Effects of seawater pCO2 and temperature on calcification and productivity in the coral genus Porites spp.: an exploration of potential interaction mechanisms

• Published in: Coral reefs Vol. 37; no. 2; pp. 471 - 481
• Main Authors: Cole, C., Finch, A. A., Hintz, C., Hintz, K., Allison, N.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-06-2018; Springer Nature B.V
• Subjects: Accretion; Acidification; Aragonite; Biomedical and Life Sciences; Calcification; Corals; Deposition; Ecosystems; Exploration; Freshwater & Marine Ecology; Genotypes; Life Sciences; Ocean acidification; Oceanography; Photosynthesis; Porites; Productivity; Respiration; Seawater; Temperature dependence; Temperature effects; Thermal stress; Water temperature; Productivity; Calcification; Ocean acidification; Coral; Seawater temperature
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s00338-018-1672-3

Understanding how rising seawater
p
CO
2
and temperatures impact coral aragonite accretion is essential for predicting the future of reef ecosystems. Here, we report 2 long-term (10–11 month) studies assessing the effects of temperature (25 and 28 °C) and both high and low seawater
p
CO
2
(180–750 μatm) on the calcification, photosynthesis and respiration of individual massive
Porites
spp. genotypes. Calcification rates were highly variable between genotypes, but high seawater
p
CO
2
reduced calcification significantly in 4 of 7 genotypes cultured at 25 °C but in only 1 of 4 genotypes cultured at 28 °C. Increasing seawater temperature enhanced calcification in almost all corals, but the magnitude of this effect was seawater
p
CO
2
dependent. The 3 °C temperature increase enhanced calcification rate on average by 3% at 180 μatm, by 35% at 260 μatm and by > 300% at 750 μatm. The rate increase at high seawater
p
CO
2
exceeds that observed in inorganic aragonites. Responses of gross/net photosynthesis and respiration to temperature and seawater
p
CO
2
varied between genotypes, but rates of all these processes were reduced at the higher seawater temperature. Increases in seawater temperature, below the thermal stress threshold, may mitigate against ocean acidification in this coral genus, but this moderation is not mediated by an increase in net photosynthesis. The response of coral calcification to temperature cannot be explained by symbiont productivity or by thermodynamic and kinetic influences on aragonite formation.