STUDY ON SPECIES COMPOSITION AND DENSITY PHYTOPLANKTON IN TIGER SHRIMP POND (Penaeus monodon) IN TRA VINH PROVINCE

Abstract

The aim of this study is to determine species composition and density of phytoplankton in improved extensive shrimp ponds, based on that  better algae management measures in shrimp culture can be suggested. Phytoplankton was collectedevery 2 weeks, in total 8 samplings from each  of 5 shrimp  ponds in Duyen Hai area, Tra Vinh province. The results of our study have identified 5 algal phylas: Bacillariophyta, Chlorophyta, Cyanobacteria, Euglenophyta and Dinophyta.  In total, 64 algal species in the shrimp ponds under study. Among them, diatoms (Bacillariophyta) had the most dominant species composition, with 30 species (47%), followed by Chlorophyta  with 15 species (23%), Cyanobacteria  with 13 species (20%),  Euglenophyta  with 5 species (8%) and Dinoflagellate  with 1 species (2%). Quantitative analysis  showed that diatoms  were the phylum with  highest average density (264 ± 265 cells/ml), followed by Chlorophyta with the second highest density (115 ± 114 cells/ml) the lowest is blue-green algae (107 ± 92 cells/ml), Euglenophyta (36 ± 33 cells/ml) and Dinoflagellates had the lowest density (18 ± 0 cells/ml). The total density of all five algal phylas fluctuated from 262 ± 50 - 1,067 ± 236 cells/ml. This highest total density was  recorded in the 4^th sampling with 1067 ± 236 cells/ml,  with no statistically significant difference (p > 0.05) compared to that of the 3^rd sampling (709 ± 208 cells/ml). The total algal density of the 4^th sampling  was significantly different (p < 0.05) compared to that of the other samplings.