Abstract: An account is given of the human impact and eutrophic elements on biotic community in the salinity gradient drainage networks and marine littorals, in the vicinity of the Tarut Bay, on the Arabian Gulf. Marked differences occurred in the algal vegetatidn between the origin of a spring (S = 0.3%) and the final discharge in the marine littorals (S = 23%). Influx of eutorphic elements and demolished building materials, which were dumped in the Tarut Bay, are causing perturbation to the tidal forests and marine littorals. Subsequently, a few mangroves inhabiting biotopes not described earlier were colonizing. A discussion is included to emphasis conservation and suggestions were made to monitor sites under threat of perturbation. in spite of the partial destruction of mangrove areas for the construction of corniche and urbanization, Anak and Al Awamiyah are still characterized by the best strands of mangrove swamps.