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Emma Johansson

Doctoral student

A natural phenomenon turned nasty: Where, when, and why will cyanobacterial blooms be toxic?

My work focus on Microcystis botrys, a freshwater cyanobacterial species commonly found in lakes in southern Sweden. It is known to produce microcystins, toxins that could be hazardous to human health, pets, cattle, aquatic organisms, and that could be a treath to drinking water supplies. However, not all strains ("individuals") in a bloom produce microcystins, and strains that are "toxic" can produce a large vareity of microcystins, in different quantities. Therefore, Microcystis blooms are not necessarily harmful.

The main focus of this project is to study the intraspecific variation of microcystin-production in M. botrys. My current aim is to investigate whether "toxic" and "non-toxic" strains form separate subpopulations and if this is driven by selection/ecological differentiation rather than neutral evolution. Another task is to examine the genetic structure of populations (temporal and spatial distribution, dispersal patterns) and the potential ecological functions of microcystins (during competition of nutrients and other resources, protection against predators and/or parasites).

Page Manager:
Emma Johansson
E-mail: emma.johansson [at]

Doctoral student

Aquatic ecology

+46 46 222 40 03


Ekologihuset, Sölvegatan 37, Lund, Sweden