POLLUTION IMPACT STUDY IN GABES GULF (TUNISIA) USING REMOTE-SENSING DATA

A multidisciplinary project was conducted to study the impact of an im portant phosphogypsum discharge (50 million tons discharged near Gabes city over twenty years). Analysis of remote sensing data (Landsat MSS , SPOT XS and P, NOAA AVHRR) combined with field measurements were use d to describe actual and historical states and begin understanding alt eration mechanisms. The satellite information concerns bottom changes, sea color, sea surface temperature, and swell. Drastic changes have o ccurred in the Gabes Gulf to the west of the Gneiss-Djerba sill. The s eagrass beds and Caulerpa fields that covered most part of the Gulf ar e now restricted to some areas upwards of 10m depth. Under hydrodynami c processes, bare sediments can be re-suspended more easily. Light rea ching the bottom is reduced, inducing a shift from bottom primary prod uction to a planktonic one. Other contributory factors are discussed.