Фауна и сообщества донных беспозвоночных ручьёв и родников Айтуарской степи (Оренбургский государственный степной заповедник)

Abstract

The benthic (invertebrate) community of streams and springs in the Aytuar steppe includes 49 taxon. Chironomids are the most diverse (11). Mayflies (10), caddisflies (7) and stoneflies (5) are rich in species. Among other invertebrates, non-chironomid dipterans (8), mollusks (3), oligochaetes (1), amphipods (1), alder flies (1), bugs (1) and beetles (1) were recorded. The specificity of the fauna is determined by the presence of the genetically Siberian species M. borealis. Its negative feature is the absence of such wide-spread European taxa as the caddisflies of the genera Beraea, Crunoecia, and Parachiona, as well as genetically Siberian elements, the mollusks Parasphaerium rectidens (Starobogatov et Streletzkaja, 1967), stoneflies Arcynopteryx compacta (McLachlan, 1872), and Nemoura arctica Esben-Petersen, 1910, may-flies Cinygma lyriformis (McDunnough, 1924) and Ephemerella aurivillii Bengtsson, 1908, caddisflies Asynarchus lapponicus Zetterstedt, 1840 and Apatania stigmatella (Zetterstedt, 1840), common in the northern regions of the Urals and Cis-Urals. Were identified groups of invertebrates that are characteristic of both spring-fed water bodies and elements of the benthic fauna of warm-water streams. Five types of zoobenthocenoses were identified in streams. The zoobenthocenosis of cobbled (boulder-pebble) substra-tum is the most typical. Its abundance is 7.19 thousand ind./m2 with a biomass of 17.75 g/m2. The second type is the sand-gravel and pebble zoobenthocenoses (20.28 thousand ind./m2 with a biomass of 27.48 g/m2). Zoobentocenoses of boulder substratum with moss fouling, sandy substratum and silts are less widespread. Two types of zoobenthocenoses are found in springs. A community with the abundance and biomass of 6.8 thousand ind./m2 and 10.88 g/m2 respectively develops on boulder-pebble substratum, and on sandy substratum with coarse CPOM a community with a moderate level of development (number 3.80 thousand ind./m2 with a biomass of 6.44 g/m2) is observed.