Organizers: Yu-Ping Chin, The Ohio State University, yo@geology.ohio-state.edu; Bettina M. Voelker, Colorado School of Mines, voelker@mines.edu

The purpose of this symposium is to celebrate the retirement of Dr. Barbara Sulzberger and to honor her achievements in the field of aquatic photochemistry. We seek papers examining photochemical and associated processes in aquatic environments, including the formation and effects of reactive oxygen species (ROS) and other reactive transients, photochemical effects on dissolved organic matter and other aspects of the global carbon cycle, and transformations of inorganic and organic contaminants. Papers are especially welcome in areas highlighting Barbara�s major contributions to our understanding of the cycling of carbon, metals, and contaminants in aquatic systems. These include mechanisms and ffects of sunlight-driven metal redox cycling, heterogeneous photochemistry, and the roles of iron and dissolved organic matter in the production of ROS.

Organizers: Zoe V. Finkel, Mount Allison University, zfinkel@mta.ca; Andrew J. Irwin, Mount Allison University, airwin@mta.ca

The size of an organism helps determine myriad characteristics including metabolic rate, generation time, and influences numerical abundance, food web structure and trophic efficiency, elemental cycling, and even evolutionary rates. Organism size provides fundmental physical constraints that lead to broad biological laws, but relentless selection pressure results in novel phenotypes that allow organisms to partially escape from these constraints and are often equally illuminating. This session is cross-disciplinary and welcomes submissions that address the physiological, ecological, biogeochemical, or evolutionary consequences of organism size across freshwater, marine, planktonic and benthic systems.

Organizers: Andrew Folkard, Lancaster University, a.folkard@lancaster.ac.uk; Ian Jones, CEH Lancaster, ianj@ceh.ac.uk

Physical processes play a crucial role in determining ecology within lakes, and much recent research has addressed the problem of understanding this nexus, from both biological and physical standpoints. Thermal structure, in both spatial and temporal senses, is a key issue here: water temperature directly affects biological activity, and the typically stratified nature of the thermal structure of lakes introduces a wide range of hydrodynamical phenomena such as internal waves, vertically-constrained turbulence and convective currents, all of which exert strong controls on biology. In addition, concentrations of suspended particulate matter due to resuspension from the lake bed by shear stresses or inflows from either point or diffuse sources affect light levels, applying another strong constraint on biology. Biological organisms can also strongly influence physical parameters within lakes, for example through shading of the water column by littoral zone macrophytes or algal mats, or by altering the extinction coefficient of the water. These effects, in turn, can feedback to influence the organisms. Relevant timescales vary from multiple-decadal processes such as climate change, through the seasonal cycle of succession to sub-hourly mixing processes. In this session, work relating to a wide range of physical and ecological interactions will be presented, with the intention of building stronger linkages and recognition between physical and biological limnology research communities.

Organizers: Bernard P. Boudreau, Dalhousie University, bernie.boudreau@dal.ca; George B. Arhonditsis, University of Toronto, georgea@utsc.utoronto.ca; Alain Vezina, Institution: Bedford Institute of Oceanography, VezinaA@mar.dfo-mpo.gc.ca; Craig A. Stow, NOAA Great Lakes Environmental Research Laboratory, craig.stow@noaa.gov

Almost every aspect of the marine environment has been subject to mathematical modelling, either to increase our knowledge of the mechanisms and processes that operate or to extract some form of derived information, such as predictions, statistics, links, comparative parameters values, etc. To obtain these outcomes, modellers have applied a host of different modelling methods. However, as a community, marine modellers are not necessarily cognizant of successful techniques employed on problems outside their immediate areas of interest or expertise. Yet, these unfamiliar methodologies might be of great value beyond their current applications.

Marine modellers traditionally do not meet as a group, but as part of sessions on the problems they address. That approach has impeded cross-specialty communication of both problems and solution procedures. This session is intended to highlight modelling and its methods in addressing any problem in the marine realm; it constitutes an opportunity for modellers to meet and address mathematical concerns, regardless of the nature of the problem. We invite modellers who work from the air-sea interface into the bottom sediments, from the lowest trophic level to the highest, and from the smallest scale to the largest to join us in this session on "all things modelling."

Organizers: Janice Lawrence, University of New Brunswick, jlawrenc@unb.ca; Steven Short, University of Toronto, steven.short@utoronto.ca

While the sheer abundance of viruses in aquatic ecosystems has been well established, precise determination of their ecological roles and impacts has remained elusive. This session aims to bring together diverse oceanographers and limnologists who examine the biology and/or ecology of viruses. A wide range of topics in aquatic virology are welcome, including but not restricted to: the role of viruses in aquatic community dynamics, the biology of viral infections of aquatic organisms, and the diversity and dynamics of viroplankton in aquatic ecosystems. This session is intended to bridge the gaps between scientists studying viruses in freshwater and marine, benthic and pelagic, and heterotrophic and autotrophic systems, to name a few.

