Astrangia in a Strange LandLatest update July 23, 2018 Started on July 23, 2018
There is a super cool temperate coral that lives in our backyard called: Astrangia poculata, the Northern Star Coral. It is a facultatively symbiotic coral, which means that sometimes it lives with its symbionts, and sometimes... not! "Symbiont-free corals" appear white, and are generally considered "bleached", but not in this case. In this case, the corals are so good at eating that they can compensate for lack of photosynthesis. One reason why these corals might maintain a symbiont-free lifestyle is that they sometimes live too deep for photosynthesis. We are planning to use the OpenROV Trident to explore the coastal mesophotic waters of New England (in our own backyard!), as well as participate in the upcoming NOAA Okeanos ASPIRE cruise that will survey deep-sea habitat in the same region (including Bermuda), to see if we can find Astrangia "in a strange land". Well, strange to us, anyway, since we are used to thinking shallow when it comes to scleractinian (hard) corals. Of course, we'll keep SCUBA diving in the mix, too.
It's always really fun to explore a new dimension of a system we've been working in for a long time.... stay tuned here for updates. The fun starts in a few weeks! ;-)
We have been exploring the shallow-water habitats of the northern star coral, Astrangia poculata, for almost a decade now, and have published a few papers exploring its geographic range, mechanism of movement (sometimes, literally on the backs of turtles!), and the role of symbiosis in the ability of the coral to heal from wounds, and in structuring associated microbial communities (citations below). We have a number of other papers in the queue (in review, in press, or almost-ready-to-submit), which we will post about here in the coming weeks. But we haven't yet had the opportunity to explore it's lifestyle in deeper waters, and we are excited to have the chance this summer/Fall with the OpenROV Trident, and the NOAA Okeanos Explorer. This coral is a cool model system for exploring the mechanisms of symbiosis, along with Aiptasia anemones and Oculina corals. Because it's a facultatively symbiotic coral, we can see brown (with symbionts), white (with very few symbionts), and every shade in between in the field, often side-by-side in nature (see photos below). Their aposymbiotic lifestyle (very few symbionts, if any), is what might support their ability to live in the mesophotic or even deep-sea. Are there any symbionts down there at all? What do the corals look like in their deeper habitats? We don't know (yet), but... stay tuned. That's the point of this expedition, and we'll hope to find out soon. In other words, don't be Astrangia! :-) (Yep, say it with a thick Boston accent....).
Dimond, JL, AH Kerwin, RD Rotjan, K Sharp, FJ Stewart, and DJ Thornhill. 2013. A simple temperature-based model predicts the upper latitudinal limit of the temperate coral Astrangia poculata. Coral Reefs 32(2): 401-409
Perrault, JR, EM Muller, ER Hall, and RD Rotjan. 2015. Presence of the northern star coral on a nesting loggerhead turtle. Reef Encounter 30(1): 46
DeFilippo, L., EM Burmester, L Kaufman, and RD Rotjan. 2016. Patterns of urface lesion recovery in the northern star coral, Astrangia poculata. Journal of Experimental Marine Biology and Ecology. 481: 15-24
Sharp, K.H., Z.A. Pratte, A.H. Kerwin, R.D. Rotjan, and F.J. Stewart. 2017. Seasonal shifts in taxonomic diversity of the microbiome in the temperate coral Astrangia poculata. Microbiome 5(120): 1-14
Burmester EM, Finnerty JR, Kaufman L, Rotjan RD. 2017. Temperature and symbiosis affect lesion recovery in experimentally wounded, facultative symbiotic temperate corals. Marine Ecology Progress Series 570: 87-99.
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