The voyage of the Dawn Treader: part 5
It was a long, productive day. I boarded the Dawn Treader at 6:30 am, and after disembarking, I went straight to the lab. My samples were finished at 7 pm - over a 12-hour workday. It was awesome.
Friends, it has come time to recover the samplers I deployed at sites in Stellwagen Bank National Marine Sanctuary earlier this summer. I was able to reach two of my three sites in the same day, diving at the shipwreck of the Josephine Marie and then at the Sponge Forest, a boulder site in the middle of the Sanctuary. I used the chance while I was underwater to collect samples of animals living at each site as well.
You may remember the Sponge Forest was covered by sand when I first dove there in June, which was a complete surprise to me. I suspected it may have been buried during one of the nor'easters that hit New England this spring. The possibility for an unstable seafloor plus the heavy fishing activity around the Sponge Forest made me suspect my samplers may have disappeared over the summer. (As my buddy and I suited up to dive, we could see 4 trawlers in our vicinity.) But lo and behold, both sets of fouling panels were still there! The larval traps had disappeared, likely swept away by a swift current, but I was excited to get 2 out of my 4 samplers back.
The other dive of the day, on the Josephine Marie shipwreck, was even more productive. I collected tissue samples from anemones living on the wreck and recovered all 4 of the samplers I had deployed - larval traps and fouling panels. It was a great day out on the boat, and I didn't even get seasick!
Back in the lab, I preserved my anemone tissue in ethanol and then set about examining my fouling panels. I had been hoping that the tunicate Didemnum albidum, the target species for my study, would settle on the panels over the course of the summer, but it appears they did not. It sounds disappointing, but the absence of Didemnum is also informative. My panels were deployed throughout Didemnum's reproductive season, so the lack of recruitment means that this species either (1) doesn't reproduce every year (possible), (2) doesn't disperse larvae 10 ft away from the shipwreck (unlikely), (3) requires a surface with a more developed biofilm for settlement (likely). I'll have to continue researching to figure out which one it is.
My fouling panels were not empty, though! At the Josephine Marie, they were populated by hydroids, limpets, and bryozoans. The hydroids were two cold-water species that I had seen on the WHOI pier before and could identify right away (Ectopleura crocea and Obelia geniculata), while the limpet reminded me of Crepidula fornicata, common in Woods Hole as well. I suspect it may be a different species in the genus Crepidula. The bryozoans were a bit more difficult, and I'm still working on them. There was Lichenopora, a species I had seen in the Arctic years ago, plus two others that I haven't yet identified.
What's crazy is that bryozoans don't occupy a lot of the surface on the shipwreck, but they were very common on the panels. I'm thinking that bryozoans and hydroids may be the first species to recruit to new surfaces with little biofilm far offshore. Part of me wants to get a permit to sink a brand-new shipwreck and watch what colonizes it over years. Maybe a subject for a future proposal...
It was a productive day, and I was glad to see good results from my study!
Friends, it has come time to recover the samplers I deployed at sites in Stellwagen Bank National Marine Sanctuary earlier this summer. I was able to reach two of my three sites in the same day, diving at the shipwreck of the Josephine Marie and then at the Sponge Forest, a boulder site in the middle of the Sanctuary. I used the chance while I was underwater to collect samples of animals living at each site as well.
You may remember the Sponge Forest was covered by sand when I first dove there in June, which was a complete surprise to me. I suspected it may have been buried during one of the nor'easters that hit New England this spring. The possibility for an unstable seafloor plus the heavy fishing activity around the Sponge Forest made me suspect my samplers may have disappeared over the summer. (As my buddy and I suited up to dive, we could see 4 trawlers in our vicinity.) But lo and behold, both sets of fouling panels were still there! The larval traps had disappeared, likely swept away by a swift current, but I was excited to get 2 out of my 4 samplers back.
The other dive of the day, on the Josephine Marie shipwreck, was even more productive. I collected tissue samples from anemones living on the wreck and recovered all 4 of the samplers I had deployed - larval traps and fouling panels. It was a great day out on the boat, and I didn't even get seasick!
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| One of the bryozoans on my fouling panels from the Josephine Marie shipwreck |
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| Lichenopora, one of the bryozoans on my fouling panels from the Josephine Marie shipwreck |
What's crazy is that bryozoans don't occupy a lot of the surface on the shipwreck, but they were very common on the panels. I'm thinking that bryozoans and hydroids may be the first species to recruit to new surfaces with little biofilm far offshore. Part of me wants to get a permit to sink a brand-new shipwreck and watch what colonizes it over years. Maybe a subject for a future proposal...
It was a productive day, and I was glad to see good results from my study!
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