Effects of water temperature and post-feeding period on postprandial ammonia excretion and oxygen consumption by larval Pacific cod (Gadus macrocephalus) fed rotifers (Brachionus plicatilis)

Özet

Postprandial ammonia excretion and oxygen consumption of 15-d post-hatch larval Pacific cod (Gadus macrocephalus), rotifer-fed (Brachionus plicatilis) since their first feeding, were studied in stationary cultures at 10$^0C$, 13$^0C$, and 16$^0C$ for 48 h. Postprandial ammonia excretion and oxygen consumption rates were determined after 2, 4, 6, 8, 10, 12, 18, 24, 36 and 48 hours. The 48-h post-feeding weight-specific ammonia excretion and oxygen consumption rates increased until 4 h postfeeding, decreased to 18 h post-feeding, and remained relatively stable until 48 h post-feeding. The highest weight-specific ammonia excretion and oxygen consumption rates were 215±19.8 &#956;g NH3-N $g^{-1}$ $h^{-1}$ and 1,778±55.6 &#956;g O2 g&#8211;1 $h^{-1}$ 2&#8211;4 h postfeeding at 13 $^0C$. The higher (P<0.05) resting ammonia and oxygen consumption at 16 $^0C$ 12-h post-feeding indicate that this temperature is not appropriate for inducing higher growth of rotifer-fed pacific cod larvae.