[Coral-List] New paper describing method for quantifying coral bleaching loss at high spatial scale and resolution

[Kai Kopecky]

Hi everyone,

Please check out our new paper, published this week in Remote Sensing,
where we describe a new method for quantifying the three-dimensional loss
of live coral from a bleaching event using underwater photogrammetry and
AI-assisted image processing. Our method enables capturing high
resolution (sub-centimeter) changes in live and dead coral over large
spatial scales (> 25m^2), and with high efficiency. Abstract and link to
paper below:

https://doi.org/10.3390/rs15164077

*Abstract*:
Detecting the impacts of natural and anthropogenic disturbances that cause
declines in organisms or changes in community composition has long been a
focus of ecology. However, a tradeoff often exists between the spatial
extent over which relevant data can be collected, and the resolution of
those data. Recent advances in underwater photogrammetry, as well as
computer vision and machine learning tools that employ artificial
intelligence (AI), offer potential solutions with which to resolve this
tradeoff. Here, we coupled a rigorous photogrammetric survey method with
novel AI-assisted image segmentation software in order to quantify the
impact of a coral bleaching event on a tropical reef, both at an
ecologically meaningful spatial scale and with high spatial resolution. In
addition to outlining our workflow, we highlight three key results: (1)
dramatic changes in the three-dimensional surface areas of live and dead
coral, as well as the ratio of live to dead colonies before and after
bleaching; (2) a size-dependent pattern of mortality in bleached corals,
where the largest corals were disproportionately affected, and (3) a
significantly greater decline in the surface area of live coral, as
revealed by our approximation of the 3D shape compared to the more standard
planar area (2D) approach. The technique of photogrammetry allows us to
turn 2D images into approximate 3D models in a flexible and efficient way.
Increasing the resolution, accuracy, spatial extent, and efficiency with
which we can quantify effects of disturbances will improve our ability to
understand the ecological consequences that cascade from small to large
scales, as well as allow more informed decisions to be made regarding the
mitigation of undesired impacts.


Feel free to reach out with questions if you have any!

Kai


-- 
-Kai Kopecky