Songkhla , environment related to fisheries and aquaculture

NIKHOM LA-ONGSIRIWONG Narathiwat Coastal Aquaculture Research and Development Center Department of Fisheries, Overview topics

• I. General information of Songkhla lake – Characteristics of Songkhla lake – Climate characteristics – Fisheries resources and Fisheries activities – Problems in Songkhla lake • II. Important environmental aspects in Songkhla lake – DO – Salinity – Chlorophyll a Overview topics (con.)

• III. Effects of environment on fisheries and aquaculture in Songkhla lake – Oxygen depletion – Salinity – Eutrophication condition I. General information of Songkhla lake Characteristics of Songkhla lake

• Unique lagoon in Thailand and one of 117 lagoonal in the world • Located at southern region of Thailand in the provinces of Songkhla and Pattalung • Largest lagoonal water in Thailand and Southeast Asia with a total area of 986.8 km2 (98, 680 ha) • Devided into 4 parts : Thale Noi, Upper lake, Middle lake and Outer lake Figure 1. Map showing Songkhla lake in Table 1.Some morphometric data on the Songkhla lakes (at 0 m MSL)

Division Thale Noi Inner lake Middle lake Outer lake

Surface 28 459 377 176 area(km2)

Mean 1.0 1.9 1.1 1.5 depth(m)

Retention 27 55 28 15 time(days)

Salinty 0-1 0-11 0-30 0-33 range Nakorn Srithammarat

Thale Noi

Characteristics of Upper lake 1.8 m Songkhla Lake Basin 491 km2 P h a t t h a l u n g

1.0 m 376 km2 Middle lake

Outerlake Basin area 9,807 km2 1.3 m Lake Properties: 190 km2 Area 1,182 km2 Length ~80 km S on g k h l a Width ~22 km

S a t u n

tapao river tapao -

Thale Sap U Songkhla Klong Luang Thale Sap Thale Luang

M A L A Y S I A

Pak Payoon Pak

Entrance

Pak Ro Pak

Ko Yo Ko Depth (m) Depth Characteristics of Songkhla lake (con.) • Thale Noi – The upper most part of the lake – The smallest of four parts with a total area of 28 km2 – A freshwater lagoon located in Pattalung province – Densely populated by various aquatic macrophytes – Very shallow lake; 1 meter in depth Figure 2. Scenery of Thale Noi Characteristics of Songkhla lake (con.) • Upper lake – Located adjacent to the southern part of Thale Noi – The largest part of the lake with a total area of 459 km2 – Normally oligohaline brackish water nearly over the year but maximum salinity may be reached to > 11 psu in the end slightly rainy season of the drought year – Deepest with an average 2 meters – Highly eutrophic condition Figure 3. Dark green color of water in Upper lake showing eutrophication problem Characteristics of Songkhla lake (con.) • Middle lake – Covers a total area of 377 km2 – Average depth only 1 m. – Mixing zone between fresh and seawater – Connected to Outer lake with deep narrow canal – Eastern coast is populated by various aquatic macrophytes – Irregulary blooming of macrophytes (Najas sp.) and macroalgae (Cladophora sp. and Enteromorpha sp.) in 2003 and 2004 Figure 4. Sceneries of the Middle lake Figure 5. Blooming of macrophytes (Najas sp.) and macroalgae (Cladophora sp. and Enteromorpha sp.) in the Middle lake occurred in 2003 and 2004 Characteristics of Songkhla lake (con.) • Thale Sap Ton Nok – Covers a total area of 176 km2 – Average depth about 1.5 m. – Connected to the Gulf of Thailand – Dense with fishing gears and fish-cage culture – Surrounded with human activities • Port (deep sea port and fishing port) • Fisheries • Industries • Cities (Songkhla, Hat Yai) 07 16 44

ST 7

ST 1

ST 5 07 11 06 ST 6 ST 8 ST 3

ST 2 ST 9 ST 4

ST 11 ST 10

07 06 31 100 23 06 100 29 22 100 35 51

Figure 6. Map showng the Outer lake Figure 6. Activities in the Outer lake Figure 6. (con) Climate characteristics of Songkhla lake

• Equatorial monsoon climate • High temperature exist all year round • The average, range of weather temperature is 27.5 oC, 23.8-31.5 oC • The coolest month is in December with a mean average temperature of 26 oC and hottest month in April (31 oC) • the average total annual fall is 1,965 mm. • About 60% of the total annual rainfall normally occurs from October to December Monthly Rain at Hat Yai City, Songkhla

300 mm

100 mm Rainfall (mm) Rainfall Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Climate characteristics of Songkhla lake (con.)

