 700
600
500
400
300
200 Calcium (mg/L) 100
0
Jul-05 Jan-05 Apr-05 Jun-05 Oct-04 Nov-04 Feb-05 Mar-05 Sep-04 Dec-04 Aug-05 May-05
Figure 2.4. Monthly calcium concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = calcium level of equivalent salinity seawater).
Waikerie Woolpunda Qualco Outfall
800 700
600
500
400
300
200
Magnesium (mg/L) 100
0
Jul-05 Jan-05 Apr-05 Jun-05 Oct-04 Nov-04 Feb-05 Mar-05 Sep-04 Dec-04 Aug-05 May-05
Figure 2.5. Monthly magnesium concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = magnesium level in equivalent salinity seawater).
31 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.4.5. Potassium Over the time period monitored, the lowest mean potassium concentration (75 ± 6 mg/L) in groundwater was recorded in the Qualco-Sunlands section of the SIS. The mean potassium concentration for Waikerie and Woolpunda sections of the SIS and the SPDB discharge point were 87 ± 4 mg/L, 94 ± 5 mg/L and 88 ± 5 mg/L respectively (Table 2.2). A marginal fall in potassium occurred in samples from the Waikerie and Woolpunda sections of the SIS and the SPDB discharge point after May 2005, however, levels remained at more than 80 mg/L (Figure 2.6). The mean level of potassium in groundwater from the SIS compared to equivalent salinity seawater (212 mg/L) was 35.4% for the Qualco-Sunlands SIS, 41.0% for the Waikerie SIS, 44.3% for the Woolpunda SIS and 41.5% for the combined flow at the SPDB discharge point.
Waikerie Woolpunda Qualco Outfall 250
200
150 g/L) (m
100
Potassium 50
0
Jul-05 Oct-04 Apr-05 Jun-05 Jan-05 Feb-05 Mar-05 Aug-05 Sep-04 Nov-04 Dec-04 May-05
Figure 2.6. Monthly potassium concentration (mg/L) for the Woolpunda, Waikerie, Qualco -Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = potassium level in equivalent salinity seawater).
2.4.6. Sodium The Woolpunda SIS pipeline had the greatest mean sodium concentration at 6,309 ± 159 mg/L (Table 2.2), followed by the Waikerie SIS (5,966 ± 820 mg/L), the SPDB discharge point (5,161 ± 1,689 mg/L) and the Qualco-Sunlands SIS (4,051 ± 576 mg/L). An increase in sodium concentration occurred at the Qualco-Sunlands SIS between September and October 2004, and July and August 2005 (Figure 2.7). The level of sodium recorded in saline groundwater from the Woolpunda and Waikerie sections of the SIS and at the discharge point for the SPDB were similar to the level (5,837 mg/L) found in equivalent salinity (19 g/L) seawater. The level of sodium recorded in groundwater from the Qualco-Sunlands section of the SIS was typically in the order of 70% of the level found in equivalent salinity seawater.
32 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
Waikerie Woolpunda Qualco Outfall
7,000
6,000
5,000
4,000
(mg/L) Sodium
3,000
2,000
Jul-05 Oct-04 Apr-05 Jan-05 Jun-05
Feb-05 Mar-05 Sep-04 Nov-04 Aug-05 Dec-04 May-05
Figure 2.7. Monthly sodium concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = sodium level in equivalent salinity seawater).
2.4.7. Bicarbonate The saline groundwater within the Waikerie section of the SIS had the highest mean monthly bicarbonate concentration of 577 ± 24 mg/L during the monitoring program. Woolpunda and Qualco-Sunlands had similar mean concentrations of 453 ± 32 mg/L and 446 ± 30 mg/L, respectively (Table 2.2). All monitoring stations experienced their lowest bicarbonate concentration in March 2005 (Figure 2.8). Mean bicarbonate levels for the Woolpunda, Waikerie and Qualco-Sunlands sections of the SIS, and at the SPDB discharge point were 576%, 733%, 567% and 619% higher respectively, than the level found (76 mg/L) in equivalent salinity19 g/L seawater.
2.4.8. Chloride During the period of sampling, mean monthly chloride levels in the saline groundwater in the Waikerie section of the SIS (9,374 ± 513 mg/L) and at the discharge point of the SPDB (9,861 ± 318 mg/L) were similar. Samples taken from the Woolpunda section of the SIS had the highest mean monthly chloride concentration during the monitoring program (11,400 ± 447 mg/L, Table 2.2). A pronounced increase in chloride concentration was observed in the sample taken from the Qualco-Sunlands section of the SIS in August 2005 (Figure 2.9). The level of chloride found in saline groundwater from the Woolpunda section of the SIS was approximately 15% higher than that of equivalent salinity (19 g/L) seawater and the groundwater from the Waikerie section of the SIS was in the order of 10% lower. The level of chloride found in the combined flow from the SIS sampled at the discharge point of the SPDB showed a very similar level to that found in equivalent salinity seawater. In contrast,
33 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
the level of chloride found in groundwater sampled from the Qualco-Sunlands section of the SIS was typically in the order of 65% of the level found in equivalent salinity seawater.
Waikerie Woolpunda Qualco Outfall 700
600
500
400
300
200 Bicarbonate (mg/L) 100
0
Jul-05 Apr-05 Oct-04 Jun-05 Jan-05 Feb-05 Mar-05 Aug-05 Sep-04 Nov-04 Dec-04
May-05
Figure 2.8. Monthly bicarbonate concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = bicarbonate level in equivalent salinity seawater).
Waikerie Woolpunda Qualco Outfall 14,000
12,000
10,000
8,000
Chloride (mg/L) 6,000
4,000
Jul-05 Apr-05 Oct-04 Jan-05 Jun-05 Feb-05 Mar-05 Nov-04 Sep-04 Dec-04 Aug-05 May-05
Figure 2.9. Monthly chloride concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB, September 2004 to August 2005 (dotted line = chloride level in equivalent salinity seawater).
34 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.4.9. Potassium: Chloride Ratio Over the time monitoring occurred, the mean potassium chloride ratio for Waikerie SIS, Woolpunda SIS and the SPDB discharge point were 0.009 ± 0.001 mg/L, 0.008 ± 0.001 mg/L and 0.009 ± 0.001 mg/L, respectively (Table 2.2). The ratio was higher at 0.011 ± 0.001 mg/L and more variable for the Qualco-Sunlands section of the SIS. Additionally, the ratios were lower and more stable (always greater than 0.007) for the Woolpunda SIS and Waikerie SIS sections and at the discharge point of the SPDB (Figure 2.10).
Waikerie Woolpunda Qualco Outfall 0.025
0.020
0.015
K/Cl 0.010
0.005
0.000
Jul-05 Oct-04 Apr-05 Jan-05 Jun-05 Mar-05 Feb-05 Nov-04 Sep-04 Dec-04 Aug-05
May-05
Figure 2.10 Monthly potassium:chloride ratio for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = potassium:chloride level in equivalent salinity seawater).
2.4.10. Fluoride Between September 2004 and August 2005, monthly fluoride concentrations at all sites were greater than 4.5 mg/L (Table 2.2). The Qualco-Sunlands SIS had the highest mean concentration of 3.4 ± 1.0 mg/L, followed by the Waikerie SIS (2.8 ± 0.4), the SPDB discharge point (1.5 ± 0.4 mg/L) and the Woolpunda SIS (0.6 ± 0.4 mg/L). An abrupt decrease in fluoride concentration occurred in March 2005 in the Qualco-Sunlands SIS and at the discharge point for the SPDB, which coincided with an increase in concentration in the Waikerie and Woolpunda SISs (Figure 2.11). The large decrease in the Qualco-Sunlands SIS resulted in a decrease at the SPDB discharge point as well.
35 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
Waikerie Woolpunda Qualco Outfall 5
4
3
2
Fluoride (mg/L)
1
0
Jul-05 Apr-05 Oct-04 Jan-05 Jun-05 Feb-05 Mar-05 Sep-04 Nov-04 Dec-04 Aug-05 May-05
Figure 2.11. Monthly fluoride concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = fluoride level in equivalent salinity seawater).
2.4.11. Sulphate Over the time monitored, the mean monthly sulphate concentration at the Woolpunda (1,422 ± 70 mg/L) and the Waikerie (1,430 ± 55 mg/L) SISs and the SPDB discharge point (1,644 ± 54 mg/L) were similar to levels found in equivalent salinity (19 g/L) seawater (Table 2.2). The average concentration of sulphate found in samples taken from the Qualco-Sunlands section of the SIS (3,014 ± 303 mg/L) were approximately double the levels recorded in other sections and at the discharge point of the SPDB (Figure 2.12).
Waikerie Woolpunda Qualco Outfall 3,500
3,000
2,500
2,000
Sulphate (mg/L) 1,500
1,000
Jul-05 Apr-05 Oct-04 Jun-05 Jan-05 Feb-05 Mar-05 Aug-05 Sep-04 Nov-04 Dec-04 May-05
Figure 2.12. Monthly sulphate concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = sulphate level in equivalent salinity seawater).
36 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.4.12. Silica Between September 2004 and August 2005, the mean concentration of silica in the Waikerie, Woolpunda and Qualco-Sunlands SISs and at the SPDB discharge point were 28 ± 0.9 mg/L, 20 ± 0.8 mg/L, 27 ± 1.4 mg/L and 24 ± 0.9 mg/L respectively (Table 2.2). Highest monthly levels were recorded in samples taken from the Waikerie and Qualco-Sunlands sections of the SIS and the lowest levels were recorded in monthly groundwater samples taken from the Woolpunda section of the SIS (Figure 2.13).
Waikerie Woolpunda Qualco Outfall 35
30
25
20
15
Silica (mg/L) 10
5
0
Jul-05 Apr-05 Oct-04 Jun-05 Jan-05 Feb-05 Mar-05 Aug-05 Sep-04 Nov-04 Dec-04 May-05
Figure 2.13. Monthly silica concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = sulphate level in equivalent salinity seawater).
2.4.13. Metals Of the metals monitored monthly from the four sections of the SIS, only iron and arsenic were recorded at levels that were above the levels of detection for the methods of analysis used (Table 2.3). The level of copper, lead and zinc at each monthly sample time was <0.01 mg/L, <0.005 mg/L and <0.03 mg/L respectively, for the duration of the monitoring program.
2.4.14. Iron Over the time of monitoring, the mean iron concentration in the Waikerie SIS (1.35 ± 0.6 mg/L) was more than three times as great as that in the Woolpunda SIS (0.41 ± 0.3 mg/L), and nearly double that in the Qualco-Sunlands SIS (0.70 ± 0.5 mg/L) and at the SPDB discharge point (0.73 ± 0.4 mg/L) (Table 2.3). The monthly iron concentration was greatest at Waikerie each month, except in April, June and July 2005 (Figure 2.14).
37 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
Table 2.3. Mean metal concentrations for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (± SD).
SIS Location Iron Arsenic Copper Lead Zinc (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Waikerie 1.35 ± 0.6 < 0.088 < 0.01 < 0.005 < 0.03
Woolpunda 0.41 ± 0.3 < 0.012 < 0.01 < 0.005 < 0.03
Qualco-
Sunlands 0.70 ± 0.5 < 0.028 < 0.01 < 0.005 < 0.03
SPDB Discharge 0.73 ± 0.4 < 0.02 < 0.01 < 0.005 < 0.03
Waikerie Woolpunda Qualco Outfall 3.0
2.5
2.0
1.5
Iron (mg/L) 1.0
0.5
0.0
Jul-05 Apr-05 Oct-04 Jun-05 Jan-05 Feb-05 Mar-05 Aug-05 Sep-04 Nov-04 Dec-04 May-05
Figure 2.14. Monthly iron concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005 (dotted line = iron level in equivalent salinity seawater).
38 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.4.15. Arsenic From September 2004 to August 2005, the level of arsenic recorded in samples from all sections of the SIS ranged from 0 to 0.045 mg/L, apart from a sample taken from the Waikerie section of the SIS in August 2005 when the concentration was recorded as 0.088 mg/L (Table 2.3, Figure 2.15).
Waikerie Woolpunda Qualco Outfall
0.10
0.08
0.06
0.04 Arsenic (mg/L) Arsenic
0.02
0.00 Jul-05 Apr-05 Oct-04 Jun-05 Jan-05 Feb-05 Mar-05 Aug-05 Sep-04 Nov-04 Dec-04 May-05
Figure 2.15. Monthly arsenic concentration (mg/L) for the Woolpunda, Waikerie, Qualco-Sunlands SIS and the SPDB discharge point, September 2004 to August 2005.
2.4.16. Rainfall For the duration of the sampling period, Waikerie received 217.3 mm of rainfall. The greatest monthly rainfall occurred in December 2004 (47.2 mm) and June 2005 (52.1 mm). No rainfall was recorded in October 2004 and May 2005 (Figure 2.16).
39 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
60 52.1 47.2 50
40
31.8 30 24.2
Rainfall (mm) Rainfall 20 19.6 10 5.4 8 10.6 0 8.6 0 9.8 0 Jul-05 Oct-04 Apr-05 Jan-05 Jun-05 Sep-04 Nov-04 Dec-04 Feb-05 Mar-05 Aug-05 May-05
Figure 2.16. Monthly rainfall (mm) for the township of Waikerie between September 2004 and August 2005 (Source: District Council of Loxton Waikerie).
2.5. Discussion The 12 month monitoring of saline groundwater from the major sections of the Woolpunda, Waikerie and Qualco-Sunlands SIS identified the key elements that are in excess or deficit when compared to equivalent salinity seawater, as well as the degree of variation between the pipeline sections investigated and the seasonal variation that occurred over this time.
Potassium is the ion of most significance to saline groundwater aquaculture and has been shown to be deficient in water from each SIS section tested. The level of potassium in these SIS sections is close to 40% of the level found in equivalent salinity seawater recommended to be the minimum level needed to support optimal growth of mulloway (Doroudi et al., 2006), and is below 60% of the level found in equivalent salinity seawater recommended to be the minimum level needed to support optimal growth of snapper (Fielder et al., 2001). This suggests that the saline groundwater from SISs in this region should be suitable for the culture of mulloway, but supplementation of potassium will be required to support the culture of snapper. A more detailed discussion of the significance of this ion for aquaculture using saline groundwater is provided in Chapters 3 and 4.
The levels of pH were lower in all groundwater samples than expected for equivalent salinity seawater. Bicarbonate was the component of the saline groundwater that was in greatest excess compared to equivalent salinity seawater. Elevated bicarbonate provides a well buffered cultured medium to maintain stable pH between the range of 6.5 to 8.5 that is considered optimal for production of fish (Ferguson, 1988) although the high levels of
40 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
bicarbonate were likely to have contributed to calcium carbonate precipitation observed on production and nursery culture tanks at the WISAC.
Davis (1990) suggested some general guidelines for the composition of saline water used for the culture of red drum (Sciaenops ocellatus), a species related to mulloway. He recommended that salinity should be between 6 g/L and 40 g/L, calcium concentration greater than 150 mg/L, and the concentration of chlorides should be more than 250 mg/L and at least double the concentration of sulphates. The SIS groundwater is ‘hard’, having calcium and magnesium concentrations greater than 400 mg/L. Davis (1990) also suggested that fish generally expend more energy due to osmoregulation in ‘soft’ water than ‘hard’ water. No deleterious effects on survival and growth of red drum cultured at 3 g/L salinity were found, with magnesium concentrations up to 241% of the level found in equivalent salinity seawater (Forsberg & Neil, 1997). Wurts and Stickney (1989) also found no effects due to magnesium deficiency on growth and survival of red drum cultured at 35 g/L, but that 100% mortality occurred within 96 hours in water with a calcium concentration of 44% of the level found in equivalent salinity seawater. The concentration of calcium in saline groundwater in all SIS sections was in excess of 100% of the level found in equivalent salinity seawater.
The levels of sodium, chloride and sulphate were all at similar levels to those found in equivalent salinity seawater for the Woolpunda and Waikerie sections of the SIS and at the discharge point at the SPDB. The level of chlorides was well in excess of twice the level of sulphates recommended by Davis (1990) for saline groundwater used to culture red drum. No deleterious effects on survival and growth of red drum were found with sulphate concentrations up to 720% of the level found in equivalent salinity seawater (Forsberg & Neil, 1997).
There was moderate variability between the different SIS pipeline sections tested, which was not unexpected, given the typical variability of groundwater over relatively short distances. The Qualco-Sunlands SIS section differed most, having the lowest sodium and chloride levels and thus salinity, and the highest calcium, fluoride, sulphate and silica levels, and potassium:chloride ratio. Levels of sodium and chloride in samples taken from the Qualco- Sunlands SIS section were lower than for equivalent salinity seawater. The reduced levels recorded were attributed to groundwater from this section being lower in salinity, probably because of the irrigated horticulture that occurs, than other sections of the SIS, as the mean salinity recorded for the Qualco-Sunlands section was 12.8 g/L compared to between 16.5g/L and 19.3 g/L for the other sections monitored. The Qualco-Sunlands section of the SIS also recorded a high level of sulphate while all other sections recorded similar levels to that found in equivalent salinity seawater.
The levels of most SIS groundwater components tested were relatively stable over the duration of the 12 month sampling period, apart from a few conspicuous changes for a few components at a single sampling time at a specific location. For example, calcium, magnesium and sulphate were low for the Qualco-Sunlands SIS in September 2004; fluoride low for the Qualco-Sunlands SIS in March 2005; and magnesium and arsenic levels high for the Qualco-Sunlands and Waikerie SISs respectively, in August 2005. Iron levels were more variable over the sampling period, with peak levels occurring for the Qualco-Sunlands SIS in November 2004, and in August 2005 for the Waikerie SIS. There was no conspicuous correlation between any of the SIS groundwater components evaluated and rainfall.
41 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.6. Conclusion and Recommendations Monitoring of the composition of saline groundwater from the three SIS sections and at the point of discharge into the SPDB showed that there was some variation in water composition between these sections. The composition of saline groundwater in the Qualco-Sunlands SIS tended to differ from the other sections. The Qualco-Sunlands SIS is the smallest of the sections, contributing only 35 L/sec, and does not appear to greatly influence the overall composition of the total 340 L/sec flow of saline groundwater discharged to the SPDB.
As with other saline groundwater sources the major ion of concern is potassium. The concentrations measured indicate that the saline groundwater available from the Woolpunda and Waikerie SIS sections appears suitable for culture of mulloway, a euryhaline species, but the concentration of this ion is too low to support the culture of snapper. It is suggested that supplementation of potassium would be required to culture snapper in this SIS groundwater and the costs incurred and appropriate culture systems required to achieve this would need to be further considered for this species.
Generally, the composition reported for SIS groundwater in each SIS section and the water discharged to the SPDB was stable throughout the year. Some unexplained variations did occur, although the changes recorded whilst monitoring are not considered to be at a level that would impact upon aquaculture operations.
42 Chapter 2 – Characterisation of the composition of saline groundwater from the Woolpunda, Waikerie, Qualco-Sunlands Salinity Interception Scheme and Stockyard Plain Disposal Basin
2.7. References Allan, G.L., Banens, B. and Fielder, S. 2001. Developing commercial saline aquaculture in Australia: Part 2. R&D Plan. FRDC Project No. 98/335, NSW Fisheries Final Report Series No. 31, 128pp. Allan, G.L., Dignam, A. and Fielder, S. 2001. Developing commercial saline aquaculture in Australia: Part 1. R&D Plan. FRDC Project No. 98/335, NSW Fisheries Final Report Series No. 30, 33pp. Davis, J.T. 1990. Inland culture of red drum. In: Chamberlain, G.W., Miget, R.J. and Haby, M.G. Red drum aquaculture: Proceedings of a symposium on the culture of red drum and other warm water fishes. Texas A &M Sea Grant College Program, 236pp. Doroudi, M.S., Fielder, D.S., Allan, G.L. and Webster, G.K. 2006. Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Aquaculture Research 37: 1034 1039. Ferguson, H. 1988. In: Fish Diseases: Refresher course for veterinarians. Proceedings 106. Post Graduate Committee in Veterinary Science, University of Sydney, 633pp. Fielder S.D., Bardsley, W.J and Allan, G.L. 2001. Survival and growth of Australian snapper, Pagrus auratus, in saline groundwater from inland New South Wales, Australia. Aquaculture 201: 73–90. Forsberg, J.A. and Neil, W.H. 1997. Saline groundwater as an aquaculture medium: Physiological studies on red drum. Environmental Biology of Fishes 49: 119–128. Goldberg, E.D. 1963. Chemistry—the oceans as a chemical system, p. 3–25. In: M.N. Hill (ed.), Composition of Sea Water, Comparative and Descriptive Oceanography. Vol. II. The Sea. Interscience Publ., New York. Partridge, G.J. 2002. Evaluating the suitability of saline groundwater from Lake Toolibin, Western Australia for culturing barramundi (Lates calcarifer), mulloway (Argyrosomus japonicus) and snapper (Pagrus auratus). Aquaculture Development Unit Challenger TAFE. Partridge, G.J. and Creeper, J. 2004. Skeletal myopathy in juvenile barramundi, Lates calcarifer (Bloch), cultured in potassium-deficient saline groundwater. Journal of Fish Diseases 27: 523–530. Partridge, G.L., Lymbery, A.J., and George, R.J. 2008. Finfish mariculture in inland Australia: A review of potential water sources, species and production systems. Journal of the World Aquaculture Society 39: 291–310. Wurts, W.A. and Stickney, R.R. 1989. Response of red drum (Sciaenops ocellatus) to calcium and magnesium concentrations in fresh and salt water. Aquaculture 76: 21–35.
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44 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
3.1 Summary In Australia, mulloway is commercially cultured using a variety of production methods including seacages, ponds and tanks.
All saline groundwater sources are deficient in potassium and, as such, consideration of the level of potassium in saline groundwater is important when assessing the potential of these sources for aquaculture.
The saline groundwater from the Woolpunda, Waikerie and Qualco-Sunlands SIS generally has a potassium concentration between 80 mg/L and 100 mg/L representing between 36.4% and 45.5% of the level found in equivalent salinity seawater. This suggests that good growth of mulloway should be achieved in suitable culture systems.
A previous study conducted by SARDI at CPISARC showed that mulloway appeared to grow slightly slower in SIS groundwater from SPDB than fish cultured in seawater diluted to the same salinity. In order to confirm these results, two further experiments were conducted at SAASC. The first experiment compared growth of mulloway in: • SIS groundwater from SPDB • seawater diluted to the salinity of SPDB groundwater.
A second experiment compared the performance of mulloway cultured in: • SIS groundwater from SPDB • seawater diluted to the salinity of SPDB groundwater • seawater (undiluted)
A third experiment was conducted to determine the routine metabolic rate (RMR), maximum metabolic rate (MMR) and metabolic scope (MS) of mulloway that had been maintained in saline groundwater from SPDB, seawater diluted to the salinity of SPDB groundwater and seawater.
Survival of mulloway in all water types was high in all experiments.
No significant difference in growth, apparent FCR or SGR was recorded for mulloway cultured in SIS groundwater, diluted seawater and in seawater. These results suggest that mulloway perform the same in SIS groundwater from SPDB as they do in equivalent salinity seawater and full salinity seawater.
45 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Results from metabolism studies showed that the RMR, MMR and MS of mulloway did not change significantly when fish were exposed to SIS groundwater, diluted seawater or seawater.
The absence of mulloway growth effects supports the results of the metabolism experiment and suggests that the metabolism of this euryhaline species may not change in response to the different salinity and ionic conditions investigated. This should provide an advantage for this species as a suitable candidate for inland aquaculture utilising saline groundwater available from SISs in the Riverland region of South Australia.
3.2 Background Mulloway (Argyrosomus japonicus) are found along the south coast of Australia from North West Cape in Western Australia to the Burnett River in Queensland (Kailola et al., 1993) and are also found off the west and east coast of Africa and off Madagascar (Gommon et al., 1994). Mulloway belong to the Sciaenids (croakers or drums) and as is typical for this family, they are large predatory fish associated with estuaries (Gommon et al., 1994).
Larvae and juveniles of mulloway appear to have a requirement for hyposaline water (Hall, 1986). In South Australia, juvenile mulloway are found in estuaries where they experience variable salinity, while adults live predominantly in the surf zone (Jones et al., 1990). These observations suggest that the species can tolerate a wide range of salinities. Fielder and Bardsley (1999) reported that mulloway juveniles with an initial weight of 7.0 ± 2.8 g mean, ± SD cultured for 28 days at different salinities, grew faster and recorded a lower food conversion ratio in water with salinity of 5 g/L than fish grown at salinities of 10, 20 and 35 g/L. This euryhaline feature of mulloway is viewed as an advantage for aquaculture using saline groundwater as the salinity of groundwater sources varies widely (Partridge et al., 2008).
In South Australia, mulloway is commercially cultured in seacages within the Spencer Gulf. Mulloway are known to have some features that provide advantages for aquaculture. It has been predicted that good markets for large fish (>1.5 kg) may be available as the product has an attractive appearance, and tasty flaky flesh with boneless fillets that hold together when raw or cooked (Ruello, 2004). The species is known to be able to adapt to low oxygen environments (Fitzgibbon et al., 2007) and has been cultured using a variety of production methods including seacages, ponds and tanks. Mulloway have also proven to be a robust species when cultured in commercial seacages, exhibiting few disease or parasite problems (Hayward et al., 2007).
All saline groundwater sources are deficient in potassium (Partridge et al., 2008). Potassium is the major cation of intracellular fluids involved in osmoregulation (Teeter, 1997), and this ion is required to maintain the electrolyte and acid balance of marine fish (Wilson and El Naggar, 1992; Shearer, 1988). As such, consideration of the level of potassium in saline groundwater is important when assessing the potential of these sources for aquaculture. Doroudi et al. (2006) concluded that growth and survival of juvenile mulloway (6.8 ± 0.8 g, ± SD) was significantly reduced (P>0.05) at potassium concentrations less that 25% of
46 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
equivalent salinity seawater, but was not significantly affected (P>0.05) when potassium concentration was 40% or greater. The groundwater from the SIS sources in the Waikerie region generally have potassium concentrations between 80 mg/L and 100 mg/L (Chapter 2) representing between 36.4% and 45.5% of the level found in equivalent salinity seawater. This suggests that good growth of this species should be achieved in suitable aquaculture production systems.
The constant elevated water temperature of saline groundwater from SISs is viewed as an advantage of these systems for aquaculture. Partridge et al. (2008) described unpublished data for mulloway maintained in seawater, with water temperatures ranging between 18oC and 23oC, in which fish grew from an initial weight of 30 g to a final weight of 810 g over a period of 12 months. Similar growth was reported from approximately 10 g mulloway fingerlings provided by SARDI to the operator of a commercial recirculating aquaculture system. These fish were reported to grow to 700 g within eight months (Roger Strouthers, 2001pers. comm.). Recently Collet et al. (2008), studying Argyrosomus japonicus in South Africa, reported that the highest SGR of 2.05% per day was achieved at 25.3oC while the optimal FCR of 0.79 was achieved at 21.7oC.
A previous study conducted by SARDI showed that mulloway appeared to grow slightly slower in saline groundwater from SPDB. During this trial conducted at CPISARC, there were concerns that a technical problem during one month of the trial may have influenced results achieved, as during this month growth rate declined for the fish in the saline groundwater treatment but in all other months growth rate was similar between the saline groundwater and diluted seawater treatments. In order to reassess these results two further experiments were conducted. The first of these experiments repeated the previous trial conducted at CPISARC comparing growth of mulloway in: • SIS groundwater from SPDB • seawater diluted to the salinity of SPDB groundwater.
A second experiment was also conducted that included a comparison of the performance of mulloway cultured in: • SIS groundwater from SPDB • seawater diluted to the salinity of SPDB groundwater • seawater (undiluted).
A third experiment was conducted to determine the RMR, MMR and MS for mulloway that had been maintained in saline groundwater from SPDB, seawater diluted to the salinity of SPDB groundwater and seawater.
47 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
3.2 Methods
3.2.1 Experiment 1 – Performance of Mulloway in Diluted Seawater and SIS Groundwater A controlled environment room at SAASC was modified and assigned to the inland saline aquaculture project to provide a facility in which to undertake the replicated experiments. Modifications included installation of storage tanks for groundwater transported from SPDB, storage tanks for mixing and storage of diluted seawater and installation of overhead air delivery and pump systems to deliver SIS groundwater or diluted seawater from storage tanks to experimental tanks. Samples of each water type were taken and analysed (AWQC, Adelaide) to determine composition of important ions (Table 3.1).
Table 3.1. Composition of diluted seawater and SIS groundwater used to culture mulloway in experiment 1 for 122 days.
Parameter Diluted seawater SIS groundwatera pH 8.1 8.0 Salinity (g/L) 20.9 19.6 Potassium (mg/L) 252 104 % K+ in equivalent salinity seawater 108.2% 47.2% Chloride (mg/L) 11,600 10,800 K:Cl 0.0217 0.0096 Calcium (mg/L) 254 424 Magnesium (mg/L) 782 532 Sodium (mg/L) 6,300 6,250
a Saline groundwater was sourced from the ‘outfall’ of the Stockyard Plains Disposal Basin, Waikerie, South Australia.
Eight 800 L capacity tanks (four tanks per treatment) were used for the experiment with each supported by a recirculating water treatment system (Figure 3.1) to maintain optimum water quality for the duration of the experiment. Components of these water treatment systems included: • Dacron™ mechanical filter material • biological trickle filter (20 L plastic media) • submerged biological filter (20 L plastic media) • foam fractionator • sump (70 L) with submersible pump (Pondmaster™ 3600, 3200 L/hr) • aeration provided to each tank using a single air stone.
The experiment started on 28 February 2005 and terminated on 29 June 2005 (122 days). Mulloway fingerlings were purchased from Clean Seas Aquaculture Ltd, Arno Bay, South Australia and transported to SAASC. Thirty (n = 30) fish were stocked into each experimental tank filled with full salinity seawater. Salinity in all tanks was reduced by 3 g/L/day until a salinity of 20 g/L was reached. A complete water exchange was then conducted for all tanks in the SIS groundwater treatment and the initial weight of all fish was recorded.
48 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Fish were fed to satiation twice daily using a closed formula commercial diet Nova ME (Nova ME, 45% protein, 20% lipid; Skretting, Cambridge, Tasmania) and the volume of food consumed was determined at the end of each day from the amount of feed remaining in pre- weighed containers assigned to each tank. A photoperiod of eight hours of light and 16 hours of darkness was maintained throughout the trial. Approximately 50% of water was exchanged each week as two exchanges of 150 L water conducted each Monday and Friday during the trial. The bottoms of tanks were vacuumed ad hoc to remove settled organic waste.
Figure 3.1. Layout of eight experimental tanks and associated components of individual recirculating water treatment systems used to culture mulloway in different water types at SAASC.
All individual fish within each tank were weighed each month, and at the end of the experiment to determine the final mean weight, SGR, (% body weight/day) and FCR.
Water quality parameters were measured each weekday. Dissolved oxygen (% saturation) and water temperature (oC) were measured using an OxyGuardTM Handygamma dissolved oxygen meter (OxyGuard International A/S, Birkerød, Denmark). pH and salinity (g/L) were measured daily using a WTW 340i SET pH and conductivity meter (Wissenschaftlich- + Technische Werkstätten, Weilheim, Germany). Ammonium (NH4 , mg/L) was recorded weekly using an RQflex 10 meter (Merck KgaA, Darmstadt, Germany).
49 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
3.2.2 Experiment 2 – Performance of Mulloway in Diluted Seawater, SIS Groundwater and Seawater Juvenile mulloway (n = 162) were randomly allocated between nine 800 L capacity fibreglass tanks (n = 18 fish per tank). Each tank was supported by an individual recirculating water treatment system as used for Experiment 1. The initial water temperature in the tanks ranged between 16–17oC and fish were acclimatised to the experimental conditions for 25 days during which time the water temperature in all tanks was gradually increased to 21–22oC. During the final four days of the acclimatisation period, the salinity in the diluted seawater and SIS groundwater treatment tanks was reduced to 20 g/L at a dilution rate of 3–4 g/L/day by daily exchange of tank water and replacement with bore water. Samples of each water type were taken and analysed (AWQC, Adelaide) to determine composition of important ions (Table 3.2).
Table 3.2. Composition of diluted seawater and SIS groundwater used to culture mulloway in experiment 2 for 45 days.
Parameter Seawater Diluted seawater SIS groundwatera Salinity (g/L) 37.5 20.9 20.7 Potassium (mg/L) 423 211 83.7 % K+ in equivalent salinity seawater – 90.6% 36.3% Chloride (mg/L) 21,000 11,200 10,800 K:Cl 0.0201 0.0188 0.0078 Calcium (mg/L) 422 243 404 Magnesium (mg/L) 1,400 714 496 Sodium (mg/L) 11,400 5,840 5,950
a Saline groundwater was sourced from the ‘outfall’ of the Stockyard Plains Disposal Basin, Waikerie, South Australia.
The experiment commenced on 15 September 2006 when each fish was weighed. During weighing, diluted seawater was drained from tanks assigned to the SIS groundwater treatment and these tanks were then refilled with groundwater before fish were returned. Water quality monitoring, fish feeding and measurements followed the same procedures as used in Experiment 1.
3.2.3 Experiment 3 – Measurement of Routine Metabolic Rate, and Maximum Metabolic Rate and Metabolic Scope Some of the information for Experiment 3 in this report has been taken from an as yet unpublished Masters thesis written by Tim Flowers, started as part of this CNRM project. A more detailed explanation of this trial will be presented in this thesis.
Routine and maximum metabolic rate of juvenile mulloway were measured using two black acrylic respirometer box systems (n = 6 boxes per system) with each box capable of holding an individual fish. The mean water volume of each respirometer was 2.4 ± 0.02 L (mean; ± standard error, SE). Each individual respirometer had its own lid to prevent the fish from escaping and minimise oxygen transfer with the atmosphere. Each respirometer box system was positioned above a 1000 L, conical bottom fibreglass reservoir containing a submersible
50 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
pump (Pondmaster™ 3600, 3200 L/hr) that supplied water to a six-way manifold connecting to the respirometer boxes. A mean water flow rate of 0.034 ± 0.002 L/sec was delivered to each respirometer with water overflowing from a hole at the opposite end of each chamber and returning to the reservoir tank. An air stone was positioned in each reservoir tank to maintain dissolved oxygen levels at 95–100% saturation. The mean water temperature of the water reservoir was 21.2 ± 0.2oC (mean ± SD).
Experimental fish were starved for 24 hours before being placed into the respirometer boxes to minimise any confounding effect of specific dynamic action (Jobling, 1994). Six fish from the same water type were dip netted from the three replicate tanks used in each experiment treatment and transferred to a respirometer box. The fish were then left overnight to acclimatise to the respirometers.
Oxygen uptake within each respirometer box was determined using methods described by Powell et al. (2005) and will be presented in more detail (Tim Flowers, Masters Thesis in preparation). In summary, the RMR of each mulloway was measured and the MMR for the fish was recorded after the fish had been chased to exhaustion. Exhaustion was achieved by placing individual fish into a 100 L tub containing 40 L of the water type (i.e. seawater, diluted seawater or SIS groundwater) then vigorously chasing the fish with a plastic pole for five minutes until it was non-responsive to touch. During chasing, dissolved oxygen levels were maintained at greater than 100% saturation using a carbon air stone connected to an industrial oxygen cylinder.
3.2.4 Statistical Analysis All statistical analyses were conducted using SPSS Version 10. Mean values are displayed with standard errors (± SE). In Experiment 1, a one-way ANOVA was used to test the affect of water type on mean weight, FCR and SGR. In Experiment 3, a one-way ANOVA was initially used to test the affect of day on water type for RMR, MMR and MS. When no significant difference was found (P >0.05), the data was pooled and re-analysed using a one- way ANOVA to test the affect of water type on RMR, MMR and MS. Significant differences between water types were identified using Tukey’s test.
3.3 Results
3.3.1 Experiment 1 A total of two mortalities were recorded over the experimental period due to fish jumping out of the tanks (one fish from each treatment). These fish were replaced with tagged fish of a similar weight to maintain the stocking density within the relevant tank but were not subsequently used during analysis of results.
Water quality parameters maintained during the trial were similar for both treatments (Table 3.3).
51 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
The initial mean weight of fish in the diluted seawater and the SIS groundwater treatments was 30.6 ± 0.13 g and 30.0 ± 0.39 g respectively. At the end of the experiment, the mean weights of fish in the diluted seawater and SIS groundwater treatments were 164.1 ± 3.57 g and 162.1 ± 4.14 g respectively (Table 3.4, Figure 3.2). There was no significant difference (F1,6 = 0.097, P = 0.766) in mean final weight of fish between the treatments.
The mean SGR of fish in the diluted seawater and SIS groundwater treatments were 1.39 ± 0.04%/day and 1.38 ± 0.02 /day respectively (Table 3.4, figure 3.2). There was no significant difference (F1,6 = 0.434, P = 0.534) for SGR between fish cultured in the two water types.
The apparent mean FCR of fish in the diluted seawater and SIS groundwater treatments were 0.97 ± 0.03 and 0.99 ± 0.03 respectively (Table 3.4, Figure 3.4). There was no significant difference (F1,6 = 0.042, P = 0.844) for apparent FCR of mulloway cultured in the two water types.
Table 3.3. Mean (± SE) dissolved oxygen (% saturation), pH, salinity (g/L), water temperature (oC) and total ammonia nitrogen (mg/L) for the different water type treatments in Experiment 1 over 122 days.
Parameter Diluted seawater SIS groundwater DO (% saturation) 89.7 ± 0.4 90.1 ± 0.2 pH 8.1 ± 0.03 8.0 ± 0.03 Salinity (g/L) 19.7 ± 0.05 19.7 ± 0.05 Water Temperature (oC) 21.8 ± 0.03 21.6 ± 0.03 Total ammonia nitrogen (mg/L) 0.9 ± 0.3 0.8 ± 0.3
Table 3.4. Mean (± SE) initial and final weights, biomass gain per tank, SGR (% body weight per day) and apparent feed conversion ratio (FCR), for mulloway cultured in diluted seawater and SIS groundwater in experiment 1 over 122 days (values that share a common superscript are not significantly different, P > 0.05).
Parameter Diluted seawater SIS groundwater Initial weight (g/fish) 30.6 ± 0.1a 30.0 ± 0.4a Final weight (g/fish) 167.3 ± 5.6a 162.0 ± 4.8a SGR (%/day) 1.39 ± 0.04a 1.38 ± 0.02a FCR 0.97 ± 0.02a 0.99 ± 0.03a
52 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Diluted seawater SIS groundwater 200
150
100 Mean weight (g) weight Mean 50
0 Feb-05 Mar-05 Apr-05 May-05 Jun-05
Figure 3.2. Mean monthly weights (± SE) for mulloway cultured in Experiment 1 for 122 days in SIS groundwater and diluted seawater for 122 days. Diluted seawater SIS groundwater 2.50
2.00
1.50
1.00 SGR (%/day) SGR
0.50
0.00 Mar-05 Apr-05 May-05 Jun-05
Figure 3.3. Mean specific growth rate (% body weight per day, ± SE) for mulloway cultured in Experiment 1 in SIS groundwater and diluted seawater for 122 days.
