Ecological models in estuarine management

Abstract

Abstract Current practice in the use of ecological models in water quality management of estuaries is almost exclusively restricted to very simple models of dissolved oxygen and biochemical oxygen demand; these models ignore almost the entire range of ecological interactions which actually occur in large estuaries and which transform organic matter and modify oxygen levels, yet nevertheless they are capable of realistic simulation and prediction. It is suggested that this is often because the modelled ecosystems are simplified due to pollution and/or very short water residence-time in the estuaries being modelled. More comprehensive ecological simulation models of estuaries are now being tested, and the nature of their output, and their application to practical estuarine water quality management are reviewed. It is suggested that the most comprehensive models have as their main role the understanding of the nature of simulations performed by simple models, and most importantly, in the prediction of the effects of major climatic or technological changes to estuaries. For instance, the effects of tidal power generation schemes, as proposed for Severn and Fundy, can only be predicted by large comprehensive models such as the NERC GEMBASE. Without the use of such models, prediction must be non-quantitative even if it is objective.