How does rising atmospheric CO2 affect marine organisms?

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Coral Reefs of Northern Tanzania
McClanahan, T.R., Muthiga, N.A., Maina, J., Kamukuru, A.T. and Yahya, S.A.S. 2009. Changes in northern Tanzania coral reefs during a period of increased fisheries management and climatic disturbance. Aquatic Conservation: Marine and Freshwater Ecosystems: 10.1002/aqc.1020.

With respect to the current and future health of earth's coral reefs, the authors note that Jones et al. (2004) have argued that "climate overrides and undermines local resource use and management," and they say that Aronson and Precht (2006) have thus further argued that "this position emphasizes the need for management of the atmosphere at the global scale," if we are to preserve the planet's corals.

What was done
In an effort to gain additional perspective on the issue, McClanahan et al. surveyed the coral reefs of northern Tanzania in 2004/05 "with the aim of comparing them over an ~8-year period during a time of increased efforts at fisheries management and the 1998 El Niņo Southern Oscillation (ENSO) and Indian Ocean Dipole coral mortality event that caused 45% mortality in northern Tanzania and much of the Indian Ocean."

What was learned
The five researchers report that changes associated with both management, its absence, and the 1998 ENSO were found, but they say that the changes were generally small and that "ecological measures indicated stability or improvements" over the period of their study. In fact, they state that "northern Tanzania reefs have exhibited considerable resilience and in some cases improvements in reef conditions in the face of dire global predictions for overfishing, climate change, and their interaction."

What it means
In light of their most interesting findings, the international team of Kenyan, Swedish, Tanzanian, and American scientists conclude that "Tanzanian and possibly many other reefs that exhibit similar environmental conditions have the ability to recover from large-scale climatic and human disturbances," and they thus urge local action to deal with local problems as the best formula for protecting earth's coral reefs in the days and years to come.

Aronson, R.B. and Precht, W.F. 2006. Conservation, precaution, and Caribbean reefs. Coral Reefs 25: 441-450.

Jones, G.P., McCormick, M.I., Srinivasan, M. and Eagle, J.V. 2004. Coral decline threatens fish biodiversity in marine reserves. Proceedings of the National Academy of Sciences, USA 101: 8251-8258.

Reviewed 21 October 2009