The ASLO journal editors convene this invitation-only special session to recognize authors that published highly cited or highly downloaded articles in 2020-2021 in the ASLO family of journals: Limnology and Oceanography , Limnology and Oceanography: Methods , Limnology and Oceanography: Letters , and Limnology and Oceanography Bulletin. The ASLO journals are a success because authors publish their finest work here. We greatly appreciate the contributions of these authors 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 lead 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. Although our selections are based on reader interest, we note that the authors of these articles are representative of ASLO’s broad geographic reach and include several early career researchers.

Lead Organizer: Rita Franco-Santos, CSIRO, Oceans & Atmosphere (rita.franco-santos@outlook.com)

Co-organizers:

David Hambright, University of Oklahoma (lo-editor@aslo.org)

James Cloern, USGS (loletters-eic@aslo.org)

Laura Falkenberg, The Chinese University of Hong Kong (lobulletin-editor@aslo.org)

Paul Kemp, ASLO (lomethods-editor@aslo.org)

Presentations

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01:30 PM

An international laboratory comparison of dissolved organic matter composition by high resolution mass spectrometry: Are we getting the same answer? (5559)

Primary Presenter: Juliana D'Andrilli, Louisiana Universities Marine Consortium (jdandrilli@lumcon.edu)

High-resolution mass spectrometry (HRMS) has become a vital tool for dissolved organic matter (DOM) characterization in aquatic systems. The upward trend in HRMS analysis of DOM presents challenges in data comparison and interpretation among laboratories operating instruments with differing performance and user operating conditions. It is therefore essential that the community establishes metric ranges and compositional trends for data comparison with reference samples so that data can be robustly compared among research groups. At the ASLO conference in Victoria, 2018, a small group of aquatic scientists working with mass spectrometry decided to address this need by initiating an international ring trial, in which the same four samples from the International Humic Substances Society would be analysed by as many laboratories as possible, in order to determine instrument variability, publish benchmark metric values for ongoing use, and reduce scientific and communication barriers. The laboratory comparison was a great success – 16 laboratories with 17 commercially purchased instruments participated, and analysed the samples in positive and negative electrospray ionization modes. Instrument variability was rather high in terms of the mass window (the range of masses) that they were tuned to, but largely garnered the same information from the four samples, because DOM has so many repeating patterns over the whole mass range. About 1000 common ions were found in each mode for each sample, and the detection of these can be used for establishing and testing new methods. The metrics produced for weighted averages of O/C, H/C, m/z and aromaticity can be used for putting all new results into international context in future studies that use one of the four standard mixtures.

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01:45 PM

The relevance of environment vs. composition on dissolved organic matter degradation in freshwater systems (6702)

Primary Presenter: Núria Catalán, IDAEA-CSIC (ncatalangarcia@gmail.com)

Dissolved organic matter (DOM) composition exerts a direct control on its degradation and subsequent persistence in aquatic ecosystems. Yet, under certain conditions, DOM degradation patterns cannot be solely explained by its chemical composition, highlighting the relevance of environmental conditions for DOM degradation. Here, we will discuss the results of our experimental assessment on the relative influence of composition vs. environment on DOM degradation based on laboratory bioassays. We inoculated contrasting DOM sources with a standardized bacterial inoculum under distinct conditions mimicking different environmental settings. Our results show that the chemical composition of DOM was more important than the environment in determining its decay patterns and we will discuss the application of the bacterial inoculum as a standard method in this and other studies. The results of a similar experimental contrast in freshwater sediments will also be presented, where the balance between sediment organic matter depositional environments (i.e. composition) and drought exposure (i.e. environment) are at interplay to drive the organic matter compounds present in the sediment. Those experiments, as well as an additional assessment of the literature across freshwaters, soils and the ocean, will lead us to discuss how the relative importance of chemical composition and ecosystem properties diverges across ecosystems or so does our conceptualization on organic matter degradation controls.

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02:00 PM

Using eDNA to track carbon from source to sink: Moving from basic to actionable science (7518)

Primary Presenter: Nathan Geraldi, Nature Metrics Ltd. (nathan.geraldi@kaust.edu.sa)

Blue carbon is the organic carbon in oceanic and coastal ecosystems that is captured on centennial to millennial timescales. Maintaining and increasing blue carbon is an integral component of strategies to mitigate global warming. Marine vegetated ecosystems (especially seagrass meadows, mangrove forests, and tidal marshes) are blue carbon hotspots as organic carbon is buried within their habitat and in surrounding environments. In addition, depositional environments throughout the ocean can also provide an important global sink of blue carbon, including carbon from macroalgae and other primary producers. Tracking the source and fate of organic carbon throughout oceans will support conservation and restoration schemes aimed at enhancing blue carbon sequestration and avoiding greenhouse gas emissions. Here we review recent research and the potential of genomic based techniques to track the provenance and fate of organic carbon and highlight next-steps in validating the use of eDNA to track and even quantify the sources of organic carbon in marine environments.

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