Metal Regulation, Tolerance, and Body Burdens in the Larvae of the Genus Chironomus

Bioaccumulation of metals are determined and compared for two populations of chironomid larvae collected from acidic lakes differing in their metal contamination. Results from laboratory experiments indicated that chironomid larvae from the more contaminated lake were able to regulate, or control their accumulation of Cu, Ni, and to some extent, Mn. Both populations regulated Zn, and neither population could regulate Pb or Cd. When larvae from the less contaminated site were exposed to sediments from the more contaminated lake, their growth was retarded and metals were accumulated to higher concentrations than for the native population. The data indicate that chronic exposure to elevated metal levels may result in the development of metal tolerance.