Razor clams, ghost shrimp don't mess around after oil spills

Cleaning up after environmental disasters may be all in a day’s work for stout razor clams and ghost shrimp.

In separate studies, UL Lafayette researchers simulated oil spills, and found sediments that contained the creatures held less oil than areas where they weren’t present.

“Our research shows that evaluations of oil spill impacts need to consider how animals living in coastal areas may influence what happens to the oil, where it will be found and how fast it will disappear,” said Dr. Paul Klerks, a biology professor and one of the projects’ investigators.

“So much depends on a vibrant coastline, from the seafood and tourism industries to the fish, shrimp and oysters we buy in stores. Studies such as these can help people decide when it is safe to go back to beaches or eat seafood following an environmental crisis.”

Razor clams and ghost shrimp are bioturbators; their burrowing reworks and moves sediment in the coastal areas where they live. Feeding and digging by these ecosystem engineers can push low levels of oil residue into the water column.

There, the ocean’s movements work to dilute contaminants. The water column also contains bacteria that “eat the oil and break it down,” Klerks said. “It’s food for them.”

This teamwork by bioturbators and bacteria could help lessen spills’ effects, he added. University researchers want to know how much.

In one study, they determined coastal sediments that held razor clams retained 25 percent less oil than areas where the mollusks weren’t present. However, levels of toxins below the surface had not increased. While investigators detected some evidence of burial, it was not enough to conclude that the oil’s fate rested below the sediment surface.

Where did it go? An ongoing study of ghost shrimp may hold the answer.

Like razor clams, ghost shrimp dig. The crustaceans’ burrows can be as much as 10 feet deep, while razor clams’ sanctuaries can be up to 30 inches below the surface.

The contrasting depths mean ghost shrimp move more sediment than razor clams do, increasing the chances that oily residue below the surface might be introduced into the water column where it can be diluted or eaten by bacteria. As a result, ghost shrimp “are likely to have even more of an impact than razor clams” on what happens to pollutants, Klerks said.

This article first appeared in the Fall 2019 issue of La Louisiane, The Magazine of the University of Louisiana at Lafayette.

Top photo: Ghost shrimp rearrange and aerate sediment (Courtesy of Darryl Felder).

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