Combined Effects of CO2 and Light on Large and Small Isolates of the Unicellular N2-Fixing Cyanobacterium Crocosphaera watsonii From the Western Tropical Atlantic Ocean

Authors

Nathan S. Garcia
Fei-Xue Fu
Cynthia L. Breene
Elizabeth K. Yu
Peter W. Bernhardt
Margaret R. Mulholland, Old Dominion UniversityFollow
David A. Hutchins

ORCID

0000-0001-8819-189X (Mulholland)

Document Type

Article

Publication Date

2013

DOI

10.1080/09670262.2013.773383

Publication Title

European Journal of Phycology

Volume

48

Issue

1

Pages

128-139

Abstract

We examined the combined effects of light and pCO₂ on growth, CO₂-fixation and N₂-fixation rates by strains of the unicellular marine N₂-fixing cyanobacterium Crocosphaera watsonii with small (WH0401) and large (WH0402) cells that were isolated from the western tropical Atlantic Ocean. In low-pCO₂-acclimated cultures (190ppm) of WH0401, growth, CO₂-fixation and N₂-fixation rates were significantly lower than those in cultures acclimated to higher (present-day approximate to 385ppm, or future approximate to 750ppm) pCO² treatments. Growth rates were not significantly different, however, in low-pCO₂-acclimated cultures of WH0402 in comparison with higher pCO₂ treatments. Unlike previous reports for C. watsonii (strain WH8501), N₂-fixation rates did not increase further in cultures of WH0401 or WH0402 when acclimated to 750ppm relative to those maintained at present-day pCO₂. Both light and pCO₂ had a significant negative effect on gross : net N₂-fixation rates in WH0402 and trends were similar in WH0401, implying that retention of fixed N was enhanced under elevated light and pCO₂. These data, along with previously reported results, suggest that C. watsonii may have wide-ranging, strain-specific responses to changing light and pCO₂, emphasizing the need for examining the effects of global change on a range of isolates within this biogeochemically important genus. In general, however, our data suggest that cellular N retention and CO₂-fixation rates of C. watsonii may be positively affected by elevated light and pCO₂ within the next 100 years, potentially increasing trophic transfer efficiency of C and N and thereby facilitating uptake of atmospheric carbon by the marine biota.

Rights

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

Original Publication Citation

Garcia, N. S., Fu, F. X., Breene, C. L., Yu, E. K., Bernhardt, P. W., Mulholland, M. R., & Hutchins, D. A. (2013). Combined effects of CO₂ and light on large and small isolates of the unicellular N₂-fixing cyanobacterium Crocosphaera watsonii from the western tropical Atlantic Ocean. European Journal of Phycology, 48(1), 128-139. doi:10.1080/09670262.2013.773383

Repository Citation

Garcia, Nathan S.; Fu, Fei-Xue; Breene, Cynthia L.; Yu, Elizabeth K.; Bernhardt, Peter W.; Mulholland, Margaret R.; and Hutchins, David A., "Combined Effects of CO2 and Light on Large and Small Isolates of the Unicellular N2-Fixing Cyanobacterium Crocosphaera watsonii From the Western Tropical Atlantic Ocean" (2013). OES Faculty Publications. 290.
https://digitalcommons.odu.edu/oeas_fac_pubs/290