Greenland – Researchers have captured rare footage of deep-sea life, including unusual fish movement and acoustic signals from marine mammals, using a compact video-acoustic system placed on the seafloor of a remote Arctic fjord.

The monitoring system was deployed in a Greenlandic fjord to observe marine biodiversity without disturbing the surrounding ecosystem. It was positioned at a depth of 260 meters in Inglefield Bredning, northwest Greenland.

Scientists from Hokkaido University’s Arctic Research Center developed the lightweight device, which weighs less than 15 kilograms and can be carried in a single transport box.

The system was designed to remain “invisible” to marine life. It uses a high-frequency video camera, hydrophones, and red LED lighting, which does not fall within the visible range for many deep-sea organisms.

Over 37 hours of recorded material revealed activity within the hyperbenthos, the layer of life just above the seafloor. A total of 478 organisms were detected, mainly small invertebrates including amphipods, copepods, arrowworms, and jellyfish.

The footage also recorded larger and more unusual observations. A snailfish was seen swimming backward, with its tail curled as it moved through the water.

Hydrophones captured daily ultrasonic sounds from narwhals, although the animals were not fully visible in the recordings. A narwhal tusk was also seen passing extremely close to the camera lens, within just tens of centimeters.

The data further showed rapid environmental changes, including shifts in marine snow, organic particles that can double in concentration within hours. The direction of this movement was observed to reverse every six hours due to tidal currents.

Researchers say the portable system offers a scalable method for polar studies and could improve future monitoring of species discovery and environmental changes in the rapidly warming Arctic.

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