Cook, Clayton B.;
Muller-Parker, Gisele;
D'Elia, Christopher F.
Ammonium Enhancement of Dark Carbon Fixation and Nitrogen Limitation in Symbiotic Zooxanthellae: Effects of Feeding and Starvation of the Sea Anemone Aiptasia pallida
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Media type:
E-Article
Title:
Ammonium Enhancement of Dark Carbon Fixation and Nitrogen Limitation in Symbiotic Zooxanthellae: Effects of Feeding and Starvation of the Sea Anemone Aiptasia pallida
Contributor:
Cook, Clayton B.;
Muller-Parker, Gisele;
D'Elia, Christopher F.
imprint:
American Society of Limnology and Oceanography, 1992
Published in:Limnology and Oceanography
Language:
English
ISSN:
0024-3590
Origination:
Footnote:
Description:
<p>The nutrient status of algae symbiotic with marine invertebrates is controversial. We assessed the nitrogen status of zooxanthellae symbiotic with the sea anemone Aiptasis pallida using NH<sub>4</sub>
<sup>+</sup>enhancement of dark C fixation; enhancement increases with N limitation in other microalgae. Freshly isolated symbionts obtained from laboratory populations of known feeding history and from field populations were assayed: NH<sub>4</sub>
<sup>+</sup>enhancement depended on the nutritional history of the host anemones. Zooxanthellae from well-fed laboratory populations showed little enhancement of dark<sup>14C</sup>fixatin by NH<sub>4</sub>
<sup>+</sup>, while mean dark enhancement ratios (NH<sub>4</sub>
<sup>+</sup>rates: seawater rates) exceeded 2.3 for zooxanthellae from anemones unfed for 1-6 weeks. Photoshynthetic rates of the isolated algae declined with starvation. V<sub>D</sub>: V<sub>L</sub>, and index which includes both dark NH<sub>4</sub>
<sup>+</sup>enhancement and photosynthesis, increased markedly with time since feeding. Three of four field samples of A. pallida yielded zooxanthellae with dark enhancement ratios similar to those of fed laboratory populations; V<sub>D</sub>: V<sub>L</sub>values were somewhat higher. Symbionts from anemones collected on a fourth date had a mean enhancement ratio of 2.88, and V<sub>D</sub>: V<sub>L</sub>values similar to those from laboratory anemones that had not fed for 1-2 weeks, indicative of increased N limitation.</p>