Effects of an oil spill on emergence and mortality in fiddler crabs Uca pugnax

Abstract

Following a spill of 567 000 gallons of No. 2 fuel oil into the Arthur Kill in New York and New Jersey in January 1990 we studied the emergence and mortality of fiddler crabs. We (1) compared seven salt marsh creeks immediately adjacent to the oil spill with 23 creeks at varying distances from the spill; (2) examined the temporal pattern of emergence in one creek; and (3) compared mortality rate of crabs that emerged with those we dug up. Twice as many crabs emerged in the adjacent creeks compared to those that were only 4.5km away. There were significant differences in the number of crabs that emerged as a function of distance from the spill. Crabs continued to emerge until mid-March. For all the emerged crabs, the percentage of females ranged from 28 to 80, whereas the percentage of females in intact burrows was 64-65%. For all emerged samples, females died earlier than males. In the laboratory, all emerged crabs died within four weeks whereas over 90% of the controls were still alive eight weeks after the initiation of the experiment.