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This project is a collaboration between myself and National Oceanic and Atmospheric Association's (NOAA) Pacific Islands Fisheries Science Center (PIFSC).
This research requires the use of some cutting edge tools, specifically structure from motion, which is increasingly being used to monitor coral reefs. In short, I am trying to determine whether 3D models of the reef can be used to quantify coral predation, or corallivory. Let's take a couple of steps back though. Structure-from-Motion (SfM) is a photogrammetry technique for estimating or reconstructing three-dimensional structures from two-dimensional image sequences. The process of building these three-dimensional models begins in the water, where I take over a thousand overlapping images of the reef section I am surveying. I then upload those images into a software called Agisoft which stitches them all together. The end result is a 3D model of the reef. Lastly, these models are reviewed and coral bite marks are counted. Back in the water, after I've collected the images for the model, I conduct surveys to count coral predation. Ultimately, I will compare the number of coral bite marks we saw in the water with those we counted in the models to determine whether these models are reliable for quantifying coral predation. |
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After I've collected images for the three-dimensional models, I conduct in water surveys
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Corallivores are important predators on coral reefs. They come in a variety of forms - from mollusks and crustaceans to echinoids and fishes. They can consume the mucus, coral polyps and/or skeleton of coral. Corallivory is an important determinant of reef health, and therefore important to monitor. Coral predators can cause mass mortality of coral on reefs. For example, the crown-of-thorns sea star was the leading source of coral mortality on the Great Barrier Reef before bleaching events. Moreover, because corals have limited metabolic resources, removing tissue and/or skeleton can reduce growth and sexual
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reproduction as resources are redirected to wound healing. Corallivores have also been known to target coral polyps that are loaded with eggs and can even be disease vectors!
Because corallivory can be a substantial stressor to corals, it is imperative that are able to quickly monitor reefs for excess predation. In doing so, we will be better able to enact rapid and targeted management interventions such as coral restoration initiatives and corallivore removals. The aim of this project is to provide such a tool which will allow reef managers to monitor large areas of the reef in a more rapid and inexpensive way.
Because corallivory can be a substantial stressor to corals, it is imperative that are able to quickly monitor reefs for excess predation. In doing so, we will be better able to enact rapid and targeted management interventions such as coral restoration initiatives and corallivore removals. The aim of this project is to provide such a tool which will allow reef managers to monitor large areas of the reef in a more rapid and inexpensive way.