Mark Moline, of the University of Delaware’s College of Earth, Ocean, and Environment, spent his childhood summers on the beach. He went diving at an early age, learning firsthand of the riches below the waves. Like a fish on a line, he was hooked to the water. And the experiences pointed him towards the path of becoming a marine biologist.
For Moline, understanding how the ocean works is an excellent gage for how well the Earth is functioning. With the planet covered in nearly 70 percent water, it’s staggering to think that 95 percent of those blue depths are uncharted mysteries.
Moline and colleagues are seeking new ways to explore the oceans’ biodiversity.
Autonomous underwater vehicles (AUVs) present researchers with unprecedented access to the waters. When AUVs were first introduced, Moline said scientists primarily used their sensors to measure the oceans’ temperature, currents, and salinity. But about 10 or 15 years ago, additional sensors were added and the usage of the platform expanded to include the distribution patterns of marine organisms. It was an alternative to netting, a technique in which scientists lower a line and attempt to understand distribution by the organisms they reel in.
“What you miss just by netting everything is the distinction between how those organisms are distributed in the three dimensional space and how they’re interacting,” Moline told R&D Magazine. “What AUVs allow you to do is unobtrusively sort of go into those areas and systematically map (marine) distribution patterns that you couldn’t do from a ship.”
Co-authoring a paper published in Robotics, Moline and Kelly Benoit-Bird, of Oregon State University, reported on the advantages of using multi-sensor systems aboard an AUV. The systems allowed the AUV to use sound data in real-time to make decisions.
During the experiment, the team used the REMUS600 to understand the distribution of marine organisms in the Tongue of the Ocean, located in the Bahamas. Particularly, they were interested in whether fish, krill, and squid, played a role in attracting whales to the region.
To do this, the team programmed the REMUS’ modules to analyze sonar data at depths between 1,640 and 3,000 ft, according to the Univ. of Delaware. When the right concentration of squid was detected, the REMUS mapped the area in finer detail.
“While this example is one of the simplest possible, it demonstrates the powerful combination of multiple data sources, a platform that can improve time/space sampling, real-time data synthesis, and autonomous decision-making,” Moline and Benoit-Bird wrote in their study’s conclusion.
The Tongue of the Ocean survey was completed in June 2015.
This isn’t the first time researchers have used marine organisms as navigation beacons for AUVs. Usually, though, these marine organisms are tracked with satellite tags. Scientists have used REMUS AUVs and tags to track the movement of great white sharks; Moline and colleagues have also used the technique to follow penguins foraging in Antarctica. That study, led by Megan A. Cimino, used penguins to find areas teeming with potential prey sources, such as krill.
Moline’s interest in the Tongue of the Ocean is partly inspired by the fact the U.S. Navy uses the area for sonar tests. “For some reason whales like to be in those areas where ranges have already been set up,” said Moline.
Preliminarily, it appears the ample amount of prey sources may attract whales to the region. But more research is required.
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