Spatial Epidemiology of Coral Disease

How does the spatial distribution of Montastrea annularis and M. faveolata impact Caribbean yellow band disease dynamics?

Williams, Sara D.1, 2; Muller, Erinn M.2

1College of William and Mary, Williamsburg, VA 23185; 2Mote Marine Laboratory, Sarasota, FL 34236

Coral diseases have caused significant mortality over the past several decades. However, whether they are contagious is unknown. We used spatial epidemiology to examine whether Caribbean yellow band disease (CYBD) followed a contagious-disease model. Spatial patterns of healthy and diseased colonies of Montastrea annularis and M. faveolata were mapped within 100 m2 sites around St. Croix, US Virgin Islands.  The patterns were analyzed at two spatial scales: within sites (meters) and among sites (100’s of meters to kilometers).  Although M. annularis was more clustered within sites, CYBD was more prevalent on M. faveolata. Furthermore, host aggregation did not influence the spatial pattern of CYBD at large spatial scales. To complement our in situ data, we developed a disease-transmission model based on the site level data of the two species. M. annularis was more susceptible to CYBD if the disease was communicable by ≤3m, with the two species being equally susceptible at transmission scales > 3 m. Therefore, the model indicated that if CYBD was transmissible, M. faveolata would be at least equally susceptible as M. annularis, whereas observed data suggested the opposite. The results of our in situ data and complementary model suggest CYBD may not follow a contagious-disease model.

…So now that I have hopefully “wowed” you with my formal research abstract, let me tell you a bit about myself and my research on a less ceremonious level. I am a senior who cannot get enough of the college, so I have one more semester left to soak it all in. Ok, really, I just changed my major from biology to physics in the middle of sophomore year and decided to do honors, so I have a couple of more class requirements left. I am from Richmond, VA, and I love spending time on the James River with my family and two dogs. I grew up on the James and it is a big part of why/how I got into doing marine science. I am a PADI Dive Master with the Dive Shop of Richmond; I have been diving since I was 15, and every day I spend out of the water is just part of a surface interval waiting for my next dive. Some of my favorite weekends at college have been spent teaching SCUBA diving to groups of my class mates in the Adair pool. After I graduate in the winter, I will work as a lab tech for a year or two before applying for graduate school and eventually getting my PhD in marine science.

I absolutely love doing marine science research … and coral. I finished up my honors thesis on determining a time constant of mixing in the gastrovascular system of coral just last week ( you can read about this research project here: http://ccsrg.blogs.wm.edu/archives/author/sdwilliams ). And now I am very excited to go back to Mote Marine Lab in Sarasota, FL, to finish up the research from my REU (research experience for undergraduates — program funded by the NSF) from last summer with Dr. Erinn Muller. I really like finding ways to combine physics with studying coral reefs. My thesis did this more directly, but I still use a lot of the skills I picked up from being a physics major while working on this project. I like taking a more quantitative and modeling approach to biology… as long as I get to have some fun in the field as well. Last summer, I spent 10 weeks at Mote working on this project. About 7 of those weeks were spent identifying coral species in the photo-quadrats, and then the last 3 weeks involved running statistics and writing the disease model code. It was a ton of computer work, so I did not end up being as tan as I should have been while living in a beach town in Florida for the whole summer. However, it was really exciting and satisfying to see all of my long, hard work on the computer come together in the end with the spatial statistics really coming together with some meaningful results. It was just really cool seeing how all of the pieces fit together in the end. I also got to spend some time in the field at the Mote Keys Lab on Summerland Key working on a side project in the coral nursery. It was pretty awesome getting to combine my love of diving with science. In the spring, I had the wonderful opportunity to present my spatial epidemiology research at the Benthic Ecology Meeting. It was my first scientific conference, and I was incredibly lucky to have the chance to give an oral presentation and get some great feedback on my research.

Keys Lab on Summerland Key, FL

Keys Lab on Summerland Key, FL

Sara Williams behind line of Acropora fragments grown in coral nursery

Sara Williams behind line of Acropora fragments grown in coral nursery

Enough about this past year, let me tell you what’s going to happen this summer. After two weeks of field work in the Virgin Islands with Dr. Mark Patterson and the biomechanics lab from VIMS, I will drive down to Sarasota and spend the rest of the summer finishing up the research from my REU. I will do some more mapping in order to get a larger sample size for greater statistical significance on the rest of the data that Dr. Muller collected from around St. Croix back in 2009, and I will also work on the disease model to incorporate a few more parameters for better disease spread simulation. Dr. Muller and I will also work on getting the research ready for publication. By the end of the summer, I will hopefully have a paper submitted for publication in some scientific journal. I am really looking forward to learning the process that goes into getting an article published.

Thinking about all of the exciting research I get to do this summer is about the only thing getting me through finals right now, I just cannot wait to be done with studying and back in the lab or in the field!