Sea lion cameras help scientists map unexplored oceans

Scientists have a new friend who helps them explore the depths of the ocean – sea lions. An Australian group recruited endangered Australian sea lions (Neophoca cinerea) to take video cameras down this small stretch of beach. The videos helped the team identify some previously unmapped areas of sea lions in the benthic zone—or the lowest part of the aquatic environment. The pinniped-assisted research is described in a study published on August 7 in the journal Frontiers in Marine Science.

[Related: How animals see the world, according to a new camera system.]

Deep diving

Our knowledge of the depth of the sand and rocks of the sea is very limited. Diving with remotely operated underwater vehicles (ROVs) such as Alvin or Jason Jr. from the Woods Hole Oceanographic Institution can be expensive and prohibitive. Cars are expensive and require certain weather conditions to dive. It is also difficult for people to reach the deep and remote areas of the oceans even with high-tech submersibles.

“Using animal-borne videos and movement data from predators is a really effective way to map the different areas of large oceans,” said Nathan Angelakis, co-author and as a PhD student at the University of Adelaide and South. Australian Research and Development Agency, said in a statement. “This data is useful for mapping critical habitats for endangered species such as the Australian sea lion, and more broadly, for mapping vulnerable areas. at the bottom of the sea.”

In the study, eight Australian female lions from the Olive Island and Seal Bay colonies were fitted with small and lightweight cameras. The team attached cameras and tracking devices to small pieces of neoprene—the stuff most wetsuits are made of—that were attached to the fur of the sea lions. Overall, the weight of the filming and tracking equipment was less than 1 percent of the sea lion’s body weight. This prevented further drag and allowed them to move freely. The sea lions recorded in two to three days.

“We applied the equipment to the older females so that we could find the equipment a few days later when they returned to the ground to nurse their young,” Angelakis said. “We used satellite GPS loggers on the sea lions, which means we can know where they are in real time and when they have returned to the colony.”

How to predict habitat

In total, the team collected 89 hours of animal-driven video. The researchers identified six benthic habitats: macroalgae reef, macroalgae meadow, bare sand, sponge/sand, invertebrate rocks and invertebrate rocks.

Back on dry land, the team used machine learning techniques to predict major habitats across the continental shelf south of Australia. They did this by incorporating 21 years of marine and environmental data into the models. These factors may influence the shape and distribution of these habitats.

[Related: Scientists strapped tiny cameras to beetles to get a bug’s-eye view of the world.]

“Sea lions from both areas covered very wide areas around the colonies. In our calculations, we kept our predicted habitable zone small to make our predictions more accurate,” said Angelakis. “This allowed us to model residential areas of more than 5,000 sq km [1,930 square miles] of the continental shelf.”

The sight of a sea lion

The Sea Lion cameras also filmed some of the more diverse locations in South Australia that had been mapped. Pinnipeds may not use or swim in certain areas or prefer some areas over others. The researchers also point out that some sites may be wrong.

However, the images still fill some knowledge gaps about the coast, while providing valuable information about endangered marine species. The population of the sea has decreased by more than 60 percent in the last 40 years. This method can also be used to monitor and evaluate other interesting marine life that the sea lions caught on camera.

According to the team, examining the ocean environment from a predator’s perspective rather than a human’s can improve our understanding of benthic ecosystems and create a more complete map of the ocean floor.