title: Stream primary producers relate positively to watershed natural gas measures in north-central Arkansas streams.
abstract: Construction of unconventional natural gas (UNG) infrastructure (e.g., well pads, pipelines) is an increasingly common anthropogenic stressor that increases potential sediment erosion. Increased sediment inputs into nearby streams may decrease autotrophic processes through burial and scour, or sediment bound nutrients could have a positive effect through alleviating potential nutrient limitations. Ten streams with varying catchment UNG well densities (0-3.6 wells/km(2)) were sampled during winter and spring of 2010 and 2011 to examine relationships between landscape scale disturbances associated with UNG activity and stream periphyton [chlorophyll a (Chl a)] and gross primary production (GPP). Local scale variables including light availability and water column physicochemical variables were measured for each study site. Correlation analyses examined the relationships of autotrophic processes and local scale variables with the landscape scale variables percent pasture land use and UNG metrics (well density and well pad inverse flow path length). Both GPP and Chl a were primarily positively associated with the UNG activity metrics during most sample periods; however, neither landscape variables nor response variables correlated well with local scale factors. These positive correlations do not confirm causation, but they do suggest that it is possible that UNG development can alleviate one or more limiting factors on autotrophic production within these streams. A secondary manipulative study was used to examine the link between nutrient limitation and algal growth across a gradient of streams impacted by natural gas activity. Nitrogen limitation was common among minimally impacted stream reaches and was alleviated in streams with high UNG activity. These data provide evidence that UNG may stimulate the primary production of Fayetteville shale streams via alleviation of N-limitation. Restricting UNG activities from the riparian zone along with better enforcement of best management practices should help reduce these possible impacts of UNG activities on stream autotrophic processes.
authors.affiliation: 601 Science and Engineering, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, United States. Electronic address: bjaustin@uark.edu.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Austin
authors.affiliation: Department of Biology, University of Central Arkansas, 201 Donaghey Ave., Conway, AR 72035, United States. Electronic address: talia.h91294@gmail.com.
authors.forename: Natalia
authors.initials: N
authors.lastname: Hardgrave
authors.affiliation: The Nature Conservancy, Ozark Highlands Office, 38 West Trenton Blvd., Suite 201, Fayetteville, AR 72701, United States. Electronic address: einlander@tnc.org.
authors.forename: Ethan
authors.initials: E
authors.lastname: Inlander
authors.affiliation: The Nature Conservancy, Ozark Highlands Office, 38 West Trenton Blvd., Suite 201, Fayetteville, AR 72701, United States. Electronic address: cgallipeau@tnc.org.
authors.forename: Cory
authors.initials: C
authors.lastname: Gallipeau
authors.affiliation: Department of Biology, University of Central Arkansas, 201 Donaghey Ave., Conway, AR 72035, United States. Electronic address: sentrekin@uca.edu.
authors.forename: Sally
authors.initials: S
authors.lastname: Entrekin
authors.affiliation: 601 Science and Engineering, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, United States. Electronic address: mevanswh@uark.edu.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Evans-White
mesh_terms: D059001:Aquatic Organisms / Q000502:physiology; D001131:Arkansas; D004784:Environmental Monitoring; D059206:Natural Gas / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D059206:Natural Gas; D014874:Water Pollutants, Chemical
keywords: Algal biomass; Gross primary production; Nutrient limitation; Unconventional natural gas infrastructures; Watershed land use