Diversity and ecology of benthic diatoms in a mire with narrow pH gradient

: Mires are specific freshwater habitats with great importance for global biodiversity. The present study investigated diatoms in different habitats of a Đon Močvar mire and their relationship with environmental param -eters, as well as the use of diatom indicator values and the German Red List for conservation purposes. The study was conducted monthly from January to November 2012. Diatoms were sampled simultaneously with water for physical and chemical properties in three different habitats. A total of 50 diatom taxa were identified. Based on their relative abundance and diversity, habitat–related environmental factors shaped the diatom community when seasonal dynamics were less important. Multivariate analysis showed that chemical oxygen demand (COD) and conductivity were the most significant environmental variables describing diatom communities. The indicator values characterized the diatoms as a typical mire community and proved to be a reliable starting point for future monitoring and management. Diatom classification by German Red List revealed a dominance of species with priority for conservation, suggesting that the Đon Močvar should have conservation status. This study brings a better understanding of the response of diatoms to living in specific habitats and the basis for future studies on ecological characteristics of new or rare taxa. Detrended Correspondence Analysis (DCA) was used to identify and measure the relationships between diatoms and environmental variables. Analysis was conducted in Canoco 5 (ter Braak & Šmilauer 2012) on log transformed and centred relative abundance of diatom taxa and normalised environmental variables. Environmental variables that were autocorrelated were excluded from the analysis. Three sam pling sites were coded as dummy variables to represent any differences between three different sampling sites that were not captured by the environmental variables. Results are presented as a triplot in which diatom taxa, samples, and environmental variables are plotted together.