Session List

SS01 ASLO Student Symposium

Benjamin Cuker, Hampton University, benjamin.cuker@hamptonu.edu
Deidre Gibson, Hampton University, Deidre.Gibson@hamptonu.edu

The ASLO Multicultural Program (ASLOMP) sponsors this 32nd annual symposium for undergraduate and beginning graduate students to present their work to a supportive audience. The program is for both participants in ASLOMP and other students attending the meetings. Students may give an oral presentation in the Student Symposium only once, and are expected to move on to a regular session for subsequent presentations.

SS03 Distribution and impacts of ocean nutrient limitation

Thomas Browning, GEOMAR Helmholtz Centre for Ocean Research Kiel, tbrowning@geomar.de
Mark Moore, University of Southampton, c.moore@noc.soton.ac.uk
Erin Bertrand, Dalhousie University, erin.bertrand@dal.ca
Alessandro Tagliabue, University of Liverpool, A.Tagliabue@liverpool.ac.uk

Nutrient limitation constrains primary production throughout the global ocean and regulates its responses to climate change. A broadscale picture of nutrient limitation in the current ocean has emerged, with nitrogen limitation revailing in the stratified subtropical gyres and iron limitation in open ocean and some coastal upwelling regions. However, new research is rapidly adding important detail to this simple picture. Evidence continues to accumulate for co-limitation between these and other nutrients, including additional trace elements and vitamins. Such (co-)limitations are likely set by nutrient supply and removal mechanisms to and from the surface ocean, phytoplankton elemental stoichiometry, as well as microbial interactions within communities that are simultaneously under the influence of multiple additional abiotic (light, temperature) and biotic (grazing, viral lysis) controls. To understand this complexity, new approaches ranging from advances in ‘-omics’ capabilities, coordinated cruise programmes and autonomous platform observations, through to alternative mathematic constructions of nutrient limited growth rates, are being utilized. Such advances are urgently needed to better understand the drivers and impacts of oceanic nutrient limitation, as well as meeting the needs of testing and improving Earth System Model simulations projecting the impacts of climate change. This session invites contributions utilizing in situ, experimental, and modelling approaches that represent new advances in understanding oceanic nutrient limitation. These could range from those describing the basic distribution and identity of limiting nutrients for diverse microbial groups to understanding the mechanisms, impacts, and future development of nutrient limitation in the ocean.

SS04 Undergraduate Research in Marine and Aquatic Sciences

David Fields, Bigelow Laboratory for Ocean Sciences, dfields@bigelow.org
Lisa Rom, NSF, elrom@nsf.gov

Research opportunities are increasingly offered to undergraduate students in an effort to help them understand marine and aquatic sciences and to offer them an opportunity to consider this field as a career. Undergraduates who have conducted research are invited to present their results in this general session that will highlight the wide variety of student research and provide opportunity for interested faculty to discuss your project with you. The Research Experience for Undergraduate (REU) program brings large numbers of undergraduate students to marine institutions for summer research programs, and students who have participated in REU programs are particularly invited to submit to this session. Students are not limited to this session, and we encourage any undergraduate student who wishes to submit an abstract to a specialized science session in the subject of her/his research to consider that option as well.

SS05 Aquatic Viral Ecology

Corina Brussaard, NIOZ Royal Netherlands Institute for Sea Research, corina.brussaard@nioz.nl
Dolors Vaqué, Institut de Ciencies del Mar-CMIMA, dolors@icm.csic.es

Marine and freshwater viruses, from polar regions to tropical systems, are a huge reservoir of genetic diversity and are key players in regulating host population dynamics and subsequently carbon cycling in the microbial food web. This session will explore the ecology of aquatic viruses, ranging from their diversity to their role as agents of microbial mortality, and drivers of biogeochemical fluxes in the various different aquatic systems. The session is inclusive to the emergent approaches and methodologies that promote advances in the area of research, including lab-based, field and theoretical studies. We invite research related (but not restricted) to viral distributions and activities, virus-host and virus-virus interactions, and impact of microbial and environmental factors on virus production, diversity and decay.

SS06 Methane Accumulation in Oxic Aquatic Environments: Sources, Sinks and Subsequent Fluxes to The Atmosphere

Mina Bizic, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), mbizic@igb-berlin.de
Daphne Donis, University of Geneve, Daphne.Donis@unige.ch
Hans-Peter Grossart, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB)/ University of Potsdam, hgrossart@igb-berlin.de
Oliver Schmale, Leibniz institute for baltic sea research warnemünde (iow), oliver.schmale@io-warnemuende.de
Jana Milucka, Max Planck Institute for Marine Microbiology (MPIMM), jmilucka@mpi-bremen.de

Accumulation of methane in oxic aquatic environments has been reported for almost half a century, yet, only in recent years it became acknowledged and its contribution to global methane fluxes is being increasingly discussed. This phenomenon, contradicting the traditional knowledge of methane being produced solely by methanogenic Archaea under strictly anoxic conditions, was termed “The Methane Paradox”. To date, several biological mechanisms have been shown to contribute to oxic methane production. Of these, some have been biochemically resolved, as is the case for demethylation of methylphosphonates. Others remain enigmatic; for example, methane produced by phytoplankton during photosynthesis, the demethylation of methylamines and dimethylsulfoniopropionate (DMSP). Additionally, it has been established that classical methanogenesis can take place in anoxic microniches hidden in the oxic environment, e.g. the guts of zooplankton or sinking organic matter particles. Alongside the growing body of evidence showing active production of methane in oxic waters, new studies have shown that oxic methane production significantly contributes to the methane fluxes to the atmosphere from the respective environment. Yet, the scientific community remains divided as to how much of the surface methane is transported. Until now, methane emissions from the oxic surface layer of oceans and lakes remain a large uncertainty in the global methane budget. Despite amassing evidence that methane production in oxic surface waters leads to methane accumulation and increased atmospheric emissions, the isotopic signature of methane produced in the oxic environment is largely unknown and therefore cannot be incorporated into current models. Similarly, not much is known about the contribution of methanotrophs to the methane turnover in oxic surface waters. To stimulate the discussion on recent advancements and uncertainties in the aquatic methane cycle, we invite abstracts discussing any aspect of methane production and oxidation in oxic surface waters as well as resulting atmospheric fluxes.

SS07 Impacts of microbial evolution on the ocean

Ramunas Stepanauskas, Bigelow Laboratory for Ocean Sciences, rstepanauskas@bigelow.org
Gerhard Herndl, University of Vienna, gerhard.herndl@univie.ac.at

Evolutionary processes of marine microorganisms have been transforming world’s oceans since the emergence of life. The rise of photosynthesis and Eukarya are some of the dramatic examples of the impact of microbial evolution over geological time scales. However, mutations, horizontal gene transfer and selection also affect current microbial responses to natural stressors, such as nutrient limitation, viral predation and grazing. Anthropogenic stressors, such as increasing temperature, decreasing pH and altered food webs as a consequence of global change are expected to influence the evolution of individual microbial taxa and consequently, marine microbial communities. However, such ongoing evolutionary processes remain enigmatic, and their studies will require detailed analyses of single microbial taxa under changing environmental conditions as well as investigations on the community level with a deeper integration with biogeochemistry. Our session will focus on the recent breakthroughs and ideas related to the impact of microbial macro- and micro-evolution on marine ecosystems.

SS08 Carbon fluxes in a changing Arctic across physical, chemical and microbial scales

Michael Cunliffe, Marine Biological Association (UK), micnli@mba.ac.uk
Anja Engel, GEOMAR, aengel@geomar.de
Gandois Laure, EcoLab - Laboratoire d'Ecologie Fonctionnelle et Environnement, laure.gandois@toulouse-inp.fr
Kumiko Azetsu-Scott, Bedford Institute of Oceanography, kumiko.azetsu-scott@dfo-mpo.gc.ca
Scott Zolkos, Woodwell Climate Research Center, szolkos@woodwellclimate.org
Karl Kaiser, Texas A&M University, Galveston, kaiserk@tamu.edu
Ranier Amon, Texas A&M University, Galveston, amonr@tamug.edu

In this session we aim to bring together diverse research communities working on carbon cycle topics in the Arctic Region, including high latitude forest and soil scientists, limnologists, oceanographers, atmospheric scientists, biogeochemists and microbial ecologists, both observers and modelers. The Arctic is experiencing rapid climate change with large and measurable effects on the carbon cycle. Last year was characterized by extremely warm spring temperatures in Siberia moving the snowmelt season up by several weeks. At the same time the Arctic Ocean showed the second lowest summer sea ice extent on record and is displaying signs of ‘Atlantification’ of the Barents Sea and Fram Strait. These changes are modifying the microbial base of Arctic ecosystems. This suite of interconnected physical, chemical, and biological changes reflect complexity of the changing Arctic and underscores the need for multidisciplinary research to understand carbon cycle implications. We therefore welcome a broad spectrum of contributions related to carbon fluxes in the Arctic, from organic carbon to inorganic carbon and greenhouse gases, connecting the forests and watersheds with the coastal and open Arctic Ocean as well as the atmosphere. Overarching themes are a.) the role of the Arctic Region for the global carbon cycle and climate change (e.g. through feedback loops involving carbon and freshwater), b.) the consequences of changing hydrologic regimes, vegetation productivity, and terrestrial-aquatic linkages for carbon cycling across the land-freshwater-marine continuum, and c.) linking the different components of microbial life in the Arctic with the biogeochemical processes that they undertake. We see this session as a home to showcase results from ongoing multinational Arctic research programs, including the UK/German Changing Arctic Ocean program, the MOSAiC expedition, the Synoptic Arctic Survey and the Arctic GRO program, to name a few. We hope to initiate a longer-term representation of Arctic Region carbon flux research at ASLO meetings to stimulate the exchange between the disciplines and generations.

SS09 Basal Metazoa - microbe interactions in the present and future ocean

Tinkara Tinta, Marine Biology Station, National Institute of Biology, Slovenia, tinkara.tinta@nib.si
Bettina Glasl, Division of Microbial Ecology, Department of Microbial Ecology and Ecosystem Science, University of Vienna, bettina.glasl@my.jcu.edu.au
Gerhard J Herndl, Microbial Oceanography Group, Department of Functional and Evolutionary Ecology, University of Vienna, gerhard.herndl@univie.ac.at

Fossil evidence of Cnidaria, Ctenophora and Porifera dates back to the Cambrian period. Since then, these phyla have developed various life forms and lifestyles, which enables them to dwell in nearly all habitats of the global ocean. This miscellaneous group of marine invertebrates is characterized by an astonishing biochemical variability of their building blocks and compounds they can release/excrete into their surrounding environment. The distinct characteristics of Hydrozoa, jellyfish, ctenophores, corals and sponges in their lifestyle, the biochemical composition of their biomass, and/or of excreted compounds, promote a broad range of microbial interactions. Microbial assemblages associated with cnidarians, ctenophores and sponges are extremely diverse both in terms of their composition and their function. Furthermore, the interactions of these phyla with microbes can range from a holobiont to the ecosystem scale. Projected future ocean conditions (i.e., warming, acidification, oxygen loss, and the increasing human exploitation of the ocean’s services, such as overfishing, maritime transport, increase of marine-based infrastructures) are likely to affect these organisms and their microbial interactions to a variable extent. For example, the adaptive features of jellyfish (cnidarian jellyfish, Hydrozoa and ctenophores) will probably allow them to flourish under projected future changes of the oceanic habitats. In contrast, corals are severely threatened by the effects of climate change leading to an unprecedented loss of tropical coral reefs around the world. Marine sponges have been hypothesized to benefit from the projected future ocean conditions, however, the function and diversity of sponges are likely to change in the future ocean with potential cascading effects on the ecosystem. This session welcomes studies investigating the interactions of cnidarians, ctenophores and sponges with microbes ranging from the level of holobionts to large-scale interactions with ambient microbial communities and its propagating consequences on ecosystem functioning, food web structures, and the biogeochemical state of marine ecosystems. In particular, we seek studies investigating these relationships/interactions in the context of the future changes, i.e., increasing seawater temperature, change of salinity and nutrients regimes, and changes of food web structures (e.g. introduction of invasive species).

SS10 Fate and Effects of Microplastics Across Aquatic Environments

Meredith Seeley, Virginia Institute of Marine Science, meseeley@vims.edu
Bongkeun Song, Virginia Institute of Marine Science, songb@vims.edu
Robert Hale, Virginia Institute of Marine Science, hale@vims.edu
Montserrat Compa, Instituto Español de Oceanografía, montse.compa@ieo.es
Carme Alomar, Instituto Español de Oceanografía, Spain, carmen.alomar@ieo.es

In recent years, microplastics have emerged as one of the most ubiquitous aquatic contaminants. The magnitude of the problem is exacerbated by the persistence of plastic in oceans and freshwater environments, as well as its ability to traverse geographic and political borders. As such, collaboration and cooperation across diverse groups of people is critical for tracking and elucidating adverse impacts of microplastics and nanoplastics. This session invites people from across the globe to share research on the fate and effects of microplastics and nanoplastics in aquatic environments. Topics of interest include research that describes and assesses the ingestion of plastics (mainly microplastics) and associated physiological effects, toxicity to or interactions with aquatic organisms from in vitro or in vivo work, and assessments the implications for coastal aquatic ecosystems. Research that highlights previously unreported ecosystem effects or research from local (Mediterranean Sea) or underrepresented locales is of particular interest. Researchers from the Mediterranean Sea with experience studying impacts of marine litter on species and ecosystems will give keynote talks. In addition, emerging work on nanoplastics will be included. Through poster and platform presentations, researchers across disciplines (biology, microbiology, chemistry, physical oceanography) and systems (oceans, estuaries, lakes, rivers) will be able to collaborate towards improved understanding of plastic pollution. For example, comparing data on the physiological effects caused by the ingestion of plastics and associated contaminants at species levels is essential to further understand the implications at population and ecosystem level. Such interdisciplinary and international cooperation is essential for developing sustainable solutions to plastic pollution. This session should be of interest to anyone who is studying microplastics and nanoplastics, or whose study area/discipline may be affected by ever-increasing plastic pollution.

SS11 From meta-system theory to the sustainable, adaptive management of freshwaters in the Anthropocene

Nuria Cid Puey, INRAE, Lyon, France, nuria.cid-puey@inrae.fr
Thibault Datry, INRAE, Lyon, France, thibault.datry@inrae.fr
Jonathan Tonkin, Univ. Canterbury, New Zealand, jonathan.tonkin@canterbury.ac.nz

Freshwaters are hotspots of biodiversity and provide essential ecosystem functions and services but are heavily threatened globally. Most existing policies driving their conservation, restoration and biomonitoring practices focus on local-scale approaches and measures, as a legacy of the persuasive niche paradigm that has prevailed in ecology for decades. The meta-system theory acknowledges that, in addition to local ecological processes, those occurring at the regional scale, such as the dispersal of organisms, and spatial flows of material and energy are fundamental for maintaining biodiversity and ecosystem functioning in freshwater ecosystems. This recently emerged paradigm highlights the need to update policy and management of freshwaters worldwide.   This session welcomes contributions aiming at translating the meta-system paradigm into practical, management recommendations for freshwaters and specific suggestions for improving environmental and conservation policies. We aim to highlight new research linked to management examples and policy-oriented findings that consider ecological processes at the regional scale to halt and/or reverse the ongoing loss of biodiversity in freshwaters and the growing deficits in ecosystem services they provide. We encourage contributions on conservation, restoration and/or biomonitoring considering the interaction of local and regional scale processes conducted in different types of freshwater ecosystems. This may include presentations on conservation planning and restoration efforts considering different biodiversity facets, ecosystem processes and services, applied metacommunity and population ecology, environmental flows and dam management. We also encourage water managers to present in our session. Depending on the submissions, a Special Issue in an environmental management international journal will be considered.

