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Influence of individual state on swimming capacity and behaviour of Antarctic krill Euphausia superba

Johnson, Magnus L.; Tarling, Geraint A.. 2008 Influence of individual state on swimming capacity and behaviour of Antarctic krill Euphausia superba. Marine Ecology Progress Series, 366. 99-110. 10.3354/meps07533

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Abstract/Summary

Swarms of Antarctic krill are frequently biased towards certain body sizes, sexes, maturities and physiological states. However, the mechanisms causing such biases remain unclear, with some speculating on differential responses to chemical or visual cues. This study examines the influence of individual state on swimming behaviour and performance, which, in turn, may cause biases in swarm composition. The frequency and strength of pleopod beats as well as the overall swimming capacity of Antarctic krill Euphausia superba were measured using a tethering technique. Individual state was considered in terms of body size, sex, maturity, moult stage and stomach fullness. Significant differences in the rate and strength of pleopod strokes as well as in the overall swimming capacity were found between individuals in different states. Body size had one of the strongest influences, with beat rate decreasing and beat strength increasing with increasing size. The sex and maturity of an individual altered this pattern, with adult females having faster but weaker pleopod beats than males of equivalent size. The difference in swimming style of females may impose a different lifestyle to that of males. Moult stage also had a significant influence on swimming, with moulting/post-moult individuals having significantly lower swimming capacities, making them unlikely to keep pace with intermoult counterparts. Both the rate and the strength of the pleopod beat were significantly lower in satiated compared to unsatiated individuals, which may contribute to the dispersion of swarms during feeding.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3354/meps07533
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > DISCOVERY 2010 - Integrating Southern Ocean Ecosystems into the Earth System
ISSN: 0171-8630
Additional Keywords: sex-dependent; moult; maturity; swarm; satiation; pleopods; Antarctic; Southern ocean
NORA Subject Terms: Marine Sciences
Biology and Microbiology
Zoology
Ecology and Environment
Date made live: 17 Jan 2011 12:11
URI: http://nora.nerc.ac.uk/id/eprint/11534

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