DisastersCommon clam to help clean oil-filled waters

Rangia, a brackish water marsh clam // Source: texasbeyondhistory.net

The lowly Rangia clam, so common in the waters of Lake Pontchartrain, Lake Maurepas, and other brackish bodies of water in the U.S. South, may take on a new role if studies at Southeastern Louisiana University determine the organism can actually contribute to helping clean oil-polluted waters.

Caitlyn Guice, a junior chemistry major from Prairieville, has received a $2,300 Louisiana Sea Grant Undergraduate Research Opportunities Grant to study the ability of the clam to remove hydrocarbon pollutants from natural water — like the oil that polluted the Gulf of Mexico last summer. She will be working under her faculty mentor, Phillip Voegel, assistant professor of chemistry.

The research is an outgrowth of the work that Voegel and Guice performed last summer when they analyzed water samples from the lakes as well as the clams themselves to determine if they absorbed any oil. In the wake of the BP oil spill, they and several other Southeastern scientists performed a number of studies, evaluating water quality, assessing the health of several species of plants and animals, and conducting visual surveillance of the wetlands for oil contamination.

Voegel explained that clams are bottom-dwelling filter feeders, obtaining nutrients by filtering the water around them. Although a food source for a number of aquatic species such as drum fish and crabs, the Rangia clams are generally small and not typically eaten by humans in the United States.

“As filter feeders, these clams help to maintain water clarity and quality,” said Guice. “We began studying them last summer as a possible marker for water contamination by the oil spill because they can concentrate hydrocarbons in their flesh.”

The scientists’ thinking then turned to the possibility of the clams serving as a natural cleaning mechanism of waters polluted by oil or other possible contaminants.

“Looking at bioconcentration of hydrocarbons by shellfish in this manner is a complete shift in thinking from the typical focus on food safety,” said Voegel. “Successful completion of this project will provide new knowledge on the abilities of the Rangia clam to concentrate pollutants from the water and determine if and under what environmental conditions, this ability could be applied to the bioremediation of oil-contaminated sites.”

He envisions the possibility of moving large caged pallets of the clams into oil-affected waters to assist in the collection of oil. The cage would prevent other species that feed on the claims from getting to them.

“We wouldn’t want them entering the food chain,” he said.

Guice will be looking at the effects of various environmental factors, such as the salinity levels of water, on the process of oil bioconcentration in the clams.

“Most of my work will focus on lab studies with clams grown at varied salinity and with different levels of oil pollutants,” Guice explained. “Then, over time, I’ll test the amounts of oil remaining in the water to determine how well the clams absorb the pollutants.”

Voegel said the information obtained in the study could lead to environmentally friendly methods that would use clams to clean lakes and wetlands that have been contaminated by oil. Of course, that would require further studies, he emphasized.

“It is exciting to consider the use of existing biological resources that could help alleviate the damage that occurs when petroleum products are accidentally released into the environment,” he said. “It’s an exciting concept.”

Guice anticipates completing the project by December 2011.