Australian sea lion by John Turnbull via From Mongabay by Shreya Dasgupta
For the first time ever, scientists have
had help from sea lions in mapping the ocean floor.
And the marine mammals have done their job well, capturing six different marine habitats, including algal meadows and reefs, that make up South Australia’s seabed, researchers report in a recently published study.
And the marine mammals have done their job well, capturing six different marine habitats, including algal meadows and reefs, that make up South Australia’s seabed, researchers report in a recently published study.
For much of the planet’s ocean, what the seafloor looks like is still a mystery.
Conventional surveys using specialized underwater equipment and vessels
require large crews as well as good weather, which makes mapping wide
areas challenging and expensive, Nathan Angelakis, lead author of the
study and a doctoral student at the University of Adelaide, Australia,
told Mongabay in an email.
As an alternative, the researchers fit small, lightweight video
cameras and movement trackers on eight adult female Australian sea lions
(Neophoca cinerea).
The team had two goals: to understand the
habitats and food that are critical for the endangered species, and to
map the little-known seafloor off southern Australia’s coast.
Sea lion swimming through invertebrate
reef, sponge garden, macroalgae reef, bare sand, and invertebrate
boulder habitats.
Video: Angelakis et al. 2024.
Video: Angelakis et al. 2024.
The sea lion videographers ended up capturing more than 89 hours of
data and footage, recording around 560 kilometers (350 miles) of the
continental shelf, at depths of 5-110 meters (16-360 feet).
On reviewing
this data, the scientists saw that the sea lions eat a wide variety of
fish, small sharks, stingrays and octopuses, either by flipping rocks
over, digging up sand, or ambushing schools of fish.
“We were also lucky enough to capture footage of a mother taking her pup on a trip to sea, providing the first direct evidence we have that Australian sea lion mothers pass on their foraging skills to pups,” Angelakis said.
“We were also lucky enough to capture footage of a mother taking her pup on a trip to sea, providing the first direct evidence we have that Australian sea lion mothers pass on their foraging skills to pups,” Angelakis said.
The team also identified six kinds of seabed habitats from the
videos.
They combined this habitat data at different locations, with long-term oceanographic and environmental data for those locations, to then predict habitats for areas that the sea lions didn’t visit.
“This allowed us to map and predict habitats on the seabed for more than 5,000 square km [1,930 square miles] of previously unexplored seabed across the continental shelf in southern Australia,” Angelakis said.
They combined this habitat data at different locations, with long-term oceanographic and environmental data for those locations, to then predict habitats for areas that the sea lions didn’t visit.
“This allowed us to map and predict habitats on the seabed for more than 5,000 square km [1,930 square miles] of previously unexplored seabed across the continental shelf in southern Australia,” Angelakis said.
Katie Dunkley, a marine researcher at the University of Cambridge, U.K., who wasn’t involved in the study, told The Washington Post
that while the number of sea lions used in the study was small, the
study was a “proof of concept” showing that sea lions can help us map
the ocean floor.
Angelakis added that such baseline knowledge of seabed habitats and
the conditions that influence their distribution is crucial “for
understanding how they may be impacted by human activity.”
Furthermore,
the study improves our understanding of the marine habitats that are
crucial for the rapidly declining Australian sea lions, he said.
“This information is fundamental for better conserving and managing their populations in the future,” Angelakis added.
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