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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.)

Hydrogen peroxide (H 2 O 2 ) is used as anti-parasitic veterinary medicine in salmon farms worldwide. In the period from 2009 to 2018 a total of 135 million kg of H 2 O 2 was used in Norway, the world's largest producer of Atlantic salmon. Since the treatment water is discharged to the sea, concerns have been raised about effects of H 2 O 2 on the coastal ecosystem. In the present study, Northern shrimp (Pandalus borealis) have been exposed to short pulses of H 2 O 2 in the PARAMOVE ® formulation, followed by a recovery period in clean seawater. The exposure concentrations represented 100, 1000 and 10 000 times dilutions of the prescribed treatment concentration for salmon; 15 mg/L, 1.5 mg/L and 0.15 mg/L H 2 O 2 . Significantly increased mortality was observed after 2 h exposure to 15 mg/L H 2 O 2 (50%) and after 2 h exposure to 1.5 mg/L H 2 O 2 on 3 consecutive days (33%), but no mortality was observed after 2 h exposure to 0.15 mg/L. The mortality occurred 2-4 days after the first pulse of exposure. The patterns of acute effects (immobility and death) could be captured with a toxicokinetic-toxicodynamic model (GUTS), which allows extrapolations to LC50s for constant exposure, or thresholds for effects given untested exposure profiles. Effects of H 2 O 2 were also detected in shrimp that survived until the end of the recovery period. The feeding rate was 66% lower than in the control after 12 days of recovery for the three-pulse 1.5 mg/L exposure. Furthermore, dose dependent tissue damage was detected in the gills and evidence of lipid peroxidation in the hepatopancreas in shrimp exposed for 1 h to 1.5 mg/L and 15 mg/L and kept in recovery for 8 days. Fluorescence intensity in the hepatopancreas of treated shrimp increased 47% and 157% at 1.5 mg/L and 15 mg/L, respectively, compared to the control. Local hydrodynamic conditions will determine how fast the concentration of H 2 O 2 will be diluted and how far it will be transported horizontally and vertically. Results from dispersion modelling (literature data) together with the current experiments indicate that treatment water with toxic concentrations of H 2 O 2 (1.5 mg/L) could reach P. borealis living more than 1 km from a treated salmon farm., (Copyright © 2019 The Authors. Published by Elsevier Inc. 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.)