Special Sessions

S01: Global Spread and Broad to Local Impacts of Suspension-Feeding Bivalves

Organizers: Henry A. Vanderploeg, Great Lakes Environmental Research Lab, NOAA, henry.vanderploeg@noaa.gov and Thomas F. Nalepa, Great Lakes Environmental Research Lab, NOAA, thomas.nalepa@noaa.gov

Recently there has been a massive expansion in the range of freshwater bivalves. For instance, Dreissena has spread from the Ponto-Caspian region into Europe and North America, and Limnoperna has spread from Asia into South America. In the wake of these expansions there have been extensive changes in ecosystem structure and function, with most biological components being affected either directly or indirectly. These changes have occurred at different rates and have often been unpredictable. Since range expansions are far from over, it is paramount to explore impacts on different scales to better understand and predict overall ecological consequences. In addition, while impacts are often negative in invaded systems, bivalves, either native or non-indigenous, are being introduced or reintroduced into lakes, rivers, estuaries, and coastal regions to improve water quality or restore ecosystem function. This special session seeks to bring together experts to look at the big or global picture on the important role that bivalves play in ecosystems to better define interactions between bivalves and ecosystems at the local level, and to define possible consequences of their continued spread.

S03: Hydrology, Geomorphology, and Ecology of Tidal Freshwater Zones, or What Happens in Rivers When Water Flows Upstream?

Organizers: Scott H. Ensign, University of North Carolina at Chapel Hill, ensign@e-mail.unc.edu and Scott C. Neubauer, University of South Carolina, scott@belle.baruch.sc.edu

At the interface between rivers and estuaries, tidal freshwater zones are a poorly understood portion of the hydrologic continuum. These areas are common along low-gradient coastal plains worldwide, often contain extensive fringing tidal wetlands, and represent the final link between river networks and coastal environments. Diurnal fluctuation of water level, flow direction, and discharge affect biogeochemical transformations, biological productivity, and ecological interactions. The resulting ecosystems are dramatically different from non-tidal rivers and brackish/saline estuarine waters. At decadal time scales, sea level rise is advancing the extent of tidal influence inland and transforming non-tidal rivers into tidal ones. Investigation of how these systems develop, evolve, and function provides many opportunities for collaboration between estuarine and fluvial ecologists. This session explores all aspects of tidal freshwater zones, but will emphasize hydrology, geomorphology, and ecosystem ecology as unifying frameworks on which to build process-based knowledge of these unique environments.

S04: Considerations of Climate Change Effects on Biological Indicators in Aquatic Ecosystems

Organizers: Michael Barbour, Tetra Tech, Inc., michael.barbour@tetratech.com; Britta Bierwagen, US Environmental Protection Agency, bierwagen.britta@epa.gov; Anna Hamilton, Tetra Tech, Inc., anna.hamilton@tetratech.com and Nicholas Aumen, Loxahatchee National Wildlife Refuge, Nick_Aumen@nps.gov

This session will focus on the effects of climate change on the biological communities of aquatic ecosystems and the indicators used to assess their condition. Understanding these effects will allow a better assessment of trends in the condition of aquatic resources and will provide scientific support for protecting and restoring surface waters. An international representation of presenters from both ASLO and NABS will highlight aspects of the session theme through their research in all aquatic systems and from around the globe.

S05: Climate Change, Overgrazing, and Gold Mining: The Nexus of Environmental Stressors and Conservation of Mongolia’s Freshwater Ecosystems

Organizers: Barbara Hayford, Department of Life Sciences, Wayne State College, bahayfo1@wsc.edu and Sudeep Chandra, Dept. of Natural Resources and Environmental Science, University of Nevada, sudeep@cabnr.unr.edu

Mongolia is often thought of as a land of deserts and steppes, but it is also a land of ancient lakes, large rivers, alpine streams, and cold springs. Freshwater systems in desert lands, dryland steppes, and taiga forests provide valuable ecosystem services in the form of drinking water for humans and Mongolia’s domesticated herds. However, Mongolia’s freshwater ecosystems are at risk from climate change, overgrazing, and gold mining. Research on climate change, basic freshwater ecology, biodiversity, conservation, and volunteer stream monitoring efforts are mounting in Mongolia. This special session brings together limnologists, volunteer coordinators, taxonomists, and landscape ecologists to better understand the role of climate change and other environmental stressors in freshwater ecology in Mongolia and to formulate models to conserve freshwater habitat. Speakers will present results on basic limnological research of ancient Lake Hovsgol, impacts of grazing, permafrost disruption, and global warming on Mongolian landscapes and the streams which drain them, biological stream assessment, and volunteer monitoring of streams under stress from gold mining. Speakers will also discuss Mongolia’s unique species, ranging from diatoms and invertebrates to the world’s largest salmonid fish, the Taimen.

S06: A Synthesis of Freshwater Ecosystem Metabolism: Gross Primary Production, Community Respiration, and Net Ecosystem Production in Streams, Rivers, and Lakes

Organizers: Denise A. Bruesewitz, University of Waikato, Department of Biological Sciences (New Zealand), dbruesew@waikato.ac.nz; David Richardson, Cary Institute of Ecosystem Studies, richardsond@caryinstitute.org and Chris Solomon, University of Wisconsin Center for Limnology, ctsolomon@wisc.edu

Measurements of ecosystem metabolism, such as gross primary production, community respiration, and net ecosystem production, are valuable integrators of ecosystem function in freshwater habitats. These measurements are capable of incorporating variation that stems from trophic status, organic matter inputs, catchment land use, geographic variation, food web structure, and other ecosystem characteristics. Consequently, ecosystem metabolism is routinely measured in systems ranging from small urban streams to Artic lakes. Comparison of studies from these diverse environments could provide new insights into freshwater ecosystem function. This session will focus on integrating ecosystem metabolism research from stream, river, and lake ecosystems. While the measurement of metabolism brings forth unique challenges in each ecosystem, advances in environmental sensor and remote sensing technology have facilitated calculation of ecosystem metabolism and associated metrics at both a broader spatial range of sites and at a finer, more frequent temporal scale. A discussion of trends across freshwater ecosystem types may result in improved understanding across the diversity of systems being studied. We hope to identify common controls of metabolism as well as sources of spatial and temporal variability that span freshwater ecosystems. Submissions based on both traditional and novel models for calculating metabolism are encouraged.

S07: Ecosystem Modeling From the Center to the Edges: Classic and Novel Approaches for Addressing Increasingly Complex Problems

Organizers: Mark J. Brush, Virginia Institute of Marine Science, brush@vims.edu and Lora Harris, University of Maryland Center for Environmental Science, harris@cbl.umces.edu

Ecosystem models have become major research tools across the aquatic sciences, both for heuristic understanding and management application. These two goals bring with them different requirements and thresholds for complexity, uncertainty, and need for quantitative validation, which has resulted in a wide variety of novel modeling methods and statistical approaches for model validation. As we continue to push towards increasingly relevant models for informing management, the modeling community will need to consider the trade-offs between complexity, realism, and generality, as well as develop models for the ever-increasingly complex problems of the day, including combined responses to nutrient loading and climate change, consideration of alternative stable states and recovery thresholds, and linkage of models from nutrients through fish. This session seeks to explore the state-of-the-art in addressing these complex issues through modeling. We seek submissions that illustrate new and innovative modeling techniques, methods of model validation, and case studies of the application of models to inform management and address the impacts of multiple stressors. Given the unique opportunity offered by this joint ASLO/NABS meeting and the increasing calls for holistic, ecosystem-based management, we especially seek presentations that explore methods for coupling traditional water quality and biogeochemical models to higher trophic levels.

