Comparison of mercury bioaccumulation in eel (Anguilla anguilla) and roach(Rutilus rutilus) from river systems in East Anglia, UK - I. Concentrations in fish tissue

Concentrations of total mercury (T-Hg) were measured in eel and roach from five selected rivers in East Anglia, U.K, to determine Hg bioaccumulation i n fish throughout the region. Levels of T-Hg in sediment and river water we re also analysed to assess their potential as pathways to the fish. Accumul ated Hg levels in River Yare eel and roach continue to exhibit a strong pos itive relationship with surface sediment Hg levels, which are declining wit h time. Mercury in muscle from all sampled fish were below the limit set by the EU Directive (93/351/EEC). Analysis of muscle:liver (M:L) ratios confi rm that eel from all sites are in equilibrium with their environment. Vario us statistical methods (single factor analysis of variance, Spearman's corr elation coefficients) were performed on the experimentally derived data on mercury concentrations in fish flesh. Significant correlations were noted f or accumulated Hg in fish flesh with length and weight in eel, and length, weight and age in roach.