SS12 Understanding (mal)adaptations to environmental change

Celia Symons, University of California, Irvine, csymons@uci.edu
Kimberley Lemmen, Netherlands Institute of Ecology (NIOO-KNAW), k.lemmen@nioo.knaw.nl

The negative effects of anthropogenic change on biodiversity have led to increased interest and urgency to understand adaptation to local environmental conditions. Aquatic systems are particularly vulnerable to environmental change as they are directly impacted by human activities, and incorporate changes that occur within their catchment. With a rapidly changing environment and a potentially limited ability to disperse, adaptation may be important for persistence. To reach the goal of a sustainable future, we require a better understanding of (mal)adaptation (the continuum of fitness variation, from suboptimal to optimal), including, but not limited to, the following questions: When and how will organisms have a (mal)adaptive response to a novel environment? What controls the ‘adaptability’ of populations? How much do responses rely on mutational genetic variation rather than the reshuffling of preexisting variation? Do heritable non-genetic mechanisms play a role in (mal)adaptive phenotypic change? And how much of the stability and function of aquatic ecosystems relies on ongoing evolutionary processes? Contributions to this session will focus on eco-evolutionary questions regarding if/how organisms will respond to aquatic environmental change. We encourage submissions that integrate across biological (e.g., genotype to phenotype, individuals to ecosystems), and spatial scales (e.g., local, regional, and global). We also encourage work from a broad range of methodologies (e.g., resurrection ecology, experimental evolution, quantitative genomics, and long term monitoring studies).

SS13 Plankton diversity and ecosystem functioning in aquatic ecosystems

Bingzhang Chen, University of Strathclyde, bingzhang.chen@strath.ac.uk
Friederike Prowe, GEOMAR Helmholtz Centre for Ocean Research Kiel, fprowe@geomar.de
Christiane Hassenrück, University of Bremen, chassen­rueck@marum.de
Aleksandra Lewandowska, University of Helsinki, aleksandra.lewandowska@helsinki.fi

It has been firmly established in terrestrial and benthic systems that biodiversity is a strong determinant of ecosystem functioning, such as productivity and nutrient recycling. In the Anthropocene, the observed drastic loss of biodiversity has led to the concern that this loss may result in a significant impairment of ecosystem functioning. In aquatic ecosystems, element cycling, trophic transfer and metabolic balance are governed by dynamics within the plankton. They support almost half of the global primary productivity and play indispensable roles in regulating atmospheric CO 2 concentrations. Plankton are taxonomically and functionally diverse. However, whether this high diversity plays a role in determining ecosystem functioning is not clear, as links between species identity and function are not well established. In this session, we welcome contributions that can advance our understandings on the links between biodiversity and ecosystem functioning and services.. The study approaches may include, but are not limited to, theoretical modelling, laboratory and field experiments, as well as large-scale surveys. Both freshwater and marine studies are welcome. We particularly invite studies that use trait-based and molecular approaches, those that address multiple ecosystem functions or multiple trophic levels, and those that use an integrated approach combining insights from both theory and experimental studies. Of special interest are interdisciplinary studies linking biodiversity research to societal needs, such as assessing plankton diversity-driven ecosystem responses to climate change and water quality management.

SS14 Blue Carbon science for a sustainable future

Oscar Serrano, Edith Cowan University, o.serranogras@ecu.edu.au
Nuria Marba, Mediterranean Institute for Advanced Studies, CSIC-UIB, Spain, nmarba@imedea.uib-csic.es
Vanessa Hatje, Universidade Federal da Bahia, Brazil, vanessahatje@gmail.com
Isaac Santos, University of Gothenburg, Sweden and National Marine Science Centre, Australia, Isaac.Santos@scu.edu.au
Dorte Krause-Jensen, Aarhus University, Denmark, dkj@bios.au.dk
Carol Robinson, University of East Anglia, carol.robinson@uea.ac.uk
Ruth Parker, Centre for Environment, Fisheries and Aquaculture Science, UK, Ruth.Parker@cefas.co.uk
Alice Newton, University of Algarve, Portugal, anewton.ualg@gmail.com
Prateep Kumar Nayak, University of Waterloo, pnayak@uwaterloo.ca

Blue Carbon constitutes one of the largest global reservoirs of carbon, and refers to the carbon sequestered long-term by any marine habitat or biogeochemical process in coastal and deep-sea systems. Hence, in addition to the biomass and soil carbon stocks below mangroves, tidal marshes, seagrass meadows and macroalgae, Blue Carbon includes particulate and dissolved carbon exported and sequestered in shelf and deep-sea sediments and the deep ocean. Blue Carbon ecosystems also make an important contribution to the social and economic development of coastal communities, whose role in the in-situ preservation and conservation of Blue Carbon is critical. While earlier studies focused on biological tissues and detritus, it is increasingly apparent that dissolved inorganic and organic carbon also play major roles. However, there are still important knowledge gaps regarding carbon dioxide, methane and nitrous oxide fluxes in climax, restored and disturbed habitat conditions, and little is known about non-conventional Blue Carbon habitats such as intertidal sand- and mudflats, macroalgal beds, coastal swamp forests, shelf, slope and deep ocean sediments, and export and sequestration of dissolved organic and inorganic carbon. In addition, understanding of how climate change influences greenhouse gas fluxes in Blue Carbon ecosystems is still lacking. Reducing these uncertainties and knowledge gaps is important to inform valuation of Blue Carbon ecosystems and thus their inclusion in policy and management scenarios. A stronger scientific framework is needed to document the full potential of Blue Carbon as a viable nature-based solution to mitigate and adapt to climate change. Blue Carbon resource assessments are crucial to inform national carbon inventories, and preserving or restoring Blue Carbon habitats can help countries to achieve their Nationally Determined Contributions. In addition to economic value, the social and cultural value of Blue Carbon ecosystems are important, including how Blue Carbon facilitates Nature’s Contribution to People and a range of Ecosystem Services in a variety of coastal-marine social-ecological systems. The assessment of current policy and management actions in terms of how well they enable the maintenance and development of the services provided by, and economic value of, Blue Carbon ecosystems including their use in accounts of natural capital, is important. Such management measures could include the restoration/recreation of coastal habitats or potential use of offshore marine protected areas to facilitate reductions in disturbances such as trawling. The development of novel governance approaches that prioritise Blue Carbon is also to be encouraged, as is a better understanding of the potential trade-offs between Blue Carbon and a growing blue economy. The growing Blue Carbon community encompasses limnologists and oceanographers, biologists, socio-ecologists, biogeochemists, geographers, soil scientists, conservationists, economists, governance experts and policy makers. This session invites contributions that present the latest developments in the interdisciplinary field of Blue Carbon, with the aim to assess the current state of the art in Blue Carbon research and policy and suggest the next priorities for interdisciplinary collaboration and focus. Full manuscripts related to presentations in this session will be considered for a Special Issue being organized in the Journal of Limnology & Oceanography.

SS16 Microbe-organic matter interactions in aquatic systems: Advances and challenges

Maria Montserrat Sala, Institut de Ciències del Mar (CSIC), msala@icm.csic.es
Andrew D. Steen, Departments of Microbiology and Earth and Planetary Sciences University of Tennessee - Knoxville, asteen1@utk.edu
Gerhard J. Herndl, Dept. of Functional and Evolutionary Ecology, Bio-Oceanography Unit. University of Vienna, Austria, gerhard.herndl@univie.ac.at
Eva Ortega-Retuerta, CNRS Laboratoire d'Océanographie Microbienne, France, ortegaretuerta@obs-banyuls.fr
Helena Osterholz, Leibniz Institute for Baltic Sea Research Warnemuende, helena.osterholz@io-warnemuend.de
Jutta Niggemann, Research Group for Marine Geochemistry (ICBM-MIP Briding Group), University of Oldenburg, jutta.niggemann@uni-oldenburg.de

Knowledge of dynamic interactions between organic matter (both dissolved and particulate) and microbial communities is critical to draw the routes of organic matter degradation or transformation, but also to understand the evolution and succession of microbial communities in ecosystems. Microorganisms are key mediators in the formation, transformation, and storage of organic matter in all aquatic environments such as marine, freshwater, and sediments. At the same time, organic matter provides the energetic foundation for the growth of heterotrophic microorganisms, affecting their community structure and metabolic potential. The combination of ”omic”-based approaches with novel analytical methods has revolutionized our ability to probe the interactions between marine microbial communities and organic matter. However, new interdisciplinary approaches are needed to move from this descriptive level to a better quantitative, process‐level understanding of the roles of microbes in biogeochemical cycles. In this session, we will explore and discuss recent advances and limitations of how organic matter (dissolved molecules, colloids, gels and particles) and microorganisms (bacteria, archaea, protozoa, fungi) can be integrated into our understanding of biogeochemical cycles to better predict functional diversity patterns, fluxes of matter (C/N/S/P…), and the impact of environmental change across microbial aquatic systems. We need to nurture cooperation between organic biogeochemists and microbial ecologists, between freshwater and marine scientists, between lab bench and computational data analysts, and include scientists from different fields who are interested in advancing the progress at the intersection of microbiology and organic matter biogeochemistry.

SS17 Unravelling the ecology and biogeochemistry of the mesopelagic zone

Martí Galí, Barcelona Supercomputing Center, marti.gali.tapias@gmail.com
Sari Giering, National Oceanography Centre, s.giering@noc.ac.uk
Steph Henson, National Oceanography Centre, shen@noc.ac.uk
Joan Llort, Barcelona Supercomputing Center, joan.llort@bsc.es

The mesopelagic layer of the oceans, also known as the “Twilight Zone”, extends between the bottom of the sunlit upper ocean and 1000 m depth, and it is one of the largest contiguous ecosystems on Earth. It plays a pivotal role in global biogeochemical cycles and climate, acting as the gateway to long-term carbon and organic matter storage, and hosts a massive biomass of zooplankton and fish. However, progress in understanding and predicting the biogeochemical processes in the mesopelagic zone has been slow, primarily due to the difficulty of exploring such a remote and expansive environment. This lack of quantitative understanding has societal and economic costs: it introduces uncertainty in estimates of oceanic carbon storage (which inform policies for the reduction of carbon dioxide emissions), and might soon hamper sustainable management of mesopelagic biological resources (threatened by imminent exploitation). A number of recent developments are unveiling key aspects of the ecology and the biogeochemical functioning of the mesopelagic zone. Bio-optical sensors mounted on autonomous robots (e.g. biogeochemical Argo floats and gliders) now enable year-round quantification of suspended and sinking particles; the abundance and biomass of mesopelagic metazoans can be assessed with underwater imaging techniques combined with artificial intelligence; acoustics reveal the biomass and diel vertical migration dynamics of zooplankton and fish and the factors regulating the formation of deep scattering layers; meta-omics and other molecular techniques unravel the phylogenetic composition and trophic links  of mesopelagic organisms (from microbes to fish); and the synthesis of observations and their distillation into numerical models is getting us closer to understanding how this important ecosystem functions, and closing the elusive mesopelagic carbon budget. These are exciting times for the exploration of the Twilight Zone. In this session we invite contributions covering all aspects of mesopelagic ecology and biogeochemistry. The session is organised by JETZON (Joint Exploration of the Twilight Zone Ocean Network) and open to all members of the community.

SS18 Greenhouse Gas Dynamics in the Coastal Ocean – Emerging Trends and Future Directions

Robinson Fulweiler, Boston University, rwf@bu.edu
Alia Al-Haj, Boston University, aalhaj@bu.edu
Nicholas Ray, Stockholm University, Nicholas.Ray@aces.su.se
Judith Rosentreter, Southern Cross University, Yale University, Judith.Rosentreter@scu.edu.au
Damien Maher, Southern Cross University, Damien.Maher@scu.edu.au

The coastal ocean is a dynamic ecosystem that plays an important, yet poorly constrained, role in global greenhouse gas budgets. Recent work on a variety of coastal habitats including salt marshes, mangroves, seagrasses, estuaries, and inter-tidal sediments demonstrates the possibility for both uptake and release of substantial amounts of CO 2 , CH 4 , and N 2 O. Importantly, these studies highlight the high variability and uncertainty associated with coastal greenhouse gas flux rates, our limited understanding of the environmental controls on these fluxes, and a lack of knowledge of the underlying mechanistic processes driving net fluxes. The goal of this session is to bring together scientists studying greenhouse gas (i.e., CO 2 , CH 4 , and N 2 O) fluxes from a variety of coastal environments to present their latest findings. We welcome scientists using a range of techniques – including direct gas measurements, environmental -omics, laboratory experiments, and modelers. We specifically want to explore how coastal greenhouse gas fluxes vary across spatial and temporal (e.g. tidal, diurnal, seasonal, inter-annual) scales. In particular, we welcome studies that focus on how anthropogenic pressures (e.g. sea level rise, eutrophication, low oxygen conditions) alter coastal greenhouse gas fluxes. Ultimately, we see this session as an opportunity to discuss how to best quantify greenhouse gas fluxes in the coastal zone to better inform global greenhouse gas budgets and blue carbon policies.

SS19 Securing biodiversity, functional integrity and ecosystem services in drying aquatic ecosystems

Thibault Datry, INRAE, thibault.datry@inrae.fr
Núria Catalán García, USGS-Boulder USA/LSCE-CNRS, France, ncatalangarcia@gmail.com
Lisette de Senerpont Domis, Netherlands Institute of Ecology, L.deSenerpontDomis@nioo.knaw.nl
Soren Brothers, Utah State University, soren.brothers@usu.edu

Most of the world’s river networks and inland waters comprise naturally intermittent and ephemeral aquatic ecosystems, which are a partially or entirely drying out at some time of the year. These prevalent ecosystems support high biodiversity, crucial biogeochemical cycles and provide key ecosystem services to society. However, in response to global change, the incidence of drying is dramatically increasing in time and space, altering the flow regimes of river networks and entirely drying out many lakes and reservoirs. In recent years, the effects of drying on the biodiversity-function-services cascade have gained attention at the local scale in these ecosystems, yet this phenomenon has been poorly considered at larger spatial scales. This lack of knowledge about how drying may shape regional-scale fluxes prevents us from predicting how global change will alter river network biodiversity, ecosystem functions and services, and how this affects public values and perceptions of such services. For example, little is known about the spatial-temporal variability of ecosystem functions across wet and dry phases, although dry phases could have disproportionate effects on carbon or nitrogen cycles. Similarly, the biodiversity of these ecosystems is generally considered locally and for aquatic organisms only. Last, despite recent advances in remote sensing, estimates of the extent of drying in inland waters are lacking. In this session, we welcome studies that investigate how global change cascades on to biodiversity, ecosystem functions and ecosystem services of drying aquatic ecosystems. These may include novel efforts from eco-hydrology, biogeochemistry, community ecology, socio-economy, policy, modelling and water management from all continents. A time dedicated to early career scientists will be considered to form a forum for further collaborations and capacity-building on drying aquatic ecosystems.

SS21 Microbial Interactions with Plastic: Implications for aquatic pollution, carbon cycling, and human and environmental health

Linda Amaral-Zettler, NIOZ Royal Netherlands Institute for Sea Research / Univ. of Amsterdam, Netherlands, linda.amaral-zettler@nioz.nl
Tracy Mincer, Harbor Branch Oceanographic Institute, Florida Atlantic University, USA, tmincer@fau.edu
Helge Niemann, NIOZ Royal Netherlands Institute for Sea Research / Univ. of Utrecht, Netherlands, helge.niemann@nioz.nl

The impact and fate of plastic litter in the environment is a high priority topic in the aquatic sciences, but the role of microbes in this growing anthropogenic threat has only been recognized over the last decade or so. Basic questions such as whether there is a core microbiome associated with plastic, whether any of these are harmful, and how microbes influence the ultimate fate of plastic remain unanswered. The realization that floating plastic debris represent only a small fraction of the plastic in aquatic environments underscores the need to develop new sample collection, processing, and analysis techniques to resolve all size classes from micro- to nanoplastic, and to constrain plastic distribution and its fate from near to offshore and surface to deep sea environments. This session will bring together the latest research on the interaction between microbes and plastic, and how these interactions influence the breakdown, sinking, and ingestion of plastic, as well as how the microbial “Plastisphere” contributes to carbon cycling, chemical transformations, and ecosystem functions in aquatic environments. A range of presentations and approaches will demonstrate the value of combining results from culturing, -omics, chemistry, and advanced imaging techniques to study how microbes respond to and alter the surfaces and properties of different plastics, both in both field and experimental systems. This is a timely topic for the theme of this ASLO meeting: “Aquatic Sciences for a Sustainable Future: Nurturing Cooperation”, because to ensure a sustainable future, the global community will need to work together to reduce the increasing flow of plastic pollution into aquatic systems.

