ESTIMATING THE PARAMETERS OF DISSOLVED-OXYGEN DYNAMICS IN SHALLOW PONDS

A modelling of the circadian evolution of dissolved oxygen dynamics in shallow homogeneous ponds, using a very simple and short-term mechani stic model and continuous measurements of dissolved oxygen, water temp erature and light intensity, is presented. Two levels of results are o btained. First, a qualitative level providing information on the gener al behaviour of the model and its ability to fit the data. The point i s to appreciate the suitability and the range of validity of the model , when a great number of data sets is available in various situations. Secondly, a quantitative level providing in situ daily values for pon d respiration, oxygen transfer coefficient, initial slope and maximum of the photosynthesis versus light relationship. Such simple models, r unning on short periods and fitted on continuous measurements, should be considered as complementary tools for in situ investigations of aqu atic ecosystems and for ecological model building.