SEASONAL PATTERNS IN A SAN-FRANCISCO BAY, CALIFORNIA, SALT-MARSH ARTHROPOD COMMUNITY

Biomass, abundance, and species richness patterns of detritivore, herbivore, and carnivore components of a San Francisco Bay, California, salt marsh arthropod community were examined over an annual cycle. Abundance and species richness patterns for herbivores and detritivores did not track the occurrence of their respective food resources, perhaps because of the influence of salinity levels, and the frequency and duration of tidal inundation. In contrast, abundance and species richness of carnivores corresponded well with occurrence of their herbivore and detritivore prey, perhaps because carnivores are less susceptible to salt marsh environmental extremes. Trophic biomass analysis showed a typical pyramid-shaped relationship among producer, herbivore and detritivore, and carnivore components in spring; during autumn, however, the biomass of carnivores exceeded that of herbivores and detritivores.