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Decoding Diatoms
Sediment records of past algal communities inform today’s climate change investigations
by Margaret Nagle

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Thresholds of change

In lakes in Maine, the Rockies and the Northern Plains, three University of Maine graduate students are using the historical records found in lake sediment cores to help reconstruct the past and tease apart the environmental catalysts of change in today’s aquatic systems.

The research by master’s students Kristin Ditzler and Heather Arnett, and Ph.D. student Courtney Salm is contributing to our understanding of the thresholds of change through time, including the triggers and how they can be managed or even precluded.

Ditzler, from Hershey, Pa., is assessing the effects of white perch removal on the frequency of algal blooms in Maine lakes. In the high-elevation lakes of the Rockies, Arnett, from Rochester, Minn., is studying how much nitrogen pollution is introduced from the atmosphere, and what effect such deposition has on algae in the aquatic ecosystems of all alpine lakes. Salm, from Sheboygan, Wis., is looking for patterns of food web interactions in the paleolimnology record of saline lakes, assessing the influence of lake-specific ecological processes on diatom-based climate reconstructions. The focus is on how ecological factors intrinsic to each lake affect the diatom record.