Larval chironomid mouthpart deformities are used as indicators of anthropogenic stress. However, there are limited data on the incidence of naturally occurring deformities. Chironomid larvae were collected from 252 reference sites throughout the Great Lakes by Environment Canada from 1991 through 1993. Overall incidence of mentum deformities was 2.27% for Procladius (SE = 0.46, n = 1055), 2.15% for Chironomus (SE = 0.51, n = 839), 1.27% for Heterotrissocladius (SE = 0.57, n = 393), 1.38% for Tanytarsus (SE = 0.61, n = 363), and 3.25% for Polypedilum (SE = 1.07, n = 277). The most common deformity was one missing tooth in the mentum. Deformity frequency was highest in Northern Channel and Georgian Bay of Lake Huron. However, incidences were homogeneous among regions (G-test, p > 0.05). In examining contaminated conditions, a result greater than one 95% confidence interval above these reference deformity frequencies should be considered significantly elevated from baseline levels.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science