Lewin I., Halabowski D.
Salinisation that is triggered by human activity within the catchment such as land development, agriculture, discharge of industrial liquid or solid waste and mining, is called secondary salinisation. Secondary salinisation has become a hot spot internationally due to its adverse effects on freshwater ecosystems. In the Upper Silesian Coal Basin (USCB) the extraction of hard coal to the earth's surface is connected with the necessity to pump out underground mine waters that are highly mineralised and contain heavy metals and radioactive nuclides. The survey was carried out in 2010-2021 in the secondary salinised tributaries of the Vistula and Odra rivers (USCB) including the Potok Gromiecki and Potok Goławiecki, currently the most secondary salinised rivers (up to 36.1‰) in the world impacted by hard coal mine waters. The objectives of the survey were to analyse the structure of the mollusc communities including invasive alien species and to determine the most important environmental factors impacted their structure in secondary salinised rivers. Our result showed high concentration of chlorides, nutrients and high conductivity, which is a consequence of the discharge of mine waters from the coal mine dewatering system into the rivers. The unionid mussel Anodonta anatina occurred only in one section of secondary salinised tributatry. The maximum density of Potamopyrgus antipodarum ranged up to 25130 individuals/m2 and Physa acuta up to 724 individuals/m2. Canonical correspondence analysis showed that conductivity and concentrations of nutrients in the water were the most predictive parameters impacted the structure of mollusc communities. Tributaries of salinity even up to 25.8- 36.1‰, constitute new habitats for euryhaline species and may create new migration routes for invasive alien species. In secondary salinised rivers, native mollusc species are replaced by invasive alien species, more tolerant to water pollution, including other invertebrates: Gammarus tigrinus, native to North America and Ponto-Caspian Dikerogammarus villosus.
Funding: This research was partially supported by the Ministry of Education and Science, Poland and by the University of Silesia in Katowice, Poland (the Fast Track Grants)