CAREER: Why Are Ponds Biogeochemical Hotspots? Examining How Ecosystem Structure and Function Scale with Waterbody Size

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Ponds are small, shallow, and globally abundant waterbodies that provide important ecosystem services: ponds cycle nutrients, filter contaminants, promote high biodiversity, and regulate carbon emissions and storage. Several metrics of ecosystem function are disproportionately greater in ponds than lakes, including greenhouse gas emissions, ecosystem productivity, and nutrient concentrations. The greater biogeochemical activity in ponds may be due to stronger connections between bottom (benthic) and surface (pelagic) waters, a term called benthic-pelagic coupling. This research examines how benthic-pelagic coupling influences pond ecosystems using field surveys and whole-pond manipulations, which includes training of undergraduates, graduate students, and a postdoctoral researcher. This project further examines how the public use ponds and perceive water quality, informing the establishment of appropriate pond water quality standards that account for benthic-pelagic coupling. A key feature of this project is the close interaction of researchers with public agencies that regulate these aquatic habitats for citizen enjoyment and ecological functions.Aquatic ecosystem function reflects processes occurring in both benthic and pelagic habitats, yet a framework integrating benthic-pelagic coupling with ecosystem function is lacking. This CAREER award links benthic-pelagic coupling to ecosystem function in temperate ponds, which offer an ideal study system due to the variable strength of benthic-pelagic coupling across ponds and their tractability for whole-ecosystem manipulations. The project focuses on two metrics of ecosystem function: ecosystem metabolism and greenhouse gas production and emissions, which reflect organic matter processing. The first goal of the project links the strength and timing of benthic-pelagic coupling to ecosystem function by sampling ponds with different mixing regimes, and by establishing experimental ponds that mix rarely, intermittently, or often. The second goal of the project determines how light availability and animal communities mediate benthic-pelagic coupling, which will be tested in experimental ponds and integrates research with an undergraduate limnology course. The third goal of the project establishes how benthic-pelagic coupling influences water chemistry and public perceptions of water quality, which includes public outreach, an undergraduate course, and partnerships with state waterbody managers. Ultimately, our framework to link benthic-pelagic coupling with pond carbon and nutrient cycling will help us to understand how small and shallow waterbodies function and predict how they will respond to environmental change such as warming, browning, eutrophication, and algal blooms.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.