Modeling the toxicity of dissolved crude oil exposures to characterize the sensitivity of cod (Gadus morhua) larvae and role of individual and unresolved hydrocarbons

Following an oil spill, accurate assessments of the ecological risks of exposure to compounds within petroleum are required, as is knowledge regarding how those risks may change with the use of chemical dispersants. Laboratory toxicity tests are frequently used to assess these risks, but differences in the methods for preparation of oil‐in‐water solutions may confound interpretation, as may differences in exposure time to those solutions. In the present study, we used recently developed modifications of standardized ecotoxicity tests with copepods (Acartia sinjiensis), sea urchins (Heliocidaris tuberculata), and fish embryos (Seriola lalandi) to assess their response to crude oil solutions and assessed whether the oil‐in‐water preparation method changed the results. We created a water‐accommodated fraction, a chemically enhanced water‐accommodated fraction, and a high‐energy water‐accommodated fraction (HEWAF) using standard approaches using two different dispersants, Corexit 9500 and Slickgone NS. We found that toxicity was best related to total polycyclic aromatic hydrocarbon (TPAH) concentrations in solution, regardless of the preparation method used, and that the HEWAF was the most toxic because it dispersed the highest quantity of oil into solution. The TPAH composition in water did not vary appreciably with different preparation methods. For copepods and sea urchins, we also found that at least some of the toxic response could be attributed to the chemical oil dispersant. We did not observe the characteristic cardiac deformities that have been previously reported in fish embryos, most likely due to the use of unweathered oil, and, as a consequence, the high proportion of naphthalenes relative to cardiotoxic polycyclic aromatic hydrocarbon in the overall composition. The present study highlights the need to characterize both the TPAH composition and concentration in test solutions when assessing oil toxicity. Environ Toxicol Chem 2022;41:2580–2594. © 2022 SETAC

Section: Discussionmentioning

confidence: 99%

The Influence of Oil‐in‐Water Preparations on the Toxicity of Crude Oil to Marine Invertebrates and Fish Following Short‐Term Pulse and Continuous Exposures

Hook

Strzelecki

Adams

et al. 2022

“…The myriad of compounds that make up crude oil render it problematic to characterize the toxicity of every one, and a wide variety of environmental, physical, and biological factors can have extreme influence on how the compounds interact with one another and with the test organism (Wang et al, 2021). Predictive models have become more popular in the last decade (Carroll & Smit, 2011; Hansen et al, 2019; McGrath et al, 2018) and are a promising approach to addressing this issue.…”

Section: Discussionmentioning

confidence: 99%

A Critical Review of the Availability, Reliability, and Ecological Relevance of Arctic Species Toxicity Tests for Use in Environmental Risk Assessment

Eldridge

Jourdan

Hanson

2021

There is a pressing need to understand the impact of contaminants on Arctic ecosystems; however, most toxicity tests are based on temperate species, and there are issues with reliability and relevance of bioassays in general. Together this may result in an underestimation of harm to Arctic organisms and contribute to significant uncertainty in risk assessments. To help address these concerns, a critical review to assess reported effects for these species, quantify methodological and endpoint relevance gaps, and identify future research needs for testing was performed. We developed uniform criteria to score each study, allowing an objective comparison across experiments to quantify their reliability and relevance. We scored a total of 48 individual studies, capturing 39 tested compounds, 73 unique Arctic test species, and 95 distinct endpoints published from 1975 to 2021. Our analysis shows that of 253 test substance and species combinations scored (i.e., a unique toxicity test), 207 (82%) failed to meet at least one critical study criterion that contributes to data reliability for use in risk assessment. Arctic-focused toxicity testing needs to ensure that exposures can be analytically confirmed, include environmentally realistic exposure scenarios, and report test methods more thoroughly. Significant data gaps were identified as related to standardized toxicity testing with Arctic species, diversity of compounds tested with these organisms, and the inclusion of ecologically relevant sublethal and chronic endpoints assessed in Arctic toxicity testing. Overall, there needs to be ongoing improvement in test conduction and reporting in the scientific literature to support effective risk assessments in an Arctic context.

“…The higher sensitivity to MGO and IFO 180 than to SAB is likely driven by the proportions of F1 and F3 fractions in these WAFs, due to both the acute toxicity of monoaromatics and the greater toxicity and persistence of heavier PAHs present. The lower molecular weight aromatics, including benzene, toluene, ethylbenzene, and xylene compounds and naphthalenes, can be the main contributors to toxicity of petroleum WAFs due to their high solubility in seawater and rapid uptake by organisms (Landrum et al 1996; Barron et al 2004; Gardiner et al 2013; Hansen et al 2019). However, the contribution of heavier hydrocarbons at lower concentrations to overall toxicity can be orders of magnitude greater than that of lighter aromatic compounds (Di Toro et al 2007; Engraff et al 2011).…”

Section: Discussionmentioning

confidence: 99%

Impacts of Petroleum Fuels on Fertilization and Development of the Antarctic Sea Urchin Sterechinus neumayeri

Brown

King

Harrison

2020

Antarctic marine environments are at risk from petroleum fuel spills as shipping activities in the Southern Ocean increase. Knowledge of the sensitivity of Antarctic species to fuels under environmentally realistic exposure conditions is lacking. We determined the toxicity of 3 fuels, Special Antarctic Blend diesel (SAB), marine gas oil (MGO), and intermediate fuel oil (IFO 180) to a common Antarctic sea urchin, Sterechinus neumayeri. Sensitivity was estimated for early developmental stages from fertilization to the early 4-arm pluteus in toxicity tests of up to 24 d duration. The effects of the water accommodated fractions (WAFs) of fuels were investigated under different exposure scenarios to determine the relative sensitivity of stages and of different exposure regimes. Sensitivity to fuel WAFs increased through development. Both MGO and IFO 180 were more toxic than SAB, with median effect concentration values for the most sensitive pluteus stage of 3.5, 6.5, and 252 µg/L total hydrocarbon content, respectively. Exposure to a single pulse during fertilization and early embryonic development showed toxicity patterns similar to those observed from continuous exposure. The results show that exposure to fuel WAFs during critical early life stages affects the subsequent viability of larvae, with consequent implications for reproductive success. The sensitivity estimates for S. neumayeri that we generated can be utilized in risk assessments for the management of Antarctic marine ecosystems.