Juvenile Mussel and Abalone Predation by the Lined Shore CrabPachygrapsus crassipes

Abstract

ABSTRACT Major rocky intertidal predators in the northeast Pacific such as sea stars, whelks, and birds can consume foundation species such as mussels and thereby affect zonation patterns and diversity in these habitats. Predation specifically on juvenile intertidal invertebrates can also substantially impact population dynamics and influence community structure. The lined shore crab Pachygrapsus crassipes (Randall, 1840) is an abundant denizen of sheltered and exposed intertidal habitats in the northeast Pacific from Canada to Mexico. This study examined potential P. crassipes predation on juvenile mussels (Mytilus galloprovincialis), whelks [Nucella ostrina (Gould, 1852)], and abalone [Haliotis rufescens (Swainson, 1822)] due to conflicting reports on the diet of this species. Crabs consumed more juvenile mussels and abalone than seaweed (Ulva lactuca) and fed preferentially on the smallest mussels (6- to 10-mm size class). Further experiments showed that predation on mussels by P. crassipes was highly ...