Turtle footage

In several of the video clips, a loggerhead sea turtle, shell studded with barnacles and matted with an undulating crop of green algae, is flanked by an entourage of fish, apparently eating the bounty of food growing on the turtle’s shell or perhaps using the large turtles for cover (adult loggerhead sea turtles are typically about three feet long).

In another clip, a turtle, evidently in response to the shadowy presence of a shark, flips over so its shell is facing the threat and swims away.

These and other natural loggerhead sea turtle behaviors were captured on video by a remotely operated vehicle, or ROV, deployed off the coast of New Jersey, Delaware, and Maryland, by a group of researchers from the Coonamessett Farm Foundation and the Woods Hole Laboratory of the Northeast Fisheries Science Center, both based in Massachusetts. They recently published their findings in the Journal of Experimental Marine Biology and Ecology – and, as the scientists note in their paper, the “study represents the first example of an ROV for tracking sea turtles.”

The scientists spotted the turtles from a boat, focusing on areas where loggerhead sea turtles have been active in the past; when they found one, they launched their ROV, tethered to the boat, and followed the turtle wherever it went. Over their 10 research trips (during which they recorded footage of 70 turtles), the researchers found that they could maneuver the ROV to within about three to five yards of the turtle without disturbing it.

From that vantage point, the scientists were able to observe a number of apparently natural behaviors which would have been difficult to capture by other means, such as human divers, cameras attached to turtle shells, and tracking tags implanted into turtles, all of which have been used to study sea turtles in the past. “[T]he ROV add[s] a new technique that complements existing technologies while overcoming several of the limitations,” the researchers write.

ROVs appear to be a new and useful tool for scientists attempting to understand how loggerhead sea turtles behave in their natural environment, and how they interact with each other and other animals.

Loggerhead sea turtles are typically about three feet long and weigh about 250 pounds.

(Image by Richard Ling via Flickr/Creative Commons license)

Under the waves

Last Saturday morning at 9 a.m., I plunged into Lake Pend Oreille with 668 other people and swam 1.76 miles, about half of it under the shadow of the long bridge that carries U.S. Highway 95 into Sandpoint, Idaho, for the 20th anniversary of the Long Bridge Swim.

Waves chopped at my face with every attempted breath – the wind was up – but I finished the swim in 72 minutes (the overall female winner, a woman in my age-group, swam the distance in just under 44 minutes). The sun-warmed water was the perfect temperature, and so was the post-race ice cream.

When I got home, I did some research on the lake. It’s one of the biggest lakes in Idaho, and the fifth deepest lake in the U.S., with a maximum depth of about 1,150 feet.

And the U.S. Navy operates a submarine-testing station there.

Evidently the combination of the depth of the lake and its relatively quiet location make it the optimum location for research on the acoustics of operating submarines. According to the official website of the Acoustic Research Detachment, “Lake Pend Oreille provides a deep (1150 ft), quiet body of water where a free-field ocean-like environment is available without the attendant problems and costs of open ocean operations.”

Recent research projects conducted at the site include the field-testing of a novel navigation system for autonomous underwater vehicles – basically underwater drones that are programmed to operate on their own once they’ve been launched – and the development of a new way to produce underwater sound waves for use in experiments and surveys that’s more environmentally friendly than other methods.

I didn’t see any model submarines or autonomous underwater vehicles during my swim (not surprising, since the Navy facility is located 26 miles south of Sandpoint in Bayview, Idaho), but I did see a lot of determined people, fighting the waves toward the finish line.

A swimmer's view of the lovely scenery. No submarines in sight.

(Image by Emily Benson)