Temperature effects on growing, feeding, and swimming energetics in the Patagonian blennie Eleginops maclovinus (Pisces: Perciformes)

Abstract

The Patagonian blennie Eleginops maclovinus is a coastal and estuarine species, important in recreational and commercial fisheries, and with aquaculture potential. This study assessed the effect of temperature on feeding and the allocation of energy in growth and swimming in a sub-Antarctic population. For growth experiments, two groups of 8 juveniles were reared at 4 and 10 °C (corresponding to winter and summer habitat temperatures, respectively) for 3 months. Swimming experiments were conducted at 5 and 10 °C, measuring the oxygen consumption before and after forced swimming for 1 min at a speed of 10 total lengths (TL)/s. Temperature affects growth. TL increased 0. 09 cm at 4 °C versus 0. 30 cm at 10 °C. Body mass grew 0. 49 g at 4 °C versus 1. 65 g at 10 °C, whereas the Fulton's condition factor increased 0. 021 at 4 °C versus 0. 080 at 10 °C. The ingested food was more than twofold higher at 10 than at 4 °C, while the feces produced at 4 °C was about twofold higher. The scope between baseline and peak oxygen consumption after forced swimming was affected by temperature, being 4. 51 at 5 °C and 3. 03 at 10 °C. The percentage energy expenditure until the return of baseline oxygen consumption values showed a marked temperature effect, being higher at 5 °C. We propose the existence of a trade-off in the allocation of energy between swimming activity and growth, with proportionally more energy being consumed at low temperatures for swimming than for other physiological functions like growth.