title: Effects on the metabolism, growth, digestive capacity and osmoregulation of juvenile of Sub-Antarctic Notothenioid fish Eleginops maclovinus acclimated at different salinities.
abstract: In this study we assessed the influence of three different environmental salinities (5, 15 and 31 psu during 90 days) on growth, osmoregulation, energy metabolism and digestive capacity in juveniles of the Notothenioid fish Eleginops maclovinus. At the end of experimental time samples of plasma, liver, gill, intestine, kidney, skeletal muscle, stomach and pyloric caeca were obtained. Growth, weight gain, hepatosomatic index and specific growth rate increased at 15 and 31 psu and were lower at 5 psu salinity. Gill Na(+), K(+)-ATPase (NKA) activity presented a "U-shaped" relationship respect to salinity, with its minimum rates at 15 psu, while this activity correlated negatively with salinity at both anterior and posterior intestinal portions. No significant changes in NKA activity were observed in kidney or mid intestine. Large changes in plasma, metabolite levels and enzymatic activities related to energy metabolism in liver, gill, intestine, kidney and muscle were generally found in the groups exposed to 5 and 31 psu compared to the 15 psu group. Only the pepsin activity (digestive enzymes) assessed enhanced with environmental salinity, while pyloric caeca trypsin/chymotrypsin ratio decreased. This study suggests that juvenile of E. maclovinus presents greater growth near its iso-osmotic point (15 psu) and hyperosmotic environment (31 psu). Acclimation to low salinity increased the osmoregulatory expenditure as seen by the gill and anterior intestine results, while at high salinity, branchial osmoregulatory activity was also enhanced. This requires the mobilization of lipid stores and amino acids, thereby holding the growth of fish back. The subsequent reallocation of energy sources was not sufficient to maintain the growth rate of fish exposed to 5 psu. Thus, E. maclovinus juveniles present better growth efficiencies in salinities above the iso-osmotic point and hyperosmotic environment of this species, showing their best performance at 15 psu as seen by the main osmoregulatory and energy metabolism enzymatic activities.
authors.affiliation: Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile. luis.vargas@uach.cl.
authors.forename: L
authors.initials: L
authors.lastname: Vargas-Chacoff
authors.affiliation: Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: E
authors.initials: E
authors.lastname: Saavedra
authors.affiliation: Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: R
authors.initials: R
authors.lastname: Oyarzún
authors.affiliation: Centro de Investigación y Desarrollo (CIEN Austral) CONICYT Regional R10C1002, Universidad Austral de Chile, Av. Los Pinos s/n, Balneario Pelluco, Puerto Montt, Chile.|Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, PO Box 610, 82000, Mazatlán, Sinaloa, Mexico.
authors.forename: E
authors.initials: E
authors.lastname: Martínez-Montaño
authors.affiliation: Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile.|Instituto de Bioquímica y Microbiología, Interdisciplinary Center for Aquaculture Research (FONDAP-INCAR), Universidad Austral de Chile, Valdivia, Chile.
authors.forename: J P
authors.initials: JP
authors.lastname: Pontigo
authors.affiliation: Instituto de Bioquímica y Microbiología, Interdisciplinary Center for Aquaculture Research (FONDAP-INCAR), Universidad Austral de Chile, Valdivia, Chile.
authors.forename: A
authors.initials: A
authors.lastname: Yáñez
authors.affiliation: Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI-MAR), Universidad de Cádiz, Cádiz, Spain.|Centre of Marine Sciences (CCMar), CIMAR-Laboratório Associado, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.
authors.forename: I
authors.initials: I
authors.lastname: Ruiz-Jarabo
authors.affiliation: Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI-MAR), Universidad de Cádiz, Cádiz, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Mancera
authors.affiliation: Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: E
authors.initials: E
authors.lastname: Ortiz
authors.affiliation: Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Bertrán
mesh_terms: D000064:Acclimatization / Q000502:physiology; D000818:Animals; D004063:Digestion / Q000502:physiology*; D004734:Energy Metabolism; D005880:Gills / Q000201:enzymology / Q000502:physiology; D007422:Intestines / Q000201:enzymology / Q000502:physiology; D007668:Kidney / Q000201:enzymology / Q000502:physiology; D064587:Osmoregulation; D010434:Pepsin A / Q000378:metabolism; D010473:Perciformes / Q000254:growth & development / Q000502:physiology*; D054712:Salinity; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D010434:Pepsin A; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Eleginops maclovinus; Euryhaline fish; Growth; Metabolism; Osmoregulation