SS22 Advancing environmental DNA interpretation: The fate and transport of a molecule at the nexus of biology, chemistry and physics in aquatic systems

Elizabeth Andruszkiewicz Allan, Woods Hole Oceanographic Institution, eallan@whoi.edu
Taylor Wilcox, National Genomics Center for Fish and Wildlife Conservation, taylor.m.wilcox@gmail.com
Lauren Sassoubre, University of San Francisco, lsassoubre@usfca.edu
Kristy Deiner, ETH Zurich, alpinedna@gmail.com

The use of environmental DNA (eDNA) for biodiversity assessments has drastically altered how aquatic species and ecosystems can be monitored and managed. The field of eDNA has exploded over the last two decades, largely due to its non-invasive nature and ease of sampling compared to traditional survey methods. Researchers worldwide are applying eDNA sampling methods to infer the presence of aquatic organisms from freshwater ponds to open ocean habitats. Several “proof of concept” studies have demonstrated that eDNA sampling can census rare and diverse taxa and communities by capitalizing on the latest advancements in molecular biology and metagenomics technologies. However, a deeper understanding of the ecology of eDNA is needed before eDNA sampling can be widely utilized as a biomonitoring tool. Currently, the interpretation of results is limited by uncertainty regarding spatial and temporal resolution of eDNA signals. This topic is particularly relevant for Aquatic Science Meeting contributors and attendees as eDNA fate and transport is at the nexus of biology, chemistry, and physics in aquatic systems. We welcome contributions that focus on improving the interpretation of eDNA signals, including insights on eDNA state/form, shedding, decay, suspension/resuspension, transport, etc. in any aquatic environment. Studies using both single-taxon and/or multi-taxa approaches are encouraged. The goal of the session is to advance our understanding of how eDNA molecules behave in the environment and thus move the field of eDNA forward in its ability to address ecological research questions in a range of aquatic environments.

SS23 Biogeochemical cycling from catchments to coastal waters: processes, models and budgets

Michael Seidel, University of Oldenburg, m.seidel@uni-oldenburg.de
Nicholas D. Ward, Pacific Northwest National Laboratory, nickdward@gmail.com
Sairah Y. Malkin, University of Maryland, smalkin@umces.edu
Patricia M. Medeiros, University of Georgia, medeiros@uga.edu
Estela Romero, Universitat Autònoma de Barcelona, CREAF, estela.romero@creaf.uab.cat
Josette Garnier, French National Centre for Scientific Research (CNRS), josette.garnier@upmc.fr
Wolfgang Ludwig, Université de Perpignan Via Domitia, CEFREM (CNRS-UPVD), ludwig@univ-perp.fr
Dennis Swaney, Cornell University, dps1@cornell.edu

In this era of global change, accelerated rates of cycling of carbon, nutrients and other materials are increasingly evident, with increased loading due to changes in human activity, land use change, and population shifts, as well as changes in biogeochemical processes due to increased frequency of extreme events (hurricanes, fires, etc.). This has particular relevance to coastal waters and their watersheds, which are particularly subject to the impacts of anthropogenic changes. It is therefore crucial to understand the relationships between anthropogenic drivers, biogeochemical fluxes, and ecosystem processes, including microbial processing. In this session, we aim to host presentations that span a range of topics integrating ecosystems from a wide range of geographical settings and spatiotemporal scales, including carbon and nutrient fluxes across the land-ocean-continuum: biogeochemical transformations in rivers, coastal wetlands, groundwater, estuaries, and marine coastal waters. We solicit submissions that seek to explain mechanisms underlying observed patterns in the distribution and rates of biogeochemical processes, including carbon and nutrient cycling and their linkages to ecosystem production and microbial community composition. We also encourage presentations on methodological developments, including modelling and accounting methodologies that use accessible data resources and new or existing analytical frameworks to shed light on “new” nutrient sources, legacy sources, and their regional variation. Presentations that provide tools that support environmental management and policy priorities, relating human activities to environmental consequences, are welcome.

SS24 Aquatic microbial structure and function across spatiotemporal scales

Michaela de Melo, Université du Québec à Montréal, michaelaldemelo@gmail.com
Pedro Junger, Universidade Federal de São Carlos, pedro.junger@gmail.com
Ramiro Logares, Institut de Ciències del Mar (ICM), CSIC, ramiro.logares@icm.csic.es

Understanding how microbiomes are spatio-temporally structured and how their structure affects ecosystem function are central questions in aquatic microbial ecology that so far have been partially answered. A particular challenge is to attain a mechanistic understanding of microbial community assembly. Recent works have investigated how ecological processes (i.e. selection, drift, and dispersal) shape microbial communities over spatio-temporal scales in distinct aquatic ecosystems. However, much less is known about the connections between the processes that structure communities, the microbial assemblages that are formed, and the ultimate effects of structuring mechanisms on ecosystem function across variable spatial (from micrometers to thousands of kilometers) and temporal scales (e.g. hourly, diel, seasonal, inter-annually and over decades). Microbial features, such as minute organismal size, high dispersal, potential dormancy, high reproductive rates, huge population sizes and potentially high adaptability to environmental change need to be considered when investigating the links between ecological processes, microbial community composition, and indicators of overall ecosystem function (e.g. primary production, organic matter decomposition, nutrient cycling and gas emissions). A major goal is to comprehend how the composition of microbiomes will be affected by changes in abiotic and biotic drivers induced by global change, and how these changes will affect main ecosystem processes. We welcome abstracts investigating the structure of aquatic microbiomes, the underlying processes shaping them, and the potential effects in ecosystem function across diverse spatio-temporal scales in freshwater or marine ecosystems.

SS25 Underwater Fluxes of biogenic constituents and their Ecological Implications

Carmen Castro, Instituto de Investigaciones Marinas (IIM - CSIC), cgcastro@iim.csic.es
Pierre Polsenaere, IFREMER, Pierre.Polsenaere@Ifremer.fr
Peter Berg, University of Virginia, pb8n@virginia.edu

Quantitative knowledge on fluxes of carbon, oxygen, and other constituents are critically important for understanding marine and freshwater ecosystems. Aquatic fluxes across boundaries (e.g. sediment-water, air-water, mid-water column density layers) are highly relevant in the study of biogeochemical processes, carbon budgets and sequestration, and ecosystem health on a local to global scale. This session invites contributions that present new ecological results involving process and flux studies over heterogeneous and dynamic coastal systems (e.g. tidal bays, marshes, mangroves, fjords, estuaries). Work focusing on spatial and temporal variability of fluxes, their magnitudes, controls, and ecological implications are welcome. We also invite presentations on methodological advances for determining fluxes, including new and integrative in situ and modeling approaches.

SS26 Adventures, Challenges, and Benefits of Conducting International Collaborative Research

Eilea Knotts, Association for the Sciences of Limnology and Oceanography, eilea.knotts@gmail.com
Adrienne Sponberg, Association for the Sciences of Limnology and Oceanography, sponberg@aslo.org
Adina Paytan, University of California, Santa Cruz, apaytan@ucsc.edu
Mike Pace, University of Virginia, mlp5fy@virginia.edu
Linda Duguay, University of Southern California, duguay@usc.edu

Aquatic sciences are increasingly global in nature, transcending political boundaries and requiring collaborations with foreign scientists along with working in other countries. Planning and executing collaborative research projects overseas, however, is not trivial. Challenges including identifying and communicating with scientists in a different country, obtaining funding for international work, overcoming technical obstacles such as shipping, permits, and dealing with language and cultural barriers, are just a few examples. In this session we invite participants at all stages of their career to share their experiences and lessons learned from both productive and not so successful adventures in conducting international collaborative research in aquatic sciences. We seek presentations on international collaboration related to funding, identifying collaborators, executing projects, overcoming obstacles, developing teams, leveraging mutual advantages and infrastructure, handling difficulties, and successful outcomes. We hope that this exchange will help others avoid pitfalls and take advantage of opportunities and increase the likelihood for effective and fun international collaborations in the aquatic sciences.

SS27 Mainstreaming inter- and transdisciplinary research: social sciences approaches applied to aquatic ecosystems

Pablo Rodríguez-Lozano, GLOWATER Research Group, Universitat de les Illes Balears, Palma, Spain, pablo.rodriguez@uib.es
Irene Iniesta-Arandia, Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain, irene.iniesta@uab.cat
Dídac Jorda-Capdevila, Catalan Institute for Water Research (ICRA), Girona, Spain, dd.joca@gmail.com
Cristina Quintas-Soriano, Faculty of Organic Agricultural Sciences, University of Kassel, Germany, cquintassoriano@gmail.com

The conservation and management of aquatic ecosystems cannot be achieved without considering human perceptions, actions, and interests around these systems. It is necessary to generate a new science that is capable of responding urgently to the sustainability challenge: researchers must interact with social actors to produce knowledge that is truly credible and applicable to ecosystem management, based on their recognition as socio-ecological systems. This session aims putting together current research that incorporates methodologies from the social sciences and humanities in the study of aquatic ecosystems. The session aims to include, but is not limited to: social perception studies, stakeholders’ views, environmental history approaches, social media analysis, multiple values studies, monetary and non-monetary valuations, aesthetics studies, and citizen science. We welcome all innovative, interdisciplinary and transdisciplinary studies, those that combine natural and social sciences, especially research that blurs the boundaries between disciplines. The session will promote mutual learning among participants, hoping to lead into future collaborations. A bigger and more inclusive picture of aquatic ecosystems will provide a better understanding of these complex ecosystems, which should be the base for actionable management outcomes.

SS28 Aquatic microbial community structure and dynamics: new insights from non-destructive high throughput automated single-cell analysis.

Luis Felipe Artigas, Laboratory of Oceanology and Geosciences - CNRS UMR 8187 - University of Littoral Cote d'Opale (ULCO) - Wimereux - FR, felipe.artigas@univ-littoral.fr
Véronique Créach, Center for Environment Fisheries and Aquaculture Science (CEFAS) - Lowestoft - UK, veronique.creach@cefas.co.uk
Melilotus Thyssen, Mediterranean Institute of Oceanology (MIO) - CNRS UMR 7294 - Marseille - FR, melilotus.thyssen@mio.osupytheas.fr
Mathilde Dugenne, School of Ocean and Earth science and Technology - University of Hawaïi at Manoa - Honolulu - USA, dugennem@hawaii.edu
Casotti Raffaela, Stazione Zooologica Anton van Dorn – Naples- IT, raffa@szn.it

In the past ten years, our understanding of aquatic microbial community structure and dynamics at fine spatio-temporal scale has greatly improved with the expanded integration of automated techniques. Hourly and km-scale studies in community structure are largely accessible, bringing new insights into marine ecosystem functioning and processes. For example, automated flow cytometers now provide high throughput measurements of cells/colonies optical signatures, resolving pico- to microphytoplankton functional groups. They can be used as indicators of changes in the ecosystem by following important dynamic processes such as microbial growth and decay. Interaction and successions between them are better understood, as their responses to environmental changes. When combined with imaging-in-flow, they also allow the assessment of coarse plankton taxonomical diversity and the detection of keystone species like harmful algae or invasive species. The new generation of instruments can be connected online and remotely operated in situ, installed in fixed or moving platforms (e.g buoys, research vessels, ships of opportunity). Together with bulk optical approaches (multi-spectral and variable/active fluorometry, in situ imaging and remote sensing) and low resolutive monitoring based on microscopy/pigment/molecular analysis, data sets are gathering incredible information for research purpose. Furthermore, surveys are crucial to develop comprehensive and connected programs that will evaluate the ecological status of aquatic systems adopted by national or international policy regulations as the EU Water and Marine Strategy Framework Directives (WFD & MSFD) and Regional Seas conventions (OSPAR, HELCOM). For this, interoperable procedures, automation in single-cell optical/imaging data analyses and common vocabulary on the main groups defined are required within national and international work on joint international coastal observatories (as the Joint European Research Infrastructure for Coastal Observatories JERICO-RI). We invite scientists and environmental managers to present and discuss their scientific results from high resolution datasets, methodological developments, inter comparison and/or implementation of high throughput techniques at single-cell level improving the knowledge of the aquatic systems. Scientific and analytical topics of this session include a broad spectrum from study of microorganisms distribution and dynamics thanks to high spatial resolution and/or high-frequency studies in aquatic systems, automation in data analysis as well as data-driven modelling of functional diversity.

SS29 Zooplankton mediation of particle flux

Susanne Neuer, Arizona State University, susanne.neuer@asu.edu
Leocadio Blanco-Bercial, Bermuda Institute of Ocean Sciences, Leocadio@bios.edu

The oceanic ‘biological carbon pump’, the export of dissolved and particulate organic carbon to the deep ocean, is a significant driver of the atmospheric carbon uptake by the oceans. It is driven mainly by the formation and sinking of particles of phytoplankton origin, as well as their use in the twilight zone, the zone below the euphotic zone. Zooplankton are known to play a major role in both the formation and consumption of sinking particles, mainly by their feeding activities and their production of sinking fecal pellets. These zooplankton communities consist of planktonic crustaceans, salps, pteropods or even protistan grazers, and consist of vertically migrating or resident populations of flux feeders in the twilight zone. Understanding the role of these zooplankton communities, both migrating and resident, in particle formation and midwater particle transformation is important for quantifying carbon export and attenuation, and with it the biological contribution to the ocean’s sequestration of organic carbon. In this interdisciplinary session that bridges zooplankton ecology with ocean biogeochemistry, we invite contributions that help bring together our current knowledge on the actions of these zooplankton communities, both from field and modeling studies, from marine and freshwater environments.

SS30 Species range shifts and biological invasions of marine ecosystems within the context of ocean warming

Andrea Anton, Institut Mediterrani d’Estudis Avançats, IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain, andrea.antongamazo@kaust.edu.sa
Marlene Wesselmann, Institut Mediterrani d’Estudis Avançats, IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain, m.wesselmann@imedea.uib-csic.es
Emma Cebrian, Centre d’Estudis Avançats de Blanes, Consejo Superior de Investigaciones Científicas (CEAB-CSIC), Blanes, Spain, emma@ceab.csic.es
Eugenia Apostolaki, Hellenic Centre for Marine Research (HCMR), Heraklion, Crete, Greece, eapost@hcmr.gr

Marine species are moving beyond their native geographical ranges in response to climate change and shifting abiotic conditions, establishing populations in higher latitudes. Similarly, species are introduced into new marine regions as a consequence of an increasingly connected world. The success of such marine species dispersal, either by a climate range shift or by human-mediated introductions, depends on the biotic interactions and environmental conditions at the recipient site and/or the capacity of species to adapt to these new conditions. The arrival of species to new regions can lead to ecological challenges for both the novel species as well as the recipient community; however, the magnitude and direction of the ecological effects are not well understood. Given the ecological similarities between species introductions and marine range shifts within the context of ocean warming, this session welcomes contributions from these two interconnected fields of work in order to disseminate the latest research advancements, and to crease synergies across disciplines. We aim to report shifts in species ranges and introductions to higher latitudes, to describe the mechanisms behind their ecological success (or failure) and to report the effects – ranging from positive to negative - on native species, communities and ecosystem services.

SS31 Imagine/Imaging the Ocean – Pelagic imaging for a sustainable future

Rainer Kiko, Sorbonne Université, rainer.kiko@obs-vlfr.fr
Margaux Noyon, Nelson Mandela University, Port Elizabeth, South Africa, Margaux.Noyon@mandela.ac.za
Rubens M. Lopes, Instituto Oceanográfico da Universidade de São Paulo, São Paulo, Brazil, rubens@usp.br

Plankton is the major driver of oceanic biogeochemistry and plays several essential roles in the ocean (oxygen production, carbon storage, food web input, etc.). Plankton is the food base for fish and the livelihood of millions of people depends on plankton dynamics. Blooms of harmful algae or jellyfish on the other hand endanger aquaculture or even energy production. Plastic particles also are nowadays observed in plankton samples and plastic pollution creates a major threat for marine life. To monitor plankton dynamics at a spatial and temporal scale that permits management of fisheries and aquaculture is therefore a global challenge for policy and society and should be a major goal for the UN Decade of Ocean Science for Sustainable Development. Plankton covers a size range from nanometers to meters and only optic tools allow to bridge this enormous span. An enormous toolkit of digital plankton cameras ranging from in situ microscopes to large high definition cameras has been developed and deployed in recent years. These enable us to monitor plankton of different size groups at an unprecedented scale and provide a new view on the spatial and temporal distribution of plankton biomass and diversity. First autonomous deployments are underway and real time analysis will enable the direct conversion of data into knowledge and policy advice. Pelagic imaging is at the edge to enter an operational stage where information on plankton, particle and plastics distribution from research vessels, gliders, floats, moorings and Citizen Scientists could be obtained, integrated and analyzed almost in real time. The benefits of an operational pelagic imaging system for society will be massive, as it will support the high-resolution prediction of food web dynamics, the monitoring of pollution events and therefore the sustainable use and protection of the Ocean. We invite contributions on pelagic imaging devices and datasets - including model development based on pelagic imaging - that showcase the scientific and societal benefits to spread such technologies and pave the path towards operationality. Likewise, contributions that deal with latest instrument and platform development, and the development of image recognition, data aggregation and data analyses algorithms (e.g. niche modelling, deep learning) are welcome.

