Post-Glacial Chironomid Succession in Two Small, Humic Lakes in the New Brunswick-Nova Scotia (Canada) Border Area

A comparative study of the post-glacial succession of chironomid communities in two closely located small lakes in the New Brunswick-Nova Scotia border area revealed initial similarities in their fauna, and a subsequent period of parallel evolution. Both lakes originally possessed a Tanytarsus-Heterotrissocladius community indicative of an oligotrophic lake environment. For much of the subsequent period, Tanytarsus remains dominant in both lakes. At about 4000 B.P., the development of the two lakes began to diverge. For Wood's Pond evidence suggests gradual encroachment by Sphagnum produced an acid, ombrotrophic environment. Subsequent to this encroachment, the Tanytarsus fauna typical of shallow, humic lakes was replaced by a peat-pool fauna with Chironomus and Monopectrocladius as dominants. The shift from Tanytarsus to Chironomus coincides with evidence for the beginning of settlement, suggesting human interference. Portey Pond did not become encircled by peat, and maintained a stable chironomid fauna throughout the post-glacial period and up to the present.