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Limitation of algal growth by iron deficiency in the Australian Subantarctic region

journal contribution
posted on 2023-05-16, 11:50 authored by Sedwick, PN, DiTullio, GR, Hutchins, DA, Boyd, PW, Griffiths, FB, Crossley, AC, Trull, T, Queguiner, B
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 (< 1.5 μM) 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 (0.05-0.11 nM) and silicic acid (< 1 μM) 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.

History

Publication title

Geophysical Research Letters

Volume

26

Issue

18

Pagination

2865-2868

ISSN

0094-8276

Department/School

Institute for Marine and Antarctic Studies

Publisher

American Geophysical Union

Place of publication

Washington

Repository Status

  • Restricted

Socio-economic Objectives

Oceanic processes (excl. in the Antarctic and Southern Ocean)

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