6/05/2017  |   09:00 - 09:15   |  302C

FLOW AND LARGE CONSUMER ALTERATIONS CAN HAVE LIMITED IMPACTS ON BENTHIC COLONIZATION IN PRODUCTIVE AGRICULTURAL STREAMS Increased water demand and more variable rainfall are expected to change stream flow regimes in the southeastern U.S. Predicted increases in floods and drying will increase benthic recolonization events, and concurrently change community interactions during recolonization as large consumers return from more distant refugia. We studied how stream benthos recover under altered flow and large consumer presence. We split a second order stream in half with 10 m long plastic barriers that diverted water to create high and low discharge sides at three sites. Consumer exclusion cages were nested within flow treatments. Neither a 2-fold difference in discharge and velocity, nor large consumers had a significant effect on algal or macroinvertebrate colonization during the five-week study. Although lower discharge increased overall benthic organic matter by 68%, benthic respiration and gross primary productivity were not significantly changed. This agricultural stream was highly productive with algal biomass exceeding 300 mg chl a m^-2. It appears bottom-up resource control may dominate physical and biological controls, suggesting impacted streams may be more resistant to changes in flow regimes when algal and macroinvertebrate source colonists are present.

Justin Murdock (Primary Presenter/Author), Tennessee Technological University, jnmurdock@tntech.edu;


Amy Doll ( Co-Presenter/Co-Author), Tennessee Tech University, aedoll42@students.tntech.edu;


Andrea Engle ( Co-Presenter/Co-Author), Tennessee Tech University, anengle42@students.tntech.edu;


Natalie Knorp ( Co-Presenter/Co-Author), Tennessee Tech University, neknorp42@students.tntech.edu;


Eric Malone ( Co-Presenter/Co-Author), Tennessee Tech University, ewmalone42@students.tntech.edu;


Grace McClellan ( Co-Presenter/Co-Author), Tennessee Tech University, gmcclellan@tntech.edu;


Melissa Moffet ( Co-Presenter/Co-Author), Tennessee Tech University, mcmoffet42@outlook.com;


Juliet Ohemeng-Ntiamoah ( Co-Presenter/Co-Author), Tennessee Tech University, johemengn42@students.tntech.edu;


Jason Payne ( Co-Presenter/Co-Author), Tennessee Tech University, jhpayne42@students.tntech.edu;


Robert Paine ( Co-Presenter/Co-Author), Tennessee Tech University, rtpaine42@students.tntech.edu;


Juju Wellemeyer ( Co-Presenter/Co-Author), Tennessee Tech University, cwellemey42@students.tntech.edu;


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6/05/2017  |   09:15 - 09:30   |  302C

EVALUATING INVERTEBRATE RESPONSES TO FLOW, LAND USE, AND LEVEL III ECOREGIONS IN THE DELAWARE RIVER BASIN The effects of land use, flow characteristics, and regionalization (level III ecoregions) on invertebrate assemblages were studied in the Delaware River Basin (DRB) using monitoring data from 1,488 sites obtained from 9 different agencies. Modeling methods including regression tree analysis (RT) were performed to identify significant environmental variables and model their relations with invertebrate responses (e.g., richness, EPT). Landscape scale attributes such as Level III ecoregions and land use (forest, urban, agriculture) strongly influenced invertebrate responses and often dwarfed the 24 flow metrics (magnitude, duration, timing) evaluated. These results indicate that the conditional effects of land form need to be considered when developing flow-response models. When only flow metrics were considered as predictors in the RT analyses, amplitude and measures of flow frequency were the most important predictors for all metrics studied. The information obtained from analyses of DRB data is being incorporated into ongoing modeling efforts aimed at facilitating more rigorous testing of flow-biology hypotheses and a better understanding of landscape effects on flow characteristics.

