Algtox - Knowledge Center on Algal Toxins

What are Algal Toxins? Algal toxins are dangerous chemicals created by both micro and macro algae during their life cycles. These toxins are released from the cells and spread into the water, causing serious problems. The production of algal toxins varies in strength and location, which is linked to the intensity and location of algal blooms.

Usually the production of algal toxins peaks during the summer, but some toxins can also be produced when the water is cold. These toxins can harm both fish and people living in or near the water.

Algal blooms are often the result of an excess of nutrients, such as nitrogen or phosphorus from fertilisers or other sources, which leads to excessive growth of algae and affects the whole ecosystem.

Research projects we are active in:

Live monitoring of mussel farms in the Baltic Sea – to predict toxin production and minimize negative environmental impact

Mussel farming is in many ways a sustainable food production where nutrients are taken up from the water and converted into food which is then taken out of the water at harvest. This is especially beneficial in the eutrophic Baltic Sea and therefore it would be a success if this industry that uses filter-feeding organisms gives mussels a chance to grow and establish themselves. However, mussel farmers today spend a lot of time travelling back and forth to their farming sites to ensure that the equipment is working properly and to manually collect samples to both ensure good ecological status around the farms and low levels of phytoplankton toxins in the water. Our project aims to develop and implement an integrated monitoring system that combines satellite data, advanced sensors that measure pigments in phytoplankton as an indicator of toxicity and in relation to environmental variables. These systems are not available on the market for the marine environment today, similar systems are used to a lesser extent in lakes for drinking water in southern Sweden and here we can draw inspiration and exchange knowledge.

Participants: Malin Olofsson, Martin Reutgard and Martin Karlsson from Ecopelag mussel farmers, Jing Li (Lund Univeristy).

Project duration: 2025-2028

Funding: Board of Agriculture/EU, 5 MSEK. 

Revealing population traits of locally adapted filamentous cyanobacteria – using multiomics

Dense blooms of filamentous cyanobacteria are formed during summer in the Baltic Sea, dominated by three different taxa, and they all use individual growth strategies resulting in variable responses to climate change, i.e., decreased salinity and elevated temperature. However, taxa-specific responses are not consistent and could be explained by the existence of locally adapted sub-populations, or so-called ecotypes. This project aims to elucidate ecological drivers and adaptations in basin-specific cyanobacterial populations by using an array of field and laboratory experiments applying a mixture of genomic tools and nuclear magnetic resonance spectroscopy (multiomics).

Participants: Malin Olofsson, Ricardo Parizotto Ribeiro (PhD student), Fernando Puente Sanchez (co-supervisor).

Project duration: 2025-2028

Funding: Swedish Research Council (VR), 4.4 million SEK. 

Establishment of the Centre for Environmental Monitoring of Algal Toxins - from sampling to communication with the public

The Knowledge Centre is a collaborative project between the Swedish University of Agricultural Sciences (SLU), the Swedish Meteorological and Hydrological Institute (SMHI) and the Swedish National Food Agency to gather insights into toxic algal blooms. We focus on the questions of when and where the toxins are produced and what types of toxins are produced by which species. The Knowledge Centre will also develop effective sampling routines and analytical methods for the toxins to investigate the possibility of including algal toxin analyses in regular environmental monitoring.

Participants: Malin Olofsson, Elin Dahlgren, Bengt Karlson (SMHI), Aida Zuberovic Muratovic (Swedish Food Agency), Karin Wiberg, Stefan Bertilsson, Stina Drakare.

Project duration: 2023-2026

Funding: 3.1 million SEK, Swedish Board of Agriculture/EU.

Climate adaptation and mapping of algal toxins associated with mussel farms

Since mussels filter water when they eat, algae are part of their diet. This makes mussels highly interesting for learning more about toxic algal blooms. Therefore, this project follows mussel farms to answer questions about when and how much algal toxins are present in the water during a year. The project includes two PhD students who will study two groups of toxins, cyanotoxins and brominated substances to increase understanding of their occurrence and production.

Participants: Elin Dahlgren, Malin Olofsson, Dennis Lindqvist, Caroline Ek, Ecopelag mussel farm.

Project duration: 2023-2027

Funding: SEK 10 million, Swedish Board of Agriculture

Toxicity of filamentous cyanobacteria in a warmer climate and their effect on zooplankton

Using a naturally heated system outside Forskmark, studies will be conducted focusing on how warming affects the toxicity of cyanobacteria and also the uptake and adaptation of zooplankton. We will study seasonal differences between the heated area and the natural area both in terms of toxins and molecular adaptations in both cyanobacteria and zooplankton. We will also use sediments to hatch resting stages to study local adaptation.

