Baseline Status of Subtidal Reefs and Associated Biodiversity Patterns in the AMLR Region
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Subtidal Reef Health Program: Baseline status of subtidal reefs and associated biodiversity patterns in the AMLR region. James Brook, Kristian Peters, Simon Bryars, Sam Owen, Jamie Hicks, David Miller, Daniel Easton, Yvette Eglington, Craig Meakin and Danny Brock Department for Environment and Water February, 2020 DEW Technical report DEW-TR-2020-01 Department for Environment and Water GPO Box 1047, Adelaide SA 5001 Telephone National (08) 8463 6946 International +61 8 8463 6946 Fax National (08) 8463 6999 International +61 8 8463 6999 Website www.environment.sa.gov.au Disclaimer The Department for Environment and Water and its employees do not warrant or make any representation regarding the use, or results of the use, of the information contained herein as regards to its correctness, accuracy, reliability, currency or otherwise. The Department for Environment and Water and its employees expressly disclaims all liability or responsibility to any person using the information or advice. Information contained in this document is correct at the time of writing. With the exception of the Piping Shrike emblem, other material or devices protected by Aboriginal rights or a trademark, and subject to review by the Government of South Australia at all times, the content of this document is licensed under the Creative Commons Attribution 4.0 Licence. All other rights are reserved. © Crown in right of the State of South Australia, through the Department for Environment and Water 2020 ISBN 978-1-925964-30-1 Preferred way to cite this publication Brook J, Peters K, Bryars S, Owen S, Hicks J, Miller D, Easton D, Eglington Y, Meakin C & Brock D (2020). Subtidal Reef Health Program: Baseline status of subtidal reefs and associated biodiversity patterns in the AMLR, DEW Technical report DEW-TR-2020-01, Government of South Australia, Department for Environment and Water, Adelaide. Download this document at https://data.environment.sa.gov.au Cover photograph: Danny Brock, Ornate cowfish (Arcana ornata) DEW Technical report 2020/01 i Contents Executive Summary vii 1 Introduction 10 1.1 Subtidal Rocky Reefs 10 1.2 Natural resources management framework 10 1.3 Health of Rocky Reefs in the AMLR region 11 1.4 Subtidal Reef Health Program 11 1.5 Objectives 12 2 Methods 13 2.1 Baseline data collection 13 2.2 Indicators of Reef status 15 2.2.1 Rationale 15 2.2.2 Definition and context of indicators 18 2.3 Evaluation of monitoring sites 20 3 Characteristics of AMLR reefs 23 3.1 Physical characteristics 23 3.2 Macroalgal communities 23 3.2.1 General features 23 3.2.2 Subregional features 24 3.3 Fish communities 25 3.3.1 General features 25 3.3.2 Subregional features 27 3.4 Mobile invertebrate communities 28 3.4.1 General features 28 3.4.2 Subregional features 29 4 Fish species of conservation concern 31 5 Baseline status of reef monitoring sites 36 5.1 Macroalgae and sessile invertebrates 36 5.1.1 Richness of functional groups 36 5.1.2 Macroalgal community structure 37 5.1.3 Cover of canopy-forming macroalgae 37 5.2 Fish 38 5.2.1 Species richness 38 5.2.2 Biomass of large fish 39 5.2.3 Biomass of targeted fish 40 5.2.4 Fish community structure 41 5.2.5 Community temperature index 42 5.2.6 Focal fish species 44 5.3 Invertebrates 48 5.3.1 Species richness 48 5.3.2 Mobile invertebrate community structure 49 DEW Technical report 2020/01 ii 5.3.3 Focal species 49 6 Evaluation of long term monitoring sites 54 6.1 Review of representative criteria 54 6.2 Review of catchment discharge criteria 54 6.3 Evaluation of monitoring sites 57 7 Conclusions 60 7.1 Overview 60 7.2 Subregional approach will improve management of subtidal reefs 60 7.3 Regional baseline established for future monitoring 60 7.4 Macroalgal communities 61 7.5 Fish communities 61 7.6 Mobile invertebrate biodiversity 62 7.7 Introduced Marine Pests 63 7.8 Catchment impacts 63 7.9 Site evaluation 64 7.10 Contribution to NRM reporting and ecosystem assessment 64 8 Recommendations 65 9 Appendices 67 A. Sites surveyed 68 B. Details of indicator calculations and interpretation notes 69 C. Species lists 72 D. Outputs from PRIMER/PERMANOVA+ 79 E. Baseline condition of subregions and sites in the AMLR region 87 10 Units of measurement 97 10.1 Units of measurement commonly used (SI and non-SI Australian legal) 97 11 Glossary 98 12 References 98 DEW Technical report 2020/01 iii List of figures Figure 1. Sites surveyed during 2017 and 2018 in relation to subregions, catchments and river discharges 14 Figure 2. Summary of evaluation of sites selected for long term monitoring 21 Figure 3. MDS plot of macroalgal communities by site. Symbol/colour combinations distinguish 41 individual sites, each of which was surveyed in 2017 and 2018. The symbol used to represent each site is shown in Appendix A. 24 Figure 4. MDS plot of macroalgal communities by AMLR subregion. Outliers from subregions are labelled using abbreviations listed in Appendix A. 25 Figure 5. Fish species with the highest abundance and biomass from reef surveys in 2017 and 2018. 