Back to top

SFS Annual Meeting

Monday, May 20, 2019
09:00 - 10:30

<< Back to Schedule

09:00 - 09:15: / 250 AB DETECTING DIFFERENCES IN NITROGEN FLOW IN ECOSYSTEM-SCALE EXPERIMENTS: A NEW APPROACH TO MODELING ISOTOPE TRACER ADDITIONS IN STREAM ECOSYSTEMS

5/20/2019  |   09:00 - 09:15   |  250 AB

DETECTING DIFFERENCES IN NITROGEN FLOW IN ECOSYSTEM-SCALE EXPERIMENTS: A NEW APPROACH TO MODELING ISOTOPE TRACER ADDITIONS IN STREAM ECOSYSTEMS Isotope tracer additions are a powerful tool for estimating nutrient flows in stream ecosystems. To date, these studies have been descriptive in nature and have estimated trophic fluxes using simple models in a piecemeal approach. A successful analytical framework needs to be able to provide flux estimates and associated errors that account for the interdependence of parameter estimates among all compartments, the uncertainty in the diet of consumers, and the over-enrichment of compartments that feed selectively. Here, we present a new, holistic modeling approach based on Bayesian Hidden Markov Models, for the analysis of 15N-NH4+ tracer data in 2 Trinidadian streams in which light and fish populations were experimentally manipulated. This modeling approach allows estimation of uncertainty associated with all N fluxes, propagates error when estimating derived parameters, quantitatively compares alternative models of food web structure, and statistically compares parameter estimates across experimental treatments. We also compare the results of this new approach with estimates derived from historical techniques. This method enables rigorous statistical estimation of nutrient fluxes and ecosystem properties and thus provides a powerful new tool for assessing how whole-stream, experimental manipulations effect food web structure and function.

Steven Thomas (Primary Presenter/Author), School of Natural Resources, University of Nebraska-Lincoln, Lincoln, sthomas5@unl.edu;


Mattieu Bruneaux (Co-Presenter/Co-Author), matthieu.bruneaux@gmail.com, matthieu.bruneaux@gmail.com;


Sarah Collins (Co-Presenter/Co-Author), University of Wyoming, sarah.collins@uwyo.edu;


Alexander Flecker (Co-Presenter/Co-Author), Cornell University, Ithaca, NY, USA, asf3@cornell.edu;


Rana El-Sabaawi (Co-Presenter/Co-Author), University of Victoria, rana@uvic.ca;


Andres Lopez-Sepulcre (Co-Presenter/Co-Author), lopezsepulcre@gmail.com, lopezsepulcre@gmail.com;


Presentation:
This presentation has not yet been uploaded.

09:15 - 09:30: / 250 AB HOW TO THINK ABOUT HYPORHEIC EXCHANGE IN GRAVEL BEDDED RIVERS (WITH ATTENTION TO IMPLICATIONS FOR BIOGEOCHEMISTRY)

5/20/2019  |   09:15 - 09:30   |  250 AB

HOW TO THINK ABOUT HYPORHEIC EXCHANGE IN GRAVEL BEDDED RIVERS (WITH ATTENTION TO IMPLICATIONS FOR BIOGEOCHEMISTRY) Hyporheic exchange – the continuous, bi-directional exchange of water between a stream channel and underlying alluvium – is now recognized as a critical driver of stream ecosystems. When conceptualizing hyporheic exchange in expansive hyporheic zones (HZs) associated with coarse-grained river beds, researchers and managers sometimes default to an assumption of homogeneity, failing to consider the temporally dynamic and heterogeneous nature of upwelling hyporheic water with respect to temperature, dissolved constituents, and other characteristics. Further, when the HZ is conceptualized as single, homogenous transient storage zone, the diversity of water characteristics and habitats within the HZ is overlooked. A conceptual model of hyporheic exchange that incorporates the hydrologic age distribution of water stored in the HZ and the residence time distribution of water discharged from the HZ underscores the spatially diverse and temporally dynamic characteristics of upwelling hyporheic water. We present such a conceptual model, focusing on variation in ratios of water exchange rates and storage as a function of residence time and water age. Incorporating such hydrologic rigor when considering hyporheic exchange aids in the design, implementation, and interpretation of research related to hyporheic processes.

Geoffrey Poole (Primary Presenter/Author), Montana State University, Montana Institute on Ecosystems, gpoole@montana.edu ;


Scott O'Daniel (Co-Presenter/Co-Author), Umatilla Tribes, scottodaniel@ctuir.org;


Katie Fogg (Co-Presenter/Co-Author), Montana State University, s.katie.fogg@gmail.com;


Byron Amerson (Co-Presenter/Co-Author), Montana State University, byron.amerson@gmail.com;


Ann Marie Reinhold (Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, reinhold@montana.edu;


Sam Carlson (Co-Presenter/Co-Author), Montana State University, sam.p.carlson@gmail.com;


Presentation:
This presentation has not yet been uploaded.

