Turtles strand with skin diseases
SCUD. When that term comes up, the veterinarian and the turtle hospital manager quit talking and look at each other. They're not researchers; they're not comfortable speculating about what's wrong with the loggerheads.
"The good news is that, for the most part, they are responding to therapy. That's our job, put them back in the water," South Carolina Aquarium veterinarian Shane Boylan says of the loggerheads.
SCUD is septicemic cutaneous ulcerative disease, essentially skin rot. It can be deadly when it shows up in turtles. It's treated with antibiotics.
So far this year, 15 live stranding sea turtles have been admitted to the aquarium -- putting 2011 on a record pace for strandings. Eight of them had skin ulcers, lesions or had lost keratin, the soft tissue on flippers and necks. In 10 years of operation, the hospital never has admitted more than one or two turtles with skin problems, out of an average 20 admissions per year.
Boylan and Kelly Thorvalson, the aquarium's sea turtle rescue program manager, know they don't have a statistically significant sampling. Nobody has done the exhaustive testing and sampling it would take to determine a forensic diagnosis, much less a cause. But the coincidence is too striking.
Asked if it's alarming, Thorvalson stops a minute to think.
"I'm intrigued by it and would love to know what it is. It's certainly raising a lot of questions in my mind," she says.
"It's a syndrome," Boylan says. "It's like a cough. It could be (caused by) any number of things."
The turtles treated at the aquarium appear to be part of a mall spike, or "pulse" in strandings along the Southeast coast of sea turtles with skin problems. They're also being reported in Florida and possibly Georgia, said veterinarian Brian Stacy, with the National Marine Fisheries Service, who coordinates marine turtle health research for the region. Stacy has not been able to confirm some of the reports yet, he says.
It isn't a first.
"We have had both sporadic strandings and pulses of strandings with skin problems," Stacy says. But like a lot of things about sea turtles, "we don't know a lot about it."
Loggerheads and other sea turtles remain among the most mysterious of sea creatures. Nobody really knows how many are out there. Thousands of nests each year each hatch eggs by the hundreds.
The creatures spend nearly all their life at sea. But few hatchlings survive to adults and adults face natural and man-made threats. There are seven species of sea turtles found across the world, and all of them are considered endangered or threatened.
The loggerhead, the 300-pound mammoth that is one of the beloved creatures of the Lowcountry coast, lays a few thousand nests here each year. Green sea turtle are found here, occasionally the huge leatherback and the Kemp's ridley, the rarest species.
The largest threats to the turtles are man-made -- boat strikes, fishing line entanglements and pollution that can cause or worsen health problems. Skin diseases are nothing new, but researchers saw one spike in the 1980s and 1990s. Green turtles worldwide, particularly off Florida and Hawaii, showed up with bulbous tumors on the skin and face that dehabilitated and killed them.
The condition was thought to be a type of herpes until researchers in Hawaii a few years ago linked it to nutrients, pollution found in the residue of farm fertilizers and sewage plant releases. Nutrients are fertilizer chemicals; they deplete oxygen in the water that organisms need to survive.
Nutrient releases, particularly in rain runoff, also are problem in the Lowcountry, where they are suspected to cause or contribute to health problems with other sea creatures.
Along a coastline with a booming population, nutrients are a constant factor in marine research. Stacy will be looking for evidence of them among other possible causes as he studies samples and test results from the turtles at the aquarium and other recent strandings.
"Absolutely. These turtles inhabit inshore waters where human impacts are the greatest," he says.
The open, oozing flesh of a few of the sea turtles brought in to the aquarium "is a gruesome-looking thing," says David Owens, College of Charleston biology professor who specializes in sea turtles and advises the hospital. It's most likely a combination of stresses are responsible for the apparent, unusual spike in turtles stranded with skin problems, he says.
In part, it might be the frigid waters last winter that also are being blamed for a precipitous drop in the shrimp crop this spring.
A cold stunning could have weakened the animals and made them more vulnerable to skin disease. Stunning is a condition similar to hypothermia that occurs when sea temperatures drop more quickly than the cold-blooded reptiles can tolerate.
It can kill a sea turtle, or weaken it to the point where something else does.
Cold stunning last winter led to the record numbers of turtles being admitted to the hospital, the second time that's happened in three years.
"It could be some of these animals survived a cold stunning," Owens says. "One thing about turtles, and reptiles in general, they can handle an amount of abuse that a mammal couldn't handle."