Dr. Kara Dodge has achieved the dream of any ocean enthusiast: she studies sea turtles for a living. In the face of a changing ocean, however, some days on the job are more demanding than others.
Dr. Dodge, a scientist at the New England Aquarium’s Anderson Cabot Center for Ocean Life, researches sea turtle behavior and human impacts on their lives. This is important work, especially when you consider that the seven species of sea turtles are either threatened or endangered.
Last November was a particularly challenging time for Dr. Dodge and her colleagues. Two endangered leatherbacks stranded on Cape Cod beaches only a couple of weeks apart. Even after round-the-clock comprehensive care at the Aquarium’s sea turtle hospital, each died. This loss was, unfortunately, not unexpected – leatherback sea turtles are notoriously difficult to rehabilitate and fewer than six leatherbacks have been treated and released by the New England Aquarium and other groups across the United States. Both deaths were tragic, but that of the 420-pound female was particularly so – her end was preventable. Found in Brewster, she died as a result of a severe entanglement injury and from ingesting plastics.
This is why Dr. Dodge’s work studying sea turtle behavior is so critical to the survival of these beloved animals—and to overall ocean health.
“We’re focused on New England waters where we don’t know a lot about sea turtle behavior,” said Dr. Dodge. “Most work has been done on nesting beaches with adult females, so what we’re doing here helps us understand the population as a whole. We’re looking at leatherbacks over different life stages, including males and females. Female sea turtles spend over 90 percent of their lives in the ocean, coming out only to nest, while males are in the ocean 100 percent of their lives. Males are much less accessible to researchers, and this is why we know so little about them. By conducting our research in their feeding habitats, we collect critical data on those mysterious males, as well as females and subs.”
So how does a scientist study this elusive animal? While there are several tools available, the newest and most exciting technique is TurtleCam.
A collaborative project between the New England Aquarium and the Woods Hole Oceanographic Institution (WHOI), TurtleCam is a “smart” underwater robot that tracks and films leatherback sea turtles. The TurtleCam system, originally developed at WHOI for tracking sharks, allows researchers to capture video footage and details about an animal’s environment, such as ocean temperature, depth, salinity, and current. The system also includes an animal-borne camera, allowing researchers to see the ocean from a turtle’s perspective. Dr. Dodge and her WHOI collaborator, Amy Kukulya, were particularly struck by the footage of the turtles feeding on sea jellies.
“We filmed leatherback turtles eating hundreds of sea jellies that bear a remarkable resemblance to single-use plastic bags,” said Dr. Dodge. “The turtles feed continuously and aren’t equipped to regurgitate plastics if they make a mistake. And it would be easy to make a mistake. These turtles are visual predators and their feeding areas off Massachusetts are usually murky with poor visibility.”
Like all sea turtles, which have been around for well over 100 million years, leatherbacks are a keystone species—integral to their ocean ecosystem. They have a highly specialized diet, exclusively eating sea jellies. Sea jellies can be voracious predators of fish eggs and larvae, negatively impacting already depleted fish populations. As a top sea jelly predator, leatherbacks can help maintain a balanced food web.
“Sea turtles are some of the few megafauna left in the world and are essential for healthy marine ecosystems,” said Dr. Dodge. “Different species play different ecological roles. Green sea turtles are the grazers of the ocean, eating primarily seagrass. They help maintain healthy seagrass beds by increasing growth, productivity, and nutrient content. Seagrass is a critical and diminishing habitat for many marine ecosystems and serves as a nursery for many fishes. And sea grass helps people by protecting shorelines from erosion.”
Dr. Dodge is also studying the impact of the Aquarium’s sea turtle rehabilitation and release program. Building off of the Aquarium’s decades of sea turtle care, Dr. Dodge is analyzing post-release outcome data for rehabilitated Kemp’s ridley, loggerhead, and green sea turtles going back to 2005, when Aquarium researchers first started tagging released turtles.
“The purpose of our post-release monitoring research is twofold. We look at the post-release survival of our rehabilitated turtles, and we also assess their behavior to see if they’re able to re-integrate into the natural population,” said Dr. Dodge. “Are they behaving the same way their peers are behaving? This is important, since our goal is not just to release these turtles back to the wild, but to increase reproductive output and contribute to species conservation and population recovery. The Aquarium’s rehabilitation efforts are very successful, but the story doesn’t end there. When the turtles are released and crawl down the beach, it is only the beginning of their story.”
The oceans of our planet are connected, and sea turtles migrate across them. By gaining greater insight into the lives of these animals in the Atlantic, Dr. Dodge and her colleagues collect data that has global significance. Conservation research like theirs is a central focus of the New England Aquarium – by supporting these efforts, you allow this essential work to continue.
Banne Image Credit: Sean P. Whelan, WHOI.