09:30 - 09:45: / 250 AB DO US STREAM NITROGEN CONCENTRATIONS REFLECT CHANGING INPUTS OVER TIME? RESULTS FROM THE U.S. EPA NATIONAL RIVERS AND STREAMS ASSESSMENTS (2000-2014)

5/20/2019  |   09:30 - 09:45   |  250 AB

DO US STREAM NITROGEN CONCENTRATIONS REFLECT CHANGING INPUTS OVER TIME? RESULTS FROM THE U.S. EPA NATIONAL RIVERS AND STREAMS ASSESSMENTS (2000-2014) The US EPA National Rivers and Streams Assessment (NRSA) surveys allow for the examination of large-scale changes in stream nutrient concentrations over time. A recent inventory of N inputs to HUC8 watersheds over time showed that while nitrogen (N) input to the entire continental US was similar in 2002 and 2012, N inputs increased in much of the Central Plains, decreased in the eastern US and showed little change across most of the West. We examined temporal and spatial variations in total nitrogen (TN) concentrations in a spatially-balanced survey of over 3,000 wadeable streams in the NRSA between 2000 and 2014. At the national scale, TN concentrations did not change significantly over this time, consistent with the lack of a national trend in N inputs for the entire US. Streams in the Central Plains had significantly greater TN concentration than streams in the West and Appalachians, reflecting the pattern in N inputs for those areas. Surveyed stream chemistry will be combined with national nitrogen input spatial data to model the response to changes in landscape nutrient loading at regional and finer scales.

Jiajia Lin (Primary Presenter/Author), National Research Council/ US EPA, jlin42@outlook.com;


Ryan Hill (Co-Presenter/Co-Author), Oregon State University c/o US EPA, Western Ecology Division, Corvallis, OR, hill.ryan@epa.gov;


Robert Sabo (Co-Presenter/Co-Author), US EPA, Sabo.Robert@epa.gov;


Alan Herlihy (Co-Presenter/Co-Author), Oregon State University, Corvallis, OR, alan.herlihy@oregonstate.edu;


Marc Weber (Co-Presenter/Co-Author), US EPA, Western Ecology Division, Corvallis, OR, weber.marc@epa.gov;


J. Renee Brooks (Co-Presenter/Co-Author), EPA Western Ecology Division, Brooks.Reneej@epa.gov ;


Christopher Clark (Co-Presenter/Co-Author), US EPA, Clark.Christopher@epa.gov;


Scott Leibowitz (Co-Presenter/Co-Author), US EPA, Western Ecology Division, Corvallis, OR, leibowitz.scott@epa.gov;


John Stoddard (Co-Presenter/Co-Author), Office of Research and Development, Environmental Protection Agency, Stoddard.John@epa.gov;


Jana Compton (Co-Presenter/Co-Author), US EPA Office of Research and Development - Western Ecology Division, compton.jana@epa.gov;


Presentation:
This presentation has not yet been uploaded.

09:45 - 10:00: / 250 AB LOADING AND BIOACCUMULATION OF SELENIUM AND MERCURY FROM MOUNTAINTOP COAL MINING INTO STREAMS AND RIPARIAN FOOD WEBS

5/20/2019  |   09:45 - 10:00   |  250 AB

LOADING AND BIOACCUMULATION OF SELENIUM AND MERCURY FROM MOUNTAINTOP COAL MINING INTO STREAMS AND RIPARIAN FOOD WEBS While mercury (Hg) and selenium (Se) bioaccumulate and are individually toxic to organisms at high concentrations, some studies show reduced rates of Hg bioaccumulation when organisms are fed diets high in both Se and Hg. This has been interpreted to suggest that Se enrichment of diets or entire ecosystems could prevent Hg toxicity. Yet, little is understood about the biogeochemical and bioaccumulation processes that potentially lead to this putative antagonistic relationship. We examined relationships between Hg and Se in Central Appalachian streams with variable Se concentration (BDL-70 ug/L) due to mountaintop coal mining. We measured Hg and methyl-Hg concentrations in water, sediment, biofilm, aquatic invertebrates, and riparian spiders across the Se concentration gradient. We found that while Se concentrations were strongly positively correlated with mining extent, mined watersheds generally had lower Hg concentrations. We found that total Hg, methyl-Hg, and Se bioaccumulate, with highest concentrations in macroinvertebrates. We found limited evidence for an antagonistic relationship between Hg and Se at the microbial level. The interaction between these two elements is less conclusive in invertebrates; while methyl-Hg and Se are negatively correlated in cranefly larvae, there is no correlation in spiders.

