Abstract
The review paper by Karr & Rossano (2001) and the opinion paper by Shimatani (2001) were edited for the mini-features entitled "What is river health?" in this volume. The concept of river health will be of use for making a common understanding on the ideal river image particularly in Japan where the most rivers have been altered artificially through the land use history. The method of multimetric index on the biological integrity applied to Japanese rivers seems to be effective for evaluating present river conditions under a wide range of human impacts. Research perspectives required in the next step may be development of methods for finding out causal relations in substance, which is necessary for conducting adaptive management in river ecosystems.
