Some problems and perspectives in applied limnology

This enlarged version of the lecture held at the 50th anniversary of our Society has been written with the idea to discuss some typical tasks in applied limnology from a conceptual point of view. There have been published many factual summaries and series of reports on almost every subject of applied nature in limnology on which to base a retrospective and critical evaluation of present-day thinking and practice in fields such as establishing water standards, water pollution control and river surveillance. Extended contacts with these problems and the sometimes confusing literature were incentives for an essay in which to confront the daily problems of practical limnologists in a broader ecological context.