Erdre Study on Cyanobacteria in the River Erdre

Comprehensive study of cyanobacteria in the river Erdre

Project partners :KWB, Veolia, Setude, Bi-EauProject volume :125.400 €Project start :01.01.2003Duration :12 months


The Erdre River, located in Western France, has been exposed to severe cyanobacteria blooms in the past years, having a negative impact on nautical activities due to the possible danger for human health. In cooperation with the Federal Environmental Agency, the KWB took part in a comprehensive study initiated by the local association E.D.E.N. Cyanobacteria growth as well as synthesis and release of algal toxins are being studied, in order to develop strategies to limit these phenomena.

Expected outcomes



The project was realised from the end of 2002 until early 2004, with the cooperation of French and German scientific partners. The specialists from the Federal Environmental Agency in Berlin (Dr. Chorus, Dr. Fastner) realised lab-scale experiments to identify the influence of three different factors on the development of cyanobacteria and their toxins. The study focused on the species Planktothrix agardhii and microcystin, the associated toxin, which are predominant in the river Erdre.

1. Nutrients:
To assess the impact of nutrient limitation (nitrogen and phosphorus) on the growth of cyanobacteria and the release of the associated toxins, lab-scale cultures in nutrient-depleted conditions were implemented at the UBA.

2. Flow velocity:
The potential influence of flow velocity on cyanobacteria growth, cell stability and toxin release were tested in the flow simulation flume of UBA in Berlin-Marienfelde, using an artificial river with massive cultures of Planktothrix agardhii.

3. Sediments:
Adsorption, degradation and release of microcystin in sediments from the river Erdre were measured using lab-scale experiments.
Sediments may also favour growth by storing and eventually releasing nutrients and cyanobacteria. This was also part of the study.

Until early 2004, the completed results allowed a comprehensive understanding of the phenomena.


Project partners

Entente pour le Développement de l'Erdre Navigable (E.D.E.N.), SETUDE, KWB in cooperation with the German Federal Environmental Agency, Anjou Recherche (Veolia Water), Eco Environnement Ingénierie, BCEOM, BI-EAU.


What are cyanobacteria ?

Cyanobacteria or “blue algae” are bacteria able to realize photosynthesis. Their proliferation in water bodies represents a risk for health due to the potential liberation of toxins by some strains.

More information about cyanobacteria and toxins:
“Toxic Cyanobacteria in Water: A guide to their public health consequences, monitoring and management” (CHORUS, BARTRAM, WHO 1999)


Dr. Bodo Weigert (KWB)