Abstract
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 (SWT) (°C) and nitrate (NO3 + NO2-N)) 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 NO3 + NO2-N 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. Heterotrissocladius, Diamesa spp., and Pseudodiamesa were present in the coldest lakes. Chironomus, Diplocladius, and Protanypus were assemblages found in cold lakes affiliated with the littoral zone or alpine streams. The modern benthic chironomid communities collected from the alpine of subalpine lakes of Rocky Mountain National Park, Colorado, represent a range of climatic and trophic influences and capture the transition from cold oligotrophic lakes to warmer and eutrophic conditions.
Highlights
The remote lakes found at high elevations act as sentinels of change and are among the first bodies of water impacted by climate change [24]
The findings of this study indicate that glacial retreat is impacting the chironomid communities in the high elevation lakes located along the continental divide of the Colorado Rocky Mountains
Surface water temperature and NO3 + NO2-N were extremely and strongly negatively correlated, indicating that glacial retreat is responsible for the greatest amount of explained variance (14.95%) from the model
Summary
The remote lakes found at high elevations act as sentinels of change and are among the first bodies of water impacted by climate change [24]. Recent studies suggest that the range of invasive fish species and invertebrates will expand due to their ability to move to higher elevation lakes via warmer creeks with stable environments [34]. This movement will impact natural communities that exist in alpine lakes by altering food web and predator/prey dynamics [34]. Increases in terrestrial vegetation related to the upslope movement of timberlines will supply higher amounts of dissolved organic carbon (DOC) to subalpine and alpine lakes, which will increase productivity and potentially affect the diversity of high lake ecosystems [44]
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