Effect of pCO2 and temperature on the boron isotopic composition of the zooxanthellate coral Acropora sp.
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Culture experiments were carried out with Acropora sp. (a branching scleractinian coral) in seawater at two pCO2 conditions (438 and 725 µatm) and two temperatures (25 and 28 °C) in order to establish the pH and temperature dependence of the boron isotopic composition of the skeleton. A clear pCO2 effect, but no temperature effect, on the coral boron isotope composition is seen. For corals cultured at “normal pCO2” (438 µatm), the δ11B of the skeleton was 24.0±0.2‰ at 25 °C, and 23.9±0.3‰ at 28 °C. The values of δ11B measured for corals cultured at higher pCO2 (725 µatm) were lower: 22.5±0.1‰, and 22.8±0.1‰ at 25 and 28 °C, respectively. The δ11B of corals cultivated at both high and normal pCO2 conditions are consistent with a dominant pH control, and are very close to that calculated from theoretical considerations. Thus, the corals do not seem to significantly alter ambient seawater for calcification with respect to pH. Co-variation between boron and carbon isotope values is explored.
KeywordsCorals Skeleton δ11B Boron Culture Temperature pCO2
Thanks are due to H. Spero for the δ13C seawater analysis, to P. Joannot, T. Corrège, and G. Cabioch for providing an Acropora colony from New Caledonia. We are grateful to N. Leclercq for his help in coral culture, to N. Lebec for her help with mass spectrometry, and to B. Hönisch for valuable discussions. Thanks are also due to four anonymous referees and to A. Grottoli for their constructive comments. Partial support for this research was provided by the National Science Foundation grant #OCE 00-83061.
- Borowitzka MA (1981) Photosynthesis and calcification in the articulated coralline red algae Amphiroa anceps and A. foliacea. Mar Biol 62:17–23Google Scholar
- CDIAC (2003) Carbon Dioxide Information Analysis Center (http://cdiac.esd.ornl.gov/)
- Gattuso J-P, Allemand D, Frankignoulle M (1999) Photosynthesis and calcification at cellular, organismal and community levels in coral reefs: a review on interactions and control by carbonate chemistry. Am Zool 39:160–183Google Scholar
- Hemming NG, Hanson GN (1994) A procedure for the analysis of boron by negative thermal ionization mass spectrometry. Chem Geol114:147–156Google Scholar
- Kakihana H, Kotaka M, Satoh S, Nomura M, Okamoto M (1977) Fundamental studies on the ion-exchange separation of boron isotopes. Bull Chem Soc Jpn 50(1):158–163Google Scholar
- Kühl M, Cohen Y, Dalsgaard T, Jørgensenm BB, Revsbech NP (1995) Microenvironment and photosynthesis of zooxanthellae in scleractinian corals studied with microsensors of O2, pH and light. Mar Ecol Prog Ser 117:159–172Google Scholar
- Leclercq N, Gattuso J-P, Jaubert J (2002) Primary production, respiration, and calcification of a coral reef mesocosm under increased CO2 partial pressure. Limnol Oceanogr 47(2):558–564Google Scholar
- Petit JR, Jouzel J, Raynaud D, Barkov NI, Barnola JM, Basile I, Bender M, Chappellaz J, Davis M, Delaygu G, Delmotte M, Kotlyakov VM, Legrand M, Lipenkov VY, Lorius C, Pépin L, Ritz C, Saltzman E, Stievenard M (1999) Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399:429–436CrossRefGoogle Scholar
- Reynaud-Vaganay S, Gattuso J-P, Cuif J-P, Jaubert J, Juillet-Leclerc A (1999) A novel culture technique for scleractinian corals: application to investigate changes in skeletal δ18O as a function of temperature. Mar Ecol Prog Ser 180:121–130Google Scholar
- Schneider K, Erez J (2000) Effects of carbonate chemistry on coral calcification, and symbiotic algae photosynthesis and isotopic fractionation. AGU/Ocean Sciences Meet, San Antonio, TX, Abstr, p 97Google Scholar
- Vengosh A, Kolodny Y, Starinsky A, Chivas AR, McCulloch MT (1991) Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates. Geochim Cosmochim Acta 55:2901–2910Google Scholar
- Zeebe RE, Wolf-Gladrow D (2001) CO2 in seawater: equilibrium, kinetics, isotopes. Elsevier, Amsterdam, Oceanography Series 65:1–346Google Scholar