[Coral-List] Coral Reef Degradation

Bruno, John jbruno at unc.edu
Mon Jul 25 22:42:04 EDT 2016

Dear Dennis,
“Perhaps the message here is that no reefs are outside the influence of humans?”
I agree.
Also, we have used this database (actually, the extended form using all years) to test whether MPAs can effectively mitigate coral loss. Our results suggest they can, but only after decades of effective implementation (Selig & Bruno, 2010) and not in response to warming (Selig et al., 2012). Local management did not generally decrease the negative effect of warm anomalies on coral cover. We also found that the negative effect of thermal stress was strongly dependent on pre-disturbance coral cover (higher cover reefs were much more susceptible when holding the magnitude of thermal stress constant). This result has been observed in numerous local and regional studies (e.g., Graham et al., 2008) and also in meta-analyses of resistance to other types of disturbances (e.g., Zhang et al., 2014). This finding is one reason why the combined effects of warming and local stressors could be antagonistic, rather than synergistic as widely assumed. I.e., other disturbances could make a reef less susceptible to warming by reducing coral cover and/or the cover of disturbance-sensitive species (Côté & Darling, 2010).
Note, the results of our study (http://www.nature.com/articles/srep29778) do not indicate local impacts do not matter/do not effect coral cover – clearly they sometimes do. Instead the results suggest that local impacts are either swamped by warming or that local and global stressors are antagonistic, rather than synergistic. The results also do not suggest we shouldn’t manage locally! IMO there are numerous obvious benefits of restoring coral reef fish communities and reducing coastal pollution, even if those actions don’t measurably benefit corals in a warming world. In other words, I believe local management is necessary but insufficient to conserve / restore coral communities.
John Bruno
Professor, Dept of Biology
UNC Chapel Hill

Côté IM., Darling ES. 2010. Rethinking Ecosystem Resilience in the Face of Climate Change. PLoS Biology 8:e1000438. DOI: 10.1371/journal.pbio.1000438.

Graham NAJ., McClanahan TR., MacNeil MA., Wilson SK., Polunin NVC., Jennings S., Chabanet P., Clark S., Spalding MD., Letourneur Y., Bigot L., Galzin R., Ohman MC., Garpe KC., Edwards AJ., Sheppard CRC. 2008. Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems. PLoS ONE 3:e3039.

Selig ER., Bruno JF. 2010. A global analysis of the effectiveness of marine protected areas in preventing coral loss. PLoS One 5:e9278.

Selig ER., Casey KS., Bruno JF. 2012. Temperature-driven coral decline: the role of marine protected areas. Global Change Biology 18:1561–1570. DOI: 10.1111/j.1365-2486.2012.02658.x.

Zhang SY., Speare KE., Long ZT., McKeever KA., Gyoerkoe M., Ramus AP., Mohorn Z., Akins KL., Hambridge SM., Graham NAJ., Nash KL., Selig ER., Bruno JF. 2014. Is coral richness related to community resistance to and recovery from disturbance? PeerJ 2:e308. DOI: 10.7717/peerj.308.

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