The Effect of Growth Rate, Phosphorus Concentration, and Temperature on N-2 Fixation, Carbon Fixation, and Nitrogen Release in Continuous Cultures of Trichodesmium IMS101

Authors

Margaret R. Mulholland, Old Dominion UniversityFollow
Peter W. Bernhardt, Old Dominion University

Document Type

Article

Publication Date

2005

DOI

10.4319/lo.2005.50.3.0839

Publication Title

Limnology and Oceanography

Volume

50

Issue

3

Pages

839-849

Abstract

With the use of continuous culture systems, rates of dinitrogen (N₂) and carbon (C) fixation and nitrogen (N)- and C-based doubling times were assessed in Trichodesmium IMS101 growing exponentially at steady state dilution rates of 0.10, 0.20, and 0.33 d^-1 (doubling times of 10, 5, and 3 d - within the range reported for natural populations). Rates of C fixation, N₂ fixation, and N release were examined in replicate culture systems with several techniques. Biomass-specific C uptake varied little with population doubling time, but N₂ fixation and N release varied markedly among treatments. Total daily gross N₂ fixation rates and estimated N release rates were higher in cultures with higher dilution rates. Cultures grown at lower dilution rates had higher daily C:N₂ fixation ratios and lower N release rates. Consistent with other studies, it was estimated that Trichodesmium released about 80-90% of their recently fixed N₂ during growth. Turnover of cellular C estimated from carbon fixation was a good estimator of population growth rates in steady state cultures, whereas turnover of cellular N estimated from gross or net N₂ fixation was not. Small changes in temperature (24°C vs. 28°C) did not appear to affect gross N₂ fixation, whereas inorganic phosphorus (1 vs. 5 μmol L^-1) supply had a large effect on N₂ fixation. These results suggest that continuous culture systems are excellent for elucidating physiological responses of Trichodesmium under ecologically relevant growth conditions and provide a framework for assessing highly variable field estimates of N₂ and C fixation.

Rights

Web of Science: "Free full-text from publisher."

Original Publication Citation

Mulholland, M. R., & Bernhardt, P. W. (2005). The effect of growth rate, phosphorus concentration, and temperature on N₂ fixation, carbon fixation, and nitrogen release in continuous cultures of Trichodesmium IMS101. Limnology and Oceanography, 50(3), 839-849. doi:10.4319/lo.2005.50.3.0839

Repository Citation

Mulholland, Margaret R. and Bernhardt, Peter W., "The Effect of Growth Rate, Phosphorus Concentration, and Temperature on N-2 Fixation, Carbon Fixation, and Nitrogen Release in Continuous Cultures of Trichodesmium IMS101" (2005). OES Faculty Publications. 297.
https://digitalcommons.odu.edu/oeas_fac_pubs/297

ORCID

0000-0001-8819-189X (Mulholland)