Forsøksdyr: PLASTICOD Juveniles- Transfer of microplastic contaminants in Atlantic cod juveniles; 2020 trial

Godkjenningsdato 17.07.2020

Godkjenningsperiode 15.08.2020-31.12.2020

1 Purpose
The purpose of this experiment is to increase our knowledge regarding potential uptake of hydrophobic contaminants bound to microplastic spheres that are typically found in Norwegian coastal areas.

2 Distress
Feeding cod with microplastic containing diets with and without contaminants is expected to cause minor and non-lethal alterations in physiology, histology and in gene expressions. Microplastic spheres may itself affect the digestive tract and digestion and the proportion of microplastic in feed will be kept very low (1%). The MP size selected is well above that which has been shown to be absorbed in the intestine. The MP size is also so small that they will not clog the digestive tract (“the plastic whale”) but rather pass along with the rest of the digesta. The levels of PCB in the microplastic used represent realistic levels found in plastic samplers in the sea in Norwegian waters in this project

3 Expected benefit
The results will provide an understanding of what role microplastic plays in transferring contaminants through the food chain. This will provide a better background for management and policy making in the future.

4 Number of animals, and kind.
The trial will include a total number of 450 Atlantic cod (Gadus morhua) juveniles.

5 How to adhere to 3R
Replacement cannot be totally achieved. The transfer of pollutants from microplastic to the living organism can only be studied in-vivo. However, to significantly reduce the necessary trials in the project, we conduct pure chemical laboratory trials where sorption-desorption kinetics of contaminants from MP are studied. These results provide basic data for improving the existing in-silico models that is also being developed as part of the project. These data sets and models have significantly reduced the number of trials that are required with live fish and the current application deals only with one final trial to conclude the findings

Reduction is achieved by ensuring that the number of animals in this experiment corresponds to the required sample mass for the relevant chemical and statistical analysis. We need to secure sufficient tissue for each of the methods and that require pooling from up to 45 individuals. The number also reflect the size of the tank used to have a fish density that give optimal fish welfare and prevent hierarchic behavior in the tanks.

Refinement is achieved by daily monitoring and removing animals showing signs of abnormal behavior, deformities and reduced weight etc.