The phenology of aquatic community assembly, harmful blooms, and lake carbon cycling

Iowa State University, Ames IA

Investigators

Abstract

Cyanobacteria are a type of algae that can cause serious water quality problems, impairing recreation and drinking water resources. Cyanobacteria often thrive in nutrient enriched lakes, where their dense populations may consume so much carbon dioxide that they turn the lake into a sink for atmospheric carbon dioxide, reversing the typical role of lakes in the global carbon cycle. Despite this importance to water quality and global carbon budgets, ecologists have been unable to predict exactly when and where Cyanobacteria will become excessively abundant. This project seeks to improve our ability to predict the timing of dense Cyanobacteria populations in lakes using a novel approach that considers algal response to both current and to past environmental conditions they experience over a season. It has long been understood that the ecological community in a particular time and place is shaped not just by the current environmental conditions but by the plants and animals that lived there in the past. It is this consideration of sequence of events, i.e., phenology, which will be the focus of this research. This project will test whether the explosive growth of Cyanobacteria in lakes is related to the timing of nutrient supply due to weather and watershed interactions, in combination with the timing of excessive demand for carbon dioxide caused by prolific growth of phytoplankton when nutrients are abundant. These ideas will be tested by a detailed study of 16 nutrient-rich lakes that display variation in timing of Cyanobacteria dominance. This research will contribute to two critical environmental issues: harmful phytoplankton blooms fueled by nutrient enrichment, and the role of lakes in the global carbon budget. Through outreach to state and federal agency personnel and citizen groups, results will have immediate application in the improvement of public waters. This project will train a doctoral student and several undergraduate students in aquatic ecology, and provide opportunities for students to participate in an NSF-funded ADVANCE program, designed to advance women in scientific careers. An important broader impact of this project is that it will provide educational opportunities and career training for minority students through a partnership with a community college on the Iron Range of Minnesota.