Saturday, May 17, 2014

Sea turtles and domoic acid

Wildlife biologist Heather Harris presented her work on how leatherback sea turtles are affected by domoic acid, the toxin produced by harmful algal blooms. That's kind of surprising, because the jellyfish they eat aren't thought of as being affected by domoic acid. But it turns out, they are.

She doesn't get to see many, but occasionally one washes up on the beach.She was here in 2012 when a tagged female died and turned up on our beach. As a veterinarian, she has been working on turtle health. She necropsied this one and found that she died of a bacterial infection caused by intestinal perforations. She had high concentrations of domoic acid in her urine and gastrointestinal contents. The question to Heather was: where did the DA come from?

Leatherback sea turtles migrate along our Central Coast. While they are here in the fall, they are eating a lot of jellyfish, to bulk up for their long migration across the Pacific Ocean. They weigh more than 1,000 lbs., so they eat huge amounts of jellyfish.

Shellfish, filter feeders such as mussels, bioaccumulate DA, but leatherback sea turtles don't eat them. She needed to look for DA in jellyfish. In 2010, that's what she did. She found DA in nearly every jelly of four different species that she sampled.

"Jellies may add a new dimension to offshore harmful algal blooms," she said.

"Human impacts affect the ocean. We are all connected. Anything we do to alter the environment affects us all."

More of Heather's work is posted on Oikonos.

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