Janet Lanyon leaps off a red zodiac into the waters of Moreton Bay and swims towards a group of splashing figures in front of her.
Moments before, four fit people in rugby helmets launched into the water off the moving boat in pursuit of a dark shadow as it came up for air.
Between them is half a tonne of grey muscle — a big male dugong (Dugong dugon).
The team monitors the dugong’s breathing in the water. (ABC TV: Dr Ann’s Secret Lives)
The dugong is held up while researchers measure it. (ABC TV: Dr Ann’s Secret Lives)
Wetsuit-clad researchers wrap a tape measure around the bull’s belly, then stretch it the length of his body to give an accurate reading of the animal’s size in the water, while the “catching team” prevents the animal from diving.
“Breath … breath … breath …” the team calls out each time the bull opens his massive nostrils.
Once they have his measurements, the team slides his hefty body onto a sling and transfers him to a larger boat for a full health check.
Dr Lanyon oversees the action, keeping track of what data is being collected and making sure her team and the dugong are safe.
The marine biologist from the University of Queensland knows dugongs very well.
She’s been running the world’s largest dugong health assessment program at Moreton Bay since it started 16 years ago.
Although the pursuit and capture looks dramatic, she says monitoring shows the dugongs calm down quickly.
“They are pretty relaxed animals really,” Dr Lanyon says.
And what we learn from these dugongs is critical for helping conserve the enigmatic marine mammal elsewhere in Australia and other places around the world where numbers are falling.
Quandamooka Country
Moreton Bay is the perfect place to study dugongs.
About 800—1,000 dugongs live in the turquoise waters that lie off the Queensland coast near Meanjin/Brisbane.
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The large mammals spend up to 20 hours a day digging and hoovering up seagrass, consuming roots, rhizomes and leaves.
On average, an adult dugong eats 65kg of grass a day — more when they are reproducing.
They are also picky eaters, preferring to eat a specific species of seagrass.
Their messy feeding leaves trails, like snails in a rock pool, making them relatively easy to find in the 3,500-square-kilometre bay.
And it’s safer than some of the other potential study sites in Australia.
“Up north, you’ve got crocodiles,” Dr Lanyon says.
These dugongs are deeply significant to the Quandamooka people, one of the traditional owner groups of Moreton Bay.
“Caring for the dugongs is the same as caring for our Country,” says Justin Ladbrooke-Parkin, who is the ranger in charge for the Quandamooka Marine Rangers, but speaking from his own experience.
“[Dr Lanyon’s] research provides that scientific knowledge … but also, it aligns with the cultural knowledge of the Quandamooka, which has been passed down through our generations.”
Read more National Science Week stories:Race on deck
Once the dugong is on board the boat, a new race is on.
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To minimise stress to the animal, the researchers extract as much biological information from it as they can within 30 minutes, before it is released.
They collect blood, urine, saliva, mucous-laden tears and faecal samples, as well as swabs of skin bacteria that could be used as a “health biomarker”. If it was a female, it would also have an ultrasound to detect pregnancies.
Data from the samples also reveal aspects of their secret lives.
By measuring stress hormones, the team has found that dugongs recover quickly from their time on board. (ABC TV: Dr Ann’s Secret Lives)
The tears of a dugong are very sticky and provide a wealth of biological information. (ABC TV: Dr Ann’s Secret Lives)
Blood samples are taken from beneath the dugong’s pectoral fin. (ABC TV: Dr Ann’s Secret Lives)
The plastic plate used to collect a faecal sample is covered in foil so the plate does not contaminate the poo and the team can test for microplastic. (ABC TV: Dr Ann’s Secret Lives)
Adult males start to look a bit rough around the edges towards late winter and early spring when there is less good-quality seagrass in the bay.
They also often have marks from fighting each other.
“That time coincides with the mating season so it’s a time when the adult males are just thinking about finding females,” Dr Lanyon says.
Sampling shows their testosterone and stress hormones increase during mating season.