Organizers: Frances Pick, University of Ottawa, CAREG, frpick@uottawa.ca; Claudia Wiedner, Leibniz-Institute of Freshwater Ecology and Inland Waters, c.wiedner@igb-berlin.de; Thomas Rohrlack, Norweigian Institute of Water Research, thomas.rohrlack@niva.no

Cyanobacteria occupy almost every habitat on the planet. This is because of a tremendous diversity of species encompassing an unknown range of genotypes, chemotypes and ecotypes. From a lake management perspective, it is important to understand the ecology of certain cyanobacterial traits such such as the capacity to produce toxins of human health concern. Yet to date, it has been difficult to associate cyanotoxin measurements in the environment with the taxa actually responsible for their production. Molecular and chemical approaches are needed to resolve this problem. In this session we welcome presentations that address 1) the problem of how to define diversity in the cyanobacteria, 2)the development of methods (molecular or chemical) for associating particular traits with the taxa expressing them in situ 3)the range of ecotypes observed within particular species 4)the question of evolution of particular ecotypes genotypes or chemotypes that may exhibit geographic differences.

Organizers: Michelle S. Hale, University of Portsmouth, michelle.hale@port.ac.uk; Richard B. Rivkin, Memorial University of Newfoundland, rrivkin@mun.ca

Microbial foodwebs are complex assemblages of viruses, and autotrophic and heterotrophic prokaryotes and eukaryotes, which have a central role in the cycling of biogeochemical elements (i.e. carbon, nitrogen, sulfur) and climatically active gases (i.e. CO2, NO2, DMS), in both marine and freshwater ecosystems. Although the processes have been studied for over two decades, the roles of this diverse group are still poorly defined both within and between systems. Understanding the spatial and temporal scale of forcings, and how the structure and function of microbial foodwebs change in response to them, is crucial in order to quantify and predict how aquatic systems will respond to, and feedback into, changes in climate. Considering their importance in global cycles, a Special Session characterizing and comparing across systems, is timely. This session will bring together scientists studying all aspects of microbial foodwebs in freshwater and marine systems, to compare and contrast the importance of microbial foodwebs in mediating biogeochemical cycles.

Organizers: Richard B. Rivkin, Ocean Sciences Centre, Memorial University of Newfoundland, rrivkin@mun.ca; Louis Legendre, Laboratoire d'Oceanographie de Villefranche, legendre@obs-vlfr.fr

The structure of the marine food web largely controls the biogeochemical cycling of organic matter, which partitions it into gas (e.g. CO2, DMS, N2O), dissolved or particulate phases. The gasses may exchange with the atmosphere, whereas the dissolved and particulate materials may be further processed by the food web or exported. This partitioning has a profound influence on both the air-sea exchange of bioactive gasses and the potential sequestration of anthropogenic carbon in the deep sea. Hence there is a coupling between food-web structure and climate. The main forcings that influence food webs are temperature, nutrient availability and ratios, and mixing; these change with latitude, season, and ocean basin. This special session will examine the observational, experimental, and conceptual and numerical modelling studies of the interactions among food-web and biogeochemical processes over a range of spatial and temporal scales, thus advancing our understanding of the feedbacks between ecosystems, biogeochemical cycles, and the earth-ocean system.

Organizers: Howard Riessen, SUNY College at Buffalo, riessehp@buffalostate.edu; Gary Sprules, University of Toronto, gary.sprules@utoronto.ca

The last ASLO meeting in St. John�s, in 1983, occurred during a period of rapid intellectual development in the field of plankton ecology. Research at that time was rapidly expanding our understanding of zooplankton feeding behavior, diel vertical migration, life history and prey defense strategies, and the roles of competition and predation in structuring plankton communities. Today, however, the major research efforts in plankton ecology have shifted to nutrition of individuals (using stoichiometry theory and fatty acid analysis) and its impact on populations and communities, benthic and watershed subsidies to plankton food webs (often using stable isotope analysis), and a more spatial approach to population and community structure that involves metapopulations and metacommunities as well as a variety of molecular genetic techniques. How are the 1983 studies linked to today�s research on plankton ecology? Why do we no longer focus on research themes from the early 1980's, such as individual zooplankton behavior? Is body size as important as we once thought? Do we completely understand diel vertical migration? It is likely that the expectations of funding agencies, technological advances in research tools, and the natural evolution of intellectual thought each provides partial answers to these questions. Understanding where we have been and how we arrived at our present state of knowledge provides a crucial framework for mapping our future intellectual development. In this special session we will examine the major shifts in the study of plankton ecology over the last quarter of a century. This will involve an historical analysis of changes in the science, but we primarily wish to use this perspective to view the state of plankton ecology today, the great questions that still need to be addressed, and where we should be headed in the future.

Organizers: Kurt E. Anderson, Department of Biology, University of California, Riverside, kurt.anderson@ucr.edu; Edward McCauley, Department of Biology, University of Calgary, mccauley@ucalgary.ca; Sebastian Diehl, Department Biologie II, Ludwig-Maximilians-Universitat, diehl@zi.biologie.uni-muenchen.de

Many freshwater and marine environments exhibit "open" dynamics, i.e., dynamics that are strongly influenced by immigration and emigration in addition to births and deaths. Many organisms in these environments disperse during some life stage in media with a strong directional bias, such as in the water columns of streams, rivers, and coastal alongshore currents. This creates asymmetric linkages among spatially separated habitats, which in turn can obscure relationships between environmental variables and ecological outcomes at all but the largest spatial and temporal scales. In addition to complicating our understanding of basic ecological processes such as population regulation and consumer-resource dynamics, advective dispersal in open systems also has implications for applied endeavors such as impact assessment and reserve design.

