Back on land, Beinart’s lab is now studying post-eruption changes in the genetic diversity in host animals and the bacteria that provide their energy. She had explored the region before and didn’t see a major shift in the animals’ genetic diversity. However, some strains of bacteria at the worst-hit sites are now missing, which could put animals that rely on them at risk.

“We did see some types of bacteria still present in the environment, but we don’t know whether they’re able to reproduce or they’re just in a dormant stage, waiting to attach to a host animal,” Beinart said. The bacteria must be able to survive on their own for at least some length of time because they aren’t found in the larvae of vent animals––only the full-grown ones. “The biological components for recovery are there, but we have no idea if they’ll actually be able to bounce back.”

Not much is known about the animal larvae the team found, but scientists think they probably settle on bare rocks like those the adults live on. Those hard surfaces are now covered in ash. It’s unclear whether that will spell the creatures’ collective doom.

Troubled waters

Beyond any lessons in ecology, the team’s observations may also preview the potential aftermath of deep-sea mining. Some mining methods kick plumes of sediment up into the water column, where it later settles on the surrounding seafloor.

“The mass-mortality of seafloor life following 2022 Hunga Volcano eruption, a result of the smothering by redistributed sediments and volcanic ash, provides a unique perspective of the damage that can be done to deep-sea communities following seafloor disturbance events,” said Sarah Seabrook, a marine biogeochemist at New Zealand’s National Institute of Water and Atmospheric Research, who was not involved in the study. “It provides a natural analogue for the potential impacts of activities such as deep-sea mining and bottom trawling, which are correlated to the removal and redistribution of sediment on the seafloor.” 

It’s not a 1:1 comparison––mining efforts probably won’t target active vents, and some of the locations that will likely be targeted are already naturally covered in sediment. But scientists currently have extremely little information about how deep-sea animals respond to disturbances in general, so the new observations help fill a major gap.

“A lot of the mining that’s being considered is in the Western Pacific, like the area we studied, which is a totally different geological setting than the Eastern Pacific, where a lot of the work about the recovery of vent ecosystems is happening,” Beinart said. The Eastern Pacific is a naturally more active area because tectonic plates there are spreading apart more quickly, which makes eruptions more common. Animals there have likely adapted to more frequent changes. It’s probably not valid to assume creatures in the Western Pacific will be able to similarly recover, “so this is a useful tool to understand how Western Pacific communities, which adapted under different conditions, can deal with dramatic change,” Beinart said.

Perhaps unsurprisingly, the expedition’s serendipitous observations opened up more questions than they answered.

“We saw some evidence of potential recovery––some animals, though smaller populations, and active reproduction along with lots of larvae,” Arellano said. “But what we don’t know is how things have gone from there.” Perhaps the animals can settle on the sediment after all. Or the sediment may have been cleared away from the area by deep-sea currents.

So far, no one has been back to make any follow-up observations. Beinart secured funding for a sequel expedition, but it likely won’t occur until 2026. “We’re potentially missing lots of major shifts or milestones while we wait to go back,” Beinart says. “Who knows what we’ll see when we finally return?”

Ashley writes about space for a contractor for NASA's Goddard Space Flight Center by day and freelances as an environmental writer. She holds master's degrees in space studies from The University of North Dakota and science writing from The Johns Hopkins University. She writes most of her articles with one of her toddlers on her lap.