No abstract

Several monitoring studies have shown that benzoylecgonine (BE) is the main illicit drug residue commonly measured in the aquatic system worldwide. Few studies have investigated the potential toxicity of this molecule towards invertebrate and vertebrate aquatic non-target organisms focusing on effects at low levels of the biological organization, but no one has assessed the consequences at higher ones. Thus, the present study was aimed at investigating the toxicity of a 48-h exposure to two concentrations of BE, similar to those found in aquatic ecosystems (0.5 μg/L and 1.0 μg/L), on the cladoceran Daphnia magna at different levels of the ecological hierarchy. We relied on a multi-level approach focusing on the effects at biochemical/biomolecular (biomarkers), individual (swimming activity) and population (reproduction) levels. We measured the amount of reactive oxygen species and of the activity of antioxidant (SOD, CAT, and GPx) and detoxifying (GST) enzymes to assess if BE exposure can alter the oxidative status of D. magna specimens, while the lipid peroxidation (TBARS) was measured as a marker of oxidative damage. Moreover, we also measured the acetylcholinesterase (AChE) activity because it is strictly related to behavioral changes in aquatic organisms. Changes in swimming behavior were investigated by a video tracking analysis, while the consequences on reproduction were assessed by a chronic toxicity test. Our results showed that BE concentrations similar to those found in aquatic ecosystems induced oxidative stress and inhibited AChE activity, affecting swimming behavior and the reproduction of Daphnia magna individuals.

Concentrations in fish of per‐ and polyfluoroalkyl substances (PFAS) were reported for 7 deep lakes in the European subalpine area: Lakes Geneva, Lugano, Maggiore, Iseo, Como, Garda, and Mergozzo; one shallow lowland lake (Varese); and 2 high‐altitude alpine lakes (>2000 m a.s.l). Fillets and, in selected cases, other body fractions (viscera, liver, and residual carcass) from 8 fish species were analyzed. The possibility of harmonizing the monitoring protocols was tested. Results suggest that the sampling season is not critical for PFASs and the total protein content cannot be used for normalization of tissue concentrations because PFASs bind to specific proteins. Moreover, the polar lipid content could be used to reduce the variability of PFAS concentrations in phospholipid rich fractions of fish such as viscera and carcass. The data comparison and analysis show that the PFAS contamination in lake fish is generally correlated with the degree of urbanization of the lake catchment; however, it is sometimes difficult to compare absolute concentrations in lake fish because the lake hydro‐morphological characteristics play a substantial role in determining the chemical concentrations of persistent and mobile contaminants. Environ Toxicol Chem 2021;40:658–676. © 2020 SETAC

A growing number of studies have highlighted the contamination and the effects towards organisms of diverse microplastics (µPs) in the marine environment. Surprisingly, although the main sources of µPs for marine environments are inland surface waters, the information on the occurrence and the effects of µPs in freshwater ecosystems is still scant. Thus, the aim of the present work is to investigate the ingestion and possible adverse effects due to the exposure to polystyrene µPs (PSµPs; Ø = 3 µm) on tadpoles of the Amphibian Xenopus laevis. Larvae at the developmental stage 36, prior to mouth opening, were exposed under semi-static conditions to 0.125, 1.25, and 12.5 µg/mL of PSµPs, and allowed to develop until stage 46. At the end of the exposure, the digestive tract and the gills from exposed and control tadpoles were microscopically examined, as well as changes in body growth and swimming activity. PSµPs were observed in tadpoles' digestive tract, but not in the gills, from each tested concentration. However, neither body growth nor swimming activity were affected by PSµPs exposure. Our results demonstrated that PSµPs can be ingested by tadpoles, but they did not alter X. laevis development and swimming behavior at least during early-life stages, also at high, unrealistic concentrations.

Fluoxetine (FLX) is one of the main antidepressants used worldwide. After human use FLX enters the aquatic ecosystems, where it has commonly detected in the high ng/L concentration range. Several investigations have shown that exposure to different concentrations of FLX caused different adverse effects towards a number of aquatic species. However, the information on the onset and the relationship between molecular and behavioral FLX-induced effects remains scant. The aim of this study was to assess the effects induced by two FLX concentrations, namely 50 ng/L and 500 ng/L, on swimming activity of zebrafish (Danio rerio) larvae at 96 hours post fertilization (hpf) and to investigate if such behavioral effects were related to modulation of the expression of oxidative stressrelated (sod1, sod2, cat, gpxa and gst), stress and anxiety-related (oxtl, prl2, npy and ucn3l) genes, and genes encoding for the transporters of the main neurotransmitters (slc6a3, slc6a4a, slc6a4b, slc6a11). Fluoxetine exposure altered the swimming behavior of larvae, as shown by the reduction of the distance traveled by treated larvae in response to an external stimulus. Such behavioral change was related, at molecular level, to an enhanced expression of sod1, cat and gpxa, suggesting an overproduction of pro-oxidant molecules. In addition, FLX modulated the expression of oxtl, slc6a4a, slc6a4b and slc6a11, suggesting its capability to affect anxiety-and neurotransmitter-related genes.