6/05/2017  |   14:00 - 14:15   |  301A

MERGING ECOSYSTEM AND FOOD-WEB UNDERSTANDING OF THE CONSEQUENCES OF TERRESTRIAL SUBSIDIES IN A FORESTED STREAM We combined estimates of secondary production of fishes, their diets, and bioenergetic efficiencies to estimate the contribution of aquatic vs. terrestrial prey to the trophic basis of production of 5 fishes in a Hokkaido stream. We found that 27-62% of total annual fish production was based on terrestrial prey, with terrestrial contributions to 3 dominant salmonid species all >56%. Organic matter fluxes to fish production totaled 8.79 g AFDM m^-2 y^-1 from terrestrial prey and 7.13 g AFDM m^-2 y^-1 from aquatic prey. Fish consumed 66% of the flux of terrestrial prey to fuel their production, and organic matter flows to fishes peaked in late summer when terrestrial prey input peaked, and when previous experiments have demonstrated positive indirect effects of terrestrial prey subsidies on aquatic invertebrates. Yet, at annual time scales fish consumed >80% of total aquatic invertebrate production, suggesting a nonlinear and dynamic fish-invertebrate interaction, and neutral or negative indirect effects of terrestrial subsidies on aquatic invertebrates. Combining ecosystem and food web perspectives may change our understanding of the indirect effects of prey subsidies across time scales.

Amy Marcarelli (Primary Presenter/Author), Michigan Technological University, ammarcar@mtu.edu;


Colden Baxter ( Co-Presenter/Co-Author), Idaho State University, baxtcold@isu.edu;


Joseph Benjamin ( Co-Presenter/Co-Author), USGS Forest and Rangeland Ecosystem Science Center, Corvallis, OR, jbenjamin@usgs.gov;


Yo Miyake ( Co-Presenter/Co-Author), Ehime University, miyake@cee.ehime-u.ac.jp;


Kurt D. Fausch ( Co-Presenter/Co-Author), Colorado State University, Department of Fish, Wildlife, and Conservation Biology, Fort Collins, CO 80523, Kurt.Fausch@colostate.edu;


Masashi Murakami ( Co-Presenter/Co-Author), Chiba University, muramasa@faculty.chiba-u.jp;


Shigeru Nakano ( Co-Presenter/Co-Author), Kyoto University, na;


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

EFFECTS OF ARTIFICIAL NIGHT LIGHTING ON FRESHWATER LITTORAL ECOSYSTEMS Artificial night lighting (ANL) has increased concurrently with human habitation along freshwater shorelines, which may influence the transfer of resources between aquatic and riparian ecosystems. We expected to find a greater abundance of riparian spiders, and adult aquatic and terrestrial insects, in littoral areas exposed to ANL. We also expected changes in benthic-macroinvertebrate-community composition since ANL extends foraging conditions for predatory fish. To test these predictions, we installed 20 1x1m enclosures in the littoral zone of Haven Hill Lake in Southeast Michigan (USA). We used a 2x2 factorial design; 10 enclosures were illuminated with 4 solar-powered LED “path-lights” and 10 housed pumpkinseed sunfish. We measured and analyzed benthic community composition, organic-matter decomposition, algal and macrophyte biomass, riparian spider density and biomass, and terrestrial invertebrate input. ANL increased riparian spider density and biomass by 101% and 51% respectively, and insect density by 139%. ANL also significantly altered terrestrial invertebrate community composition. No significant differences were found in benthic-invertebrate-community composition among light or fish treatments. We concluded that the influence of ANL on the transfer of resources across the aquatic-riparian boundary may have consequences for maintaining shoreline ecosystems.

