[Effects of water temperature and feeding on respiratory metabolism of juvenile Salvelinus fontinalus].

ABSTRACT

The oxygen consumption and ammonia excretion rates of juvenile brook trout (Salvelinus fontinalus) under satiation and starvation were measured at different levels of water temperature [(5.5 +/- 0.5), (8.5 +/- 0.5), (11.5 +/- 0.5), (14.5 +/- 0.5), (17.5 +/- 0.5) degrees C], aimed to study the effects of water temperature and feeding on the respiratory metabolism of the fish. Under satiation, the oxygen consumption and ammonia excretion rates of juvenile S. fontinalus at the five temperature levels increased rapidly to the maximum, and then decreased gradually to the initial state. The regression equations of oxygen consumption rate (OR) and ammonia excretion rate (NR) to water temperature (t) were OR = -0.0601 t4 + 2.5542 t3 - 39.256 t2 + 276.26 t - 598.75 (R2 = 1, 4.5 degrees C < t < 17.5 degrees C) and NR = - 0.0020 t4 + 0.0826 t3 - 1.2318 t2 + 8.6186 t - 18.838 (R2 = 1, 4.5 degrees C < t < 17.5 degrees C), respectively. Under starvation, the regression equations were OR = 13.723 t(0.9738) (R2 = 0.9974, 4.5 degrees C < t < 17.5 degrees C) and NR = 0.1687 t(1.0896) (R2 = 0.9977, 4.5 degrees C < t < 17.5 degrees C), respectively. The optimal temperature range was 11.5 degrees C-14.5 degrees C. The juvenile S. fontinalus in starvation was heavily depended on fat and carbohydrates.