PAHs are often produced by incomplete fossil fuel burning and accidental discharges of petroleum products from factories,

vehicles, and ships (Fang et al., 2003, Doong and Lin, 2004, Ko and Baker, 2004 and Froehner et al., 2010). They have been declared as primary pollutants by the Environmental Protection Agency, United States, due to their carcinogenicity, toxicity, and mutagenicity. Recent research has shown that PAHs can be transported from terrestrial sources to estuaries and nearby coastal areas Cyclopamine research buy via discharges and land runoff (Gogou et al., 1996, Bouloubassi et al., 2001, Li et al., 2006, Hung et al., 2010, Hung et al., 2011, Cheng et al., 2010 and Ko et al., 2014a). After PAHs have been transported to estuarine and coastal environments through various physical processes, they will be incorporated with phytoplankton or detritus. Subsequently,

they may enter marine food chains to be highly accumulated in marine organisms of higher trophic RO4929097 molecular weight levels (e.g., zooplankton, fish larvae, fishes, or mammals) via absorption and/or bioaccumulation (Landrum et al., 1992, Burkhard, 1998, Cailleaud et al., 2007, Vigano et al., 2007, Froehner et al., 2010, Hung et al., 2011 and Ko et al., 2014b). Therefore, an understanding of how PAHs are distributed and accumulated in zooplankton contributes to a better understanding of PAHs pollution in marine ecosystems. The East China Sea (ECS) is a large marginal sea of the Pacific Ocean and is characterized by high values of primary production, particulate organic carbon flux,

carbohydrate Adenosine yield, and carbon sequestration rate (Gong et al., 2003, Gong et al., 2006, Gong et al., 2011, Hung et al., 2009a, Hung et al., 2010, Hung et al., 2013, Chen et al., 2013a, Chou et al., 2009, Chou et al., 2011 and Chou et al., 2013). The ECS also supports many key fisheries stocks, e.g., croakers, mackerels, hairtails, and pomfrets (Chen et al., 1997; Hung and Gong, 2011). According to previous studies, distinct salinity fronts have been frequently found in the ECS and may be important for small fish and plankton (Belkin et al., 2009 and Chen, 2009). Besides numerous nutrient input to the ECS, previous research has reported that the Changjiang River (Yangtze River) transports thousands of tons of pollutants, such as heavy metals and persistent organic pollutants, including hydrocarbons (Lü and Zhai, 2005), pesticides, and PAHs (Guo et al., 2006, Feng et al., 2007, Müller et al., 2008 and Deng et al., 2013) to the ECS per year. These PAHs discharged to the ECS may be easily accumulated in marine animals inhabiting the ECS through feeding links.