Kristine Toxværd’s field experiments with crude oil were conducted using specially designed semi-open mesocosms deployed in sea ice at Svalbard. Photo: Line Reeh.

Oil spill affects Arctic plankton communities

Tuesday 14 Aug 18


Kirstine Toxværd
PhD Student
+45 20 97 14 76

Time & Place

22 August 2018, 1:00 p.m.

Building 303A, auditorium 44
2800 Kgs. Lyngby

The thesis

A copy of the thesis "Effects of oil spills on Arctic pelagic ecosystems - Winter exposure and variations in sensitivity" is available for reading at DTU Aqua. Please contact Rikke Hansen,

Microorganisms and copepods in the Arctic seas are negatively affected by oil spill, which may impact the entire marine food web, states new PhD thesis. On 22 August, the author, Kirstine Toxværd, will defend her thesis

The declining sea ice cover in the Arctic encourages exploration of the region’s abundant offshore oil and gas resources.

When oil activities in the Arctic are to be environmentally risk assessed, better biological background data is needed. In particular, data from the winter period is often insufficient. In her PhD thesis from DTU Aqua, Kirstine Toxværd contributes with new knowledge about the effect of oil spill on the arctic ecosystems in winter.

The thesis focuses on the effect of oil spill on phyto- and zooplankton with particular focus on the largest copepods, which form a key group in arctic ecosystems and are an important food source for fish, birds and mammals.

Kirstine Toxværd has investigated how oil spill in sea ice and technologies to remove oil spill affect plankton communities under the ice during winter and when the oil spill is released from the melting sea ice in spring. Her studies show that the use of chemical dispersants increases the concentration of oil under the sea ice and that this leads to a change in the structure and biomass of the microbial communities found under the ice, as well as deformed offspring among the copepods that are feeding on the microorganisms.

The PhD study also shows how the Arctic copepods overwintering under the sea ice to a much greater extent than previously assumed are affected by prolonged oil exposure and that it reduces their ability to rebuild fat reserves and reproduce in spring.

The PhD was conducted as an industrial PhD in collaboration with COWI. The experimental work has been carried out in Svalbard and in the laboratory at DTU Aqua.

About the thesis defence
Wednesday 22 August 2018, Kirstine Toxværd will defend her PhD thesis "Effects of oil spills on Arctic pelagic ecosystems - Winter exposure and variations in sensitivity". The defence takes place at 1:00 p.m. in auditorium 44, building 303A at DTU, Lyngby.


  • Principal supervisor: Professor Torkel Gissel Nielsen, DTU Aqua and PhD Morten Hjorth, COWI
  • Co-supervisor: PhD Steffen Brøgger-Jensen, COWI


  • Senior Researcher Sigrun Jonasdottir, DTU Aqua
  • Professor Jean-Eric Tremblay, Université Laval, Canada
  • Professor lngela Dahllof, University of Gothenburg, Sweden

Chairperson at defence

  • Senior Researcher Stefan Neuenfeldt, DTU Aqua