Bacteria and cyanobacteria can appear as single-cells or as colonial forms in aquatic systems along a wide spectrum of trophic conditions. Single cells aggregate or divide in an extracellular matrix forming a microcolony. The success of one variant over the other can depend on physical and/or biological factors. High irradiance can affect picocyanobacteria aggregation in the short-term, as well as grazing which induces morphological transformations of the cell surface thus facilitating microcolony formation. High substrate concentrations, as well as the presence of nutrient particles, can promote the aggregation of heterotrophic bacteria. The activity of grazers directly induces aggregation of bacteria (large aggregates escape predation) and indirectly favours aggregating strains by removing competitive non-aggregating bacteria. This session encourages contributions on the dynamics of bacterial and cyanobacterial microcolonies and aggregates in freshwater and marine environments along a trophic gradient to compare the role of colonial and single-cell morphotypes. Laboratory experiments to understand the role of aggregation on biodiversity and fitness of the community are also welcome.
Conveners: Maeve C. Lohan, University of Plymouth, firstname.lastname@example.org; Sylvia G. Sander, University of Otago, email@example.com; Kristen N. Buck, Bermuda Institute of Ocean Sciences, firstname.lastname@example.org
The bioactive trace metals iron, copper, cobalt, nickel, zinc and cadmium are essential micronutrients for marine phytoplankton and exert a major influence on the global carbon cycle. Complexation of these metals by organic ligands may enhance or reduce bioavailability depending upon the metal-ligand complex formed. Yet we know little about the composition, sources and cycling of metal-binding ligands, which is hindering further advances in the field of trace metal biogeochemistry. An active SCOR Working Group (WG 139) ‘Organic Ligands- A Key Control on Trace Metal Cycling in the Ocean’ fosters the multidisciplinary collaboration of trace metal biogeochemists, organic geochemists and biogeochemical modelers in order to advance this field. This session is a community wide forum to highlight recent accomplishments in metal-binding ligand characterization and approaches for assessing ligand composition, sources and impacts on trace metal cycling in the aquatic environment, and to discuss future efforts in this field. We welcome abstracts related to metal- binding ligands from throughout the multidisciplinary field of oceanography.
Conveners:Richard B. Rivkin, Memorial University of Newfoundland, Canada, email@example.com; Louis Legendre, Laboratoire d'Oceanographie de Villefranche, France, firstname.lastname@example.org; M. Robin Anderson, Fisheries and Oceans Canada, Canada, email@example.com
Over 25 years ago, it was proposed that the biological carbon pump (BCP) transfers particulate organic carbon (POC) from surface waters into the deep ocean. Recently, it was suggested that in a parallel process, the microbial carbon pump (MCP) lengthens the residence time of carbon in the ocean through the production of refractory dissolved organic carbon (DOC) by heterotrophic prokaryotes. Both pumps lead to the sequestration of atmospheric CO2 in the ocean. Ongoing studies on responses of marine microbial communities to drivers that are both natural (e.g. atmospheric and ocean circulation, mixing) and anthropogenic (e.g. acidification, eutrophication, increased temperature) contribute to better understanding of the functioning of the two pumps. Microbes influence both the BCP (e.g. effects on community respiration or solubilisation of POC) and the MCP (e.g. effects on production of refractory DOC). This session invites marine microbiologists, biogeochemists, environmental scientists and modellers to report on empirical, synthetic and/or model studies that contribute to our understanding of the responses of the microbial community to the above drivers, and the consequences for carbon sequestration through the microbial and biological carbon pumps.
The vertical flux of particulate material in the oceans plays both direct and indirect roles in biogeochemical cycles and ecosystems of the ocean. Sinking particles redistribute carbon and other elements vertically in the ocean, supplying food to deep-sea organisms and contributing the ocean uptake of carbon from the atmosphere. Although recent studies have shed light on the fate of particulate material in both surface and mid-waters of the ocean, we still have a poor understanding of the drivers affecting changes to particulate material as it sinks, and models are still unable to accurately reproduce observations of particle flux. This session aims to bring together those interested in understanding particle flux in the ocean with an aim of synthesizing our current understanding and initiating discussions for future directions in this field. We invite submissions from field researchers and modelers to present in this session.
