Modelling of phosphate enrichment and trophic status of Sipin Lake Jambi using TSI Carlson method

Abstract

Floating fishery net (keramba) activity in Sipin Lake Jambi has increased significantly in the last decade. This intensive fishery results in enrichment of phosphate due to the application of fish feeding and induces eutrophication. The objectives of this study are to determine phosphate enrichment, the trophic status using TSI Carlson method and to propose a model of phosphate enrichment in the lake water. TSI Carlson is a method to determine the trophic status condition in the water body. Composite water samples were collected at up-, downstream and middle of the lake. Total phosphate content, chlorophyl-a, and brightness were measured. The results show that the average of total phosphate, chlorophyl-a, and brightness of the lake water are 0.0505 mg/L, 5.86 μg/L and 58 cm, respectively. These figures indicate that fishery net activity has induced eutrophication with phosphate enrichment of 9.65 T/yr. A proposed TSI Carlson model estimates the TSI value would be 61.79 within next ten years with phosphate enrichment of 12.04 T/yr. Application of double fishery nettings (keramba) would be expected to reduce these figures and the risk of eutrophication in the lake.