Current distribution and conservation of Najas tenuissima (Hydrocharitaceae)

Abstract

Najas tenuissima (Hydrocharitaceae) is an endangered relict species with a disjunctive range in Eastern Europe, in the Urals, in Siberia and Kazakhstan, and in the Far East, in Japan. More than 60 locations of the plant were revealed during the last 160 years. More than 30 of them are located in the waterbodies of Southern Finland. The species is known reliably in Fennoscandia, Latvia, Russian Federation (Leningrad region, Novgorod region, Tver region, Ryazan region, Republic of Mordovia, Sverdlovsk region, Chelyabinsk region, Irkutsk region, Amur region, Krasnoyarsky Krai and Primorsky Krai), Northern and Eastern Kazakhstan and Japan. The paper summarises the data on locations of the species in the above mentioned regions. We suggest that species grows in floodplain waterbodies on the right bank of the Amur river in China. Reasons why the species has disappeared are given and discussed. An anthropogenic impact on aquatic ecosystems was denoted as the main factor causing the populations' reduction of Najas tenuissima in the XX–XXI centuries. We have shown a reduction in the number of populations found from 1857 to 1936 (in Leningrad region, Tver region, Novgorod region, Ryazan region of Russia), as well as the appearance of new populations of the species found from 2006 to 2016 (in Latvia and Russia: Amur region, Chelyabinsk region, Irkutsk region, Republic of Mordovia). We assumed the possibilities of resettlement of the species at new places. It was noted that species conservation is possible only if the territorial protection of Najas tenuissima locations will be organised.

Keywords

• Najas tenuissima
• Protected Areas
• range
• Red Data Book
• relict species
• resettlement