Multi-biomarker responses in fish (Jenynsia multidentata) to assess the impact of pollution in rivers with mixtures of environmental contaminants

Abstract

Aquatic biotas frequently inhabit a multi-stressor environment that affects their structure and function. The hypothesis of this work is that differential responses at different levels of organization will be found in J. multidentata exposed to the multi-stressor context of the Ctalamochita River (Córdoba, Argentina), and that those responses will be more pronounced in sites impacted by anthropic activity (cultivated and industrial areas, city settlements). The study was carried out at four sites along the Ctalamochita River, during the wet and the dry seasons. A seven-day active sampling used caged fish. After exposure, biomarker levels were measured at individual (somatic indexes, behavioral parameters), histological (semi-quantitative indexes in gills and liver) and biochemical (oxidative stress, Acetyl- and butyrylcholinesterase enzymes) levels. The biomarkers had an individually differential response depending on the hydrological seasons, the histological biomarkers (increased histopathological gill and total indexes) being more sensitive during the wet season and the biochemical and behavioral (increased catalase in liver, increased AChE and BChE in muscle, time spent in the lateral section of the tank) during the dry season. Multivariate analysis demonstrated our hypothesis that contamination of the Ctalamochita River occurs in sites impacted by anthropic activity.