On 23 October 2020, Sieme Bossier, DTU Aqua will defend her PhD thesis. The defence can be watched online.
The Baltic Sea is exposed to several pressures and human impacts, including nutrients flowing out from land, fishing and climate change. In her PhD study, Sieme Bossier has investigated how these pressures will impact the marine ecosystem with specific focus on key fish stocks.
Achieving a good environmental status in the complex Baltic Sea region requires holistic and cross disciplinary scientific support tools to compare alternative fisheries management strategies and to compare the responses of fish and fisheries to changing climatic conditions and nutrient load.
To study this, Sieme Bossier and her colleagues have applied a comprehensive mathematical model, called the Baltic Atlantis. This end-to-end whole-of ecosystem model is a holistic ecosystem model which explores climate, eutrophication, fishery and spatial management scenarios and incorporates the dynamics of the whole Baltic Sea ecosystem. Additionally, the researchers have used the RCO-SCOBI biogeochemical climate model to enable projections of future climate change and eutrophication.
In her thesis, “Evaluating Major Baltic Fish Stocks under Climate, Eutrophication and Fishing Pressure using a Holistic end-to-end Ecosystem Model”, Sieme Bossier concludes that the results of the research indicate that excess nutrient loads is the main driver of the changes in the ecosystem. For the main fish stocks, this results in a decrease in cod and an increase in sprat and herring under high nutrient load levels.
However, in the longer run climate change will have a stronger impact on the ecosystem than eutrophication, once minimum oxygen or salinity levels or maximum temperature levels required for fish to spawn are exceeded.
However—the thesis also states—it is difficult to determine the exact effect of climate change and eutrophication and their combined effect because of the uncertainties surrounding the climate model projections.
About the defence
Sieme Bossier will defend her PhD thesis "Evaluating Major Baltic Fish Stocks under Climate, Eutrophication and Fishing Pressure using a Holistic end-to-end Ecosystem Model" on Friday 23 October 2020 at 13:30 via Zoom.
Supervisors
- Principal supervisor: Professor J. Rasmus Nielsen, DTU Aqua
- Co-supervisor: Senior Researcher Stefan Neuenfeldt, DTU Aqua
- Co-supervisor: Senior Researcher Asbjørn Christensen, DTU Aqua
- Co-supervisor: Senior Researcher Francois Bastardie, DTU Aqua
Examiners
- Senior Researcher Margit Eero, DTU Aqua
- Researcher Marie Savina-Rolland, IFREMER, France
- Researcher Cecilie Hansen, Institute of Marine Research, Norway
Chairperson at defence
- Professor Brian MacKenzie, DTU Aqua
Registration
Please register for the Zoom meeting no later than 22 October at 14:00 by e-mail to Karin Stubgaard, stub@aqua.dtu.dk. You will receive an e-mail with a link to Zoom on the day before the defence.
Learn more
A popular science summery of the thesis can be downloaded here
A copy of the thesis is available for reading at the Institute. Please contact Karin Stubgaard, stub@aqua.dtu.dk