ZOOPLANKTON ASSEMBLAGES IN A HEAVILY POLLUTED RIVER ECOSYSTEM (PINANG RIVER, MALAYSIA): IMPACTS OF ANTHROPOGENIC STRESSORS ON THE COMMUNITIESAzma Hanim Ismail, Ng Yang Qing and Wan Nor Afiqah Zulkarnain
River ecosystems are among the most affected habitats globally due to various anthropogenic stressors such as pollution, habitat degradation, hydromorphological alterations and impervious cover due to urbanization. It remains largely unknown how and to what extent zooplankton communities are affected by these stressors in a heavily polluted river ecosystem. This study investigated the abundance and distribution of zooplankton species and the factors affecting their abundance and distribution in Pinang River. A total of 29 taxa of zooplankton were recorded, which includes 27 taxa of Rotifera and two taxa of Copepoda. Among rotifers, the order Bdelloidea had the highest relative abundance (64.79%), followed by Testudinella sp. and Lecane sp. with 10% relative abundance respectively. Spearmanâs correlation coefficient showed that the zooplankton abundance was negatively correlated with total dissolved solids and conductivity (P < 0.01). Much higher total dissolved solids and water conductivity, much lower zooplankton abundance. This condition is probably to be unfavorable to the zooplankton population as it is attributed to the presence of extreme anthropogenic activities along the river that cause runoff with high suspended matter. Thus, variations in zooplankton biodiversity reflect the deterioration of water quality in the polluted river ecosystem.