Predation on the rocky shores of Patagonia,Argentina |
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| Authors: | Fernando J Hidalgo Brian R Silliman María Cielo Bazterrica Mark D Bertness |
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| Institution: | 1.Laboratorio de Ecología, Departamento de Biologia (FCEyN),Universidad Nacional de Mar del Plata,Mar del Plata,Argentina;2.Department of Zoology,University of Florida,Gainesville,USA;3.Department of Ecology and Evolutionary Biology,Brown University,Providence,USA |
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| Abstract: | Rocky intertidal communities of Argentinean Patagonia are exposed to harsh physical conditions caused by dry, strong southern
trade winds (mean speed 45 km h-1, gusts up to 140 km h-1) that result in intense desiccation of intertidal organisms. Predator distributions in these communities were evaluated from
April 2003 to December 2004 at two exposed headlands and six protected bays in Cabo dos Bahias (44°50′S, 65°40′W). Crabs and
sea stars dominated the predator assemblage, with occasional scavenger snails and fish also present. During low tide, predators
were never found in the open but were always associated with shelter (primarily within mussel beds and coralline algae), suggesting
a strong predator dependency on foundation species to buffer them from physical stress. Few predators (mostly crabs) emerged
from shelter at high tide. Unlike the larger predators found on Chilean rocky shores, invertebrate predators in this system
are diminutive, generally < 2 cm. The lone exception was the newly discovered invasive green crab,Carcinus mamas. Feeding trials, gut content analyses, and visual surveys indicated that native predators feed primarily on small, soft-bodied
prey.C. mamas fed on slow-moving and sessile animals, including the super abundant musselPerumytilus purpuratus, with much greater voracity than native predators. Because native intertidal organisms are dependent on mussel beds and coralline
algae for shelter from desiccation, successful invasion ofC. mamas may lead to a significant decrease in native diversity by consuming foundation species. This study represents a preliminary
survey of predator distributions and feeding habits on the rocky shores of Argentinean Patagonia and provides important baseline
data to evaluate trophic linkages and predatory effects on Patagonian rocky shores. |
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