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

In an effort to understand the relationship between surface water processes and seafloor sediment characteristics in the Southern California Bight, op al concentrations, organic carbon weight percent measurements, diatom abund ances and assemblages, and living benthic foraminiferal abundances were exa mined in surface sediments from two sites along the continental margin of S outhern California. Although opal and organic carbon weight percentages in the top 1 cm of surface sediments reflect spatial changes in productivity b etween sites, our results indicate that they are not sensitive indicators o f seasonal changes in surface water productivity at either site. The close correspondence between seasonal diatom flux in the adjacent Santa Barbara B asin (SBB), abundances of diatoms indicative of upwelling conditions, and o pportunistic 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 hig hlight the close association of surface water conditions and preservable mi crofauna and flora, and confirm the influence of surface characteristics on seafloor ecosystems in bathyal environments on the California margin, Addi tional information on these associations will further improve our ability t o discern seasonal and spatial changes in paleoproductivity from the geolog ic record. (C) 2001 Elsevier Science B.V. All rights reserved.