Saturating light and not increased carbon dioxide under ocean acidification drives photosynthesis and growth in Ulva rigida (Chlorophyta). Issue 4 (25th January 2015)

• Record Type: Journal Article
• Authors: Rautenberger, Ralf; Fernández, Pamela A.; Strittmatter, Martina; Heesch, Svenja; Cornwall, Christopher E.; Hurd, Catriona L.; Roleda, Michael Y.
• Is Part Of: Ecology and evolution. Volume 5:Issue 4(2015:Apr.)
• Page Start: 874
• Page End: 888
• Publication Date: 2015-01-25
• Subjects: Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.1382
• Languages: English
• ISSNs: 2045-7758

Abstract

<abstract abstract-type="main" id="ece31382-abs-0001"> <title>Abstract</title> <p>Carbon physiology of a genetically identified <italic>Ulva rigida</italic> was investigated under different CO<sub>2(aq)</sub> and light levels. The study was designed to answer whether (1) light or exogenous inorganic carbon (Ci) pool is driving growth; and (2) elevated CO<sub>2(aq)</sub> concentration under ocean acidification (OA) will downregulate CA<sub>ext</sub>‐mediated <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh3x0d865p" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:20457758:media:ece31382:ece31382-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>HCO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula> dehydration and alter the stable carbon isotope (<italic>δ</italic><sup>13</sup>C) signatures toward more CO<sub>2</sub> use to support higher growth rate. At pH<sub>T</sub> 9.0 where CO<sub>2(aq)</sub> is <1 <italic>μ</italic>mol L<sup>−1</sup>, inhibition of the known <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh3x0d8667" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:20457758:media:ece31382:ece31382-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>HCO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula> use mechanisms, that is, direct <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh3x0d868b" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:20457758:media:ece31382:ece31382-math-0003" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>HCO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula> uptake through the AE port and CA<sub>ext</sub>‐mediated <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh3x0d86bf" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:20457758:media:ece31382:ece31382-math-0004" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>HCO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula> dehydration decreased net photosynthesis (NPS) by only 56–83%, leaving the carbon uptake mechanism for the remaining 17–44% of the NPS unaccounted. An in silico search for carbon‐concentrating mechanism elements in expressed sequence tag libraries of <italic>Ulva</italic> found putative light‐dependent <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh3x0d86c0" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:20457758:media:ece31382:ece31382-math-0005" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>HCO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula> transporters to which the remaining NPS can be attributed. The shift in <italic>δ</italic><sup>13</sup>C signatures from –22‰ toward –10‰ under saturating light but not under elevated CO<sub>2(aq)</sub> suggest preference and substantial <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh3x0d86dj" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:20457758:media:ece31382:ece31382-math-0006" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>HCO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula> use to support photosynthesis and growth. <italic>U. rigida</italic> is Ci saturated, and growth was primarily controlled by light. Therefore, increased levels of CO<sub>2(aq)</sub> predicted for the future will not, in isolation, stimulate <italic>Ulva</italic> blooms.</p> </abstract>