EVIDENCE OF TERATOGENS IN SEDIMENTS OF THE NIAGARA RIVER WATERSHED AS REFLECTED BY CHIRONOMID (DIPTERA, CHIRONOMIDAE) DEFORMITIES

Chironomids from two locations in an IJC "Area of Concern" in the Niagara River watershed and from one site in Lake Huron were sampled and classified as either normal or abnormal based on their menta ("teeth") deformities. The two Niagara River sites were the King's Bridge reference site and the Kane Dock coal tar contaminated area. The latter site was immediately downstream of an abrasives company located about 800 m downstream of the King's Bridge reference site. Among the 739 chironomids sampled from the King's Bridge reference site, 3.1% (23) possessed menta with deformities. This deformity frequency was similar to the 2.8% deformity frequency observed in a clean water site in Lake Huron. Chironomids removed from the coal tar contaminated site displayed a deformity frequency of 14%. The dominant invertebrate in the coal tar (PAH) contaminated sediments was the midge (Chironomus anthracinus), a non-biting fly larva referred to as a blood worm. Thus there was a significantly higher frequency of menta deformities downstream of the abrasives manufacturer's discharge than at the King's Bridge reference site (Student's "t" test, P < 0.05). The chironomids at the contaminated site were themselves contaminated with elevated levels of fifteen different PAHs. The PAH levels in the bodies of the deformed chironomids were higher than the levels in the undeformed chironomids collected at the same site. When over 200 chironomids with an average deformity frequency of 7.7% were taken from the PAH contaminated site and placed in clean (PAH uncontaminated) sediments taken from the King's Bridge Park reference site, the resulting F1 generation displayed a mentum deformity frequency of 4%. These rearing experiments indicated that few, if any, of the observed C. anthracinus menta deformities were passed on to the next generation.