Potential relation between mercury concentrations and necropsy findings incetaceans from German waters of the North and Baltic Seas

Concentrations of total mercury and methylmercury were analysed in muscle, kidney and Liver samples from 57 harbour porpoises and three white-beaked d olphins, stranded or by-caught from the German waters of the North and Balt ic Seas. Levels of total mercury ranged between 0.6 and 450 mu g/g dry weig ht (dw) and of methylmercury between 0.2 and 26 mu g/gdw. No differences in concentrations of either total mercury or methylmercury were observed betw een stranded and by-caught animals nor between males and females. However, a difference in mercury content of cetaceans from the North and Baltic Seas was found. A significant correlation between animal age and total mercury as well as methylmercury in all examined organs could be demonstrated. Pathological, microbiological and parasitological studies were performed on the animals. The majority of pathological lesions were caused by helminths , Lesions characteristic of acute or chronic intoxication with mercury coul d not be found. However, there were significant associations between mercur y levels and severity of lesions with respective to nutritional state of th e cetaceans examined, demonstrated by means of polychotomous logistic regre ssion for ordinal variables and adjusted for the effects of age and locatio n. (C) 1999 Elsevier Science Ltd. All rights reserved.