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Deep-sea creatures may be hitchhiking on scientific gear

The world’s most famous research submersible may have inadvertently been carrying invasive species between the deep-water sites it has spent decades studying.

Since its creation in 1964, the venerable Alvin sub has performed thousands of dives, and its successes include surveying the Titanic and probing the first discovered hydrothermal vents.

In 2004 a team of scientists using Alvin found 38 tiny limpets of a type normally seen on hydrothermal vents in samples they had grabbed from an area with no vents. In fact, they were hundreds of kilometres north of the known range of the species they found. Their conclusion: the animals had hitched a ride on Alvin after a previous dive.

“I was so upset when I came to that realization,” says Janet Voight, a deep-sea biologist at the Field Museum of Natural History in Chicago, Illinois, and the lead scientist on that mission.

In a paper out today in Conservation Biology, Voight and her colleagues report finding the limpets after taking samples on the Juan de Fuca Ridge in the Pacific Ocean. They identified the species as Lepetodrilus gordensis (pictured, left), but this animal has only previously been found 635 kilometres to the south, in an area known as the Gorda Ridge.

Using gene sequences, isotope data and other information, they confirmed that the animals they found after the Juan de Fuca dive were identical to those found on the Gorda Ridge, where Alvin was diving just before the Juan de Fuca mission.

Voight admits that an error was made and that the team should have been more careful in its cleaning of Alvin’s sampling systems. But the survival of the limpets from one dive to the next has broader implications.

Research submersibles are cleaned after every mission, but it was widely assumed that the radical changes in pressure and temperature as they surfaced from the depths would kill any animals that were missed, says Voight. If that is not the case, researchers may have been inadvertently contaminating sites as they move a limited number of research vessels around multiple deep-sea sites.

There are dozens of submersibles used in research and other sectors, plus a host of different monitoring and sampling devices that researchers deposit into the murky depths of our oceans. All of these now have to be considered capable of unwittingly transferring species from one location to another.

“It’s agreed that we should not transplant populations among different sites,” says Voight. “But the threat of having the same instrument as a vector has been neglected.”

In addition to making sure sampling systems are carefully cleaned, researchers could consider washing subs with fresh water as one way of killing any stowaways, she suggests.

Image top:
Alvin courtesy of OAR/National Undersea Research Program (NURP); Woods Hole Oceanographic Inst.
Image lower:
Lepetodrilus gordensis courtesy of Ray Lee.

Comments

  1. Report this comment

    Matt Chew said:

    An animal trapped in a collecting apparatus is NOT hitchhiking or stowing away.

    Hitchhikers and stowaways intend to leave wherever they are. Hitchhikers actively solicit transportation. Stowaways intentionally steal it. Most have destinations in mind. Nothing living around a deep-sea vent is likely to have any conception of ‘here’ or ‘there’, much less the capacity to recognize a potential means of transport or to work out strategies for soliciting or stealing it.

    If NPG insists on deploying anthropomorphic metaphors, it would be more apt to call animals transported in this fashion abductees, and perhaps victims of negligent abuse and false imprisonment. I don’t imagine there will be a rush to do that, because the point of stories like this is to pin the blame on organisms for failing to conform to (rash or thoughtless) human expectations.

    Finally, there is reason to suggest that any organism so transported between collection sites is “invasive.” Even if we grant that “invasive” applies to animals (and I don’t, for the same reasons cited above) there is no evidence presented that populations of species from one site are proliferating at another.

    NPG seems to be suffering from (and more problematically, promoting) scientific illiteracy.

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      Matt Chew said:

      Sorry, editing error. Should have been: There is NO reason to suggest…

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    John Molloy said:

    Would “non-invasive apply to all organisms transported to a new area Matt?

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    Anthony Kerwin said:

    Call it what you will, but I say kudos to the team to not only say they’ve overlooked a potential issue with transporting (potentially invasive) organisms from one site to another, but to publish it, and admit their mistake.

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