Ocean warming and acidification synergistically increase coral mortality

• DOI: 10.1038/srep40842
• Publication Date: 2017-01-19T14:18:15Z
• Authors: F. Prada; E. Caroselli; S. Mengoli; L. Brizi; P. Fantazzini; B. Capaccioni; L. Pasquini; K. E. Fabricius; Z. Dubinsky; G. Falini; S. Goffredo
• Keywords: 0106 biological sciences; Coral Reefs; Temperature; Hydrogen-Ion Concentration; Anthozoa; Global Warming; 01 natural sciences; Article; Calcium Carbonate; ocean warming (OW); ocean acidification (OA); mortality and growth of Mediterranean coral species; natural pH gradient; CO2 vents; solitary and colonial, symbiotic and asymbiotic corals;net calcification rate;; 13. Climate action; Mediterranean Sea; Animals; Seawater; 14. Life underwater; Ecosystem

AbstractOrganisms that accumulate calcium carbonate structures are particularly vulnerable to ocean warming (OW) and ocean acidification (OA), potentially reducing the socioeconomic benefits of ecosystems reliant on these taxa. Since rising atmospheric CO2is responsible for global warming and increasing ocean acidity, to correctly predict how OW and OA will affect marine organisms, their possible interactive effects must be assessed. Here we investigate, in the field, the combined temperature (range: 16–26 °C) and acidification (range: pHTS8.1–7.4) effects on mortality and growth of Mediterranean coral species transplanted, in different seasonal periods, along a natural pH gradient generated by a CO2vent. We show a synergistic adverse effect on mortality rates (up to 60%), for solitary and colonial, symbiotic and asymbiotic corals, suggesting that high seawater temperatures may have increased their metabolic rates which, in conjunction with decreasing pH, could have led to rapid deterioration of cellular processes and performance. The net calcification rate of the symbiotic species was not affected by decreasing pH, regardless of temperature, while in the two asymbiotic species it was negatively affected by increasing acidification and temperature, suggesting that symbiotic corals may be more tolerant to increasing warming and acidifying conditions compared to asymbiotic ones.