Long‐Term Temporal and Spatial Fluctuations of Soft Bottom Infaunal Invertebrates Associated with an Ocean Outfall from the San Pedro Shelf, California

Publisher Website
Google Scholar
Abstract
Temporal (annual) and spatial fluctuations of soft‐bottom invertebrates from 1977 to 1988 were reviewed and analyzed from an ocean outfall area on the San Pedro Shelf, California. Several dominant species which occurred throughout the monitoring period provide continuity between early sampling efforts and recent ones. Annual fluctuations in the mean number of species, abundance, diversity and biomass were generally conservative compared to spatial fluctuations. Temporal changes of note include a marked reduction in abundance and biomass between 1981 and 1984 and another decline in biomass in 1988. The former was associated with conditions of the 1982–1983 El Niño, and the latter with a shift in population dominance from a bivalve to a polychaete.Mean abundance and biomass were enhanced by the outfall without a significant reduction in number of species. The response of the biota to the outfall extended further upcoast (northwest) than downcoast.Several hypotheses were posed and briefly examined. These include the effects of total suspended solids generated from the outfall, and the role of the “Three Little Pigs” (bivalve‐Parvilucina tenuisculpta CARPENTER, ostracod‐Euphilomedes carcharodonta (SMITH), polychaete‐Capitella capitata (FABRICIUS)) in influencing benthic community structure. Finally, measures of infauna from the San Pedro Shelf were, except for abundance, very similar to those reported from other California shelf areas. Through time and space the outfall has had limited negative effect on infaunal community structure.