MEPS 360:147-161 (2008)  -  DOI:

Biochemically based modeling study of Antarctic krill Euphausia superba growth and development

Bettina A. Fach1,2,*, Bettina Meyer1, Dieter Wolf-Gladrow1, Ulrich Bathmann1

1Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
2Institute of Marine Sciences, Middle East Technical University, PO Box 28, 33731 Erdemli, Turkey

ABSTRACT: A biochemical model of Antarctic krill Euphausia superba was developed to investigate the physiological mechanisms which enable krill to survive winter, when food is scarce. In this modeling approach data sets on the biochemical composition of krill and its food sources are combined into a model that takes food quality into account rather than just food availability during different seasons. Krill is defined in terms of protein, neutral lipid, polar lipid, carbohydrate, chitin, and ash content, and the model tracks krill neutral lipid content separately from weight. The model includes parameterizations of filtration, ingestion, and metabolic processes which determine krill growth rate. Initial ratios of protein, neutral lipid, polar lipid, carbohydrate and ash change in chitin response to the biochemical composition of food as krill grows. Model results show that a diet of phytoplankton food alone may be sufficient for krill to grow to observed sizes but may not be sufficient to provide the summer lipid resources that are observed in the field and that are necessary for krill to reproduce and survive winter. The inclusion of sea ice algae as an additional food is beneficial for krill at the end of winter but does not significantly change summer krill lipid content. However, the amount of lipids accumulated within krill increases significantly when krill feeds on lipid-rich heterotrophic food, which points to the importance of carnivory, even in times when phytoplankton food is available. The strategy of combusting body components to produce energy (shrinking) is found to provide the greatest source of energy for krill of all sizes during times of prolonged starvation. 

KEY WORDS: Antarctic krill · Biochemical · Growth model · Food quality · Overwinter strategies

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Cite this article as: Fach BA, Meyer B, Wolf-Gladrow D, Bathmann U (2008) Biochemically based modeling study of Antarctic krill Euphausia superba growth and development. Mar Ecol Prog Ser 360:147-161.

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