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 (∼42°S, 142°E), silicic acid concentrations were low (< 1....
| Published in: | Geophysical Research Letters |
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| Main Authors: | , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
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ODU Digital Commons
1999
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| Subjects: | |
| Online Access: | https://digitalcommons.odu.edu/oeas_fac_pubs/94 https://doi.org/10.1029/1998GL002284 https://digitalcommons.odu.edu/context/oeas_fac_pubs/article/1101/viewcontent/Sedwick_1999_Limitation_of_algal_growth_by_iro.pdf |
| 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 (∼42°S, 142°E), silicic acid concentrations were low (< 1.5μM) 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 (∼46.8°S, 142°E), low concentrations of dissolved iron (0.05-0.11nM) and silicic acid (< 1μM) 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. |
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