Séminaires de Myriam BORMANS et Claudia WIEGAND


Le vendredi 20 avril 2018 à 13h00, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1

Le vendredi 20 avril 2018 à 13h00, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1

Transfer and fate of toxic cyanobacteria from freshwater to the marine environment (M. Bormans, 13h)

Résumé :
Eutrophication of aquatic ecosystems combined with global warming lead to an increase of the frequency and intensity of cyanobacterial blooms. These photosynthetic microorganisms produce a high number of bioactive molecules including a great diversity of toxins affecting animal and human health. The ecology of freshwater cyanobacteria is well documented but less is known about their transfer and fate to the coastal environment.
I will present two complementary projects where we assess the transfer of toxic cyanobacteria via the river continuum into estuarine waters. We aim to better understand the survival of toxic freshwater cyanobacteria in estuarine waters and their impact on estuarine organisms. Combined field and laboratory experiments are being conducted to - determine the direct effects of salinity (as shock and acclimated conditions) on growth and toxins production by freshwater cyanobacteria - investigate the fate of freshwater cyanobacteria and their toxins during the transfer from the freshwater to estuarine environment based on natural samples - expose marine bivalves to freshwater cyanobacteria and assess the cyanotoxins bioaccumulation, to evaluate the potential contamination of estuarine organisms.

Channel Payment for Ecosystem Services CPES (EU-INTERREG) (C. Wiegand, 13h30)

Résumé :
More than 50 % of the water bodies entering the Channel are not classified as of Good Ecological Status due to sedimentation, low oxygen levels, or excess nutrient load, causing cyanobacterial dominance. This in turn causes economical losses for drinking water abstraction, fishing and tourism activities. I will present the project CPES, that started January 2018 and aims to develop PES (Payment for Ecosystem Services) schemes to improve water quality by reducing sedimentation and eutrophication (nitrates and phosphates) with a catchment wide approach. The project comprises 6 pilot studies within the British and French side of the Channel area. One of which is the multi-purpose reservoir Lac au Duc (touristic, drinking water, fishing) and its catchment. We are part of the consortium studying features from catchment (hydrology, land use, nutrient emissions), aquatic ecology (eutrophication), and economy (evaluation of public policies applied to agriculture and environmental economics, design of PES).
Reducing cyanobacterial dominances requires a long-term reduction of the nutrient load and input, and can be accomplished by acute treatments. These acute treatments (e.g. hydrogen peroxide, ultra-sound) need a thorough analysis of the eutrophication scenario, and the ecological state of the lake, to meet both, efficiency and environmental safety demands.

Contacts : Myriam BORMANS et Claudia WIEGAND

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