Epiphytic and epilithic diatom communities along the Raška River – implications for the water quality

Abstract

We compared epiphytic and epilithic diatom communities in the Raška River, and their use in river biomonitoring. The material was collected in April, June, August and November 2011, and March 2012 from 5 localities along the Raška River. The result showed high variation of the diatom species composition between this two micro-habitats. The most abundant genera were Navicula, Gomphonema and Nitzschia, but with higher diversity in epiphytic diatom community. During first season, Achnanthidium minutissimum and Gomphonema tergestinum were dominant taxa in epilithic, while A. minutissimum and Diatoma vulgaris in epiphytic diatom community. Epilithic diatoms are the favoured community for monitoring water quality. However, at any river, diatom species are located on various substrates at the same sampling site. For diatom diversity assessment it is necessary to investigate all micro-habitats. Our results point to a difference in values of TDI diatom index between macrophytes and stone samples. Is it necessary to investigate all micro-habitats, or is the type of substratum independent for water quality monitoring?