The state of the Ahnfeltia field and species composition of macrophytes in Izmena Bay of Kunashir Island (Southern Kuriles Islands)

Abstract

Aim: the generalization of long-term results of a study of the Ahnfeltia formation and the species composition and distribution of the macrophytes in Izmena Bay (Kunashir Island).Method: data analysis was carried out on the basis of data obtained in 1989–2019 according on recommended methods of fisheries research.Novelty: data on the state of the Ahnfeltia formation and the species composition and distribution of macrophytes in Izmena Bay of Kunashir.Result: Since 2014, there has been a decrease in all parameters of the Ahnfeltia field: average layer height, biomass, total area and field reserve. The decline was particularly significant in 2019. The likely reason is fishing in the center of the field with fracturing against the backdrop of a general decline in the stock. In despit of a fairly significant species composition of macrophytes in the Izmena Bay, except for two species of sea grasses, in 1989–2019, most often, 3 types of algae are found — Chondrus armatus, Chorda asiatica and Chaetomorpha linum, which form settlements of varying densities. The general list of macrophytes found includes 79 species. Of these, more than 40 species are facultative epiphytes.Practical significance: The results will be used to make recommendations for the sustainable use of the commercial seaweed Ahnfeltia fastigiata var.tobuchiensis.