Saturday, July 18, 2015

4804: Part 3

We flew over the jagged precipice and continued across the mussel bed. It looked for a while like the mussels might have been thinning out, but then we reached another jagged cliff. It stuck up from the seafloor by about a meter, so it was much smaller than the last one. We saw only a little bit of bubbling, but the mussels were still pretty dense. We collected a few more and also used Alvin's slurp function to suck up animals living between the mussels. We couldn't really be sure what we were getting, since the in-between animals are too small to see, but we thought it would be an interesting sample to examine back in the lab.

Our third precipice was the most dramatic by far, and as we pulled up to it, we could barely believe our eyes. It rose a good 8 or 10 meters off the bottom, and when we reached the top, we could see it was a straight shot down the back side. The entire surface was jagged carbonate covered in dense mussels, which created an even more jagged surface, and it was the most vertical drop we had seen so far. If you were an underwater aqua-man and you fell off the back side of this cliff, you would have a very, very bad day.

The mussels were covered in a bacterial mat at this third precipice, and even some of the crabs were decked in white fuzz. We found a spot of active bubbling and focused an ultra-high-definition camera on it to record for a few minutes. After collecting a few more mussels, we looked back at the bubble source and discovered it had stopped. Hm, we all thought, that's interesting. Around this time, all of us were getting hungry, so in the time it took us to pull out sandwiches, take two bites, and decide where to go next, the bubbling went from a full stop to gushing like Old Faithful. Adam was particularly interested in what turns the bubbling on and off, so we turned the ultra-high-def camera back on and watched while it gushed. After a few minutes, the bubbles slowed a bit to a steady stream, then started spurting again and eventually stopped. It was really interesting to note that the bubbling rate can vary on such a short time-scale. Besides, sitting in a submarine next to a methane seep is without question the coolest place I've ever eaten lunch.

We still had more sampling to do, so we flew out over the mussel bed in search of sediment. We needed a few different spots where the seafloor was clear enough to push plastic cores into it, but we had a really hard time finding one. Even when the mussels thinned out and there were mostly dead shells, the shells were so dense we couldn't get any cores. We eventually found one location with a patch of bacterial mat and drove the cores in there. It's not as many replicates as the scientist analyzing them wanted, but we tried.

I sketched out some of the organisms I saw on the bottom.
The labels are in Craig's handwriting, partly because he
helped me identify each thing, but mostly because his
handwriting looks way cooler on a diagram than mine.
Flying to the edge of the mussel bed was actually a really neat experience, because we saw a lot of pelagic animals on the way. There were giant rays laying on the shell hash. We saw one shark and lots of bony fish. One in particular was pretty common, and it kept swimming in front of my window. It was about 3 inches long and had a yellow-orange head but a blue-brown body. I sketched it out on my note pad so I would remember it. There was another organism, which I presume to be a pelagic holothurian (sea cucumber), that hung suspended in a J-shape about a meter above bottom, motionless. There was some little swimming guy that was shaped like a ghost in a sheet, except every once in a while, the sides of the sheet would fly up like wings. I have yet to figure out what he was. But there was one organism in particular that caught my eye. I couldn't tell at all what it was, so I asked Chris to fly as near to it as he dared. I got as close to the front port hole as possible, practically laying on my stomach and pressing my nose on the acrylic until I could get a clear view. The organism was long and thin and red, and it had fleshy orange spikes all along its body. There was a clear gelatinous structure at the end closest to me. As we approached, the clear part got blown up into the water column until it was vertical, hanging suspended.

Just as soon as I had gotten a semi-decent view of the animal, we got too close to the seafloor and kicked up dust with Alvin's thrusters. My port hole view was obscured by benthic sediment, and Chris started moving away from the dust cloud. I grabbed my clipboard to sketch the animal, and as soon as I did, my ears caught wind of a familiar song playing softly over Alvin's speaker system. It was "Hopeless Wanderer" by Mumford and Sons. My theme song. I can't explain to you how high my soul was soaring at that moment - at the bottom of the ocean, seeing unidentifiable creatures, discovering new habitats, listening to my very own musical mantra. That moment will be forever seared into my memory.

When I first showed Craig, my doctoral adviser, my sketch of the unknown red thing, he asked if I had been low on oxygen and imagined it. I insisted I wasn't, so we looked at the video recording together later to see what it was. Our best idea for now is that it was an enteroneust, an acorn worm, and the clear part was its extended anterior end. Craig still wasn't sure about the fleshy orange bits, but a tentative identification is the best we can do for now.

Part 4 of this post is coming soon.

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