Faasse, M.; Van Moorsel, G. (2003). The North-American amphipods, Melita nitida Smith, 1873 and Incisocalliope aestuarius (Watling and Maurer, 1973) (Crustacea: Amphipoda: Gammaridea), introduced to the Western Scheldt estuary (The Netherlands). Aquatic Ecology. 37(1): 13-22.
The North-American amphipods, Melita nitida Smith, 1873 and Incisocalliope aestuarius (Watling and Maurer, 1973) (Crustacea: Amphipoda: Gammaridea), introduced to the Western Scheldt estuary (The Netherlands)
The American amphipod species Melita nitida and Incisocalliopeaestuarius have been found in the Western Scheldt estuary (theNetherlands). This is the first record of these species in thenorth-east Atlantic. Shipping is the most likely vector of introduction. The distribution of both species is investigated andcompared with the distribution and the microhabitat ofco-occurring amphipod species. Melita nitida is known from both the east and west coast of North America and I. aestuariusoriginates from the east coast of North America. Until now neitherhas been reported from other parts of the world. In the Netherlands both species are restricted to the mesohaline part of the Western Scheldt. Melita nitida occurs predominantly underPacific oysters at the underside of boulders, mainly sublittorally. Incisocalliope aestuarius is associated to hydrozoans. Both microhabitats are hardly utilized by other amphipod species. Therefore, the theory that the existence of many empty niches in north-western European brackish waters make this environment particularly susceptible to invasions of alien species is corroborated. The application of hard substrates in a regionoriginally predominated by soft bottoms moreover facilitates theintroduction of exotic species. The species community on hardsubstrates in the mesohaline part of the Western Scheldt containsa high proportion of introduced species: approximately one thirdof the macrofauna species is of allochthonous origin.