The Kava River Basin (Northern Okhotsk Area) as a Hotspot of Aquatic Macrophyte Diversity in Northern Pacific

Aquatic macrophytes of the Kava River basin in northern Okhotsk area are represented by 4 species of macroalgae and 51 species and 4 hybrids of vascular plants. Flora of the Magadan Region was completed by 3 species and 3 hybrids: Aegagropilopsis moravica, Equisetum arvense × E. scirpoides, Elatine aff. triandra vel americana, Potamogeton × vepsicus, Sparganium chlorocarpum and S. chlorocarpum × S. gramineum. Almost all species of aquatic vascular plants protected in the Magadan Region (10 out of 11) are concentrated and abundant in the Kava River basin, 3 “red listed” species in the Khabarovsk Territory were also found in its basin and with a high abundance. Basing on floristic diversity, water bodies are grouped according to the similarity of environmental conditions, and not according to their geographical location. Almost all diversity of aquatic macrophytes is concentrated in lakes. The lake-river system of the Chukcha River, one of the major tributary of the Kava River, is distinguished here by the greatest diversity and concentration of rare taxa, because it is the most isolated from the cold sea winds. Rich aquatic flora and vegetation in the Kava River basin had emerged and are now sustained due to the special favorable microclimatic conditions of the closed valley of a large river, the existence of numerous water bodies of different ages and genesis with a wide variation in hydrological and hydrochemical parameters, the possibility of moving the propagules of aquatic plants along a well-developed lake-river network. The unique lake-river system of the Kava River requires increased attention and protection.