Variation of antioxidant enzyme activities of sprat (Sprattus sprattus) larvae and organic contaminant levels in mixed zooplankton from the southern North Sea.

Sprat (Sprattus sprattus) larvae and mixed zooplankton were collected from sites in the southern North Sea across three transects running north, north-west and west from the Elbe and Weser estuaries (Germany). Sprat larval sub-cellular fractions (13,500 g supernatants) were assayed for the antixoxidant enzymes catalase (EC 1.11.1.6) and superoxide dismutase (SOD; EC 1.15.1.1), and levels of polychlorobiphenyls (PCBs), p,p'-DDE and polycyclic aromatic hydrocarbons (PAHs) were determined in the mixed zooplankton (fish larval diet). Higher levels (p < 0.05) of SOD and catalase activities were observed at sites closest to estuaries corresponding to sites with the highest levels (p < 0.05) of total PCBs and p,p'-DDE. Antioxidant enzymes activities decreased in samples collected from sites further from the estuaries across a northern and north-western transect; however this was not observed across a western transect. Larval antioxidant enzyme activities are discussed in relation to potential processes affecting them including plankton contaminant level distributions.