Some coral reefs are thriving, but they're not where you might think

A new study delves into data for more than 2,500 coral reefs across the globe, looking at a multitude of factors and comparing predicted levels of fish biomass with actual recordings.

First Look

At a time when any news about coral reefs tends to point to their demise, an international group of scientists has bucked the trend to bring us a measured account of optimism.

Determining that the world has for too long stood by and documented the decline of these vital ocean habitats, trying simply to understand their breakdown, they decided to consider data from more than 2,500 reefs worldwide in an effort to draw a roadmap toward preservation.

The results were undeniably a mixed affair, identifying 35 "dark spots," where reefs were doing less well than expected, alongside 15 "bright spots," where they were doing better than anticipated. But in considering a multitude of factors associated with these varying degrees of performance, the researchers have gained valuable – and surprising – insights into how the reefs might be saved.

"Most conservation approaches aim to identify and protect places of high ecological integrity under minimal threat," write the authors in a paper published Wednesday in the journal Nature. "Yet, with escalating social and environmental drivers of change, conservation actions are also needed where people and nature coexist, especially where human effects are already severe."

With this in mind, the researchers considered sites spanning 46 countries, states, and territories and examined 18 socioeconomic and environmental factors, including characteristics such as fishing patterns, tourism levels, accountability, and the nature of the reef itself. Based on these data, they made predictions about the levels of reef fish biomass they would find, and then investigated the realities.

One of the biggest surprises of the results was a contradiction of the conventional wisdom that says places far from human impacts represent near-pristine areas where conservation efforts should be focused. Instead, most of the bright spots were to be found in fished, populated areas.

"We thought this was counterintuitive," coauthor Jack Kittinger of Conservation International told National Geographic. "You might expect a high dependency on the reefs to mean high harvesting and therefore a dark spot, but we found the converse is true. What we saw is that people who are dependent on it are more likely to be better stewards, perhaps because if they crash that resource they are really in trouble."

Indeed, as the researchers dug deeper into these bright spots associated with high human dependency, they found substantial levels of local engagement in resource management, as well as "sociocultural governance institutions," characterized by customary tenure or taboos.

An example was Karkar Island in Papua New Guinea where ecological feedbacks are used to implement a system of harvest rotation, and marine tenure permitted the exclusion of fishers from outside the local village.

An environmental factor that was also evident in most of the bright spots was proximity to deep water, perhaps providing a refuge where fish could retreat in the face of disturbance.

Dark spots also yielded a pattern of traits, often characterized by fishing technologies that allowed intensive exploitation, such as freezers that enabled the storage of large quantities of catch, or destructive netting techniques. There was also an association with environmental shocks such as coral bleaching or cyclones.

"Reefs are hugely threatened. I saw my own field site melt down and completely die," Julia Baum, an assistant biology professor from Canada's University of Victoria, told The Atlantic. "The danger is that we lose hope, or we feel like there's nothing to be done. That's why this study is so important. It shows that the end state of people relying on and using coral reefs doesn't have to be reef degradation."

So, where do we go from here?

The authors see two possible pathways leading from their work. One is to shift the conversation away from the preservation of pristine places, instead seeking to utilize the lessons learned from localities that have confronted multiple stressors and found a sustainable way of coexisting with reefs.

The second is to reinvigorate efforts to manage socio-economic drivers that can have such dramatic impacts on coral reef health, to shape governance intervention and social drivers such as markets and development.

"The long-term viability of coral reefs will ultimately depend on international action to reduce carbon emissions," conclude the authors. "However, fisheries remain a pervasive source of reef degradation, and effective local-level fisheries governance is crucial to sustaining ecological processes that give reefs the best chance of coping with global environmental change."

This report contains material from Reuters.