How does rising atmospheric CO2 affect marine organisms?

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Marine Ecosystem Response to "Ocean Acidification" Due to Atmospheric CO2 Enrichment
Vogt, M., Steinke, M., Turner, S., Paulino, A., Meyerhofer, M., Riebesell, U., LeQuere, C. and Liss, P. 2008. Dynamics of dimethylsulphoniopropionate and dimethylsulphide under different CO2 concentrations during a mesocosm experiment. Biogeosciences 5: 407-419.

The authors write that "ocean acidification is one of the effects of increased anthropogenic CO2," that "oceanic DMS [dimethylsulphide] production is a result of complex interactions within the marine food-web," and that "ocean acidification may affect DMS concentrations and fluxes by altering one or more of the various pathways or impacting some of the species involved," with the reason for concern being the fact that the particulate atmospheric oxidation products of DMS can act as cloud condensation nuclei and lead to the creation of more numerous and more reflective clouds that can cool the planet by reflecting more incoming solar radiation back to space, which would tend to mute the greenhouse effect of rising atmospheric CO2 concentrations and keep the planet from getting too warm.

What was done
Effects of atmospheric CO2 enrichment on various marine microorganisms and DMS production were studied in nine marine mesocosms maintained within 2-meter-diameter polyethylene bags submerged to a depth of ten meters in a fjord adjacent to the Large-Scale Facilities of the Biological Station of the University of Bergen in Espegrend, Norway. Three of the mesocosms were maintained at ambient levels of CO2 (~375 ppm), three were maintained at levels expected to prevail at the end of the current century (760 ppm or 2x CO2), and three were maintained at levels predicted for the middle of the next century (1150 ppm or 3x CO2), while measurements of numerous ecosystem parameters were made over a period of 24 days.

What was learned
Vogt et al. report that they detected no significant phytoplankton species shifts between treatments, and that "the ecosystem composition, bacterial and phytoplankton abundances and productivity, grazing rates and total grazer abundance and reproduction were not significantly affected by CO2 induced effects," citing in support of this statement the work of Riebesell et al. (2007), Riebesell et al. (2008), Egge et al. (2007), Paulino et al. (2007), Larsen et al. (2007), Suffrian et al. (2008) and Carotenuto et al. (2007). In addition, they say that "while DMS stayed elevated in the treatments with elevated CO2, we observed a steep decline in DMS concentration in the treatment with low CO2," i.e., the ambient CO2 treatment.

What it means
With respect to their many findings, the eight researchers say their observations suggest that "the system under study was surprisingly resilient to abrupt and large pH changes," which is just the opposite of what the world's climate alarmists characteristically predict about CO2-induced "ocean acidification." And that may be why Vogt et al. described the marine ecosystem they studied as "surprisingly resilient" to such change: it may have been a little unexpected.

Carotenuto, Y., Putzeys, S., Simonelli, P., Paulino, A., Meyerhofer, M., Suffrian, K., Antia, A. and Nejstgaard, J.C. 2007. Copepod feeding and reproduction in relation to phytoplankton development during the PeECE III mesocosm experiment. Biogeosciences Discussions 4: 3913-3936.

Egge, J., Thingstad, F., Engel, A., Bellerby, R.G.J. and Riebesell, U. 2007. Primary production at elevated nutrient and pCO2 levels. Biogeosciences Discussions 4: 4385-4410.

Larsen, J.B., Larsen, A., Thyrhaug, R., Bratbak, G. and Sandaa R.-A. 2007. Marine viral populations detected during a nutrient induced phytoplankton bloom at elevated pCO2 levels. Biogeosciences Discussions 4: 3961-3985.

Paulino, A.I., Egge, J.K. and Larsen, A. 2007. Effects of increased atmospheric CO2 on small and intermediate sized osmotrophs during a nutrient induced phytoplankton bloom. Biogeosciences Discussions 4: 4173-4195.

Riebesell, U., Bellerby, R.G.J., Grossart, H.-P. and Thingstad, F. 2008. Mesocosm CO2 perturbation studies: from organism to community level. Biogeosciences Discussions 5: 641-659.

Riebesell, U., Schulz, K., Bellerby, R., Botros, M., Fritsche, P., Meyerhofer, M., Neill, C., Nondal, G., Oschlies, A., Wohlers, J. and Zollner, E. 2007. Enhanced biological carbon consumption in a high CO2 ocean. Nature 450: 10.1038/nature06267.

Suffrian, K., Simonelli, P., Nejstgaard, J.C., Putzeys, S., Carotenuto, Y. and Antia, A.N. 2008. Microzooplankton grazing and phytoplankton growth in marine mesocosms with increased CO2 levels. Biogeosciences Discussions 5: 411-433.

Reviewed 16 July 2008