53 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Diluted seawater SIS groundwater 1.20
1.10
1.00 FCR
0.90
0.80 Mar-05 Apr-05 May-05 Jun-05
Figure 3.4. Mean apparent FCR (± SE) for mulloway cultured in diluted seawater and SIS groundwater in Experiment 1 for 122 days.
3.3.2 Experiment 2 Over the 45 days of the experiment. two mortalities were reported due to fish jumping out of tanks in the SIS groundwater treatment. Water quality parameters maintained during the trial were similar for all treatments (Table 3.5), although the mean water temperature in the seawater treatment tanks was 0.8oC higher than the diluted seawater treatment tanks and 1.1oC higher than the SIS groundwater treatment tanks.
The mean initial weights (g, ± SE) of fish in the diluted seawater, SIS groundwater and seawater treatments were 190.9 ± 7.0 g, 179.5 ± 7.0 g and 186.5 ± 8.0 g respectively. Mean final weights (g, ± SE) of fish in the diluted seawater, SIS groundwater and seawater treatments were 285.4 ± 12.0 g, 255.4 ± 7.3 g and 280.9 ± 6.9 g respectively (Table 3.6, Figure 3.5). There was no significant difference for final average weight between treatments (F2, 36 = 2.180, P = 0.117, Table 3.6). There were no significant difference for FCR (F2, 8 = 2.783, P = 0.140) and SGR (F2,8 = 4.0, P = 0.079) for fish cultured in the three water types (Table 3.6).
Table 3.5. Mean (± SE) dissolved oxygen (% saturation), pH, salinity (g/L), water temperature (oC) and ammonia (mg/L) in tanks used to culture mulloway in different water type treatments in Experiment 2 conducted over 45 days.
Parameter Seawater Diluted seawater SIS groundwater DO (% saturation) 86.8 ± 0.4 88.6 ± 0.3 89.5 ± 0.4 pH 7.4 ± 0.01 7.4 ± 0.01 7.9 ± 0.01 Salinity (g/L) 37.5 ± 0.02 20.9 ± 0.11 20.7 ± 0.57 Water Temperature (oC) 22.9 ± 0.04 22.1 ± 0.04 21.8 ± 0.04 Total ammonia nitrogen (mg/L) 0.7 ± 0.04 0.9 ± 0.05 0.8 ± 0.04
54 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Table 3.6. Mean (± SE) initial and final weights, biomass gain, SGR (% body weight per day) and apparent FCR for mulloway cultured in different water type treatments in Experiment 2 over 45 days (values that share a common superscript are not significantly different, P >0.05).
Parameter Seawater Diluted seawater SIS groundwater Initial weight (g/fish) 186.5 ± 4.0a 190.9 ± 6.1a 179.5 ± 2.8a Final weight (g/fish) 280.9 ± 6.9a 285.4 ± 12.0a 255.4 ± 7.3a SGR (%/day) 0.91 ± 0.06a 0.89 ± 0.03a 0.78 ± 0.03a FCR 0.95 ± 0.03a 0.94 ± 0.03a 1.20 ± 0.13a
Seawater Diluted seawater SIS Groundwater 300
250
200
Mean weight (g) 150
100 Sep-06 Oct-06 Date
Figure 3.5. Monthly mean weights (g, ± SE) for mulloway cultured in Experiment 2 in SIS groundwater, diluted seawater and seawater for 45 days.
3.3.3 Experiment 3 All fish survived the chasing procedure used to measure MMR. The results for RMR, MMR and MS were pooled as there was no significant difference between days for each treatment (P >0.05). After pooling the data, there was no significant difference (P >0.05) between RMR (F2, 33 = 0.008, P = 0.992), MS (F2, 33 = 0.116, P = 0.891) and MMR (F2, 33 = 0.178, P = 0.838) of mulloway maintained in the diluted seawater, SIS groundwater or seawater treatments (Figure 3.6).
55 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Routine
Maximum
)
r
h
/
g
/ Scope
l
o
m
μ
(
n
o
i
t
p
m
u
s
n
o
c
n
e
g
y
x
O
Diluted SIS groundwater Seawater seawater
Figure 3.6. Mean (± SE) routine metabolic rate (μmol O2/g/hr), metabolic scope (μmol O2/g/hr) and maximum metabolic rate (μmol O2/g/hr) of mulloway cultured in diluted seawater, SIS groundwater and seawater.
3.4 Discussion Survival of mulloway in both water types was high in all experiments, with the only mortalities due to fish jumping from tanks. Although not significantly different, the mean apparent FCR of mulloway cultured in SIS groundwater in Experiment 2 was higher than that recorded for fish in the other water types, and mean SGR and growth were also lowest for the fish cultured in SIS groundwater. It is possible that the lower mean weight of the SIS groundwater fish at the start of the trial contributed to the lower mean final weight of fish cultured in this water type. In addition, the mean water temperature of SIS groundwater treatment tanks were 0.3oC lower than tanks of the diluted seawater treatment and 1.1oC lower than tanks of the seawater treatment. These temperature differences cannot be explained as all tanks were randomly assigned to locations within the same temperature controlled room. These differences in mean water temperature during the trial may explain slightly poorer final weight, FCR and SGR achieved for mulloway in the SIS groundwater treatment when compared with results achieved in Experiment 1 where mean water temperature was the same in both water type treatments.
Using groundwater from the Wakool-Tullakool subsurface drainage scheme in south western New South Wales, Doroudi et al. (2006) reported maximum survival of mulloway at a
56 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
potassium concentration of 78.7 mg/L which was 38% of that present in equivalent salinity seawater. In a further trial, Doroudi et al. (2006) also reported maximum survival and growth of mulloway above a potassium concentration of 82.8 mg/L, or 40% of that present in equivalent salinity seawater. Results from both experiments support these results as no significant difference in growth was achieved between mulloway cultured in diluted seawater and in SIS groundwater with similar potassium concentrations. SIS groundwater used in Experiment 1 had a mean potassium concentration of 104 mg/L representing 47.6% of that found in equivalent salinity seawater, while in Experiment 2 the concentration of potassium was 83.7 mg/L representing 36.3% of the level found in equivalent salinity seawater. Although not significant, the slightly lower growth and SGR, and increased FCR for mulloway cultured in SIS groundwater in Experiment 2 compared to fish cultured in the other water types may be due to the slightly deficient level of potassium in the SIS groundwater from SPDB used for this experiment as the level is slightly below the minimum concentration of potassium required by this species (Doroudi et al., 2006).
During a 12 month sampling program (Chapter 2), the potassium concentration of SIS groundwater sampled at the outfall at SPDB varied between 81.2 mg/L and 92.6 mg/L with a mean concentration of 87.4 ± 1.46 mg/L (± SE). During this program, the potassium concentrations recorded represented values equivalent to between 40.9% and 49.1% of the concentration of potassium in seawater with a mean of 44.7 ± 1.0% (± SE). This suggests that the lower concentration of potassium in the SIS groundwater used in Experiment 2 was not typical of the groundwater discharged into SPDB.
The apparent FCR and SGR of mulloway cultured in SIS groundwater was 0.99 ± 0.03%/day and 1.38 ± 0.02%/day respectively in Experiment 1 when fish grew from 30.0 ± 0.4 g to 162.0 ± 4.8g over the 122 days. FCR and SGR values were 1.22 ± 0.13%/day and 0.78 ± 0.03%/day respectively in Experiment 2 when fish grew from 179.5 ± 0.13 g to 255.4 ± 7.3 g over 45 days. These FCR and SGR values compare favourably to values recorded in other studies conducted on mulloway. Partridge et al. (2006) grew mulloway in a semi-intensive floating tank system located in a lined pond exposed to ambient conditions, and reported that when water temperatures exceeded 21oC fish grew from 116 g to 384 g over 174 days with an FCR of 1.39 and an SGR of 0.68%/day. Mulloway cultured for eight months (243 days) in 500 L tanks supplied with saline groundwater grew from 10.8 ± 2.1 g to 270 ± 35 g with an FCR of 2.1 and achieved an SGR of 1.31%/day (Doroudi et al., 2006).
Conversion of results of Experiment 3 from μmolO2/g/hr to mgO2/kg/hr allows comparison with the only other metabolic study conducted on mulloway by Fitzgibbon et al. (2007); and results obtained from a related species, red drum, Sciaenops ocellatus (Forsberg and Neill, 1997 (Table 3.7) maintained in low salinity conditions (i.e. 3 g/L and 6 g/L). In the study by Fitzgibbon et al. (2007), SMR was determined by extrapolation of an oxygen consumption (Mo2) swimming velocity relationship to a velocity of zero, and metabolic scope was determined by subtraction of SMR from active metabolic rate (AMR) recorded at a maximum sustained swimming velocity. These studies show that the RMR of these Sciaenids varies between 72 mgO2/kg/hr and 230 ± 20 mgO2/kg/hr and MS varies between 120 ± 7.5 mgO2/kg/hr and 292 ± 17.6 mgO2/kg/hr. Differences in values of the metabolic parameters recorded in these studies may be attributed to differences the methods used with a chasing approach (Powell et al., 2005) used in Experiment 3 while Fitzgibbon et al. (2007) used an
57 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
850 L Brett-type water tunnel respirometer constructed by modification of a flume tank, and Forsberg and Neill (1997) used automated respirometry. The key outcome for aquaculture from the metabolic studies on mulloway conducted by Fitzgibbon et al. (2007) is demonstration of suppression of MS at levels of hypoxia of 75%, 50% and 25% saturation. These results suggest that although mulloway can survive in lower than optimal levels of dissolved oxygen, it is likely that there will be energy budgeting conflicts in hypoxic conditions that may reduce energy available for growth resulting in reduced production from aquaculture systems (Fitzgibbon et al., 2007).
Table 3.7. Comparison of metabolic parameters (mgO2/kg/hr; mean ± SE) for mulloway recorded in experiment 3 with those determined by Fitzgibbon et al (2007); and for red drum, Sciaenops ocellatus (Forsberg and Neill, 1997).
Source RMR MMR MS Experiment 3 129 ± 2.8 249 ± 12.0 120 ± 7.5 SMR AMR Fitzgibbon et al., 2007 72 365 ±19.7 292 ±17.6 RMR Forsberg and Neill, 1997 230 ± 20 (3 g/L) 140 ± 20 (3 g/L) Red drum, Sciaenops ocellatus 210 ± 10 (6 g/L) 120 ± 10 (6 g/L)
In Experiment 3, the lack of significant differences between RMR, MS and MMR recorded suggests that metabolism of mulloway did not change significantly when fish were exposed to the differences in salinity and ionic composition represented by the water type treatments. This indicates that the energy saving advantages suggested for marine fish exposed to salinities approaching their iso-osmotic point (Gaumet et al., 1995; Imsland et al., 2008) may not confer the same benefits to a euryhaline species such as mulloway. Although no metabolic studies were conducted during studies on another euryhaline fish species, black bream (Acanthopagrus butcheri), no significant differences were demonstrated for growth, FCR and SGR for fish cultured for six months at salinities ranging from 12–48 g/L (Partridge and Jenkins, 2002). Similarly, no significant salinity effects on growth were observed for hatchery reared larvae of the euryhaline species, greenback flounder (Rhombosolea tapirina) cultured at 15 g/L, 25 g/L and 35 g/L (Hart et al., 1996).
58 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
3.5 Conclusions and Recommendations Survival of mulloway in each water type was high in all experiments with the only mortalities recorded attributed to fish jumping from tanks. In these experiments no significant difference in growth, apparent FCR or SGR was recorded for mulloway cultured in SIS groundwater, diluted seawater and in seawater. These results suggest that mulloway perform the same in SIS groundwater from SPDB as they do in equivalent salinity seawater and full salinity seawater.
The absence of growth effects with mulloway supports the results of the metabolism experiment and suggests that the metabolism of this euryhaline species may not change in response to the different salinity and ionic conditions investigated. It is suggested that the level of salinity and potassium in SIS groundwater from SPDB is sufficient to support levels of growth and performance of mulloway equivalent to those achieved by fish cultured in seawater of a similar salinity and in full salinity seawater. These results combined with other information available for mulloway suggest that this species should be considered as suitable for culture in SIS groundwater.
59 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
3.6 References Collet, P.D., Vine, N.G., Kaiser, H. and Baxter, J. 2008. Determination of the optimal water temperature for the culture of juvenile dusky kob, Argyrosomus japonicus Temminck and Schlegel 1843. Aquaculture Research 39: 979 – 985. Doroudi, M.S., Fielder, D.S., Allan, G.L. and Webster, G.K. 2006. Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Aquaculture Research 37: 1034– 1039. Fielder, D.S. and Bardsley, W. 1999. A preliminary study on the effects of salinity on growth and survival of mulloway Argyrosomus japonicus larvae and juveniles. Journal of the World Aquaculture Society, 30: 380–387. Fitzgibbon, Q.P., Strawbridge, A. and Seymour, R.S. 2007. Metabolic scope, swimming performance and the effects of hypoxia in the mulloway, Argyrosomus japonicus (Pisces: Sciaenidae). Aquaculture 270: 358–368. Forsberg, A.J and Neill, W.H. 1997. Saline groundwater as an aquaculture medium: Physiological studies on the red drum, Scaenops ocellatus. Environmental Biology of Fishes 49: 119–128. Gaumet, F., Boueuf, G., Severe, A., Le-Roux, A. and Mayer-Gostan, N. 1995. Effects of salinity on the ionic balance and growth of juvenile turbot. Journal of Fish Biology. 47(5): 865–876. Gommon, M.F., Glover, J.C.M. and Kuiter, R.H. (Editors). 1994. The fishes of Australia’s south coast. The Flora and Fauna of South Australia Handbooks Committee. State Print, Adelaide, 922 pp. Hall, D.A. 1986. An assessment of the mulloway (Argyrosomus hololepidotus) fishery in South Australia with particular reference to the Coorong Lagoon. Department of Fisheries, South Australia, 41 pp. Hart P.R., Hutchinson W.G. and Purser, G.J. 1996. Effects of photoperiod, temperature and salinity on hatchery reared larvae of the greenback flounder (Rhombosolea tapirina Gunther, 1862) Aquaculture 144: 303–311. Hayward, C. J., Bott, N.J., Itoh, N., Iwashita, M., Okihiro, M. and Nowak, B.F. 2007. Three species of parasites emerging on the gills of mulloway, Argyrosomus japonicus (Temminck and Schlegel, 1843), cultured in Australia. Aquaculture 265: 27–40. Imsland, A.C., Gústavsson, A., Gunnarsson, S., Foss, A., Árnason, J., Árnarson, I., Jónsson, A.F., Smáradóttir, H. and Thorarensen, H. 2008. Effects of reduced salinities on growth, feed conversion efficiency and blood physiology of juvenile Atlantic halibut (Hippoglossus hippoglossus L). Aquaculture 274: 254–259. Jobling, M. (Editor), 1994. Fish bioenergetics. Chapman and Hall, London, 389 pp. Jones, G.K., Hall, D.A., Hill, K.L. and Staniford, A.J. 1990. The South Australian marine scale fishery: Stock assessment, economics and management. Green Paper, South Australian Department of Fisheries, Adelaide, 186 pp.
60 Chapter 3 – Assessment of the performance of mulloway (Argyrosomus japonicus) cultured in saline groundwater from Stockyard Plain Disposal Basin.
Kailola, P.J., Williams, M.J., Stewart, R.E., Reichelt, R.E., McNee, A. and Greive, C. 1993. Australian Fisheries Resources. Bureau of Resources Sciences and the Fisheries Research and Development Corporation, 422 pp. Partridge, G.J. and Jenkins, G.I. 2002. The effect of salinity on growth and survival of juvenile black bream (Acanthopagrus butcheri). Aquaculture 210: 219–230. Partridge, G.L, Lymbery, A.J., and George, R.J. 2008. Finfish mariculture in inland Australia: A review of potential water sources, species and production systems. Journal of the World Aquaculture Society 39(3) 291–310. Partridge, G.J., Sarre, G.A., Ginbey, B.M., Kay, G.D. and Jenkins, G.I. 2006. Finfish production in a static, inland saline water body using a Semi-Intensive Floating Tank System (SIFTS). Aquaculture Engineering 35: 109–121. Powell, M.D., Speare, D.J, Daley, J. and Lovy, J. 2005. Differences in metabolic response to Loma salmonae infection in juvenile rainbow trout Oncorhynchus mykiss and brook trout Salvelinus fontinalis. Diseases of Aquatic Organisms 67: 233–237. Ruello, N. 2004. Inland saline aquaculture: Market and supply chain development. Report prepared for the National Aquaculture Council. Ruello and Associates Pty Ltd, 60pp. Shearer, K.D. 1988. Dietary potassium requirements of juvenile Chinook salmon. Aquaculture 73: 119–129. Teeter, R. 1997. The electrolyte: Acid-base connection. Feed Mix 5(4): 32–34. Wilson, R.P. and El Naggar, G. 1992. Potassium requirement of fingerling channel catfish, Ictalurus punctatus. Aquaculture 108: 169–175.
61 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
Chapter 4 – Assessment of the performance of snapper, Pagrus auratus, cultured in saline groundwater from Stockyard Plain Disposal Basin
4.1. Summary Snapper are a premium seafood species in Australia, attracting good market prices, and have been previously investigated for commercial aquaculture in NSW, Western Australia and South Australia.
The two most significant problems that confront snapper aquaculture are the relatively poor growth rate in seacages to achieve market size (400–500 g) and the poor appearance of product due to darkening of the skin during culture. The use of saline groundwater from SIS offers potential to overcome these problems by culturing snapper at a relatively constant optimal water temperature within a covered system to reduce light exposure that is responsible for darkening of the skin.
Most groundwater supplies are deficient for potassium, and other studies have shown lack of this physiologically important ion can cause reduced growth and total mortality in highly deficient saline groundwater sources. To investigate the suitability of SIS groundwater for snapper culture, two trials were conducted: Experiment 1. Snapper growth in SPDB groundwater Experiment 2. Metabolic response of snapper cultured in SPDB groundwater
Results from these experiments demonstrated a significant reduction in growth and increase in RMR for snapper cultured in SIS groundwater from SPDB compared to fish cultured in equivalent salinity (i.e. diluted) seawater. These results were observed after 28 days and it is suggested that a reduced level of potassium in the SIS groundwater is the most likely factor contributing to the reduced performance of snapper cultured in this water type.
4.2. Background Snapper (Pagrus auratus) are found in coastal waters of all southern Australian states below 18oS, and are widely distributed throughout warm, temperate and sub-tropical waters of the Indo-Pacific region extending to New Zealand, Indonesia, India and Japan (Kailoa et al., 1993). Historically, the annual Australian catch of snapper has been in excess of 2,400 tonnes (Kailoa et al., 1993) but in recent years has ranged from 1,700 to 1,900 tonnes (Anon., 2006). Snapper are a premium seafood species in Australia attracting good market prices averaging approximately $10.00/kg (SAFCOL Central Fish Market).
Snapper were the first marine finfish species investigated for aquaculture in South Australia. A significant advantage offered by snapper was that methods for hatchery rearing to provide mass production of fingerlings for aquaculture were established in Japan around 1970 and by
63 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
1988 Japanese snapper production was 45,000 tonnes (Anon., 1990). From 1993 until 1996 SARDI conducted pilot scale sea cage grow-out trials of wild caught juvenile snapper and hatchery reared fingerlings at the BHP marina at Whyalla. These trials were conducted in collaboration with members of the Northern Spencer Gulf Aquaculture Enterprise Inc. (NSGAE) to evaluate growth potential and provide opportunity for members to gain exposure to husbandry practices and evaluate viability of this species. A number of NSGAE members formed the commercial hatchery Spencer Gulf Aquaculture Pty Ltd (SGA) at Port Augusta which subsequently formed the seacage farming group South Australian Aquaculture Management Pty Ltd (SAAM) that established sea cage grow-out sites in Fitzgerald Bay, north of Whyalla.
From 1997 until 2001 snapper were grown in seacages by four private groups with coastal lease sites in Franklin Harbour at Cowell (two private groups), in Fitzgerald Bay, and in Boston Bay at Port Lincoln. During this period, two commercial hatcheries commenced operations, the first at Port Augusta (Spencer Gulf Aquaculture) and the other at Arno Bay (Clean Seas Aquaculture). In South Australia, snapper production of 60 tonnes was reported in 1998–99 and 1999–2000. However, aquaculture production of snapper in Australia was only 0.2 tonnes in the 2004–05 financial year (O’Sullivan, et al., 2007). No production of snapper is currently being undertaken in South Australia due to a combination of factors including: • relatively poor growth rate in seacages requiring 18–24 months to achieve market size (400–500 g) • poor appearance of product due to melanisation (dark colour) of skin due to light exposure, and reduced market price and demand for perceived lower quality fish • preference for culture of fast growing yellowtail kingfish (Seriola lalandi) • limited availability of leases with tuna and kingfish as preferred species
It is suggested that farmed snapper have attractive market prospects as the product is well regarded by seafood merchants and there is a substantial unmet demand and in particular, there is an increasing demand-supply gap for plate size fish due to diminishing wild fish supply and fishing regulations that prevent capture of this size snapper in some Australian states (Ruello, 2004).
The availability of saline groundwater from SISs at a constant elevated temperature provides the capacity to supply a relatively constant favourable culture environment that would improve the growth rate of snapper. In a previous project conducted by SARDI at CPISARC, snapper were grown from 10 g to market size (approximately 400 g) in approximately 9.5 months. In this study, fish were cultured in saline groundwater in a recirculating aquaculture system that provided temperature control between 22– 0C and 250C.
The potential for culture of snapper in saline groundwater is also advantaged by the ability to conduct rearing within tanks located under a roof structure or within an enclosed shed to restrict light to reduce melanisation and allow skin pigmentation similar in appearance to wild caught fish to be achieved. This is difficult to achieve in seacage situations, although Booth et al. (2004) demonstrated that the addition of the carotenoid pigment astaxanthin to a formulated diet at levels of 36 mg/kg and 72 mg/kg significantly increased skin redness.
64 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
These researchers also compared the effects of astaxanthin pigment source (Carophyll Pink™ and NatuRose™) and shading (50% and 95%) on skin colour of snapper (approximately 800 g) held in small experimental cages (1 m3) positioned within 25 m2 seacages. This trial found no significant difference in the skin lightness between the two levels of shading but observed that fish in the 95% shading treatment tended to be lighter than those in the 50% shading treatment. Both pigment types significantly increased the redness of fish fed diets without supplemental astaxanthin (Booth et al., 2004). These results suggest that growth rate and skin colour can be managed in culture systems utilising SIS groundwater to provide the possibility for commercial snapper aquaculture in inland locations aligned to SISs. This will depend on SIS groundwater having the suitable salinity and ionic composition to support optimal growth and survival of this species.
Previous studies have shown that snapper grew equally well in diluted seawater with a salinity of 16 g/L and seawater with a salinity of 32 g/L (Partridge and Furney, 2001). Woo and Fung (1981) reported that red sea bream, Chrysophys major (now recognised as the same species as snapper, Pagrus auratus), was able to adapt to reduction in salinity until this was less than the iso-osmotic level (340 m Osm/kg). Wu and Woo (1983) suggest that shallow water, near shore species of fish such as snapper are tolerant of changes in salinity up to a critical limit in the range of 5–10 g/L. Trials on snapper cultured at elevated salinities have shown that growth of this species is reduced when salinity exceeds 48 g/L (Hutchinson et al., 1997). This information suggests that snapper are likely to grow equally well in systems supplied with groundwater sources with salinity between 10 g/L and 48 g/L. Salinity is not the only factor that needs to be considered as the ionic composition of saline groundwater is generally different than that of seawater, and excesses and deficiencies of physiologically important ions may also affect the growth and survival of snapper in these water sources. The suitability of saline groundwater for snapper culture has been investigated (Fielder et al. 2001). This study showed that all juvenile snapper (Pagrus auratus) lost equilibrium of buoyancy and floated upside down, did not feed and died within four days following transfer from oceanic seawater diluted to the same salinity (19 g/L) as saline groundwater from evaporation ponds of the Warkool-Tullakool Subsurface Drainage Scheme at Warkool, western New South Wales. The level of K+ in this groundwater is 9.2 mg/L equal to only 4.5% of that present in equivalent salinity seawater (203 mg/L). Comparable growth performance was achieved with snapper when this groundwater was supplemented with K+ to 60–100% (>134 mg/L) of the level present in equivalent salinity seawater. These authors also investigated the ratio of potassium to chloride (K+/Cl-) and determined that snapper survived and grew when this ratio was greater than 0.007, but maximum growth was achieved when K+/Cl- was greater than 0.01 and the fish died if the ratio was less than 0.007.
One approach to investigation of the suitability of water type for culture of fish is to measure their metabolic rate in the water type of interest compared with that observed for fish in seawater. Typically, metabolic rate is considered to comprise the energy used to support routine metabolism, activity and growth (Cunha et al., 2007). In view of this, a trial was conducted to investigate the growth and survival of snapper cultured in saline groundwater from the SPDB compared to performance of fish in equivalent salinity seawater. It was anticipated that the results of this trial would allow assessment of the suitability of this water source to directly support culture of snapper or alternatively if further modification of the composition of this water source would be required. To determine the effects of SIS
65 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
groundwater on snapper growth, performance and metabolism, two trials were conducted to provide information upon which to assess the suitability of this water source for culture of this species: • Experiment 1. Snapper growth in SPDB groundwater • Experiment 2. Metabolic response of snapper cultured in SPDB groundwater.
4.3. Methods
4.3.1. Experiment 1 – Snapper Grown in SPDB Groundwater From 22 February 2006 until 24 April 2006 (62 days), a growth experiment was conducted at the SAASC. The two treatments compared were diluted seawater (19–20 g/L) and SIS groundwater from the SPDB (19–20 g/L). The groundwater used in the experiment was pumped from the inflow to SPDB and transported by road tanker (22 kL) to SAASC where it was held in storage reservoirs until use. Samples of each water type were analysed for composition of major ions (Table 4.1) for comparison with seawater supplied to SAASC.
The experiment was conducted in an insulated room at SAASC, maintained at constant temperature of 22oC. The light regime for the experiment was 8.5 hours light and 15.5 hours darkness each day. Four replicate tanks (800 L capacity) were used for each treatment and each tank was stocked with 30 fish. Fish used in this experiment (n = 240) were obtained from the Aquaculture Development Unit, Challenger TAFE, Fremantle, Western Australia.
Initial mean weight for fish in the diluted seawater treatment and the SPDB treatment was 22.9 ± 0.8 g and 22.5 ± 0.7 g respectively. All fish were initially acclimatised to 19–20 g/L over five days by addition of freshwater from a bore to progressively dilute oceanic water by approximately 3 g/L each day. When the desired salinity was achieved a complete water replacement was undertaken for all SPDB treatment tanks.
Eight individual recirculating aquaculture systems (Figure 4.1) were constructed to undertake the growth experiment. Each recirculating aquaculture system had the same sized water treatment components to maintain optimum water quality for the duration of the experiment, including: • Dacron™ mechanical filter material • biological trickle filter (20 L plastic media) • submerged biological filter (20 L plastic media) • foam fractionator • sump (70 L) with submersible pump (Pondmaster™ 3600, 3200 L/hr) • aeration provided to each tank using a single air stone.
66 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
Table 4.1. Composition of seawater, iso-osmotic and saline groundwater sources used in Experiment 1 (mg/L unless stated). Analysis carried out by AWQC, SA Water.
SPDB Element or chemical Seawater Diluted seawater Groundwatera Salinity (g/L) 36 19 18 pH 8.2 8.3 8.0
Major ions Chloride 22,100 11,600 10,800 Sodium 11,700 6,300 6,250 Sulphate 2,940 1,640 1,620 Magnesium 1,430 782 532 Potassium 461 252 104 Calcium 422 254 424
Minor ions Fluoride 0.84 0.88 1.4 Total phosphorus 0.021 0.027 0.022 Aluminium 0.061 0.096 0.121 Boron 4.67 2.72 3.06 Bromide 81.5 40.9 6.47 Copper <0.01 <0.01 <0.01 Iodide <0.1 <0.5 <0.5 Iron 0.008 0.436 0.072 Lithium 0.16 0.09 0.17 Manganese <0.005 <0.005 0.068 Mercury <0.0003 <0.0003 <0.0003 Molybdenum <0.005 <0.005 <0.005 Strontium 8.573 4.624 19.950 Zinc <0.03 <0.03 <0.03 Tin <0.005 <0.005 <0.005 Nickel <0.005 <0.005 <0.005 Silica <1.0 11 22 Bicarbonate 151 256 456 a Saline groundwater was sourced from the ‘outfall’ of the Stockyard Plains Disposal Basin, Waikerie, South Australia.
Fish in each tank were fed three times per day to satiation using a closed formula commercial diet, Nova ME (Skretting, Cambridge, Tasmania). Feed consumed was calculated from the amount of feed remaining at the end of each day in pre-weighed feed containers assigned to each tank. Approximately 30% of water was exchanged from each system each week as two exchanges of 70–80 L each Monday and Friday.
Water quality parameters for each tank were measured each day. Dissolved oxygen (% saturation) and water temperature (oC) were measured using an OxyGuardTM Handygamma dissolved oxygen meter (OxyGuard International A/S, Birkerød, Denmark). The pH and salinity (g/L) were measured daily using a WTW 340i SET pH and conductivity
67 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
+ meter (Wissenschaftlich-Technische Werkstätten, Weilheim, Germany). Ammonium (NH4 , mg/L) was recorded weekly using an RQflex 10 meter (Merck KgaA, Darmstadt, Germany).
Figure 4.1. Layout of eight experimental tanks and associated components of individual recirculating water treatment systems used to culture snapper in different water types at SAASC.
4.3.2. Experiment 2 – Metabolic Response of Snapper Cultured in SIS Groundwater Some of the information for Trial 2 in this report has been taken from an unpublished Masters thesis written by Tim Flowers, done as part of this CNRM project. A full explanation of this trial will be presented in his thesis.
The metabolism of snapper in the two different water types was investigated after completion of experiment 1. The system used for this investigation consisted of two 1,000 L tanks functioning as water reservoirs for each of the water types. A submersible pump (PondMaster® 3600; Danner Manufacturing, Islandia, New York, USA) in each reservoir supplied water through a six-way manifold connecting to a bank of six respirometer chambers (volume = 2.1 ± 0.2 L; average ± SE), each receiving water at an average flow rate of 0.04 ± 0.001 L/s; average ± SE. Water exiting each chamber overflowed back into the reservoir that was continually aerated to maintain dissolved oxygen at 95–100% saturation. Fish were starved for 24 hours before the respirometer chambers were stocked with a sub- sample of six randomly selected snapper from each of the two treatments (n = 12 fish).
68 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
The method and equipment described by Powell et al., (2005) was used to measure RMR and MMR of each fish. RMR was determined for an individual fish by calculating the oxygen consumption rate in a respirometer box when the water flow was stopped. MMR was determined after measurement of RMR by transferring individual fish into a 100 L tub containing approximately 40 L water and vigorously chasing them using a PVC pole for approximately five minutes until fish were unresponsive to touch. Fish were then returned to the allocated respirometer chamber and another respiration rate determination made (MMR). MS was calculated by subtracting RMR from MMR for each fish. Both metabolic rate calculations were determined with consideration of background oxygen consumption from measurements taken in a control respirometer chamber with no fish added.
4.3.3. Statistical Analysis SPSS version 10 was used to conduct all statistical analyses. Mean values are displayed with standard errors (± SE). Data were tested for heterogeneity of variance and transformed if required. A repeated measures ANOVA was used to test the effects of treatments on mean weight, SGR and FCR over time. Significant differences between treatment means were identified using a Tukey’s test.
4.4. Results
4.4.1. Experiment 1 No fish died due to the ionic composition of saline SPDB groundwater over the duration of the experiment (62 days). The only mortalities recorded occurred as a result of fish jumping out of the tanks (diluted seawater = 6:SPDB = 14). Water quality data was similar between treatments throughout the experiment (Table 4.2).
Table 4.2. Mean (± SE) water temperature (oC), dissolved oxygen (% saturation), pH, salinity (g/L), and total ammonia nitrogen (mg/L) for different water type treatments over 62 days.
Water Dissolved temperature oxygen Salinity Total ammonia Treatment (oC) (% sat) pH (g/L) nitrogen (mg/L) Diluted seawater 21.8 ± 0.03 89.7 ± 0.4 8.1 ± 0.01 19.7 ± 0.05 0.9 ± 0.3 SPDB 21.6 ± 0.03 90.1 ± 0.2 8.0 ± 0.01 19.7 ± 0.05 0.8 ± 0.3 groundwater
After 62 days, the mean final weight (Table 4.3, Figure 4.2) of fish in the diluted seawater treatment was significantly greater than the SPDB groundwater treatment (F1.96, 424.5 = 4.56, P = 0.012). The mean FCR (Table 4.3, Figure 4.3) was not significantly different (F1, 6 = 0.18, P = 0.689) between the diluted seawater treatment and the SPDB treatment. There was also no significant difference (F1, 6 = 2.74, P = 0.149) between SGR (Table 4.3, Figure 4.4) of fish cultured in the diluted seawater and the SPDB treatment.
Table 4.3. Comparison of mean weight (g ± SE), FCR and SGR of snapper cultured in diluted seawater and SPDB groundwater for a period of 62 days.
69 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
Factor Diluted seawater SPDB Groundwater Mean weight (g) 79.1 ± 2.2a 65.9 ± 1.4b FCR 0.91 ± 0.02a 1.12 ± 0.09a SGR (%) 2.0 ± 0.06a 1.7 ± 0.07a
4.4.2. Experiment 2 The results for RMR, MMR and MS were pooled as there were no significant differences between days for each parameter (p>0.05). After pooling the data, there was a highly significant difference between treatments for RMR and MMR (both p<0.05). The mean RMR and MMR for snapper cultured in SPDB groundwater were 41.8% and 24.9% greater respectively than snapper cultured in diluted seawater (Figure 4.5). However, there was no significant difference in MS between treatments (F1, 23 = 0.243, p = 0.627).
100.0 Diluted Seawater SPDB 80.0
60.0
40.0
Mean weightMean (g) 20.0
0.0 Feb-06 Mar-06 Apr-06 Date
Figure 4.2. Monthly mean weight (g, ± SE) of snapper cultured in diluted seawater and SPDB groundwater for 62 days.
70 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
1.40
)
R Diluted seawater SPDB
C
F
(
o
i
t 1.20
a
R
n
o
i
s
r
e 1.00
v
n
o
C
d
e
e 0.80
F
n
a
e M 0.60 Mar-06 Apr-06 Date
Figure 4.3. Monthly mean feed conversion ratio (FCR) of snapper cultured in diluted seawater and SPDB groundwater for 62 days.
3.0 Diluted Seawater SPDB
2.5
2.0
1.5 Mean Rate (SGR) Specific Growth 1.0 Mar-06 Apr-06 Date
Figure 4.4. Monthly mean specific growth rate (SGR) of snapper cultured in diluted seawater and SPDB groundwater for 62 days.
71 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
Routine
)
r
h
/ Maximum
g
/
l o Scope
m
μ
(
n
o
i
t
p
m
u
s
n
o
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e
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Diluted seawater SPDB groundwater
Figure 4.5. Mean routine metabolic rate, metabolic scope and maximum metabolic rate (µmol02/g/hr, ± SE) for snapper cultured in diluted seawater water and saline groundwater from SPDB.
4.5. Discussion It suggested that the composition of SPDB groundwater has contributed to the reduced performance of snapper cultured in this water type. Analysis of the water types used show that the SPDB groundwater contained only 41.3% (104 mg/L, Table 4.1) of the level of potassium found in the diluted seawater (254 mg/L) used in this experiment. As previously discussed, Fielder et al. (2001) showed that snapper require the level of potassium to be in excess of 60% of that found in equivalent salinity seawater. The results observed in the experiment conducted suggest that a reduced level of potassium in the SIS groundwater is the most likely factor contributing to the reduced growth of snapper cultured in this water type.
Results of this experiment show that snapper expended significantly more energy for routine metabolic processes in SIS groundwater than in diluted seawater. RMR was 41% greater for fish in the SIS groundwater (SPDB) treatment than fish in diluted seawater treatment, and the MMR for fish in this treatment was 21.9% higher than the level recorded for fish in diluted seawater. The lack of any significant difference in MS of snapper cultured in SPDB groundwater and diluted seawater suggests that MS is defended by snapper cultured in groundwater. However, the relative proportion of MMR represented by MS was only approximately 32.0% for snapper in SPDB groundwater compared to 46.7% of MMR for fish cultured in diluted seawater (Figure 4.6).
72 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
Scope Routine 100%
90%
80%
70%
60%
50%
40%
30%
20%
10% Percentage of Maximum Metabolic Rate Metabolic Maximum of Percentage 0% SPDB Groundwater Diluted seawater
Figure 4.6. Comparison of the relative proportion of maximum metabolic rate attributed to metabolic scope and routine metabolic rate for snapper cultured in SPDB groundwater and diluted seawater.
An explanation for the additional energy expenditure required for snapper cultured in saline groundwater is most likely to relate to the additional requirements for energy consuming (i.e. active) processes required to maintain a suitable osmotic state within fish cultured in water that is deficient in important ions. It is suggested that the most likely ion involved may be potassium as it is deficient in SIS groundwater and is known to be an essential ion required to maintain the electrolyte and acid balance of marine fish (Wilson and El Naggar, 1992; Shearer, 1988). Potassium is the major cation of intracellular fluids, and sodium and chloride are the major extracellular anions involved in osmoregulation (Teeter, 1997). It is likely that the lower than optimal concentration of potassium in SIS groundwater requires greater energy expenditure by snapper to maintain a constant extracellular and intracellular osmolality as has been suggested for red drum, Sciaenops ocellatus (Bryan et al., 1988). This information supports the suggestion that the increased RMR reported for snapper in SPDB groundwater is a result of the additional routine energy expenditure required for osmoregulation by snapper in potassium deficient water, resulting in the reduced growth observed in this experiment.
Although a similar amount of energy is partitioned for MS by snapper in SPDB groundwater and diluted seawater, this amount represents a relatively smaller proportion of the total energy expenditure of snapper growing in the saline groundwater. It is suggested that the elevated RMR has contributed to a reduced growth rate of snapper maintained in saline groundwater from SPDB. This conclusion is supported by data from this study that shows that although not significant, there was a trend for snapper in SIS groundwater to have a higher FCR and a lower SGR suggesting that a lower proportion of energy intake is partitioned for growth by fish in this water type.
73 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
4.6. Conclusion and Recommendations The results from both experiments conducted indicate that snapper prefer diluted seawater to SPDB groundwater as demonstrated by the significant reduction in growth and increase in RMR and MMR recorded for fish cultured in groundwater from SPDB. In addition, a statistically significant difference (P<0.05) in growth between snapper cultured in diluted seawater and SPDB groundwater was detected after the first 28 days of the experiment. To observe a difference in growth after a short time interval has significant implications for the commercial viability of snapper grown in raw SPDB groundwater, and it is suggested that this species is not suitable for aquaculture using the groundwater available from this SIS.
