Deep-Sea ‘Zombie Worms’ Vanish, Signaling potential Ecosystem collapse
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A concerning trend is unfolding in the depths of the Pacific Ocean: the unexplained disappearance of Osedax, commonly known as “zombie worms,” is raising alarms among scientists about the health of deep-sea ecosystems and the potential for widespread species loss linked to climate change.
A decade-long experiment conducted off the coast of British Columbia (BC) has revealed a startling absence of these crucial creatures, despite their well-established role in breaking down whale bones and supporting complex food webs. The findings, recently published, underscore the growing unease surrounding the impact of expanding low-oxygen zones on marine life.
A Decade-Long Watch in Barkley Canyon
Fabio De Leo, a senior staff scientist with Ocean Networks Canada (ONC) and an adjunct assistant professor at the University of Victoria (UVic), co-led the ambitious study. Researchers strategically placed humpback whale bones on the ocean floor within Barkley Canyon, nearly 1,000 meters below the surface, and meticulously monitored them for signs of life.
For years, the team anticipated the arrival of the Osedax worms, known for their unique feeding habits. These creatures lack a conventional digestive system – no mouth,
Whale Falls and Expanding Oxygen Minimum Zones
When whales die,their bodies sink to the seafloor,creating what are known as whale falls.These events represent a concentrated pulse of nutrients, supporting a diverse community of organisms. The absence of Osedax at Barkley Canyon suggests that the expansion of oxygen minimum zones (OMZs) in the northeast pacific and beyond may be disrupting this critical ecological process. preliminary data from ongoing research at another ONC NEPTUNE site indicates similar concerns in other areas.
The implications are far-reaching. Without osedax to break down bones, the ecological succession process is disrupted, limiting access to vital nutrients for numerous species.whale falls, as one scientist explained, are “almost like islands,” serving as “a stepping-stone habitat for this and many other whale bone specialist species.”
The Looming Threat of Species Loss
The disappearance of the “bone devourer” raises the specter of species loss. Adult Osedax worms reside on whale bones, while their larvae travel vast distances – sometimes hundreds of kilometers – through ocean currents to colonize new whale falls. If these habitats vanish or become uninhabitable, the connectivity between populations breaks down, possibly leading to a decline in Osedax diversity across entire regions.
The research also revealed signs of stress in another key ecosystem engineer: wood-boring Xylophaga bivalves. While present on submerged wood samples, their colonization rates were significantly lower than in oxygen-rich waters, potentially delaying carbon decomposition and reducing habitat formation.
“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,” said Craig smith, professor emeritus from the University of Hawaii, who co-led the experiment.
Data collection and Future Research
De Leo and Smith relied on ONC’s NEPTUNE observatory Barkley Canyon Mid-East video camera platform, alongside oceanographic sensors and high-definition video collected by remotely operated vehicles. Additional data is anticipated in the coming months from a whale fall currently being monitored at NEPTUNE’s Clayoquot Slope site.
The research was supported by the Canada foundation for Innovation Major Science Initiative Fund and a US National Science Foundation grant, and aligns with United Nations Sustainable Development Goal 14, focused on life below water. The vanishing of the zombie worm serves as a stark reminder of the hidden vulnerabilities within our planet’s deepest ecosystems and the urgent need to address the impacts of climate change.
