title: Stress response of Salmo salar (Linnaeus 1758) when heavily infested by Caligus rogercresseyi (Boxshall & Bravo 2000) copepodids.
abstract: The year-round presence of ovigerous females of the parasite Caligus rogercresseyi in the fish farms of southern Chile results in a continuous source of the copepodid (infestive) stage of this louse. The short generation time in spring-summer could lead to high abundances of this copepodid, potentially leading to high infestation levels for fish. Knowing how heavy lice infestations affect Salmo salar can help determine how to time antiparasitic treatments so as to both minimize the treatment impact and reduce lice infestation levels for fish. This study aimed to describe the effects of high infestations of the copepodid stage of C. rogercresseyi on the physiology of S. salar. Two groups of S. salar were used: an infested group (75 copepodids per fish) and a control group (not infested). Sixty-five days after the first infestation, the infested fish group was re-infested at an infestation pressure of 200 copepodids per fish. Sampling was done prior to and following the second infestation, at 56 and 67 days (the latter 2 days following the second infestation). Several physiological variables were measured: cortisol (primary stress response) and glucose, proteins, amino acids, triglycerides, lactate, osmolality levels, and number and diameter of skin mucous cells (secondary stress responses). The plasma cortisol, glucose, and triglyceride levels were altered in the heavily infested fish, as was the diameter of skin mucous cells. These results suggest that heavy infestations of C. rogercresseyi lead to an acute stress response, metabolic reorganization, and increased mucus production in S. salar under heavy infestation conditions.
authors.affiliation: Programa de Doctorado en Ciencias de la Acuicultura, Universidad Austral de Chile, Los Pinos s/n, Balneario Pelluco, Puerto Montt, Chile. margaritapgg@hotmail.com.|Instituto de Acuicultura, Universidad Austral de Chile, Los Pinos s/n, Balneario Pelluco, Puerto Montt, Chile. margaritapgg@hotmail.com.
authors.forename: Margarita P
authors.initials: MP
authors.lastname: González
authors.affiliation: Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Independencia 641, Valdivia, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Vargas-Chacoff
authors.affiliation: Instituto de Acuicultura, Universidad Austral de Chile, Los Pinos s/n, Balneario Pelluco, Puerto Montt, Chile.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Marín
mesh_terms: D000596:Amino Acids / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001798:Blood Proteins / Q000378:metabolism; D033342:Copepoda / Q000502:physiology*; D004478:Ectoparasitic Infestations / Q000097:blood* / Q000378:metabolism / Q000662:veterinary; D005260:Female; D005393:Fish Diseases / Q000097:blood* / Q000378:metabolism; D029941:Fish Proteins / Q000097:blood; D006854:Hydrocortisone / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D009093:Mucus / Q000378:metabolism; D020317:Salmo salar / Q000097:blood / Q000378:metabolism / Q000469:parasitology*; D012867:Skin / Q000378:metabolism; D013312:Stress, Physiological; D014280:Triglycerides / Q000097:blood
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D001798:Blood Proteins; D029941:Fish Proteins; D014280:Triglycerides; D019344:Lactic Acid; D006854:Hydrocortisone
keywords: Acute stress; Caligus rogercresseyi; Experimental infestation; Physiological variables; Salmo salar