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Digging Into Pollution Problems

Plaster of Paris casts of the burrows of salt marsh fiddler crabs show how crabs from a healthy marsh (left side) dig straighter and deeper holes than those burrowing into a marsh that was polluted by an oil spill more than 38 years ago. Fiddler crabs that burrowed into the relatively pristine marsh made holes that were straight and stretched an average of 14.8 centimeters. In a marsh tainted by residual oil, the burrows averaged 6.8 cm and showed erratic shapes where the fiddler crabs halted or turned laterally. The locations of the stunted, twisted burrows mapped closely with the location of residual oil in the sediments. (Photo by Tom Kleindinst, Woods Hole Oceanographic Intitution)