RELATIONSHIPS BETWEEN CONCENTRATIONS OF MERCURY IN LARGEMOUTH BASS AND PHYSICAL AND CHEMICAL CHARACTERISTICS OF CONNECTICUT LAKES

Concentrations of total mercury were determined for axial muscle tissu e of 438 largemouth bass Micropterus salmoides from 46 lakes represent ing five regions in Connecticut to determine relationships between mer cury concentrations and lake characteristics and to assess regional di fferences in mercury concentrations. Expected concentrations of mercur y (EHg) predicted for a length of 356 mm for each population ranged fr om 0.103 to 0.795 mu g/g wet weight. Principal components analysis rev ealed that, in general, two types of lakes were represented in the dat a set and were grouped based on hydrologic characteristics. Type-II la kes (artificial impoundments) had a significantly lower mean retention time than type-I lakes (natural drainage lakes) and a significantly l arger mean watershed area, watershed area : surface area ratio, waters hed area:lake volume ratio, and shoreline development index. Mean EHg was approximately 20% higher in type-II lakes (0.514 mu/g wet weight) than in type-I lakes (0.410 mu g/g wet weight; P = 0.08); factors most strongly correlated with EHg differed between lake types. Largemouth bass EHg in type-I lakes was most strongly correlated to particulate p hosphorus (r = -0.64) and conductivity (r = -0.55); EHg in type-II lak es was most strongly correlated with retention time (r = 0.76) and wat ershed area:lake volume ratio (r = -0.75). Stepwise multiple regressio n revealed that particulate P and mean depth accounted for 51% of the variability in EHg among type-I lakes. Retention time was the only var iable retained in stepwise regression of type-II lakes and accounted f or 57% of the variation in EHg. Largemouth bass EHg in type-I lakes wa s significantly different among regions, as were lake variables descri bing hardness, alkalinity, and productivity.