In addition to comparing the ARMS to the Mullineaux sandwiches, I also wanted to compare recruitment between a recently inactive vent site to a very active site. I had a total of 6 ARMS/sandwich pairs and 2 larval traps, so I decided to put three ARMS/sandwich pairs and a larval trap at an inactive vent site, and the remaining pairs and larval trap at an active site.
The deployments were set up between two dives: one geology and one biology. The first dive was the geology dive to M-Vent, a recently inactive vent site with some diffuse flow still emitting from spires. This was the more challenging deployment as it was a very dynamic landscape with lots of steep cliffs and hard-to-reach places. When deploying things at sites like this, you must always be thinking about if it is accessible for the ROV and if it's possible to recover in the future with another submarine, which in my case is HOV Alvin.
Before the dive, I had planned out three specific locations to deploy the ARMS and as most experiments go, plan A did not work, and neither did plan B nor C. Thankfully a plan D was possible and three ARMS were successfully deployed!
The next set of ARMS were deployed on a biology dive at Tica. This site is dynamic in a different way in that there is so much biological activity, we have to be careful not to disturb anyone, and the many other experiments here have been going on for over a decade.
In these biologically dominated sites, there are typically four zones observed around active vents. In descending order from the active flow emitted from the chimney is (1) Alvinellid zone (2) Riftia zone (3) mussel zone and (4) suspension feeder zone. Deciding on three locations was a little easier this time around because I knew I wanted to deploy one ARMS/sandwich pair in each of the Riftia, mussel, and suspension feeder zones. After cruising around a bit to find a good mound with all three zones, we came across a perfect spot and began deploying the ARMS.
And with that, everything I needed to be at the seafloor made it there and I am happy with the results. It was a long 72 hours of prepping equipment, loading Jason and the elevator, and deploying it all at two sites on two dives. I stepped outside the van and was greeted by the stars. I walked out to the bow, took some time to watch some shooting stars and listen to the waves hit the ship, and then headed down to my bunk for some much-needed sleep.