SFS Annual Meeting

5/22/2018  |   14:00 - 14:15   |  

LAND USE, RESTORATION, AND HYDROLOGICAL CONNECTIVITY OF TEMPORARY WETLANDS AND STREAMS INFLUENCE DISSOLVED ORGANIC MATTER IN DOWNSTREAM PERENNIAL WATERS The importance of upland wetlands with temporary surface water connections to perennial waters has been debated despite the potential importance of material fluxes from wetlands. Efforts have been undertaken to restore ditched upland wetlands so they do not drain quickly but hold surface water more often. We focused on Delmarva wetlands to determine: when wetlands were connected to downstream waters and if this varied between restored, altered and natural (forested) wetlands; if DOM concentration and composition in perennial streams varied as a function of connectivity; and if there were seasonal changes in DOM microbial bioavailability. Natural wetlands contributed surface water to perennial streams more often than restored or altered wetlands and exported more aged, aromatic-rich compounds. Seasonal inputs from the natural wetlands to perennial streams were associated with increases in DOC concentrations and shifts in composition during periods when temporary channels were flowing to perennial streams. Since natural wetlands have water in the temporary channels connecting to perennial streams more days per year than restored or agricultural wetlands we suggest natural wetlands contribute more DOM that is more aromatic to downstream waters than wetlands with altered land use or cover.

Margaret Palmer (Primary Presenter/Author), University of Maryland, mpalmer@umd.edu;


Jacob Hosen (Co-Presenter/Co-Author), Purdue University, jhosen@purdue.edu;


Alec Armstrong (Co-Presenter/Co-Author), University of Maryland, aarmstrong@mica.edu;


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5/22/2018  |   14:15 - 14:30   |  

THREE-DIMENSIONAL CONNECTIVITY OF RUNOFF SOURCE AREAS DRIVE STREAM HYDRO-BIOGEOCHEMICAL SIGNALS ACROSS AN EPHEMERAL-TO-PERENNIAL DRAINAGE NETWORK The balance between longitudinal, lateral, and vertical expansion and contraction of hydrologic flowpaths and source areas across spatial scales in headwater catchments is poorly understood. To address this, we collected chemical and hydrometric data from zero through second order catchments in the Piedmont region of North Carolina, USA to characterize spatiotemporal runoff and overland, shallow soil, and deep subsurface flow across characteristic landscape elements. We also conducted 77 mapping campaigns of flow permanence across the ephemeral-to-perennial stream network. We determined that the active stream network was driven by two superimposed runoff generation regimes, event-driven and baseflow-associated, that produced distinct hydro-biogeochemical signals at the catchment outlets at two spatial scales. Frequently activated shallow subsurface flowpaths in the terrestrial landscape drove an increase in dissolved organic carbon (DOC) concentrations with increases in runoff across both catchments. DOC-runoff relationship variability was driven by a balance between runoff generation regimes and seasonal depletion of DOC from shallow flowpath activation. We suggest that the hydro-biogeochemical signals at larger watershed outlets can be driven by a balance of longitudinal, lateral, and vertical source area contributions that are mediated by climate and critical zone structure and stratigraphy.

Margaret Zimmer (Primary Presenter/Author), University of California, Santa Cruz, margaret.zimmer@ucsc.edu;


Brian McGlynn (Co-Presenter/Co-Author), Duke University, brian.mcglynn@duke.edu;


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5/22/2018  |   14:30 - 14:45   |  

DISSOLVED INORGANIC NITROGEN EXPORTS DURING FLOODS FROM AN INTERMITTENT DESERT STREAM Nitrogen export from streams is an environmental and public health concern. Temporary streams export the majority of nitrogen loads during floods, but there is high variability between events. We investigated the balance of nitrogen retention versus export during floods in an intermittent desert stream watershed. From 2010-2016, we collected floodwater samples for analysis of nitrate and ammonium from Sycamore Creek, located northeast of Phoenix, Arizona. We calculated nitrogen export by multiplying the mean floodwater concentration by total water load from each event. Export (as N) ranged from 2 to 3066 for nitrate and from 0.02 to19 kg for ammonium, and was primarily driven by the amount of discharge during the flood. Ammonium export increased significantly with a longer time interval since the previous flood. Mean nitrate and ammonium concentrations in flood water were significantly lower with higher prior season precipitation and current season cumulative precipitation prior to the event date, but were not related to time interval since prior flood. These results may indicate biological control of floodwater nitrate and ammonium concentrations, with higher precipitation increasing nutrient processing and uptake by the biological community, preventing accumulation of potentially mobile nitrogen.

