Krylova E.M.1, Ivanov D.L.2, Mironov A.N.1 2013. The ratio of species of Atlantic and Pacific origin in modern Arctic fauna of bivalve molluscs // Invertebrate Zoology. Vol.10. No.1: 89–126 [in English].

1 P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Nakhimovskyi Prospect 36, Moscow 117997, Russia; e-mail:;

2 Zoological Museum, Moscow State University, Bolshaya Nikitskaya Str. 6, 125009 Moscow, Russia; e-mail:

KEY WORDS: Arctic Ocean, biogeography, Bivalvia, origin of fauna.

ABSTRACT. The present work aims to estimate the ratio of species of the bivalve molluscs of the Atlantic and the Pacific origin in different geographical and bathymetrical regions of the Arctic basin. Seven shallow-water regions of the Arctic, with depths of 0–300 m, (the Norwegian, Barents, Kara, Laptev, East Siberian, Chukchi and Beaufort Seas) and three deep-sea regions with depths exceeding 1000 m (the Norwegian and Greenland Basins, Nansen and Amundsen Basins, Canada Basins) are considered. For the identification of origin we combined fossil records with records of the distribution of living genera and, when possible, used molecular genetic data. The distribution patterns of 265 species from 132 genera were analysed.

The share of species of Atlantic origin decreases in marginal Eurasian seas from the Norwegian Sea to the Chukchi Sea, and then increases in the Beaufort Sea. The share of species of Pacific origin is higher only in the Chukchi and Beaufort Seas, the species of the Atlantic and the Pacific origin are equally represented in the East-Siberian Sea. The share of species of the Atlantic origin is much higher in all deep-sea regions.

Many taxa of bivalves that dispersed into the Arctic from the North Pacific also penetrated into the North Atlantic. In contrast, most taxa of the Atlantic origin remained in the Arctic Ocean, having stopped at the Bering Strait. Differences between the Arctic boundaries, the Arctic – Atlantic (the Greenland-Iceland – Faeroe Ridge) and the Arctic – Pacific (the Bering Strait) as barriers for dispersal are discussed.

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