J.-P. Descy - Böcker

The ecology of potamoplankton has received less attention than lake plankton. These proceedings produce a synthesis of the composition, community structure and dynamics of lotic phytoplankton, which are intuitively submitted to a strong physical control in the flowing environment, perceived as much more "disturbed" than a lake, even than a well-mixed shallow one. It turns out that the boundary between the phytoplankton of rivers and lakes is not as clear-cut as was thought. In particular, most contributions provide arguments emphasizing the prominent role of physical control in both aquatic systems, especially due to the steep light gradient resulting from turbulent mixing in a turbid water column. Similarities and differences between potamoplankton and limnoplankton, largely based on the information gathered by the contributors are discussed in the introductory paper by Reynolds et al.

The book presents approaches and methodologies for predicting the structure and diversity of key aquatic communities (namely diatoms, benthic macroinvertebrates and fish), under natural conditions and under man-made disturbance. Such an approach will make it possible to: 1) set up procedures for robust and sensitive ecosystem evaluation, based on the prediction of the expected community structure; 2) model community structure in disturbed ecosystems, taking into account all the relevant ecological variables; 3) test ecosystem sensitivity to natural and anthropic disturbance; and 4) explore specific actions to be taken for the restoration of ecosystem integrity.

The landmass on which we live is an integral part of our water catchment. Any human - tivity will inevitably have some consequences on the availability and composition of fresh waters. These consequences are becoming increasingly important and detectable as the - man population grows. The problem is to be addressed at the global scale, as frequently, decisions made have inter-regional and international impacts, and must therefore be coor- nated. In a number of European Member States, for example, the availability of water - sources depends on the activities of other upstream countries. The demand for fresh water in Europe, as well as in the world, is increasing. There is an upward pressure on European water demand for public supplies (drinking water, recreation, etc. ), for industry, and for - rigated agriculture. The ecological impacts of different uses are complex, and currently not always predictable. This book should help planners in their decisions on different water management options for human use. Water, of course, is not only relevant as a resource, exploited for human activities, but it is also relevant to aquatic ecosystems and to their quality. Preservation and restoration of the ecological quality of these ecosystems have a major social impact, as it has been stressed in several European Community actions.