S08: CombineD with S35
S09: Didymosphenia Geminata—Environmental Impacts, Limiting Factors, and Prospects for Control

Organizers: Scott Larned, National Institute of Water and Atmospheric Research, s.larned@niwa.co.nz and Max Bothwell, Environment Canada, Pacific Biological Station, info@5thsticehousewaco.com

The mat-forming diatom Didymosphenia geminata (didymo) has proliferated in many rivers, both within and outside of its presumed native range. These proliferations may lead to alterations in aquatic communities, ecosystem processes, hydrodynamic conditions and water quality. There is widespread concern that the frequency of new introductions and proliferations is outpacing our understanding of the ecological impacts of didymo and our ability to control its spread. In the face of this concern, didymo research is expanding rapidly. Much of the initial research focused on chronologies and geographic patterns of invasion. Current research includes environmental impacts, physical and biological factors that limit growth and accumulation, and potential tools for controlling or preventing proliferation. This session will provide a forum for scientists and river managers. We invite presentations on diverse aspects of didymo biology and management, including its effects on organisms and habitats, limiting factors, and the search for safe and effective controls.

S10: Foundation Species and Terrestrial-Aquatic Linkages: Effects of Shifting Tree Species Composition at the Aquatic-Riparian Interface

Organizers: John Kominoski, University of British Columbia, jkominoski@gmail.com and Jennifer Follstad Shah, Duke University, jfs12@duke.edu

Foundation species are abundant primary producers that provide fundamental structural support for other species within ecosystems. Across landscapes, tree species compositions in riparian forests are being altered by environmental changes (land-use and climate change), pests, and pathogens. As aquatic and riparian ecosystems rely on reciprocal energy and nutrient transfer, shifts in tree species composition may alter the structure and functioning of these coupled ecosystems. The processing of allochthonous resources at the aquatic-riparian interface has been extensively studied, but we lack a firm understanding of the role of foundation species, relative to other species in the forest community, in maintaining aquatic-riparian structure and functioning. We propose a special session that will bring together aquatic and riparian ecologists to address patterns and processes related to current and predicted declines in foundation species and/or shifts in riparian forest species composition. We will highlight current global trends and make predictions of future aquatic-riparian dynamics given regional climate change projections. We will also address the following questions: How are the spatial demographics and dynamics of riparian foundation species altering interactions between riparian forest and aquatic ecosystems? What are the functional roles of foundation species relative to other tree species within coupled aquatic-riparian ecosystems?

S12: River Research: Populations to Ecosystems

Organizers: Thomas Hein, University of Natural Resources and Applied Life Sciences, thomas.hein@boku.ac.at and Michael Delong, Winona State University, mdelong@winona.edu

River studies have expanded greatly over the last decade, addressing questions of interest to a broad range of scientists. This session will encourage presentations on the most recent developments in our understanding of river systems. Topics can cover studies of the population ecology of taxa, community interactions, the influence of biotic and abiotic factors on community structure, productivity, trophic dynamics, and nutrient cycling. Of particular interest are papers that address broader questions in aquatic science. Presenters will be invited to submit a manuscript for a special issue in the new journal River Systems.

S13: 50 Years of Global Limnology: The Ongoing Legacy of Charles R. Goldman

Organizers: John C. Priscu, Montana State University, jpriscu@montana.edu; James Elser, Arizona State University, j.elser@asu.edu and Carol Folt, Dartmouth College, carol.l.folt@dartmouth.edu

Charles Goldman has been a seminal figure in the field of limnology. He is perhaps best known for his work on micronutrient limitation in lakes and his long-term research on Castle Lake and Lake Tahoe. In addition to these long term studies, he has sampled lakes on every continent and was one of the first limnologists to conduct detailed studies on Arctic and Antarctic systems. Besides his scholarly research endeavors, he found time to serve as president of ASLO during the mid-1960s. During his 50-plus-year career, he has mentored more than 300 graduate students, the first being the late Robert Wetzel. These students carry on the Goldman tradition of aquatic research, and many have gone on to establish distinguished careers of their own. This symposium will include scientists who worked side-by-side with Goldman early in his career and students whose research today reflects their tenure in the Goldman research group.

S14: When Rivers Run Dry: Temporary Streams as Coupled Aquatic-Terrestrial Ecosystems

Organizers: Thibault Datry, Cemagref Lyon, thibault.datry@cemagref.fr; Vicenç Acuña, University of Girona, Spain, vicenc.acuna@icra.cat; Sergi Sabater, University of Girona, ICRA, Spain, sergi.sabater@udg.edu; Klement Tockner, IGB, Germany, tockner@igb-berlin.de and Cliff Dahm, CALFED Bay-Delta Program, Sacramento, California, Cliff.Dahm@Calwater.ca.gov

Temporary streams and rivers are among the most common freshwater ecosystems, and their proportion is predicted to rapidly increase in the near future due to global change. Temporary streams are alternating aquatic and terrestrial ecosystems that are functionally linked. Of particular importance are the distinct transition periods between the aquatic and terrestrial phases. These “temporary ecotones” may shape the biogeochemistry and biodiversity of entire stream networks for periods that extend far beyond the transition periods. Current knowledge about the effects of intermittency is fragmentary, and no clear framework exists about the temporal and spatial scales at which intermittency is a relevant phenomenon. This special session aims to bring together scientists from different biomes, working at different scales, and focusing on the hydrogeomorphic, ecologic, and evolutionary consequences of drying rivers.

S15: Linking Microbial Enzymes to Ecosystem Processes in Aquatic Ecosystems

Organizers: Kevin Simon, University of Maine, ksimon@maine.edu, Bob Sinsabaugh, University of New Mexico, rlsinsab@unm.edu and Stuart Findlay, Cary Institute of Ecosystem Studies, findlays@caryinstitute.org

Mineralization of organic matter by heterotrophic micro-organisms creates the trophic base for detritus food webs, drives global carbon and nutrient cycles, and mediates plant production and atmospheric composition. The proximate agents of organic matter decomposition are extracellular enzymes that deconstruct plant and microbial cell walls, depolymerize macromolecules, and ultimately produce soluble substrates for microbial assimilation. At the organismal scale, expression of these activities is controlled by environmental signals linked to substrate availability and population density. At large scales, activities track biogeochemical trends linked to climate and other variables. This session will include papers that use enzymatic approaches to investigate ecological processes on molecular to ecosystem scales. Topics of interest include environmental control of extracellular enzyme activity, enzyme stoichiometry, and enzyme activities in relation to community composition, ecosystem metabolism, and biogeochemical cycles.

