NEWS - ENGENEERED TURTLES TAKE THE HIT FOR SCIENCE IN BLOOMIGDALE

Engineered turtles take the hit for science in Bloomingdale

Posted: August 6, 2011 - 12:20am

TOP: Graduate student Chad Spurluck, left, and undergraduate Justin Lanier prepare the artificial turtle for its swim in the Ogeechee River. CENTER: David Scott, right, associate professor of engineering at Georgia Tech Savannah, watches as his boat runs over an artificial turtle. Piloting the boat is Mark Dodd of the Georgia Department of Natural Resources. RIGHT: The damage to the artificial turtle is measured after being hit by a boat.

It’s no secret that lots of sea turtles are injured and killed every year from getting run over by boats.
In Georgia, almost a quarter of sea turtle fatalities are attributed to crushing blows from hulls and slicing wounds from propellers.
But scientists are only just beginning to document exactly how boats and motors, and which types, do their damage and to figure out how best to prevent it. Researchers from the Georgia Department of Natural Resources and Georgia Tech are in the second phase of experiments on full-scale models of loggerhead sea turtles, the most common sea turtle in state waters.
On the Ogeechee River near Bloomingdale on Monday, they continued their field work.
Piloting the DNR’s law enforcement boat at planing speed of about 26 mph, Mark Dodd aimed straight for a fake turtle tethered just below the water’s surface. A muffled thump signaled a hit, then the engineered loggerhead broke into pieces. A lethal strike.
“This is turtle 2.0,” said Tech’s David Scott as he fingered the resin-covered foam shell.
Scott, associate professor of civil and environmental engineering, and his colleague Paul Work, also an associate professor, improved on their previous turtle model. They added, among other changes, silica microspheres to the shell’s outer layer so it became harder on the outside.
“It acts like a sandwich; that’s what you see in a real shell,” Scott said. “Nature is pretty smart that way.”
The first round of testing in 2008 produced a scientific paper published in June in the Journal of Experimental Marine Biology and Ecology. Not surprisingly, the researchers found that higher speeds produced greater injuries. Propeller guards didn’t seem to protect against harm except at idle, but jet propulsion systems, like those seen on Jet Skis, did seem safer for animals.
“We’re looking at the boat strike as an engineering problem, not a biological problem,” Scott said.
In Monday’s testing, the jet boat, a kind of overgrown Jet Ski bought for the grant-funded research, first produced significant injuries in the turtle models. But late afternoon testing with a green turtle carcass — the animal died after being cold-stunned last winter and has been in the deep freeze waiting for this opportunity ever since — failed to produce any fractures.
That’s science, said Dodd, who coordinates the Georgia Sea Turtle Program.
“We have inconclusive results,” he said. “Further testing will be necessary.”
It may require more tweaking of the engineered shell.
“The idea is to get a shell that behaves like a real turtle,” Dodd said. “It’s not a simple thing. It’s not as simple as you would think.”