title: Behavioral response of juvenile rainbow trout exposed to an herbicide mixture.
abstract: Fish are capable of sensing water-borne chemicals at sub-lethal concentrations. Inadequate behavioral responses to physiological and environmental stimuli owing to adverse effects of aquatic toxicants can have serious implications for survival. In this study we exposed juvenile rainbow trout (Oncorhynchus mykiss) during 5 days to a low-concentration mixture of three co-occurring herbicides: atrazine, linuron and metolachlor, at maximum concentrations of 4.5, 4.9 and 13.4 μg L(-1), respectively. Our hypothesis was that fish behavior - swimming activity and interactions between individuals - would be modified due to exposure to the mixture. We studied these behaviors by observing fish twice-daily throughout the exposure period at 30-s intervals for 5 min, registering the vertical distribution of fish in the water column and the number of agoniztic acts between all individuals. Fish exposed to the mixture of herbicides were hypoactive and spent more time in the lower parts of the aquaria in comparison to non-exposed controls, reflecting inhibited swimming activity. Average swimming height of exposed fish decreased significantly with the number of agoniztic acts, whilst in control groups there was no significant relationship between the two behaviors. Overall, behavior of fish exposed for a short time to the herbicide mixture was altered in comparison to control-fish behavior. The behavioral endpoints chosen here were easily observed, simple to quantify, and of ecological relevance.
authors.affiliation: Laboratoire Evolution et Diversité Biologique, Université Paul Sabatier/CNRS, 118 Av. de Rangueil, 31062 Toulouse, France; Escuela de Ciencias Agrícolas y Ambientales, Pontificia Universidad Católica del Ecuador-Sede Ibarra, Ibarra, Ecuador, Av.Padre Aurelio Espinosa Polit, Ibarra, Ecuador. Electronic address: candida.shinn@gmail.com.
authors.forename: Candida
authors.initials: C
authors.lastname: Shinn
authors.affiliation: CIMAR/CIIMAR, Interdisciplinary Centre for Marine and Environmental Research, University of Porto, Rua dos Bragas no. 289, 4050-123 Porto, Portugal. Electronic address: santos@ciimar.up.pt.
authors.forename: Miguel Machado
authors.initials: MM
authors.lastname: Santos
authors.affiliation: Laboratoire Evolution et Diversité Biologique, Université Paul Sabatier/CNRS, 118 Av. de Rangueil, 31062 Toulouse, France. Electronic address: sovannarath.lek@univ-tlse3.fr.
authors.forename: Sovan
authors.initials: S
authors.lastname: Lek
authors.affiliation: Laboratoire Evolution et Diversité Biologique, Université Paul Sabatier/CNRS, 118 Av. de Rangueil, 31062 Toulouse, France. Electronic address: gael.grenouillet@univ-tlse3.fr.
authors.forename: Gaël
authors.initials: G
authors.lastname: Grenouillet
mesh_terms: D000081:Acetamides / Q000633:toxicity; D000818:Animals; D001280:Atrazine / Q000633:toxicity; D006540:Herbicides / Q000633:toxicity*; D008044:Linuron / Q000633:toxicity; D009043:Motor Activity / Q000187:drug effects*; D017686:Oncorhynchus mykiss / Q000502:physiology*; D011897:Random Allocation; D013550:Swimming; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000081:Acetamides; D006540:Herbicides; D014874:Water Pollutants, Chemical; D008044:Linuron; D001280:Atrazine; C051786:metolachlor
keywords: Aggression; Herbicides; Juvenile trout; Mixture; Swimming activity