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The Effect of Coastal Zone Eutrophication on Ocean Acidification
Borges, A.V. and Gypens, N. 2010. Carbonate chemistry in the coastal zone responds more strongly to eutrophication than to ocean acidification. Limnology and Oceanography 55: 346-353.

Climate alarmists contend that as the air's CO2 content continues to rise and more CO2 enters the world's oceans, they will become more acidic (experience declining pH values), and that this phenomenon will make it more difficult for calcifying marine organisms to carry out the process of calcification. However, it has been demonstrated that high rates of aquatic photosynthesis by marine micro- and macro-algae, which have been shown to be stimulated and maintained by high levels of atmospheric CO2 -- see, for example, Wu et al. (2008), Fu et al. (2008) and Egge et al. (2009) -- can dramatically increase the pH of marine bays, lagoons and tidal pools (Gnaiger et al., 1978; Santhanam, 1994; Macedo et al., 2001; Hansen, 2002; Middelboe and Hansen, 2007), as well as significantly enhance the surface-water pH of areas as large as the North Sea (Brussaard et al., 1996). Thus, it is logical to presume that anything else that enhances marine photosynthesis, such as nutrient delivery to the waters of the world's coastal zones (i.e., eutrophication), may do so as well.

What was done
Thinking along these lines, Borges and Gypens employed an idealized biogeochemical model of a river system (Billen et al., 2001) and a complex biogeochemical model describing carbon and nutrient cycles in the marine domain (Gypens et al., 2004) "to investigate the decadal changes of seawater carbonate chemistry variables related to the increase of atmospheric CO2 and of nutrient delivery in the highly eutrophied Belgian coastal zone over the period 1951-1998."

What was learned
The findings of the two researchers indicate, as they describe it, that "the increase of primary production due to eutrophication could counter the effects of ocean acidification on surface water carbonate chemistry in coastal environments," and that "changes in river nutrient delivery due to management regulation policies can lead to stronger changes in carbonate chemistry than ocean acidification," as well as changes that are "faster than those related solely to ocean acidification." And to make these facts perfectly clear, they add that "the response of carbonate chemistry to changes of nutrient delivery to the coastal zone is stronger than ocean acidification."

What it means
Once again we have another example of a situation where the doom-and-gloom prognostications of the world's climate alarmists have been made without regard to the full spectrum of important phenomena that come to bear upon the issue in question, and where the conclusions they reach are found to be far more uncertain than what they portray them to be -- so far uncertain, in fact, as to typically be wrong, and in some cases to be just the opposite of what is actually true.

Billen, G., Garnier, J., Ficht, A. and Cun, C. 2001. Modeling the response of water quality in the Seine river estuary to human activity in its watershed over the last 50 years. Estuaries 24: 977-993.

Brussaard, C.P.D., Gast, G.J., van Duyl, F.C. and Riegman, R. 1996. Impact of phytoplankton bloom magnitude on a pelagic microbial food web. Marine Ecology Progress Series 144: 211-221.

Egge, J.K, Thingstad, T.F., Larsen, A., Engel, A., Wohlers, J., Bellerby, R.G.J. and Riebesell, U. 2009. Primary production during nutrient-induced blooms at elevated CO2 concentrations. Biogeosciences 6: 877-885.

Fu, F.-X., Mulholland, M.R., Garcia, N.S., Beck, A., Bernhardt, P.W., Warner, M.E., Sanudo-Wilhelmy, S.A. and Hutchins, D.A. 2008. Interactions between changing pCO2, N2 fixation, and Fe limitation in the marine unicellular cyanobacterium Crocosphaera. Limnology and Oceanography 53: 2472-2484.

Gnaiger, E., Gluth, G. and Weiser, W. 1978. pH fluctuations in an intertidal beach in Bermuda. Limnology and Oceanography 23: 851-857.

Gypens, N., Lancelot, C. and Borges, A.V. 2004. Carbon dynamics and CO2 air-sea exchanges in the eutrophied costal waters of the Southern Bight of the North Sea: A modelling study. Biogeosciences 1: 147-157.

Hansen, P.J. 2002. The effect of high pH on the growth and survival of marine phytoplankton: implications for species succession. Aquatic Microbiology and Ecology 28: 279-288.

Macedo, M.F., Duarte, P., Mendes, P. and Ferreira, G. 2001. Annual variation of environmental variables, phytoplankton species composition and photosynthetic parameters in a coastal lagoon. Journal of Plankton Research 23: 719-732.

Middelboe, A.L. and Hansen, P.J. 2007. High pH in shallow-water macroalgal habitats. Marine Ecology Progress Series 338: 107-117.

Santhanam, R., Srinivasan, A., Ramadhas, V. and Devaraj, M. 1994. Impact of Trichodesmium bloom on the plankton and productivity in the Tuticorin bay, southeast coast of India. Indian Journal of Marine Science 23: 27-30.

Wu, H.-Y., Zou, D.-H. and Gao, K.-S. 2008. Impacts of increased atmospheric CO2 concentration on photosynthesis and growth of micro- and macro-algae. Science in China Series C: Life Sciences 51: 1144-1150.

Reviewed 10 March 2010