Griscom, S. B. Marine Sciences Research Center, State University of New York, Stony Brook, griscom@msrc.sunysb.edu
Fisher, N. S. Marine Sciences Research Center, State University of New York, Stony Brook, nfisher@ccmail.sunysb.edu
Aller, R. C. Marine Sciences Research Center, State University of New York, Stony Brook, raller@ccmail.sunysb.edu

 
GUT REDOX CONDITIONS AND THE ASSIMILATION OF SEDIMENT-BOUND METALS IN TWO MARINE BIVALVES
 
Sediments ingested by the mussel, M. edulis and clam, M. balthica are subjected to geochemical conditions substantially different from ambient deposits (low pH, Eh; high surfactancy, enzyme activity). These conditions may affect the dissolution, bioavailability, and cycling of sediment-associated trace metals. Reducing conditions in the guts were measured using tetrazoleum salts and direct measurement of solid phase Fe(II). Well-oxidized suspended sediment was fed to M. edulis and M. balthica and Fe(II) production was measured in gut contents using ferrozine. Fe(II) was also measured in surface sediment and in guts of M. balthica in deposit-feeding mode. Assimilation efficiencies (AE) of Cd, Co, and Ag, from oxic and anoxic sediment were measured in each bivalve and compared with desorption of metals from the sediment resuspended in seawater and extracted digestive juices. M. edulis reduced 85 to 93% Fe in the sediment after 2 h regardless of size. Small and large M. balthica reduced 23% and 80% Fe, respectively when suspension-feeding, and 37% and 60% feeding in situ. Metal AEs from oxic sediment were higher than from anoxic sediment except for Cd and Co in M.edulis. Sediment-bound metals associated with iron phases may be released or back-extracted due to gut redox tranformations.
 
Day: Friday, Feb. 5
Time: 12:15 - 12:30pm
Location: Sweeney Center
 
Code: CS63FR1215S