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On the food of northern krill Meganyctiphanes norvegica in relation to its vertical distribution
Citation
Lass, S and Tarling, G and Virtue, P and Matthews, J and Mayzaud, P and Buchholz, F, On the food of northern krill Meganyctiphanes norvegica in relation to its vertical distribution, Marine Ecology - Progress Series, 214 pp. 177-200. ISSN 0171-8630 (2001) [Refereed Article]
Copyright Statement
Copyright 2001 Inter-Research
Abstract
The feeding behaviour of northern krill (Meganyctiphanes norvegica) was studied in
populations from the Clyde Sea and the Kattegat during summer and winter. The food spectrum in the
stomachs was analysed using traditional taxonomic methods and biochemical techniques. The vertical
migration behaviour of krill was monitored through a 30 h series of net samples, whilst the trophic environment
was characterised through accompanying quantitative analyses on the depth distribution
and biomass of copepods and phytoplankton. Krill was found to be more carnivorous in the Kattegat
than in the Clyde Sea, which correlated with the higher ratio of copepod to phytoplankton biomass
found in the Kattegat compared with the Clyde Sea. High levels of fatty alcohols and other lipid markers
in the stomach contents of Kattegat krill were also indicative of a carnivorous diet. Other food
sources included detritus, terrestrial material and other euphausiids, underlining the opportunistic nature
of northern krill in its choice of prey items. Analyses of stomach and intestinal fullness over a diel
cycle showed significant variations with time in the Clyde Sea but not in the Kattegat. However, a diel
cycle in the rate of ingestion was evident at both locations when comparing the copepod mandibles in
the stomachs to the distribution of copepods in the environment. The fact that deep-living Calanus was
not a major prey item suggested that there was little feeding activity during the daytime, when the krill
occupied the deeper layers. Instead, the majority of mandibles were from species that were dominant
in the upper layers, e.g. the genera Temora and Pseudocalanus. The fact that krill caught in the daytime
contained the same relative composition of mandibles in the stomach as those caught at night is
probably explained by a cessation in daytime feeding activity and retention of the mandibles from the
night before. It is proposed that krill in the Clyde Sea area and the Kattegat show a diel rhythm in feeding
activity that is believed to be an adaptive response to minimising predation risk.
Item Details
Item Type: | Refereed Article |
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Keywords: | diet, krill , vertical distribution, Meganyctiphanes norvegica, Fatty acids · Alcohols ·Sterols |
Research Division: | Biological Sciences |
Research Group: | Ecology |
Research Field: | Marine and estuarine ecology (incl. marine ichthyology) |
Objective Division: | Environmental Management |
Objective Group: | Management of Antarctic and Southern Ocean environments |
Objective Field: | Biodiversity in Antarctic and Southern Ocean environments |
UTAS Author: | Virtue, P (Associate Professor Patti Virtue) |
ID Code: | 90448 |
Year Published: | 2001 |
Web of Science® Times Cited: | 43 |
Deposited By: | IMAS Research and Education Centre |
Deposited On: | 2014-04-04 |
Last Modified: | 2014-06-10 |
Downloads: | 0 |
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