Disputation: Kaixing Dong

PhD candidate Kaixing Dong at the Department of Biosciences will be defending the thesis "Bottom-up effects on plankton dynamics in Northeast Atlantic and Arctic seas" for the degree of PhD.

Profile picture of Kaixing Dong

Kaixing Dong. Photo: private.

The trial lecture is: "Assessing oceanic primary production: concepts, approaches and scales, with emphasis on high latitudes".

Time and place: June 10, 2022 10:15 AM, Nucleus, Bikuben, The Kristine Bonnevie building.

Main research findings

Marine phytoplankton play a vital role in serving as the ultimate base of the food web and fishery yields. Understanding how climate influences phytoplankton dynamics through changing environmental factors in high latitude marine ecosystems is important in order to understand and predict changes in ecosystem productivity and fishery yields. Therefore, this thesis aims to untangle environmental effects on plankton dynamics in Northeast Atlantic and Arctic seas, focusing on the response of phytoplankton to climatic variations. For this purpose, we linked satellite-derived chlorophyll data (the proxy of phytoplankton) to physical variables and zooplankton observations.

Contrary to our expectations, we found that higher sea surface temperature does not necessarily result in earlier onset of spring phytoplankton blooms in the open waters of the Northeast Atlantic. However, in the seasonally ice covered region in the Barents Sea, higher sea surface temperature was associated with earlier phytoplankton bloom with higher magnitude, probably because of earlier sea ice retreat under warmer conditions. Stepping up the food chain, we also investigated associations between the phytoplankton and the zooplankton that graze on them. Our results imply that a possible earlier phytoplankton bloom timing with future warming could benefit planktivorous fishes that feed on medium-sized zooplankton.

Adjudication committee

Dr. Laurent Oziel, Alfred Wegener Institute

Dr. Eva Leu, Akvaplan NIVA

Professor Tom Andersen, University of Oslo

Chair of defence

Professor emeritus Reidun Sirevåg, University of Oslo


Researcher Leif Christian Stige, University of Oslo

Researcher Kristina Øie Kvile, NIVA

Professor Nils Christian Stenseth, University of Oslo

Published May 27, 2022 11:43 AM - Last modified May 27, 2022 11:43 AM