Elizabeth Parkinson (Primary Presenter/Author), Dept. Biological Sciences, Oakland University, emparkinson@oakland.edu;


Scott Tiegs ( Co-Presenter/Co-Author), Oakland University, tiegs@oakland.edu;


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

Exploring exurban influences to nitrogen dynamics in a forest basin: a simulation study with hybrid modeling approach Forested mountains provide essential resources and services (e.g., clean water supply) to downstream ecosystems and human communities. Fast-growing exurbanization not only modifies terrestrial ecosystem but also aquatic ecosystem by changing nutrient input from terrestrial to aquatic. We developed a hybrid modeling approach to link a forest ecohydrological model, the Regional Hydro-Ecologic Simulation System (RHESSys), with a stream model to simulate the impacts of exurbanization on mountainside on the dissolved inorganic nitrogen (DIN) export. In this study, we focused on mountainside residential development as one type of exurbanization. We set three housing densities. Exurbanization elevated the annual discharge and annual DIN export from the terrestrial ecosystem. Elevated DIN inflow to the adjacent aquatic ecosystem accelerated in-stream decomposition and reduced in-stream DIN retention time. Similar impacts would potentially occur in further downstream reaches with amplified magnitude. Linking terrestrial ecosystem simulation with stream model provides a framework that incorporates longitudinal dynamics represented by stream network, additional to lateral dynamics (terrestrial hillslope processes), and thus helps to evaluate the impacts carried by stream network far reaching downstream.

Laurence Lin (Primary Presenter/Author), University of North Carolina at Chapel Hill, hrlauren@email.unc.edu;


Jack Webster ( Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University, jwebster@vt.edu;


Taehee Hwang ( Co-Presenter/Co-Author), Indiana University, taehee@indiana.edu;


Lawrence Band ( Co-Presenter/Co-Author), University of Virginia, leb3t@virginia.edu;


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

HOW DOES INUNDATION AFFECT DENITRIFICATION IN AGRICULTURAL LANDSCAPES? Anthropogenic activities have greatly altered the nitrogen cycle, necessitating nitrogen management strategies in agricultural landscapes. Our research utilized field sampling, along with water level manipulation in an experimental stream and flow-through basin to determine how periodic inundation affects denitrification rates, microbial communities, and nitrous oxide pulses. DNA-based methods were used to quantify total bacteria and denitrifying gene abundances for each step in denitrification. At field sites, locations that periodically flooded had high potential for denitrification. In the experimental stream, short-term flood events led to physiological increases in denitrification, and in the flow-through basin, locations that periodically flooded had sustained increased denitrification rates without consequential increases in nitrous oxide yields. Results suggest that management strategies that promote water retention on the floodplain and that would periodically inundate floodplains would stimulate the formation of denitrification hot spots and hot moments, and that reconnecting agricultural channels with their floodplains would enhance nitrate uptake.

Abigail Tomasek (Primary Presenter/Author), St. Anthony Falls Laboratory, Department of Civil Engineering, University of Minnesota, toma0074@umn.edu;


Jessica Kozarek ( Co-Presenter/Co-Author), St. Anthony Falls Laboratory, University of Minnesota, jkozarek@umn.edu;


Miki Hondzo ( Co-Presenter/Co-Author), St. Anthony Falls Laboratory, Department of Civil Engineering, University of Minnesota, mhondzo@umn.edu;


Michael Sadowsky ( Co-Presenter/Co-Author), BioTechnology Institute, University of Minnesota, sadowsky@umn.edu;


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

ARCTIC OASES? - HOW DOES THE DELAYED RELEASE OF WINTER DISCHARGE FROM AUFEIS AFFECT THE ECOSYSTEM STRUCTURE AND FUNCTION OF RIVERS Aufeis are massive accumulations of ice found along many arctic rivers, with aufeis on some Alaskan rivers covering 20+ km2 and attaining thicknesses of 3+ m. Although aufeis are prominent landscape features, understanding of their ecology is poor. We propose that aufeis function as summer oases by providing meltwater and nutrients to downstream habitats and winter oases due to insulating layers of ice that maintain below-ground freshwater habitat that would otherwise be frozen in regions of continuous permafrost. To gain information about the ecological roles of aufeis, we installed 50 ~1-m deep wells in a ~1.5 km2 aufeis field along the Kuparuk River, an arctic tundra river in Alaska. We assessed the predictions that aufeis provide perennially-unfrozen, below-ground habitat for a specialized invertebrate community while functioning as hot spots for nutrient regeneration. Freshwater invertebrates sampled from the wells represent a rich community consisting of flatworms, annelids, copepods, ostracods, chironomids (Krenosmittia, Trichotanypus) and stoneflies. Although the potential for below-ground NH4+ and NO3- regeneration was indicated, analyses were complicated by a surprisingly strong and dynamic apparent coupling of surface and below-ground water.

