Mercury in Crayfish Species from Thirteen Ontario Lakes in Relation to Water Chemistry and Smallmouth Bass (Micropterus dolomieui) Mercury

Abstract

Total mercury was determined in crayfish from 13 lakes in South-Central Ontario that receive no direct discharge of mercury to their watersheds. Mercury concentration in crayfish abdominal muscles ranged from 0.022 to 0.614 μg∙g−1 wet weight and was positively related with weight in Cambarus bartoni, C. robustus, Orconectes obscurus, O. propinquus, and O. virilis. Bioaccumulation of mercury in the early maturing and comparatively small body-sized O. propinquus was faster than in any other species. There were significant differences in mercury concentrations in crayfish among the lakes. Conductivity of lake water alone explained 54% of the variability observed among lakes for mercury in abdominal muscle of a 10-g crayfish. Moreover, mercury levels in C. bartoni and C. robustus were significantly higher in lake inlets than in the corresponding lake basin. Mercury in smallmouth bass was also positively correlated with crayfish mercury. From these results, we conclude that high mercury concentrations in biota were related to low mineralization of lake or inlet water and to the sensitivity to acidification. We also recommend that crayfish be used as biomonitors of mercury in addition to proving useful toward a better understanding of mercury pathways in these remote lakes.