Evaluation of spatial and temporal variations in zooplankton community structure with reference to water quality in Teluk Bahang Reservoir, Malaysia

Abstract

The patterns of zooplankton community structural attributes were evaluated with reference to water quality in Teluk Bahang Reservoir, Penang, Malaysia over an annual cycle (March 2014–March 2015) and spatial gradients. Four sampling stations located at the lacustrine (Stations 1, 2 and 3) and riverine (Station 4) zones of the reservoir were designated to gather data. Samples were collected vertically at 5 m, 10 m and 15 m depth. Zooplankton samples were collected by filtering forty litres of lake water using plankton net with 30 µm mesh size. A total of 28 taxa from three major groups of zooplankton (Rotifera, Cladocera and Copepoda) were recorded. Pearson’s correlation showed that the abundance of zooplankton is directly correlated with most environmental variables including water transparency, temperature, dissolved oxygen, conductivity, total dissolved solids, pH, chlorophyll a, ammonium-nitrogen, nitrite-nitrogen and rainfall. In a similar vein, the Canonical Correspondence Analysis (CCA) also revealed that zooplankton abundances were influenced by the combined effects of water quality variables. This was further proven by the fact that the zooplankton diversity, when measured by Shannon-Weiner index, was low probably due to short water retention time and fluctuations in water levels. The results of this study indicated that the occurrence of zooplankton was characterised by the reservoir water conditions based on the value of species-environment correlations (0.66–0.84) in CCA analysis.