IX SCAR International Biology Symposium

Effect of a carnivorous diet on the lipids, fatty acids and condition of Antarctic krill, Euphausia superba

Wilhelm Hagen^a1 c1, Toshihiro Yoshida^a2a3, Patti Virtue^a2, So Kawaguchi^a3, Kerrie M. Swadling^a4, Stephen Nicol^a3a5 and Peter D. Nichols^a5a6

^a1 Marine Zoology, University of Bremen, D-28334 Bremen, Germany

^a2 Institute of Antarctic and Southern Ocean Studies, University of Tasmania, Private Bag 77, Hobart, TAS 7001, Australia

^a3 Australian Antarctic Division, TAS 7050, Australia

^a4 TAFI, University of Tasmania, Private Bag 49, Hobart, TAS 7001, Australia

^a5 ACE CRC, University of Tasmania, Private Bag 80, Hobart, TAS 7001, Australia

^a6 CSIRO, Division of Marine and Atmospheric Research, Hobart, TAS 7001, Australia

Abstract

Krill are thought to be predominantly herbivorous, but a heterotrophic diet might be crucial for their growth and survival. To compare the influence of herbivory and carnivory on krill we conducted a nine month feeding trial. We examined lipid composition of the hepatopancreas, abdomen and remaining body portions of krill fed diatoms at bloom condition levels, and diatoms with the addition of pellets or minced clam meat to simulate a partly carnivorous diet. Mortality, dry mass and lipid content were similar among treatments. We examined lipid class and fatty acid profiles, with emphasis placed on the ratio of storage (triacylglycerol) to structural (polar lipid) lipid and key essential omega 3 polyunsaturated fatty acids: 20:5ω3 and 22:6ω3. The triacylglycerol : polar lipid ratio increased in krill fed on the mixed diet as did the 20:5ω3 : 22:6ω3 ratio. Overall these findings indicate that provision of clam in the diet improved krill condition, and further suggest that carnivory may aid krill growth in the wild under certain environmental conditions.

(Received September 12 2006)

(Accepted March 21 2007)

Key words

• copepods;
• polar lipid;
• polyunsaturated fatty acids;
• triacylglycerol;
• trophic interactions

Correspondence:

^c1 *corresponding author: whagen@uni-bremen.de