Single and mixture effects of pesticides and a degradation product on fluvial biofilms

Abstract

The Morcille River located in the Beaujolais vineyard area (Eastern France) is subjected to strong vine-growing pressure leading to the contamination by a range of herbicides and fungicides of the surrounding freshwater environment. Particularly high concentrations of norflurazon, desmethyl norflurazon and tebuconazole were recorded in spring 2010 at the downstream site of the river. Despite their occurrence in rivers, scarce toxicity data are available for these products, in particular in the case of desmethyl norflurazon (main norflurazon degradation product). Furthermore, the toxicity data are generally available only for single compounds and are issued from single species toxicity tests, leading to a lack of ecological relevance. Consequently, this study was undertaken to evaluate the toxic effects of norflurazon, desmethyl norflurazon and tebuconazole singly and in a ternary mixture on fluvial biofilm. Toxicity tests were performed in microplates for 48 h. Photosynthetic endpoints were measured using pulse amplitude-modulated fluorometry; diatom densities and taxonomic composition were determined. After 48 h of exposure, significant effects on optimal quantum yield (F v/F m) for desmethyl norflurazon and mixture were observed.

Herbicide toxicity on river biofilms assessed by pulse amplitude modulated (PAM) fluorometry

“…Exposure to NFZ is expected to lead to indirect effects on fluorescence levels by inhibiting renewal of the cellular carotenoid pool essential to the correct functioning of the photosynthetic apparatus. Its effects have been well studied with regards to growth-related parameters or photosynthetic pigments in microalgae or plants (Sandmann et al, 1981;Frankart et al, 2003;Wilkinson, 1987;Wilson and Koch, 2013) but very little is known on its indirect effects on photosynthetic activity and in particular on river biofilms (Nestler et al, 2012;Kim Tiam et al, 2014).…”

Effects of mixtures of dissolved and particulate contaminants on phototrophic biofilms: new insights from a PICT approach combining toxicity tests with passive samplers and model substances

“…Given the study of Kim-Tiam et al (2014b), who obtained for photosynthetic efficiency EC 10 between 9 and 254 μg NFZ-D/L with biofilms exposed to 48 h to this metabolite. As a consequence, diuron and NFZ-D may have significantly contributed to the toxicity of POCIS extract in the present study.…”

“…As recently shown by Kim-Tiam et al (2014b) with tebuconazole (well represented in the POCIS extract), photosynthetic efficiency is not a relevant parameter to reveal short-term direct effects of fungicides, which do not act directly on the algal compartment of the biofilm (nontarget organisms). This confirms the abovestated need to use functional endpoints associated with fungal communities to explore potential impacts of fungicides on aquatic ecosystems.…”

“…Pesticide concentrations in the water phase were determined by solid-phase extraction on Oasis HLB cartridges followed by liquid chromatography in tandem with mass spectrometry (LC/ MS/MS API 4000, Applied Biosystem, France) as previously described (Kim-Tiam et al 2014b). A total of 43 pesticides were analyzed (see Supplementary Table 2).…”

Improving Toxicity Assessment of Pesticide Mixtures: The Use of Polar Passive Sampling Devices Extracts in Microalgae Toxicity Tests

“…Other single species toxicity tests have been used with cultures diatoms or green algae isolated from benthic or phytoplankton communities (Leboulanger et al, 2001; Fernández-Alba et al, 2002; Gatidou and Thomaidis, 2007; Magnusson et al, 2008; Roubeix et al, 2011b; Larras et al, 2013; Kim Tiam et al, 2014a). Toxicity tests at the community level generally aimed at characterizing the community tolerance according to the PICT (Pollution Induced Community Tolerance, Blanck et al, 1988) concept (McClellan et al, 2008; Schmitt-Jansen and Altenburger, 2008; Montuelle et al, 2010; Pesce et al, 2010; Rotter et al, 2011; Tlili et al, 2011a,b; Larras et al, 2016).…”