Lososinka river initially was an abode of salmon. Petrozavodsk town being situated around the mouth of Lososinka, causes the strong anthropogenic pressure expressed via the pollution. The studies of technical landscapes impact to ecosystems becomes more important. Lososinka river as an example of such artificial influence appears to be very interesting for ecological researches.

The study was based on fauna samples captured from the bottom of Lososinka in 1996, July. They were picked out along the town's bank of river, in 9 plots, using the standard technique with quantitative frame of "Surber" type.

Representatives of 3 groups of insects (Ehemeroptera, Plecoptera, Threchoptera) there identified as species. The rest of fauna was classified over several groups according the systematic signs (Shubina, 1986). The number/weight ratio of different groups of organisms was evaluated.

The comparison of obtained data with references exhibits that river conditions upstream from town (outside the town's area) is similar with such rivers as Lizhma and Pyama. Within the town the structure of bottom ecosystems alters significantly. The number of species declines, the ratio of Oligichaeta increases and organisms regarded to pure water disappear. Woodiwis coefficient of pollution (scale consist of 10 balls and shows the quality of water using species diversity and particulars of animals) in the mouth amount to 2, that points to great pollution. At the same time in middle of the town water is not so polluted (coefficient = 8), in green zone (outside the town ) water is pure (coefficient = 10).

Investigation shows the significant effect of technical area to river and the importance of green zone around a reservoir.