6/07/2017  |   09:00 - 09:15   |  302A

DENITRIFICATION HOTSPOTS IN ACCIDENTAL URBAN WETLANDS IN PHOENIX, ARIZONA In wetlands, denitrification is an ecosystem process that permanently removes reactive nitrogen from systems. Much research on denitrification has occurred in non-urban or highly managed urban wetlands. However, in urban landscapes nitrogen-rich water is often discharged into areas not designed or managed to reduce nitrogen loads. “Accidental” wetlands resulting from these discharges have the capacity to remove nitrate, but little known about what drives where hotspots of denitrification occur in these systems. We measured potential denitrification on soils from nine accidental wetlands forming at storm drain outfalls in Phoenix, AZ. Denitrification hotspots were defined as data within the fourth quartile of the data distribution. Soil moisture was the best predictor of hotspots in the study wetlands. Further, denitrification hotspots were more likely to occur under patches of Ludwigia peploides and at wetlands that remained inundated for a greater proportion of the year. There was no seasonal variability in when hotspots were more likely to occur. These results suggest that promoting particular hydrologic regimes and vegetation growth could increase the capacity of accidental wetlands to remove excess nitrate via denitrification.

Amanda Suchy (Primary Presenter/Author), City University of New York, suchya@caryinstitute.org;


Monica Palta ( Co-Presenter/Co-Author), Pace University, mpalta@asu.edu;


Daniel Childers ( Co-Presenter/Co-Author), Arizona State University, dan.childers@asu.edu;


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6/07/2017  |   09:15 - 09:30   |  302A

TURN YOUR TV TO 10: URBAN ASSESSMENT OF TAXA SENSITIVITY INDICATES INCREASED TOLERANCE Benthic macroinvertebrate sensitivity or tolerance values (TVs) are regularly used by research scientists and regulatory agencies as indicators of aquatic stress or ecosystem recovery. Tolerance values are useful as surrogates for water quality if they are incrementally correlated with the level of stressor(s) and/or have a threshold response (extirpation) when the level of stress reaches some quantifiable level. However, few TVs are developed within urban systems similar to Fairfax County, Virginia. Data from Fairfax County’s biological monitoring program (2004-2016) were used to develop cumulative distribution functions (CDFs) and generalized additive models (GAMs) for over 90 benthic macroinvertebrate taxa (mostly genera) in response to various aquatic stressors such as impervious area, specific conductivity and habitat. Results indicate the TVs for many common benthic taxa should be revised, particularly when working in urban systems. Further, variation among the benthic community structure and function indicate that local landscapes (Level IV Ecoregions) have additional influences on taxa sensitivity. Both are important considerations when setting achievable goals for regulatory implementation and stream restoration projects.

Chris Ruck (Primary Presenter/Author), Fairfax County (VA), Watershed Assessment Branch, christopher.ruck@fairfaxcounty.gov;


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6/07/2017  |   09:30 - 09:45   |  302A

HYDROGEOMORPHIC ALTERATIONS IMPACT FISH ASSEMBLAGE STRUCTURE AND FUNCTION IN URBAN STREAMS Urban development results in widespread geomorphic and hydrologic alterations of streams. Despite a developing literature regarding urban stream hydrogeomorphology, few studies have addressed the timing and spatial scale of urban-induced stream geomorphic adjustment on fish assemblages. Here, we investigated the relationships between annual changes in fluvial geomorphology and fish assemblages in 12 small streams in the Columbus Metropolitan Area (CMA), Ohio (USA) over 3-5 years. Multiple measures of stream geomorphology changed over time including slope (9% decrease on average), discharge rate (39% decrease), and shear stress (29% decrease), some in concert with one another (e.g., slope and shear stress). Repeated-measures ANOVA showed that a number of fish assemblage metrics were related to hydrogeomorphic variables, but the nature of these relationships often changed over time (e.g., linear to non-linear). Among the strongest relationships observed were associations between substrate size (D50) and species richness, slope and evenness, and width of flood-prone area and shear stress and H’ and % specialists (e.g., invertivores)). These results contribute to mechanisms regulating changes in resident fish communities in urbanizing catchments.

