title: Application of artificial photoperiod in fish: a factor that increases susceptibility to infectious diseases?
abstract: This paper describes and evaluates the mortality associated with the potential stressor effect induced by application of artificial photoperiods in rainbow trout (Oncorhynchus mykiss). After application of artificial photoperiods, high mortalities of trout subjected to this management were recorded (36% in LD 14:10 and 25% in LD 24:0) as compared to controls (7%). The recorded signology related to diseased trout included darkening, lethargy and erratic swimming. Among the morphological changes, skin lesions and ulcerative-type necrosis could be observed. Blood tests, histopathology and isolation of pathogens identified as Flavobacterium psychrophilum, associated with Aeromonas, Pseudomonas and Saprolegnia sp., were performed. The application of artificial photoperiods suggests that fish may be more susceptible to opportunistic diseases; thus, it is advisable to emphasize preventive measures in fish subjected to this management.
authors.affiliation: Laboratory of Pisciculture and Aquatic Pathology, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile. avalenz@udec.cl.
authors.forename: Ariel
authors.initials: A
authors.lastname: Valenzuela
authors.affiliation: Laboratory of Microbiology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile.
authors.forename: Victor
authors.initials: V
authors.lastname: Campos
authors.affiliation: Laboratory of Pisciculture and Aquatic Pathology, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile.
authors.forename: Francisco
authors.initials: F
authors.lastname: Yañez
authors.affiliation: Laboratory of Pisciculture and Aquatic Pathology, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile.
authors.forename: Katherine
authors.initials: K
authors.lastname: Alveal
authors.affiliation: Laboratory of Pisciculture and Aquatic Pathology, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile.
authors.forename: Pamela
authors.initials: P
authors.lastname: Gutiérrez
authors.affiliation: Laboratory of Pisciculture and Aquatic Pathology, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile.|Master's Program in Zoology, Graduate School, University of Concepción, Concepción, Chile.
authors.forename: Meyling
authors.initials: M
authors.lastname: Rivas
authors.affiliation: Laboratory of Pisciculture and Aquatic Pathology, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile.
authors.forename: Nancy
authors.initials: N
authors.lastname: Contreras
authors.affiliation: Laboratory of Pisciculture and Aquatic Pathology, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Klempau
authors.affiliation: Laboratory of Microbiology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile.
authors.forename: Italo
authors.initials: I
authors.lastname: Fernandez
authors.affiliation: Laboratory of Biology in Fisheries Resources, Oceanography Department, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, Chile.
authors.forename: Ciro
authors.initials: C
authors.lastname: Oyarzun
mesh_terms: D000333:Aeromonas; D000818:Animals; D017756:Aquaculture; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology / Q000401:mortality; D005417:Flavobacterium; D016905:Gram-Negative Bacterial Infections / Q000276:immunology* / Q000401:mortality; D017686:Oncorhynchus mykiss / Q000276:immunology*; D017440:Photoperiod; D011549:Pseudomonas