Traditional ecological theory has been mostly concerned with describing closed dynamics, yet the past decade has witnessed a proliferation of both theoretical and empirical studies of the causes and consequences of open dynamics. More recently, theory has been developed to address the specific effects of advective dispersal. Notable theoretical advances have been made in understanding the conditions for population persistence, scaling up ecological dynamics from local to regional scales, and linking system return times following a disturbance to the disturbance�s spatial scale. In concert, empirical studies increasingly recognize the potential scale dependence of open system dynamics. Methodological advances (e.g. use of stable isotopes, molecular genetic techniques, and experimental facilities) and larger scale conservation measures (e.g. stream restoration, marine reserves) create new opportunities to empirically study how dispersal processes interact with the local environment in shaping ecological dynamics. The goal of this session is to communicate recent advances in our understanding of open dynamics influenced by advection, and we will ask invitees to offer their thoughts on linking theory and empirical data. Our session should appeal to a wide variety of researches working in both freshwater and marine systems.

The session will begin with a 30-minute overview given by a leader in the field. We will ask the presenter to highlight areas where linking theoretical and empirical research can lead to rapid progress.

Example papers highlighting the effects of advective dispersal in open systems:

• Anderson KE, Nisbet RM, Diehl S, et al. 2005. Scaling population responses to spatial environmental variability in advection-dominated systems. Ecol Lett 8: 933-943.
• Anderson KE, Paul AJ, McCauley E, et al. 2006. Instream flow needs in streams and rivers: the importance of understanding ecological dynamics. Front. Ecol. Environ. 6: 309-318.
• Byers JE, Pringle JM. 2006. Going against the flow: retention, range limits and invasions in advective environments. Marine Ecology Progress Series. 313: 27-41.
• Diehl S, Cooper SD, Kratz KW, et al. 2000. Effects of multiple, predator-induced behaviors on short-term producer-grazer dynamics in open systems. Am. Nat. 156: 293-313.
• Lutscher F, Pachepsky E, Lewis MA. 2005. The effect of dispersal patterns on stream populations. SIAM Rev 47: 749-772.
• Lutscher F, McCauley E, Lewis MA. 2007. Spatial patterns and coexistence mechanisms in systems with unidirectional flow. Theoretical Population Biology. 71: 267-277.
• Macneale KH, Peckarsky BL, Likens GE. 2005. Stable isotopes identify dispersal patterns of stonefly populations living along stream corridors. Freshw. Biol. 50: 1117-1130.
• Shanks AL, Eckert GL. 2005. Population persistence of California Current fishes and benthic crustaceans: A marine drift paradox. Ecol. Monogr. 75: 505-524.
• Speirs DC, Gurney WSC. 2001. Population persistence in rivers and estuaries. Ecology, 82: 1219-1237.
• Speirs DC, Gurney WSC, Holmes SJ, et al. 2004. Understanding demography in an advective environment: modelling Calanus finmarchicus in the Norwegian Sea. Journal of Animal Ecology, 73: 897-910.

Organizers: Michael T. Arts, National Water Research Institute, Michael.Arts@ec.gc.ca; Martin Kainz, WasserKluster Lunz - Biologische Station, martin.kainz@donau-uni.ac.at; Christopher C. Parrish, Ocean Sciences Centre, Memorial University, cparrish@mun.ca

Lipids are increasingly being recognized as playing a preeminent role in structuring both marine and freshwater ecosystems. Certain of the polyunsaturated fatty acids and sterols have been shown to promote/enhance growth in zooplankton, shellfish and finfish. These and others are also useful for determining trophic transfer. Produced at the base of the food chain (algae), ω3 and ω?6 PUFA and phytosterols may undergo significant modification once ingested by consumers. The extent and mechanisms of these modifications and the degree of "trophic upgrading" which take place are now the subjects of intense research worldwide. We are now also becoming aware of threats to our access to essential fatty acids (e.g. overfishing, pollution, exotic invaders) resulting in an increased awareness of the critical role of these compounds for a sustainable and healthy aquaculture industry.

