Ability of invasive green crabs to handle prey in a recently colonized region

Abstract

During the past few decades, the green crab Carcinus maenas, a native to Europe, has invaded the North American Pacific coast. In this new habitat, C. maenas encounters North American periwinkles of the genus Littorina that differ from European Littorina spp. in size, shape and shell strength. We hypothesize that the ability to handle prey never encountered previously is a prerequisite for successful invasion of novel habitats. In a first approach to testing our hypothesis, we compared European (native) to Canadian (invaded) C. maenas in feeding trials with Littorina spp. from Europe as well as Canada. Canadian crabs had significantly larger crusher claws than European crabs of the same size. Prey handling by Baltic crabs, but not by North Sea crabs, significantly depended on shell morphometry and strength of European periwinkles. By contrast, neither European nor Canadian crabs were affected by shell characteristics of the relatively soft-shelled Canadian periwinkles. Baltic and Canadian crabs did not differ in terms of handling time for, and handling success of, different periwinkle species, but North Sea crabs needed more time for, and were less successful in, crushing periwinkles. We conclude that C. maenas exhibits plasticity in both claw morphometry and feeding behaviour that enables this predator to handle novel prey organisms, and contributes to its success as an invader.