S16: Limnology and Oceanography: Fluids and Environments – Celebrating Interdisciplinary Research in Aquatic Science Driven by Fluid Dynamic Interactions

Organizer: Joe Ackerman, University of Guelph, ackerman@uoguelph.ca

The physical properties of water, saturated sediments and fractured rock as interactive transport media for diverse aquatic systems and their processes have become a central driver for many interdisciplinary studies. Such studies have addressed issues ranging from geochemical transport and reaction in surface and ground water and in sediments, hyporheic zones and fractured oceanic crusts, to the influence of turbulence on plankton dynamics and larval dispersal, to mass transport relationships to benthic organism in coastal, littoral and wetland habitats. This special session will celebrate the launch of ASLO’s new journal, Limnology & Oceanography: Fluids and Environments, which will publish interdisciplinary limnology and oceanography research wherein advection and/or diffusion or the mechanics of the media drive biological, chemical, and geological processes from molecular to system scales. Topics of interest for this special session include any and all interactions of fluid, sediment, or rock dynamics with aquatic biology, chemistry, ecology, geology, and physics in lake, stream, river, groundwater, estuarine, marine and ocean systems.

S17: Aquatic Ecosystems: Tribal Advances and Perspectives

Organizers: Scott Bulgrin, Pueblo of Sandia Environment Department, sbulgrin@sandiapueblo.nsn.us; Jim Snitgen, Oneida Tribe of Indians of Wisconsin, jsnitgen@oneidanation.org; Dan Mosley, Pyramid Lake Paiute Tribe, dmosley@plpt.nsn.us and Stephanie Ogren, Little River Band of Ottawa Indians, sogren@lrboi.com

This special session (symposium) will highlight various tribal nations and their advances, efforts, and perspectives on protecting and sustaining their aquatic ecosystems. Topics could include water quality standards, biological monitoring, wetlands and ecosystem restoration, as well as tribal perspectives on aquatic ecosystems and what they mean to their culture. This session will offer an opportunity for tribes and pueblos to discuss their water programs and, for those not familiar with how tribal nations manage their water resources, to learn and to share information. An information exchange format is envisioned.

S18: Plankton Ecology of Large Rivers

Organizers: Andrew F. Casper, Waterways Experiment Station, US Army Corps of Engineers, andrew.f.casper@usace.army.mil and Tamara Sluss, Kentucky State University, tamara.sluss@kysu.edu

The understanding of the structure and function of plankton in large rivers has increased dramatically in the past 20 years. An analysis of the ISI Web of Science database shows that the number of river plankton publications has risen from fewer than 10 per year in the early 1990s to 30 per year since 2004. In addition to this steadily rising level of interest and inquiry, these works also show that plankton studies have grown to encompass microbial, invertebrate, and larval fish classes, meaning that important contributions have come from a diversity of perspectives. The objectives of this session are to provide a venue for river ecologists to present theoretical, observational, and experimental data on topics that could range from spatial/temporal dynamics and structural and functional roles, to abiotic and biotic interactions. Attendees of this session should expect to gain insights from many taxa and hierarchical levels (i.e. individuals to landscape). In every case the riverine environment will serve as the context and unifying theme for posters and oral presentations.

S20: Recent Breakthroughs in Stream Solute Studies: Identifying New Methods, Applications, and Limitations for Tracing Ecosystem and Catchment Processes

Organizers: Adam S. Ward, Penn State University, asw178@psu.edu; Steven M. Wondzell, U.S. Forest Service, swondzell@fs.fed.us; Jay P. Zarnetske, Oregon State University, zarnetsj@geo.oregonstate.edu and Robert O. Hall, Jr., University of Wyoming, bhall@uwyo.edu

Stream solute studies are a widely used technique, providing integrated assessment of physical, chemical, and biological processes affecting solute transport. A range of spatially and temporally variable processes are integrated in downstream measurements, complicating modeling and interpretation of results. This session will focus on novel applications and modeling strategies, interpretation of observations, and limitations of the technique. Furthermore, this session seeks to recognize the 20-year anniversary of the “Concepts and methods for assessing solute dynamics in stream ecosystems” publication (Stream Solute Workshop, JNABS, 1990), and will serve as a review of progress made in the past 20 years of stream solute research. Invited authors will provide perspective on progress since the 1990 publication, and discuss future prospects for evaluation of ecosystem and catchment processes using stream tracer studies. Presentations and posters highlighting evolution in methodology or literature analyses are also welcomed.

S22: Linking Simplicity and Complexity in Lakes and Ponds: A Tribute to Stanley Dodson

Organizers: John Havel, Missouri State University, JohnHavel@MissouriState.edu; Charles Ramcharan, Laurentian University, cramcharan@laurentian.ca and Howard Riessen, SUNY College at Buffalo, riessehp@buffalostate.edu

Stanley Dodson’s contributions to limnology and ecology spanned a wide variety of topics and ideas, mostly focused on the plankton communities of lakes and ponds. Among these were the first pioneering studies on the influence of size-selective predation, early investigations on inducible antipredator defenses, analyses of the factors influencing species richness in lakes, impacts of contaminants on lake communities, and detailed studies on the systematics of cladocerans and copepods. Stanley had a knack for finding the important questions in modern limnology and designing simple experiments as critical tests. He was drawn to the beauty of small things and simple ideas that had big effects. In his honor we would like to encourage contributions to this special session that showcase some good examples of Stanley’s vision and interests. While we welcome contributions from all areas of freshwater ecology in which Stanley was an active participant, we are especially interested in addressing the major ecological ideas to which he devoted his career.

S24: Linking Environmental Change, Community Change, and Ecosystem Function in Streams

Organizers: Caryn Vaughn, University of Oklahoma, cvaughn@ou.edu; Keith Gido, Kansas State University, kgido@ksu.edu and Daniel Spooner, Trent University, dspooner45@gmail.com

Globally, freshwaters are experiencing biodiversity declines greater than those in marine or terrestrial systems, yet predicting how such biodiversity declines will alter ecosystem function is uncertain. The influence of organisms on ecosystem function varies along both natural (e.g. climatic, productivity) and anthropogenic (e.g. agricultural, urbanization) environmental gradients and with community composition (species traits, species dominance, species interactions, food web linkages). Thus, predicting ecosystem function requires understanding the complex interactions between communities and the environment underlying ecosystem function. Our proposed session will bring together researchers who are addressing how environmental change and community change interact to influence ecosystem function across a wide variety of aquatic systems and with diverse approaches. For example, potential participants are studying how environmental drivers such as climate change, disturbance intensity and frequency, urbanization, impoundments, water management and agriculture are shifting community structure and ecosystem function. By organizing presentations by researchers with examples from a variety of systems, we hope to highlight novel approaches for investigating these problems and to evaluate emergent patterns of ecosystem responses to environmental changes.

