From the sea – Scientists monitor coral reef growth and change using photogrammetry Structure-from-Motion (SfM). This new method is able to reconstruct the seabed and coral communities.
The researchers used SfM (structure-of-motion) photogrammetry to measure coral colony growth and other changes in Pacific Island reefs.
Resilience is the ability of corals to resist and recover from stressful events. Measuring reef resilience allows us to predict reactions to environmental stressors.
Scientist NOAA Fisheries using photogrammetry to measure it at the colony and population scale.
The team measured reef resilience by monitoring growth, mortality, and the incidence of coral colonies breaking or coalescing. This is the vital level of the coral colony.
NOAA Fisheries Very happy to announce that we have successfully demonstrated new method to measure the vital level of corals using photogrammetry Structure-from-Motion (SfM).
This image processing technique is able to reconstruct the seabed and the coral communities that inhabit it.
Pacific Island Fisheries Science Center (Pacific Islands Fisheries Science Center) has been monitoring Pacific coral populations and benthic communities since the early 2000s under the National Coral Reef Monitoring Program (National Coral Reef Monitoring Program).
Previously, the team had used various survey methods to measure coral cover and density.
The team randomized the survey spatially. This means not visiting the same coral colony more than once. These scientists use this method to track coral populations, but not individual colonies.
Tracking coral vital levels with this traditional method is very time consuming. Because coral reefs can respond differently to the same stress. The team needed a method that could cover a large area of reef.
The Scale of Everything
3D and 2D structure-of-motion products show clear images of large areas at millimeter-scale resolution.
Unlike previous attempts to track vital levels, SfM can track thousands of colonies at tens to hundreds of sites.
This will provide the ecological and spatial replication needed to build statistical models of vital levels and environmental patterns.
This program is the result of collaboration with other researchers to achieve this scale and expansion, such as Dr Stuart Sandin of Scripps Institution of Oceanography, Dr. John Burns of the University of Hawaii at Hilo and Dr. Joshua Madin of the University of Hawaii’s Hawaii Institute of Marine Biology.
Testing Method
A group of students at California State University in Monterey Bay, led by Knauss Fellow Caroline Rodriguez, helped track thousands of colonies across the Hawaiian Islands, from 2013 to 2019.
SfM presents impressive potential for tracking colony-scale changes, but like any new tool, we must document errors accurately.
A recent report details this approach for capturing, processing and extracting data from SfM photogrammetry. In it, shows a low error rate with imaging and annotation methodologies.
SfM photogrammetry provides a robust, efficient and scalable method for extracting coral vital level data.
For example, we can perform a sensitivity analysis to determine which species or populations of corals are most vulnerable to stressors and should be targeted for management interventions.
Scientists are excited to integrate this new technology with their current methods to support important decisions that guide coral reef conservation, ecosystem management, restoration, and rebuilding efforts.
Coral reefs are not only beautiful ecosystems. Coral reefs provide economic, cultural and biological resources, and food for hundreds of millions of people worldwide.
Pollution, overfishing, ocean acidification and change climate continue to threaten the ecosystem Coral reefs.
As these reefs become more intense and frequent, it is important that we learn more about how coral reefs react.
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