Geological factors governing ichthyofauna formation in rivers of Semlyachikskii volcanic region (Eastern Kamchatka)

The role of environmental factors is considered for the lower reaches of rivers and creeks originating from the slopes of volcanoes of the Semlyachikskaya group (East Kamchatka volcanic region). The hydrological and environmental conditions of rivers and creeks flowing into the Semlyachikskii Liman are described for the first time. The specific hydrological and geomorphological characteristics of the lower reaches of those streams and the relationship between abiotic characteristics and the specific features of the structure and abundance of fish communities are studied. The spawning intensity (density) of salmon Salmonidae and the complexity (balance) of the structure of young fish and resident fish communities depend on the stream size. The habitation density and the uniformity of young fish distribution are determined by channel slope and the morphology of channel relief forms. The temperature regime determines fish growth rate, and water chemistry determines the phonetic features of resident fish population.