We welcome presentations along the lines of, but not limited to, the roles of lipids, including fatty acids and sterols, in:

• Production, transport and physiological implications of essential fatty acids, both within aquatic systems and at the aquatic-terrestrial interface
• Growth enhancing effects of essential fatty acids and sterols in natural systems and in aquaculture
• Effects of essential fatty acids and/or sterols on physiologically-important processes (e.g. membrane fluidity, cell signaling, ion channeling).
• Threats to the production and/or distributions of essential fatty acids (e.g. cultural eutrophication, climate change, overfishing) from an ecosystem perspective and/or from a human health perspective.
• Manipulating aquatic food webs to maximize essential fatty acid production
• Interactions between lipophilic contaminants and fatty acids and/or sterols
• The importance of optimal ratios of fatty acids
• Recent advances in lipid source identification and their pathways through aquatic food webs

Organizers: Catherine Johnson, Bedford Institute of Oceanography, JohnsonC@mar.dfo-mpo.gc.ca; Ann Tarrant, Woods Hole Oceanographic Institution, atarrant@whoi.edu; Mark Baumgartner, Woods Hole Oceanographic Institution, mbaumgartner@whoi.edu

Diapause is a critical part of the life history of many abundant aquatic crustaceans, and diapause timing can influence seasonal population dynamics, biological interactions with other taxa, and population responses to environmental variability. Significant progress has been made in understanding diapause control in many �model� arthropod species. Yet because diapause control mechanisms can differ among arthropod taxa, the underlying processes that control diapause are not yet understood in many ecologically-important aquatic species. The aim of this session is to bring together new research approaches or new applications of established approaches that address physiological, hormonal, and environmental mechanisms of diapause control. Contributors are invited to present methods, results, and perspectives that help to understand the physiological and hormonal mechanisms controlling diapause in aquatic organisms, the interactions between environmental cues and diapause, and their ecological significance and implications. Papers on both marine and freshwater taxa, 'model' species and key ecological species, as well as from laboratory experiments and field studies are all welcome.

Organizers: Dolors Planas, Universite du Quebec a Montreal, planas.dolores@uqam.ca; Robin Anderson, Fisheries and Oceans Canada, andersonro@dfo-mpo.gc.ca

Littoral and coastal zones are active ecotones linking watershed to lakes, rivers and oceans and the more productive areas of continental and marine waters. Riparian inputs fuel the productivity of littoral communities and a significant proportion of global primary productivity occurs in coastal zones. Coastal zones provide important habitat for larval fish and the integrity of the riparian zone is important for fish growth. Littoral zones support resting stages and initial growth of many pelagic algae, and are nursery and feeding habitats for many pelagic organisms at different levels of the foodweb. Habitat coupling has important consequences for biogeochemical cycling of carbon, nutrients fluxes, foodweb structure and stability. Habitat coupling between benthic and pelagic has often been investigated as a unidirectional process: from pelagic to the littoral for coastal organisms or vice versa for nutrient fluxes. Understanding the type and magnitude of interactions within and through littoral zones is urgently needed as we strive to evaluate and mitigate increasing pressures of human activities (waste discharges, habitat modifications, aquaculture, etc.) in the coastal zone. This session will invite papers on processes and population/community dynamics across the edges of aquatic environments and/or on linkages between habitats (riparian, littoral, riverine, estuarine, coastal, pelagic).

Organizers: Mike Piehler, UNC Chapel Hill, Institute of Marine Sciences, piehler@unc.edu; Wayne Gardner, The University of Texas at Austin, Marine Science Institute, gardner@utmsi.utexas.edu

Estuaries are at the interface of both salt and freshwater and the terrestrial-aquatic environments. Dynamic biological, chemical and physical features result from their location, morphology, and geological characteristics, but so does their susceptibility to eutrophication and other stressors. Recent advances have improved our understanding of the ranges and rates of nutrient cycling processes and linkages between cycles in shallow water estuarine environments. Research on rates of transformations of major biogenic elements in shallow water estuarine environments (e.g. marshes, flats, submerged aquatic vegetation, oyster reefs) and the potential impact of stressors such as climate change and nutrient loading on these transformations will be presented.

Organizers: Owen Sherwood, Biology Dept., Memorial University of Newfoundland, osherwood@gmail.com; Daniel Sinclair, Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Dan.Sinclair@sams.ac.uk

Interest in the paleoceanographic utility of cold-water corals continues to grow. From its infancy over a decade ago, the science of paleo-reconstruction has evolved in two principle directions. Single long-lived Gorgonians promise continuous high-resolution records over century to millennial time scales. In contrast, cores taken down through deep reefs yield fragments of Scleractinian corals that may contain snapshots of seasonal-resolution climate over millions of years.

However, development of useful climate records from either approach proves challenging. Isotope and element 'vital effects' are ubiquitous in cold-water scleractinians; can we extract meaningful environmental records in light of this? How do we interpret the isotopic and elemental composition in the 2-part mineral-organic skeletons of cold-water gorgonians? Are geochemical records reliable and reproducible, and are they diagenetically stable? What are the best techniques for developing accurate age models? How do we calibrate records given the paucity of in-situ data in the deep ocean? The purpose of this session is to provide a forum for the presentation of results that explore all aspects of sclerochronology and biogeochemistry of cold-water corals.

Interfaces, whether chemical, physical or biological in nature, are often foci of intense activity. By their very nature a variety of processes can be concentrated over short distances, leading to unique interactions between organisms and environments. Sharp chemical gradients often lead to an abundance of bacterial activity and a myriad of interwoven substrates and products. This session welcomes papers discussing all aspects of ecology within and near strong environmental interfaces. Examples of such interfaces include oxic-suboxic-anoxic, sediment-water, air-sea, terrestrial-riparian, hydrothermal-deep sea, and freshwater-saline.

