The structure of fish community in the floodplain of the middle reaches of the Sysola river in spring flood periods
The ichthyofauna of the Sysola River remains practically unstudied: there are only two publications dedicated to its research (Cadastre…, 2014; Rafikov et al., 2015). This paper aims at studying the structure of fish community in perennial impounded bodies and vernal ponds in spring flood periods in the context of a part of the Sysola River watershed in the Yb village area (Syktyvdinsky District, Republic of Komi). Field works were performed in 2015-2019. The composition of the local fish community was described. 11 fish species habitation was identified: pike, bream, bleak, white bream, crucian carp, chub, ide, dace, roach, burbot, and perch. Some fish species use the floodplain for spawning and feeding. The composition of the fish community depends considerably on water level in flood periods and its variations. At various times roach, bleak, white bream and perch predominate alternately. Equally considerable changes take place in the density of dominant fish species, as well as in the level of the diversity of the fish component of the aquatic community indicated by informational indices. The fish community of perennial impounded bodies is considerably more diverse in spring flood periods than in summer runoff low periods. Biological parameters of dominant fish species are presented, and some features of their biology are described. Under extremely intense pressure of unregulated recreational fishing, including spring spawning periods, it becomes critically difficult to maintain the viability of all fish species populations. Reproduction periods are the most critical stage of the fish ontogeny, and for most of the fish species in the Sysola River basin these periods are directly connected with the floodplain. It is necessary, therefore, to concentrate efforts of nature conservation bodies and supervisory agencies, regional and municipal authorities on conservation of floodplain water bodies and flood meadows, prevention of extraction of peat and other mineral resources and logging, as well as on scrupulous following special protection regime of water conservation zones and protected shoreline belts.