Deep-water ecosystems are characterized by relatively low carbonate concentration values and, due to ocean acidification (OA), these habitats might be among the first to be exposed to undersaturated conditions in the forthcoming years. However, until now, very few studies have been conducted to test how cold-water coral (CWC) species react to such changes in the seawater chemistry. The present work aims to investigate the mid-term effect of decreased pH on calcification of the two branching CWC species most widely distributed in the Mediterranean, Lophelia pertusa and Madrepora oculata. No significant effects were observed in the skeletal growth rate, microdensity and porosity of both species after 6 months of exposure. However, while the calcification rate of M. oculata was similar for all colony fragments, a heterogeneous skeletal growth pattern was observed in L. pertusa, the younger nubbins showing higher growth rates than the older ones. A higher energy demand is expected in these young, fast-growing fragments and, therefore, a reduction in calcification might be noticed earlier during long-term exposure to acidified conditions.
References
[1]
Gattuso, J.P.; Hansson, L. Ocean Acidification: Background and History. In Ocean Acidification; Gattuso, J.P., Hansson, L., Eds.; Oxford University Press: Oxford, UK, 2011; pp. 1–20.
[2]
Khatiwala, S.; Tanhua, T.; Mikaloff-Fletcher, S.; Gerber, M.; Doney, S.C.; Graven, H.D.; Gruber, N.; McKinley, G.A.; Murata, A.; Ríos, A.F.; et al. Global ocean storage of anthropogenic carbon. Biogeosciences 2013, 10, 2169–2191, doi:10.5194/bg-10-2169-2013.
[3]
Orr, J.C.; Fabry, V.J.; Aumont, O.; Bopp, L.; Doney, S.C.; Feely, R.A.; Gnanadesikan, A.; Gruber, N.; Ishida, A.; Joos, F.; et al. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 2005, 437, 681–686, doi:10.1038/nature04095.
[4]
Touratier, F.; Goyet, C. Impact of the Eastern Mediterranean Transient on the distribution of anthropogenic CO2 and first estimate of acidification for the Mediterranean Sea. Deep Sea Res. Part I Oceanogr. Res. Pap. 2011, 58, 1–15, doi:10.1016/j.dsr.2010.10.002.
[5]
Schneider, A.; Wallace, D.W.R.; K？rtzinger, A. Alkalinity of the Mediterranean sea. Geophys. Res. Lett. 2007, 34, 1–5.
[6]
Schneider, A.; Tanhua, T.; K？rtzinger, A.; Wallace, D.W.R. High anthropogenic carbon content in the eastern Mediterranean. J. Geophys. Res. 2010, doi:10.1029/2010JC006171.
[7]
Touratier, F.; Goyet, C. Decadal evolution of anthropogenic CO2 in the northwestern Mediterranean Sea from the mid-1990s to the mid-2000s. Deep Sea Res. Part I Oceanogr. Res. Pap. 2009, 56, 1708–1716, doi:10.1016/j.dsr.2009.05.015.
[8]
Calvo, E.; Simó, R.; Coma, R.; Ribes, M.; Pascual, J.; Sabatés, A.; Gili, J.M.; Pelejero, C. Effects of climate change on Mediterranean marine ecosystems: The case of the Catalan Sea. Clim. Res. 2011, 50, 1–29, doi:10.3354/cr01040.
[9]
Guinotte, J.M.; Orr, J.C.; Cairns, S.S.; Freiwald, A.; Morgan, L.; George, R. Will human-induced changes in seawater chemistry alter the distribution of deep-sea scleractinian corals? Front. Ecol. Environ. 2006, 4, 141–146, doi:10.1890/1540-9295(2006)004[0141:WHCISC]2.0.CO;2.
[10]
Steinacher, M.; Joos, F.; Fr？licher, T.L.; Plattner, G.K.; Doney, S.C. Imminent ocean acidification in the Arctic projected with the NCAR global coupled carbon cycle-climate model. Biogeosciences 2009, 6, 515–533, doi:10.5194/bg-6-515-2009.
[11]
Yamamoto, A.; Kawamiya, M.; Ishida, A.; Yamanaka, Y.; Watanabe, S. Impact of rapid sea-ice reduction in the Arctic Ocean on the rate of ocean acidification. Biogeosciences 2012, 9, 2365–2375, doi:10.5194/bg-9-2365-2012.
[12]
Thresher, R.; Tilbrook, B.; Fallon, S.J.; Wilson, N.C.; Adkins, J. Effects of chronic low carbonate saturation levels on the distribution, growth and skeletal chemistry of deep-sea corals and other seamount megabenthos. Mar. Ecol. Prog. Ser. 2011, 442, 87–99, doi:10.3354/meps09400.
[13]
Form, A.U.; Riebesell, U. Acclimation to ocean acidification during long-term CO2 exposure in the cold-water coral Lophelia pertusa. Glob. Chang. Biol. 2012, 18, 843–853, doi:10.1111/j.1365-2486.2011.02583.x.
[14]
Doney, S.C.; Fabry, V.J.; Feely, R.A.; Kleypas, J.A. Ocean Acidification: The other CO2 problem. Ann. Rev. Mar. Sci. 2009, 1, 169–192, doi:10.1146/annurev.marine.010908.163834.
Pelejero, C.; Calvo, E.; Hoegh-Guldberg, O. Paleo-perspectives on ocean acidification. Trends Ecol. Evol. 2010, 25, 332–344, doi:10.1016/j.tree.2010.02.002.
