Previous studies have shown the effect of surface coatings on biofouling; however, they did not take into account the interaction of the micro and macrofouling communities, the effect of substrate orientation and the zooplankton-zoobenthic coupling together. Therefore, the aim of this study was to evaluate the effect of Zn- and Cu₂O-based coatings on micro and macrofouling on steel surfaces, while also observing the role of substrate orientation and zooplankton supply. An experiment was carried out in the Patos Lagoon Estuary in southern Brazil for three months between spring and summer, where ASTM-36 steel plates represented different coatings (Zn- and/or Cu₂O-based) and orientations (vertical and horizontal). To assess the zooplankton supply, sampling was carried out weekly using a 200 μm plankton net. Zn-based coating positively affected microfouling density compared to uncoated surfaces. The same pattern was observed with macrofouling, associated with vagile fauna preference, which represented 70% of the settled macrofoulers. Cu₂O-based antifouling painted surfaces showed the highest microfouling density inhibition, while Zn + Cu₂O-based coating did not affect the bacteria adhesion but showed lower density compared to Zn-based coating alone. The coatings combination showed the highest invertebrate inhibition. In this way, the macrofouling community was more sensitive than microfouling was to the antifouling coatings tested. The substrate orientation only affected macrofouling, horizontal surfaces being more attractive than vertical. Meroplankton, tychoplankton and holoplankton were recorded on the surfaces, although their representation in plankton was not proportional to the recruits recorded on the substrates. This was probably due to fast dispersion, the interactions of other factors and/or ecological succession stage. Surface coating, substrate orientation, and zooplankton supply interacted with the biofouling process on steel in different ways depending on the organism evaluated. Therefore, copper oxide- and zinc-based coatings were not suitable as coatings to avoid the total biofouling establishment.

As a new type of pollutant, fluoroquinolones (FQs) antibiotics are ubiquitous in environment and have some threat to human health and ecological environment. Their ecological toxicity to the environment urgently need to be assessed. Therefore, we firstly explored the toxic effects and possible mechanism of cardiovascular toxicity induced by gatifloxacin (GTFX) and ciprofloxacin (CPFX) using zebrafish model. After 24 h exposure, the zebrafish treated with GTFX showed pericardial edema which was further investigated by histopathological examination, while CPFX exposure did not induce morphological abnormalities. However, both of them induced cardiac dysfunction, such as decreased heart rate and cardiac output which was showed a positive correlation with the concentration. To better understand the possible molecular mechanisms underlying cardiovascular toxicity in zebrafish, we investigated the transcriptional level of genes related to calcium signaling pathway and cardiac muscle contraction. The results indicated that the expression of ATPase (atp2a1l) and cardiac troponin C (tnnc1a) genes were significantly inhibited, the expression of calcium channel (cacna1ab) gene showed slight promoted trend after CPFX exposure. For zebrafish treated with GTFX, the expression of atp2a1l genes was also significantly inhibited, while the expression of tnnc1a genes was slightly inhibited and cacna1ab genes expression had no obvious effect. The present study firstly revealed that GTFX exposure can induce morphological and functional abnormalities on the cardiovascular system of zebrafish. Though CPFX exposure did not induce morphological abnormalities, the function of cardiovascular system was still damaged. Mechanistically, this toxicity might result from the pressure of down-regulation of genes associated with calcium signaling pathway and cardiac muscle contraction. The results of this study can provide a valuable theoretical basis for the establishment of FQs environmental quality standards in water environment, environmental drug regulation and risk management.

Lead (Pb) contaminated soil is of particular concern for infants and children due to their susceptibility to exposure, fast metabolic rates and rapidly developing neuronal systems. Determining the bioaccessibility of Pb in soils is critical in human health risk assessments, which can vary due to different soil properties and sources of Pb contamination. In this study, the potential relationships between soil properties and Pb bioaccessibility from various Pb sources including Pb contamination from mining (specifically, Broken Hill), three shooting ranges, a smelter and two industry sites (pottery and battery), were investigated using the Relative Bioavailability Leaching Procedure (RBALP). We found the following: (1) CEC, TOC, sand and silt content, and total Pb were significantly different (p < 0.05) between the two particle size fractions of < 2 mm and < 250 μm; (2) EC, CEC and total Pb were significantly correlated to Pb bioaccessibility (p < 0.05); and (3) soil analyses based on source of Pb demonstrated a strongly significant relationship between Pb bioaccessibility and soil properties (CEC, EC, clay content and total Pb) for mining soils from Broken Hill (r² = 0.86, p < 0.05, n = 18). These results demonstrated the influences of Pb contamination sources, soil properties and particle size fractions on Pb bioaccessibility as well as the prediction of Pb bioaccessibility using soil properties. The findings documented here will help in developing a predictive tool for human health risk assessment and the remediation of Pb contaminated soils.

