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| griddap | Subset | tabledap | Make A Graph | wms | files | Accessible | Title | Summary | FGDC | ISO 19115 | Info | Background Info | RSS | Institution | Dataset ID | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_986875_v1 | https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_986875_v1.graph | https://erddap.bco-dmo.org/erddap/files/bcodmo_dataset_986875_v1/ | public | [Water Column Methane Oxidation Gulf of Alaska] - Water column methane, methane oxidation, and pmoA gene copies above methane seeps determined from samples collected off the Aleutian Islands, Gulf of Alaska on R/V Atlantis cruise AT50-24 in May to June 2024 (Collaborative Research: Redefining the footprint of deep ocean methane seepage for benthic ecosystems) | Cold seeps along the eastern Aleutian subduction zone in the Gulf of Alaska fuel benthic ecosystems through microbial methane (CH₄) consumption, yet the structure and controls of water column CH₄ oxidation in these deep, cold waters remain poorly resolved. During a May–June 2024 expedition with the R/V Atlantis and HOV Alvin, we studied CH₄ and its bacterial oxidation from surface to seafloor above three deep seep sites (2000 to 5000 meters): Edge, Shumagin, and Sanak, by combining radiotracer incubations with pmoA gene profiling. CH₄ oxidation occurred throughout the water column, with peak rates (1 to 242 nanomoles per liter per day) in near-seafloor Alvin samples and 0.1 to 0.25 nanomoles per liter per day in CTD rosette samples 10 to 30 meters above bottom. Rates varied by site and depth. CH₄ oxidation in surface waters, coinciding with an algal bloom, suggests cryptic cycling via in situ production and consumption. A ~325-meter near-bottom CTD transect at Sanak revealed lateral gradients in CH₄ and oxidation aligned with bottom currents, with oxidation highest near hydrate-bearing gas vents and at the off-seep distal end. These findings show that aerobic CH₄ oxidation peaks near the seafloor to ~30 meters above but extends laterally and vertically beyond active seepage. Oxidation was detected even where methanotroph gene abundance was low, potentially indicating the influence of lateral CH₄ transport and tidal currents. The methanosphere thus emerges as a dynamic and spatially diffuse microbial system shaped by CH₄ availability and physical transport processes.\n\ncdm_data_type = Other\nVARIABLES:\nDate_UTC (unitless)\nCTD_Start_Time_or_Alvin_Niskin_Closure_UTC (unitless)\ntime (Iso_datetime_utc, seconds since 1970-01-01T00:00:00Z)\nSite_Name (unitless)\nCTD_or_Alvin_Sample_Number (unitless)\nWaypoint (unitless)\nlatitude (degrees_north)\nlongitude (degrees_east)\nWater_Depth (meters below sea level (mbsl))\nMethane (nanomoles per liter (nmol L-1))\nMethane_oxidation_Replicate_1 (nanomoles per liter per day (nmol L-1 d-1))\nMethane_oxidation_Replicate_2 (nanomoles per liter per day (nmol L-1 d-1))\nMethane_oxidation_Replicate_3 (nanomoles per liter per day (nmol L-1 d-1))\npmoA_gene_copy_number (Log pmoA copies per liter)\n | https://erddap.bco-dmo.org/erddap/metadata/fgdc/xml/bcodmo_dataset_986875_v1_fgdc.xml | https://erddap.bco-dmo.org/erddap/metadata/iso19115/xml/bcodmo_dataset_986875_v1_iso19115.xml | https://erddap.bco-dmo.org/erddap/info/bcodmo_dataset_986875_v1/index.htmlTable | https://osprey.bco-dmo.org/dataset/986875
| https://erddap.bco-dmo.org/erddap/rss/bcodmo_dataset_986875_v1.rss | https://erddap.bco-dmo.org/erddap/subscriptions/add.html?datasetID=bcodmo_dataset_986875_v1&showErrors=false&email= | BCO-DMO | bcodmo_dataset_986875_v1 | |||
| https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_986866_v1 | https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_986866_v1.graph | https://erddap.bco-dmo.org/erddap/files/bcodmo_dataset_986866_v1/ | public | [Water column methane, methane oxidation, and pmoA gene copies] - Water column methane, methane oxidation, and pmoA gene copies above southern California methane seeps determined from samples collected on R/V Atlantis cruise AT50-12 in July 2023 (Collaborative Research: Redefining the footprint of deep ocean methane seepage for benthic ecosystems) | Marine methane (CH₄) seeps are dynamic biogeochemical systems that modulate carbon cycling and support high-biomass communities through microbial methane (CH₄) oxidation. While most CH₄ is consumed anaerobically in sediments, a fraction enters the water column, where aerobic methanotrophs form a biological filter limiting CH₄ flux to the atmosphere. However, the extent to which this microbial activity and CH₄ influence extend beyond visibly active seep zones remains poorly constrained, with implications for deep-sea food webs, biogeochemical gradients, and carbon cycling. We investigated CH₄ dynamics and methanotroph distribution across three seep sites on the Southern California margin (Del Mar, Santa Monica (800 meters) Mound, Lasuen Knoll; ~400–1200 meters depth). Using radiotracer (³H-CH₄) incubations, CH₄ concentration profiling, and particulate methane monooxygenase (pmoA) gene quantification, we sampled vertical and horizontal transects and near-bottom waters via the HOV Alvin. CH₄ oxidation was active not only within seep plumes but also in off-seep regions, with the highest rate (454 nanomoles per liter per day) observed within a CH₄-rich bubble plume. pmoA gene abundances remained relatively stable across both seep and off-seep waters, suggesting a persistent CH₄-oxidizing potential. These findings support an expanded \"methanosphere,\" a CH₄-influenced microbial zone shaped by physical transport and environmental gradients. This dataset is part of a PhD thesis: Klonicki-Ference, Emily F. \"Microbial Regulation of Methane and Redox Dynamics in the Water Column: From a Proterozoic Ocean Analog to Modern Marine Seeps.\" PhD diss., University of California, Los Angeles, 2025.\n\ncdm_data_type = Other\nVARIABLES:\nDate_UTC (unitless)\nCTD_Start_Time_or_Alvin_Niskin_Closure_UTC (unitless)\ntime (Iso_datetime_utc, seconds since 1970-01-01T00:00:00Z)\nSite_Name (unitless)\nCTD_or_Alvin_Sample_Number (unitless)\nWaypoint (unitless)\nlatitude (degrees_north)\nlongitude (degrees_east)\nWater_Depth (meters below sea level (mbsl))\nMethane (nanomoles per liter (nmol L-1))\n... (4 more variables)\n | https://erddap.bco-dmo.org/erddap/metadata/fgdc/xml/bcodmo_dataset_986866_v1_fgdc.xml | https://erddap.bco-dmo.org/erddap/metadata/iso19115/xml/bcodmo_dataset_986866_v1_iso19115.xml | https://erddap.bco-dmo.org/erddap/info/bcodmo_dataset_986866_v1/index.htmlTable | https://osprey.bco-dmo.org/dataset/986866
| https://erddap.bco-dmo.org/erddap/rss/bcodmo_dataset_986866_v1.rss | https://erddap.bco-dmo.org/erddap/subscriptions/add.html?datasetID=bcodmo_dataset_986866_v1&showErrors=false&email= | BCO-DMO | bcodmo_dataset_986866_v1 |