Blinded by the light: Increased chlorophyll fluorescence of herbicide-exposed periphyton masks unfavorable structural responses during exposure and recovery

Aquatic Toxicology
Alexander FecklerMirco Bundschuh

Abstract

In surface waters within agricultural catchments, periphyton - i.e., biofilms containing algae, heterotrophs, and associated detritus - is subjected to multiple stressors including herbicides. Although herbicide effects on periphyton are frequently studied, the focus has been on photosynthesis-inhibiting herbicides while other modes of toxic action have received little attention. Against this background, a 21-days-lasting bioassay was conducted, during which mature periphytic communities were exposed to the carotenoid-biosynthesis-inhibiting herbicide diflufenican for 12 days (up to 10 μg/L; n = 4), followed by a 9-days-lasting recovery phase in herbicide-free medium. Variables related to periphytic functioning (photosynthetic efficiency and non-photochemical quenching) and structure (pigment concentrations, biomass, and algal community structure) were quantified every third day during both experimental phases. Exposure to ≥ 0.2 μg diflufenican/L resulted in 20-25% and 25-30% lowered carotenoid and chlorophyll a concentrations, respectively, likely explained by a reduced algal biovolume as well as diflufenican's mode of toxic action and thus a shift towards a higher heterotrophy of the communities. Despite these adverse effects...Continue Reading

Citations

Apr 11, 2020·Environmental Toxicology and Chemistry·Maria Alexandra BighiuWillem Goedkoop
Sep 17, 2019·Water Environment Research : a Research Publication of the Water Environment Federation·Paula C FureySylvia Lee
Dec 15, 2020·The Science of the Total Environment·Laura Beecraft, Rebecca Rooney
Aug 25, 2021·Environmental Pollution·María Solange Vera, María Alcira Trinelli

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