Characteristic of Lower Don aquatic ecosystem in late autumn |
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| Authors: | G G Matishov O V Stepan’yan V M Har’kovskii A V Startsev N I Bulysheva V V Semin V G Soier K V Kreneva G Yu Glushchenko L D Svistunova |
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| Institution: | 1.Southern Scientific Center,Russian Academy of Sciences,Rostov-on-Don,Russia;2.Institute of Arid Zones, Southern Scientific Center,Russian Academy of Sciences,Rostov-on-Don,Russia;3.Murmansk Marine Biological Institute, Kola Scientific Center,Russian Academy of Sciences,Murmansk,Russia |
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| Abstract: | Multidisciplinary studies were carried out in the Lower Don River in the low-water November of 2012. The studies showed relatively low concentrations of oil products (up to 2 MAC) and heavy metals (up to 1 MAC), which were likely due to the cessation of navigation in the river. However, copper concentration was found to be in excess of its MAC. The most polluted were found to be the port water areas of the cities of Volgodonsk, Ust’-Donetsk, and Semikarakorsk. The distribution of nutrients over streams is uneven: the Don water is poorer in nutrients than the waters of the Severskii Donets and the Manych are. Oxbows can serve as depots of organic matter, where it accumulates over longer periods than in the river. The residual manifestations of the summer–autumn blooming of blue-green algae, observed in shallows, the predominance of algae of divisions Cryptophyta and Bacillariophyta (typical representatives of winter planktonic algacenosis), and their low abundance suggest the transitional state of phytoplankton communities to autumn–winter season (pre-winter period). The species diversity and biomass of zooplankton were largest in the Don R. and lowest in the Severskii Donets R. The formation of zooplankton species composition shows the effect of the runoff from the Tsimlyanskoe Reservoir. An increase in the proportion of oligochaetes and invading species was recorded in the Don. The decrease in the diversity of benthos is attributed to natural factors, i.e., the decay of imago and thicket forms in autumn. The biomass of the soft (food) benthos is low because of the predominance of its small-size forms. |
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