INDEXING DEFORMITIES IN LIGULAE AND ANTENNAE OF PROCLADIUS LARVAE (DIPTERA, CHIRONOMIDAE) - APPLICATION TO CONTAMINANT-STRESSED ENVIRONMENTS

The severity of deformities in the ligulae and antennae of Procladius is indexed and both indices are expanded to include population and community indices and a general index of Chironomid Community Response. These biological indices are compared with Indices of Contamination derived from chemical data from the St. Lawrence River, Port Hope Harbour, Southern Indian Lake - Notigi Reservoir, Tobin Lake, and Last Mountain Lake. Biological and chemical indices both identified Lac St. Louis Site 4 on the St. Lawrence River as the most highly contaminated site and the Wupaw Bay site in the Southern Indian Lake - Notigi Reservoir as the least contaminated of the 23 sites studied. The increase in frequency and severity of deformities in spring and summer data from the Rat Lake basin suggests that larvae are sensitive to increased mercury availability resulting from the greater activity of mercury-methylating bacteria in warmer summer waters.