James Cook University TropWATER scientists are unlocking vital clues about the diets of globally endangered dugongs by studying the DNA found in an unusual source – dugong poo.
Seagrass is the main food source for dugongs, but as these meadows come under increasing threat, this research could be key to uncovering what other foods these sea cows consume when seagrass is scarce.
The JCU research team will collect around 20 dugong poo samples for DNA analysis across 350 square kilometres of seagrass meadows in the Townsville region, which is home to a thriving dugong population.
JCU TropWATER's Dr Samantha Tol said it's unclear if dugongs seek out or avoid certain animals – like sea cucumbers, sea squirts and sponges – within seagrass meadows.
"Dugong poo comes in different shapes, sizes, and consistencies – so we know they are eating more than just seagrass, but we don't know what they are eating," she said.
"By analysing the DNA of marine species found in dugong poo, we're solving a puzzle of their diet."
It's estimated that dugongs eat around 40 kilograms of seagrass each day, but Dr Tol said this research will determine if other marine animals are important to their diet.
"If a seagrass meadow dies back, it may impact the small animals living there, like sea cucumbers and sea squirts," she said.
"Looking at what dugongs eat in seagrass meadows, like those in Townsville, could improve our understanding of what makes seagrass habitat most beneficial to this iconic megafauna."
Analysing the DNA inside poo is a novel and largely unexplored approach. The findings will draw on TropWATER's 18 year seagrass monitoring program, with both projects funded by the Port of Townsville.
TropWATER seagrass expert Skye McKenna said their team surveys over 350 square kilometres of seagrass meadows.
"The Townsville region has a high diversity of seagrass, with up to 10 seagrass species," she said.
"During these surveys, we monitor seagrass health, identify seagrass species, and record other marine life like sponges, coral, and algae. This gives us an idea of what bottom dwelling species live in these habitats.
"We'll compare the species found in dugong poo with those recorded in our surveys to understand if dugongs prefer or avoid certain marine species."
Dr Tol said the research uses non-intrusive methods to study the dugong diet – without disturbing these shy, endangered marine mammals.
"This is a new way of exploring their diet and seagrass habitats," Dr Tol said.
"While our sample size is small, with more support, we could expand this research and gain a clearer picture of dugong diets across a wider area and answer key questions about what makes seagrass habitat most beneficial to dugongs."
This research will also help understand how dugongs adapt to changes in seagrass availability, guiding efforts to protect both the dugongs and their seagrass habitats.
This research is funded by the Port of Townsville's 2024 Community Fund.
JCU TropWATER conducts extensive research on seagrass and dugongs across Northern Australia, using innovative technologies like drones, environmental DNA and dugong tagging. The team works with Indigenous communities, industries, and governments to develop science-based solutions for managing these vital ecosystems and marine species.
