Effect of underground salty mine water on the rotifer communities in the Bolina River (Upper Silesia, Southern Poland)

The research was carried out in the Bolina River, which is the most anthropogenically saline river in Europe, from 2017 to 2018. This river flows through the highly industrialised and urbanised part of Upper Silesia (Poland). The aims of our survey were to analyse the structure of the rotifer communities and to determine the most important environmental factors that have a significant impact on their structure in a river under the influence of underground salty mine water discharge. According to a canonical correspondence analysis (CCA), the rotifer communities in the Bolina River are affected by electrical conductivity, the temperature of the water and the concentration of phosphates. An increase in the electrical conductivity (salinity) in the lower course, which was the result of salty mine water discharge into the Bolina River, was reflected by a decrease in the median density, the number of rotifer taxa and the Shannon–Wiener index H′. The Bolina River is a unique habitat for halophilic rotifers as well as a site of the occurrence of rotifers that can also develop in winter.