Further physiological research will be required to fully elucidate the mechanisms involved that have contributed to the results observed for snapper in SPDB groundwater.
74 Chapter 4 – Assessment of the performance of snapper (Pagrus auratus) cultured in saline groundwater from Stockyard Plain Disposal Basin
4.7. References Anon. 2006. ABARE 2006, Australian Fisheries Statistics 2005, Canberra, p. 68. Anon. 1990. The “king of fish”, its history and development as fishery. Fishery Journal No. 33. Yamaha Motor Co. Ltd. Shizuoka-ken, Japan. Booth, M.A., Warner-Smith, R.J., Allan, G.L. and Glencross, B.D. 2004. Effects of dietary astaxanthin source and light manipulation on the skin colour of Australian snapper Pagrus auratus (Bloch & Schneider, 1801). Aquaculture research 35: 458–464. Bryan, J.D., Ham, K.D. and Neill, W.H. 1988. Biophysical model of osmoregulation and its metabolic cost in red drum. Contrib. Mar. Sci. 30: 169–182. Cunha, I., Conceicao, E.C. and Planas, M. 2007. Energy allocation and metabolic scope in early turbot, Scophthalmus maximus, larvae. Mar. Biol. 151: 1397–1405. Fielder, D.S., Bardsley, W.J. and Allan, G.L. 2001. Survival and growth of Australian snapper, Pagrus auratus, in saline groundwater from inland New South Wales, Australia. Aquaculture 201: 73–90. Hutchinson, W.G., Mawer, S. and Clarke, S. 1997. Development of snapper (Pagrus auratus) aquaculture in the Upper Spencer Gulf region of South Australia. Part A: Research Report. SARDI Aquatic Sciences, 44 pp. Kailoa, P.J., Williams, M.J., Stewart, P.C., Reichelt, R.E., McNee, A. and Grieve, C. 1993. Australian fisheries resources. Bureau of Resource Sciences and the Fisheries Research and Development Corporation, Canberra. Imprint Ltd., Brisbane. O’Sullivan, D., Savage, J. and Fay, A. 2007. Status of Australian Aquaculture in 2004/05, Austasia Aquaculture Trade Directory 2007. Partridge, G.J. and Furney, A. 2001. Culturing snapper in Dumbleyung—a case study for determining the potential for inland saline groundwater to grow marine fish in Western Australia. 8th National Conference and Workshop on Productive Use and Rehabilitation of Saline Lands (PUR$L), September 16–20, 2002. Fremantle, Western Australia, Australia. Promaco, Perth, Australia. Powell, M.D., Speare, D.J., Daley, J. and Lovey, J. 2005. Difference in metabolic response to Loma salmonae infection in juvenile rainbow trout, Oncorhynchus mykiss, and brook trout, Salvelinus fontinalis. Diseases of Aquatic Organisms 67: 233–237. Ruello, N. 2004. Inland saline aquaculture market and supply chain development. Report prepared for the National Aquaculture Council by Ruello and Associates Pty Ltd, Clifton Beach, Queensland, 60 pp. SAFCOL Central Fish Market (A division of SAFCOL Australia Pty. Ltd.) http://www.safcol.com.au/SpeciesSalesGeneral.html. Shearer, K.D. 1988. Dietary potassium requirements of juvenile Chinook salmon. Aquaculture 73: 119–129. Wilson and El Naggar, G. 1992. Potassium requirement of fingerling channel catfish, Ictalurus punctatus. Aquaculture 108: 169–175.
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Woo, N.Y.S. and Fung, A.C.Y. 1981. Studies on the biology of the red sea bream, Chrysophys major – II. Salinity adaptation. Comp. Biochem. Physiol. Vol. 69A: 237– 242. Wu, R.S.S. and Woo, N.Y.S. 1983. Tolerance of hypo-osmotic salinities in thirteen species of adult marine fish: Implications for estuarine fish culture. Aquaculture 32: 175 – 181
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Chapter 5 – Evaluation of yellowtail kingfish, Seriola lalandi, in saline groundwater
5.1. Summary Globally, the production of yellowtail kingfish amberjack species (Seriola spp.) is well established in coastal and near oceanic waters. The local species, the yellowtail kingfish (Seriola lalandi) is currently being produced commercially in seacages in South Australian coastal waters and there is ongoing expansion of this industry. This study was undertaken to investigate the potential for culture of yellowtail kingfish in saline groundwaters (salinity approximately 20 g/L) available from the Woolpunda, Waikerie and Qualco-Sunlands SIS in the Riverland region of South Australia. If preliminary studies are successful, the culture of yellowtail kingfish in SIS groundwater may contribute to further industry expansion in South Australia.
A series of three experiments were conducted to evaluate the suitability of yellowtail kingfish for culture using saline groundwater from SISs in the Riverland region of South Australia. They were as follows: Experiment 1. Preliminary assessment of the survival and growth of yellowtail kingfish in SIS groundwater Experiment 2. Metabolic responses of yellowtail kingfish cultured in SIS groundwater Experiment 3. Assessment of the growth and survival of yellowtail kingfish in standard seawater, diluted seawater, SIS groundwater and potassium supplemented SIS groundwater.
Experiment 1 was conducted as a preliminary investigation that compared growth and survival of yellowtail kingfish maintained in diluted seawater (20.02 ± 0.05 g/L, mean ± standard error), standard seawater (37.10 ± 0.08 g/L) and SIS groundwater (20.75 ± 0.07 g/L). After 21 days, the total biomass gain for fish maintained in diluted seawater was significantly greater than for fish maintained in either seawater or SIS groundwater. Apparent FCR and SGR were also significantly greater for fish maintained in diluted seawater. Although not significantly different, biomass gain, SGR and FCR were greater for fish in seawater than in SIS groundwater. Survival of fish was 94% in all treatments.
The metabolic study (Experiment 2) indicated no significant differences in estimates of routine metabolic rate, maximum metabolic rate and metabolic scope for yellowtail kingfish cultured in SIS groundwater, diluted seawater or ambient seawater.
In Experiment 3, growth rates of yellowtail kingfish were not significantly different between treatments although the diluted seawater treatment recorded the highest biomass gain of all treatments. These data suggest that yellowtail kingfish have the capacity for good growth in intermediate salinity waters of approximately 20 g/L.
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Results from Experiment 3 also showed no significant difference in growth of yellowtail kingfish cultured in SIS groundwater with added potassium (204.3 ± 7.0 mg/L) equivalent to a potassium to chloride ratio (K+:Cl-) of 0.017, compared to fish cultured in SIS groundwater with an ambient concentration of potassium (99.9 ± 2.94 mg/L) equivalent to a K+:Cl- ratio equal to 0.008. This result suggests that potassium concentration, and the potassium to chloride ratio, were not limiting the performance of yellowtail kingfish cultured in this source of SIS groundwater.
In summary, saline groundwater sourced from the Woolpunda, Waikerie and Qualco- Sunlands Salinity Interception Scheme appears to be suitable for the culture of yellowtail kingfish. Further research is required to determine the optimum conditions for culture of yellowtail kingfish using this SIS groundwater.
5.2. Background Yellowtail kingfish (Seriola lalandi) belong to the Carangidae family. Species from this family are typically large, free swimming predatory fish. They are found in temperate and sub-tropical coastal and oceanic waters adjoining countries including Australia, Japan, New Zealand, South Africa and the west coast of USA (Benetti et al., 2005). Yellowtail kingfish are reported to grow to over 150 cm in length and weigh in excess of 50 kg (Benetti et al., 2005).
In Japan Seriola lalandi is also known by its synonym, Seriola aureovittata, commonly called goldstriped amberjack or hiramasa and are regarded as a high quality sashimi fish ranking in the top bracket of species after tuna (Nakada, 2000; Benetti et al. 2005). Aquaculture production of yellowtail kingfish began in Japan in 1927. Currently Seriola lalandi contributes less than 5% of the total production of Seriola spp. with the bulk of the annual 140,000–160,000 tonnes of production comprised of amberjack, Seriola dumerili, and Japanese amberjack yellowtail, Seriola quinqueradiata, (Nakada, 2000).
The aquaculture of yellowtail kingfish commenced in Port Augusta, South Australia in 1998 following successful broodstock spawning and larval rearing conducted by Spencer Gulf Aquaculture Pty Ltd that resulted in production of approximately 6,000 fingerlings. Since then the yellowtail kingfish industry has rapidly expanded in South Australia with approximately 1,700 tonnes produced in 2006–07 and 2,900 tonnes in 2007–08. Ongoing expansion of the industry is expected.
Yellowtail kingfish display a number of characteristics that have contributed to their successful culture, including: • a consistent supply of high quality eggs at any time of the year from captive broodstock maintained in environmentally controlled holding systems • good survival during larval rearing allowing supply of fingerlings for on-growing operations • fast growth rate to market size of 3.0–3.6 kg within 15–18 months or 5.0–6.0 kg in 24 months
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• good adaptation to high stocking density conditions in seacages • ready acceptance of pellet feeds • ability to tolerate handling during husbandry operations associated with commercial sea cage aquaculture • product that is highly regarded in the market place.
There is currently considerable interest in expanding the yellowtail kingfish industry in South Australia. One potential area for expansion may be the culture of yellowtail kingfish in saline inland waters. Previous studies have investigated the potential culture of a range of marine and euryhaline species including barramundi (Lates calcarifer), rainbow trout (Oncorhynchus mykiss), mulloway (Argyrosomus japonicus), snapper (Pagrus auratus), and black tiger prawns (Penaeus monodon) in Australian saline groundwater (Fielder et al., 2001; Sarre and Partridge, 2005; Doroudi et al., 2006; Hutchinson and Flowers, 2007, unpublished). Outcomes of these studies have been variable and dependent on the chemical and physical conditions of the groundwater and also on the species selected. For example, when considering growth and survival of finfish in saline groundwater the level of potassium is often discussed, as this physiologically important ion is frequently deficient in these water sources. Mortality attributed to potassium deficiency in saline groundwater has been observed in studies on barramundi conducted in Western Australia (Partridge and Creeper, 2004) and on snapper in New South Wales (Fielder et al., 2001). Doroudi et al., (2006) demonstrated reduced growth and survival of mulloway cultured in suboptimal levels of potassium in saline groundwater.
The elevated water temperature of SIS groundwater is well suited to support the high growth rates that can be achieved by yellowtail kingfish. Additionally, groundwater is considered to be a source of water for aquaculture that is pathogen and parasite free (Anon., 1999). This provides an added advantage in maintaining biosecurity during the culture of yellowtail kingfish. A significant problem with sea cage aquaculture of this species has been ongoing infestation of cultured fish by parasitic flukes. Skin fluke (Benedenia seriolae) and gill fluke (Zeuxapta seriolae) infestations demand considerable operational resources and financial costs during sea cage culture of yellowtail kingfish. A water supply free of known pathogens provides an opportunity to culture this species in a biosecure environment.
The SIS groundwater resource available and the demonstrated performance of yellowtail kingfish in sea cage aquaculture combine to support investigation of this species for inland aquaculture. A preliminary experiment was conducted to determine if yellowtail kingfish could survive in SIS groundwater. A second experiment was then undertaken to investigate the physiological adaptation occurring by this oceanic species in response to SIS groundwater. This experiment compared oxygen requirements of yellowtail kingfish as an indicator of metabolic efficiency that may explain differences in performance of fish cultured in SIS groundwater, diluted seawater and seawater. A third investigation was conducted to investigate the effect of reduced potassium levels found in SIS groundwater on yellowtail kingfish. This experiment compared the performance of yellowtail kingfish cultured in seawater, SIS groundwater, seawater diluted to a similar salinity as SIS groundwater and SIS groundwater with potassium added to a similar level to that found in equivalent salinity seawater.
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5.3. Methods
5.3.1. Experiment 1 – Preliminary Assessment of the Survival and Growth of Yellowtail Kingfish in SIS Groundwater Yellowtail kingfish fingerlings were sourced from Clean Seas Aquaculture Hatchery, Arno Bay, South Australia and 54 fish (452.5 g ± 17.6 g, mean ± standard error) were randomly allocated to nine 800 L conical bottom fibreglass tanks (n = 6 fish per tank) in a controlled environment room. Each tank held approximately 650 L water and water quality was maintained by a recirculating water treatment system incorporating mechanical and biological filtration and foam fractionation (Figure 5.1). Mechanical filtration was achieved using Dacron® (Invista, Wichita, Kansas, USA) matting spread over a tray of bioballs. The filter matting intercepted suspended solids from water flowing from the tank and foam fractionator through two spray bars (40 mm PVC). Water then passed through plastic biological filtration media (30 L) spread in a plastic tray (Nally IHO36, 32 L; Viscount Plastics, Dudley Park, South Australia). Water discharged into a plastic sump (Nally IHO78, 68 L; Viscount Plastics, Dudley Park, South Australia) that acted as a reservoir and housed a 3,200 L/hr submersible pump (PondMaster® 3600; Danner Manufacturing, Islandia, New York, USA) that returned water back to the experimental tank. A foam fractionator was also installed to remove dissolved organic matter as part of the water treatment system supporting each tank.
Treatments were selected to differentiate the effect of reduced salinity and water type. Three water treatments were examined in this experiment: 1. standard seawater (37.6 ± 0.0 g/L) 2. diluted seawater (19.1 ± 0.2 g/L) 3. SIS groundwater (18.8 ± 0.1 g/L) sourced from the ‘outfall’ of Stockyard Plains Disposal Basin (SPDB).
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Foam fractionator
800 L tank
Dacron® matting
Biological filter
68 L sump with submersible pump
Figure 5.1. Layout of 800 L tank and water treatment components used to conduct Experiment 1 within temperature controlled room at the South Australian Aquatic Sciences Centre (SAASC).
At the time of stocking fish, all tanks were filled with natural seawater. Over a period of seven days fish in relevant tanks were acclimatised to the composition of water required for treatments 2 and 3. At this time, all fish were weighed and measured (total length) and the experiment commenced on 7 May 2007. The experiment was conducted for 21 days finishing on 28 May 2007 when all fish from all tanks were weighed to determine the final mean weight and length and returned to their tank for use in Experiment 2.
Fish were fed to satiation twice daily using a closed formula commercial diet Nova ME (Skretting, Cambridge, Tasmania). A photoperiod of 10 hours of light and 14 hours of darkness was maintained throughout the experiment. Approximately 30% of water was exchanged from each system each week (two exchanges of 70–80 L water each Monday and Friday). Water quality parameters were measured each weekday. Dissolved oxygen (% saturation) and water temperature (oC) were measured using an OxyGuardTM Handygamma dissolved oxygen meter (OxyGuard International A/S, Birkerød, Denmark). The pH and salinity (g/L) was measured daily using a WTW 340i SET pH and conductivity meter + (Wissenschaftlich-Technische Werkstätten, Weilheim, Germany). Ammonium (NH4 , mg/L) was recorded weekly using an RQflex 10 meter (Merck KgaA, Darmstadt, Germany).
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5.3.2. Experiment 2 – Metabolic Responses of Yellowtail Kingfish Cultured in SIS Groundwater Some of the information for Experiment 2 in this report has been taken from an as yet unpublished Masters thesis written by Tim Flowers, done as part of this CNRM project. A more detailed explanation of this experiment will be presented in his thesis. The metabolic rate of yellowtail kingfish in different water types was investigated over three days following the 21 day growth experiment (Experiment 1). Fish used in Experiment 1 were transferred into three 2000 L holding tanks. Each tank contained one of the treatment waters. Water temperature in each tank was maintained between 19–21oC. Water was continuously pumped (PondMaster® 3600; Danner Manufacturing, Islandia, New York, USA) from each 2000 L tank to five respirometry boxes with water flowing through these boxes and returning to the holding tank.
Respirometry boxes were used to measure the routine metabolic rate (RMR), and maximum metabolic rate (MMR) of yellowtail kingfish from each treatment. The average box volume and flow rates were 3.2 L ± 0.1 (n = 10) and 0.04 ± 0.001 L/s, respectively. The fish were acclimatised for 16 hours in the respirometry boxes prior to any oxygen measurements being recorded. Previous experiments for mulloway and snapper indicated that this was adequate time for acclimatisation (Flowers, unpublished). The RMR and MMR were determined for ten fish from each water treatment. RMR was determined for an individual fish by calculating the oxygen consumption rate in a respirometer box when the water flow was ceased. MMR was achieved by exposing fish to acute stress by transferring individual fish into a tub containing 20 L water and chasing for five minutes using a PVC pole. After approximately five minutes, fish were unresponsive to touch and were returned to the allocated respirometer chamber and another respiration rate determination made. Metabolic scope (MS) of each fish was calculated by subtracting the MMR from the RMR. Both metabolic rate calculations were determined with consideration of background oxygen consumption determined from measurements taken form a control respirometer chamber with no fish added. The methods and equipment used to measure oxygen consumption are described by Powell et al. (2005).
5.3.3. Experiment 3 –Assessment of the Growth and survival of Yellowtail Kingfish in Standard Seawater, Diluted Seawater, SIS Groundwater and Potassium Supplemented SIS Groundwater. Juvenile yellowtail kingfish (n = 20 fish per tank, mean initial weight 88.3 ± 1.2 g) were grown for 40 days in 12 tanks set up as per the system used in Experiment 1, with the exception that foam fractionators were not included.
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Figure 5.2. Experimental tanks (800 L) and recirculated water treatment systems used in Experiment 3.
The experiment incorporated four different water source treatments, each replicated in three tanks. The four treatments were: 1. seawater 2. diluted seawater 3. SIS groundwater 4. SIS groundwater with added potassium.
Monitoring of the Woolpunda, Waikerie and Qualco-Sunlands SIS conducted by SARDI between September 2005 and August 2006 (Hutchinson and Flowers, 2007) determined that the level of potassium (K+) in saline groundwater entering SPDB was 87.37 ± 3.73 mg/L (mean ± SD). This level was used to determine the amount of potassium added to SIS groundwater to provide a concentration equivalent to that found in 20 g/L seawater (i.e. K+ = 217 mg/L). A reservoir of this water type was made by addition of 570 g of commercial grade potassium chloride (KCl, Ace Chemical Co., Camden Park, South Australia) to 5,000 L of SPDB groundwater in an aerated reservoir tank (Mastertanks™, Richmond, South Australia). The diluted seawater treatment water (20 g/L diluted from 37 g/L seawater) was prepared in another 5,000 L reservoir tank using a mix of ambient sand filtered seawater and mains freshwater that was dechlorinated using continuous aeration during storage.
Before starting the experiment, fish in the reduced salinity treatments were acclimatised over a period of two weeks. A 5,000 L reservoir tank was filled with seawater diluted to 20 g/L salinity, and used to slowly bring salinity down in each tank by adding approximately 60 L/day. Once all reduced salinity treatment tanks had reached the appropriate salinity
83 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
diluted seawater was completely exchanged for SIS groundwater (with or without additional potassium) in the relevant treatment tanks and control tanks and the experiment was commenced.
Throughout the experiment, fish were fed closed formulae commercial extruded fish feeds. Marine Start (Ridley Agri-Products, Pakenham, Victoria) 3 mm sinking pellet (approximately 49% protein, 23% lipid) was fed during the acclimation period and until day 26. For the final 14 days of the experiment, feed size was increased to 4 mm Nova ME (Skretting, Cambridge, Tasmania) to accommodate for increase in fish size. Approximate composition of Nova ME was 45% protein and 20% lipid. Fish were fed three times a day (approximately 10.00 am, 12.30pm and 3.00pm) to optimise ingestion by all fish. The total amount of feed provided to each tank each day was recorded.
Approximately 25% of the system water was exchanged per week as two partial exchanges conducted each Monday and Friday. The 70 L sump was first drained then new water from reservoirs was pumped into the sump and then replaced into the main tank using the submersible pump operating each system. Dacron™ filter matting was cleaned and replaced each day to maintain water quality. Temperature was maintained between 20–22oC in the room using airconditioning. A photoperiod of 10 h of light and 14 h of darkness was maintained throughout the experiment.
Water quality parameters were measured each weekday. Dissolved oxygen (% saturation) and water temperature (oC) were measured using an OxyGuardTM Handygamma dissolved oxygen meter (OxyGuard International A/S, Birkerød, Denmark). Salinity (g/L) was determined using a standard refractometer. pH was measured after each water exchange to check that this + parameter was within an acceptable range. Ammonia (NH4 /NH3 mg/L) was recorded using a colorimetric test kit (Aquarium Pharmaceuticals Inc., Chalfont, Pennsylvania, USA). Potassium and chloride concentration of each water treatment was determined from samples submitted to the Australian Water Quality Centre (Bolivar, South Australia). Water samples were taken from each treatment type on three occasions (days 0, 21 and 35) during the experiment.
All fish in each tank were weighed and measured every two weeks. Fish were anaesthetised using 2 mL of Aqui-S® (Aqui-S New Zealand Ltd, Lower Hutt, New Zealand) dissolved in 40 L of the appropriate water type (actual concentration 50 mg/L) with oxygenation maintained. Weight was determined (g) by transferring each anaesthetised fish into a 3 L water bath on an electronic balance (PG8001-S, Mettler-Toledo Ltd, Greifensee, Switzerland). Fork length (mm) was determined using a measuring board. After measurement, fish were placed in a highly aerated recovery tank containing water of appropriate salinity for several minutes until recovered and then they were transferred back into the relevant tank. Data collected were used to determine biomass gain (i.e. weight gain of all fish in each replicate tank for each treatment), specific growth rate ([ln final weight – ln initial weight]/days*100, SGR) and apparent food conversion ratio (biomass gain/apparent feed consumed, FCR) for fish in each treatment tank.
The experiment started with 20 fish per tank. After completion of the first weigh and measure point, four fish were removed from each replicate to reduce tank biomass in order to maintain
84 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
manageable dissolved oxygen and ammonia levels. Fish removed were those that were in the largest and smallest size cohorts with the aim being to reduce size variability between fish in each tank. Mortalities were not replaced and a record of date of occurrence was made and daily feed amounts adjusted to allow for reduction in tank biomass.
5.4. Statistical Analysis Data were tested for normality and homogeneity of variances using the Kolmogorov-Smirnov Test and the Levene’s test of equality of error variances, respectively. Initial and final data for experiments 1 and 2 were analysed using one-way ANOVA. Experiment 3 data for fish growth and feed efficiency performance was analysed using two-way ANOVA for repeated measures. The first factor was water type and the second factor was grow-out time (0, 14, 28 and 40 days). Survival rate data for Experiment 3 was analysed using one-way ANOVA. For Experiment 3, data for one of the replicate tanks for the seawater treatment were excluded from the analyses due to a failure of the dedicated biological filtration system. The filtration system failure resulted in excessively high ammonia levels in this tank (1.5 mg/L), and while fish survived, fish appetite decreased as did growth performance.
A significance level of P<0.05 was used for all statistical tests, and tank mean values (n = 3 except for seawater in Experiment 3 where n = 2) were considered units of observation for statistical analysis. Student Newman-Kuels test was used as a post-hoc test to identify significant differences among multiple treatment means. All statistical analyses were done using SPSS, Version 16.0.1 for Windows (SPSS Inc., Chicago, IL, USA). All values are presented as means ± standard error (SE) unless otherwise stated.
5.5. Results
5.5.1. Experiment 1 One fish from each treatment died resulting in 94.4% survival for all treatments. Apart from salinity, similar levels for all water parameters were recorded for all treatments (Table 5.1) with low variation observed between replicate tanks for each treatment.
The weight of fish was not significantly different (P>0.05) between treatments at the start or the finish of the experiment (Table 5.2). Biomass gain, SGR and apparent FCR recorded for fish in diluted seawater (20 g/L) were significantly better (P<0.05) than the SIS groundwater and seawater treatments.
Table 5.1. Mean (± SE) dissolved oxygen (% saturation), pH, salinity (g/L), water temperature (oC) and ammonia (mg/L) for different water type treatments over 21 days.
Parameter Standard seawater Diluted seawater SIS groundwater DO (% saturation) 84.7 ± 2.0 81.1 ± 2.0 84.2 ± 2.0 pH 7.4 ± 0.0 7.8 ± 0.0 8.0 ± 0.0 Salinity (g/L) 37.6 ± 0.0 19.1 ± 0.2 18.8 ± 0.1 Water temperature (oC) 22.1 ± 0.2 21.9 ± 0.2 21.8 ± 0.2 Ammonia (mg/L) < 0.1 < 0.1 < 0.1
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Table 5.2. Mean (± SE) initial and final weights, biomass gain, specific growth rate (% body weight per day, SGR) and apparent feed conversion ratio (FCR) for yellowtail kingfish cultured in different water type treatments over 21 days (averages that share a common superscript are not significantly different, P>0.05).
Parameter Standard seawater Diluted seawater SIS groundwater Initial weight (g/fish) 474.9 ± 17.5a 466.6 ± 19.8a 416.0 ± 24.5a Final weight (g/fish) 529.1 ± 23.7a 609.1 ± 28.2a 458.8 ± 24.5a Biomass gain (g/tank) 340.7 ± 46.8b 840.7 ± 111.6a 237.3 ± 58.4b SGR (%/day) 0.5 ± 0.0b 1.2 ± 0.0a 0.4 ± 0.1b FCR 3.6 ± 0.4b 1.7 ± 0.1a 5.3 ± 1.1b
5.5.2. Experiment 2 On day one of the experimental period, two fish in the diluted seawater treatment did not survive the overnight acclimation period. During the RMR oxygen determination, some fish became restless within the respirometry boxes and this prevented the measurement of their RMR. This resulted in a 56% reduction in the experimental sample size for the diluted seawater treatment (n = 4) and a 44% reduction in the experimental sample size for the seawater treatment (n = 5). No significant differences for RMR were detected between treatments (P > 0.05; Figure 5.3). No significant differences were recorded for MMR (i.e. post-stressed fish) between water types (Figure 5.3). The greatest average MMR for fish occurred in the seawater treatment (16.1 ± 1.5 µmol/g/hr). The average MMR for fish in diluted seawater (14.1 ± 0.8 µmol/g/hr) and SIS groundwater (14.6 ± 0.7 µmol/g/hr) treatments were similar. No significant difference was detected between treatments for MS (Figure 5.3). The greatest average MS occurred for fish in the seawater (5.9 ± 1.4 µmol/g/hr). The average MS for fish in diluted seawater (4.0 ± 0.4 µmol/g/hr) and SIS groundwater (4.8 ± 1.1 µmol/g/hr) were similar.
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Routine Maximum Scope 20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0 Metabolic Rate (µmol/g/hr) Metabolic 4.0
2.0
0.0 Diluted seawater (n = 4) SIS groundwater (n = 9) Seawater (n = 5)
Figure 5.3. Mean (± SE), routine metabolic rate, maximum metabolic rate and metabolic scope µmol/g/hr for yellowtail kingfish grown in diluted seawater (DSW), SIS groundwater (GW) and standard seawater (SW) for 21 days. There were no significant differences between means for each response variable (P > 0.05, one-factor ANOVA).
5.5.3. Experiment 3 During the experiment water temperature ranged between 20.0 oC and 21.5 oC, pH ranged + between 7.4 and 8.0 and the average total ammonia (NH4 /NH3) ranged between 0.19 ± 0.03 mg/L and 0.23 ± 0.03 mg/L (Table 5.3). Within this water temperature and pH range, the proportion of unionized ammonia (NH3) is between 0.002 and 0.01 mg/L; a range considered to be safe for fish (Ferguson, 1988; Moe, 1989).
The survival rate of fish ranged from 77.5% for the diluted seawater treatment to 90% for groundwater treatment with potassium added, and there was no significant effect of treatment on survival (P>0.05; one-way ANOVA).
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+ Table 5.3. Mean (± SE) salinity (g/L), dissolved oxygen (% saturation), ammonia (NH4 /NH3, mg/L), potassium (mg/L), chloride (mg/L) and potassium to chloride (K+:Cl-) ratio for different saline water types over 40 days.
Standard Diluted seawater SIS groundwater SIS groundwater Parameter seawater (SW) (DSW) (GW) + K+ (GWK) Salinity (g/L) 37.10 ± 0.08 20.02 ± 0.05 20.75 ± 0.07 20.75 ± 0.07 Dissolved Oxygen 69.67 ± 1.76 71.88 ± 1.68 73.42 ± 1.51 71.15 ± 1.46 (% Saturation) + Ammonia NH4 /NH3 0.23 ± 0.03 0.20 ± 0.03 0.19 ± 0.03 0.20 ± 0.03 (mg/L) Potassium K+ (mg/L) 432 ± 0.58 235 ±17.39 99.9 ± 2.94 204.3 ± 6.98 Chloride Cl- (mg/L) 21,233 ± 66.7 11,900 ± 850.5 12,700 ± 208.21 12,267 ± 133.3 K+:Cl- Ratio 0.020 0.020 0.008 0.017
The results for the two-factor ANOVA for repeated measures indicated there was no significant effect of water type on fork length (Figure 5.4), condition index (Figure 5.5), SGR (Figure 5.6), weight gain, feed consumed or apparent FCR of yellowtail kingfish (Table 5.4). However, there was a significant effect of grow-out time on total weight, fork length, weight gained, SGR, feed consumed and apparent FCR. Although the total weight of fish increased at each grow-out time, the SGR was observed to progressively decrease at each grow-out time. Fish consumed significantly more food at each grow-out time. However, fish converted feed (FCR) less efficiently during each successive grow-out period. There was a significant interaction between water type and grow-out time for fork length (P = 0.044), condition index (P = 0.036) and SGR (P = 0.031, Table 5.4). There was no significant interaction between saline water type and grow-out time for total weight, weight gain, amount of feed consumed or apparent FCR (Table 5.4).
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Table 5.4. Two-factor ANOVA for total weight (g), fork length (mm), condition index (weight (g) x 105/fork length (mm)3), weight gain (g), SGR (% biomass per day), feed consumed (g) and apparent FCR of yellowtail kingfish grown in different saline water types for 40 days1, 2
Saline water type (A) P Grow-out time (day) (B) P Interaction
Standard Diluted SIS SIS (A) 0 14 28 40 (B) P (A x B) seawater seawater groundwater groundwater Item (37 g/L) (20 g/L) (21 g/L) + K (21 g/L)
Weight (g) 164.3 ± 6.2 179.1 ± 5.0 160.8 ± 5.0 172.0 ± 5.0 0.139 88.3 ± 1.2d 142.1 ± 2.7c 205.5 ± 3.7b 240.1 ± 4.5a <0.001 0.068
Fork length 223.8 ± 2.8 228.3 ± 2.3 222.8 ± 2.3 227.9 ± 2.3 0.301 185.1 ± 0.9d 215.6 ± 1.5c 244.8 ± 1.8b 257.3 ± 1.5a <0.001 0.044 (mm)
Condition 1.40 ± 0.01 1.43 ± 0.01 1.39 ± 0.01 1.39 ± 0.01 0.127 1.39 ± 0.01 1.41 ± 0.01 1.40 ± 0.01 1.41 ± 0.01 0.596 0.036 index
Weight gain 100.3 ± 6.1 119.1 ± 5.0 98.1 ± 5.0 112.9 ± 5.0 0.067 NA 53.7 ± 1.8c 117.3 ± 3.0b 151.9 ± 4.3a <0.001 0.077 (g)
SGR (% 2.73 ± 0.1 3.14 ± 0.1 2.85 ± 0.1 3.12 ± 0.1 0.064 NA 3.38 ± 0.1a 3.00 ± 0.0b 2.49 ± 0.1c <0.001 0.031 biomass/day)
Feed 1948 ± 62.5 2029 ± 51.1 1916 ± 51.1 2002 ± 51.1 0.456 NA 941 ± 9.3c 2096 ± 26.5b 2885 ± <0.001 0.418 consumed 053.6a (g)
Apparent 1.11 ± 0.07 0.99 ± 0.06 1.18 ± 0.06 1.02 ± 0.06 0.162 NA 0.89 ± 0.02a 1.02 ± 0.02a 1.31± 0.07b <0.001 0.144 FCR
1 Means ± SE; for grow-out time; means that share the same superscript are not significantly different, P > 0.05; two-factor ANOVA; SNK. 2 NA = not applicable
89 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
DSW GWK GW SW 300
280
260
240
220
Fork length (mm) 200
180
160 0142840 Day
Figure 5.4. Mean (± SE) fork length (mm) of yellowtail kingfish grown in different types of saline water for 40 days. SW = standard seawater; DSW = diluted seawater; GW = groundwater; GWK = groundwater with potassium added.
90 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
DSW GWK GW SW 1.6
1.55
1.5
1.45
1.4
1.35 Condition Index
1.3
1.25
1.2 0142840 Day
Figure 5.5. Mean (± SE) condition index (weight (g) x 105/fork length (mm)3) of yellowtail kingfish grown in different types of saline water for 40 days. SW = standard seawater; DSW = diluted seawater; GW = groundwater; GWK = groundwater with potassium added.
DSW GWK GW SW 4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5 Specific Growth Rate (% body weight/day) body (% Rate Growth Specific 0.0 14 28 40 Day
Figure 5.6. Mean (± SE) specific growth rate (% body weight per day) of yellowtail kingfish grown in different types of saline water for 40 days. SW = standard seawater; DSW = diluted seawater; GW = groundwater; GWK = groundwater with potassium added.
91 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
5.6. Discussion Experiment 1 was primarily intended to reveal if yellowtail kingfish could survive in water of intermediate salinity. This was confirmed, as after 21 days only one mortality was reported from each treatment, representing 94.4% survival.
Experiment 2 addressed whether yellowtail kingfish would grow in reduced natural salinity seawater. Results showed that the fish did grow, with the highest weight gain achieved in the diluted seawater treatment. FCR and SGR were also significantly better for fish maintained in the diluted seawater.
The main focus of Experiment 3 was to assess potassium supplementation of the saline groundwater. Growth rates of yellowtail kingfish in standard seawater, diluted seawater, SIS groundwater and potassium supplemented SIS groundwater were not significantly different over the 40 day experiment, however the diluted seawater treatment recorded the highest biomass gain of all treatments. Diluted seawater also produced the better SGR and FCR, although on this occasion the results were not statistically different. Together experiments 2 and 3 strongly suggest that yellowtail kingfish have the capacity for good growth in intermediate salinity waters of approximately 20 g/L.
The ability of yellowtail kingfish to survive and grow well in reduced salinity is intriguing as it is a pelagic species and is not reported to inhabit reduced salinity environments. However, similar findings have been reported for other fully marine species. Significantly greater final weight and improved SGR and food conversion efficiency has been reported for Atlantic halibut (Hippoglossus hippoglossus) at salinities of 15 g/L and 25 g/L compared to fish cultured at 32 g/L (Imsland et al. 2008). For turbot (Scophthalmus maximus) the optimal water temperature and salinity combination for growth was reported to be 21.8 ± 0.9 oC and 18.5 ± 0.08 g/L while the best combination for food conversion efficiency was 18.3 ± 0.6 oC and 19.0 ± 1.0 g/L (Imsland et al. 2001). Woo and Kelly (1995) found consistently higher growth rates and protein conversion efficiencies (weight gained/protein consumed) for sea bream (Sparus sarba) cultured at 15 g/L when compared with fish cultured at 35 g/L and 7 g/L. Laiz-Carrión et al. (2005) reported similar results for another marine sparid species, gilthead sea bream (Sparus aurata). This species was reported to exhibit better growth, weight gain and SGR at an intermediate salinity of 12 g/L compared to 38 g/L or 6 g/L.
When considering the difficulties often experienced in growing finfish using saline groundwater, the concentration of potassium present is often discussed, as this physiologically important ion is frequently deficient in saline groundwater sources. Potassium deficiency has been reported to cause mortality in a number of species of finfish that have been investigated for aquaculture in saline groundwater. Mortality attributed to hypokalaemic muscle myopathy has been reported in barramundi (Lates calcarifer) cultured in 45 g/L groundwater that was deficient in potassium (Partridge and Creeper, 2004). Fielder et al. (2001) reported mortality in snapper (Pagrus auratus) cultured in a saline groundwater from the Wakool-Tullakool subsurface drainage scheme in south western NSW. Salinity of this water was 19 g/L and had a potassium concentration of only 9.2 mg/L. Fielder et al. (2001) minimised mortality by increasing the potassium concentration from 9.2 mg/L to 83 mg/L, although growth improved up to a potassium concentration of 124 mg/L. Using groundwater from the same source Doroudi et al. (2006) reported maximum survival of
92 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
mulloway at a potassium concentration of 78.7 mg/L which is equivalent to 38% of that present in equivalent salinity seawater. In a further experiment, Doroudi et al. (2006) also reported maximum survival and growth of mulloway above 82.8 mg K+/L or 40% of that present in equivalent salinity seawater. These results agree with results obtained by SARDI in experiments conducted on mulloway and snapper cultured in SIS groundwater as part of this project (Hutchinson and Flowers, 2007, unpublished).
Due to these results, Experiment 3 included a treatment with potassium added to SIS groundwater to a concentration of 204.3 ± 6.98 mg/L, which equated to 87% of the level measured in the diluted seawater (235 ± 17.39 mg/L) treatment. The intention was to supplement potassium to a level equivalent to 100% of that found in diluted seawater. However the level used is believed to be sufficiently elevated. There was no significant difference in growth of yellowtail kingfish in the SIS groundwater (99.9 ± 2.94 mg K+/L) and SIS groundwater with additional potassium (204.3 ± 6.98 mg K+/L) and diluted seawater treatment (235 ± 17.39 mg K+/L). This suggests that potassium was not a limiting factor for yellowtail kingfish in SIS groundwater, at least over the duration tested.
Partridge and Creeper (2004) suggested that potassium should be considered in relation to the amount of chloride present in the water source. They hypothesised that the requirement for potassium by barramundi was a non-linear function of salinity. Fielder et al. (2001) reported total mortality of snapper when the ratio K+:Cl- = 0.001. Survival increased when the ratio was increased to K+:Cl- = 0.008 and further improved when the ratio was above K+:Cl- = 0.013. Results from Experiment 3 showed no significant difference in growth for yellowtail kingfish cultured in SIS groundwater (K+:Cl- = 0.008) compared with fish cultured in SIS groundwater supplemented with potassium (K+:Cl- = 0.017). There was no evidence that the K+:Cl- ratio inhibited survival or growth in these experiments.
For marine species it has been suggested that there is an energy saving advantage when cultured at intermediate salinities that approach their iso-osmotic point (Gaumet et al., 1995, Imsland et al., 2008). It has been hypothesized that this energy saving allows more energy to be partitioned for growth (Gaumet et al., 1995, Imsland et al., 2008). Results from Experiment 2 do not support this hypothesis as no significant differences for RMR, MRM or MS were recorded for yellowtail kingfish maintained in SIS groundwater, diluted seawater and seawater. The reason for this is not known, but it was very clear that yellowtail kingfish were more unsettled in the respirometry boxes compared to snapper and mulloway (Flowers, unpublished) and this may have affected the accuracy of the metabolic data obtained.
