5/22/2016  |   13:30 - 13:45   |  315

DRAINING THE TANK TWICE A DAY: WHAT TIDAL FRESHWATERS CAN TELL US ABOUT THE ROLE OF HYDROLOGY IN BENTHIC COMMUNITY STRUCTURE Tidal freshwaters are poorly integrated into conceptual freshwater community ecology. The benthic invertebrate communities of tidal freshwaters are thought to be less diverse than nearby non-tidal freshwaters, but the underlying mechanisms are unclear. We collected benthic community data from three tidal heights across a vegetated freshwater intertidal zone, and from nearby inland freshwater habitats that varied in their permanence. We hypothesized that communities would be differentiated along a gradient of tidal height, with increasing tidal height excluding taxa that are intolerant of prolonged emersion. Communities in low tidal marshes and permanent inland sites overlapped considerably, likely due to similarity in selection pressures (i.e. low desiccation risk, high fish predation risk). Some taxa were found at all sites and are apparently hydrological generalists. By integrating tidal freshwaters into the models of community structure currently applied to seasonal and permanent freshwaters, we can develop a broader understanding of the mechanisms structuring communities in both tidal and non-tidal freshwaters.

Jack McLachlan (Primary Presenter/Author), University of Maine, jack.mclachlan@maine.edu;


Braden Adams ( Co-Presenter/Co-Author), University of Maine, braden.adams@maine.edu;


Erin Nolan ( Co-Presenter/Co-Author), University of Maine, erin.a.nolan@maine.edu;


Hamish Greig ( Co-Presenter/Co-Author), University of Maine, hamish.greig@maine.edu;


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5/22/2016  |   13:45 - 14:00   |  315

BENTHIC RESPONSE TO FLOW ALTERATION IN A NEW MEXICO ARID MOUNTAIN STREAM Pressure on streams and rivers for consumptive use requires the development of tools and decision-making processes for water managers to minimize impacts on ecological function. This paper examines the utility of modeling benthic biomass in relation to benthic macroinvertebrate (BMI) community attributes for water resource management scenarios in the Gila River, New Mexico. The river benthos biomass model (RivBio) was used in conjunction with hydraulic modeling to predict growth and decline of benthic biomass. BMI community attributes were compared along gradients of hydrologic impact in the Cliff Gila Valley and in similar regional streams. Benthic biomass was minimally affected by proposed diversions at flows above 4.25 cms, but was severely reduced downstream because of existing diversions. Riffle habitat was disproportionately affected during extreme low and interrupted flow, resulting in more multi-habitat generalists. Flow augmentation from proposed diversions and storage would greatly mitigate these existing biomass losses by providing consistent base flow and lotic conditions in riffle habitat. Both benthic biomass and BMI community endpoints were useful when comparing water management scenarios.

Chad Wiseman (POC,Primary Presenter), HDR, Inc., chad.wiseman@hdrinc.com;


Brian Marotz ( Co-Presenter/Co-Author), Marotz Enterprises, bjotz@centurytel.net;


Jarvis Caldwell ( Co-Presenter/Co-Author), HDR, Inc., jarvis.caldwell@hdrinc.com;


Robert Sherrick ( Co-Presenter/Co-Author), HDR, Inc., Robert.Sherrick@hdrinc.com;


David Ward ( Co-Presenter/Co-Author), HDR, Inc., David.Ward@hdrinc.com;


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5/22/2016  |   14:00 - 14:15   |  315

NOVEL HYDROLOGIC REGIMES DISRUPT INSECT LIFE HISTORY STRATEGIES: EFFECTS OF HYDROPEAKING ON INSECT OVIPOSITION Previous studies quantifying the density, distribution and diversity of aquatic insects overwhelmingly focus on larval life stages. However, many aquatic insects exhibit selective oviposition behaviors, with a preference for emergent substrates along a river’s edge. The practice of hydropeaking creates an artificial intertidal zone that is absent from natural rivers and to which freshwater organisms are not adapted. We hypothesized that this novel disturbance could reduce the availability and temporal persistence of oviposition habitats resulting in egg mortality. To test this hypothesis, we quantified the oviposition behavior of four aquatic insects using a hierarchical field survey of habitat availability and utilization. We found that three out of four genera exhibited preferences for larger, emergent substrates located along the river edge, thus increasing the likelihood of desiccation during stage height fluctuations. When subject to experimental drying, we observed up to 93% egg mortality during desiccation lasting two hours or less, and 100% mortality when desiccation exceeded four hours. These paired field and experimental results suggest that hydropeaking could impart a population bottleneck on aquatic insects.

