New Waves March 2008

Breaking news about water resources research and education in Texas

Graduate student researches exotic mud crab introductions

Texas A&M University graduate student Terrence Boyle Jr., under the direction of Dr. Mary Wicksten, biology professor, is studying the mud crab, Rhithropanopeus harrisii, recently introduced to Texas. The crabs are known to foul up water intake pipes.

The crab, first reported in Possum Kingdom Reservoir during the summer of 1998, has since been confirmed in seven other lakes and reported from a ninth lake as well. The lakes with confirmed populations are Trading House Creek Reservoir, Lake Colorado City, E.V. Spence Reservoir, Squaw Creek Reservoir, Lake Balmorhea, Lake Granbury and Lake Whitney. The latest report is from Lake Braunig in the fall of 2006.

"The crabs are reproducing in these lakes and show all indications of successful introductions," Boyle said.

"Successful reproduction may be due to increased salinity during recent drought years," he said. "Decreased freshwater input and increased water usage may be influencing salinity, which can further influence the biota."

Boyle's research is focusing on the interactions between this exotic species and the native crayfish, as it appears that the crabs may be outcompeting the crayfish.

Boyle said he is also trying to establish how many introductions have taken place as well as identify from where the original population may have come. Boyle's previous research at Tarleton State University indicated that there had been at least two introductions, but the study did not include individual crabs from all of the introduced populations.

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