Data suggests that during the final 12 days of Experiment 3, the experimental system reached the maximal load that could be sustained. Because yellowtail kingfish grew at a fast rate the biomass in each experimental system increased to a point at which the amount of feed added each day was assessed to be too much to be treated by the simple mechanical and biological filtration systems supporting each experimental tank. This was reflected by the decline in SGR for all treatments during the final 12 days. During this period ammonia concentrations were acceptable, however, suspended solids observed in each tank increased, water clarity decreased and the appetite of fish became more unpredictable. As a result the experiment was terminated 2 days earlier than planned. It is suggested that future yellowtail kingfish experiments using the experimental system commence with smaller fish (i.e. 10–20 g) that
93 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
can be allowed to grow for a longer period before the capacity of the experimental system is reached.
5.7. Conclusions and Recommendations Overall these data suggest that under the experimental conditions used, yellowtail kingfish grow equally well in SIS groundwater, diluted seawater and potassium supplemented SIS groundwater, as they do in seawater. The metabolic rate of yellowtail kingfish cultured in SIS groundwater over 21 days was not demonstrated to be abnormally affected in the experiment undertaken. It appears that the level of potassium and the potassium to chloride ratio found in the SIS groundwater did not significantly limit growth of yellowtail kingfish in these studies. In both growth experiments conducted there was a trend for yellowtail kingfish to perform better in diluted seawater.
Saline groundwater sourced from the Woolpunda, Waikerie and Qualco-Sunlands SIS appears to be suitable for the culture of yellowtail kingfish. Further research will be required to determine the optimum conditions for culture of yellowtail kingfish using this SIS groundwater.
94 Chapter 5 – Evaluation of yellowtail kingfish in saline groundwater
5.8. References Anon. 1999. Aquaculture potential of Australian native finfish. Primary Industries and Resources South Australia Fact Sheet No: 14/99. Benetti, D., Nakada, M., Shotton, S., Portenaar, C., Tracey, P., Menomoto, Y. and Hutchinson, W. 2005. Aquaculture of three species of yellowtail jacks. American Fisheries Society Symposium 46: 491–515. Doroudi, M.S., Fielder, D.S., Allan, G.L. and Webster, G.K. 2006. Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Aquaculture Research 37: 1034–1039. Fielder, D.S., Bardsley, W.J. and Allan, G.L. 2001. Survival and growth of Australian snapper, Pagrus auratus, in saline groundwater from inland New South Wales, Australia. Aquaculture 201: 73–90. Ferguson, H. 1988. Water quality diseases. In: Fish Diseases. Proceedings, refresher course for veterinarians, 23–27 May. Post Graduate Committee in Veterinary Science, University of Sydney, pp. 49–56. Gaumet, F., Boueuf, G., Severe, A., Le-Roux, A. and Mayer-Gostan, N. 1995. Effects of salinity on the ionic balance and growth of juvenile turbot. Journal of Fish Biology. 47 (5): 865–876. Hutchinson, W.G. and Flowers, T.J. 2007. Assessment of the composition of saline groundwater from major sections of the Woolpunda–Waikerie–Qualco-Sunlands salinity interception scheme and evaluation of mulloway (Argyrosomus japonicus) and snapper (Pagrus auratus) growth in saline groundwater from Stockyard Plains Disposal Basin. Draft Final Milestone Report. Waikerie Inland Aquaculture Centre (unpublished). Imsland, A.C., Gústavsson, A., Gunnarsson, S., Foss, A., Árnason, J., Arnarson, I., Jónsson, A.F., Smáradóttir, H. and Thorarensen, H. 2008. Effects of reduced salinities on growth, feed conversion efficiency and blood physiology of juvenile Atlantic halibut (Hippoglossus hippoglossus L). Aquaculture 274: 254–259. Imsland, A.K., Foss, A., Gunnarsson, S., Berntssen, M.H.G., Fitzgerald, R., Bonga, S.W., Ham, E.V., Naevdal, G. and Stefansson, S.O. 2001. The interaction of temperature and salinity on growth and food conversion in juvenile turbot (Scopthalmus maximus). Aquaculture 198: 353–367. Laiz-Carrión, R., Sangiao-Alvarellos, S., Guzmán, J.M., Martin del Rio, M.P., Soengas, J.L. and Mancera, J.M. 2005. Growth performance of gilthead sea bream Sparus aurata in different osmotic conditions: Implications for osmoregulation and energy metabolism. Aquaculture 250: 849–861. Moe, M.A. Jr. 1989. The marine aquarium reference—systems and invertebrates. Green Turtle Publications, pp. 510. Nakada, M. 2000. Yellowtail and related species culture. In Stickney, R. (Editor) Encyclopaedia of Aquaculture, pp. 1007–1036.
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Partridge, G.J. and Creeper, J. 2004. Skeletal myopathy in juvenile barramundi, Lates calcarifer (Bloch), cultured in potassium-deficient saline groundwater. Journal of Fish Diseases 27: 523–530. Powell, M.D., Speare, D.J, Daley, J. and Lovy J. 2005. Differences in metabolic response to Loma salmonae infection in juvenile rainbow trout Oncorhynchus mykiss and brook trout Salvelinus fontinalis. Diseases of Aquatic Organisms 67: 233–237.
SarreH G.A and Partridge G.J. 2005. Inland saline aquaculture: A new marine industry for the
WA wheatbelt.H Challenger TAFE (Aquaculture Development Unit) Springfield Waters Aquaculture, Northam. Woo, N.Y.S. and Kelly, S.P. 1995. Effects of salinity and nutritional status on growth and metabolism of Sparus sarba in a closed seawater system. Aquaculture 135: 229–238.
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Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
6.1. Summary From 10 May 2006 until 4 April 2008, two batches of mulloway were cultured in three 70,000 L tanks within a semi-intensive aquaculture system at WISAC using saline groundwater supplied from the Woolpunda SIS pipeline that runs adjacent to this facility.
Survival of advanced mulloway (340 g) and two groups of fingerlings (55.5 g) cultured to market size in three production tanks using SIS groundwater was 46.5%, 92.4% and 94.8% respectively. The low survival in one tank was due to a mortality event caused by a technical malfunction in the oxygen supply system and a delay in receiving the alarm.
A total of 13,112 fish were stocked and grown to market size resulting in the harvest of 9,772 kg that equated to a biomass gain of 7,531 kg. These fish consumed a total of 15,280 kg of feed, giving an apparent FCR of 2.03 for combined fish tanks.
Feed conversion of mulloway cultured in SIS groundwater was comparable to results achieved in other studies with this species cultured in saline groundwater and in sea water, but was higher than that of other commercial aquaculture species. Feeding management is recommended as area for future R&D to improve feed utilisation to reduce FCR and cost of mulloway production.
Total SGR of an advanced batch of mulloway grown to market size at WISAC was 0.30%/day compared to 0.55%/day and 0.51%/day for the batch of fingerlings grown from 2.0 g through to market size (>750 g).
SGR was high while fish were less than approximately 180 g, but declined as fish grew to market size (i.e. >750g).
Over the grow-out period, the growth trajectory of mulloway cultured in the semi-intensive aquaculture system was almost linear, rather than exponential as would be expected for the early growth period of cultured fish.
The maximum stocking density achieved when fish reached market size and during progressive harvesting was within the 30 kg/kL target for the semi-intensive system.
Data collected from these trials and results of previous research indicate that it is unlikely that the level of potassium in the SIS groundwater could adversely affect the growth performance of mulloway cultured at WISAC.
There is insufficient information to recommend what a desired condition index (CI) should be for a given size of mulloway. Feedback from commercial finfish processors that sold the fish cultured at WISAC, suggests that a CI value greater than 1.1 should be targeted for fish at a harvest size greater than 750 g.
97 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
The fish cultured in SIS groundwater in the semi-intensive aquaculture system at WISAC grew faster than both wild mulloway and hatchery produced mulloway cultured in commercial seacages. Growth performance data suggests that it will take approximately 600 days (19.7 months, 1.64 years) for mulloway to grow from 2.0 g to an initial marketable size of 750 g, although the best batch of fish achieved this size in 566 days (18.6 months, 1.55 years).
Discussions with processors and marketing studies conducted indicate that the culture of larger fish (>1.5 kg) should be targeted in future as there are positive market prospects for fish of this size.
In this study, the relationship y = 0.0088x1.7913 (R2 = 0.992) was found to estimate the growth of the best performing batch of mulloway cultured at WISAC. This relationship predicts that it would take approximately 835 days (27.5 months, 2.3 years) for the best performing mulloway to achieve 1.5 kg and a further 65 days to achieve 2.0 kg.
The culture period of mulloway in SIS groundwater in the semi-intensive aquaculture system at WISAC was comparable to the culture period of temperate water marine finfish that support significant commercial aquaculture industries in other countries.
Testing of fish produced in SIS groundwater showed that the level of all compounds tested was either below the limit of detection or below the maximum residue limit.
Prices received for whole gut in mulloway ranged from $6.60/kg to $7.00/kg. Retail price reported for these fish ranged from $12.00/kg to $14.00/kg for whole fish and $22.00/kg to $25.00/kg for fillets. Information provided by fish processors suggest that product recovery rates achieved for mulloway cultured in SIS groundwater were between 85% and 88% for whole gilled and gutted fish; 52% and 54% for scaled “wing-on” fillets; between 48% and 50 % for skin on fillets (wing off); and between 45% and 48% for skin off fillets.
6.2. Background Pilot commercial scale grow-out of mulloway (Argyrosomus japonicus) has been undertaken at WISAC in order to evaluate the potential to use SIS groundwater for commercial aquaculture. The semi-intensive aquaculture system at WISAC used a semi-intensive approach that targeted a final stocking density in the order of 30 kg fish per 1,000/L in each production tank.
In addition, between February and May 2006 mulloway larvae were cultured through to fingerlings at the SARDI R&D Hatchery at SAASC.
This report presents information collected on the two batches of mulloway cultured at WISAC from May 2006 until April 2008, representing performance of these fish from stocking until harvest at market size. Growth and feed consumption data collected from these mulloway can be used to evaluate performance of this species cultured in a similar but larger scale semi-intensive commercial system using SIS groundwater. These data can also be used
98 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
to determine the likely time to reach a marketable size. Major operating costs for mulloway cultured in the semi-intensive system are also provided covering the full production cycle from stocking to completion of harvesting of the three batches cultured at WISAC.
6.3. Methods
6.3.1. Batch 1 – Advanced Mulloway In February 2005, a batch of mulloway fingerlings was purchased from a commercial marine finfish hatchery in South Australia (Clean Seas Tuna Ltd, Arno Bay) and transported to SAASC where they were on-grown in anticipation of the completion of WISAC. The WISAC facility was completed in April 2006. On 8 May 2006, this advanced batch of 3,200 mulloway (average weight 340 g, total biomass weight 1,020 kg) was transferred to WISAC and stocked into a 70,000 L production tank (G1, Figure 6.1). Fish were grown in production tank G1 at WISAC for 449 days until harvesting was completed on 30 July 2007.
Figure 6.1. First stocking of 3,200 advanced mulloway into production tank G1 at WISAC on 8 May 2006.
99 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
To maximise feed intake, all fish were handfed to satiation in the morning (typically 8.00am) and as late in each day as possible (typically 4.00pm). The amount of feed consumed by fish in each tank was recorded daily. The feed used was a closed formula extruded commercial diet (Nova ME, Skretting, Cambridge, Tasmania) consisting of approximately 55% crude protein and 22% crude lipid. The pellet size was determined by assessment of fish size and consumption. At approximately monthly intervals, 100 mulloway from each production tank were randomly sampled and weighed to monitor growth.
From 10 September 2006 small quantities of fish harvested from tank G1 were supplied to a local butcher. In December 2006, visual observations made at the time of sale revealed a decline in fish condition. From this time all fish sales were halted and CI—Fulton’s Condition index (CI) = weight (g/fish)/length (mm)3 x 100,000—(Bagenal & Tesch, 1978) was monitored. To assist, a diet was formulated (Appendix 6.1, Jeff Buchanan, SARDI) to optimise quality of ingredients in order to improve finfish condition. Formulation of this pellet was based upon assessment of previous research conducted on the nutritional requirements of mulloway and was produced by SARDI at the Australasian Experimental Stockfeed Extrusion Centre at Roseworthy, South Australia. This diet was fed to all fish at WISAC from January 2007 until June 2007.
Daily records were maintained for each production tank of the feed provided and water quality parameters (i.e. DO, CO2, pH, salinity, water temperature, ammonia). Water quality measurements were taken between 12.30–2.00 pm each day. An Oxyguard® Portable CO2 meter (OxyGuard International A/S, Birkerφd, Denmark) was used to measure the concentration of dissolved CO2. The pH was measured daily using a WTW 340I pH conductivity meter (Wissenschaftlich-Technische Werkstätten, Weilheim, Germany). Ammonia was measured using a Reflectoquant® test kit (Merck KgaA, Darmstadt, Germany). Water temperature and DO levels were measured using a portable OxyguardTM Handygamma dissolved oxygen meter (OxyGuard International A/S, Birkerφd, Denmark).
6.3.2. Batch 2 – Fingerling Mulloway Between February and May 2006 mulloway larvae were cultured through to fingerlings at the SAASC R&D Hatchery. On 10 May 2006, the 10,500 mulloway fingerlings (2.0 g) produced were transported to WISAC. These fish were cultured in 10,000 L nursery tanks until they reached 55.5 ± 8.7 g (mean ±SD) when they were stocked into two 70,000 L production tanks on 5, 6 and 9 October 2006. Production tank G2 was stocked with 4,729 fish (total weight 262.5 kg) and production tank G3 was stocked with 5,183 fish (total weight 287.7 kg). On 31 July 2007, 1,260 fish were transferred from tank G3 to tank G2 to adjust the stocking density following a mortality event. On 5 October 2007, all fish in tank G2 were moved into a clean tank (G1) were they remained until all were harvested. On 10 December 2007, all fish in tank G3 were transferred into a cleaned tank (G2) were they remained until harvesting was completed. Feeding procedures, monitoring of growth and water quality parameters where conducted as described for Batch 1.
100 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
6.3.3. Product Safety and Sale of Mulloway Cultured at WISAC A sample of 10 fish between 350 g and 650 g were harvested to provide a composite sample of edible tissue to test the levels of polychlorinated biphenyls (PCBs), metals, pesticides, dioxins, malachite green (AgriQuality Ltd, Wellington, New Zealand), and antimicrobials (Department of Primary Industries Victoria, Weeribee, Victoria). All mulloway produced at WISAC were sold to local seafood distributors in the Riverland and in Adelaide. Generally, harvesting from a production tank commenced when the mean weight for fish exceeded 750 g. Fish supplied were processed and sold as whole fish, head on gilled and gutted, or as fillets. Quantities of fish were also supplied to chefs, and for consumer taste tests and surveys as part of the study Market research report: Salt interception schemes for finfish (PIRSA Aquaculture, unpublished).
6.4. Results
6.4.1. Batch 1 Fish grew from a mean weight of 340 g to a final mean weight of 1,290.4 ± 236.8 g (± SD, Figure 6.2). A total of 2,912 kg was harvested from tank G1. Of the 3,200 fish stocked 2,958 were harvested representing 92.4 % survival.
During the 449 days grow-out period, 3,916 kg of feed was consumed for a biomass gain of 1,824 kg representing a total FCR of 2.15. SGR, over the grow-out period was 0.30%/day. There were considerable variations in SGR and FCR recorded between months (Figure 6). Generally, low FCR values were recorded during months when SGR was high and conversely, high FCR values were recorded during months when SGR was low.
From December 2006 the CI (Figure 6.4) of market size fish in production tank G1 increased progressively from a mean of 0.98 ± 0.11(± SD) to a mean of 1.12 ± 0.11 on 29 March 2007, allowing sales to recommence in April 2007.
101 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
Figure 6.2. Monthly mean weight (kg, ± SD) of Batch 1 advanced mulloway cultured at WISAC for 449 days.
FCR SGR 3.5 1.00% 0.90% 3.0 0.80% 2.5 0.70% 2.0 0.60% 0.50% 1.5 0.40% 1.0 0.30%
Feed conversion ratio 0.20% 0.5 0.10% Specific growth rate (%/day) 0.0 0.00%
6 6 7 -06 -06 -0 0 -07 -07 07 07 t v c- b-07 ul- ay-06 Jul-06ug e un- J M Jun-06 A Sep-06Oc No D Jan-0Fe Mar Apr J Date
Figure 6.3. Monthly FCR and SGR of mulloway cultured in production tank G1 at WISAC for 449 days.
102 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
1.6
1.4
1.2
1.0
0.8 Condition index
0.6
0.4
7 -0 Jul-07 Dec-06 Jan-07 Feb Mar-07 Apr-07 May-07 Jun-07 Date
Figure 6.4. Monthly CI (mean ± standard deviation) for mulloway grown in production tank G1 at WISAC from 27 December 2006 until 30 July 2007 (216 days).
6.4.2. Batch 2 Mulloway fingerlings initially stocked at a mean weight of 55.5 ± 8.7 g (± SD) grew to a mean weight of 1,076.2 ± 204.5 g (± SD) in 543 days; and 902.8 ± 242.0 g (± SD) in 548 days (Figures 6.5 and 6.6) in production tanks G2 and G3 respectively.
On 24 March 2007, a mortality event occurred in tank G2 resulting in the loss of 2,286 fish (total weight 244.0 kg). This event was caused by water entering a circuit breaker and stopping oxygen supply to the tank overnight resulting in asphyxiation of 52% of the fish in the tank.
The total SGR recorded for fish initially stocked into production tanks G2 and G3 was 0.55% and 0.51% respectively. SGR data showed that the growth of mulloway was better during the early period of culture but declined as fish grew. SGR of fish growing between 55.5 g and approximately 180 g was 1.60 ± 0.60%/day (± SE) and 1.49 ± 0.44%/day for fish in production tanks G2 and G3 respectively (Figures 6.5 and 6.6). SGR declined for the remainder of the grow-out period with mean values of 0.37 ± 0.07%/day recorded for fish in tank G3 and 0.42 ± 0.05%/day for fish in tank G2.
Growth performance measured as SGR and FCR was highly variable between monthly samplings. In six month intervals when SGR exceeded 0.30%/day, the mean FCR was 1.39 ± 0.34 (± SE), while in the six monthly periods in which SGR was <0.30%/day, the mean FCR was 2.41 ± 0.60 indicating that fish may not have consumed sufficient feed during these months.
103 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
1,400 G2 3.00% Mean weight (g) SGR 1,200 2.50%
1,000 2.00% y = -0.0062Ln(x) + 0.0187 800 R2 = 0.6744 1.50%
600 1.00%
Mean weight (g) 400 0.50%
200 0.00% Specific growth rate (% bwt/day)
0 -0.50% Jul-07 Jul-07 Oct-06 Oct-07 Apr-08 Jan-07 Jun-07 Jan-08 Feb-07 Mar-07 Feb-08 Mar-08 Nov-06 Sep-07 Nov-07 Dec-06 Dec-07 May-07 Date
Figure 6.5. Monthly specific growth rate (SGR) and mean weight (g, ± SD) of mulloway cultured in production tank G2 at WISAC for 543 days.
1,400 Mean weight (g) SGR G3 3.00%
1,200 2.50%
1,000 2.00%
800 1.50% y = -0.0058Ln(x) + 0.0173 R2 = 0.7132 600 1.00%
Mean weight (g) 400 0.50%
200 0.00% Specific growth rate (% bwt/day)
0 -0.50% Jul-07 Jul-07 Oct-06 Oct-07 Apr-08 Jan-07 Jun-07 Jan-08 Feb-07 Mar-07 Feb-08 Mar-08 Nov-06 Sep-07 Nov-07 Dec-06 Dec-07 May-07 Date
Figure 6.6. Monthly specific growth rate (SGR) and mean weight (g, ± SD) of mulloway cultured in production tank G3 at WISAC for 548 days.
104 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
Data collected on 27 December 2006 showed that the CI of fish in tank G2 was 1.33 ± 0.16 (± SD) while at the same time the CI of fish in G3 was 1.30 ± 0.25 (± SD, Figure 6.7). Over the duration of the trial, the mean CI of fish stocked into production tanks G2 and G3 was 1.37 ± 0.07 (± SD) and 1.39 ± 0.07 (± SD) respectively, and over this period the CI of fish in both tanks improved as they grew larger. Fingerlings G2 Fingerlings G3 1.80
1.70
1.60
1.50
1.40
1.30 Condition index 1.20
1.10
1.00
07 -07 -07 -07 08 v-06 n- v-07 n- a ay Jul ep-07 No J Mar M S No Ja Mar-08
Date
Figure 6.7. Monthly mean condition index (± SD) of mulloway cultured in production tanks G2 and G3 at WISAC for 543 days and 548 days respectively.
6.4.3. Performance of all Batches of Mulloway Cultured at WISAC Survival of the advanced fish in tank G1 and the fingerlings in tank G3 was 92.4% and 94.8% respectively, compared to 46.5% for tank G2 where a mortality incident occurred due to a technical malfunction. The average survival across all tanks combined was 76.8% (Table 6.1).
Fish performance data collected (Table 6.1) from the two batches of mulloway cultured in three 70,000L production tanks at WISAC show that a total of 13,112 fish were stocked into three production tanks and these grew to market size resulting in the harvest of 9,772 kg, which equated to a biomass gain of 7,531 kg. These fish consumed a total of 15,280 kg of feed giving an apparent FCR of 2.03 for all tanks of fish combined. Total SGR of the advanced batch of mulloway was 0.30% compared to 0.55% and 0.51% for the batch of fingerlings initially stocked into production tanks G2 and G3 respectively. The maximum stocking density achieved when fish reached market size and during progressive harvesting
105 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
ranged from 28.2 kg/kL to 31.5 kg/kL for the three production tanks. This was within the 30 kg/kL target for the semi-intensive system.
To allow comparison of the different batches of mulloway cultured at WISAC, the number of days of culture from when fish of each batch were 2.0 g was calculated. This comparison (Figure 6.8) shows that similar growth performance was achieved by the advanced fingerlings and Batch 2 fingerlings initially stocked into production tanks G1 and G3 respectively. Batch 2 fingerlings initially stocked into production tank G2 were the best performing fish.
Batch 2 (G2 -G3) Batch 2 (G3 -G1)
Batch 1 Advanced All data 1400 1300 1200 1100 y = 0.0134x1.7082 1000 900 800 700 600 500 Mean weight (g) 400 300 200 100 0 0 100 200 300 400 500 600 700 800 900 Days from 2.0 g
Figure 6.8. Comparison of growth (days from 2.0 g) of two batches of mulloway cultured using SIS groundwater in three 70 kL production tanks at WISAC.
When all data for all batches are combined, the growth relationship y = 0.0134x1.7082 (R2 = 0.985) was generated, which can be used to estimate growth of typical mulloway cultured in SIS groundwater in the semi-intensive culture system at WISAC. Using data from the best performing fish (Batch 2 fingerlings stocked into tank G2) another growth relationship y = 0.0088x1.7913 (R2 = 0.992) was generated. These relationships indicate that the time taken for typical 2.0 g fingerlings to reach an initial market size of 750 g (Table 6.2) will be approximately 600 days (19.7 months, 1.64 years), while the best performing batch achieved this weight in 566 days (18.6 months, 1.55 years).
106 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
Table 6.1. Performance measures for two batches of mulloway cultured in three 70,000L tanks in SIS groundwater at WISAC from 8 May 2006 until 4 April 2008.
G1 G2 - G3 G3 - G1 All batches Start date 8-May-06 9-Oct-06 5-Oct-06 Finish date 7-Aug-07 4 April 08 4-Apr-08 Days in tank 449 543 548 Mean start weight (g) 340.0 55.5 ± 8.7 55.5 ± 8.7 Mean final weight (g ± SD ) 1290.4 ± 236.8 1076.2 ± 204.6 902.8 ± 242.0 Total harvest (kg) 2,912 3,262 3,599 9,772 Total biomass gain (kg) 1,824 2,412 3,295 7,531 Total feed (kg) 3,916 5,352 6,012 15,280 Total FCR 2.15 2.22 1.82 2.03 Total SGR 0.30 0.55 0.51 Number fish stocked 3,200 4,729 5,183 13,112 Max. stocking density (kg/KL) 31.5 28.2 29.5 Mortalities 242 2,529 267 3,038 Total survival 92.4% 46.5% 94.8% 76.8%
Feedback from fish processors and distributors suggest that more options for markets for mulloway would be available if larger fish were cultured. Using the relationships generated, the culture period predicted (Table 6.2) for mulloway to achieve 1.5 kg, 2.0 kg and 3.0 kg will be approximately 905 days (29.8 months, 2.48 years), 1,070 days (35.2 months, 2.93 years) and 1,360 days (44.7 months, 3.73 years) respectively for typical fingerlings; and 835 days (27.5 months, 2.29 years), 980 days (32.2 months, 2.68 years) and 1,230 days (40.4 months, 3.37 years) respectively for the best performing fish.
107 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
Table 6.2. Growth models (all batches and best batch) of number of days for 2.0 g mulloway to achieve target weights based upon data collected from Batch 1 advanced and Batch 2 fingerlings cultured to market size at WISAC between May 2006 and April 2008.
Mulloway growth in SIS groundwater at WISAC All batches R2 0.985 Best batch R2 0.992 Model formula y = 0.0134x^1.7082 y = 0.0088x^1.7913
Days Days Weight (g) post 2 g Months Years Weight (g) post 2 g Months Years 10.7 50 1.6 0.14 9.7 50 1.6 0.14 35.0 100 3.3 0.27 33.7 100 3.3 0.27 114.2 200 6.6 0.55 116.5 200 6.6 0.55 228.3 300 9.9 0.82 240.9 300 9.9 0.82 373.2 400 13.2 1.10 403.2 400 13.2 1.10 546.4 500 16.4 1.37 601.4 500 16.4 1.37 643.0 550 18.1 1.51 748.6 565 18.6 1.55 746.0 600 19.7 1.64 833.7 600 19.7 1.64 970.7 700 23.0 1.92 1,098.8 700 23.0 1.92 1,092.2 750 24.7 2.05 1,243.3 750 24.7 2.05 1,219.4 800 26.3 2.19 1,507.0 835 27.5 2.29 1,505.4 905 29.8 2.48 1,723.5 900 29.6 2.47 1,785.3 1000 32.9 2.74 2,007.5 980 32.2 2.68 2,004.0 1070 35.2 2.93 2,469.0 1100 36.2 3.01 2,437.6 1200 39.5 3.29 2,885.5 1200 39.5 3.29 2,613.6 1250 41.1 3.42 3,016.0 1230 40.4 3.37 2,794.7 1300 42.7 3.56 3,330.3 1300 42.7 3.56 3,018.7 1360 44.7 3.73 3,803.1 1400 46.0 3.84
Growth data from mulloway cultured at WISAC showed that the fish cultured in SIS groundwater grow faster than wild mulloway and hatchery produced mulloway cultured in commercial seacages (Figure 6.9). Available data suggests that it will take 900 days (29.6.0 months, 2.47 years) for mulloway cultured in ambient seawater conditions in seacages to achieve 750 g; and 1,140 days (37.5 months, 3.12 years) for wild fish to achieve this weight compared to 600 days (19.7 months, 1.64 years) for typical mulloway cultured in SIS groundwater at WISAC.
108 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
Wild fish WISAC fish Seacage fish 2,000
1,750
1,500
1,250 y = 0.0004x2.2151 2 1,000 R = 0.99 3.6188 y = 7E-09x 2
Weight (g) Weight R = 0.9833 750
500
250
0 0 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200 1,300 1,400 1,500
Days
Figure 6.9. Comparison of growth of mulloway cultured in SIS groundwater at WISAC, in ambient seawater in commercial seacages, and in natural conditions in the wild.
109 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
6.4.4. Product Safety and Sale of Mulloway Cultured at WISAC Analysis of mulloway tissue showed no detectable amounts of the 208 pesticides and 30 antimicrobial screened. Levels of all metals, malachite green, crystal violet, PCBs and dioxins were below the maximum residue levels for these compounds (Table 6.3).
Table 6.3. Results from testing and screening for pesticides, antimicrobials, metals triphenylmethane dyes, PCBs and dioxins from a composite sample of flesh from mulloway (n = 10) cultured at WISAC.
Category Type Concentration Pesticides N = 208 screened All < method detection limit Antimicrobials N = 30 screened All < limit of reporting
Metals (mg/kg) Antimony <0.01 Arsenic 0.21 Cadmium 0.0023 Chromium <0.1 Copper 0.24 Lead <0.01 Mercury 0.021 Selenium <0.1 Zinc 4.3 Triphenylmethane dyes Malachite green <0.1 (mg/kg) Crystal violet <2 PCBs Total concentration Fresh weight 1.11 (mg/kg) Lipid weight basis 26.7 Toxic equivalence Fresh weight 0.191 (TEQ, pg TEQ/g) Lipid weight basis 4.58 Dioxins Total concentration Fresh weight 2.22 (mg/kg) Lipid weight basis 129 Toxic equivalence Fresh weight 0.225 (TEQ, pg TEQ/g) Lipid weight basis 13
Prices received for whole gut in mulloway ranged from $6.60/kg to $7.00/kg. Retail price reported for these fish sold as ‘Murray Mulloway’ (Figure 6.10) ranged from $12.00/kg to $14.00/kg for whole fish and $22.00/kg to $25.00/kg for fillets. Information provided by fish processors suggest that product recovery rates achieved for mulloway cultured in SIS groundwater were between 85% and 88% for whole gilled and gutted fish, 52% and 54% for scaled ‘wing-on’ fillets; between 48% and 50 for skin on fillets (‘wing off’); and between 45% and 48% for skin off fillets (Adelaide Fish Processors, 2008). Fish supplied to
110 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
restaurants and chefs catering for local food industry and charity functions were always well accepted and reported to be a high quality product.
Figure 6.10. The logo used to market the mulloway from WISAC.
6.5. Discussion FCR for the batches of mulloway cultured to market size in SIS groundwater at WISAC were between 1.82 and 2.22. Previous studies of mulloway cultured in saline groundwater reported FCR of 2.1 (Doroudi et al., 2006) and 1.39 (Partridge et al., 2006). Panagiotidou (2007) reported mean FCR of 1.26 ± 0.10 (± SD) for the closely related brown meagre, Argyrosomus regius, that is being developed as an aquaculture species in the Mediterranean. In this study, fish were cultured in 500 L tanks from an initial mean weight of 84 ± 10 g (± SD) to a final mean weight of 214.7 ± 11.6 g over seven months. Although not optimal, these values compare favourably with yellowtail kingfish, Seriola lalandi, being developed for aquaculture. FCR values of 3.1 and 3.4 and SGR values of 0.32% and 0.25% have been reported for yellowtail kingfish cultured commercially in two seacages in Fitzgerald Bay, South Australia over a period of 283 days and 324 days during which fish grew from 1.3 kg to a mean weight of 3.3 kg and 2.9 kg respectively (Fernandes and Tanner, 2007). In comparison with other established aquaculture species, the FCR of mulloway is higher.
111 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
Tantikitti et al. (2004) reported FCR of between 1.03 and 1.33 for barramundi, Lates calcarifer, fed on an experimental pellet. For Atlantic salmon, Salmo salar, FCR can be in the order of 1.0 in commercial culture, and levels between 0.78 and 0.86 have been obtained with experimental feeds (Hevroy et al., 2004) while FCR of 1.14 has been reported with red sea bream, Pagrus auratus (Sarker et al., 2005). The relatively high FCR of mulloway cultured at WISAC and in other studies compared to the FCR achievable with these established aquaculture species suggests that better feed utilisation might be achieved through improvements in feeding strategies and diet formulation.
During the grow-out period, the growth trajectory of mulloway cultured at WISAC was almost linear, rather than exponential as would be expected for the early growth period of cultured fish (Westers, 2001). Over the duration of the grow-out period, SGR of the advanced batch of mulloway was 0.30% compared to 0.55% and 0.51% for the batch of fingerlings initially stocked into production tanks G2 and G3 respectively. Doroudi et al. (2006) reported exponential growth for juvenile mulloway represented by an SGR of 1.15%/day over a 243 day trial in which fish were maintained in 500 L tanks at 20.0 ± 1.0oC. In this trial, mulloway grew from an initial mean weight of 10.8 ± 2.1 g (± SD) to a final mean weight of 270 ± 35 g. Recently, Panagiotidou (2007) reported that SGR of Argyrosomus regius was 0.46 ± 0.02 g (± SD), and it is suggested that this species has a relatively high growth rate and is capable of achieving 1 kg in one year of culture (Cardia and Lovatelli, 2007). Partridge et al. (2006) reported SGR of 0.69% for mulloway growing from 116 g to 384 g over 174 days in a semi- intensive floating tank system in a pond containing groundwater supplemented to provide a K:Cl ratio of 0.016. In this study, the water temperature ranged from 18.4oC to 24.8oC. In comparison, similar size mulloway in production tanks G2 and G3 at WISAC grew over a period of 187 days from initial mean weights of 126.8 ± 18.7 g (± SD) and 117.2 ± 19.7 g respectively, to final mean weights of 392.8 ± 74.3 g and 370.7 ± 57.6 g representing an SGR of 0.60%/day for fish in tank G2 and an SGR of 0.62%/day for fish in tank G3. These data suggest that an SGR between 0.60–0.69%/day can be expected for mulloway growing from approximately 120 g to 390 g in water temperatures between 18.5oC and 25.0oC.
For the second batch of fingerlings cultured at WISAC, the SGR was high (i.e. >1.40%/day) while fish were less than approximately 180 g. SGR declined to mean values of 0.37 ± 0.07% (± SE) for fish in tank G3, and 0.42 ± 0.05% for fish in tank G2 as fish grew to final mean weights of 1,076 ± 204.6 g (± SD) and 902.8 ± 242.0 g in the respective tanks. This decline in SGR with increasing body weight is usual for many fish species (Jobling, 1993).
When considering the difficulties often experienced in growing finfish using groundwater, the suitability of the level of potassium present is often discussed, as this physiologically important ion is frequently deficient in saline groundwater. Potassium deficiency causes mortality in a number of species of finfish that have been investigated for aquaculture in saline groundwater. Mortality attributed to hypokalaemic muscle myopathy has been reported in barramundi (Lates calcarifer) cultured in 45 g/L groundwater that was deficient in potassium (Partridge and Creeper, 2004). Fielder et al. (2001) reported mortality in snapper (Pagrus auratus) cultured in a saline groundwater from the Wakool-Tullakool subsurface drainage scheme in south western NSW. Salinity of this water was 19 mg/L and had a potassium concentration of only 9.2 mg/L. This mortality was corrected by increasing the potassium concentration to 83 mg/L, although growth improved up to a potassium
112 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
concentration of 124 mg/L after which no further improvement in growth was achieved when compared to fish grown in equivalent salinity seawater (K = 207 mg/L). Using groundwater from the same source, Doroudi et al. (2006) report maximum survival of mulloway at a potassium concentration equivalent to 38% (78.7 mg/L) of that present in equivalent salinity seawater, and in a further trial reported maximum survival and growth above 40% (82.8 mg/L). These results agree with results obtained by SARDI in trials conducted on snapper (Chapter 4) and yellowtail kingfish (Chapter 5). These trials concluded that the SIS groundwater supplied to WISAC (salinity 20.5 g/L, potassium 92 ± 2.1 mg/L equivalent to 41.9% of the level found in 35 g/L seawater) supported the same growth rate for mulloway as equivalent salinity seawater, while the growth of snapper was impaired at this level of potassium. These research findings suggest that it is unlikely that the level of potassium in the SIS groundwater used has affected the growth performance of mulloway cultured at WISAC.
The CI of mulloway cultured in all production tanks was variable between months showing unexplained periods of decline and improvement for fish in all production tanks monitored. At present there is insufficient data to recommend what a desired CI should be for a given size of mulloway. Feedback from commercial finfish processors on the WISAC product suggests that a value greater than 1.1 should be targeted for fish at a harvest size of approximately 750 g.
The opportunity to improve feed utilisation and achieve better growth and condition of mulloway is indicated by the high variability of FCR and SGR between monthly samplings reported from all production tanks. It is expected that a combination of factors have affected these FCR, SGR and CI results, including: • difficulties encountered by technical staff such as the restricted ability to carefully observe feeding response by the fish in reduced visibility water within dark coloured production tanks • the need for fish to be disturbed at regular intervals to allow partial harvest and to obtain monthly growth data • elevated levels of dissolved carbon dioxide in production tanks that may have contributed to reducing the growth performance (Chapter 8).
The fish cultured in SIS groundwater using the semi-intensive aquaculture system at WISAC grew faster than both wild mulloway and hatchery produced mulloway cultured in commercial seacages. Data collected from mulloway cultured in three 70,000 L production tanks at WISAC showed that it took in the order of 600 days for fish to grow from 2.0 g to a marketable size of 750 g, and it is predicted that the best performing fish would achieve the more marketable size of 1.5 kg in approximately 835 days (27.5 months) and it would take a further 65 days to achieve 2.0 kg. This growth rate and product size is superior to that of other marine finfish species that support significant industries in other countries. Sea bream (Sparus auratus) and sea bass (Dicentrarchus labrax) comprise 85% of production from cage aquaculture in the Mediterranean (Cardia and Lovatelli, 2007) where production of these two species was approximately 190,000 tonnes in 2006 (Kirsch, 2006). Sea bass and sea bream cultured in seacages in Croatia achieve market size of 350 g in 22 months and 15 months respectively. Seasonal water temperature range in this country is 10–13oC in winter and 24– 26oC in summer (Šarušić, 2000). Generally, in the Mediterranean region, sea bass and sea
113 Chapter 6 – Performance of mulloway, Argyrosomus japonicus, cultured in SIS groundwater at WISAC
bream achieve market size of between 300 g and 400 g within 16 to 18 months and 14 to 16 months respectively (Cardia and Lovatelli, 2007). This suggests that the culture period of mulloway in SIS groundwater in the proof of concept aquaculture system at WISAC was better than the culture period of these temperate water marine finfish that support significant commercial aquaculture industries in other countries although this production is undertaken in ambient water conditions.
Testing of fish to address food safety concerns revealed that the mulloway cultured in SIS groundwater were free of all compounds that were tested, providing the potential to produce a quality assured product. It is suggested that the prices obtained for mulloway cultured at WISAC do not necessarily reflect the potential prices that could be obtained from a larger production operation that could maintain consistent supply and invest in marketing and promotion of the product. Discussions with processors and marketing studies (Ruello, 2004) indicated that the culture of larger fish (>1.5kg) should be targeted in future as there are positive market prospects for fish of this size as they provide greater versatility and potentially higher value due to greater meat recovery from larger fish. This positive outlook is due to growing demand for boneless fillets and portion controlled pieces that could be supplied from larger cultured mulloway (Ruello, 2004).
