Coral reefs aren’t just threatened by pollution, ocean acidification and over-heated ocean temperatures. In some places they are being undermined by erosion of the seafloor, U.S. Geological Survey scientists said in a new study that looked at reefs in Florida, the Caribbean and Hawaii.
In the five study sites, the reefs can’t keep pace with sea level rise. As a result, coastal communities protected by the reefs are facing increased risks from storms, waves and erosion.
The degradation of reefs and the subsiding seafloor go hand-in-hand, as sand and other sea floor materials have eroded over the past few decades. In the waters around Maui, the sea floor losses amounted to 81 million cubic meters of sand, rock and other material – about what it would take to fill up the Empire State Building 81 times, the researchers calculated. Continue reading “Sea level rise overwhelming some coral reefs”→
Scientists are currently mapping the biological damage caused by global warming
At the end of eastern Australia’s long, hot summer, ocean scientists are once again seeing devastating coral die-backs in the northern reaches of the Great Barrier Reef. Over the next few weeks, they’ll venture underwater to study how the coral communities responded to a second straight year of overheated water.
When temperatures pass a threshold, the coral expels its symbiotic algal partner, leaving underwater wastelands of white-washed reefs. The scientists will also use survey flights above the reef, and even satellite imaging as they mobilize to document one of global warming’s most devastating impacts. There has been a prolonged global mass bleaching under way for the past year, and climate researchers say nearly all the world’s corals will be at risk by mid-century under projected global temperature increases. Continue reading “Mass coral bleaching likely along northern Great Barrier Reef”→
Study says 90 percent of all predatory fish species have been lost from Caribbean coral reefs
Not all Caribbean reefs are created equal, say researchers with the University of North Carolina at Chapel Hill, who recently identified reef areas they are calling “supersites”that could help restore populations of predatory fish needed maintain an ecological balance.
That’s the good news. The bad news is their study also shows that up to 90 percent of predatory fish are gone from Caribbean coral reefs. The research suggests that these supersites should be prioritized for protection and could serve as regional models showcasing the value of biodiversity for tourism and other uses. Continue reading “Can ‘supersites’ anchor coral reef protection efforts?”→
Uptick in tropical cyclones intensifies impacts, hampers recovery
Along with the widely reported bleaching threat from over-heated oceans, coral reefs in many parts of the world also may have to cope with intensifying tropical storms, which could make it even more difficult for them to survive the Anthropocene.
Northern section hammered by warm ocean temperatures
Australian researchers this week released results of their latest Great Barrier Reef surveys, concluding that huge swaths of coral died in the past year under the onslaught of an ocean heatwave that led to widespread coral bleaching.
A new survey of the Great Barrier Reef shows that an ocean heat wave that peaked last March killed up to 95 percent of corals in some parts of the northern reef. And in the aftermath of the worst coral-bleaching event on record, predatory snails are now taking on toll on the remaining corals.
According to the ARC Centre of Excellence for Coral Reef Studies, researchers recently returned to 83 reefs they surveyed at the height of the bleaching event.
Study identifies bleaching and mortality thresholds for imperiled coral reefs
The steady rise in ocean temperatures projected for the next few decades will put more and more corals at risk of bleaching, as the warm water simply overwhelms their thermal tolerance mechanisms.
Recent research along the Great Barrier Reef shows that corals have been able to survive past bleaching events because they were acclimated to warmer temperatures by being exposed to a pattern of gradually warming waters in the lead up to each episode. But global warming is likely to change that, the scientists said.
Before long, temperature increases of as little as 0.5 degrees Celsius may push many corals over the edge as the warm water causes them to expel the algae-like dinoflagellates that help keep them alive and give them their color.
Lead author Dr. Tracy Ainsworth from Coral CoE said bleaching is like a marathon for corals.