RAPID: Invasive hydrilla and carbon cycling: leveraging an ecosystem-scale herbicide application to investigate feedbacks between invasive plants and greenhouse gas emissions

About This Grant

Hydrilla verticillata is an invasive aquatic plant that is rapidly spreading in freshwaters across the eastern United States, including the lower Connecticut River. With large environmental and economic impacts, hydrilla is one of the most problematic invasive aquatic plants in the United States. Hydrilla forms dense submerged mats or canopies, which impact native habitats, hydrology, carbon cycling, and recreation. To control the spread of hydrilla, experimental herbicides will be applied to affected areas in the lower Connecticut River in summer 2024. This RAPID project will leverage these herbicide applications as a unique plant-removal experiment to better understand the effects of hydrilla on freshwater ecosystems. The overarching goal of the project is to understand how this invasive aquatic plant can alter carbon cycling and greenhouse gas emission in inland waters. This research is important for understanding the full impacts of invasive aquatic plants on ecosystem function and potential linkages between climate change and invasive aquatic plants via greenhouse gases. Findings will inform aquatic plant management. This research will explore how carbon concentrating mechanisms that help invasives like hydrilla outcompete native species can shift ecosystem-scale primary productivity from using only carbon dioxide to also using bicarbonate, a non-gaseous form of inorganic carbon. Bicarbonate uptake by hydrilla has the potential to transfer carbon from the slow-cycling geologic pool (bicarbonate has geologic sources) to the faster-cycling biologic pool (carbon dioxide in inland waters largely comes from respiration). This study will use oxygen and carbon dioxide sensors and grab samples to compare ecosystem metabolism and carbon cycling in treated and untreated embayments. Weekly samples will be used to assess greenhouse gas emissions. Analyses will determine the extent of bicarbonate uptake by hydrilla and the cascading impacts on carbon cycling processes. 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.