Plasticity of N:P ratios in laboratory and field populations of Trichodesmium spp.
© 2006 Inter-Research. DOI:10.3354/ame042243 We followed changes in N:P ratios in batch cultures of the planktonic marine cyanobacterium Trichodesmium (IMS 101) grown in 2 different media and in field populations from 4 different oceanic regions. Cultures grown on low P media showed a rapid rise in...
Published in: | Aquatic Microbial Ecology |
---|---|
Main Authors: | , , , , |
Other Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Georgia Institute of Technology
2006
|
Subjects: | |
Online Access: | http://hdl.handle.net/1853/43090 https://doi.org/10.3354/ame042243 |
Summary: | © 2006 Inter-Research. DOI:10.3354/ame042243 We followed changes in N:P ratios in batch cultures of the planktonic marine cyanobacterium Trichodesmium (IMS 101) grown in 2 different media and in field populations from 4 different oceanic regions. Cultures grown on low P media showed a rapid rise in N:P ratio upon depletion of phosphate. Ratios exceeding 125 were reached in 1 experiment before attaining stationary phase. A transect across the North Atlantic Ocean along 32°N showed a monotonic decrease in the N:P ratio of field collected colonies, dropping from about 60:1 on the western side of the basin to about 30:1 on the eastern side. A second cruise sampled colonies and surface slicks in waters along the north coast of Australia, where ratios of N:P were generally lower than in the North Atlantic, ranging from 11:1 to 47:1 with an average of 22:1. A comparison of rising and sinking colonies collected at 8 stations in the Gulf of Mexico shows a higher mean N:P ratio among sinking colonies than floating colonies. Overall, the average N:P in the Gulf of Mexico was about 68:1. N:P ratios of Trichodesmium around the Hawaiian Islands were very consistent between 2 consecutive years of sampling, with an average colony N:P for both years of about 38:1. Our research demonstrates high variability in the cellular N:P in Trichodesmium both in the laboratory and in the field. Trichodesmium N:P ratio may provide an index to the relative severity of P limitation in these diazotrophs. Geochemical and ecological modeling efforts which rely on using the N:P ratio of diazotrophs in deriving nitrogen fixation rates should account for the variability of these ratios in situ. |
---|