How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Corals Moving Northward in the Western Mediterranean Seas
Serrano, E., Coma, R., Ribes, M., Weitzmann, B., Garcia, M. and Ballesteros, E. 2013. Rapid northward spread of a zooxanthellate coral enhanced by artificial structures and sea warming in the Western Mediterranean. PLOS ONE 8: e52739.

The authors write that "despite the evidence that some coral species appear to be responding to climatic warming by expanding their distributions toward the poles (Wooddroffe, 2011), it has been argued that latitudinal migration is unlikely to occur rapidly enough to respond to the current projected temperature change [italics added] (3-6°C over the next 100 years (IPCC, 2007)) due to [1] the significant distance involved (i.e., the latitudinal temperature gradient is ~1.5°C/1000 km), [2] the effects of temperature on reproduction, and [3] the decrease in carbonate ion concentrations at high latitudes."

What was done
Unfazed by this contention, Serrano et al. (1) analyzed a long-term, large-scale observational dataset to characterize the dynamics of a hermatypic coral (Oculina patagonica) in regard to its "recent northward range shift along the coast of Catalonia" and (2) examined "the main factors that could have influenced this spread," which they did "by monitoring 223 locations including natural and artificial habitats along >400 km of coastline over the last 19 years (1992-2010)."

What was learned
The six Spanish scientists report that the abundance of Oculina patagonica "increased from being present in one location in 1992 to occur on 19% of the locations in 2010, and exhibited an acceleration of its spreading over time driven by the joint action of neighborhood and long-distance dispersal," noting further that the "northward expansion has occurred at the fastest rate (22 km per year) reported for a coral species thus far."

What it means
In discussing the significance of their findings, Serrano et al. write that "a coral species with particular biological characteristics that allow it to withstand the temperature challenge that accompanies northward migration as well as the natural and anthropogenic side effects that this type of migration involves (i.e., competition with macroalgae, high sediment loads, turbidity, water chemistry) has accomplished a successful northward expansion and may be able to keep pace with the global warming prediction of ~3°C over the next 100 years." And if one species of coral can do so, it is likely that many species of coral can do so.

IPCC. 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S.D., Qin, M., Manning, Z., Marquis, M., Averyt, K., Tignor, M.B., Miller Jr., H.L. and Chen, Z. (Eds.). Cambridge University Press, Cambridge, United Kingdom.

Wooddroffe, C.D. 2011. Poleward extension of reefs. In: Hopley, D. (Ed.). Encyclopedia of Modern Coral Reefs: Structure, Form and Process. Springer-Verlag, Berlin, Germany, pp. 813-815.

Reviewed 17 July 2013