Chl-a fluorescence parameters as biomarkers of metal toxicity in fluvial biofilms: an experimental study

Abstract

A study was carried out to evaluate the sensitivity of different chlorophyll-a (chl-a) fluorescence parameters measured in freshwater biofilms as metal pollution biomarkers of short-and long-term metal exposures at environmentally realistic concentrations. A microcosm experiment was performed using indoor channels. Mature biofilms were exposed from hours to weeks to three different treatments: NoMetal, Zn (400 lg l -1 ); and Zn plus Cd (400 lg l -1 and 20 lg l -1 , respectively). Metal concentration was based on a real case study: the Riou-Mort River (France). Biofilms exposed to Zn bioaccumulated similar Zn contents per dry weight to those exposed to the mixture (Zn plus Cd) causing a similar inhibition of the effective quantum yield ðU 0 M Þ during the first hours of exposure. A reduction of the algal biomass, a shift in the community composition (a high reduction of diatoms), a reduction of the maximal quantum yield (U M ) and a strong reduction of non-photochemical quenching (NPQ) were observed from day 14 until the end of the experiment (35 days). The results indicate that the effects of the metal mixture present in the Riou-Mort on biofilms could be attributed to Zn toxicity. The use of a set of chl-a fluorescence measurements, including photochemical and NPQ parameters, are recommended as a reliable biomarker tool box to evaluate both short-and long-term effects of metals on biofilms containing oxygenic photoautotrophs, suggesting its use in field applications.

Arsenic toxicity effects on microbial communities and nutrient cycling in indoor experimental channels mimicking a fluvial system

“…Overall, As-exposed periphytic biofilm accumulated 48% less biomass than controls with a reduction of diatom growth by 32.1%. Several studies showed that toxicants inhibit algal photosynthesis (Barranguet et al, 2003;Pesce et al, 2010;Corcoll et al, 2011) and that metals may selectively affect diatoms (Bonet Sánchez, 2013;Corcoll et al, 2011;Serra et al, 2010). Clearly acute toxicity effects of As were observed on the photosynthetic efficiency of diatoms and cyanobacteria (Fig.…”

“…Biofilms can be used as warning systems for the detection of the effects of toxicants on aquatic systems due to the sensitivity and integration of a large diversity of physiological responses of the species constituting the biofilm (Sabater et al, 2007;Lear et al, 2012;Burns and Ryder, 2001). Several studies have highlighted biofilm sensitivity to a large panel of toxicants, such as metals (e.g., Serra et al, 2010;Corcoll et al, 2011;Bonet et al, 2012), herbicides (Guasch et al, 2003;Pesce et al, 2008), and pharmaceuticals (Proia et al, 2011(Proia et al, , 2013Corcoll et al, 2014). The effects of arsenic on biofilm communities and the role of biofilm in the adsorption, uptake and/or transformation of arsenic have been recently investigated (Rodriguez Castro et al, 2014).…”

Effects of flow intermittency and pharmaceutical exposure on the structure and metabolism of stream biofilms

“…Further, differences in sensitivity between autotrophs and heterotrophs to chemicals (Tlili et al, 2011), and the occurrence of indirect effects between biofilm components (Ricart et al, 2009) make prediction of pharmaceutical effects difficult. Even though links between carbamazepine accumulation and toxicity have been reported in algal monocultures (Vernouillet et al, 2010), there are no evidences that pharmaceutical bioaccumulation can enhance their effect in biofilms, in the way observed for other pollutants (Morin et al, 2008;Corcoll et al, 2011).…”

Tolerância de mamona a zinco avaliada por fluorescência de clorofila e nutrição das plantas

“…A fluorescência de clorofila é caracterizada por um pico máximo na região vermelha (680-700 ηm), que é atribuído ao PSII; e outro na região vermelha distante (730-740 ηm), correspondente ao PSI. Essa fluorescência pode ser uma ferramenta potencial para avaliar a contaminação em ecossistemas causada por metais pesados em plantas, pois consegue detectar alterações no aparato fotossintético (Corcoll et al, 2011;. Essa técnica é não invasiva e pode revelar alterações nas membranas dos cloroplastos resultantes do funcionamento anormal do aparato bioquímico (Joshi & Mohanty, 2004).…”