Scientists alarmed by zombie worms missing from B.C. waters
A ten-year study found that zombie worms are missing from the ocean floor in waters off British Columbia’s coast—a finding that could signal a much bigger climate problem.
Scientists at the University of Victoria (UVic) in British Columbia have made an alarming discovery: zombie worms are missing from B.C.’s ocean floor. These missing worms spell trouble, but not for the reason you may think.
Zombie worms, scientifically known as Osedax, are critical in decomposing bones from dead whales on the ocean floor.
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In a study published in Frontiers in Marine Science, scientists placed bones of a humpback whale on the ocean floor off the B.C. coast, where oxygen in the water is naturally low, and used underwater cameras to observe which type of species would colonize the bones. Working with Ocean Networks Canada (ONC), the study took place over a period of ten years.
Whale bone experiment recovered from Barkley Canyon in 2023. (Credit: Ocean Networks Canada)
In those ten years, the scientists working on the study found no evidence of any zombie worm colonization on the whale bones—a red flag signalling a much bigger problem.
“This was a remarkable observation in such a long-term experiment,” said Fabio De Leo, a senior staff scientist with ONC and adjunct assistant professor with UVic’s Department of Biology, in a media release.
De Leo, who co-led the study, explained that the missing zombie worms could be due to the low oxygen concentration at the observation site and that oxygen minimum zones (OMZs)—layers of water with a low oxygen concentration—are expanding due to climate change, which could be disrupting aquatic ecosystems and biodiversity.
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It is also noted in the study that the oxygen concentration at the site dropped from 0.3 ml/L to 0.22 ml/L during the experiment, a drop that could result in there being too little oxygen in the water for the zombie worms to survive.
The zombie worm, Osedax, on a bone. (Credit: Yoshihiro Fujiwara/JAMSTEC)
“It looks like the OMZ expansion, which is a consequence of ocean warming, will be bad news for these amazing whale-fall and wood-fall ecosystems along the northeast Pacific Margin,” commented Dr. Craig Smith, professor emeritus from the University of Hawaii, who co-led the experiment with De Leo.
The whale-fall ecosystems Smith described are essentially biodiversity hotspots created by whale carcasses that have sunk to the ocean floor, providing nutrients for all kinds of aquatic organisms, including zombie worms, who rely on the whale bones for nutrients and to reproduce.
De Leo says they are essentially islands for zombie worms and other species, as their larvae are dispersed in the ocean currents from one carcass to another.
“Basically, we’re talking about potential species loss,” De Leo states. “So, this connectivity, these island habitats, will not be connected anymore, and then you could start losing a diversity of Osedax species across regional spatial scales.”
Thumbnail image of a zombie worm (Osedax) credit to Adisha Pramod/Alamy.