SFS Annual Meeting

6/04/2024  |   10:30 - 10:45   |  Independence Ballroom C

A NATIONWIDE GEOSPATIAL MODEL OF RIVER SEDIMENT ACCRETION ON TIDAL WETLANDS INFORMS MANAGEMENT AND MONITORING OF SEA LEVEL RISE IMPACTS River sediment can support tidal wetland accretion in some geographic settings, but generalized patterns in the role of river sediment loads on tidal wetland accretion are unknown. We analyzed predictions of sediment delivered by 4,798 U.S. rivers to their adjoining tidal wetlands and calculated its accretion potential: this amounted to less than 1 mm per year for the majority of rivers in the Northeast, Southeast, and central Gulf of Mexico. We then compared these predicted tidal wetland accretion rates with relative sea level rise: river sediment accretion on tidal wetlands was less than sea level rise in 72% (Northeast), 90% (Southeast), 89% (Central Gulf of Mexico), 49% (Western Gulf of Mexico), and 31% (Pacific) of rivers in each region. The high proportion of rivers with a relatively small influence on their tidal wetlands’ accretion is due to the fact that 90% of U.S. rivers reaching the coast drain less than 35 square kilometers and thus have very small sediment loads. Despite this predicted shortcoming of river sediment to meet the accretion needs of tidal wetlands, half of our predictions that we were able to pair with short-term accretion measurements revealed that tidal wetlands were accreting faster than sea level rise. Autochthonous organic matter production and coastal-marine sediment are widely recognized as important contributors of elevation gain in tidal wetlands, but the limited influence of river sediment that our model revealed has implications for coastal science and management. These communities can explore our results in a geospatial web app.

Scott Ensign (Primary Presenter/Author), Stroud Water Research Center, ensign@stroudcenter.org;

Joanne Halls (Co-Presenter/Co-Author), University of North Carolina at Wilmington, hallsj@uncw.edu;

Erin Peck (Co-Presenter/Co-Author), University of Massachusetts Amherst, ekpeck@umass.edu;

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6/04/2024  |   10:45 - 11:00   |  Independence Ballroom C

Tracking anthropogenic salt signatures in urban streams Along urban streams and rivers, various processes, including road salt application, sewage leaks, and weathering of the built environment, contribute to novel chemical cocktails made up of metals, salts, nutrients, and organic matter. More work is needed to fully understand how sources of multiple contaminants vary along rural-to-urban flowpaths through different U.S. cities and how these contaminants can be exported from or retained within urban watersheds. To track the impacts of urbanization, we conducted longitudinal stream synoptic (LSS) monitoring in nine watersheds in five major metropolitan areas of the U.S. as well as routine monitoring at intensive Washington, D.C. and Baltimore sites. Results demonstrated that salt-derived ions (Ca^2+, Mg^2+, Na^+, and K^+) and commonly correlated elements (e.g. Sr, N, Cu) formed salty chemical cocktails that increased along rural to urban flowpaths across U.S. cities. Streams flowing through restored reaches and wide riparian buffer zones in parks did not show longitudinal increases in salty chemical cocktails along flowpaths. In these systems, flux data reveal the relative importance of uptake processes and dilution, suggesting that there is attenuation within these conservation and restoration areas. Temporally, road salt related pulses in salinity, primarily of Na^+, contribute to a large portion of salt fluxes from urban systems. Our results suggest that salty chemical cocktails may be a common water quality signature of urbanization, elevated salinity can be exported to receiving waters, and urbanization-related salinity can be prevented by or retained within conservation and restoration areas.

