Research group MPEA

Marine Phytoplankton Ecology and Applications

Beneath icy waters: A research excursion to the Arctic



In just two weeks, our team of picophytoplankton researchers will board the research SAS Oden and set sail on July 26, when the icebreaker departs from Helsingborg. On August 2, the observations in the Arctic Ocean begin. The estimated return to Helsingborg is September 20, 2021. Preparations for the excursion have been underway for over a year – the global pandemic in 2020 canceled the research trip last year, and the marine scientists have redoubled their efforts to ensure a sampling trip that is both COVID-safe and successful in its scientific conquests.

The study is part of the Synoptic Arctic Survey, an international study that will be making a comprehensive investigation of the current state of the Arctic ecosystem from 2020-2022 and assess how it is changing.

In the Swedish part of the survey, 39 researchers from 14 institutions will be participating. From Lnu, project managers Hanna Farnelid, Karin Holmfeldt, and Samuel Hylander lead their group.

For updates on this synoptic survey, you can visit the official blog: as well as the project page—synoptic-arctic-survey-sas-oden-2021/ .

Christien Laber, one of MPEA’s researchers is prepping for the excursion. Christien spend his time on the arctic investigating picophytoplankton, the smallest photosynthesizing organisms on the planet, and their contribution to sustaining the marine ecosystem in the Arctic. He will begin his journey by undertaking a quarantine in Malmö beginning July 16th:


What has been the biggest challenge in preparing for your trip to the Arctic?

Two things.  Details, and shortages due to coronavirus.  Details are very important because we will be at sea for two months.  If we forget anything or don’t have spares when things break, there’s no way to get extras.  So we really have to plan all of our experiments and the things we need for them very carefully.  This has been a bit more difficult recently with coronavirus as well, because some equipment we buy well ahead of time takes a long time to get here, which makes it difficult to feel prepared when we never know when equipment will show up.



What is your schedule like from day to day?

Every day will be different.  We have a number of experiments we will conduct and they will be done at different times throughout the cruise.  We also have a number of core sampling procedures we will do every day, but may have different personnel doing them depending on the other tasks that are ongoing.  But one thing that will remain the same is that there will be lots of filtering seawater, every single day.


You work with Hanna Farnelid and her team on the picophytoplankton research. What kind of sampling will you do and equipment you will use to answer your research questions?

We will be doing experiments to investigate how the smallest phytoplankton in the arctic grow, what types of nutrients they consume, and then in turn how quickly they are eaten by larger plankton.  Our deck-board incubators are important for conducting these studies, as it allows us see what happens in the seawater over time.  Because water is always moving, we can’t simply sample the ocean over three days and expect it to be the same water, so these incubators allow us to know we are working with the same water over each of our experiment time points.


We will surely miss you all and look forward to seeing you! We know that updates from the vessel will be few and far between, if at all, but we look forward to seeing the samples, and the photos, upon your return!


-Caroline Littlefield




GENIE Program: “A conscious focus on unconscious bias​” Zoom Seminar


During this past month’s AMRI seminar, we learned about the GENIE program at Chalmers University, which was established with the following goals:

  • Increase the proportion of female faculty
  • Remove the structural and cultural obstacles that hamper women’s careers
  • Create a working environment that is diverse and inclusive and supportive of excellence in research and teaching

Next week, a Zoom seminar with GENIE will take place on Nov. 23, 15.00 – 16.00 entitled “A conscious focus on unconscious bias.” 

Speakers are:  Annette Bak, Head of Advanced Drug Delivery at AstraZeneca, and Katarina Matson, Head of Culture & Diversity at Volvo Cars. Sign up to the seminar using the Choodle link below. You will receive a  Zoom link to the seminar the day before the seminar.

Avslöjat! Havets hemliga mikroliv


De senaste åren har naturens hemliga liv kommit på tal allt mer. Böcker som handlar om hur träd och svampar kommunicerar via vidsträckta underjordiska nätverk har toppat listorna. Men hur står det egentligen till med det hemliga mikrolivet i våra hav och sjöar?

Vi vet att mikroorganismer såsom alger och bakterier är avgörande för hur näringsämnen och energi fördelas och återanvänds, och att utan dem skulle havens makroliv se ut på ett helt annat sätt än det gör idag. Vi vet också att det är mikroalger som producerar mer än hälften av det syre som finns i vår atmosfär idag. Men hur de olika mikroorganismerna i haven faktiskt fördelar dessa uppgifter emellan sig och hur denna arbetsfördelning påverkas av störningar orsakade av till exempel övergödning och klimatförändringar känner vi inte så väl till än. För att kunna göra bättre modeller av hur havens ekosystem och de ekosystemtjänster dessa förser oss med kan komma att ändras under ändrade förutsättningar, såsom ökande temperaturer, ökande nederbörd och ökande tillförsel av näring till sjöar och hav, behöver vi veta mer om naturens hemliga mikroliv. Detta har jag försökt ta reda på i min avhandling där jag har studerat just hur interaktioner mellan alger och bakterier är organiserade, vilka mekanismer det är som styr dem och hur de påverkas av störningar såsom hög tillgång på energi och näring eller varierande temperaturer.

