Blizzards Drones and Gas Bubbles

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Yesterday under calm seas we completed work at the Oregon Offshore site, turning one of the Benthic Experiment Platforms (BEP). After we left Newport we tried twice to recover the BEP at the Oregon Shelf Site in 80 m water depth, but visibility was near zero due to a snow storm of material in the water – there is a reason our coasts are some of the most biologically productive in the world. We are anxious to turn the zooplankton instrument and digital still camera there before the full solar eclipse because there is intense interest in witnessing, in real time, how the marine organisms respond to the full solar eclipse.

We are now working at the Southern Hydrate Ridge site, a dynamic environment >2000 ft beneath the oceans surface where methane-ice compounds (methane hydrates) are sequestered beneath the seafloor. The gas hydrates are metastable such that methane is released in the subsurface and migrates through small channels to the seafloor, where the methane gas is released either as gentle bubble streams or more rarely as explosive events.

The OOI-NSF Cabled Array chose a site called Einsteins’ Grotto at Southern Hydrate Ridge as its main focus site. Here, in 2014 explosions of methane bubbles and sediment issued from a large orifice in the partially lithified sediments. Our annual visits and a cabled digital still camera has documented profound changes in this site. From a gentle mound in 2010, to a large steep sided explosion pit in 2014, and this year the pit has grown in length several meters and one side of the steep hummock has collapsed. Gases emanating from the seafloor through the sediments support dense microbial mats rimmed by large clams with hemoglobin that hosts symbiotic microbes in their guts.

This year, the microbial mats have also changed dramatically, dying off in some areas and expanding in others. During the wee hours of the morning, Co-Chief Scientist Orest Kawka lead the dive to recover and install an underwater mass spectrometer to measure the methane concentrations issuing from the seafloor. These data, coupled with instruments that measure flow into and out of the seafloor, will be used to calculate the flux of methane from this system into the water column.

Yesterday was exciting for the Cabled Array team because Chuck McGuire, a lead engineer on the project at the Applied Physics Laboratory brought onboard a drone to document cruise activities off the ship – providing new perspectives. The team gathered on the fantail to watch the drones inaugural flight—it was wonderful providing a view of the R/V Revelle, operated by Scripps Institution of Oceanography, that we never get to experience.