Australian researchers study oysters’ resilience in face of climate change
Near Moreton Bay Research Station’s back entrance is a line of parked research boats and a storage room with diving gear for expeditions. In the facility’s parking lot on North Stradbroke Island off Australia’s eastern coast near Brisbane, an opened freezer used to store research samples thaws in the sun after a recent storm cut power to the station.
“It’s time to defrost everything and empty it out,” said Ben Mos, senior lecturer in aquaculture biology at the University of Queensland. “Rotting seafood is one of the worst smells there is.”
Moreton Bay, part of Quandamooka Country in southeastern Queensland, has lost over 95% of its oyster reefs since European colonization began in the late 18th century. These reefs — one of the world’s most-degraded marine ecosystems — are not just the source of a culinary delicacy, but they help to filter seawater and protect shorelines from the effects of storms, sea-level rise and increasing temperatures. Researchers at the University of Queensland are working with the nonprofit OzFish Unlimited, as well as Quandamooka Elders, to study possible solutions to revitalize oyster reefs in the bay.
Inside the wet lab were tanks the size of small, above-ground pools. A set of glass fish bowls lined the shelves. But the room’s centerpiece was 16 barrels filled with seawater, which circulated between them through black and clear tubes. Inside each barrel is a steel basket that the researchers had filled with empty oyster shells collected from restaurants.
The researchers had dropped the steel oyster baskets in the bay for six to 18 months and then brought them back to the wet lab for testing.
“All the oysters are growing on top of each other, they’re all bound together,” Mos said, holding up a basket, its wires now corroded away and covered in new oyster shells. “They’re creating these little spaces and gaps in between for other little organisms to grow in. And the whole reef itself is holding together.”
Researchers want to know if these habitats will hold up in warming oceans and if the oysters will continue to filter the water. In the lab, they have heated the water to the extreme temperatures predicted for the year 2100.
“We’ve taken them all the way up to 33 degrees Celsius (about 91 degrees Fahrenheit),” he said. “They didn’t like it so much, but they were still filtering at about half of their usual capacity,” he said of the organisms.
The researchers have also tested these oyster baskets with different salt levels in the water. After storms, which are likely to intensify with climate change, freshwater and other pollutants wash into the bay. When the baskets were tested in water with low levels of salinity — close to freshwater — they were still able to filter at about two-thirds of their usual capacity.
Through the use of environmental DNA testing, the researchers found more than 400 different types of organisms living in these baskets. That kind of biodiversity helps with managing pollution and makes it possible for more oysters and other seafood to flourish.
This research is particularly important because the ocean water off the east coast of Australia is warming three to four times quicker than other parts of the planet, Mos explained.
“Here in Moreton Bay or Quandamooka, we’re seeing the effects of climate change before everybody else,” he said. “We’re like a canary in the coal mine.”
A National Adaptation Plan is currently in the works in Australia to address the country’s broader, long-term response to climate change. But some people think it is not happening fast enough.
“At the moment, within Australia, we see that the agenda to adapt to climate change is very much on the back foot. It’s a low priority,” said Mark Howden, who led the Institute for Climate, Energy and Disaster Solutions at the Australian National University for about a decade.
Besides the oyster reef restoration project, there are some other promising solutions underway. Marine biologists are growing coral larvae in floating pools, in a technique known as coral IVF, to restore damaged areas of the Great Barrier Reef. Other researchers are investigating ways to cool and shade reefs to protect them from the impacts of climate change.
But by 2030, the world’s oceans will require an estimated $175 billion in investments annually to meet the UN’s sustainable development goals. Others estimate it could cost up to $1 trillion per year to restore ocean health, according to David Mead, executive director of strategic development at the Australian Institute of Marine Science. For Mead, that’s just a number.
“To spend $1 trillion a year, you actually need methods that you can spend $1 trillion on. Right now, we don’t have them in a lot of instances,” he said.
When it comes to Australia’s coral reefs, Mead says they are some of the best managed on the planet.
“That has bought us a window of time here,” he added. “We have a short window of opportunity that we can potentially do something about it.”
Doing something, he said, requires dreaming up new technologies that do not even exist yet and galvanizing people to work toward large-scale solutions.