SFS Annual Meeting

5/21/2018  |   14:00 - 14:15   |  310 A

URBANIZATION, STREAM BASE FLOW, AND STREAMFLOW PERMANENCE Urbanization processes alter runoff generation and stream base flow and therefore can shift streamflow permanence, either through shifts in streamflow intermittence or ephemeral flow. Changes to streamflow intermittence can occur with changes in groundwater recharge and discharge due urbanization processes such as infiltration of stormwater, changes to evapotranspiration, lawn irrigation, water supply pipe leakage, impervious surface cover, and infiltration of groundwater into wastewater pipes. Changes to runoff generation processes in urban areas can increase or decrease the presence of ephemeral flow in streams. Spatial and temporal changes to streamflow permanence may dramatically alter the ecological and social characteristics of headwater streams as they undergo urbanization. The effects of urbanization on stream base flow are explored across climate regions in this presentation. Particular focus is given to the effects of stormwater infiltration on urban stream base flow, with empirical, modeled, and conceptual frameworks.

Aditi Bhaskar (Primary Presenter/Author), Colorado State University, aditi.bhaskar@colostate.edu;


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5/21/2018  |   14:15 - 14:30   |  310 A

HOW IS A STREAM IMPACTED BY BURIAL? EXAMINING THE SPATIAL VARIATION WITHIN URBAN BURIED STREAMS IN CINCINNATI, OH. While the effects of urbanization on stream ecosystems have been well-documented, little is known regarding the impact of burying streams within culverts. Our project aims to explore the ecological impacts of stream burial at a fine spatial scale. Two culverted urban streams in Cincinnati, OH, USA were evaluated over 8 months to achieve this aim, with measurements made along a spatial gradient above, within, and below the culverts. Monthly periphyton samples were collected from artificial substrate, and monthly deployments of dissolved oxygen and temperature loggers were used to evaluate rates of gross primary production (GPP) and ecosystem respiration (ER). Preliminary results demonstrate that ash-free dry mass (AFDM) of periphyton was lower in buried reaches than in open upstream and downstream reaches, as expected. GPP was supported at lower levels within buried reaches and continued to decrease with distance downstream within the buried reach. ER was supported at lower levels within buried reaches as well, but showed little within-culvert spatial variation. The differing responses of GPP and ER can lead to patches of low stream dissolved oxygen, particularly at the downstream end of culverts and during periods of low flow.

Tammy Newcomer-Johnson (Co-Presenter/Co-Author), US EPA, Newcomer-Johnson.Tammy@epa.gov;


Ken Fritz (Co-Presenter/Co-Author), US Environmental Protection Agency, Office of Research and Development, fritz.ken@epa.gov;


Ishi Buffam (Co-Presenter/Co-Author), University of Cincinnati, buffamii@ucmail.uc.edu;


Chelsea Hintz (Primary Presenter/Author), University of Cincinnati, hintzca@mail.uc.edu;


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5/21/2018  |   14:30 - 14:45   |  310 A

HIGH BETA-DIVERSITY OF URBANIZED STREAM MICROBIAL COMMUNITIES Watershed urbanization is known to change microbial community composition in headwater streams. Most research on the impact of stream urbanization on microbial communities measure only the intensity of urban impacts. Yet, urbanization is a heterogeneous process: urbanized stream beds can be composed of natural or artificial substrates, encased in cement, or heavily incised. Further, presence or absence of riparian canopy cover can also strongly influence microbial habitats. Existing studies that classify stream urbanization based solely on watershed impervious cover do not capture the diversity of microbes among urbanized watersheds. Thus, less attention has been paid to microbial communities across different urbanized stream habitats. We assessed microbial communities from 20 streams in Connecticut, USA using 16S rDNA sequenced with Illumina MiSeq. We found that microbial communities were related stream watershed impervious cover, but with a high degree of beta-diversity across urbanized stream sites. We linked this diversity between urbanized streams to differences in stream bed, water chemistry, and riparian cover that were not linked to the intensity of watershed urbanization. We argue that diversity of urbanized stream microbial communities will have implications for nutrient cycling and food web structure.

