Man-made dispersal of microbenthos

Man-made geographic dispersal of species of well-known among malacologists who study the compositions of recent mollusc faunas. Ostracod faunas are very often studied by micropalaeontologists who are well aware of the geological implications of faunal composition but show reluctance to include human interference in distribution patterns. Ostracods are part of the family of the Crustacea which includes also more familiar groups such as crabs, lobsters, crawfish and shrimps. When Darwin described Elminius modestus, a barnacle (Cirripedia), it was restricted to Pacific waters but these days this crustacean is also indigenous in the littoral fauna of the Eastern Atlantic. First reported from a British harbour in 1944, where it was probably introduced by a returning man-of-war. Symbiotic relationships have been observed between ostracods and other larger crustaceans and may apply to barnacles as well. Although a convenient argument, such a relationship is not a prerequisite for anthropogenic displacement. Ballast water inside the ship's hull, weeds on the ship's skin etc. could also be spreading agents.