Diversity of the ichthyofauna of the rivers of the southern macroslope of the Tarbagatai ridge (Alakol basin, Kazakhstan)

Abstract

Freshwater ecosystems are among the most diverse ecosystem types. The fish communities of the
rivers of the southern slope of the Tarbagatai ridge that flow into the system of the Alakol lakes (Alakol
and Sasykkol) are currently poorly studied, with the exception of the Emel River. The analysis of literary
sources up to the beginning of the 21st century is carried out and the results of our own research are
presented. Catching and biological analysis of fish were carried out according to the standard method.
The composition and biological parameters of mass fish species in the Karakol, Urzhar, Katynsu, and
Emel rivers have been studied. Fish community diversity indices according to Simpson and Shannon
were calculated. Using the PAST 4.07 statistical program, the species similarity (according to Sørensen)
of the ichthyofauna of the studied rivers was analyzed. Analysis of the obtained results revealed a de-
crease in the species diversity of fish in all the studied rivers, which numbered from 4 to 9 species. In
general, the presence of 15 species of fish belonging to three families was found, while the basis of the
list is representatives of the order carp. For 2 years of the study, it turned out that the composition of the
ichthyofauna and the frequency of occurrence of fish species in the rivers were not stable. In addition
to the Emel and Karakol rivers, the composition of the ichthyofauna consisted only of native species.
The diversity of commercial acclimatized species and random invaders that were previously part of the
ichthyofauna of the Karakol, Urzhar and Katynsu rivers has decreased.
Key words: ichthyofauna, native, alien, fish communities, biodiversity.