A seabed camera follows Antarctic krill’s winter rhythm
A three-day camera deployment in Antarctic waters found far more krill in view at night than during daylight. The peer-reviewed observational study follows animals close to the seabed, adding a local view of winter behaviour. Its counts describe one camera’s surroundings, while oxygen associations and artificial illumination leave the causes of movement unresolved.
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Nighttime counts exceeded daylight counts
Krill, the small crustaceans followed in a peer-reviewed observational study, appeared much more frequently at night in a seabed camera’s view near the Antarctic Peninsula, in Great Wall Bay. Chaofeng Wang and colleagues found a nighttime mean of 34.3 animals in each frame, compared with 1.3 in daylight. Their 72 hours of footage covered May 31 to June 3, 2023, with 865 sampled frames. These measurements describe the animals visible in a small area rather than the bay’s total population.[1]
Oxygen varied with local movement
The researchers identified six aggregation and dispersal phases and compared them with temperature, salinity, currents and dissolved oxygen. Within the selected phases, counts were most strongly associated inversely with dissolved oxygen. The observational comparison cannot establish the drivers of the movement. Daylight lasted about 6 hours at the site, leaving an 18-hour night, so the deployment did not take place in continuous darkness.[1]
The camera watched a narrow seabed zone
The instrument’s depth was 28 m, with its lens 0.5 m above sediment and observed approximately 0.5–3 m ahead. Its 12 W light remained on throughout. Image resolution prevented reliable species identification, and the light’s behavioural effects were not measured with a separate dark control. The authors propose longer monitoring, acoustic observations and net sampling to complement this short winter deployment.[1]
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