Biological Responses of Pacific Herring Embryos to Crude Oil Are Quantifiable at Exposure Levels Below Conventional Limits of Quantitation for PAHs in Water and Tissues

Abstract

Pacific herring (Clupea pallasii), a cornerstone of marine food webs, generally spawn on marine macroalgae in shallow nearshore areas that are disproportionately at risk from oil spills. Herring embryos are also highly susceptible to toxicity from chemicals leaching from oil stranded in intertidal and subtidal zones. The water-soluble components of crude oil trigger an adverse outcome pathway that involves disruption of the physiological functions of cardiomyocytes in the embryonic herring heart. In previous studies, impaired ionoregulation (calcium and potassium cycling) in response to specific polycyclic aromatic hydrocarbons (PAHs) corresponds to lethal embryolarval heart failure or subtle chamber malformations at the high and low ends of the PAH exposure range, respectively. Sublethal cardiotoxicity, which involves an abnormal outgrowth (ballooning) of the cardiac ventricular chamber soon after hatching, subsequently compromises juvenile heart structure and function, leading to pathological hypertrophy of the ventricle and reduced individual fitness, measured as cardiorespiratory performance. Previous studies have not established a threshold for these sublethal and delayed-in-time effects, even with total (∑)­PAH exposures as low as 29 ng/g of wet weight (tissue dose). Here, we extend these earlier findings showing that (1) cyp1a gene expression provides an oil exposure metric that is more sensitive than typical quantitation of PAHs via GC–MS and (2) heart morphometrics in herring embryos provide a similarly sensitive measure of toxic response. Early life stage injury to herring (impaired heart development) thus occurs below the quantitation limits for PAHs in both water and embryonic tissues as a conventional basis for assessing oil-induced losses to coastal marine ecosystems.

High-Efficiency Effect-Directed Analysis Leveraging Five High Level Advancements: A Critical Review

“…For example, an in vivo bioassay using Pacific herring to detect sublethal cardiotoxicity can be utilized to evaluate the health of coastal marine ecosystems in EDA. 187 The current focus of biological assessments on acute toxicity needs to be expanded to include chronic toxicity, for which EDA could be valuable in establishing a connection between environmental contaminants, ecological safety, and chronic diseases. Fourth, harmonizing the HRMS instrument configuration is crucial.…”

“…Moreover, developing sensitive testing models closely related to adverse health outcomes and creating multilevel endpoints (i.e., tissue or organ level), establishing a bridge between the chemicals and target toxicity endpoints. For example, an in vivo bioassay using Pacific herring to detect sublethal cardiotoxicity can be utilized to evaluate the health of coastal marine ecosystems in EDA . The current focus of biological assessments on acute toxicity needs to be expanded to include chronic toxicity, for which EDA could be valuable in establishing a connection between environmental contaminants, ecological safety, and chronic diseases.…”