S25: Advances in Limnology: A Tribute to W. John O’Brien

Organizers: Anne E. Hershey, University of North Carolina at Greensboro, aehershe@uncg.edu; Chris Luecke, Utah State University, chris.luecke@gmail.com and Val H. Smith, University of Kansas, vsmith@ku.edu

This session will be a tribute to the career contributions of W. John O’Brien, who passed away in August 2009. Although best known as a zooplankton ecologist, John’s research interests were much broader, including fish-feeding behavior, the evolution of anti-predator defenses, phototoxicity, reservoir limnology, and landscape control of planktonic communities. We welcome all contributions which reflect his interests.

S26: Ecosystem Size: A Fundamental Driver of Processes in Freshwaters

Organizers: Angus McIntosh, University of Canterbury, angus.mcintosh@canterbury.ac.nz; Ross Thompson, School of Biological Sciences and Australian Centre for Biodiversity, Monas, ross.thompson@sci.monash.edu.au and Pete McHugh, School of Biological Sciences, Canterbury Univ., Christchurch, New Zealand, pete.mchugh@canterbury.ac.nz

Ecologists have long recognized an over-riding influence of habitat or ecosystem size on the structure and function of biological communities and whole ecosystems. One of the earliest quantitative generalizations made in ecology, for instance, involved the demonstration of positive species richness–area relationships for island environments. Recent research has documented linkages between the size of freshwater ecosystems and a range of biological traits, like food web structure and stability, the importance of cross-ecosystem subsidies, and the cycling of nutrients. It is also a dynamic feature of aquatic ecosystems, varying seasonally or on longer time scales. Moreover, size is arguably the most imperiled attribute of the Earth’s freshwater environments, as stream, lake, and wetland hydrology are increasingly altered to meet human demands, and global climate change impinges on hydrological cycles. Thus, improved knowledge of how the size of freshwater ecosystems affects biological communities will be central to advancing ecological understanding and the management of these systems. This session will be centered on understanding the influence of ecosystem size on ecological processes in freshwater systems. Given the integrated nature of the 2010 meeting, this session will serve as a platform for communicating new research findings and a much-needed opportunity to link research from lotic and lentic environments. In addition to talks intended to set a broad conceptual framework, we encourage presenters speaking (or sharing a poster) on work occurring on a variety of levels of ecological organization and based on different approaches. We anticipate that this ecosystem size-related session will integrate across ecological (e.g., modelling, food-web ecology, biogeochemistry) and physical (e.g., geomorphology) sub-disciplines. Further, by joining work that is traditionally separated by ecosystem type or approach, we will help pave a path towards new, and broadly applicable, size-based conceptual models of aquatic ecosystem structure and function. We expect these to be particularly important in guiding the future use, conservation, and restoration of freshwaters.

S27: Fish and Fisheries in an Ecosystem Context: A Celebration of the Career of J.F. Kitchell

Organizers: Daniel Schindler, University of Washington, Seattle, deschind@u.washington.edu; Chris Harvey, NOAA Fisheries, Seattle, Washington, chris.harvey@noaa.gov and Tim Essington, University of Washington, Seattle, essing@uw.edu

A hallmark of modern ecology is the realization that fishes are critical structuring components of aquatic ecosystems. Fishes, through their support of fisheries and their inherent biodiversity value are one of the main reasons society places high value on healthy aquatic ecosystems. In addition to the attention they attract from people, fishes are also key determinants of aquatic ecosystem structure. Their behavior, energetics, and trophic ecology have significant effects on community structure, ecosystem productivity, and nutrient cycling in lotic-, lentic-, and many marine ecosystems. Scientific study of fishes as components of aquatic ecosystems has required that ecologists develop new approaches for dealing with these wide-ranging and notoriously difficult-to-sample organisms. Development of bioenergetics and ecosystem models, ecosystem experiments, and management experiments involving people have become the scientific standard for understanding the ecology of fishes in an ecosystem context. J.F. Kitchell developed many of the key insights that have enabled fish ecology to become an integrated dimension of aquatic ecosystem ecology. This symposium will highlight state-of-the-art science focused on understanding fish and fisheries ecology in an ecosystem context.

S28: Stream Network Connections: Quantifying Hydrological, Chemical and Biological Linkages

Organizers: Joe Ebersole, US Environmental Protection Agency, ebersole.joe@epa.gov; Parker J. Wigington, Jr., US Environmental Protection Agency, wigington.jim@epa.gov and Ken Fritz, US Environmental Protection Agency, Fritz.ken@epa.gov

Most research focusing on stream-watershed connections has been accomplished at small scales (10^2 m), yet decision makers need information on ecosystem processes operating at watershed scales. Linking specific actions or processes within watersheds to physio-chemical or biological conditions far downstream remains a vexing challenge for watershed science. Recent U.S. Supreme Court rulings on the scope of jurisdictional waters protected under the Clean Water Act highlight the need to better understand connections between headwater streams and downstream receiving waters. This symposium will address the need to better understand the function of entire stream networks. The symposium objectives are: 1. Review and develop physical and biological concepts for understanding linkages within stream networks – from headwaters to estuaries; 2. Highlight innovative research approaches illustrating hydrological, chemical or biological connectivity within stream networks at watershed scale; and 3. Develop and expand whole-network approaches for characterizing, modeling, and predicting stream network behavior. Through case studies, applications of new technologies, and modeling approaches, this symposium will provide an opportunity to share and synthesize information on whole-network research. Participants will acquire new information that will encourage novel research approaches, and stimulate additional synthesis and tool development for quantifying hydrological, chemical and biological linkages within stream networks.

S32: Emerging Science From Aquatic Sensor Networks

Organizers: Paul Hanson, Center for Limnology, University of Wisconsin-Madison, pchanson@wisc.edu and Cayelan Carey, Department of Ecology and Evolutionary Biology, Cornell University, ccc99@cornell.edu

The recent development of environmental sensor networks offers unprecedented opportunities to advance our understanding of aquatic ecosystems. High-frequency data collected across expanded temporal and spatial scales provide a new frontier for examining ecosystem dynamics, and advances in sensor technology are revealing previously unobservable phenomena. Simultaneously, collaborations between limnologists and scientists from other disciplines are stimulating innovative hypotheses and analytical approaches. The role of aquatic sensor networks will become increasingly important in future research, as lakes are sensitive indicators of land use and climate change. The aim of this session is to highlight innovative science facilitated by the use of remotely-deployed aquatic sensors. We encourage participation by scientists utilizing these tools to present their findings from single systems, as well as analyses from networks of sensored systems, in an oral session. In particular, we will highlight discoveries and active research from the Global Lake Ecological Observatory Network (www.gleon.org), an international grassroots network of limnologists, ecologists, information technology experts, and engineers who have a common goal of building a scalable, persistent network of lake ecology observatories.

