Study on the Species Composition and Abundance of Plankton,Water Quality and Stomach Contents of Pacific White Shrimp (Litopenaeus vannamei Boone,1931) Reared in Low Salinity Conditions

Abstract

          This study analyzed the species composition and abundance of plankton and water quality in low salinity (2-3 parts per thousand (ppt)) ponds used for rearing Pacific white shrimp, Litopenaeus vannamei. A total of 62 genera of plankton were found from six groups: 12 genera in Division Cyanophyta, 28 genera in Division Chlorphyta, 10 genera in Division Chromophyta, two genera in Phylum Protozoa, eight genera in Phylum Rotifera and two genera in Phylum Arthropoda. The phytoplankton that were the most prolific were the diatoms, Cyclotella and Nitzschia. The most common blue-green algae were Merismopedia, Oscillatoria and Phormidium. The most common green algae were Dictyosphaerium, Ocystis and Scenedesmus. The numbers of plankton found near the bottoms of the ponds were not different from the numbers found near the water surface. The numbers of plankton were positively related to the dissolved oxygen (DO) and chlorophyII a contents int the water.

          The plankton found in the stomachs and guts of the Pacific white shrimp consisted of seven genera in Division Cyanophyta,19 genera in Division Chlorophyta, 10 gemera in Division Chromophyta, one genus in Phylum Protozoa and two genera in Phylum Rotifera. The plankton found in both the stomachs and the guts were Merismopedia, Oscillatoria, Phormidium, Scenedesmus and Oocystis which were the same as the dominant species found in the water.