The Alien Mollusk Anadara kagoshimensis in the Structure of Benthic Communities on the Crimean Shelf. Shalovenkov N.

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Inland Water Biology, Vol. 16, No. 4, pp. 681–689.

The Alien Mollusk Anadara kagoshimensis in the Structure of Benthic Communities on the Crimean Shelf.

Shalovenkov N.

The Centre for Ecological Studies, shaloven@rambler.ru

Over the past fifteen years, the frequency of occurrence of the alien mollusk Anadara kagoshimensis (Tokunaga, 19 06) increased from 5 to 17–23% in the zoobenthos of the southern coast of the Crimean shelf.

Fig. 1. Study area. Area of the Crimean shelf where the alien mollusk A. kagoshimensis was recorded in benthic samples (dotted line). Coastal studied areas: (1), outer harbor of Balaklava, (2), water area of the urban-type settlement of Alupka, and (3), water area of the urban-type settlement of Gurzuf.

At the same time, the proportion of the alien mollusk was not significant and varied from 0.73 to 23.29% of the biomass and from 0.19 to 2.20% of the abundance of the macrozoobenthos in the benthic communities.

Fig. 2. Dendrogram of grouping of stations according to the species composition of zoobenthos (a) and the spatial distribution in the water area of Vasilieva Balka (b) benthic community of Gouldia minima–Pitar rudis (I) with the division into overlapping sections (1) and “cores” (2) of the community; the alien mollusk A. kagoshimensis. Isolines denote the mollusk biomass (g/m2); the dotted line is the area of the underwater landslide.

The mollusc A . kagoshimensis has been registered in the three communities: Chamelea gallina, Gouldia minima–Pitar rudis and Gouldia minima. The mollusc Anadara has not formed an independent community here. Influence of this alien species on bottom communities of the Crimean Coast was not such considerable as on bottom communities in northwest or in east parts of Black Sea Shelf.

Fig. 3. Dendrogram of grouping of stations according to the species composition of zoobenthos (a) and the spatial distribution of the benthic communities of Chamelea gallina (I) and Gouldia minima (II) and the alien mollusk A. kagoshimensis in the water area of the coast of Alupka (b) (isolines are mollusk biomass, g/m2).

Fig. 4. Dendrogram of grouping of stations according to the species composition of zoobenthos (a) and the spatial distribution of the benthic communities of Chamelea gallina (I) and the alien mollusk A. kagoshimensis in the water area off the coast of Gurzuf (b) (isolines denote mollusk biomass, g/m2).

The structure of benthic communities had no significant changes on the shelf of the Southern Coast of the Crimea, compared with 70–80 of the last century. The first registration and the settlement of the mollusc-invader on the Crimea Shelf coincides with salinity decrease and temperature rise of coastal waters which are observed during last decade.