THE USE OF INVERTEBRATES IN-GROUND WATER MONITORING - A RISING RESEARCH FIELD

The use of invertebrates as biomonitors of ground water quality is a r elatively new approach that has come of age with the development of gr ound water ecology. The benefits of such an approach are illustrated b y four examples of field biomonitoring from several sites in various h ydrogeological settings. Contamination of the interstitial zone by hea vy metals in some sectors of the Rhone River (France) was shown by the scarcity of insect species; sewage pollution in the saturated zone of a karstic aquifer was indicated by the low relative abundances of sty gobites as compared with those of stygophiles and stygoxenes; and enri chment with organic matter of an underflow was dearly demonstrated by the extremely high density of ground water invertebrates such as oligo chaetes, ostracods, and isopods. Examination of the spatial changes in the composition and abundance of invertebrate assemblages was also us eful in determining the direction and intensity of water fluxes betwee n a river and its underflow, as well as in delineating the reduced or oxidized zones in a manganese-polluted aquifer. Finally, the selected case studies emphasized the variety of methodological approaches that could be developed in ground water contamination biomonitoring, as wel l as the complementary and sometimes new information provided by this innovative method in comparison with that obtained by conventional pol lution monitoring techniques.