| A crude oil spill along coastal California, particularly when spawning and developing fish are present, could potentially cause adverse population impacts. Currently, resource managers and oil spill responders require information on the relative toxicity of dispersed and un-dispersed oil, and their sublethal effects in wildlife, in order to make informed decisions regarding the use of chemical dispersants during spill events. Investigation of the damage hydrocarbons pose towards marine organisms is becoming more involved, particularly through the use of metabolomics, which has the potential to examine metabolic responses of organisms exposed to environmental and anthropogenic stressors.;The toxic effects of the water-accommodated fraction (WAF) and the chemically-enhanced WAF (CEWAF, with Corexit 9500) of Prudhoe Bay Crude Oil (PBCO) on adult and embryonic topsmelt (Atherinops affinis) and pre-smolt Chinook salmon (Oncorhynchus tshawytscha) was examined using NMR-based metabolomics. Based on resultant LC50 values, determined for both treatments, toxicity to both topsmelt and salmon decreased (i.e. less toxic) when Corexit 9500 dispersant was applied. However, NMR profiles and metabolic responses, for both fish species, were similar for both WAF and CEWAF, thus suggesting the fish were accumulating similar dissolved hydrocarbons at near similar concentrations.;To confirm this hypothesis, semi-permeable membrane devices (SPMDs), which specifically accumulate dissolved compounds from water, were used. SPMDs exposed to either WAF or CEWAF accumulated two- and three-ringed PAHs at concentrations differing by as little as 3-fold; however oil loadings differed by 8-fold. Thus it appears that similar hydrocarbon concentrations are eliciting the observed similar metabolic responses. Since SPMDs specifically target dissolved components, the variation among the previously measured LC 50 values is possibly due to the combined analysis of dissolved and particulate oil (as they are difficult to separate).;Overall, NMR-based metabolomics was successful in assessing the sublethal effects of petroleum hydrocarbons on topsmelt and salmon. More importantly, the metabolomics approach has led to confirmation that dissolved (bioavailable) hydrocarbon concentrations, those likely responsible for the toxic actions, are similar in both WAF and CEWAF. |
