SFS Annual Meeting

6/06/2024  |   13:30 - 13:45   |  Philadelphia Ballroom

The Lamprey River Hydrological Observatory: Suburbanization and changing seasonality The Lamprey River Hydrological Observatory (LRHO) was established in 1999 to address the effects of suburbanization on hydrology, biogeochemistry and water quality. The LRHO is located in southeastern New Hampshire (USA) and comprises a basin area of 554 km2 that drains into the Great Bay Estuary. Work in the LRHO is motivated by four overarching questions focused on interactions among suburbanization, climate and watershed-scale processes: (1) how do suburbanization and associated changes in land cover drive long-term trends in surface water chemistry? (2) how do watershed attributes influence surface and groundwater chemistry? (3) how does suburbanization affect the long-term nitrogen (N) balance? and (4) what is the effect of changing seasonality and climate variability on watershed biogeochemical processes in a suburban landscape? The LRHO was established by Bill McDowell in the spirit of the whole-ecosystem approach to understanding how terrestrial-aquatic linkages change as a result of the suburbanization process. Data records now include twenty years of weekly wet deposition and surface water chemistry measurements and ten years of weekly greenhouse gas data and high-frequency water quality sensor data. Here we will summarize some of the major findings from this hydrological observatory that has been sustained through multiple funding opportunities and that has offered a platform for the training of multiple graduate students and post-doctoral researchers.

Adam Wymore (Primary Presenter/Author), University of New Hampshire, adam.wymore@unh.edu;

Michelle Shattuck (Co-Presenter/Co-Author), University of New Hampshire, Michelle.Shattuck@unh.edu;

Jody Potter (Co-Presenter/Co-Author), University of New Hampshire, jody.potter@unh.edu;

William H McDowell (Co-Presenter/Co-Author), University of New Hampshire, bill.mcdowell@unh.edu;

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6/06/2024  |   13:45 - 14:00   |  Philadelphia Ballroom

A Story Map for Visualizing the hydrodynamics of the New Hampshire Great Bay Visualizing data from hydrodynamic models for the web in a consistent and approachable manner can be challenging. Here, we explore the implementation of a visualization approach using R-Shiny and ArcGIS Story Maps. This approach presents a clear and user-friendly version of model outputs from the Regional Ocean Modeling System (ROMS) for the Great Bay of New Hampshire and Maine. By creating embeddable Shiny Apps, we have leveraged R and Python code to visualize bed shear stress, water depth, and velocity over a 5-day model run in a tidal estuary. The bed shear stress data is presented as aggregated data for the ROMS model run. Water depth and velocity are initially shown with views highlighting the state of the estuary at high tides, low tides, and the time steps with the maximum velocity of flow into and out of the estuary. To ensure the visualization is legible, water velocity vectors are subsampled. Another view presents these water depths and velocities in a self-advancing loop through the datasets 15 minute time steps, allowing users to observe changes in flow direction, velocity, and water level over time. The Story Map is available here: https://arcg.is/1ePK0H2

Miguel Leon (Primary Presenter/Author), University of New Hampshire, miguel.leon@unh.edu;

Tom Lippmann (Co-Presenter/Co-Author), University of New Hampshire, lippmann@ccom.unh.edu;

William H McDowell (Co-Presenter/Co-Author), University of New Hampshire, bill.mcdowell@unh.edu;

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6/06/2024  |   14:00 - 14:15   |  Philadelphia Ballroom

EFFECTS OF TEMPERATURE AND SEASONAL LIGHT REGIME ON NUTRIENT UPTAKE IN FIVE THERMALLY STABLE ARCTIC SPRING-STREAMS Light and temperature, both important drivers of ecosystem processes such as nutrient uptake, are strongly correlated in most ecosystems. Light availability and temperature, for example, are usually highest during summer and lowest in winter. Temperature controls nutrient uptake through changes in physiological demand, while light drives uptake via altered autotrophic activity and production. Because of their near-ubiquitous seasonal correlation, it is difficult to isolate the individual effects of light and temperature under natural conditions. The unique environmental context of arctic spring-streams provides an exception: they exhibit relatively stable water temperatures (i.e., ±2°C annually) but are exposed to extreme annual light fluctuations (i.e., 24-hr light in summer, ~24-hr darkness in winter), which effectively uncouples the seasonal effects of light and temperature. We conducted semi-monthly instantaneous slug-injections of ammonium (NH4+-N) and soluble reactive phosphorus (SRP) year-round in five spring-streams differing in temperature (range among streams ~2-12°C). Preliminary analyses show similar seasonal trends between NH4+-N and SRP across streams, with NH4+-N uptake greater than SRP uptake. Both nutrients showed highest ambient concentrations during winter (i.e., lowest light) and highest uptake during spring. Ambient NH4+-N concentration was not correlated with mean stream temperature but uptake generally increased with temperature among streams, particularly in summer. In contrast, SRP ambient concentration was greater in warmer streams, but SRP uptake showed no clear relationship with temperature among streams. By comparing nutrient uptake spatially and temporally in arctic spring-streams along a thermal gradient, we aim to better understand light and temperature as independent drivers of stream nutrient dynamics.

