Seagrasses At The Islands Iturup And Urup Of Kuril Archipelago

Abstract

The islands Iturup and Urup of Kuril Archipelago have been understudied in respect of seagrasses. The research aimed to fill this gap. In 2019 during the expedition of the Russian Geographical Society a part of the coastline has been surveyed by walking, the beached remains of seagrasses and the seagrasses growing on the littoral have been registered. The length of the routes was 95 km. The possible sources of negative anthropogenic impact have been examined. Herbarium collections of several institutions (LE, LECB, MHA, MW, MWG, SAK, Kamchatka Branch of Pacific Geographical Institute of the RAS, the Herbarium of Kronotsky Nature Reserve) have been explored. Three species of seagrasses occur at Iturup and Urup: Zostera marina L., Zostera asiatica Miki, and Phyllospadix iwatensis Makino. The last two species are of particular interest as they are threatened and distributed over a relatively small area. Unlike the habitats of the main part of their range located at the coasts of Japan and Korea, the habitats of the studied islands do not suffer from anthropogenic pressure. The discovered northern refuge is significant for the seagrasses conservation. Current global warming and increasing anthropogenic pressure on the southern habitat would increase its significance. It is especially important for Phyllospadix iwatensis as it turned out to be rather numerous at the studied islands. The other two species occur in small numbers there.