Leslie O. Rieck (Primary Presenter/Author), The Ohio State University, rieck.6@osu.edu;


S. Mažeika Patricio Sulliván ( Co-Presenter/Co-Author), The Ohio State University, sullivan.191@osu.edu;


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6/07/2017  |   09:45 - 10:00   |  302A

BENTHIC MACROINVERTEBRATE COMMUNITY RECOVERY IN STREAMS RESTORED FOLLOWING LONGWALL MINING SUBSIDENCE Stream restoration has been increasingly criticized because of a lack of clear performance objectives and a perceived failure to show measurable improvements in ecological function. Here, we present data from a large replicated study of stream restorations following longwall coal mining that included specific biological performance standards and demonstrated significant improvements in these and additional biological parameters. Longwall coal mining is a full-extraction method that can cause subsidence pooling in streams, decreasing habitat diversity and potentially impacting water quality from sedimentation. Channel restoration was used to return the natural grade to the stream, improve in-stream habitat, and ultimately restore aquatic life uses. Biological monitoring was performed at 18 stream reaches in southwestern Pennsylvania where subsidence pooling and subsequent restoration had occurred. The benthic macroinvertebrate community was monitored using a standard multi-habitat IBI protocol before and after pooling and following restoration to determine compliance with state-specified biological performance standards. Benthic macroinvertebrate IBI scores and taxa richness declined following subsidence, but improved following restoration at a rate of 6.9 + 1.9 IBI points per year and 2.3 + 0.7 taxa per year.

Marisa Logan (Primary Presenter/Author), Civil & Environmental Consultants, Inc., mlogan@cecinc.com;


Tim Nuttle ( Co-Presenter/Co-Author), Civil & Environmental Consultants, Inc., tnuttle@cecinc.com;


David Parise ( Co-Presenter/Co-Author), Civil & Environmental Consultants, Inc., dparise@cecinc.com;


David Foltz II ( Co-Presenter/Co-Author), Civil & Environmental Consultants, Inc. / West Liberty University, dfoltz@westliberty.edu;


Joshua Silvis ( Co-Presenter/Co-Author), CONSOL Energy, Inc., JoshuaSilvis@consolenergy.com;


Mark Haibach ( Co-Presenter/Co-Author), Civil & Environmental Consultants, Inc., mhaibach@cecinc.com;


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6/07/2017  |   10:00 - 10:15   |  302A

NOVEL TECHNIQUES FOR SUBMERGED AQUATIC VEGETATION RESTORATION IN FLORIDA SPRING SYSTEMS Florida spring systems are experiencing substantial ecological changes that tend to favor a plant community shift from submerged aquatic vegetation (SAV) to filamentous algae dominance. A pilot restoration project was initiated to assess causes of plant community shifts and to test several novel techniques for re-establishment of SAV in Florida springs. Three 1000 m² restoration plots were established within the Crystal River/Kings Bay system in the fall of 2015. Custom-designed herbivory exclusion fences were installed around each plot to evaluate the effect of herbivory by Florida manatee (Trichechus manatus latirostris). Multiple SAV planting techniques were tested, including experimental eelgrass (Vallisneria americana) “sod” mats that were cultivated offsite and transplanted into the plots. Eelgrass abundance increased and displaced filamentous algae over the first growing season; however the invasive SAV species hydrilla (Hydrilla verticillata) also colonized the plots and outcompeted eelgrass in some areas. Towards the end of the growing season, a surge of high salinity water from a tropical storm caused significant loss of SAV and recovery has been variable. In 2018, exclusion fences will be removed to determine if the established SAV community can persist with the return of herbivory.

Sean King (Primary Presenter/Author), Southwest Florida Water Management District, sean.king@swfwmd.state.fl.us;


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6/07/2017  |   10:15 - 10:30   |  302A

COMPARING DENITRIFICATION RATES BETWEEN RESTORED AND NATURALIZED FLOODPLAINS IN AGRICULTURAL DITCHES Enhancing nitrogen (N) removal in agricultural streams and ditches of the Midwestern US is one potential mechanism to reduce N export to sensitive downstream ecosystems. The restoration of inset floodplains via implementation of the two-stage ditch can enhance denitrification compared to channelized systems, however, little is known about how denitrification on restored floodplains compares to those formed naturally when stream channel management lapses. We used sacrificial microcosm incubations and membrane-inlet mass spectrometry (MIMS) to compare denitrification rates in floodplain soils collected along transects in both naturalized and restored floodplains; longitudinal transects sampled two zones in the active floodplain (near-stream, NS vs. middle, MID) while the third reflected upland conditions in the riparian buffer strip (UP). Denitrification rates ranged from 500-730 ugN/m/hr and 800-2,200 ugN/m/hr in the naturalized and restored inset floodplains, respectively. Denitrification in the MID transects were >70% higher in the restored floodplain compared to naturalized, highlighting contrasts between constructed floodplains and the heterogeneity in depositional bars typical of naturalizing channels. Consequently, restored inset floodplains would remove >50% more N than the naturalized floodplains during similar inundation events.

Brittany Hanrahan (Primary Presenter/Author), USDA Agricultural Research Service, br.hanrahan@gmail.com;


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


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


Matt Trentman ( Co-Presenter/Co-Author), Flathead Lake Biological Station, University of Montana, matt.trentman@flbs.umt.edu;


Sara McMillan ( Co-Presenter/Co-Author), Iowa State University, swmcmill@iastate.edu;


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