Participants: Malin Olofsson, Magnus Huss, Anna Gårdmark

Project duration: 2023-2025

Funding: 1 million SEK, Oscar and Lilli Lamm

Previous projects

Pilot project focusing on toxin production in filamentous cyanobacteria

We will conduct experiments where we study the cyanobacterium Nodularia spumigena under different conditions to study when and how many toxins are produced. Here we also include molecular methods to understand the genetic expression during production, to more easily monitor gene presence in natural environments.

Malin Olofsson, Elin Dahlgren, Parisa Norouzitallab

Project duration: 2023-2024

Funding: 68 000 SEK, SLU Water

Cyanobacterial toxin - when and why is it produced?

Cyanobacterial blooms are becoming more common in the Baltic Sea as a result of human impact. Many of them produce toxins that affect both humans and animals. Recent research shows that algal toxins are likely to be a contributing factor to poor fish health in the Baltic Sea and that fish are ingesting more cyanobacteria than previously thought through their diet. To understand when and why cyanobacteria produce toxins, we will map them in different environments and find out under what circumstances the toxins are produced by both measuring different toxins and looking at gene content and expression. This will allow us to inform policy makers to take effective measures to reduce its negative effects.

Participants: Malin Olofsson

Project duration: 2024-2025

Funding: 200 000 SEK, BalticWaters

------------------------------------------

Current team:

Malin Olofsson, Researcher (Docent)

Elin Dahlgren, Researcher (Docent)

Manuela Seehaser, PhD student since 2024

Manne Larsson, PhD student since 2023

Ricardo Parizotto Ribeiro, PhD student since 2025

Ana Cekol, lab technician since 2024

Zachary Chan Zhe Kai, MSc student fall 2025-spring 2026

Ailin Rasaie, guest PhD student fall 2025

Alma Sandqvist, BSC student fall 2025

Alumni:

Fanny Persson, Lab assistant, summer 2024 and 2025

Sajani Hansana, MSc student spring 2025

Mohanad Abdelgadir, Post doc 2024-2025

Mihriban Özen, Post doc, 2023-2024

Freja Westermark, BSc 2023

------------------------------------------

More about algal toxins:

Cyanobacteria

When we talk about algal blooms in summer, we often refer to cyanobacteria, as they create thick mats of tiny cells. These tiny organisms sometimes produce different types of toxins that can be harmful to humans, animals, and possibly plants. We know of several different types of toxins produced by cyanobacteria, but there are gaps in our knowledge because not enough comparative material is available yet.

In the Baltic Sea, three groups of filamentous cyanobacteria dominate: Aphanizomenon spp, Dolichospermum spp, and Nodularia spumigena. For the first group, Aphanizomenon spp. there is no evidence that it produces toxins in the Baltic Sea - but in other environments. Dolichospermum spp. can produce several different types of toxins with great variation between environments and environmental parameters. Nodularia spumigena produces high levels of the toxin nodularin in the Baltic Sea. Among the species that can produce toxins in lakes, Microcystis and Planktothrix predominate, which mainly produce various microcystins that interfere with both swimming and drinking water production.

Red and brown algae

Filamentous algae can also produce biotoxins. The brackish waters of the Baltic Sea contain the element bromine, from which fine-grained red and brown algae can produce toxic substances such as polybrominated diphenyl ethers (OH-PBDEs), polybrominated phenols (BPs) and polybrominated dibenzo-p-dioxins and polybrominated dibenzofurans (PBDD/Fs). These substances are also produced industrially as flame retardants. The algae Ceramium tenuicorne and Pilayella littoralis are known producers of brominated algal toxins. The toxins OH-PBDEs and BPs can be found in all parts of the Baltic Sea food web, in cyanobacteria and algae, crustaceans, mussels, fish, seals, and birds.

Other toxin-producing species

In the Baltic Sea and on the west coast, diatoms and microscopic organisms such as dinoflagellates produce toxins and can cause various forms of poisoning. In recent years, the dinoflagellate Alexandrium ostenfeldii has increased in the Baltic Sea. It can cause paralytic shellfish poisoning syndrome (PSPs), as it can produce neurotoxins such as gonya toxin and saxitoxin. PSP is caused by the ability of saxitoxins to block nerve impulses and can be fatal when it causes respiratory failure. PSP toxins are found in several parts of the Baltic Sea food web, in filter feeders, crustaceans and fish with levels varying over the summer season. Dinoflagellates can produce diarrhoea toxins, such as okadaic acid, which is considered to be a particular problem when consuming mussels. The Finnish Food Authority monitors commercially farmed mussels and oysters for paralytic shellfish poisoning (PSP) and diarretic shellfish poisoning (DSP), but not currently for cyanotoxin.