Dynamics of the Stellate Sturgeon (Acipenser stellatusPallas, 1771) Ecological Niche in the Northern Part of the Caspian Sea Modeled on the Basis of Long-Term (1992–2006) Summer Monitoring Data

Abstract: This paper presents models describing ecological niches of the stellate sturgeon (Acipenser stellatusPallas, 1771) in the northern part of the Caspian Sea produced on the basis of long-term (1992–2006) monitoring data. Long-time spatial distribution dynamics of two alien species (polychaete worm Hediste diversicolorand mollusk Abra ovata) and crustaceans is analyzed. The effects of abiotic and biotic factors on the formation of stellate sturgeon ecological niches in the eastern and western regions of the northern part of the Caspian Sea are estimated. Ordination diagrams reflecting the spatial distribution of stellate sturgeon in different years in the plane of two principal components (PCA) are constructed. It is shown that the leading factors for the construction of ecological niche models are water salinity and density of crustacean aggregations.