Exploring bioenergetics of diadromous Galaxias maculatus in the southernmost extreme of its distribution: Summer is not always the better season

BOY, C.C.; PÉREZ, A.F.; TAGLIAFERRO, M.T.; LATTUCA, M.E.; GUTIÉRREZ, M.; VANELLA, F.A.

JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY

ELSEVIER SCIENCE BV

Lugar: Connecticut; Año: 2017 vol. 488 p. 102 - 110

0022-0981

G. maculatus is a fast-growing species, and the studiedpopulation at the southernmost extreme of the species? distribution (54ºS), hasthe shortest growing season of the South American populations, as well as thegreatest maximum size. Thus it offers an opportunity to study the effects ofstrong seasonal variation. We explored the seasonal variation of the energyallocation pattern on a diadromous population of G. maculatus and studied the influence of winter/summerexperimental conditions on the bioenergetics of the species using both physiologicaland biochemical indicators. Somatic growth, energy density, food consumption, oxidativemetabolism and oxygen consumption were measured.We found that summer and winter are the two more ?energydemanding? seasons in the wild population (given reproduction and growth atsummer and environmental conditions at winter), leading to the lowest energydensity of its individuals. But also this population showed same level of basalmetabolism, feeding level and activity during winter and summer experimentalconditions of temperature and day length. Then, during winter this populationwould afford highest energetic demands without diminishing its basal metabolismnor its activity, but with the consequent lowest gross conversion efficiency,the complete absence of growth in length, mass and muscle, and the deplete ofenergy reserves.Our results provide evidence of different energyallocation strategies for winter and summer. A higher proportion of energycould be directed to growth and reproduction in summer, and to maintenance, to feeding  and to maintain swimming activity in winter.