Grottum, J.A., M. Staurnes, T. Sigholt-1997
Aquaculture Research, 28:159-164
Abstract:
The survival of turbot, Scophthalmus maximus (L.), kept at high densities (0.5 kg/l water) was studied when O2 was added by oxygenation, aeration, a combination of oxygenation and aeration, or by aeration with control of water pH by the addition of acid. Oxygen instead of air increased the LT50 (lethal time for 50% of the population) from 40 h to 130 h. Aeration in combination with acid addition further increased LT50 to 220 h. The results show that the transport time of live fish can be increased by reducing pH, either by raising carbon dioxide levels or by adding acid, probably because of reduced toxicity of total ammonia (NH3 and NH4+ ). In all groups, mortality was recorded at NH3 concentrations above 0.4 mg/l NH3-N.
(SINTEF Applied Chemistry, Center of Aquaculture, N-7034 Trondheim, Norway)
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