Annually significant amounts of petroleum and petroleum products are disposed to marine environment. Bioremediation technique tends to be one of the most effective methods to purify the marine environment from petroleum in the future. The efficiency of the bioremediation is highly depended on the environment. Within this study the effects of salinity and temperature over the biodegradation of diesel oil is investigated. As a pilot project area Istinye Bay, located at Bosporus, is chosen. The Bay has been used as a shipyard until recently. It's now used as a yacht harbor. The natural conditions of Istinye Bay are simulated under laboratory conditions.