Amalia Handler (Primary Presenter/Author), EPA, Handler.Amalia@epa.gov;


Nancy Grimm (Co-Presenter/Co-Author), Arizona State University, nbgrimm@asu.edu;


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5/22/2018  |   14:45 - 15:00   |  

CARBON CYCLING IN A BOREAL TEMPORARY STREAM: INSIGHT FROM AN EXPERIMENTAL HYDROLOGICAL MANIPULATION Climate and land use changes are expected to increase the occurrence of intermittency and alter flood regimes worldwide. Such changes have widespread implications for stream ecosystems, including their capacity to transform organic carbon (C). We manipulated discharge from a boreal lake to test the effects of drying and flooding on C cycling along the 1.4 km outlet stream. Flow manipulation created a longitudinal gradient in drought severity over a 18-day period, which we terminated with an experimental flood. In response, we estimated stream metabolism and quantified C gases in the stream surface and subsurface water. Drying and flooding modified the hydrological mechanisms that regulate C delivery to the stream and the residence time by which these C resources are processed under different redox conditions. Where most severe, drying induced a transition from oxic to anoxic conditions in hyporheic sediments that increased methane concentrations in the stream surface water (from 10.1 to 53.7 µg/L). Drying also interacted with groundwater inputs to create heterogeneity in metabolic rates and C gas concentrations along the experimental reach. Our results emphasize the sensitivity of stream C cycling to extreme flow events in the boreal region.

Anna Lupon (Co-Presenter/Co-Author), Swedish University of Agricultural Sciences, anna.lupon@slu.se;


Jason Leach (Co-Presenter/Co-Author), Simon Fraser University, jleach@sfu.ca ;


Nicolai Brekenfeld (Co-Presenter/Co-Author), School of Geography, Earth and Environmental Sciences, University of Birmingham, nxb634@student.bham.ac.uk ;


Stefan Krause (Co-Presenter/Co-Author), School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, U.K. , S.Krause@bham.ac.uk;


Hjalmar Laudon (Co-Presenter/Co-Author), Swedish University of Agricultural Sciences, hjalmar.laudon@slu.se;


Ryan Sponseller (Co-Presenter/Co-Author), Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden, ryan.sponseller@umu.se;


Lluís Gómez-Gener (Primary Presenter/Author), Centre for Research on Ecology and Forestry Application (CREAF), gomez.gener87@gmail.com;


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5/22/2018  |   15:00 - 15:15   |  

FLOW INTERMITTENCY AND BIODIVERSITY OF AN ALPINE FLUVIAL NETWORK: VAL ROSEG, SWITZERLAND The influence of flow intermittency (FI) on ecosystem function/biodiversity of fluvial networks will increase in the future due to climate change. The methodology for quantifying FI and its effect on river function/biodiversity is still poor. Here, we used data loggers modified from light/temperature Hobo sensors to measure FI of 30 streams comprising an Alpine stream network in Val Roseg, Switzerland. Our goals were to: i) accurately measure the presence/absence of surface water, ii) validate measured values with field surveys, iii) develop metrics to characterize flow/temperature regimes and ordinate sites along a FI gradient, and iv) relate measures of FI with stream biodiversity. Streams were equipped with flow/temperature sensors to hourly record water presence/temperature. Macroinvertebrates were sampled to determine local assemblages in each stream. Fifteen of 30 measured streams periodically dried with three groups of streams being identified: permanent streams, daily intermittent streams, and seasonally intermittent streams. Assemblage composition of streams reflected this difference in surface flow regimes in the fluvial network. Results indicate the method was robust to assess FI and showed that FI affects biodiversity and consequently ecosystem function of Alpine rive networks.

Amael Paillex (Primary Presenter/Author), ECOTEC Environment SA, 1203, Geneva, Switzerland, amael.paillex@eawag.ch;


Andre Siebers (Co-Presenter/Co-Author), Centre for Freshwater Ecosystems, La Trobe University, Wodonga, VIC, 3690, Australia, andre.siebers@eawag.ch ;


Christian Ebi (Co-Presenter/Co-Author), Swiss Federal Institute of Aquatic Science and Technology, EAWAG, Urban Water Management dpt., christian.ebi@eawag.ch ;


Jorrit Mesman (Co-Presenter/Co-Author), University of Geneva | Department F.A. Forel, Jorrit.Mesman@unige.ch;


Benjamin Misteli (Co-Presenter/Co-Author), ECOBIO, UMR 6553, CNRS, Université de Rennes 1, Rennes, France, bmisteli@student.ethz.ch;


Christopher Robinson (Co-Presenter/Co-Author), Swiss Federal Institute of Aquatic Science and Technology, EAWAG ; Aquatic Ecology dpt., Christopher.robinson@eawag.ch;


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