Plankton are tiny aquatic creatures which form the basis of many of the food webs found in the world’s oceans. Each smaller than a grain of rice, they band together in huge swarms that sometimes manifest on the surface as “red tides.” But for the most part, they actually live under the ocean’s surface, where they are affected by internal waves, which are slow moving waves underwater.
At least, that was the hypothesis. Two decades ago, Peter Franks, an oceanographer at the Scripps Institution of Oceanography, wrote that plankton swarms most likely bunched up in the warm waters of the internal wave troughs, but dispersed over the slightly colder wave crests. Until recently, however, there was no way to verify this, until Jules Jaffe, also working at Scripps, developed grapefruit-sized robots meant to mimic plankton movements. Called miniature autonomous underwater explorers, or M-AUEs, the robots were used to prove Franks’ arguments correct.
For the initial test, 16 M-AUEs were deployed in a 300-meter diameter swarm (almost 1,000 feet) and programmed to maintain buoyancy at 10 meters deep (about 33 feet), while they sent back 3-D location information every 12 seconds.
The M-AUEs have a lot of other potential uses as well. While floating about in swarms and mimicking plankton movement, they can teach us a lot about plankton, but they can also be equipped with devices to further our understanding of other ocean life as well. With cameras, they can take pictures of coral reefs and other underwater habitats, while other sensors can be used to record more information about how internal waves and other ocean mechanisms work. The microphones already built into the M-AUEs, used to track their movements at sea, could be used to record ambient ocean sounds as well.
Researchers also believe the M-AUEs could have other functions such as tracking oil spills, as they recalled the difficulties rescuers and environmentalists had in locating the oil leaked in the 2010 Deepwater Horizon oil spill.
All in all, these little robots could help researchers to learn a lot more about the ocean—which can help us preserve the fragile ecosystems within it.