Congratulations Dr. Gollnisch!

On March 25th, Raphael Gollnisch defended his PhD thesis “Single-cell population genetics and dispersal limitation of a bloom-forming microalga“. He did brilliantly and can now call himself Dr. Gollnisch. If you are interested in a pdf of the thesis please contact him directly. From our team we wish him all the good luck for the future.

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High calcium limits expansion of Gonyostomum semen

Congratulations to Raphael Gollnisch on his first first-author paper Calcium and pH interaction limits bloom formation and expansion of a nuisance microalga in Limnology & Oceanography (see

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Phytoplankton sampling during winter

In one of our projects we sample year round. That means some extra challenges. Currently sampling on ice on beautiful lake Krageholmssjön. We are using an ice drill to make a hole for our sampling equipment. Of course we have brought all the safety equipment and have taken the necessary precautions for safe sampling. Here on a beautiful day with -10°C and a singing ice!

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New PhD student

I would like to welcome Sandra Rabow, who is a new PhD student in my group. Sandra’s research focus will be on the effect of extreme weather on algal blooms, specifically summer heat waves and the competition between dinoflagellates and cyanobacteria.

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PhD student position opening

A fully funded doctoral student position on freshwater algal bloom dynamics is available in my lab. Closing date February 15, 2020.

 Project description

Blooms like it hot – or not

Aquatic environments are of enormous importance as natural resources of drinking water, fish production and recreation. However, surface waters worldwide are threatened by toxic cyanobacterial harmful algal blooms. The ruling paradigm (blooms like it hot) is that there will be more frequent and intense cyanobacterial blooms in the due to higher temperatures and higher nutrient input. However, during the recent extreme hot summer in Sweden, we observed inconsistencies in this prediction. The event 2018 led to a complete shift in the algal community of a drinking water supply. lnstead a non-cyanobacterium, a potentially toxic dinoflagellate bloomed. This leads to new issues and challenges for management and drinking water plants.

The overall goal of the project is to investigate and include the effect of extreme weather events in conceptual models for future algal blooms, thereby filling an important  knowledge gap. The specific aims include determining how widespread community shifts were in 2018, to which extent spring temperatures determine bloom composition, and if the drought reduced nutrient inputs thereby allowing cyanobacteria to be outcompeted. ln addition, algal toxins will be investigated in the various stages of drinking water treatment.

For further information see:

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High diversity of microcystin chemotypes

Congratulations to PhD student Emma Johansson for the publication of her first paper for her thesis! In this study Emma has explored the microcystin variants (chemotypes) of 130 Microcystis botrys strains from a single bloom season. See

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Gonyostomum chloroplast genome

Former lab member Ingrid Sassenhagen just published our paper on the Gonyostomum semen chloroplast genome in a special volume in Genes. This work was done using whole-genome amplification from a few isolated chloroplasts, thereby circumventing having to culture cells. Please see:

Special Issue:
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Postdoctoral position available

Project description

Microscopic organisms are widespread and many species have a cosmopolitan distribution. This pattern suggests that microorganisms (such as phytoplankton), in contrast to most larger organisms, have unlimited dispersal. Unlimited dispersal implies high migration rates and gene flow within a species, and consequently no opportunity for populations to differentiate. However, many studies show that phytoplankton populations are genetically highly differentiated. This implies limited gene flow despite high dispersal, posing a dispersal–differentiation paradox. Explanations to this paradox may include the importance of founding individuals (founder effects), and rapid local adaptation in phytoplankton. Within this project we will experimentally test these hypotheses using a model green algal system.

The postdoctoral fellow will be involved in the research on the dispersal-differentation paradox in phytoplankton, utilizing the model species Chlamydomonas. The project encompasses both experimental laboratory studies as well as some field work. The postdoctoral fellow will be responsible for experimental work testing founder effects and local adaptation in Chlamydomonas populations. The work will include algal culturing, PCR, and preparation of RADseq libraries, in the laboratory. Downstream analyses will include bioinformatic analyses, population genetic analyses, as well as writing manuscripts. The postdoctoral fellow is expected to conduct high quality research and to disseminate results in international scientific publications.

For more information follow the link below and/or contact Karin Rengefors.

Application deadline: 6 March 2019

Procedure: Go to Postdoctoral fellow in Biology, PA2019/75

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Gonyostomum in Cedar Swamp, Woods Hole

In a paper 1935, Drouet and Cohen, described that they had found the rarely observed flagellate Gonyostoum semen in a sphagnum swamp in Woods Hole, Massachusetts, USA. This locality is referred to by residents as the Cedar Swamp. This year we managed to enter the swamp, find the open water, and resample. Just as in 1934, there was a major bloom of Gonyostomum, dominated the phytoplankton community entirely! The next step is comparative analyses to European populations.


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2018 field sampling

This summer we will have two major field sampling campaigns going on. One is here in southern Sweden, in lakes Ringsjön and Vombsjön. The project is focused on the seasonal dynamics of toxin and non-toxin producing strains of the cyanobacterium Microcystis botrys, and is part of Emma Johansson’s PhD project.  The second field sampling expedition will be across the U.S. This sampling is part of Raphael Gollnisch’s PhD project, and is focused on collecting samples of the invasive nuisance raphidophyte Gonyostomum semen. Fingers crossed that both sampling campaigns will be successful!ringsjön


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