Marine protected areas (MPAs) act as important management tools to protect biodiversity in the oceans. When managed as a network, they are key to maintaining connectivity for many populations and have conservation benefits such as protecting larval dispersal and promoting fish abundance.
Climate change is expected to have a big impact on marine communities, particularly in the form of rising ocean temperatures. In theory, MPAs can help mitigate the impacts of climate change by protecting diversity and promoting stability. However, so far there is little direct evidence to show just how well MPAs maintain stability in the face of global warming.
Benedetti-Cecchi, L., Bates, A.E., Strona, G., Bulleri, F., Horta e Costa, B., Edgar, G.J., Hereu, B., Reed, D.C., Stuart-Smith, R.D., Barrett, N.S. and Kushner, D.J. 2024. Marine protected areas promote stability of reef fish communities under climate warming. Nature Communications, 15(1), p.1822.
New research aims to provide this evidence through a meta-analysis of reef fish communities across 50 global Marine Ecoregions. Over 2,000 reef fish species were surveyed during several decades at 357 MPA and 747 open area sites, providing a large dataset for looking at timeseries of population abundances. This information was then used to quantify how well MPAs promote stability across multiple scales as compared to open areas, and how well MPAs might buffer communities from heatwaves and human disturbance.
The results provide evidence that MPAs can in fact mitigate the impacts of climate change and human disturbance, by supporting larger populations, safeguarding species richness, and maintaining stronger asynchronous fluctuations than open areas.
There was a positive relationship between reef fish abundance and marine heatwaves for most fish in MPAs, while the opposite was true for most fish in open areas. Differences that emerged between different tropic levels (ex. grazers vs. carnivores) mean that traits such as thermal tolerance influence the extent to which MPAs can protect species in the face of heatwaves.
While individual MPAs are important for local stability, the connectivity of MPAs is key to supporting network stability of metacommunities. In this case, MPAs did a better job than open areas in supporting fish populations the farther they were from human populations and direct human disturbance. Remoteness and protection were key to promoting community stability, with even the most isolated MPAs still capable of contributing the the larger MPA network by helping to connect populations.
MPAs that are well-enforced and well-designed can be effective in supporting and stabilizing fish communities that are likely to be negatively impacted by rising sea temperatures. There are numerous MPAs around the world that create essential networks linking populations, and even small, isolated MPAs can contribute to connectivity. Given the anticipated impacts of climate change on marine life, these networks will be critical to protecting and conserving biodiversity across the world’s oceans.
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