5/25/2016  |   15:30 - 15:45   |  304-305

LETHAL AND SUBLETHAL RESPONSES OF 3 BAETID MAYFLIES EXPOSED TO TEMPERATURE EXTREMES Thermal effects on aquatic insect performance (survival, growth rate, development times, body size, fecundity) are well known. but thermal limits for performance remain poorly understood. Laboratory experiments involved whole life cycle rearing (1st instar to adult) of three baetid mayfly species in 9 different constant-temperature regimes (12-32°C). All 3 species are multivoltine, with Procloeon rivulare having a winter egg diapause while Neocloeon triangulifer and Cloeon cognatum overwinter as larvae. We observed linear responses to increased temperature between 14 and 24°C for several life history parameters (e.g., decreased development time and body size, increased growth rate), with a marked change at >24°C and <14°C. r peaked at 26°C for P. rivulare, 24°C for N. triangulifer, and 28°C for C. cognatum. Survivorship approached zero at 28-30°C for P. rivulare, 26-28°C for N. triangulifer, and 32-34°C for C. cognatum. Growth and development approached zero at 8.6°C for P. rivulare, 9.6°C for N. triangulifer, and 10.7°C for C. cognatum. Thus, life history responses to increasing temperature were relatively consistent across a 10°C range, but change at temperature extremes.

John Jackson (Primary Presenter/Author), Stroud Water Research Center, jkjackson@stroudcenter.org;


David Funk ( Co-Presenter/Co-Author), Stroud Water Research Centrer, dfunk@stoudcenter.org;


Bernard Sweeney ( Co-Presenter/Co-Author), Stroud Water Research Center, sweeney@stroudcenter.org;


Goggy Davidowitz ( Co-Presenter/Co-Author), University of Arizona, goggy@email.arizona.edu;


Charles Hawkins ( Co-Presenter/Co-Author), Utah State University, chuck.hawkins@usu.edu;


David Buchwalter ( Co-Presenter/Co-Author), North Carolina State University, david_buchwalter@ncsu.edu;


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5/25/2016  |   15:45 - 16:00   |  304-305

FLOW-POPULATION MODELS FOR TRACKING NON-STATIONARY CHANGES IN AQUATIC AND RIPARIAN ECOSYSTEMS Extreme temperature and precipitation events due to climate change are shifting the timing, frequency, and magnitude of flood and drought events, directly affecting populations of fish, aquatic invertebrates, and riparian vegetation. Climate models as drivers of hydrologic models are sophisticated in their ability to determine flow regimes at small spatial scales (<144 km2). Current population models, however, do not accommodate non-stationary effects caused by climate-forced flow regime changes. To address this, we developed a time-varying logistic r-K model for aquatic invertebrate populations, a stochastic stage-structured model for riparian vegetation, and a life-history model for fish. Model analysis identified distinct threshold boundaries, where small changes in flow regime resulted in major changes to population dynamics. These thresholds were associated with traits conferring resistance and/or resilience to extreme flow events. Models recovered field-observed community patterns, despite a lack of direct biotic competition in the model structure, suggesting that abiotic forcing by flooding and drought overrides biotic interactions under dynamic flow conditions. These results show promise for forecasting climate-induced population shifts in river ecosystems, even when biotic interactions among taxa are poorly understood.

Dave Lytle (Primary Presenter/Author), Oregon State University, lytleda@oregonstate.edu;


David Merritt ( Co-Presenter/Co-Author), USDA Forest Service, dmmerritt@fs.fed.us;


Julian Olden ( Co-Presenter/Co-Author), University of Washington, olden@uw.edu;


Jonathan Tonkin ( Co-Presenter/Co-Author), University of Canterbury, jonathan.tonkin@canterbury.ac.nz;


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5/25/2016  |   16:00 - 16:15   |  304-305

LONG-TERM EVOLUTION OF THE MACROPHYTE COMMUNITIES RELATED TO NUTRIENT DECREASE AND TEMPERATURE INCREASE IN A FRENCH LARGE RIVER Large French rivers are impacted by multiple stressors (chemical and morphological disturbance, hydrological regulation, eutrophication, climate change), which can greatly influence the evolution of the aquatic macrophyte communities. Long-term floristic and environmental surveys from 1985 to 2015 were used to analyze the temporal dynamics of the macrophyte communities on the Rhône River and identify environmental driving factors. Classification and ordination analyses show a temporal gradient in the species composition with three successive time periods and two major shifts in 1989 and 2003. Each time period is characterized by one or more indicator species as for example Ranunculus fluitans in 1985-1988, filamentous algae in 1989-2002 and invasive Elodea nuttallii in 2003-2015. The major shifts in the species composition are correlated with environmental changes such as nutrient load decrease and water temperature increase during the growing period, inducing the great expansion of invasive E. nuttallii in 2003, during a major heat wave. Our study highlights the need for long-term monitoring data to determine the temporal evolution of aquatic biotic communities related to environmental change.