Selenium (Se) is an essential micronutrient for animals with a relatively narrow margin between essentiality and toxicity. To evaluate Se removal efficiency by a constructed wetland treatment system and its potential eco-risk, a floating-leaved macrophyte system was constructed, consisting of three main trophic levels. Over 21-d treatment, water Se concentration was gradually reduced by 40.40%, while 24.03% and 74.41% of the removed Se were found in the plant Nymphoides sp. and sediment, respectively. Among plant tissues, roots accumulated the highest Se level, although the greatest total Se was found in stems, followed by leaves, roots and rhizomes. X-ray absorption spectroscopy revealed that 82.65% of the absorbed selenite by the plants was biotransformed to other forms, as organo-Se species accounted for 45.38% of the Se retained in the sediment, which was primarily responsible for the entry of Se into the detritus food chain. The proportion of organo-Se compounds increased with trophic levels from sediments to fish, indicating, instead of direct uptake of selenite, the food chain transfer and biotransformation of Se may serve as a key exposure route for Se in aquatic organisms. When exposed to organo-Se compounds, i.e., SeCys and SeMet, the plants, shrimp and fish tended to accumulate more Se. However, the greater trophic transfer factor was obtained for selenate, leading to higher Se levels accumulated in fish. Overall, in addition to key mechanisms involved in Se removal, our research also provides a much better understanding of the potential eco-risk that may be posed by the floating-leaved plant system for bioremediation of Se via food chain transfer and biotransformation, paving the way for a low eco-toxic treatment system for Se remediation.

We previously found that folic acid (FA) attenuated cardiac defects in zebrafish embryos exposed to extractable organic matter (EOM) from PM2.5, but the underlining mechanisms remain to be elucidated. Since DNA methylation is crucial to cardiac development, we hypothesized that EOM-induced aberrant DNA methylation changes could be diminished by FA supplementation. In this study, zebrafish embryos were exposed to EOM in the absence or presence of FA. Genomic-wide DNA methylation analysis identified both DNA hypo- and hyper-methylation changes in CCGG sites in zebrafish embryos exposed to EOM, which were attenuated by FA supplementation. We identified a total of 316 genes with extensive DNA methylation changes in EOM samples but little or no DNA methylation changes in EOM plus FA samples. The genes were involved in critical cellular processes and signaling pathways important for embryo development. In addition, the EOM-decreased SAM/SAH ratio was counteracted by FA supplementation. Furthermore, FA attenuated the EOM-induced changes in the expression of genes involved in the regulation of DNA methylation and in folate biosynthesis. In conclusion, our data suggest that FA supplementation protected zebrafish embryos from the cardiac developmental toxicity of PM2.5 by alleviating EOM-induced DNA methylation changes.

Dichlorvos (2,2-dichlorovinyl-dimethylphosphate), an organophosphorus pesticide used for indoor insect and livestock parasite control, is among the most common commercially available pesticides. However, there are significant concerns over its toxicity, especially due to its relative stability in water, soil, and air. Zebrafish, an important developmental model, has been used for studying the effects of toxic compounds. The aim of this study was to evaluate the exposure to dichlorvos at early life stages (1 h postfertilization - 7 days postfertilization) in the zebrafish and its toxicological effects during the development, through morphological (7 days postfertilization), locomotor and social behavior analysis (7, 14, 30, 70, and 120 days postfertilization). Dichlorvos (1, 5, and 10 mg/L) exposure reduced the body length and heartbeat rate at 7 days postfertilization (dpf), as well as the surface area of the eyes (5 and 10 mg/L). The avoidance behavior test showed a significant decrease in escape responses at 7 (1, 5, and 10 mg/L) and 14 (5 and 10 mg/L) dpf zebrafish. The evaluation of larval exploratory behavior showed a reduction in distance traveled, mean speed (1, 5, and 10 mg/L) and time mobile (10 mg/L) between control and dichlorvos groups. In addition, the analysis performed on adult animals showed that the changes in distance traveled and mean speed remained reduced in 30 (1, 5, and 10 mg/L) and 70 dpf (5 and 10 mg/L), recovering values similar to the control at 120 dpf. The social behavior of zebrafish was not altered by exposure to dichlorvos in the early stages of development. Thus, the exposure to organophosphorus compounds at early stages of development induces an increased susceptibility to behavioral and neuronal changes that could be associated with several neurodegenerative diseases.

