Effects of washing fiddler crabs (Uca pugnax) following an oil spill.

An oil spill on 2 January 1990 in New Jersey resulted in premature emergence of fiddler crabs Uca pugnax from their underground burrows. Live fiddler crabs that emerged on the surface were collected and behavioral changes were compared between those that were washed with freshwater and those that were not washed. Locomotion, aggression, balance, and burrowing behavior were examined. Unwashed crabs improved significantly on only one of twelve behavioral tests, while washed crabs improved in four tests relating to movement, defensive behavior, and burrowing. The washed crabs showed the greater improvement on ten of twelve tests while unwashed crabs showed greater improvement for two tests. Washed crabs also showed greater improvement in their ability to find and to construct their own burrows. These experiments indicate that oil removal improves the behavioral performance of crabs, and suggests that under some circumstances the immediate flushing of salt marsh creeks by uncontaminated tidal waters may decrease behavioral effects on crabs.