Vertical migration behaviour in the northern krill Meganyctiphanes norvegica is influenced by moult and reproductive processes

A population of the northern krill Meganyctiphanes norvegica was sampled between 24 July and 3 August 1998 in the Alkor Deep, Kattegat, in order to investigate the influence of sexual and developmental factors on the vertical distribution of adult krill. Depth-discrete samples of krill were taken wi...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 1999-12, Vol.190, p.253-262
Main Authors: Tarling, G. A., Cuzin-Roudy, J., Buchholz, F.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal migration behavior
Animal, plant and microbial ecology
Animals
Autoecology
Biological and medical sciences
Confidence interval
Earth Sciences
Eggs
Fundamental and applied biological sciences. Psychology
Krill
Marine
Mating behavior
Meganyctiphanes norvegica
North Sea
Oceanography
Plankton
Protozoa. Invertebrata
Salinity
Sciences of the Universe
Segregation
Surface layers
Vertical distribution
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Summary:A population of the northern krill Meganyctiphanes norvegica was sampled between 24 July and 3 August 1998 in the Alkor Deep, Kattegat, in order to investigate the influence of sexual and developmental factors on the vertical distribution of adult krill. Depth-discrete samples of krill were taken with aim2 MOCNESS net at the cardinal times of day (midnight, midday, sunrise and sunset). Specimens were immediately measured and categorised for moulting and spawning status. Further samples were preserved for detailed analysis in the home laboratory. Results showed that the population concentrated in the deep (80 to 100 m) during day-time but segregated vertically during night-time. Moulting occurred in the deep during night-time, away from the main part of the non-moulting population, which was located between 80 and 50 m. Spawning females were most evident in the uppermost depth interval (30 to 5 m). Moulting at night in the deepest layers may be viewed as a mechanism to avoid cannibalism whilst in a vulnerable condition. Spawning in the warm upper layers accelerates reproductive processes and may also reduce the depth to which the eggs sink before hatching into nauplii.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps190253