Geraldine Nogaro (Primary Presenter/Author), EDF Research and Development, National Hydraulics and Environment Laboratory (LNHE), geraldine.nogaro@edf.fr;


Nina Dagens ( Co-Presenter/Co-Author), Irstea - Centre of Bordeaux, CARMA Aquatic Ecosystems and Global Change, nina.dagens@irstea.fr;


Thibaut Feret ( Co-Presenter/Co-Author), Irstea - Centre of Bordeaux, CARMA Aquatic Ecosystems and Global Change, thibaut.feret@irstea.fr;


Jean-François Fruget ( Co-Presenter/Co-Author), ARALEP - Ecologie des Eaux Douces, fruget@aralep.com;


Christian Chauvin ( Co-Presenter/Co-Author), Irstea - Centre of Bordeaux, CARMA Aquatic Ecosystems and Global Change, christian.chauvin@irstea.fr;


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5/25/2016  |   16:15 - 16:30   |  304-305

CHANGES IN LEAF AND COTTON DECOMPOSITION RATES EXPOSED TO DIFFERENT TEMPERATURES IN TROPICAL STREAM MESOCOSMS Water temperature increases can potentially affect the structure of lotic communities and consequently the responses of ecological processes they mediate. In a previous study, we observed that in high altitude streams in the tropics, decomposition rates were mostly mediated by microbial decomposers. In this study, we evaluated how experimental increases in stream water temperature affect natural microbial stream decomposers, and in turn rates of organic matter decomposition. In an experimental stream mesocosm facility located in the Napo Basin (Ecuador), we placed cotton strips and leaf discs of Andean Alder (Alnus acuminata) in 60 mesocosmos tanks exposed to different temperature treatments: 1) ambient stream temperatures (8.8 ± 1.4C), 2) increase of +2.5C, and 3) increase of +5C. Organic discs were recovered after 3, 7, 14 and 21 days to estimate litter decay rates. Preliminary data suggest that decomposition rates were faster in the +2.5C treatment. In contrast, the +5C treatment showed a decrease in the processing rates. Microbial biomass and richness remains to be analyzed; however, we expect a strong correspondence between the microbial composition and their decomposition rates.

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


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


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


Manuel Graça ( Co-Presenter/Co-Author), MARE, University of Coimbra, Portugal , mgraca@ci.uc.pt;


Cristina Salgado ( Co-Presenter/Co-Author), MARE, Dept. Life Sciences, Faculty of Science and Technology, University of Coimbra, Portugal , cris_salgadomg@yahoo.com;


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


Steven Thomas ( Co-Presenter/Co-Author), University of Alabama, sathomas16@ua.edu;


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


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5/25/2016  |   16:30 - 16:45   |  304-305

THE EFFECT OF WHOLE STREAM WARMING ON ITS INSECT EMERGENCE A cold stream (IS7) in Hengill volcano 20 km east of Reykjavík was heated up by leading the stream water through a pipe into a heat exchanger in a nearby warm stream (IS8) and back to the lower reaches of the original stream. Emergence traps were placed in the unheated (7-10°C) and heated reaches (10-18°C) of the stream and in a warm stream (IS8) (19-22°C). This lead to a significant increase in total number of insects emerging from the heated stream. Of the total number of insects, Chironomidae were proportionally more numerous in the unheated reach compared with the heated reach, but blackflies and the predatory Limnophora riparia were both totally and proportionally more numerous in the heated reach. The fauna of the heated reach became more similar to the warm stream IS8. Warming up natural stream water by 3-8°C, a temperature increase expected at high latitudes in the next century, will result in increased density of aquatic insects and increased density of predatory insects, longer food chains and thus the height of the trophic network as a whole.

Gisli Mar Gislason (Primary Presenter/Author), University of Iceland, gmg@hi.is;


Aron Dalin Jonasson ( Co-Presenter/Co-Author), University of Iceland, adj11@hi.is;


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5/25/2016  |   16:45 - 17:00   |  304-305

PREDICTING HOW SHIFTS IN CADDISFLY DISTRIBUTIONS ALONG HYDROPERIOD AND ELEVATIONAL GRADIENTS AFFECT ECOSYSTEM PROCESSES IN SHALLOW HIGH-ELEVATION PONDS Shifts in species distributions along local and regional gradients are perhaps the most frequently reported impact of climate change, yet we often know little about how the resulting new combinations of species affect ecosystem function. We have observed range shifts among species of detritivorous limnephilid caddisflies in high-elevation ponds where changes in snow pack, melt dates, and summer temperature and precipitation are affecting whether and when ponds dry. In microcosm experiments, we found species-specific rates of detritus processing and nutrient (N & P) release. We used these data to parameterize linear models that predict how substitutive and additive changes in community composition will affect the total amount of detritus processed and nutrients released into the water column. Our models predict that the particular combination of resident and invading species will determine whether shifts in species distributions will increase, decrease, or not change the overall rates of ecosystem processes. Our predictions provide the basis for designing future experiments in which we experimentally manipulate combinations of resident and invading species in natural habitats.

Scott Wissinger (Primary Presenter/Author), Allegheny College, swissing@allegheny.edu;


Susan Washko ( Co-Presenter/Co-Author), Allegheny College, washkos@allegheny.edu;


Jared Balik ( Co-Presenter/Co-Author), Allegheny College, balikj@allegheny.edu;


Brad Taylor ( Co-Presenter/Co-Author), North Carolina State University Dept. of Applied Ecology; Rocky Mountain Biological Laboratory, bwtaylo3@ncsu.edu ;


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


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