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Biochemical composition and photosynthate distribution in sea ice microalgae of McMurdo Sound, Antarctica: evidence for nutrient stress during the spring bloom

Published online by Cambridge University Press:  13 May 2004

Michael P. Lizotte  and
Cornelius W. Sullivan
Michael P. Lizotte
Affiliation:
Biology Department, Montana State University, Bozeman, Montana 59717, USA
Cornelius W. Sullivan
Affiliation:
Hancock Institute of Marine Studies and Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-0371, USA
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Abstract

The nutrient status of microalgae inhabiting sea ice in McMurdo Sound, Antarctica was evaluated during the peak and decline of the spring bloom in November and December. Natural populations of microalgae were analysed for C, N, chlorophyll a, protein, lipid, polysaccharide, and low-molecular-weight carbohydrate content, and for the distribution of 14C-labelled photosynthate into macromolecular fractions. Ratios of N:C and protein to carbohydrate (PR:CHO) were similar to values reported for nutrient-limited phytoplankton. Biochemical ratios and 14C-photosynthate allocation patterns suggest that microalgae from congelation ice habitats may be more nutrient-stressed than those from underlying platelet ice habitats. This trend would be consistent with the presumed gradient of seawater nutrient influx through the platelet layer to the bottom congelation ice habitat. Microalgae from congelation ice subjected to an experimental depletion of nutrients (particularly nitrate) showed decreased N:C, PR:CHO, and allocation of 14C-photosynthate to proteins. This evidence suggests that sea ice microalgae are nutrient-stressed during the peak and decline of the spring bloom in McMurdo Sound, which presumably begins when microalgal biomass concentrations and demands for growth reach or exceed the rate of nutrient supply from underlying seawater.

Keywords

biochemical compositiondiatomsnutrientsphotosynthesissea icesea ice algae
Type
Papers—Life Sciences and Oceanography
Information
Antarctic Science , Volume 4 , Issue 1 , March 1992 , pp. 23 - 30
Copyright
© Antarctic Science Ltd 1992

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