Application of the Carlson’s Trophic State Index for the Assessment of Trophic Status of Lake Simbi Ecosystem, a Deep Alkaline-saline Lake in Kenya

Abstract

Eutrophication is increasingly becoming the greatest threat to the ecological health of global water resources hence constant screening of the trophic state of these ecosystems is important. This study was aimed at defining the trophic status of Lake Simbi through the Carlson’s Trophic State Index (CTSI) which is based on the interactions of three water quality variables viz., Secchi depth (SD), total phosphorus (TP) and the chlorophyll-a (Chl-a). The classification scale for Trophic State Index (TSI) runs from 0 to 100, and the results of this study showed that the mean TSI for SD was 67.60, for TP was 118.56, for Chl-a was 74.86 and finally the overall CTSI was 87.01. These show that Lake Simbi is hypereutrophic which reflects the high concentration of nutrients in the lake. The lake suffers from cultural eutrophication which symptomatically manifests in the prevalent proliferation of algal bloom in the lake. The study therefore recommends adoption of an efficient multi-sectoral plan for monitoring and controlling nutrients loading and other pollutants input into the lake