5/25/2016  |   10:30 - 10:45   |  309-310

PHOSPHORUS INTERNAL LOADING FROM RESERVOIR SEDIMENTS: A HISTORICAL LEGACY, OR SUSTAINED BY ONGOING INPUTS? Many eutrophic reservoirs display internal loading of phosphorus (P) during the warm season, which may continue for years after exogenous loading is reduced and is often attributed to legacy effects of past inputs. An annual P mass balance for a run-of-river reservoir in southern Michigan indicated internal P loading during the summer, although not accompanied by water-column anoxia. Total P release during summer was roughly equal to total retention over the rest of the year, and thus release could be derived from recently deposited P rather than legacy deposits. Internal loading driven by solubilization of iron-bound sediment P is evidenced by large reductions in both sediment P and iron between early and late summer. The sediment P deficit far exceeds the observed net export via internal loading, so most solubilized P must return to the sediments rather than flow out the dam. Seasonal changes in net P retention and release could therefore explain the internal loading without invoking a role for legacy P, and if so, summer internal loading and consequent eutrophication may be sustained indefinitely at current input loads.

Stephen K. Hamilton (Primary Presenter/Author), Michigan State University & Cary Institute of Ecosystem Studies, hamilton@kbs.msu.edu;


Mark Kieser ( Co-Presenter/Co-Author), Kieser & Associates LLC, mkieser@kieser-associates.com;


Patricia Hoch-Melluish ( Co-Presenter/Co-Author), Kieser & Associates LLC, phoch-melluish@kieser-associates.com;


Brian Boyer ( Co-Presenter/Co-Author), Kieser & Associates LLC, bboyer@kieser-associates.com;


Sylvia Heaton ( Co-Presenter/Co-Author), Michigan Dept. of Environmental Quality, heatons@michigan.gov;


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5/25/2016  |   10:45 - 11:00   |  309-310

A META-ANALYSIS OF P UPTAKE RATES IN LOTIC ECOSYSTEMS: INFLUENCE OF LOCAL CONDITIONS ON GLOBAL PATTERNS Previous studies have modeled the relationship between nutrient cycling rates and stream size for nitrogen (N), but this relationship has not been established for phosphorus (P). Additionally, there is a relative lack of data on P uptake in larger streams. We conducted a meta-analysis using data from experiments we conducted in 2013 along with 272 P uptake experiments reported in the literature in order to determine relationships between P uptake and various in-stream and hydrologic variables. We found that the intensity of P cycling scaled positively with river size, but the slope and intercept differ substantially from the same relationship for N, indicating that smaller streams cycle P more intensively than larger streams and the demand for P relative to N decreases with river size. Data from our 2013 study indicates that deviation of individual sites from this global relationship is explained by local conditions such as benthic algal biomass and stream water chemistry. Further research is needed to establish the relative importance of local factors in determining global-scale patterns in N and P cycling in rivers.

Aaron Swink (Primary Presenter/Author), Texas State University, aps36@txstate.edu;


Weston Nowlin ( Co-Presenter/Co-Author), Texas State University, wnowlin@txstate.edu;


Benjamin Schwartz ( Co-Presenter/Co-Author), Department of Biology, Texas State University, San Marcos, Tx., bs37@txstate.edu;


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5/25/2016  |   11:00 - 11:15   |  309-310

FACTORS AFFECTING PHOSPHORUS UPTAKE IN KARST RIVERS IN CENTRAL TEXAS Phosphorus (P) is often a limiting nutrient for microbial and primary producers in aquatic systems. Although there is abundant data on nutrient uptake rates in streams, most data is for nitrogen (N) uptake rates in relatively small systems (< 50 L/s). More recently, the use of pulsed-tracer addition methods has allowed nutrient uptake estimates to be made in larger systems. Using the pulsed-tracer addition method, we quantified P uptake in 6 relatively large (>100 L/s) karst rivers in central Texas in relation to in-stream factors that may influence P uptake rates. Across systems, chlorophyll a and P content in benthic biofilms were the strongest predictors of uptake rates. Chlorophyll-a, benthic P, water column P and dissolved calcium (Ca) were highly correlated across systems, indicating that biological and physicochemical factors both contribute to P uptake in karst rivers. P uptake rates for the rivers in our study were rapid when compared to similarly-sized non-karst rivers due to the low availability of dissolved P, the abundance of algal biofilms, and precipitation of P with Ca.

