You can see the light blue halos where seaweed has been grazed around the coral patches in the Red Sea. Image downloaded from Google Earth Pro 7 June 2011. Image date 19 Dec. 2010. Image copyright 2011 GeoEye.
The image you see above was taken with the GeoEye satellite and reveals marine animal behavior that would otherwise be difficult for scientists to witness. But in a paper published by Scientific Reports, researchers were able to witness how marine animals and their predators interact by studying the feeding patterns of herbivores. Monga Bay reports, "Studying the satellite imagery of lagoons around remote and protected Heron Island in the Great Barrier Reef, researchers found that they could easily identify a phenomenon known as 'grazing halos'. Scientists believe these 'grazing halos' are created by hungry herbivorous fish and sea urchins who pick a region clean of seaweed, revealing the substrate beneath. Seeking protection from predators in a reef, these herbivores venture out to feed only so far, creating a halo-shape around their refuge. Therefore, these areas are the result of a complex game of cat-and-mouse between marine predators and their cautious prey."
Scientists have shown us that a healthy coral reef has a vast number of predators. In fact, while we usually expect the population of predators in an ecosystem to be far outnumbered by the population of prey animals, in coral reefs this is the opposite. Researchers have found that healthy coral reefs are an "inverted pyramid" where predators compete for what few prey animals exist. This is incredibly important for the health of the coral reefs because as we can see from the satellite images, it keeps the herbivores from eating everything in sight. An image such as the one above helps highlight the link between a large shark population and the health of coral reefs, and illustrates why bans on shark fishing are so important.
"Freely-available satellite imagery of the entire Earth's surface via Google Earth allows examination of landscape features in even the most remote areas, including difficult-to-access habitats within them," the paper's authors write, adding that, "here we demonstrate [...] it is possible to remotely observe the landscape-scale footprint of behavioral interactions between predators and prey on shallow coral reefs...The collective antipredator behavioral patterns of small herbivores are sufficient to shape the distribution of vegetation on a scale clearly visible from space."
What is even more interesting than the fact that this behavior can be witnessed even from space, is the concept that just such use of satellite imagery can be used elsewhere in the world to monitor the behavior between predator and prey and the impact it has on healthy ecosystems such as forests. Such use of remote monitoring can help parks officials monitor healthy levels of predator and prey animals, and watch for any upsets in the ecosystem balance.
Yet another wonderful use found for Google Earth!
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