A new study highlights how healthy mangroves can help some coral reef fish navigate the impacts of climate change.
Co-author Professor Peter Mumby, from the ARC Centre of Excellence at the University of Queensland (Coral CoE at UQ), said warming seas cause corals to bleach and reefs to lose their structural complexity—in the process also losing the hiding places that support thousands of fish.
“When a young fish arrives at a degraded reef it has nowhere to hide and is easily targeted by predators,” he said.
“Of course, predators experience the same problem when they’re young. The entire food web becomes unproductive and few fish survive.”
Despite the alarming trend, the team found mangroves provided a partial solution.
“We know some reef fish can use mangroves as an alternative nursery habitat to the reef,” Prof Mumby said.
“Mangroves provide a calm, safe environment with plenty of food and allow fish to grow larger before heading out to the reef as adults.”
The study compared and validated model predictions with field data from Belize.
Lead author Dr Alice Rogers, from the Victoria University of Wellington, said the results should inform reef fisheries management strategies protecting areas now and in the future.
“Mangrove nurseries essentially allow some fish to sidestep the challenges of early life on a degraded reef,” she said.
“Mangrove restoration can be important, but in places where that’s impossible future research might examine adapting structures to offer mangrove-like nursery functions.”
“This would be in environments that either do not support natural mangrove forests, or have too large a tidal range to provide stable nursery functions in coastal fringes.”
The study says while the results offer a glimmer of hope, this does not undermine the importance of healthy coral reef habitats—nor the impacts of their degradation and loss.
Prof Mumby said the protection and restoration of mangrove habitats should remain a priority.
“While we need to take every effort to prevent reef degradation, our study reveals that healthy mangrove forests can help buffer the effects of habitat loss on reef fisheries.”
“It’s critical that they remain a priority as part of the battle to mitigate climate change impacts on coral reefs.”
“Ultimately, we need to protect intact combinations of both mangroves and coral reefs,” Prof Mumby said.
Rogers A, Mumby P (2019). PLOS Biology. ‘Mangroves reduce the vulnerability of coral reef fisheries to habitat degradation’. DOI: 10.1371/journal.pbio.3000510
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Prof Peter Mumby
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Dr Alice Rogers
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