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The balance between photosynthesis and grazing in Antarctic mixotrophic cryptophytes

Citation

Marshall, W and Laybourn-Parry, J, The balance between photosynthesis and grazing in Antarctic mixotrophic cryptophytes, Freshwater Biology, 47, (11) pp. 2060-2070. ISSN 0046-5070 (2002) [Refereed Article]

DOI: doi:10.1046/j.1365-2427.2002.00950.x

Abstract

1. Grazing and photosynthetic contributions to the carbon balance of planktonic, mixotrophic cryptophytes in Lakes Fryxell and Hoare in the Taylor Valley, Antarctica were measured during November and December 2000. 2. The cryptophytes never became entirely photosynthetic, although carbon derived from grazing decreased in December. Individual grazing rates ranged between 5.28 and 10.08 bacteria cell-1 day-1 in Lake Fryxell and 0.36-11.76 bacteria cell-1 day-1 in Lake Hoare. Grazing rates varied temporally and with depth in the water column. In Lake Fryxell, which is a meromictic lake, highest grazing occurred just above the chemocline. Individual photosynthetic rates ranged from 0.23 to 1.35 pg C cell-1 h-1 in Lake Fryxell and 0.074 to 1.08 pg C cell-1 h-1 in Lake Hoare. 3. Carbon acquisition by the cryptophyte community gained through grazing ranged between 8 and 31% during November in Lake Fryxell, dropping to between 2 and 24% in December. In Lake Hoare grazing contributed 12-21% of the community carbon budget in November and 1-28% in December. Around 4% of the carbon acquired from grazing and photosynthesis was remineralised through respiration. 4. Mixotrophy is probably a major survival strategy for cryptophytes in the extreme lakes of the Dry Valleys, because perennial ice-cover severely limits light penetration to the water column, whereas these phytoflagellates are not normally mixotrophic in lower latitude lakes. The evidence suggests that mixotrophy may be a mechanism for supplementing the carbon budget, as well as a means of acquiring nutrients for growth.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbial Ecology
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Antarctic and Sub-Antarctic Flora, Fauna and Biodiversity
Author:Laybourn-Parry, J (Professor Johanna Laybourn-Parry)
ID Code:49067
Year Published:2002
Web of Science® Times Cited:43
Deposited By:Research Division
Deposited On:2007-11-12
Last Modified:2011-08-02
Downloads:0

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