[17]
Wicks, L.; Roberts, J.M. Benthic invertebrates in a high-CO2 world. Oceanogr. Mar. Biol. Annu. Rev. 2012, 50, 127–188.
[18]
Parker, L.; Ross, P.; Connor, W.; P？rtner, H.; Scanes, E.; Wright, J. Predicting the response of molluscs to the impact of ocean acidification. Biology 2013, 2, 651–692, doi:10.3390/biology2020651.
[19]
Maier, C.; Hegeman, J.; Weinbauer, M.G. Calcification of the cold-water coral Lophelia pertusa under ambient and reduced pH. Biogeosciences 2009, 6, 1671–1680, doi:10.5194/bg-6-1671-2009.
[20]
Maier, C.; Watremez, P.; Taviani, M.; Weinbauer, M.G.; Gattuso, J.P. Calcification rates and the effect of ocean acidification on Mediterranean cold-water corals. Proc. R. Soc. Lond. B. Biol. Sci. 2012, 279, 1716–1723, doi:10.1098/rspb.2011.1763.
[21]
Maier, C.; Schubert, A.; Berzunza-Sánchez, M.M.; Weinbauer, M.G.; Watremez, P.; Gattuso, J.P. End of the century pCO2 levels do not impact calcification in Mediterranean cold-water corals. PLoS One 2013, 8, doi:10.1371/journal.pone.0062655.
[22]
Hennige, S.J.; Wicks, L.C.; Kamenos, N.A.; Bakker, D.; Findlay, H.S.; Dumousseaud, C.; Roberts, J.M. Short-term metabolic and growth responses of the cold-water coral Lophelia pertusa to Ocean Acidification. Deep Sea Res. Part II Top. Stud. Oceanogr. 2013, doi:10.1016/j.dsr2.2013.07.005.
[23]
Olariaga, A.; Gori, A.; Orejas, C.; Gili, J.M. Development of an autonomous aquarium system for maintaining deep corals. Oceanography 2009, 22, 44–45, doi:10.5670/oceanog.2009.04.
[24]
Bramanti, L.; Movilla, J.; Guron, M.; Calvo, E.; Gori, A.; Dominguez-Carrió, C.; Grinyó, J.; López-Sanz, A.; Martínez-Quintana, A.; Pelejero, C.; et al. Detrimental effects of Ocean Acidification on the economically important Mediterranean red coral (Corallium rubrum). Glob. Chang. Biol. 2013, 19, 1897–1908, doi:10.1111/gcb.12171.
[25]
Perez, F.F.; Fraga, F. A precise and rapid analytical procedure for alkalinity determination. Mar. Chem. 1987, 21, 169–182, doi:10.1016/0304-4203(87)90037-5.
[26]
Perez, F.F.; Rios, A.F.; Rellán, T.; Alvarez, M. Improvements in a fast potentiometric seawater alkalinity determination. Ciencias Mar. 2000, 26, 463–478.
[27]
Clayton, T.D.; Byrne, R.H. Spectrophotometric seawater pH measurements: Total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results. Deep Sea Res. I 1993, 40, 2115–2129, doi:10.1016/0967-0637(93)90048-8.
[28]
Jokiel, P.L.; Maragos, J.E.; Franzisket, L. Coral Growth: Buoyant Weight Technique. In Coral Reef: Research Methods; Stoddart, D.R., Johannes, R.E., Eds.; United Nations Educational Scientific and Cultural Organization: Paris, France, 1978; pp. 529–541.
[29]
Davies, P.S. Short-term growth measurements of corals using an accurate buoyant weighing technique. Mar. Biol. 1989, 101, 389–395, doi:10.1007/BF00428135.
[30]
Bucher, D.; Harriott, V.J.; Roberts, L.G. Skeletal micro-density, porosity and bulk density of acroporid corals. J. Exp. Mar. Bio. Ecol. 1998, 228, 117–136, doi:10.1016/S0022-0981(98)00020-3.
[31]
Movilla, J.; Orejas, C.; Calvo, E.; Gori, A.; López-Sanz, A.; Grinyó, J.; Dominguez-Carrió, C.; Pelejero, C. Differential response of two Mediterranean cold-water coral species to ocean acidification. Coral Reefs 2013. submitted.
[32]
Movilla, J.; Calvo, E.; Pelejero, C.; Coma, R.; Serrano, E.; Fernández-Vallejo, P.; Ribes, M. Calcification reduction and recovery in native and non-native Mediterranean corals in response to ocean acidification. J. Exp. Mar. Bio. Ecol. 2012, 438, 144–153, doi:10.1016/j.jembe.2012.09.014.
[33]
Al-Horani, F.A.; Al-Moghrabi, S.M.; de Beer, D. The mechanism of calcification and its relation to photosynthesis and respiration in the scleractinian coral Galaxea fascicularis. Mar. Biol. 2003, 142, 419–426.
[34]
Cohen, A.L.; Holcomb, M. Why corals care about ocean acidification: Uncovering the mechanism. Oceanography 2009, 22, 118–127, doi:10.5670/oceanog.2009.102.
[35]
Allemand, D.; Tambutté, é.; Zoccola, D.; Tambutté, S. Coral Calcification, Cells to Reefs. In Coral Reefs: An Ecosystem in Transition; Dubinsky, Z., Stambler, N., Eds.; Springer: Heidelberg, Germany, 2011; pp. 119–150.
