title: Elevated pCO2 enhances bacterioplankton removal of organic carbon.
abstract: Factors that affect the removal of organic carbon by heterotrophic bacterioplankton can impact the rate and magnitude of organic carbon loss in the ocean through the conversion of a portion of consumed organic carbon to CO2. Through enhanced rates of consumption, surface bacterioplankton communities can also reduce the amount of dissolved organic carbon (DOC) available for export from the surface ocean. The present study investigated the direct effects of elevated pCO2 on bacterioplankton removal of several forms of DOC ranging from glucose to complex phytoplankton exudate and lysate, and naturally occurring DOC. Elevated pCO2 (1000-1500 ppm) enhanced both the rate and magnitude of organic carbon removal by bacterioplankton communities compared to low (pre-industrial and ambient) pCO2 (250 -~400 ppm). The increased removal was largely due to enhanced respiration, rather than enhanced production of bacterioplankton biomass. The results suggest that elevated pCO2 can increase DOC consumption and decrease bacterioplankton growth efficiency, ultimately decreasing the amount of DOC available for vertical export and increasing the production of CO2 in the surface ocean.
authors.affiliation: Marine Science Institute, Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, United States of America.
authors.forename: Anna K
authors.initials: AK
authors.lastname: James
authors.affiliation: Marine Science Institute, Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, United States of America.
authors.forename: Uta
authors.initials: U
authors.lastname: Passow
authors.affiliation: Marine Science Institute, Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, United States of America.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Brzezinski
authors.affiliation: Bermuda Institute of Ocean Science (BIOS), St. George's, Bermuda.
authors.forename: Rachel J
authors.initials: RJ
authors.lastname: Parsons
authors.affiliation: Bermuda Institute of Ocean Science (BIOS), St. George's, Bermuda.
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Trapani
authors.affiliation: Marine Science Institute, Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, United States of America.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Carlson
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D000458:Cyanobacteria / Q000378:metabolism; D017753:Ecosystem; D004784:Environmental Monitoring; D006801:Humans; D009792:Oceans and Seas; D010839:Phytoplankton / Q000378:metabolism*; D012623:Seawater / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D002245:Carbon Dioxide; D002244:Carbon