Plankton - Change in phytoplankton community in the inner Oslofjord during a century of sampling

Phytoplankton community in the Oslofjorden dominated by diatoms. Photo: Vladyslava Hostyeva. 


Phytoplankton composition, abundance and production undergo steady changes through the season in Norwegian coastal waters driven by various physicochemical and biological factors. Long-term changes can also be caused by climate change and human activities. Phytoplankton are the basis for higher trophic levels in the ocean and thus for the fisheries. Phytoplankton communities react rapidly to changes due to fast growth and are sensitive indicators of marine ecosystem status. Phytoplankton composition and abundance are thus a common parameter in monitoring of marine environments.

About the project

In this project we will study long-term time-series of phytoplankton counts and diversity in the inner Oslofjorden. Such time-series of species composition and abundance are essential in understanding the natural seasonal and interannual variability and possible future scenarios and thereby important for long-term management. In the project we will analyse data sampled and produced over the last 100 years. Based on analysis of changes and possible causes for changes in the phytoplankton community the outcome will be prediction of future effects and improvements of monitoring- and management strategies.


Investigate patterns and long-term changes in the phytoplankton community in the inner Oslofjord and possible driving forces and predictions.

•    Have the phytoplankton community composition, relative abundance and phenology changed?
•    If so, in what way?
•    Can we relate changes to nutrient levels or to hydrographic conditions?
•    Can we model and predict possible future changes and consequences of these changes?
•    What are the strengths and weaknesses of todays methodology for monitoring the marine ecological status by phytoplankton data ? How should we do it in the future?


This project will contribute to improve the monitoring and management of the water quality in the inner Oslofjorden.


  • Study historic phytoplankton data to reveal seasonal patterns, inter-annual variability and longterm trends in the composition and abundance of taxonomic groups and species
  • Explore environmental factors and anthropogenic activities as driving forces for the phytoplankton structure 
  • Further develop a monitoring strategy for the future based on phytoplankton composition and abundance


RCN - (Research Council of Norway, Nærings-PhD)

Tags: Nærings-PhD, planteplankton, Oslofjorden, overvåking
Published Jan. 6, 2017 6:10 PM - Last modified July 31, 2019 6:03 PM


Elisabeth Lundsør

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