AGU Journal Highlights -- March 19, 2008( 1. Higher CO 2 boosts phytoplankt...)

Oceanographers and climatologists are intensely studying how the ocean acts as a source or a sink of carbon dioxide (CO₂). Under normal conditions, highly productive areas of the ocean are carbon sinks: Biological activity traps atmospheric CO₂ within organic particles that fall to the ocean floor when organisms die. The efficiency of this biological C pump is known to depend on the productivity and species composition of phytoplankton, yet almost no information is currently available on how CO₂ concentrations may affect these parameters. The results of Tortell et al. show that elevated CO₂ concentrations increase phytoplankton productivity in the Ross Sea, Antarctica, and promote the growth of larger diatom chains. These chains are prolific bloom formers with very high capacities to export organic carbon to sediments. The authors expect that as ocean CO₂ levels rise, similar blooms may be found in regions subject to natural ion fertilization, through upwelling of deep waters, windblown input, island effects, or melting sea ice.

Title: CO₂ sensitivity of Southern Ocean phytoplankton

Authors: Philippe D. Tortell: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia, Canada; also at Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada;

Christopher D. Payne and Yingyu Li: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia, Canada;

Scarlett Trimborn and Bjrn Rost: Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany;

Walker O. Smith: Virginia Institute of Marine Sciences, Gloucester Point, Virginia, U.S.A.;

Christina Riesselman and Robert B. Dunbar: Geological and Environmental Sciences, Stanford University, S
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