Limitation of algal growth by iron deficiency in the Australian Subantarctic region
In March 1998 we measured iron in the upper water column and conducted iron- and nutrient-enrichment bottle-incubation experiments in the open-ocean Subantarctic region southwest of Tasmania, Australia. In the Subtropical Convergence Zone (42S, 142E), silicic acid concentrations were low (< 1.5 M...
Published in: | Geophysical Research Letters |
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Main Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Geophysical Union
1999
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Subjects: | |
Online Access: | https://doi.org/10.1029/1998GL002284 http://ecite.utas.edu.au/17093 |
Summary: | In March 1998 we measured iron in the upper water column and conducted iron- and nutrient-enrichment bottle-incubation experiments in the open-ocean Subantarctic region southwest of Tasmania, Australia. In the Subtropical Convergence Zone (42S, 142E), silicic acid concentrations were low (< 1.5 M) in the upper water column, whereas pronounced vertical gradients in dissolved iron concentration (0.12-0.84 nM) were observed, presumably reflecting the interleaving of Subtropical and Subantarctic waters, and mineral aerosol input. Results of a bottle-incubation experiment performed at this location indicate that phytoplankton growth rates were limited by iron deficiency within the iron-poor layer of the euphotic zone. In the Subantarctic water mass (46.8S, 142E), low concentrations of dissolved iron (0.05-0.11 nM) and silicic acid (< 1 M) were measured throughout the upper water column, and our experimental results indicate that algal growth was limited by iron deficiency. These observations suggest that availability of dissolved iron is a primary factor limiting phytoplankton growth over much of the Subantarctic Southern Ocean in the late summer and autumn. Copyright 1999 by the American Geophysical Union. |
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