Sydney Shelton (Primary Presenter/Author), University of Maryland, College Park, sydneys8@umd.edu;

Sujay Kaushal (Co-Presenter/Co-Author), University of Maryland, skaushal@umd.edu;

Paul Mayer (Co-Presenter/Co-Author), United States Environmental Protection Agency, mayer.paul@epa.gov;

Tammy Newcomer-Johnson (Co-Presenter/Co-Author), US EPA, Newcomer-Johnson.Tammy@epa.gov;

Ruth Shatkay (Co-Presenter/Co-Author), University of Maryland, rshatkay@terpmail.umd.edu;

Joseph Malin (Co-Presenter/Co-Author), University of Maryland, College Park, joemalin@terpmail.umd.edu;

Megan Rippy (Co-Presenter/Co-Author), Virginia Tech, mrippy@vt.edu;

Stanley Grant (Co-Presenter/Co-Author), Virginia Tech, stanleyg@vt.edu;

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6/04/2024  |   11:00 - 11:15   |  Independence Ballroom C

ISOTOPE ENRICHMENT INCREASES ALONG THE SALINITY GRADIENT OF AN URBANIZING ESTUARY Estuaries are a key transition zone between freshwater and marine ecosystems that filter nitrogen and store carbon originating from upstream before they enter the ocean. The magnitude and timing of nitrogen (N) and carbon (C) sources (e.g. fertilizer, yard waste, fossil fuel combustion) can vary temporally and spatially (e.g. caused by seasonal fertilizer use upstream and weather patterns). These sources are potentially identifiable due to their unique isotopic signatures. Quantifying patterns and magnitudes of the variability of nitrogen and carbon isotopes will clarify how nutrient sources and fates vary along the estuarine salinity gradient. Furthermore, knowledge of sources can provide crucial information for upstream watershed management. The water quality of the Guana Estuary, located in northeast Florida, has been classified as impaired for nutrients and algae, primarily attributed to runoff from golf resorts and housing developments in the watershed. To identify the fate of anthropogenic N and C in the Guana Estuary, we collected sediment samples and apical foliage from the dominant vegetation from six sites spanning a salinity gradient quarterly. We analyzed these samples for ?15N, ?13C, and C:N. The least isotopically-enriched signatures were furthest upstream and increased linearly downstream along the salinity gradient, potentially indicating oceanic sources as opposed to anthropogenic sources from the watershed. Compared to sediments, plants were more enriched in C and N, suggesting plants are more responsive to changing inputs. Discrete water sampling captures instantaneous measurements; however, to integrate nutrient sources and fates over longer time periods, isotopic signatures are a key management tool.

Jenna Reimer (Primary Presenter/Author), University of Florida, reimerj@ufl.edu;

Alexander Reisinger (Co-Presenter/Co-Author), University of Florida, reisingera@ufl.edu;

Ashley Smyth (Co-Presenter/Co-Author), University of Florida, ashley.smyth@ufl.edu;

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6/04/2024  |   11:15 - 11:30   |  Independence Ballroom C

Biogeochemical Transformations and Dissolved Oxygen Dynamics along the Urban Watershed-Estuary Continuum Despite the crucial role of understanding and accurately mapping dissolved oxygen over space and time, the sensitivity of dissolved oxygen to physical gradients within and between ecosystems – such as water depth, diel cycles, and salinity – continue to impede water quality management and regulation. This research leverages continuous and discrete water quality data collected from the U.S. Mid-Atlantic region's Potomac and Anacostia watersheds, covering more than 160 km along the mainstem of the Potomac alone, to explore drivers of water quality and dissolved oxygen along the urban watershed-estuary continuum. We conducted longitudinal stream synoptic (LSS) monitoring across different climatic and hydraulic conditions including drought, tropical storms, snowfall, and snowmelt, where we observed longitudinal changes in organic matter quantity and quality, and significant relationships between organic matter and salinity were observed across sites, and tidal versus non-tidal hydrologies (p < 0.05). Preliminary analysis of continuous sensor data reflected the capacity of extreme events and anthropogenic inputs to disrupt or even reverse background trends in longitudinal dissolved oxygen and specific conductivity. Future work will combine sensor data, routine sampling, and longitudinal steam synoptic monitoring to better understand drivers and longitudinal patterns in dissolved oxygen, salinity, and organic matter, as well as the interplay of extreme climatic events and anthropogenic inputs in regulating biogeochemical transformations along the urban watershed-estuary continuum.

