PhD trial lecture and defence: Marina Espinasse

15 December 2017 10:00 - 15 December 2017 15:30

Auditorium Petter Thomassen (A5)

PhD candidate Marina Espinasse will hold a trial lecture and defend her thesis for the degree Philosophiae Doctor (PhD), at the Faculty of Biosciences and Aquaculture, Nord University.

Phd candidate: Marina Espinasse

Title of thesis:
Interannual variability in key zooplankton species in the North-East Atlantic: an analysis based on abundance and phenology 

Title of trial lecture:
Top down effects on phenology and interannual variation in zooplankton populations

Time of trial lecture: 10:15 - 11:15
Time of defence: 12:15 - 15:30
Place: Auditorium Petter Thomassen (A5)

Members of the evaluation committee:
Senior researcher Eva Friis Møller, Aarhus University, Aarhus, Denmark 
- Researcher Nicolas Dupont, CEES Department of Biosciences, University of Oslo 
Professor Jarle Tryti Nordeide, FBA, Nord   university (leader).

Main supervisor: Professor Ketil Eiane, FBA
- Senior researcher Claudia Halsband, Akvaplan niva, Tromsø
- Senior researcher Øystein Varpe, Akvaplan niva, Tromsø

The PhD trial lecture and defence are open to the public. The thesis is available on request. Please contact Jeanett Stegen, email:, phone: 75 51 74 49 

About the thesis:
The North Atlantic is an economically important marine area. Therefore, a great research effort is directed to understand the ecosystems functioning in this region and predict their possible changes under climate fluctuations in the Northern Hemisphere. 

One of the key species targeted by the research of the North Atlantic is zooplankton of the genus Calanus.

is the crucial element of the North Atlantic and sub-Arctic marine ecosystems, because it is an essential food source for economically important fish species such as herring, capelin, and young stages of Atlantic cod. Calanus however, is sensitive to changes in its environment and may considerably decrease in abundance under unfavourable conditions.

Marina Espinasse has undertaken a comprehensive analysis of the data-series on Calanus abundances originating from the fjord in northern Norway, Western Svalbard shelf, northern Icelandic waters and the White Sea, Russia. She studied long-term fluctuations in Calanus abundance and identified major environmental factors that drive abundance variability. 

In addition, she analysed changes in Calanus seasonal development between the study locations and suggested viable approaches to study seasonal cycle of Calanus when only limited data-sets are at hand.

The results of the thesis suggest that large-scale climate affects most of Calanus populations in the North-East Atlantic, but these effects are mediated by local environmental factors such as transport of water masses, temperature and phytoplankton production. 

For the seasonal development of Calanus, temperature appears to be a critical factor, while climate effects differ with the developmental stage of the species. 

This research represents a valuable contribution to the knowledge of zooplankton population dynamics, and consequently, enhance the understanding of the pelagic marine ecosystems.