EXPERTISE ON CYANOBACTERIA, OR BLUE-GREEN ALGAE, AT LIST

The recent mass outbreaks of cyanobacteria, also called blue-green algae, in the water of the Haute-Sûre reservoir shows the importance of local scientific expertise, especially since European Directive 2006/7/EC concerning the management of bathing water quality advises appropriate monitoring to enable the timely identification of the health risks associated with cyanobacteria. The environmental microbiology team at the Luxembourg Institute of Science & Technology (LIST) has over 10 years of experience in this field.

SEASONAL MONITORING OF BLUE-GREEN ALGAE: RESULTS AND MEASURES TAKEN

LIST is working in close collaboration with the Administration de la Gestion de l’Eau (Water Management Administration, or AGE) and the Syndicat des Eaux du Barrage d'Esch-sur-Sûre (SEBES) as part of the monitoring of cyanobacteria and their associated toxins during the period of prevalence, which usually extends from late August to late October in the Haute-Sûre reservoir. When there is a proliferation of cyanobacteria and when a health risk has been identified or is assumed, the framework directive calls for adequate management measures to prevent exposure, including measures to inform the public. This is why the Ministry of Sustainable Development and Infrastructure has recommended against bathing in the reservoir water since 30 August 2016.

The blue-green algae is, in fact, bacteria. These photosynthetic micro-organisms produce specific pigments, such as phycocyanin (blue pigment), which gives them their characteristic colour as well as their historical name. In favourable conditions – strong sunlight, little wind, abundant supply of nitrogen and phosphorus, etc. – these colonial bacteria proliferate and become dominant in the water column, to finally form blooms on the surface. Apart from the sometimes spectacular visual effect, many species of cyanobacteria produce dangerous toxins to humans and animals, including hepatotoxins (liver damage), neurotoxins (brain) and dermatotoxins (skin).

WHAT ARE LIST EXPERTS LOOKING FOR AND WHY?

LIST's team of specialists want to better identify the factors that promote the appearance and development of cyanobacteria blooms, by combining microscopic (identification of species) and chemical (type and rate of cyanotoxins) analyses with hydrology, environmental pollution and climatology studies. As part of the definition of the new protected areas of the Haute-Sûre reservoir, nutrient inputs into the reservoir are assessed, including assessing the importance of the "Misère" and "Bavigne pre-dams in the causes of contamination and the formation of blooms.

In addition to the seasonal monitoring of the diversity and quantities of cyanobacteria in the Haute-Sûre reservoir, researchers from LIST are also testing new technologies to prevent the formation of blooms, for example by the localised use of specific ultrasound waves. All these research activities at LIST are designed to better analyse and manage the toxic and microbiological risks associated with the issue of blue-green algae, most especially with regard to drinking water and recreational water in Luxembourg.

> For further information, please contact Dr. Christian Penny