SS32 Name that species: Toward a new global view of species diversity of marine zooplankton

Silke Laakmann, Helmholtz Insitute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB) and Alfred Wegener Institute, silke.laakmann@hifmb.de
Leocadio Blanco-Bercial, Bermuda Institute of Ocean Science, leocadio@bios.edu
Katja Peijnenburg, Naturalis Biodiversity Center and University of Amsterdam, k.t.c.a.peijnenburg@uva.nl
Ann Bucklin, University of Connecticut, ann.bucklin@uconn.edu

Knowledge of species diversity, distribution, and abundance of the marine zooplankton assemblage will continue to be a critical element for understanding and predicting the complex interconnected network of global ocean ecosystems. A species-level biodiversity baseline is essential for detecting and monitoring changes in marine systems due to climate change, commercial harvesting, deep-sea mining, and other events and activities. Integrative approaches, including morphological taxonomic, optical visualization, and molecular analysis are yielding promising results for both research and management applications. DNA barcoding and metabarcoding are central to ongoing initiatives to ensure accurate species-level identification of marine zooplankton. Best practices are that DNA sequences for specimens are identified by expert taxonomists, with archiving of voucher specimens, DNA, and photographs. These protocols will allow reliable assignment of DNA sequences to known species, as well as discovery of new species and detection of cryptic species. With advancements in high-throughput sequencing, DNA metabarcoding (i.e., large-scale taxonomic identification of complex samples via analysis of one or more DNA barcode regions) has produced millions of DNA sequences from environmental samples and has the potential to provide a comprehensive biodiversity assessment, including rare and cryptic species previously overlooked by traditional morphological taxonomic approaches. Geographically- and taxonomically-comprehensive high-quality reference barcode entries and databases are critically needed to allow and ensure that barcoding and metabarcoding analyses can discriminate, identify, and name recognized taxonomic units – ideally species – in assessments of zooplankton biodiversity. The session will address integrative morphological, optical, and molecular analysis of zooplankton assemblages across the globe, and contribute to the continued development of best-practices for reliable identification of marine zooplankton species for assessment of the pelagic assemblage.

SS33 Ecological genomics

Eric Dexter, The University of Basel, ericdaviddexter@gmail.com
Joana Santos, University of Basel, joana.santos@unibas.ch
Fabrizia Ronco, University of Basel, fabrizia.ronco@unibas.ch
Virginie Ricci, University of Basel, virginie.ricci@unibas.ch

Recent advances in DNA and RNA sequencing technology have enabled unprecedented access to genome-scale data across a wide range of organisms, and provided a powerful new tool for the examination of ecological and evolutionary questions in aquatic systems. This session will examine the manner in which genomic tools can illuminate the structure and function of aquatic communities and the ecological interactions of individual species. Example topics might include conservation genetics of threatened species, the genomic basis of functional traits such as salinity or temperature tolerance, metagenomic analysis of community composition, genomic reconstruction of demographic events, or disentangling cryptic species complexes. We additionally welcome contributions concerning advances in sequencing methodology, bioinformatics, statistical analysis, and theoretical aspects of ecological genomics as well.

SS34 Invertebrate-microbes associations and their relevance in biogeochemical processes: from loose relationships to intimate symbioses

Stefano Bonaglia, Department of Marine Sciences, University of Gothenburg (Sweden), stefano.bonaglia@su.se
Marco Bartoli, Parma University (Italy), marco.bartoli@unipr.it
Ugo Marzocchi, Aarhus University (Denmark), ugomar@bio.au.dk
Ulisse Cardini, Stazione Zoologica Anton Dohrn - National Institute of Marine Biology, Ecology and Biotechnology (Italy), ulisse.cardini@szn.it

Microorganisms play a primary role in regulating biogeochemical cycles in virtually all of our planet’s environments, particularly so in aquatic systems. While the role of free-living microbes in driving nutrient cycles has been extensively studied, less explored is the role of invertebrate-associated microbes. In particular, the overwhelming majority of aquatic animals are invertebrates, which cover a vast diversity of forms and functions. Such interactions between aquatic invertebrates and microbes encompass all degrees of intimacy: From loose (and diverse) relationships to intimate (and specific) symbioses. Invertebrates can harbour specific microbial communities in distinct microhabitats such as their digestive systems, gills or outer surface. In these host-microbe associations, also called holobionts, peculiar microbial communities thrive thanks to the host lifestyle and behaviour, providing these bacterial and archaeal communities preferential or exclusive access to electron donors and acceptors. These associations are increasingly found to have a conspicuous impact on both holobiont functioning and element cycling. Even though invertebrate-microbial associations are widespread in the aquatic environment, they remain largely understudied due to methodological limitations or lack of interdisciplinarity. This session will thus provide a forum for presenting both biogeochemical and molecular approaches, with the manifest aim of revealing the importance of these associations for element cycling and ecosystem processes in aquatic systems.

SS35 Controls and limits on freshwater productivity

Isabella Oleksy, Cary Institute of Ecosystem Studies, bellaoleksy@gmail.com
Chris Solomon, Cary Institute of Ecosystem Studies, solomonc@caryinstitute.org
Stuart Jones, University of Notre Dame, jones20@nd.edu

In an age of unprecedented global change, it is more important than ever for limnologists to refine our understanding of ecological processes in order to make predictions how freshwater systems will function into the future. Aquatic ecosystems are subjected to multiple concurrent stressors (e.g., warming, changing precipitation regimes, and associated nutrient and organic matter loads), which may have implications on production with cascading effects through the aquatic food web. Heterogeneity in hydrologic setting (e.g., morphometry and residence time in lakes, hydrological connectivity and watershed area in rivers) across and within regions complicate our efforts to understand these changes. However, in recent years, there has been a revolution in our understanding of limits and controls on primary production that account for both variation in light environment and load stoichiometry. Large, spatial studies and the advent of relatively affordable sensor technologies have also deepened our understanding of drivers of variability in metabolic regimes. Ultimately, improved understanding of the underlying mechanisms driving aquatic ecosystem productivity will allow for better predictions that can aid managers and decision makers into the future. In this session, we encourage field scale, laboratory, modeling, and predictive studies which investigate both basic (e.g., biogeochemical cycling) and applied (e.g., fisheries production) questions relating to lentic and lotic productivity dynamics. Studies can include explicit tests of mechanisms relating to benthic and pelagic production, respiration, or feedbacks to other trophic links. We especially seek investigators who are considering how coupled elemental cycles or multiple concurrent stressors may interact or synergistically control various aspects of lake biogeochemistry, physics, and ultimately productivity.

SS36 Groundwater-surface water exchange across the land-ocean continuum

Joseph Tamborski, Old Dominion University, jtambors@odu.edu
Valenti Rodellas, Universitat Autònoma de Barcelona, valenti.rodellas@uab.cat
Julia Guimond, Dalhousie University, guimondja@gmail.com

Groundwater-surface water exchange is increasingly recognized for its role in the transfer of water, energy, heat and chemicals across the land-ocean continuum. In the absence of rivers and estuaries, coastal aquifers, important freshwater resources for coastal communities, act as “invisible” bridges between the land and ocean. This submarine groundwater discharge (SGD) to the coastal zone can supply essential nutrients necessary to support primary productivity, and in some instances may fuel eutrophication. Within the last several years there has been an increasing focus on distinguishing terrestrial groundwater discharge (fresh SGD) and seawater circulation through sediments (saline SGD and/or pore water exchange), their flow paths, driving mechanisms and their respective importance as a source or sink of chemicals. These investigations, together with a comprehensive understanding of the biogeochemical transformations occurring in the coastal aquifer, are needed to improve both present estimates and future predictions of water exchange and chemical loadings. Hydrogeologists and oceanographers often have disparate viewpoints on the importance of groundwater-surface water interactions. This session aims to bring together these different communities to discuss the importance of groundwater-surface water exchange in the coastal zone. We invite novel contributions that advance our conceptual framework of groundwater-surface water exchange across the land-ocean continuum. This includes modeling and field-based studies focused on mechanisms and drivers of flow, biogeochemical transformations within the coastal aquifer, nutrient, metal and carbon fluxes driven by groundwater-surface water exchange, and upscaling. We welcome studies that span a multitude of spatial scales, from the coastal aquifer and subterranean estuary to wetlands, embayments and the continental shelf.

SS37 Trophic complexity in pelagic microbial interactions

Serena Rasconi, UMR INRAE CARRTEL, serena.rasconi@inrae.fr
Kevin Lafferty, U.S. Geological Survey, Santa Barbara, CA, lafferty@ucsb.edu
Robert Ptacnik, WasserCluster Lunz, Lunz am See, Austria, Robert.Ptacnik@wcl.ac.at

Recent insights into aquatic diversity revealed a multitude of overlooked taxonomic groups mainly among microorganisms and protists (fungi, SAR, cryptomycota...) carrying an enormous related potential for ecological functions. This newly discovered diversity can affect ecological processes such as organic matter transfer, trophic upgrading, and nutrient cycling. This has inspired recent efforts to add such taxa to aquatic food webs, which have otherwise focused on predation, herbivory and bacterivory. In particular, microbial parasites (fungi and fungal-like organisms) are major infectious agents in pelagic ecosystems and also can be novel food sources that sustain consumer growth. Similarly, parasites can affect host population dynamics and predator-prey interactions. Furthermore, mixotrophs are now considered key bacterivores in near-surface waters, and open a new perspective for light-dependent loss rates, whereas cryptomycota and dark matter fungi are major decomposers and play crucial roles in organic matter cycling both in lentic and lotic ecosystems. This section welcomes contributions on overlooked biological interaction governing trophic transfer within aquatic food webs and aims at exploring new perspectives for a full understanding of aquatic ecosystem functioning.

SS38 Too hot to handle? Getting to grips with global change impacts in subtropical and tropical coastal waters

Christian Lønborg, Aarhus University, clonborg@gmail.com
Cátia Carreira, Departamento de Biologia and CESAM, Universidade de Aveiro, Portugal, ccd.carreira@gmail.com
Susana Carvalho, King Abdullah University of Science and Technology (KAUST), Red Sea Research Center, Thuwal, Saudi Arabia, Susana.Carvalho@KAUST.EDU.SA
Xosé Anxelu G. Morán, Centro Oceanográfico de Gijón, Instituto Español de Oceanografía, Gijón, Spain, xelu.moran@kaust.edu.sa

Subtropical and tropical coastal waters are among the most diverse and productive ecosystems on the planet. These shallow environments are highly dynamic at all trophic levels (e.g. plankton, corals, macrophytes) and receive nutrient inputs from a wide range of sources (e.g. upwelling, rivers, urban developments). Due to these features the ecological and biogeochemical role of these coastal waters are key to understand ecosystem health and functioning. Because of the high temperature and sunlight levels, these coastal ecosystems are some of the most biogeochemical active zones in the ocean. Furthermore, tropical waters contain the highest species richness in the world’s oceans. From a global change perspective, these ecosystems are also unique as they already experience elevated temperatures. However, they are expected to be substantially impacted by future global change (e.g. further warming, extreme freshwater discharge, decreased oxygen levels). Given the vast area occupied and the key ecological and biogeochemical role of subtropical and tropical coastal waters, we call for contributions that showcase observed and predicted responses of pelagic and benthic communities to global change in these “hothouses”. Such studies could be species-, process- or ecosystem-specific, as well as present across-ecosystem perspectives. Our goal is to provide a venue for researchers from different geographical regions to discuss and learn about impacts of global change in the ocean’s “hothouses”.

SS39 The present and future of nitrogen fixation in aquatic systems

Mar Benavides, Mediterranean Institute of Oceanography, mar.benavides@ird.fr
Sophie Bonnet, Meditarranean Institute of Oceanography, sophie.bonnet@univ-amu.fr
Maren Voss, Leibniz Institute for Baltic Sea Research, maren.voss@io-warnemuende.de
Lasse Riemann, University of Copenhagen, lriemann@bio.ku.dk
Douglas Capone, University of Southern California, capone@usc.edu

Exciting work into a range of areas considering aquatic nitrogen fixation is ongoing, including fresh and marine waters. Nitrogen fixation provides a critical nutrient input in diverse freshwater and ocean ecosystems including pelagic and benthic systems. Nitrogen fixation is also subject to major changes due to rapidly shifting environmental conditions. Diazotrophs include a large variety of organisms able to thrive under diverse environmental conditions now known to include nutrient rich environments, as well as cold or deep aphotic waters. Their responses to the changing environment may therefore affect their survival and importance in various ways, including attendant shifts in ecological niches, affecting nitrogen as well as carbon cycling in aquatic systems. The multiple metabolic abilities of diazotrophs make them an attractive group for climate change mitigation and biotechnological applications. Ocean dynamics, rising temperatures, increasing levels of DIC, deoxygenation as well as various human impacts on aquatic systems affect the species composition, distribution and physiological performance of these microbes in the contemporary ocean and will most likely continue to do so in the future. Understanding the impact of interwinned environmental and anthropogenic effects requires deploying multidisciplinary research efforts ranging from single-cell approaches to modeling. This session welcomes presentations on all aspects of ongoing experimental, field and modeling work and particularly those that investigate the role of nitrogen fixation under future climate conditions. Moreover, studies that consider geoengineering solutions to mitigate climate change and the use of diazotrophs in mariculture systems for production of cosmetics and health compounds and in bioremediation are encouraged.

SS40 Host-microbiome interactions of marine organisms

Gerard Muyzer, University of Amsterdam, g.muijzer@uva.nl
Aschwin Engelen, CCMAR, Faro, Portugal, aengelen@ualg.pt

The idea of considering organisms in connection with their associated complex microbial communities, i.e. as holobionts, marks a real paradigm shift in biology. Both the host and its microbiome depend on chemical signalling and metabolite exchange that modulate the holobiont physiology. Imbalances in these signalling systems can rapidly lead to shifts in the interaction patterns, e.g., from mutualism to pathogenicity. Known molecular actors involved in the establishment, maintenance, and control of symbiotic relationships within holobionts include hormones, defence compounds, quorum-sensing and -quenching molecules, as well as nutrients (e.g., amino acids and vitamins). This session will bring together leading scientists that study the interactions of marine organisms, such as sponges, corals, algae and seagrasses, with their associated microbiomes using different state-of-the-art omic techniques.

SS42 The biogeochemistry of dissolved organic matter

Sinikka Lennartz, Institute of Chemistry and Biology of the Marine Environment, University of Oldenburg, sinikka.lennartz@posteo.de
Thorsten Dittmar, Institue for Chemistry and Biology of the Marine Environment, University of Oldenburg, thorsten.dittmar@uni-oldenburg.de
Aron Stubbins, Department of Marine Environmental Science, Northeastern University, a.stubbins@northeastern.edu
Lixin Zhu, State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, lixinzhu0305@hotmail.com

Dissolved organic matter (DOM) plays a major role for biogeochemical cycles in the ocean and on land. DOM contains as much carbon as all living biomass on the continents and oceans combined. The accumulation of DOM in the ocean over several millennia is enigmatic and contradicts established paradigms in geochemistry for organic matter stabilization. On the other hand, bacteria can only assimilate dissolved molecules, and DOM is therefore the main mediator for the flux of energy in marine and freshwater ecosystems. The DOM pool is now recognized as paralleling the sedimentary record as an information-rich set of tracers. These molecules carry the signatures of their source and subsequent journey through the environment. For this session, we invite contributions from all areas of research on DOM biogeochemistry, including empirical and modelling studies. Since inland waters are important contributors of DOM to coastal margins, we also welcome research which focuses on DOM biogeochemistry across the freshwater-to-marine continuum. Molecular-level and interdisciplinary studies are particularly welcome. Also, contributions that apply innovative analytical approaches, or identify novel concepts, fundamental challenges and the future directions of this fast growing field of research are encouraged.

