Gammarus salinus Spooner, 1947

pls IV-VI; Bousfield 1973, pp 51- 52p. 50, pl. IV-14; Lincoln 7. Gammarus salinus Spooner, 1947 View in CoL 1979, p. 254, fig. 117.

This species belongs to a group of primarily American Synonyms: Gammarus zaddachi salinus auct.; brackish- and fresh-water Gammarus species, which in many Lagunogammarus salinus auct. ways parallel the G. zaddachi group in Europe, i.a. by their Descriptions and illustrations: Sexton 1942, pl. 1, figs 8, conspicuous ‘tiger stripes’ (cf e.g. Bousfield 1969). G. tigrinus 9, pl. 2, figs 15-18 (as G. zaddachi , saline form); Spooner 1947, has no doubt been imported to Europe by man, but when p. 20. figs 4C, 5D-E; Kinne 1954, p. 416, figs 1-4pp; Dennert et and where is unknown. It was first discovered in Britain in al. 1969, p. 23; Lincoln 1979, pp 243, 251, figs 111f, 115. the 1930’s and described as a new species by Sexton (1939). Ecology and habitat: Elsewhere in Europe Gammarus It was later recognized as identical to certain populations of salinus is known as the species concentrated in the areas with the American freshwater species G. fasciatus Say, 1818 but the largest oscillations in salinity (den Hartog 1964, Movaghar this species was split by Bousfield (1958), with the brackish 1964, Meurs & Zauke 1988); this is in agreement with the water populations retaining the name G. tigrinus . Later it situation in the inner Oslofjord ( Skadsheim 1983). Here G. was imported by fisheries people to both the Netherlands and salinus lives in the lower intertidal, while the records from the Germany, in the hope that this would increase the food basis south coast and the Bergen area mostly concern the shallow for freshwater fish; instead the species quickly developed into subtidal, as in the estuaries of Western Europe ( Spooner 1947, a problem (see i.e. Ruoff 1968). Its dispersal in the Netherlands has been followed in detail over the years, and it is clear that G. pools, and even in oligohaline brackish water. tigrinus is completely dominant to the indigenous Gammarus Distribution: The Scandinavian distribution has been species in many habitats; it is i.e. less sensitive to pollution (see mapped by Segerstråle (1954). Gammarus pulex has in Sweden e.g. Nijssen & Stock 1966, Gras 1971). been found close to the border of Østfold in SE Norway, but as Ecology and habitat: In the USA Gammarus tigrinus is a yet there are no Norwegian records. species of oligohaline and mesohaline habitats in estuaries. In Europe it is found in similar biotopes, e.g. in the Baltic Sea, but also in stagnant oligohaline brackish and even in fresh water, F. The Gammarus duebenii group where it often has ousted the local indigenous Gammarus Here we have combined G. duebenii and Marinogammarus species. finmarchicus , both somewhat odd man out in their genus, both Distribution: In Europe hitherto found in Ireland, Britain, morphologically and ecologically. Both are largely intertidal Holland, Germany and the Baltic Sea. Gammarus tigrinus has species, although duebenii has a much wider ecological not yet been recorded from Norway. tolerance, and both have an amphi-atlantic distribution. ( Pinkster

et al. (1970) split off the freshwater populations in Ireland and