Australia turns to sea lions to map the ocean floor

Thursday, August 15, 2024, 00:56

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Ocean exploration and conservation has advanced significantly in recent decades, but large underwater areas remain mysterious and inaccessible to researchers. A recent study published in ‘Frontiers in Marine Science‘ has introduced an innovative approach to addressing this challenge: the use of cameras attached to sea lions to map and study seabed habitats in South Australian waters. According to Nathan Angelakis, one of the researchers, this pioneering method, known as ‘video-borne’, promises to open new frontiers in marine research and has the potential to revolutionise the way marine ecosystems are monitored and protected.

The new study proposes a unique solution to these challenges by using cameras attached to sea lions. The researchers selected eight sea lions, also known as fur seals (Otariidae), as camera-carrying subjects because of their ability to dive to great depths and cover large underwater areas. These marine mammals are hunters that explore diverse habitats in search of food, making them natural vehicles for data collection.

A sea lion with a camera attached.

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The study attempted to ensure that the cameras did not interfere with the animals’ natural behaviour, and designed a lightweight, non-invasive camera. Each camera was equipped with a waterproof housing and a high-definition recording system, capable of capturing clear, detailed images even in low-light conditions. In addition, these devices were programmed to record during specific intervals, allowing the researchers to obtain a wide range of data during the sea lions’ periods of activity.

A window to a diverse underwater world

The study was conducted in a region known for its rich marine biodiversity in South Australian waters, such as Gulf St Vincent and Spenser Gulf. During the research period, fur seals equipped with cameras explored a variety of benthic habitats, including coral reefs, seagrass beds and rocky areas. The captured images provided an unprecedented view of these underwater ecosystems, revealing a diversity of species and habitat structures. They were able to verify that invertebrate communities (sponges, bryozoans and soft corals) dominate the depths where macroalgal reefs and macroalgal beds are absent. The structures of these communities are influenced by nutrient supply, topography, substrate availability, seawater conditions and hydrodynamics.

One of the most notable findings of the study was the identification of areas with complex structure, where rock formations and corals provided refuge for a variety of marine species and which could not be accessed by traditional seafloor mapping methods such as scuba diving, the use of remotely operated vehicles (ROVs) or sonar surveys. Although effective, these techniques are often expensive, require specialized equipment, and are limited by environmental conditions. These areas are crucial to ecosystem health, as they serve as breeding, feeding and refuge grounds for many species.

Benthic habitats – benthos are the community of bottom-dwelling organisms in aquatic ecosystems – which include the seabed and structures found on the ocean floor, are essential for marine biodiversity. These habitats are home to a wide variety of species, from corals to sponges and algae, and play a crucial role in the balance of ocean ecosystems. However, exploring these habitats presents numerous challenges. The depth of the sea, strong currents, and limited visibility make it difficult for researchers to access and map these areas accurately. Traditionally, techniques have been used to measure the depth of the ocean, and many areas, especially in remote or hard-to-reach regions, remain largely unexplored.

The ability to accurately and efficiently map these marine habitats has important implications for marine conservation, which is facing climate change, overfishing and pollution. This study demonstrates that the use of cameras on sea lions can be a valuable and environmentally friendly tool for collecting this data, especially in areas that are inaccessible or difficult to study using traditional methods. Data obtained through this approach can help decision-makers identify priority areas for conservation.

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