The Atlantis Sulfuric Sub Shop has opened for business!

After 4 dives of recovering our deployed settlement sandwiches, we processed them for 8 full days. We sat under the microscope scanning each sandwich plate, looking for any attached animals that had settled on them during the two weeks they’ve sat on the seafloor. Once that is done, we handed off the plates to Dr. Costa Vetriani’s group where they will analyze the microbes and conduct proteomic and metagenomic work on the bacterial communities. This will allow us to tease apart patterns between the animals and bacteria; if the bacteria are sending cues for animals to settle on these surfaces, emulating the natural processes at our vent sites.

In order to keep the plates preserved for microbial analysis, we had to sort all of our samples in a solution called RNA Later. This is essentially a super salty liquid, that crusts over everything, so we wore gloves the whole time. Throughout this week of sorting, all of our clothes, scopes, and utensils became encrusted in salt. I still don’t feel clean days later. We also had to be conscious of cross-contamination and being sterile between each sample, so we sterilized our equipment after each completed sandwich.

We had many candy breaks, played music, and told jokes to make the hours fly by. While it was tedious, we were seeing successional processes similar to the origins of these hydrothermal vent communities, which was awesome. Thankfully we also got some help from fellow scientists like Susan Mills (WHOI) to sort. In total we sorted 45 half sandwiches, and 16 full sandwiches, totaling 231 plates. We scanned each square, every groove and inside each gunk pile on both sides.

Sorting through the sandwiches we saw a lot of variation in the biofilms. We had sandwiches that had been deployed since the last cruise and a new set that we deployed at the beginning of this cruise. The ones deployed longer typically had thicker biofilms, some with white filamentous bacteria, some were completely clean, and a few had this strong orange color. This made the squares look like Cheez-Its. Combing through them felt like exploring the surface of a foreign planet. I think the last picture could be circulated with the title “Life on Mars??” and would fool a good amount of people.

Of course the goal for this process was to collect all the organisms that were attached to the sandwich and categorize them as settlers or colonists. Whether they had attached and grown as exploring larvae looking for cues, or potentially just exploring a new surface and grazing on the biofilms for food. We did see evidence of biofilm grazing, and attachment by adult mussels with byssal threads left behind. There were many animals which had made homes in the grooves of the plates: mostly polychaete worms and limpets. Amphisamytha galapagensis created mucus tubes covered in sediment that we would have to pick them out off, and other worms like the Serpullid worm Laminatubis alvini created calcareous tubes.

We also found many larval snails, known as veligers as they swim with a velum (a sail-like organ covered in cilia), on our sandwich plates. At this size they are very difficult to find during our sorting, and impossible to identify at the dissecting microscope. Seeing veligers is a good sign. These settlers will help us test our hypotheses by observing patterns of bacterial presence on the plates they’ve attached to and if they are preferentially attaching to sandwiches with older biofilms. We take pictures of each one we find, and preserve them for DNA analysis later, to find out what species they are.

We found plenty of other tiny things while sorting too. Some we knew, others we didn’t. Deep-sea research is time-consuming, and expensive, so we try to make the most of every sample we collect, or organism we find. It’s a highly opportunistic field, which is part of why I love this work, there’s always something new, and so many unanswered questions. Every unknown organism we take pictures of on the compound microscope, and bring it back to the lab where it can be analyze it later.

These are just some of the organisms we’ve found through our shipboard sorting, but there is much more sorting to be done back at the main lab. I will not be part of that process, but I’m hoping for many more larvae! In my next, and last post about this cruise, I will share some more pictures of the deep-sea, and what’s next for this project.

EPR Biofilms4Larvae project is a multi-institutional NSF grant: OCE-1948580 (Arellano), OCE-1947735 (Mullineaux), OCE-1948623 (Vetriani).

Also find us on Instagram @larvallab, #Biofilms4Larvae

The Inactive Sulfides project is a multi-institutional NSF grant: OCE-2152453 (Mullineaux & Beaulieu), OCE-2152422 (Sylvan & Achberger).

Also find us on Instagram @jasonsylvan, #LifeAfterVents