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Coral Crisis

Hurricane Waters Calm a Coral Crisis
by Dan O’Connor

The past hurricane season brought heavy rains, high winds and a cause for concern—both on land and below sea level. For many BVI residents, the wet and windy season proved either threatening or costly—or both. But for local marine biologists and dive enthusiasts with a vested interest in the territory’s lush yet increasingly threatened coral reefs, the heavy systems that swept through BVI waters brought a sigh of relief.

Early studies of surrounding reefs indicate that the BVI escaped a threat of widespread coral bleaching, thanks in large part to sea temperatures cooled by passing tropical systems. A recently released report co-authored by BVI marine biologist Shannon Gore shows through satellite and field evidence that the territory dodged predictions suggesting that high water temperatures caused by global warming would devastate the region’s vast coral networks. Instead, the busy hurricane season had a cooling effect on the waters, after numerous systems filed one after another off the cape of western Africa and from the Gulf of Mexico, largely trampling the northern Leeward Islands. And while many of those islands experienced millions of dollars in costly surface damages, much of the underwater habitat survived in large part because of the natural cooling effects that helped to shelter marine life from the harmful effects of global warming, Gore explained.
“Interestingly, it’s basically a way that nature kind of protected itself,” the marine biologist said, adding that hurricanes also help to clear out dead coral, stimulating fresh, productive life.
Predictions before the start of the 2010 hurricane season suggested that the Caribbean region, along with coral reef breeding grounds around the globe, would be susceptible to a rise in water temperatures significant enough to cause more devastation to the underwater habitat than in 2005, when coral bleaching effectively terrorised coral basins globally. From June to October of that year, researchers from 22 different countries found that more than 80 percent of basin-scale coral experienced bleaching, which occurs when the healthy algae (zooxanthellae) dies off as a result of unsustainable living conditions. Here, the Department of Conservation and Fisheries recorded a 60 percent mortality rate due to coral affected by bleaching.
“That was the worst in recorded history,” Gore said, adding that rising water temperatures have taken their largest toll on tropical waters over the past two decades.
Warm, calm waters shocked by heavy sunlight and minimal winds provide the perfect recipe for bleaching, Gore explained. When water temperatures rise as little as one degree Celsius above average maximum temperatures, corals can expel the living algae from their bodies, subsequently expelling the provider of 90 percent of their food. The coral will turn white, and, after only a few days living in this condition, will likely to die.

Coral bleaching is a phenomenon researchers link directly to global warming, but that doesn’t mean the battle to preserve the BVI’s pristine waters is hopeless, Gore explained. Aside from increasing water temperatures, reefs can be even more negatively impacted by the human imprint, she said.
The marine biologist added that many divers and snorkellers who swim without a trained eye have a hard time identifying bleaching patterns and often overlook its cause for concern.
“For the most part, people just think, ‘Wow! That’s pretty,’” she said of the bleached coral. Generally, a lack of concern about the problem persists, she added. Here, policy makers and those charged with enforcing the law need to be equally proactive protecting the reefs, she said. Furthermore, she added, boating and SCUBA enthusiasts visiting the Caribbean should respect the living coral’s fragility as they admire its beauty.

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