Spongillidae (Porifera, Spongillidae) in the Subarctic of Western Siberia

When studying the zooperiphyton of reservoirs and watercourses in the Subarctic of Western Siberia, freshwater sponges were identified. The research was carried out in areas of the southern tundra and forested tundra belts, which in turn were conditionally divided into three zones: western, central and eastern. In total, the research covered 40 reservoirs and watercourses. Three species of sponges have been found: Spongilla lacustris, Ephydatia muelleri and Ephydatia fluviatilis. The most common species is S. lacustris, E. muelleri being less common, vs E. fluviatilis which occurs only occasionally. The maximum numbers of species and their occurrence were noted in forested tundra water bodies. Linear measurements and a dimensional analysis both of gemmules and elements of the skeleton of the sponges were carried out. A tendency was revealed to a decrease in size of the skeletal structures of the studied biological material in comparison with literature data.