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

ORCID

0000-0001-8819-189X (Mulholland)

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