Benthic-pelagic coupling in the Southern California Bight: Relationships between sinking organic material, diatoms and benthic foraminifera

Abstract

In an effort to understand the relationship between surface water processes and seafloor sediment characteristics in the Southern California Bight, opal concentrations, organic carbon weight percent measurements, diatom abundances and assemblages, and living benthic foraminiferal abundances were examined in surface sediments from two sites along the continental margin of Southern California. Although opal and organic carbon weight percentages in the top 1 cm of surface sediments reflect spatial changes in productivity between sites, our results indicate that they are not sensitive indicators of seasonal changes in surface water productivity at either site. The close correspondence between seasonal diatom flux in the adjacent Santa Barbara Basin (SBB), abundances of diatoms indicative of upwelling conditions, and opportunistic benthic foraminifera indicate that there is a rapid, (weeks to months) opportunistic response of the benthic species, Nonionella fragilis, to input from changes in surface water characteristics. These results highlight the close association of surface water conditions and preservable microfauna and flora, and confirm the influence of surface characteristics on seafloor ecosystems in bathyal environments on the California margin. Additional information on these associations will further improve our ability to discern seasonal and spatial changes in paleoproductivity from the geologic record.