CAREER: Lakes on a Changing Landscape: A Disturbance Phenology for Phytoplankton Communities and Ecosystem Function

University Of Vermont & State Agricultural College, Burlington VT

Investigators

Abstract

Algae in freshwater lakes are sentinels of environmental change because they respond rapidly to disturbances. As they respond to disturbance, algae alter their surrounding environment through fluctuations in their growth, the processing of carbon and nutrients, and biotic interactions. This makes algae important mediators of lake ecosystem functions such as nutrient cycles and gas exchange. In the past, the regular seasonality of lake ecosystem processes made it possible to predict the composition of algal communities and the traits that influence lake ecosystem function. Lake ecosystems, however, are changing rapidly in response to multiple interacting environmental change disturbances, making previously predictable seasonal processes such as ice cover, evaporation, and run-off increasingly uncertain and chaotic. This project will identify algal traits that confer persistence across a gradient of disturbance intensity over short and long timescales. This project seeks to understand how algal communities form and influence ecosystem function, not as a disruption to expected stable conditions, but as a fluctuating, dynamic process. As part of this CAREER proposal, the research will be integrated into undergraduate curriculum and will train undergraduates, a graduate student, and a postdoctoral researcher using collaborative team science approaches. Through a partnership with lake managers and professional workshops, findings will be communicated with stakeholders and translated into management action. This CAREER award aims to describe a disturbance phenology framework for phytoplankton community assembly that is scalable across space and time in order to predict feedbacks and threshold shifts for lake ecosystem function. First, the project will seek to understand the heterogeneity of algal responses to stressors across nearshore benthic and open water pelagic vertical zones to better predict ecosystem scale response to stochastic events. Across lake zones, synchronous fluctuations of phytoplankton communities are expected to amplify and destabilize ecosystem function, measured as lake metabolism, carbon dioxide, and methane flux. Second, the project will investigate phytoplankton traits that confer persistence across time scales, and will test the hypothesis that traits which confer persistence in response to short term, stochastic disturbance such as dormancy or alternative metabolic strategies will be recruited to communities over multi-decadal time scales. Hypotheses will be tested across scales in laboratory microcosms, outdoor mesocosms, and using modern and paleolimnological approaches across a trophic gradient in five lakes. Experimental mesocosms, high-frequency sensor arrays, and microscopy facilities will be integrated into undergraduate limnology, phycology, and ecosystem ecology curriculum aimed at training students in team science, experimental design, and ecological theory. This project is jointly funded by the Population and Community Ecology Cluster and Ecosystem Science Clusters in the Division of Environmental Biology and the Established Program to Stimulate Competitive Research (EPSCoR). 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.