Effect Of Water Quality And Marine Phytoplankton Community Structure On Shrimp Production In Tropical Ponds
Production of giant black tiger shrimp (Penaeus monodon) in earthen ponds in the tropical region may vary as the pond matures, depending on water quality and phytoplankton community structure. The objectives of the present study were to determine water quality and marine phytoplankton succession...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2009
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/12425/1/FS_2009_34A.pdf |
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| Summary: | Production of giant black tiger shrimp (Penaeus monodon) in earthen ponds in the
tropical region may vary as the pond matures, depending on water quality and
phytoplankton community structure. The objectives of the present study were to
determine water quality and marine phytoplankton succession in ponds of different
ages, to nutritional value of isolated species of a dominant cyanobacterium in the
shrimp ponds in comparison with a beneficial diatom and green alga and to
investigate how phytoplankton community structure could be affected by alteration
of macronutrient concentrations in mixed cultures. The field study was carried out in
an intensive shrimp farm in Kuala Selangor, Malaysia. Phytoplankton and water
samples were collected from ponds of different ages categorized as new (<1yr),
intermediate (2-5yrs) and old (>10yrs), for 16 weeks of shrimp culture. Fluctuation
of nutrient and chlorophyll-a concentrations were not different from other tropical shrimp ponds in the region. Cyanobacteria (five genera), diatoms (24 genera),
dinoflagellates (four genera) and green algae (three genera) were four dominant
groups of phytoplankton found in all the shrimp ponds. Diatoms were dominant
during the early stage of the culture in new ponds whilst blue–green algae dominated
intermediate and old ponds throughout the culture period. Shrimp production in new
ponds were significantly higher than intermediate and old ponds (p<0.05) probably
due to the abundance of diatoms at the beginning of the culture cycle, suitable as live
feed for zooplankton and shrimp larvae. Pseudanabaena tenuis was found abundant
in all pond categories throughout the culture period. The cyanobacterium was
isolated for surface structure and proximate analysis in the laboratory. Result showed
that P. tenuis have lower nutritional value in comparison with a common diatom
(Chaetoceros calcitrans) and a green alga (Chlorella pyrenoidosa), indicating that is
was not part of consumable algae among grazers. All the above microalgae species
were used in the nutrient enrichment bioassays in the laboratory to determine the
growth and competition among species when grown singly and in mixed cultures.
The result showed that the diatom grew well in single cultures and competed
successfully over other microalgae in mixed cultures when silica concentrations
increased whilst other essential growth nutrients were not limited. This present
research gives an idea of how shrimp production in ponds of different ages could be
affected by water quality and phytoplankton community structure and how alteration
of nutrient concentrations could be use to stimulate growth of beneficial algae and
suppress harmful algae in mixed culture systems which need further research for
better understandings. |
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