Up at the homestead, Dr. Jordy Thomson (GTCP 2015/16 Program Assistant), gave a presentation to Gnarloo’s staff and the GTCP Scientific Interns on some of his previous work with green and loggerhead sea turtles (Chelonia mydas, Caretta caretta) and humpback whales (Megaptera novaeangliae). Jordy has been working with sea turtles in Western Australia for the last 10 years, and prior to that he has worked with humpback whales in Alaska – we were excited to see some of his work!
The presentation started off with video footage from Jordy’s days as a Field Technician with the University of Alaska, during which he helped a PhD student deploy time-depth recorders on humpback whales (which looked like massive suction cups!) to investigate their diving and foraging patterns on their summer feeding grounds.
After working with whales, Jordy got himself into sea turtle research down in Shark Bay, WA, where he had the opportunity to attach GoPro cameras onto the carapace of green and loggerhead turtles to record their feeding behaviours, movements and social interactions. Green turtles in Shark Bay have a surprisingly diverse diet including seagrasses, algae and soft-bodied invertebrates, and seem to be a lot more social than we originally thought, interacting extensively with other turtles around coral heads and rock ledges. They use these areas as resting habitat, to take refuge from predators (e.g. large sharks), and to rub barnacles and other unwanted passengers off their bodies. Jordy also showed some footage of loggerhead turtles trying awkwardly (and unsuccessfully) to catch blue crabs while foraging over sand flats.
The turtle-borne cameras also captured the state of Shark Bay’s seagrass beds just after they were impacted by a heat wave, which increased water temperatures by 2-4ºC for ten weeks during the summer of 2011. The footage showed major seagrass dieback (where large areas of seagrass die and become overgrown with algae) as a result of the event. Many animals rely on these habitats for food and shelter, and in the four years since the heat wave little to no recovery of the primary temperate seagrass in Shark Bay has occurred. This is a concern because these kinds of extreme events may become more frequent under climate change, so coastal ecosystems where foundation species (species like certain corals, kelps and seagrasses, which create habitat for other species) are sensitive to extreme temperatures are likely to experience some major changes in the next few decades.
Overall, it was a very engaging and informative talk which we all enjoyed greatly.
Thanks Jordy, and we can’t wait until it’s our turn to present GTCP research in the near future!
Mel Do, Community Engagement Intern