6.6. Conclusions and Recommendations SGR and FCR data indicate performance of mulloway in the semi-intensive aquaculture system utilising SIS groundwater was comparable to results achieved with this species in other studies and was superior to the growth performance of mulloway cultured in seacages and in the wild. Growth of mulloway cultured in SIS groundwater in the semi-intensive aquaculture system at WISAC is comparable to performance of other species cultured commercially in South Australia and is faster than other temperate finfish species that support significant aquaculture industries internationally. These results suggest that further research is required to gain a greater understanding of feeding and other requirements of mulloway during different stages of growth within different aquaculture systems and environmental conditions. Further improvement in feed management and production system operation may assist the ability to achieve consistent periods of optimal growth (SGR) and body condition during which feed utilisation (FCR) is optimised.
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6.7. References Bagenal, T.B. and Tesch, F.W. 1978. Age and growth: In T.B. Bagenal (Editor), Methods for assessment of fish production in fresh waters, 3rd Edition, Blackwell Scientific Publications, Oxford, England, pp. 101–136. Cardia, F. and Lovatelli, A. 2007. In: Halwart, M., Soto, D. and Arthur, J.R. (Editors). Cage aquaculture—regional reviews and global overview, pp. 156–187. FAO Fisheries Technical Paper No. 498, Rome, 241 pp. Doroudi, M.S., Fielder, D.S., Allan, G.L. and Webster, G.K. 2006. Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Aquaculture Research, 37: 1034–1039. Fernandes, M. and Tanner, J. 2007. Modelling of nitrogen and phosphorous loads from yellowtail kingfish (Seriola lalandi) aquaculture. In: Tanner, J.E., Clark, T.E., Fernandes, M. and Fitzgibbon, Q. Innovative solutions for aquaculture: Spatial impacts and carrying capacity—further developing, refining and validating existing models of environmental effects on finfish farming. SARDI Aquatic Sciences Publication No. F2007/000537. South Australian Research and Development Institute (Aquatic Sciences), Adelaide, 126pp. Fielder, D.S., Bardsley, W.J. and Allan, G.L. 2001. Survival and growth of Australian snapper, Pagrus auratus, in saline groundwater from inland New South Wales, Australia. Aquaculture 201: 73–90. Hevroy, E.M., Sandnes, K. and Hemre, G.I. 2004. Growth, feed utilization, appetite and health in Atlantic salmon (Salmo salar) fed a new type of high lipid fish meal, Sea Grain, processed from various pelagic marine fish species. Aquaculture 235: 371–392. Jobling, M. 1993. Bioenergetics: Feed intake and energy partitioning. In: Rankin, J.C and Jensen, F.B (Editors), Fish Ecophysiology, Chapman Hall, London, pp. 1–44. Kirsch, B. 2006. Marine aquaculture from a Mediterranean perspective. Conference presentation—Future Aquaculture, Trieste, Italy 14–15 September, Eurofish International Organisation. Panagiotidou, M. 2007. Biological basis for culture of Meagre, Argyrosomus regius. PhD thesis, University of Crete. Partridge, G.J. and Creeper, J. 2004. Skeletal myopathy in juvenile barramundi, Lates calcarifer (Bloch), cultured in potassium-deficient saline groundwater. Journal of Fish Diseases 27: 523–530. Partridge, G.J., Sarre, G.A., Ginbey, B.M., Kay, G.D. and Jenkins, G.I. 2006. Finfish production in a static, inland saline water body using a Semi-Intensive Floating Tank System (SIFTS). Aquaculture Engineering 35: 109–121. Ruello, N. 2004. Inland saline aquaculture: Market and supply chain development. Report prepared for the National Aquaculture Council. Ruello and Associates Pty Ltd, 60 pp.
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Sarker, S.A., Satoh, S. and Kiron,V. 2005. Supplementation of citric acid and amino acid- chelated trace element to develop environment-friendly feed for red sea bream, Pagrus major. Aquaculture, 248: 3–11. Šarušić, G. 2000. Mariculture on Croatian Islands. Ribarstvo, 58: 111–118. Tantikitti, C., Sangpong, W and Chiavareesajja, S. 2005. Effects of defatted soybean protein levels on growth performance and nitrogen and phosphorous excretion in Asian seabass (Lates calcarifer). Aquaculture, 248: 41–50. Westers, H. 2001. Production p. 31–90. In: Wedemeyer G.A. (Editor) Fish hatchery management, 2nd Ed. American Fisheries Society, Bethesda, Maryland, USA.
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Appendix 6.1. Formulation of the mulloway diet produced by SARDI at the Australasian Experimental Stockfeed Extrusion Centre, Roseworthy.
Ingredient g/kg Choline chloride 3 Lecithin 7.2 Ethoxyquin 0 Mineral & vitamin premix 2 Fish oil 100 Wheat gluten 200 Fish meal 635 Krill meal 10 KCL 15.28 Sulphur 10 EDS-50 (Vitamin E) 0.24 Stay C 35 0.33 Water additional approx 18
117
118 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
Chapter 7 – Performance of a Semi-Intensive Aquaculture System for Culture of Mulloway at WISAC
7.1. Summary Between May 2006 and March 2008, water quality parameters and water usage were monitored for saline groundwater supplied from the Woolpunda SIS and in mulloway production tanks at WISAC.
The temperature of SIS groundwater varied seasonally from a minimum monthly mean of 20.3 ± 0.1oC (± SE) in June 2006 to a maximum monthly mean of 26.0 ± 0.2oC (± SE) in February 2007. The water temperature in production tanks was maintained between 18.5oC and 25oC. This temperature range is considered to be favourable for the growth of mulloway.
Salinity of SIS groundwater remained stable with a monthly mean concentration of 20.45 ± 0.01 g/L (± SE). This salinity is considered suitable for a euryhaline species such as mulloway.
The mean dissolved oxygen concentration in groundwater supplied from the SIS pipeline before degassing was 5.0 ± 0.1% saturation (± SE). After passing through the degassing column the mean dissolved oxygen concentration of SIS groundwater entering the storage tanks for use at WISAC was 89.6 ± 0.4% saturation. A monitoring and control system maintained the dissolved oxygen in each mulloway production tank between 70–100% saturation.
Increases in turbidity (>40 nephelometric turbidity units, NTU) were mostly related to maintenance operations conducted on the SIS pipeline, and turbidity often exceeded 100 NTU following these procedures. Turbidity of SIS groundwater showed a pattern of gradual increase from approximately 5 NTU to approximately 30 NTU over a period of six months after which major pigging operations reduced turbidity back to 5 NTU. Technical staff located at WISAC received notification of planned SIS maintenance at least 24 hours before commencement. During maintenance procedures WISAC was isolated from the SIS groundwater supply for between 12 hours and 3 days.
A consistently elevated level of dissolved CO2 was recorded in the SIS groundwater supplied to WISAC. Passage of all incoming SIS groundwater through a packed column degasser decreased dissolved CO2 from a mean concentration of 63.4 ± 0.6 mg/L (± SE) to a mean concentration of 17.5 ± 0.3 mg/L without decreasing water temperature.
The monthly mean concentration of dissolved CO2 in each production tank was consistently elevated The maximum monthly mean concentration of dissolved CO2 recorded was 32.6 ± 1.1 mg/L (± SE) and the minimum monthly mean concentration of dissolved CO2 was 8.4 ± 0.3 mg/L.
The scientific literature in relation to other finfish species was ambivalent about whether such a dissolved CO2 level will impact the growth rate of mulloway. However, based on the results
119 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
of the research undertaken at WISAC, the high CO2 levels were considered responsible for the slow growth performance of mulloway, and as such that the effect of varying CO2 levels on mulloway growth performance should be experimentally assessed (Chapter 8).
It is considered that the saline groundwater available from the Woolpunda SIS provides a significant opportunity for aquaculture. It is also believed that the advantage offered by the elevated temperature of SIS groundwater at WISAC was limited by the elevated levels of dissolved CO2 characteristic of this same water. In addition, there was an increase in the concentration of dissolved CO2 occurring due to the design and manner of operation of the semi-intensive aquaculture system used to culture mulloway at WISAC.
Alternative mechanisms are highlighted for further reducing dissolved CO2 levels in the water to be used for finfish culture at WASIC, with the challenge being to achieve this while retaining the desired water temperatures to optimise mulloway growth.
The major operating cost items considered equated to production costs of between $6.36/kg and $8.10/kg for the three batches of mulloway cultured at WISAC. Feed represented the major operating cost considered (47.7%), followed by electricity (29.6%) and then oxygen (19.8%).
Suggestions to improve system performance and reduce operating costs include: • reducing FCR
• improved management of dissolved CO2 • more efficient use of oxygen • site selection to reduce cost of pumping water to return it to the SIS.
It is suggested that use of an intensive aquaculture system may allow these issues to be addressed.
7.2. Background Utilising SIS groundwater for aquaculture is a novel use of this resource. Although commercial use of this water is desirable, there is a paucity of information on the fundamental parameters that could affect production and how these are affected by system operations, fish growth and seasonal fluctuations. To start to accumulate this information, three batches of mulloway were cultured to marketable size (>750 g) in 70,000 L tanks at WISAC between May 2006 and March 2008. During cultivation of these fish, records were kept of the major water parameters, water usage, problems experienced and operating costs incurred. Consideration of the information collected provides insight to identify key factors that can affect production and approaches needed to improve upon the system performance achieved during this initial demonstration trial.
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7.3. Methods Turbidity of SIS groundwater supplied to WISAC was recorded by a turbidity system (ABB Limited, Stonehouse, Gloucestershire, UK). The system included a turbidity sensor (output range 0–100 NTU) with maximum acceptable turbidity and alarm set at 40 NTU. A wall mounted analyser provided a visual display of turbidity and logged data measurements every 15 minutes.
An oxygen monitoring and control system (Analogue and Digital Services Pty Ltd, East Fremantle, Western Australia) provided monitoring and logging of levels of dissolved oxygen and water temperature in each of the three production tanks used to culture mulloway. This system also controlled the level of dissolved oxygen through introduction of compressed oxygen at the impeller of the Force 7 (Acqua & Co®, Via Augera, Italy) dissolution device installed within each production tank. Oxygen was supplied when dissolved oxygen levels in each production tank were between an upper set point of 95% saturation and a lower set point of 80% saturation.
Between 10 May 2006 and 13 August 2007, all dissolved CO2 was measured by a standard titration method (Appendix 7.1). The average level of dissolved CO2 in incoming SIS groundwater (pre-degassing) measured by titration over this period was 115.2 ± 16.6 mg/L. This level of dissolved CO2 was considered to be too high for mulloway culture given that levels greater than 100 mg/L (Ferguson, 1988) and 200 mg/L (Needham, 1988) are recommended for short term anaesthesia of finfish. The high levels of dissolved CO2 measured by titration were greater than the levels predicted when using an alternative method that provides a measure for dissolved CO2 based upon chemical relationships between pH, water temperature and alkalinity, that govern the amount of dissolved CO2 present in water (Appendix 7.3) (Wurts and Durborow, 1992). Using the alternative method for average measures of total alkalinity (473.2 ± 19.5 mg/L as CaCO3, ± SE), pH (7.20 ± 0.15) and water temperature (23.30 ± 2.11oC) for the SIS groundwater entering WISAC from 29 May 2006 until 30 May 2007, it was predicted that this water should contain 61.5 mg/L dissolved CO2. This level is much lower than the average level of 115.2 ± 16.6 mg CO2/L measured using the titration method.
Due to concerns about the accuracy of dissolved CO2 measurements being collected at ® WISAC, it was decided to purchase an Oxyguard CO2 Portable (OxyGuard International A/S, Birkerφd, Denmark, Appendix 7.3). This meter determines the concentration of free dissolved CO2 by direct measurement of the partial pressure of CO2 present in a water sample. From 13 August 2007, all CO2 measurements were taken using the Oxyguard CO2 meter. Comparative measurement of the same samples using the titration method and the CO2 meter (Appendix 7.4) provided a relationship best explained by the formula:
Y = X1.6697 x 0.0242 (R2 = 0.994)
All dissolved CO2 data determined by titration and collected prior to 13 August 2007 were corrected using this formula. It is suggested that these values more truly represent the actual levels of dissolved CO2 present in SIS groundwater supply and culture systems at WISAC as the measurement is not influenced by the many additional elements present in groundwater. These elements may affect the results obtained using the titration method, which was
121 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
developed primarily for freshwater use where total alkalinity is primarily from bicarbonate ions.
Water usage was measured by a MagMaster™ electromagnetic flowmeter (ABB Limited, Stonehouse, Gloucestershire, UK) installed within the 200 mm inlet pipeline supplying SIS groundwater to WISAC. Within the site laboratory, a wall mounted keypad display showed water usage (litres) and flow rate (L/sec). Total water use was recorded at the start of each day to determine the previous day’s water usage.
Daily measurements were taken of water quality parameters (i.e. DO, CO2, pH, salinity, ® water temperature, ammonia) in each production tank. An Oxyguard CO2 Portable meter (OxyGuard International A/S, Birkerφd, Denmark) was used to measure the concentration of dissolved CO2. The pH was measured daily using a WTW 340I pH conductivity meter (Wissenschaftlich-Technische Werkstätten, Weilheim, Germany). Ammonia was measured using a Reflectoquant® test kit (Merck KgaA, Darmstadt, Germany). Water temperature and DO levels were measured using a portable OxyguardTM Handygamma dissolved oxygen meter (OxyGuard International A/S, Birkerφd, Denmark).
Records were kept of water and oxygen use and feed consumption, as these represented the major costs incurred during the production of mulloway. No pumping (i.e. electricity) costs were incurred to supply groundwater to WISAC as there was approximately 16 m head pressure within the SIS pipeline. However, all water used at WISAC was pumped back into the pipeline against this pressure representing a considerable electricity cost. This cost was estimated from the electricity (kilowatt hours, KwH) required to pump the volume of water used each day back into the SIS pipeline and to pump reused SIS water back to fish production tanks. Electricity required was taken from the performance curves of the submersible pumps installed to return water to the SIS pipeline (Flygt Model 3171) and to pump reused SIS water back to the fish production tanks (Flygt Model 3102). Electricity cost used was $0.137/KwH, determined from charges for different tariffs on accounts received. The feed cost used was $1.80/kg based upon accounts received for feed purchased. A cost of $1.00/kg for oxygen was used to calculate production costs, as it is assumed that a commercial facility would use oxygen supplied from an on-site liquid oxygen storage vessel. The oxygen cost used was provided by a supplier (BOC) of bulk oxygen nd includes the cost of installation and rental of the required liquid oxygen storage vessel.
7.4. Results
7.4.1. Water Temperature The temperature of SIS groundwater supplying aquaculture systems at WISAC varied seasonally (Figure 7.1). The minimum monthly mean temperature of the groundwater supplied from the Woolpunda SIS for a complete month was 20.33 ± 0.14oC (± SE) during June 2006. The maximum monthly mean water temperature was 25.96 ± 0.14oC during February 2007. Over this period, the mean water temperature of incoming SIS groundwater was 23.15 ± 0.09oC. The mean difference between the temperature of incoming SIS groundwater and water within production tanks was 1.22 ± 0.11oC.
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SIS water Tank G1 Tank G2 Tank G3 28
26
24
22
20 Water temperature (oC)
18
16
6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 8 8 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 - - l------r- - - - l------r- y n u g p t v c n b a r y n u g p t v c n b a a u J u e c o e a e p a u J u e c o e a e M J A S O N D J F M A M J A S O N D J F M Date
Figure 7.1. Monthly mean temperature (oC ± SE) of SIS groundwater entering WISAC and in production tanks used to culture mulloway.
Throughout the period during which the advanced fingerlings (G1) were cultured at WISAC, the mean monthly water temperature varied seasonally (Figure 7.2) with a maximum of 25.1 ± 0.8oC (± SD) recorded in February 2007 and a minimum of 18.4 ± 0.8oC in August each year (2006 and 2007). The second batch of fingerlings initially stocked into production tank G2, were cultured in water with a maximum monthly mean temperature of 25.0 ± 0.8oC during February 2007 and 24.6 ± 1.2oC during January 2008. The minimum mean monthly water temperature was 18.4 ± 0.8oC during July 2007 (Figure 7.2). For fish initially stocked into production tank G3, the maximum monthly mean water temperature was 25.0 ± 0.8oC during January 2007 and 24.6 ± 1.1oC during January 2008. The minimum mean monthly water temperature was 18.4 ± 2.1oC during August 2007 (Figure 7.2). No seasonal relationship between growth and water temperature was apparent for mulloway in any of the production tanks.
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Weight Water temperature G1 1,600 30 1,400 25 1,200 20 1,000
800 15 600 10
Mean weight (g) 400 5
200 Water temperature (oC) 0 0
6 7 7 7 06 06 -0 0 -0 g- r Jul-0 ov- Jul May-06Jun-06 Au Sep-06 Oct-06N Dec-06Jan-07Feb-07Mar-07Ap Jun- Aug-07
1,400 G2 30 1,200 25 1,000 20 800 15 600 10 400 Mean weight (g) 200 5 Water temperature (oC) 0 0
06 06 07 -07 -07 -07 07 07 -08 c- n- c- r-08 e eb-07 Jul Jul ov-07e eb-08 a pr Oct-06Oct-06Nov- D Ja F Mar May-07Jun-07 Sep-07Oct- N D Jan-08F M A
1,400 G3 30 1,200 25 1,000 20 800 15 600 10 400 Mean weight (g) 200 5 Water temperature (oC)
0 0
6 7 7 -0 06 06 0 -0 07 07 08 ct ct ov- ec- ay-07 Jul-07 ov- ec- Oct-06O N D Jan-07Feb-07Mar-07M Jun- Aug-07Sep-07O N D Jan-08Feb-08Mar-08Apr- Date
Figure 7.2. Monthly mean water temperature (oC ± SD), and monthly mean weight (g, ± SD) of mulloway culture in production tanks G1 (449 days), G2 (543 days) and G3 (548 days) at WISAC.
124 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
7.4.2. Salinity The salinity of SIS groundwater within each production tank remained virtually constant throughout each year (Figure 7.3). Monthly mean salinity recorded for production tank G1 showed the greatest range of salinity varying from 19.86 ± 0.05 g/L (± SE) to 20.63 ± 0.03 g/L. For production tank G2, the mean monthly salinity ranged from a minimum 20.21 ± 0.02 g/L to 20.54 ± 0.02 g/L while a similar range of between 20.23 ± 0.05 g/L and 20.56 ± 0.02 g/L was recorded for production tank G3.
21.0 G1 20.8
) 20.6 20.4 20.2 20.0
Salinity (g/L 19.8 19.6 19.4 May - Jun- Jul- Aug- Sep- Oct- Nov- Dec- Jan- Feb- Mar - Apr- May - Jun- Jul- Aug- 06 06 06 06 06 06 06 06 07 07 07 07 07 07 07 07
21.0 G2 20.9 20.8 20.7 20.6 20.5 20.4 20.3 20.2 20.1 20.0 Oct- Nov - Dec - Jan- Feb- Mar - Apr- May - Jun- Jul- Aug- Sep- Oct- Nov - Dec - Jan- Feb- Mar - Apr- 06 06 06 07 07 07 07 07 07 07 07 07 07 07 07 08 08 08 08
21.0 G3 20.9 20.8 20.7 20.6 20.5 20.4
Salinity (g/L) 20.3 20.2 20.1 20.0 Oct- Nov - Dec - Jan- Feb- Mar - Apr- May - Jun- Jul- Aug- Sep- Oct- Nov - Dec- Jan- Feb- Mar - 06 06 06 07 07 07 07 07 07 07 07 07 07 07 07 08 08 08 Month
Figure 7.3. Monthly mean salinity (g/L ± SE) of water in production tank G1 at WISAC from 1 October 2006 until 31 May 2007.
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7.4.3. Dissolved Oxygen The mean dissolved oxygen concentration in groundwater supplied from the SIS pipeline before degassing was 5.0 ± 0.1% saturation (± SE). After passing through the degassing column, the mean dissolved oxygen concentration of SIS groundwater entering the storage tanks for use at WISAC was increased to 89.6 ± 0.4% saturation (± SE, Figure 7.4). Throughout the period that mulloway were cultured at WISAC, the monitoring and control system maintained the dissolved oxygen in each production tank between 70-100% saturation, measured by probes located in the discharge water standpipe of each production tank. Logged data for each tank (Figure 7.5) showed a regular pattern of control responding to an upper set point of 95% saturation and a lower set point of 80% saturation throughout each day.
Pre-Degassing DO (% Sat) Post-Degassing DO (% Sat) 120
100
80
60
40 Dissolved oxygen (% Sat)
20
0
6 6 6 6 7 7 7 7 7 7 8 0 0 0 0 0 0 0 0 0 0 0 - l------l- - - - y u p v n r y u p v n a J e o a a a J e o a M S N J M M S N J Date Figure 7.4. Mean dissolved oxygen concentration (% saturation ± SE) of SIS groundwater before (pre) and after (post) degassing at WISAC.
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6 March 2007 Tank 1 Tank 2 Tank 3 120
110
100
90
80
70
60
50 Dissolved oxygen (% Sat)
40
M M M M M M M M M M M M M M M M AM A AM A A AM A A A A A P P PM P P PM P P P P 0 0 0 0 0 0 0 0 AM 0 0 0 0 0 0 0 0 :0 :0 :0 :00 :0 :0 :00 :00 0 :0 :0 :0 :0 :00 :0 :0 :00 1 2:0 3 4 5:0 6 7 8 9 1: 1 2 3:0 4 5 6:0 7 8 9 12:00 10 1 12:00 PM 10:0011 PM Time
Figure 7.5. Typical daily log (6 March 2007) of dissolved oxygen (% saturation) in effluent water from three mulloway production tanks at WISAC.
7.4.4. Turbidity Logged turbidity data (Figure 7.6) shows that increases in turbidity (>40 NTU) were mostly related to maintenance operations conducted on the SIS pipeline. Turbidity often exceeded 100 NTU following these procedures. Over a typical year (1 April 2007 until 31 March 2008) a total of 31 maintenance events were notified (Figure 7.6) resulting in WISAC being isolated from the SIS groundwater supply for durations between 12 hours and 72 hours. During this year, the turbidity of SIS groundwater showed a pattern of gradual increase from approximately 5 NTU to approximately 30 NTU over a period of six months. A reduction of turbidity from 30 NTU to 5 NTU corresponded to when pigging of the major SIS pipe sections was conducted following a six monthly maintenance schedule conducted by SA Water. Daily fluctuations in turbidity were also observed, which are attributed to variations in flow as different bores are turned on and off to optimise SIS operation (Figure 7.7).
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= SIS pipeline system mainteance event notified (Ryan Felder, SA Water) 110
100
90
80
70
60
50 Turbidity (NTU) 40
30
20
10
0 2-Jul-07 1-Jun-07 2-Oct-07 2-Jan-08 1-Apr-07 1-Feb-08 3-Mar-08 3-Apr-08 1-Sep-07 1-Nov-07 2-Dec-07 1-May-07 1-Aug-07 Date
Figure 7.6. Turbidity (NTU) of Woolpunda SIS groundwater used at WISAC and notified pipeline maintenance events from 1 April 2007 until 3 April 2008.
128 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
9 August 2006
15
10
5 Turbidity (NTU) Turbidity
0 12:00 1:00 2:00 3:00 4:00 5:00 6:0 0 7:00 8:00 9:00 10 :0 0 11:00 12:00 1:00 2:00 3:0 0 4:00 5:00 6:00 7:00 8:00 9:0 0 10 :0 0 11:00 AM AM AM AM AM AM AM AM AM AM AM AM PM PM PM PM PM PM PM PM PM PM PM PM Time
Figure 7.7. Turbidity (NTU) of Woolpunda SIS groundwater used at WISAC on 9 August 2006.
7.4.5. Dissolved Carbon Dioxide and pH
The monthly mean concentration of dissolved CO2 in each production tank was elevated (Table 7.1). The maximum monthly mean concentration of dissolved CO2 recorded was 32.6 ± 1.1 mg/L (± SE) and the minimum monthly mean concentration of dissolved CO2 was 8.4 ± 0.3 mg/L (Table 7.1). Dissolved CO2 concentration showed variable and elevated levels that tended to change with fish biomass (Figure 7.8).
Table 7.1. Mean concentration of dissolved CO2 (mg/L, ± SE) in mulloway production tanks at WISAC.
Maximum monthly Minimum monthly Mean dissolved CO2 mean dissolved mean dissolved Production (± SE) CO2 CO2 Mean pH tank (± SE) (± SE) (± SE) G1 24.5 ± 1.5 31.4 ± 1.4 13.9 ± 1.4 7.47 ± 0.03 G2 18.6 ± 1.6 29.6 ± 1.3 8.5 ± 0.4 7.45 ± 0.03 G3 20.0 ± 1.9 32.6 ± 1.1 8.4 ± 0.3 7.58 ± 0.02
Operation of the degassing tower at WISAC decreased the level of dissolved CO2 in incoming SIS groundwater from a mean concentration of 63.4 ± 0.60 mg/L to a mean concentration of 17.5 ± 0.31 mg/L (Figure 7.9) in water entering the header tanks (i.e. post- degassing). This represented a mean reduction in the concentration of dissolved CO2 of 72.7 ± 0.4%.
During degassing, the pH of incoming SIS groundwater increased from an average pre- degassing level of 6.82 ± 0.003 (± SE) to an average post degassing level of 7.63 ± 0.003 (± SE). Compilation of all data from all tanks (Figure 7.10) shows a relationship (R2 = 0.236) in which pH declines as the level of dissolved CO2 increases.
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G1 2,500 Biomass (kg) CO2 Outflow (mg/L) 40
35 2,000 30 ) 1,500 25 20
1,000 15 Biomass (kg 10
500 dioxide (mg/L) Dissolved carbon 5
- 0 May - Jun- Jul-06 Aug- Sep- Oct- Nov - Dec - Jan- Feb- Mar - Apr- May - Jun- Jul-07 Aug- 06 06 06 06 06 06 06 07 07 07 07 07 07 07 G2 Biomass (kg) CO2 Outflow(mg/L) 2,500 40
35 2,000 30 ) 1,500 25 20
1,000 15 Biomass (kg 10 500 5 dioxide (mg/L) Dissolved carbon
- 0 Oct- Nov - Dec - Jan- Feb- Mar - Apr- May - Jun- Jul- Aug- Sep- Oct- Nov - Dec - Jan- Feb- Mar - Apr- 06 06 06 07 07 07 07 07 07 07 07 07 07 07 07 08 08 08 08
G3 Biomass (kg) CO2 Outflow(mg/L)
2,500 40
35 2,000 30 ) 1,500 25 20
1,000 15 Biomass (kg 10
500 dioxide (mg/L) Dissolved carbon 5
0 0 Oct- Nov - Dec - Jan- Feb- Mar - Apr- May - Jun- Jul- Aug- Sep- Oct- Nov - Dec - Jan- Feb- Mar - 06 06 06 07 07 07 07 07 07 07 07 07 07 07 07 08 08 08 Month
Figure 7.8. Monthly mean dissolved carbon dioxide (mg/L ± SE) and biomass (kg) for mulloway production tanks at WISAC.
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Pre-degassing CO2 Post-degassing CO2 140
120
100
80
60
40
Dissolved carbon dioxide (mg/L) dioxide carbon Dissolved 20
0 May - Jul-06 Sep- Nov - Jan-07 Mar-07 May- Jul-07 Sep- Nov- Jan-08 Mar-08 06 06 06 07 07 07 Date
Figure 7.9. Dissolved CO2 concentration (mg/L) of SIS groundwater before (pre) and after (post) passing through a degassing tower installed at WISAC (May 2006 until March 2008).
8. 5
8. 3
8. 1
7. 9 y = -0.1474Ln(x) + 7.8889 7. 7 R 2 = 0.2355 7. 5 pH
7. 3
7. 1
6. 9
6. 7
6. 5 0 102030405060 Dissolved carbon dioxide (mg/L)
Figure 7.10. Relationship between dissolved CO2 and pH from data collected from all production tanks at WISAC between May 2006 and March 2008.
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7.4.6. Water Use While production tanks were stocked between October 2006 and March 2008. the mean daily use of SIS groundwater at WISAC ranged from 782.1 ± 38.1 KL/day (± SE) to 1,635.0 ± 67.4 KL/day. During this period, the total mulloway biomass ranged from 1,088 kg to 4,364kg (Figure 7.12). The mean daily water usage was greatest during 2007 while all production tanks were stocked (Table 7.2) and equated to only 4.25% of the approximately 30 million litres per day available from the SISs in the region.
Total biomass Water use (KL/day) 5,000 1,800
4,500 1,600
4,000 1,400 3,500 1,200 3,000 1,000 2,500 800 2,000 600 Total biomass(kg) 1,500 use (KL/day) Water
1,000 400
500 200
0 0 Oct- N D Jan- Feb- Mar- Apr- Jun- Jul- A S Oct- N D Jan- Feb- Mar- 06 ov- ec- 07 07 07 07 07 07 ug- ep- 07 ov- ec- 08 08 08 06 06 07 07 07 07 Month & Year
Figure 7.11. Monthly mean total SIS groundwater use (kL/day ± SE) and total monthly mulloway biomass (kg) at WISAC while production tanks were stocked between October 2006 and March 2008.
Table 7.2. Summary of SIS groundwater used at WISAC from May 2006 until March 2008.
Mean water use Mean water inflow rate Percentage of total Year (KL/day ± SE) (L/sec ± SE) SIS water 2006 940.1 ± 22.8 10.9 ± 0.3 3.11% 2007 1,285.4 ± 26.0 14.9 ± 0.3 4.25% 2008 805.3 ± 19.9 9.3 ± 0.2 2.66%
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7.4.7. SIS Groundwater Parameters Table 7.3 provides a summary of mean (± SE), maximum and minimum values for water parameters monitored daily for SIS groundwater used at WISAC before and after passage through the packed column degasser and prior to use in the aquaculture system.
Table 7.3. Summary of parameters measured daily for SIS groundwater used at WISAC.
Parameter Mean ± SE Maximum Minimum Salinity (g/L) 20.45 ± 0.01 21.00 19.50 Water temperature (oC) Pre 23.1 ± 0.1 28.8 17.9 Post 23.1 ± 0.1 29.8 15.5 Dissolved CO2 (mg/L) Pre 63.4 ± 0.6 117.0 44.5 Post 17.5 ± 0.3 26.3 6.0 Dissolved oxygen Pre 5.0 ± 0.1 15.0 1.0 (% saturation) Post 89.6 ± 0.4 108.0 60.0 pH Pre 6.82 ± 0.00 7.08 6.54 Post 7.63.1 ± 0.00 7.88 7.31 Total ammonia nitrogen Pre 2.14 ± 0.1 4.39 0.13 (mg/L) Post 2.04 ± 0.06 4.52 0.13 Un-ionised ammonia Pre 0.04 ± 0.00 0.09 0.002 (NH3, mg/L) Post 0.007 ± 0.000 0.014 0.000
7.4.8. Major Operating Costs The major operating costs considered equated to production costs of between $6.36–$8.10/kg for the three tanks of mulloway cultured at WISAC. Feed represented the major operating cost, followed by electricity and then oxygen (Table 7.4).
Table 7.4. Summary of major costs ($/kg) and percentage of costs of production of mulloway cultured in a semi-intensive aquaculture system operated at WISAC between May 2006 and March 2008.
Batch 1: Batch 2: Batch 2: Cost item G1 G2 G3 Mean $/kg $/kg $/kg $/kg (% total cost) (% total cost) (% total cost) (% total cost) Electricity* 2.34 (34.3%) 2.54 (31.4%) 2.50 (28.9%) 2.40 (29.6%) Oxygen** 1.74 (24.5%) 1.56 (19.3%) 1.69 (19.5%) 1.60 (19.8%) Feed*** 2.92 (41.4%) 3.99 (49.3%) 4.48 (51.7%) 3.65 (47.7%) Total cost ($/kg) 7.10 8.10 6.36 7.65
*$0.137/KwH **$1.00/kg ***$1.80/kg
7.5. Discussion Results of this study suggest that a near optimal water temperature range for mulloway was maintained in the production systems at WISAC. However, maintenance of near optimum water temperatures did not translate into the expected higher growth of mulloway. For all production tanks, the growth trajectory of mulloway was essentially linear (Figure 7.1) rather
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than exponential as would be expected for the early growth period of cultured fish (Westers, 2001). Doroudi et al. (2006) reported exponential growth for juvenile mulloway represented by an SGR of 1.15%/day over a 243 day trial in which fish were maintained at 20.0 ± 1.0oC. In this trial, mulloway grew from an initial average weight of 10.8 ± 2.1 g to a final average weight of 270 ± 35 g (± SD). Partridge et al. (2006) reported SGR of 0.68% for mulloway growing from 116 g to 384 g over 174 days in a semi-intensive floating tank system in a pond containing groundwater supplemented to provide a potassium: chloride ratio of 0.016. In this study, the water temperature ranged from 18.4–24.8oC. In comparison, over a period of 187 days, similar size mulloway in production tanks G2 and G3 at WISAC grew from initial average weights of 126.8 ± 18.7 g (± SD) and 117.2 ± 19.7 g respectively, to final average weights of 392.8 ± 74.3 g and 370.7 ± 57.6 g, representing an SGR of 0.60%/day for tank G2 and 0.62%/day for tank G3. This suggests that factors other than water temperature may have affected the growth of mulloway in the culture system at WISAC.
Douroudi et al. (2006) concluded that optimal survival of juvenile mulloway occurred within a salinity range of 15 to 35 g/L. This agrees with previous research which concluded that salinity levels of between 5 g/L and 35 g/L had no significant affect on survival and growth of juvenile mulloway (Fielder and Bardsley, 1999). Salinity of groundwater used at WISAC remained relatively constant (20.45 ± 0.1 g/L ± SE) throughout this study. This salinity is within the range considered to be optimal for growth and survival of mulloway.
Generally, groundwater has a very low concentration of dissolved oxygen and requires aeration or oxygenation before it can be used for aquaculture. The mean concentration of dissolved oxygen in the groundwater from the Woolpunda SIS was 5.0 ± 0.1% saturation (± SE). After passing through the packed column degasser installed at WISAC, the mean concentration of dissolved oxygen was increased to 89.6 ± 0.4% saturation. Apart from during the mortality incident recorded on 24 March 2007, the oxygen monitoring and control system at WISAC generally maintained concentrations between 70–100% saturation. It is not likely that mulloway growth would be adversely impacted within this range of dissolved oxygen concentration as this species appear to be able to adapt to low oxygen environments (Fitzgibbon et al, 2007), and prolonged exposure to low dissolved oxygen conditions (<70% saturation) did not occur.
Turbidity of groundwater supplied to WISAC was variable and was primarily due to planned maintenance procedures that are needed to ensure ongoing efficient operation of the SIS. A good relationship was established between the SIS operators (SA Water) and technical staff located at WISAC so that notification was received of maintenance at least 24 hours before commencement. During planned maintenance procedures, WISAC was isolated from the SIS groundwater supply for between 12 and 72 hours during which time the culture systems were operated using reused SIS groundwater, a reduced exchange of stored SIS groundwater and feeding was either stopped or restricted.
The high level of dissolved CO2 in all production tanks was the major water quality parameter of concern at WISAC during this study. Elevated dissolved CO2 was present in both the SIS groundwater supply and the production systems at WISAC. Installation of the degassing system for incoming SIS groundwater at WISAC allowed the level of dissolved CO2 to be reduced significantly from a mean of 63.4 ± 0.6 mgCO2/L (± SE) before degassing
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to 17.5 ± 0.3 mg CO2/L after degassing. Data from all production tanks at WISAC identify that the total mean level of dissolved CO2 during the period of mulloway culture was greater than 18 mg/L in all tanks. These high levels of dissolved CO2 are thought to be a major factor contributing to the poor growth performance of mulloway in the semi-intensive culture systems at WISAC, and have subsequently been investigated in a trial conducted at WISAC (Chapter 8).
Elevated levels of dissolved CO2 are common with intensive aquaculture systems due to intensive feeding practices with a corresponding increase in CO2 production due to respiration of fish. This was observed in production tanks at WISAC as dissolved CO2 tended to vary in relation to mulloway biomass. One physiological factor contributing to reduction in growth performance at elevated levels of dissolved CO2 is the Bohr effect that is linked to the chemistry of the haemoglobin molecule in the blood. Finfish haemoglobin is known to be very sensitive to CO2 compared to mammals (Ferguson, 1988). As acidity increases, the oxygen binding affinity of haemoglobin decreases (the Bohr effect). In normal conditions, the Bohr effect facilitates release of oxygen in tissues where CO2 production, due to respiration, has lead to increased acidity. In aquaculture systems where there is a build up of dissolved CO2 the Bohr effect may reduce the uptake of oxygen by haemoglobin at the gills making it increasingly difficult for finfish to transport oxygen even when adequate amounts are available.
Timmons et al. (2002) report that tilapia and striped bass show no adverse effects at dissolved CO2 concentration as high as 60 mg/L, and that a safe range for trout is between 9 mg/L and 30 mg/L. Westers (2001) suggests that fish may be able to acclimate to CO2 levels as high as 60 mg/L, and reports that Coho salmon (Oncorhynchus kisutch) cultured at 21 oC show no adverse effects at dissolved CO2 concentrations up to 40 mg/L. For coldwater species such as salmonids, adverse affects of dissolved CO2 occur at levels of 20 mg/L and it is suggested that this level should not be exceeded in intensive fish culture (Wedemeyer, 1996). Fivelstad et al. (2003) reported a significant difference (P<0.05) in length and a significant reduction in condition for Atlantic salmon (Salmo salar) smolts cultured for 38 days in freshwater with 1.8 mg CO2/L and 9.3 mg CO2/L. SGR over this period was 0.26% for control fish (1.8 mg CO2/L) and only 0.06% for finfish cultured in water containing 9.3 mg CO2/L.
It is likely that the oxygenation method and low turbulence used in the semi-intensive tanks supporting a moderate stocking density contribute to the elevated levels of CO2 through minimising opportunities for gas exchange. The low turbulence and use of oxygenation within production tanks was designed to minimise loss of heat from incoming ‘new’ SIS water to maintain water temperature at optimal levels during winter when night-time ambient air temperatures can be as low as –5oC; and during summer when ambient air temperatures are regularly in excess of 40oC. An alternative approach that could be considered for this system would be the use of vigorous aeration devices such as paddlewheels (Figure 7.12) to maintain dissolved oxygen and achieve degassing of dissolved CO2. However, it is expected that operation of aeration devices will impact upon the temperature (range and stability) of culture water and that this is undesirable for maintaining the optimal water temperatures characteristic of this SIS groundwater. Further reduction in dissolved CO2 may be achieved through installation of additional degassing of incoming SIS water to achieve greater than the
135 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
72.7% reduction that was reached. In addition, efficient degassing of reused SIS water could also be considered.
Figure 7.12. Paddlewheel in use in a semi-intensive production tank for European seabream (Sparus aurata) in Israel.
The major costs for production were feed, electricity and oxygen. When all batches of mulloway are combined, feed was the largest production cost representing 47.7% of the total costs considered. This cost is affected by the relatively high FCRs for mulloway cultured at WISAC, and there is potential to reduce feed costs by improving FCR. For example, if FCR of the lowest cost batch of fish initially cultured in production tank G3 could be reduced to 1.2 then the total cost of production would fall to 5.26/kg with the proportion attributed to feed reducing to 41.6%.
