Range expansion of the North American alien amphipod Gammarus tigrinus Sexton, 1939 (Crustacea: Gammaridae) in Brittany, France

Christophe Piscart

doi:10.3391/ai.2008.3.4.15

Abstract

Abstract Since the first observation in September 2005 of Gammarus tigrinus in Brittany (Western France), the species’ range has expanded slowly. By September 2008, the range of G. tigrinus expanded > 63.6 km to the North and 60.4 km to the West of that observed in 2005. G. tigrinus is thought to be responsible for the replacement of native Gammarus pulex . The relatively slow expansion rate of G. tigrinus in Brittany may result from either a low frequency of ship traffic, a known vector for the species, or from the species’ slow acclimatisation to brackish waters. A number of simulated invasion scenarios are presented for the future dispersal of G. tigrinus in Brittany. Key words : invasion, non-native species, colonization velocity, ship traffic, freshwater, Western Europe The first record in Europe of the North American amphipod Gammarus tigrinus Sexton, 1939, a native of the east coast of (Bousfield 1958; van Maren 1978), was from the British Islands in 1931 (Sexton 1939). However the species probably arrived in Europe earlier (Hynes 1955) via ballast water exchanges in estuaries during the First World War by ships from the east coast of North America. The dispersal of

Highlights

The first record in Europe of the North American amphipod Gammarus tigrinus Sexton, 1939, a native of the east coast of (Bousfield 1958; van Maren 1978), was from the British Islands in 1931 (Sexton 1939)
The dispersal of G. tigrinus to other parts of Northern Europe has clearly been assisted by ship traffic and it has since become the dominant freshwater amphipod in the Netherlands (Pinkster 1977; Pinkster et al 1992), with established populations in numerous areas, e.g. British Isles (Gledhill et al 1993), the Baltic coast (Szaniawska et al 2003; Jazdzewski et al 2004), and Russia (Berezina 2007)
G. tigrinus was observed in brackish and fresh waters where two native amphipod species (Gammarus pulex (Linneaus 1758), Gammarus zaddachi Sexton 1912) had been observed in the 1960s, suggesting that the North American invader had displaced to two native species (Gras and Maasen 1971)

Summary

Introduction

The first record in Europe of the North American amphipod Gammarus tigrinus Sexton, 1939, a native of the east coast of (Bousfield 1958; van Maren 1978), was from the British Islands in 1931 (Sexton 1939). Since the first observation in September 2005 of Gammarus tigrinus in Brittany (Western France), the species’ range has expanded slowly.

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Results

Conclusion