Ingestion of tannery effluent as a risk factor to the health of birds: A toxicological study using Coturnix coturnix japonica as a model system.

Tannery industries generate large amounts of tannery effluents (TE), which have been considered highly toxic to various groups of animals. However, the identification and characterization of the impact of this mix of pollutants on birds is still highly incipient. So, our goal was to evaluate the possible biological changes of Coturnix coturnix japonica, exposed for 45 days, to different dilutions of TE (1.4%, 3.1% and 6.5%), using behavioural biomarkers, mutagenics and egg production. When submitted to the behavioural tests, quails that ingested TE presented behaviour compatible with an anxiolytic effect in the open field test; absence of emotional reactivity in the object recognition test; reduced rates of predation of Tenebrio molitor larvae (potential prey); as well as an anti-predatory defensive response deficit when confronted, especially with Felis catus males (potential predator). In addition, we observed increased biomass of the liver, increased feed conversion index and lower feed efficiency index; mutagenic effect of TE (inferred by the increase of nuclear erythrocyte abnormalities); reduced productive performance and egg quality, in addition to different staining patterns of the eggs produced by quails from the control group. Therefore, our study confirms the toxicity of TE in C. coturnix japonica, even in small dilutions. While behavioural changes demonstrate the neurotoxic potential of the pollutant, the other alterations suggest that the mechanisms of action of its chemical constituents are not selective, that is, they act systemically, acting synergistic, antagonistic or additively, causing harmful effects in animals.

The effects of predicted environmentally relevant concentrations of ZnO nanoparticles on the behavior of Gallus gallus domesticus (Phasianidae) chicks.

The toxicity of ZnO nanoparticles (NPs) has been the subject of several investigations; however, concentrations much higher than the ones potentially found in the environment are often tested. In addition, groups of animals such as birds have not been used as model in studies in this field, fact that creates an important ecotoxicological gap in them. The aim of the present study is to investigate the effects of the exposure to environmentally relevant concentrations of ZnO nanoparticles on the anti-predatory behavior of chicks (Gallus gallus domesticus). The test animals were daily exposed to an environmentally relevant concentration of ZnO nanoparticles (0.245 mg kg-1) and to a toxic concentration of it (245.26 mg kg-1) through intraperitoneal injection for two days. We set a control group for comparison purposes. According to our results, ZnO nanoparticles did not affect the locomotor activity of, and did not cause anxiolytic or anxiogenic effect on, birds in the open field test. However, based on the lowest cluster score recorded during the social aggregation test, chicks exposed to ZnO nanoparticles failed to recognize the grunt of a hawk (Rupornis magnirostris) as predatory threat. Only birds in the control group recognized the test snake (Pantherophis guttatus) as potential predator. The higher Zn concentration in the brains of animals exposed to ZnO nanoparticles evidenced the capacity of these nanomaterials to cross the blood-brain barrier, even at low concentrations. This blood-brain barrier crossing could have affected the structures or neuronal mechanisms that modulate the defensive response of birds. Assumingly, even the minimal exposure to low concentrations of ZnO nanoparticles can affect birds. Our outcomes corroborate previous studies about the biological risks of water surface contamination by metal-based nanomaterials.