The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography
Experiments were conducted in the equatorial Pacific Ocean to assess the role of Fe and grazing in regulating use of N03- by the phytoplankton community. Nitrate uptake rates in situ were slow because NH,+ concentrations were inhibitory and because phytoplankton biomass was kept low by grazing. When...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.589.3355 2023-05-15T13:55:08+02:00 The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography N. M. Price B. A. Ahner F. Ill M. Morel The Pennsylvania State University CiteSeerX Archives 1994 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.589.3355 http://www.aslo.org/lo/toc/vol_39/issue_3/0520.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.589.3355 http://www.aslo.org/lo/toc/vol_39/issue_3/0520.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.aslo.org/lo/toc/vol_39/issue_3/0520.pdf text 1994 ftciteseerx 2016-01-08T13:24:17Z Experiments were conducted in the equatorial Pacific Ocean to assess the role of Fe and grazing in regulating use of N03- by the phytoplankton community. Nitrate uptake rates in situ were slow because NH,+ concentrations were inhibitory and because phytoplankton biomass was kept low by grazing. When feeding of grazers was artificially suppressed, phytoplankton net growth rate increased, biomass accu-mulated, and NO,- was consumed. Rapid rates of Fe uptake [40 pmol Fe (g Chl a)- ’ h-l] decreased by an order of magnitude in l-2 d after Fe was added, demonstrating that these rates were under physiological regulation and were elevated in response to low Fe concentrations. Addition of Fe increased carbon uptake and the short-term N-specific NO,- uptake rate by 2-9 times. These physiological stimulations were confined to large phytoplankton (> 3 pm), which thus must have been Fe-limited in situ. N03- uptake rate and biomass of small phytoplankton were unaffected by Fe enrichment. The results thus suggest that the low biomass, N03--rich condition of the equatorial Pacific Ocean exists because low Fe concentrations limit use of N03- by large phytoplankton and favor growth of small phytoplankton that are grazed efficiently and use NH,+ preferentially. The equatorial Pacific is one of the regions of open ocean that is comparatively rich in nitrate and phosphate and low in chlorophyll; other such areas are in the Antarctic and sub-arctic Pacific. Several explanations for this un-usual condition have been offered. Two of these, grazing control and Fe limitation, were originally portrayed as antipodal hypotheses. We and others (Price et al. 1991; Chavez et al. Text Antarc* Antarctic Arctic Phytoplankton Unknown Antarctic Arctic Chavez ENVELOPE(-64.483,-64.483,-65.667,-65.667) Pacific The Antarctic |
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ftciteseerx |
language |
English |
description |
Experiments were conducted in the equatorial Pacific Ocean to assess the role of Fe and grazing in regulating use of N03- by the phytoplankton community. Nitrate uptake rates in situ were slow because NH,+ concentrations were inhibitory and because phytoplankton biomass was kept low by grazing. When feeding of grazers was artificially suppressed, phytoplankton net growth rate increased, biomass accu-mulated, and NO,- was consumed. Rapid rates of Fe uptake [40 pmol Fe (g Chl a)- ’ h-l] decreased by an order of magnitude in l-2 d after Fe was added, demonstrating that these rates were under physiological regulation and were elevated in response to low Fe concentrations. Addition of Fe increased carbon uptake and the short-term N-specific NO,- uptake rate by 2-9 times. These physiological stimulations were confined to large phytoplankton (> 3 pm), which thus must have been Fe-limited in situ. N03- uptake rate and biomass of small phytoplankton were unaffected by Fe enrichment. The results thus suggest that the low biomass, N03--rich condition of the equatorial Pacific Ocean exists because low Fe concentrations limit use of N03- by large phytoplankton and favor growth of small phytoplankton that are grazed efficiently and use NH,+ preferentially. The equatorial Pacific is one of the regions of open ocean that is comparatively rich in nitrate and phosphate and low in chlorophyll; other such areas are in the Antarctic and sub-arctic Pacific. Several explanations for this un-usual condition have been offered. Two of these, grazing control and Fe limitation, were originally portrayed as antipodal hypotheses. We and others (Price et al. 1991; Chavez et al. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
N. M. Price B. A. Ahner F. Ill M. Morel |
spellingShingle |
N. M. Price B. A. Ahner F. Ill M. Morel The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography |
author_facet |
N. M. Price B. A. Ahner F. Ill M. Morel |
author_sort |
N. M. Price |
title |
The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography |
title_short |
The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography |
title_full |
The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography |
title_fullStr |
The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography |
title_full_unstemmed |
The equatorial Pacific Ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. Limnology and Oceanography |
title_sort |
equatorial pacific ocean: grazer-controlled phytoplankton populations in an iron-limited ecosystem. limnology and oceanography |
publishDate |
1994 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.589.3355 http://www.aslo.org/lo/toc/vol_39/issue_3/0520.pdf |
long_lat |
ENVELOPE(-64.483,-64.483,-65.667,-65.667) |
geographic |
Antarctic Arctic Chavez Pacific The Antarctic |
geographic_facet |
Antarctic Arctic Chavez Pacific The Antarctic |
genre |
Antarc* Antarctic Arctic Phytoplankton |
genre_facet |
Antarc* Antarctic Arctic Phytoplankton |
op_source |
http://www.aslo.org/lo/toc/vol_39/issue_3/0520.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.589.3355 http://www.aslo.org/lo/toc/vol_39/issue_3/0520.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766261402118389760 |