A comparison between the physiological effects in fish exposed to lethal and sublethal concentrations of a dispersant and dispersed oil

The acute and sublethal effects of a dispersant and crude oil on anisosmotic and isosmotic regulation in flounder have been tested. Flounder were exposed to different concentrations of Corexit 9527 and crude oil by use of a biotest system. Fourteen days' exposure to 20 ppm of Corexit 9527, alone or in a 1:1 mixture with crude oil, had no effect on the blood parameters. On the other hand, 96 hours' exposure to 80 ppm of the same compounds led to 50 % mortality and significant effects on the blood parameters in surviving fish. The comparability between effects obtained in fish exposed to lethal and sublethal concentrations of toxicants, respectively, is discussed.