Diversity of Phytoplankton and Relationships with Water Quality in the 6 Reservoirs at Loei Watershed, Loei Province

Abstract

The aims of this study were to investigate the diversity of phytoplankton and its relationships with some water qualities in 6 reservoirs. Sampling was collected in February, May, August, and November 2009. The results showed that there were 120 species of phytoplankton classified into 77 genera, 8 class and 3 divisions. Chlorophyta was found the highest number with 77 species, followed by Chromophytaand Cyanophyta with 27 and 16 species, respectively. Species diversity index, evenness index, and richness index ranged between 3.0876-3.584, 0.7556-0.8656 and 6.9835-10.2630, respectively. The relationship on transparency between the amount of phytoplankton and environmental factor was found significantly positively correlated. On the other hand, significant negative correlation was found between phytoplankton and other factors, namely, suspended solids, pH, nitrate nitrogen and orthophosphate contents. Factors regarding transparency and pH were found statistically significant at 68.60 per cent (R² = .688) in forecasting the amount of phytoplankton.