Gammarus zaddachi zaddachi, Segerstråle, 1947

lowered salinity ( Vader 1965). Synonyms: Gammarus zaddachi zaddachi View in CoL auct.; G. setosus Distribution in Norway: Not well known. The species balticus Dementieva, 1931; G. sarsi Reid, 1939 ; G. ochlos Reid , is common in the inner part of the Oslofjord (Skadsheim 1945; Lagunogammarus zaddachi auct. 1983, 1984), and it has also been found along the south coast Descriptions and illustrations: Sexton 1942, p. 593, pl. ( Dennert 1973, Vader et al. 1984). In the Hardangerfjord 1, figs 1-7, pl. 2, figs 10-14 (as G. zaddachi , freshwater form); Brattegard (1966) found G. salinus only in the side fjords, while Segerstråle 1947, p. 231, figs 3h-j, 5; Spooner 1947, p. 20, figs the northernmost records hitherto are from the Bergen area 4A-B, 5A-C; Kinne 1954, p. 417, figs 1- 4pp; Dennert et al. 1969, ( Vader 1972). Vader (1977a) did not find G. salinus at all in the p. 23; Lincoln 1979, pp 239, 243, 249, figs 110a, 111a-b, 114. Sognefjord. G. salinus is a southern species, occurring along Ecology and habitat: Gammarus zaddachi is a brackish European coasts south to N. Spain (van Maren 1975); it is absent water amphipod, living subtidally or in the lower intertidal. It is from Iceland ( Ingolfsson 1977). quite common in the lower intertidal in the inner fjords (where G. duebenii occupies the upper intertidal), but on the outer coast it is generally confined to river mouths (Vader 1977a-b). Also 8. Gammarus wilkitzkii Birula, 1897 there it lives mainly in the lower intertidal or shallow subtidal, while G. duebenii occupies the higher intertidal. Compared Synonym: Lagunogammarus wilkitzkii auct. to areas further south (den Hartog 1964, Spooner 1947) G. Descriptions and illustrations: Sexton 1942, p. 601; zaddachi in Norway seems to occupy somewhat less saline Gurjanova 1951, p. 764, fig. 551; Barnard 1959, p. 120, pls 10-13. waters. Migratory movements, quite conspicuous in French Ecology and habitat: This large and slow-growing species estuaries ( Dennert et al. 1969, Stock 1966, Girisch et al. 1974), occurs primarily in the pack ice ( Weslawski 1994), where it is have not yet been studied in Norway. omnivorous ( Arndt 2002). In areas with seasonal ice cover the Distribution in Norway: Gammarus zaddachi occurs all animals may live benthically in the ice free periods (Arndt et along the Norwegian coast, in the right biotopes (Brattegard al. 2005). 1966, Dennert 1973, Vader 1977a-b). On the open coast it Distribution: This is a high-arctic species, occurring along is restricted to the outlet of minor streamlets, where it may the coasts of Siberia and northern Canada, as well as in the pack penetrate quite far inland ( Vader 1977b). In the inner parts of ice of the Polar Sea. It has never yet been found in Norwegian the large fjords, often meso- or even oligohaline, G. zaddachi waters outside Svalbard. Svalbard distribution is mapped by becomes the dominant amphipod in the lower intertidal, often Węsławski et al. (2018). together with G. oceanicus ( Brattegard 1966, Vader 1977a). The species is absent from Svalbard. A very aberrant biotope was discovered by the Økland D. The Gammarus tigrinus group family ( Økland et al. 2011): a population of G. zaddachi lives at 150 m depth in the freshwater lake Eikeren in inland southern 9. Gammarus tigrinus Sexton, 1939 Norway.

Description and illustrations: Sexton 1939, pp 545-548,