A lipid budget for Antarctic krill (Euphausia superba Dana)
Microplankton at five sites off South Georgia in January to February 1991 was dominated by a range of diatoms. The haptophyte Phaeocystis was present in three of the five sites but in low abundance only. Diatoms dominated at a more southerly site near the Antarctic Peninsula in March, whereas dinofl...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
University of Stirling
1993
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| Online Access: | http://hdl.handle.net/1893/21431 http://dspace.stir.ac.uk/bitstream/1893/21431/1/Pond-thesis.pdf |
| Summary: | Microplankton at five sites off South Georgia in January to February 1991 was dominated by a range of diatoms. The haptophyte Phaeocystis was present in three of the five sites but in low abundance only. Diatoms dominated at a more southerly site near the Antarctic Peninsula in March, whereas dinoflagellates dominated at a site near Deception Island. Multivariate analysis allowed the seven sites to be distinguished on the basis of microplankton species composition. Analysis of thirteen lipid classes present in total lipid extracted from the microplankton also demonstrated substantial differences from site to site. Multivariate analysis showed a different pattern of variation from the species ordination, with the South Georgia sites forming a distinct cluster. Outlier sites identified in the species and lipid ordinations confirmed the association between some taxonomic groups and lipid 'fingerprints'. Fatty acids extracted from total lipid in microplankton at five sites around South Georgia and two sites near the Antarctic Peninsula ranged from 37 to 195 J.Lg1-1, with a ratio of fatty acids in polar lipid: neutral lipid ranging from 4: 1 to 1:2. A further eleven particulate samples analysed from sites around the Antarctic Peninsula had slightly lower fatty acid content with a mean of 50 J.Lg1-1. Fatty acids in polar lipid were rich in (n-3) polyunsaturated fatty acids, chiefly 20:5(n-3). However, 22:6(n-3) could be as abundant as 20:5(n-3) in polar lipid from microplankton less than 20 J.1m, and also in dinoflagellate-rich microplankton. Neutral lipid was dominated by 16:0, 16:1(n-7) and 18:1(n-9) fatty acids and contained only low levels of (n-3) polyunsaturated fatty acids. The data reveal the high nutritional quality of microplankton lipids in the Southern Ocean for filter feeding animals, including krill. Samples of krill from eight sites around South Georgia consisted predominantly of immature animals, and females were entirely absent from samples from two of the eight sites studied. Animal wet mass varied ... |
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