By Matthew Stock
A submarine glider and an autonomous surface vehicle are being used by the National Oceanography Center (NOC) to work together to better understand why marine animals are attracted to a biodiversity hotspot in the Celtic Sea. Working in partnership with the World Wildlife Fund (WWF), the research team hopes the data the robotic duo gathers will help inform future conservation initiatives of marine environments and gain a better understanding of the marine ecosystem.
"Biodiversity hotspots are areas in the ocean that are usually particularly productive. Productive areas attract zooplankton, and that in turn attracts fish. Areas of enhanced or elevated biomass of fish often attract marine mammals and seabirds in turn," marine biologist Lavinia Suberg told Reuters.
Based in Southampton in England, the NOC mission is focusing its attentions on the Celtic Deep area of the Celtic Sea, off the south-west coast of Wales. It contains known hotspots for marine animals, including the Fin Whale and the threatened Balearic Shearwater seabird.
"We're interested in finding links between the different characteristics that we are studying. So we're interested in how, for example, weather events directly affect the water column and in turn does that effect productivity and then again in fish and further up the food chain, cetaceans or seabirds," added Suberg.
The submarine glider was recently deployed from the Royal Research Ship Discovery into the Celtic Sea. The craft oscillates through the water column at a very slow speed, providing tywo-dimensional (2D) profiles from the sea surface to near the seabed. To collect the vast array of data needed to generate a comprehensive picture of the marine environment, glider engineer Stephen Woodward said it's jam-packed full of sophisticated sensing equipment.
"The sensors that we use are things like oxygen optodes, we measure conductivity, temperature, salinity. We have echo-sounders to detect zooplankton and fish, acoustic Doppler current profilers for measuring the currents in the water, wet-lab fluorometers for measuring chlorophyll and organic matter, and a few other specialist sensors as well," Woodward said.
Despite the glider's torpedo-like shape, Woodward said it actually travels very slowly in order to accurately gather data and extend the life of its batteries.
"They kind of look like torpedoes, they look like they'd be very fast and sleek in the water. But they're really not. They're really very slow moving and energy efficient, so that's how they can stay out for so long," Woodward said, adding that the lithium batteries onboard a glider could run for up to six months.
The data the glider collects on its expedition will be used in conjunction with the information gathered by an autonomous catamaran called C-Enduro. The robotic vehicle has solar panels and a wind turbine, meaning it could potentially remain offshore for several months.
"In this particular project, the novelty is that we are combining surface and underwater vehicles. The surface vehicles move above the surface just like a boat and collects data mainly on atmospheric variables and anything that's happening on the water surface. Whereas the underwater glider oscillates with the water column and gives us information on the physical characteristics of the water," said Suberg.
The combined dataset from the two robotic crafts will provide vital information about biodiversity hotspots in the sea. It is information that the WWF hopes will give a clearer picture of the region and inform future management and protection. This, they say, is important for ensuring strong marine economies and thriving coastal communities that depend on the resources and business opportunities the seas provide.
For scientists such as Suberg, the project will give a rare opportunity to use cutting-edge robotics to acquire a vast and detailed amount of information.
"I'm particularly excited about the science side of things. If all the sensors and the EV [electric vehicles] kits work; we are getting an amazing dataset, collecting data over various levels of the food-chain simultaneously. And that's rare and that's great, and it provides us with a lot of useful information," she said.