Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification

Abstract

Ocean acidification (OA) and its associated decline in calcium carbonate saturation states is one of the major threats that tropical coral reefs face this century. Previous studies of the effect of OA on coral reef calcifiers have described a wide variety of outcomes for studies using comparable partial pressure of CO 2 (pCO 2 ) ranges, suggesting that key questions remain unresolved. One unresolved hypothesis posits that heterogeneity in the response of reef calcifiers to high pCO 2 is a result of regional-scale variation in the responses to OA. To test this hypothesis, we incubated two coral taxa (Pocillopora damicornis and massive Porites) and two calcified algae (Porolithon onkodes and Halimeda macroloba) under 400, 700 and 1000 matm pCO 2 levels in experiments in Moorea (French Polynesia), Hawaii (USA) and Okinawa (Japan), where environmental conditions differ. Both corals and H. macroloba were insensitive to OA at all three locations, while the effects of OA on P. onkodes were locationspecific. In Moorea and Hawaii, calcification of P. onkodes was depressed by high pCO 2 , but for specimens in Okinawa, there was no effect of OA. Using a study of large geographical scale, we show that resistance to OA of some reef species is a constitutive character expressed across the Pacific.

Ocean acidification influences hostDNAmethylation and phenotypic plasticity in environmentally susceptible corals

“…), whereas exposure of P. damicornis to 1000 μatm pCO 2 resulted in ~28% decline in calcification compared to ambient pCO 2 (500 μatm, Comeau et al. ). The acclimation of M. capitata calcification and DNA methylation to control levels by week 6, while P. damicornis maintained differences in both factors, suggests that there could be a direct role for DNA methylation of biomineralization control.…”

Coralline algae (Rhodophyta) in a changing world: integrating ecological, physiological, and geochemical responses to global change

“…Comeau et al. () found variable, location‐specific responses to elevated p CO 2 in the nongeniculate coralline Porolithon onkodes across sites that differ in environmental conditions and carbon chemistry across the tropical Pacific, showing yet another degree of response variability. In another example, thick, slow‐growing species reduced their thallus thickness while keeping skeletal density and cell wall thicknesses constant (McCoy , McCoy and Ragazzola ).…”

Environmental and physiochemical controls on coral calcification along a latitudinal temperature gradient in Western Australia

“…In addition to ocean warming, increasing CO 2 is driving declines in seawater pH and thus seawater aragonite saturation state (Ω = [][Ca 2+ ]/ K sp ). OA can result in morphological deformities in juvenile corals (Cohen, McCorkle, de Putron, Gaetani, & Rose, ; Foster, Falter, McCulloch, & Clode, ) and a reduction in coral calcification rates for some adult corals (e.g., Crook, Cohen, Rebolledo‐Vieyra, Hernandez, & Paytan, ; Jokiel et al, ; Marubini et al, ; Marubini, Ferrier‐Pagès, & Cuif, ; Mollica et al, ), although this is not always the case (e.g., Comeau et al, ; Comeau, Cornwall, DeCarlo, Krieger, & McCulloch, ; Jury, Whitehead, & Szmant, ; Schoepf et al, ). Variation in the responses of coral calcification to OA can be explained by differences in species, life stage, food availability, growth form (e.g., Albright & Langdon, ; Cohen & Holcomb, ; Kornder, Riegl, & Figueiredo, ), and bio‐calcification mechanisms (e.g., Comeau et al, ; DeCarlo, Comeau, Cornwall, & McCulloch, ; Georgiou et al, ; Schoepf, Jury, Toonen, & McCulloch, ).…”