S33: Sources, Transport, and Cycling of Nutrients in Aquatic Ecosystems

Organizers: Rebecca T. Barnes, U.S. Geological Survey, becca.barnes@gmail.com and Elizabeth W. Boyer, Penn State University, ewb100@psu.edu

Anthropogenic and natural sources of dissolved and particulate nutrients have a profound impact on ecosystems and water quality. Spatial and temporal variations in nutrient loading can influence local water clarity, oxygen levels, community composition, trophic interactions, and contaminant bioaccumulation pathways within food webs. Groundwater contamination and coastal eutrophication are two negative consequences of nutrient pollution. We seek presentations aimed at a fundamental understanding of sources, transport, and transformations of nutrients in aquatic environments. We are particularly interested in highlighting work aimed at tracking sources of nutrients with hydrological, biogeochemical, or isotopic tracers, and field or modeling studies that emphasize the coupled nature of hydrological and biogeochemical processes in watersheds. All aquatic environments are of interest, including wetlands, groundwater, rivers, lakes, streams, and estuaries.

S34: Biological, Dcological and Ecotoxicological Traits – Current Developments and Future Directions

Organizers: Mikhail A. Beketov, UFZ - Helmholtz Centre for Environmental Research, Germany, mikhail.beketov@ufz.de; Russell Rader, Brigham Young University, russell_rader@byu.edu and Philippe Usseglio-Polatera, University Paul Verlaine - Metz, France, usseglio@univ-metz.fr

Biological, ecological and ecotoxicological traits are an important part of both applied and basic ecological studies. In freshwater biological assessment, the use of traits has provided a wide range of tools, multimetric indices and innovative approaches allowing for separation of different stressors, large-scale cross-regional assessments and comparisons or function-related measurements. However, despite considerable progress, the full potential of trait-based approaches remains to be understood. The present special session will aim at presenting the current state of the art and defining possible future directions in the trait-focused investigations in both applied (e.g. bioassessment, modeling) and basic (e.g. relation of traits and phylogeny) freshwater ecology.

S35: Greenhouse Gas Emissions from Natural Freshwater Systems and Reservoirs

Organizers: Alain Tremblay, Hydro-Quebec, tremblay.alain@hydro.qc.ca; Paul del Giorgio, University of Quebec at Montreal, del_giorgio.paul@uqam.ca and Yves Prairie, University of Quebec at Montreal, prairie_yves@uqam.ca

Carbon dioxide and methane are the world’s main greenhouse gases (GHG), and have been the focus of intense research for decades now. There is no question that oceans play a key role in global gas exchange, but there is mounting evidence that continental waters may play a role in global GHG dynamics that is largely disproportional to their relative small areal coverage, and yet we still lack basic information to effectively incorporate these systems into global GHG models. Under current scenarios of rapid climate change and landscape alteration, and with increasing global energy demand and the demand for cleaner energy sources, the need to better understand the fundamental processes involved in the cycling of greenhouse gases in natural ecosystems (both terrestrial and aquatic) becomes more pressing. The objective of this session is to discuss the most recent advances in our understanding of the magnitude, regulation and biogeochemical implications of GHG emissions (CO2 and CH4) from both natural freshwater aquatic systems and hydroelectric reservoirs. We encourage presentations that attempt to place these emissions in the context of regional biogeochemical cycles and of the regional C budgets, and of global climate change.

S37: Intra- and Intercontinental Experiences of Interaction Between Aquatic Sciences and Management: Learning From Others

Organizers: Eugènia Martí, Centre d’Estudis Avançats de Blanes (CSIC), eugenia@ceab.csic.es; Piet Verdonschot, Alterra, Piet.Verdonschot@wur.nl and Isabel Pardo-Gamundi, University of Vigo, ipardo@uvigo.es

This session is organized by the NABS International Profile Committee and aims at providing an overview of studies on transfer of aquatic science to water management and policies; and vice versa, on how legislation and directives influence aquatic ecology science, both across different continents. The objective is to examine synergies among different approaches and to learn from successful and unsuccessful experiences and existing tools across different geographic domains and socio-political systems. Europe developed the Water Framework Directive (2000), which resulted in a Europe-wide assessment evaluation; and the Habitat and Bird Directives (1992), which were the foundation of a European ecological network of natural areas, including many freshwater ecosystems. The USA developed the Clean Water Act in the seventies, eventually resulting in the Biological Condition Gradient approach; and the Nature Conservation Act in 1992. Australia developed its National River Health Program (1994) as a response to the growing concern for maintaining ecological values. Similar experiences are currently being developed in many other regions. Altogether this legislation has triggered a large scientific response, and concurrently, science has contributed to develop and improve directives and legislation. The session will include speakers from different countries and welcomes contributed talks and posters.

S38: Submarine Groundwater Discharge – From Watershed to Coast: Climate, Land-Use, Geohydrology and Marine Biogeochemical Impacts

Organizers: Craig Glenn, University of Hawaii, glenn@soest.hawaii.edu, Henrieta Dulaiova; University of Hawaii, hdulaiov@hawaii.edu; Richard Peterson, Coastal Carolina University, rpeters2@coastal.edu and Thomas Stieglitz, European Institute of Marine Studies (IUEM)/Université de Bretagne, Occidentale, Laboratoire de Sciences de l'Environnement Marin (LEMAR), Plouzané, France, thomas.stieglitz@jcu.edu.au

Submarine groundwater discharge (SGD) is now recognized as a significant source of nutrients, organic and inorganic pollutants, trace metals and other compounds of biogeochemical importance to the coastal ocean. Yet the impact of this process worldwide is still largely unknown. New advances of technology have allowed application of groundwater discharge studies in diverse systems, including rivers, lakes, and wetlands as well as new and revisited coastal ocean sites. Such studies are vitally important now to establish baseline characteristics of current SGD behavior and its implications before we can anticipate future effects of climate change, sea level rise, and population increase. This session will include a consortium of presentations (both oral and poster) on 1) upstream processes that influence SGD from the land, such as watershed approaches that examine natural and anthropogenic controls on groundwater recharge, transport and composition, including climate, hydrogeology and land use; 2) measurement and modeling of SGD that reveal its spatial and temporal variability, as well as biogeochemical processes within the subterranean estuary; and 3) downstream coastal effects of SGD, including its influence on coastal and marine biological processes, chemical budgets of elements, contaminant fates, and coastal zone management.

S39: Health Checkup for the Rio Grande and the Silvery Minnow

Organizers: Diana M. Papoulias, U.S. Geological Survey, Columbia Environmental Research Center, dpapoulias@usgs.gov and Kevin Buhl, U.S. Geological Survey, Columbia Environmental Research Center, kbuhl@usgs.gov

The silvery minnow is listed as endangered. Despite recovery efforts, the future for this fish is precarious in the highly impacted Rio Grande. Threats include habitat fragmentation, dewatering, poor water quality, and invasive species. The minnow is easily reared in captivity, thus an important aspect of the recovery plan includes a stocking program. For this program to succeed, that is, for naturally reproducing populations to persist in the Rio Grande, individuals must be healthy enough to grow and reproduce. This symposium would bring together those scientists that have studied the physico-chemical condition of the river water with those who have studied the health of the silvery minnow. It will provide a forum for recent data that has come from studies conducted during the last three years by the state of New Mexico and the USFWS on health assessments of fish in the Rio Grande including the silvery minnow and contemporary water quality data. Ideally, presenters would provide attendees with a view of 1) what physico-chemical water quality conditions are necessary for the silvery minnow, 2) the current conditions and how these conditions contribute to the observed health of the fish, and 3) the consequences of future climate and land use changes on silvery minnow health.

