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

Abstract

In the channel areas of the large Tayshir Reservoir valley, zooplankton is unevenly distributed along the longitudinal profile. The number and biomass of communities increases from the upper to lower rea­ ches. In the Durgun Reservoir, which has features of a canyon­type reservoir, the greatest abundance and biomass of zooplankton are recorded in the upper reaches, while the greatest number of species is recorded in the lower reaches. In the Taishir Reservoir, an increase in precipitation and a raised water level have a stimula­ ting effect on the crustaceans in the middle part of the reservoir, the area of the greatest accumulation of substances brought from the catchment area, contributing to the food supply of the invertebrates. In the upper reaches of the reservoir, with increased precipitation, high flowage prevents the development of zooplankton, and in the lower reaches, due to minimal accumulation of organic and biogenic substances and the impossibility of their intensive diffusion from bottom sediments due to maximum depth and width, the communities display the effect of “dilution” (reduced abundance). For interannual changes in the zooplankton of the channel of the upper part of the Durgun reservoir, precipitation fluctuations are of major importance. In the lower reaches of the reservoir, in the deeper areas, the temperature regime and fluctuations of the water level, depending on the work of hydroelectric power plants, are of decisive importance.

Keywords

• zooplankton
• arid zone
• reservoirs
• water level
• rainfall
• channel area
• temperature
• electrical conductivity
• air temperature