Trophic and saprobic diatom-based indices are not indicating the same ecological status in a shallow lake, Türkiye

Abstract

This study aimed to assess the ecological health of a RAMSAR site lake by leveraging diatoms as ecological indicators. Utilizing six trophic and four saprobic indices, we evaluate the lake's ecological status. Monthly samples were collected from five sites between June 2014 and May 2015. Our findings revealed that the lake exhibited hypereutrophic characteristics according to TN and TP concentrations, as well as trophic state indices, except TIDL. Notably, the TI_VD index showed a significant correlation with TN and TP, while SI_Sla correlated significantly with TN. Despite the substantial organic matter load, our analysis positioned the lake at a beta mesosaprobic level with moderate ecological status across three saprobic indices. Interestingly, the annual average dissolved oxygen (DO) concentration classified the lake water as Class I in terms of water quality. The moderate saprobic index values suggest efficient organic matter oxidation, potentially influenced by high DO concentrations in the lake littoral. Our study underscores the importance of integrating trophic and saprobic indices to comprehensively evaluate ecosystem health and ecological status in shallow eutrophic lakes, offering insights into nutrient enrichment and organic pollution load, respectively.