Tag Archives: coral reefs

Gulf Aqaba corals resilient to ocean warming and acidification

Jessica Bellworthy, Malika Menoud, Thomas Krueger, Anders Meibom, Maoz Fine. Developmental carryover effects of ocean warming and acidification in corals from a potential climate refugium, the Gulf of Aqaba. Journal of Experimental Biology, 2019, 222: doi: 10.1242/jeb.186940 Published 2 January 2019.

Coral reefs are degrading from the effects of anthropogenic activities, including climate change. Under these stressors, their ability to survive depends upon existing phenotypic plasticity, but also transgenerational adaptation. Parental effects are ubiquitous in nature, yet empirical studies of these effects in corals are scarce, particularly in the context of climate change. This study exposed mature colonies of the common reef-building coral Stylophora pistillata from the Gulf of Aqaba to seawater conditions likely to occur just beyond the end of this century during the peak planulae brooding season (Representative Concentration Pathway 8.5: pH −0.4 and +5°C beyond present day). Parent and planulae physiology were assessed at multiple time points during the experimental incubation. After 5 weeks of incubation, the physiology of the parent colonies exhibited limited treatment-induced changes. All significant time-dependent changes in physiology occurred in both ambient and treatment conditions. Planulae were also resistant to future ocean conditions, with protein content, symbiont density, photochemistry, survival and settlement success not significantly different compared with under ambient conditions. High variability in offspring physiology was independent of parental or offspring treatments and indicate the use of a bet-hedging strategy in this population. This study thus demonstrates weak climate-change-associated carryover effects. Furthermore, planulae display temperature and pH resistance similar to those of adult colonies and therefore do not represent a larger future population size bottleneck. The findings add support to the emerging hypothesis that the Gulf of Aqaba may serve as a coral climate change refugium aided by these corals’ inherent broad physiological resistance.

Coral reef fish not impaired by ocean acidification

Timothy D. Clark, Graham D. Raby, Dominique G. Roche, Sandra A. Binning, Ben Speers-Roesch, Fredrik Jutfelt, Josefin Sundin. Ocean acidification does not impair the behaviour of coral reef fishes. Nature (2020) doi:10.1038/s41586-019-1903-y

The partial pressure of CO2 in the oceans has increased rapidly over the past century, driving ocean acidification and raising concern for the stability of marine ecosystems1,2,3. Coral reef fishes are predicted to be especially susceptible to end-of-century ocean acidification on the basis of several high-profile papers4,5 that have reported profound behavioural and sensory impairments—for example, complete attraction to the chemical cues of predators under conditions of ocean acidification. Here, we comprehensively and transparently show that—in contrast to previous studies—end-of-century ocean acidification levels have negligible effects on important behaviours of coral reef fishes, such as the avoidance of chemical cues from predators, fish activity levels and behavioural lateralization (left–right turning preference). Using data simulations, we additionally show that the large effect sizes and small within-group variances that have been reported in several previous studies are highly improbable. Together, our findings indicate that the reported effects of ocean acidification on the behaviour of coral reef fishes are not reproducible, suggesting that behavioural perturbations will not be a major consequence for coral reef fishes in high CO2 oceans.

The Great Barrier Reef adapts to ecosystem changes

“The Great Barrier Reef spans 2,000 kilometers and five degrees Celsius from 27 to 32°C and we’re still finding reefs we didn’t even know about. The pH swings on a daily basis, and fish do better when it does. One coral has adapted to ocean “acidification” in 6 months. Other fish remarkably adapted from salt to freshwater in just fifty years. As Peter Ridd says: Of all the ecosystems in the world, the reef is one that’s best at adapting to climate change.click here