Some hitch rides on submarines.

• Position: Invasive Species

Marine scientists studying life around deep-sea vents have discovered that some hardy species can survive the extreme change in pressure that occurs when a research submersible rises to the surface. The team's findings, published in Conservation Biology, reveal how a species can be carried inadvertently by submersibles to new areas, with potentially damaging effects on marine ecosystems.

After using the manned submersible Alvin to collect samples of species from the Juan de Fuca Ridge under the northeastern Pacific Ocean, the team discovered 38 deep-sea limpets (Lepetodrilus gordensis) among their specimens. Intriguingly, this species is believed to occur only in the vents of the Gorda Ridge, which are 635 kilometers south of the dive site.

"The big question was, how did they get over 600 kilometers from their habitat?" wonders Janet Voight, from the Field Museum of Natural History, Chicago, Ill. "We discovered that the individuals must have been transported from the Gorda Ridge by our submersible. Even though we clean the submersibles after sampling, we had always assumed that the extreme pressure change would kill any species that are missed."

The introduction of new species to an ecosystem by humans--often inadvertently--is a big challenge to conservation. How a new...