Marine protected areas help coral reefs against global warming

Coral reef fish communities are helped by marine protected areas in the fight against global warming

by Lorenzo Ciotti
Marine protected areas help coral reefs against global warming
© Donald Miralle / Staff Getty Images News

Global warming, a direct consequence of the unstoppable climate crisis, has devastating effects on biomes and ecosystems. One ecosystem that is under constant and terrible threat is the coral reef. All reef communities are at risk, but the establishment of marine protected areas can help them.

The study Marine protected areas promote stability of reef fish communities under climate warming, published in the Nature communications, provided an interesting retrospective on the topic.

The researchers explain: “Protection from direct human impacts can safeguard marine life, but ocean warming exceeds the boundaries of marine protected areas. Here, we test whether protection offers resilience to marine heat waves from local to network scales We examine 71,269 time series of population abundances for 2,269 coral reef fish species surveyed in 357 protected sites versus 747 open sites worldwide.

We quantify the stability of coral reef fish abundance from populations to metacommunities, considering responses of species and functional diversity, including the thermal affinity of different trophic groups. Overall, protection mitigates the negative effects of marine heat waves on fish abundance, community stability, asynchronous fluctuations and functional richness.

We find that local stability is positively related to distance from centers of high human density only in protected areas. We provide evidence that protected area networks have persistent reef fish communities in warming oceans, maintaining large populations and promoting stability at different levels of biological organization."

Coral Reef
Coral Reef© Ian Waldie / Staff Getty Images News

Coral reefs under siege

Coral reefs form some of the world's most productive ecosystems, providing complex and varied marine habitats that support a wide range of other organisms. Coral reefs just below low tide level have a mutually beneficial relationship with high-tide mangrove forests and seaweed beds in between.

The reefs protect the mangroves and seaweed from strong currents and waves that would damage them or erode the sediments in which they are rooted, while the mangroves and algae protect the coral from large influxes of silt, fresh water and pollutants. This level of variety in the environment benefits many coral reef animals, which, for example, can feed on sea grass and use coral reefs for protection or reproduction.

Unfortunately, these ecosystems are very fragile and are threatened, directly or indirectly, by human activity. Trawling and anchors can damage them significantly.
A conservative prediction is that of some scientists from the Australian University of Queensland, who predict the death of the Great Barrier Reef within 50 years due to the rise in average water temperatures.

One of the problems with coral reefs is the time it takes corals to recover from damage, in fact many of them grow a few centimeters a year. Some researchers have found a way to repair the reefs: in order to recreate themselves, corals must be attached to a solid substrate and must receive a continuous flow of water, so the researchers built small steel frames to which the fragments were attached of live corals. These steel frames, called reef stars, have led to increased coral growth.