Notes from the field: Kathryn Furby on Photomegatron
Posted by marlenebrito on Aug 14, 2012 in Featured • No commentsPHOTOMEGATRON: Transforming Coral Reef Science
Written by: Expedition member Kathryn Furby, 6/21/2012
Via: The New England Aquariums Phoenix Islands Blog
Meet PHOTOMEGATRON (imagine James Earl Jones in his low voice saying the word photomegatron). A tandem camera setup, it takes photos (one per second) while I swim it above the reef.
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| Kathryn Furby swims the PHOTOMEGATRON above a coral reef in the Phoenix Islands. (Photo: K. Ellenbogen) |
How do you build your own Transformer to map reefs for you? Take two Nikon SLR’s, mount them in a protective frame and add lasers. The lasers are used to calibrate the scale of the photos, although I use them to look fierce (incidentally, watching damselfish chase the lasers is my new favorite game).
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| Example of an image taken by the PHOTOMEGATRON |
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| Example of an image taken by the PHOTOMEGATRON |
After thousands of photos are taken over a large area, we send them to our colleagues, Art Gleason and others at the University of Miami. They use an algorithm that compiles the overlapping photos into a large “mosaic” of the reef. The finished product is an approximately 60 – 100 square meter map of a coral reef, with a 5mm resolution.
Ecology is largely an observational science. One that is constantly evolving. Previous to the mosaic method, we would mark a specific location on the coral reef and photograph it. Each photo covered no more than one square meter per quadrat. With this we could revisit the sites again and again, take the same photo at the same marked location, and thus track corals’ changes in health or size over time. However, a disadvantage to this is that you miss out on massive corals. One square meter doesn’t cover too many small corals, and it completely excludes the big ones. Large boulder corals or giant branching plate corals are the charismatic mega-fauna of the benthic environment. The adorable manatees of the invertebrate world. These corals live for hundreds of years, and until now we haven’t had a good way to study them. We’ve personally tagged individuals, but this is time-consuming. It can be difficult to cover a representative sample.
Now with PHOTOMEGATRON (enter James Earl Jones again) we can digitally tag the corals. We photograph a large swath of reef, return to marked sites year after year. This way we can track the fates of corals, large and small. The Sandin Lab at Scripps Institution of Oceanography is using this method here at the Phoenix Islands this month, Palmyra Atoll at the end of the summer, and after that … who knows. PHOTOMEGATRON is locked and loaded, ready to map and monitor the reefs of the world!
-Kathryn