Journal Article

Lagrangian modelling studies of Antarctic krill (<i>Euphausia superba</i>) swarm formation

Eileen E Hofmann, A.G.Edward Haskell, John M Klinck and Cathy M Lascara

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 61, issue 4, pages 617-631
Published in print January 2004 | ISSN: 1054-3139
Published online January 2004 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1016/j.icesjms.2004.03.028
Lagrangian modelling studies of Antarctic krill (Euphausia superba) swarm formation

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A two-dimensional Lagrangian particle model was developed to examine the spatial distribution of Antarctic krill (Euphausia superba). The time-dependent location of particles, which represent krill individuals, is determined by random diffusion, foraging activity, and movement induced by the presence of neighbours. Foraging activity is based on prescribed food conditions and is such that krill swim slower and turn more frequently in areas of high food concentration. The presence or absence of neighbours either disperses krill, if the local concentrations become too dense, or coalesces krill, if concentrations become too dilute, respectively. Predation on krill is included and affects swarm characteristics by removing individuals. Sensitivity studies indicate that the rate of krill swarm formation and the total number of swarms formed are determined primarily by foraging response and nearest neighbour sensing distance. Simulations using food distributions that are representative of those encountered at boundaries, such as fronts, mesoscale eddies, or the sea ice edge, show that foraging activity can produce rapid swarm formation. Results from other krill swarm models show that attraction between individuals is the primary mechanism producing krill swarms. However, the parameterizations for krill interactions used in those models and that used in this model differ, thereby implying different biological dynamics. Thus, parameterization of the basic interactions in krill swarm models remains to be defined.

Keywords: Antarctic krill; Krill swarms; Lagrangian models

Journal Article.  7088 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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