Conveners: Karen Wishner, University of Rhode Island, firstname.lastname@example.org; Lisa Levin, Scripps Institution of Oceanography, UCSD, email@example.com; Brad Seibel, University of Rhode Island, firstname.lastname@example.org
Oxygen minimum zones may be expanding in the world’s oceans in response to global climate change. These regions are also locations of high carbon dioxide, so animals may be affected by the multiple stressors of low oxygen and increasing acidification. For metazoans, physiological constraints, along with changes in ecological and environmental interactions, may result in changes in abundances, vertical distributions, migration patterns, and life history strategies. Potential community and ecosystem impacts include habitat compression affecting fisheries and benthos, alterations in biological pump processes and biogeochemical cycles, and changes in benthic-pelagic coupling. We seek presentations on these effects, focused on metazoans from zooplankton and meiofauna to top predators and megafauna. Contributions dealing with educating students and the public about potential human impacts and seeking solutions to public concerns are also welcome.
Conveners: Gustav Paffenhofer, Skidaway Institute of Oceanography, email@example.com; Marion Koester, University of Greifswald, Germany, firstname.lastname@example.org; Christian Wexels Riser, University of Tromso, Norway, email@example.com
Faecal pellets of marine metazooplankton and their fate vary, partly because of feeding processes, packaging, and composition and abundance of ingested food particles. Why are e.g. pellets of copepods and doliolids, occurring abundantly on subtropical shelves, different? Copepods mainly ingest particles of a narrower size spectrum than doliolids; copepods destroy nearly all food particles upon ingestion, doliolids do not, resulting in differing pellet compositions; copepod pellets are compact and membrane-covered, doliolid pellets have no membrane, being loosely packaged and readily accessible to microbes; their different morphology may lead to different prokaryotes and eukaryotes colonizing and degrading such pellets. What would be the fate of damaged pellets? Longer residence time, physical disintegration, instantaneous attack by microbes? While knowledge about pellet production and distribution among dominant metazooplankton exist, less is known about their environmental impact and fate. Our session therefore focuses on the fate of zooplankton pellets in relation to their wide range in morphology and composition, affecting their sinking behavior and associated microbial communities, including pellets of protozooplankton, and the impact of various taxa processing them.
The patchy, microscale distribution of aquatic microbial communities is determined in large part by the presence of conglomerations of organic and inorganic particles suspended in the water column, i.e., lake, river, or marine “snow”. For decades and with a variety of techniques, these conglomerations have been shown to be small-scale patches of higher biomass and productivity compared to surrounding water. These hotspots of microbial processes harbor pathogens, facilitate quorum sensing and genetic exchanges, and physically focus biogeochemical processes, even anoxic ones. This special session will update the “aggregate community” about the cornucopia of topics generated by recent studies of marine snow and its freshwater analogs.
The interstitial spaces inside sea ice constitute a vast habitat for both microorganism and animal life. Sea ice primary production exceeds that of the water column in early spring, therefore extending the duration of the productive season in ice-covered seas and providing an important resource for consumers. Melting sea ice releases immured sea ice organisms into the open water, seeding ice edge blooms and constituting a source of particulate as well as dissolved organic carbon. In a warming Arctic Ocean, the sea ice communities and associated carbon fluxes will likely be affected by later sea ice formation, earlier melt and varying snow cover. In this session we invite studies which report on the biology and biogeochemistry of sea ice biota and its role in the polar biogeochemistry and ecology, as well as its susceptibility to climate change.
Conveners: Lasse Riemann, University of Copenhagen, Denmark, firstname.lastname@example.org; Jonathan P. Zehr, University of California, USA, email@example.com; Julie LaRoche, Dalhousie University, Canada, firstname.lastname@example.org
Nitrogen cycling in marine waters is largely mediated by microbes. Bacteria or Archaea transform organic and inorganic nitrogen into bioavailable nutrients supporting productivity at local and global scales. Despite being essential for carbon biogeochemistry, many aspects of the marine nitrogen cycle remain poorly constrained and understood. Magnitudes of sources and sinks of nitrogen have been intensively debated throughout the last decade without reaching consensus. Recent discoveries of new organisms and pathways relevant for the oceanic nitrogen cycle along with developments of new applications of tracer techniques, molecular biology, and ‘omics’ have provided important new insights. In future endeavors to understand the marine nitrogen cycle it will be essential to examine the diversity and composition of microbial assemblages responsible for nitrogen transformations and, in particular, identify rates of activity for key microbes. In turn, this will promote the identification of environmental drivers important for the cycling of nitrogen, and facilitate establishment of couplings between key organisms, functional genes, and process rates. The session goal is to promote exchange among researchers from various fields to integrate data on biogeochemistry and process rates with the molecular ecology of microbes to facilitate understanding, modeling, and ultimately, prediction of nitrogen transformations in the sea.
