Age- and size-specific patterns of heavy metals in the organs of freshwater fish Abramis brama L. populating a low-contaminated site.

Concentrations of cadmium, copper, mercury, lead and zinc were determined by atomic absorption spectrophotometry in the muscle, gill and liver of bream Abramis brama L. to study the relationship between the heavy metal load of fish and their age and size, and the seasonal variation of pollutant loads. Fish were collected from the Western basin of Lake Balaton (Hungary) in October 1999 and May 2000. The average metal concentrations of different organs varied in the following ranges: Cd 0.42-2.10; Cu 1.77-56.2; Hg 0.01-0.19; Pb 0.44-3.24; Zn 10.9-82.5 microg g(-1) dry weight. The highest Cd, Cu, Pb and Zn concentrations were detected in the gill or liver of fish, whereas the highest Hg concentrations were measured in the muscle. In the liver of bream for cadmium, copper and mercury the Pearson correlation analysis revealed positive associations related to age and size (length, net weight), as well as for the mercury load of all three investigated organs. In the muscle and gill the copper, lead and zinc concentrations, similarly to the lead and zinc concentrations of the liver, the associations related to age and size were negative. The correlations between the heavy metal concentrations of organs and the individual condition factors of fish samples proved to have opposite trends compared to those related to the age and size of fish. The seasonal variations in the heavy metal load of bream could be attributed rather to the seasonal change in the condition factor of fish than to variations in the pollutant load of the site.