MSc in Environmental Sciences Claudia Erhart at the Department of Arctic and Marine Biology (AMB) will Thursday 21 May 2026 hold her trial lecture and defend her thesis for the PhD degree in Natural Science.
Trial lecture on assigned topic will take place at 10.15: "Consequences of climate change on effects of oil pollution on Arctic fish populations"
Later, at 12.15 she will defend her thesis entitled: "From Parent to Progeny: Reproductive and intergenerational effects of crude oil exposure in key fish species in the Barents Sea"
Professor Monica Alterskjær Sundset at AMB will lead the disputation.
Popular Science Summary
Oil is still a major part of the world’s energy supply, and demand may remain high for decades. New oil fields are also being developed in northern regions such as the Barents Sea. While these projects bring economic benefits, they also increase the risk of accidental oil spills in sensitive Arctic marine ecosystems. Scientists already know that fish eggs and larvae are very sensitive to oil pollution. But we still know relatively little about how oil exposure might affect adult fish during important processes such as reproduction or whether it can influence their offspring.
This thesis studied how exposure to crude oil in water affects reproduction in two important Barents Sea fish species: Atlantic cod (Gadus morhua) and polar cod (Boreogadus saida). Adult fish were kept in tanks with water containing small amounts of oil before they were ready to spawn.
The results showed that fish that came in contact with oil compounds started spawning earlier than normal. In polar cod, this earlier spawning happened even though the fish otherwise seemed healthy. Their reproductive organs looked normal, and egg fertilization and sperm performance were not affected. But, changes in hormones levels were found. This means that oil compounds can disturbed the complex system that controls reproduction.
Effects were also seen in the next generation. Exposed Atlantic cod mothers had smaller eggs, which contained oil compounds. These embryos showed changes in important genes needed for early development, and depending on the timing of egg collection more embryos from exposed mothers died. Effects in offspring from exposed fathers were seen after hatch, as larvae mortality increased.
These results show that crude oil in water can shift when fish reproduce and reduce the survival of their offspring. These effects across generations could affect fish populations over time. Considering such long-term effects is therefore important when assessing the environmental risks of oil activity in Arctic seas.
Evaluation Committee
Supervisors
Streaming
Both the trial lecture and defense and will be streamed and recorded:
Thesis
The thesis is available in Vitenarkivet