This multidisciplinary cruise led by Dr. Carolyn Ruppel of U.S. Geological Survey is studying the hydrate seeps off the coast of Oregon, US. Methane is a dangerous greenhouse gas that bubbles up from these seeps. However, very little methane seeping from the seafloor ever reaches the ocean’s surface due to a process known as aerobic oxidation of methane, which some scientists call a “biofilter.” Critical knowledge gaps remain about gas hydrate degradation, seafloor methane seepage, and aerobic methane oxidation – this information has implications for the interaction of the sediment-ocean-atmosphere system with global climate change. A team of geologists, geophysicists, biochemists, and benthic ecologists will tackle by examining a selection of the hundreds of methane seeps by constructing a mini-observatory at a seep site near the gas hydrate stability limit and using ROV SuBastian to conduct surveys and collect water, gas, sediment, rock, and biological samples at seep sites along transects from shallower to deeper than the gas hydrate stability limit. Comparisons of the new data with those collected in other well-studied seep provinces (for example, the U.S. Atlantic margin) will advance understanding of global methane emissions from the seafloor and their consequences.

ROV SuBastian Dive 257 – Astoria Canyon
Date: 06/13/2019
Location: Pacific Ocean – Astoria Canyon off the coast of Oregon, US.
Depth: 850 meters depth
Work Completed:  ROV SuBastian headed down to a depth of 850m for an exploratory dive looking at methane seeps and surrounding fauna.

ROV SuBastian Dive 258 – Astoria Canyon
Date: 06/14/2019
Location: Pacific Ocean – Astoria Canyon off the coast of Oregon, US.
Depth: 843 meters depth
Work Completed:  ROV SuBastian headed down to a depth of 843m for an exploratory dive looking at methane seeps and surrounding fauna. Samples will be taken with push cores of microbial mats and images of the bubbles.

ROV SuBastian Dive 259 – Grays Canyon
Date: 06/15/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 500 meters depth
Work Completed:  ROV SuBastian went for an exploratory dive looking at methane seeps and surrounding fauna. Samples will be taken with push cores of microbial mats and images of the bubbles.

ROV SuBastian Dive 260 – Grays Canyon
Date: 06/16/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 1000 meters depth
Work Completed:  ROV SuBastian went for an exploratory dive looking at methane seeps and surrounding fauna. Samples will be taken with push cores of microbial mats and images of the bubbles.

ROV SuBastian Dive 261 – Astoria Canyon
Date: 06/17/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 200 meters depth
Work Completed: During this short, bounce dive, we recovered the Gas Quant lander so that it was prepared for the next day’s dive.

ROV SuBastian Dive 262 – Astoria Canyon
Date: 06/17/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 850 meters depth
Work Completed: On this dive, ROV SuBastian headed down to a depth of 850m for an exploratory dive looking at methane seeps and surrounding fauna.

ROV SuBastian Dive 263 – Astoria Canyon
Date: 06/18/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 850 meters depth
Work Completed: On this dive, ROV SuBastian headed down to a depth of 850m for an exploratory dive looking at methane seeps and surrounding fauna.

ROV SuBastian Dive 264 – Astoria Canyon
Date: 06/19/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 500 meters depth
Work Completed: The team investigated another gas vent site in Astoria Canyon.

ROV SuBastian Dive 265 – Astoria Canyon
Date: 06/20/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 1300 meters depth
Work Completed: The team investigated another gas vent site in Astoria Canyon. The area is on a compressional ridge at about 1370 meters water depth near the Astoria Canyon region. The ridge was likely created as a result of the convergence of two tectonic plates in this area.

ROV SuBastian Dive 266 – Astoria Canyon
Date: 06/21/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 500 meters depth
Work Completed: The dive was in about 500 meters depth where the team sampled biological specimens and retrieved landers that were deployed earlier in the week to measure gas flux from the methane seeps.

ROV SuBastian Dive 267 – Heceta Seep Site
Date: 06/22/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 1200 meters depth
Work Completed: The team sampled gas, corals, clams, and carbonate rocks at this seep site.

ROV SuBastian Dive 268 – Heceta Seep Site
Date: 06/23/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 500 meters depth
Work Completed: There are many mapped seeps close to the dive target, which was previously explored by a ROV in 2018. In addition to gas, biological, and sediment sampling, the BubbleBox lander was deployed during this dive.

ROV SuBastian Dive 269 – Coquille-500
Date: 06/24/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 500 meters depth
Work Completed: The target was an area where several seeps have been previously mapped and where gas has not been previously sampled for analysis. The team conducted methane flux measurements and sampling of biological specimens, sediments, and gas.

ROV SuBastian Dive 270 – Coquille-900
Date: 06/25/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 1000 meters depth
Work Completed: The team investigated the source of a spectacular methane plume imaged overnight. If the bubble source was found, gas samples were collected along with flux measurements and biological and geological specimens.

ROV SuBastian Dive 272 – Astoria Canyon
Date: 06/27/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 500 meters depth
Work Completed: The team conducted methane flux experiments, sampled tubeworms and deep sea corals, and activated landers to measure the rate of methane destruction in the water column.

ROV SuBastian Dive 273 – Astoria Canyon
Date: 06/28/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 500 meters depth
Work Completed: The team conducted methane flux experiments, sampled tubeworms and deep sea corals, and activated landers to measure the rate of methane destruction in the water column.

ROV SuBastian Dive 274 – Nehalem Banks
Date: 06/28/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 200 meters depth
Work Completed: The team explored the site which has microbial mats, deep sea corals, and bubbles from previous dive reports by Hercules.

ROV SuBastian Dive 275 – Astoria Canyon
Date: 06/29/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 1400 meters depth
Work Completed: The team visited a deep site in Astoria Canyon and feature sampling of gas, deep sea corals, and seep organisms and carbonates.

ROV SuBastian Dive 276 – Astoria Canyon 500
Date: 06/30/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 1400 meters depth
Work Completed: The dive focused on the lander site where the ROV retrieved the Gas Quantifier and Bubble Box landers, which are out of battery power by now.

ROV SuBastian Dive 277 – McArthur Promontory
Date: 06/30/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 830 meters depth
Work Completed: The team sampled corals, seep organisms, sediment, and gas.  Quantitative bubble measurements were made.

ROV SuBastian Dive 278 – Grays Canyon
Date: 07/01/2019
Location: Pacific Ocean – off the coast of Oregon, US.
Depth: about 1000 meters depth
Work Completed: The team focused on a site on a compressional ridge where we have imaged a big methane plume in the water column.