Evolution of Potential Ecological Impacts of the Bottom Sediment from the Gulf of Gemlik; Marmara Sea, Turkey Selma U ¨ nlu ¨ Æ Bedri Alpar Received: 6 November 2008 / Accepted: 21 June 2009 Ó Springer Science+Business Media, LLC 2009 Abstract The eastern and southern coasts of the Gulf of Gemlik, a resort in the Sea of Marmara, Turkey, are under the influence of rapid ecotourism development, direct domestic and industrial discharges via rivers and outfalls, surface run- off, drainage from ports and shipping. According to sediment quality criteria in use around the world, sediment quality in the gulf shows a broad spectrum. It is more related by direct input, rather than by the type of sediment, and excluding inner port and southern coasts, it does not exert adverse biological effects yet. The total PAH concentrations range from 51 to 13,482 ng/ g dry weight with the mean value of 1,850 ng/g dry weight (n = 61). The elevated values of the total toxic Benzo[a]- pyrene equivalency (TEQ carc ), with a maximum of 1,838 ng/g dry weight, were found at the inner harbor of Gemlik, possibly posing hazard to benthic organisms. Among the different PAHs, the contribution to the total TEQ carc decreased as the following order: Benzo[a]pyrene (43.6%) [ Benzo[k]fluo- ranthene (36.0%) [ Indeno[1,2,3-cd]pyrene (35.1%) [ Benzo[b]fluoranthene (20.0%) [ Chrysene ? Triphenylene (18.9%) [ Benzo[a]anthracene (12.5%). Keywords Pollution  Contaminated sediment  Sediment toxicity  Sediment quality guidelines  TEQ carc  Gulf of Gemlik In recent years, there has been great concern about the marine environment, especially relating to the presence of anthropogenic contaminants and their possible biological effects. As essential components of aquatic and marine ecosystems, sediments provide habitat for a wide variety of benthic organisms as well as juvenile forms of pelagic organisms. Benthic organisms are in constant contact with contaminants adsorbed to the sediment particles. The potential impacts include acute/chronic toxicity, bioaccu- mulation of contaminates, and passing of contaminants to predators of benthic species (Adams et al. 1992). Monitoring of the contaminant concentrations is an important record to understand the natural biogeochemical processes of hydrocarbons in sediments. Such information is crucial to ecological risk assessment and management of marine areas with contaminant input. A similar study has been applied for the sediment of the Gulf of Gemlik (U ¨ nlu ¨ and Alpar 2006) which show the concentration and possi- ble sources of PAHs. Sediment quality guideline values ‘‘effects range-low’’ (ERLs) and ‘‘effects range-median’’ (ERMs), representing possible-effects ranges of organics in sediment, are scien- tific tools that synthesize information regarding the rela- tionships between the sediment concentrations of chemicals and any adverse biological effects resulting from exposure to these chemicals (Long et al. 1995). The objectives of this study were to assess the potential for sediment quality within the Gulf of Gemlik on the basis of internationally accepted values of National Oceanic and Atmospheric Administration (NOAA), and to identify those areas in which the potential for biological effects is greatest. Materials and Methods The methods used in this study have been described in detail (U ¨ nlu ¨ and Alpar 2006) and will only be summarized here. S. U ¨ nlu ¨(&)  B. Alpar Institute of Marine Sciences and Management, Istanbul University, 34116 Istanbul, Turkey e-mail: su@istanbul.edu.tr B. Alpar e-mail: alparb@istanbul.edu.tr 123 Bull Environ Contam Toxicol DOI 10.1007/s00128-009-9803-8