6/08/2017  |   09:00 - 09:15   |  302A

QUANTIFYING WATER QUALITY BENEFITS OF FLOODPLAIN RESTORATION IN AGRICULTURAL STREAMS AT BOTH THE REACH- AND WATERSHED-SCALE. Excess fertilizer nutrients entering Midwestern streams degrade both local and downstream water quality, while the restoration of inset floodplains in formerly channelized systems can reduce nutrient runoff from agricultural watersheds. At the reach-scale, we found that floodplain restoration using the two-stage ditch increased reach-scale nitrate-N removal via denitrification and reduced sediment export and associated phosphorus. Nevertheless, changes in stream nutrient concentrations were negligible due to very high loading and relatively short floodplain reaches (~ 600m). As a next step, we compiled empirical relationships for nutrient reductions using data collected from two-stage ditches across the Midwest, and applied them to the River Raisin Watershed (RRW) in the Western Lake Erie Basin. We modeled two-stage implementation in 25, 50, and 100% of headwater reaches in the RRW, and found that floodplains could reduce annual nitrate-N export by 2, 5 and 10%, respectively. The two-stage was even more effective at reducing total phosphorus (TP) export, which decreased by 10, 20 and 30%, respectively. Watershed-scale modeling suggested that longer two-stage implementations can result in policy-relevant reductions in nutrient and sediment export showing promise for improved water quality in agricultural landscapes at larger spatial scales.

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


Sheila Christopher ( Co-Presenter/Co-Author), University of Notre Dame, sheila.christopher@nd.edu;


Ursula H. Mahl ( Co-Presenter/Co-Author), University of Notre Dame, umahl@nd.edu;


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


Todd V. Royer ( Co-Presenter/Co-Author), Indiana University Bloomington, troyer@iu.edu;


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6/08/2017  |   09:15 - 09:30   |  302A

MECHANISMS OF COTTONWOOD SEEDLING ESTABLISHMENT IN GRAVEL-BED RIVERS, ACROSS A RANGE OF SCALES We propose that currently-accepted models for cottonwood establishment, derived for sandy streams, require modifications in gravel environments due to fundamental physical differences. There is agreement that the master variable driving regeneration and seedling success in western North American gravel-bed rivers is stage, through its effects on water availability. On the Nyack Floodplain of the Flathead River in Montana, we found that at the point scale, two variables determine suitable locations for seedlings to get a continued water supply through their first growth season: (i) a finer matrix, which retains more capillary water, and (ii) the surface gravel layer, acting as “rock mulch” (capillary barrier) to decrease evaporation. At the reach scale, we found that the typically observed arcuate bands of salicaceous trees are not explained by groundwater dynamics, but have a hydraulic fundament: hydrochory. The drift entrains seeds, which start germinating. Turbulent mixing advects some propagules into shallow zones along shorelines, where they deposit and start growing underwater; as stage recedes, the river seeds its own boundaries. Thus, spatial patterns of establishment depend on the drawdown of flow profiles between the beginning and end of the seed availability period.

Claudio Meier (Primary Presenter/Author), University of Memphis, cimeier@memphis.edu;


Richard Hauer ( Co-Presenter/Co-Author), University of Montana, ric.hauer@umontana.edu;


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6/08/2017  |   09:30 - 09:45   |  302A

Bayesian modeling of effects of flooding and dam removal on epilithic algal biomass in a monsoonal Taiwan stream Increasingly, dams are being removed to improve ecosystem integration. It is important to determine the effectiveness of these restoration efforts and the total cost of dam removal, especially in Mediterranean-climate and monsoonal streams with strong seasonal changes. In this study, we used Before-After-Control-Impact (BACI) design and a Bayesian mechanistic model to investigate algal responses to immediate and repeated sediment pulses after dam removal. Algal biomass decreased immediately after dam removal at a downstream site, and then rebounded within a month. Dam removal allowed sediments in the former reservoir to be washed downstream by high-flow events, but the pulses did not decrease algal biomass more than flooding alone due to scouring and burial. In monsoonal streams, the impacts of dam removal on epilithic algal biomass may be relatively temporary, and further study addressing the community structure is, however, needed to understand the further mechanism.

