Sad, Half of the Coral Reefs in the World Are Gone

 


Coral reefs are irreplaceable ecosystems for marine life, protecting coastlines, and sustaining the livelihoods of people around the world, so it's only natural that we should all be concerned when they lose. Sadly, half the coral reefs on Earth have disappeared in the last 70 years.

A recent study shows the rate of damage to coral reefs is happening faster than previously thought. Half of Earth's coral reefs have died since 1950.


The study, published in the journal One Earth, notes that fish caught per capita (or more accurately, per "unit of effort") has declined by 60% since 1950. Half of the coral reefs lost are capable of providing ecological services like the 1950s. The loss of coral reefs leads to reduced biodiversity on the world's coral reefs.



"Coral reefs worldwide are facing the effects of climate change, overfishing, habitat destruction, and pollution," the authors wrote in the study.


"With the projected continued degradation of coral reefs and the loss of biodiversity and associated fisheries catches, the well-being and sustainable coastal development of the human communities that depend on coral reef ecosystem services are threatened," they continued.


Like redwood forests, coral reefs are highly heat sensitive ecosystems. Warming waters threaten coral reefs by triggering bleaching events.







Algae provide nutrients to corals through photosynthesis, but if the algae become heat stressed or overexposed to sunlight, they produce toxins instead. The coral then expels the algae, causing the coral to turn white. Bleaching, depending on the severity, can be fatal.


Scientists say it doesn't take a significant temperature rise to cause major problems. An increase in sea temperature of just 0.068 degrees Celsius has proven catastrophic for Australia's Great Barrier Reef. The world's largest coral reef has experienced three bleaching events over the past five years.


The Belize Barrier Reef and the Great Florida Reef, the world's second and third largest coral reef ecosystems, have also been hit by bleaching events in the past five years.


The team behind the study, led by Memorial University of Newfoundland researcher Tyler Eddy, reviewed data from 14,705 surveys of more than 3,500 coral reefs from 87 countries. Among other results, the team found that biodiversity was decreasing, with temperature-resistant fish becoming more dominant, and a decrease in catch per unit of effort.


"Our study shows that the capacity of coral reefs to provide the ecosystem services that millions of people depend on worldwide has decreased by half since the 1950s," they wrote.


"Achieving climate change emissions targets and reducing local impacts can reduce pressure on coral reefs, enabling them and the ecosystem services they provide to survive," the note added.


Scientists have tried several methods to protect coral reefs from the threat of rising sea temperatures. These efforts include cloud brightening, which is thickening clouds with saltwater so that they reflect more heat back into the atmosphere, and using advanced robots to produce carbon dioxide.

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