Sub-Lethal Effects of Exposure of Juvenile Turbot to Oil Produced Water

Exposure of 50-day-old turbot (Scophthalmus maximus) to 0.001–1% produced water (PW) from a North Sea oil platform for up to six weeks did not affect their survival. Overall, the results indicate that impacts of this PW on young turbot are likely to be limited to an area close to its discharge to surface waters. Sub-lethal physiological stress was evident (elevated whole body cortisol) only after six weeks in 0.1% or 1% PW. In these fish and those exposed to 1% PW for three weeks 50% gill lamellae were fused at their tips and as a result respiratory and/or ionoregulatory processes were likely to be impaired. Decreased oxygen uptake or the narcotic effects of aromatic hydrocarbons may account for the reduced swimming activity of 1% PW-exposed fish. However, in 0.001% PW, fish increased swimming activity which may partially account for their depressed growth. Whole body ethoxyresorufin O-deethylase (EROD) activity was elevated only after one or six week’s exposure to 1% PW, not in all groups with hydrocarbon accumulation.