EROD activity measured in flatfish from the area of the Sea Empress oil spill

Dab (Limanda limanda) and plaice (Pleuronectes platessa) were collected at five stations near to the site of the Sea Empress oil spill within two week s of the incident and a further fourteen stations three months after the sp illage. Ethoxyresorufin-O-deethylase (EROD) activity was determined in the livers of the specimens to determine whether induction could be detected. S tatistically significant inter-site differences in EROD levels in both spec ies were demonstrated. Elevated levels of EROD activity in dab were found a t the two stations nearest to the incident up to three months after the spi ll but no clear relationship to putative contaminant levels was determined. EROD levels in plaice showed a generally similar pattern of induction as i n dab. Correlation of EROD levels with other variables showed that sexual m aturity had the greatest influence on dab during the study period. The plai ce specimens were sexually immature and, therefore, did not demonstrate a c orresponding relationship. It was concluded that, for EROD monitoring purpo ses, fish should be sampled during their sexually inactive phase and that c lose attention needs to be paid to other variables (depth, temperature, GSI , length, influential contaminants etc.) when interpreting the results. Cro wn copyright (C) 1999 Published by Elsevier Science Ltd. Ail rights reserve d.