ACROPORID SUCCESS AT HORSESHOE REEF!
Since 2007, Coral Restoration Foundation™ has returned over 220,000 corals to more than 34 different reef sites throughout the Florida Keys! Differences in three-dimensional structure, the presence of different species and populations, among numerous other aspects help make each reef site somewhat unique from one another. All of these different factors impact restoration success and by collecting different forms of data, we gain significant insights on all of the important metrics (e.g., growth, survivorship) which give us even more information on how the corals we've returned to the wild are doing at each site!
Recent analyses conducted on past coral outplants at Horseshoe Reef in Upper Key Largo are showing great results! Using photomosaic technology, Coral Restoration Foundation™ has watched our Acroporids—our staghorn and elkhorn coral species—grow from young fragments to large, thriving coral colonies in little time!
How Does CRF™ Monitor Restored Corals?
First, let’s talk about photomosaics!
Currently, our science team monitors restored corals using high-resolution, large-scale, interactive images called photomosaics. Restoration practitioners can use photomosaics to collect information on coral survivorship, coral cover, disease presence, in addition to several other necessary metrics. To add to this, photomosaics not only provide a necessary visual aspect during analysis, but also act as a data repository—with photomosaics, we can go back and look at the data at a moment in time whenever we want!
CRF™ staff swim back and forth along the reef to capture hundreds, even thousands, of images which are stitched together into a singular, interactive, photomosaic. ©Alexander Neufeld/Coral Restoration Foundation™
We monitor our corals at three different time points. The first monitoring session begins at Time Zero—the day that the corals are first attached to the substrate by our divers—then we capture 2 more photomosaics by going back to our restoration sites at One Month after the original outplanting date, and then again at the One Year mark. Spreading out our monitoring days allows us to compile accurate data on the status of our corals over a prolonged period of time!
What Do the Photomosaics Say?
On April 13th, 2021 CRF’s restoration team outplanted a total of 906 corals at Horseshoe Reef. Of that number 504 were elkhorn corals and 402 were staghorn corals. After just one year our data shows a 56% increase in elkhorn coral cover and a 70% increase in staghorn coral cover!
At this point, several of the original coral fragments have fused together, creating even larger colonies! Survivorship for elkhorn and staghorn were 66% and 71% respectively. Those are some amazing numbers, especially when compared to average terrestrial restoration survivorship which hovers around 50%. Seeing this sort of growth is motivating, and this continued sustained growth will eventually help to stabilize the reef ecosystem and jumpstart the reefs' natural recovery processes.
Left: Elkhorn corals the day they are returned to the wild by CRF™ divers. Right: Those same elkhorn corals one year later! ©Alexander Neufeld/Coral Restoration Foundation™
Coral survivorship as an independent metric must be viewed critically as it does not distinguish between when many corals fuse into a single colony; when this happens the survivorship percentage is skewed lower. Imagine 10 coral fragments growing and fusing into 1 coral colony. The survivorship is reported as 10% but in reality that coral grew much larger and there is more living tissue on the reef! This is why we gather both survivorship data AND growth data to give a holistic view of ecosystem health over time.
How does CRF™ Create and Analyze Photomosaics?
Prior to taking a photomosaic, divers will place four scale bars on the reef surrounding a restoration site. These help the photo-stitching software orient the pictures so they can correct for depth at different positions along the site of interest. Then on land, using computer software, each bit of living coral tissue is manually traced in photoshop by one of our CRF™ team members. These tracings are later used to calculate the amount of area within the image taken up by living coral tissue: this metric is referred to as ‘coral cover’, because it is the surface area of the entire reef covered by living coral tissue! Coral cover is recognized as one of the best ways to track growth on the reef!
Above you see three stages of a photomosaic being "traced". Every bit of living coral tissue is manually outlined by our team and a software system analyzes the surface area covered by living tissue! ©Coral Restoration Foundation™
Recall that reefs within the Florida Keys, as compared to many of the reefs around the world, have been suffering for quite some time. Recent success at Horseshoe Reef deserves proper celebration. Seeing such growth reminds us why we do what we do, but we couldn’t do that without you, so thank you!
"Talking Science" Editorial Intern
While Jason grew up in Westchester, NY, he would much rather consider the ocean his home. Jason lead most of his life wanting to be near the sea where he could explore Earth’s oceans and learn about marine life. After graduating from Stony Brook University with a degree in marine sciences, Jason decided to delve into the field of coral reef ecology so as to contribute to global conservation efforts and aid in the preservation of our planet. When he’s not in the water, Jason spends most of his time bouldering, snowboarding, making music, and writing. Beyond anything else, Jason finds purpose in making our planet a better, safer, and more enjoyable place for all of its constituents.
Coral Chronicles Editor
Madalen Howard is CRF's Communications and Outreach Coordinator. Madalen comes to CRF™ via a winding road from the Tennessee hills, to the South Carolina low country, ending here in Florida’s Coral Reef. She earned her Bachelor's degree in Marine Biology and a Minor in Environmental Studies from the College of Charleston in 2016. Her experience ranges from field research to education, marketing and digital communications.
With CRF™ Madalen creates inclusive pathways to scientific discovery through content creation and by building and fostering relationships with press, digital media creators, and local community members. Throughout her life Madalen has had a skill connecting people with nature, and is excited to bring people into the world of coral restoration.