Assessment of endocrine disruption in reproducing polar cod exposed to crude oil
1 Purpose
The main objective of this study is to assess the endocrine disruption potential of crude oil water-soluble compounds in maturing polar cod (Boreogadus saida). A special emphasis on transcriptomic changes within organs of the brain-pituitary-gonad-liver (BPGL) axis allows us to investigate altered pathways linked to reproductive success in an ecologically relevant artic fish species.
2 Distress
Adult polar cod will be exposed to a simulated oil spill (water-soluble fraction of crude oil) during three weeks at Havbrukstasjon i Tromsø. The levels of oil in the water will be so low that no visible effects are expected to be seen on the fish. The levels in questions will only be able to induce specific enzyme activities and metabolite production from the components bioavailable to the fish. After exposure the fish are kept in clean seawater until spawning. Over the duration of the experiment, fish are sampled at several occasions. Any sampling will be terminal and preceded by anaesthesia. We expect mild distress in fish during brief checks if the fish are ready to spawn (gentle pressure on abdomen without anaesthesia).
3 Expected benefit
This study helps to better understand the risk from accidental oil spills and has immediate relevance for ongoing debates on the drilling for oil in the Barents Sea. Specifically, we expect to gain knowledge on how the gamete quality is altered by parental exposure to crude oil and what are the underlying mechanisms of toxicity for the observed adverse reproductive outcomes. Overall, this research has implications for regulatory ecotoxicology and risk assessment for accidental oil spills in marine habitat as the generated data will contribute to the knowledge base for building sound population level models. The knowledge gained is highly relevant for the Barents Sea Integrated Management Plan.
4 Number of animals, and what kind
190 females and 190 males of adult polar cod (Boreogadus saida). Fish were previously sexed and tagged (Søknad: 25790).
5 How to adhere to 3R
Replace: There are no alternatives to study endocrine disruption and ultimately reproductive success in polar cod. In order to considering hormonal levels and transcriptome changes along the BPGL axis at specimen level we need to use the whole organism and cannot resort to alternative methods (e.g. cell cultures).
Reduce: The numbers of used animals is a minimum to guarantee successful sample collection from specimen during identical gonadal developmental stages, especially during spawning. Furthermore, we account for high variability in hormone levels and increased natural mortality during reproduction.
Refine: The experiment uses all available methods and knowledge to reduce discomfort in the organisms. The team has long experience in this type of set-up and uses levels of contaminant known to cause only cellular effects.
The main objective of this study is to assess the endocrine disruption potential of crude oil water-soluble compounds in maturing polar cod (Boreogadus saida). A special emphasis on transcriptomic changes within organs of the brain-pituitary-gonad-liver (BPGL) axis allows us to investigate altered pathways linked to reproductive success in an ecologically relevant artic fish species.
2 Distress
Adult polar cod will be exposed to a simulated oil spill (water-soluble fraction of crude oil) during three weeks at Havbrukstasjon i Tromsø. The levels of oil in the water will be so low that no visible effects are expected to be seen on the fish. The levels in questions will only be able to induce specific enzyme activities and metabolite production from the components bioavailable to the fish. After exposure the fish are kept in clean seawater until spawning. Over the duration of the experiment, fish are sampled at several occasions. Any sampling will be terminal and preceded by anaesthesia. We expect mild distress in fish during brief checks if the fish are ready to spawn (gentle pressure on abdomen without anaesthesia).
3 Expected benefit
This study helps to better understand the risk from accidental oil spills and has immediate relevance for ongoing debates on the drilling for oil in the Barents Sea. Specifically, we expect to gain knowledge on how the gamete quality is altered by parental exposure to crude oil and what are the underlying mechanisms of toxicity for the observed adverse reproductive outcomes. Overall, this research has implications for regulatory ecotoxicology and risk assessment for accidental oil spills in marine habitat as the generated data will contribute to the knowledge base for building sound population level models. The knowledge gained is highly relevant for the Barents Sea Integrated Management Plan.
4 Number of animals, and what kind
190 females and 190 males of adult polar cod (Boreogadus saida). Fish were previously sexed and tagged (Søknad: 25790).
5 How to adhere to 3R
Replace: There are no alternatives to study endocrine disruption and ultimately reproductive success in polar cod. In order to considering hormonal levels and transcriptome changes along the BPGL axis at specimen level we need to use the whole organism and cannot resort to alternative methods (e.g. cell cultures).
Reduce: The numbers of used animals is a minimum to guarantee successful sample collection from specimen during identical gonadal developmental stages, especially during spawning. Furthermore, we account for high variability in hormone levels and increased natural mortality during reproduction.
Refine: The experiment uses all available methods and knowledge to reduce discomfort in the organisms. The team has long experience in this type of set-up and uses levels of contaminant known to cause only cellular effects.