Free-Living Ciliates of the Deepwater Part of the Kama Reservoirs

The species composition (113 species) and distribution of free-living ciliates of the deepwater zone of the Kama cascade of reservoirs were studied in the summer low-water period in 2014 and 2016. A slight decrease in the species diversity from top to bottom along the Kama River is demonstrated; its comparison with the indices of species diversity in the Volga cascade of reservoirs is carried out. The composition of structure-forming species (from the order Tintinnida, order Choreotrichida, and subclass Scuticociliatia) and their distribution over the water area of individual reservoirs and along the longitudinal axis of the cascade are analyzed. The number of ciliates in the area from the village of Pyskor to Atabaevo varies within 119 000-4892 000 individuals/m(3), biomass varies from 1.4 to 186 mg/m(3), and production varies from 1.1 to 134 mg/m(3). Maximal indices are noted near the mouth of the Belaya River; minimal ones are noted at deepwater stations with oxygen deficiency in the bottom layers. The spatial distribution of quantitative indices of the ciliate community by morphological regions of the reservoirs is considered. The formation of sharp gradients of abiotic factors (particularly, oxygen content) leads to the synchronization of the ciliate community parameters and their high variability (oscillation amplitude). A saprobiological estimation of reservoirs by ciliates (indicators of environmental saprobity) is given: water in the reservoirs is a beta-alpha-mesosaprobic zone. The highest saprobity indices are typical for the stations in the area of wastewater discharge and stations with large depths in the near-dam areas of the reservoirs.