Getting your bearings

The ups and downs of working a mile under water

Written by Mandy Joye, 12 April 2014; Posted by Mandy Joye, 16 April 2014

People often ask ‘what’s it like to be in the Alvin?’ My answer is always the same: it’s magical; a life changing experience; more incredible than you could ever imagine. It is magical. It is life changing. It is incredible. But sometimes it’s also frustrating: scientific instruments may not perform to specs or may fail all together and every once in a while, finding a target – that proverbial needle in a haystack a mile under water – is tough. Then there are the cases where you want to do one thing, go to one place, grab one more sample, and for whatever reason, it does not happen and you feel like a failure; those things leave me with a feeling of immense frustration.

I had a frustrating dive on April 11th because I failed to complete the most important task on the dive plan. The fact that we accomplished everything else did not counterbalance the fact that I did not accomplish the primary goal. Sometimes that happens and well, it’s frustrating.

The primary goal of that dive was to sample the colorful oil/gas chimneys we discovered at Oil Mountain, at the GC600 site. But we could not find the mound despite the fact that we had visited it three times before and had a good position on it. It was maddening. Ultimately we moved and accomplished everything on the list but not getting those chimney samples was tough to swallow.

But, thinking back on what we did accomplish takes a little of the sting away. We landed on the seafloor adjacent to a magnificent seafloor depression that had a hydrate mound in its center (image 1). We found multiple mounds with small oil chimneys (figure 2) though nothing we saw was as spectacular as the large, colorful and dynamic chimneys we observed and documented at Oil Mountain. We mounted a video time-lapse recording camera system at these small oil chimneys and captured them waxing and waning over the course of several hours. This was simply amazing (check out the ECOGIG.ORG You-Tube channel for a video showing this soon).

While looking for the Cobra Brine (image 3), we found something we had lost a few days earlier – a coring arm from the multiple corer (!)…just sitting there, all alone at the seabed (image 4). We spent some time coring oily, gassy sediments – something my lab can never have enough of for use in subsequent experiments (image 5) – and then we went searching for microbial mats.

Usually it is pretty straightforward to distinguish a microbial mat from mineral sulfur. At GC600, it’s not so easy (image 6). Sulfate reduction rates are so extremely high in these oily and gassy sediments that often what looks like a fluffy Beggiatoa mat is actually a fluffy ball of elemental/colloidal sulfur. Furthermore, the actual microbial mats at GC600 seem to grow atop gas hydrate or carbonate outcrops making it extremely difficult to collect them using a standard push core. We did get some mat cores on this dive, but it was not easy!

And, where there are mats there are mussels (image 7) and both tend to happily co-occur with oil. In fact, at this site, mussels seems to thrive in bubbling oil seeps – this is something new, something we’ve not seen before. So, despite the frustration of the day, we did confirm our recent discovery of mussels thriving in oil.

Finally, today was a ‘newbie’ dive. This was the first Alvin dive for one of the PhD students in my group, Mary Kate Rogener (image 8) and what a treat that the camera recovery provided a “selfie” of Mary Kate and pilot Bruce Strickrott. That picture made her day – what a treat for Mary Kate to get a perfect picture of herself looking through the Alvin window sitting on the bottom of the ocean 1200m below the sea surface. I suspect her parent’s were pretty thrilled too.