The world’s seabeds remain largely unexplored, with current knowledge being inconsistent. Utilizing remotely operated underwater vehicles (ROVs) to study seabeds can be costly, dependent on weather conditions, and challenging in deep, remote areas.To address these obstacles, Australian researchers have turned to endangered Australian sea lions (Neophoca cinerea) to carry cameras. The videos recorded by these sea lion crews enabled the identification of previously unmapped benthic habitats on the continental shelf. The findings have been published in *Frontiers in Marine Science*.

“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,” said first author Nathan Angelakis, a PhD student at The University of Adelaide and the South Australian Research and Development Institute (Aquatic Sciences). “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.”

Tracking Sea Lions
The project, funded by The Australian Government and The Ecological Society of Australia, involved equipping eight adult female Australian sea lions from Olive Island and Seal Bay colonies with small, lightweight cameras. These cameras and tracking devices were attached to small neoprene patches, which were then glued to the sea lions’ fur. The total weight of the equipment was less than 1% of the sea lions’ body weight, ensuring no impact on their movement. Recordings were made over two to three days.

“We deployed the instruments on adult females so we could recover the equipment a few days later when they returned to land to nurse their pups,” Angelakis explained. “We used satellite-linked GPS loggers on the sea lions, which meant we could track their position in real-time and knew when they had returned to the colony.”

Predicting Ocean Habitats
From the animal-borne videos – totaling 89 hours of recordings – the researchers identified six benthic habitats: macroalgae reef, macroalgae meadow, bare sand, sponge/sand, invertebrate reefs, and invertebrate boulder.

The team then used machine learning models to predict large habitat areas across the continental shelf of southern Australia. This analysis also included oceanographic and environmental factors critical to the structure and distribution of these habitats, based on 21 years of observation and measurements.

“The sea lions from both locations covered quite broad areas around the colonies. In our calculations, we kept the area in which we predicted habitats small to maximize the precision of our predictions,” Angelakis said. “This allowed us to model benthic habitats across more than 5,000 square km of the continental shelf.”

As Seen by Sea Lions
The habitats captured by the sea lions were different from previously mapped regions in South Australia. This variation could be due to different oceanographic and environmental conditions, the sea lions’ habitat preferences, or the possibility that certain habitats were not covered by the sea lions.

Despite these factors, the study provides valuable information about these seabeds and offers critical insights into an endangered species whose populations have decreased by over 60% in the past 40 years. Additionally, the data can be used to survey and assess other marine species observed in the videos.

The researchers highlighted that utilizing animal-borne video presents an efficient and cost-effective method for future seabed mapping projects. Studying marine areas from a predator’s perspective rather than a human-centric viewpoint can enhance the understanding of benthic environments and contribute to more comprehensive seabed maps.