INVASIONS OF THE NORTHEAST PACIFIC BY ASIAN AND ATLANTIC GAMMARIDEAN AMPHIPOD CRUSTACEANS, INCLUDING A NEW SPECIES OF COROPHIUM

Abstract

ABSTRACT Northeast Pacific estuaries may be severely altered by a broad diversity of accidentally introduced exotic invertebrates (Carlton, 1979a, b, 1987), but few detailed analyses of individual species have been made. The gammaridean amphipods Ampelisca abdita, Melita nitida, Corophium alienense, new species, and Parapleustes derzhavini have previously appeared to be introduced (Carlton, 1979b). However, the specific identities of the last two species and the origins of the last three species have remained unknown. Analyses based on criteria for introduced species, that include evidence from systematics, geography, and ecology, indicate the four species are introduced in 26 of 27 possible instances. They are thus exotic as predicted, and partially corroborate Carlton's thesis that extensive and persistent faunal invasions have occurred in northeast Pacific estuaries.