Biologists from Hendrix College and the University of Central Arkansas say the ecosystem within the Lake Conway Watershed is likely still in danger six months after the oil spill in Mayflower.
Remnants of the heavy crude can be seen along the oil’s route of travel, a downhill flow that took it through a residential street, a system of drainage ditches, and eventually into the Lake Conway Watershed.
The product made its way to a wetland that is just south of Arkansas Game and Fish Commission’s Bell Slough Wildlife Management Area, a reserve home to fowl, fish, reptiles and many small mammals.
The long-term effects of organisms’ exposure to the chemicals associated with the heavy crude product can be more impactful than the initial exposure, according to Dr. Matthew Moran, a Hendrix biology department professor who teaches ecology and zoology.
Dr. Vickie McDonald, a UCA biology department professor and expert in vertebrate zoology, also looks at the incident with concern for the long-term, cumulative effects on living things, particularly the birds that live in the area.
"Often when we think of chemical spills, we’re more concerned with the direct poison rather than the long-term cumulative effects and behavior," she said. "I’m taking the long-term approach."
McDonald plans to study warblers and their behavior this coming Spring to document possible changes and test feathers for any sign of "persisting chemicals" that may have introduced themselves into the food chain.
McDonald said some of the chemicals that were said to have been associated with the crude are known teratogenic agents that can cause malformations in an embryo or fetus or change the nature of reproduction.
Some were clearly carcinogens, she said.
Bioaccumulation can occur when toxins are exposed to an ecosystem, according to both professors.
Bioaccumulation, they explained, occurs when fat soluble compounds move up the food chain and become more concentrated as animals consume them.
An example Moran provided was an insecticide called DDT that bioaccumulated as smaller organisms consumed it until it moved from fish to high predatory mammals such as bald eagles.
The bioaccumulation is said to have been associated with the bird’s decline after it impacted unhatched offspring.
"No matter how good the intentions and competence, no matter how good they are, you can’t recover all of the oil. It gets into living systems and deep into the soil, and there’s no physical way to recover it," said Moran.
A visual check Moran performed last week with the Log Cabin Democrat at several sites along the oil’s route of travel revealed black solids that smelled like petroleum and blackened mud that smelled and looked like it contained oil one to two inches below the dirt’s surface.
When Moran put a shovel into underwater sediment at several locations in the creek that flows behind the shopping center in Mayflower, an oil sheen floated to the surface of the water.
The cove seen from State Highway 89 North has an oil sheen over a large part of its surface.
The cove’s water level is low and now flowing into the large body of the lake through the culvert beneath the roadway, and Moran said when rain comes in Fall, he expects the oily water to flow with the rest into the main body of the lake.
The oil sheen had collected on the surface of the water past at least two systems of boom along the oil’s known route of travel.
There is another boom barrier that floats on top of the water, on the other end of the culvert, which empties to the main body of Lake Conway that is used to filter oil from the surface, should contaminants flow from the cove.
"When our first big rain comes this fall, this water will move to the lake," Moran said.
Moran said without direct flow, contaminants will travel from the cove and creeks through living things.
"We can work to recover the spill material, but once it gets into living organisms, it moves very easily. We can’t control their movement," he said.
Moran said the spill’s effects on the ecosystem shouldn’t be considered permanent because petroleum does break down eventually, and volatile organic compounds can be metabolized by microbes.
Some compounds may be in living tissue for "a long time," he said, and oil trapped under topsoil can reemerge in weather events.
He said his biggest concern is the possible lasting effect on reproduction, which would impact some species’ ability to repopulate.
(Staff writer Courtney Spradlin can be reached by email at firstname.lastname@example.org or by phone at 505-1236, or on Twitter @Courtneyism. To comment on this and other stories in the Log Cabin, log on to www.thecabin.net. Send us your news at www.thecabin.net/submit)