John Bruno kicks off another part of his Reef Science coral series, excerpting a modified version of an article he published last year on the Earth Portal about Coral Reefs and Climate Change. He covers global patterns of coral loss and several of the mechanisms through which anthropogenic climate change is contributing to this trend including coral bleaching, disease and ocean acidification. Let him know know if there are particular topics you want to hear about. You can reach him at firstname.lastname@example.org.
In addition to the global and regional effects of climate change, there are several localized threats and impacts to coral reef ecosystems. Reef fishes and some invertebrates are intensely harvested, which has greatly reduced their abundances and altered food web dynamics on all but the most isolated or intensely managed reefs. Additionally, some fishing practices such as dynamite fishing and muro ami directly kill corals and can destroy the reef matrix.
Reefs are also threatened by many other local activities such as coastal agriculture and development that increase sediment runoff into watersheds and sedimentation rates on coastal reefs, in some cases smothering and killing corals. Some scientists believe that these and other local impacts could act synergistically with climate change, thereby magnifying the negative effects of both types of stressors.
There has been little work on this idea, but it seems clear that reef managers, policy makers and conservationists will have to act on many fronts at several political levels to begin to protect reef ecosystems from this diverse list of threats. Halting and reversing coral loss will require actions across a range of scales including:
Local restoration and conservation of herbivores that facilitate coral recruitment and the reduction of fishing practices that directly kill corals.
The implementation of regional land use practices that reduce sedimentation and nutrient pollution.
The institution of global policies to reduce anthropogenic ocean warming and acidification.
We can do a far better job of developing technologies and implementing smart policies that will reduce greenhouse gas emissions. However, there is substantial political resistance to this and no matter what we do we are already committed to at least some increased warming and acidification. But until we address and reverse anthropogenic climate change, we can reduce at least some of the local stressors that are compounding its effects.
Dr. John Bruno is a marine ecologist and conservation biologist. He's also an associate professor in the Department of Marine Science at the University of North Carolina at Chapel Hill . His research is focused on understanding and conserving the structure and dynamics of marine communities. Dr. Bruno works in a variety of marine habitats including coral reefs, coastal wetland and sand dune plant communities, oyster reefs and seagrass beds. Read more of his work on The Climate Shifts blog, and check out the Bruno lab home page.