Ming-Chih Chiu (Primary Presenter/Author), Ehime University, Japan, mingchih.chiu@gmail.com;


Hao-Yen Chang ( Co-Presenter/Co-Author), Department of Life Sciences, National Chung Hsing University, Taiwan ROC, peter710503@gmail.com;


Hsing-Juh Lin ( Co-Presenter/Co-Author), Department of Life Sciences, National Chung Hsing University, Taiwan ROC, hjlin@dragon.nchu.edu.tw;


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6/08/2017  |   09:45 - 10:00   |  302A

CHANGES IN BENTHIC SUBSTRATE IN RESPONSE TO THE RESTORATION OF INSET FLOODPLAINS IN A MIDWESTERN AGRICULTURAL STREAM In the agricultural Midwest, stream channelization reduces habitat complexity, altering biodiversity and ecosystem function. We quantified changes in benthic substrate following floodplain restoration (via a two-stage ditch) over 10yrs in the Shatto Ditch (Indiana). For both the two-stage and upstream reference reaches (each 600m), we sampled 20 longitudinal transects to examine variation in substrate composition. Typical of agricultural streams, sand and FBOM dominated both reaches, nevertheless substrate composition showed seasonal patterns. FBOM accumulated during seasonal baseflow conditions (summer-fall), but was flushed out during spring storms to reveal coarser underlying gravels. Thus we found an inverse relationship between FBOM and sand, with sand dominating the two-stage reach in spring, along with some modest increases in the proportion of larger substrate (>2mm). Surprisingly, we also found an increase in larger substrate over time in the upstream reference reach, indicating the potential for stream naturalization when routine dredging ceases. In future, we hope to link substrate changes with macroinvertebrate responses, because seasonal patterns in substrate may influence biota as well as substrate-specific ecosystem processes such as sediment denitrification or reach-scale metabolism.

Anna Kottkamp (Primary Presenter/Author), University of Notre Dame, kottkamp.anna@gmail.com;


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


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


Ursula H. Mahl ( Co-Presenter/Co-Author), University of Notre Dame, umahl@nd.edu;


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


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6/08/2017  |   10:00 - 10:15   |  302A

BIOLOGICAL RESPONSE TO STREAM RESTORATION ON TENMILE CREEK Biological Response to Stream Restoration on Tenmile Creek David J. Parise, Tim Nuttle, Marisa N. Logan, Mark R. Haibach, Nathan S. Ober We counter three criticisms of stream restoration: lack of clear performance objectives, lack of biological improvement, and long recovery times. Using a case study of two stream restoration projects where permits specified biological performance criteria, we show that biological recovery can be observed within a relatively short time period. The projects were located along Tenmile Creek in southwestern Pennsylvania and employed natural channel design to correct channel instability caused by agricultural activity and changes to stream grade caused by post-mining subsidence. Federal and state permits required specific macroinvertebrate biological index values be met within five years at each site. Additional data on instream habitats and fish communities were also collected. Macroinvertebrate index and taxa richness improved following restoration by 8 to 17 points and from two to five taxa. Size and composition of fish communities remained similar between pre-mining and post-restoration; however, dominance shifted to less pollution-tolerant species. Because the restoration measures addressed the sources of degradation, permit-specified performance objectives were met within three years of restoration.

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


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6/08/2017  |   10:15 - 10:30   |  302A

TRANSIENT STORAGE REFLECTS A GRADIENT OF LARGE-WOOD VOLUME IN SOUTHEAST ALASKA STREAMS Transient storage is an important aspect of stream hydrology, but the response of storage metrics to changes in land-use remains poorly understood. For example, the reduction of in-stream large wood associated with forest timber harvest may exacerbate channel simplification and reduce transient storage. In contrast, restoration efforts to increase complexity via large wood additions may enhance storage. We explored the influence of in-stream structure on transient storage by conducting 33 tracer releases in 8 Southeast Alaska streams spanning a gradient of large-wood volume, including a restored reach. We conducted tracer additions at baseflow and stormflow to investigate whether storage metrics varied in a predictive fashion under different discharges. The relative area of storage and residence time were positively related to large-wood volume and were up to 5- and 10-fold higher, respectively, in streams with 5- to 15-fold higher large-wood volume. During stormflow, residence time decreased while storage area did not change. We found that large wood enhances channel transient storage, but that metrics generally did not change with increased discharge. Our results provide evidence that channel simplification has implications for in-stream transient storage, but restoration may mediate the impacts.

Peter S. Levi (POC,Primary Presenter), Drake University, peter.levi@drake.edu;


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


Antoine Aubeneau ( Co-Presenter/Co-Author), Purdue University, aubeneau@gmail.com;


Sarah G. Winikoff ( Co-Presenter/Co-Author), University of Minnesota, wini0019@morris.umn.edu;


Janine Ruegg ( Co-Presenter/Co-Author), Brandenburg University of Technology, jrueegg@GMAIL.COM;


Scott Tiegs ( Co-Presenter/Co-Author), Oakland University, tiegs@oakland.edu;


Dominic Chaloner ( Co-Presenter/Co-Author), University of Notre Dame, dchaloner@nd.edu;


Gary Lamberti ( Co-Presenter/Co-Author), University of Notre Dame, lamberti.1@nd.edu;


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