6/06/2017  |   14:00 - 14:15   |  306A

RATES AND DRIVERS OF NITROGEN REMOVAL BY FRESHWATER WETLANDS IN NUTRIENT ENRICHED COASTAL WATERSHEDS Excess nitrogen (N) inputs to the landscape create many environmental problems that result in harmful algal blooms and threats to aquatic species. Watersheds in the northeastern US typically remove about 80% of this anthropogenic N while in the shallow-sloped watersheds of northeastern Massachusetts, this removal can exceed 90%. Channelized streams are well studied and can have high rates of N removal. In contrast, fluvial wetlands, a prominent element of the aquatic network in many watersheds, have not been as well studied and may contribute disproportionately to N removal at the network scale. We quantified N removal in fluvial wetlands using several approaches, including coupling a dynamic solute addition method with in situ nitrate analyzer technology. N removal as a percentage of inputs ranged from 6.9-36.5% among five different fluvial wetland sites and also varied across seasons. Removal was generally greater in wetlands compared to channelized streams in the region and was in a similar range as removal measured at the patch-scale in surface transient storage areas. This suggests that fluvial wetlands may be responsible for a significant proportion of the total N removal in regions where they are abundant.

Christopher Whitney (Primary Presenter/Author), University of New Hampshire, chris.whitney@unh.edu;


Wilfred M. Wollheim ( Co-Presenter/Co-Author), University of New Hampshire, wil.wollheim@unh.edu;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   14:15 - 14:30   |  306A

META-ANALYSIS OF NUTRIENT DIFFUSING SUBSTRATE EXPERIMENTS IN RUNNING WATERS: INFLUENCE OF EXPERIMENTAL DESIGN, ENVIRONMENTAL FACTORS, AND GEOGRAPHY Algal growth is often limited by nitrogen and phosphorus availability. For over 30 years, investigators have conducted nutrient diffusing substrata (NDS) experiments to quantify algal nutrient limitation in rivers and streams. Previous meta-analyses of NDS have shown that algae are often co-limited by nitrogen and phosphorus, and that in-stream nutrients are weakly predictive of limitation. However, no meta-analysis has comprehensively addressed the experimental, environmental, and geographic covariates affecting nutrient limitation results. We reviewed the literature and extracted data for algal biomass effect sizes (n = 649 experiments). We built meta-regression models to identify important controls on NDS results and gain insights about algal nutrient limitation patterns over space and time. Experimental factors such as NDS chemical compound, chemical concentration, and experimental length significantly affected phosphorus limitation and provided insight into potential mechanisms for phosphorus inhibition. Environmental variables affecting NDS results included in-stream nutrients, light, temperature, discharge, and stream velocity. Land use, ecoregion, and season also explained trends in nutrient limitation. Based on our findings, we provide recommendations for improving experimental design and pursuing fruitful research using NDS.

Whitney Beck (Primary Presenter/Author), Environmental Protection Agency, Beck.Whitney@epa.gov;


Amanda Rugenski ( Co-Presenter/Co-Author), University of Georgia, atrugenski@gmail.com;


LeRoy Poff ( Co-Presenter/Co-Author), Colorado State University, n.poff@rams.colostate.edu;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   14:30 - 14:45   |  306A

LOCAL AND LARGE SCALE NUTRIENT DYNAMICS IN A METAL-CONTAMINATED RIVER Excessive and persistent inputs of nutrients into mid-order rivers can cause and sustain net autotrophic states over long periods of time. In the Upper Clark Fork River (UCFR), Montana, augmented autochthonous production takes the form of nuisance algal blooms and poses a threat to successful ecological restoration including removal of metal-contaminated sediments across the river’s floodplain. Despite a relative lack of evident point sources, river restoration and recovery is occurring under nutrient-rich conditions due to an average net gain of inorganic nitrogen (N) and phosphorous (P) within in the UCFR headwaters of 78.5±20.7 kg N-NO3/d and 11.6±2.3 kg P-PO4/d, respectively. Abundant P results from P-rich geologic formations in the basin, while preliminary results of dual isotope analysis of NO3 suggest nitrified soil N and animal/human waste as primary N sources with seasonal 15N-NO3 and 18O-NO3 values ranging within 5.1-19.4‰ and -6.2-2.1‰, respectively. Results for local interactions among algal standing stocks, dissolved inorganic nutrients, and organic N and P show a robust seasonality leading to sustained P:R ratios greater than one and N-limiting conditions (<0.005 ppm N-NO3) throughout base flow conditions.

