Freshwater midges of the Yukon and adjacent Northwest Territories: a new tool for reconstructing Beringian paleoenvironments?

Distributions of freshwater midges, including Chironomidae, Chaoboridae, and Ceratopogonidae, were analyzed along a transect of lakes extending north from Whitehorse (Yukon Territory) to the Arctic Ocean (Northwest Territories). Abiskomyia, Mesocricotopus, Monodiamesa, and Paracladius were restricted to arctic tundra lakes, whereas Chaoborus, Pseudochironomus, Polypedilum, and Glyptotendipes were clearly associated with forest and forest–tundra environments. Many other taxa were broadly distributed with little apparent regard to latitude or ecoclimatic region. Canonical correspondence analyses revealed that midge distributions were most strongly correlated with total Kjeldahl N, maximum lake depth, pH, and summer surface water temperature. The distribution patterns suggest that subfossil midges may provide valuable proxy evidence for paleoenvironmental conditions in the Beringian region of northwestern Canada and Alaska.