Monitoring DNA damage in indigenous blue mussels (Mytilus edulis) sampled from coastal sites in Denmark

Damage to DNA detected by use of the single-cell gel electrophoresis (comet) assay was monitored in blue mussels, Mytilus edulis, sampled from coastal waters in Denmark. Mussels from five locations in Køge Bay, an area receiving wastewater from many industries and municipalities, were collected five times during 1999 and six times in 2001. In 1999, both gill cells and haemolymph cells were examined, and sediments were sampled on three dates from the same five locations. In the autumn of 1999, mussels were also collected at six reference sites without known pollution. Results showed a significantly higher level of DNA damage in gill cells compared with haemolymph cells. Because of this, only gill cells were sampled for the monitoring in 2001. Levels of DNA damage, expressed as tail moments, were significantly higher for the mussels in Køge Bay when compared with levels of DNA damage in mussels from the non-polluted coastal areas. No clear seasonal variation was demonstrated. Analysis of the correlation between chromium, nickel, cadmium and mercury in sediments and tail moments in haemolymph and gill cells from the five sites showed a statistically significant positive correlation between tail moments and chromium, nickel and cadmium (P < 0.01). The overall conclusion was that the comet assay on blue mussels could be useful for screening of genotoxic pollution in marine waters.