A NEW METHOD FOR SAMPLING THE FAUNA OF DEEP KARSTIC AQUIFERS

Because of the inaccessibility of karstic groundwater ecosystems, faun al sampling has so far been carried out essentially at the natural acc ess of the aquifers : the caves and springs. In 1991-1993, faunal samp ling was carried out with an air-lift in 8 wells located in the Let Ba sin (Herault, France). The depth of the wells ranged from 46 to 90 m a nd the static water level from 2 to 40 mt This sampling method offers several key advantages : 1) it allows the study of karstic aquifers wi th no natural access (e.g. confined aquifer); 2) sampling may be carri ed out in the thinly fissured parts of the saturated zone; 3) very dif ferent spatial scales may be considered (e.g. the scale of a basin or an experimental site); 4) faunal sampling in monitoring wells may be u sed to assess the impact of a point source of pollution on the groundw ater quality.