title: Liver ethoxyresorufin-O-deethylase and brain acetylcholinesterase in two freshwater fish species of South America; the effects of seasonal variability on study design for biomonitoring.
abstract: Responses at low levels of biological organization to evaluate environmental changes and water quality have been used for many years. South America is no different, and recently biochemical endpoints in fish have been used to assess the impacts of industrial and sewage effluents on wild fish populations. For Chilean native freshwater fish, basic biological data is scarce and data on 7-ethoxyresorufin-O-deethylase (EROD) and Acetylcholinesterase (AChE) activity is practically absent. Moreover, extensive variation in these two biochemical endpoints exists among species and seasons. In this article we evaluate seasonal variation in liver EROD and brain AChE activities in Trichomycterus areolatus and Percilia gillissi, two widely distributed native freshwater fish species in central Chile. We observed a marked seasonality in hepatic EROD activity in both species, with maximums for P. gillissi during winter months and sex differences in February, July, August and December. T. areolatus showed no sex differences, and peaks in EROD activity in the middle of summer, winter and late spring. Species differences in EROD activity were observed with activity being 1-2 orders of magnitude higher in P. gillissi compared to T. areolatus. Scarce seasonal variation and no sex related differences in brain AChE for both species were observed. Multivariate analysis (PCA) indicated that physical water quality parameters had some degree of responsibility for the seasonal responses found. The seasonal variability data of these biochemical endpoints were used to optimize study design for future monitoring programs, planning timing of sampling, increasing statistical power by collecting specific sample sizes required.
authors.affiliation: Unidad de Sistemas Acuáticos, Centro de Ciencias Ambientales EULA-Chile, Universidad de Concepción, Concepción, Chile. gchiang@udec.cl
authors.forename: Gustavo
authors.initials: G
authors.lastname: Chiang
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Munkittrick
authors.forename: Roberto
authors.initials: R
authors.lastname: Urrutia
authors.forename: Cesiah
authors.initials: C
authors.lastname: Concha
authors.forename: Meyling
authors.initials: M
authors.lastname: Rivas
authors.forename: Mauricio
authors.initials: M
authors.lastname: Diaz-Jaramillo
authors.forename: Ricardo
authors.initials: R
authors.lastname: Barra
mesh_terms: D000110:Acetylcholinesterase / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002677:Chile; D019363:Cytochrome P-450 CYP1A1 / Q000032:analysis / Q000378:metabolism*; D004784:Environmental Monitoring / Q000592:standards*; D005260:Female; D005399:Fishes / Q000378:metabolism*; D005618:Fresh Water; D008099:Liver / Q000378:metabolism; D008297:Male; D012621:Seasons; D012737:Sex Factors
chemical_list: D019363:Cytochrome P-450 CYP1A1; D000110:Acetylcholinesterase