This 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.