Use of mangroves for control of effluent from intensive fish and shrimp culture in artificial wetlands

Transcription

1 Use of mangroves for control of effluent from intensive fish and shrimp culture in artificial wetlands G Z Chen a *, Y S Peng a, Y G Peng ab a School of Environmental Science and Engineering, Sun Yat-sen University Guangzhou, China PR, ; b College of Forestry, South China Agricultural University Guangzhou, China PR, *Author for correspondence Nov. 28 th, 2007 Bangkok, Thailand

2 1 Introduction Aquatic product: important source of human foodstuff. Economic development & population increase demand for aquatic product: accelerating upwards Aquaculture: developing rapidly Increase in scale and intensity of aquaculture Land-based pollution getting worse

3 Aquaculture pollutants mainly organic nutrient materials, cause eutrophication & anoxia (directly), increase aquaculture diseases (indirectly) seriously affects the sustainable development of aquaculture Establishment of Integrated Salt-tolerant Plant (Mangrove) - Aquaculture Wetland Systems (IMAS): To enhance self-purification of aquaculture ponds; accelerate decomposition, transformation and assimilation of pollutants; improve water quality; reduce aquaculture diseases; increase aquatic production; elevate aquatic product quality.

4 2 Establishment of Integrated Mangrove Aquaculture Systems (IMAS) Component of IMAS: Ponds 34 hectares of ponds, in the Shenzhen Waterlands Resort, eastern coast of Pearl River Estuary Wetland Mangroves Nine experimental ponds (titled A, B & C, with mangroves) vs one control pond (titled D, without mangroves) three species - Sonneratia caseolaris (Sc), Kandelia obovata (Ko), Aegiceras corniculatum (Ac) were planted as monoculture in each pond with area proportion of 45%, 30% or 15%, respectively. Aquaculture animals Sciaenops ocellatus, Labidochromis flavigulus, Scylla serrata were fed in all ponds.

5 Channel No. 1 G1 G2 Core area for tour of Shenzhen Waterlands Tourism Development Ltd. Channel No. 2 A2 A3 B3 C3 C2 F1 F2 D A1 B1 B2 C1 Channel No. 3 A1 Sc45%, A2 Sc30%, A3 Sc15% B1 Ko45%, B2 Ko30%, B3 Ko15% C1 Ac45%, C2 Ac30%,C3 Ac15% D control F1~G2 demonstration

6 In In spring spring Scylla serrata Pond BK. obovata Pond APond B: planted before establishment ofpond IMASC(2001) Pond A: plantedponds S. caseolaris Pond C: planted A. corniculatum Sciaenops ocellatus

7 3 Results 3.1 Growth of mangrove plants in systems Table 1 Growth of height and basal diameter of mangrove plant (cm a -1 ) Year S. caseolaris K. obovata A. corniculatum Height Basal diameter Height Basal diameter Height Basal diameter

8 3 Results 3.1 Growth of mangrove plants in systems Table 2 Biomass of mangrove plants (g m -2 ) Year S. caseolaris K. obovata A. corniculatum Table 3 Survival rate of mangrove plants (%) Year S. caseolaris K. obovata A. corniculatum

9 3.2 Aquatic Production Pond Experiment ponds Control pond Table 4 Fish harvest in integrated systems in 2003 Yield (kg ha) Increase (%) A A A B B B C C C Av. yield (kg ha) Av. increase (%) Average D

10 3.2 Aquatic Production Table 5 Yield of Scylla serrata in 2004 Item A1 A2 A3 B1 B2 B3 C1 C2 C3 D Yield (kg ha) Comparison with pond D (%) Table 6 Yield of Scylla serrata in 2005 Item A1 A2 A3 B1 B2 B3 C1 C2 C3 D Yield (kg ha) Comparison with pond 41.9 D (%)

11 3.3 Water Quality First aquaculture period Ponds A~C: DIN & phosphate (PO 4 3- ) matched the national seawater quality standard IIIII (0.3~0.4 mg l -1, 0.03 mg l -1 ); ph & DO matched standard I~II (7.8~8.5, 5~6 mg l -1 ) Ponds A1 & A2 planted with S. caseolaris with proportions of 45% and 30%, DO was relatively low. Most water quality criteria in channel and control pond ( D ) matched or exceeded the national seawater quality standard III.

12 4 Conclusion 4.1 Mangrove can reduce effectively the concentration of nitrogen and phosphorus in aquaculture water K. obovata: grew slowest, low survival rate S. caseolaris: grew fastest, largest biomass, rapid element circulation, affected purification effect via debris A. corniculatum: best adapted, highest survival rate, long element circulation period, best for purifying aquaculture

13 4.2 Planting different mangroves species makes difference of the aquaculture production Aquatic production was: highest in ponds planted with A. corniculatum, lowest in ponds planted with S. caseolaris. Of the three mangrove species A. corniculatum accelerated aquaculture production the most.

14 Acknowledgement This research is funded by the 863 Project from the Ministry of Science and Technology, China PR (2003AA627030) and UNEP/GEF South China Sea Project (GF/ ). We express our gratitude to the staffs from Sun Yat-sen University and the Shenzhen Waterlands Resort who assists us to conduct field sampling and laboratory experiment. Thank you! Sunny Yisheng Peng Ph. D. candidate, assistant of China Wetland Sub-component of UNEP/GEF SCS Project School of Environmental Science and Engineering, Sun Yat-sen University Research interest phytotaxonomy, mangrove & forest ecology, wetland ecology / Sonneratia@126.com