Mouth area of the Kamchatka River at the beginning of the XX-th century: hydrological conditions, morphological structure, aquatic biota (according to the research material of F.P. Ryabushinskiy's expedition)
The paper analyzes the research material of F.P. Ryabushinskiy's expedition describing the mouth area of the Kamchatka River. Among the studied materials there are some rare publications and archives sources whose facts have never been published before. The analyzed expedition's data show that in 1908-1909 the Nerpich'e and Kurilskoe Lakes were freshwater, most of the estuarine lagoons were freshwater too and only their seashore areas underwent poor alkalinization at the end of winter period. The mouth area biota was composed by freshwater lower plants, invertebrates and fish species. But in spite of all this, “sea” correlation of ions in the Nerpich'e and Kurilskoe Lakes as well as relic “sea” composition of fauna of invertebrates was observed throughout the whole area. Besides occasional catchings of semi-anadromous fish species (herring and smelt) in the Nerpich'e Lake were registered. The research data of F.P. Ryabushinskiy's expedition describing the Kamchatka River mouth area are not outdated as they can be used for comparing with present-day information on brackish-water stage of development of the mouth area.