Thursday, January 30, 2014

Animal-borne video cameras reveal the secret lives of sea turtles

By Dr. Jordan Thomson, Postdoctoral Scientist

Like many aquatic species, sea turtles can be extremely difficult to observe in the wild so important aspects of their behavior remain poorly known. However, using new, high-definition animal-borne video cameras, we have gotten an astonishing look into the lives of these charismatic yet elusive creatures.

Motivated by a lack of understanding of the basic biology of endangered sea turtles, we used custom-built animal-borne video cameras to study the behavior of green and loggerhead turtles in Shark Bay, Western Australia. The researchers conducted over 120 camera deployments, yielding nearly 400 hours of video footage and an unprecedentedly detailed, first-hand view of turtle foraging patterns, diets, habitat use and social interactions – information vital to effective conservation.

The first peer-reviewed article to emerge from this research, published in the Journal of Experimental Marine Biology and Ecology, reveals strong patterns in turtle behavior associated with seasonal water temperatures (which have long been suspected but have proven difficult to observe). During summer, turtles in Shark Bay were highly active, spending most of their time exploring vast seagrass meadows, feeding, interacting with other turtles and keeping themselves clear of barnacles and algae by rubbing on rocks and corals (see article for video clips). When temperatures dipped in winter, however, turtles’ lives slowed to a crawl as they spent most of their time resting on the seabed and rarely came up to the surface to breathe.

While video analysis is ongoing, several other tidbits and video clips (Green Turtle Video 1) have emerged from this research. For example, green turtles in Shark Bay have a very broad diet consisting of seagrasses, algae, jellyfish and other invertebrates (unlike green turtles in the Caribbean Sea, for example, which eat mostly seagrass) (Green turtle eats seagrass, Video 2; Green turtle eats more seagrass; Video 3; Green turtle eats a sponge, Video 4). Loggerhead turtles feed on hard-shelled invertebrates and appear to be quite fond of blue swimmer crabs – but apparently need some practice at catching them (Loggerhead Turtle, Video 5). Limited rocky habitat in Shark Bay appears to be in high demand for resting and rubbing by green turtles, and sometimes things can get testy (Green turtle fight Video 6). And then there’s this clip of a tagged female loggerhead turtle spurning the advances of an interested male (Video 7) (who eventually decides to give up and try another day).

A valuable and evolving research tool, animal-borne video cameras continue to provide unique glimpses into the lives of poorly understood, and often imperiled, marine wildlife.  Check back later for more on our turtle-cams and the other species we are working on!  For now check out this video of a green turtle swimming past a cow tail stingray.

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