Chironomids (Insecta –Diptera) as indicators of climate change in the Neotropics

MASSAFERRO, J

Flores, Guatemala

Workshop; GLAD800 Drilling in Lake Peten-Itza (Guatemala): A lowland Neotropical Record of; 2004

ICDP International Continental Scientific Driling Program

In recent years, subfossil chironomids (non-bitting midges) have proven to be a powerful independent paleo-proxy indicator of environmental change. They are being increasingly used as indicators of eutrophication, water-level changes and, especially as indicators of climatic change . Because midge abundance and distribution are strongly influenced by mean July air temperature, this can be used to infer past climate by analysing changes in midge assemblages recovered from lake sediments. Chironomid assemblages from lake sediments are extremely sensitive to temperature changes being able to pin-point climatic oscillations of short duration and low amplitude. Nevertheless, the best results have been achieved in studies by using a multi-proxy approach that enables the comparison of chironomids to other lines of evidence such as pollen sequences, diatom profiles, oxygen isotopes  or chemical analysis in a sedimentary column. In this study I propose to develop a modern chironomid-temperature calibration data set based on surface sediments taken along a N-S and a E-W transect of lakes located in the Yucatan Penninsula (Central America). These transects are characterized by strong precipitation/evaporation and temperature gradients.  The modern data set will be used to develop a transfer function to reconstruct past temperatures from fossil chironomid assemblages. This project is a contribution to the Lake Peten Drilling Project, an initiative within the International Continental Scientific Drilling Program (ICDP) with the ultimate goal to reconstruct climate change in the Neotropics spanning multiple glacial to interglacial cycles.