Трансформация экосистем (Oct 2018)

Zooplankton of the coastal areas of reservoirs of the arid zone: effects of level regime and meteorological conditions

  • Аlexander V. Krylov,
  • Bud Mėndsaĭkhan,
  • Chananbaatar Ayushsuren,
  • Alexander I. Tsvetkov

DOI
https://doi.org/10.23859/estr-180319
Journal volume & issue
Vol. 1, no. 1
pp. 5 – 23

Abstract

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The interannual differences in the zooplankton of the coastal zone of two different types of reservoirs were analyzed, depending on the location along the longitudinal profile of water bodies, the amount of atmospheric precipitation, air temperature, the level and electrical conductivity of the water, and the morphometry of the water areas. The zooplankton of the coastal area of the large Tayshir Reservoir differed markedly along the longitudinal profile of the reservoir. In the upstream zone, the state of the zooplankton was estimated by totalling the effects from changes in water mineralization, in the supply of organic and nutrient substances brought by the river, in the surrounding landscape, and also the effects of the transfer of nutrients from the sediments to the water. In the middle zone, the following effects were taken into account: external intake of substances and diffusion of nutrients from bottom sediments. In the downstream zone these were: an increase in the amount of precipitation and water level that led to a dilution of water with already impoverished zooplankton content. In the Durgun reservoir, which is short and narrow, the quantity and content of zooplankton in the coastal areas of the upstream and downstream zones were not much different: in the downstream zone the number of species was somewhat higher, as well as the proportion of Cladocera in the total biomass, and the values of Shannon diversity indices calculated for the numbers and the biomass. In general, in the Durgun reservoir, the quantitative characteristics and structure of zooplankton depended on the connection with the feeding eutrophic Har-­Us Lake, which was determined by the amount of precipitation. An increase in precipitation led to an increase in the number and biomass of rotifers. An increase in the water level of the reservoir associated with a reduction in the discharge of hydroelectric power stations and a general decrease in the amount of precipitation, when the littoral zone and floods were nearly entirely absent, was correlated with an increase in the numbers and biomass of Copepoda.

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