Analogous PI3 kinase pathway uncoupling results between nitrate and Chl-a (or primary production) were also reported in the East China Sea ( Hung et al., 2013). Total concentrations of PAHs (as the sum of 50 compounds) in zooplankton ranged from 29 to 5384 ng g−1, showing a high spatial variation, with higher levels (>1000 ng g−1), when normalized to dry weight of zooplankton, found in coastal areas (Table 1 and Fig. 4). Surprisingly, the highest level of PAHs (5384 ng g−1, dry weight) was found in the the outer shelf region (i.e. station 15). We suggest that this could have been caused by low zooplankton weight (Table 1) as compared to other stations.

The detailed data of PAHs at different stations are shown in Table 2 and the main compounds of PAHs in the zooplankton were phenanthrene (Phe), 2-methylanthracene, 4,6-dimethyldibenzothiophene, fluoranthene (Flu), pyrene (Pyr), Anthracene (An), Benzo (a)pyrene (BaP), Benzo(ghi)perylene (BghiP), and chrysene + triphenylene which are similar to previous investigations ( Hung et al., 2011 and Deng et al., 2013). These compounds have been reported in tributaries or the main stream

of the Changjiang River and the estuary and/or coastal area of the ECS, indicating that pollution conditions of PAHs have existed in the ECS ( Feng et al., 2007 and Liu et al., 2008). This is probably due to the relatively large learn more and rapid energy consumption in China, including 48% of coal, 11% of oil and 3.5% of natural gas of global energy consumption (BP, 2011). Undoubtedly, the eastern coastal provinces of China produced enormous PAHs in the world and these PAHs are easily be transported to the ECS. The distribution of PAHs check in zooplankton may be related to other hydrographic parameters such as nutrient and Chl-a concentration. However, we did not find a pronounced correlation between PAHs and nutrient (and Chl-a) concentrations, indicating that nutrient and phytoplankton distributions could not help in the interpretion of the variations of PAHs concentrations in zooplankton in this study. Besides the effect of water masses, the high variation of PAHs in zooplankton

was likely affected by different zooplankton species, growth stage (Lotufo, 1998) or lipid contents (Bruner et al., 1994). However, when compared to literature data on total PAHs concentrations in marine organisms (such as copepods and amphipod), the observed PAHs data in zooplankton in this study are in agreement with those documented elsewhere (Harris et al., 1977, Ko and Baker, 1995, Lotufo, 1998 and Vigano et al., 2007). Due to patchiness in zooplankton abundance in surface waters (Table 1), we prefer to report abundance in ng m−3 (calculated as the product of PAH concentration in ng g−1 and abundance in g m−3), when discussing the distributions of total PAHs concentrations in the frontal zones of the ECS. Total concentrations of zooplankton PAHs in the CDW ranged from 2 to 3500 ng m−3 (e.g.