More than two decades ago, researchers noted the expansion of harmful algal blooms (HABs) across the globe. Since that time, the frequency, intensity, diversity, and impacts of HABs in both freshwater and marine ecosystems have all continued to increase. Concurrently, our ability to assess the molecular and biochemical status of HABs and co-occurring microbes has improved significantly as has our ability to detect HABs and their toxins. This session seeks to bring together researchers of HABs in multiple ecosystems (e.g. estuaries, lakes, coastal ocean) that use a diversity of approaches (molecular, experimental, field, laboratory) to assess the sundry biological, chemical, and physical factors that facilitate the onset and demise of HAB events. Studies including, but not limited to, assessments of regulators of algal growth such as nutrients, carbon dioxide, temperature, light, and cyst emergence, as well as morality processes such as zooplankton grazing, viral lysis, allelopathy, grazing by bivalves, and physical dispersion are welcome. Investigations that consider both harmful algae and co-occurring phytoplankton and/or microbes are also encouraged.
Conveners: David T. Elliott, University of Maryland Center for Environmental Sciences, Horn Point Lab, email@example.com; Amy E. Maas, Biology Department, Woods Hole Oceanographic Institution, firstname.lastname@example.org
As anthropogenic influences on aquatic environments increase, there is considerable scientific and practical interest in understanding how a system’s biological components will respond to both single and multiple stressors (chemical pollution, hypoxia, ocean acidification, toxic and harmful algal blooms, changing temperatures, etc.). The response of zooplankton to environmental conditions is of particular interest due to the central and mediating role that this group occupies as a trophic link between planktonic primary producers and larger consumers. Consequently, the response of zooplankton to stress has implications for a breadth of research fields including biogeochemical cycling, trophodynamics, fisheries and other ecosystems services. A goal of the session is to facilitate communication across geographic boundaries in zooplankton research, to identify gaps in our technological needs and to provide a venue for discussion of the responses of zooplankton to the multiple potential stressors associated with environmental change. We encourage submissions that build a mechanistic foundation for describing responses of zooplankton to stressors at the level of the individual, as well as those that utilize such a foundation to scale up to the population, community, and ecosystem levels.
Conveners:Stephane Blain, Universite Pierre et Marie Curie, email@example.com; Queguiner, Universite d'Aix-Marseille, firstname.lastname@example.org; Strass, Alfred Wegener Institute for Polar and Marine Research, Volker.email@example.com; Dieter Wolf-Gladrow, Alfred Wegener Institute for Polar and Marine Research, Dieter.Wolf-Gladrow@awi.de
In the macronutrient-rich waters of the Southern Ocean, the biological pump of CO2 is likely controlled by the supply and bioavailability of iron. Through diverse interactions, iron limitation causes co-limitations principally by the light regime or by silicon. These processes are themselves modulated by the biological couplings in the food webs, and iron availability drives the functional structure and the biodiversity within the Southern Ocean ecosystems. Iron impacts the coupling between the different biogeochemical cycles with feedbacks on climate or on the productivity of adjacent ocean basins, possibly affecting the global carbon cycle. Resolving this complex multi-faceted story requires a large international effort which is underway. This session aims to bring together the most recent findings on the following issues: the impact of iron supply on carbon sequestration and atmospheric CO2 drawdown, the interaction between iron availability and the structure, biodiversity, and functioning of pelagic ecosystems, the identification of iron sources and transport pathways, the transformations of iron mediated by biotic or abiotic processes, and the coupling/decoupling between iron and major nutrient biogeochemical cycles. We invite submissions addressing any of these topics, either obtained from the most recent field studies (such as KEOPS2, or Eddy Pump), modeling studies or re-analysis of relevant previous observations.
The international GEOTRACES program is a multi-nation and multi-year effort to determine the concentration and speciation of trace elements and select isotopes in the world’s major ocean basins and some marginal seas at high vertical and horizontal resolution, reminiscent of the GEOSECS program. This program’s goal is “to improve the understanding of biogeochemical cycles and large-scale distribution of trace elements and their isotopes in the marine environment.” ( www.geotraces.org). To date, 35 “GEOTRACES compliant” section and process cruises have been completed and many more are planned. For this session, we invite investigators to share their findings from any GEOTRACES cruise including those related to dissolved and particulate trace elements, isotopes, nutrients and dissolved gases as well as atmospheric analyses. We also welcome presentations describing intercalibration, data management and modeling efforts related to GEOTRACES process and section studies.
Conveners: Uta Passow, Marine Science Institute, University of California Santa Barbara, firstname.lastname@example.org; Adrian Burd, Department of Marine Sciences, University of Georgia, email@example.com; Deborah Steinberg, Virginia Institute of Marine Science, firstname.lastname@example.org
Spatial and temporal variations in export particle flux from the surface ocean depend in part on the variability of the surface food web structure which varies geographically. Remineralization of particles below the surface layer depends largely on the food web structure underlying the surface waters. This session aims to present research related to geographical variability in surface and deep water food web structure and how it controls variability in particle flux and remineralization. This session will be of interest to biogeochemists, surface and deep water ecologists, phytoplankton specialists, ecosystem or biochemical modelers and those interested in zooplankton and higher trophic levels in both the surface and deep ocean, who strive for a mechanistic understanding of processes driving particle flux.
