Forsøksdyr: Pulsed exposure of Northern shrimp (Pandalus borealis) to salmon lice treatments

Godkjenningsdato 02.02.2018

It is important to find out if discharges of salmon treatment water can explain the losses of shrimp, and in particular egg carrying females, from fishing areas, as reported by Norwegian coastal fishermen. The proposed experiments will provide valuable new information about how a keystone species in the marine ecosystem, the commercially and culinary important northern shrimp (Pandalus borealis) responds to three chemicals used as medicine against salmon lice in Norwegian aquaculture. It is also important to test the sensitive early life stages (larvae) when determining the risk of contaminants to the environment. Increased mortality of early life stages may increase the risk of recruitment failure.
We will test the commercial medicines: AlphaMax (a.i.deltamethrin, DEL), Paramove (a.i. hydrogen peroxide, H2O2) and Releeze medicated feed, DIF (a.i Diflubenzuron). Moderate stress to the shrimp may be expected during the procedures. The experiments will focus on the effects of treatments on egg carrying female shrimp and larvae. Combined effects of anthropogenic and natural stressors will also be investigated, low food levels (natural stress) will be investigated in the recovery period to see if it will have the same effect on larvae that survive 14 days pulsed exposure as control larvae. Concentrations used in the proposed experiments are based on experiments done in spring 2017 and a series of experiments using multiple pulse exposures of shrimp to the three chemicals will take place. No more than 460 adult shrimp and 3360 larvae will be used throughout the entire run of experiments. There are currently no effective replacement methods available to avoid the use of shrimp in this complex experimental investigation. The minimum number of shrimp required to achieve acceptable statistical strength will be used. Surviving non-exposed control shrimp will be returned to the fjord at the end of the experimental procedures. Endpoints at different levels of biological organization will be studied in adult females and larvae during the pulsed exposures and recovery periods. The spring 2017 experiments documented gill damage of shrimp exposed to1.5 mg/L or 15 mg/L H2O2 for one hour (Arnberg et al. 2017). In the new experiments a longer recovery period in clean water will be included to investigate if shrimp are able to recover from the moderate gill damage observed at 1.5 mg/L – and if combined exposure makes it worse? At the end of the recovery period, tissue damage in the gills and hepatopancreas will be investigated in order to assess long-term effects of oxidative stress (Mezzasalima, et al. 2008).
Investigation of swimming behavior and immobilization is relevant for the DEL and for H2O2 exposures, as these compounds affected behavior in 2017 experiments. In the completed RCN#234407 project FluClim, we documented high mortality during moulting for shrimp exposed to Releeze medicated feed containing DIF. Therefore, larvae will be followed through their first three moults.

Maj Arnberg, Alessio Gomiero, Stig Westerlund, Emily Lyng, Mark Berry, Frederike Keitel-Gröner, Thorleifur Agustsson & Renée K. Bechmann. Sensitivity of shrimp to short pulses of Paramove® (hydrogen peroxide). IRIS REPORT – 2017/196