Publication Date:
2024-03-15
Description:
Corals are globally important calcifiers that exhibit complex responses to anthropogenic warming and acidification. Although coral calcification is supported by high seawater pH, photosynthesis by the algal symbionts of zooxanthellate corals can be promoted by elevated pCO2. To investigate the mechanisms underlying corals' complex responses to global change, three species of tropical zooxanthellate corals (Stylophora pistillata, Pocillopora damicornis, and Seriatopora hystrix) and one species of asymbiotic cold-water coral (Desmophyllum pertusum, syn. Lophelia pertusa) were cultured under a range of ocean acidification and warming scenarios. Under control temperatures, all tropical species exhibited increased calcification rates in response to increasing pCO2. However, the tropical species' response to increasing pCO2 flattened when they lost symbionts (i.e., bleached) under the high-temperature treatments—suggesting that the loss of symbionts neutralized the benefit of increased pCO2 on calcification rate. Notably, the cold-water species that lacks symbionts exhibited a negative calcification response to increasing pCO2, although this negative response was partially ameliorated under elevated temperature. All four species elevated their calcifying fluid pH relative to seawater pH under all pCO2 treatments, and the magnitude of this offset (Δ[H+]) increased with increasing pCO2. Furthermore, calcifying fluid pH decreased along with symbiont abundance under thermal stress for the one species in which calcifying fluid pH was measured under both temperature treatments. This observation suggests a mechanistic link between photosymbiont loss ('bleaching') and impairment of zooxanthellate corals' ability to elevate calcifying fluid pH in support of calcification under heat stress. This study supports the assertion that thermally induced loss of photosymbionts impairs tropical zooxanthellate corals' ability to cope with CO2-induced ocean acidification.
Keywords:
Acid-base regulation; Alkalinity, total; Alkalinity, total, standard error; Ammonium; Ammonium, standard error; Animalia; Aragonite saturation state; Aragonite saturation state, standard error; Benthic animals; Benthos; Bicarbonate; Bicarbonate ion; Bicarbonate ion, standard error; Bottles or small containers/Aquaria (〈20 L); Buoyant mass; Calcification/Dissolution; Calcification rate; Calcification rate, standard deviation; Calcifying fluid, pH; Calcifying fluid, pH, standard deviation; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard error; Carbonate ion; Carbonate ion, standard error; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard error; Cnidaria; Dry mass; Dry mass, standard deviation; Experiment duration; Fragments; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Laboratory experiment; Laboratory strains; Lophelia pertusa; Mass, standard deviation; Mortality; Mortality/Survival; Nitrate; Nitrate, standard error; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Partial pressure of carbon dioxide (water) at sea surface temperature (wet air), standard error; pH; pH, standard error; Phosphate; Phosphate, standard error; Pocillopora damicornis; Salinity; Salinity, standard error; Score; Score, standard deviation; Seriatopora hystrix; Single species; Species, unique identification; Species, unique identification (Semantic URI); Species, unique identification (URI); Stylophora pistillata; Temperature; Temperature, water; Temperature, water, standard error; Treatment; Type
Type:
Dataset
Format:
text/tab-separated-values, 1378 data points
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