Modern Limnological and Paleolimnological Applications of Diatoms in Minnesota Lakes

Abstract

The following chapters represent a continuity of diatom research in Minnesota lakes. In Chapter 2, the study on Upper and Lower Red Lakes demonstrates the use of well-established paleolimnological proxies to assess eco-limnological change in a pair of large shallow lakes and inform management of the lakes by the Red Lake Tribal Department of Natural Resources and the Minnesota Pollution Control Agency. Highlighted here was the use of diatoms using traditional morphological and geochemical approaches to reconstructing limnological history. In Chapter 3, I present a review on resurrection ecology as a new tool in the paleolimnological tool belt. This chapter highlights diatoms as prime candidates for resurrection ecology studies and the use of sediment eDNA to guide such studies. Chapter 4 uses the recommendations in Chapter 3 to leverage diatom microfossils and their DNA to examine the influence of 20th century dust deposition on productivity and community composition. This study highlights the first use of sediment DNA to characterize diatom assemblage changes in a North American lake, and furthermore highlights the beneficial uses of paired microfossil-DNA diatom proxies. In Chapter 5, I used sediment DNA to describe the genomic diversity of diatoms across lakes of Minnesota. The diatom diversity described here corresponds to the distribution of lake types across Minnesota that can be characterized by diatoms observed in light microscopy or by their DNA signatures. Furthermore, the paired use of diatom microfossils and sediment DNA showed similar limnological trends in the paleolimnological record of two lakes.