Dels har jag kunnat visa att de bakterier en alg omger sig med går att förutse, vilket tyder på att interaktioner mellan dessa organismer är så pass viktiga att de påverkar vilka typer av mikroorganismer som återfinns på en plats. Dels har jag kunnat visa att alger och bakterier tillsammans skapar förutsättningar för att ekosystem ska kunna hantera till exempel varierande temperaturer utan att systemet ändrar karaktär. De kan göra detta genom att balansera hög eller låg artvariation och genom att ta över varandras funktioner, och de gör detta på ett sätt som bibehåller både variationen och funktionen för hela systemet. På detta sätt har mikrolivet en stark inverkan på balansen i hela näringsväven. Jag har också kunnat visa på att alger och bakterier, under förutsättningar som tidigare har antagits leda till konkurrens om näring, istället karaktäriseras av fördelning av näringsämnen mellan mikroorganismerna. Detta tyder på att tidigare antaganden och de slutsatser som dessa har givit upphov till kan komma att behöva omvärderas. Sammantaget visar jag i avhandlingen att alger och bakterier påverkar och påverkas av varandra på ett sätt som tidigare inte varit känt.

Klimatförändringar och övergödning av våra sjöar och hav är några av vår tids stora ödesfrågor, med den här avhandlingen har jag bidragit till att avslöja lite mer om hur mikroorganismer hanterar ändrade förutsättningar. Detta är kunskap som kan användas för att bättre förstå konsekvenserna av klimatförändringar på naturen. Naturens hemliga mikroliv är inte längre lika hemligt▪


– ES

Dr. Eva Sörenson defended her thesis on September 25th , 2020.

Her supervisor is Catherine Legrand. 

Opponent: Prof Sonya Dyhrman, Columbia University
Chairman: Dr. Per Nilsson, Linneaus University
Examining committee:
Prof Alexandra Z. Worden, GEOMAR Helmholtz Centre for Ocean Research
Doc Sam Dupont, Gothenburg University
Prof Stefan Bertilsson, Swedish University of Agricultural Sciences

Thesis title: Functional and structural characterisations of phytoplankton-bacteria interactions in response to environmental challenges

Wrapping up the summer field work season with BUG2020


August and September in the Baltic Sea is full of life fueled by the summer sun.  Phytoplankton at the base of the marine food web are rapidly photosynthesizing, and cyanobacteria in particular are producing their annual summer blooms at the surface of the warm and stratified waters. We took the opportunity to conduct experiments at the LNU marine field station in Kårehamn, Öland, in beautiful summer weather investigating the growth and mortality of Baltic picocyanobacteria.

Pictured: PhD student Javier Alegria-Zufia and Dr. Hanna Farnelid recovering an array containing bottles of experimental seawater for the grazing study. After initially collecting seawater, the different experimental groups are contained in bottles and placed in these arrays, which are kept as close to ambient conditions as possible. The incubated experimental seawater experiences the same light and temperature conditions as a natural population would for the duration of the incubation, before being retrieved for sampling.

Tiny picocyanobacteria are prominent members of this community of phytoplankton. They can divide and become more abundant or they may become food for others in the food chain. Picocyanobacteria sustain their growth by consuming the available nutrients in the surrounding waters. Like many of us here on planet Earth, these microbes have preferences for their nutritional intake. Where a person might choose a banana over an apple for their daily fruit consumption, picocyanobacteria can have preferences for nitrate or ammonium as a source for critically needed nitrogen to grow. These nutrient preferences impact both the respective nutrient concentrations remaining in the water as well as the growth strategy of the cells that consume them. It is, however, still a mystery what the preferences are for picocyanobacteria that live and grow in the Baltic Sea.

The study, titled BUG2020 for Baltic Uptake and Grazing investigates the preferences for nutrient sources and the mortality rates of picocyanobacteria growing at the Linnaeus Marine Observatory (LMO), located 10 km offshore the east coast of Öland. To determine nutrient preferences, seawater was incubated with stable isotope labeled nutrients. In addition, dilution experiments were performed focusing on the grazing and mortality of Baltic picocyanobacteria. Measuring growth rates at several dilutions of relaxed grazing and virus pressure allows for the calculation of grazing rates on the algae, which is important in understanding the cycling of nutrients throughout the Baltic Sea.


-Christien Laber, Laboratory Engineer


The BUG2020 experiment is a collective effort within the Marine Phytoplankton Ecology and Applications research group. The members working on BUG2020 are:

Hanna Farnelid, Associate Professor

Elin Lindehoff, Associate Professor

Christien Laber, Laboratory Engineer

Javier Alegria-Zufia, PhD student

Catherine Legrand, Professor