Back to top

SFS Annual Meeting

Monday, May 21, 2018
09:00 - 10:30

<< Back to Schedule

09:00 - 09:15: / 330 B HYDROLOGIC AND VEGETATION MANAGEMENT INFLUENCE OXYGEN DYNAMICS AND NITROGEN PROCESSING IN SHALLOW, LOW GRADIENT, EXPERIMENTAL STREAMS

5/21/2018  |   09:00 - 09:15   |  330 B

HYDROLOGIC AND VEGETATION MANAGEMENT INFLUENCE OXYGEN DYNAMICS AND NITROGEN PROCESSING IN SHALLOW, LOW GRADIENT, EXPERIMENTAL STREAMS Excess nitrogen (N) runoff from agricultural areas remains a major challenge to reducing the environmental footprint of high intensity agriculture; producers require simple and innovative approaches to reduce runoff while maintaining high productivity. Agricultural ditches and stream management can potentially increase both on-farm and landscape-scale mitigation of excess N runoff. To date, studies evaluating management practices in Lower Mississippi River Basin ditches have relied on small scale mesocosms and core based methods. Yet it is unclear how these studies inform larger scale observations that incorporate diel patterns in light and temperature which can influence primary production, oxygen (O2) dynamics, and related N processing. To examine larger spatial and temporal scales, we explored how hydrologic and vegetation management practices interact to influence diel N and O2 dynamics by manipulating hydrologic residence time and the presence of rice cutgrass (Leersia oryzoides) in six experimental streams. We measured plant nutrient uptake, denitrification fluxes, and metabolism using in situ dissolved solute and gas sampling techniques over three 24 hour diel experimental runs. Results indicate that ditches with vegetation promote N retention and have more pronounced O2 dynamics which can alter expected N removal pathways.

Rachel Nifong (Primary Presenter/Author), Agricultural Research Service, USDA, rachel.nifong@ars.usda.gov;


Jason M. Taylor (Co-Presenter/Co-Author), USDA, Agricultural Research Service, National Sedimentation Lab, jason.taylor@ars.usda.gov;


Lindsey Yasarer (Co-Presenter/Co-Author), Agricultural Research Service, US Department of Agriculture, lindsey.yasarer@ars.usda.gov;


Presentation:
This presentation has not yet been uploaded.

09:15 - 09:30: / 330 B RIVER NETWORK-SCALE PATTERNS OF GROUNDWATER DISCHARGE AND DENITRIFICATION OF LEGACY NITROGEN AT THE STREAMBED INTERFACE

5/21/2018  |   09:15 - 09:30   |  330 B

RIVER NETWORK-SCALE PATTERNS OF GROUNDWATER DISCHARGE AND DENITRIFICATION OF LEGACY NITROGEN AT THE STREAMBED INTERFACE More than half of surface water in the United States is derived from groundwater, and widespread contamination in aquifers from decades of watershed nitrogen inputs suggest legacy nitrogen discharging from groundwater may contribute to contemporary nitrogen pollution in surface waters. Legacy nitrogen loads to surface waters are controlled by both regional scale flow paths and fine-scale processes that drive nitrogen transformations, such as groundwater-surface water exchange across steep redox gradients at streambed interfaces. Integrating these disparate scales is a challenge for predicting spatial patterns of legacy nitrogen discharge and the role of the streambed interface in attenuating legacy nitrogen. We developed a regional groundwater model for the Farmington River watershed, Connecticut. To evaluate and refine the model, we used thermal infrared imagery along 36km of stream length paired with vertical temperature profiling (n=25) to measure spatial patterns of groundwater discharge. We also quantified nitrogen loading and denitrification (n=54) at the streambed interface in zones of groundwater discharge. Integrating regional and local estimates of groundwater discharge of legacy N to river networks should improve our ability to predict spatiotemporal patterns of legacy N loading to and transformation within surface waters.

Ashley Helton (Primary Presenter/Author), University of Connecticut, ashley.helton@uconn.edu;


Janet Barclay (Co-Presenter/Co-Author), University of Connecticut, janet.barclay@uconn.edu;


Martin Briggs (Co-Presenter/Co-Author), U. S. Geological Survey, Hydrogeophysics Branch, Storrs, Connecticut, USA, mbriggs@usgs.gov;


J. Jeffrey Starn (Co-Presenter/Co-Author), USGS National Water-Quality Assessment , jjstarn@usgs.gov;


Ann Hunt (Co-Presenter/Co-Author), University of Minnesota, huntx218@d.umn.edu;


Presentation:
This presentation has not yet been uploaded.

