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<front>
<journal-meta>
<journal-id journal-id-type="publisher">BGD</journal-id>
<journal-title-group>
<journal-title>Biogeosciences Discussions</journal-title>
<abbrev-journal-title abbrev-type="publisher">BGD</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Biogeosciences Discuss.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1810-6285</issn>
<publisher><publisher-name></publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/bgd-4-209-2007</article-id>
<title-group>
<article-title>Co-limitation by iron, silicate, and light of three Southern Ocean diatom species</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Hoffmann</surname>
<given-names>L. J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Peeken</surname>
<given-names>I.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Lochte</surname>
<given-names>K.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Leibniz Institute of Marine Science at the University of Kiel, Duesternbrooker Weg 20, 24105 Kiel, Germany</addr-line>
</aff>
<pub-date pub-type="epub">
<day>31</day>
<month>01</month>
<year>2007</year>
</pub-date>
<volume>4</volume>
<issue>1</issue>
<fpage>209</fpage>
<lpage>247</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2007 L. J. Hoffmann et al.</copyright-statement>
<copyright-year>2007</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by-nc-sa/2.5/">https://creativecommons.org/licenses/by-nc-sa/2.5/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://bg.copernicus.org/preprints/4/209/2007/bgd-4-209-2007.html">This article is available from https://bg.copernicus.org/preprints/4/209/2007/bgd-4-209-2007.html</self-uri>
<self-uri xlink:href="https://bg.copernicus.org/preprints/4/209/2007/bgd-4-209-2007.pdf">The full text article is available as a PDF file from https://bg.copernicus.org/preprints/4/209/2007/bgd-4-209-2007.pdf</self-uri>
<abstract>
<p>The effect of combined iron, silicate, and light co-limitation was
investigated in two Southern Ocean diatom species, &lt;i&gt;Chaetoceros dichaeta&lt;/i&gt; and &lt;i&gt;Actinocyclus&lt;/i&gt; sp. and one
cosmopolitan species, &lt;i&gt;Chaetoceros debilis&lt;/i&gt;, all isolated in the Southern Ocean (SO). We found
species specific differences in the level of nutrient limitation and its
effect on physiological and morphological parameters.
&lt;br&gt;&lt;br&gt;
Growth of all species tested was clearly co-limited by iron and silicate,
reflected in a 4 to 40 times higher increase in cell numbers in the high
iron, high silicate treatments compared with the controls. However, the
effect of iron and silicate availability on chain length and frustules
structures was species specific. Most drastic frustule malformation was
found under iron and silicate co-limitation in &lt;i&gt;C. dichaeta&lt;/i&gt; while Si limitation caused a
strong cell elongation in both &lt;i&gt;Chaetoceros&lt;/i&gt; species. Additional a significant increase
in chain length was observed in these species under high iron conditions.
Therefore, species composition in the SO is likely also indirectly affected
by these nutrients via different effects on diatom grazing protection. These
morphological changes reflect a potential as biological markers in sediments
for the growth history of chain forming species.
&lt;br&gt;&lt;br&gt;
High light conditions, comparable with light intensities found in the upper
28 m of the SO, showed a negative impact on growth of the endemic species
&lt;i&gt;C. dichaeta&lt;/i&gt; and &lt;i&gt;Actinocyclus&lt;/i&gt; sp. This is in contrast to the assumed light limitation of SO diatoms and
indicates an adaptation strategy to the deep mixing and resulting low light
conditions in the SO. In contrast to that, the cosmopolitan species &lt;i&gt;C. debilis&lt;/i&gt; was not
negatively affected by increased light intensity, indicating adaptation to a
broader light environment. These results suggest that light limitation of SO
phytoplankton due to deep wind mixed layers may play a minor role than
hitherto assumed.</p>
</abstract>
<counts><page-count count="39"/></counts>
</article-meta>
</front>
<body/>
<back>
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