Research Interests

Management of natural ecosystems:

  • - Structure and functioning of planktonic ecosystems
  • - Eutrophication
  • - Disinfection of ballast water

Management of engineered ecosystems:

  • - Biological water treatment
  • - Biofilm formation and fouling
  • - Seaweed Biorefinery systems
  • - Oil pollution and degradation


  • - Host/microbe interactions in fish
  • - Microbial management of marine fish larvae
  • - Water quality in aquaculture 


  • - Sources of biofuel
  • - Production of biogas


 Management of natural ecosystems:

Structure and functioning of planktonic ecosystems

Key words: Food web interaction, stability, omnivory, limiting factors, predation.

This research involves several groups at NTNU, started in limnetic systems, but is now focused on marine systems. All functional groups of plankton have been studied, and research has been funded by the Research Council of Norway and some smaller agencies. A large number of master and dr students have been educated within the field, and partly with international collaboration (CSIC, Spain; Leibnitz Int Mar Sci, Germany; Univ München, Germany, Finnish Environment Institute, Finland).

Ongoing activity is related to limiting factors for heterotrophic bacteria in Arctic waters (partly financed by The Norwegian Svalbard Society) and ecological effects of harvesting zooplankton (cooperation with Dept Biology and Inst Marine Research, Bergen, and financed by the Research Council of Norway). [back to top]



Key words: Nitrogen and phosphorus loading, biological responses, ecosystem experiments.

The work is strongly linked to the work on "Structure and functioning of planktonic ecosystems", by its focus on plankton and on biological mechanisms of significance for the ability of the plankton to manage nutrient loading. The link also relates to international cooperation and to funding. We have also been involved in an EU funded project, COMWEB, on marine eutrophication.

Ongoing activities are mainly related to publication of results from previous projects, and include data from a five-year full scale eutrophication in the land-locked bay Hopavågen. [back to top]


Disinfection of ballast water

Key words: Disinfection, substrate mobilization, recolonization, ecological consequences.

The work is related to the Ballast Water Project, and involves the activity of one PhD student and Master student. The focus is on microbes in ballstwater and with emphasize on prokaryotes. The following topics are highlighted: 1) The significance of biotic and abiotic particles as refuges against disinfection agents. 2) The impact of disinfection for production of easily degradable substrate for heterotrophic bacteria. 3) Recolonization kinetics by heterotrophic bacteria after disinfection. The project is funded by VISTA, which is Statoil's basic research programme which is conducted in close collaboration with the Norwegian Academy of Science and Letters. [back to top]


Management of engineered ecosystems:

Biological water treatment

Key words: Nutrient removal, EBPR, nitrification, gel entrapment, process water.

Enhanced biological phosphorus removal EBPR and P sludge analysis related to Swedish NUTEKs STAMP program was combined with denitrification at full scale UCT and in lab. Gel entrapped nitrification project "New immobilization techniques for biological wastewater treatment" (NFR) supported one PhD 1999. Fluorescence in situ hybridization FISH applied to quantify nitrifying community dynamics modelled by cellular automata. Gel technology also includes studies of freezing / drying for long-term storage and reactivation, as well as developing gel microbeads for superactive airlift reactors.

Current activities focus on molecular techniques to analyze nitrifying communities at high salinities, related to nitrifying biofilms applied in recycled marine aquaculture. Also, total N removal from process water after post-combustion CO2 capture by amine absorption is investigated in cooperation with Sintef Process Technology .

Related Master projects have been performed at Department of Civil and Environmental Engineering NTNU, Hydro Research Center Porsgrunn, Lunds University, TU Delft (including Anammox) and University of Nijmeegen. [back to top]


Biofilm formation and fouling

Key words: Chitosan, flocculation, adhesion, non-solid surfaces, hydrogels, marine biofouling.