Electricity is also a significant cost, representing 29.6% of the combined batches production costs. This is primarily due to the high proportion of SIS groundwater used and the need to pump this water back into the SIS pipeline against a head pressure of approximately 16m. Electricity cost could be significantly cut by reducing the amount of SIS groundwater used that subsequently requires pumping back into the SIS pipeline. This could be achieved through adoption of more intensive aquaculture systems that incorporate biological and mechanical filtration to allow greater reuse of water and reduce the amount of water that is exchanged daily through these systems. The location selected for WISAC was done in an expedient manner due to the time available for this project. A more ideal location for a commercial aquaculture facility would allow discharge of exchange water without the need for pumping, or to allow pumping against a reduced head pressure. This may be available at a location closer to the disposal basin where topography may allow an aquaculture operator to achieve gravity flow of discharged water while taking advantage of incoming water being supplied under pressure from the SIS pipeline.
The cost of fingerlings has not been included in this analysis as currently the supply is limited and variable. SARDI has successfully completed larval rearing of mulloway on a number of occasions producing up to 400,000 fingerlings in a single run. Experience gained suggests
136 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
that the degree of technical difficulty and the growth and survival of mulloway fingerlings is comparable to barramundi. This indicates that it should be possible to commercially produce mulloway fingerlings and sell these at a cost similar to that of barramundi fingerlings. For over a decade, commercial hatcheries across Australia have supplied barramundi fingerlings to on-growing operations at a cost of approximately $0.01 per mm (e.g. $0.50 for a 50 mm fingerling).
Oxygen represented 19.8% of the production costs considered for all batches combined. Oxygenation was adopted at WISAC in order to minimise turbulence to optimise the retention of water temperature and reduce the amount of water supplied to tanks in order to maintain adequate levels of dissolved oxygen. Oxygenation also provided a reliable supply to mange risks associated with culture of fish at elevated stocking densities. More efficient systems for achieving oxygen transfer should be considered for a commercial scale aquaculture system. However, the approach adopted will also need to consider the need to manage dissolved CO2.
7.6. Conclusions and Recommendations From the data presented. it is considered that the opportunity provided by saline groundwater available from the Woolpunda SIS is being limited by the elevated levels of dissolved CO2 characteristic of this same water, as well as an increase in the concentration of dissolved CO2 occurring because of the culture system’s design and manner of operation. A trial subsequently undertaken on the affect of elevated levels of dissolved CO2 on growth and survival of mulloway has identified the contribution of this parameter to the poor growth performance of mulloway at WISAC (Chapter 8).
It is recommended that further investigation needs to be conducted to evaluate technological approaches to achieve greater reduction of dissolved CO2 in incoming SIS groundwater and to achieve ongoing reduction of dissolved CO2 within systems. An analysis of the costs (i.e. loss of water temperature) and benefits (i.e. improved oxygen transfer efficiency and reduction of dissolved CO2) from available technologies should be undertaken to optimise management of both dissolved oxygen and dissolved CO2 within aquaculture systems designed to utilise SIS groundwater. Until this issue is resolved, the potential growth performance of mulloway in the available SIS groundwater is unlikely to be fully realised.
It is suggested that a modern, energy efficient intensive aquaculture system could address the issues identified, as these systems should incorporate water treatment components capable of managing the issues identified, including:
• dissolved CO2 • efficient oxygenation (contact vessels) • thermal insulation • low head design to minimise energy use • low water exchange to optimise production and reduce volume of waste water for disposal.
137 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
7.7. References American Public Health Association. 2005. Standard methods for the examination of water and wastewater. prepared and published jointly by American Public Health Association, American Water Works Association and Water Environment Federation. 21st ed. Washington, D. C. APHA-AWWA-WEF. Doroudi, M.S., Fielder, D.S., Allan, G.L. and Webster, G.K. 2006. Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Aquaculture Research 37: 1034–1039. Ferguson, H. 1988. Water quality diseases. In: Fish Diseases. Proceedings, refresher course for veterinarians, 23–27 May. Post Graduate Committee in Veterinary Science, University of Sydney, pp. 49–56. Fielder, D.S. and Bardsley, W.J. 1999. A preliminary study on the effects of salinity on growth and survival of juvenile mulloway Argyrosomus japonicus larvae and juveniles. Journal of World Aquaculture Society 30: 380–387 Fitzgibbon, Q.P., Strawbridge, A. and Seymour, R.S. 2007. Metabolic scope, swimming performance and the effects of hypoxia in the mulloway, Argyrosomus japonicus (Pisces: Sciaenidae) Aquaculture 270: 358–368. Fivelstad, S., Waagbø, R., Zeitz, S.F., Hosfeld, A.C.D., Olsen, A.B. and Stefansson, S. 2003. A major water quality problem in smolt farms: Combined effects of carbon dioxide, reduced pH and aluminium on Atlantic salmon (Salmo salar L.) smolts: Physiology and growth. Aquaculture 215: 339–357. Needham, D.J. 1988. Anaesthesia and surgery. In: Fish Diseases. Proceedings, refresher course for veterinarians, 23–27 May. Post Graduate Committee in Veterinary Science, University of Sydney, pp. 513–529. Partridge, G.J., Sarre, G.A., Ginbey, B.M., Kay, G.D. and Jenkins, G.I. 2006. Finfish production in a static, inland saline water body using a Semi-Intensive Floating Tank System (SIFTS). Aquaculture Engineering 35: 109–121. Timmons, M.B., Ebeling, J.M, Wheaton, F.W., Summerfelt, S.T. and Vinci, B.J. 2002. Recirculating aquaculture systems (2nd Ed.). Northern Regional Aquaculture Centre Publication No. 01-002. Cayuga Aqua Ventures, Ithaca, NY, p. 786. Tucker, C.S. 1984. Carbon Dioxide. In: Wellbourne T.L. Jr and Mac Millan, J.R. (Editors). For Fish Farmers 84–2. Mississippi Co-operative Extension Service. Wedemeyer, G.A. 1996. Physiology of fish in intensive culture systems. Chapman and Hall, New York. Westers, H. 2001. Production. In: Wedemeyer G.A. (Editor) Fish hatchery management, 2nd Ed. American Fisheries Society, Bethesda, Maryland, USA, pp. 31–90. Wurts, W.A. and Durborow, R.M. 1992. Interactions of pH, carbon dioxide, alkalinity and hardness in fish ponds. Southern Regional Aquaculture Centre, Publication No. 464. pp.4.
138 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
Appendix 7.1. Method for determination of dissolved CO2 (mg/L) by titration (American Public Health Association, 2005).
• Water sample should be obtained mid-stream or under water in a manner to cause minimal splashing of the sample. This can cause a change in dissolved gasses, including CO2. • Fill the burette in the lab with 0.0227 M solution of anhydrous sodium carbonate (2.406 g Na2CO3/L) (the titrant) from the 1 L flask remembering to open the valve to get all the air out of the bottom before starting. • Record the level of the titrant in the burette prior to titration. • Measure 50 mL of the sample solution into the smaller flask, taking care to avoid splashing by running it down the side of the flask. • Place the pH probe into the test solution • While gently swirling the sample flask, slowly drip the titrant from the burette into the sample until a pH of 8.3 is achieved, taking care not to go over a pH of 8.3. • Record the new level of the titrant and calculate the difference between initial and final level.
• Calculate the CO2 using the following formula:
(ml titrant x 0.0227 x 44,000) ÷ 50 = CO2 mg/L
139 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
Appendix 7.2. Factors for calculating dissolved CO2 concentrations in water with known pH, temperature and alkalinity (from Tucker, 1984 in Wurts and Durborow, 1992).
140 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
Appendix 7.3. Portable meter purchased to measure dissolved CO2 in saline groundwater at WISAC (www.oxyguard.dk).
141 Chapter 7 – Performance of a proof of concept semi-intensive aquaculture system for culture of mulloway at WISAC
Appendix 7.4. Comparison of dissolved CO2 concentration (mg/L) measured by titration and using a portable CO2 meter (Oxyguard® CO2 Portable).
Titration CO2CO2 Oxyguard CO2CO2 23.0 4.0 29.0 7.0 36.0 10.0 42.5 13.0 48.8 17.0 57.0 22.0 68.3 27.0 82.0 36.0 102.4 53.0
60.0 y = 0.0242x1.6697 R2 = 0.9936 50.0
40.0 by meter by 2 30.0 CO
20.0 Dissolved
10.0
0.0 0.0 20.0 40.0 60.0 80.0 100.0 120.0
Dissolve d CO2 by titration
142 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
8.1. Summary The Waikerie Inland Saline Aquaculture Centre (WISAC) has been developed to demonstrate the suitability of SIS groundwater for potential commercial aquaculture production. The euryhaline finfish mulloway, Argyrosomus japonicus, has been the focus of investigations.
Since commencing operations at WISAC the SIS groundwater has been found to contain inherently high concentrations of dissolved carbon dioxide (CO2), with typical levels averaging 61.6 mg/L between 18 August and 30 September 2007. Excessively high
concentrations of dissolved CO2 levels in water may cause a serious problem for fish health and growth performance. Therefore, in an attempt to investigate the effects of high levels of dissolved CO2 on mulloway we designed and constructed an experimental system at the WISAC site. This was done with the specific aim to compare the growth performance and survival of mulloway held in inland saline culture water with increasing concentrations of dissolved CO2 ranging from 0 mg/L to 80 mg/L. Fish were cultured for 54 days from 5 September to 29 October 2007.
Results from the trial have demonstrated that growth performance and ultimately survival of mulloway is impacted by the high levels of dissolved CO2 found in the SIS groundwater supply used at WISAC, even after primary degassing (dissolved CO2 10.7 mg/L). Although this trial was carried out under experimental conditions the observed growth and survival trends indicate that performance of mulloway is superior when levels of dissolved CO2 are maintained at the lowest concentration evaluated, 6 mg/L. There is also a clear relationship between increasing concentration of dissolved CO2 and decreasing pH that may be a factor contributing to the reduced growth of finfish at increasingly high levels of dissolved CO2.
The relationship between the concentration of dissolved CO2, pH and finfish growth requires more detailed physiological and biochemical investigation to explain the mechanisms that are operating in mulloway and other potential aquaculture species that might be cultured in SIS groundwater.
8.2. Background Since commencing investigations at WISAC the SIS groundwater has been found to contain inherently high concentrations of dissolved CO2, with typical levels averaging 61.6 ± 10.7 mg/L (mean ± SE) between 18 August and 30 September 2007. Excessively high concentrations of dissolved CO2 levels in water may lead to increased CO2 partial pressures in the fish’s blood and cause serious problems with respiratory physiology, health and growth. As the removal of CO2 from the fish’s blood to the water relies on passive diffusion across a negative gradient (typically 2:1 ratio) at the surface of the gills, the ability of the fish to
143 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
remove CO2 from the blood is impaired (Fromm, 1980). This in turn, leads to increased blood CO2 levels and partial pressures, or a condition referred to as hypercapnia (Fromm, 1980; Michaelidis et al., 2007). In the short term this condition may be alleviated by the buffering capacity of the blood bicarbonate ion system (Fromm, 1980). However, once the threshold for this system is exceeded, hypercapnia reduces the pH level of the blood dramatically, and results in a condition referred to as acidosis, which in turn leads to a reduction in the blood’s ability to carry oxygen; conditions referred to as the “Root and Bohr effects” (Alabaster et al., 1957; Fromm, 1980). Ultimately, if left unattended, these conditions are deleterious to fish health and growth performance (Fromm, 1980; Fivelstad et al., 1998, 2003, 2007; Michaelidis et al., 2007; Sullivan et al., 2007). Consequently, to achieve maximum growth finfish must be cultured in water that is low in dissolved CO2.
The establishment of reliable dissolved CO2 concentrations for optimum growth is complicated. Carbon dioxide tolerance limits may be species and size dependent. Additionally tolerance limits may also be affected by a combination of water quality parameters including, but not restricted to, dissolved oxygen levels, temperature, pH, water hardness and dissolved metals (Alabaster et al., 1957; Wurts and Durborow, 1992; Fivelstad et al., 2003). For example, the mortality rate of rainbow trout, Oncorhynchus mykiss, at a constant dissolved CO2 level was reported to be reduced by increasing dissolved oxygen concentration in conjunction with decreasing water temperature (Alabaster et al., 1957). Timmons et al. (2002) recommended an upper limit of 15–20 mg/L of dissolved CO2 as a steady state maximum to support optimum finfish health and growth. However, after reviewing the literature it appears this recommendation has been inadequately researched. A more realistic recommendation for dissolved CO2 levels for optimum finfish health and growth for a range of species of fish appears to be <10 mg/L (Wedemeyer, 1996; Fivelstad et al., 1998, 2003, 2007). Additionally, and as a general guideline, dissolved CO2 concentrations ranging from 15 to 30 mg/L may induce sub-lethal effects including respiratory stress, the development of kidney stones, and a reduction in growth performance in some species, while levels exceeding 30 mg/L may be lethal to many species when combined with prolonged exposure (Wedemeyer, 1996; Fivelstad et al., 1998, 2003, 2007).
There is limited scientific information to support the recommended range of dissolved CO2 levels for marine finfish, and none could be found that specifically describe toxic CO2 levels for mulloway. In response to this issue, SARDI installed a packed column degasser to reduce the level of CO2 in incoming SIS groundwater used at WISAC.
Consideration was given to the type of CO2 degassing system used at WISAC. After reviewing the literature it became apparent that the two most common systems for the removal of dissolved CO2 from water are packed column degassing and vacuum degassing (Colt, 1986; Spotte, 1992). The operating principle of each system is described.
In a packed column degassing system, untreated water is distributed over a column packed with plastic media. The water cascades through the column by gravity. When the water flows over the media, water surface area is increased and as a result surface tension is reduced allowing the transfer of excess gases from the water to the atmosphere (Colt, 1986). The passage of water through this system may be solely by gravity making it power efficient. The
144 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
efficiency of this process is further increased when a high volume counter current of air is directed up through the packed column against the flow of water.
For vacuum degassing, water is pumped into a sealed vessel which is packed with plastic media to increase the surface area. The sealed container is then exposed to a vacuum which results in a negative pressure differential between the water and air. Gasses in the water rapidly diffuse across the pressure differential from the water to the air. The vacuum is maintained within the vessel by a pump and as the treated water is under vacuum it must be pumped out (Spotte, 1992). The operation of this system relies upon the use of several pumps and is therefore, costly to operate. An additional disadvantage of the vacuum degassing system is it also reduces the level of dissolved oxygen in the water (Colt, 1986).
Packed column degassing was chosen for installation at WISAC because of the simplicity of design, construction and cost of operation. Additionally, the packed column degassing system has the advantage of increasing the level of dissolved oxygen in the incoming SIS groundwater.
The packed column degassing system installed at WISAC reduced the CO2 levels of the incoming water to an average of 10.7 ± 1.8 mg/L after which it was held in two storage tanks before it was used to culture finfish. However, after referring to the literature, even at this reduced level of dissolved CO2, there was concern that growth of mulloway may have still been inhibited. Therefore, we designed and constructed an experimental system at the WISAC site to compare the growth performance and survival of mulloway held in inland saline culture water with increasing concentrations of dissolved CO2 ranging from 0 mg/L to 80 mg/L.
8.3. Methods
8.3.1. Carbon Dioxide Levels
We investigated the effects of six nominal level of dissolved CO2 on the growth and survival of mulloway cultured in inland saline water in experimental tanks at WISAC. The concentrations were 0(6), 10, 20, 40, 60 and 80 mg dissolved CO2/L. These levels of dissolved CO2 were chosen to investigate the range that had the minimum impact on growth and survival of mulloway. The levels of 60 mg CO2/L and 80 mg CO2/L were also chosen as they reflect the upper range of CO2 concentration of the untreated SIS groundwater. Unfortunately, due to limitations of the experimental system it was not possible to maintain the chosen nominal level of dissolved CO2 for the 0 mg CO2/L treatment. The experimental system was not able to completely remove all of the dissolved CO2 from the incoming water supply; consequently the chosen nominal concentration of 0 mg CO2/L was measured to be 6 mg CO2/L (Table 9.1).
145 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
8.3.2. Experimental System Work conducted at the SARDI Aquatic Sciences Centre prior to the commencement of the experiment at WISAC identified a system that controlled the flow of water and compressed CO2 to the experimental tanks resulting in concentrations as close as possible to the target levels. After a series of trials using degassing towers, venturis, flow meters and diffusers to obtain appropriate dissolved CO2 concentrations, a simple system was utilised to provide a water flow of 200 litres (one tank exchange) per hour while CO2 flow was regulated by single tube glass flow meters and precision metering valves set in a manifold (Dakota Instruments, Inc., Orangeburg, New York, USA).
The trial was conducted at WISAC where a dedicated experimental system was constructed (Figures 9.1 & 9.2). This system was designed to enable the desired treatment levels of dissolved CO2 to be maintained in each of the three replicate 200 L finfish culture tanks for each of the six treatment levels. A schematic diagram of the system is displayed in Figure 9.1. In order of operation the system was comprised of the SIS groundwater supply, a primary degassing tower (5,200 L tank containing 4 m3 of media) utilising a counter current airflow with a 370 watt, 315 mm tube axial fan (MRE Industries, Thebarton, South Australia, Australia), a 4,500 L reservoir tank, a secondary de-gassing tower with a 200 watt, 225 mm tube axial fan (ebm-papst Mulfingen GmbH & Company KG, Mulfingen, Germany) and a 3 700 L tank containing 0.65 m of media, six 200 L CO2 mixing tanks, a CO2 cylinder (G- sized cylinder; 86 kg, Air Liquide Australia Ltd., Melbourne, Victoria, Australia), CO2 manifolds, and 18 x 200 L finfish culture tanks. The three finfish culture tanks for each treatment were randomly situated within two rows of nine tanks.
To achieve the desired dissolved CO2 levels in the experimental system the incoming untreated SIS water was pumped through to the primary degassing tower and then to the reservoir tank. The primary degassing tower is part of the existing water treatment system at WISAC and delivers water with dissolved CO2 level of 10.7 ± 1.8 mg/L to the reservoir. To further reduce the CO2 levels of the supply water, the water from the reservoir tank is continually pumped to the secondary degassing tower and then returns by gravity back to the reservoir tank. By doing this we were able to maintain minimum mean dissolved CO2 levels of 6.03 ± 0.62 mg/L. Degassed water from the reservoir tank was introduced into CO2 contact chamber, where the required amount of CO2 was supplied via the CO2 manifold comprised of five flow meters (one dedicated to each CO2 contact chamber) to achieve the desired dissolved CO2 concentration for each treatment. Water containing the required concentration of CO2 flowed by gravity from the CO2 contact chamber to each of the three replicate tanks for each dissolved CO2 treatment.
8.3.3. Fish and Experimental Procedures Mulloway used in this study were spawned and cultured at the R&D Finfish Hatchery at SARDI, West Beach, Adelaide, and then transferred to WISAC. They were then cultured in primarily degassed saline (20.5 g/L) groundwater at WISAC for 12 weeks prior to the commencement of the trial. Each experimental tank was stocked with 25 mulloway fingerlings that weighed 62.83 ± 2.93 g and measured 72.59 ± 2.42 mm in total length. There
146 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
was no significant difference in the initial weight (P = 0.450) or length (P = 0.334) of mulloway between treatments at stocking.
Fish were allowed to acclimate to the finfish culture tanks for a day at the lowest nominal level of 6 mg CO2/L. Then the nominal dissolved CO2 concentrations for each treatment were established as follows; 10 and 20 mg CO2/L treatments were achieved after 2 days, 40 mg CO2/L treatment after 5 days, and finally the 60 and 80 mg CO2/L treatments were achieved after 6 days, following 3 days at 40 mg/L. The CO2 concentrations of each treatment were then measured and adjusted daily and maintained until the completion of the trial (Figure 9.3). Water flow rate to each culture tank was set at 200 L/hr and provided a water exchange rate of ~100% per hour. The dissolved oxygen level of the culture water was maintained with compressed oxygen using fine diffusers in the 4,500 L reservoir tank. This approach was taken to minimise and standardise the loss of dissolved CO2 from each finfish culture tank due to oxygenation. Mulloway were fed twice a day at a feed rate of 2% body weight per day with a 4 mm pellet closed formula commercial diet containing approximately 55% crude protein and 22% crude lipid (Nova ME, Skretting, Cambridge, Tasmania, Australia). Mortalities were recorded daily. Tanks were cleaned twice per week. Fish from each tank for each treatment were weighed and measured on days 0 (5 September 2007), 30 (4 October 2007) and 54 (29 October 2007), after which time the experiment was discontinued due to high mortalities caused by a plumbing malfunction.
SIS water 5.5.2 m3 primary supply degassing tower
O2 cylinder and regulator 4500 -L 0.7 m3 secondary Reservoir degassing tower tank
CO 2 cylinder 200-L CO 2 & 6 mg/L 10 mg/L 20 mg/L 40 mg/L 60 mg/L 80 mg/L contact manifold CO2 CO2 CO2 CO2 CO2 CO2 tanks
= Water
= CO 2 3 replicate 200-L fish culture tanks/treatment = O Figure 1. 2
Figure 8.1. Schematic diagram of the experimental system used to conduct the dissolved CO2 trial with mulloway at WISAC.
147 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
Secondary degassing Secondary tower CO cylinder & degassing CO cylinder2 2flow meters tower and flow meters
ReservoirReservoirReservoir tanktank
CO2 contact CO 2 contact chamberschambers
ExperimentalExperimental 200 L fish 200culture -L fish tanks culture tanks
Figure 8.2. Picture of the experimental system used to conduct the dissolved CO2 trial with mulloway at WISAC.
8.3.4. Water Quality
An OxyGuard™ Portable CO2 meter (OxyGuard International A/S, Birkerød, Denmark) was used to measure the concentration of dissolved CO2 in the contact chambers and each fish culture tank. Dissolved CO2 was measured and adjusted daily. This meter was chosen as it determines the concentration of dissolved CO2 directly by detecting the partial pressure of free dissolved CO2 and is not based on a pH measurement and is also not affected by carbonates or other dissolved interfering substances. The pH was measured daily using a WTW 340I pH conductivity meter (Wissenschaftlich-Technische Werkstätten, Weilheim, Germany), as was the water temperature and dissolved oxygen levels using a OxyGuardTM Handygamma dissolved oxygen meter (Water Management Technologies, Baton Rouge, LA, USA; OxyGuard International A/S, Birkerød, Denmark).
148 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
8.3.5. Calculation of Performance Indices Performance indices were calculated for each tank for each treatment using the following formulae:
• Weight gain (g/fish) = final weight – initial weight
• Specific growth rate (SGR, % body weight/day) = (ln final weight – ln initial weight) / days grown x 100
• Fulton’s Condition index (CI) = weight (g/fish)/length (mm)3 x 100,000 (Bagenal & Tesch, 1978).
8.3.6. Statistical Analysis
Data for fish grown at dissolved CO2 concentrations exceeding the nominal level of 40 mg/L were excluded from statistical analyses due to total mortality for these treatments. Additionally, the values for finfish from one of the replicate tanks for the 6 mg/L CO2 treatment at day 54 was also excluded from the analyses due to high mortality caused by a system fault.
Data for total weight, weight gain, total length and condition index were tested to satisfy the requirements for normality and homogeneity of variances using the Kolmogorov-Smirnov Test and the Levene’s test of equality of error variances, respectively. Data for these indices were then analysed using two-factor ANOVA for repeated measures. The first factor was dissolved carbon dioxide concentration (Nominal concentration: 6, 10, 20 and 40 mg/L) and the second factor was grow-out time—0 (5 September 2007), 30 (4 October 2007) and 54 (29 October 2007) days grow-out. Significant interactions were observed between the two factors for all indices; therefore, one-factor ANOVA was used to determine significant effects on each index due to treatment. A significance level of P<0.05 was used. The mean of three replicate tanks were considered units of observation for statistical analysis. Student Newman- Kuels (SNK) test was used to identify significant differences among multiple treatment means. All statistical analyses were done using SPSS, Version 16.0.1 for Windows (SPSS Inc., Chicago, IL, USA). Unless otherwise stated all values are reported as means ± standard error of the mean.
8.4. Results
8.4.1. Water Quality
Actual dissolved CO2 concentrations were monitored daily (Figure 9.3) and the overall treatment average concentrations of dissolved CO2 for the trial calculated (Table 9.1). The CO2 levels for treatments were close to the chosen nominal values, however, they fluctuated slightly throughout the study. These fluctuations were more dramatic in the first two weeks of the experiment.
149 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
6 mg/L 10 mg/L 20 mg/l 40 mg/L 60 mg/L 80 mg/L 80
70
60
50
40
30
20 Dissolved carbon dioxide (mg/L) (mg/L) dioxide carbon Dissolved 10
0 0 7 14 21 28 35 42 49 56 Day
Figure 8.3. Average concentration of dissolved CO2 (mg/L) in each experimental treatment.
The pH of the experimental water varied with the concentration of dissolved CO2. In the experimental tanks there was an inverse relationship between pH values and concentrations of dissolved CO2 (Figure 9.4, Table 9.1).
Table 8.1. The nominal and actual average concentrations of dissolved CO2 (mg/L), and pH for the experimental treatments1
Nominal CO2 Actual CO2 pH (mg/L) (mg/L)
6 6.03 ± 0.62 7.69 ± 0.05 10 11.28 ± 0.87 7.48 ± 0.05 20 22.03 ± 2.28 7.23 ± 0.06 40 38.83 ± 2.88 6.92 ± 0.05 60 54.60 ± 2.91 NA 80 75.00 NA
Values are means ± SEM for three experimental fish culture tanks for each treatment.
150 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
6 mg/L 10 mg/L 20 mg/l 40 mg/L
9.0
8.5
8.0
pH 7.5
7.0
6.5
6.0 0 7 14 21 28 35 42 49 56
Day Figure 8.4. Average pH in the experimental treatments during the trial.
Throughout the trial the average dissolved oxygen saturation level was 95.8%. However, this level varied considerably during the study and ranged from 63–171% until the 26 October when levels were reduced considerably thereafter due to a plumbing problem (Figure 9.5). The average dissolved oxygen concentrations were 7.1 mg/L, and levels always remained above a minimum of 5 mg/L throughout the trial.
6 mg/L 10 mg/L 20 mg/L 40 mg/L 60 mg/L 80 mg/L
180
160
140
120
100
80
60
40
20 Dissolved oxygen (% saturation) (% oxygen Dissolved 0 0 7 14 21 28 35 42 49 56 Day Figure 8.5. Average dissolved oxygen saturation level (%) in experimental tanks during the trial.
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Water temperature during the trial varied between 18–24 oC (Figure 9.6), and the variations experienced were similar for all treatments. 6 mg/L 10 mg/L 20 mg/l 40 mg/L 60 mg/L 80 mg/L
26
25
24
23
22
21
20
Water temperature (°C) 19
18
17 0 7 14 21 28 35 42 49 56 Day Figure 8.6. Average water temperature (°C) in experimental tanks during the trial.
8.4.2. Mortality
Mortality of mulloway commenced during the start-up phase of the trial as the dissolved CO2 concentration of each treatment was established (Figure 9.7). By the third day of the experiment, finfish in the tanks with the nominal concentration of 80 mg CO2/L (44 mg CO2/L at the time) appeared disoriented. Mortality commenced on the morning of day 6 (one fish) for the 80 mg CO2/L treatment (CO2 at 42 mg/L at this time). The dissolved CO2 concentration of the 80 mg CO2/L treatment had been increased to 75 mg/L by day 7 and at this time 53 mortalities, or 72% of the total treatment fish number, were observed across the three treatment tanks. At this point the nominal 80 mg CO2/L treatment was discontinued.
Mortalities occurred on day nine in nominal 60 mg CO2/L treatment tanks when the dissolved CO2 levels were at 60 mg/L (12 mortalities) and continued on days 10 (5 mortalities), 11 (4 mortalities), 12 (7 mortalities) and 13 (22 mortalities). By this time 67% of the fish originally stocked in nominal 60 mg CO2/L treatment tanks had died and the treatment was discontinued. Mortalities commenced in the nominal 40 mg CO2/L treatment tanks after 38 days (4 mortalities). Eleven fish died on day 49 and another fish died on day 50.
Mortalities also occurred in one of the replicate tanks in the nominal 6 mg CO2/L treatment with 8 fish dying on day 39 and a further 3 fish dying on day 50. These mortalities were not attributed to excessive levels of dissolved CO2. Technicians reported disruptions to the water supply to this tank leading to extremely low levels of dissolved oxygen. Consequently, data
152 Chapter 8 – Preliminary evaluation of the effects of dissolved carbon dioxide on growth and survival of mulloway, Argyrosomus japonicus
from this replicate tank was not included in analysis as it was considered to be confounded in relation to performance of fish and mortality.
6 mg/L 10 mg/L 20 mg/L 40 mg/L 60 mg/L 80 mg/L
60
50
40
30
20 Number of mortalities
10
0 0 7 14 21 28 35 42 49 56 Day Figure 8.7. The total number of mortalities recorded for each treatment during the trial.
8.4.3. Growth Performance Fish were cultured for 54 days from 5 September 2007 to 29 October 2007. During this period fish were fed twice a day at a feed rate of 2% body weight/day with a commercial diet. Due to the design of the experimental fish culture tanks and the bottom feeding habit of mulloway, it was not possible to observe feeding behaviour. Therefore, it was not possible to visually determine if increasing concentrations of dissolved CO2 reduced feed intake. As such, it was not possible to determine reliable feed conversion or efficiency data.
The results indicate that dissolved CO2 concentration (6>10 = 20>40 mg CO2/L) had a significant effect on total weight (Table 9.2; P<0.05; two-factor ANOVA), while grow-out time did not (P>0.05). However, there was also a significant interaction between the two factors (P<0.05; Table 9.2). The interaction indicates that total weight was not affected equally between 0, 30 and 54 days by differing CO2 concentrations. For the mulloway exposed to the nominal level of 6 mg CO2/L, total weight progressively increased throughout the trial and a significant increase in total weight was observed after 54 days (Figure 9.8; Table 9.3; one-factor ANOVA). Whereas, finfish exposed to the nominal levels of 10 and 20 mg CO2/L did not exhibit a significant increase in total weight throughout the trial. In contrast, there was a significant reduction in total weight of mulloway exposed to the CO2 concentration of 40 mg/L at 30 and 54 days.
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Results recorded for weight gain followed the same trend as reported for total weight (Tables 9.2 and 9.3; Figure 9.8). Weight gain was significantly reduced due to increasing dissolved CO2 concentration, and also significantly increased with increasing grow-out time (two-factor ANOVA; P<0.05; Table 9.2). There was also a significant interaction between the two factors. The interaction is explained by the observation that the finfish exposed to a nominal level of 6 mg CO2/L were the only fish to exhibit a statistically significant increase in weight gain throughout the trial (P<0.05; one-factor ANOVA; Table 9.3). Whereas, fish exposed to 10 and 20 mg CO2/L exhibited numerical increases in weight gain, while the fish exposed to the level of 40 mg CO2/L displayed a numerical reduction in weight gain that was statistically lower than observed in all other treatments. The results for SGR followed the same trend as weight gains (Tables 9.2 and 9.3).
The total length of fish was significantly affected by dissolved CO2 concentration and also by grow-out time (two-factor ANOVA; P<0.05; Table 9.2). There was also a significant interaction between the two factors. The interaction between CO2 concentration and grow-out time for total length may be explained by differences in finfish growth, in terms of length, due to increasing CO2 concentration (Table 9.3; Figure 9.9). Fish exposed to levels of CO2 up to 20 mg/L progressively increased in length at days 30 and 54, while the length of the fish exposed to 40 mg CO2/L remained statistically similar to the initial length throughout the trial.
The condition index (CI) of fish was significantly affected by dissolved CO2 concentration and grow-out time (two-factor ANOVA; P<0.05; Table 9.2). There was also a significant interaction between the two factors. Again the interaction is explained by differences in response of the fish exposed to CO2 concentrations of >20 mg/L (Table 9.3; Figure 9.10). The CI values for the treatments with CO2 concentrations of up to 20 mg/L significantly decreased after 30 days, but remained significantly similar there after. In contrast, the CI values of mulloway exposed to 40 mg/L CO2 were progressively and significantly reduced at each subsequent grow-out stage.
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6 mg/L 10 mg/L 20 mg/L 40 mg/L
100.0
80.0
60.0
40.0
Total weight (g/fish) weight Total 20.0
0.0
Day 0 Day 30 Day 54 Figure 8.8. Average total weight (g/fish, mean ± SE) of mulloway cultured at different concentrations of dissolved CO2 (mg/L).
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Table 8.2. Two-factor ANOVA results for total weight, weight gain, specific growth rate (SGR), total length and condition index of mulloway exposed to different 1, 2, 3 levels of dissolved CO2 for 54 days
Item CO2 concentration (mg/L) (A) P Grow-out time (day) (B) P Interaction P 6 10 20 40 (A) 0 (5/9/07) 30 (4/10/07) 54 (29/10/07) (B) (AxB)
Total weight (g/fish) 71.3±1.17a 64.4±0.96b 63.2±0.96b 53.8±0.96c <0.001 62.6±0.79 61.42±0.60 65.37±0.86 0.070 0.001
Weight gain (g/fish) 10.9±1.90a 2.9±1.55b -0.2±1.55b -10.50±1.55c <0.001 NA -1.2±0.46 2.7±1.28 0.005 0.016
SGR (% body weight /day) 0.37±0.07a 0.09±0.06b -0.05±0.06b -0.47±0.06c <0.001 NA -0.08±0.03 0.05±0.04 0.001 0.048
Total length (mm) 183.2±0.90a 178.1±0.74b 177.9±0.74b 172.7±0.74c <0.001 172.1±0.49C 178.8±0.46B 183.0±0.56A <0.001 0.001
Condition index 1.16±0.01a 1.14±0.01a 1.13±0.10a 1.11±0.10b <0.001 1.23±0.01A 1.07±0.01B 1.06±0.01B <0.001 0.004
1 Means ± SEM; for CO2 concentration means that share the same lower case superscript are not significantly different; for grow-out time means that share the same upper case superscript are not significantly different, P>0.05; two-factor ANOVA; SNK. 2 NA = not applicable 3 Condition index = weight/length 3 x 100,000
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1,2,3 Table 8.3. Mean values for total weight, weight gain, total length and condition index of mulloway exposed to different levels of dissolved CO2 for 54 days
Index & CO2 concentration (mg/L) Day 0 (5/9/07) n Day 30 (4/10/07) n Day 54 (29/10/07) n
Total weight (g/fish) 6 63.9±2.44bcd 3 68.6±2.92b 3 78.9±1.15a 2 10 62.4±0.92bcd 3 63.2±0.59bcd 3 67.5±1.98bc 3 20 63.3±0.47bcd 3 59.7±0.65c 3 66.5±1.53bcd 3 40 60.8±0.87cd 3 52.0±0.10e 3 48.5±2.71e 3
Weight gain (g/fish) 6 NA 6.8±2.17b 3 14.92±5.36a 2 10 NA 0.8±0.75bc 3 5.1±1.70b 3 20 NA -3.6±0.87cd 3 3.2±1.64bc 3 40 NA -8.7±0.80de 3 -12.2±2.28e 3
SGR (% body weight/day) 6 NA 0.34±0.06b 3 0.40±0.09a 2 10 NA 0.04±0.05bc 3 0.15±0.07b 3 20 NA -0.20±0.05c 3 0.09±0.07b 3 40 NA -0.52±0.05d 3 -0.43±0.07d 3
Total length (mm) 6 173.2±1.44d 3 183.3±1.87b 3 192.3±0.15a 2 10 172.0±0.58d 3 179.6±0.23bc 3 182.6±1.85b 3 20 172.5±0.15d 3 178.3±0.26c 3 182.8±0.61b 3 40 178.8±0.73d 3 173.0±0.33d 3 174.4±0.57d 3
Condition index 6 1.23±0.02a 3 1.11±0.03b 3 1.11±0.01b 2 10 1.23±0.02a 3 1.09±0.01b 3 1.11±0.02b 3 20 1.23±0.01a 3 1.06±0.01b 3 1.09±0.02b 3 40 1.22±0.02a 3 1.01±0.01c 3 0.91±0.03d 3
1 Means ± SEM, n = sample size. Values for each index with the same superscript are not significantly different; P>0.05; one-factor ANOVA; SNK. 2 NA = not applicable. 3 Condition index = weight/length 3 x 100,000; SGR = (ln final weight – ln initial weight)/days grown x 100.
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6 mg/L 10 mg/L 20 mg/L 40 mg/L
200
190
180
170
Total length (mm) 160
150 Day 0 Day 30 Day 54
Figure 8.9. Average total fork length (mm; mean ± SE) of mulloway cultured at different concentrations of dissolved CO2 (mg/L).
6 mg/L 10 mg/L 20 mg/L 40 mg/L
1.40
1.20
1.00
Condition index Condition 0.80
0.60 Day 0 Day 30 Day 54
Figure 8.10. Average condition index (mean ± SE) of mulloway cultured at different concentrations of dissolved CO2 (mg/L).
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8.5. Discussion During this study the experimental de-gassing system did not allow for the complete removal of dissolved CO2 from the culture water. However, the actual concentration of 6 mg CO2/L achieved for the selected nominal concentration of 0 mg/L dissolved CO2 fell within the recommended range, <10 mg/L, for dissolved CO2 levels for optimum finfish health and growth for a range of species of fish (Wedemeyer, 1996; Fivelstad et al., 1998, 2003, 2007; Foss et al., 2003). The differences between the nominal and actual dissolved CO2 levels of the other treatments were not large and to enabled a comparison between the effects of increasing levels of dissolved CO2 on fish health and growth performance to an upper level of 80 mg/L dissolved CO2.
The growth performance of mulloway was reduced as dissolved levels of CO2 increased. Mulloway exposed to 6 mg dissolved CO2/L exhibited the best growth performance. Fish from this treatment exhibited significant increases in growth throughout the entire trial. Whereas, mulloway exposed to dissolved CO2 concentrations of 10 or 20 mg/L did not display a significant increase in weight or weight gain during the trial. Interestingly all mulloway exposed to levels of <40 mg CO2/L displayed a significant increase in length, regardless of the CO2 concentration. In contrast, throughout the study the mulloway held in the dissolved CO2 concentration of 40 mg/L lost weight and did not exhibit a statistical increase in length, and hence lost condition indicating a negative sub-lethal chronic effect of CO2 exposure at this level.
