Coral Biochemistry, Skeletal Chemistry and Microstructure from Culture Experiments
Paleoceanographic research programs that depend upon coral chemistry measurements are growing in number and sophistication. Our applications of chemical proxies are dangerously way ahead of our knowledge of the biochemical processes that control these chemical proxies. We are vulnerable to grossly misinterpreting ocean and climate change signals of chemical time-series measured in corals and other carbonate groups such as foraminifera. The days are gone when paleoceanographers can tacitly assume that chemical measurements on skeletal archives of ocean changes can be interpreted as inorganic systems. In addition, optimum sampling strategies of ancient coral skeletons or other fossil archives require an ability to identify and properly sample suitable primary skeletal material from diagenetically altered carbonate. To this end, we continue our long-standing collaboration with our colleagues at the Centre Scientifique de Monaco dedicated to calcification research with specialties in coral physiology, biochemistry, symbiosis, and calcification. In addition, we maintain a coral culture program in our laboratory to carry our short-term experiments that require rapid mass spectrometric measurements during the course of an experiment. Our recent coral culture experiments, in collaboration with Dr Stéphanie Reynaud at the Monaco Laboratory, have resulted in new insights and our abandonment of the widely used Sr/Ca thermometer due to the many biochemical processes that affect this ratio other than temperature.
Research by the Monaco group into the biochemistry of the calcium channel shows the many factors controlling the delivery of calcium to the active sites of calcification and the hazards for paleoceanographers naively using cation to calcium ratios as environmental proxies. In collaboration with Dr Stéphanie Reynaud, our most recent oxygen isotope measurements of cultured specimens of Acropora species continues to reinforce the pioneering work of Jon Weber and Peter Woodhead on the fidelity of oxygen isotope proxies in corals.
- [PDF]Reynaud, S., C. Ferrier-Pages, A. Meibom, S. Mostefaoui, R. Mortlock, R. Fairbanks and D. Allemand, 2007. Light and temperature effects on Sr/Ca and Mg/Ca ratios in the scleractinian coral Acropora sp. Geochim. et Cosmochim. Acta, 71, 354-362.
- [PDF] Reynaud, S., C. Ferrier-Pages, F. Boisson, D. Allemand, and R.G. Fairbanks, 2004. Effect of light and temperature on calcification and strontium uptake in the scleractinian coral Acropora verweyi. Marine Ecology Progress Series, 279,105-112.
- Hemming, N.G., T.P. Guilderson, and R.G. Fairbanks, 1998. Seasonal variations in the boron isotopic composition of coral: A productivity signal? Global Biogeochemical Cycles, 12, 4, 581-586.