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Temperature Probe Retrieval

The first dive commenced at sunrise, with ROPOS carrying a newly-devised "tool tray" to the gas hydrates outcrops in Barkley Canyon. Our dive goals (both accomplished) were to retrieve a string of temperature probes and collect a couple of scoops of clam shells from the seabed. The temperature probes, which were originally deployed to a gas hydrates outcrop in Barkley Canyon on 9 September 2009, had to be recovered to adjust measurement accuracy levels. The clam shells will be used to further research into patterns and processes of carbonate shell breakdown in different marine environments.

Benthic Pod 2 Deployment

Our final dive of the cruise commenced in the afternoon, as we raced to deploy and connect our final instrument platform before ship time ran out. Fortunately, we were able to complete the installation, and now all Barkley Benthic Pods have been recovered, refurbished and redeployed.

Barkley Benthic Pod 2

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Acronym Soup

Our morning dive was something of a study in acronyms. ROPOS first placed a CTD on the ODP 889 BPR, then went to retrieve an mPFA. After returning to the IP, ROPOS proceeded to disconnect and recover the SFC along with the CTD and the mPFA.

Translation

The Remotely Operated Platform for Ocean Science (ROPOS) placed a Conductivity-Temperature-Depth (CTD) gauge on the Ocean Drilling Program (ODP) 889 bottom pressure recorder (BPR) in order to compare temperature measurements between these two instruments. As it turned out the BPR reading was 2.93°C while the CTD reading ranged between 2.8501-2.8531°C. Quite cold down there!!

Then we returned to Bubbly Gulch to retrieve a second mini-Pore-Fluid Array (mPFA), like the one we retrieved the preceding dive from Barkley Hydrates. Like its twin, this mPFA was originally deployed in 2009. Here in Bubbly Gulch, the mPFA was positioned next to some intriguing seafloor cracks, which seem to indicate a deeper gas/hydrate source pushing up from below.

After returning to the Instrument Platform (IP), we proceeded to the installed Sea Floor Compliance (SFC) apparatus, which had become quite popular with local crabs (there were at least four large crabs on or next to it!) We disconnected the SFC and recovered it along with the CTD and PFA to ship. Needless to say, ROPOS had its arms full, carrying that mouthful back to the surface!

Fetching the "BB-Aux"

After our morning dive at ODP 889, we steamed 7 hours to ODP 1027 for an evening dive to the broadband seismometer installation there. Unfortunately, our newly installed broadband seismometer auxiliary (a.k.a. "BB-Aux") platform developed an electrical fault and had to be recovered. (The other one at ODP 889, however, is problem-free.)

We dove 2.6km to the seafloor, disconnected the platform, and recovered it to ship. Local rattail fish, who oversaw our efforts, have lost a nice meeting place. But we hope to return it to them during a future maintenance cruise.

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