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

Abstract

Streams located in vineyard areas are particularly exposed to mixtures of dissolved and particulate contaminants such as metals and organic pesticides. In this context, phototrophic biofilms are increasingly used as indicators of river water contaminations through pollution-induced community tolerance (PICT) assessments based on short-term toxicity tests with individual or mixtures of toxicants. We conducted a laboratory experiment to evaluate the relative influence of the dissolved and particulate fractions on the effects of metals and pesticides on phototrophic biofilms in a context of contamination from a vineyard watershed. Three sets of artificial channels were supplied with (i) unfiltered water from a stream reference site, (ii) unfiltered water from a stream contaminated site, and (iii) filtered water (0.45 μm) from the same contaminated site. Biofilm growth, diatom community structure, and dissolved toxicant concentrations differed slightly between channels supplied with unfiltered or filtered water from the contaminated site. However, PICT assessments with individual toxicants or mixtures of toxicants extracted from passive samplers suggested no significant difference in tolerance to metals and organic pesticides between phototrophic communities supplied with unfiltered or filtered contaminated water. Our results confirm the use of extracts from passive samplers as a promising approach in short-term toxicity tests to characterize impacts of contamination on aquatic communities.

Micropollutant-induced tolerance of in situ periphyton: Establishing causality in wastewater-impacted streams

“…They can provide an integrative picture of pollutants over a period of time, allowing for quantification of average concentrations to which organisms have been exposed (Alvarez et al 2008). Indeed, some studies have used this approach with periphyton grown in indoor microcosms, which were chronically exposed to extracts from passive samplers that had been deployed in streams contaminated with pesticides (Foulquier et al 2015, Kim Tiam et al 2015, Morin et al 2012. Furthermore, Pesce et al (2011) examined the tolerance to passive sampler extracts of in situ periphyton from a stream with a gradient of agricultural pollution.…”

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

“…Dose-response curves performed with PE sampled at the downstream (Ruiné and Morcille) or contaminated (Trec) site allowed to evidence differences in the sensitivity to PE mixtures depending on the origin of the biofilms. Apart from Foulquier et al (2015), significant higher tolerance was measured for biofilms originated from the most contaminated site (noted contaminated for Trec river and downstream for Morcille river in Table 4). These results confirmed the relevance of using PE as “blackbox” complex contaminants to reveal biofilm exposure history.…”

“…The works based on the PICT concept, using PE considered as a “blackbox” of contaminants, allowed to highlight previous exposure of the biofilms, or not, to these cocktails. The ecological significance of combined PICT and PE approaches proved to be relevant, for biofilms sampled from rivers presenting different contamination profiles in term of concentrations and/or nature of compounds detected (Pesce et al, 2011; Morin et al, 2012c; Kim Tiam et al, 2014b; Foulquier et al, 2015). The PICT responses of field biofilms were compared in three study sites subjected to distinct kinds of agricultural pressure (increasing vineyard occupation from upstream to downstream in Morcille river, distinct land use along the Ruiné river and growing cereal crops at the Trec river; Table 4).…”