Снижение обилия и видового разнообразия макрозообентоса таежных ручьев при дорожных работах

Abstract

The article focuses on studying the species composition and abundance of macrozoobenthos in the overhaul area of a large road facility that includes assembling the new culverts, northern taiga streams being taken as examples. There were surveyed six small forest watercourses taking water from swamps that belong to the Chirka-Kem river basin. Four quantitative samples of macrozoobenthos (area = 0.02 m2) were taken in each watercourse, one sample was taken upstream and appointed as a background, and the other three at the construction site. Invertebrates of 50 taxa were identified in the benthos, of which 27 taxa were identified to the species level. Diptera (23 taxa) are the most widely represented. Comparison of watercourse sections in the construction area with the background ones showed that the leading factor in the disturbance of natural ecosystems is entering of a large number of substrates that are not typical for them (fine sand and clay) into the channels. The sections of the channel covered by fine sand and clay are characterized by reduced species diversity (species abundance decreased on average from 7.8 to 4.2, the Shannon index decreased from 1.72 to 1.06, the Simpson index from 0.77 to 0.57, the dominance index increased from 0.23 to 0.43). The abundance of macrozoobenthos in the construction zone also decreased – from 1 700 to 350 ind./m2, biomass from 6.1 to 1.0 g/m2. Mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddis flies (Trichoptera) are the most sensitive to biotope destruction; their species richness, abundance, and share in macrozoobenthos decreased most significantly in the work area. Among the surveyed pickets in the construction zone with stable indicators of benthos is a picket where the old culvert was left: due to the absence of active land works the destruction of bottom communities turned out to be relatively small.