Water sampling in Kalmar with the castle in the background

Project: Virus control on Baltic Picocyanobacteria

Viruses are the most abundant biological entity in marine environments and influence the abundance and evolution of microbes. Here, we explore the impact of this viruses on picocyanobacteria, the smallest primary producers which are widespread in all aquatic environments and play a crucial role in the Baltic Sea ecosystem.

Project information

Project manager
Hanna Farnelid
Other project members
Anders Runesson, Josefin Fägerås, Linnaeus University; Alison Buckler, Open University, UK
Participating organizations
Linnaeus University
Crafoord Foundation; Carl Trygger Foundation
31 Dec 2021–31 Dec 2025
Ecology (Department of Biology and Environmental Science, Faculty of Health and Life Sciences)

More about the project

Viruses are by far the most abundant 'lifeforms' in the oceans. If stretched end to end, the estimated 1030 viruses in the ocean would span farther than the nearest 60 galaxies. Viruses are important for carbon and nutrient flow in the oceans, overturning a quarter of the organic carbon from primary production and thus having a large impact on global biogeochemical cycles. Furthermore, Cyanophages, viruses that infect cyanobacteria, exert important controls on the abundance, productivity, and diversity of cyanobacterial communities; impacting their ecology and evolution. Cyanobacteria play an important role in the ecosystem of all aquatic environments. These tiny photosynthetic organisms are the base of the marine food web and through their photosynthetic function, responsible for 25% of the daily oxygen production. In the Baltic Sea picocyanobacteria (< 2 µm) can make up to 80% of the biomass during summer.

The Baltic Sea picocyanobacterial populations are composed of a diverse group with distinct seasonality and distribution patterns; differing from those of marine and freshwater ecosystems. The distribution and growth of picocyanobacteria is largely determined by abiotic factors such as temperature, salinity, nutrients, and light availability. However, biotic factors that control the mortality (e.g. viral lysis and zooplankton grazing) have been much less explored. Up to date, most research on cyanobacteria and their associated viruses focuses on marine or freshwater systems.

Here we study cyanophages from the Baltic Sea, the world’s second-largest estuarine environment. The project will gain insights into the ecology of cyanophages and their role in controlling estuarine picocyanobacteria. On a global scale, knowledge of the diversity of cyanophages and their infection in the oceans is of great importance for understanding and predicting ecosystem functions.

The project is connected to Linnaeus University Centre for Ecology and Evolution in Microbial model Systems (EEMiS). It is part of the research in the Marine phytoplankton ecology and applications (MPEA) research group and belongs to the Linnaeus Knowledge Environment: Water.