Effects of Bioremediation on Toxicity and Chemical Composition of No. 2 Fuel Oil: Growth Responses of the Brown Alga Fucus vesiculosus

We conducted a laboratory experiment to assess the effectiveness of nutrient (N and P) application to indigenous, marine microbial populations as a bioremediation technique to respond to oil spills along the temperate coastline of the western North Atlantic. We investigated the effects of various concentrations (10 ppm to 1 ppt) of No. 2 fuel oil, a commonly transported oil, on growth rates of the intertidal macroalga Fucus vesiculosus. We found growth inhibition after a one-day application of the lowest concentration tested and a clear dosage effect. The sensitivity of F. vesiculosus to oiling suggests that this abundant brown alga may serve as an effective indicator species. Nutrient (N + P) application as a bioremediation technique ameliorated the toxic effects of oil on F. vesiculosus without resulting in enrichment of macroalgal growth. Analysis of treatment samples with gas chromatography indicated greater microbial breakdown of the oil under enriched, compared with unenriched conditions. We measured a complete loss of n-alkanes, the preferred substrate by micro-organisms, from `enriched+oiledʹ samples after 18 days, while oil introduced to autoclaved seawater showed only minimal degradation. Bioremediation may be a viable clean-up alternative for petroleum contamination of temperate ecosystems, particularly in areas of heavy shipping traffic, which probably support a relatively large background population of oil-degrading organisms.