As conservation scientists, we know that marine protected areas (MPAs) are critical for maintaining coral reef health. Here at Conservation International, our work through the Marine Science and Seascapes programs has demonstrated the biological and socioeconomic benefits of MPAs. We know that they can increase fisheries yields, improve livelihoods and provide critical coastal protection by supporting healthy, thriving coral reefs.
Yet according to my recent research, which was just published in the journal Global Change Biology, corals continue to be threatened by climate change even within MPAs.
Working with my co-authors John Bruno of the University of North Carolina at Chapel Hill and Kenneth Casey of the National Oceanic and Atmospheric Administration, we compiled more than 8,000 surveys of coral cover inside and outside of nearly 300 MPAs around the world. We then combined these data with estimates of ocean temperature from satellite data. By looking at all of this information together, we were able to track whether protection within MPAs changes how much coral is lost from episodes when ocean temperature is warmer than usual.
Climate change is one of the key threats to coral reefs. Rising ocean temperatures can trigger a stress response in corals known as coral bleaching. If temperatures rise more than 1 degree Celsius beyond what they usually are in the summertime — especially for longer periods of time — corals can die. During the 1998 El Niño event, reefs around the Indian and Pacific oceans lost substantial amounts of corals. In 2002, another warm event had major impacts on the coral in the Great Barrier Reef, one of the most highly protected reefs in the world.
Although MPAs cannot do anything to alter the temperature of the water, scientists have often thought that by reducing other stressors, we may be able to use MPAs as a way to mitigate temperature driven coral loss. However, our work suggests that current MPA planning and design are not optimizing potential benefits. In order to rectify this situation, we need to be more strategic about where we decide to designate MPAs and how big they are.
These results emphasize the critical need to implement policies which reduce global greenhouse gas emissions — the benefits of which would extend beyond the boundaries of any protected area. Such policies, along with the continued protection of vulnerable and valuable coral reef populations in MPAs, will help us save these valuable resources for the millions of people that depend on them.
Elizabeth Selig is a conservation scientist in CI’s Science and Knowledge division.