09:30 - 09:45: / 330 B NITROGEN LOADING IN AN OLIGOTROPHIC RESERVOIR: INFLUENCE ON FOOD WEB DYNAMICS

5/21/2018  |   09:30 - 09:45   |  330 B

NITROGEN LOADING IN AN OLIGOTROPHIC RESERVOIR: INFLUENCE ON FOOD WEB DYNAMICS Land-use alterations and other anthropogenic sources increase nutrient availability globally. Lake Koocanusa, an oligotrophic reservoir, exemplifies these changes and provides an opportunity to examine the response of organisms through time. We use 35+ years of monthly monitoring data to examine relationships among reservoir operations, water quality, phytoplankton, zooplankton, and fisheries. Increased mining activity in the upper Kootenai River watershed has contributed to increased nitrate loading into Lake Koocanusa. Nitrogen concentrations have more than doubled since 2000 while the remainder of water quality parameters have been relatively consistent; for example, mean TP from 2000-2016 was 6.2 ± 0.4 ppb (mean ± SE). Thus, N:P ratios have increased to be in excess of 100:1. Although lower trophic levels may be somewhat resilient to these changes, characteristics of the fisheries have changed. Kokanee length growth has declined by 0.6 mm yr-1 from 38 mm yr-1 in 1987 to 20 mm yr-1in 2016. Similarly, weight growth has declined by 2.2 g yr-1 from 113 g yr-1 in 1987 to 48 g yr-1in 2016. Increased N loading in oligotrophic reservoirs may influence food web dynamics.

Lisa Kunza (Primary Presenter/Author), South Dakota School of Mines and Technology, lisa.kunza@sdsmt.edu;


Kurt Chowanski (Co-Presenter/Co-Author), South Dakota School of Mines and Technology, kurt.chowanski@sdsmt.edu;


James Dunnigan (Co-Presenter/Co-Author), Montana Fish Wildlife and Parks, jdunnigan@mt.gov;


Kent Easthouse (Co-Presenter/Co-Author), US Army Corps of Engineers, Kent.B.Easthouse@usace.army.mil;


Gregory Hoffman (Co-Presenter/Co-Author), US Army Corps of Engineers, Gregory.C.Hoffman@usace.army.mil;


Presentation:
This presentation has not yet been uploaded.

09:45 - 10:00: / 330 B FLOW REGIME INFLUENCES ON CARBON DIOXIDE AND METHANE FLUXES AND SOURCES IN FORESTED OZARK STREAMS

5/21/2018  |   09:45 - 10:00   |  330 B

FLOW REGIME INFLUENCES ON CARBON DIOXIDE AND METHANE FLUXES AND SOURCES IN FORESTED OZARK STREAMS A growing body of work has provided estimates of stream contributions to carbon dioxide (CO2) and methane (CH4) dynamics across the United States. However, few studies have addressed the impact of flow regime on CO2 and CH4 fluxes. We determined summer daily CO2 and CH4 flux rates, carbon gas sources, and instream factors related to carbon gas flux rates in six forested streams within the two dominant natural flow regimes in northern Arkansas, runoff flashy and groundwater flashy systems. Flow types differed primarily in water source, intermittency, and ecoregion. We found that daily CO2 and CH4 fluxes did not differ significantly between flow regimes (CO2: p= 0.19, CH4: p= 0.27) , though both fluxes tended to be greater and more variable across streams at groundwater sites. Riparian soil respiration was the primary source of instream CO2 across all streams (dCO2= -17.6 to -22.0). CH4 in runoff streams streams originated from natural gas (dCH4= -38.8 to -43.7), while both thermogenic and biogenic CH4 were found in groundwater streams (dCH4= -32.5 to -50.0). Our work suggests that flow regime is likely an important player in stream carbon sources and fluxes.

Allyn Dodd (Primary Presenter/Author), University of Arkansas, akdodd@email.uark.edu;


Erik Pollock (Co-Presenter/Co-Author), University of Arkansas, epolloc@uark.edu;


Daniel Magoulick (Co-Presenter/Co-Author), University of Arkansas, danmag@uark.edu;


Michelle Evans-White (Co-Presenter/Co-Author), University of Arkansas, mevanswh@uark.edu;


Presentation:
This presentation has not yet been uploaded.

10:00 - 10:15: / 330 B ARE BIOGEOCHEMICAL RESPONSES LINKED TO THE MICROBIAL COMPOSITION OF A DEFINED NUTRIENT AND MICROBIAL INPUT TO A LARGER RIVER?

5/21/2018  |   10:00 - 10:15   |  330 B

ARE BIOGEOCHEMICAL RESPONSES LINKED TO THE MICROBIAL COMPOSITION OF A DEFINED NUTRIENT AND MICROBIAL INPUT TO A LARGER RIVER? Rivers play a critical role in transporting nutrients to coastal waters; thus, understanding river N transport and transformation is of fundamental importance. Nitrate concentration, land use, hydrology, and seasons all affect rates of denitrification (nitrate to di-nitrogen gas) and nitrification (ammonium to nitrate). The linkages between riverine microbial community composition (MCC) and N cycling rates, however, are often unclear. Large ecosystem-scale additions of both N and a novel N-enriched microbial community may assist in understanding the role of MCC in altering N cycling rates. We ask: Does N processing respond solely to changes in N substrate supply, or does changing the MCC also affect ecosystem-scale biogeochemistry? We use a release of remarkably high-N water (from a decommissioned fertilizer plant) and its resident microbial enrichment culture into the Kansas River to address our question. We measured rates of denitrification potentials (DEAs), nitrification rates and MCC upstream of the release site, and across a 32-km downstream reach. Quantifying whether the Kansas River transports novel microbial communities and how riverine N cycling changes in response to the additions will aid us in understanding the connection between MCC and biogeochemical cycling in aquatic ecosystems.

