Is Glacial Retreat Impacting Modern Benthic Chironomid Communities? A Case Study from Rocky Mountain National Park, Colorado.

Authors: Danielle Haskett Jennings*, South Dakota State University
Topics: Biogeography, Mountain Environments, Global Change
Keywords: chironomid, glacier retreat, nitrogen, boron, alpine lake
Session Type: Virtual Paper
Day: 4/7/2021
Start / End Time: 8:00 AM / 9:15 AM
Room: Virtual 40
Presentation File: No File Uploaded

The aim of this study was to determine which environmental variables are responsible for modern benthic chironomid distributions in a glacial setting. The chironomid communities from nine alpine lakes were assessed and forty-three individual taxa were extracted and identified. Surface water temperature and nitrate were strongly and negatively correlated (-0.82, p=0.007), suggesting that glacial meltwater (the driver that explains both surface water temperature and nitrate is the environmental variable that explains the most variance (15%). On average, lakes receiving glacial meltwater were 2.62°C colder and contained 66% more nitrate than lakes only receiving meltwater from snow. The presence of taxa from the tribe Diamesinae indicates very cold input from running water, and these taxa may be used as a qualitative indicator species for the existence of glacial meltwater within a lake catchment. The presence of boron and the percentage of carbon in bulk sediment (i.e., lake productivity) are also responsible for the distribution of modern chironomid communities in Rocky Mountain National Park, Colorado. While the temperature most likely responsible for chironomid distribution is surface water temperature, anthropogenic activities may no longer be separated from natural variables for lakes in Rocky Mountain National Park, Colorado. This is the first to study to address the relationship between benthic chironomids and their response to glacial retreat in an alpine lake setting.

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