A new study of coral reefs in Fiji finds that protecting a few well-connected reefs and tackling both overfishing and pollution together can strengthen entire reef networks. The work offers a practical roadmap for safeguarding coral ecosystems and the communities that depend on them.
Coral reefs are often described as underwater rainforests, but many are sliding toward collapse under the combined weight of climate change, pollution and overfishing. New research from an international team, published in the journal Ecological Applications, suggests there is a powerful way to push back: protect the right reefs, and protect land and sea together.
By modeling a network of coral reefs in Fiji, scientists found that connections between reefs can help stabilize reef health and spread the benefits of conservation far beyond the places that are directly protected. Their results point to a more hopeful future for reefs if managers focus on both fishing and water quality, and on how reefs are linked by drifting coral larvae.
Lead researcher Ariel Greiner of the University of Oxford said the work challenges the way coral reefs have often been managed.
“For too long, coral reefs have been managed in isolation. Our research shows that when we account for connections between reefs, we find that they are far more stable than previously thought. Protecting a few key reefs can help sustain high coral cover across the entire network – the key is identifying which ones to protect. We also illustrate that strategies that address both overfishing and land-based pollution together deliver the strongest and most lasting results,” she said in a news release.
The study, carried out by researchers from the University of Oxford, the University of Toronto, the National Research Council of Italy and the Wildlife Conservation Society (WCS), used a mathematical model of a Fijian reef network to test different management strategies over time.
The team simulated future reef conditions under three scenarios: reducing fishing pressure to boost herbivorous fish that graze on algae, cutting land-based runoff that increases coral death, and combining both actions. These local pressures are especially important in Fiji, where many reefs are considered climate refuges that have so far been less affected by global warming and mass bleaching and can naturally recover from storms and other shocks.
When the researchers compared outcomes, the combined strategy clearly came out on top. Tackling both overfishing and pollution together produced the healthiest reefs and the most resilient reef network, even when the model included uncertainty about key ecological conditions. That robustness suggests the findings could guide real-world decisions in Fiji and in other reef systems.
The model also revealed the power of connections. Coral reefs are linked by the dispersal of tiny coral larvae, which drift on ocean currents before settling and growing into new colonies. The study found that closing fisheries to improve grazing on less than half of the reefs in the network could still increase coral cover across the entire system, thanks to those larval connections.
In other words, protecting a strategically chosen subset of reefs can send out a steady supply of young corals that help sustain many other sites. That kind of network-based planning, which looks at how reefs support each other rather than treating each reef as an isolated patch, is still relatively rare in marine conservation but may be crucial for long-term success.
The researchers also used the model to explore how these connections affect the risk of a reef tipping from a healthy, coral-dominated state to a degraded one dominated by algae or other organisms. In many simple models that focus on single reefs or pairs of reefs, there is a stark either-or outcome: reefs tend to be either coral-rich or coral-poor.
That picture changes when you zoom out to the scale of an entire reef network, according to Greiner.
“Our study shows that when we include realistic dispersal connectivity between many reefs, the duality of coral- or non-coral-dominated reefs that we see in models of single or pairs of reefs disappears when we consider entire networks of reefs. This is a novel, unexpected, and exciting result with impacts for coral reef management, and for our understanding of coral reef dynamics globally,” Greiner added.
That finding suggests that the movement of juvenile corals among reefs can help stabilize the system as a whole, lowering the risk that any one reef will permanently flip into a degraded state. For managers, it underscores the importance of keeping those connections intact and factoring them into conservation plans.
To evaluate which management actions matter most, the team paired their ecological model with a tool known as value of information analysis. This method, more commonly used in fields like economics and public health, helps decision-makers weigh the benefits of different choices under uncertainty and identify where better data would most improve decisions.
Applied to coral reefs, the approach allowed the researchers to test how different combinations of fishing rules and pollution controls might play out over large areas and long timeframes, and to see which strategies remained effective even when the exact details of reef dynamics were not fully known.
Emily Darling, director of coral reefs at WCS and a co-author on the study, noted that the modeling offers a way to look ahead and make smarter choices now.
“This study shows how modelling can help forecast the long-term consequences of today’s conservation decisions and pinpoint the actions that build lasting resilience for reefs facing multiple pressures,” she said in the news release.
The results are not just academically interesting, but directly usable by governments, communities and conservation groups.
“What’s powerful about these findings is their practicality: when we focus on climate-resilient coral reefs, coordinated efforts to reduce fishing pressure and improve water quality can generate outsized benefits across entire reef networks. This gives decision-makers a realistic path to protect ecosystems while supporting the communities who depend on them,” Darling added.
Coral reefs support an estimated quarter of all marine species and provide food, coastal protection and income from tourism and fisheries for hundreds of millions of people worldwide. Yet they are among the ecosystems most threatened by climate change, with rising ocean temperatures driving more frequent and severe bleaching events.
The new work does not diminish the need to cut global greenhouse gas emissions. But it shows that local actions, if well designed and coordinated, can still make a major difference, especially in places like Fiji where some reefs have natural resistance or resilience to warming.
Next, the researchers plan to apply their approach to other reef systems around the world and to expand their models to include human behavior more explicitly. That could mean exploring how tourism-funded conservation, community-based management or changes in local economies affect reef health and the success of different strategies.
They also aim to better understand when the dispersal of young corals and competing organisms like macroalgae will stabilize local reef dynamics and when it might instead spread degradation.
For coastal communities and policymakers, the message is that there is still room to act. By recognizing how reefs are connected, and by pairing protections in the water with better practices on land, it may be possible to keep coral networks thriving even in a warming world.
Source: University of Oxford