Abstract
Cod (Gadus morhua L.) eggs and larvae were continuously exposed to water extracts of North Sea crude oils in the concentration range from 50 to 280 ppb of the water soluble fraction (WSF). The oil exposure did not influence the oxygen uptake of cod eggs. Unfed cod larvae, however, suffered a 50 % reduction in the oxygen uptake rate. The effect was independent of the oil concentration in the tested range. Larvae exposed to 230 ppb WSF for only 24 hours demonstrated the same 50 % reduction in the oxygen uptake. The oxygen uptake of control larvae measured in total darkness was of the same magnitude as for the oil-exposed larvae. Oil-exposed larvae, measured in darkness, however, showed a further 5–10 % reduction in the oxygen uptake rate. After anaesthesia (MS-222, 1:20 000) the oxygen uptake of both control and oil-exposed larvae decreased with 60–65 % compared to control conditions at the time of final yolk absorption.
