Major Biological Processes in European Tidal Estuaries

This work presents results of the project Major Biological Processes in European Tidal Estuaries , funded by the Commission of the European Communities under its Marine Science and Technology Programme. This was one of the first projects in which a large number of European macrotidal estuaries, from the Elbe to the Tagus, were studied simultaneously and compared in a coherent way by application of a standardized methodology. It revealed that these estuaries have many species in common and that their ecology can be understood on the basis of a common concept. A major result of the comparison is that, while salinity gradients explain species succession very well within each estuary, similar succession series are found at different salinity levels in different estuaries. Organic loading and the availability of food may explain these differences. Overall, organic loading appears more important in explaining the functioning of tidal estuarine systems than nutrient loading.