Many of us have likely watched a nature documentary and wondered how cinematographers got the perfect shot of a cheetah hunting its prey, or a school of fish navigating the deep blue.
But in a recent study, published by Australian researchers in Frontiers in Marine Science, there’s no wondering who was behind the camera this time. In fact, the whole study focuses on one camera crew in particular: Sea lions.
These endangered mammals didn’t have a goal of seamless filmmaking but were employed by researchers to collect video data about habitats and ecosystems in the waters of southern Australia.
“Using animal-borne video and movement data from a benthic predator is a really effective way of mapping diverse benthic habitats across large areas of the seabed,” the study’s first author, Nathan Angelakis, said in a statement.
“These data are useful both for mapping critical habitats for an endangered species such as the Australian sea lion, and more broadly, for mapping unexplored areas of the seabed.”
With the help of the sea lions, researchers identified six benthic — or underwater — habitats covering 5,000 square kilometers.
The idea to utilize the sea lions came from the fact that these seabeds are under-explored (Only about a quarter of the seabed has been mapped at high resolution worldwide) and using remote underwater vehicles can get extremely costly.
Plus, the sea lions seemed unfazed by the job of wearing cameras while roaming their natural habitats.
For this study, the researchers — who hail from the University of Adelaide and the South Australian Research and Development Institute — attached tiny, lightweight cameras to eight adult female sea lions.
The equipment was attached to neoprene patches that were glued to the backs of the sea lions and included GPS trackers, cameras, and motion sensors.
These pieces were designed to weigh less than 1% of the sea lions’ body weight, so they weren’t encumbered by their video equipment.
They then went on to capture nearly 90 hours of footage, which, most excitingly, included areas of the water that have never been mapped before.
“These are particularly deep and remote offshore habitats that you can’t get to by usual surveys that you would conduct from a boat,” Angelakis told Nature. “With the data we’re collecting, we’re essentially exploring new parts of the ocean that haven’t been mapped.”
After completing the project, the equipment was removed from their backs without damaging any of the sea lions’ fur, with the patches to easily fall off upon their next molting season. Additionally, this process was approved by the university’s Animal Ethics Committee, as well as government bodies responsible for animal welfare and the environment, according to the study.
Another interesting element of this work is that it puts the animals at the heart of the study in control of its findings, providing metrics that are clearly relevant to their survival, rather than human-subjective ideas.
“Traditionally, assessing the quality of different habitats and marine environments is done from an anthropocentric perspective,” Angelakis told Science.org in an interview.
“Whereas here, we’re using the sea lions as the tool to assess the marine environment, and they provide us information on the areas that are important to them. I think that’s an important shift and something that can be incorporated with more traditional data.”
This is especially important, as the Australian sea lion population dwindles. Hunted in the early 20th century and threatened by fishing nets, populations have declined by 60% in the past 40 years, with about 10,000 sea lions left across 80 breeding sites along Australian coastlines.
But this new insight into their homes shows researchers what they encounter every day.
“Information has been so elsive, because they are feeding at the bottom of the sea,” Professor Simon Goldsworthy of SARDI told The Guardian. “Now we get this amazing, exquisite detail. They’re giving us a window into their world that we haven’t had before.”
The researchers used the footage to assess biodiversity in the area and to help train a machine-learning model that aims to predict and map seafloor habitats, using variables like sea-surface temperature and distance from the coast.
They also hope to use the data to better understand habitat distribution and biodiversity in these areas, which will illustrate the value of various factors in a habitat and could contribute to the conservation efforts protecting sea lions.
While the future of these studies — and sea lions themselves — remains uncertain, knowing even a little bit more about the ins and outs of the species is significant to their survival — and to science at large.
“Just like humans know our streets, the sea lions know the seabed in intimate detail for hundreds of kilometers and they build up this knowledge over time,” Goldsworthy told the Guardian.
“They have a mental map of their environment and they are leading you to places of profound significance for them.”
Header images courtesy of Nathan Angelakis, et al