Tori A. Hebert (Primary Presenter/Author), The University of Alabama, tahebert@crimson.ua.edu;

Adam C. Hensley (Co-Presenter/Co-Author), The University of Alabama, hensley.adam4@gmail.com;

Annie G. Blalock (Co-Presenter/Co-Author), The University of Alabama, agblalock@crimson.ua.edu;

Carla L. Atkinson (Co-Presenter/Co-Author), The University of Alabama, carla.l.atkinson@ua.edu;

Jonathan P. Benstead (Co-Presenter/Co-Author), University of Alabama, jbenstead@ua.ed;

Alexander D. Huryn (Co-Presenter/Co-Author), The University of Alabama, huryn@ua.edu;

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6/06/2024  |   14:15 - 14:30   |  Philadelphia Ballroom

LONG TERM WATER QUALITY RECORDS QUANTIFY NUTRIENT EFFECTS ON PRIMARY PRODUCTION IN THE KLAMATH RIVER, CALIFORNIA Despite well-established relationships between nutrient concentrations and primary production in lakes, clear relationships between nutrients and riverine gross primary production (GPP) are sparse. We investigated the effects of variation in nutrients on GPP in the Klamath River, California where high nutrient concentrations, high GPP, and high autotrophic biomass impair water quality. We calculated daily ecosystem metabolism at 2 sites for 15 y during May–October from high-frequency dissolved O2 data and we used biweekly nutrient data to interpolate daily nutrient concentrations from data collected by the Karuk and Yurok Tribes. We used multiple regression models to examine nutrient effects among sites and years, and we used time-series models to examine effects on daily rates of GPP within years. We incorporated light, flow, total nitrogen(TN) and soluble reactive phosphorus (SRP) in models. The Klamath River had spring and summer GPP peaks and high within and among year variability in GPP, with mean summer GPP ranging from 4.1–13.4 gO2m-2d-1 at site 1 to 6.6–12.6 gO2m-2d-1 at site 2. Mean summer GPP increased with increasing light, decreasing flow, and increasing TN. We did not detect an SRP effect, due to persistently high levels that did not limit growth or because biological uptake overshadowed positive effects of SRP. Within years, preliminary results indicate strong effect sizes of TN and SRP, suggesting that water column nutrients may be most influential seasonally. Identifying the effect of nutrients on fluxes of GPP in rivers will help inform ecologically relevant nutrient goals in rivers.

Laurel Genzoli (Primary Presenter/Author), University of Montana, laurel.genzoli@umontana.edu;

John R. Oberholzer Dent (Co-Presenter/Co-Author), Karuk Tribe Department of Natural Resources, joberholzer@karuk.us;

Eli Asarian (Co-Presenter/Co-Author), Riverbend Sciences, eli@riverbendsci.com;

Alice M. Carter (Co-Presenter/Co-Author), Flathead Lake Biological Station, University of Montana, alicecarter05@gmail.com;

Robert O. Hall (Co-Presenter/Co-Author), Flathead Lake Biological Station, University of Montana, bob.hall@flbs.umt.edu;

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6/06/2024  |   14:30 - 14:45   |  Philadelphia Ballroom

Controls on major solutes within the drainage network of a central Himalayan River system Chemical weathering processes play an important role in regulating the chemistry of any water body, and thus are essential for understanding ecosystem function. The drivers responsible for regulating solute release during weathering are likely to vary from biome to biome. Himalayan river systems transport large quantities of both solutes and suspended sediment to the global ocean due to rapid weathering in this tectonically active region. Surface water samples were collected at different elevations (169 m-3989 m) from sixteen stations along Langtang-Narayani Himalayan River system in central Nepal on a monthly basis in low elevation sites and on a bi-monthly basis in high elevation sites for one year in order to investigate the geochemical processes, transport rate of major solutes and sediment and estimate the erosion rate of the basin. Seasonality has a strong influence on the transport rate of major solutes and sediment. Carbonate weathering contributes more solute flux than the silicates within the basin. The silica and cation export rates were 12.72 tons km-2 yr-1 and 78.56 tons km-2 yr-1, respectively, from low elevation Himalaya basins which are 3.3 and 9.8-fold higher than the world average. This basin transports 51.2 million tons sediment per year to the Bay of Bengal. Overall, the basin erosion rate is 201 mm.kyr-1, which is nearly six-fold higher than the world average. Pyrite oxidation counteracts CO2 drawdown from silicate weathering in this central Himalayan river system.

Maya Bhatt (Primary Presenter/Author), Texas A&M International University, maya.bhatt@tamiu.edu;

William McDowell (Co-Presenter/Co-Author), Department of Natural Resources and the Environment, University of New Hampshire, 03824, Durham, New Hampshire, bill.mcdowell@unh.edu;

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