The findings from this study are consistent with those reported for Atlantic salmon smolt held in fresh water. Fivelstad et al. (1998) reported a significant reduction in the condition index of Atlantic salmon, Salmo salar, smolts cultured in freshwater, at a constant pH, when exposed to increasing levels of dissolved CO2 (medium level 19 mg CO2/L and high level 32 mg CO2/L) when compared to the control group (7 mg CO2/L), after 62 and 123 days. Fivelstad et al. (2003) also observed a progressive significant reduction in specific growth rate of Atlantic salmon from 0.26 to 0.06 to -0.25%/day after 38 days exposure as dissolved CO2 levels increased from 1.8 to 9.3 to 19.4 mg/L. In the same study the condition index of the Atlantic salmon was also significantly lower in the group cultured at 9.3 mg CO2/L compared to the control group cultured at 1.8 mg CO2/L (Fivelstad et al., 2003). Fivelstad et al. (2003) also reported accumulated mortality levels of 42% for Atlantic salmon smolt after 25 days exposure to dissolved CO2 levels of 19.4 mg/L. Fivelstad et al. (2007) reported a significant reductions in the specific growth rates of Atlantic salmon parr cultured over a 47 day period in buffered freshwater due to an increased dissolved CO2 concentration (<1.8 or >28.2 mg/L), and a reduction of water temperature (from 15–5°C). In contrast, Wurts and Durborow (1992) reported channel catfish, Ictalurus punctatus, tolerated levels of dissolved CO2 up to 30 mg/L with no apparent loss in growth performance if dissolved oxygen concentrations exceed 5 mg/L. Foss, Røsnes & Øiestad (2003) observed no differences in
growth rates of spotted wolffish, Anarhichas minor, when dissolved CO2 levels ranged from 1.1 to 33.5 mg CO2/L. When our results are compared to those for the abovementioned species it is clear that CO2 tolerance is species dependent.
With respect to upper limits of CO2 tolerance the treatments levels (60 and 80 mg CO2/L) chosen in this study clearly covered the range required to elicit a reduction in growth performance, and ultimately for the two highest treatments, in all probability, complete
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mortality. These findings are relevant and clearly demonstrate that the inherent levels of CO2 in the untreated SIS groundwater supply will not support mulloway growth or survival. Fish have been reported to have the ability to successfully acclimatise to slow increases of CO2 but may be adversely affected by sudden increases (Timmons et al., 2002). To avoid exposing the mulloway to sudden and potentially lethal spikes in CO2 concentration during the start up phase of the trial, every attempt was made to ensure concentrations were increased slowly over six days. The high mortalities observed for the mulloway exposed to the 60 and 80 mg CO2/L treatments are not surprising when data was compared to the recommended guidelines for CO2 exposure and it is realised that CO2 is commonly used as an anaesthetic for fish (Summerfelt and Smith, 1990; Bernier and Randall, 1998; Pirhonen and Schreck, 2003; Coyle et al, 2004), including a killing technique for harvested fish on some commercial farms. Levels of 120 to 150 mg CO2/L are reported to be suitable to anaesthetise fingerling rainbow trout while higher levels of 200 mg CO2/L are required for adults (Coyle et al., 2004). The disoriented behaviour of mulloway in the 80 mg CO2/L treatment during the start up phase of the trail was typical of behaviour of finfish entering into the early light sedation stage of anaesthesia (Summerfelt and Smith, 1990).
The SGRs of mulloway observed in this study were comparable to the lower range SGR values reported for other mulloway cultured in inland saline waters in Australia (Doroudi et al., 2006; Partridge et al., 2006). Doroudi et al. (2006) reported SGR ranging from 0.46 to 1.12 for mulloway of comparable size cultured in inland saline waters at temperatures of 20°C. However, reported SGRs of mulloway may be considered inferior when compared to SGRs reported for other species of fish grown in inland saline waters. Partridge et al. (2006) reported SGRs of 1.91, 1.73 and 0.68, respectively, for rainbow trout (Oncorhynchus mykiss), barramundi (Lates calcarifer) and mulloway grown in inland saline water in a semi intensive floating tank system. In the same study, Partridge et al. (2006) also reported FCRs of 0.97, 0.90 and 1.39, respectively, for rainbow trout, barramundi and mulloway. The slow growth rates of cultured mulloway have been reported to be attributed to several factors including, but not restricted to, low water temperatures (<20°C) (Doroudi et al., 2006; Partridge et al., 2006), hypoxia as a result of failure to maintain dissolved oxygen saturation levels of above >75% in culture systems (Fitzgibbon et al., 2007; Partridge et al., 2006), or low feed intake (Partridge et al., 2006). As mulloway in this study were held in water temperatures and dissolved oxygen levels that were consistently maintained above 20°C and 75% saturation, respectively, the slow growth of mulloway in this study may be attributed to low feed intakes. Further research is need in this area.
The pH of the culture water differed between treatments. In fact, there was an inverse relationship with increasing CO2 concentration and pH observed in this study. Fivelstad et al., (2003) also reported the same relationship between CO2 concentration and pH in a study carried out in fresh water with Atlantic salmon. Extremes in pH may impact on the respiratory physiology of finfish and result in reduced growth and, if levels deviate too far from the recommended levels, mortality may occur (Fromm, 1980; Stickney and Kohler, 1990). Stickney and Kohler (1990) reported that most freshwater fish appear to be indifferent to pH within the range of approximately 6.5 to 9.0, where as marine finfish should have pH maintained in the range of 7.0 to 9.0. Stickney and Kohler (1990) also suggested that drastic shift in pH level may be detrimental to fish health and growth. The pH levels of all treatments did fluctuate in this study, but only mildly, and over a period of days. Therefore, it is unlikely
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that a pH shift would have contributed to mortalities. In contrast, throughout the study the pH level of the 40 mg CO2/L treatment was consistently lower than for all other treatments and bordered on the minimum recommended level for marine fish (Stickney and Kohler, 1990). As water pH can have an impact on oxygen uptake, the low levels of pH, in combination with the high CO2 concentration may have negatively impacted on the respiratory physiology and growth of the mulloway. No measurements of blood pH or respiratory physiology were done in this study to understand in detail the mechanisms in operation, and this could be an area for further investigation.
8.6. Conclusions and Recommendations Results from the trial have demonstrated that growth performance and ultimately survival of mulloway is impacted by the levels of dissolved CO2 found in the SIS groundwater supply used at WISAC, even after primary degassing (dissolved CO2 10.7 mg/L). Although this trial was carried out under experimental conditions, the observed growth and survival trends are likely to be representative of what would occur at a larger scale and, therefore, relevant to those considering the development of commercial ventures. The results indicate that performance of mulloway is superior when levels of dissolved CO2 were at a 6 mg CO2/L, the lowest level investigated. Also, there is a clear relationship between increasing concentration of dissolved CO2 and decreasing pH that may be a factor contributing to the reduced growth of fish at increasingly high levels of dissolved CO2. The relationship between the concentration of CO2, pH and finfish growth requires more detailed physiological and biochemical investigation to explain the mechanisms that are operating in mulloway and other potential aquaculture species that might be cultured in SIS groundwater.
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8.7. References Alabaster, J.S., Herbert, D.W.M and Hemens, J. 1957. The survival of rainbow trout (Salmo gairdnerii Richardson) and perch (Perca fluviatilis L.) at various concentrations of dissolved oxygen and carbon dioxide. Annals of Applied Biology 45: 177–188. Bagenal T.B. and Tesch F.W. 1978. Age and growth: In T.B. Bagenal (Editor), Methods for assessment of fish production in fresh waters, 3rd Edition, Blackwell Scientific Publications, Oxford, England, pp.101–136. Bernier, N. J. and Randall, D. J. 1998. Carbon dioxide anaesthesia in rainbow trout: Effects of hypercapnic level and stress on induction and recovery from anaesthetic treatment. Journal of Fish Biology 52: 621–637. Colt, J. 1986. Gas supersaturation—impact on the design and operation of aquatic systems. Aquacultural Engineering 5: 49–85. Coyle, S.D., Durbarow, R.M. and Tidwell, J.H. 2004. Anaesthetics in Aquaculture. Southern Regional Aquaculture Center Publication No. 3900, p. 6. Doroudi M.S., Fielder D.S., Allan G.A. and Webster G.K. 2006. Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Aquaculture Research 37: 1034–1039. Fitzgibbon Q.P., Strawbridge A. and Seymour R.S. 2007. Metabolic scope, swimming performance and the effects of hypoxia in the mulloway, Argyrosomus japonicus (Pisces: Sciaenidae). Aquaculture 270: 358–368. Fivelstad, S., Haavik, H., Lovik, G. and Olsen A.B 1998. Sublethal effects and safe levels of carbon dioxide in seawater for Atlantic salmon postsmolts (Salmo salar): ion regulation and growth. Aquaculture 160: 305–316. Fivelstad, S., Waagbø, R., Stefansson, S. and Olsen, A.B 2007. Impacts of elevated water carbon dioxide partial pressure at two temperatures on Atlantic salmon (Salmo salar L.) parr growth and haematology. Aquaculture 269: 241–249. Fivelstad, S., Waagbø, R., Zeitz, S.F., Hosfeld, A.C.D., Olsen, A.B. and Stefansson, S. 2003. A major water quality problem in smolt farms: Combined effects of carbon dioxide, reduced pH and aluminium on Atlantic salmon (Salmo salar L.) smolts: Physiology and growth. Aquaculture 215: 339–357. Foss, A., Røsnes, B.A. and Øiestad, V. 2003. Graded environmental hypercapnia in juvenile spotted wolffish (Anarhichas minor Olafsen): effects on growth, food conversion efficiency and nephrocalcinosis. Aquaculture 220: 607–617. Fromm, P.O. 1980. A review of some physiological and toxicological responses of freshwater fish to acid stress. Journal Environmental Biology of Fishes 5: 79–93. Michaelidis, B., Spring, A. and Pörtner, H.O. 2007. Effects of long-term acclimation to environmental hypercapnia on extracellular acid-base status and metabolic capacity in Mediterranean fish Sparus aurata. Journal Marine Biology 150: 1417–1429.
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Partridge G.J., Sarre G.A., Ginbey B.M., Kaya G.D., & Jenkins G.I. 2006. Finfish production in a static, inland saline water body using a Semi-Intensive Floating Tank System (SIFTS). Aquacultural Engineering 35: 109–121.
Pirhonen, J. and Schreck, C. 2003. Effects of anaesthesia with MS-222, clove oil and CO2 on feed intake and plasma cortisol in steelhead trout (Oncorhynchus mykiss). Aquaculture 200: 507–514. Spotte, S. 1992. Captive seawater fishes: Science and Technology. John Wiley and Sons Inc, New York. 942 pp. Stickney, R.R. and Kohler, C.C. 1990. Maintaining fishes for research and teaching. In: C.B. Schreck and P.B. Moyle (Editors). Methods for Fish Biology. American Fisheries Society, Bethesda, MD, pP. 633–663. Sullivan, M., Reid, S.W.J., Ternent, H., Manchester, N., Roberts, R.J., Stone, D.A.J. and Hardy, R.W. 2007. The aetiology of spinal deformity in Atlantic salmon, Salmo salar L.: Influence of different commercial diets on the incidence and severity of the preclinical condition in salmon parr under two contrasting husbandry regimes. Journal of Fish Disease, 30: 759–767. Summerfelt, R.C. and Smith, L.S. 1990. Anaesthesia surgery, and related techniques. In: C.B. Schreck and P.B. Moyle (Editors). Methods for Fish Biology. American Fisheries Society, Bethesda, MD, pp. 213–272. Timmons, M.B., Ebeling, J.M., Wheaton, F.W., Summerfelt, S.T. and Vinci, B.J. 2002. Recirculating Aquaculture systems. Cayuga Aqua Ventures, Ithaca, NY, USA. NRAC Publication No. 01-002, p. 769. Wedemeyer, G.A. 1996. Interactions with water quality conditions. In: Physiology of Fish in Intensive Culture Systems. Chapman and Hall, New York, New York. Wurts, W.A and Durborow, R.M. 1992. Interactions of pH, carbon dioxide, alkalinity and hardness in fish ponds. Southern Regional Aquaculture Center Publication No. 463: 5 pp.
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Chapter 9 – Characterisation of the affects of the waste discharge from the Waikerie Inland Saline Aquaculture Centre on the composition of saline inland aquaculture water, May 2006–December 2007
Summary An environmental water quality monitoring program was conducted from May 2006 to December 2007 to evaluate the effects of semi-intensive fish farming that occurred at WISAC.
WISAC fish culture was a semi-intensive system using mulloway (Argyrosomus japonicus) as the main species. Over the time that the environmental water quality monitoring program was undertaken, the finfish standing stock at WISAC increased from 0 to 3,839 kilograms, while the system managed to optimise the temperature and water quality experienced by the fish.
The purpose of this component of the project was to: • collect the required water quality data • determine the extent the level of fish farming undertaken influenced the waste discharge levels • obtain and maintain the relevant regulatory approvals.
Three key aspects were found to limit the likely usefulness of the South Australian government regulated environmental water quality monitoring to evaluate the effects of a semi-intensive fish farming that occurred at the WISAC. These are: • the problem of detecting the environmental effects of finfish farming when only a relatively small culture system was in operation, which used only about 4% of the total flow of the water in the SIS pipeline • the problem of detecting the environmental effects of finfish farming when the system was constructed and operated to maintain suitable water quality for culturing finfish • the problem of detecting the environmental effects of finfish farming using small numbers of water samples, which were instantaneous measures, and not related to or standardised with the farming practices in use (e.g. feeding times, tank sludge drainage times, etc.)
Based on the results obtained, it is proposed that there was no pronounced effect of a semi- intensive scale finfish farming at WISAC on the downstream SIS water and even less on the SPDB, which seemed to operate as a largely independent system.
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Of the water quality parameters assessed, oxidised nitrogen, ammonia, total nitrogen and suspended solids seemed to provide the most sensitive measures of the effects of, and affects on, finfish farming.
Background WISAC was constructed and trials initiated using mulloway (Argyrosomus japonicus) as the focal species. The WISAC fish farming system is a semi-intensive system consisting of three 70,000 L shade-mesh covered outdoor tanks that use a combination of flow through and partially recirculated water. New SIS groundwater flows by gravity into each production tank from two 250,000 L holding tanks connected to the SIS. Recirculated water is water that has been previously discharged from the production tanks and has proceeded through a solids separator (Eco-Trap™, AquaOptima, Trondheim, Norway) adjacent to each tank as well as common primary and secondary settlement ponds. Separated solids are diverted to a purpose built lined pond where it accumulates in isolation from the finfish culture system. It is pumped into a collection tanker and disposed at an approved council waste disposal site. All these items work together to remove the sludge and much of the suspended matter (see Chapter 1 for a more detailed system description). Treated discharge water is pumped back into the SIS pipe, from where it flows into the SPDB.
To obtain fish farming approval and licensing for WISAC, liaison was conducted with PIRSA Aquaculture and, through them, with the South Australian Environmental Protection Authority (EPA). Both have environmental responsibilities, the former primarily to ensure sustainable aquaculture development and the latter to control and manage the impacts of discharge wastes.
The purpose of this component of the project thus became to: • collect the required water quality data • determine the extent the level of fish farming undertaken influenced the waste discharge levels • obtain the relevant regulatory approvals.
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Methods An application was made for a fish farming licence from PIRSA Aquaculture and through this, SARDI was directed to undertake a waste water monitoring program that met the requirements of PIRSA Aquaculture and the EPA.
The licence specified an environmental monitoring program and involved samples being collected prior to the fish farming activity (i.e. where water was taken from the SIS pipeline and entered the WISAC – Inlet), and after the fish farming activity (where water was discharged back into the SIS pipeline – Outlet). As the activity was R&D, water samples were also required to be taken at the SIS pipeline discharge point into the SPDB (SPDB – Outlet) and at a location within the SPDB approximately one hundred metres from the point of SIS inflow.
Duplicate samples were taken monthly and tested for oxidised nitrogen (N as NO3 and NO2), ammonia (as NH4 and NH3), Total Kjeldahl Nitrogen (total organic nitrogen), soluble phosphorus and suspended solids. Analytical water sample testing was undertaken by the Australian Water Quality Centre, Adelaide, a National Association of Testing Authorities (NATA) accredited facility. This procedure was undertaken from May to December 2006.
After a subsequent review of the results of the environmental monitoring program, it was agreed by PIRSA Aquaculture that future water sampling could be decreased to match the requirement of commercial aquaculture ventures with a single discharge point. At this time, water sampling involved duplicate samples, three times per year, before the aquaculture venture and at its discharge point. Again, analytical testing was required from a NATA certified laboratory for oxidised nitrogen (N as NO3 and NO2), ammonia (as NH4 and NH3) and soluble phosphorus. As a settlement pond was present, suspended solids did not need to be assessed. This procedure was used from February 2007 until the end of the project. Some missing data resulted because of sample damage either on site soon after collection, during transport, or at the analytical laboratory.
Commercial aquaculture facilities will require large scale production (i.e. hundreds of tonnes pa) to be economically viable. This level of production will necessitate management of discharged water that has potential to impact upon the ecology of SPDB. To increase the information available on the ecology of SPDB prior to any commercial aquaculture development, a South Australian Murray Darling Basin Natural Resource Management (SA MDB NRM) Board and SA Water funded study was conducted. As part of this project an honours study was conducted, titled Aquatic micro-invertebrate ecology within three saline lakes, one natural and two artificial, This study incorporated investigation of SPDB, Noora Disposal Basin near Loxton and Lake Gnotuk in Victoria (David Barry, Flinders University, unpublished). In addition, a seasonal bird study was conducted for SPDB (Peter Waanders, unpublished, Appendix D).
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Statistical Analysis A range of exploratory data analysis techniques were undertaken using Excel (Microsoft Inc.) and SPSS Version 16.0.1 for Windows (SPSS Inc., Chicago, IL, USA) to detect visual patters of meaningful correlation or clustering of data.
Results
Culture System Over the time that the environmental water quality monitoring program was undertaken, finfish standing stock at WISAC went from 0 to 3,839 kilograms (Table 9.1), with the system being continuously managed to optimise temperature and water quality experienced by the fish.
Soluble Phosphorus Soluble phosphorus remained relatively constant between replicate samples and with time, with the median generally being between 0.005 and 0.0007 mg/L at the WISAC Inlet and Outlet, and at the SPDB Outlet and SPDP Other (Table 9.1).
Ammonia Median ammonia levels fluctuated considerably with time, although not between replicate samples, ranging from 0.005 to 3.486 mg/L with these extreme values both occurring in the WISAC Inlet water (Table 9.1).
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Table 9.1. Environmental water quality monitoring and fish stock biomass data for the WISAC from May 2006 to December 2007.
5/05/2006 5/05/2006 22/09/2006 22/09/2006 30/10/2006 30/10/2006 29/11/2006 29/11/2006 27/12/2006 27/12/2006 24/01/2007 24/01/2007 22/06/2007 22/06/2007 20/08/2007 20/08/2007 20/12/2007
Date 21/06/2006 21/06/2006 18/07/2006 18/07/2006 17/08/2006 17/08/2006 Sample 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1
Inlet 0.547 0.605 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.006 0.006 0.007 0.007 0.007 0.007 0.007 0.007 0.008 0.005 0.005 0.01 Outlet 0.78 0.523 0.013 0.017 0.021 0.021 0.005 0.005 0.005 0.005 0.006 0.005 0.005 0.005 0.008 0.009 0.005 0.005 0.007 0.005 0.005 0.009 SPDB Outlet 0.005 1.04 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.008 0.006 0.006 0.006 0.006 0.007 0.007 0.005 0.005 0.005 (EPA < 0.1) SPDB Soluble P (mg/L)Soluble P Other 0.482 0.505 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.008 0.022 0.031 0.007 0.005 0.007 0.007 0.005 0.005 0.006 Inlet 0.006 0.006 0.772 0.804 1.907 1.499 1.658 1.77 0.013 0.019 2.57 2.31 2.217 2.376 2.273 2.312 3.335 3.292 0.005 0.173 0.386 3.486 Outlet 0.596 0.63 0.437 0.48 1.473 1.471 1.187 1.134 0.631 0.831 1.72 1.92 1.151 0.909 1.485 1.493 1.785 1.794 0.978 0.293 0.005 2.145 SPDB
(mg/L) Outlet 0.17 0.057 0.358 0.331 1.036 0.876 0.996 0.906 1.289 1.3 0.018 0.034 0.027 0.048 1.332 1.365 1.961 1.928 0.015 0.006 0.077
(EPA 0.005) SPDB Ammonia as N Other 0.09 0.084 0.3 0.121 0.042 0.005 0.082 0.045 0.117 0.127 0.01 0.051 0.312 0.245 0.052 0.014 0.005 0.005 0.005 1.3 Inlet 1.56 1.63 1.41 1.36 0.904 0.927 1.25 1.25 0.593 0.633 1.08 1.13 1.1 1.04 1.23 1.26 0.394 0.385 0.825 0.767 0.736 0.184 Outlet 1.39 1.31 1.39 1.41 1.49 1.49 1.73 1.73 1.45 1.47 1.63 1.58 2.03 2.07 2.14 2.2 1.6 1.62 1.77 0.738 0.015 1.39 SPDB
(mg/L) Outlet 1.88 1.98 2.02 1.97 1.73 1.76 1.91 1.96 2.45 2.41 2.13 0.005 2.07 2.02 1.43 1.44 1.34 1.3 0.047 0.026 0.007 Oxidised N (EPA < 0.2) SPDB Other 0.005 0.005 0.005 0.005 0.006 0.005 0.005 0.005 0.005 0.005 2.1 0.005 0.007 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.515 Inlet 0 0 0.56 0.87 1.84 1.71 1.7 1.72 0.1 0.005 2.48 2.22 2.41 2.52 2 2.12 3.3 3.31 2.26 0.84 0.75 3.42 Outlet 0.97 1.11 1.18 1.13 1.76 1.54 1.63 1.53 1.74 0.83 1.89 2.28 1.23 1.15 1.95 2.02 2.21 2.31 0.88 1.37 1.36 3.33 SPDB Outlet 1.74 0.13 0.41 0.38 1.04 0.93 1.51 1.01 0.13 0.13 0.22 1.66 0.83 0.96 1.1 1.11 0 0 1.4 1.4 2.19
(EPA < 4.8) SPDB TKN as N (mg/L) Other 1.74 1.93 2.2 2.27 1.38 1.42 1.58 1.88 1.63 1.51 0.16 1.66 2.41 2.41 1.67 1.68 1.29 1.24 1.34 1.32 1.56 Inlet 1 4 4 8 7 7 4 4 6 7 6 4 6 5 13 12 4 5 7 Outlet 2 1 6 2 5 7 10 5 36 36 6 9 4 4 57 18 7 22 7 SPDB
(mg/L) Outlet 1 1 5 5 6 5 6 6 7 12 6 15 7 14 7 6 6 5
(EPA < 10) SPDB
Suspended Solids Other 10 10 19 10 9 11 13 9 113 81 7 11 54 39 63 21 12 14 Fish Biomass (kg) 0 1157 1157 1286 1286 1525 1525 2017 2017 2017 2288 2288 2709 2709 3041 3041 3371 3371 3529 3529 3396 3396 3839
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Oxidised Nitrogen Median oxidised nitrogen levels ranged from 0.3895 to 2.17 mg/L over the monitoring period, again with little variation between replicates and with the lowest level in the WISAC Inlet water and the highest value in the WISAC Outlet water (Table 9.1). This trend was reinforced by the oxidised nitrogen levels on nine of the 12 sampling dates being higher in the WISAC Outlet water than the paired Inlet water levels.
Total Nitrogen The median total nitrogen level in the SPDB waters ranged from undetectable to 2.085, and also varied moderately between paired replicate samples (Table 9.1).
Suspended Solids The median suspended solid levels ranged from 1–37.5 mg/L in the SIS pipeline system with the paired replicate samples relatively similar (Table 9.1). They were higher in the WISAC Outlet water (1.5–37.5 mg/L) compared to the Inlet water (2.5– 12.5 mg/L) on five of the 10 sampling dates and identical on one.
Discussion There is little variation in soluble phosphorus in the SIS pipeline water over the time monitored, and there was no discernible effect from a semi-intensive system of fish farming undertaken at WISAC on this measure of water quality.
There was no systematic correlation in ammonia levels in the outlet water with finfish stock biomass. On only three of the 12 sampling dates did the WISAC outlet water have higher ammonia levels than the inlet water, and on each of these occasions the ammonia level in the inlet water was particularly low. It is also interesting to note that the ammonia levels of the SPDB Outlet water were commonly less than the WISAC Inlet water, suggesting that ammonia levels possibly degraded along the length of the SIS pipeline. The SPDB Other ammonia levels were typically much lower than anywhere within the SIS pipeline, either before or after the WISAC. Overall, the data suggests that the level of finfish farming undertaken at WISAC had very little affect on the waste water ammonia levels, with the normal levels in the SIS pipeline masking any affects of the fish farm except when the normal pipeline (Inlet) levels were very low.
Oxidised nitrogen levels suggest that the level of finfish farming occurring at WISAC may have had an affect on this parameter because there was often high levels in the SPDB outlet water and the levels decreased with distance along the pipeline. However, there was no correlation between oxidised nitrogen levels and finfish stock biomass. Very low oxidised nitrogen levels (typically around 0.005mg/L) suggest that any higher levels rapidly dissipated, therefore, a few hundred metres into the Basin
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from the SPDB outlet it is unlikely that there will be a noticeable effect on the ecosystem.
On only three of the 12 sampling times was the level of total nitrogen at the WISAC Outlet higher than the Inlet level, and like with ammonia, these were each when the Inlet total nitrogen levels were at their lowest. For nine out of the 11 sampling dates with available data, the SPDB Outlet total nitrogen levels were lower than the equivalent WISAC Inlet and Outlet levels. There was no correlation of total nitrogen levels and finfish stock biomass. The SPDB total nitrogen levels were generally of a similar magnitude to the WISAC Inlet and Outlet levels. Overall, the data suggests that the level of finfish farming undertaken at WISAC had very little effect on the waste water total nitrogen levels, with the normal levels in the SIS pipeline masking any effects except when the inlet levels were very low.
It was noticeable that the outlet water levels of suspended solids tended to be lower than the inlet water levels at earlier sampling dates and higher at latter sampling dates—the latter times also generally having much higher suspended solid levels. Despite this qualitative trend of increased suspended solid levels with increased finfish stock biomass, there was no quantitative correlation. The suspended solid levels in the SPDB away from the outlet, were moderately high (typically between 9 mg/L and 13 mg/L) compared to other sampling points in the SIS pipeline, and varied greatly on occasion (e.g. 97 mg/L). Overall, the data suggested that the level of finfish farming undertaken at WISAC could increase the suspended solid levels, but levels at the WISAC Outlet declined to be similar to background levels at the SPDB Outlet. These were, in turn, much lower than typical levels recorded at the sampling site further into the Basin (SPDB Other).
As relatively little ecological information exists for SPDB, a project was initiated by SARDI titled An ecological study of the Stockyard Plain Disposal Basin, with funding provided by the SA MDB NRM Board and SA Water. The study involved monthly water quality and biological sampling along a set transect of six points within SPDB. Aquatic micro-invertebrate ecology within three saline lakes, one natural and two artificial was conducted as an honours project and incorporated investigation of SPDB, Noora Disposal Basin near Loxton and Lake Gnotuk in Victoria (David Barry, Flinders University, unpublished). In addition, a seasonal bird study was conducted for SPDB (Peter Waanders, unpublished, Appendix D). Together these studies provide additional information on the ecology of SPDB prior to commencement of any commercial scale aquaculture operation using SIS groundwater that is ultimately discharged into this water body.
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Conclusions and Recommendations Three key aspects limit the likely usefulness of the SA Government regulated environmental water quality monitoring to evaluate the effects of semi-intensive system fish farming that occurred at the WISAC. These are: • The problem of detecting the environmental effects of finfish farming when only a relatively small culture system was in operation, which used only about 4% of the total flow of the water in the SIS pipeline. Typical mass balance calculations for key nutrients suggest that any effects this level of finfish farming would have on water quality would be small and thus difficult to detect above background. • The problem of detecting the environmental effects of finfish farming when the semi-intensive aquaculture system was operated to minimise adverse water quality conditions in order to provide optimal conditions for culturing finfish. • The problem of detecting the environmental effects of finfish farming using small numbers of water samples, which were instantaneous measures, and not related to or standardised with the farming practices in use (e.g. feeding times, tank sludge drainage times, etc). A more meaningful approach to monitoring than that presently dictated by regulation would be to use continuous sampling over select periods of time to capture average and known extreme conditions. This could be achieved using automated water sampling equipment and subsequent analysis, or in situ water quality sensors with data loggers. This type of equipment is likely to be prohibitively expensive for small aquaculture ventures.
Given these constraints on the environmental water quality monitoring undertaken, it still remains reasonable to propose, based on the results obtained, that there was no pronounced effect of a semi-intensive scale finfish farm at WISAC on the downstream SIS water and even less on the SPDB, which seemed to operate as a largely independent system. The latter is not surprising given that SPDB has an established aquatic ecosystem present and a wide range of other environmental factors influence the ecology of the organisms within it. Together they are likely to have a significant capacity to ameliorate the effects of the quality of SIS groundwater discharged into the SPDB ecosystem.
Of the water quality parameters assessed, oxidised nitrogen, ammonia, total nitrogen and suspended solids seemed to provide the most sensitive measures of the effects of, and affects on, finfish farming. They are also widely used measures of the successful operation of any static (i.e. settlement ponds) and dynamic mechanical (i.e. filters) treatment systems that are incorporated into fish farms to manage waste discharges.
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Chapter 10 – Halophyte culture trials, March 2007– February 2008
10.1. Summary Halophytes are terrestrial plants that are able to live in soils with a high concentration of salt. The endemic halophyte, the samphire, Sarcocornia quinqueflora, has been investigated at WISAC as a potential crop with the capacity to remove finfish farm wastes, particularly nutrients and suspended solids, which might otherwise impact on the SPDB. Also of interest, was the capacity of this species to reduce the volume of water discharged into the SPDB through water loss from evapotranspiration by the plant itself and through evaporation of water used to irrigate the plants.
Preliminary trials were undertaken at WISAC to investigate whether small, established plants of S. quinqueflora could be transplanted from the margins of SPDB to provide a source of plants. If successful, it was envisaged that transplanted plants would be used to conduct experiments to determine factors such as water use (i.e. evapotranspiration), nutrient uptake and growth of this common halophyte species.
Three trials were undertaken using a factorial experimental design with replicate pots of transplanted S. quinqueflora held in replicate trays using salt interception water prior to and after being used to culture mulloway (Argyrosomus japonicus).
Adverse weather and a poor response to transplantation by this halophyte species resulted in low survival and highlighted the need for improved methods to establish plants for experimentation and/or the need to identify alternative species. Potential future research directions are highlighted.
10.2. Background As commercial aquaculture operations aligned to SISs in the Riverland region are established, the issue of wastewater treatment will become significant for adherence to environmental sustainability requirements and increasingly for market access. As such, there is a need to investigate methods to remove nutrients and suspended solids from water discharged from inland aquaculture facilities using SIS groundwater. One option for the reduction of nutrients, suspended solids and water volume may be to use discharged water to irrigate crops of endemic halophytic plants that can flourish in elevated salinity soils.
Halophytes are terrestrial plants that are able to live in soils with a high concentration of salt. There are a range of Australian native halophytic plants (i.e. Sarcocornia sp., Tecticornia sp. previously Halosarcia sp., Bob Chinnock, Acting Manager, South Australian Herbarium, pers. comm. 2007) that are known to grow in areas that are subject to high levels of salinity. The local samphire species, Sarcocornia quinqueflora (Bob Chinnock, Acting Manager, South Australian Herbarium,, pers. comm. 2007) (Figures 11.1 and 11.2) was utilised in
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SARDI’s three preliminary trials. These plants were collected from land adjacent to the SPDB where they grow in abundance.
A similar plant type Salicornia sp. has been demonstrated to grow using water with salinity levels of up to 70g/L (Glenn et al., 1997) and is already under commercial production in Mexico, Israel, India, France, the United Kingdom and the United Arab Emirates. Menterra (2008) suggested that Salicornia sp. may also offer a possible solution as a biofilter to the problem of nutrient rich saline aquaculture effluent. Saltgrass (Distichlis spicata) and saltbush (Atriplex nummulatia) are other halophytes that have potential as animal forage. Other potential commercial products harvested from halophytes include oils, novel products for human consumption and fibre for production of construction materials.
The rock samphire (Crithmum maritimum) has fleshy, divided aromatic leaves that have long been regarded as a delicacy in England. In former times, samphire was prepared as a pickle, but is now appearing as a garnish in London restaurants. To prepare it for the table, samphire is trimmed of its hard root, washed and plunged into boiling water for a few minutes. The flavour is highly reminiscent of asparagus, and samphire is sometimes referred to as ‘sea asparagus’.
Figure 10.1. Sarcocornia quinqueflora growing adjacent to the SPDB.
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Figure 10.2. Juvenile Sarcocornia quinqueflora growing at SPDB.
In addition to the uptake of nutrients and suspended solids, the evapotranspiration from these halophytic plants and the evaporation of the waters used for their irrigation, will result in water loss that may have the potential to reduce a proportion of the volume of water requiring discharge into disposal basin. It was believed that this could have the benefit of extending the ‘life’ of disposal basins and/or allowing additional bores to be added to existing SIS.
The aim of this project was to undertake preliminary experiments to evaluate the use of a local SPDB halophyte species to achieve a significant uptake of nutrients and increase in loss of water volume of SIS groundwater used for finfish farming. It was envisaged that further dedicated projects could be justified if basic growth and water use data could be collected from the local halophyte cultivated in a system irrigated with saline groundwater discharged from the finfish aquaculture trials conducted at WISAC.
10.3. Trial 1: Potting Mix and Initial Water Regime
10.3.1. Aim The first trial started on 1 March 2007, aimed to investigate the potential for transplanting small, established Sarcocornia quinqueflora plants removed from the margins of SPDB. Treatments investigated in this trial were the potting media used and the initial water regime applied to the potted plants (Table 10.1).
10.3.2. Methods Sarcocornia quinqueflora (n = 120) of approximately 10 to 15 cm in height were collected from adjacent the SPDB (11.1). To minimise root damage, plants were dug to retain soil around the roots then immediately transplanted at their natural growing site into pots containing either natural soil, potting mix, or a 1:1 mixture of potting mix and natural soil.
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After transplanting, the potted plants were transported by vehicle (Figure 11.3) from the SPDB to WISAC. All plants were watered daily with either fresh, diluted SIS (1:1 SIS water: fresh water), or full strength SIS groundwater (Table 11.1). Plants were placed in direct sun for the duration of this trial and the condition of plants was assessed after four weeks.
A bulk soil sample was taken from beneath the soil surface down to 10–15 cm at serval locations adjacent to where plants were dug up for transplanting. The bulk soil sample was transported to SARDI’s Plant Research Centre in Adelaide where four 10 g sub samples were suspended in 50 ml of reverse osmosis filtered water and shaken intermittently for 30 minutes. The electrical conductivity (EC, dS/m) was read after 30 minutes of settling and again after centrifuging for 10 minutes at 10,000 rpm (Dr Tapas Biswas, Senior Irrigation Scientist, SARDI).
Table 10.1. Treatment descriptions and number of plants used in Trial 1, March 2007.
Treatment Watering treatment SPDB soil 1:1 Potting mix SPDB soil: potting mix A Fresh water for 7 days then SIS water 10 10 10 B Fresh water for 7 days, then 10 10 10 diluted SIS water (1:1 SIS water: fresh water) for 7 days, then SIS water C Diluted SIS water (1:1 SIS water: fresh water), for 7 10 10 10 days, then SIS water
D SIS water only 10 10 10
Figure 10.3. Plants being transferred from the SPDB to WISAC.
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10.3.3. Results The soil type in the area from where plants were removed was assessed to be a light, medium clay with salinity of 130 dS/m equivalent to 83 g/L. After four weeks only 11.7% of the 120 plants transplanted were growing, 14.2% were looking weak (unhealthy) and 74.1% had died (Table 11.2). Trial 1 was discontinued after the 29 March 2007 (29 days) due to the high mortalities.
Table 10.2. Condition of Trial 1 plants after four weeks.
Watering SPDB soil 1:1 Potting mix treatment SPDB soil: potting mix Growing Weak Dead Growing Weak Dead Growing Weak Dead
A 1 0 9 3 1 6 2 0 8
B 1 0 9 1 1 8 1 1 8
C 0 1 9 1 4 5 2 2 6
D 0 2 8 1 2 7 1 3 6
10.3.4. Discussion Discussions with a native plant nursery owner indicated that seed collection, germination and ongrowing of Sarcocornia sp seedlings to a size suitable for transplanting would take in the order of 6 months. At the time that the trial was commenced this amount of time was considered to be too long to provide any results before the end date for the project. Hence, it was considered that starting preliminary investigations on the water and nutrient use of local halophytes found at SPDB should start with investigating the ability for the most abundant species to be transplanted in order to provide the required number of plants to conduct subsequent trials to investigate factors such as water and nutrient use. Transplantation of S. quinqueflora has previously been successful. The halophytes now occurring at SPDB were introduced in 1996 by transplanting spade cut clumps (30 cm x 30 m) of 150 mm high plants, collected from natural populations around Noora Disposal Basin near Loxton. These clumps were transplanted into an area near the SIS groundwater inlet to SPDB. Five different species of halophytes were identified in clumps of plants transplanted. Approximately 10 of the 15 clumps survived transplanting and are believed to be responsible for seed that has been subsequently distributed to establish the populations of halophytes found at SPDB (Gary Schultz, Survey and Land Manager, SA Water, , pers. comm. 2007).
There could be several reasons for the poor survival rate of plants, including that the transplant stress and watering regime were not suitable. Ambient air temperature of 39°C on the day immediately following transplanting was also likely to have exacerbated transplanting and watering stress during early establishment of the plants (Figure 11.4).
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45
40
35
30
25
20
15 Temperature °C Temperature
10
5
0 1/03/2007 3/03/2007 5/03/2007 7/03/2007 9/03/2007 11/03/2007 13/03/2007 15/03/2007 17/03/2007 19/03/2007 21/03/2007 23/03/2007 25/03/2007 27/03/2007 29/03/2007
Figure 10.4. Maximum daily ambient air temperatures at Waikerie during Trial 1, March 2007.
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10.4. Trial 2: New v Used SIS Water
10.4.1. Aims A second trial commenced on the 6 December 2007 to assess growth of Sarcocornia quinqueflora irrigated with ‘new’ SIS water compared with ‘used’ SIS water discharged from a finfish production tank at WISAC. The finfish production tank was stocked with mulloway at a density of 18.3 kg/m3. This trial was viewed as the first step toward investigating the use of constant irrigation for the culture of S. quinqueflora.
