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The application of chemical dispersants is one option of oil spill response (OSR). Here, Northern shrimp (Pandalus borealis) larvae were experimentally exposed for short periods (6 h and 1 h) to a realistic concentration of chemically dispersed oil (CDO) (~10 mg L -1 THC), mechanically dispersed oil (MDO) (~7 mg L -1 THC), and dispersant only (D). A control (C) with seawater served as reference. Short-term effects on survival and feeding were examined right after exposure and longer-term consequences on survival, feeding, growth and development following 30 days of recovery. Both exposure durations provoked long lasting effects on larval fitness, with 1 h exposure leading to minor effects on most of the selected endpoints. The 6 h exposure affected all endpoints with more adverse impacts after exposure to CDO. This study provides important data for assessing the best OSR option relevant to NEBA (Net Environmental Benefit Analysis)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Knowledge of key species sensitivity for oil spill response (OSR) options is needed to support decision-making and mitigate impact on sensitive life stages of keystone species. Here, Northern shrimp (Pandalus borealis) larvae were exposed for 24 h to a gradient (H-High, M-Medium: 10 times dilution and L-Low: 100 times dilution) of mechanically- (MDO) (H < 6 mg/L total hydrocarbon content) and chemically- (CDO) dispersed oil (Slickgone NS, H < 20 mg/L total hydrocarbon content), followed by a recovery period. Larval mortality, feeding rate and development were evaluated. Overall, the results show that 24 h exposure to field-realistic concentrations of CDO lead to lower survival, reduced feeding rate and slower larval development in P. borealis larvae compared to MDO. These effects persisted during recovery, indicating a higher vulnerability with dispersant use and the need for longer observation periods post-exposure to fully evaluate the consequences for sensitive life-stages from OSR., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Rising oil and gas activities in northern high latitudes have led to an increased risk of petroleum pollution in these ecosystems. Further, seasonal high UV radiation at high latitudes may elevate photo-enhanced toxicity of petroleum pollution to marine organisms. Zooplanktons are a key ecological component of northern ecosystems; therefore, it is important to assess their sensitivity to potential pollutants of oil and gas activity. As ontogenetic development may be particularly sensitive, the aim of this study was to examine the impact of chronic exposure to oil water dispersion (OWD) on development and feeding of early life stages of the Northern krill, Meganyctiphanes norvegica. In a range of experiments, embryonic, nonfeeding, and feeding larval stages were exposed to concentrations of between 0.01 and 0.1 mg/L of oil or photo-modified oil for 19 and 21 d. No significant effects on egg respiration, hatching success, development, length and larval survival were observed from these treatments. Similarly, evolution of fatty acid composition patterns during ontogenetic development was unaffected. The results indicates a high degree of resilience of these early developmental stages to such types and concentrations of pollutants. However, feeding and motility in later calyptopis-stage larvae were significantly impaired at exposure of 0.1 mg/L oil. Data indicate that feeding larval stage of krill was more sensitive to OWD than early nonfeeding life stages. This might be attributed to the narcotic effects of oil pollutants, their direct ingestion, or accumulated adverse effects over early development.

Abstract: Studies have shown that exposure to Polycyclic Aromatic Hydrocarbons (PAHs) and other oil related components alter normal fish larvae development and can cause increased mortality in early life stages. Modelling of results from controlled laboratory exposure experiments will help relate typical oil exposure parameters (biomarkers) to field observations and are valuable tools for oil exposure monitoring and risk assessment. Post yolk sack larval stages of Atlantic herring were exposed to different concentrations of dispersed Arctic crude oil. The selected nominal concentrations were 0.015, 0.040, 0.060, 0.250 and 0.750mgl−1 raw dispersed oil (0.129, 0.373, 0.496, 2.486 and 6.019μgl−1 Total Polycyclic Aromatic Hydrocarbons (TPAH) respectively), and control seawater in flow through systems. The larvae were exposed for 12days and daily mortality recorded in all treatments. Thereafter, the larvae were transported to two large (300l) rearing tanks, one for control/trace oil and one for oil exposed larvae. The larvae were allowed to recover for 8weeks after exposure, and mortality and morphological factors then assessed, giving preliminary information on recovery of Atlantic herring larvae after oil exposure. Throughout the testing period, there was a general trend for higher mortality of herring larvae in the oil exposure concentrations than in control, and significantly higher mortality was found in all oil concentrations than in the control after 12days. We did not detect a clear dose related mortality for our test concentrations, except for the highest concentration. There was no difference found in mortality rates of the herring larvae from either the oil or control/trace oil batch during the recovery phase during the following 60days. Morphological observations of the herring larvae after 2months recovery in clean seawater showed that the oil exposed larvae had morphological features that could be described as deformities, and growth was found to be significantly impaired for the oil exposed group when compared to the control/trace oil group. [Copyright &y& Elsevier]