Diurnal changes of dissolved oxygen in fouling land-based tanks for rearing of sea bass

Concentration of dissolved oxygen (DO) was measured in non-fouling tanks wi th sea bass and in fouling tanks without fish. The rate of oxygen productio n and respiration of fouling organisms and the rate of oxygen consumption b y sea bass were calculated from the changes of DO. It was possible to appro ximate diurnal changes of these rates as periodical functions of time. A ma thematical model was used to study the effects of fouling, density of fish and water flow on DO during the day (0-24 h). During the sunlight the fouli ng increases DO in the tank, while during the night it does not affect DO s ignificantly. Water detention time significantly affects the minimum values of DO, and relatively little the maximum ones during the day. (C) 1999 Els evier Science B.V. All rights reserved.