LATE HOLOCENE CLIMATE CHANGE IN NEW ENGLAND AS INFERRED FROM CHIRONOMID REMAINS IN LAKE SEDIMENTS

The use of chironomid remains and transfer functions to infer past temperatures has been shown to be an effective tool in the study of late-glacial and early Holocene climate change in Atlantic Canada and Europe. In this study, we use fossil chironomids from New England lake sediments to study more recent and more subtle climate changes. We are interested in the time period known as the Little Ice Age (approximately AD1450 - 1850). Chironomids are a diverse insect group (Diptera: family Chironomidae) which is distributed worldwide and the larval stages live in all aquatic habitats. Several environmental factors, including temperature, determine the distribution of species. In order to construct transfer functions for chironomids and temperature, modern surface samples have been collected and analyzed to extend the existing training set from northern Atlantic coast regions into southern New England. Tests of inference models using the entire Atlantic coast set as well as only the New England set show that a subset of these data produce the most accurate temperature reconstructions. The models will be tested using both summer lake-surface temperatures and mean July air temperatures. Results to date indicate that in some ponds, a cooler period corresponds to the Little Ice Age time period, with a change in temperature of 1-2° C. This result suggests that chironomids may be effective for temperature reconstruction throughout the Holocene period. This study is part of a large multiproxy effort in New England which also includes stable isotopes, sediment geochemistry, diatoms, and pollen.