Sunday, May 22, 2016
13:30 - 15:00

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13:30 - 13:45: / 302-303 EXPERIMENTAL EVIDENCE THAT HEMLOCK DECLINE CHANGES THE ROLE OF DETRITAL SUBSIDIES IN FRESHWATER FOOD WEBS

5/22/2016  |   13:30 - 13:45   |  302-303

EXPERIMENTAL EVIDENCE THAT HEMLOCK DECLINE CHANGES THE ROLE OF DETRITAL SUBSIDIES IN FRESHWATER FOOD WEBS Shifts in forest composition are anticipated a consequence of climate change interactions with forest pests. Resulting changes in tree species have the potential to alter terrestrial subsidies to freshwaters by changing the quantity and quality of detritus. We tested the response of food webs in aquatic mesocosms to changing detrital quality observed to occur with hemlock (Tsuga canadensis) decline. We added gradients of leaf-litter reflecting a shift from hemlock to a less-palatable species (Rhododendron maximum) that is becoming dominant in the southeast, or a more palatable leaf (red maple, Acer rubrumL.) that is anticipated in the northeast. Pulses of dissolved organic carbon and ammonium were released in mesocosms with higher proportions of maple, whereas Rhododendron treatments had little effect on these variables. Producers and consumers tracked shifting detrital resources, but responses attenuated with increasing trophic position and were overwhelmed by the stochastic establishment of filamentous algae. Our results suggest that the loss of hemlock will have ecosystem-level consequences for forested freshwaters, but the nature of these changes depends on replacement tree species and the relative importance of stochastic community processes.

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


Krista Capps ( Co-Presenter/Co-Author), University of Georgia, kcapps@uga.edu;


Jacquelyn Gill ( Co-Presenter/Co-Author), University of Maine, jacquelyn.gill@maine.edu;


Amanda Klemmer ( Co-Presenter/Co-Author), University of Maine, klemmer.amanda@maine.edu;


Robert Northington ( Co-Presenter/Co-Author), University of Maine, robert.northington@maine.edu;


Thomas Parr ( Co-Presenter/Co-Author), University of Delaware, tbparr@udel.edu;


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13:45 - 14:00: / 302-303 EFFECTS OF SHADING ON STREAM WATER TEMPERATURE AND STENOTHERMIC MACROINVERTEBRATES ALONG A EUROPEAN LATITUDINAL CLIMATE GRADIENT

5/22/2016  |   13:45 - 14:00   |  302-303

EFFECTS OF SHADING ON STREAM WATER TEMPERATURE AND STENOTHERMIC MACROINVERTEBRATES ALONG A EUROPEAN LATITUDINAL CLIMATE GRADIENT We showed that shaded reaches have a significant effect on the water temperature of lowland streams, both by cooling the water when its flows from an upstream open area into the forest and by having a downstream cooling effect when the water flows from the forest into an open area. Despite a temperature effect was commonly detected, the magnitude of the effect differed considerably among streams. We showed that this was partly the result of the LAI of the riparian forest canopy and of the current velocity. Based on the presence of stenothermal macroinvertebrates, we detected an effect on soft-substrate inhabiting species, with more warm-stenothermic and potamal species in the open reaches and more crenal species in the shaded reaches of the streams, indicating that the cooling by the forest or warming in the open areas had consequences for the biota of the streams. It can be concluded that planting wooded riparian zones is a legitimate stream temperature mitigation measure from which macroinvertebrates preferring relatively low stream water temperatures could benefit.

Piet F.M. Verdonschot (Primary Presenter/Author), University of Amsterdam / Wageningen Environmental Research , piet.verdonschot@wur.nl;


Ralf C.M. Verdonschot ( Co-Presenter/Co-Author), Wageningen Environmental Research, ralf.verdonschot@wur.nl;


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14:00 - 14:15: / 302-303 NEON AQUATIC MACROINVERTEBRATE SAMPLING AT THE CONTINENTAL SCALE

5/22/2016  |   14:00 - 14:15   |  302-303

NEON AQUATIC MACROINVERTEBRATE SAMPLING AT THE CONTINENTAL SCALE The National Ecological Observatory Network (NEON) is a national-scale research platform designed to assess the impacts of climate change, land-use change, and invasive species on ecosystem structure and function across 20 ecoclimatic domains from Alaska to Puerto Rico. NEON’s aquatic program is comprised of a suite of instrument and observational data collected at 24 wadeable streams, 7 lakes, and 3 large rivers, including biogeochemistry, hydrology, site morphology, and biology. Data are rigorously quality-checked before being provided publicly via NEON’s web portal. During the first two years of sampling, aquatic macroinvertebrate samples were collected at 17 NEON sites using standard sampling protocols. Data collected by field technicians and external taxonomists undergo an automated quality assurance process prior to being packaged and hosted on the NEON data portal. A subset of these data are expected to be available in summer 2016, providing opportunities to connect organismal data to other available supporting data streams, such as continuously monitoring sensors, stream discharge, and water chemistry data. When operating at full capacity, NEON macroinvertebrate data will be available from 34 sites across the observatory.

