Invasive water chestnut hinders tidal wetland development

Consistent shoreline development and urbanization have historically resulted in the loss of wetlands. However, some construction activities have inadvertently resulted in the emergence of new tidal wetlands, with prominent examples of such anthropogenic wetlands found within the Hudson River Estuary. Here, we utilize two of these anthropogenically created tidal wetlands to explore the sedimentary and hydrologic conditions driving wetland development from a restoration perspective. Tivoli North is an emergent freshwater tidal marsh, while Tivoli South is an intertidal mudflat with vegetation restricted to the seasonal growth of invasive water chestnut during summer months. Using a combination of sediment traps, cores, and tidal flux measurements, we present highly resolved sediment budgets from these two protected bays and parameterize trapping processes responsible for their divergent wetland evolution. Utilizing a 16‐year tidal flux dataset, we observe net sediment trapping in Tivoli North for most years, with consistent trapping throughout the year. Conversely, flux measurements at Tivoli South reveal net sediment loss over the study period, with trapping constrained to the summer months. Here, we explore potential mechanisms responsible for these contrasting accumulation regimes, including initial geological differences, sediment loading, and human land use changes, with a focus on the invasion of emergent aquatic vegetation. Results suggest that water chestnut is contributing to these divergent morphologies by inhibiting sediment trapping and facilitating erosion, thereby preventing marsh nucleation in Tivoli South. The longevity of this dataset highlights the capacity of aquatic vegetation to regulate sediment exchange and geomorphology in enclosed bays when provided with an opportunity to colonize. The results of this project provide evidence to inform the management of restoration projects in river systems with tidal wetlands, especially those affected by invasive species of aquatic vegetation. We utilize a 16‐year tidal flux dataset alongside sediment cores and traps to create high‐resolution sediment budgets that assess the impact of invasive aquatic vegetation on sediment trapping in freshwater tidal wetlands. Results show that water chestnut (Trapa natans) invasion impedes long‐term sediment trapping and facilitates erosion, preventing marsh initiation and growth in off‐river waterbodies along tidal rivers.