Research
Quantifying & predicting landscape-scale ecological change in Vermont inland lakes
Over the past 40 years, all low nutrient lakes in Vermont have approximately doubled in phosphorus (P) concentrations, while oligo- and eutrophic lake ecosystems are stable or decreasing in P. We know that lake chemistry is changing, but know very little about the biological, ecological, and functional response of these systems to long-term shifts. In collaboration with the VT DEC and funding from the USGS Vermont Lake Studies and Water Resources Center, we are using a paleo-diatom data record to identify disturbance gradients and indicator species of ecological change in 103 inland Vermont lakes. In addition, we have conducted the first landscape-scale assessment of dissolved organic matter (DOM) composition and phytoplankton biodiversity across approximately 80 inland lakes over 4 years spanning trophic, land-use, and altitudinal gradients . This information provides insight into how lake biodiversity and carbon processing is changing in response to altered land-water connectivity and climate change pressure.
Environmental drivers of cyanobacteria bloom diversity and toxicity in Lake Champlain and its tributaries
In collaboration with the NSF EPSCoR BREE project and through an ongoing collaborative project on Lake Carmi funded by the VT DEC, we are integrating metagenomic approaches with high frequency environmental data, discrete nutrient stoichiometry, phytoplankton community composition, and paleolimnological data from lake sediment cores (Carmi) to predict environmental conditions triggering bloom formation and toxicity. This information will allow for rapid assessment of toxic bloom risk in Lake Champlain and predict future events with changing environmental conditions. Work on Champlain is led by Ph.D. student Katelynn Warner, work on Carmi is a collaborative effort with multiple lab members, including M.Sc. student Maria Alfaro and undergraduate honors thesis students Sarah Wasserman and Margaret Polifrone.
Re-defining a disturbance phenology for phytoplankton communities and ecosystem function
Anthropogenic disturbance is not only altering ecosystem function but shifting the amplitude of fluctuation in aquatic ecosystems. The scale of chaotic disturbance events currently occurring globally cannot be fully described by the steady-state equilibrium theory which assumes that ecosystems are converging toward a stable climax state. Within lakes, phytoplankton communities are sentinels of ecological change, responding to disturbance and shaping biogeochemical cycles through fluctuation in their biomass, primary productivity, and functional traits. Although phytoplankton and benthic algae generally have a doubling time of hours to days, traits such as dormancy and alternative metabolic strategies allow persistence of populations across annual to multi-decadal time scales. The goal of this project is to describe a disturbance phenology framework for algal community assembly that is scalable across space and time in order to predict feedbacks and threshold shifts in lake ecosystem function.
