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The carapace matters: refinement of the instantaneous growth rate method for Antarctic krill Euphausia superba Dana, 1850 (Euphausiacea)


Melvin, JE and Kawaguchi, S and King, R and Swadling, KM, The carapace matters: refinement of the instantaneous growth rate method for Antarctic krill Euphausia superba Dana, 1850 (Euphausiacea), Journal of Crustacean Biology, 38, (6) pp. 689-696. ISSN 0278-0372 (2018) [Refereed Article]

Copyright Statement

Copyright 2018 The Authors

DOI: doi:10.1093/jcbiol/ruy069


Growth of Antarctic krill Euphausia superba Dana, 1850 is commonly calculated using the Instantaneous Growth Rate (IGR) method based on the difference between the uropod lengths of the moulted exoskeleton and the uropod lengths after moulting. To date, this method has not accounted for sex-dependent differences in body proportion, relying only upon uropod measurements. We measured the carapace, uropod, and total body lengths of gravid females, non-gravid females, males, and juvenile krill from the Indian Sector of the Southern Ocean. Growth rates derived using a combination of the carapace and uropod measurements for gravid females were different from those derived through the traditional uropod-only based IGR, whereas non-gravid females, male, and juvenile growth rates showed no significant difference between methods. The refined method we propose successfully reflects dimorphism in growth between the sexes of krill, with gravid females having enlarged carapaces during the reproductive season. The interaction between growth and reproduction must be considered to improve the reliability of predictions from krill life history models, which is possible through the use of sex-dependent IGR measurements. We propose that, whenever possible, measurements of carapace and total length should be made along with uropod measurements. Together with assessments of maturity stages of krill that did not moult during experiments, these measurements will aid in further informing krill stock assessments.

Item Details

Item Type:Refereed Article
Keywords:krill, growth, IGR, carapace, sexing, moults, gravid females, instantaneous growth rate (IGR) method, life history, sex dependent, Southern Ocean, sexual dimorphism
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:Melvin, JE (Miss Jessica Melvin)
UTAS Author:Kawaguchi, S (Dr So Kawaguchi)
UTAS Author:Swadling, KM (Associate Professor Kerrie Swadling)
ID Code:128389
Year Published:2018
Web of Science® Times Cited:4
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2018-09-18
Last Modified:2019-02-27

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