26 Figure 6. MDS plot of fish communities by site. Symbol/colour combinations distinguish 41 individual sites, each of which was surveyed in 2017 and 2018. The symbol used to represent each site is shown in Appendix A. 27 Figure 7. MDS plot of fish communities by AMLR subregion. Outliers from subregions are labelled using abbreviations listed in Appendix A. 28 Figure 8. MDS plot of mobile invertebrate communities by site. Symbol/colour combinations distinguish 41 individual sites, each of which was surveyed in 2017 and 2018. The symbol used to represent each site is shown in Appendix A. 29 Figure 9. MDS plot of mobile invertebrate communities by AMLR subregion. Outliers from subregions are labelled using abbreviations listed in Appendix A. 30 Figure 10. Richness of macroalgal functional groups by subregion and year 36 Figure 11. Richness of macroalgal functional groups by site and year. Site names corresponding to abbreviation are provided in Appendix A. 37 Figure 12. Percentage cover of canopy-forming macroalgae by subregion and year 38 Figure 13. Percentage cover of canopy-forming macroalgae by site and year. Site names corresponding to abbreviation are provided in Appendix A. 38 Figure 14. Richness of fish species by subregion and year 39 Figure 15. Richness of fish species by site and year. Note that fish surveys (method 1) were not undertaken at Port Elliot Deep (PED) in 2017. Site names corresponding to abbreviation are provided in Appendix A. 39 Figure 16. Biomass of large (>20 cm) fish by subregion and year 40 Figure 17. Biomass of large (>20 cm) fish by site and year. Site names corresponding to abbreviation are provided in Appendix A. 40 Figure 18. Biomass of targeted fish by subregion and year 41 Figure 19. Biomass of targeted fish by site and year. Site names corresponding to abbreviation are provided in Appendix A. 41 Figure 20. Community temperature index for fish by subregion and year 42 Figure 21. Community temperature index for fish by site and year. Site names corresponding to abbreviation are provided in Appendix A. 43 Figure 22. Mean abundance of blue groper (per block) by subregion and year. Error bars show standard error of mean abundance across individual sites. 44 Figure 23. Mean abundance of blue groper (per block) by site and year. Error bars show standard error of mean abundance across four contiguous 50 m transects. Site names corresponding to abbreviation are provided in Appendix A. 44 Figure 24. Mean abundance of southern blue devil (per 50 m block) by subregion and year. Error bars show standard error of mean abundance across individual sites. 45 DEW Technical report 2020/01 iv Figure 25. Mean abundance of southern blue devil (per 50 m block) by site and year. Error bars show standard error of mean abundance across four contiguous 50 m transects. Site names corresponding to abbreviation are provided in Appendix A. 45 Figure 26. Mean abundance of bluethroat wrasse (per block) by subregion and year. Error bars show standard error of mean abundance across individual sites. 46 Figure 27. Mean abundance of bluethroat wrasse (per block) by site and year. Error bars show standard error of mean abundance across four contiguous 50 m transects. Site names corresponding to abbreviation are provided in Appendix A. 46 Figure 28. Mean abundance of sea sweep (per block) by site and year. Error bars show standard error of mean abundance across individual sites. 47 Figure 29. Mean abundance of sea sweep (per 50 m block) by subregion and year. Error bars show standard error of mean abundance across four contiguous 50 m transects. Site names corresponding to abbreviation are provided in Appendix A. 47 Figure 30. Richness of mobile invertebrates by subregion and year 48 Figure 31. Richness of mobile invertebrates by site and year. Site names corresponding to abbreviation are provided in Appendix A. 49 Figure 32. Density of abalone (per 50 m2 block) by subregion and year. Error bars show standard error of mean abundance across individual sites. 50 Figure 33. Density of abalone (per 50 m2block) by site and year. Error bars show standard error of mean abundance across four contiguous 50 m transects. Site names corresponding to abbreviation are provided in Appendix A. 50 Figure 34. Density of southern rock lobster (per 50 m2 block) by subregion and year. Error bars show standard error of mean abundance across individual sites. 51 Figure 35.