title: Experimental exposure of rainbow trout Oncorhynchus mykiss (Walbaum) to the infective stages of the sea louse Lepeophtheirus salmonis (Krøyer) influences the physiological response to an acute stressor.
abstract: The influence of infection with the juvenile stages of the sea louse, Lepeophtheirus salmonis (Krøyer) on the response of rainbow trout Oncorhynchus mykiss (Walbaum) to a net confinement protocol was investigated. The experiment consisted of two groups of seawater-adapted rainbow trout, one which was exposed to a total of 4000 nauplii/copepodid stages of L. salmonis 30, 25 and 14 days prior to confinement. Confinement elicited a greater stress response in the lice-exposed fish, than in the controls, as seen by higher plasma cortisol and glucose levels. A reduced spleen somatic index in exposed fish following 6 h confinement coincided with increased erythrocyte and lymphocyte numbers in the blood. Circulating lymphocyte numbers were significantly reduced in both groups 24 h post-confinement, when a lower alternative complement activity was recorded in control fish. Prior to confinement, lice-exposed fish had an elevated serum lysozyme activity and reduced oxygen radical production by blood leukocytes. Following confinement, lysozyme activity was gradually reduced in lice-exposed trout. During confinement, oxygen radical production decreased in control fish and increased in infested fish. Overall, transient exposure to juvenile lice altered the response to a second stressor, which has implications for management procedures of L. salmonis exposed fish.
authors.affiliation: Department of Animal Physiology, University of Nijmegen, The Netherlands. Neil.Ruane@alg.venv.wau.nl
authors.forename: N M
authors.initials: NM
authors.lastname: Ruane
authors.forename: D T
authors.initials: DT
authors.lastname: Nolan
authors.forename: J
authors.initials: J
authors.lastname: Rotllant
authors.forename: J
authors.initials: J
authors.lastname: Costelloe
authors.forename: S E
authors.initials: SE
authors.lastname: Wendelaar Bonga
mesh_terms: D000818:Animals; D003445:Crustacea; D004478:Ectoparasitic Infestations / Q000150:complications / Q000276:immunology / Q000662:veterinary*; D005260:Female; D005393:Fish Diseases / Q000276:immunology / Q000469:parasitology*; D006400:Hematocrit; D007962:Leukocytes / Q000276:immunology / Q000378:metabolism; D008297:Male; D009113:Muramidase / Q000378:metabolism; D017686:Oncorhynchus mykiss; D013154:Spleen / Q000276:immunology; D013312:Stress, Physiological / Q000150:complications / Q000276:immunology / Q000662:veterinary*
chemical_list: D009113:Muramidase