©2026 Biological and Chemical Oceanography Data Management Office.Funded by the U.S. National Science Foundation
©2026 Biological and Chemical Oceanography Data Management Office.Project title: Collaborative proposal: In situ measurements of aerobic methane oxidation rates in the deep sea (AMOR)
Recent discoveries of tens of thousands of methane-rich gas seeps on ocean continental margins around the world and elevated methane concentrations found in the overlying water column led to our proposal to quantify the fate of dissolved methane derived from hydrocarbon reservoirs in the underlying ocean crust.
Key research goals included determination of water column dissolved methane concentrations resulting from injection by dissolution of rising bubble plumes, the characterization of the microbial community and microbial methane oxidation (consumption) rates in deep bottom waters near seeps, and the relative importance of advective dissolved methane transport away from seep sources. Most of the methane released as bubble plumes from gas seeps dissolves into the overlying oxygenated water column within a few hundred meters of the seafloor. However, determination of in situ rates of microbial aerobic methane oxidation rates (MOx) of the dissolved methane had remained a challenge, even though it is critical for understanding how important seep-derived methane might be in water column carbon recycling plus net loss to the atmosphere. Previous ex-situ laboratory and shipboard work on MOx had revealed possible relationships to methane concentrations, “bacterial numbers”, physical processes, stratification, oxygen concentration and other factors. Shipboard determinations of MOx were achieved through carefully-designed ex situ incubation measurements of seawater samples returned to the surface. However, other researchers have questioned the applicability of these shipboard rate measurements to in situ rates, since the effects of depressurization following deep-water sample retrieval are unknown and one- to three-week lags observed in the onset of MOx are not supported by their methane stable isotopic results from the same study. In addition, these previous studies produced “potential rates” because of limited incubation data or required spiking with articially high methane concentrations during shipboard experiments.
We measured MOx and microbial community dynamics in situ on the seafloor in order to obviate these uncertainties and to answer key questions about the efficiency of natural methane removal in the bottom waters above a well-described group of deep-sea methane seeps on the upper slope off Delaware at approximately 300 meters depth. Determination of in situ AMOR rates and monitoring the driving factors causing variability in MOx required us to conduct simultaneous measurements of in situ dissolved methane and oxygen concentrations plus bottom water transport rates using acoustic Doppler techniques, while simultaneously collecting samples for quantifying the associated microbial community in the water column at upper slope gas seep sites. We utilized lander-based, multi-sensor technology developed during the first year of the our project at UNC-Chapel Hill, nick-named AMOR, to make the concentration and rate measurements, in collaboration with collaborating microbiologists at the University of Southern California (USC). The USC group assessed the entire microbial community composition using 16S rRNA genes and metagenomes to determine which genes are upregulated under methane-oxidizing conditions (from transcripts recruited to metagenome-assembled genomes).
The primary accomplishments from the AMOR project include:
Our results have so far led to several publications and meeting presentations, plus valuable research experiences for both graduate and undergraduate students. Integration of chemical and biological data from this in situ project have allowed for the start of unprecedented examination of key drivers for the fate of methane released in bottom waters of the deep-sea from both natural gas seeps and from accidental releases associated with fossil fuel drilling and extraction operations.
@font-face {font-family:Wingdings; panose-1:5 0 0 0 0 0 0 0 0 0; mso-font-charset:2; mso-generic-font-family:decorative; mso-font-pitch:variable; mso-font-signature:0 268435456 0 0 -2147483648 0;}@font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:-536870145 1107305727 0 0 415 0;}@font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-536859905 -1073697537 9 0 511 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0in; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}p.MsoCommentText, li.MsoCommentText, div.MsoCommentText {mso-style-priority:99; mso-style-link:"Comment Text Char"; margin:0in; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}span.CommentTextChar {mso-style-name:"Comment Text Char"; mso-style-priority:99; mso-style-unhide:no; mso-style-locked:yes; mso-style-link:"Comment Text"; font-family:"Times New Roman",serif; mso-fareast-font-
Last Modified: 11/10/2025
Modified by: Christopher S Martens
Principal Investigator: Christopher S. Martens (University of North Carolina at Chapel Hill)