Jacob Hosen (Primary Presenter/Author), Purdue University, jhosen@purdue.edu;


Byron Crump (Co-Presenter/Co-Author), Oregon State University, bcrump@coas.oregonstate.edu;


Charles Leal (Co-Presenter/Co-Author), Oregon State University, lealch@oregonstate.edu;


Rachel Lowenthal (Co-Presenter/Co-Author), Yale University, rachel.lowenthal@yale.edu;


Wenjun Song (Co-Presenter/Co-Author), Yale University, wenjun.song@yale.edu;


Lisa Weber (Co-Presenter/Co-Author), Yale University, lisa.weber@yale.edu;


Peter Raymond (Co-Presenter/Co-Author), Yale University, peter.raymond@yale.edu;


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5/21/2018  |   14:45 - 15:00   |  310 A

SETTING MANAGEMENT TARGETS FOR URBANIZED STREAMS: CONSTRAINTS AND OPPORTUNITIES The urban stream syndrome is a reality in urban landscapes, with degraded biological conditions almost universally accepted. From a regulatory perspective, assessment, restoration, and permitting goals for urban streams are frequently based on a single, least-disturbed reference based biological condition target. For urban stream management, this raises important questions: is a single biological target based on reference condition an achievable goal? What other structure might exist? In past talks, we presented analysis of biological conditions along urban gradients in North Carolina to explore these questions. We found that essentially no streams in urban watersheds met least-disturbed reference based targets. However, biological condition did vary within these watersheds, with some maintaining better biological conditions than others. We developed a biological potential model to evaluate sites that were further from meeting what is attainable in urban streams and used that to explore and compare watershed and reach scale predictors to try and understand this variability. In this presentation, we layout a framework for better management of biological conditions in urban streams that builds from the biological potential model and we offer alternative management goals based on ecosystem goods and services.

Michael Paul (Primary Presenter/Author), U.S. Environmental Protection Agency, Paul.Michael@epa.gov;


Diane Allen (Co-Presenter/Co-Author), Tetra Tech Inc., Diane.Allen@tetratech.com;


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5/21/2018  |   15:00 - 15:15   |  310 A

CAUSES AND CONSEQUENCES OF URBAN HEADWATER HETEROGENEITY Like non-urban streams, streams in urban areas have heterogeneous structure and function. In addition to natural sources of variation, urban streams vary across gradients of land cover, legacies, and infrastructure. Variation exists across scales – both within and across cities and has important consequences for stream function. In this presentation, I focus on stormwater infrastructure as an important source of heterogeneity in urban headwater streams. Given the highly modified nature of urban flow paths, zero-order urban streams are often designed stormwater conveyance systems. The design of these systems can vary substantially, from highly connected storm sewers to disconnected retention basins, with important consequences for the hydrology and biogeochemistry of small urban watersheds. The underlying drivers of stormwater heterogeneity include development history both with cities and across cities, as well as climate and other biophysical factors. In addition to technological developments in infrastructure design, stormwater systems reflect shifting and expanding priorities in urban environmental management. In contrast to the paradigm of urban homogenization, urban headwaters display significant heterogeneity, which is the result of the complex social-ecological dynamics of urban ecosystems.

Rebecca Hale (Primary Presenter/Author), Smithsonian Environmental Research Center, haler@si.edu;
Rebecca Hale is an ecosystem ecologist who works at the interface of biogeochemistry, hydrology, and society. In addition to traditional ecological methods, she adapts concepts and tools from geography, sociology, and history to ask fundamental ecosystem ecology questions in non-traditional settings. She works within and across cities and rural areas at local to regional scales.

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5/21/2018  |   15:15 - 15:30   |  310 A

COMPARISON OF DIFFERENT METABOLISM MEASUREMENT METHODS TO EVALUATE IMPACT OF WASTEWATER TREATMENT PLANT EFFLUENT DISCHARGE ON AN URBAN STREAM Point source nutrient discharges to urban streams spur in-stream metabolic activity, but there may be limits to this increase. We used multiple methods to determine in-stream metabolism, including plateau injections of the Raz-Rru metabolic tracer system, diurnal dissolved oxygen modeling, and longitudinal nutrient patterns, along two reaches of the same second-order stream in urbanized Montgomery County, PA. Each reach was directly below the outfall of a wastewater treatment plant. In the 2000m below the outfall of the upstream, headwater treatment plant, N and P concentrations decreased by 10-15%, Raz to Rru transformation was approximately 30%, and ecosystem respiration on the day of the tracer injection was 7.8 g O2 m-2 d-1. In comparison, in the 1500m below the downstream treatment plant, nutrient concentrations increased, Raz did not measurably transform, but daily ecosystem respiration was 7.9 g O2 m-2 d-1. The upstream reach had a higher percentage of flow from the treatment plant than the lower reach. The lack of agreement between methods shows the need to use multiple metabolism measurement methods in high nutrient urban streams to parse out hydrologic and metabolic controls on in-stream nutrient concentrations.

Sarah Ledford (Primary Presenter/Author), Department of Earth and Environmental Science, Temple University, sarah.ledford@temple.edu;


Marie J. Kurz (Co-Presenter/Co-Author), Oak Ridge National Laboratory , kurzmj@ornl.gov;


Laura Toran (Co-Presenter/Co-Author), Department of Earth and Environmental Science, Temple University, ltoran@temple.edu;


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