New models show that connections between climate-resilient coral reefs can help recover biodiversity even under future climate change and coral bleaching scenarios
Healthy “stepping stone” reefs will be critical to find and protect, to create a connected network of biodiversity hotspots that oceans will need to rebound after bleaching events
Steps taken now to curb global emissions and protect an international network of coral reef strongholds will pay dividends in the coming decades
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New York, NY (August 3, 2022) – A new study from WCS, the University of Toronto and the National Research Council of Italy has shed light on coral reef “hope spots'' around the world. Findings show that climate-resilient reefs are connected in invisible underwater networks linked by tiny larval corals that travel from reef to reef on ocean currents. These networks have the ability to survive and re-seed ocean biodiversity, even after projected mass bleaching events from climate change.
“Our findings show how crucial it is to understand coral reef networks and how they may be affected by climate change, when designing future coral reef conservation strategies,” said Ariel Greiner, a PhD Candidate at the University of Toronto. “In particular, this study finds that these coral reef networks may help maintain coral reef strongholds and additional “stepping stone” reefs, reefs that serve as larval dispersal pathways between coral reef strongholds, will be needed to preserve the rest of global coral reef habitat.”
In the study, scientists looked at models of coral larval dispersal connections between reefs (also called coral connectivity). These connections form networks that serve to transport larval corals over vast distances to shuffle the gene pool and as a source of new individuals that help reefs recover from coral bleaching and other disturbances. By modeling connectivity under different scenarios of climate change and future coral bleaching, their results generate a preview of where reef habitat may be lost in coming decades as well as pinpointing which reefs will have the greatest potential to recover and re-seed other reefs. This new information will help direct limited resources for conservation at a crucial time for climate action.
There exist climate-resilient coral reef strongholds, some of which have been designated as ‘50 Reefs’, that are expected to have the best chance of surviving rising ocean temperatures. If these reefs survive, the researchers found that even after severe bleaching, coral connectivity (grouped into six major networks of interconnected reefs worldwide) will be largely preserved even if 71% of global coral reef habitat is lost. Their findings however indicate that “stepping stone” reefs, which create links across reef networks to better enable coral reef strongholds to re-seed corals around the world, should also be prioritized for conservation and management.
“Strategic conservation action is crucial in the face of climate change,” says Dr Emily Darling, Director of Coral Reef Conservation at WCS, an Adjunct Professor at U of T, and coauthor of the study. “These findings show that biological connections between reefs can increase the ability of corals to recover from climate shocks and are a call to action to boost the health and function of key ‘source’ reefs in climate-resilient networks.”
This study provides hope for the communities, scientists, governments, and institutions all over the world who rely on and steward coral reef ecosystems. If the global community curbs carbon emissions and limits warming to 1.5 degrees Celsius, coral reefs have a chance to survive climate change. Protecting the most climate-resilient reefs, and their connections between each other, will pay dividends in the decades to come.
The new paper, titled “Limited Spatial Rescue Potential for Coral Reefs Lost to Future Climate Warming”, was led by authors from the Department of Ecology & Evolutionary Biology at the University of Toronto, and appears in Volume 31, Issue 8 of the journal Global Ecology and Biogeography.
This work was generously supported by Bloomberg Philanthropies, The Tiffany & Co. Foundation, and by the National Science and Engineering Research Council (NSERC) Canada Graduate Scholarships and Canada Research Chairs.
For more than 70 years WCS has been underwater studying coral reefs. Today there is a global crisis for coral reefs facing pressures from climate change, pollution, unsustainable tourism, and destructive fishing. From Kenya to Belize, Mozambique to Cuba, WCS is conserving reef biodiversity hotspots and supporting communities who depend on reefs to survive. We currently work across 16 countries to protect coral reefs and ensure that they can continue to provide for the people and species that rely on them.
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