First Non-native North American Marine/Estuarine Record: 1864
First Non-native East/Gulf Coast Marine/Estuarine Record: 1864
Orchestia gammarellus has a wide native distribution in the Northeast Atlantic, from southern Norway to the Mediterranean and Black Seas, as well as the Azores. Madeira, and the Canary Islands (Dahl 1967; Lincoln 1979; Bellan-Santini et al. 1993; Sezgun et al. 2001). It has a much narrower range in the Northwest Atlantic, from northern Newfoundland to Casco Bay, Maine (Bousfield 1973), and is thought to be introduced here (Chapman 2000). Patterns of genetic diversity and abundance are consistent with a spread from east to west (Norway, Scotland, and Baltic to Iceland and North America) (Henzler and Ingolfsson 2008). Introduced populations are also known from South Africa, Argentina, and Chile (Orensanz et al. 2002; Lopez Gappa et al. 2006; Mead et al. 2011b; Pérez-Schultheiss 2014). Likely vectors for transport are dry ballast and cargo, given the littoral habitat and air-breathing nature of these amphipods.
The timing of the introduction of Orchestia gammarellus to Northeastern North America is not known, but one museum specimen was collected in Passamaquoddy Bay, Maine in 1864 (Yale Peabody Museum of Natural History 2016). Bousfield (1973) gave the range as: 'from eastern and southern Newfoundland to Cape Breton Island; from the western end of Nova Scotia and throughout Bay of Fundy along coast of Maine to Casco Bay.' Steele (1961) reported one record each from the western shore (Port au Port) and the northern shore (Notre Dame Bay) of Newfoundland. Henzler and Ingolfsson (2008) commented on the scarcity and patchy distribution of this amphipod in Atlantic Canada, in contrast to its abundance in Europe.
Orchestia gammarellus was first collected in Iceland in 1968, near Reykjavik. In southwest Iceland, it occurs along the coast from Reykjavík to Strandarkirkjar. In northwest Iceland, during 2000-2002, it was found at 12 sites from Gjorvidalur to Skaro, but with a very limited distribution in intertidal hot springs (Henzler and Ingolfsson 2008). In South Africa, O. gammarellus was collected in 1949 at Langebaan, north of Cape Town, and at the Knysna Estuary, on the southern coast. It was found near Table Bay, Cape Town, in 2008 (Mead et al. 2011b). On the other side of the Atlantic, this amphipod was collected in Rio Negro Province, Argentina before 1978, and later found near Puerto Deseado, Santa Cruz in 1986 (Orensanz et al. 2002). In Chile, it has been found at three widely separated sites, Playa Changa, Coquimbo at 30°S in 2005; Concón, Reg. de Valparaíso at 36°S in 2005; and Puerto Montt at 41.5°S in 2013 (Pérez-Schultheiss 2014). The pattern of invasion at many of these locations seems very patchy, possibly reflecting this amphipod's poor ability to disperse by rafting (Henzler and Ingolfsson 2008), making it dependent on many independent local transport events on ships, small boats, fishing gear, bait wrapped in seaweed, etc.