Plankton community characteristics of natural and man-made tropical lakes

Abstract

Aim: Plankton community assemblages in both natural and man-made lakes are greatly influenced by the environmental variations, which in turn are dependent on the lake morphometric characteristics, edaphic conditions, climatic changes and the surrounding anthropogenic activities. The main objective of the present study was to investigate the pattern of phytoplankton and zooplankton composition and density, and their relationship with the water chemistry in three different lakes ofMalaysia. Methodology: Water quality, phytoplankton and zooplankton abundance were measured in a natural lake and two reservoirs in Malaysia. Multivariate and univariate analyses were performed to compare the differences in community assemblages between a natural lake and a reservoirof same depth, and a shallow andadeepreservoir.-Results : Marked lake variations were observed in the phytoplankton density. Dominant phytoplankton groups were Cryptophyta and Bacillariophyta in the shallow Bera Lake, Chlorophyta in the shallow Bukit Merah Reservoir and Euglenophyta and Chlorophyta in the deeperDurian Tunggal reservoir. Both man-made lakes had significantly higher (P < 0.05) plankton densities compared to the natural lake. The shallower Bukit Merah Reservoir had higher phytoplankton density compared to the deeper Durian Tunggal Reservoir. Dissolved oxygen and pH levels were correlated to the phytoplankton and zooplankton communities in the Bera floodplain, whilst nutrient and chlorophyll-A concentrations were important factors affecting the phytoplankton and zooplankton assemblages, respectively, in the Durian Tunggal and Bukit Merah reservoirs. Interpretation : Plankton community in shallow tropical lakes have different characteristics and composition compared to the deeperones, and thus requiring different management measures.