Evaluation of the Acute Effects of Arsenic on Adults of the Neotropical Native Fish Cnesterodon decemmaculatus Using a Set of Biomarkers

Environmental Health in the Upper-Middle Luján River Basin from a multi-biomarker approach

The objectives of this study were to evaluate the ecophysiological state of the biota using a set of biomarkers in the upper-middle Luján River. To this aim, we collected adult Cnesterodon decemmaculatus fish, biofilm and water at three sampling sites in the upper-middle Luján River (S1: rural area, S2: Luján City and S3: urban area after passing Lujan City). For each site we determined physicochemical variables, heavy metal concentration in water, 19 biomarkers in fish (morphometric, histological, genotoxic, oxidative stress, metabolic and neurotoxic) and six biomarkers in biofilm (oxidative stress and extracellular enzyme). Additionally, we compared the responses of fish and biofilm with those of laboratory controls obtained from outdoor cultures. Our results indicated increased heavy metal concentration at all sites, mainly As and Cd, and decreased dissolved oxygen at S1 and S3. In fish, genotoxic biomarkers showed significant differences with respect to the control. The comet assay indicated damage in fish at the urbanized sites (S2 and S3) and an increased frequency of erythrocytes with nuclear aberrations at all sites. The CEA index (cellular energy allocation), calculated from the metabolic biomarkers and lipid concentration were significantly increased at S1. The gill damage evaluated histologically and with three indices indicated severe damage at all sites. Gills showed thickened primary and secondary lamellae and fusion of filaments at all sites, but a significant increase in mucous cells was only found at S1 and S3. Biofilm showed increased values of extracellular enzymes (β-glucosidase and alkaline phosphatase, lipid peroxidation and oxidative stress enzymes (i.e., catalase) at S3. These results are novel in that they incorporated laboratory controls allowing for comparisons with fish and biofilm from the field. They provided information on the status of a fish population and biofilm community, indicating the negative effect of river water deterioration on the tested organisms. Moreover, results showed what biomarkers were most sensitive for each biological sample.

Poison in the water: Arsenic's silent assault on fish health

Arsenic occurs across the world in freshwater and marine environments, menacing the survival of aquatic organisms. Organic and inorganic forms of this substance can be found, in which the inorganic form is more hazardous than the organic form. Most aquatic bodies contain inorganic arsenic species, but organic species are believed to be the dominant form of arsenic in the majority of fish. Natural and anthropogenic both are the sources of water contamination with arsenic. Its bioaccumulation and transfer from one trophic level to another in the aquatic food chain make arsenic a vital environmental issue. Continuous exposure to low concentrations of arsenic in aquatic organisms including fish leads to its bioaccumulation, which may affect organisms of higher trophic levels including large fishes or humans. Humans can be exposed to arsenic through the consumption of fish contaminated with arsenic. Hence, the present review facilitates our understanding about sources of arsenic, its bioaccumulation, food chain transfer, and its effect on the fish health. Also, "Poison in the Water: Arsenic's Silent Assault on Fish Health" serves as a wake-up call to recognize the pressing need to address arsenic contamination in water bodies. By understanding its devastating impact on fish health, we can strive to implement sustainable practices and policies that safeguard our precious aquatic environments and ensure the well-being of both wildlife and human communities that depend on them.

Exposure to low-dose arsenic caused teratogenicity and upregulation of proinflammatory cytokines in zebrafish embryos

Arsenic is currently ranked as the most toxicant on the ATSDR 2015 substance priority list and is categorised as a Group 1 human carcinogen. Biota that are subjected to inorganic arsenicals through food, water, occupational or medical exposure pose a risk to the environment and to human health. The present study was carried out to investigate the toxicity caused by inorganic arsenic. After fertilisation, zebrafish embryos were exposed to sodium arsenite at several concentrations (100 nM to 600 nM) for 24 to 96 hpf. The indicators of teratogenicity (hatchability, morphological abnormalities, mortality), behavioural modifications (touch induced escape response (TIER), startle response (SR) and turning behaviour (TB)), biochemical testing (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione S transferase (GST)) and the expressions of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) were investigated. The aforementioned parameters were found to be altered in embryos exposed to sodium arsenite. According to the findings of the current study, even a low dose of inorganic arsenic compound caused teratogenicity, behavioural abnormalities, altered enzyme activities and the expression of proinflammatory cytokines in zebrafish embryos.