What can a mere floor tile tell us about coral health?

By Emily Cunningham

This summer I’m thrilled to be an intern in Bigelow Laboratory for Ocean Science’s first virtual REU cohort! I’m collaborating with Senior Research Scientist Dr. Nichole Price over Zoom to investigate global trends in the biogeography of coral recruitment, when drifting young coral larvae settle and attach themselves to the reef, from 2014 to 2020.

Studying coral recruitment is important as it is a key mechanism that determines the recovery and resilience of a reef after disturbances. Sexual reproduction is the only means through which decimated coral colonies can be rejuvenated, either by quickly re-establishing a once heavily-populated reef with new recruits, or through building colonies outside of their original range. Last year, Dr. Price and her colleagues discovered that from the 1970s through 2014, corals have been recruiting at slower rates in the tropics and establishing new reefs in the subtropics; indicating a slight poleward shift in latitude for coral recruitment. But in the last six years (2014-2020), we have seen some of the worst bleaching events yet. Gaining a better understanding of biogeographic trends in coral recruitment during this intensifying warming period will provide better insight into the extent to which sexual reproduction has continued to aid coral reef recovery.

So where do floor tiles play into all of this? Settlement tiles, usually made out of terracotta, are devices used to measure coral recruitment. They simulate natural substrates that coral settle on, and they are increasingly being used as a non-destructive method to do so due to their low cost, low impact, and replicable nature. Settlement plates are immersed underwater for a period of time, typically just before known spawning events. Then, they are removed, and the coral recruits are counted under magnification to find the density of juvenile coral colonies.

Coral settlement tiles submerged underwater and covered in coral recruits from a study in Fiji (Source: h ttp://repicore.zmt-bremen.com/the-recruitment-tiles-are-out/)

So if there’s no field or lab-work involved, what do I do all day? I’ve actually been spending most of my day curled up with my laptop in upstate New York. I spent the first two weeks identifying papers where coral settlement tiles had been immersed in shallow reef habitats to track coral recruitment by measuring recruit density. I compiled over fifty papers and datasets, from which I now spend my days

extracting density data and detailed methodology information to augment the pre-existing database that Dr. Price and her colleagues had started. Despite working from home, I’m still making interesting connections in the realm of marine science. I’ve had to reach out to many scientists to ask for access for their raw data, including some very big names in the field of coral reef research—it’s so exciting when I get a response from very accomplished scientists with the exact data I need! By the end of the summer, I’ll be able to analyze this data and draw conclusions about whether the latitudinal shift in coral recruitment is consistent across time and space.

A typical day at the home office — a member of the Price lab working on the database outside with her trusty assistant.

In this past month working virtually at Bigelow, I’ve already learned so much—including what makes a good proposal, critical thinking skills, to trust my instincts, and how to reach out to scientists. Weekly Zoom meetings on topics ranging from coding to scientific communication have kept all of the REU participants connected—this week we’re even having a virtual dinner with the head of the REU program, Dr. Fields, where we all get to order our takeout from our favorite restaurants! Bigelow is an incredibly talented and kind community that I’m very excited to be a part of this summer, and I can’t wait to see what I find out about recent trends in coral recruitment.

Emily Cunningham is a Colby College student in Bigelow Laboratory for Ocean Science’s Research Experience for Undergraduates program. This intensive experience provides an immersion in ocean research with an emphasis on state-of-the-art methods and technologies.

What can a mere floor tile tell us about coral health?