Activity based on earlier NTNF projects, leading to projects "Biopolymers in biofilm and flock formation" (NFR/Jotun) with one PhD finishing 2001, and "Marine Biofouling" (Jotun/NFR) with one PhD in 2002. While polycation-cell interaction studies have concentrated on chitosans, marine biofouling include microbial adhesion to gel surfaces as well as development of suitable controlled shear test systems for fouling-release regimes on low energy surfaces LES.

Related Master projects have also been performed at TU Delft, Montana State University Bozeman and at Florida Institute of Technology FIT supported by Jotun. [back to top]


Seaweed Biorefinery Systems

Key words: Marine primary biomass, seaweeds, alginate, hydrolysis, composting, biogas production, ethanol production.

According to Wikipedia, a biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, heat, and value-added chemicals from biomass. Seaweeds and their utilization constitute an essential part of this Department's cultural heritage, as a direct descendant of the former Norwegian Institute of Seaweed Research (NITT) founded in 1949.

Previous seaweed biomass degradation and fermentation research led to successful studies of fertilizer applications of fermentate. NFR supported studies on seaweed biotechnology devoted to developing methods for protoplast and callus tissue culture have formed the basics of understanding selective enzymatic degradation. Further studies have
concentrated on kelp and other common brown algae, in NFR projects on "Biodegradation of Norwegian brown seaweeds" (Pronova/NFR) supporting one PhD 1997 and "Energy from macroalgae" (Hydro/NFR) supporting one PhD 2000. Recent2009-cooperation with Sintef Biotechnology is further developing biofuel production, see below. Also, a multitude of projects and Master students has successfully continued this work.

Based on this experience, it is our firm belief that the biorefinery approach is the key factor to sustainable seaweed utilization for the future. It is our intention to participate in this development. [back to top]


Oil pollution and degradation

Key words: Crude oil, pollution, ecotoxicity, surfactants, Arctic, biodegradation, xenobiotics.

Activity based on earlier ecotoxicological studies financed by the Norwegian Marine Pollution Research and Monitoring Programme and related NTNF projects, leading to development of stadardized diatom ecotox test applied for approval of oil based drilling fluids and offshore chemicals. Oil related projects by Fina/NFR on biosurfactants and emulsifiers lead to one PhD in 1998 and one in 2000 (with prof. em. Kjell Eimhjellen as supervisor). Recent activities have been related to Arctic oil degradation at Sintef Marine Environmental Technology .

Related Master projects have been performed at Sintef Marine Environmental Technology, Hydro Research Center Porsgrunn (vax), UCB Berkeley (BTEX) and ICTP Prague (PCB). [back to top]



Host/microbe interactions in fish

Key words: Mutualism/commensalism/parasitism, host gene expression.

The normal interactions between host and microbes are of a mutualistic or commensal nature, and the unnormal situations are those with parasitism involving pathogens. For studies of host/microbe interactions in an aquaculture context there has been a bias towards studies of the unnormal situations (pathogens), which partly relates to the low survival generally observed for marine fish. However, better knowledge on the role of microbes in healthy animals will serve as knowledge basis for microbial management strategies.

Our work has focused on how microbes enter the gastro intestinal (GI) tract, the speed of colonization, and individual variation in GI tract colonization. More recently we have extended the work to studies on the impact of the microflora for digestion/nutrition, the development of bacteria free larvae to do rearing under gnotibiotic conditions, microbial diversity/pathogen invasion relationships, and gene expression in the fish regulated by differences in the microbiota. Ongoing activities are mainly related to the Codtech and the Promicrobe projects.


Microbial management of marine fish larvae

Key words: Microbial management strategies, microbial maturation, probiotics, disinfecton of eggs, grazer control of microbes, immunostimulation, manipulation of microflora in live feed, microalgae/microbe interactions.

