These sea lions are on the move in the service of science.
Photo: Nathan Angelakis
Sea lions hiding in the sea grass, cavorting among fish, dolphins and sharks or a sea lion teaching her cub to hunt: the 90 hours of material that eight sea lions filmed in Australia are, as one of the researchers involved in local media said, “the best slow TV ever.”
But the marine mammals are not intended to entertain the scientists, but rather to help them map the previously largely unexplored seabed around Kangaroo and Olive Island south of the Australian mainland.
“The world’s seabeds have been little explored and our knowledge is patchy,” said researchers from the University of Adelaide in a statement Accompanying text to yours in the specialist magazine »Frontiers in Marine Science« published study. The US weather agency also confirms the latter NOAAwhich said that as of June this year, only 26.1 percent of the global seafloor had been mapped using modern high-resolution technology.
Only 26.1 percent of the global seafloor has been mapped in high resolution.
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The footage collected by the Australian sea lions (Neophoca cinerea) helped scientists map 5,000 square kilometers of seafloor. In addition to researching the seabed, the researchers also wanted to gain a better understanding of how sea lions use different habitats and how people can better protect these ecosystems. Australian sea lions are an endangered species whose numbers have declined by more than 60 percent in the last 40 years.
The images revealed rocky reefs and seagrass meadows and showed which habitat the sea lions prefer. The images also revealed that some animals prefer eating fish, while others have a more specific preference, for example, searching for smaller sharks, stingrays or squid, as Nathan Angelakis, a graduate student at the University of Adelaide who led the study, said in an email. wrote an email. The researchers were also fascinated by the animals’ different hunting methods, such as knocking over stones, digging up sand or simply sitting and waiting. “We were also lucky enough to capture footage of a mother taking her puppy on a trip to the sea,” reported Angelakis. This provided the first direct evidence that Australian sea lion mothers pass on their foraging skills to their pups.
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To date, studies have tended to use remotely operated underwater vehicles as well as towed and dropped cameras from ships to collect high-resolution video and image data and enable detailed mapping and surveying of the seabed. “However, these ship-based investigations are costly, time- and personnel-intensive, and depend on suitable weather conditions,” the researchers wrote. This would make mapping large areas challenging.
Working with sea lions instead offers “unique advantages” because work can be done from shore with few personnel and relatively low costs, and operations are less dependent on weather conditions. In addition, videos could be collected from depths, habitats and marine areas that are difficult or impossible to access using conventional methods. In order to equip the animals with small cameras and sensors that transmit their speed and location, the researchers administered a light anesthetic to the sea lions using a breathing mask. The camera itself was glued to a piece of fabric, which was then attached to the sea lion’s fur with resin. When the animals returned to their young on land after a few days, the researchers removed the devices again. The material remains on the fur and falls off during the next moult.
By the way, the fact that scientists use animal helpers is not entirely new. In 2016, a study of elephant seals in Australia tried to figure out how melting ice was changing the depths of the ocean. For this purpose, elephant seals living there were equipped with satellite tags.
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