Resistance of Two Mediterranean Cold-Water Coral Species to Low-pH Conditions

Abstract

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. OPEN ACCESSWater 2014, 6 60

Intra-Specific Variation Reveals Potential for Adaptation to Ocean Acidification in a Cold-Water Coral from the Gulf of Mexico

“…These results contrast with what has been found so far in other long-term experiments where there has not been a significant negative response in calcification for L. pertusa (Form and Riebesell, 2012;Maier et al, 2013;Movilla et al, 2014;Hennige et al, 2015) and for other cold-water coral species (Carreiro-Silva et al, 2014;Rodolfo-Metalpa et al, 2015;Gori et al, 2016). However, the majority of the studies performed in cold-water corals to date have used pH levels that still yielded ar saturation states at or near 1.…”

“…This is the first long-term experiment performed on L. pertusa from the Gulf of Mexico, although long-term experiments have been conducted using L. pertusa from the North Atlantic (Form and Riebesell, 2012;Hennige et al, 2015), and the Mediterranean sea (Maier et al, 2013;Movilla et al, 2014). Our results showed a significant effect of time and pH, where corals in the control treatment (pH 7.9) maintained positive net calcification, while, on average, corals in the acidified treatment (pH = 7.6) experienced declining net calcification rate over time and net dissolution by the end of the 6-month period.…”

Impact of Ocean Acidification on Marine Organisms—Unifying Principles and New Paradigms

“…The finding that simulated ocean acidification had no significant effects on the growth and skeletal structure of the adult stages of two widespread cold-water corals [3], but can be particularly severe for organisms which start to calcify in their larval and/or juvenile stages [1] and there may also be indirect effects through loss of food quality since rising CO2 levels affect the biochemistry of phytoplankton [7,8] highlights the fact that there is likely to be significant variations in species' responses. The otoliths of squid embryos are affected by the combined effects of acidification and lowered oxygen, although conditions within the brood capsule also affect their geochemistry.…”

“…Few studies have been carried out on the vulnerability of deep-sea organisms to ocean acidification yet this is an important topic since deep-water ecosystems are expected to be among the first to be exposed to waters that are corrosive to calcium carbonate. Movilla et al [3] investigated the effects of decreased pH on calcification of Madrepora oculata and Lophelia pertusa, which are widely distributed in the Mediterranean. Surprisingly, they found no significant effects of acidification on skeletal growth rate, microdensity and porosity in either species after 6 months incubation in aquaria.…”

“…Juancho Movilla from the Institut de Ciències del Mar in Barcelona conducted a study concerning the resistance of two Mediterranean cold-water coral species to long term exposure to low pH with co-workers in the same institute and with researchers at the Spanish Centro Oceanográfico de Baleares and the Institució Catalana de Recerca i Estudis Avançats [3]. Few studies have been carried out on the vulnerability of deep-sea organisms to ocean acidification yet this is an important topic since deep-water ecosystems are expected to be among the first to be exposed to waters that are corrosive to calcium carbonate.…”