Amy J. Burgin (Primary Presenter/Author), University of Kansas, burginam@ku.edu;


Lydia Zeglin (Co-Presenter/Co-Author), Kansas State University, lzeglin@ksu.edu;


Michelle Kelly (Co-Presenter/Co-Author), University of Kansas, michellekelly@ku.edu;


Cay Thompson (Co-Presenter/Co-Author), Haskell Indian Nations University, caynoel16@gmail.com;


Janaye Hanschu (Co-Presenter/Co-Author), Kansas State University, jhanschu@ksu.edu;


Priscilla Moley (Co-Presenter/Co-Author), Kansas State University, pmoley@ksu.edu;


Presentation:
This presentation has not yet been uploaded.

10:15 - 10:30: / 330 B CAN A SMALL BLUE-GREEN ENDOSYMBION FIX ENOUGH NITROGEN TO SUPPORT A FOUR LEVEL FOOD CHAIN?

5/21/2018  |   10:15 - 10:30   |  330 B

CAN A SMALL BLUE-GREEN ENDOSYMBION FIX ENOUGH NITROGEN TO SUPPORT A FOUR LEVEL FOOD CHAIN? Inverse trophic pyramids are common in streams and lakes, where large densities of insects and fish are supported by low algal biomass. Upside-down pyramids are often attributed to algal traits that increase trophic efficiency (i.e., high turnover rates, minimal defenses, high caloric value). Our research expands this field beyond energy and carbon to test how nitrogen fixation affects food chain length and trophic pyramids. In the Eel River (CA), the food base comprises Cladophora glomerata and its abundant epiphytic diatoms. Diatoms in the family Rhopalodiaceae, which contain a cyanobacteria endosymbiont, often dominate the epiphyte assemblage. Here we combine small-scale measurements using 15N and Nanoscale Secondary Ion Mass Spectroscopy (nano-SIMS) with watershed scale surveys to address the following: 1) What are the rates of nitrogen fixation in the Cladophora epiphyte matrix? 2) How does N fixed by the endosymbiont move throughout the matrix to non N-fixing algae and bacteria? 3) How important is nitrogen fixation to higher trophic levels? Results indicate very high nitrogen fixation rates, demonstrating that under some conditions N fixed by the endosymbiont is an important source of nitrogen for higher trophic levels.

Jane Marks (Primary Presenter/Author), Northern Arizona University, jane.marks@nau.edu;


Mary Power (Co-Presenter/Co-Author), University of California, Berkeley, mepower@berkeley.edu;
Dr. Mary E. Power is Professor in the Department of Integrative Biology at the University of California, Berkeley. She was awarded an honorary doctorate by Umea University, the Kempe Medal for distinguished ecologists, and the Hutchinson Award from the American Society of Limnologists and Oceanographers. She is a member of the California Academy of Science, the American Academy of Arts and Sciences, and National Academy of Sciences, USA. She has served on the Editorial Board of PNAS (2014 to present) and Science (2006-2009). Mary also served as President of the American Society of Naturalists, and of the Ecological Society of America. Since 1988, she has been the Faculty Director of the Angelo Coast Range Reserve, (one of the UC Natural Reserve System sites, a 3500 ha reserve protected for university teaching and research). She has studied food webs in temperate and tropical rivers, as well as linkages of rivers, watersheds and near-shore environments. Focal organisms include cyanobacteria, algae, invertebrates, fish, estuarine crustaceans and terrestrial grasshoppers, spiders, lizards, birds and bats. By studying how key ecological interactions depend on landscape and temporal contexts, her group hopes to learn how river-structured ecosystems will respond to changes over space and time in climate, land use, and biota. Her group also collaborates closely with Earth and atmospheric scientists in site-based research to investigate linkages among riverine, upland, and near-shore ocean ecosystems.

Jennifer Pett-Ridge (Co-Presenter/Co-Author), Lawrence Livermore National Lab, pettridge2@llnl.gov;


Xavier Mayali (Co-Presenter/Co-Author), Lawrence Livermore National Lab, Mayali1@llnl.gov;


Peter Weber (Co-Presenter/Co-Author), Lawrence Livermore National Lab, weber21@llnl.gov;


Bruce Hungate (Co-Presenter/Co-Author), Northern Arizona University, bruce.hungate@nau.edu;


Presentation:
This presentation has not yet been uploaded.