Organizers: Ian R. Bradbury, Dalhousie University, Halifax Nova Scotia Canada, ibradbur@dal.ca; Paul V.R. Snelgrove, Ocean Sciences Center, Memorial University, NL, psnelgro@mun.ca; Robert Gregory, Dept. of Fisheries and Oceans Canada, St. John's, NL, Gregoryr@DFO-MPO.GC.CA

Dispersal and connectivity among populations in fragmented habitats is a key factor that promotes the stability and persistence of metapopulations. The scale of connectivity is ultimately determined by habitat heterogeneity (i.e. structural connectivity), dispersal patterns, and mortality (i.e. functional connectivity). In aquatic ecosystems, multiple approaches have quantified connectivity ranging from tagging methodologies to molecular genetic analysis to hydrographic simulations. Although progress has been made in measuring dispersal in aquatic organisms, these approaches are typically applied in isolation and to single life-history stages. Interpretation and direct comparison with other studies and habitats are therefore problematic. This session will focus on dispersal and connectivity in aquatic systems with emphasis on integrating multidisciplinary approaches, comparing larval, juvenile, and adult dispersal kernels, and contrasting the roles of structural and functional connectivity. We invite contributions focusing on novel approaches to quantifying connectivity, analytical and conceptual tools for the analysis of dispersal data, and specific case-studies.

Organizers: Claudio DiBacco, Fisheries and Oceans Canada, cdibacco@gmail.com; Thomas Therriault, Fisheries and Oceans Canada, therriaultt@pac.dfo-mpo.gc.ca

The accidental or intentional introduction and spread of invasive species in marine and freshwater environments is recognized as a serious threat to the conservation of commercially and ecologically important organisms, their associated ecosystems and the economies that depend upon them. Further, impacts of invasive species are second only to habitat destruction as the cause of global biodiversity loss. Marine and freshwater ecosystems present few barriers to the spread of invasive species once they become established so efforts should aim to prevent invasions. However, preventing invasions requires knowledge of potential vectors and pathways for introduction and dispersal and the invader's biology and ecology, including factors affecting establishment success. Frequently, risk assessments are conducted to identify higher risk invaders and this information can be used to inform monitoring and rapid response efforts. However, a paucity of information about many potential invaders and their impacts usually results in high levels of uncertainty that also must be conveyed to managers. This symposium is intended to serve as an international forum for researchers to review newly accumulated scientific knowledge; presentation of the latest field research; introduction of new technological developments for prevention, monitoring and control of aquatic invasive species. Also, we will entertain papers on policy, public education and outreach initiatives that raise awareness of the impacts of aquatic invasive species and are intended to prevent new introductions.

Organizers: Sophia E. Fox, Marine Biological Laboratory/Boston University Marine Program, sefox@bu.edu; Paulina Martinetto, Lab. Ecologia Dpto. Biologia Universidad Nacional de Mar del Plata (UNMdP), pmartin@mdp.edu.ar

Important ecosystem-level controls act across landscape mosaics. Human-driven changes in terrestrial land use on watersheds directly and indirectly restructure adjoining receiving coastal ecosystems. Nutrient loading and deforestation are two major consequences of intensifying human land use at the land-sea interface. These changes on the surrounding watershed often lead to major shifts in composition and abundance of primary producers and consumers existing in adjacent coastal areas. The strength of coupling to the terrestrial environment depends on the particular physical and chemical characteristics of the affected area, and the connections among adjacent ecosystems can be observed in trophic interactions on spatial scales from the near-shore to the open ocean. As humans alter the coastal landscape, it becomes increasingly important to understand the connectivity among watersheds, receiving waters, and coastal ecosystems. For this session, we welcome contributions examining the coupling of anthropogenic activities on watersheds to estuarine and marine food webs.

While there have been recent advances in the transformations of mercury in specific ecosystems there has been little integration and comparison of processes studied in lakes and oceans, polar vs tropic. The purpose of this symposium is to bring together this divergent group to link biogeochemical processes with contrasting food chain processes to determine if global contamination of mercury has reached a critical level where impacts to top predators, including man, has been impacted.

Organizers: Laurel Larsen, University of Colorado, Laurel.Griggs@colorado.edu; Ian Droppo, National Water Research Institute, Ian.Droppo@ec.gc.ca; Paul Hill, Dalhousie University, Paul.Hill@dal.ca; Dave Richardson, University of Maryland, drichar4@umd.edu

The aggregation/flocculation of organic matter in aquatic and marine systems greatly influences the transport and delivery of labile material downstream and vertically through the water column. Due to the fractal, porous nature of ubiquitous flocculated material and the fact that there are no universal equations for predicting cohesive sediment erosion, transport or fate, the assessment of POM mobility in fresh and salt water is not straightforward. Regardless, transport of this material can have strong implications for ecosystem metabolism, contaminant fate, water quality, and even geomorphic processes. This session will focus on recent advances in assessing the mechanisms and impact of POM transport in freshwater environments, estuaries, and oceans, with a particular emphasis on ecological implications. Submissions based on laboratory, field, and/or computational studies are all encouraged.

