Mercury Accumulation in Millipedes (Narceus spp.) Living Adjacent to a Southern Appalachian Mountain Stream (USA).

Millipedes are among the most important processors of leaf litter in temperate forests. Through consumption of leaf litter, millipedes may be exposed to mercury that accumulates in leaf tissues prior to senescence. To investigate mercury uptake in millipedes, Narceus spp. were collected from a remote site in the southern Appalachian Mountains, an area known to receive high mercury deposition. Additionally, aquatic primary consumers (larval caddisflies and stoneflies), brook trout (Salvelinus fontinalis) and rainbow trout (Oncorhynchus mykiss) were collected from the same site for comparisons of mercury concentrations and percent methylmercury. Bioaccumulation factors for millipedes were 18.5 and 20.2 for total and methylmercury, respectively. At this site, the mean THg concentration in millipedes was ~ 10 × greater than both brook trout and rainbow trout and ~ 200 × greater than that of aquatic primary consumers. Millipede THg concentrations ranged from 222 to 1620 ng/g ww in an area where EPA fish consumption criteria (300 ng/g MeHg in fish tissue, ww) were not exceeded. The mean percent methylmercury in millipedes was 1.4%, suggesting these animals were accumulating large quantities of inorganic mercury.