Athens, Ga. Researchers have found that a species invasion that starts at the upstream edge of its range may have a major advantage over downstream competitors, at least in environments with a strong prevailing direction of water or wind currents.
Scientists from the University of Georgia, University of New Hampshire, Smithsonian Environmental Research Center and University of Vermont studied populations of European green crab, Carcinus maenas. The species was introduced to the East Coast of North America twice, at both the upper and lower edges of its range. Their findings, recently published in the Proceedings of the National Academy of Sciences, may help inform the control of invasive species and the conservation of imperiled native species.
"In New England, they're worried," said Jeb Byers, an associate professor at the UGA Odum School of Ecology and one of the paper's authors. "These green crabs have been doing a number on native shellfish. They eat a lot of clams. And they're a very cosmopolitan speciesthey've now spread all over, to places as far afield as the West Coast of the U.S. and South Africa."
The European green crab was first detected in North America in New Jersey in the early 1800s, Byers said. It spread slowly north against the prevailing direction of ocean currents until it reached Halifax, Nova Scotia in 1964. That was the extent of its range along the East Coast until the 1990s, when populations suddenly appeared throughout the Canadian Maritime provinces.
Conservation biologist Joe Roman of the University of Vermont, another of the paper's authors, determined that these new populations were genetically different from those established earlier. Analysis revealed that unlike the earlier arrivals, they were related to European green crabs found in the Baltic, suggesting a new introduction directly from Europe to Nova Scotia had taken place.
Understanding how the species spread c
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University of Georgia