How does rising atmospheric CO2 affect marine organisms?

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Challenges of Corals Living in the World's Warmest Reefs
Bauman, A.G., Baird, A.H. and Cavalcante, G.H. 2011. Coral reproduction in the world's warmest reefs: southern Persian Gulf (Dubai, United Arab Emirates). Coral Reefs 30: 405-413.

The authors write that "coral assemblages in the Persian Gulf (24-30°N) experience the highest annual variability in water temperatures of any coral reefs (Kinsman, 1964; Sheppard, 1988; Sheppard et al., 2000)," noting that sea surface temperatures there "can fluctuate annually from winter lows <12°C to summer highs >36°C (Sheppard et al., 1992; Sheppard, 1993)." And they thus suggest that "understanding coral reproductive biology in the Gulf may provide clues as to how corals may cope with global warming."

What was done
Bauman et al. examined six locally common coral species on two shallow reef sites in Dubai, United Arab Emirates, in 2008 and 2009, in order to investigate their patterns of reproduction, focusing primarily on the timing and synchrony of spawning.

What was learned
The three researchers report that the reproductive biology of the six coral species in the southern Persian Gulf "appears to be well adapted to extreme annual environmental fluctuations" and is "remarkably similar to conspecifics elsewhere in the Indo-Pacific (Baird et al., 2009a,b)," adding that "the adaptive capacity of corals in the Persian Gulf is likely facilitated by a combination of short-term acclimation in individuals during acute environmental conditions (e.g., recurrent bleaching events) and long-term adaptation among coral populations to chronic environmental conditions (e.g., extreme temperatures)."

What it means
In concluding their analysis of their data, Bauman et al. say their work "confirms that corals are capable of reproductive activities under extreme environmental conditions," as has also been found to be the case by Coles and Fadlallah (1991) and Coles and Brown (2003). Hence, they state that "coral populations can survive and proliferate in extreme conditions that are projected to occur in many other regions of the world by the end of this century," buttressing their claim with the statement that "the recovery of these coral assemblages following mortality induced by a number of recent temperature-related bleaching events (1996, 1998 and 2002) suggests these assemblages are also resilient to extreme fluctuations in water temperature," additionally citing in this regard the work of Riegl (1999, 2003) and Burt et al. (2008).

Baird, A.H., Guest, J.R. and Willis, B.L. 2009a. Systematic and biogeographical patterns in the reproductive biology of scleractinian corals. Annual Review of Ecology, Evolution, and Systematics 40: 531-571.

Baird, A.H., Birrell, C.L., Hughes, T.P., McDonald, A., Nojima, S., Page, C. Pratchett, M.S. and Yamasaki, H. 2009b. Latitudinal variation in reproductive synchrony in Acropora assemblages: Japan vs. Australia. Galaxea 11: 101-108.

Burt, J., Bartholomew, A. and Usseglio, P. 2008. Recovery of corals a decade after bleaching event in Dubai, United Arab Emirates. Marine Biology 154: 27-36.

Coles, S.L. and Brown, B.E. 2003. Coral bleaching-capacity for acclimatization and adaptation. Advances in Marine Biology 46: 183-223.

Coles, S.L. and Fadlallah, Y.H. 1991. Reef coral survival and mortality at low temperatures in the Arabian Gulf -- new species-lower temperature limits. Coral Reefs 9: 231-237.

Kinsman, D.J.J. 1964. Reef coral tolerance of high temperatures and salinities. Nature 202: 1280-1282.

Riegl, B. 1999. Corals in a non-reef setting in the southern Arabian Gulf (Dubai, UAE): fauna and community structure in response to recurring mass mortality. Coral Reefs 18: 63-73.

Riegl, B. 2003. Climate change and coral reefs: different effects in two high-latitude areas (Arabian Gulf, South Africa). Coral Reefs 22: 433-446.

Sheppard, C.R.C. 1988. Similar trends, different causes: responses of corals to stressed environments in Arabian seas. Proceedings of the Sixth International Coral Reef Symposium 3: 297-302.

Sheppard, C.R.C. 1993. Physical environment of the Gulf relevant to marine pollution: an overview. Marine Pollution Bulletin 27: 3-8.

Sheppard, C.R.C., Price, A. and Roberts, C. 1992. Marine Ecology of the Arabian Region: Patterns and Processers in Extreme Tropical Environments. Academic Press, Toronto, Canada.

Sheppard, C.R.C., Wilson, S.C., Salm, R.V. and Dixon, D. 2000. Reefs and coral communities of the Arabian Gulf and Arabian Sea. In: McClanahan, T.R., Sheppard, C.R.C. and Obura, D.O. (Eds.) Coral Reefs of the Indian Ocean: Their Ecology and Conservation. Oxford University Press, USA, pp. 257-293.

Reviewed 13 July 2011