Revista Chilena de Historia Natural 78 (2): 303-311, 2005
RESEARCH ARTICLE
Temperature, energy acquisition and energy use in the Chilean silverside Basilichthys
australis Eigenmann (Atherinopsidae)
We evaluated the influence of water temperature (Tw) on the energy acquisition and use
in the Chilean silverside Basilichthys australis (Eigenmann 1927), an endemic species inhabiting freshwater ecosystems
in Chile. We tested the effect of Tw (11.5, 14.0, 18.0, 22.0 and 26.0 °C) on food intake, digestibility, food transit time and metabolic rate.
As expected, this study demonstrated that many physiological variables under study were significantly affected by Tw, as well as the
net energy balance of this species. Nevertheless, the net energy balance was not strictly related to the range of Tws evaluated. At Tws
lower than 14 °C the energy budget was depressed, because food intake was lower than at Tws between 14 and 26 °C, where food
intake was higher and independent of Tw. Consequently, at these temperatures the energy balance was positive and also independent
of Tw. Physiologically, B. australis appears to be a tolerant species with respect to the wide range of water temperature in
habitats at different depths. Thus, its distributions may extend through the entire profile of lakes and rivers, even in systems
characterised by spatial and temporal thermal variability.
Key words:
water temperature,
metabolic rate, food consumption, digestion, energy budget, Basilichthys australis
