Epiphytic diatoms as bioindicators of trophic status of Lake Modrac (Bosnia and Herzegovina)

Abstract

Biodiversity of diatoms and applicability of diatom indices in biomonitoring based on littoral epiphytic samples of LakeModrac were investigated. Diatoms were taken mostly from Phragmites australis stems in 2017, during which physical and chemicalparameters of the water were measured. A total of 85 diatom taxa were identified. Gomphonema (13 spp.), Navicula (11 spp.), andNitzschia (8 spp.) were the most abundant genera. Obtained values of trophic indices (TID, TvD, and TDIL) pointed to meso- toeutrophic status for most localities, while values of the IBD, EPI, –D, and IPS indices indicated good ecological status, except forlocalities at the mouth of 2 main tributaries which had moderate or poor ecological status. Based on the hierarchical group averageclustering and nonmetric multidimensional scaling, 4 groups were identified, mainly related to the sampling period, with higher spatialvariation in species composition during summer. Since environmental legislation in Bosnia and Herzegovina still does not providedetailed instructions on using diatoms in biological assessment, results of this study can be useful for the development of biomonitoringtools for lakes in Bosnia and Herzegovina.