Green turtles research tracked habitat use in two NT areas
Green turtles in the Northern Territory are feeding across a broader range of habitats than expected, with new mapping showing use of coral reefs, algal reefs and seagrass meadows in two protected areas.
The green turtles study, completed as part of Natalie Robson’s PhD with Charles Darwin University’s Research Institute for the Environment and Livelihoods, focused on Trepang Bay in Garig Gunak Barlu Marine Park and Field Island in Kakadu National Park.
Green turtles are listed as a vulnerable species in Australia. The project used ground-truthed remote sensing with Sentinel-2 satellite imagery to map subtidal habitats, the first time the method has been used for that purpose in the Northern Territory.
Trepang Bay and Field Island
The mapping found what Robson described as a diverse spread of marine habitat in both areas. “I’d heard rumours that we only had really patchy seagrass out here, and when I got down to it some of the sites had some really beautiful seagrass meadows,” Dr Robson said.
She said the results also challenged assumptions about where green turtles feed. “We found that turtles aren’t necessarily using those big seagrass areas as much as we would think being herbivores, and that they seem to be feeding on the coral reef sections of those shallow areas. Their diet seems to be quite diverse up here.”
The broader project worked with eight Indigenous ranger groups across the Northern Territory to study how green turtles move, where they feed and what threats they face, as well as habitat use and genetics.
Data collected through the work has been added to Seamap Australia, and maps and results are also available through the project’s website as a resource for rangers. Robson said one of the project’s main outcomes was helping marine rangers build habitat mapping skills and connect turtle behaviour with scientific data.
The paper, Marine habitat mapping of green turtle (Chelonia mydas) foraging grounds in the Northern Territory, Australia, has been published in Marine & Freshwater Research.
