title: Effects of elevated pCO2 and feeding on net calcification and energy budget of the Mediterranean cold-water coral Madrepora oculata.
abstract: Ocean acidification is a major threat to calcifying marine organisms such as deep-sea cold-water corals (CWCs), but related knowledge is scarce. The aragonite saturation threshold (Ωa) for calcification, respiration and organic matter fluxes were investigated experimentally in the Mediterranean Madrepora oculata Over 10 weeks, colonies were maintained under two feeding regimes (uptake of 36.75 and 7.46 µmol C polyp-1week-1) and exposed in 2 week intervals to a consecutively changing air-CO2mix (pCO2) of 400, 1600, 800, 2000 and 400 ppm. There was a significant effect of feeding on calcification at initial ambient pCO2, while with consecutive pCO2treatments, feeding had no effect on calcification. Respiration was not significantly affected by feeding or pCO2levels. Coral skeletons started to dissolve at an average Ωathreshold of 0.92, but recovered and started to calcify again at Ωa≥1. The surplus energy required to counteract dissolution at elevated pCO2(≥1600 µatm) was twice that at ambient pCO2Yet, feeding had no mitigating effect at increasing pCO2levels. This could be due to the fact that the energy required for calcification is a small fraction (1-3%) of the total metabolic energy demand and corals even under low food conditions might therefore still be able to allocate this small portion of energy to calcification. The response and resistance to ocean acidification are consequently not controlled by feeding in this species, but more likely by chemical reactions at the site of calcification and exchange processes between the calicoblastic layer and ambient seawater.
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Observatoire Océanologique de Villefranche, Villefranche-sur-mer 06230, France maier.conny@gmail.com.|CNRS-INSU, Laboratoire d'Océanographie de Villefranche, BP 28, Villefranche-sur-mer 06234, France.
authors.forename: Cornelia
authors.identifier: 0000-0002-2162-0677
authors.initials: C
authors.lastname: Maier
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Observatoire Océanologique de Villefranche, Villefranche-sur-mer 06230, France.|CNRS-INSU, Laboratoire d'Océanographie de Villefranche, BP 28, Villefranche-sur-mer 06234, France.
authors.forename: Pauline
authors.initials: P
authors.lastname: Popp
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Observatoire Océanologique de Villefranche, Villefranche-sur-mer 06230, France.|CNRS-INSU, Laboratoire d'Océanographie de Villefranche, BP 28, Villefranche-sur-mer 06234, France.
authors.forename: Nicole
authors.initials: N
authors.lastname: Sollfrank
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Observatoire Océanologique de Villefranche, Villefranche-sur-mer 06230, France.|CNRS-INSU, Laboratoire d'Océanographie de Villefranche, BP 28, Villefranche-sur-mer 06234, France.
authors.forename: Markus G
authors.initials: MG
authors.lastname: Weinbauer
authors.affiliation: University of Bremen, Faculty of Biology & Chemistry, Leobener Strasse, Bremen D-28359, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wild
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Observatoire Océanologique de Villefranche, Villefranche-sur-mer 06230, France.|CNRS-INSU, Laboratoire d'Océanographie de Villefranche, BP 28, Villefranche-sur-mer 06234, France.|Institute for Sustainable Development and International Relations, Sciences Po, 27 rue Saint Guillaume, Paris F-75007, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gattuso
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology*; D002113:Calcification, Physiologic / Q000187:drug effects*; D002119:Calcium Carbonate / Q000737:chemistry; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000494:pharmacology*; D019069:Cell Respiration / Q000187:drug effects; D003080:Cold Temperature; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology; D005247:Feeding Behavior / Q000187:drug effects*; D008522:Mediterranean Sea; D015854:Up-Regulation / Q000187:drug effects; D014867:Water
chemical_list: D014867:Water; D002245:Carbon Dioxide; D002244:Carbon; D002119:Calcium Carbonate
keywords: Deep sea; Mediterranean Sea; Metabolic energy; Ocean acidification; Scleractinia