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


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


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   14:45 - 15:00   |  306A

COPPER AS A SIGNATURE OF THE 2015 GOLD KING MINE RELEASE: EVIDENCE FROM BED SEDIMENTS AND BENTHIC MACROINVERTEBRATES IN THE ANIMAS RIVER The 2015 Gold King Mine release sent 3 million gallons of acidic, metal-rich water down Cement Creek and the Animas River in southern Colorado. Assessment of aquatic effects associated with the release is confounded by the fact that numerous mines in the Silverton, Colorado area have impacted receiving waters since the advent of mining in the 1870s. Proper assessment of aquatic effects requires data describing conditions before and after the release, and upstream and downstream of the release point. Herein we present water quality, sediment, and macroinvertebrate data that meet these assessment criteria. With respect to water quality, a synoptic study indicates that 40% of copper loading in the Animas River below Silverton was attributable to the Gold King Mine, prior to the release. This copper signature is evidenced by elevated copper concentrations in water samples, sediment samples, and macroinvertebrate tissues collected following the release. Despite these noted increases, the overall effect of the release appears to be minimal in light of long-term, widespread contamination within the watershed. Sediment concentrations for several metals appear to be unaffected, for example, and there were no detectable changes in macroinvertebrate diversity or abundance.

Robert L Runkel (Primary Presenter/Author), US Geological Survey, runkel@usgs.gov;


Scott Roberts ( Co-Presenter/Co-Author), Mountain Studies Institute, scott@mountainstudies.org;


Daniel J Cain ( Co-Presenter/Co-Author), US Geological Survey, djcain@usgs.gov;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   15:00 - 15:15   |  306A

THEORETICAL INCONSISTENCIES BETWEEN WHOLE-STREAM UPTAKE KINETICS INFERRED FROM SYNTHETIC CONSTANT-RATE AND INSTANTANEOUS RELEASE TRACER EXPERIMENTS Increasing numbers of field studies are using reactive tracer experiments to estimate saturating uptake kinetics for stream reaches. Yet there has been little theoretical investigation of the consistency among the various field approaches to gather the necessary breakthrough curve data for inference of whole-stream kinetic model parameters. We constructed a simple one-dimensional solute transport model of advection, longitudinal dispersion, and hyperbolic saturating kinetics, and we ran paired multi-level-constant-rate and instantaneous-release synthetic tracer experiments in hypothetical stream reaches. Conventional approaches for analyzing data from these experiments were applied to the constant-rate (multi-level release) and instantaneous (TASCC) simulated results, and comparisons demonstrated substantial differences between the kinetic parameter estimates recovered from the simulated breakthrough curves. Furthermore, kinetic parameter estimates from the synthetic instantaneous experiment were substantially different from the kinetic parameters used for the underlying stream simulation. We present numerical experiments that provide evidence of the mechanisms behind these differences and suggest that longitudinal dispersion may be a neglected control on active to conservative tracer concentration ratios in instantaneous release experiments.