• 2 season : Dry season and Wet season • Dry season : the middle of February to the middle of May • Wet season is divided into 2 periods – A light rainy period : effected by the southwest monsoon (from the middle of May to the middle of October) – A heavy rainy period : effected by the northeast monson (from the middle of October to the middle of February) Fisheries resources and fishing activities in Songkhla lake • In the past, one of the most abundance of aquatic animals • 700 species of fish, crab, shellfish and prawn • Dominant species – 43 estuarine species : Lates calcarifer, Plotosus canius, Mugil sp., Arius sp. – 19 freshwater species : Macrobrachium rosenbergii, Clarias spp. M. ensis P. merguiensis

Plotosus canius

Figure 7. Some commonly economical fishes in Songkhla Lake Scatophagus augus Lates calcarifer

Arius sp. Arius sp. Figure 7. (con) Chana striata Clarias spp.

Macrobrachium rosenbergii

Figure 7. (con.) Fishery activities in Songkhla lake

• 2 types of fishery activities : aquaculture and capture fishery • Capture fishery – At least 7,000 tons of fish per year caught from the Songkhla lake • Thale Noi : 528 tons, all • Upper lake : 300-1000 tons, mainly fresh water fish but occasionally brackish water fish • Middle lake : 700-1300 tons, mostly marine shrimp (Penaeus merguiensis and Metapenaeus spp.) • Outer lake : 2000-4000 tons, mostly marine shrimps and brackish water fish Fishery activities in Songkhla lake (con.) • Capture fishery (con.) – Quantity of capture fishery in the lake now lower than in the past probably due to illegal fishing and environmental degradation – Fishing gears : stationary gears and moving gears – Stationary gears :standing trap, set bag – Moving gears : gill net, hook, scoop net Figure 8. Some commonly stationary gears in Outer Lake Figure 9. Standing trap in Songkhla Lake Fishery activities in Songkhla lake (con.) • Capture fishery (con.) – Common size of captured fishes was small

• Metapenaeus ensis : 5.5-5.9 cm (TL) juveniles • Swimming crab: 6.5-7.5 cm (carapace length) – Abundance of captured fishes by standing trap depend on salinity trap gill net

scoop net Figure 10. Some commonly moving gears in Outer Lake Fishery activities in Songkhla lake (con.) • Aquaculture : shrimp farming and fish- cage culture • Shrimp farming – First established in 1988-1989 – Intensive culture – About 1,372 hectares, 1412 tons – all white shrimp Figure 11. Cultured-species of shrimp in Songkhla lake area and earthen ponds for shrimp culture Fishery activities in Songkhla lake (con.) • fish-cage culture – First practiced in 1980 at Ban Bor Keng near the lake mouth – Rapidly expanded and now > 7,000 cages, 1,100 farmers was established in Outer lake – Mostly seabass (Lates calcarifer) culture – The fisheries farmers always face problem of fish mortality since 1986 Figure 12. Netcages Figure 13. Seabass culture Mari-culture activities

Khao Khieo

Mari-culture Hua Khao (No. of cages): Ko Yo ~ 1,854 Hua Kao Dang ~479 Kao Keaw ~593 Ko Yo Seabass Mari- culture

1997 Vel. Meas.

2005-6 Vel. Meas. Problems in Songkhla lake

• Shallowness Water level in Songkhla lake system Thale Noi

Gulf of Thailand Upper lake

Songkhla Lake Andaman Sea Middle lake Gulf of Thailand

Ko Nu Outer lake Ko Yo 2.5

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average depth is 0.9-2.2 m. with a minimum in August and maximum in December Problems in Songkhla lake

• Pollutions – Community – Industry – aquaculture Problems in Songkhla lake • Construction of stationary fishing gear – Standing trap 1984 : 700-900 traps 1993 : 8,750 traps 2005 : >20,000 traps – set bag : 1979 : 1,029 units 2005 : >2,300 units Problems in Songkhla lake

• eutrophication Problems in Songkhla lake

• Declination of fishery resources – Extinction : Dugong, turtle – Endangered species : Clarias sp. (Orcaella brevirostris),Puntius schwanenfeldi – Decreasing of catch effort and captured size • Standing trap: 1984 1.46 kg/day 2005 0.67 kg/day II. Important environmental aspects in Songkhla lake Dissolved Oxygen (DO)

• Very important and sensitive indicator of the health of aquatic systems • Provides key information about the system state -Algal blooms -Oxygen depletion • Low DO can cause the loss of aquatic animals Surface Exchange

Photosynthesis -Algae -Fe2+ -Macrophyte Dissolved -Mn2+ Respiration Oxygen Oxidation -S2- -NH4+ -Fish Respiration -Zooplankton Decomposition

-Organic Matter -SOD

Figure 14. Process effecting dissolved oxygen content Sources : GÖnenç and Wolflin (2005) Dissolved Oxygen (DO)(con.)

