This experiment tested the effects of heavy metal contaminated sediment on emergence of chironomids. The number of adults emerging from test chambers containing an uncontaminated sediment and ones with sediment containing 1030 ppm cadmium (Cd), 17,300 ppm zinc (Zn), and1640 ppm chromium (Cr) were observed for rqdays. It was found that emergence was reduced by over three times and delayed for two days in the heavy metal contaminated sediment.

Chironomid larvae were maintained for 17 days in sediments with various heavy metal levels . The control sediment had levels of 0.6 ppm cadmium, 17 ppm chromium and 77 ppm zinc . The most contaminated sediment had levels of 1030 ppm cadmium, 1640 ppm chromium, and 17300 ppm zinc .The mean length and weight of the larvae from the control sediment were 1 .83 cm and 2 .86 mg. The mean length and weight of larvae from the most contaminated sediment were 0 .82 cm and 0 .20 mg. A linear relationship was found for the square root of length versus metal levels in the sediment .

Avoidance reactions of chironomid larvae to contaminated sediment taken from a heavy metal impacted lake were studied . Heavy metal levels in the test sediment ranged from background of o .6 parts per million (ppm) cadmium, 77 ppm zinc and 17 ppm chromium to a maximum of 1,029 ppm cadmium, 17,262 ppm zinc and 2,106 ppm chromium . A linear relationship was established between cadmium and zinc levels in the sediment and avoidance by chironomids .An approximate threshold avoidance of metals in the sediment was determined to be between 213-422 ppm cadmium, 4385-8330 ppm zinc and 799-1513 ppm chromium .

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