Selection of the best method for preserving structural timbers in the marine environment requires an assessment of the relative toxicity of preservation methods. Creosote has been identified as toxic to herring embryos in a laboratory experiment where the LC50 for hatching success was reported to be 50 ppb (Vines et al 2000). In the current study, Pacific herring embryos were exposed to water that had flowed past various quantities of creosoted wood treated to BMP (Best Management Practices). Mean concentrations of total creosote—derived PAHs (polycyclic aromatic hydrocarbons) in exposures ranged from 0.12- 30.33 ppb. Statistically significant responses included death, skeletal defects, and impaired swimming ability. Due to a high level of variation observed in hatching success, the current study estimates an LC50 for hatching success at between 5 and 50 ppb. Skeletal defects were also observed and the LC50 for skeletal defects is 17 .75 ppb with far less variation, SE=0.76. The LC50 for swimming performance is 22.00 ppb (SE = 1.22). The results of this study indicate that embryonic exposure to creosote-treated wood effluent in low part-per-billion concentrations results in decreased hatch rates, increased incidence of skeletal defects, and impaired swimming ability in Pacific herring. These results build upon those of Vines et al. and demonstrate that creosote is toxic to Pacific herring embryos at part-per-billion levels. These responses have negative implications for survival and fitness. A field study is currently in progress to evaluate environmental levels of creosote derived PAH.
