The paper proposes a new biological method for assessing the quality of lakes. It is based on the comparison of littoral and profundal macroinvertebrate communities sampled in soft sediments. Two depths were sampled: one at the littoral zone (Zl = 2m) to define a littoral index (Bl ) related to the biogenic potential of the lake (quantitative data), the other at the deep zone (Zf = 0.66 Zmax) to define a taxonomic deficit index (Df ) connected with the quality of the water-sediment interface in deep zone (qualitative data). These two indexes were combined in a Lake Biotic Index (LBI), with a range from 0 to 20, which gives an evaluation of the biogenic capacity of a lake to the development of macroconsumer communities. Using the Bl and Df values any lake can be plotted on a typological graph which is helpfull to characterize lakes both quantitatively (oligo-to polybiotic) and qualitatively (eu-to dysbiotic). Lake Châlain (French Jura) is presented as an example of the method application with its macrofauna and the index calculation. Then, this lake was included in the typological graph with nine other French lakes studied using the same method. Each lake, characterized by its Bl, Df and LBI values, can be compared to the others in a typological scheme. The proposed indexes are discussed and bases for interpretation of the results are presented. The proposed classification of lakes gives an evaluation of their biogenic capacity concerning macroconsumers and can be usefully compared with other classifications, especially with trophic and sediment types, in functional studies as well as in lake diagnosis, in the context of the Water Framework Directive (Directive 2000/60/CE).

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To evaluate the landfill leachate impact on the stream water quality, we assessed the spatial evolution of several abiotic and biotic parameters in Etueffont domestic landfill (Belfort, France). The samples were taken in 13 June 1999 with a Van-Dorn bottle from upstream to downstream. The study showed that leachate rejection resulted in an increase of the pH, NO 3 -, Cl -and COD concentrations in the first meters after rejection. In downstream, however the reverse was quoted. Bacterial abundance increased from upstream to downstream with no relationship between this biological compartment and leachate rejection. Finally, it seems likely that the abilities of self regulation of brook were higher to the leachate-induced pollution.