How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Elevated CO2 Boosts Iron's Positive Impact on Phytoplanktonic Productivity
Breitbarth, E., Bellerby, R.J., Neill, C.C., Ardelan, M.V., Meyerhofer, M., Zollner, E., Croot, P.L. and Riebesell, U. 2010. Ocean acidification affects iron speciation during a coastal seawater mesocosm experiment. Biogeosciences 7: 1065-1073.

The authors write that "studies of artificial and natural iron input have demonstrated iron control of phytoplankton productivity and CO2 drawdown over vast oceanic regions (Boyd et al., 2007; Blain et al., 2007; Pollard et al., 2009) and in coastal upwelling regions (Bruland et al., 2001; Hutchins and Bruland, 1998)," and they state that "temporal control of iron on phytoplankton productivity was also observed in a Norwegian fjord system (Ozturk et al., 2002)."

What was done
Following the development of natural phytoplanktonic blooms in the Pelagic Ecosystem CO2 Enrichment (PeECE III) study -- where the blooms were monitored in mesocosms consisting of two-meter-diameter polyethylene bags submerged to a depth of ten meters in an adjacent fjord, where they were maintained in equilibrium with air possessing CO2 concentrations of either 350, 700 or 1050 ppm via aeration of the water column and the overlying atmosphere with air of the three CO2 concentrations (Schulz et al., 2008), Breitbarth et al. measured dissolved iron (dFe) concentrations as well as levels and oxidation rates of Fe(II) -- a necessary trace element (the ferrous species of iron) used by almost all living organisms -- over the course of the study to determine if ocean acidification may affect iron speciation in seawater.

What was learned
The eight researchers report that CO2 perturbation and phytoplanktonic bloom development resulted in pH value ranges of 7.67-7.97, 7.82-8.06 and 8.13-8.26 at 1050, 700 and 350 ppm CO2, respectively; and they say their measurements revealed that under these conditions there were significantly higher dFe concentrations in the high CO2 treatment compared to the mid and low CO2 treatments, and that the high-CO2 mesocosms showed higher values of FE(II) compared to the lower CO2 treatments.

What it means
Breitbarth et al. conclude that "ocean acidification may lead to enhanced Fe-bioavailability due to an increased fraction of dFe and elevated Fe(II) concentrations in coastal systems ... due to pH induced changes in organic iron complexation and Fe(II) oxidation rates," noting that these phenomena "will result in increased turnover of Fe in surface seawater, potentially maintaining iron bioavailability given a sufficient supply of total Fe, since equilibrium partitioning eventually restores the biolabile Fe pools that have been depleted by biological uptake." Hence, they opine that "these processes may further fuel increased phytoplankton carbon acquisition and export at future atmospheric CO2 levels," citing the work of Riebesell et al. (2007); and they thereby reach their final conclusion that "changes in iron speciation and the resulting potential negative feedback mechanism of phytoplankton productivity on atmospheric CO2" -- i.e., the drawdown of atmospheric CO2 due to enhanced phytoplanktonic growth and transferal of the carbon thus removed from the atmosphere to the ocean depths -- "need to be considered when assessing the ecological effects of ocean acidification," which is something climate alarmists are generally loath to do when the effects are beneficial.

Blain, S., Queguiner, B., Armand, L., Belviso, S., Bombled, B., Bopp, L., Bowie, A., Brunet, C., Brussaard, C., Carlotti, F., Christaki, U., Corbiere, A., Durand, I., Ebersbach, F., Fuda, J.-L., Garcia, N., Gerringa, L., Griffiths, B., Guigue, C., Guillerm, C., Jacquet, S., Jeandel, C., Laan, P., Lefevere, D., Lo Monaco, C., Malits, A., Mosseri, J., Obermosterer, I., Park, Y.-H., Picheral, M., Pondaven, P., Remenyi, T., Sandroni, V., Sarthou, G., Savoye, N., Scouarnec, L., Souhaut, M., Thuiller, D., Timmermans, K., Trull, T., Uitz, J., van Beek, P., Veldhuis, M., Vincent, D, Viollier, E., Vong, L. and Wagener, T. 2007. Effect of natural iron fertilization on carbon sequestration in the Southern Ocean. Nature 446: 1070-1074.

Boyd, P.W., Jickells, T., Law, C.S., Blain, S., Boyle, E.A., Buesseler, K.O., Coale, K.H., Cullen, J.J., de Baar, H.J.W., Follows, M., Harvey, M., Lancelot, C., Levasseur, M., Owens, N.P.J., Pollard, R., Rivkin, R.B., Sarmiento, J., Schoemann, V., Smetacek, V., Takeda, S., Tsuda, A., Turner, S. and Watson, A.J. 2007. Mesoscale iron enrichment experiments 1993-2005: Synthesis and future directions. Science 315: 612-617.

Bruland, K.W., Rue, E.L. and Smith, G.J. 2001. Iron and macronutrients in California coastal upwelling regimes: Implications for diatom blooms. Limnology and Oceanography 46: 1661-1674.

Hutchins, D.A. and Bruland, K.W. 1998. Iron-limited diatom growth and Si:N uptake ratios in a coastal upwelling regime. Nature 393: 561-564.

Ozturk, M., Steinnes, E. and Sakshaug, E. 2002. Iron speciation in the Trondheim Fjord from the perspective of iron limitation for phytoplankton. Estuarine, Coastal and Shelf Science 55: 197-212.

Pollard, R.T., Salter, I., Sanders, R.J., Lucas, M.I., Moore, C.M., Mills, R.A., Statham, P.J., Allen, J.T., Baker, A.R., Bakker, D.C.E., Charette, M.A., Fielding, S., Fones, G.R., French, M., Hickman, A.E., Holland, R.J., Hughes, J.A., Jickells, T.D., Lampitt, R.S., Morris, P.J., Nedelec, F.H., Nielsdottir, M., Planquette, H., Popova, E.E., Poulton, A.J., Read, J.F., Seeyave, S., Smith, T., Stinchcombe, M., Taylor, S., Thomalla, S., Venables, H.J., Williamson, R. and Zubkov, M.V. 2009. Southern Ocean deep-water carbon export enhanced by natural iron fertilization. Nature 457: 577-580.

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: 545-548.

Schulz, K.G., Riebesell, U., Bellerby, R.G.J., Biswas, H., Meyerhofer, M., Muller, M.N., Egge, J.K., Nejstgaard, J.C., Neill, C., Wohlers, J. and Zollner, E. 2008. Build-up and decline of organic matter during PeECE III. Biogeosciences 5: 707-718.

Reviewed 30 June 2010