S40: Implementation of Statistically-based Monitoring Designs for Water Management Decision-Making at Multiple Scales

Organizers: Sarah Lehmann, US Environmental Protection Agency, lehmann.sarah@epa.gov; Treda Grayson, US Environmental Protection Agency, grayson.treda@epa.gov and Ellen Tarquinio, US Environmental Protection Agency, tarquinio.ellen@epa.gov

States, tribes, federal agencies and other organizations monitor our nation’s waters to address a variety of issues. The data they collect address many Clean Water Act requirements and other critical issues. Unfortunately, we cannot combine this information to effectively answer national questions or track water quality changes over broader scales. EPA and its state/tribal partners are implementing a series of national probability-based randomized surveys to address this national information gap. Additionally, these National Aquatic Resource Surveys are helping build stronger monitoring programs across the country by collaborating across partner organizations on new methods, new indicators and other water quality research. This session will highlight information from the national surveys, state/tribal intensification of the surveys or implementation of other statistical surveys, and other probability-based assessments of water quality. Presentations may address rivers, streams, lakes, reservoirs, coastal waters, and/or wetlands. Presenters will discuss their findings and the successful application of the results to policy and management actions. Beyond the survey results, talks should emphasize one or more of the following: integration of multiple designs (probability, targeted, modeling, etc) to more effectively meet management needs, development/refinement of field/lab methods, development of assessment tools, and leveraging resources to enhance implementation.

S41: Computer-based Visual Identification of Plankton

Organizers: Phil Culverhouse, University of Plymouth, pculverhouse@plymouth.ac.uk; Mike Sieracki, Bigelow Laboratory, msieracki@bigelow.org and Mark Benfield, Louisiana State University, mbenfie@lsu.edu

Research into visual identification of plankton is becoming viable for functional group ecology studies. SCOR WG130 was convened three years ago to promote the domain, establish standards and common working practices and to establish open-source software. The research community is now vibrant and growing quickly. There are several open-source toolsets available that can operate from scanners, digital cameras and commercial instruments. It is timely to bring together researchers from across the world to present recent progress in this area, including, examples of practice (both large-scale and small scale studies), software tool research and development of standards in both zooplankton and phytoplankton oceanography applications.

S43: Role of Environmental Change and Other Stressors on Predation and Parasitism in Aquatic Systems

Organizers: Bas Ibelings, Netherlands Institute of Ecology/ NIOO-KNAW, b.ibelings@nioo.knaw.nl; Piet Spaak, Eawag, piet.spaak@eawag.ch, Alena Gsell, NIOO-KNAW, a.gsell@nioo.knaw.nl and Silke van den Wyngaert, Eawag, wyngaert@eawag.ch

Host-parasite and predator-prey interactions play a substantial role in the structure and dynamics of communities. The continuum from predatory to parasitic behavior is rather gradual; the underlying principles are the same. Environmental factors (abiotic and biotic) can influence the strength and direction of these interaction types. The occurrence and strength of anthropogenic stressors—e.g. climate change, pollution, habitat fragmentation, invasive species and eutrophication—is on the rise. What role will these stressors play in the outcome and severity of host-parasite/predator prey systems? Intuitively, environmental stressors are expected to weaken the host’s defenses and thus make them more susceptible to predation and parasitism. But in some cases, stressors may also act directly or indirectly on the predator/parasite, either by generally weakening their virulence or by driving host numbers down to a level, where predators/parasites find it hard to find new preys or susceptible hosts. Environmental stress may also erode genetic diversity of (endangered) species, weakening their defenses even more. Thus, the influence of environmental change and other stressors on parasitism and predation dynamics may be more complex than expected. In this session we will explore this complexity in all its aspects.

S44: Environmental Controls on Mercury Bioaccumulation in Freshwater Ecosystems

Organizers: Paul M. Bradley, U.S. Geological Survey, South Carolina Water Science Center, pbradley@usgs.gov and Lia C. Chasar, U.S. Geological Survey, Florida Integrated Science Center, lchasar@usgs.gov

Bioaccumulation of mercury in freshwater ecosystems is a significant threat to aquatic communities and the associated terrestrial populations, including humans. As of 2008, more than 3000 fish consumption advisories for Hg have been listed, affecting 50 states and covering more than 43% of lakes and 39% of the nation’s total river miles (greater than 800,000 river miles affected). Conceptually, mercury bioaccumulation in aquatic systems can be viewed as a function of (1) the microbial production and in situ persistence of methylmercury (MeHg), (2) the transport of MeHg from the site and matrix of production to the point of entry into the food web, and (3) the efficiency of biotic uptake and trophic transfer of MeHg. This session will focus on recent advances in our understanding of the geochemical, hydrologic and biological factors affecting mercury bioaccumulation in freshwater systems, with an emphasis on factors influencing MeHg transport to aquatic habitats, bioaccumulation in lower trophic levels, and trophic level transfer of MeHg. In light of the increasing requirement to integrate the results of individual ecosystem studies with regional- and national-scale multi-basin investigations, presentations addressing the effects of scale on the interpretation of bioaccumulation results are encouraged.

S45: Landscape Limnology: Integrating Lakes, Streams and Wetlands in the Freshwater Landscape

Organizers: Patricia A. Soranno, Michigan State University, soranno@msu.edu; Kendra Spence Cheruvelil, Michigan State University, ksc@msu.edu and Mary T. Bremigan, Michigan State University, bremigan@msu.edu

Lakes, streams, wetlands, and groundwater are often studied, managed, and understood in isolation from other freshwater ecosystems. This situation has occurred despite the early definition of limnology as a discipline that integrates all types of inland waters. However, many of today’s most pressing problems, from climate change to invasive species spread, depend on understanding the often complex linkages among multiple freshwater ecosystem types, necessitating an integrated approach to the study of freshwater ecosystems. The sub-discipline of landscape limnology offers a perspective that can address such a range of ecological and environmental issues, because it studies freshwater ecosystems in a spatial context as they interact with the terrestrial, freshwater, and human landscapes to determine pattern and process of important aquatic ecosystem dynamics. Accordingly, we invite contributions that seek to bridge stream, lake, wetland or groundwater disciplinary and hydrologic boundaries and that address landscape or cross-scale linkages among freshwater ecosystems, their catchments and human disturbance gradients.

