Scientists using sea lions with cameras to explore unknown ocean areas

By Stephen Beech via SWNS

Sea lions have been fitted with special video cameras to allow scientists to explore previously inaccessible ocean habitats.

Video data collected by the endangered marine mammals was used to identify previously unmapped areas beneath the sea off southern Australia.

The world’s seabeds remain relatively unexplored, and using remotely operated underwater vehicles to learn about them is expensive and requires certain weather conditions.

To get around the problems, researchers enlisted endangered Australian sea lions to carry cameras.

The resulting videos allowed the team to identify previously unmapped underwater habitats used by the sea lions on the continental shelf.

Study first author Nathan Angelakis said: “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.

“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.”

Eight adult female Australian sea lions from Olive Island and Seal Bay colonies were equipped with small and light-weight cameras for the project.

Cameras and tracking instruments were glued to small pieces of neoprene that were then glued to their fur.

In total, the filming and tracking equipment weighed less than one per cent of the sea lions’ bodyweight to prevent dragging effects and allow the mammals to move without restrictions.

Angelakis, a PhD student with The University of Adelaide and the South Australian Research and Development Institute, explained that the recordings were made over two to three days.

He said: “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.

“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.”

From the 89 hours of animal-borne video recordings, the researchers identified six benthic habitats: macroalgae reef, macroalgae meadow, bare sand, sponge or 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.

To do so, they also incorporated oceanographic and environmental factors which may be important drivers of the structure and distribution of the habitats.

The oceanographic data that was incorporated into the models was based on 21 years of observation and measurements.

Angelakis said: “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.

“This allowed us to model benthic habitats across more than 5,000 square kilometers of the continental shelf.”

He added that the habitats the sea lions filmed were different than in other, previously mapped regions of South Australia.

The research team believe that could be due to contrasting environmental conditions, as well as sea lions not using or traveling through certain habitats or preferring certain ones over others, while other habitats may have been missed.

Angelakis says the study, published in the journal Frontiers in Marine Science , contributes to knowledge about and provides "critical" information about an endangered species, the populations of which have declined by more than 60% over the past 40 years.

He believes that exploring underwater habitats by way of animal-borne video offers an efficient and cost-effective method for future mapping projects.

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