Impact of crude oil and the dispersant Corexit™ EC9500A on capelin (Mallotus villosus) embryo development

Marine food webs are particularly vulnerable to oil spills if keystone species are impacted. To quantify lethal and sublethal toxicity in a key Holarctic forage fish, capelin embryos were exposed to Hibernia crude oil water accommodated fraction (WAF) produced at an oil-to-water ratio of 1:9 (v:v) and chemically-enhanced WAF (CEWAF) produced with the dispersant Corexit™ EC9500A at a dispersant-to-oil ratio of 1:10 (CEWAF H) or 1:50 (CEWAF L). Corexit alone yielded similar embryotoxicity to CEWAF. 10% CEWAF H, with total polycyclic aromatic hydrocarbons of 99.2 μg/L, decreased embryo survival following 10 h of exposure, while continual exposed to 1% CEWAF L decreased hatching and heart rates. Concentrations down to 0.1% CEWAF L increased in a dose-dependent manner the transcript level of cytochrome P4501a1 (cyp1a1) in hatched larvae. These data indicate that embryo-larval survival of capelin is likely at risk if an oil spill coincides in space and time with spawning. [Display omitted] •Capelin embryos were similarly affected by Corexit alone and CEWAFs treatments.•Hatching success was lower in embryos exposed to CEWAF with 2.8 μg/L TPAH throughout development.•Hatching success was lower in embryos exposed to CEWAF with 10.4 μg/L TPAH after late organogenesis.•Exposure to water accommodated fraction of oil with 0.73 μg/L TPAH induced upregulation of cyp1a.•Embryo-larval survival of capelin are at risk if oil spills affect spawning areas.