For many marine larvae the rearing is associated with low and variable growth and survival, and lack of reproducibility within and between egg batches. Detrimental larvae/microbe interactions seem to be a key cause for these observations. Based on an ecological analysis of rearing systems we have hypothesized that due to high densities and system perturbations there is a selection for opportunistic species (r-strategists) in today's aquaculture systems, with detrimental host/microbe interactions as a consequence. Based on this analysis we proposed a general strategy and methods for microbial control already in 1993 (Vadstein et al. 1993), and have used that as a research strategy since. Early work focused on methods for surface disinfection of fish eggs, development and testing of the Microbial Maturation concept, methods for classification of microbial communities on a r/K-axis, the use of live feed as vectors for probiotics, evaluation of bacteria as candidates as probiotics, and microalgae as modulators of microbial communities. Four PhDs and a large number of Master students have graduated within this topic.

Previous activities have been funded by the Research Council of Norway, the European Commission, and industry. Ongoing activities are mainly related to the Codtech and the Promicrobe projects. Within this research there has always been a strong national and international cooperation (among others Glasgow Univ, Scotland; Gent Univ, Belgium; Wageningen Univ, Netherlands; Ifremer, France).


Water quality in aquaculture

Key words: Physiochemical quality, microbial quality, Microbial Maturation, recirculation.

Water quality is a fuzzy expression where we have given attention to particles and particle removal, ammonia and nitrification, and microbial quality. At this stage there is no knowledge to classify microbial species on a quality axis, thus we have used the r/K-strategist concept from ecology as a basis for evaluation of microbial quality – dominance of K-strategists indicate good quality and dominance of r-strategists poor quality. We developed the Microbial Maturation Concept where a biofilter is used for controlled recolonization by K-strategist after disinfection or ultra-filtration of the water. Test with yolk sac larvae and during first feeding have demonstrated better survival and growth with Matured water, and effects that are as strong as addition of antibiotics to the water. Later, partly based on experience with recirculation for rearing of sea bass, we have proposed that also recirculation is a technology by which K-selection is obtained. At present we are testing this hypothesis. As a consequence we have also started research on nitrification in seawater, which seem to differ from nitrification in fresh-water.

Previous activities have been funded by the Research Council of Norway and industry. Ongoing activities are mainly related to the Codtech and the Promicrobe projects.



Sources of biofuel

Key words: Microalgae, brown seaweeds, lipids, biodiesel, ethanol.

Microalgae have been suggested as raw materials for second or third generation biodiesel. This raw material can be produced with higher yield per area than traditional plant, will not be in conflict with cultivation of food for humans, and in the case of marine microalgae will not be a competitor for fresh-water. The goal of our activity is physiologically oriented and aims to find environmental factor that are critical for the switch between cell division and lipid accumulation. Focus is on growth limiting factors and light regime. This activity is a cooperation with Department of Biology and is part of the Nordic Lipido project , where the other partners deal with other aspects microalgae raw material for biodiesel.

Biofuel in the form of ethanol from seaweeds was also an important part of the "Energy from macroalgae" (Hydro/NFR) project with one PhD 2000, see Biomass degradation. Current cooperation with Sintef Biotechnology 2009 is trying to improve yield of such production.

Related Master projects have involved Sintef Biotechnology and NIVA Oslo (H2 cyanobact.).


Production of biogas

Key words: Marine biomass, brown seaweeds, cattle manure, fiber fraction, organic fertilizer.

Biogas production from marine primary biomass consisting of brown seaweeds has been intensively studied in projects described above, see Biomass degradation.

Long-term cooperation with Bioskiva AS has handled a variety of aspects related to process optimalization of anaerobic fermentation of cattle manure for total utilization, in their concept with three commercial products biogas, Bioskiva plant cover from fiber fraction and organic (Debio approved) fertilizer from final liquid leftover fraction. The latter has been successfully stabilized as odour free. From 2009 we also participate in the NFR (BIP) project "Biogas Trøndelag" on biogas production by the newly formed company Biogass Fosen.

Related Master projects run in part at Sintef Biotechnology and Bioskiva AS.

SINTEF Aquaculture Technology