Unprecedented Levels Of Coral Reef Loss

While not breaking news to me, PLoS One has a sobering paper that documents the regional decline of coral cover in the Indo-Pacific. Coral cover is a measure of the ocean floor area covered by living corals--regarded as a key indicator of reef habitat quality and quantity. Authored by John Bruno and Elizabeth Selig from the University of North Carolina at Chapel Hill, the study indicates that the rate and extent of coral loss in the Indo-Pacific are greater than previously expected. What I find particularly chilling is that while coral cover is surprisingly uniform among subregions studied, overall coral cover has declined decades earlier than previously assumed, even on some of the Pacific's most intensely managed reefs. The histograms above illustrate percent coral cover in the Indo-Pacific and selected subregions during different periods.

I've commented before on the challenges that limit marine protected area (MPA) effectiveness. Most MPAs are understaffed, under funded, or their protected status is on paper only. Still, according to the science that supports marine resource management, they are the best defense we have against loss of marine biodiversity. Recognizing this, a growing alliance of Pacific nations are teaming together to meet the challenges facing their marine resources. But is it too little, too late? Certainly this study provides the first regional-scale and long-term analysis of coral loss in the region where relatively little was known about patterns of reef loss.

Even in Pacific regions labeled "best managed," not surprisingly Hawaii and Australia's Great Barrier Reef, where coral cover loss has been less severe, the authors are quick to point out that coral cover represents only one measure of overall reef health. A complete picture must factor in the reduction in the overall quality of reef habitat. This includes the presence of the foundation species that generate the physical reef framework as well the composition of species that live in and around that framework.

As the authors summarize, these results have significant implications for policy makers and resource managers as they search for successful models to reverse coral loss. While coral reef stressors are legion, management approaches need to be more adaptive to the individual needs of a region. Building reef resilience might be a moving target. But if we can measurably reduce the stressors within our capacity to address, perhaps we provide breathing room for sensitive marine ecosystems to better weather the long term challenges.

Source: PLoS One