California Sea Grant College Program

Population dynamics of many r-selected species are influenced by physical factors that affect the vulnerable larval stage. Brachyurans have planktonic larval stages that spend weeks to months in open water before metamorphosing into benthic juveniles. The environmental conditions that the planktonic larvae experience can alter the rate of development and survivorship, and significantly influence the year-class strength of new cohorts.

The Chinese mitten crab, Eriocheir sinensis (Crustacea: Decapoda: Grapsoidea), was discovered in San Francisco Bay in 1992, following more than a century of global dispersal. Since the invasion, E. sinensis has become one of the most abundant and widely distributed non-native aquatic organisms in the San Francisco Bay (Cohen and Carlton, 1998). The potentially rapid population growth of E. sinensis has created ecological concerns. Invasive populations of this catadromous crab in Europe spread hundreds of kilometers into freshwater streams and rivers (Panning, 1939a). Ecological and economic effects include predation on invertebrates of estuarine and freshwater systems (Rudnick and Resh, 2002); burrowing of juveniles can cause stream bank erosion and threaten levee integrity (Veldhuizen, 1997; Rudnick et al., 2000, 2003, 2005b); recreational and commercial fisheries are harmed through gear destruction and bait stealing (Rudnick and Resh, 2002); and mass migrations of adult mitten crabs have led to increased mortality of fish at the South San Francisco Bay Delta fish facilities during salvage operations (Veldhuizen and Stanish, 1999).