Dolphins die off: the Canary in our Oceans?


They are agile, playful mammals that are known to play with swimmers, rescue humans, and leap out of the water just to check things out. They follow ships, big and small, maybe to conserve energy or maybe because they are curious about the humans they share the planet with. And we have been just as curious about them; we love to watch them in the wild, in aquariums and on the big screen.

Dolphins live in social groups as small as five or as large as five hundred. And they have been around some thirty million years, ten million more than us, the upstart humans.

Image: Courtesy of Virginia Aquarium & Marine Science Center and Smithsonian.

In the past dolphins were slaughtered by the million for their skin and meat. Now they are still dying even though they are a protected species. They drown in drift nets, they are captured to populate aquariums, but they are also dying because their home, our world’s oceans, are too toxic.

Three different mass and record-sized die-offs of dolphins started around Florida this year. The most threatened species is the bottlenose dolphin. Greg Bossart, as quoted in the Tampa Bay Times, said dolphins are “sentinels for ocean and human health” as the canaries in a coal mine.

 

Dolphins began dying off in southern U.S. waters in 2010, complicated by the huge Gulf oil spill and a bacterial infection. By the end of November this year, 1,000 of these giant mammals have died off Florida’s Gulf coast. Formerly these mammals were found to have large amounts of mercury in their systems and skin infections. A massive algae bloom (an algae bloom is also causing havoc in Lake Erie) is killing hundreds of manatees and pelicans along with the dolphins there. The fish are disappearing and the dead dolphins have found to be emaciated with only shrimp in their bellies.

Bossart feels that we have used the ocean as a toilet and it is now catching up with us. It is well known that ocean water is now too acidic and the waters are warming. Alanna Mitchell, writer for the magazine Canadian Wildlife, notes that carbon dioxide catches the headlines but methane trapped in the ocean may be a greater threat. In 2011 Russians found a kilometer long string of methane plumes. Methane is a carbon based gas, and every molecule traps about 70% more heat than a molecule of carbon dioxide. In a few decades methane burps could erupt from the ocean.

The race is on to save our seas and the creatures who live there.

 

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