SS43 Bridging the land–ocean divide: limnological and oceanographic perspectives on the ecological effects of a changing Arctic hydrological cycle

Johnna Holding, Aarhus University, johnna@bios.au.dk
Ada Pastor Oliveras, Aarhus University, adapastor@bio.au.dk
Maria Lund Paulsen, Aarhus University, mlp@bios.au.dk
Kristina Brown, Institute of Ocean Sciences, Fisheries and Oceans Canada, Kristina.Brown@dfo-mpo.gc.ca

Climate change is affecting the Arctic disproportionally compared to the rest of the globe, resulting in six-fold warming and an intensifying hydrological cycle. The observed warming is responsible for the rapid melting of glaciers, ice sheets, and permafrost, while changing precipitation patterns have drastically altered freshwater (FW) run-off on land. Run-off not only delivers increasing amounts of FW to the coastal ocean, but it also has the potential to carry large amounts of allochthonous material (e.g. organic matter, nutrients, dissolved ions, inorganic carbon, pollutants, etc.) and substantially alter the biogeochemistry of the Arctic coastal ocean, which makes up 34% of the coastline globally. The consequences of FW run-off to the coastal ocean, and the fate of the allochthonous material it carries, is only beginning to be understood in the context of Arctic change, in particular, as oceanographic studies have begun to recognize that not all “run-off” is the same. Limnological studies have long documented that FW ecosystems are not merely pipes from land to sea but rather active conduits that play a disproportionate role in biogeochemical processing of material before it reaches the ocean. As such, the hydrological changes currently taking place across the Arctic landscape have important consequences for not only biogeochemical cycling in lakes, rivers, and streams, but also for downstream ecosystems that will alter the timing and magnitude of FW and allochthonous material transfer from land to the ocean. This session seeks to bring together limnologists and oceanographers tackling similar questions about the biogeochemical and ecological effects of a changing hydrological cycle in the Arctic from their different perspectives along the land-ocean continuum. We invite abstracts that unify these two vantage points and address not only the fate and effects of FW and allochthonous material in the coastal ocean, but also the changes taking place in the active conduits transporting FW and associated allochthonous material to the coast. With this session we hope to establish unifying concepts and paradigms and identify overarching hypotheses for how this continuum will be affected in the future so as to bridge these two perspectives to make better observations and predictions moving forward. This session will provide a broad overview of land to ocean linkages in the Arctic, integrating a wide array of approaches, methodologies, and perspectives to strengthen common grounds among disciplines.

SS44 Modelling the ecology & evolution of plankton

Sergio M. Vallina, Spanish Institute of Oceanography (IEO) @ Gijon, sergio.vallina@ieo.es
Meike Vogt, ETH Zurich, meike.vogt@env.ethz.ch
Pedro Cermeno, ICM -- CSIC @ Barcelona, pedrocermeno@icm.csic.es
Sakina Ayata, Sorbonne University, sakina@obs-vlfr.fr

The relationship between the ecology and evolution of plankton and the functioning of both present and future aquatic ecosystems is currently one of the most pressing issues in aquatic ecology. The role of trait diversity for the maintenance of ecosystem functioning under climate and environmental change is the focus of major research programs worldwide. Ecological system theory, mechanistic models, and statistical models, such as species distribution models or Bayesian Inference models, have become essential tools to study and gain a deeper understanding of the mechanisms that shape the relationship between biodiversity, ecosystem structure, and ecosystem functioning. The inclusion of adaptive dynamics of species in the next generation of trait-based numerical models has been recognized as a grand challenge. The use of artificial intelligence and machine learning in the next generation of statistical models is also a major step forward. This session would like to call for works that: 1) use any kind of ecosystem modelling approach; 2) address ecological questions such as resource competition, environmental filtering and ecological network properties; 3) address the dynamics of adaptive evolution such as trait-diffusion, pairwise invasibility and evolutionary branching; 4) use phytoplankton, zooplankton and/or bacterioplankton as their model organisms; 5) focus on freshwater or marine systems, either at local, regional or global scales; 6) study ecosystem structure, biodiversity and ecosystem functioning of plankton ecosystems; 7) quantify the feedbacks between plankton diversity, ecosystem structure and productivity with climate/environmental change, or 8) evaluate the links between plankton biogeography, biodiversity, ecosystem function, ecosystem service provision and policy making. The works can range from pure ecological theory developments to observationally validated modelling. The session aims to be inter-disciplinary at the interface between microbial ecology, systems physics, applied mathematics, and computer science.

SS45
Functional connectivity in marine ecosystems: methodological advances to integrate ecosystems complexity into management frameworks

Lucia Lopez-Lopez, Spanish Institute of Oceanography, lucia.lopez@ieo.es
Audrey Darnaude, Université de Montpellier- Centre National de la Recherche Scientifique (France), Audrey.DARNAUDE@cnrs.fr
Manuel Hidalgo, Instituto Español de Oceanografía (Spain), jm.hidalgo@ieo.es

Historically, research on marine connectivity has been largely limited to species-specific approaches, focusing primarily on dispersal and demographic connectivity. However, with recent methodological advances allowing researchers to link individual movements and trait expression to ecosystem function, marine functional connectivity has gained increasing momentum. At the same time, this rapidly growing field needs to respond to the growing demand for a broader perspective on connectivity to inform ecosystem management. Combining novel approaches with traditional methods offers unprecedented new opportunities for advancing knowledge on marine connectivity. Among these are the use of environmental DNA to investigate dispersal of early life stages, the use of natural markers and increasingly sophisticated individual tracking tools to reconstruct the lifetime movements of marine organisms, and the development of meta-webs and multilayer networks for modelling and predicting connectivity rates. These new multidisciplinary approaches allow us to better assess connectivity processes across multiples scales, from population to community and ultimately to ecosystem levels. With this session we aim to provide a platform for scientists to showcase multidisciplinary and multi-scale approaches being used in marine connectivity research, bridging the gap between its structural and functional components, and novel applications of connectivity data to current challenges in marine management. We welcome diverse contributions at the population, community or ecosystem level, including theoretical, methodological and empirical research. The emphasis will be on studies that (1) evaluate the value of biological and/or ecological traits to inform organism connectivity, (2) integrate methods and/or address multiple scales of connectivity to advance our understanding of marine ecosystem complexity, and (3) aim to increase the incorporation of connectivity data into marine policy and management.

SS46 Forecasting is the future: advancing methods and applications of ecological forecasting in aquatic ecosystems

Tadhg Moore, Virginia Tech, tadhgm@vt.edu
Mary Lofton, Virginia Tech, melofton@vt.edu
Cayelan Carey, Virginia Tech, cayelan@vt.edu
Rafael Marcé, Catalan Institute for Water Research (ICRA), rmarce@icra.cat
Paul Hanson, University of Wisconsin, pchanson@wisc.edu

How are aquatic ecosystems going to respond to anthropogenic activities in the future? Using near-term, iterative ecological forecasting – i.e., making predictions about the future state of ecosystems that account for specified uncertainties and are continuously updated with new data when they are available – can potentially be a critical tool for answering this question. Recent advances in data availability and models have positioned the aquatic research community to increase their use of forecasting for prediction of hypoxic zones, algal blooms, the availability of drinking water, and other metrics of ecosystem functioning. These near-term forecasts can help managers act preemptively to mitigate water quality and quantity concerns, which will benefit society as a whole. In addition, near-term forecasting allows researchers to iteratively test ecological theory by continuously confronting models with data and thereby improving models over time. However, many challenges remain to enhance our ability to make forecasts, including improving ecosystem models, model-data fusion, and the quantification and analysis of uncertainties. This proposed session builds on a highly successful session at the 2019 ASLO meeting that highlighted new advances in ecological forecasting in the aquatic sciences. We solicit diverse presentations on both methodological and application-based research on forecasting hydrodynamics, biogeochemistry, and ecology in aquatic ecosystems, and especially welcome submissions that examine the role of uncertainty in forecast development, operationalization, and decision support.

SS47 Freshwater browning and coastal darkening – combining research insights regarding impacts on biology, ecology and ecosystem functioning

Anne Deininger, Norwegian Institute for Water Research (NIVA), anne.deininger@niva.no
Anders Opdal, University of Bergen, Anders.Opdal@uib.no
Helene Frigstad, Norwegian Institute for Water Research, helene.frigstad@niva.no
Dag Olav Hessen, University of Oslo, d.o.hessen@mn.uio.no

In recent years, optical alterations have been observed in both fresh- and coastal waters, especially across the boreal zone. Both freshwater “browning” and downstream coastal “darkening” have been attributed to the same stressor: increased input of terrestrially derived organic material (ter-OM). Ter-OM is increasingly recognized to strongly influence global biogeochemical cycles and ecosystem productivity, where most insights regarding the processing and impacts of ter-OM on aquatic ecosystems stem from decades of research in freshwaters. However, comparably little research has been conducted on the ecosystem impacts of coastal darkening, a rather newly identified stressor observed across boreal coastal waters. In particular, it is unclear how increased ter-OM concentrations may influence the biology, ecology and functioning of coastal ecosystems. By bringing together researchers from two traditionally separated disciplines, this session aims to facilitate the knowledge transfer and build-up regarding the impacts of ter-OM on and between aquatic ecosystems (i.e. from fresh to salty waters). We invite abstracts that identify drivers, trends, variance and impacts among and within ecosystems and explore the effects of ter-OM on optical properties, the biology, ecology and ecosystem functioning of aquatic ecosystems. We also invite contributions that examine the biological, chemical, and/or physical processes responsible for the various impacts across the land-ocean continuum. Further, we invite cross-disciplinary contributions integrating whole ecosystem dynamics. Especially welcome are contributions from ecosystems where climate change is expected to alter the flux (and cycling) of terrestrial matter in the aquatic environment (e.g. boreal and Arctic systems), as well as contributions from other areas across the globe where optical alterations caused by ter-OM have been observed, and impacts on ecosystems have been monitored or assessed (e.g. by experiments, lab studies, meta-analysis etc.).

SS49 Limnological Processes Beneath Ice Cover

Trista Vick-Majors, Michigan Technological University, tjvickma@mtu.edu
Alexander Michaud, Bigelow Laboratory for Ocean Sciences, amichaud@bigelow.org
John Priscu, Montana State University, jpriscu@montana.edu

Ice cover is fundamental to the seasonal cycles of inland waters and is a permanent feature of many high-latitude aquatic environments. The presence of ice limits light penetration, influences water column mixing and diminishes atmospheric ventilation. These influences produce a cascade of effects on water column and sediment physiological and biogeochemical processes. For example, long term datasets collected from ice covered lakes in the polar regions have revealed unique physiological adaptations to permanent ice cover, and investigations of temperate systems during the ice covered season have highlighted the importance of under ice processes in the regeneration of nutrients. Experimental data show that autotrophic and heterotrophic organisms respond at the individual and community level to the formation of ice-cover. Rising global temperatures are decreasing ice cover duration and altering ice thickness, which clearly have implications for freshwater biogeochemistry. This session aims to further our understanding of limnological processes under lake ice and highlight the consequences of changing ice covers for limnological processes across local, regional and global scales. We welcome submissions focused on any aspect of limnology including physical, biological, and chemical processes under ice cover and during open water – ice cover transitions, especially those that aim to link biogeophysical processes.

SS50 Structure, Function and Controls of Hardwater Lakes in a Changing Climate

Bjoern Wissel, University of Regina, bjoern.wissel@uregina.ca
Rafael Marcé, ICRA, rmarce@icra.cat
Zoraida Quiñones-Rivera, University of Regina, zoraida.quinones@uregina.ca

Hardwater lakes occur on all continents except Antarctica and represent almost half of all inland waters worldwide. Their prevalence in semi-arid to sub-humid climate zones and unique hydrology makes these lakes particularly vulnerable to climate change, water withdrawal and pollution, resulting in substantial damage to both environmental and economic systems. Lake morphometry, hydrology and water chemistry in these systems is often different from those in boreal lakes, leading to large differences in biogeochemical cycles and atmospheric exchange (CO 2, CH 4, N 2 O). In addition, hardwater lakes often exhibit a highly diverse and/or specialized food-web structure. Improved understanding of the role of these lakes in elemental cycling and biological diversity is needed to improve surface water management in continental interiors, protect ecosystems from irrevocable damage (e.g., Aral Sea), and understand their effect on surface hydrology. To address these shortcomings and enable future synthesis, we invite contributions that evaluate biological, hydrological, physical, chemical aspects of hardwater lakes.

SS51 Author spotlight: recent high-impact authors from the ASLO journals

Paul Kemp, ASLO, lomethods-editor@aslo.org
Jim Cloern, USGS, loletters-eic@aslo.org
Chris Filstrup, University of Minnesota Duluth, filstrup@aslo.org
Dave Hambright, University of Oklahoma, dhambright@aslo.org
Adrienne Sponberg, ASLO, sponberg@aslo.org

The ASLO journal editors convene this invitation-only special session to recognize authors that published highly cited or highly downloaded articles in 2018-2019 in any of the ASLO family of journals. Limnology and Oceanography, Limnology and Oceanography Bulletin, Limnology and Oceanography: Letters, and Limnology and Oceanography: Methods. The ASLO journals are a success because authors publish their finest work in our journals. We greatly appreciate their contributions to our science and to the ASLO community. This session is an opportunity to celebrate the authors and showcase their work, highlighting some of the most influential work in recent years. We invited the contributing author (or any co-author) to present updates to the selected article, describe their evolving research directions, or present a review of the state of the art in their field. Given the broad scope of our journals, these presentations represent the breadth of the aquatic sciences, and some of the most exciting work now underway. Articles were selected based on their average monthly rate of downloads and/or citations, both of which serve as indicators of reader interest.

SS52 New frontiers in mixoplankton research – lab, modeling, and field approaches

George McManus, Univ. Connecticut, george.mcmanus@uconn.edu
Aditee Mitra, Cardiff University, MitraA2@cardiff.ac.uk
Luciana Santoferrara, University of Connecticut, luciana.santoferrara@uconn.edu

Since the rediscovery of plastid retention by ciliates and ingestion of prey by some phytoplankton in the 1980s, many studies have documented the widespread occurrence of mixotrophy in marine plankton. This simultaneous capability for phagotrophy and phototrophy is common across the protist branches of the tree of life, and it now appears likely that a large plurality of chloroplast-bearing marine protists are also capable of ingesting particles. Despite the widespread occurrence of mixotrophy and acknowledgement of its importance, it has been difficult to re-conceptualize protist plankton in this light and our teaching and research are often still focused on protists as either “little plants” (phytoplankton) or “little animals” (zooplankton).  In this session, we aim to recruit presenters who will summarize the latest results on the physiology of these mixoplankton, its global diversity, and efforts to incorporate mixotrophy into new conceptualizations of planktonic food webs. Good experimental models for mixotrophy have been established among ciliates, dinoflagellates and a variety of smaller flagellates (chrysophytes, cryptophyes, etc.). Laboratory studies with these model organisms have advanced knowledge on the physiology of mixotrophy and its implications for carbon and nitrogen cycling. We also have new modeling approaches addressing the quantitative importance of mixoplankton in food webs. Some of these results are ripe for review or overview talks. In three key areas, however, novel research approaches are just beginning to bear fruit: the distribution and diversity of mixoplankton, revealed in global biodiversity databases and molecular surveys; the costs of mixotrophy; and the molecular mechanisms that support and regulate mixotrophy and integration of foreign plastids within hosts. These and other topics will be featured in this session, for which we hope to attract participants from the newest generation of plankton ecologists.

