ABSTRACT
This study uses ecological indicators for the assessment of coastal water quality. Four stations having different geographical and ecological conditions were chosen along the coastal area of south Lebanon. Water samples were collected monthly from September 2000 to December 2001. Hydrological, hydrobiological and biological parameters were measured. Results showed that temperatures varied between 16.2 and 30 [degree]C, salinity between 38.87 and 39.57, orthophosphates between 0,01 and 0,68 micromol/L, nitrite and nitrates between 0,01 and 0,47 micromol/L et 0,02 and 11,64 micromol/L successively. The ratio N/P is far from the normal value, in the 4 stations. This is due to the fact the stations are coastal and subject to continental influence. Hence they could not be considered as the only indicator for a well-equilibrated marine ecosystem. Specific diversity [Shannon index] varied between 0.8 and 4.6. Stations with a low pollution have a high diversity while highly polluted stations have a lower diversity. The diversity index, within certain conditions can be considered as one criteria to estimate the equilibrium in the environment. Qualitative and quantitative study of phytoplankton are still an important factor in estimating the level of eutrophication in the littoral environment