From: Andy Soos, ENN
Published May 24, 2012 02:01 PM

Deep Sea Hitchhiking

The bottom of the sea is dark and lonely. Yet there is life usually isolated and located near some source of energy such as a deep sea vent. these vents are not continuous and in between there is a lot of empty space and totally alien environmental conditions especially between the bottom of the sea and the top of th3e ocean. 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 inadvertently carried by submersibles to new areas, with potentially damaging effects on marine ecosystems.

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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 among their sample. Intriguingly this species is believed to occur only in the vents of the Gorda Ridge, which are 635 km south of the dive site.

The Juan de Fuca Ridge is a tectonic spreading center located off the coasts of the state of Washington in the United States and the province of British Columbia in Canada.  The Gorda Ridge is a tectonic spreading center located off the coast of Oregon and northern California north of Cape Mendocino.

"The big question was, how did they get over 600 kilometers from their habitat?" said Dr. Janet Voight, from the Field Museum of Natural History in Chicago. "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 assumed that the extreme pressure change would kill any species which are missed."

The introduction of new species to an ecosystem by humans, often inadvertently, is a big challenge to conservation. How a new species will react to new surroundings, and the effect it can have, is unpredictable. Increases in deep-sea drilling and submersible activity can increase the probability of introductions, but until now hydrothermal vents have been considered too extreme and too isolated to be a source of introduced species.

In coastal environments one of the biggest threats posed by invasive species to native species is disease, as newly introduced pathogens and parasites can cause mass mortality. Diseases that may exist in the extreme environments created by hydrothermal vents have not been well studied.

"We've discovered that it is possible to accidentally introduce a species, and any potential diseases it may carry, from a deep-sea vent to a new location," concluded Voight. 

A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both geologically active and has large amounts of water on its surface and within its crust. Common land types include hot springs, fumaroles and geysers. Under the sea, hydrothermal vents may form features called black smokers. Relative to the majority of the deep sea, the areas around submarine hydrothermal vents are biologically more productive, often hosting complex communities fueled by the chemicals dissolved in the vent fluids. Chemosynthetic archaea form the base of the food chain, supporting diverse organisms, including giant tube worms, clams, limpets and shrimp.

For further information see Deep Sea Vents.

Limpet by Todd Haney via Field Museum of Natural History in Chicago.

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