Influence of a dispersant on the bioaccumulation of phenanthrene by topsmelt (Atherinops affinis).

Abstract Chemical dispersants enhance oil spill dispersion by forming water-accommodated micelles with oil droplets. However, how dispersants alter bioavailability and subsequent bioaccumulation of hydrocarbons is not well understood. Thus, the goal was to investigate the influence of a chemical dispersant on the disposition (uptake, biotransformation, and depuration) of a model hydrocarbon, [ 14 C]-phenanthrene ([ 14 C]PHN), by larval topsmelt ( Atherinops affinis ). Exposure was via aqueous-only or combined dietary and aqueous routes from a water-accommodated fraction (WAF) of Prudhoe Bay Crude Oil (PBCO) or a WAF of Corexit 9527-dispersed PBCO (DO). Trophic transfer was measured by incorporating into exposure media both a rotifer ( Brachionus plicatilis ) as food for the fish and a phytoplankton ( Isochrysis galbana ) as food for the rotifers. Short-term (⩽4 h) bioconcentration of PHN was significantly decreased in topsmelt when oil was treated with dispersant ( P 0.05 ), but differences diminished after 12 h. When trophic transfer was incorporated, PHN accumulation was initially delayed but after 12 h attained similar levels. Dispersant use also significantly decreased the proportion of biotransformed PHN (as 9-phenanthrylsulfate) produced by topsmelt ( P 0.05 ). However, overall PHN depuration was not affected by dispersant use. Thus, chemical dispersant use in oil spill response may reduce short-term uptake but not long-term accumulation of hydrocarbons such as PHN in pelagic fish.