SS54 Vegetated Areas in Aquatic Ecosystems: Greenhouse Gas Dynamics and Fluxes

Pascal Bodmer, Université du Québec à Montréal, bodmerpascal@gmail.com
Paul del Giorgio, Université du Québec à Montréal, del_giorgio.paul@uqam.ca
Sarian Kosten, Radboud University, s.kosten@science.ru.nl

Aquatic ecosystems (among others - wetlands, lakes, rivers, estuarine and coastal systems) are important players in greenhouse gas (GHG; i.e. CO 2 , CH 4 , N 2 O) dynamics. The emission of e.g. CH 4 to the atmosphere entails the diffusive, ebullitive, as well as the plant-mediated pathway. Particularly, the latter is largely understudied, and not well understood. Although CH 4 fluxes from vegetated areas may present a large share of the total CH 4 emissions in certain systems, we currently lack insight into emission intensities from vegetated areas. This has led to vegetated areas being barely included in upscaling efforts. There is a lack of studies across all aquatic ecosystems, especially running waters, coastal and estuarine systems. Furthermore, vegetated areas influence carbon and GHG dynamics in multiple ways, such as potentially increasing aerobic CH 4 oxidation through increased oxygen availability in the root areas but at the same time increasing CH 4 production through the accumulation of fine sediments and consequently organic matter. This session aims at developing an overview of GHG related processes in vegetated areas, exploring the contribution of plants and vegetated habitats to total GHG emissions in aquatic ecosystems, and potentially identifying relevant future research directions. In this session, we welcome contributions that study all aspects of GHG dynamics in vegetated habitats in any aquatic ecosystem, natural or human-made, including wetlands, rivers, lakes, estuaries, and coastal areas. These contributions can be conceptual, experimental, technical, or in the field at local to regional scales.

SS55 Let it snow! Towards understanding the drivers of marine snow in a changing global ocean.

Antonietta Quigg, Texas A&M University at Galveston, quigga@tamug.edu
Peter Santschi, Texas A&M University at Galveston, santschi@tamug.edu
Kai Ziervogel, University of New Hampshire, Kai.Ziervogel@unh.edu

Marine snow originates in the surface waters of the ocean, primarily produced by photosynthesis and microbes. As the material sinks, it collects other floating debris, including fecal material, dead and decaying animals, suspended sediments, and other organic material that may have been transported from the land to the sea. Many animals in the deeper parts of the ocean filter marine snow from the surrounding seawater or scavenge it from the seabed as their primary food source. Differences in the amount of marine snow falling through the water column, or density of this snowfall, is influenced by many factors, including production of phytoplankton in surface waters, consumption and decomposition rates of the organic matter en route to the seafloor, and the movement of this material via currents (horizontal and vertical). Recent advances have provided a deeper understanding of marine snow, especially its composition, chemical basis for aggregate formation and dynamics (fragmentation, coagulation, ballasting), particle associated micro-organisms and in turn their export, carbon and nitrogen cycling, its role in pollutant transport to the deep ocean (e.g., oil, dispersants, microplastics). But much remains to be learned, more so as we face an ocean responding to global change. While changing, oceans enhance or decrease the production of marine snow and how will this in turn impact the biological carbon pump? And how will this in turn impact the biogeochemical cycling of macro- and micro-elements, particularly iron? This session will bring together a community of scientists interested in understanding the drivers of marine snow in a changing global ocean, the consequences and future directions for research.

SS56 Coping with the stress: Microbial responses to natural and anthropogenic perturbations in aquatic environments

Kai Ziervogel, University of New Hampshire, kai.ziervogel@unh.edu
Gabriella Caruso, Institute of Polar Sciences (ISP), National Research Council, gabriella.caruso@cnr.it
Xiuyun Cao, Institute of Hydrobiology, Chinese Academy of Sciences, caoxy@ihb.ac.cn

Aquatic ecosystems worldwide are subject to frequent natural and anthropogenic stress such as eutrophication, acidification, warming, and pollution (e.g., spilled oil, microplastics, POP, chemical and microbial contaminants). Microorganisms including bacteria, archaea, microalgae, and protists respond and adapt to such perturbations due to their wide metabolic plasticity on rather short timescales, which makes them ideal sentinels for understanding the effects of environmental stressors on aquatic ecosystems. Microbial responses to environmental stressors range from larger scale processes such as harmful algal blooms with system-wide consequences for ecosystem functions, to responses at the microscale in which microbes operate. For instance, microbial interactions with pollutants from spilled oil, microplastics, POP antibiotics, and other microbial contaminants involve complex biochemical processes and metabolic pathways on the molecular and single-cell scale. Understanding the broad range of microbial responses to environmental perturbations often require a combination of field observations and laboratory incubations under controlled conditions. We welcome submissions of observational and experimental studies that explore microbial dynamics including distribution patterns, community structure, metabolic pathways and activities, as well as interactions between decomposing and producing microorganisms in response to natural and anthropogenic stressors in marine and freshwater environments. We particularly welcome studies that contribute to model parameterization, extrapolating microbial processes to environmental scales and thus helping to predict future scenarios and guide decision makers.

SS57 Microbial responses to global changes across scales of organization: from molecular to assemblage levels and from prokaryotes to microeukaryotes

Senjie Lin, University of Connecticut, senjie.lin@uconn.edu
Thomas Mock, University of East Anglia, T.Mock@uea.ac.uk

At the rapid change of climate and environment, microbes (including prokaryotic and eukaryotic auto-, hetero-, and mixo-trophs) in the aquatic ecosystem are experiencing unprecedented pressure of stress, the combination of warming, acidification, and coastal eutrophication. Despite the numerous studies already reported, there still needs to be an integrative framework to facilitate inquiries about responses at different organizational levels, spanning from molecular, genomic, epigenetic, biochemical, cell, population, to assemblage. How plastic are these microbes and their interactions (symbiotic, trophic) and what are the molecular mechanisms? Can they evolve fast enough to keep up? How many generations are required to run long-term experiments for in order to find out? Besides, where are the tipping points for the environmental influence to reach the next organizational level or to cause ecological collapse such as harmful algal blooms and coral bleaching? This session is designed to bring together research results, expertise, experiences, and questions to foster enthusiastic discussions and debates about multi-scale responses and adaptive evolution of microbes in face of single as well as multiple stressors.

SS58 Shallow Lakes: Ecology, Biogeochemistry, and Human Health

James Gawel, University of Washington Tacoma, jimgawel@uw.edu
Meredith Holgerson, Cornell University, meredith.holgerson@cornell.edu
Angela Strecker, Western Washington University, angela.strecker@wwu.edu

Shallow lakes can have very different physical, chemical, and biological drivers than the deeper lakes often studied in classical limnology. These lakes play a critical role in aquatic productivity important to the function of natural ecosystems as well as providing a significant source of food for human needs. In populated areas, these lakes provide greenspace valuable for psychological health and a human refuge under a warming climate regime, and yet these lakes are also more susceptible to climate change and anthropogenic influences. The sheer number of these shallow waterbodies compared to deep lakes stands in contrast to small amount of research attention they have received. Therefore, there is a significant need for a better understanding of the biogeochemistry and ecology of shallow lakes, the impact of climate change and other human influences on these critical ecosystems, and resultant ecological and human health risks needing to be addressed. This session is open to new research on physical, chemical, biological, and ecological processes in shallow lakes in natural and human-influenced systems, human impacts on these lakes, and the risks to human populations dependent on them.

SS59 The power of time series for unraveling aquatic microbial community interactions and functions

Ryan Newton, University of Wisconsin Milwaukee, newtonr@uwm.edu
Katherine McMahon, University of Wisconsin Madison, trina.mcmahon@wisc.edu

Time series sampling of aquatic ecosystems is a powerful approach to detecting and perceiving ecosystem change, and the drivers contributing to that change. The concept of the "Invisible Present" states that some changes cannot be observed without extended and sufficiently dense sampling. Microbial communities are sensitive response variables and therefore sentinels of change. Freshwater and marine microbial time series are being used to unravel microbial community dynamics and understand the implications of change with respect to community function. They can also be used to infer terrestrial contributions to aquatic communities, including contaminant organisms delivered in storm water inputs. Attendees will leave the session able to explain why time series are important for understanding microbial ecology and evolution, and what we can (and can't) learn from them. They will also be able to identify major roadblocks preventing advances on this topic, along with proposed near-term next steps.

SS60 Contextualizing abrupt change using big environmental data at freshwater and marine ecosystems

Xavier Benito-Granell, SESYNC, University of Maryland, xavier.benito.granell@gmail.com
Xavier Benito, SESYNC, University of Maryland, xavier.benito.granell@gmail.com
Eric J. Pedersen, Concordia University, Dept. of Biology, eric.pedersen@concordia.ca
Trisha Spanbauer, University of Toledo & Lake Erie Center, trisha.spanbauer@utoledo.edu
Jessica Burnett, US Geological Survey, Lakewood, jburnett@usgs.gov
Gavin Simpson, University of Regina, Canada, gavin.simpson@uregina.ca

Human activities are causing diverse and unprecedented changes in many of Earth’s ecosystems. Marine and freshwater ecosystems have been in the spotlight because their economic and ecological values are among the highest of any biome. Understanding how accelerating environmental stressors in freshwater ecosystems will produce regime shifts, the changes in the underlying structure and function of the system, requires an understanding of the local and regional environments, as well as a long-term view on the range of past environmental change and variability. However, evidence linking environmental variation to regime shifts is largely restricted to relatively small spatio-temporal scales. The explosion of large volumes of ecological data has occurred in parallel with the advancement of resilience science, providing an opportunity to approach these complex phenomena from an interdisciplinary point of view (e.g., limnology, community ecology, paleolimnology, food web ecology, coastal fisheries, disturbance ecology). We welcome contributions focused on regime shifts in both marine and freshwater ecosystems across different spatial (local to regional) and/or temporal (decades to millennia) scales, with focus on possible synchronization across large, disconnected areas. We aim to highlight studies that use disparate sources of data and novel synthesis-related statistical and visualization techniques to advance the understanding of which variables or combinations of variables (natural and anthropogenic) may lead to different ecosystems with undesirable states. Societies rely heavily on freshwater and marine ecosystem services, which can be jeopardized when critical thresholds are crossed. Improving our ability to forecast thresholds in these systems is crucial for well informed management practices.

SS61 Dissolved organic matter reactivity and molecular composition in the Anthropocene

Dolly Kothawala, Uppsala University, dolly.kothawala@ebc.uu.se
Martin Berggren, Lund University, martin.berggren@nateko.lu.se
S. Leigh McCallister, Virginia Commonwealth University, slmccalliste@vcu.edu
Marguerite Xenopoulos, Trent Unversity, mxenopoulos@trentu.ca

Multiple anthropogenic drivers are altering the geomorphic and biogeochemical characteristics of inland waters and their surrounding catchments. Anthropogenic disturbances have resulted in melting glaciers, land use change, climatic change, altered water residence times, increased suspended sediment, warming water temperatures and increased nutrient inputs, to name a few impacts. Changing environmental conditions have the potential to modify dissolved organic matter (DOM) reactivity in terms of light absorption, potential for physico-chemical interactions with inorganic and organic particles and its metabolic fate. Concurrently, the molecular composition of DOM can be modified by these changing environmental conditions. Methods for measuring DOM composition can range from simple approaches including bulk optical methods to more detailed molecular approaches including mass spectrometry, nuclear magnetic resonance spectroscopy and coupled approaches with liquid chromatography. With recent technological advances in DOM characterization methods including instrument sensitivity, wider availability of instruments and sample throughput, it has become increasingly feasible to develop a deeper understanding of how anthropogenic drivers might influence DOM composition and reactivity at a range of scales. Ultimately, these advances are critical for predicting how climate and environmental changes may impact the fate of DOM (i.e. respiration, oxidation, transformations, sedimentation, export) and the role of aquatic ecosystems in regional carbon budgets. We welcome presentations focusing on DOM composition and/or reactivity, as well as studies linking molecular composition to functional characteristics of DOM that sit within the scope of changing environmental conditions in the Anthropocene.

SS62 Citizen Science in Aquatic Ecosystems, open and participatory science for healthy ecosystems

Lara S. Garcia-Corral, Asociación Noctiluca- King Juan Carlos University, ls.garcia@alumnos.urjc.es
Patricia de la Fuente Gamero, Universidad de Burgos, pdelafuente@ubu.es
Jaume Piera, Instituto de Ciencias del Mar- Consejo Superior de Investigaciones Científicas, jpiera@icm.csic.es
David Leon, Hombre y Territorio, contacto@hombreyterritorio.org
Luis Francisco Ruiz-Orejón, Sistema de Observación y Predicción Costero de las Islas Baleares, SOCIB, luisf.ruizorejon@gmail.com

Citizen science involves the volunteer participation of citizens in at least one of the scientist method stages (i.e., the research design, sample collection, and/or interpretation data process) together with the scientific community. The final goal is to achieve personal, community, and environmental benefits. Citizen Science creates a wide range of new opportunities for the public participation in scientific research, and complement more traditional ways of scientific data collection and knowledge generation/learning. Citizen science activities benefits include improving scientific literacy, culture and interest, increasing participants’ awareness about environmental issues, filling specific knowledge gaps, increasing interactions between scientists and the society, promoting changes in individuals' behaviors, and fostering local stewardship. In the context of the aquatic research, the interest of volunteer’s participation in scientific research and monitoring programs by both, the public and governmental agencies, is increasing. Moreover, the development of sensing technology, data processing and visualization, as well as communication of ideas and results, provides unprecedented opportunities for citizen science in the study and conservation of aquatic ecosystems. However, it is also necessary to assess the challenges of integrating citizen science into traditional scientific work applied to aquatic ecosystems. Challenges, such as the nature and quality of data collected, data acquisition methodologies, data processing, interpretation, and open use. It requires care in designing citizen science programs such the generated data complement optimally other available data to co-generate new knowledge. This session brings together worldwide citizen science projects focused on aquatic ecosystems through that the actual state of citizen science in the study and conservation of marine and freshwater ecosystems is reviewed. This brings everyone an excellent opportunity 1) to meet people involved and create work networks, 2) to discuss processes about methodology and data treatment, 3) to define good practices in the design of citizen science projects focused on aquatic ecosystems, 4) to reflect onto the role of aquatic-oriented citizen science projects within traditional scientific knowledge, and its potential as a tool for public environmental education, suitable resource management, and policy decision-making about marine and freshwater ecosystems conservation.

SS63 Towards a mechanistic understanding of metal-microbe interactions in the Oceans

Martha Gledhill, GEOMAR Helmholtz Center for Ocean Research, mgledhill@geomar.de
Yeala Shaked, Interuniversity Institute for Marine Sciences & The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, yeala.shaked@mail.huji.ac.il
Ingrid Obernosterer, Microbial Oceanography Laboratory(LOMIC), CNRS-Sorbonne University, ingrid.obernosterer@obs-banyuls.fr

Trace metals are essential for life, catalysing key cellular reactions which then govern patterns of ocean fertility and biodiversity. Fundamental in this regard are the ways in which ocean microbes acquire essential metals and how biological activity is affected by metal availability. Diverse microbial community members can compete for this scarce resource, and trace-metal related metabolic functions can also be partitioned among taxa and benefit the whole population. Defining these interactions is critical for understanding the relationship between metabolic rates and elemental cycles in the ocean. Developments in this field are being led by advances in analytical chemistry, nanotechnology, molecular biology, and bioinformatics, as well as the expansion of 'omics'-related observations of in-situ microbial communities, and within the context of high resolution geochemical such as obtained as part the international GEOTRACES program. In this session we invite contributions that bring together insights from these different disciplines to better understand how microbial activity, diversity and ecology is shaped by interactions with trace metals over different space and time scales. By linking across disciplines, there is the potential to develop the mechanistic understanding required to inform the ecological and biogeochemical models we rely on for testing hypotheses and projecting the impacts of ocean change that will result from the impending BioGeoScapes program. We are specifically interested in contributions that address (i) metal uptake and interactions between microbes for metal resources, (ii) how microbes adapt their physiology to metal scarcity and varied supply, and (iii) how trace metals shape microbial activity and diversity in the ocean.