Alexander D. Huryn (Primary Presenter/Author), The University of Alabama, huryn@ua.edu;


Michael Gooseff ( Co-Presenter/Co-Author), University of Colorado, michael.gooseff@colorado.edu;


Martin Briggs ( Co-Presenter/Co-Author), U. S. Geological Survey, Hydrogeophysics Branch, Storrs, Connecticut, USA, mbriggs@usgs.gov;


Michael Kendrick ( Co-Presenter/Co-Author), The University of Alabama, kendrickmr@gmail.com;


Patrick Hendrickson ( Co-Presenter/Co-Author), University of Colorado, Patrick.Hendrickson@Colorado.EDU;


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

SYNCHRONICITY OF INSECT EMERGENCE ACROSS A RIVER-FLOODPLAIN MOSAIC Emergence of adult aquatic insects constitutes a resource flux that can influence a suite of terrestrial insectivores, and the relative importance of these emergence pulses to recipient food webs is largely determined by their timing and duration. Spatial heterogeneity may play a critical role in mediating the availability of these subsidies by creating patchiness, not just in magnitude of these fluxes, but in their temporal dynamics. Variability in environmental conditions across habitats within a landscape may desynchronize timing of emergence pulses, thereby prolonging availability of emergent insects to predators across that landscape. Different habitats may yield complementary or supplementary emergence patterns and predator mobility likely mediates their ability to capitalize on such fluxes. We conducted a year-round study of emergence across a mosaic of 7 habitats that varied in physical characteristics (e.g., thermal and flow regime) within the Snake River-floodplain in southeastern Idaho. Here, we present results from an analysis of the degree of synchronicity in the spectra of emergence from these habitats, and evaluate the contributions of habitat heterogeneity, life history variation, and composition of the insect community to these temporal dynamics.

Jade Ortiz (Primary Presenter/Author), Idaho State University, ortijade@isu.edu;


Colden Baxter ( Co-Presenter/Co-Author), Idaho State University, baxtcold@isu.edu;


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6/05/2017  |   15:30 - 15:45   |  301A

SEASONALITY OF AN AQUATIC-TERRESTRIAL LINKAGE IN A SUBTROPICAL ESTUARY Emergence of aquatic insects is an important mechanism of energy flow between aquatic and terrestrial habitats in freshwater systems. In estuaries, however, knowledge of the ecological role of aquatic insects is currently limited. We explored how seasonal variability in salinity and nutrient gradients are associated with community composition and availability of emergent insects to terrestrial consumers in estuarine habitats. Our study combined field surveys estimating aquatic insect emergence and riparian orb-weaving spider density with carbon and nitrogen isotope measurements to quantify this aquatic-terrestrial linkage across spatial (freshwater to marine) and seasonal (wet and dry) gradients in the Fakahatchee Strand Estuary, Florida. Aquatic insect emergence and riparian spider density varied seasonally at freshwater and mesohaline sites. Salinity was a strong predictor of aquatic insect emergence. Both salinity and season were important in explaining riparian spider density. Further analyses will examine how variability in emergent insect community composition across salinity gradients influences spider assemblages and their relative reliance on aquatic insects as nutritional subsidies. These findings provide evidence to the importance of cross-habitat connectivity in estuarine habitats.

Xavier Zapata-Rios (Primary Presenter/Author), Escuela Politécnica Nacional, xavier.zapata@epn.edu.ec;


S. Mažeika Patricio Sulliván ( Co-Presenter/Co-Author), The Ohio State University, sullivan.191@osu.edu;


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