Phytoplankton diversity and its relationships to the physico-chemical environment in the Banglang Reservoir, Yala Province

Abstract

The diversity of phytoplankton and its relationships to the physico- chemical environment were studied in Banglang Reservoir, located on the Pattani River in Southern Thailand. Samples were collected monthly from May 2000 to April 2001 at three stations and three different depths: water surface, 10, and 30 meters. Physico-chemical parameters: temperature, pH, dissolved oxygen, alkalinity, conductivity, water transparency, and nutrients were measured simultaneously. One-hundred and thirty-five species in seven divisions of phytoplankton were found. The greatest number of species were in Division Chlorophyta (50%), followed by Cyanophyta (21%), Bacillariophyta (13%), Pyrrophyta (6%), Cryptophyta (4%), Chrysophyta (3%) and Euglenophyta (3%). The most diverse genus was Staurastrum (15 species). Phytoplankton density ranged from zero to 2.1x109 cells.m-3. Microcystis aeruginosa Kutzing in January at 30 m at the lacustrine zone had the highest phytoplankton density. By applying a PCA(principal components analysis) using the MVSP statistical analysis program on the abundance of species, it was found that Cyclotella meneghiniana Kutzing and Melosira varians Agardh were the most abundant in each station. Diversity index (Simpson’s diversity index) was maximum at 10 m at the transition zone and lowest at the outflow zone. The factors affecting the phytoplankton species by Canonical correspondence analysis ordination (PC-ORD program)were alkalinity, water temperature, water transparency, nutrients and conductivity. When the water quality parameters were classified by the trophic level, Banglang Reservoir belonged to oligo-mesotrophic status. Furthermore, Cyclotella meneghiniana Kutzing and Melosira varians Agardh could be used as the phytoplankton indicator of oligo-mesotrophic reservoir.

Keywords

• phytoplankton
• Banglang reservoir
• water quality
• diversity