Jonathan Kennen (Primary Presenter/Author), U.S. Geological Survey, New Jersey Water Science Center, 3450 Princeton Pike, Suite 110, Lawrenceville, NJ 08648, jgkennen@usgs.gov;


Thomas Cuffney ( Co-Presenter/Co-Author), U.S. Geological Survey, South Atlantic Water Science Center, 3916 Sunset Ridge Rd., Raleigh, NC 27607, tcuffney@usgs.gov;


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6/05/2017  |   09:45 - 10:00   |  302C

LONG TERM RESPONSE OF FISHES TO EXPERIMENTAL HYDROPEAKING Peaking hydroelectric operations, generally considered harmful to biota, can be altered to mitigate effects, yet knowledge of whether environmental operational restrictions are protective is limited. We used a BACI design to test if removing operational restrictions on ramping rates (rate of change of flow) impacted the relative abundance, biomass and diversity of fishes. Electrofishing was conducted over 14 years on paired experimental regulated (Magpie) and reference (Batchawana) rivers, during Magpie ramping rate restrictions (2002-2004), and when no restrictions existed (2005-2015). Fish relative biomass was greater closer to the dam on the Magpie (2-10 km), but relative density showed no longitudinal effect (to 20 km). Neither metric showed downstream trends on the reference river. Overall the BACI interactions for relative biomass and density were significant in fast habitat, but only relative density was significant in the slow habitat. Results implicate that the change in dam operations had a greater effect on relative biomass and density of fish in fast habitat closer to the dam, but further from the dam, relative density was still affected. Relationships between flow metrics and fish relative density, biomass and diversity will be explored.

Karen Smokorowski (Primary Presenter/Author), Fisheries and Oceans Canada, Karen.Smokorowski@dfo-mpo.gc.ca;


Evan Timusk ( Co-Presenter/Co-Author), Fisheries and Oceans Canada, Evan.Timusk@dfo-mpo.gc.ca;


Michael Power ( Co-Presenter/Co-Author), University of Waterloo, m3power@uwaterloo.ca;


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6/05/2017  |   10:00 - 10:15   |  302C

CONTEXT DEPENDENT EFFECTS OF FLOW ON FISH Freshwater fish population dynamics and demographics are thought to be highly influenced by hydrologic conditions. However, creating transferrable flow ecology relationships for fish has proved challenging. This is in part because fish responses to flow vary due to factors such as the intensity of the flow event and the tolerance of the fish species. We propose that attributes of the flow event, habitat, and fish are the major sources of context dependency that drive variation in fish responses. We present preliminary analyses of fish-flow relationships for 60 stream reaches over five years with a focus on testing hypotheses related to these sources of context dependency. We test which flow metrics best predict fish abundance and size-structure and examine whether fish-flow relationships vary by fish species or stream reach degradation. We find that the relationship between fish abundance and flow does vary by species/stream reach combination and are currently conducting further analysis to better understand the patterns seen. Awareness of these sources of context dependency can help managers interpret and explain data and predict vulnerability of fish communities.

Annika Walters (Primary Presenter/Author), USGS Wyoming Coop Fish and Wildlife Unit, annika.walters@uwyo.edu;


Richard Walker ( Co-Presenter/Co-Author), University of Wyoming, rwalker2442@gmail.com;


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6/05/2017  |   10:15 - 10:30   |  302C

Response of arid-river fishes to extreme hydrologic and wildfire disturbance The extent to which populations and communities of stream organisms are influenced by natural and anthropogenic disturbance is influences by magnitude of the disturbances, characteristics of the habitat, and traits of species occupying those habitats. Unfortunately, there are relatively few systems that are sampled intensively on both spatial and temporal scales to capture responses to extreme events. We use data from long-term monitoring spanning a range of disturbances including supraseasonal drought, wildfire and extreme flooding to characterize the resistance and resilience of the fish communities of the upper Gila River basin in New Mexico. The response of fish communities to regional disturbances was most variable in headwaters, which ranged from complete extirpation of all taxa to undetectable changes in community structure. Mainstem sites responded more linearly to disturbance magnitude. Although native species were more broadly affected by disturbance than nonnatives, their recovery was generally rapid. Our results suggest resistance of fishes to disturbance is highly dependent on spatial position within the stream network and resilience is influence by species traits.

Keith Gido (Primary Presenter/Author), Kansas State University, kgido@ksu.edu;


David Propst ( Co-Presenter/Co-Author), University of New Mexico, tiaroga@comcast.net;


Skyler Hedden ( Co-Presenter/Co-Author), Arizona Department of Game and Fish, shedden@azgfd.gov;


Tyler Pilger ( Co-Presenter/Co-Author), FISHBIO, tjpilger@gmail.com;


Thomas Turner ( Co-Presenter/Co-Author), University of New Mexico, turnert@unm.edu;


James Whitney ( Co-Presenter/Co-Author), Pittsburg State University, jewhitney@pittstate.edu;


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