As a result, it’s not uncommon for a few dead males to wash up at this time of year, but Dr Lanyon has been able to use this research to calm public fear of mass mortality events.
Seagrass precious for picky eaters
Moreton Bay’s dugongs are the most studied in the world.
“We’ve now tagged probably 750, or more, different animals in the bay,” Dr Lanyon says.
One of the major findings of the research is that this population rarely strays from the bay. If an occasional animal swims north, they are unlikely to breed with other dugongs.
But their homebody nature, massive appetites and picky eating puts them at risk.
Their growth rate, reproductive rates, how healthy they are, their whole life history is determined by their food.
The underwater meadows they rely on are susceptible to dieback, a disease that is on the rise due primarily to increased extreme weather events.
“We’re concerned because a lot of the species that are good food for dugongs and that dugongs like to feed on are becoming rarer [in Moreton Bay],” Dr Lanyon says.
This ties in with traditional knowledge.
“We’ve always known that there’s these special areas for the dugongs and their feeding grounds,” Mr Ladbrooke-Parkin says.
“And this research obviously just supports that these areas should be protected.”
Life near a big city
Swimming near Australia’s third-largest city comes with specific risks for dugongs.
Human medicine is flushed into the bay, and urban grime washes down the drains.
“We looked at a panel of 18 different common antibiotics and we found that every dugong that we looked at was resistant to quite a few of the antibiotics,” Dr Lanyon says.
Her team has also found heavy metals, pesticides, microplastics and herbicides in the tissue and circulating blood of Moreton Bay dugongs.
Extreme weather can compound these urban risks.
“We know that with every flood event or cyclone there’s direct damage to seagrass beds,” Dr Lanyon says.
Even if there is enough seagrass to eat, dugongs are still affected. They show increased levels of heavy metals, pathogens and microplastics after floods, and “there is a drop in body condition compared to that time in other years”, Dr Lanyon says.
But, she adds, this population may be faring better than those further north. They’re exposed to agricultural runoff, which could severely affect the dugongs.
In these northern populations, researchers have not been able to observe calves in the year after major cyclones and floods, suggesting none were born or survived early life.
It is unclear whether this also happens in Morton Bay.
There are also other looming threats such as the H5N1 strain of bird flu, which has affected many other species of mammals around the world.
H5N1 hasn’t yet arrived in Australia, but Dr Lanyon is monitoring dugongs for any signs of the disease.
“We want to detect an emerging problem, not wait until there’s a mass mortality event,” she says.
International insights
Onboard the floating vet clinic, Chiaki Yamato is busy measuring the width of the bull’s head.
This is her second year studying Moreton Bay’s dugongs.
While the Moreton Bay population appears to be stable, other populations in waters around Asia and Africa are declining.
Before joining the University of Queensland team, Dr Yamato studied dugongs in ThailaND.
“In Thailand, if we could see one dugong in three boating days, I was very happy … but here, on the first day I went on the sea we were having lunch surrounded by a herd of dugongs,” Dr Yamato says.
By taking precise measurements on the boat and comparing those measurements to drone footage, Dr Yamato can better estimate size from the air. (ABC TV: Dr Ann’s Secret Lives)
Dr Yamato hopes the measurements she takes in Moreton Bay can be used to help develop non-invasive ways of studying the animals elsewhere. (Supplied: Chiaki Yamato)
When dugongs come up for breath, their body is often bent, making them hard to measure. (Supplied: Chiaki Yamato)
It is too risky to catch and study unhealthy members of declining populations, so Dr Yamato is trying to develop a way to measure the animals using drones.
Drones can be an affordable and low-impact way to study species for researchers who are licensed to use them, making her data invaluable for use on vulnerable populations.
She’ll use the information gathered from measuring the Moreton Bay dugongs in the water and on the boat to help refine measurements taken by drones.
Swabbed, sampled and measured, the healthy male is ready for release, but for Dr Yamato, it is not yet goodbye.
As the dugong swims free, her drone buzzes in its wake.
Check out the Dr Ann’s Secret Lives episode about dugongs on ABC iview.