Organizers: Aaron Packman, Northwestern University, a-packman@northwestern.edu; Patrick Mulholland, Oak Ridge National Laboratory, mulhollandpj@ornl.gov

Recently it has been recognized that processes occurring on or within sediments play extremely important roles in freshwater and coastal ecosystems. For example, it has been estimated that up to 90% of the microbial biomass in shallow freshwater systems occurs in the form of biofilms attached to sediments and other surfaces. As a result, processes within biofilms strongly influence whole-system metabolism and associated elemental cycling, e.g., of carbon, nitrogen, and phosphorus. Benthic and hyporheic processes are complex because they involve interfacial transport, pore fluid flow, and a variety of chemical reactions occurring both on surfaces and in pore waters. Further, the strong spatial gradients resulting from the combination of sediment heterogeneity, strong local variability in transport conditions, and microbial activity support diverse microbial populations that can, in turn, drive a wide range of biochemical processes. This session will explore all aspects of benthic and hyporheic processes, with particular emphasis on the coupling between system structure, hydrodynamic transport, chemical transformations, microbial processes, and overall ecosystem metabolism and biogeochemical cycling

Organizers: Edith Durisch-Kaiser, Swiss Fed. Inst. of Technology (ETH) Zurich, edith.durisch-kaiser@env.ethz.ch; Sebastian Sobek, Swiss Fed. Inst. of Aquat. Sci. and Technol. (Eawag)/ETH Zurich, sebastian.sobek@env.ethz.ch; David Bastviken, Stockholm University, david.bastviken@geo.su.se

Despite their small areal extent, lakes are sites of intense carbon cycling (Cole et al. 2007). Some of the OC is processed by microbes and benthic animals, resulting in the production of biomass supporting aquatic food webs. Microbial activity results in the formation of carbon dioxide (CO2) and methane (CH4). Recent studies indicate that CH4 emissions from lakes account for 6 - 16% of the non-anthropogenic emissions on a global basis (Bastviken et al. 2004). The OC, escaping assimilation and mineralization, is buried in lake sediments. Global estimates represent roughly 50% of the marine rate. Regarding that lakes cover only 0.5 % of the Earth's surface (compared to 71% by oceans), lakes appear to be disproportionately important as sinks for OC. The extent and mechanisms of OC preservation in lake sediments bear major knowledge gaps and generalizations are difficult due to the heterogeneity of lake systems. Oxygen exposure, protective sorption onto mineral surfaces, and the chemical composition of the organic matter (Burdige 2007) may possibly regulate OC preservation in lake sediments. For the proposed session we welcome contributions from both mechanistic and ecosystem-scale studies, and from the field as well as from the laboratory.

Representative papers:

• Bastviken D, Cole J, Pace M, Tranvik L (2004) Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate. Global Biogeochemical Cycles 18 GB4009 (4012 pages), doi:4010.1029/2004GB002238
• Burdige DJ (2007) Preservation of Organic Matter in Marine Sediments: Controls, Mechanisms, and an Imbalance in Sediment Organic Carbon Budgets? Chem. Rev. 107:467-485
• Cole JJ et al. (2007) Plumbing the global carbon cycle: Integrating inland waters into the terrestrial carbon budget. Ecosystems 10:171-184

Organizers: William Li, Bedford Institute of Oceanography, LiB@mar.dfo-mpo.gc.ca; Paul del Giorgio, Universite du Quebec a Montreal, del_giorgio.paul@uqam.ca; Angel Lopez-Urrutia, Instituto Espa�ol de Oceanograf�a, alop@gi.ieo.es

Long term environmental monitoring is widely conducted, often in the context of anthropogenic perturbations. Such time series measurements contribute to and strengthen existing macroecological concepts. Macroecology investigates the abundance, distribution and diversity of organisms in their environment by examining the statistical phenomenology of a large number of observations. By and large, these observations are made in diverse ecosystems across a broad spatial scale, testing for links between biological phenomena and environmental predictors. In aquatic ecosystems, it remains to be demonstrated whether such correlative links derived from comparative analyses over space provide robust interpretation for patterns of change over time, especially if prediction is required beyond the range of existing observations. This session aims to explore empirical and theoretical macroscopic approaches to contemporary aquatic problems that focus on change over multiyear time scales.

Organizers: Martin Kernan, Environmental Change Research Centre, University College London, mkernan@geog.ucl.ac.uk; Gavin Simpson, Environmental Change Research Centre, University College London, gavin.simpson@ucl.ac.uk

Climate change affects the hydrological, physical, chemical and biological characteristics of all freshwaters, and is thereby a key influence on element cycling (nutrients, major ions, DOC, organic pollutants, metals), food webs and biodiversity. Additionally climate change acts indirectly through changes in land-use patterns which will have impacts on aquatic ecosystems at both the catchment and habitat scales. Further, global land use changes are likely to result from mitigation and adaptation strategies in response to the impacts of changing climate. A third global pressure, nitrogen deposition, has resulted in a major disruption of the nitrogen cycle which has had widespread impacts on aquatic ecosystems. This session seeks to bring together work examining the effects of these drivers of global change with particular emphasis on the interactions between them.