Weston Slaughter (Primary Presenter/Author), University of Maryland, College Park, wslaught@umd.edu;

Sujay Kaushal (Co-Presenter/Co-Author), University of Maryland, skaushal@umd.edu;

Paul Mayer (Co-Presenter/Co-Author), United States Environmental Protection Agency, mayer.paul@epa.gov;

Kaylyn Gootman (Co-Presenter/Co-Author), United States Environmental Protection Agency, Gootman.Kaylyn@epa.gov;

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6/04/2024  |   11:30 - 11:45   |  Independence Ballroom C

Addressing the sodium surge: An interactive model to inform management decisions in the Occoquan Reservoir Rising sodium concentrations in Northern Virginia’s Occoquan Reservoir—an important drinking water source for >1 million people and the country’s first planned indirect potable reuse project—is a critical management challenge for stakeholders (e.g., water and wastewater utilities, government agencies) as sodium is not removed during production of drinking water. Sodium in the reservoir originates from myriad natural and anthropogenic sources (e.g., geologic and urban weathering, chemicals used in water and wastewater treatment, road salts, industrial discharges, sodium-rich household products, etc.). Understanding the origin, fate, and dynamics of different sodium sources and their relative contributions to sodium concentration in the reservoir is critical information necessary to manage rising salinization. We developed a data-driven, computationally inexpensive, interactive pollutant transport (hydrologic + transit time) model that predicts daily sodium concentration in the Occoquan Reservoir up to the year 2100 based on user inputs. The model incorporates user-defined scenarios of future climate (e.g., greenhouse gas emissions), human behavior (e.g., population growth, deicer use) and socio-economic development (e.g., land-use changes, stormwater infrastructure). As a pilot test, the model was deployed interactively during the Executive Committee on the Occoquan System’s biannual meeting, where ~40 stakeholders explored different future scenarios for climate change, population growth, deicer use, land-use change, etc., and assessed the impacts of various interventions on reservoir sodium concentration in a collaborative setting. Such interactive models can be a valuable tool for improving stakeholder collaboration and enabling informed decision-making in managing sodium pollution at this site and similar environmental management challenges globally.

Shantanu Bhide (Primary Presenter/Author), Virginia Tech, bhidesv@vt.edu;

Stanley Grant (Co-Presenter/Co-Author), Virginia Tech, stanleyg@vt.edu;

Ahmed Monofy (Co-Presenter/Co-Author), Virginia Tech, monofy@vt.edu;

Jesus Gomez Velez (Co-Presenter/Co-Author), Oak Ridge National Laboratory, gomezvelezjd@ornl.gov;

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6/04/2024  |   11:45 - 12:00   |  Independence Ballroom C

The structure and stability of wild harvest food webs in coastal watersheds: a case study of southeast Alaska rural communities Coastal watersheds that couple terrestrial, freshwater, and marine habitats provide numerous ecosystem services. Importantly, these “ridge-to-reef” watersheds sustain diverse wild foods that support the nutritional, cultural, and economic well-being of many rural and indigenous communities across the world. However, key uncertainties in the diversity, structure, and resilience of wild harvest challenges integration of wild food systems into watershed management. Here, we examine the provisioning of wild foods from coastal watersheds to rural communities in southeast Alaska, a region characterized by a strong reliance on subsistence food harvest (~25% of caloric requirements). We employ food web approaches to quantify the diversity and structure of “wild harvest webs” (i.e., topology of energy flux) using highly resolved harvest data for 33 communities. We then draw on ecological theory to identify features of wild harvest webs that may promote harvest stability. Landscape heterogeneity was an important driver of harvest structure, influencing the accessibility of resources across terrestrial, freshwater, intertidal, and ocean habitats. We illustrate that seasonal asynchronies in resource availability across these four habitats result in diverse harvest webs with few strong and numerous weak interactions, an architecture that food web theory has shown to be highly stabilizing. Our analysis emphasizes the importance of managing watersheds to maintain productive and resilient wild food systems and illustrates how food web approaches can help inform such management.

Marie Gutgesell (Primary Presenter/Author), USDA Forest Service, Marie.Gutgesell@usda.gov;

Lauren Sill (Co-Presenter/Co-Author), Alaska Department of Fish and Game, lauren.sill@alaska.gov;

Ryan Bellmore (Co-Presenter/Co-Author), USDA Forest Service, james.r.bellmore@usda.gov;

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