Viriobenthos production and virioplankton sorptive scavenging by suspended sediment particles in coastal and pelagic waters

Virus production in oxic surface sediments and virioplankton sorption to suspended particles was estimated across three stations in the Southern California region (33.4degreesN, 118.6degreesW). Viriobenthos production was estimated using a sterile sediment and filtered porewater dilution technique that targeted production from both attached bacteria and bacteria living free in the porewater, and attached bacteria alone. Potential virus production rates by bacteria free in the porewater ranged from 1.7 to 4.6 x 10(8) VLP cm(-3) h(-1), while attached bacteria had slower potential production rates of between 0.4 and 1.1 x 10(8) VLP cm(-3) h(-1), suggesting turnover rates of viruses in sediments (1-5 h) which are significantly higher than those of virioplankton (similar to24-48 h). Virioplankton adsorbed to small (<150 mum) suspended sediments at stations with high ambient suspended solid concentrations. Virioplankton scavenging rates combined with published sedimentation rates demonstrate that this mechanism of virus arrival could only account for 0.01% of daily benthic virus production. Calculated mortality rates of benthic bacteria (4-14% h(-1)) suggest viruses may play an important role in sediment carbon cycling.