6/05/2017  |   14:15 - 14:30   |  301B

INVESTIGATING THE POTENTIAL IMPACTS OF HYDRAULIC FRACTURING, AN ANALYSIS OF THE POTOMAC RIVER The process of hydraulic fracturing (fracking) has come under heavy public scrutiny in recent years as it has expanded across the United States. Fracking has enabled a new form of continental energy independence reliant on shale oil and gas development. The process ensues a series of post extraction effects related to both the disposal of wastewater and groundwater seeping that have resulted in higher concentrations of Ra226 in sediments downstream of fracking wells as well as elevated mean concentrations of Sr. When analyzed by individual state, mean surface water Ra224, Ba, Sr, and SO4 were found to be significantly lower in Virginia, a state without fracking in the Potomac Watershed. These results could indicate a natural baseline that could separate the underlying geology from the add-on effects of fracking technology, providing a useful guide for quantifying contamination in the future.

Colin Casey (Primary Presenter/Author), American University, cpcasey317@gmail.com;


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6/05/2017  |   14:30 - 14:45   |  301B

LANDSCAPE ECOHYDROLOGIC PATTERNS IN AQUATIC RESOURCE COMPENSATORY MITIGATION Compensatory mitigation for unavoidable impacts permitted under Clean Water Act §404 has continued to gain prominence since the 2008 Mitigation Rule, and landscape patterns in the practice of mitigation merit empirical research. We investigated topographic, soils, and land use features of an extensive geospatial dataset of mitigation sites. On average, project footprints generally exhibited topography and soil properties conducive to wetlands, and potentially suitable land cover types composed a substantial percentage area of mitigation sites, whereas agricultural and developed cover classes were less prominent. In addition, data describing the likely contribution to overall habitat connectivity suggested that valuable “hub” and “corridor” classes were well represented. Ongoing uncertainty surrounds the functional performance of projects individually and collectively, but these findings offer an encouraging sign that mitigation has at least tended toward plausibly suitable locations. More conclusively, this research demonstrates the potential for consistent and reproducible geospatial analyses to inform the regulatory process by revealing and clarifying key landscape-scale considerations for proposed mitigation sites.

Dan Auerbach (Primary Presenter/Author), Office of Wetlands, Oceans and Watersheds, USEPA, Washington DC, auerbach.dan@gmail.com;


Rachel Harrington ( Co-Presenter/Co-Author), U.S. Environmental Protection Agency Region 8, harrington.rachel@epa.gov;


Palmer Hough ( Co-Presenter/Co-Author), USEPA, hough.palmer@epa.gov;


Brian Topping ( Co-Presenter/Co-Author), U.S. Environmental Protection Agency, topping.brian@epa.gov;


Ashley Monroe ( Co-Presenter/Co-Author), USEPA, monroe.ashley@epa.gov;


William Ainslie ( Co-Presenter/Co-Author), USEPA, ainslie.william@epa.gov;


Eric Somerville ( Co-Presenter/Co-Author), US EPA, Region 4, somerville.eric@epa.gov;


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6/05/2017  |   14:45 - 15:00   |  301B

A sequential stopping-line method with continuous feedback to sampling precision: implication of fluctuation scaling in sampled fish abundance The variance function of population abundance has been widely used in the sampling program of agricultural pest and fisheries. Here, we introduce a ubiquitous variance function, called Taylor's law (TL), and develop a fixed-precision sequential sampling with continuous feedback. We tested TL using freshwater fish samples from a long-term gillnet experiment conducted in the fished and unfished areas of Lake Kariba, Africa. We confirmed a spatial version of TL using cross-sectional means and variances of fish sample abundances over time, in the fished and unfished areas separately. We estimated TL parameters from sequentially collected samples to update the stopping line and to give continuous feedback to the sampling precision. Our results showed that, compared to sampling planned a priori, the sequential stopping-line method can save around 3/4 of sampling effort in time and in net implementation. The mean abundance estimates were similar between the two methods, with a slight increase in the error-to-mean ratio for the sequential method. Our method can help fisheries managers to design efficient and economical sampling programs and can support effective guidelines on fishing and conservation.

Meng Xu (Primary Presenter/Author), Pace University, mxu@pace.edu;


Jeppe Kolding ( Co-Presenter/Co-Author), University of Bergen, jeppe.kolding@uib.no;


Joel E. Cohen ( Co-Presenter/Co-Author), The Rockefeller University and Columbia University, cohen@mail.rockefeller.edu;


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6/05/2017  |   15:00 - 15:15   |  301B

An Evaluation of Continuous Monitoring Data for Assessing Dissolved-Oxygen in the Boston Mountains, Arkansas Continuous water-quality monitoring data can be more useful for assessing the degree of variability over space and time than data collected periodically at discrete points in time. We assessed continuous dissolved-oxygen (DO) data at five USGS monitoring sites to evaluate assessment methodology that Arkansas applies to Boston Mountains streams with watersheds >10 mi2 (i.e. streams are listed as impaired when more than 10% of the measurements are < 6 mg/L). We evaluated data for periods of record available when stream temperatures exceeded 22o C, which Arkansas considers to be the “critical season”, from 2013 to 2015. The current assessment methodology for the Boston Mountains is effective at identifying streams with various degrees of impairment. The two sites designated as least disturbed by nutrient and land use indices exceeded the DO standard for <4% of unit values (measurements), while the three sites that were moderately and most disturbed exceeded the 6 mg/L standard for 20 to 33% of unit values. Our analysis also demonstrated the importance of other constituents such as pH and specific conductance for indicating the degree that photosynthetic processes and groundwater interactions influence DO concentrations.

Billy Justus (Primary Presenter/Author), USGS, Little Rock, AR, bjustus@usgs.gov;


Lucas Driver ( Co-Presenter/Co-Author), USGS, Lower Mississippi-Gulf Water Science Center, ldriver@usgs.gov;


Jessie Green ( Co-Presenter/Co-Author), Arkansas Department of Environmental Quality, greenj@adeq.state.ar.us;


Nathan Wentz ( Co-Presenter/Co-Author), Arkansas Dept of Environmental Quality, wentz@adeq.state.ar.us;


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6/05/2017  |   15:15 - 15:30   |  301B

THE DEVELOPMENT OF A TRAIT BASED THEORITCAL TEMPLATE FOR ASSESSING MACROINVERTEBRATES VULNERABILITY TO ELAVATED SEDIMENTS LOADS IN TSITSA RIVER AND ITS TRIBUTARIES, SOUTH AFRICA Fine sediment loads in global freshwater ecosystems have long been recognised as a major environmental problem. They pose serious threats to ecological structure and functions by adversely impacting on individual taxa and community composition of macroinvertebrates. Macroinvertebrates impact can be through direct effects including abrasion, clogging or indirect effects such as change in substrate composition and food web dynamics. In this study, we developed a theoretical trait-based template for predicting the vulnerability of macroinvertebrates to the effects of elevated sediment loads in freshwater ecosystems. The template was preliminarily evaluated in the Tsitsa River situated in a catchment prone to erosion and instream sediment loads. Our template successfully predicted the vulnerability of macroinvertebrates to sediments, indicating that taxa having external gills, possessing filter-feeding apparatuses, associated with bottom soft sediments and interstitial spaces between stones, were more vulnerable to sediments. Taxa having a combination or at least two of the following traits: a mechanism for tapping atmospheric oxygen, potential for aquatic exit, and high mobility, and free living were less vulnerable. The template holds potential for predictive biomonitoring and water resource management.

Pindiwe Ntloko (Primary Presenter/Author), Rhodes University, Institute for Water Research, ntloko80@gmail.com;


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