Siri Eline Ofstad

Title of the PhD thesis:

«Arctic planktonic calcifiers in a changing ocean - A study on recent planktonic foraminifera and shelled pteropods in the Fram Strait-Barents Sea region»

Popular scientific abstract:

The Arctic is changing. Small organisms (planktonic foraminifera and shelled pteropods) in the water column were studied in terms of their abundance, seasonality, diversity, life cycles, and calcification. This was done by collecting samples with a plankton net and collecting water and surface sediments. This thesis has shown that the Fram Strait-Barents Sea region is characterized by low species diversity and marked seasonality. We found a decrease in the relative abundance of the polar species N. pachyderma on the Greenland shelf compared to the 1990s, and sub-tropical species in the Barents Sea. This thesis has helped in filling gaps in research into the impacts of ocean acidification in the Arctic. Lastly, we have been able to show that organisms in the same size class and water depth have a wide range of shell densities which is also true for foraminifera in surface sediments. These two points may complicate geochemical or ocean acidification studies as well as paleo-studies

The thesis is published and available in Munin.

Supervisors:

• Professor Tine L. Rasmussen, Department of Geosciences, UiT (main supervisor)
• Researcher Katarzyna Zamelczyk, Department of Geosciences
• Dr. Julie Meilland, Marum, University of Bremen

Evaluation Committee:

• Professor Ulysses Ninnemann, Department of Geosciences, UiB, Norway (1. Opponent)
• Senior Research Scientist Dr. Clara Manno, British Antarctic Survey, UK (2. Opponent)
• Researcher Dr. Mohamed M. Ezat, Department of Geosciences, UiT (internal member and leader of the evaluation committee)

Leader of the public defence:

Professor Alfred Hanssen, Vice Dean for Research and Innovation, Faculty of Science and Technology, UiT, will lead the public defence.

Trial lecture:

Siri Eline Ofstad will hold her trial lecture for the PhD degree in Science on 16 December at 10.15 in the same auditorium. The topic of her trial lecture is:

«The role of marine calcifiers in the ocean carbon and carbonate pumps; past, present, and future»

The trial lecture and the public defence will be streamed from this link.

Audience:

UiT follows the national guidelines regarding infection control. A maximum of 20 people are allowed in the auditorium during the defence, as long as everybody keeps a distance of 1 meter at all times.