LOCAL VARIATION IN POPULATIONS OF THE SAND CRAB EMERITA-ANALOGA ON SANDY BEACHES IN SOUTHERN CALIFORNIA

To investigate the effect of beach morphodynamics on the biology of a dominant macroinfaunal species we compared the abundance, biomass, siz e structure and life history characteristics of populations of the san d crab Emerita analoga (Stimpson) from 12 beaches representing low int ermediate to dissipative types over a restricted geographic area (52 k m of coastline). We found significant spatial variation in abundance, biomass, size structure and life history between populations. These pa rameters were not correlated with any single environmental factor incl uding: beach morphodynamic type, water temperature, beach slope, sedim ent size, and sediment sorting and diversity. A significant amount of the variation in abundance, size and life history characteristics was associated with location, expressed by coastline distance. Once variat ion associated with coastline distance, was removed, some life history characteristics were partially correlated with water temperature, bea ch slope and sediment diversity. Our results suggest that variation ob served in the population biology of Emerita analoga may be related in part to spatial variation in recruitment, growth rates and survival.