title: Biochemical and behavioral responses of the Amazonian fish Colossoma macropomum to crude oil: the effect of oil layer on water surface.
abstract: The largest Brazilian terrestrial province of petroleum mining is located at the margins of Urucu River, Amazonas. Mined crude oil is transported along 400 km across Solimões River to be refined in Manaus. Thus, the main goal of this study was to evaluate the effects of crude oil exposure on biochemical, physiological and behavioral parameters of juveniles of the Amazonian fish tambaqui (Colossoma macropomum). The toxicity of water-soluble and insoluble oil fractions and the influence of a layer formed by the oil on the water surface from low and high concentrations of crude oil were analyzed. The results showed a strong physical effect of oil at the water surface and a significant effect on fish behavior. Swimming time and response to alarm substance decreased when fish was exposed for just one day to water insoluble fraction, and remain lower after 30 days of exposure, compared to control. Chronic exposure to water insoluble fraction of the inert oil also affected these two parameters. Critical swimming velocity decreased in fish exposed to both crude and inert oil water insoluble fraction. These reductions are possibly related to a decrease in aerobic capacity. Only exposure to high concentrations of petroleum water-soluble fractions induced transient alterations of the analyzed parameters. The exposure of fish to low and high concentrations of water insoluble fraction of Urucu oil caused a reduction of responses to alarm substance, spontaneous swimming activity and swimming capacity (Ucrit), decreased activity of acetylcholinesterase, and increased activity of alkaline phosphatase. Severe hypertrophy of lamellar epithelium and extensive lamellar fusion of the gills were also observed. Overall, these results show significant behavioral and physiological changes caused by the oil layer on the water surface, which means that toxicity of petroleum produced by its chemical components is, in fact, in this fish species, enhanced by the presence of an oil phase as a physical barrier.
authors.affiliation: Brazilian National Institute for Research in the Amazon, Laboratory of Ecophysiology and Molecular Evolution, Ave André Araújo 2936, 69060-001, Manaus, AM, Brazil. Electronic address: daia.kochhann@gmail.com.
authors.forename: Daiani
authors.initials: D
authors.lastname: Kochhann
authors.affiliation: Brazilian National Institute for Research in the Amazon, Laboratory of Ecophysiology and Molecular Evolution, Ave André Araújo 2936, 69060-001, Manaus, AM, Brazil.
authors.forename: Manoela
authors.initials: M
authors.lastname: Meyersieck Jardim
authors.affiliation: Brazilian National Institute for Research in the Amazon, Laboratory of Ecophysiology and Molecular Evolution, Ave André Araújo 2936, 69060-001, Manaus, AM, Brazil.
authors.forename: Fabíola Xochilt
authors.initials: FX
authors.lastname: Valdez Domingos
authors.affiliation: Brazilian National Institute for Research in the Amazon, Laboratory of Ecophysiology and Molecular Evolution, Ave André Araújo 2936, 69060-001, Manaus, AM, Brazil.
authors.forename: Adalberto Luis
authors.initials: AL
authors.lastname: Val
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D001938:Brazil; D060125:Characiformes / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D005880:Gills / Q000187:drug effects / Q000473:pathology; D010578:Petroleum / Q000633:toxicity*; D045483:Rivers; D013550:Swimming; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010578:Petroleum; D014874:Water Pollutants, Chemical; D000110:Acetylcholinesterase
keywords: Acetylcholinesterase; Behavior; Biomarkers; Multibiomarker; Swimming; Tambaqui