Copper oxide nanoparticles (CuO NPs) is one of the most commonly used metal oxide nanoparticles for commercial and industrial products. An increase in the manufacturing and use of the CuO NPs based products has increased the likelihood of their release into the aquatic environment. This has attracted major attention among researchers to explore their impact in human as well as environmental systems. CuO NPs, once released into the environment interact with the biotic and abiotic constituents of the ecosystem. Hence the objective of the study was to provide a holistic understanding of the effect of abiotic factors on the stability and aggregation of CuO NPs and its correlation with their effect on the development of zebrafish embryo. It has been observed that the bioavailability of CuO NPs decrease in presence of humic acid (HA) and heteroagglomeration of CuO NPs occurs with clay minerals. CuO NPs, CuO NPs + HA and CuO NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA with clay showed protective effect on zebrafish embryo development. These findings provide new insights into the interaction of NPs with abiotic factors and combined effects of such complexes on developing zebrafish embryos genetic markers.

The Environmental Quality Standards (EQS) directive was an important improvement of long-term water quality monitoring at the European level, leading to the use of sediments and biota as relevant matrices for assessing priority substances under the European Water Framework directive. Currently, commonly accepted sediment EQS for Hg are missing in Europe. In this study we present a new, tiered approach to deriving sediment quality standards for Hg: the derivation of Predicted No-Effect Concentration (PNEC) from data in the literature, followed by adjusting values at regional scale, using ecological field data (macroinvertebrate community assessment) and field sediment ecotoxicity bioassays. The limited set of effect data available for Hg spiked-sediment ecotoxicity tests has resulted in unreliable PNEC values for sediment quality assessment. Field reference sites (n = 40) where the macroinvertebrate community status was assessed as High or Good were used to define the ecological background and threshold levels in sediments in northern Spain. Sediment QS developed in other areas were not suitable for specific basins in our study area, since they were within the range of our Hg background levels. Temporary sediment Quality Standards (QS) for Hg were developed for the Nalón River basin (where several mining districts occur), using field effect-based approaches such as sediment ecotoxicity data from Tubifex tubifex chronic bioassays and ecological assessment of macroinvertebrate communities. A proposal for Hg quality assessment in freshwater sediments of northern Spain is made based on ecologically relevant QS values, providing benchmark values for No-Effect and Effect Hg sediment concentrations.

The aim of this study was to investigate the long-term effects of a short exposure to natural sediments within the Athabasca oil sand formation to critical stages of embryo-larval development in fathead minnows (Pimephales promelas). Three different sediments were used: Ref sediment from the upper Steepbank River tested at 3 g/L (containing 12.2 ng/g ∑PAHs), and two bitumen-rich sediments tested at 1 and 3 g/L; one from the Ells River (Ells downstream, 6480 ng/g ∑PAHs) and one from the Steepbank River (Stp downstream, 4660 ng/g ∑PAHs). Eggs and larvae were exposed to sediments for 21 days, then transferred to clean water for a 5-month grow-out and recovery period. Larval fish had significantly decreased survival after exposure to 3 g/L sediment from Stp downstream, and decreased growth (length and weight at 16 days post hatch) in Ells and Stp downstream sediments at both 1 and 3 g/L. Decreased tail length was a sensitive endpoint in larval fish exposed to Ells and Stp downstream sediments for 21 days compared to Ref sediment. After the grow-out in clean water, all growth effects from the bitumen-containing sediments recovered, but adult fish from Stp downstream 3 g/L sediment had significant increases in jaw deformities. The study shows the potential for fish to recover from the decreased growth effects caused by sediments containing oil sands-related compounds, but that some effects of the early-life sediment exposure occur later on in adult fish.

Due to the growing concern about the presence of microplastics (MP) in the environment, the number of studies evaluating the toxicity of these small persistent particles on different marine species has increased in recent years. Few studies have addressed their impact on marine phytoplankton, a subject of great concern since they are primary producers of the aquatic food web. The aim of this study is to unravel the cytotoxicity of 2.5 μg mL⁻¹ unlabelled amino-modified polystyrene beads of different sizes (0.5 and 2 μm) on the marine diatom Chaetoceros neogracile. In addition to traditional growth and photosynthesis endpoints, several physiological and biochemical parameters were monitored every 24 h in C. neogracile cells by flow cytometry during their exponential growth (72 h). Dynamic Light Scattering measurements revealed the strong aggregation and the negative charge of the beads assayed in the culture medium, which seemed to minimize particle interaction with cells and potentially associated impacts. Indeed, MP were not attached to the microalgal cell wall, as evidenced by scanning electron micrographs. Cell growth, morphology, photosynthesis, reactive oxygen species levels and membrane potential remained unaltered. However, exposure to MP significantly decreased the cellular esterase activity and the neutral lipid content. Microalgal oil bodies could serve as an energy source for maintaining a healthy cellular status. Thus, MP-exposed cells modulate their energy metabolism to properly acclimate to the stress conditions.