QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online November 28, 2008
Journal of Experimental Biology 211, 3850-3858 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.024232

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Auerswald, L. Articles by Meyer, B. Search for Related Content PubMed PubMed Citation Articles by Auerswald, L. Articles by Meyer, B. Social Bookmarking                         What's this?

Physiological and morphological colour change in Antarctic krill, Euphausia superba: a field study in the Lazarev Sea

Lutz Auerswald^1,*, Ulrich Freier², Andreas Lopata^3,4 and Bettina Meyer²

¹ Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa
² Scientific Division Biological Oceanography, Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
³ Division of Immunology, IIDMM-Institute, University of Cape Town, 7925 Observatory, Cape Town, South Africa
⁴ School of Applied Sciences, Allergy Research Group, RMIT University, Melbourne, VIC 3083, Australia

^* Author for correspondence (e-mail: lauerswa{at}deat.gov.za)

Accepted 14 October 2008

Antarctic krill, Euphausia superba, is very susceptible to harmful solar radiation because of its unique genetic setup. Exposure occurs in spring to autumn during vertical diel migration and during occasional daytime surface-swarming. We have investigated colour change in Antarctic krill, Euphausia superba, during summer and winter in the Lazarev Sea in response to ultraviolet radiation (UVR) and photosynthetically active radiation (PAR). Short-term physiological colour change and long-term (seasonal) morphological colour change are present. Both are facilitated by a single type of monochromatic red chromatophore, i.e. erythrophores, of 20–450 µm diameter. Superficial erythrophores cover large dorsal areas, especially above vital organs (brain, sinus glands), additional `profound' erythrophores cover internal organs (heart, gut, nerve cords). Short-term change in light regime causes rapid physiological colour change along dense bundles of microtubules: pigment disperses into chromorhizae upon exposure to PAR and UVA and to a lesser extent to UVB. Darkness leads to aggregation of pigment in the centre and hence blanching. There is no circadian rhythm in the dispersal state of erythrophores present in winter. Physiological colour change in adult krill is two to three times more rapid in summer than in winter. Furthermore, seasonal changes in light regime also result in a profound morphological colour change: in summer animals, abdominal astaxanthin concentration is 450% and erythrophore count is 250–480% higher than in winter krill. We conclude from our results, that pigmentation of E. superba serves in the protection from harmful solar radiation and is adapted to the varying diel and seasonal light conditions.

Key words: colour change, chromatophore index, UV protection, pigmentation, astaxanthin, erythrophore

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				H. Vestheim and S. Kaartvedt Vertical migration, feeding and colouration in the mesopelagic shrimp Sergestes arcticus J. Plankton Res., November 1, 2009; 31(11): 1427 - 1435. [Abstract] [Full Text] [PDF]