Laura Naslund (Co-Presenter/Co-Author), Duke University , laura.naslund@duke.edu;


David Walters (Co-Presenter/Co-Author), US Geological Survey, waltersd@usgs.gov;


Collin Eagles-Smith (Co-Presenter/Co-Author), US Geological Survey, ceagles-smith@usgs.gov ;


Emily Bernhardt (Co-Presenter/Co-Author), Duke University, ebernhar@duke.edu;


Jacqueline Gerson (Primary Presenter/Author), Duke University, jacqueline.gerson@duke.edu;


Presentation:
This presentation has not yet been uploaded.

10:00 - 10:15: / 250 AB EVENT-SCALE RIVERINE LOADING OF NITROGEN AND PHOSPHORUS: IMPACTS OF LAND USE AND SEASONALITY ON N:P EXPORT RATIOS

5/20/2019  |   10:00 - 10:15   |  250 AB

EVENT-SCALE RIVERINE LOADING OF NITROGEN AND PHOSPHORUS: IMPACTS OF LAND USE AND SEASONALITY ON N:P EXPORT RATIOS Riverine nutrient loads, particularly during high flows, impact ecological processes in receiving waterbodies by altering nutrient concentrations and ratios. Given that nitrogen (N) to phosphorus (P) ratios influence a range of processes, and that anthropogenic activities are shifting the balance of these elements, it is important to understand N and P loading patterns across space and time. While general differences in N and P provenance and riverine loading dynamics are well-established, drivers of variability in intra- and inter-event loading patterns remains poorly understood. Yet these events tend to dominate annual nutrient loads in many climates. With the advent of in situ sensors and novel algorithms to predict N and P concentrations concurrently, opportunity exists to examine event-scale N and P loading patterns. Here we use high-frequency N and P measurements for >350 events, over 5 years, across land uses to quantify riverine N and P loading and N:P export ratios. Initial results demonstrate the importance of event contributions to annual loads for both nutrients, and variability in concentration-discharge relationships for N and P across event sizes, land uses, and seasons that drive important differences in N:P export ratios.

Dustin Kincaid (Primary Presenter/Author), University of Vermont, dustin.kincaid@uvm.edu;


Erin Seybold (Co-Presenter/Co-Author), University of Vermont, ecseybold@gmail.com;


E. Carol Adair (Co-Presenter/Co-Author), University of Vermont, carol.adair@uvm.edu;


William Breck Bowden (Co-Presenter/Co-Author), University of Vermont, breck.bowden@uvm.edu;


Julia Perdrial (Co-Presenter/Co-Author), University of Vermont, julia.perdrial@uvm.edu;


Matthew Vaughan (Co-Presenter/Co-Author), Lake Champlain Basin Program, mvaughan@lcbp.org;


Andrew Schroth (Co-Presenter/Co-Author), University of Vermont, aschroth@uvm.edu;


Presentation:
This presentation has not yet been uploaded.

10:15 - 10:30: / 250 AB RELATIONSHIPS BETWEEN TRACE METAL-NUTRIENT COLIMITATION IN STREAM BIOFILMS AND SURFACE WATER CHEMISTRY

5/20/2019  |   10:15 - 10:30   |  250 AB

RELATIONSHIPS BETWEEN TRACE METAL-NUTRIENT COLIMITATION IN STREAM BIOFILMS AND SURFACE WATER CHEMISTRY Stream biofilms use complex and diverse element sequestration and assimilation mechanisms for growth and metabolism. Trace metals are incorporated in many mechanisms as enzyme cofactors, to support electron transfer proteins for photosynthesis and respiration, or to produce enzymes that allow for use of less common organic nutrient sources. Much of what is understood about stream nutrient limitation focuses on just N and P, although trace metals support several underlying metabolic pathways that may also cause apparent nutrient limitation. We present data from streams in the Great Lakes region that span a gradient of pristine to urban and low to high inorganic and organic nutrient concentrations. We used trace metal nutrient diffusing substrates (tNDS) with different combinations of elements to identify trace metal-nutrient co-limitation of algae and measured surface water chemistry. Stream biofilms responded to multi-element additions more than single-element additions. Zinc and nickel amended treatments showed increased algal biofilm growth across 60% of streams. Colimitation was observed most frequently in streams with low dissolved inorganic nutrients; however, colimitation was also observed in urban streams. These data suggest that colimitation is common and trace metal-nutrient colimitation is complex and overlooked.

Andrea Fitzgibbon (Primary Presenter/Author), Kent State University , afitzgib@kent.edu;


David Costello (Co-Presenter/Co-Author), Kent State University, dcostel3@kent.edu;


Presentation:
This presentation has not yet been uploaded.