The green crab invasion to Patagonia: Understanding the adaptation of the invader to a new environment and predicting its potential impacts.

HIDALGO, FERNANDO J.; BARÓN, PEDRO J.; BAZTERRICA, MARÍA C.; LEAL, GUSTAVO A.; SILLIMAN, BRYAN; BERTNESS, MARK

México

Conferencia; ESAI 2006 Ecological Society of America International Conference; 2006

Ecological Society of America

The European green crab Carcinus maenas, a voracious and generalist predator whose ecological and economic impacts have been widely recognized, is one of the most successful global invaders in marine coastal systems. In November of 2003, two specimens were found and identified in the Patagonian Atlantic coast (Argentina), and since then several pieces of information have been accumulated showing that a population has succeed to establish in the region, presumably since 2000 or earlier. In this work we present an update on the geographic spread of the species in Patagonia, the chronology of the most relevant reproductive events, and the predation potential on native species. C. maenas has been found under rocks laying on sandy or muddy bottoms in areas moderately exposed or protected from waves, in Caleta Carolina, Caleta Sara, Bahia Melo and Rada Tilly (Punta Marques), over 250 km of coastline. Green crabs were found in all of the samplings conducted in Caleta Carolina (January, April, May and July of 2004, and March, May, June and September of 2005) over the entire tidal range, but most frequently in the proximity of tidal pools in the mid and lower intertidal levels. One mating pair, and several females in early inter-moult and displaying full spermathecae, were found in mid-summer. Egg-carrying females were collected in May, September and January; but most displayed empty chorion cases in the setae of their pleopods during the last month. These results suggest that mating occurs during the summer, and that the breeding season may extend from mid fall to the next summer. Prey-preference experiments conducted in aquaria showed that C. maenas can feed upon native mollusks, including the bivalve Perumytilus purpuratus and the gastropods Trophon geversianus and Siphonaria lessoni, and crustaceans including the barnacle Balanus glandula and the crab Cyrtograpsus angulatus. Coastal waters north and south of the present range of distribution of C. maenas are considered the most productive in Patagonia, so it is likely that the species spreads in both directions, threatening the native biodiversity and local fisheries resources.