Primary Productivity and Plankton Abundance of Foy’s Lake, Chattogram

Abstract

The present study was conducted to estimate primary productivity in relation the physical and chemical properties and plankton abundance of Foy’s lake. Plankton is one of the most important food items of fishes that indicates productivity of water body. Gross primary productivity, net primary productivity and critical respiration were estimated in pre-monsoon, monsoon and post-monsoon. Primary productivity was estimated 0.39 gCm-3h-1 in pre-monsoon, 0.31 gCm-3h-1 in monsoon and 0.61 gCm-3h-1 in post monsoon. The lowest primary productivity was estimated 0.30 gCm-3h-1 in April and the highest primary productivity was estimated 0.61 gCm-3h-1 in September. Nine species of phytoplankton was estimated under five classes that includes Chlorophyceae, Bacillariophyceae, Cyanophyceae, Euglenophyaceae and Dinophyceae. The highest phytoplankton abundance was estimated 28 Cellsl-1 in September and the lowest in July 13 Cellsl-1. Five species of zooplankton namely Cyclops, Daphnia sp., Moina sp., Brachionus sp. and Padina sp. were identified under three classes viz Copepod, Cladocera and Rotifer. The highest abundance of phytoplankton was 17 unitsl-1 in September and the lowest abundance of phytoplankton was 7 unitsl-1 in July. This study shows that the primary productivity vary with monsoon to monsoon and highest primary productivity was estimated in post monsoon.