PLOS ONE published a paper on the seafloor survey of Greenland Glacier Fjord using our "LoggLaw CAM".

An international research team led by Evgeny A. Podolskiy of the Hokkaido University Center for Arctic Research has published the results of synchronized video and acoustic observations conducted on the seafloor of a glacial fjord in northwestern Greenland using our underwater video logger, “LoggLaw CAM,” in the international academic journal PLOS ONE (May 6, 2026).From the behavior of deep-sea amphipods and copepods to backward-drifting fish of the family Scorpaenidae and even the acoustic presence of narwhals, the study reveals the previously hard-to-observe ecosystem of the glacial fjord seafloor.

Publication details: Podolskiy EA, Ogawa M, Hasegawa K, Tomiyasu M, Sugiyama S, Mitani Y. (2026) Seafloor video-acoustic monitoring in a Greenlandic glacial fjord records hyperbenthos, backward-swimming fish, and narwhals. PLOS ONE. https://doi.org/10.1371/journal.pone.0347193

Survey Overview

The survey was conducted in August 2025 in the Inglefield Bredning Fjord in northwestern Greenland (near 77°28′ N, 66°21′ W).The research team deployed a small mooring system—comprising a LoggLaw CAM, an acoustic recorder (SoundTrap ST600), and ocean environmental sensors—on the seafloor at a depth of approximately 260 m between the Qeqertaq and Heilprin glaciers for about eight days. With a compact configuration consisting of a single transport case and a total weight of less than 15 kg, the system enabled operations in polar field environments where access by helicopter or boat is essential.

Key Findings

• A total of 478 individuals representing more than 11 taxonomic groups were identified. Visual analysis of 37 hours of video footage revealed that isopods (47%) and copepods (26%) were the dominant groups. This data represents a valuable case of continuous observation of the hyperbenthos on the seafloor of a glacial fjord.
• Recorded “backward swimming” by fish of the family Scorpaenidae — Video captured the rare behavior of these fish passively drifting backward by yielding to currents near the seafloor.
• Acoustic presence of narwhals detected throughout the entire period — Synchronously recorded underwater sounds indicated that narwhals continuously visit the deep parts of the fjord during the summer.
• Variations in particle flux synchronized with tides — Analysis using Digital Particle Image Velocimetry (DPIV) quantified that particle transport modulates on a cycle of approximately 12 hours.

The Role of the LoggLaw CAM

The "LoggLaw CAM" used in this survey is an underwater video logger equipped with red LED (wavelength ~660 nm) lighting to minimize the impact on deep-sea animals and hydrophone-synchronized recording.In this study, a model rated for depths of 500 m was used to record synchronized VGA (640×480 pixels, 30 fps) video and 96 kHz audio data for 10 minutes every 20 minutes.

It is well known that trawl nets and sediment samplers, which have been used in conventional seabed ecological surveys, make it difficult to capture the behavior of highly mobile animals, and that the sampling process itself affects the animal community. Since LoggLaw CAM enables long-term continuous observation in a passive and non-invasive manner, this paper positions it as an “alternative methodology for ecological surveys in the deep glacial fjords.”

Significance and Future Developments

This paper represents a rare case where synchronized observations of video, acoustic, and physical parameters were successfully completed using a single set of compact equipment in the challenging environment of a polar glacial fjord. It demonstrates that our line of underwater logger products can contribute to international research projects focused on monitoring polar coastal ecosystems, where the effects of climate change are particularly pronounced.

Moving forward, we will continue to develop and provide solutions for acquiring video, acoustic, and behavioral data tailored to polar, deep-sea, and coastal environments. By collaborating with research institutions both domestically and internationally, we aim to contribute to the understanding and conservation of marine ecosystems.

Co-authors

• Evgeny A. Podolskiy (Hokkaido University, Center for Arctic Research) — Lead Author and Corresponding Author
• Monica Ogawa (Center for Arctic Research, Hokkaido University / National Institute of Polar Research)
• Kohei Hasegawa (Hokkaido University, Graduate School of Fisheries Science)
• Makoto Tomiyasu (Hokkaido University, Graduate School of Fisheries Science)
• Shin Sugiyama (Hokkaido University, Institute of Low Temperature Science)
• Yoko Mitani (Kyoto University, Center for Wildlife Research)

Supplementary Materials (PLOS ONE Supplementary Materials)

As supplementary materials for this paper, PLOS ONE has published a compilation of highlights from footage captured by LoggLaw CAM, videos of the analysis process, and an annotation table of all detected organisms. These can be downloaded directly from the links below.

• S1 Video ― Videos of organisms (MOV): A highlight reel featuring organisms that passed through the system and synchronized audio when they were detected.
  https://doi.org/10.1371/journal.pone.0347193.s001
• S2 Video ― Automatic image processing (MOV): A frame-by-frame demonstration of the automatic image processing procedure that calculates particle count, coverage area, and average luminance.
  https://doi.org/10.1371/journal.pone.0347193.s002
• S3 Video ― PIV processing (MOV): 0049*.MOV
  https://doi.org/10.1371/journal.pone.0347193.s003
• S1 Table ― Table of detections (CSV): Annotation table of all detected organisms.
  https://doi.org/10.1371/journal.pone.0347193.s004
• S1 Figure ― Periodograms (PDF): Periodic analysis of particle coverage area, particle count, and red luminance (with 95% confidence intervals).
  https://doi.org/10.1371/journal.pone.0347193.s005

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