Initial Stage of Macrozoobenthos Formation in Reservoirs of Western Mongolia

Resumo

Data on the initial stage of macrozoobenthos formation in the Taishir and Durgun reservoirs in western Mongolia in 2010–2015 have been generalized. A taxonomic list of macrozoobenthos is presented; 15 species have been recorded in Mongolia for the first time. In the Durgun Reservoir, the formation of bottom sediments and communities of invertebrates in the near-dam part is accelerated due to the water-flow transport of reed beds and invertebrates from Lake Khar-Us. The macrozoobenthos in the Taishir Reservoir is formed first due to consumers of terrigenous organic matter (decaying terrestrial vegetation and soils), and then by inhabitants of sapropelic mud; complexes of filter feeders, Spongilla lacustris (L.), are formed in the profundal zone. The process of macrozoobenthos development in the reservoir is similar to that in lowland reservoirs. After the construction of the reservoir, quantitative characteristics of macrozoobenthos increased downstream of the dam in the Dzabhan River and rheophilic species were replaced by limnophilic ones.