Distribution, abundance and species composition of phytoplankton in the Vietnamese waters

Abstract

Samples of phytoplankton were collected from 58 stations in the Vietnamese waters from 30 April to 21 - May, 1999 on boat M. V. SEAFDEC. The total of 508 taxa, which consisted of 1 genus, 3 species of Cyanophyta; 1 genus, 2 species of Silicoflagellata; 63 genera, 283 species of Bacillariophyta and 34 genera, 220 species of Pyrrophyta were identified. In the Cyanophyta, Oscillatoria (mainly O. erythraea) was the frequently dominant species. Bacteriastrum elongatum, Bellerochea malleus, Chaetoceros cintus, Thalassionema nitzschioides and Thalassiothrix frauenfeldii were dominant species only in some stations of the coastal region of area A, B and D. Average cell numbers of phytoplankton in the different parts of Vietnamese sea waters were in the range 5.984-53.570 cells/l. The indices of species diversity were in the ranges: - R: from 0.70 to 2.5 - H´: from 2.49 to 2.32 - H´_max: from 6.67 to 6.80 - J: from 0.37 to 0.48 - Dv: from 1.21 to 2.07