Organizers: Carlos M. Duarte, IMEDEA, CSIC-UIB, Mallorca, Spain, carlosduarte@ifisc.uib.es; Susana Agust�, IMEDEA, CSIC-UIB, Mallorca, Spain, sagusti@uib.es

The 4th International Polar Year (IPY, March 2007 - March 2009) is taking place at a time when climate warming is clearly affecting polar regions. Warming rates and the associated ice loss appears to be accelerating in the Arctic and some regions of Antarctica. Provided the critical role of ice cover in determining the functioning and traits of polar aquatic ecosystems, marine and freshwater, rapid ice loss is expected to severely impact these ecosystems at multiple levels. Ice loss will affect the radiative balance of polar waters, affecting their thermal and light, including UV, environments. Ice loss will intensify air-water interactions in polar ecosystems, and will also severey impact all species, from microbes to megafauna, depending on ice as habitat. Warming together with ice loss will affect the key biological and biogeochemical processes supporting aquatic polar ecosystems, and may induce ecological regime shifts in these ecosystems, derived from posible losses of polar biodiversity together with an increased vulnerability to invasions from exotic species. This session aims at providing a forum to present and discuss, both through oral presentations and postres, results on the Impacts of Climate Warming on Polar Marine and Freshwater Ecosystems, allowing scientists concernid with freshwater and marine ecosystems to interact and exchange information. These discussions may provide timely in redirecting and providing new impetus to research efforts as we cross the equator of the IPY.

Organizers: Roger Harris, Plymouth Marine Laboratory, UK, r.harris@pml.ac.uk; Peter Wiebe, Woods Hole Oceanographic Institution, USA, pwiebe@whoi.edu; Brad de Young, Memorial University, St. John's, Newfoundland, bdeyoung@physics.mun.ca

It is timely to coordinate studies at the basin scale, including connections with shelf seas such as the North Sea and the Newfoundland and Labrador shelves, given the importance of the North Atlantic for climate change and for exploited resources such as fisheries. The goal of this session is to advance understanding of the impacts of climate variability on marine ecosystems of the North Atlantic and associated shelf seas as well as the resultant feedbacks to climate. The enhanced understanding, through data synthesis and modeling, will contribute to the advancement of resource management strategies mitigating the effects of global change. The focus of the session will be on topics including the impact of climate variability on: temperature, stratification, transport, acidification, and their influence on the seasonal cycle of primary productivity, trophic interactions, and fluxes of carbon to the benthos and the deep ocean; life history strategies of target organisms, population dynamics and community structure; and the dynamics of exploited species. We welcome contributions, both retrospective and future scenarios, that present analysis and modeling studies of oceanographic plankton, benthos and fisheries data as a step towards the design and implementation of new field programs at the basin scale.

Organizers: Michael Scarratt, Fisheries and Oceans Canada, Maurice Lamontagne Institute, ScarrattM@dfo-mpo.gc.ca; Maurice Levasseur, Universit� Laval, maurice.levasseur@bio.ulaval.ca; Richard Rivkin, Memorial University of Newfoundland, rrivkin@mun.ca

Cycles of elements and energy within the Earth System are closely coupled. Exchanges of climate-active gases and aerosols between the ocean surface and the atmosphere exert important feedbacks on the global climate system. Understanding which processes are important, and constraining their magnitudes are essential for diagnostic and prognostic models of contemporary and future climate. This session focuses on recent research developments from Northern waters including, but not limited to, the IGBP SOLAS (Surface Ocean - Lower Atmosphere Study) program. We invite papers on the physical, chemical and biological processes underlying climate-relevant ocean-atmosphere interactions and feedbacks. Topics of interest will include: biogeochemical cycling of climatically important elements in the ocean, responses of oceanic systems to dust deposition, impacts of ocean acidification, as well as the influence of oceanic gas and aerosol emissions on atmospheric chemistry and aerosol dynamics.

Organizers: Libby Jewett, NOAA, libby.jewett@noaa.gov; Carol Auer, NOAA, carol.auer@noaa.gov

Climate change can have a profound effect on coastal and marine environments, and exacerbate impacts of other ecosystem stressors such as those associated with contaminant or nutrient loading. For example, warming and increased precipitation can promote hypoxia by increasing nutrient runoff and/or water column stratification. Among several other examples, the prevalence and impacts of harmful algal blooms and invasive species are predicted to increase under climate change scenarios. Forecasting how coastal ecosystems adapt to future conditions of rising sea level, and increases in temperature, flooding, and groundwater salinity, complicated by increased rates of coastal eutrophication, will allow for the development of tools for the evaluation of management options and associated tradeoffs. This session will present research on the interactive effects of climate change with other coastal ecosystem stressors, with an emphasis on the development of forecasting models for management application.

