Modern Fauna of the Cladocera and Copepod Crustaceans (Crustacea: Cladocera, Copepoda) of Lake Dood Tsagaan (Darhad Basin, Mongolia)

Abstract—The results of a study on the qualitative and quantitative composition of modern planktonic Crustaceans (Cladocera, Diaptomidae, and Cyclopidae) of Lake Dood Tsagaan (northwestern Mongolia) are presented. A comparative analysis of the species composition of crustaceans according to new data and data obtained in the last century (1962–1963) has revealed an increase in the list of crustaceans by five Cladocera species and three Copepoda species, two of which belong to the order Cyclopoida and one to the order Calanoida. Ultrastructural studies of the main morphological parts of the copepod crustaceans Mixodiaptomus incrassatus (Sars, 1903), Acanthodiaptomus paulseni (Sars, 1903), and Cyclops glacialis Flossner, 2001 have been carried out for the first time using a scanning electron microscope (SEM). A detailed study of morphometric and morphological characters, including the use of a SEM, shows that C. glacialis from Lake Dood Tsagaan is identical to the species described in Turgen Kharkhiraa Uvs aimag and Nogoon nuur lakes in the northwest of Mongolia. Nowadays, the biomass of M. incrassatus, an important food object for the whitefish and other fish species, reaches 1100 mg/m³.