10.4.2. Methods As survival of halophytes transplanted into pots had been poor in Trial 1, several improvements were made for Trial 2 in an attempt to improve the survival of transplanted plants, including:
1. undertaking plant collection from SPDB in cool conditions during the early morning 2. careful separation of individual plants and soil removal from roots in water to avoid desiccation 3. transport of plants from SPDB to WISAC in a covered container to maintain humidity and cool temperature 4. weighing of individual plants (i.e. foliage and roots) in an air conditioned room before transplanting into moist soil collected from the removal location 5. location of potted plants under shade in a protected location 6. constant irrigation of pots to maintain soil moisture
At SPDB, young S. quinqueflora plants are observed to grow in rows or clumps from rhizomes (Figures 11.5 and 11.6). In cool early morning conditions at SPDB, sections of halophyte rhizome (30 cm x 30 cm) were spade cut from a large clump (approximately 1m diameter) and transferred directly into saline groundwater within a 70 L plastic container. Individual plants were separated by cutting sections of rhizome, and then plants were transferred to another 70 L plastic container for further washing. As much soil as possible was washed from the plant and rhizome sections and the plants separated. Small plants (n = 250) of up to 16 g were then transported in an insulated cooler box to WISAC (approximately 30 minutes away by vehicle) where they were kept in an air-conditioned room.
Initial biomass (i.e. roots and foliage) of each plant was recorded before potting into individual pots. Individual plants were blotted on paper towel to remove excess water before being weighed and transferred into labelled and numbered 125 mm diameter pots (Figure 11.7 and 11.8). A sample of 10 excess plants was frozen for analysis of the initial nutrient composition. Sufficient numbers of plants were used in each treatment to allow removal without replacement of five plants for growth measurement and analysis of nutrient composition from each replicate of each treatment at three week intervals for 15 weeks
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(allowing for 50% initial survival). All plants were potted in natural soil before being placed in troughs containing 20 mm deep water (Figure 11.9 and 11.10). Establishment of the trial was assisted by six researchers from the Shandong Academy of Natural Sciences, China who visited the WISAC site as part of a study tour to observe and participate in research being undertaken by SARDI on a range of salinity related issues.
Figure 10.5. Sarcocornia quinqueflora growing from rhizomes at SPDB.
Figure 10.6. Sarcocornia quinqueflora growing from rhizomes at SPDB.
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Figure 10.7. Visiting scientists from Shandong Academy of Sciences, China, removing excess water from plants before weighing and transplanting.
Figure 10.8. Visiting scientists from Shandong Academy of Sciences, China, weighing plants prior to transplanting at WISAC.
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Figure 10.9. Sarcocornia quinqueflora plants potted and sitting in troughs supplied with ‘new’ SIS water or ‘used’ SIS water at WISAC.
Figure 10.10. Sarcocornia quinqueflora plants directly after transplanting into 125 mm pots at WISAC.
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The use of constant irrigation of pots was incorporated in Trial 2 to simulate furrow irrigation used in broad acre commercial plantings of Salicornia bigelovii watered with seawater in Mexico (Figure 11.15). It was envisaged that use of S. quinqueflora at a commercial scale may also consider use of this method of irrigation with plants grown on mounds of soil. To simulate this cultivation method a system of shallow raceway tanks was set up to hold the potted S. quinqueflora. In these raceways water was maintained at 20 mm depth and a flow rate of three litres per minute was applied to each raceway. Each raceway contained 50 potted plants and received either:
a) ‘New’ SIS groundwater from the supply; or b) ‘Used’ SIS water discharged from a finfish (mulloway) production tank.
It was anticipated that Trial 2 would allow indicative information to be obtained on the water use (evapotranspiration, ETcrop) of S. quinqueflora to estimate the potential for this halophyte to provide significant loss of water volume from SIS groundwater waste streams. To estimate ETcrop it was planned that pots would be used as small lysimeters as they could be weighed at a start and end period to determine change in weight as an indirect measure of water use. It was planned that for three days preceding the predetermined plant sampling date, the five designated pots to be sampled from each raceway would be taken from the troughs and allowed to drain for 1 hour. All pots would then be weighed and left out of the irrigation trough for 24 hours, then weighed again to determine weight change. Pots would be return to the troughs for one hour of watering before the process was repeated. Control pots of unplanted soil would also be drained and weighed during each measurement period to estimate water loss by evaporation from the soil surface. Weight loss by planted and unplanted pots over the measurement period would allow estimation of water use.
Preliminary information on the nutrient use by S. quinqueflora was to be investigated. It was intended that all plant samples taken at predetermined dates throughout the trial would be dispatched for tissue analysis to allow comparison of differences in nutrient composition between plants grown in different water types.
Growth of plants was to be determined by careful removal from soil followed by washing of excess soil from roots. Excess water would be removed by paper towel before weighing of the whole plant to determine biomass. It was anticipated that length of the main stem (plant height) would be investigated as an alternative non-destructive measure for growth. Plant height is recognised as a good measure of growth as the branching pattern of Salicornia is governed by growth of the main stem (Ellison and Niklas, 1988).
10.4.3. Results From the original 200 transplanted and potted S. quinqueflora, only 11 survived (5.5%) in total, six surviving from the two replicate ‘new’ SIS water treatment trays and five from the ‘used’ (finfish farm waste water) SIS water treatment. Air temperature was high (39°C) on the day that they were transplanted but declined over the following week (Figure 11.12).
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Insufficient plants survived to allow the intended investigation of water use (ETcrop). Surviving plants inspected on the 7 February 2008 (63 days) were observed to be actively growing in both water irrigation treatments.
10.4.4. Discussion Results from Trial 1 suggested that adverse weather following transplantation was the most likely factor to have contributed to the poor survival recorded. In response to this observation it was intended to undertake Trial 2 in spring when weather conditions are mild. Unfortunately the development of an experimental system to conduct a priority trial on the effect of elevated carbon dioxide on mulloway took much longer than anticipated. This commitment delayed the start of Trial 2 until the start of summer when temperatures were again high.
It is suggested that transplanting stress due to root disturbance and separation into small individual plants may have contributed to the poor survival. Subsequent temperatures for the remainder of December were also high (Figure 11.11) being above 30°C for 15 days between 6 and 31 of December. It is expected that the high temperatures may have been mitigated to some extent by the relatively moderate temperatures in the week following transplanting, provision of constant watering and location of potted plants under shade in a protected location.
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Figure 10.11. Maximum daily ambient air temperatures at Waikerie during Trial 2, December 2007.
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Observation of salt accumulating on the soil surface of potted plants suggested that elevated salinity in the root zone within the pots may have contributed to poor survival. The application of SIS groundwater from the base of the pots using the shallow trough irrigation method may have contributed to this outcome. However, S.quinqueflora and Tecticornia sp. are observed to grow on areas surrounding SPDB where salt scald is present and the soil salinity in the area where transplants were taken was 83 g/L. Glenn et al. (1997) suggest that soil salinity in the root zone (0 to 15 cm soil depth) should be kept below 75 g/L to achieve high biomass yield from the oilseed halophyte Salicornia bigelovii. Soil salinity in the root zone can be maintained by high irrigation rates as long as soil permeability and drainage can maintain the required leaching fraction to control the salt balance (Glenn et al., 1997), It was concluded that increased watering depth could be easily achieved in future trials by raising the water level in the pots to minimise salt accumulation.
10.5. Trial 3: Transplantation of Halophytes
10.5.1. Aims Two possible reasons for the poor survival of transplanted S.quinqueflora recorded from of trials 1 and 2 were identified: • potentially stressful transplant methods required to obtain initial biomass data for individual plants involving excessive root disturbance • evaporation of water from the top of the pots causing an increase in salt concentration within the root zone of plants when applying SIS groundwater by shallow irrigation at the bottom of pots.
Trial 3 aimed to investigate methods to improve survival of transplanted S. quinqueflora to assist in progressing to the desired halophyte research. The transplanting treatments investigated were: • transplant methods that would minimise root damage and desiccation • watering methods that would mitigate the effects of evaporation from the pots (i.e. flooding pots and watering transplanted plants with fresh water).
10.5.2. Methods On 17 January 2008, plants of S. quinqueflora plants between 7.5 and 10 cm in height were collected from adjacent the SPDB. Care was taken to ensure that minimal damage to roots occurred during all stages of transplanting. Transplanting was undertaken in the cool early morning. Two types of plants were collected: • individual plants • small clusters of two or three plants that were growing from a rhizome and left attached to each other.
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Whole plants were dug up with soil and transferred to covered and insulated coolers where they were watered with fresh water to avoid desiccation. Plants were transferred to WISAC in the back of a vehicle and immediately transplanted to pots located under shade cloth.
10.5.3. Results Survival of experimental S. quinqueflora plants (Table 11.4) were better than in Trial 1 and 2, however, plants continued to show signs of deterioration including wilting, yellowing and death. It appears that the transplanting methods and/or the cooler air temperatures were less stressful in Trial 3 (Figure 11.12) considering that 72% were still alive after three weeks (31% of these with new growth) compared to 25.9% and 5.5% that survived to four weeks in Trials 1 and 2 respectively.
After six weeks 55% of plants were alive but only 13.2% of these were actively growing. Treatments Agw and Afcw had 37.5% and 25.0% of plants with active growth respectively: none of the other treatments had any plants with new growth. The Agw and Afcw treatments both used individual plants transplanted with soil attached and were grown in deep troughs where the water level was maintained at the top of the soil. Water used to irrigate treatment Agw was ‘new’ SIS water while that used in treatment Afcw was SIS water that had previously been ‘used’ for finfish culture.
After six weeks no plants transplanted as small groups of two to three plants with soil attached (B treatments) or plants that had soil washed away (C treatments) were showing active growth. No plants from treatments D, E or F showed active growth after three or six weeks.
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Table 10.3. Treatments and number of plants used in Trial 3, January–February 20081. Treatment Description Agw Individual plants with soil attached to roots, kept in deep trough, watered with ‘new’ SIS ground water. Bgw Groups of two or three small plants growing from rhizomes with soil attached, kept in deep trough, watered with ‘new’ SIS ground water. Cgw Individual plants with soil removed from roots by washing within a plastic container of saline groundwater (to simulate treatment required for weighing individual plants) before potting, kept in deep trough, watered with ‘new’ SIS ground water. Afcw Individual plants with soil attached to roots, kept in deep trough, watered with ‘used’ (fish culture) SIS water. Bfcw Groups of two or three small plants growing from rhizomes with soil attached, kept in deep trough, watered with ‘used’ (fish culture) SIS water. Cfcw Individual plants with soil removed from roots by washing within a plastic container of saline groundwater (to simulate treatment required for weighing individual plants) before potting kept in deep trough, watered with ‘used’ (fish culture) SIS water. D Individual plants potted with soil remaining attached to roots and watered once per day with fresh water from a watering can. E Soil removed from roots by washing within a plastic container of saline groundwater (to simulate treatment required for weighing individual plants) before potting and watered once per day with fresh water from a watering can. Fgw Individual plants with soil attached to roots, plant pots standing in shallow trough (20 mm deep water) using ‘new’ SIS ground water. Ffcw Individual plants with soil attached to roots, plant pots standing in shallow trough with ‘used’ (fish culture) SIS water.
1Note: Treatments Agw, Bgw Cgw and Afcw, Bfcw, Cfcw were watered by placing pots in troughs flooded with groundwater to the top of the soil. Treatments D and E were not placed in troughs and were watered daily with fresh water using a watering can.
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Figure 10.12. Maximum daily ambient air temperatures at Waikerie during Trial 3 (17 January to 28 February 2008).
Table 10.4. Condition of Trial 3 plants after three weeks (7 February 2008) and 6 weeks (28 February 2008). Treatment Starting 3 Weeks 6 Weeks number Alive New Alive New growth growth Agw 8 8 3 4 3 Bgw 5 5 0 5 0 Cgw 8 8 1 7 0 Afcw 8 8 3 6 2 Bfcw 4 4 2 3 0 Cfcw 8 8 6 6 0 D 8 1 0 1 0 E 8 2 0 1 0 Fgw 6 2 0 2 0 Ffcw 6 3 0 3 0
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10.5.4. Discussion Results of Trial 3 in combination with those from Trials 1 and 2 indicate that transplanted small, established S. quinqueflora plants are not a suitable source of material to conduct the proposed investigations on nutrient removal and water loss through evapotranspiration at WISAC. Although a range of transplantation methods were investigated the poor survival from all treatments did not provide the number of plants required to provide adequate replication to conduct the desired experimentation.
It is suggested that the poor survival recorded in Trial 2 was attributed to the transplanting or irrigation method used, rather than adverse weather as transplanted plants were located under shade with continuous watering provided. Observation of salt accumulating on the soil surface suggested that the shallow irrigation method employed may have promoted accumulation of salt in the root zone of transplants and contributing to the poor survival.
Subsequently Trial 3 was initiated to elucidate if the need to remove plants from soil to allow weighing of plants for growth measurement, contributed to the poor survival following transplanting, or if this could be attributed to the shallow irrigation method used in Trial 2. The best performing treatments in Trial 3 indicated that survival may be improved using individual plants transplanted with soil attached and subsequently grown with the water level maintained at the top of the soil. This is supported by successful culture of Salicornia sp. in nearly submerged pots positioned in shallow ponds observed and discussed at the National Centre for Research in Mariculture, Eilat, Israel (Figure 11.13), summarised in Flowers and Hutchinson (2005). Regardless, survival from the treatments investigated in Trial 3 was not to a level that could justify the use of these methods to reliably establish the numbers of plants required for the intended investigations.
More success with transplanting of plants and germination of seeds may be achieved if carried out during cooler weather from early autumn to late spring. At the time of writing, S. quinqueflora seeds collected from plants adjacent the SPDB had been planted in seed trays but none had germinated after 20 days. These seeds may germinate after abrading them between fine sandpaper followed by soaking in fresh water before planting (Jason Emms, SARDI, pers. comm. 2007).
Other species that may prove to be more tolerant of transplanting and culture conditions at WISAC are of the genus Atriplex, such as old man saltbush (A. nummularia) and river saltbush (A. amnicola), which is able to tolerate flooded roots (Jason Emms, SARDI, pers. comm. 2007). A. nummularia is available from Western’s Nursery at Waikerie and from the State Flora nursery at Murray Bridge. A. amnicola is available from both suppliers if ordered with approximately six months notice. Alternatively other local halophytes such as Tecticornia sp. and Suedea sp. could be considered.
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Figure 10.13. Salicornia sp. being cultured in seawater discharged from finfish culture tanks at the National Centre for Research in Mariculture, Eilat, Israel (Flowers and Hutchinson, 2005).
10.6. Future Options for Halophyte Culture in SIS Groundwater
10.6.1. Brief Review of the Culture of Salt-tolerant Crops High salt content in soils increases the osmotic potential of the soil solution and prevents crop uptake of water. At any given site there is a dynamic balance between the loss of salt by drainage and the salt concentrating effect of irrigation and evaporation. In many areas the equilibrium level is above that at which conventional crops can be economically productive and hundreds of billions of dollars are lost each year due to the impact of high salinities.
10.6.2. Halophyte Seeds and Fruits Many seed bearing halophytes have an interesting characteristic; although they may have significantly greater levels of salt in their stems, leaves and branches than conventional plants, their seeds are relatively salt-free (Simpson, undated). Seeds of halophytes and salt sensitive plants have about the same ash and salt content. This has important consequences. Although the salt content can limit the direct consumption of halophyte vegetation tissues by humans and animals, the seeds of many halophytes present no such obstacle. Simpson (undated) describes the location, sizes and products of a number of halophytic grain and oil seed species, as well as acacia and other fruit bearing trees.
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Table 10.5. Nutritional composition (100g/fresh vegetable) of Salicornia (Simpson, undated). Component Units/100g fresh vegetable Energy (kcal/kJ) 9.0/37.9 Proteins (g) 2.3 Carbohydrates (g) <1.0 Fat (g) <0.5 Fibre (g) 4.4 Cholesterol (mg) <0.1 Vitamin C (mg) 9.1 Sodium (g) 2.0 Calcium (mg) 78.0 Magnesium (mg) 120.0 Potassium (mg) 180.0 Iron (mg) 3.0
For example, Salicornia is the Latin name for a plant that grows in salt marshes around much of the world. In much of Western Europe, Salicornia has supplied key vitamins and minerals to coastal diets for centuries (Table 11.5). More recently, this plant has become a delicacy for a wider public. Salicornia can be consumed raw or cooked. If a less salty flavour is desired the vegetable should be rinsed for longer. It can be kept in the refrigerator for one to two weeks, but should be stored in packaging with holes to prevent condensation and to keep the vegetable from drying out.
Today Salicornia fresh green tips are sold as a delicacy in the USA, Canada and several countries in Europe. They feature in top class restaurants in New York, London, Paris, Brussels and Amsterdam (Menterra, 2008), and in deluxe greengrocers as well as a widening range of nature food shops.
Sanderson and Prendergast (2002) reported that in London in 2001 Wild Harvest (a supplier and caterer of wild foods) sold marsh samphire for £7.50 /kg, but only 5% of its supplies are British, the rest being imported from France (in June and July) and Saudi Arabia (December and May). Sanderson and Prendergast (2002) also reported Rockport Fish Ltd (Tunbridge Wells, Kent) imports all its marsh samphire from France, and sells it for £4.00–6.50/kg depending on season
Food processing companies are now using Salicornia, as it has the rare quality of remaining green during the process of freezing and defrosting, and adds newness and delicacy to excellent cuisine.
Glenn (1991) reported that when crushed for oil, Salicornia yielded 30% oil and 70% meal, and that the protein content of the meal is 42–45%. When used as hay, including the seeds, Salicornia is about 1012% protein; without the seeds it is 5–7% protein.
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The Israeli company Bacto-Sil Ltd is growing and supplying halophyte vegetables to the European Community, including Salicornia (sea asparagus), sea aster (sea spinach) and the Japanese salsola (sea cress, also called oka hikiki). The company emphasises the high and diversified minerals content including vitamin A and C, and magnesium, potassium, copper, iron, manganese and zinc. Selenium levels were reported to be 1,000 to 10,000 times the value in non-halophytic plants.
Sanderson and Prendergast (2002) reported that Salicornia bigelovii is cultivated for seed oil in Saudi Arabia by Seaphire International Inc. (Phoenix, Arizona, USA). This company also has farms in Mexico and Eritrea for cosmetics and foodstuffs.
10.6.3. Halophytes and Leaf Protein Although the leaves and shoots of some salt tolerant foliage crops can be used in salads or as a garnish with minimal processing, most halophytes retain enough salt in their leaves to inhibit their consumption. One solution to this problem that has been adapted is to extract leaf protein from the salt containing foliage. To produce leaf protein, fresh foliage is fed into a press. The juice is extracted from the leaves which can then be used as ruminant feed. The juice is heated until a coagulum is formed and this curd is filtered, washed, and separated. The watery residue (containing most of the salt) is discarded or passed through into a biodigestor used to produce methane gas for cooking or heating. The material recovered during the filtration is salt free protein (Table 11.6) that can be used as supplements to fortify traditional foods for humans or animals.
Table 10.6. Leaf composition of a range of salt tolerant plants used for leaf protein production (includes Salicornia) (Simpson, undated). Component Units/100 g Dry Matter True Protein (g) 50–60 Lipids (g) 10–25 Beta Carotene (mg) 45–159 Starch (g) 2–5 Monosaccharides (g) 1–2 B-Vitamins (g) 16–22 Vitamin E (mg) 15 Choline (mg) 220–260 Iron (mg) 400–800 Calcium (mg) 400–800 Phosphorus (mg) 240–570 Ash (g) 5–10
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10.6.4. Production Methods Benes et al., (1999) described four options for the utilisation of subsurface saline ‘drain’ water to irrigate crops: • Application of drain water to an undrained field cropped to a salt tolerant row crop or forage—Tall wheat grass and other forages have been used for this purpose, but ideally, a blend of warm and cool season forage would be best. This practice is not sustainable in the long-term, as soil salinity in the undrained field tends to increase beyond the tolerance limit of the forages. • Blending—Saline drain water is mixed with less saline water to achieve irrigation water of suitable quality for the salinity tolerance of the crops being grown. The blending must not unduly compromise the quality of the irrigation water. • Cyclic Re-use—Saline drain water is used for irrigation but alternated with high quality water, often within a multi-year rotation. The drain water is used only for the more salt tolerant crops of the rotation and/or during the more salt tolerant stages of crop development (e.g. after first bloom for tomato or after thinning for cotton). • Sequential Re-use—Drain water is reused several times, each time being applied to progressively more salt tolerant plants.
Thus a range of salt tolerant forages, date palm and olive orchards, cereals and vegetables, as well as wood lot trees can be produced. Examples of these products are briefly discussed in Rhoades (1993).
A fifth method is the use of flood irrigated furrows using similar technology to the irrigation of many traditional crops. This has been successfully used for the production of Salicornia in a number of countries, particularly Mexico and the United Arab Emirates (Glenn et al., 1998; Brown and Glenn, 1999).
As the water available at Waikerie has a salinity of 20 mg/L only the sequential re-use system is considered suitable for a possible site identified adjacent to the SPDB.
10.6.5. Sequential Re-use Draining Model Benes et al., (1999) reported that many possibilities existed for combining crops and non- agronomic plants in sequential, drainage water re-use system. At each step in the re-use, species selection would be determined by plant tolerance to salinity and trace elements such as boron, and secondarily, by economic potential and farmer preference. For example, the first (primary) drainage might be applied to a salt tolerant crop such as cotton, sugar beets, or canola; the secondary drainage to a highly salt tolerant forage such as Bermuda-grass; the tertiary drainage to halophytes and lastly, drainage from the halophytes would be discharged into a solar evaporator (or at Waikerie the SPDB). The water is reused several times, each time being applied to progressively more salt tolerant plants. The objective is to reduce the volume of the water before it is discharged into a small area solar evaporator.
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In Benes et al., (1999) sequential re-use drainage model a very small portion of the farm, usually the least productive ground or an area with rising water table problems, is designated as the ‘Re-use Area’. With sequential re-use all drainage and salt is managed on-farm. Drainage lines must be installed in the re-use area, so that salts can be moved through the system and finally into the solar evaporator. The incorporation of these drainage lines significantly increases the capital cost of this system.
Blackwell et al. (2000) described ‘Sequential Biological Concentration’ for an integrated aquaculture system similar to Benes et al., (1999) re-use system and reported that their Filtration and Irrigated Cropping for Land Treatment and Effluent Reuse (FILTER, Figures 10.14 and 10.15) system may be capable of cleaning moderately saline aquaculture effluent prior to discharge.
Figure 10.14. Diagram of the FILTER system (Blackwell et al., 2000).
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Figure 10.15. Diagram showing how the FILTER system removes nitrogenous pollutants from water (Blackwell et al., 2000).
10.7. Efficiency of Halophyte Production Systems
10.7.1. Production O’Leary (1984) reported that the most productive halophytes such as Atriplex nummalaria have yielded the equivalent of 8 to 17 tonnes of dry matter per hectare; equivalent to 0.6 to 2.6 tonne of protein per hectare, which compares to that obtained for alfalfa irrigated with freshwater.
Simpson (undated) reported that researchers estimate that one hectare of Salicornia could sustain up to twenty goats or sheep.
The roots and stems of saltwort (Batis maritima) were used as food by the Seri Indians in the south-western US. Using seawater irrigation, dry weight yields of 17 tonnes per hectare have been obtained. A related species of saltwort Batis argillicola is found in tropical Australasia (http://en.wikipedia.org/wiki/Bataceae).
Glenn et al. (1998) reported that Salicornia farms had been established in California, Mexico (Figure 11.16), Saudi Arabia, Egypt, Pakistan and India. They reported average annual crops of Salicornia of 1.7 kg/m2 total biomass and 0.2 kg/m2 oilseed. These yields were stated to equal or exceed those of soybean and other oilseeds grown using freshwater irrigation.
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Figure 10.16. Seawater irrigated furrow cultivation of Salicornia on a large scale commercial farm on the west coast of Mexico (www.salicornia.com).
10.7.2. Nutrient Uptake Brown and Glenn (1999) calculated the area of halophytes needed to treat effluent from a pond. For example, the effluent water from the harvest of a one hectare 1.5 m deep shrimp (prawn) pond could be used to irrigate 18 hectares of halophytes for one week, or one hectare of halophytes for 18 weeks (water would be stored in a reservoir). If the shrimp pond was 1.5 m deep and discharged 20% of its water per week, then 2.5 hectares of halophytes would be needed. For a high end estimate, a 1.5 m deep shrimp pond discharging an average of 70% of its water per week would require about 13 hectares of halophytes for each hectare of pond.
10.7.3. Water Loss Benes et al. (2000) reported on the evapotranspiration (ET) of a range of halophytes and salt tolerant forages in such re-use systems in California. For a six week period in 1998 the ET of saltgrass (Distichlis sp.) irrigated with drain water (31 dSm-1, 19.8 g/L) averaged 63% of the ET of nonsaline fescue irrigated with canal water (0.5–0.9 dSm-1, 0.32–0.58 g/L). For this period Benes et al. (2000) reported that the ET for saltgrass was 7.6 mm/day, whilst that for nonsaline fescue (pasture grass) was 12.1 mm/day. For another six week period in 1999, the ET for saltgrass was 6.9 mm/day, whilst for saltbush (Atriplex sp.) it was 7.4 mm/day and for samphire (Salicornia bigelovii) it was 10.3 mm/day.
Rhoades (1993) reported an average annual evapotranspiration of about 20,000 m3/ha in Israel for a range of crops grown with saline water (2–8 dS/m in EC).
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10.7.4. Problems Although halophytes are salt tolerant, satisfactory growth occurs only within a suitable range of salinities. As water moves through the soil profile and past the plant roots, it gradually becomes more saline because the plants generally remove the water and leave the salts (Brown and Glenn, 1999). Thus excess water is required to flush salts below the plant root zone, thus there is a need in both the sequential reuse and the irrigated pasture systems to collect this flushing water if it is not to go to the water table.
This adds significant capital costs to either option, but most significantly to water reuse that requires pumps and associated infrastructure to move the water between different crops or evaporation ponds.
10.8. Conclusion and Recommendations The desired research cannot be achieved until satisfactory propagation or transplant methods for preferred salt-tolerant plants that thrive in saline groundwater (19–20 g/L) are developed. If time is available, it is recommended that seeds be used to produce the required potted plants for experiments. Once abundant healthy replicate potted plants are available then the most appropriate system for watering with and without finfish farm wastes can be established.
Once these methodologies have been resolved, factorial designed experiments can be used to measure the growth, nutrient uptake and water loss through evapotranspiration and irrigation. This initially needs to be done on a small experimental scale, as was proposed as part of this project, but subsequently needs to be done on a larger proof-of-concept scale, where perhaps a number of hectares of halophytes are planted in trial plots.
This information would assist the evaluation of the potential for large scale irrigated plantings to achieve a significant loss of volume of saline groundwater entering SIS disposal basins, as well as to reduce finfish farm waste water nutrient and suspended solid discharges into the SPDB.
The proposed research, conducted at the WISAC and SPDB, would potentially deliver the following commercially orientated outcomes: • reduce or remove the need to build a new disposal basin in the Riverland or alternatively enable the existing disposal basin to service an expanded SIS system • provide a potentially more cost effective and energy efficient biological nutrient and suspended solids removal system for aquaculture ventures using SIS water • produce additional crops with economic return from SIS waste water streams (these include oils and protein for stock or human consumption, as well as forage for stock and fibre for a range of products).
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10.9. References Benes, S.E., Grattan, S.R., Peters, D.W., Cervinka, V., Menezes, F. and Finch, C., 2000. Evapotranspiration and productivity of halophytes and salt tolerant forages proposed for drainage water re-use systems for California’s Westside San Joaquin Valley. Proceedings of Irrigation Australia 2000, 23–25 May, 2000. Irrigation Association of Australia. Benes, S.E., Peters, D. and Grattan, S.R. 1999. Integrated on-farm drainage management: using plant transpiration to reduce drainage volumes. California Agricultural Technology Institute (CATI) Publication #990602, pp. 1–4. Blackwell, J., Biswas, T.K., Jayawardane, N.S. and Townsend, J.T., 2000. A novel method for treating effluent from rural industries for use in integrated aquaculture systems.In: M.S. Kumar (Editor) National Workshop on Wastewater Treatment an Integrated Aquaculture Production, 17–19 September 1999. South Australian Research and Development Institute, West Beach, Adelaide, South Australia, pp. 80–92. Brown, J.J. and Glenn, E.P. 1999. Management of saline aquaculture effluent through the production of halophyte crops. World Aquaculture, December 1999, pp. 44–49. Glenn, E.P. 1991. Fodder that defies salt. Viewed 19 March 2008 http://fadr.msu.ru/rodale/agsieve/txt/vol4/issue3/art1.html> Glenn, E.P., Brown, J.J. and O’Leary, J.W. 1998. Irrigating crops with seawater. Scientific American, Vol. 279, No. 8, Aug. 1998, p. 56–61. Glenn E., Miyamoto, S., Moore, D., Brown, J.J., Lewis Thompson, T. & Brown, P. 1997. Water requirements for cultivating Salicornia bigelovii Torr. with seawater on sand in a coastal desert environment. Journal of Arid Environments 36: 711–730. Ellison, A.M. and Niklas, K.J. 1988. Branching patterns of Salicornia europea (chenopodiacae) at different succession stages: A comparison of theoretical and real plants. American Journal of Botany 75: 501–512. Flowers, T.J. and Hutchinson, W.G. 2005. Overseas travel report: Inland aquaculture study tour: USA and Israel, October 2004. CNRM Milestone Report 2005 Project No. 04/2004, South Australian Resarch and Development Institute, Adelaide, p. 50. Menterra. 2008. Gwynedd Council, Wales, UK. Viewed 19 March 2008.
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Simpson, D. Undated. Saline and arid agriculture for human and animal food production, sustainable agriculture for saline and arid soils—research and investigation of saline and arid tolerant plants. Castor & Pollux Biofuels & Biotechnologies. Viewed 16 March 2008.
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Chapter 11 – Conclusions and recommendations
11.1. General Conclusions The 12 month sampling program conducted to characterise the composition of saline groundwater from each of the major sections of the Woolpunda, Waikerie and Qualco- Sunlands SISs and the inflow to the Stockyard Plain Disposal Basin (SPDB) identified that the concentration of potassium was approximately 40% of the level found in similar salinity seawater. Potassium is an ion of physiological importance to fish and is often deficient in saline groundwater. The level of potassium identified in saline groundwater from the SIS sections and at the discharge point to the SPDB is sufficient to support growth of mulloway, a euryhaline species.
Bicarbonate and calcium were in excess for all SIS sections compared to equivalent salinity seawater. In samples taken from the Woolpunda and Waikerie SISs, and at the discharge point of the SPDB, the levels of sodium, chloride and sulphate were at similar levels to that found in equivalent salinity seawater. The levels of pH and magnesium were lower in all SIS groundwater samples than in equivalent salinity seawater.
The levels of most SIS groundwater components evaluated were relatively stable over the duration of the 12 month sampling period apart from a few changes for some components at a single sampling time. As typical for groundwater, there was moderate variability in the ionic composition between the different SIS pipeline sections. The Qualco-Sunlands SIS differed most, having the lowest sodium and chloride levels and thus salinity, and the highest calcium, fluoride, sulphate and silica levels and potassium:chloride ratio.
Trials were conducted to evaluate the growth, survival and metabolism of mulloway, snapper and yellowtail kingfish, all species of fish identified as having potential for commercial aquaculture using SIS groundwater. These trials demonstrated that growth and metabolism of mulloway were not significantly affected by the level of salinity and potassium of SIS groundwater collected from the discharge point of the SISs to the SPDB. It is suggested that this SIS groundwater can support levels of growth and performance of mulloway equivalent to those achieved by fish cultured in seawater diluted to a similar salinity or in seawater.
Saline groundwater sourced from the discharge point of the SISs to the SPDB also appears to be suitable for the culture of yellowtail kingfish. Results achieved in experimental conditions showed that yellowtail kingfish grow equally well in SIS groundwater, diluted seawater and potassium-supplemented SIS groundwater, as they do in seawater. The metabolic rate of yellowtail kingfish cultured in SIS groundwater over 21 days was not abnormally affected in the experiment undertaken and the level of potassium and the potassium:chloride ratio found in the SIS groundwater did not significantly limit growth. In both growth trials conducted there was a trend for yellowtail kingfish to perform better in diluted seawater.
Experiments conducted showed a significant reduction in growth and increase in RMR for snapper cultured in groundwater collected from the discharge point of the SISs to the SPDB compared to diluted seawater. These results indicate that snapper prefer diluted seawater to
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this groundwater and it is suggested that it is not viable to culture snapper in raw SPDB groundwater.
High survival of mulloway was achieved during demonstration of production trials conducted. SGR and FCR data from these trials indicate performance of mulloway in the semi-intensive aquaculture system utilising SIS groundwater was comparable to results achieved with this species in other studies and was comparable to the growth performance of other species cultured commercially in South Australia and internationally. In addition, growth of mulloway in SIS groundwater was faster than for the same species cultured in seacages and in the wild.
Testing of flesh of mulloway cultured in SIS groundwater showed no elevated levels of pesticides, antimicrobials, metals, PCBs or dioxins. These data and feedback from chefs, seafood processors and consumers confirm that mulloway cultured using SIS groundwater is a readily accepted, high quality seafood product.
It was identified that the temperature of saline groundwater from the Woolpunda SIS varied seasonally ranging from 17.9 oC to 28.8 oC. Salinity of this water remained constant around a mean of 20.45 ± 0.01 g/L (±SE). The mean concentration of dissolved oxygen in the SIS groundwater used was 5.0 ± 0.1% saturation. Dissolved CO2 was the most variable parameter ranging form 44.5 mg/L to 117 mg/L and this influenced the pH of the water resulting in a range recorded between 6.54 and 7.08. Pre-treatment of the SIS groundwater by degassing increased dissolved oxygen to 89.6 ± 0.4 % saturation. Post-degassing levels of dissolved CO2 were 17.5 ± 0.3 mg/L and the pH was 6.82 ± 0.00.
Feed was identified to be the largest production cost for mulloway cultured in the semi- intensive aquaculture system at WISAC, followed by electricity and oxygen. It is considered that there is potential to reduce feed costs by improving FCR through ongoing refinement of feed management and improved system operation (i.e. to reduce dissolved CO2). Electricity is also a major cost that could be significantly reduced using more intensive aquaculture systems that use less exchange water, and by selecting sites for commercial developments at locations that allow discharge of water with reduced or zero pumping requirements.
No seasonal changes to the growth rate of mulloway were observed during the proof of concept production trials conducted at WISC. It is believed that the SIS groundwater temperature advantage available at WISAC is being limited by the elevated levels of dissolved CO2 characteristic of this same water, as well as an increase in the concentration of dissolved CO2 within the culture tanks because of the system design and manner of operation. A trial was conducted which demonstrated that the growth performance, and ultimately survival, of mulloway is impacted by the elevated concentration of dissolved CO2 found in the SIS groundwater. The results show that performance of mulloway was best at the lowest concentration of dissolved CO2 investigated (6 mg CO2/L) indicating that improved growth will be achieved in an aquaculture system which includes water treatment components that allow for further management of dissolved CO2.
Investigations conducted on the use of a local halophyte for treatment of waste water identified the need to develop better methods for propagation of plants for use in experiments
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to allow further investigations to be pursued to provide nutrient and suspended solids removal, and reduction of the volume of water discharged to the disposal basin.
11.2. General Recommendations From the results of this report, it is considered that the groundwater available from the Woolpunda SIS provides a significant opportunity for aquaculture. It has been demonstrated that mulloway has the potential to be further developed as a commercial aquaculture species to exploit the saline groundwater available from SISs in the Riverland.
Although survival was high, it is considered that growth of mulloway in SIS groundwater could be further improved. Results achieved to date suggest that further research is required to gain a greater understanding of feeding and other requirements of mulloway during different stages of growth within different aquaculture systems and environmental conditions. Further improvement in feed management and production system operation may assist the ability to achieve consistent periods of maximum growth (SGR) and body condition during which feed utilisation (FCR) is optimised.
Future research needs to be undertaken to reduce production costs for mulloway cultured in the semi-intensive aquaculture system at WISAC. This research should target reduction of FCR through ongoing improvement of feed management and improved system operation (i.e. reduced dissolved CO2).
The sale of mulloway from the proof of concept trials undertaken at WISAC highlighted that seafood wholesalers preferred a larger size of fish, 1.5-2.0 kg, rather than 750 g.
Experiments conducted showed growth and metabolism of snapper is adversely affected in SIS groundwater from SPDB and, as such, it is recommended that this species should not be considered for commercial aquaculture using SIS groundwater. Alternatively, this species could be considered in an intensive aquaculture system using reduced water exchange to allow supplementation of potassium to maintain the level desired by this species.
It has been shown that yellowtail kingfish grow well in SIS groundwater and in diluted seawater. Preliminary batches of fingerlings transferred to WISAC showed ongoing mortality attributed to the semi-intensive system providing sub-optimal conditions for this species. Further research will be required to determine the optimum conditions and production system appropriate for culture of yellowtail kingfish using WISAC SIS groundwater.
The parameters measured for the incoming SIS groundwater indicated that management of dissolved CO2 and oxygen need to be considered during the design of a commercial aquaculture facility. Installation of appropriate water treatment components will be required to manage these parameters for incoming water and within the culture system. It is recommended that further investigations be conducted on options to minimise dissolved CO2, as growth of mulloway has been shown to be best at low levels (i.e. < 6 mg/L). Until this issue is resolved the potential growth performance of mulloway, and of other species, in the available SIS groundwater is unlikely to be fully realised. It is expected that a more intensive
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aquaculture system would incorporate components (i.e. degassers, aeration) that would allow greater capacity to manage dissolved CO2 and oxygen, while retaining the thermal advantage of the available SIS groundwater.
As electricity is a significant operating cost, any commercial aquaculture development using saline groundwater from SISs should consider the adoption of a more intensive aquaculture system. Intensive aquaculture systems are likely to require significant electricity use to operate pumps and water treatment components. However, this will be offset by selection of an energy efficient system that provides greater production from the available SIS groundwater. To further reduce operating costs, commercial ventures should also select a location that allows discharge of exchange water without the need for pumping to further reduce electricity costs.
Any future use of SIS groundwater for commercial aquaculture will need to incorporate methods to manage waste nutrients in discharged SIS groundwater. Preliminary trials on the use of local halophytes were not successful and the desired research cannot be achieved until satisfactory propagation or transplant methods are developed. It is recommended that future research should commence with development of methods to propagate seedlings to supply replicate potted plants to investigate irrigation methods, growth, transpiration rates and nutrient uptake of selected halophyte species grown using wastewater from aquaculture systems utilising SIS groundwater. This initially needs to be done on a small experimental scale, as originally proposed as part of this project, but subsequently needs to be done on a larger proof-of-concept scale, where perhaps a number of hectares of halophytes are planted in trial plots. The proposed research would potentially deliver the following commercially orientated outcomes: 1. A significant loss of volume of saline groundwater entering SIS disposal basins to reduce or remove the need to build a new disposal basin in the Riverland, or alternatively enable the existing disposal basin to service an expanded SIS system. 2. Provide a potentially more cost effective and energy efficient biological nutrient and suspended solids removal system for aquaculture ventures using SIS water. 3. Produce additional crops with economic return from SIS waste water streams (these include oils and protein for stock or human consumption, as well as forage for stock and fibre for a range of products).
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