SFS Annual Meeting

5/21/2019  |   09:00 - 09:15   |  250 AB

PATTERNS OF METABOLISM IN MATCHED TEMPERATE STEPPE ECOREGIONS OF THE US AND MONGOLIA River metabolism data are increasingly available with improved technology, broadening our understanding of rates of metabolism as central indicators of ecosystem function. Changing patterns of human influence and land use vary by biome and interfere with predictions based on changing climate. Mongolia is warming twice as quickly as the US, and the rivers of temperate steppe biome are poorly studied. We discuss whether the riverine metabolic character of these sites is better explained by expectations of biome or ecoregion, or by hydrogeomorphic character driven by land use. We introduce metabolism estimates for 80 sites in the context of hydrogeomorphic and riparian data, using mixed models and path analysis to identify drivers. Principal components regarding hydrogeomorphology explained more than 70% of variation and sites clustered into four groups unrelated to their functional process zone (FPZ) as characterized from remote sensed images. Gross production, ecosystem respiration, and net production varied with continent and upland/lowland wide/constrained designation, but less clearly by ecoregion and individual FPZ. Despite low population density in Mongolia, impacts of grazing cause rivers to exhibit characteristics of more urbanized US streams, indicating how human impacts erode expectations for river systems.

Anne Schechner (Primary Presenter/Author), Kansas State University, anneschechner@ksu.edu;


Flavia Tromboni (Co-Presenter/Co-Author), University of Nevada, Reno, ftromboni@unr.edu;


Walter Dodds (Co-Presenter/Co-Author), Kansas State University, wkdodds@ksu.edu;


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5/21/2019  |   09:15 - 09:30   |  250 AB

DOES LAND CONSERVATION IMPROVE STREAM ECOSYSTEM HEALTH? Extensive land cover change in human-dominated landscapes has impaired stream ecosystems throughout the Midwest U.S. Land conservation and restoration activities have sought to improve stream ecosystem health, yet little research has investigated the efficacy of these projects. In our study, we investigated streams in or adjacent to Chichaqua Bottoms Greenbelt, a 9,000-acre property that includes restored prairie, wetlands, and forests in Central Iowa. We quantified a suite of structural and functional metrics at six streams with varying proportions of conservation in their watersheds. Three streams were small headwaters with natural channel geomorphology, low discharge (3–30 L/s), and low mean residence time (0.34–0.61 hours), whereas the other three streams were channelized ditches with higher discharge (40–200 L/s) and longer residence times (1.5–3.6 hours). Despite contrasting geomorphology and hydrology, the streams with more natural land cover in their proximal watersheds frequently had lower rates of whole-stream metabolism relative to the streams in more highly impacted watersheds. A thorough understanding of the predictors of stream ecosystem health can provide a strong tool for the management and restoration of watersheds and streams in highly developed landscapes.

Peter S. Levi (Primary Presenter/Author), Drake University, peter.levi@drake.edu;


Katlyn Schulz (Co-Presenter/Co-Author), Drake University, katlyn.schulz@drake.edu;


Grace Mikelsons (Co-Presenter/Co-Author), Drake University, grace.mikelsons@drake.edu;


Bret Lang (Co-Presenter/Co-Author), Drake University, bret.lang@drake.edu;


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5/21/2019  |   09:30 - 09:45   |  250 AB

NITROGEN AND CARBON DYNAMICS ALONG A WETLAND-STREAM SEQUENCE Studies of the stream continuum are often segregated from influential ponds, lakes, and wetland zones that function as discrete nutrient processing domains among linked aquatic ecosystems. We used a mass-balance approach along a 23-km wetland-stream sequence to determine potential controls on biogeochemical cycling in a tributary of the Upper Clark Fork River (UCFR), MT. Results identified discrete zones of nutrient production, transformation, and uptake along the sequence. Zones of production resulted in five- to seven-fold increases in nitrate loads. Nutrient dynamics were driven primarily by net groundwater exchange, which explained up to 30% (P = 0.0064) of the change in nitrate load. Processing of ammonium-rich groundwater inputs resulted in a mean nitrification rate of 250 mg m-2 day-1; on par with surface-flow constructed treatment wetlands. Abnormally high respiration rates (up to 172.27 g O2 m-2 day-1) calculated from changes in dissolved organic carbon load between ground- and surfacewater compartments suggest alternative removal pathways – i.e., adsorption to the carbonate precipitates which coat benthic and hyporheic substrates. During summer months, this sequence of aquatic systems nearly doubled the nitrate load of the UCFR while contributing only a 10% increase in discharge.

