Particle fluxes in a coastal upwelling zone: sediment trap results from Santa Barbara Basin, California

Particle fluxes were measured in the center of Santa Barbara Basin on a bi- weekly basis for a three-year period beginning in August 1993. Lithogenic m aterial dominates the total flux throughout the entire year, although it is delivered to the basin primarily during the winter rainy period. It appear s that both biological and physical processes control the eventual transpor t of detrital material to the deep part of the basin. Biogenic sedimentatio n in Santa Barbara Basin is dominated by opaline silica, with highest fluxe s during the spring-summer upwelling period. Export ratios (ratios of organ ic carbon Bur to primary production) are inversely related to primary produ ction. This relationship may be due to increased advective transport and/or enhanced regeneration of organic carbon during the highly productive upwel ling period. During the first half of the study period, Santa Barbara Basin was influenced by El Nino conditions and our data suggest that productivit y in this region is reduced during such periods. Seasonal changes in the re lative contributions of biogenic and lithogenic material to the total parti cle flux, combined with the lack of bioturbation on the sea floor, results in the accumulation of varved sediments in Santa Barbara Basin. (C) 1998 El sevier Science Ltd. All rights reserved.