Smith, C. R. University of Hawaii at Manoa, csmith@soest.hawaii.edu
DeMaster, D. J.
, W. Fornes.

 
ARE MEGAFAUNAL DEPOSIT FEEDERS "KEYSTONE MODIFIERS" OF POC FLUX ON THE CONTINENTAL SLOPE?
 
Because they are relatively sparse, the deposit-feeding megafauna are often ignored in studies of POC transformations on continental margins. Recent studies of several megafaunal deposit feeders indicate that they may feed selectively on freshly settled particles, and could substantially alter the quality and distribution of labile POC at the seafloor. In this study, we utilize excess Th-234 as a tracer to evaluate feeding selectivity and ingestion rates of 12 species of common surface- and subsurface deposit feeders in three bathyal basins off California (San Clemente, San Nicolas, and Santa Catalina Basins). We then compare estimated feeding rates to the flux of Th-234 (and labile POC) into sediment traps and to seafloor sediments. We find that the megafaunal assemblages are ingesting Th-234 (and presumably labile POC) at surprisingly high rates, processing and redistributing up to 30% of the flux reaching the basin floors. These large, sparse, and readily overlooked animals are thus likely to substantially influence the quality and availability of labile POC in continental-slope sediment communities.
 
Day: Thursday, Feb. 4
Time: 11:30 - 11:45am
Location: Hilton of Santa Fe
 
Code: SS30FR1130S