Patrick Hurley (Primary Presenter/Author), University of Montana, patrick1.hurley@umontana.edu;


H. Maurice Valett (Co-Presenter/Co-Author), University of Montana, Division of Biological Sciences, maury.valett@umontana.edu;


Marc Peipoch (Co-Presenter/Co-Author), Stroud Water Research Center, mpeipoch@stroudcenter.org;


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5/21/2019  |   09:45 - 10:00   |  250 AB

HIGH-FREQUENCY DATA REVEALS SPATIOTEMPORAL VARIABILITY IN CARBON AND NITRGEN CONCENTRATION-DISCHARGE RELATIONSHIPS ACROSS A STREAM NETWORK Concentration-discharge (c-Q) relationships provide fundamental insight into the mobilization and export of solutes from watersheds. The development of optical sensors have now enabled researchers to measure dissolved nutrients at a time scale that captures the variability in stream discharge. We analyzed both weekly grab-sample and high-frequency time series of stream solute-discharge relationships for ten streams to characterize the spatiotemporal variation in c-Q relationships. We used windowed regression analysis to produce c-Q slopes across 30-day time intervals for 3-5 years of data. Within- and among streams, the c-Q slopes for nitrate, ammonia, dissolved organic nitrogen, total dissolved nitrogen, and fluorescent dissolved organic matter differed, suggesting varied biogeochemical controls over transport. Redundancy analysis revealed that 58% of the variation in c-Q slope was explained by watershed characteristics. c-Q slopes calculated at an annual timeframe misclassified streams 36% of the time missing seasonal and event induced shifts in c-Q dynamics. This suggests that sample frequency can impact how hydrologic systems are characterized and that intra-annual assessment of c-Q dynamics using high frequency data provides information on the processes controlling solute transport in complex environments.

Hannah Fazekas (Primary Presenter/Author), University of New Hampshire, hannah.fazekas@unh.edu;


Adam Wymore (Co-Presenter/Co-Author), University of New Hampshire, adam.wymore@unh.edu;
Dr. Adam Wymore is a Research Assistant Professor at University of New Hampshire.

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


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5/21/2019  |   10:15 - 10:30   |  250 AB

CAN BEAVERS MITIGATE NON-POINT SOURCE POLLUTION? Non-point source (NPS) pollution remains high in many watersheds despite strategies aimed at reducing nutrient pollution. One solution for mitigating NPS pollution in mountain streams is via beaver (Castor canadensis) dams. Beaver activity converts lotic systems to semi-lentic, altering the fate of nutrients in streams by impounding stream flow and trapping sediments, which have a high affinity for nutrients and most pollutants. We measured phosphorous (total and orthophosphate), nitrogen (total, dissolved, particulate) and heavy metals (EPA regulated toxins) from the water column and sediments within three beaver ponds and adjacent upstream and downstream free-flowing reaches in three headwater streams. We sampled distinct geomorphic units to account for meso-habitat variability. Water column results suggest pond margin and backwater meso-habitats display higher nutrient concentrations than free-flowing reaches. Results from sediment cores indicate pond sediments may contain 2-4 times more heavy metals compared to free-flowing reaches. Nutrient budgets constructed from both water column and sediment data suggest beaver ponds may be both NPS sources and sinks, depending on pond age and dam maintenance. Overall, beaver ponds influence stream water quality through sediment-water interactions and burial, however their impact may vary spatially and interannually.

Bethany Neilson (Co-Presenter/Co-Author), Utah State University, bethany.neilson@usu.edu;


Janice Brahney (Co-Presenter/Co-Author), Utah State University, jbrahney@gmail.com;


Deni Murray (Primary Presenter/Author), Utah State University, Department of Watershed Sciences and the Ecology Center, deni_murray@yahoo.com;


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