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1. Ocean acidification effects on in situ coral reef metabolism

   https://doi.org/10.1038/s41598-019-48407-7  

   Doo, Steve S.; Edmunds, Peter J.; Carpenter, Robert C. (August 2019, Scientific Reports)

   Abstract The Anthropocene climate has largely been defined by a rapid increase in atmospheric CO_2,causing global climate change (warming) and ocean acidification (OA, a reduction in oceanic pH). OA is of particular concern for coral reefs, as the associated reduction in carbonate ion availability impairs biogenic calcification and promotes dissolution of carbonate substrata. While these trends ultimately affect ecosystem calcification, scaling experimental analyses of the response of organisms to OA to consider the response of ecosystems to OA has proved difficult. The benchmark of ecosystem-level experiments to study the effects of OA is provided through Free Ocean CO₂Enrichment (FOCE), which we use in the present analyses for a 21-d experiment on the back reef of Mo’orea, French Polynesia. Two natural coral reef communities were incubatedin situ, with one exposed to ambient pCO₂(393 µatm), and one to high pCO₂(949 µatm). Our results show a decrease in 24-h net community calcification (NCC) under high pCO₂, and a reduction in nighttime NCC that attenuated and eventually reversed over 21-d. This effect was not observed in daytime NCC, and it occurred without any effect of high pCO₂on net community production (NCP). These results contribute to previous studies on ecosystem-level responses of coral reefs to the OA conditions projected for the end of the century, and they highlight potential attenuation of high pCO₂effects on nighttime net community calcification. 

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2. Scaling the effects of ocean acidification on coral growth and coral–coral competition on coral community recovery

   https://doi.org/10.7717/peerj.11608  

   Evensen, Nicolas R.; Bozec, Yves-Marie; Edmunds, Peter J.; Mumby, Peter J. (January 2021, PeerJ)

   Ocean acidification (OA) is negatively affecting calcification in a wide variety of marine organisms. These effects are acute for many tropical scleractinian corals under short-term experimental conditions, but it is unclear how these effects interact with ecological processes, such as competition for space, to impact coral communities over multiple years. This study sought to test the use of individual-based models (IBMs) as a tool to scale up the effects of OA recorded in short-term studies to community-scale impacts, combining data from field surveys and mesocosm experiments to parameterize an IBM of coral community recovery on the fore reef of Moorea, French Polynesia. Focusing on the dominant coral genera from the fore reef, Pocillopora , Acropora , Montipora and Porites , model efficacy first was evaluated through the comparison of simulated and empirical dynamics from 2010–2016, when the reef was recovering from sequential acute disturbances (a crown-of-thorns seastar outbreak followed by a cyclone) that reduced coral cover to ~0% by 2010. The model then was used to evaluate how the effects of OA (1,100–1,200 µatm pCO 2 ) on coral growth and competition among corals affected recovery rates (as assessed by changes in % cover y −1 ) of each coral population between 2010–2016. The model indicated that recovery rates for the fore reef community was halved by OA over 7 years, with cover increasing at 11% y −1 under ambient conditions and 4.8% y −1 under OA conditions. However, when OA was implemented to affect coral growth and not competition among corals, coral community recovery increased to 7.2% y −1 , highlighting mechanisms other than growth suppression (i.e., competition), through which OA can impact recovery. Our study reveals the potential for IBMs to assess the impacts of OA on coral communities at temporal and spatial scales beyond the capabilities of experimental studies, but this potential will not be realized unless empirical analyses address a wider variety of response variables representing ecological, physiological and functional domains. 

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3. Responses of coral reef community metabolism in flumes to ocean acidification

   https://doi.org/10.1007/s00227-018-3324-0  

   Carpenter, R. C.; Lantz, C. A.; Shaw, E.; Edmunds, P. J. (April 2018, Marine Biology)
4. Ocean Acidification Has Impacted Coral Growth on the Great Barrier Reef

   https://doi.org/10.1029/2019GL086761  

   Guo, Weifu; Bokade, Rohit; Cohen, Anne L.; Mollica, Nathaniel R.; Leung, Muriel; Brainard, Russell E. (October 2020, Geophysical Research Letters)

   null (Ed.)
5. Widespread scope for coral adaptation under combined ocean warming and acidification

   https://doi.org/10.1098/rspb.2024.1161  

   Jury, Christopher P; Toonen, Robert J (September 2024, Proceedings of the Royal Society B: Biological Sciences)

   Reef-building coral populations are at serious risk of collapse due to the combined effects of ocean warming and acidification. Nonetheless, many corals show potential to adapt to the changing ocean conditions. Here we examine the broad sense heritability (H²) of coral calcification rates across an ecologically and phylogenetically diverse sampling of eight of the primary reef-building corals across the Indo-Pacific. We show that all eight species exhibit relatively high heritability of calcification rates under combined warming and acidification (0.23–0.56). Furthermore, tolerance to each factor is positively correlated and the two factors do not interact in most of the species, contrary to the idea of trade-offs between temperature and pH sensitivity, and all eight species can co-evolve tolerance to elevated temperature and reduced pH. Using these values together with historical data, we estimate potential increases in thermal tolerance of 1.0–1.7°C over the next 50 years, depending on species. None of these species are probably capable of keeping up with a high global change scenario and climate change mitigation is essential if reefs are to persist. Such estimates are critical for our understanding of how corals may respond to global change, accurately parametrizing modelled responses, and predicting rapid evolution. 

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