A lot of dead dolphins continue to wash ashore along the Gulf Coast and now a lot of sea turtles — most of them rare Kemp's ridleys — are washing up dead too, federal officials said Thursday.
Last summer's oil spill may be to blame for the dolphin deaths, but the evidence so far suggests it didn't kill the turtles.
About 15 of the 153 dolphins that have washed ashore since Jan. 1 — including one that showed up two weeks ago — were coated in oil. On eight of those, laboratory tests verified that it came from the BP spill that began a year ago this month, federal officials say.
"A year after the oil spill, we are still seeing dolphins washing ashore with evidence of oil on them — but it may not be the cause of death," said Blair Mase, who coordinates dolphin stranding reports in the southeast for the National Oceanic and Atmospheric Administration.
But the 87 turtles found since mid March appear to be clean of oil, they said. Most of them were endangered Kemp's ridleys.
Of the 87, only 26 were in good enough shape to cut open for examination. Seven had injuries that showed they had been clobbered by boats, and one had been caught on a hook. The rest had sediment in their lungs, indicating they drowned near the bottom, said Barbara Schroeder, the NOAA's sea turtle stranding coordinator.
Those that drowned may have been snagged in bottom-trawling fishermen's gear, she said. Another possibility: some sort of acute toxin, perhaps from an algae bloom. However, there are no signs of any toxic algae bloom currently going on in the gulf.
None of the dead turtles have washed ashore in Florida. Most showed up along the beaches of Mississippi, with a few washing up in Louisiana, too.
The dolphin deaths remain a mystery. Although every year a handful wash ashore dead along the Gulf Coast, this year hundreds of them — many stillborn or newborn — washed up on the beaches of Louisiana, Mississippi, Alabama and Florida's Panhandle, prompting speculation that somehow the oil or chemical dispersants from the Deepwater Horizon disaster killed them.
The young dolphins were in the early stages of development as about 4.9 million barrels of oil gushed into the gulf, and BP was spraying 771,000 gallons of chemical dispersant on the flow.
Mase said the tide of dead young dolphins has tapered off — but dead adult dolphins continue turning up on the beaches and in coastal marshes. Federal officials have sent letters to the biologists collecting the carcasses to caution them that any samples they collect may be part of the criminal case the government is preparing against those held responsible for the disaster.
Despite the passage of nearly 12 months, evidence of the spill's effects remain in the gulf. A recent study of the area around the spill by University of Georgia scientist Samantha Joye found dead corals, crabs and sea stars scattered on the sea floor, along with strings of bacterial slime that created what she called an "invertebrate graveyard."
Reach Craig Pittman at firstname.lastname@example.org.