Climate change has led to widespread, long-term declines in coral reefs around the globe. In order to recover, coral populations under stress depend on new larvae from outside populations to disperse and settle there. However, a lack of connectivity between reefs can hinder larval movement between populations, potentially slowing or even preventing coral reef recovery. Connectivity is a key component to reversing the stress of warmer temperatures.
Figueiredo, J., Thomas, C.J., Deleersnijder, E., Lambrechts, J., Baird, A.H., Connolly, S.R. and Hanert, E. 2021. Global warming decreases connectivity among coral populations. Nature Climate Change 12: 83-87.
New research highlights the effect of warming on reef connectivity by combining models of larval survival and competency for the stony coral Acropora millepora with a high-resolution model of ocean circulation on the southern Great Barrier Reef. Under 2˚C of warming, estimates of larval dispersal shift in several ways: there is a decrease in the distance larval disperse, a decrease in connectivity into each reef, and a large increase in the number of larvae that stay in their home reef and produce offspring that also stay. Although these projected changes can vary from reef to reef, recovery times are dependent everywhere on having well-connected reefs.
One way to mitigate this loss of connectivity is through marine protected areas (MPAs), which create stable protected regions that can be linked together. There are numerous ways to design MPAs in order to improve connectivity and make them more effective. As more marine areas – including coral populations – come under protection, there is more potential for connectivity between these populations to be maintained or restored. In addition, an increasing number of policy measures have included legislation that protects threatened marine areas such as coral reefs.
Numerous conservation efforts are currently underway to protect marine connectivity. The CCSG Marine Connectivity Working Group has released 15 case studies representing a diversity of design and management strategies highlighted in the publication Marine Connectivity Conservation ‘Rules of Thumb’ for MPA and MPA Network Design. Covering 31 countries and also areas beyond national jurisdiction (ABNJ), they are now part of the Globescapes map that features short summaries and direct links to each case with thorough evaluations of the diversity of contexts and challenges, approaches, and results, as well as photographs, maps, and diagrams.
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