The Impact of Global Change on Marine Benthic Invertebrates

Abstract

Marine biogeographers divide the coastal areas of the southern SouthwestAtlantic in two main biogeographic units: the warm-temperate Argentine and thecold-temperate Magellanic provinces, with a transition at 43º?44ºS. Biodiversitydecreases with latitude in decapod crustaceans, but increases southwards inmost benthic invertebrate groups. Patagonian rocky shores are exposed to harshphysical conditions resulting in intense desiccation of intertidal organisms,which can beexpected to get worse in future scenarios of global climate change. A change to be anticipatedin the Patagonian coast is the southward range shift of warm-temperate species,which can already be perceived in San Jorge Gulf, where recent southward rangeextensions were detected in the distribution of several species. The most importantchanges during the last decades in the Patagonian coast were caused by theinvasion of nonindigenous benthic invertebrates. The arrivals of the intertidalbarnacle Balanus glandula, the crab Carcinus maenas, the sea slug Pleurobranchaea maculata, the tunicate Styela clava, and the reef-formingoyster Crassostrea gigas were themain invasions of marine invertebrates recorded in the region. Massivemortalities of the yellow clam Amarilladesmamactroides occurred in Buenos Aires Province and northern Patagonia in the1990's. Future perspectives for the region are briefly discussed.