Doctoral Dissertation Research: A Paleolimnological Investigation of Climate and Nitrogen Impacts on Primary Producers in Greenland Lakes and Community Water Supplies

This doctoral dissertation research improvement project will use ancient lake sediment records to reconstruct 5,000-year histories of ecosystem changes in Arctic lakes that are of particular relevance to Northern communities. Though many remote Arctic villages rely on lakes for critical ecosystem services like drinking water reserves and agricultural irrigation, these small water supplies are insufficiently monitored and their susceptibility to changing climate and land use have been minimally investigated. This study will examine what factors, including temperature and nutrient inputs, have most influenced the biological productivity and diversity of photosynthetic organisms in Arctic lakes over multi-decadal and multi-millennial timescales. A second goal of this study is to provide formal training to the doctoral student in building international collaborations between U.S. scientists and Arctic Indigenous communities. The doctoral student will foster relationships between the United States and Greenland as a foundation for a career in collaborative research that incorporates local and Indigenous knowledge for the benefit of Northern communities. In response to warming in Arctic regions that outpaces global trends by four-fold, Arctic landscapes are “greening” and ecosystems, including those within lakes, are becoming more productive. This work examines the roles of temperature shifts and changing nitrogen cycling in driving changes in algal and cyanobacterial communities in lakes. This project employs a novel methodology to assess productivity through quantifying numerous sedimentary pigments. Pigments have many strengths as proxies, including their organism class or taxonomic specificity and their ability to reflect organisms that do not produce hard macrofossils, which are particular assets for work that aims to understand trends in cyanobacterial communities. Quantifying sedimentary pigments of different organisms can both provide insight on what drives bulk primary productivity and characterize how individual groups of primary producers might respond. This research will advance the use of this underutilized methodology, which is potentially applicable in many regions where changing lacustrine algal or cyanobacterial communities and/or eutrophication are a societal concern. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.