[Ecological data on the interstitial meiofauna of the lower part of the beaches of the gulf of Tunis].

The density of the meiofauna in the mediolittoral zone can exceed 4.10(6) ind./m2; the Nematoda are the most important group but their percentage is lower as in constantly immersed biotops; the population has a great vertical extension. Near the mouth of Medjerda river, the low salinity brings about a strong impoverishment.