Can a low concentration of an organophosphate insecticide cause negative effects on an aquatic macrophyte? Exposure of Potamogeton pusillus at environmentally relevant chlorpyrifos concentrations

Abstract

The contamination of the aquatic environments with organophosphorus pesticides may affect non-target organisms. The aim of this study was to evaluate the toxic effects of the insecticide chlorpyrifos (CPF) at environmental concentrations on the freshwater macrophyte Potamogeton pusillus belonging to a genus of worldwide distribution. For this purpose, individuals were exposed from 3.5 to 94.5 ng of CPF L À1 for 96 h. A battery of biochemical responses including bioaccumulation, defense and damage biomarkers were measured in leaf, stem and root. Even when CPF was not detected in the macrophyte tissues, our results showed that this insecticide promotes oxidative stress and biomolecule damages in P. pusillus after acute exposure. Significant response of biomarkers was observed from the lowest tested concentration (3.5 ng CPF L À1). Oxidative stress was evidenced by increased lipid peroxidation and antioxidant enzymatic activation, including changes in superoxide dismutase, guaiacol peroxidase and glutathione peroxidase activities, especially in leaf. Also, a significant decrease in chlorophyll a and b contents was observed mainly in leaf. Finally, with some selected biomarkers, an Integrated Biomarker Response index was calculated showing a dose-response relationship with CPF exposure. Previous studies reported that herbicides and organophosphorus pesticides are responsible for several effects on photosynthetic systems but at higher exposure concentrations than the tested in this study. These results draw attention to the need for more studies in toxic effects of insecticides on aquatic macrophytes, at low concentrations and different biological levels, since the protection guidelines would not be preserving these species.

An integrated biomarker response study explains more than the sum of the parts: Oxidative stress in the fish Australoheros facetus exposed to imidacloprid

“…Despite the fact that in the last years there was an increase of the use of IBR indices both in plant and animals in laboratory experiments (Bertrand et al, 2016b(Bertrand et al, , 2017 or field studies (Santos et al, 2016), few of them are applied for defining processes or modes of toxicity. For example, for mussels IBR indices were developed for inmunotoxical (Auffret et al, 2006) and lysosomal biomarkers (Izagirre and Marigomez, 2009) to evaluate contaminated sites.…”

Usefulness of a freshwater macrophyte (Potamogeton pusillus) for an environmental risk assessment in a multi-source contaminated basin.

“…org). Previous studies reported Potamogeton capacity to evidence pollutants exposure under laboratory conditions (Bertrand et al, 2016(Bertrand et al, , 2017Costa et al, 2018;Monferr an et al, 2009). In a similar way, others authors described the usefulness of Potamogeton in passive monitoring programs, showing to be useful as a biological indicator while evaluating environmental deterioration (Demirezen and Aksoy, 2004;Harguinteguy et al, 2016;Munteanu and Munteanu, 2007).…”

“…Individuals of South American native macrophyte, P. pusillus, were collected from a reference site located in a tributary (Yuspe River) of the Suquía River upper basin based on an earlier study (Bertrand et al, 2017). Organisms were acclimated during two weeks in glass aquaria filled with 10% Hoagland's solution, sediments (1/4) from the same sampling area, and they were maintained at 25 ± 1 C under a natural light: dark regime.…”

“…Organisms were exposed for four days in two sampling campaigns. The exposure period was selected in accordance to previous laboratory testing (Bertrand et al, 2016(Bertrand et al, , 2017. Sampling dates were chosen to take into account the rain seasonality and thermal variation for the proposed basin: cold (July, CP) and warm periods (December, WP), according to previous studies (SM, Table SM2; Bertrand et al, 2018;O'Mill, 2012).…”

“…Enzyme extracts of P. pusillus were prepared according to Bertrand et al (2017). After removal of cell debris (10 min at 13,000 g, 4 C), the membrane fraction of the extracts were separated by centrifugation at 105,000 g for 60 min.…”