Biological Invasions

, Volume 2, Issue 2, pp 151-163

First online:

Non-native Species and Rates of Spread: Lessons from the Brackish Baltic Sea

  • Erkki LeppäkoskiAffiliated withDepartment of Biology, Åbo Akademi University
  • , Sergej OleninAffiliated withCoastal Research and Planning Institute, Klaipeda University

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The Baltic Sea, a semi-enclosed brackish water region, has been inoculated by non-indigenous species for centuries. Today, much of its biological diversity is of foreign origin (i.e. xenodiversity), intentionally or unintentionally moved by humans over ecological and geographical barriers. As many as 98 introduced species have been recorded in the Baltic Sea and Kattegat. The role and abundance of much of the unique native brackish water fauna of the Baltic Sea are threatened by these non-indigenous species. The rate of primary introductions into the Baltic has increased since the 1950s; the secondary rate of spread of non-indigenous species within the basin varies from 30–480 km/year. We review here the invasion histories of the brown alga Sargassum muticum (introduced in the early 1990s), the mud snail Potamopyrgus antipodarum (1887), the barnacle Balanus improvisus (1844), the polychaetes Marenzelleria viridis (1985) and Polydora redeki (1963), the cladoceran Cercopagis pengoi (1992) and the mysid shrimp Hemimysis anomala (1962).

Baltic Sea introduced species invasive species spread vector xenodiversity