"Talking Science" in April 2021 with the Coral Chronicles

Photomosaics 101

Setting Up

“One of the cool things about the Science Program Internship is learning how to take photomosaics. But there are a lot of intricate details to keep track of to make sure the final photomosaic is as clear as possible.” - Charis Peterson, Science Program Intern

When taking a photomosaic, we first need to set up the apparatus. We refer to the whole instrument informally as the photomosaic “hammerhead” as it has a wide frame with two cameras or ‘eyes’ on the ends much like a hammerhead shark’s face. To assemble it we attach two GoPro cameras to a custom PVC frame.

Before getting into the water, we ensure that the cameras are in the correct mode: a time lapse taking one picture every second. Then we assess the water conditions and depth to determine which light filter to use to reduce the amount of color correction needed in post processing.


Attention to detail is crucial to make post processing smooth. A single bubble on the camera lens can ruin the entire photomosaic! Finally, we hop into the water and the hammerhead is handed to us by a crew mate!

The Swim

Photomosaics reduce the amount of time spent in water to capture raw monitoring data, but accurately swimming a photomosaic is no easy task! Before taking any data, we swim the perimeter of the area we are monitoring and orient ourselves to the reef.


Swimming on a reef can be very disorienting, even a familiar one looks different based on water clarity. Our divers use distinctive landmarks to find their way like coral heads, sand channels, reef peaks and valleys and of course our handy dandy scale bars to help us stay oriented.


As each reef varies in its topography and habitat type, we are constantly thinking about where to position ourselves in the water column. It can be difficult to stay on the proper path especially if the current or surge is strong, but the more practice our team gets the more accurate we become!

Science Program Intern Charis Peterson captures a photomosaic as part of her internship training. ©Amelia Moura/Coral Restoration Foundation™


To capture a full mosaic, we swim back and forth across the monitoring zone, in the same pattern you would make if you were mowing a lawn. The cameras take a picture every second, and as we swim, we make sure to overlap our passes slightly. This overlap between photos in each “pass” accounts for some human error like veering too far left or right. It also allows the software to stitch the images together when we are back on land.

“It takes a lot of leg power to swim over the mosaic areas. Some areas are 1,500 square meters and it can take half an hour to collect the photomosaic. That is still much less time than monitoring random individual colonies with pencil and paper though!” - Charis Peterson

Just like all scientific field work, photomosaic monitoring has its challenges, but the results are accurate and even beautiful!

Monitoring Corals To Maximize Reef Health

Once corals are returned to the reef our work has just begun! We continue to monitor our transplanted corals' and overall ecosystem health over time. We look at as many details as we can to get an accurate understanding of how the reefs are faring.


Join us as we dive deeper into each parameter we measure throughout this series! We've covered algal competition and snail predation, now its time to understand fusion!


Fusion

Corals are colonial animals. Each polyp is linked to another by connective tissue through which the coral can share resources! It is this entire connected structure which forms the full animal we see when swimming over the reef. Coral polyps of the same genotype will fuse together when they meet, resulting in fields of beautiful corals!

CRF™ Science Program Manager Amelia Moura monitors for coral fusion within multiple clusters of staghorn coral. ©Alexander Neufeld/Coral Restoration Foundation™


When we secure our coral fragments to the reef, they are placed in clusters of the same genotype about a foot apart. Over time the coral polyps grow over the epoxy used to adhere them to the reef and attach to the natural limestone. This process is called skirting. It takes less than a month for the corals to grow their own strong anchors in this manner!


The corals continue to grow upward and outward towards the rest of the fragments in their cluster. The joining of two or more coral fragments into one is called fusion. Fun fact: a cluster of staghorn coral is called a thicket and a cluster of eklhorn coral is a stand!

Elkhorn coral fragments before and after fusion. ©Coral Restoration Foundation™


While monitoring our restoration sites, our team looks for fusion. This is an incredibly important part of the monitoring process because as 10 coral fragments fuse into 1 single coral colony the number of corals on the reef will decrease but the total area of coral cover on the reef increases! Our photomosaic technology allows us to gather this more accurate metric as corals fuse over time.

"Talking Science" Editorial Intern

Charis grew up in Michigan where her curiosity for the underwater world started in the local rivers and lakes. She always had a passion for marine biology. While she was in high school, her family unexpectedly had to relocate to coastal Georgia. Moving across the country allowed her to pursue her passion. After learning about the threats and harm humans have caused to coral reefs, she decided she did not want to just study coral reefs, but she wanted to be a part of the solution.

Charis is a recent graduate from the University of Houston-Clear Lake with a M.S. in Biotechnology and a concentration in Molecular Biotechnology. She received her B.S. in Biology with a concentration in Coastal Ecology from the College of Coastal Georgia in 2017. She is a PADI Open Water Scuba Instructor and has enjoyed working as a dive professional in the British Virgin Islands and the Florida Keys. Charis is excited to intern with CRF™ because she is passionate about educating the public on how to protect our oceans.


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