SS64 Addressing challenges in monitoring water quality using Earth Observation (EO) in transitional waters

Eirini Politi, Brockmann Consult GmbH, eirinidpoliti@gmail.com
Vittorio Brando, CNR-ISMAR, vittorio.brando@cnr.it
Diana Vaiciute, Marine Research Institute, Klaipeda University, diana.vaiciute@jmtc.ku.lt
Badr El Mahrad, Centre for Marine and Environmental Research, University of Algarve, badr.elmahrad@gmail.com

Preservation and restoration of good quality status in transitional waters is a key worldwide issue relevant to food production, industry, nature and recreation. To fulfil the increasing need to protect and sustainably manage aquatic resources, scientists and water managers first need to address existing data and knowledge gaps to better understand which areas are most affected and are threatened with status deterioration. Recognizing this, space agencies and the international remote sensing community have been generating satellite data in recent decades to provide water quality data, products and services to end-users in industry, policy, monitoring agencies and science. However, water quality data production is often focused on specific water bodies, not considering the water continuum and source-to-sea linkages. Different methods are used for each distinct water body (e.g. ocean vs lakes), while transitional waters are often neglected. In addition, certain limitations are posed by the inherent characteristics of transitional waters in terms of trophic and bio-optical regimes, as well as spatial and temporal scales of hydrological and ecological processes. This session invites presentations on how challenges in monitoring water quality using EO in transitional waters can be overcome. Examples from around the world are invited as a means of showcasing good practices, innovative methods, new tools, promising water quality products (e.g. water clarity, particle size distribution, phytoplankton functional types, algal blooms, aquatic vegetation), and success in upscaling the processes (e.g. primary production). Methods like data harmonization, data fusion and new algorithms for estuaries and lagoons are particularly welcome. Input from local to regional case studies are invited, especially when inter-comparison between different scales addresses issues stemming from scaling-up methods for observing these transitional aquatic ecosystems.

SS65 Feeding and ecophysiology of marine suspension feeders

Gitai Yahel, Ruppin Academic Center, Faculty of Marine Science, yahel@ruppin.ac.il
Martina Capriotti, University of Connecticut, Department of Marine Sciences,, martina.capriotti@uconn.edu
Sandra Shumway, Department of Marine Sciences, University of Connecticut, sandra.shumway@uconn.edu
Evan Ward E., Department of Marine Sciences, University of Connecticut, evan.ward@uconn.edu

Suspension feeding, the capture, and ingestion of small particles suspended in the water, is a mode of feeding unique to aquatic environments. Suspension feeders belong to almost all phyla and ranging in size from microorganisms to planktivorous fish to sharks and whales dominate pelagic food webs. Suspension-feeders also dominate a great variety of benthic ecosystems, mostly in the productive and particle reach photic zone. An increasing number of studies, however, now show the importance of benthic suspension feeders in the deeper ocean. By filtering large volumes of water, suspension feeders regulate the abundance of primary producers and play a crucial role in nutrient cycling, and benthic-pelagic coupling. While a vast amount of knowledge on suspension-feeding biomechanics and ecophysiology was gathered over the last century, our understanding of key topics is still evolving. These include the eco-physiology of suspension feeders residing in particle poor (oligotrophic) environments, the biomechanics of selective feeding and sub-micron size filtration, the role of DOM feeding, symbiosis, and allometric relationships in maintaining bio-energetic balances. Presentations addressing all aspects of nutrition-related ecophysiology and biomechanics of suspension feeders, across taxa, different ecosystems, and in changing environmental conditions, are welcome. Both field and laboratory studies investigating the physiological and metabolic aspects of suspension-feeding under diverse ambient conditions, like hypoxia, increased temperature, acidification, and species interactions, are also considered of great value for the purpose of the present session.

SS66 Coastal Ocean Observing Systems to understand and predict changes of the coastal ocean

JERICO-S3 Coordination team, Ifremer, jerico-s3@ifremer.fr
Laurent Delauney, Ifremer, laurent.delauney@ifremer.fr
Ingrid Puillat, Ifremer, ingrid.puillat@ifremer.fr
Felipe Artigas, CNRS, felipe.artigas@univ-littoral.fr

The coastal ocean is the most productive part of the world ocean and it is providing a large variety of ecosystem services. At the same time, it is also largely affected by anthropogenic disturbances, due to increase of coastal populations and intensification of their activities, while being vulnerable to climatic hazards and environmental disasters. It is a key objective to assess anthropogenic impacts in order to enhance the sustainability of the ecosystem services provided by the coastal ocean and to ensure the conservation and restitution of a Good Environmental Status (GES) for coastal marine waters. This is far from trivial since anthropogenic impacts are superimposed on global change and natural ones. Moreover, the coastal ocean is a complex and heterogeneous system, where a large variety of potential drivers are interacting over a wide range of nested spatio-temporal scales. More specifically, at temporal scales, these include a number of nested components: (1) long term (e.g. in relation with climate change), (2) interannual (e.g., in relation with climatic oscillation), (3) seasonal (in temperate areas), (4) mesoscale and submesoscale related, and (5) short term, including episodic events (e.g. in relation with the occurrence of rare/extreme events that constitute key factors in controlling the structuration, stability and the functioning of coastal marine systems). Due this heterogeneity, and its impacts, observing, understanding and ultimately predicting changes of coastal marine systems over a large range of spatio-temporal scales constitutes a key objective for Coastal Ocean Observing Systems (COOSs) and infrastructures such as JERICO-RI (Joint European Research Infrastructure for Coastal Observatories). This session focuses on the design, development, and contribution of COOSs and coastal multi-platform observation infrastructures towards the key objectives mentioned above. The contributions include collaboration schemes and solutions for coastal observations, including case studies (and related initiatives / projects) and examples of systems dedicated to tackling specific scientific questions. Particular attention will be paid to presentations demonstrating an ecosystem approach to observe the coastal ocean with holistic methodologies integrating physics, biology and biogeochemistry from the sensors to the analysis of the results and their use for advancing knowledge, modelling applications, ecosystem assessments, mitigation strategies. Collaboration and co-design of such infrastructure is key, and conferences such as ASLO 2021 are amongst the best ways to exchange ideas, knowledge, and build the coastal community of tomorrow.

SS67 The Fragile Food Web: Dynamics and impacts of gelatinous zooplankton and other understudied organisms

Adam Greer, University of Georgia, Skidaway Institute of Oceanography, atgreer@uga.edu
Marc Frischer, University of Georgia, Skidaway Institute of Oceanography, marc.frischer@skio.uga.edu
Laura Treible, University of Georgia, Skidaway Institute of Oceanography, laura.treible@skio.uga.edu
Deidre Gibson, Hampton University, deidre.gibson@hamptonu.edu

Quantifying the abundance, trophic links, and other ecologically significant interactions between organisms and their environment is critical for understanding any ecosystem. In the marine environment, our understanding of the food web is generally biased towards hard-bodied organisms, such as crustaceans, that survive conventional net sampling, chemical preservation, and are easily cultivated in the laboratory. Coastal and open ocean environments, however, often contain large populations of soft-bodied organisms that are difficult to sample and may be important components of marine food webs. These organisms include gelatinous zooplankton (e.g., ctenophores, cnidarian medusae, and thaliaceans) that often generate large blooms and fragile protists that can be found in large aggregates or chains that play an important role in carbon cycling. In this session, we invite presentations that explore new approaches to advance the understanding of the biology, ecology, and contributions to biogeochemical cycling of gelatinous zooplankton and other organisms that, in nature, exhibit fragile structures, such as long chains or colonial assemblages that are difficult to detect. Together, these historically neglected organisms and their ecologically relevant traits comprise the “fragile food web.” We invite studies that explore new sampling approaches, such as in situ imaging and acoustics, describing the physics, biology, and ecology in either laboratory or field settings, or modeling studies that predict abundances, distributions, and transport in relation to physical and chemical properties of the ocean. We are particularly interested in attracting interdisciplinary studies that incorporate multiple scales of observation – from fine-scale interactions to continental or global scale dynamics. This session will bring together field and laboratory biologists, oceanographers, and modelers to describe the dynamics of these understudied organisms, their important role in coastal and open ocean ecosystems, and the path forward to integrate these findings into our broader understanding of ocean ecosystem functioning.

SS68 Interactions of Harmful Algal Blooms, Eutrophication and Carbonate Chemistry in Coastal Oceans and Large Lakes

Erica Ombres, NOAA, erica.h.ombres@noaa.gov
Quay Dortch, NOAA, quay.dortch@noaa.gov
Beth Turner, NOAA Centers for Coastal Ocean Science, Scientist Emeritus, elizabethjturner@comcast.net

Harmful Algal Blooms (HABs), eutrophication and changes in carbonate chemistry are all threats to coastal ocean and large lake ecosystems and human communities. Often these processes occur simultaneously in space and time and share their major drivers. Although many areas of research have provided insights into the factors that govern HAB dynamics, toxicity and impacts, only a few of these have included carbonate dynamics. Similarly, carbonate studies have examined ocean and lake biogeochemistry and impacts to aquatic resources and economies, and have started to expand into multiple stressor studies (e.g. with hypoxia and warming). Less is known about the influences of each of these stressors on each other and cascading impacts to coastal ecosystems, communities and economies. Many questions remain about the co-dynamics of these phenomena. Does carbonate chemistry influence growth and/or toxicity of HABs? What are food web impacts of combining these impacts? Are some species more vulnerable/resilient to combined impacts, as compared to single stressors? What are the resulting impacts to fisheries and coastal economies? Can we make projections about future conditions? How can we encapsulate information about these interactions into useful information for management and policy makers? What are the major gaps in our understanding? Future work needs to address the many forms of coastal carbonate as multiple stressors in themselves, as well as the interactions with other stressors. Basic information is needed on HABs, carbonate chemistry and eutrophication in isolation, but more co-monitoring is needed in order to tease out potential relationships and construct meaningful experiments. Future lab experiments should look to the different carbonate chemical species, not just pH. Experimentation in the lab is necessary, but also needs to be extended to natural communities and field conditions, and be inclusive of HABs that produce human impacts and impacts to resources. This needs to be pursued at many levels: species, populations, communities, food webs, and important resources to society. An ecosystem context should be adopted that seeks linkages among open ocean, estuaries and watershed processes, especially the role of tributaries in delivering nutrients, dissolved carbon, pH and alkalinity. This session will foster discussion around these linked issues and encourage suggestions for the best research approaches to address them.

SS69 Population shifts of key species in the Southern Ocean: Drivers and consequences for food web dynamics and biogeochemistry

Stefanie Moorthi, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Germany, moorthi@icbm.de
Morten Iversen, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany, morten.iversen@awi.de
Bettina Meyer, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany, bettina.meyer@awi.de
Christoph Plum, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Germany, c.plum@uni-oldenburg.de

The warming Southern Ocean is undergoing drastic changes with global implications. These changes include reduction of Antarctic sea ice and ice sheets, increasing water temperatures, freshening from meltwater, and changing mixing regimes in the upper water column. These Antarctic alterations currently impac standing stocks of dissolved and particulate nutrients as well as key species including phytoplankton, zooplankton, and large grazers such as seabirds, penguins and whales. These shifts in key species in turn have consequences for organic matter fractions, biogeochemical processes, primary and secondary production, and community composition, with cascading effects ranging from the base of the food web up through higher trophic levels. Yet, the impacts on biodiversity, biogeochemistry, and the functioning of Antarctic communities remain poorly characterized. Recent observations show that salps are currently replacing krill as the main pelagic grazer along the West Antarctic Peninsula (WAP). Krill and salps occupy different ecological and spatial niches in the Southern Ocean, as they differ remarkably, e.g. in their reliance on sea ice, their life cycles, their mode of feeding and reproduction, and in the way they affect the lower food web via organic matter, nutrient and trace metal release. It is expected that this key species shift will also impact the top predators in the Antarctic, since salps are considered to be nutritionally inferior to krill. This macro-grazer shift has been attributed to the observed shift in phytoplankton composition towards small-sized cells and flagellates rather than large diatom blooms, which might foster salp blooms while krill cannot efficiently graze on small phytoplankton. A shift from krill to salps will have cascading effects on trophic interactions in the food web, and on the (re)cycling of important elements, such as carbon, nitrogen, phosphorus and iron. While we know much about the autecology of krill and salps, we lack information to address the ecosystem consequences of this regime shift. In this session we welcome observational, experimental and modeling studies which provide information and improve our understanding on climate induced shifts in key species in the Southern Ocean and their consequences for ecosystem functioning, including food web structure and dynamics, biodiversity changes, altered biogeochemical cycles, and ecological shifts across spatial scales, how feedbacks and controls operate and, ultimately, what new environmental conditions might be expected in the future Southern Ocean.

SS71 Scaling Aquatic Metabolism From Microbes to Ecosystems

Mario Muscarella, University of Alaska Fairbanks, memuscarella@alaska.edu
Pedro Barbosa, University of Quebec at Montreal, pebarbosa.limno@gmail.com

Aquatic food webs and biogeochemical cycles are connected by the metabolic processes that move organic matter and energy through the aquatic ecosystem. Primary producers fix new organic matter and capture solar energy. Secondary producers recycle organic matter and release chemical energy. Together, these organisms form the base of the aquatic food web and regulate major biogeochemical fluxes. In addition to being important for the energy flow within the ecosystem, they are also important resources for consumers -- including zooplankton, macroinvertebrates, and fish -- which inturn are important resources for other consumers including humans. Ultimately, the cumulative interactions among the various constituents of the system yield ecosystem level metabolic rates. Changes at any level of this ecological network can have profound impacts on the net ecosystem response. For example, changes in thermal conditions and modified nutrient inputs can have amplifying effects as we transition from fine scale microbial to macro scale ecosystem fluxes of matter and energy. Here, we propose to bring together studies that have addressed issues of aquatic metabolism from microorganisms to ecosystem fluxes. We specifically aim to bring together groups that address aquatic metabolism at different scales and therefore promote synergies and holistic dialogs. This session will integrate what we have learned about aquatic metabolism and different levels of organization in a series of presentations and yield new discussions.

SS73 Coupling long-term observations and experimental approaches to best address challenges emerging from global change

Robert Ptacnik, WasserCluster Lunz - Biologische Station GmbH, robert.ptacnik@wcl.ac.at
Meryem Beklioğlu, METU, Ankara, meryem@metu.edu.tr
Miguel Matias, CSIC, Madrid, mail.miguelmatias@gmail.com
Jens Nejstgaard, IGB, Berlin, nejstgaard@igb-berlin.de

Global Change (GC) is threatening aquatic ecosystems in an unprecedented way. Time series (TS) analysis and experiments potentially inform on consequences of GC in complementary ways. The analysis of time series from aquatic monitoring stations exhibit trajectories of state variables from past to present environmental conditions. Conversely, experiments inform us especially on short-term consequences of alternative environmental conditions on established communities. Thus, analysis of time series data can lead us to formulate hypotheses about ecosystem responses to GC. These hypotheses then should be subject to experimental testing, where underlying mechanisms can be analyzed in detail. In this session, we want to communicate approaches that exemplify synergies arising from such a combined approach. Presentations may address GC effects related to physical and chemical drivers (e.g. warming, salinization), but also those arising from altered biodiversity (species loss, non-indigenious taxa). We further invite contributions that highlight research gaps arising from TS analysis, i.e. questions that yet need to be addressed experimentally. In this context we also welcome perspectives how experimental systems like mesocosm facilities can be utilized in an improved way for addressing such research gaps.

SS75 Ecosystem-scale questions tackled by a mesocosm approach in aquatic systems

Meryem Beklioglu, Midle East Technical University, meryem@metu.edu.tr
Lisette De Senerpont Domis, Netherland Institute of Ecology (NIOO), Wagenningen, The Netherlands, L.deSenerpontDomis@nioo.knaw.nl
Maria Stockenreiter, Ludwig-Maximilians-Universität München, Department Biology II, Aquatic Ecology, Munich, stockenreiter@bio.lmu.de
Jens Nejstgaard, IGB, Department. Experimental Limnology, Research group leader, Berlin, nejstgaard@igb-berlin.de

Globally unprecedented disruptions (e.g. biodiversity loss, nutrient and pollutant inputs, climate crises etc.) are taking place in freshwater ecosystems with major consequences of losing biodiversity and ecosystem services. Obtaining quantitative mechanistic understanding of aquatic ecosystem structure and functioning is ever more crucial for taking sound adaptation and mitigation measures. Well controlled and highly replicated empirical approaches from small-scale laboratory microcosm experiments have been used to relate changes in food webs to altered environments, however, the degree of realism is limited and the extrapolation to natural systems often impaired. Large-scale mesocosm (or enclosure) experiments allow a more realistic setting by including a higher complexity in terms of trophic levels, and thus potential interactions. Thus, mesocosms experiments are a powerful approach to obtain such mechanistic quantitative understanding. To this session we therefore welcome researchers to present their ecosystem-scale empirical work where scientific questions about various aspects of aquatic ecosystem functioning have been tested through using mesocosms.