• spatial and seasonal fluctuation in Songkhla lake • Varies wide limits in Upper lake • Lower than criteria value for normal fish growth (4.8 mg/l) in the vinicity of fish-cage • In the restricted water exchange areas, oxygen depletion can be occurred at dawn, especially when the wind calm and neap tide • oxygen depletion in Songkhla lake sometimes caused by eutrophication 7.80 53 85 7.70

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88 91 7.30 90 89 86 7.20 91 89 91 82 81 67 77 7.10 100.10 100.20 100.30 100.40 100.50 100.60 longitude (E) Figure 15. Spatial distribution of DO content (% saturation) in Songkhla lake 7.80 7.80 7.80

101 105 91 7.70 7.70 7.70

110 107 103 7.60 98 7.60 94 7.60 100 105 99 97

7.50 105 7.50 112 7.50 95 105 103 104

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t t t

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t t t

a a a l 88 l 88 l 94 7.40 101 7.40 96 7.40 99

93 94 90 102 88 89 7.30 7.30 7.30

88 89 96 7.20 90 96 7.20 91 95 7.20 94 90 93 93 95 82 83 78 82 80 83

7.10 7.10 7.10 100.10 100.20 100.30 100.40 100.50 100.60 100.10 100.20 100.30 100.40 100.50 100.60 100.10 100.20 100.30 100.40 100.50 100.60 longitude longitude longitude

Figure 16. Spatial-seasonal distribution of DO content (% saturation) in Songkhla lake 10 9 At the vinicity of fish-cage in Outer lake 8 7 6 5 mg/L 4 3 2 1 0 18 19 20 21 22 23 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 time 10 In Upper lake 8 6

mg/L 4 2 0

1:00 4:00 7:00

1:00 4:00 7:00

16:00 19:00 22:00

10:00 13:00 16:00 19:00 22:00

10:00 13:00 time Figure 17. Diurnal change of DO content in Songkhla lake Important environmental aspects in Songkhla lake (con.)

• Salinity – “the total quantity of dissloved salts in seawater” – Vary widely in Songkhla lake which are affected by tidal flow, freshwater runoff – Spatial and seasonal variation with precipitation and the distance away from the sea – Before 2006, salinity in the Outer lake usually sharply rised in the beginning of hot season (February) – Unnormal change of salinity in Songkhla lake was occured since 2006 7.80

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9.5 7.5 7.30 8.5 9.1 9.4 7.20 11.0 24.0 14.7 19.620.6 7.0 18.0 7.10 100.10 100.20 100.30 100.40 100.50 100.60 longitude

Figure 18. Spatial distribution of salinity in Songkhla lake 7.80 7.80 7.80 0.4 1.0 0.3 0.5 0.9 0.9 7.70 7.70 7.70

0.6 1.1 1.4

7.60 0.6 0.6 7.60 1.3 1.2 7.60 0.9 1.7

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9.4 13.0 2.6 6.0 10.7 1.8 7.30 7.30 7.30 8.7 11.1 2.7 8.8 12.1 2.6 8.5 13.1 2.2 7.20 7.20 2.5 7.20 8.9 24.3 16.3 29.8 11.3 16.2 4.2 18.9 7.7 21.021.9 25.026.1 6.6 9.4 9.0 0.5 4.0 7.10 19.6 7.10 23.8 7.10 100.10 100.20 100.30 100.40 100.50 100.60 100.10 100.20 100.30 100.40 100.50 100.60 100.10 100.20 100.30 100.40 100.50 100.60 longitude (E) longitude (E) longitude (E)

Figure 19. Spatial-seasonal distribution of salinity in Songkhla lake 40 1400

35 1200 30 1000 25 800 20

PSU 600 mm. 15 400 10

5 200

0 0

Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05Jul-05Oct-05Jan-06Apr-06Jul-06Oct-06Jan-07Apr-07Jul-07Oct-07

salinity rain

Figure 20. Variation of salinity and rainfall in Outer Songkhla lake during 2003-2007 Salinity Intrusion in Songkhla Lake System, 1997

20 ppt

5 ppt Important environmental aspects in Songkhla lake (con.)

• Chlorophyll a – The photosynthetic pigments of plants – Various chlorophyll, identified by symbols a, b, c, d occur in water plants – Chlorophyll a is the most important; it indicated biomass of phytoplankton – Indicator of eutrophication; > 10 μg/l – Spatial-temporal typically change of chlorophyll a level in Songkhla lake was found Important environmental aspects in Songkhla lake (con.)