Weston Nowlin (Primary Presenter/Author), Texas State University, wnowlin@txstate.edu;


Aaron Swink ( Co-Presenter/Co-Author), Texas State University, aps36@txstate.edu;


Benjamin Schwartz ( Co-Presenter/Co-Author), Department of Biology, Texas State University, San Marcos, Tx., bs37@txstate.edu;


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5/25/2016  |   11:15 - 11:30   |  309-310

A SPATIAL ANALYSIS OF SEASONAL VARIATION IN DISSOLVED NUTRIENTS AND GREENHOUSE GASSES ALONG TWO STREAM-RIVER NETWORKS DRAINING WATERSHEDS OF CONTRASTING LAND USE Human activity and subsequent biogeochemical processing of dissolved reactive nutrients make stream networks important sources of greenhouse gasses (GHG) that contribute to the heat trapping capacity of the modern atmosphere. We replicated a seasonal synoptic sampling regime to measure dissolved nutrients and GHG at 80 stream/river sites in two watersheds of contrasting land use: the Manistee R (MI; ~83% forested) and Tippecanoe R (IN; 82% agricultural). Solute and GHG concentrations were higher in the agricultural Tippecanoe R, and varied significantly among seasons. We then modeled the spatial distribution of solutes and GHG in each basin. Nitrate-N concentrations correlated with nitrous oxide emissions, and were strongly influenced by agricultural land use during the dormant winter season. In contrast, both watersheds exhibited a diverse configuration of GHG “hotspots” during the summer growing season. Furthermore, river mainstems appeared to act as land use “buffers,” whereas tributary signatures were tightly coupled with surrounding land use. Our high-resolution data demonstrates marked heterogeneity in spatio-temporal patterns in river networks; identifying controls will be critical for predicting the future impact of land use in a changing climate.

Martha M. Dee (Primary Presenter/Author), University of Notre Dame, mdee@nd.edu;


Jennifer L. Tank ( Co-Presenter/Co-Author), University of Notre Dame, tank.1@nd.edu;


Alessandra Marzadri ( Co-Presenter/Co-Author), Center for Ecohydraulics Research, University of Idaho , marzadri@ing.unitn.it;


Daniele Tonina ( Co-Presenter/Co-Author), Center for Ecohydraulics Research, University of Idaho, dtonina@uidaho.edu ;


Alberto Bellin ( Co-Presenter/Co-Author), University of Trento, Trento, Italy, Alberto.Bellin@unitn.it ;


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5/25/2016  |   11:30 - 11:45   |  309-310

THE NATIONAL ECOLOGICAL OBSERVATORY NETWORK’S EVOLVING AQUATIC DATA PIPELINES AND DATA AVAILABILITY The National Ecological Observatory Network (NEON) is a 30-year, national-scale research platform for examining ecological change, using consistent procedures to standardize instrument and observational measurements at 47 terrestrial and 34 aquatic sites, including airborne remote sensing. NEON’s data pipeline development is underway and data are being made available. NEON data pipelines include data ingest using in-field mobile data recorders and web User Interfaces for data uploads from distributed field offices, as well as from external analytical laboratories. Quality assurance is implemented at various stages for all of the above ingest pathways, including constraining data before submission (i.e., correct type of data, within the plausible range) and flagging data after submission (i.e., samples exceeding storage conditions). A subset of data is currently available for NEON Aquatic sites ranging from continuously-streaming water quality sensor data, to chemical and biological field and laboratory point samples, to airborne remote sensing of watersheds. Opportunities to connect instrument and observational data, as well as remotely sensed data, are increasing across the Observatory and will culminate in a full suite of NEON data products by 2017.

Keli Goodman (Primary Presenter/Author), National Ecological Observatory Network (NEON) operated by Battelle, kgoodman@battelleecology.org;


Stephanie Parker ( Co-Presenter/Co-Author), Battelle, National Ecological Observatory Network (NEON), sparker@battelleecology.org;
NEON Aquatic Ecologist and Research Scientist

Caren Scott ( Co-Presenter/Co-Author), NEON, cscott@neoninc.org;


Jesse Vance ( Co-Presenter/Co-Author), National Ecological Observatory Network, jvance@battelleecology.org;


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5/25/2016  |   11:45 - 12:00   |  309-310

A CONSTRAINT-BASED, COMPOUND SPECIFIC APPROACH TO MODELING LINKED BIOGEOCHEMICAL CYCLES We developed a “generic algorithm for nutrient, growth, stoichiometric, and thermodynamic analysis” (GANGSTA) that automates the creation of user defined, constraint-based, compound specific biogeochemical models. Such models are founded in thermodynamic theory and simulate microbial metabolism, growth, and linked elemental cycling in user-specified in silico biogeochemical systems subject to stoichiometric constraints. We present a series of GANGSTA-derived models that simulate linked C, H, O, N, and S cycling and reproduce realistic patterns of aerobic heterotrophy, denitrification, nitrification, methane oxidation, sulfate reduction, hydrogen sulfide oxidation, and methanogenesis. Our models illustrate the advantages of representing compound limitation rather than elemental limitation when simulating linked elemental cycles. Further, and perhaps counterintuitively, our models reveal that tracking O and H cycling through specific compounds provides a more complete representation of C, H, O, N, and S biogeochemistry than tracking any other pair of elements through those same compounds.

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


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


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


Clemente Izurieta ( Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, clemente.izurieta@cs.montana.edu;


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


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


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