S46: Current Research Themes in Aquatic Ecology: A Perspective from the Tropics

Organizers: Anne Brasher, U.S. Geological Survey, abrasher@usgs.gov; Mollie McIntosh, Michigan State University, mcinto57@msu.edu and Richard MacKenzie, U.S. Forest Service, rmackenzie@fs.fed.us

Tropical regions throughout the world have diverse aquatic environments, including a variety of stream, river and wetland ecosystems. Until recently, little ecological research on tropical ecosystems has been published in the scientific literature compared to temperate regions. Recent studies have brought new insight on the biology and ecology of tropical aquatic assemblages and on the effect of human disturbance and subsequent environmental degradation on tropical aquatic ecosystems. This information is critical to the development of new ecological concepts, themes and management strategies specific to tropical aquatic environments. In addition, this information contributes to our overall understanding of ecological processes in aquatic systems, across all geographical regions. This session will provide those conducting aquatic research with a forum to share and discuss their current basic and applied research in tropical regions throughout the world. This session will also foster collaborations among new and leading researchers in this field. Continued communication among researchers along with new, innovative research efforts are needed to conserve the ecological integrity of tropical aquatic ecosystems.

S47: Aquatic Science in the Cryosphere and Other Really Cold Places

Organizers: Michael R. Twiss, Clarkson University, mtwiss@clarkson.edu and Hunter J. Carrick, Penn State University, hjc11@psu.edu

Consequences of global change are reflected in contraction of polar ice caps, reduction in lake ice cover, and alterations of seasonal signals in aquatic ecosystems. Most aquatic science investigations take place during field seasons that are typically amenable to sampling and periods of expected high biological activity, such as summer in temperate zones. As a result, relatively little information is available on the structure and function of aquatic ecosystems during winter periods, resulting in a fragmented understanding of system ecology. This session will present research on aquatic systems conducted during winter periods. Given the interest in global climate change that can affect the severity and extent of winter periods, knowledge of how these systems function (biogeochemical, geophysical, ecological) during cold is needed.

S49: Using Isotope Tracer Additions to Quantify Food Web Flows in Stream Ecosystems

Organizers: Rana El-Sabaawi, University of Victoria, rana@uvic.ca; Alex Flecker, Cornell University, asf3@cornell.edu and Steve Thomas, University of Nebraska - Lincoln, sthomas5@unlnotes.unl.edu

The use of whole-stream isotope additions has greatly improved our estimates of biogeochemical transformations such as nitrification, denitrification and ammonium uptake. These techniques have facilitated the ability to compare biogeochemical processes across many types of stream ecosystems, and have led to several cross-system syntheses of nitrogen dynamics. Tracer additions have also been used to measure how food web fluxes respond to various environmental and biological factors, but the development and synthesis of tracer-generated models of food web structure and function have lagged behind measurements of biogeochemical processes. The goal of this session is to provide a forum for researchers to synthesize tracer-generated food web models and identify future needs and directions for these analyses. Invited and submitted talks will address case studies highlighting how tracer additions have been used to answer food web-related questions and identify technical challenges of modeling food webs based on isotope tracer data. A further goal of this session will be to investigate how food web theory can be coupled with tracer techniques to generate comprehensive food web models of lotic ecosystems. This session aims to galvanize and coordinate efforts that compare patterns of food web dynamics and trophic connections across diverse systems.

S50: Development of Process-Based, Continental-Scale, Aquatic Ecosystem Models

Organizers: Wilfred Wollheim, University of New Hampshire, wil.wollheim@unh.edu; John Kominoski, University of British Columbia, jkominoski@gmail.com; John Harrison, Washington State University-Vancouver, john_harrison@vancouver.wsu.edu; Takashi Sakamaki, University of the Ryukyus, Japan, sakamaki@lab.u-ryukyu.ac.jp and Bill McDowell, University of New Hampshire, bill.mcdowell@unh.edu

Aquatic ecosystems regulate material transfer between terrestrial and coastal systems, and play a significant role in regional to global carbon (C) and nutrient (nitrogen, N; phosphorus, P) cycles. This regulation is likely being altered by human activities such as land-use change, climate change, and hydraulic engineering. In order to predict the aggregated effects of global environmental change on C and nutrient cycles in freshwater systems and ultimately in linked estuarine systems, process-based models are needed that integrate terrestrial-aquatic linkages (spatial and temporal variability of source quantity and quality), transformations within different types of aquatic ecosystems, and upstream-downstream linkages. Development of such aquatic models will help constrain terrestrial ecosystem models, and support continental-scale ecological observation systems, such as NEON. We seek presentations that will inform the development of process-based, continental-scale, aquatic ecosystem models. A wide range of approaches are of interest including the application of existing aquatic modeling approaches to address watershed to continental-scale questions on the fate of C and nutrients; development of sub-models or datasets that are needed to drive continental-scale models (e.g., spatially distributed discharge, water temperature, light, material loadings); field studies and/or data syntheses that can potentially be used to parameterize or test such models. Examples of relevant topics include 1) quantification of C and nutrient inputs to aquatic systems over broad spatial and temporal scales, 2) approaches for developing general algorithms of C and nutrient reactivity (including photo-oxidation, microbial respiration, denitrification, assimilation, remineralization) 3) strategies for integrating diverse aquatic systems that range in size and connectivity with continental river networks, 4) strategies for validating estimates of terrestrial inputs and aquatic transformations of C and nutrients, and 5) broad-scale assessments of major environmental changes that may influence C and nutrient processing dynamics in aquatic ecosystems.

S51: Organic Carbon Dynamics in Freshwater Arctic Ecosystems

Organizers: William V. Sobczak, Holy Cross College, wsobczak@holycross.edu and John Schade, St. Olaf College, schade@stolaf.edu

There is increasing evidence that inland freshwater ecosystems play a significant role in the global carbon cycle due to the metabolism of terrestrial-derived organic matter as it moves in fluvial networks from land to sea. Recent research suggests that Arctic watersheds may increasingly augment the global role of freshwater ecosystems in the flux of terrestrial carbon to the atmosphere and ocean as a result of global warming. There is also growing recognition that many Arctic fluvial networks are experiencing marked hydrologic and biogeochemical changes in headwater streams, lakes, and wetlands. The objective of this special session is to convene researchers examining organic matter dynamics in a wide variety of freshwater Arctic environments (including wetlands, lakes, streams, and rivers) in order to develop a more unified conceptual model of Arctic carbon cycling. We welcome contributions from researchers studying both lower and higher trophic levels.

S52: Experimental Evidence for Ecosystem Responses to Global Warming in the Center and at the Edges of Oceans, Lakes and Streams

Organizers: Mark Gessner, Eawag, mark.gessner@eawag.ch and Jessica Hines, Eawag, jessica.hines@eawag.ch

Proposal for a semi-interactive special session at the joint ASLO/NABS meeting abstract projected global changes in temperature and other environmental factors are expected to have strong impacts on the structure and functioning of ecosystems. However, there have been few experimental studies documenting consequences of global warming on aquatic ecosystems. One of the most powerful means to elucidate ecological impacts is manipulative experiments that encapsulate the complexity and scales of natural systems. This approach allows for description of patterns, identification of mechanisms, and tests of hypotheses derived from observation or theory. In spite of these strengths, the majority of empirical research addressing temperature effects on ecosystems has been conducted using correlative approaches based on gradient analysis, observations from long-term monitoring studies, or small-scale laboratory experiments. This session will unite scientists with diverse backgrounds to share their perspectives, approaches and findings from manipulative field experiments in the center and at the edges of oceans, lakes, and streams. We seek contributions from coastal, benthic and pelagic studies in marine and fresh waters. The intention is to identify generalities and contrasts among systems by evaluating a broad range of responses (populations, species interactions, communities, or ecosystem processes) to effects of warming, either alone or in combination with other global change factors. The session will conclude with a synthesis designed to encourage an open discussion between the speakers and attendees, with the goal of evaluating the current consensuses and future directions of the field.

