title: Dispersants have limited effects on exposure rates of oil spills on fish eggs and larvae in shelf seas.
abstract: Early life stages of fish are particularly vulnerable to oil spills. Simulations of overlap of fish eggs and larvae with oil from different oil-spill scenarios, both without and with the dispersant Corexit 9500, enable quantitative comparisons of dispersants as a mitigation alternative. We have used model simulations of a blow out of 4500 m(3) of crude oil per day (Statfjord light crude) for 30 days at three locations along the Norwegian coast. Eggs were released from nine different known spawning grounds, in the period from March 1st until the end of April, and all spawning products were followed for 90 days from the spill start at April first independent of time for spawning. We have modeled overlap between spawning products and oil concentrations giving a total polycyclic hydrocarbon (TPAH) concentration of more than 1.0 or 0.1 ppb (μg/l). At these orders of magnitude, we expect acute mortality or sublethal effects, respectively. In general, adding dispersants results in higher concentrations of TPAHs in a reduced volume of water compared to not adding dispersants. Also, the TPAHs are displaced deeper in the water column. Model simulations of the spill scenarios showed that addition of chemical dispersant in general moderately decreased the fraction of eggs and larvae that were exposed above the selected threshold values.
authors: †Institute of Marine Research, Box 1870, Nordnes, N-5817 Bergen, Norway.
authors: Frode B
authors: FB
authors: Vikebø
authors: ‡SINTEF, Strindvegen 4, 7465 Trondheim, Norway.
authors: Petter
authors: P
authors: Rønningen
authors: †Institute of Marine Research, Box 1870, Nordnes, N-5817 Bergen, Norway.
authors: Sonnich
authors: S
authors: Meier
authors: †Institute of Marine Research, Box 1870, Nordnes, N-5817 Bergen, Norway.
authors: Bjørn Einar
authors: BE
authors: Grøsvik
authors: †Institute of Marine Research, Box 1870, Nordnes, N-5817 Bergen, Norway.
authors: Vidar S
authors: VS
authors: Lien
mesh_terms: D000818:Animals; D004531:Eggs; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods / Q000706:statistics & numerical data*; D005399:Fishes; D007814:Larva / Q000187:drug effects*; D010578:Petroleum / Q000633:toxicity*; D059392:Petroleum Pollution / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D010578:Petroleum; D014874:Water Pollutants, Chemical