Multilevel responses of adult zebrafish to crude and chemically dispersed oil exposure

Abstract

Background The application of chemical dispersants is a common remediation strategy when accidental oil spills occur in aquatic environments. Breaking down the oil slick into small droplets, dispersants facilitate the increase of particulate and dissolved oil compounds, enhancing the bioavailability of toxic oil constituents. The aim of the present work was to explore the effects of water accommodated fractions (WAF) of a naphthenic North Sea crude oil produced with and without the addition of the chemical dispersant FINASOL OSR 52 to adult zebrafish exposed for 3 and 21 d. Fish were exposed to environmentally relevant concentrations of 5% and 25% WAFOIL (1:200) and to 5% WAFOIL+D (dispersant–oil ratio 1:10) in a semi-static exposure setup. Results The chemically dispersed WAF presented a 20-fold increase of target polycyclic aromatic hydrocarbons (PAHs) in the water phase compared to the corresponding treatment without dispersant and was the only treatment resulting in markedly bioaccumulation of PAHs in carcass after 21 d compared to the control. Furthermore, only 5% WAFOIL+D caused fish mortality. In general, the undispersed oil treatments did not lead to significant effects compared to control, while the dispersed oil induced significant alterations at gene transcription and enzyme activity levels. Significant up-regulation of biotransformation and oxidative stress response genes (cyp1a, gstp1, sod1 and gpx1a) was recorded in the livers. For the same group, a significant increment in EROD activity was detected in liver along with significant increased GST and CAT activities in gills. The addition of the chemical dispersant also reduced brain AChE activity and showed a potential genotoxic effect as indicated by the increased frequency of micronuclei in erythrocytes after 21 d of exposure. Conclusions The results demonstrate that the addition of chemical dispersants accentuates the effect of toxic compounds present in oil as it increases PAH bioavailability resulting in diverse alterations on different levels of biological organization in zebrafish. Furthermore, the study emphasizes the importance to combine multilevel endpoints for a reliable risk assessment due to high variable biomarker responses. The present results of dispersant impact on oil toxicity can support decision making for oil spill response strategies.

Zebrafish eye development and function is affected by crude oil exposure – line of evidence from underlying molecular effects to behavioral consequences

“…However, it might be possible that concentrations of the compounds driving toxicity were elevated in CEWAF due to the presence of the dispersant. Additionally, the composition of the PAH fraction might have been different as has been suggested in one previous study using a different chemical analysis strategy in LEWAF and CEWAF (Esteban-Sánchez et al, 2021). Nonetheless, the elevated toxicity in CEWAFs highlights the controversial nature of the application of dispersants as an oil spill response measure in the environment.…”

Zebrafish as Model Organism in Aquatic Ecotoxicology: Current Trends and Future Perspectives

“…Specifically, it aims to identify substances that lead to micronuclei forming acentric chromosome fragments or entire chromosomes [81]. Research data indicate that various substances, such as nanomaterials, metals, effluents, pesticides, pharmaceuticals, alkylating Zebrafish as Model Organism in Aquatic Ecotoxicology: Current Trends and Future Perspectives DOI: http://dx.doi.org/10.5772/intechopen.1002731 agents, steroids, hormones, minerals, and polycyclic aromatic hydrocarbons, exhibit mutagenic properties by inducing micronuclei formation in fish erythrocytes [82][83][84][85]. The comet assay, also known as single cell gel electrophoresis (SCGE) protocol, represents a widely used and well-established technique employed for the evaluation of DNA damage and DNA repair mechanisms.…”

Growth performance and condition factor of <i>Oreochromis niloticus</i> (Linneaus, 1758) after exposure to chemically dispersed Bonny Light crude oil

“…The possible toxic effects of dispersed oil in the water column on exposed organisms are of primary concern. Chemically dispersed crude oils are known to result in about a 20-fold increase of PAHs readily made bioavailable for uptake by exposed fish with deleterious effects (Ramachandran et al 2004;Fingas 2011;Lelei and Sikoki 2013;Mauduit et al 2016;Incardona 2017;Bejarano 2018;Chen et al 2018;Esteban-Sánchez et al 2021).…”

“…Dispersants are employed to mitigate spill situations despite their synergistic and deleterious effects (Lelei and Sikoki 2013;Chen et al 2018;Esteban-Sánchez et al 2021), to allow for recovery of the affected environments, as well as, the 'survivor-organisms.' It is pertinent to know how well the 'recovery-response' of exposed fish is.…”