Fluvial biofilms: A pertinent tool to assess beta-blockers XXXX .

@entity1169 @entity137 @entity4324 @entity1406 @entity2165
Among increasingly used pharmaceutical products, beta-blockers have been commonly reported at low concentrations in rivers and littoral waters of @entity4324 . Little is known about the @entity137 of these chemicals in freshwater ecosystems while their presence may lead to chronic pollution. Hence, in this study the acute @entity137 of 3 beta-blockers: @entity1406 , @entity1169 and @entity2165 on fluvial biofilms was assessed by using several biomarkers. Some were indicative of potential alterations in biofilm algae (photosynthetic efficiency), and others in biofilm bacteria (peptidase activity, bacterial mortality). @entity1169 was the most toxic beta-blocker, mostly affecting the algal photosynthetic process. The exposure to 531microg/L of @entity1169 caused 85% of inhibition of photosynthesis after 24h. @entity1406 was particularly toxic for bacteria. Though estimated No-Effect Concentrations (NEC) were similar to environmental concentrations, higher concentrations of the toxic (503microg/L @entity1406 ) caused an increase of 50% in bacterial mortality. @entity2165 was the least toxic of the three tested beta-blockers. Effects superior to 50% were only observed at very high concentration (707mg/L). Higher @entity137 of @entity1406 and @entity1169 might be due to better absorption within biofilms of these two chemicals. Since beta-blockers are mainly found in mixtures in rivers, their differential @entity137 could have potential relevant consequences on the interactions between algae and bacteria within river biofilms.
