Nutrients dynamics and trophic status of lake Kenyir

Information about nutrients dynamics is very important for the lake’s productivity and ecosystem. Such information is lacking in the case of lake Kenyir, which is the largest man-made lake in Malaysia. A 12-month study (Jan-Dec 2017) was conducted to understand spatio-temporal nutrients dynamics and trophic status of the lake Kenyir. The study was conducted in three sampling zones (downstream, middle and upstream) in the Tekak river located northeast of lake Kenyir. Each sampling zone was subdivided into three sampling sites, which were considered as replications. The distance between any two sampling sites was approximately 500 m. A series of water quality parameters (temperature, dissolved oxygen, pH, conductivity, nitrate-nitrogen, nitrite-nitrogen and ammonia-nitrogen, phosphate-phosphorous and chlorophyll-a) and trophic status were determined monthly in each sampling site. Results indicate that all water quality parameters remained within expected ranges for aquatic animal particularly for fish. According to Malaysian National Water Quality Standards, most of the water quality parameters are in class I. All water quality parameters significantly (p0.05). Both total suspended solid and turbidity decreased from upstream to downstream. Chlorophyll-a showed two low value loops: one from March to May and another from August to December. The highest chlorophyll-a was observed in June compared to other months. A significant negative correlation (r=-0.29, p