Biological-physical interactions in estuaries

Abstract

Estuaries are an excellent example of the complex interactions that normally occur in coastal environments. A large number of factors (Perillo, 1995) interact simultaneously in a non-linear fashion, making rather difficult the exact prediction of even the simplest processes. The difference with other types of coastal settings is that this interaction occurs within the restricted space provided by the estuarine valley. Therefore, the local geomorphology becomes a dominant player. Tidal propagation, for instance, is affected by the geomorphology and wind action resulting in modifications of the symmetry of the tidal curve, duration and direction of the tidal currents and mixing of the waters. As these occur, sediment, nutrient and pollutant distribution are continuously changing, developing concentration zones (e.g., turbidity maxima) or modifying the residence time of the substances.