The ecophysiology and ecotoxicology of fishes as a tool for monitoring andmanagement strategy of high mountain lakes and rivers in acidified areas

A monitoring programme for lakes and running waters is discussed with refer ence to manuals from national and international monitoring programmes and t he EU research projects AL:PE, AL:PE 2 and MOLAR. For lakes, the monitoring programme must include standard test-fishing with multimesh sized gillnets , repeated at a frequency determined by the population status found in the individual lake. The sampling and analyses programme should include tissue samples for determination of levels of micro-pollutants such as heavy metal s and persistent organic pollutants (POPs). Nitrogen isotopes (N-14/N-15) s hould be included to determine the trophic level of the individual fish. As micropollutants are directly related to the socio-economic aspects and hum an consumption, it is of vital importance to follow standard procedures for sampling and analyses. The MOLAR manual is therefore recommended. In areas with a significant pollution load, stocking strategies, including choice o f fish species and strain, should minimize risk for human consumption. In r ivers and streams in acidified areas, a traditional water sample describes the "at present" water quality conditions only. In important periods of the year such as the smoltification period in Atlantic salmon rivers, a high f requency sampling programme should be used. However, by using in situ water chemistry analyses of aluminium for species fractionation and molecular si ze determination in combination with ecotoxicological and ecophysiological methods, a much better resolution of the past and present water quality can be found. This will include sampling of blood for analyses of chloremia an d other haematological parameters, and gill tissue for histological charact erisation and determination of Al concentration.