15 SCUBA and 3 skin dives were performed at Fethiye Port (Southwestern Turkey) in order to determine the marine biodiversity and facieses distribution in the region and to assess the effects of marina construction activities on biota. The study area faced a variety of problems besides marina activities. The freshwater inflow caused a persistent, thin, less saline layer characterized with high nutrient concentrations and fecal contamination. A couple of meters high highly turbid water body at the bottom is due to sediment transport through the canal and weak circulation at the region as derived from ADCP measurements.

118 species were observed at the region heavily disturbed by anthropogenic facilities. Species adapted to organic matter rich environments were dominant in the area. Filter feeders such as tunicates, barnacles and bivalves constituted the major fraction of biomass. Flora was dominated by Enteromorpha spp. that was highly tolerant to organic pollution. Our studies clearly showed that the ecosystem was significantly altered as a result of anthropogenic activities. Although the recovery of the ecosystem is very difficult, it is evident that some improvements may be possible if the rate of sediment transport and terrestrial influxes to the bay is decreased.