Climate change-related marine heatwaves are known to be the cause of mass mortality in some of the world’s most famous coral reef systems.
But scientists have found that an extreme weather event that caused the sea temperature to drop quickly by up to 10 degrees was the main cause of the coral die-off.
The extent of the coral reef collapse in Costa Rica’s eastern tropical Pacific in 2009 was abnormally high due to widespread increases in harmful algal blooms.
Some sites’ coral cover went down by 20% to 100% because of these two things, and levels of recovery have been very different in the years since.
According to a recent study that was published in the journal PeerJ, the results show that upwellings, which cause sea temperatures to suddenly drop, are an important factor to take into account when trying to manage reef systems.
The study was done by an international group of scientists led by the University of Plymouth. They worked with groups like Raising Coral and ACG that work to protect Costa Rica’s coral reefs.
Using data from 25 years of reef surveys and measurements of sea surface temperature, they looked at how the coral cover and composition of six reefs changed in response to temperature highs and lows.
By doing this, they were able to figure out what it meant for successful conservation and restoration strategies, get a full picture of the health of corals in the area, and figure out how fast coral populations were going down.
The study found that the ecosystem in the area had reached a tipping point because there had been no overall coral recovery in the ten years since the first event.
They therefore suggest an approach to coral reef declines that is locally specific but also globally scaleable, and that is based on resilience-based management and restoration, as well as coral health dynamics.
Reefs may be able to recover and continue providing ecological and societal ecosystem services with the help of such measures and careful management, despite the growing threats posed by climatic change.
Professor of conservation biology at the University of Plymouth, Dr. Robert Puschendorf, said: “Coral reef destruction is closely related to marine heatwaves and global warming. The remaining reefs in our ocean, however, might be preserved with the aid of regional and customized conservation strategies. The extent and intensity of the harmful algal blooms can be reduced if we involve local communities, improve governance regarding how we manage waste water, and take other actions. Even though the problems of global warming and extreme weather are undoubtedly much more serious, this study shows what people can do right now. “