Robert Payn (Primary Presenter/Author), Montana State University, Montana Institute on Ecosystems, rpayn@montana.edu;


Steven Thomas ( Co-Presenter/Co-Author), University of Alabama, sathomas16@ua.edu;


Tim Covino ( Co-Presenter/Co-Author), Colorado State University, Tim.Covino@ColoState.EDU;


Lauren Koenig ( Co-Presenter/Co-Author), University of New Hampshire, lauren.koenig@unh.edu;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   15:15 - 15:30   |  306A

POTENTIAL EFFECTS OF THE INVASIVE CLAM, CORBICULA FLUMINEA, ON METHANE CYCLE PROCESSES IN AN URBAN STREAM Lotic systems have recently been recognized as significant contributors to the global methane cycle. Organic matter decomposition in stream sediments can form localized anaerobic microsites where methanogenesis occurs. Methanogenesis and subsequent methane oxidation or efflux are subject to local biogeochemical conditions in the stream. The invasive clam, Corbicula, has been shown to affect stream biogeochemical processes and may also influence methane cycle processes. Distribution of Corbicula and anaerobic microsites within streams is highly variable and field surveys revealed no correlation between Corbicula and methane concentrations. Therefore, I used microcosm experiments to directly evaluate Corbicula’s effect on methane cycle processing rates. I manipulated Corbicula presence/absence and found that methane efflux increased in the presence of Corbicula, but there was no significant effect on methanogenesis. In an experiment manipulating Corbicula density I observed negative methane flux at low densities, indicating that oxidation was greater than methanogenesis. However, I observed positive methane flux in high density treatments. Increased respiration rates of dense Corbicula populations may promote reducing conditions in sediments, enhancing methanogenesis and lowering the potential for oxidation.

Robert Brown (Primary Presenter/Author), Tennessee Tech University, brownrs1991@gmail.com;


Anne Hershey ( Co-Presenter/Co-Author), The University of North Carolina at Greensboro, aehershe@uncg.edu;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   15:30 - 15:45   |  306A

TESTING A MULTI-SCALE STREAM REHABILITATION TOOLBOX TO REDUCE NITRATE EXPORT IN AGRICULTURAL WATERWAYS IN CANTERBURY, NEW ZEALAND A vast network of surface- and subsurface drains supports agriculture on the Canterbury Plains, South Island, New Zealand, but, those drains act as ‘leaky plumbing’ because they often transport leeched nutrients downstream, circumventing riparian protection networks. A multi-scale spatial approach within the Canterbury Waterway Rehabilitation Experiment (CAREX) was used to quantify the export of nitrate-nitrogen in nine one-kilometer long agricultural headwaters <2 m wide to identify leaky plumbing and trial stream rehabilitation tools. In-stream nitrate-N export ranged from <1 to >50 kg/day with <0.01 to >5 kg/day coming from tile drain ‘hotspots’. Edge-of-field woodchip bioreactors and in-stream woodchip additions were trialed to reduce N export. Bioreactors reduced edge-of-field nitrate-N loss by <10 to >70%; however, in-stream additions of labile carbon are needed to address the large downstream export of nitrate-N that is not removed by edge-of-field and riparian nutrient tools. Combining nutrient removal tools in a synergistic fashion highlights the suitability a toolbox-based stream rehabilitation approach which targets multiple critical source areas of N export. Practical, cost-effective stream rehabilitation tools are recommended to address stream nutrient export while catchment-scale nutrient plans are developed to address losses from land.

Brandon Goeller (Primary Presenter/Author), University of Canterbury, bcgoeller@gmail.com;


Catherine Febria ( Co-Presenter/Co-Author), University of Windsor, Catherine.Febria@uwindsor.ca;


Kristy Hogsden ( Co-Presenter/Co-Author), NIWA, kristy.hogsden@niwa .co.nz;


Hayley Devlin ( Co-Presenter/Co-Author), University of Canterbury, hayley.devlin@canterbury.ac.nz;


Helen Warburton ( Co-Presenter/Co-Author), University of Canterbury, helen.warburton@canterbury.ac.nz;


Jon Harding ( Co-Presenter/Co-Author), University Canterbury, jon.harding@canterbry.ac.nz;


Angus McIntosh ( Co-Presenter/Co-Author), University of Canterbury, angus.mcintosh@canterbury.ac.nz;


Presentation:
This presentation has not yet been uploaded.