Embryo toxicity assay in the fish species Rhamdia quelen (Teleostei, Heptaridae) to assess water quality in the Upper Iguaçu basin (Parana, Brazil)

Abstract

The Iguaçu River is one of the largest and most important rivers in the Southern of Brazil. The Upper Iguaçu Basin is responsible for water supply (80%) of the Metropolitan Region of Curitiba (MRC). After crossing a large urban region, the river is polluted by domestic and industrial sewage, but despite of that few ecotoxicological studies have been performed in order to evaluate the water quality from Iguaçu River. The aim of the present study was to investigate the risk of exposure of Iguaçu water to biota and also human population. In this terms, was utilized the survival effect and the morphological deformities in larval embryos of Rhamdia quelen, a native South America species. The results showed a high level of pollution in all studied sites along the Upper Iguaçu River including PAHs and toxic metals such as lead. The lethal and non-lethal effects described in earlier stages of development suggest an elevated risk to biota. This data was corroborated by the theoretical model, showing that the pollutants present in water from Iguaçu River may further reduce the fish population density including risk of local extinction. The present study reflect the needs to conduct in-depth research to evaluate the real impact of human activities on the endemic fish biota of Iguaçu River including the risk for human populations.

Use of fish embryo biomarkers for the evaluation of mazut toxicity in marine environment

“…Studies have been performed using the different life stages of Japanese medaka (Oryzias latipes), fathead minnow (Pimephales promelas), goldfish (Carassius auratus), rainbow trout (Oncorhynchus mykiss), etc. The life cycle stages of fish (through the embryo-larval stage) may represent a way to establish definitive testing strategies and will provide another option for the acute testing of juvenile and adult fish (Heintz et al 1999;Embry et al 2010;de Andrade et al 2018). Embryos and larvae have important roles in the life cycle of marine organisms as during this phase there are dramatic morphological and physiological changes that lead to the adult form.…”

“…Previously, the researchers have reported the negative impact of oil contamination on fish eggs and larvae (Rudneva 2014;Mu et al 2018;Pereira et al 2018;Hansen et al 2018). Oil induced a series of abnormalities during fish embryonic development, increased embryo mortality at various stages, changed the morphogenesis and organ formation, and modified the responses of the defense antioxidant and immune systems (Pauka et al 2011;Mu et al 2018;de Andrade et al 2018).…”