Stephanie Parker (Primary Presenter/Author), NEON/Battelle, sparker@battelleecology.org;


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14:15 - 14:30: / 302-303 INVERTEBRATE COMMUNITY COMPOSITION AND DRIVERS OF ASSEMBLAGE DISSIMILARITY BETWEEN RUNOFF AND SPRING-FED RIVERS

5/22/2016  |   14:15 - 14:30   |  302-303

INVERTEBRATE COMMUNITY COMPOSITION AND DRIVERS OF ASSEMBLAGE DISSIMILARITY BETWEEN RUNOFF AND SPRING-FED RIVERS Flow variability plays an important role in structuring lotic communities, yet we know comparatively little about processes governing species assemblage dynamics in stream ecosystems exhibiting stable environmental conditions. We sampled invertebrate assemblages and quantified primary productivity and habitat characteristics over four seasons from spring-fed and runoff rivers in northern California. Runoff rivers exhibited high variability in discharge and temperature, while spring-fed rivers were relatively stable with high naturally-occurring nutrient levels. On average, nutrient concentrations were 40-fold greater in spring-fed rivers. Spring-fed rivers supported nearly seven-fold greater invertebrate densities than runoff systems, but invertebrate richness was greater in runoff rivers over all seasons. Spring-fed assemblages correlated with elevated nutrient concentrations and basal carbon resources, while runoff assemblages were associated with increased discharge variability and median particle size. We suggest that runoff invertebrate assemblages in this study are constrained by abiotic factors, while density dependent processes may be more important in regulating diversity in spring-fed rivers. Abiotic stability and abundant food resources also indicate that spring-fed systems will play an increasingly important role in conserving coldwater species under a rapidly changing climate.

Robert Lusardi (Primary Presenter/Author), University of California, Davis, ralusardi@gmail.com;


Randy Dahlgren ( Co-Presenter/Co-Author), University of California, Davis, radahlgren@ucdavis.edu;


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14:30 - 14:45: / 302-303 LAKES IN DRYLANDS: VARIATION IN CHIRONOMID COMMUNITIES IN WESTERN MONGOLIA LAKES

5/22/2016  |   14:30 - 14:45   |  302-303

LAKES IN DRYLANDS: VARIATION IN CHIRONOMID COMMUNITIES IN WESTERN MONGOLIA LAKES Western Mongolia is an arid region characterized by a variety of lake ecosystems. These lakes increasingly face environmental stress from grazing and climate change. Data from lake samples collected in 2004 and 2005 are used to characterize the lake ecosystems prior to the most recent changes in the region. We evaluated variation in chironomid community assemblages based on surface-floating pupal exuviae (SFPE) in relation to environmental features of fifty-three lakes. The study lakes spanned wide gradients in conductivity, alkalinity, and anion concentration. Results of multivariate analyses indicated that taxonomic richness fell along a gradient of conductivity with lower richness in high conductivity lakes. A shift to more saline tolerant taxa was observed along a gradient of conductivity, alkalinity, and anion concentration. Chlorophyll a, pH, and transparency also appeared to be important drivers of community structure. Although lakes were sampled along an elevational gradient community composition did not vary along this gradient. These results provide insight into the environmental factors that influence chironomid communities and can be used to establish baseline conditions in a unique, but threatened landscape.

R. William Bouchard, Jr. (Primary Presenter/Author), Minnesota Pollution Control Agency, bouc0048@umn.edu;


Barbara Hayford ( Co-Presenter/Co-Author), University of Montana, bhayford@gmail.com;


Leonard C. Ferrington, Jr. ( Co-Presenter/Co-Author), University of minnesota, ferri016@umn.edu;


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14:45 - 15:00: / 302-303 CONTRASTING RESPONSES OF MAYFLY GROWTH TO EXPERIMENTAL WARMING ACROSS ELEVATION GRADIENTS IN TEMPERATE AND TROPICAL STREAMS

5/22/2016  |   14:45 - 15:00   |  302-303

CONTRASTING RESPONSES OF MAYFLY GROWTH TO EXPERIMENTAL WARMING ACROSS ELEVATION GRADIENTS IN TEMPERATE AND TROPICAL STREAMS Increases in temperature associated with climate change may impact aquatic biota differentially depending on the temperature variability they currently experience. We hypothesized that macroinvertebrates from temperate streams, which experience greater seasonal and diel temperature fluctuations, will be less vulnerable to elevated temperatures compared to phylogenetically-related organisms from tropical regions, where temperatures are more stable. We used streamside mesocosms to test effects of three temperatures (ambient, +2.5°C and +5°C) on growth rates of Baetidae mayflies in the Colorado Rockies (CO) and Ecuadorian Andes (EC). We conducted reciprocal transplants across a ~1200m elevational gradient in both locations. Warming responses generally followed expectations, with higher growth rates at higher temperatures in CO for both mesocosms and transplants. However, EC Baetidae had overall slower growth rates at similar temperatures, and increasing temperatures did not lead faster growth. In CO, high elevation individuals grew the fastest at warmer temperatures, but we did not observe this for EC Baetidae. Invertebrate responses to climate change are likely to vary for even related taxa adapted to different climates.

Amanda Rugenski (Primary Presenter/Author), University of Georgia, atrugenski@gmail.com;


Andrea Landeira-Dabarca ( Co-Presenter/Co-Author), Universidad San Francisco de Quito, andrealandab@gmail.com;


Carla L. Atkinson ( Co-Presenter/Co-Author), University of Alabama, carlalatkinson@gmail.com;


Jake Sousa ( Co-Presenter/Co-Author), Cornell University, jps396@cornell.edu;


Andrea C. Encalada ( Co-Presenter/Co-Author), Instituto BIOSFERA, Universidad San Francisco de Quito, Cumbayá, Ecuador Biológicas y Ambientales, Universidad San Francisco de Quito, Cumbaya, Ecuador, aencalada@usfq.edu.ec;


Steven Thomas ( Co-Presenter/Co-Author), School of Natural Resources, University of Nebraska-Lincoln, Lincoln, sthomas5@unl.edu;


LeRoy Poff ( Co-Presenter/Co-Author), Colorado State University, n.poff@rams.colostate.edu;


Alexander Flecker ( Co-Presenter/Co-Author), Cornell University, Ithaca, NY, USA, asf3@cornell.edu;


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