[Oxygen consumption and ammonia-N excretion rates of Coelomactra antiquata]

With laboratory experiments, this paper studied the oxygen consumption rate (OCR) and ammonia-N excretion rate (NR) of Coelomactra antiquata at different levels of dissolved oxygen (DO) and water temperature. The results indicated that at 25 degrees C and 3.11 +/- 0.15 mg DO x L(-1), C. antiquate had a comparatively stable OCR and NR, which maintained at 0.74 +/- 0.05 mg x g(-1) x h(-1) and 2.56 +/- 0.05 micromol x g(-1) x h(-1), respectively. When DO was lower than 3.11 +/- 0.15 mg x L(-1), the metabolism of C. antiquate became abnormal, and its OCR was decreased with decreasing DO until suffocate, with a suffocate point 1.22 +/- 0.06 mg L(-1) at 25 degrees C. The NR also declined with decreasing DO, which ceased later than oxygen consumption. There was a quadratic linear relationship between OCR and water temperature (OCR = -0.0027T(2) + 0.1367T - 0.9557, R2 = 0.9724). When water temperature was 25.3 degrees C, the OCR arrived to its maximum value 0.77 mg x g(-1) x h(-1). The O/N ratio at optimal temperature (15-20 degrees C) was higher than that at low (10 degrees C) and high temperature (25 degrees C and 30 degrees C). To maintain its standard metabolism, C. antiquata consumed more fat under fit condition, while more protein under stress.