traps, as a substantialamount of nutrients maybound in biomass (Mitsch & Gosselink, 1993). Botfreshwater lakes and wetlands may also exhibit seasonal variations in nutrient levels, which will affect the performance of oilbiodegradation. Ward and Brock (1976) found that in an oil-contaminated lake, oil biodegradation was at the highest rate during early spring when the nutrient content (i.e., N and P) was also high. As N and P levels decreased in the summ(probably due to algal productivity), oil biodegradation also decreased. Another potential limiting nutrient is iron, which was found to limit oil degradationclean offshore seawater, but is not likely to be limiting in freshwater (Foght & Westlake, 1987).