Deciphering the Ecology of Key Diatom Taxa to Understand Climate-Induced Changes in West Greenland Lakes over the Holocene

Abstract:

Paleolimnological records from southwest Greenland reveal that diatom communities have not changed in a similar way to other regions of the Arctic, and in general, do not show synchronous change across this area. There are a number of cases in which lakes in close proximity to each other show opposite community changes over the Holocene. These changes in diatom fossil profiles have been difficult to interpret due to a lack of explicit ecological information for key species. The objective of this project is to decipher the ecology of key diatom species that are abundant across these paleolimnological records. We hypothesize that climate-driven changes in nutrients and water column stability (via its effects on light availability) are key factors shaping diatom community structure in these lakes. We assessed the requirements of particular taxa for nutrients and light through comparative lake sampling and resource bioassays. A whole-lake manipulation in which water column stability was reduced through enhanced water circulation was also conducted to assess the response of key taxa to this change. We found that the relative abundances of key diatom taxa are under complex control by the interactive effects of nutrients and light. We discuss how these results will enhance interpretation of climate-induced changes in Arctic lakes in this region.