SS77 Connecting in-situ sensor networks and remote sensing to understand the complex ecology of aquatic landscapes

Stella Berger, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), berger@igb-berlin.de
Igor Ogasharwara, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), igor.ogashawara@igb-berlin.de
Sabine Wollrab, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), wollrab@igb-berlin.de

Globally, inland and coastal waters face rising temperatures, shifts in precipitation patterns and an increased frequency of extreme weather events. Forecasting long-term effects of global change at larger spatial scales needs regional assessments of lakes, rivers and coastal systems with a focus on connectivity between local aquatic systems and with their surrounding to the terrestrial matrix. Satellite and airborne remote sensing and measurements, combination with high frequency in-situ probes enable high spatial and temporal coverage of chlorophyll, turbidity as well as greenhouse gas emissions. While satellite based monitoring of chlorophyll is well established in the open ocean, the use of remote sensing in inland and coastal waters is challenging due to the spatial resolution of satellite imagery and the adaption of algorithms to optically complex waters. In this special session we invite researchers from different fields such as experts in remote sensing (RS) and aquatic ecology to challenge this research frontier. Presentations about innovative combinations of automatic high- frequency in-situ measurements with state of the art RS technology, experimental approaches, research and development (R&D), and combinations of long-term data with airborne remote sensing improve temporal and spatial resolution of data acquisition, as well as meta-ecosystem approaches for regional coverage of response patterns of aquatic ecosystems, e.g. their change in connectivity, are welcome. Ideas on future environmental monitoring and interpretation of available data to support more effective integrated management of coastal and inland waters for the mitigation of eutrophication impacts or other environmental challenges are highly appreciated.

SS78 Life in the Cyanobacterial Phycosphere: Using Genomic Tools to Understand Bacterial, Archaeal, Fungal, and Viral Interactomes

K. David Hambright, University of Oklahoma, dhambright@ou.edu
Hans Paerl, University of North Carolina-Chapel Hill, hans_paerl@unc.edu
Morgan Steffen, James Madison University, steffemm@jmu.edu
Alan Wilson, Auburn University, aew0009@auburn.edu
Jessica Beyer, University of Oklahoma, beyer@ou.edu

Harmful algal blooms, particularly those of toxic cyanobacteria, once thought to be homogeneous populations, are now known to be accompanied by a diverse community of fungi, bacteria, archaea, and viruses, within the phycosphere, which may play important roles in cyanobacterial bloom health and duration. Interactions between cyanobacteria and constituents of the phycosphere may be symbiotic, parasitic, or commensal. For example, cyanobacteria generate abundant dissolved organic carbon resources to the benefit of nearby heterotrophs that can subsequently return benefits to the cyanobacteria, including removal of reactive oxygen species, CO 2 generation, and nutrient recycling. Moreover, some cyanobacteria have been shown to alter ambient environmental conditions by decreasing O 2 concentrations and light availability, as well as by altering CO 2 and pH levels, which is likely to affect nearby bacteria. Indeed, studies have found that cyanobacterial bloom species strongly impact bacterial community composition. Additionally, viruses may play an important role in termination of cyanobacterial blooms. Symbiotic relationships between cyanobacteria and other taxa (e.g., Bacteria, Archaea) may be more likely due to the reduced genome size of cyanobacteria. With smaller genomes come reduced functionality, but also greater capacity for growth, due to the reduced cost of maintaining a large genome. While this may be beneficial for rapid reproduction and evolution, it is not necessarily conducive for cyanobacterial bloom formation. A smaller genome expresses fewer functions, but can also confer a selective advantage if the organism can obtain the lost function from other species as predicted in the Black Queen Hypothesis. This hypothesis suggests that some of the needs of one organism can be met by other organisms, allowing an interdependent microbial community to live more efficiently by managing fewer genes within their genomes. Along with genome reduction, some members of the community can receive metabolic products as public goods, which are useful metabolites or other necessary resources that are leaked into the external environment. With such products available extracellularly, these leaky functions become dispensable, and once these functions are lost, they may confer a selective advantage to that organism, if maintenance of the cellular machinery was expensive. It has been proposed that this coevolved community of synergistic and interacting microbial species constitutes a cyanobacterial microbiome or “interactome”, analogous to the microbiome concept described, for example, in humans, soils, and coral reefs. It is hypothesized that the interactome is key to the formation and demise of cyanobacterial blooms. This session seeks to bring together aquatic microbial scientists who study the complex relationships within cyanobacterial interactomes. Blooms of cyanobacteria are a threat to sustainability of freshwater ecosystems and their goods and services. We plan to bring together partners working on different taxa, methodologies, countries, and systems to synthesize the state of the field and develop an understanding of organizing principles and future directions.

SS79 New perspectives on the functional roles of fauna in wetlands, lakes, and other aquatic ecosystems

Andrew Mehring, University of Louisville, andrew.mehring@louisville.edu
Adam Kessler, School of Earth, Atmosphere &Environment; Monash University; Clayton, VIC 3800, Australia, adam.kessler@monash.edu
Bia Almeida, Department of Wetland Ecology; Doñana Biological Station EBD-CSIC; Sevilla, Spain, bialmeida182@gmail.com

Our understanding of the roles of fauna in aquatic ecosystems has been evolving at a rapid pace. For example, it is now known that several orders of macrofauna substantially alter benthic greenhouse gas emissions; waterbirds disperse plants and live animals between aquatic ecosystems; and microbial and macrophyte communities can be structured by larger fauna. However, questions remain as to whether recent findings can be generalized inside and outside of laboratory settings and across large spatial scales (i.e. globally). Addressing these issues requires multinational collaboration to gain a better understanding of universal functional relationships. This session will present the results of the latest international research from far flung aquatic ecosystems, and in doing so will provide an overview of the latest breakthroughs in understanding the roles of waterbirds and other fauna in modifying wetland ecosystem structure and function. One of the goals of this session will be the development of a synthesis paper bringing together the work of presenters and other leading authors in the field. While this session is intended to focus on wetlands and lakes, studies demonstrating large-scale effects of fauna on structure and function in streams and rivers are welcomed.

SS80 Dynamics of organic matter in the river-ocean continuum: From analytical methods, molecular and isotope geochemistry, to ecosystem modelling

Kaijun Lu, The University of Texas at Austin Marine Science Institute, kaijun.lu@utexas.edu
Zhanfei Liu, The University of Texas at Austin Marine Science Institute, zhanfei.liu@utexas.edu
Ding He, Zhejiang University, dinghe@zju.edu.cn
Xiaolin Li, Xiamen University, xlli@xmu.edu.cn
Laodong Guo, University of Wisconsin-Milwaukee, guol@uwm.edu

Organic matter, including dissolved and particulate forms, undergoes intense physical and biochemical alteration/modification during its transport along the river-ocean continuum. Globally, roughly 0.4 Pg of dissolved organic matter (DOM) and particulate organic matter (POM) is transported from the river to the ocean. The biogeochemical cycling and environmental fate of organic matter in the aquatic continuum has always been intriguing to aquatic biogeochemists. During mixing with seawater, a relatively large fraction of these seemingly bio-refractory organic matter is affected by various physical-chemical-biological processes such as flocculation and photo-oxidation, and eventually degraded in different time scales ranging from days to years. All these processes not only modify the structure of the organic matter and affect its reactivity and fate, but also exert a profound influence on coastal marine environments through remineralization of organic matter and subsequent release of nutrients. The composition of riverine and coastal organic matter is also highly related to anthropogenic activities (e.g., land use and land cover changes, damming), and it still remains uncertain how and to what extent anthropogenic influences may be altering the dynamics of organic matter in the river-dominated estuarine and ocean margin regions. Organic matter contains diverse molecular structures and chemical functionalities, and exists in dissolved, colloidal, and particulate forms that vary in molecular size, composition, and lability/reactivity along the aquatic continuum. Despite decades of efforts, we still have a very limited understanding of organic geochemical processes in aquatic systems, especially at the molecular level and the overall dynamics. In this session, we seek to invite presentations that focus on, but not limited to, the dynamics and fates of natural organic matter in various forms (e.g., dissolved, colloidal, or particulate), cutting across ecosystem boundaries (e.g., in freshwater and transitional environments including rivers, estuaries, and coastal oceans). We encourage interdisciplinary topics, including elemental, molecular and isotopic characterization of organic matter using advanced analytical techniques, interactions of organic matter with microbes especially those using forefront “omics” approaches, the emerging metabolomics, and particle dynamics such as aggregation/disaggregation and degradation/export. In addition, we also welcome studies with modelling or machine learning approaches to link the local chemical characterization of organic matter to its regional or even global significance, or to establish a transferable framework better predicting organic matter cycling in the context of climate and environmental change. The goals of this session are to bring together the scientists who have common interest but with different expertise, and to identify key knowledge gaps that can move the field forward.

SS81 Life in a warmer, more extreme world: how will increasing temperature and its interactions with other stressors affect plankton communities?

Elena Litchman, Michigan State University, litchman@msu.edu
David Hutchins, University of Southern California, dahutch@usc.edu
Tatiana Rynearson, University of Rhode Island, rynearson@uri.edu

Both the increasing means and the amplitudes of temperature fluctuations are already affecting the dynamics, community structure and productivity of planktonic communities in marine and freshwater ecosystems. Understanding how rising temperature affects bacterioplankton, phytoplankton and zooplankton and their interactions is critical for our ability to predict the responses of aquatic ecosystems to global change. We welcome studies that use observations, experiments and models to elucidate the physiological-, population- and community-level effects of temperature on the plankton. Looking at the effects of both the increasing temperature means and the extremes may provide more realistic estimates of the effects of warming, which can be addressed both theoretically and empirically. Recent studies showed that both the ecological and evolutionary responses of plankton to temperature depend on other factors. Therefore, we especially encourage studies that look at the interactions of temperature and other global change stressors. We hope that our session will bring together researchers working in both marine and freshwater systems, help synthesize the experimental, observational and theoretical developments on the effects of temperature and chart the path towards a more predictive science.

SS82 Multiple dimensions of macrophyte diversity

Paolo Villa, National Research Council (CNR), villa.p@irea.cnr.it
Rossano Bolpagni, University of Parma, rossano.bolpagni@unipr.it
Viktor Tóth, BLI, Centre for Ecological Research, toth.viktor@okologia.mta.hu

Macrophyte diversity provides information on spatial and temporal dynamics in primary production, and can therefore inspire informed conservation actions of aquatic systems. Starting from the notion of the inherent multidimensionality of biodiversity, few recent works - focusing on forest and grassland systems - have started to explore the potential of integrating multiple diversity metrics in analyzing the mutual relations between plant diversity (functional, phylogenetic and spectral) and ecosystem processes. Within this framework, applications to aquatic systems are strongly needed, because macrophyte peculiar characteristics and plasticity make them good case study of what functional adaptation potential plants could display when faced to heterogeneous environmental conditions. The objective of this session is to focus on multiple aspects of macrophyte diversity, spanning from established approaches, i.e. taxonomy based, to advanced and emerging approaches, e.g. genetic-phylogenetic-based, optical-spectral-based, functional trait-based (including phenology-based), and present a state-of-the-art illustration of different tools and methods used by aquatic ecologists to measure and retrieve all these aspects. Through this, we aim to set up an international, interdisciplinary forum for sharing different expertise on plant diversity assessment, discussing their different dimensions, and building the basis for future integration of techniques and approaches that potentially provide new perspectives on how macrophyte diversity is shaped and could be predicted in face of climate and habitat changes, and alien plants spread.

SS83 Homage to Jacco Kromkamp

Rodney Forster, University of Hull, r.forster@hull.ac.uk
Katja Philippart, NIOZ  Katja.Philippart@nioz.nl
Graham Underwood, University of Essex gjcu@essex.ac.uk
Dick van Oevelen, NIOZ Dick.van.Oevelen@nioz.nl

This session is dedicated to Dr. Jacco Kromkamp (1956-2020), who passed away after a battle with cancer in early October 2020. Jacco was an expert on the benthic and pelagic primary production that underpins coastal ecosystems around the globe. Understanding the physiological constraints on algal photosynthesis, and measuring photosynthesis in situ to enable accurate scaling-up of productivity estimates are domains for which Jacco was at the forefront for three decades. After completing his PhD on microalgal buoyancy regulation with Prof. Luuc Mur at the University of Amsterdam, Jacco took a postdoctoral position at the University of Bristol resulting in a highly-cited computer modelling study of cyanobacterial vertical migration. A permanent position followed at the Delta Institute for Hydrobiological Research in Yerseke, The Netherlands, to study the productivity changes accompanying the large-scale transformations of Dutch coastal waters for flood protection. As the then Centre for Estuarine and Marine Ecology of the Netherlands Institute for Ecological Research (NIOO-CEME) developed its international identity, and later merged with NIOZ, Jacco’s research broadened to include many aspects of phytoplankton, microphytobenthic, cyanobacterial and coral physiology and ecology, going from single-cell measurements to estuary-wide remote sensing productivity estimates. More highly-cited works followed, and central to his research was a comprehensive understanding of the variable fluorescence method, which measures the efficiency of photosystem-II in situ and in real-time. As chief scientist of several international projects, he developed fluorescence-based techniques into a reliable method for continuous, sustained measurements of photosynthesis. Recently, Jacco was an integral part of the SCOR working group 156 on the use of active chlorophyll fluorescence measurements, and was a member of the European Marine Board Working Group on Biological Ocean Observations. Jacco was a regular attendee at ASLO meetings, and will be greatly missed by a large community of friends and colleagues. This session will highlight Jacco’s legacy in coastal primary production, and we welcome contributions from both laboratory, field and modelling studies, from the small (individual cell) to the larger (regional seas) scale of variability, with particular interest in those topics Jacco developed throughout his career.

SS84 Ocean acidification: trends and effects from local to regional scales

Steeve Comeau, Laboratoire d'Oceanographie de Villefranche, steeve.comeau@obs-vlfr.fr
Abed El Rahman Hassoun, National Council for Scientific Research (CNRS-L)-National Center for Marine Sciences, abedhassoun@cnrs.edu.lb
Michele Giani, National Institute of Oceanography and Experimental Geophysics (OGS), Trieste, Italy, mgiani@ogs.trieste.it

Ocean acidification (OA) is getting more attention among the scientific community as new evidence is highlighting its effects on marine biogeochemistry, as well as on key marine ecosystems. The interplay of ocean acidification, warming, deoxygenation, and direct anthropogenic pressures is perturbing all ecosystems and putting the livelihoods, health, well-being and prosperity of people relying on marine resources under threat. This is why regional cooperations are key to further understand OA effects at local, regional, and global scales, an idea that is supported through GOA-ON (Global Ocean Acidification-Observing network) regional hubs (i.e. OA Med-Hub, OA-Africa, LAOCA, and many more). These hubs aim to connect scientists who are working on ocean acidification in a particular region and who are willing to cooperate to better understand the different aspects of OA from chemistry to biology, during present, future, as well as the past via paleo-studies of carbonate chemistry dynamics. This session aims to highlight the latest OA research globally, with a particular attention to marginal seas such as the Mediterranean Sea, which is considered a natural laboratory where synergistic trends of warming, OA and other drivers are already highlighted. We anticipate this to be a highly multidisciplinary session, with contributions from a range of fields including biology, chemistry, biogeochemistry, paleo-climatology, and modeling with a particular focus at local and regional levels.

Contributed Sessions

CS01 Human and Social Dimensions

CS02 Management and Conservation of Aquatic Systems

CS03 Restoration

CS05 Valuation of Aquatic Ecosystems and Resources

CS07 Trace metals

CS08 Hypoxia

CS09 Stable Isotopes

CS10 Gas Fluxes

CS11 Nitrogen biogeochemistry and cycling

CS12 Phosphorus biogeochemistry and cycling

CS13 Carbon fluxes in FW & marine environment

CS14 Dissolved organic matter - DOC, DON, DOP, fDOM, cDOM

CS15 Sediment dynamics

CS16 Environmental Change

CS17 Extreme Events

CS18 Harmful blooms

CS19 Novel methods

CS22 Fish and fisheries

CS23 Aquatic food webs

CS24 Biodiversity

CS25 Community Ecology

CS26 Microbial ecology and physiology

CS27 Phytoplankton ecology and physiology

CS29 Viruses

CS30 Zooplankton ecology and physiology

CS31 Aquatic Landscape Ecology

CS33 River and Stream Ecology

CS36 Estuarine Ecosystems

CS38 Polar Ecosystems

CS39 Coastal Ecosystems

CS44 Big data in aquatic systems

CS46 Models and modelling

CS48 Physical-Biological Coupling