Scott Miller (Primary Presenter/Author), BLM/USU National Aquatic Monitoring Center, Department of Watershed Sciences, Utah State University, scott.miller@usu.edu;


Matt Schroer ( Co-Presenter/Co-Author), BLM/USU National Aquatic Monitoring Center, Department of Watershed Sciences, Utah State University, mattschroer@gmail.com;


Jesse Fleri ( Co-Presenter/Co-Author), Utah State University, jessefleri@gmail.com;


Ted Kennedy ( Co-Presenter/Co-Author), USGS Southwest Biological Science Center, Grand Canyon Monitoring and Research Center, tkennedy@usgs.gov;


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5/22/2016  |   14:15 - 14:30   |  315

LINKING HYDROLOGY AND A MACROINVERTEBRATE METACOMMUNITY ASSEMBLY IN A REGULATED FLOODPLAIN Despite the recognition of floodplains as biodiversity hot-spots, their ecological state is in decline worldwide due to human activities such as flow regulation and channelization. The inherent complexity of floodplain ecosystems impedes the development of ecologically relevant flow recommendations. For instance, lateral habitats contribute disproportionally to biodiversity in alluvial floodplains, and management models should incorporate the dependencies between hydrology and the functioning of these habitats if they are to preserve biodiversity in the long term. To identify processes linking hydrology and metacommunity assembly, we sampled macroinvertebrates in a set of lateral habitats of a regulated floodplain during summer 2015. We investigated the relative effects of local environmental conditions (related to origins of water and organic matter dynamics) and spatial patch arrangement on community composition and trophic structure. Preliminary results confirm that lateral habitats contribute to a large part of biodiversity in this particular floodplain and suggest that both environmental conditions and distance have an effect on community composition. These first results emphasize the importance of considering the mosaic of lateral habitats and their connectedness in floodplain ecohydrological models.

Pierre Chanut (Primary Presenter/Author), EAWAG (Swiss Federal Institute of Aquatic Science and Technology), pierre.chanut@eawag.ch;


Christopher Robinson ( Co-Presenter/Co-Author), Swiss Federal Institute of Aquatic Science and Technology, EAWAG ; Aquatic Ecology dpt., Christopher.robinson@eawag.ch;


Thibault Datry ( Co-Presenter/Co-Author), INRAE, France, Thibault.datry@inrae.fr;


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5/22/2016  |   14:30 - 14:45   |  315

RESTORATION OF LARGE WOOD TO A SALMONID STREAM IN WESTERN WASHINGTON: LOOKING FOR EFFECTS BEYOND PHYSICAL HABITAT STRUCTURE Restoring wood to streams can improve physical habitat for fish, but there may be additional benefits as well. We examined the potential for added wood to enhance the hydraulic complexity and thermal conditions within the Raging River, near Seattle, WA. The river drains second-growth forest and provides critical habitat for salmonids, but is thermally stressed. In 2009, to improve conditions for salmonids, we placed nearly 100 untethered logs in a 200-m reach where wood was historically removed. In 2015, we quantified habitat and thermal conditions in reaches with and without added wood. We accounted for the movement and transformation of log jams since 2009, assessed fish use, used instantaneous salt tracers to measure residence time in multiple reaches, and for one week, we measured near-streambed temperatures averaged over 1-meter intervals with a fiber-optic distributed temperature sensor (DTS) at 30-minute intervals. Although the clearest benefit of the wood was likely the increase in physical habitat complexity, temperature data from several piezometers suggest there may be subtle but important effects of added wood on hyporheic processes including cold water upwelling.

Kate Macneale (Primary Presenter/Author), King County - Water and Land Resources, kate.macneale@kingcounty.gov;


Andrew Gendaszek ( Co-Presenter/Co-Author), USGS, agendasz@usgs.gov;


Ray Timm ( Co-Presenter/Co-Author), Cramer Fish Sciences, ray.timm@fishsciences.net;


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5/22/2016  |   14:45 - 15:00   |  315

EFFECTS OF FOREST MESOPHICATION ON STREAMFLOW ACROSS THE EASTERN US In a process known as mesophication, climate change and anthropogenic disturbances in forests of the eastern US have favored drought and fire intolerant mesophytic tree species of relatively high water use. We hypothesize that mesophication is reducing streamflow (Q) in forested watersheds throughout the region. To test this hypothesis, we quantified changes in Q from 1960 to 2012 in 202 reference forested watersheds across the eastern US, and separated the effect of changes in the forest from changes in climate using Auto-Regressive Integrated Moving Average (ARIMA) time series modeling. We then linked forested-related changes in Q to changes in forest structure and species composition using plot-level forest measurements in each watershed derived from USDA Forest Service Forest Inventory and Analysis (FIA) data. A conservative preliminary analysis suggests that 19 of the 202 watersheds (9.4%) have had significant reductions in Q due to changes in forest structure and species composition. Mesophication could have significant implications for water supply in the region and may inform forest management strategies to mitigate climate change impacts on water resources.

Peter Caldwell (Primary Presenter/Author), USDA Forest Service, Center for Forest Watershed Science, Coweeta Hydrologic Lab 3160 Coweeta Lab Road, Otto, NC 28763, pcaldwell02@fs.fed.us;


Andy Hartsell ( Co-Presenter/Co-Author), USDA Forest Service Southern Research Station,Forest Inventory & Analysis, ahartsell@fs.fed.us;


Chelcy Miniat ( Co-Presenter/Co-Author), USDA Forest Service, Southern Research Station, Center for Forest Watershed Research, Coweeta Hydrologic Laboratory, cfminiat@fs.fed.us;


Katherine Elliott ( Co-Presenter/Co-Author), USDA Forest Service, Southern Research Station, Center for Forest Watershed Research, Coweeta Hydrologic Laboratory, kelliott@fs.fed.us;


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