Marine Ecologists Warn Of Coral Extinction By End Of Century – Verve Times

LSU marine ecologist Dan Holstein scientifically dives in the Caribbean. Credit: Viktor Brandtneris

Vibrant coral reefs teeming with marine life are shrinking in the Caribbean as global temperatures rise. Coral reefs are habitats that support the seafood industry, are barriers for coastal communities against storms, floods and sea level rise, and are tourist attractions. Their net economic worth worldwide is estimated at tens of billions of dollars. However, if air and ocean temperatures continue to rise at the current rate, coral reefs are at risk of disappearing within the next 80 years, or by the end of this century.

“Entire reefs I used to dive and snorkel on have disappeared. There are species that you no longer see on the reef. Change is happening,” said Dan Holstein, assistant professor in the Department of Oceanography and Coastal Sciences at LSU.

He and his collaborators have developed a new open-source computer model that is the first to predict how warming seas will destabilize coral populations throughout the western Atlantic, including the Florida Keys, Bahamas and Caribbean. Using existing projections of ocean warming, the model calculates how coral populations will sustain and thrive, or begin to perish, as ocean temperatures rise.

“This model predicts that warming oceans will reduce the ability of migrating coral larvae to replenish bleached and dead reefs. The model doesn’t seal the fate of coral reefs, but it’s a big wake-up call,” said Holstein, whose work is published in a new journal article. Coral reefs.

As the ocean warms, it can destabilize marine ecosystems, causing imbalances similar to the temperature and weather extremes experienced on land.

“Heat stress isn’t the only problem corals face, but it’s considered the most important,” Holstein said. “And the amount of carbon we release into the atmosphere is something we can decide. We can actually do something about it.

Corals are marine animals that depend on a healthy symbiotic relationship with microscopic seaweed to survive. Algae live inside coral tissue and produce sugars for the coral through photosynthesis. However, when the ocean gets too warm, this symbiotic relationship breaks down, leading to a phenomenon called coral bleaching, and eventually the coral may starve.

Coral reefs could be threatened with extinction within the next 80 years, or by the end of this century, if atmospheric and ocean temperatures continue to rise at the current rate, according to new research from the assistant professor of the Department of LSU Oceanography and Coastal Science, Dan Holstein. Credit: Dan Holstein, LSU

The Holstein model examines the resilience of connected coral populations to expected temperature changes in the Caribbean.

“Coral reef connectivity via sexual reproduction and planktonic larvae remains a critical process to follow during climate change,” said co-author Claire Paris, a professor at the Rosenstiel School at the University of Miami.

The new model uses connectivity information derived from the open source connectivity modeling system developed by Paris.

Although the model suggests a dire outcome for coral reefs and especially for the widespread but endangered boulder star coral used in the model given the current trajectory, Holstein does not believe that coral reef extinction is inevitable.

Consumers and policy makers can still change the amount of carbon emitted into the atmosphere. The countries most at stake and those that are the biggest carbon emitters must work together to reverse the trend.

“Managing coral reefs and mitigating this dire future requires cooperation across boundaries and spatial scales to manage critical habitat. This is one of the obvious conclusions. If we don’t, all of our efforts risk being ineffective,” Holstein said.

The study, titled “Predicting coral metapopulation decline in a changing thermal environment,” was published online April 12 in the journal Coral reefs. The paper’s authors include Holstein, Tyler Smith, associate research professor of marine science at the University of the Virgin Islands, assistant scientist Ruben van Hooidonk at NOAA’s Atlantic Oceanographic and Meteorological Laboratory, and Paris.


Protecting coral reef connectivity is crucial to conservation efforts


More information:

Daniel M. Holstein et al, Predicting Coral Metapopulation Decline in a Changing Thermal Environment, Coral reefs (2022). DOI: 10.1007/s00338-022-02252-9

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