Climate change-induced marine heat waves are known to be responsible for mass deaths on some of the planet’s most iconic coral reef systems.
However, scientists have found that an extreme weather event that resulted in rapid drops in sea temperatures to 10 degrees was the primary cause of catastrophic coral deaths.
Combined with a widespread increase in harmful algal blooms, the rate of reef collapse in Costa Rica’s eastern tropical Pacific Ocean was abnormally high in 2009.
The two factors resulted in a decrease in coral cover in some locations by between 20% and 100%, with levels of recovery also varying significantly in subsequent years.
In a new study, published in the journal pearJresearchers say their findings show that the effects of upwellings — which cause sea temperatures to drop suddenly — are an important factor to consider when managing reef systems.
The research was conducted by an international team of scientists led by the University of Plymouth, in collaboration with partners including: Raising coral and ACG that promote the conservation of coral reefs in Costa Rica.
They used 25 years of reef research and sea surface temperature data to document changes in coral cover and the composition of six marginal reefs in relation to thermal highs and lows.
By doing so, they were able to provide a comprehensive picture of the local health status of corals and quantify the magnitude of coral population decline, while also determining the implications for effective conservation and restoration strategies.
In the study, they say the lack of overall coral recovery in the decade since the first event indicates that the region’s ecosystem had reached a tipping point.
As a result, they propose a locally tailored – yet globally scalable – approach to coral reef decline that is based on resilience-based management and restoration, as well as coral health dynamics.
Such measures, with careful management, could enable reefs to recover and continue to support ecological and societal ecosystem services, despite the increasing threats of climate change.
dr. Robert Puschendorf, lecturer in Conservation Biology at the University of Plymouth, said: “The decline of coral reefs is closely linked to global warming and sea heat waves. However, local and tailor-made conservation strategies can help preserve the remaining reefs.” … in our ocean. If we involve local communities and improve governance on how we deal with wastewater and other factors, it can reduce the size and intensity of harmful algal blooms. The problems of global warming and extreme climate events are obvious. much larger, but this study shows what actions people can take in the meantime.”
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Caroline Palmer et al, Cold water and harmful algal blooms associated with coral reef collapse in the Eastern Tropical Pacific, pearJ (2022). DOI: 10.7717/peerj.14081
Quote: Study links cold water shock to catastrophic coral collapse in eastern Pacific (2022, Sept. 29) retrieved Sept. 29, 2022 from https://phys.org/news/2022-09-links-cold-catastrophic-coral-collapse. html
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