It is well established that atmospheric depositions of aerosols (such as black carbon) and dust are major local and global climate forcing factors. Also, recent research indicates that atmospheric deposition influences the diversity of microorganisms and microbe-mediated ecosystem functioning in the ocean. However, its influence on the (micro)biota is still poorly studied. This session brings together researchers from different scientific fields such as marine biology and biological oceanography, population and community ecology, diversity research and trophic ecology, and biogeochemistry. The aim is to summarize the research on the effect of atmospheric deposition on the microbiota, compare the effect of various factors such as black carbon and desert dust (and others), evaluate recent developments and potentially come up with a common position paper on global change, atmospheric deposition and the marine microbial life written by interested participants.
Methods for identifying and sequentially tracking discrete water parcels and entrained plankton populations have advanced to the point where it is feasible to conduct quasi-Lagrangian studies of plankton populations even in some dynamic coastal and oceanic environments. This session invites contributions that utilize different approaches to tracking water parcels and following planktonic organisms, with an emphasis on the resulting rate processes and population dynamic parameters that can be inferred in situ. Contributions are encouraged that address tracers and in situ perturbation experiments, drifting mesocosms, in situ drift arrays, modeling studies, and other quasi-Lagrangian approaches that help resolve planktonic distributions and vital rates.
Advances in situ electronic sensors have made sampling aggregates and animals in the ocean with optical instruments feasible. The more difficult tasks include interpreting the observations and using them to understand the ocean. Although all optical instruments use light, they use it in different ways that yield different results. All use absorption. Some also image. Examples are the LOPC, UVP, VPR, ISIIS, and SIPPER; others exist. We invite people using various instruments to come together to compare techniques and observations.
Conveners: Ken O. Buesseler, Woods Hole Oceanographic Institution, email@example.com; Margaret L. Estapa, Woods Hole Oceanographic Institution, firstname.lastname@example.org; David A. Siegel, University of California, Santa Barbara, email@example.com
Physical motions associated with submesoscale flows have many important implications for upper ocean planktonic communities and resulting biogeochemical fluxes. For example, upward submesoscale motions can inject nutrients into the euphotic zone, while downward motions can aggregate particles and export them from the euphotic zone. Observations of submesoscale features have largely come from ocean circulation model output or using appropriate satellite data products, and show that submesoscale features are ubiquitous. However, field results linking ocean biogeochemistry to submesoscale flows have lagged numerical experiments. This session brings together studies of submesoscale motions and how they might impact ecological communities, productivity, export and even foraging by higher trophic level species. Such studies may use modeling, remote sensing, sensors on floats, moorings and AUVs, high resolution in-situ sampling and lab experiments to study ocean ecological and biogeochemical processes that are only seen at smaller scales (<10 km). Sites of convergence and divergence that occur on smaller scales will also affect oceanic distributions of plastics, oil spills and other passive tracers, and evidence of these impacts would also be appropriate in this session.
In recent decades, Harmful Algal Blooms (HABs) have expanded geographically, increased in duration and intensity, and resulted in escalated economic costs worldwide. HABs are a major threat to coastal economies because they negatively affect human and ecosystem health, coastal water quality, fisheries and recreation. As scientists continue to unravel the unique drivers and controls of blooms, research programs must be integrated with environmental management, education, and outreach efforts to develop strategies that protect public and resource health. In the last decade, there have been many examples of beneficial interactions between researchers, environmental agencies, industries and the public. For example, collaborations between researchers, aquaculture industries, coastal managers and citizen groups have been particularly successful in protecting public health from HABs while also promoting economic growth. It is promising that such cross-disciplinary collaborations continue to grow, yielding creative solutions to the challenges that HABs create. In this session, we invite presentations of case studies that highlight new or existing collaborations between research and non-research groups that hold a stake in HAB research, including scientists, regulatory agencies, public health groups, decision-makers, private stakeholders, and the public. This forum will provide an environment to foster such synergistic strategies.
The web of interactions between photoautotrophs and other microbes is appearing to be increasingly complex. Predation, allelopathy, mutualism, cell-cell communication, cell-cell carbon transfer, vitamin interactions, etc are some examples of the spectrum of possibly important processes that go beyond the ‘bottom up’ look at ecology and evolution. This special symposium will examine the latest developments in this field. Examples of the communication of this research to broader audiences and K-12 education are welcome.