S54: Frontiers in the Biology, Ecology and Global Significance of Pelagic Tunicates

Organizers: Marc E. Frischer, Skidaway Institute of Oceanography, marc.frischer@skio.usg.edu and Christofer Troedsson, Unifob Environmental Research, Unifob AS, christofer.troedsson@bio.uib.no

Neritic and oceanic regions experience episodic occurrences of pelagic tunicate swarms, yet a comprehensive understanding of the ecological and biogeochemical role of pelagic tunicates or of the oceanographic processes that regulate these species is limited. Over 10 years ago the last comprehensive text dealing with pelagic tunicates was published. Since then, despite significant progress in the field, a full review of the topic has not been undertaken. Preparing such a review will require a synthesis of disparate studies conducted by scientists all over the world and employing a diversity of approaches; for example, the integration of the tools of molecular biology with the classical tools of zooplankton ecology. This session will include presentations by those who are engaged in the study of pelagic tunicates from any perspective to stimulate an interdisciplinary discussion concerning the biology, ecology, and global significance of pelagic tunicates. This symposium is a springboard to explore interest within the scientific community to prepare a timely synthesis of the biology of pelagic tunicates.

S55: From the Center to the Edge: Rediscovering the Littoral Zone in Lake Ecosystems

Organizers: Shawn Devlin, Wright State University, shawn.devlin@gmail.com; Scott Higgins, University of Wisconsin-Madison, snhiggins@wisc.edu and Yvonne Vadeboncoeur, Wright State University, yvonne.vadeboncoeur@wright.edu

Research on lake littoral dynamics and littoral-pelagic links has intensified recently, and a true whole-lake perspective is reemerging in lake ecology. Regardless of lake size, littoral zones harbor high diversity, and littoral production is a critical component of lake food webs. Littoral zones are also the interface between lakes and the terrestrial landscape leading to cross-ecosystem fluxes of nutrients and energy. The emerging understanding of the ecological activity in littoral zones is paralleled by the recognition that lake edges are also focal points of human activity: lake edges are highly modified by humans and are critical points for the establishment and spread of invasive species and disease. Despite their ecological importance and sensitivity to anthropogenic impacts, littoral processes remain one of the least studied areas of limnology. This session will present an integrated perspective of our current understanding of the role of littoral zones in lake ecosystems and identify key unexplored questions. In addition to research on basic littoral ecosystem processes, this session will include presentations on littoral-pelagic links, littoral-terrestrial links, and anthropogenic impacts on the terrestrial aquatic ecotone. The exploration of littoral zone dynamics has truly expanded aquatic ecological focus from the center to the edge.

S56: Multiple Stressors in Aquatic Ecosystems

Organizers: Colin Townsend, University of Otago, New Zealand, colin.townsend@stonebow.otago.ac.nz; Christoph Matthaei, University of Otago, New Zealand, christoph.matthaei@stonebow.otago.ac.nz , Stephen Maberly, Centre for Ecology and Hydrology, Lancaster, United Kingdom, scm@ceh.ac.uk, Alan Hildrew, University of London, Queen Mary and Westfield College, School of Biological Sciences, A.Hildrew@qmul.ac.uk and Klement Tockner, IGB, Leibniz-Institute of Fisheries Ecology & Inland Fisheries, tockner@igb-berlin.de

Anthropomorphic stressors seldom act in isolation in aquatic ecosystems. Factors as diverse as eutrophication, sedimentation, invasive species and climate change may act interactively in unpredictable ways. Managers aim to identify thresholds of harm beyond which ecosystems should not be allowed to move but, to be meaningful, thresholds often need to be defined for situations where multiple stressors are operating. If managers only consider the effects of individual stressors, their assessment of risk may be higher or lower than reality. The challenge for both freshwater and marine researchers is to appraise and predict effects on aquatic organisms, populations, communities and ecosystems where stressors interact.

S57: Spring-fed Ecosystems as Models for Testing Ecological Theory and Global Change Predictions

Organizers: Jón S. Ólafsson, Institute of Freshwater Fisheries, Iceland, jsol@veidimal.is; Jon Benstead, University of Alabama, jbenstead@bama.ua.edu and Jim Heffernan, Florida International University, jheffer@fiu.edu

The use of springs and spring-fed streams as model ecosystems has a long history in ecology, dating back to H.T. Odum’s seminal study of energy flow in Silver Springs, Florida. Such systems provide unique natural laboratories because of their thermal, hydrologic and chemical stability and clearly delimited ecosystem boundaries. Moreover, a considerable diversity of spring types is found on Earth. Heterogeneity in terms of thermal regime, chemical composition and discharge is reflected in their distinctive biota, making springs analogs of islands, with fauna and flora that have limited resemblance to those of adjacent ecosystems. These combined characteristics (stability of individual springs, diversity of spring types across landscapes, and distinctive communities) make spring-fed ecosystems increasingly relevant and useful for testing novel ecological theory and predictions of future global change. In this session we welcome contributions involving experimental and observational studies on warm and cold spring-fed ecosystems, their biodiversity, ecological and evolutionary processes. We particularly encourage presentation of data from spring-fed ecosystems that focuses on testing either general ecological theory or global change predictions.

S58: Coupling Water Residence Time and Biogeochemical Cycling in Landscapes

Organizers: Ryan Sponseller, University of Alabama, rasponseller@bama.ua.edu; Kevin Mcguire, Virginia Tech, kevin.mcguire@vt.edu; Maury Valett, Virginia Tech, mvalett@vt.edu and Emily Stanley, University of Wisconsin, ehstanley@wisc.edu

Hydrologic flow paths and connectivity act as important drivers of biogeochemical pattern and process in both terrestrial and aquatic components of landscapes. The relative importance of hydrologic flow to biogeochemical cycles in different ecological settings depends on the physical properties of transport and the biological or geochemical reaction rates characteristic of a particular habitat. One increasingly popular approach to quantifying hydrologic influences on ecosystem properties is to determine water transit time (or water residence time) through different environments. Originally, many of these efforts focused on only the residence times of water; however, biological interactions during transport along flow paths have important consequences for the fate and form of reactive elements in ecosystems. In recent years, a set of approaches and tools for understanding how the timing and character of water movement influence biogeochemical cycles has been developed and employed by catchment hydrologists, stream and river ecologists, wetland scientists, and oceanographers. The goal of this session is to bring together investigators from these diverse settings, and to explore generalities in both the drivers and biogeochemical implications of variable hydrologic routing among terrestrial and aquatic ecosystems.