• Chlorophyll a (con.) – In Upper lake, typically higher than 30-40 μg/l over the year and maximum as 180 μg/l was recorded – At the fish-cage culture area, normally lower than 10 μg/l but sometime may be reached to 160 μg/l – In Outer lake, chlorophyll a level in heavy rainy period often found higher than others 7.80

22.75 43.63 7.70

40.42 29.58 7.60 37.49

7.50 9.87 30.89

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3.86 10.58 7.30 9.25 9.38 9.09 7.20 8.21 7.53 9.96 8.228.95 14.43 17.55 7.10 100.10 100.20 100.30 100.40 100.50 100.60 longitude Figure 21. Spatial distribution of chlorophyll a level in Songkhla lake 7.80 7.80 7.80

18.1 29.1 14.1 37.9 54.6 25.6 7.70 7.70 7.70

30.1 47.4 35.5 7.60 22.6 7.60 34.1 7.60 27.1 31.5 42.3 29.8

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3.3 2.9 6.3 7.3 10.4 14.2 7.30 7.30 7.30 5.8 8.3 14.3 6.9 7.8 14.7 8.0 7.6 13.2 7.20 12.0 8.1 7.20 6.1 5.9 7.20 8.8 10.4 8.8 8.7 13.7 7.8 8.9 6.5 7.3 12.212.4 15.4 16.1 9.9 13.5 17.2 22.1 7.10 7.10 7.10 100.10 100.20 100.30 100.40 100.50 100.60 100.10 100.20 100.30 100.40 100.50 100.60 100.10 100.20 100.30 100.40 100.50 100.60 longitude (E) longitude (E) longituude (E)

Figure 22. Spatial seasonal distribution of chlorophyll a level in Songkhla lake III. Impact of environment on fisheries and aquaculture Salinity

• Effected to fish distribution and sea bass culture • Migration of fish – Food, breeding and spawning, environmental adaptation • Fish distribution in Songkhla lake – Freshwater group, salinity <0.5 ppt – Estuarine group or brackish group, salinity 0.5-33 ppt – Marine group, salinity >33 ppt • 3 groups of aquatic fauna – Resident – Migrant – displacement Salinity of environment

Reproduction success Distribution (function of salinity (function of tolerance and osmoregu- preference and tolerance) latory ability)

Eggs Larvae Migration orientation (response Survival To salinity gradients)

Eggs Juveniles Adults Distribution Larvae

Juveniles

Abundance to fishery Recruitment

Abundance to spawning stock

Figure 23. Influence of environmental salinity on the distribution and abundance of fish FRESHWATER ESTUARINE INSHORE

Mysis postlarvae Protozoea

nauplii PELAGIC

eggs

juveniles Spawning

adults DEMERSAL

Figure 25. Life cycle of Metapenaeus brevicornis in Songkhla lake FRESHWATER ESTUARINE INSHORE

postlarvae juveniles Mysis PELAGIC Protozoea nauplii

eggs Spawning Spawning adults

adults DEMERSAL

Figure 26. Life cycle of Metapenaeus tenuipes in Songkhla lake Oxygen depletion

• Normally occured at fish-cage-vinicity in Outer lake but seldomly found in other areas e.g. Upper lake • Normally caused by several factors as co-factors – Fish respiration – Tidal flow (blocked by the dense of fish cage) – Water level – Wind (reaeration) – Algal bloom • Usually found lowest DO content at dawn Oct. 2005

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Fig. 5 : Time-Variation of Water Level, Velocity, Water Temperature, Salinity and DO 0.25 0.20

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Figure 27. speed fluctuation in mari-culture area at Ko Yo Island, Outer lake Thailand air

DO available Current dispersion Oxygen consumption Water level air stagnant Oxygen consumption DO available

Water level Benthic DO Flux Flux DO

sediment sediment

Figure 29. Effects of DO depletion to seabass culture Figure 30. Mass mortallity of fishes caused by oxygen depletion (top : cultured fish; bottom : natural fish) Figure 31. Aeration with long-tail boat motor Eutrophication

• First reported in the data book of the world lake by Kira (1984) • Overfertilization of nitrogen and phosphorus that come from , municipality, industry and aquaculture • One major caused of fish resources declining in Songkhla lake • Serious problem now in Songkhla lake Figure 32. Dark green of water color showing phytoplankton bloom result in high DO and pH in daily light Figure 33. Macro algae bloom in Middle lake (2002-2004) and Outer lake (2008) (bottom right) Figure 33. Rapid growth of macrophyte in Middle lake during 2002-2004 Figure 34. Color of oxic sediment (upper left ) and anoxic sediment (upper light) bottom : anoxic sediment caused by degradation of macro algae Thank you for your attention