Organizers: Robinson Fulweiler, Louisiana State University, wally1@lsu.edu; Robert Twilley, Louisiana State University, rtwilley@lsu.edu

Perhaps nowhere is the effect of pulsing events more evident than at the land-sea boundary. Pulsing events can alter physical, geological, chemical, and biological aspects of coastal ecosystems. Sometimes the events are seasonal (i.e. the spring freshet) and transport materials from watersheds; others are more erratic (i.e. hurricanes) and transport nearshore materials into shallow coastal ecosystems. In order to understand how these events modify structure and function of coastal ecosystem, methodologies that implore long-term monitoring of coastal system response and large scale experimental manipulations can provide valuable insights. In this session we will focus on (but are not limited to) the effects of pulsing on biogeochemical cycling, sediment re-distribution, salinity gradients, and hypoxia. Speakers should focus on overviews of the topic or specific case studies of coastal system response to changes in pulsing events; and how human modification of coastal landscapes alter system resiliency. Our goal is to draw a wide diversity of scientists working on pulsing events together so that we can encourage better understanding of these disturbances to stability of coastal landscapes.

Organizers: Douglas R. Smith, USDA-ARS, drsmith@purdue.edu; Emily Stanley, University of Wisconsin, ehstanley@wisc.edu; Jennifer Tank, University of Notre Dame, jtank@nd.edu; Candiss Williams, Purdue University, williaco@purdue.edu

In most agricultural regions of the United States, headwater streams have been intensively managed over the last century and a half to facilitate rapid drainage of water from nearby fields. This has dramatically altered the hydrology in many of these areas. For many streams in the Midwestern U.S., greater than 75% of the land-use is row crop or animal agriculture. These are some of the same areas that have been identified as primary contributors to non-point sources of nutrients that can lead to water quality problems such as eutrophication and downstream hypoxia. It is important to understand the ecological role played by headwater streams in agricultural landscapes which can help us to better manage them for enhanced local and downstream environmental quality. The proposed session will include presentations from multiple regions where agricultural streams are an important part of the landscape, including topics such as aquatic ecology and habitat; land-use impacts on streams; in-stream biotic and abiotic nutrient transport; biogeochemistry; and the impacts of agricultural stream management and restoration on ecosystem function. Tentative responses indicate that there is likely to be sufficient interest for both an oral and a poster session.

Organizers: Philippe Archambault, ISMER-Universit� du Qu�bec � Rimouski, philippe_archambault@uqar.qc.ca; Suzanne Roy, ISMER-Universit� du Qu�bec � Rimouski, suzanne_roy@uqar.qc.ca; Robin Anderson, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, andersonro@dfo-mpo.gc.ca

Aquaculture has expanded significantly over the past decade, leading to increasing concerns about environmental consequences. Aquaculture is generally a coastal activity, with potential repercussions on human activities and the environment. In this special session, we focus on extractive aquaculture practices, namely bivalve aquaculture and its direct and indirect effects on pelagic and benthic ecosystems around the world. Current management practices for regulation of bivalve aquaculture are usually focused on site-by-site assessments. New approaches are required to quantify cumulative effects from all anthropogenic influences in coastal areas (including invasive species) where intensive bivalve aquaculture has the potential to cause broad-scale, ecosystem-level changes. We want to compare and contrast aquaculture sites that differ in terms of bivalve production and environmental characteristics. In order for bivalve aquaculture to be sustainable and properly regulated, the potential effects of the practice on different components of the environment, as well as the scale and variability of the effects, must be better understood and defined. A tutorial session would start this special session, and eventual publication of the presentations is being considered.

Organizers: Diane Stoecker, UMCES, HPL, stoecker@hpl.umces.edu; Per Juel Hansen, MBL, Univ of Copenhagen, PJHansen@bi.ku.dk; Thomas Weisse, �sterreichische Akademie der Wissenschaften, thomas.weisse@oeaw.ac.at

In fresh and marine waters, pH has a profound influence on availability of inorganic carbon, major nutrients and trace metals as well as directly affecting the physiology and growth of plankton, benthos and nekton. Changes in pH in aquatic systems due to blooms, increased atmospheric carbon dioxide, changing land use and weathering patterns and pollution can all influence organisms and their interactions with their environment. This session includes both increases and decreases in pH on time scales ranging from minutes to decades. It is designed to examine direct and indirect affects of alkalinity and acidity on ecophysiology, biogeochemistry and the structure and function of aquatic ecosystems.

Organizers: George I. Matsumoto, Monterey Bay Aquarium Research Institute, mage@mbari.org; John DeLaughter, Miami Science Museum, jdelaughter@miamisci.org; Leslie Peart, Joint Oceanographic Institutions, lpeart@joiscience.org

Free choice learning is education that is self-motivated, guided by the learner's desires and needs, and is the most common form of life-long learning. It happens in libraries, science museums, radio, television, and in many other venues. It is also exceptionally effective at inspiring new scientists and in promoting the importance of science and its central role in society. This session will solicit contributions on free choice learning activities, such as Distinguished Lecturer Series, displays, workshops, programs, podcasts, and exhibits. Presentations that focus on methods for gauging activity effectiveness and impact, and on those programs that provide create interactions between scientists, educators, and the general public are of special interest.

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