Effects of low pH and feeding on calcification rates of the cold-water coral Desmophyllum dianthus

• Main Authors: Martínez-Dios, Ariadna, Pelejero, Carles, López-Sanz, Àngel, Sherrell, Robert M., Ko, Stanley, Häussermann, Vreni, Försterra, Günter, Calvo, Eva María
• Other Authors: Consejo Superior de Investigaciones Científicas (España), Fundación Endesa, Fundación San Ignacio del Huinay, Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: PeerJ 2020
• Subjects: Scleractinian corals; Deep-sea corals; Ocean acidification; Global change; Coral calcification; Carbonate saturation; Coral feeding; Ocean acidification
• Online Access: http://hdl.handle.net/10261/209325; https://doi.org/10.7717/peerj.8236; https://doi.org/10.13039/501100003329; https://doi.org/10.13039/501100003339; https://doi.org/10.13039/501100007827; https://doi.org/10.13039/501100007829; https://doi.org/10.13039/501100011033

28 pages, 5 figures, 6 tables, supplemental information https://doi.org/10.7717/peerj.8236/supp-1 and https://doi.org/10.7717/peerj.8236/supp-2.-- The data on weight, calcification rate and mortality of D. dianthus corals during the experiment is available as a Supplemental File https://doi.org/10.7717/peerj.8236/supp-1 Cold-Water Corals (CWCs), and most marine calcifiers, are especially threatened by ocean acidification (OA) and the decrease in the carbonate saturation state of seawater. The vulnerability of these organisms, however, also involves other global stressors like warming, deoxygenation or changes in sea surface productivity and, hence, food supply via the downward transport of organic matter to the deep ocean. This study examined the response of the CWC Desmophyllum dianthus to low pH under different feeding regimes through a long-term incubation experiment. For this experiment, 152 polyps were incubated at pH 8.1, 7.8, 7.5 and 7.2 and two feeding regimes for 14 months. Mean calcification rates over the entire duration of the experiment ranged between ¿0.3 and 0.3 mg CaCO3 g¿1d¿1. Polyps incubated at pH 7.2 were the most affected and 30% mortality was observed in this treatment. In addition, many of the surviving polyps at pH 7.2 showed negative calcification rates indicating that, in the long term, CWCs may have difficulty thriving in such aragonite undersaturated waters. The feeding regime had a significant effect on skeletal growth of corals, with high feeding frequency resulting in more positive and variable calcification rates. This was especially evident in corals reared at pH 7.5 (¿A = 0.8) compared to the low frequency feeding treatment. Early life-stages, which are essential for the recruitment and maintenance of coral communities and their associated biodiversity, were revealed to be at highest risk. Overall, this study demonstrates the vulnerability of D. dianthus corals to low pH and low food availability. Future projected pH decreases and related changes in zooplankton communities may ...