The editors of this book, Mr Derek Westlake, Dr Jan Květ, and Dr Andrzej Szczepański have made significant contributions to the results of the International Biological Programme (IBP), which ran from 1964 to 1974.

The programme was organised into seven main sections which were inevitably subdivided with a very large number of research projects. By no means all could be brought to conclusion at the end of the programme's decade, so the Cambridge University Press, which had been very helpful throughout, agreed to publish a series of volumes, which record many of the results.

This volume is published in addition to the original IBP Series, and follows on in subject matter from Volume 22: The Function of Freshwater Ecosystems, edited by E.D. le Cren and R.H. Lowe-McConnell. As Scientific Director of the IBP with its very wide view of environmental ecology, I have a special interest in its section on inland waters, having spent my early years of research on that subject. I am sure this volume will be welcomed as a valuable contribution.