F. Lipschultz J. McClelland G.A. Piniak 2003 <p><span>The movement of nitrogen from zooplankton prey into the temperate scleractinian coral&nbsp;</span><i>Oculina arbuscula</i><span>&nbsp;and the anemone&nbsp;</span><i>Aiptasia pallida</i><span>&nbsp;was measured using&nbsp;</span>¹⁵<span>N-labeled brine shrimp. The efficiency with which prey nitrogen was incorporated into cnidarian tissues was species-specific.&nbsp;</span><i>O. arbuscula</i><span>&nbsp;with a full complement of zooxanthellae had an assimilation efficiency of nearly 100%, compared to only 46% for corals containing few zooxanthellae. In&nbsp;</span><i>A. pallida</i><span>, symbiont density had no effect, and nitrogen assimilation was 23 to 29%. In both species, the host retained the bulk of the ingested label. Complete digestion was rapid (&lt;4 h), as was the partitioning of the label between host amino acids and macromolecules. The label was primarily in the low-molecular weight-amino acid pool in&nbsp;</span><i>O. arbuscula</i><span>, where it remained for 30 h. A maximum of ca. 20% of the&nbsp;</span>¹⁵<span>N appeared in the zooxanthellae, where it was rapidly converted into macromolecules. Individual amino acids in&nbsp;</span><i>A. pallida</i><span>&nbsp;tissues were highly labeled with&nbsp;</span>¹⁵<span>N within 4 h and showed no subsequent enrichment with time; however, zooxanthellae amino acids became increasingly enriched over 30 h. Differences in&nbsp;</span>¹⁵<span>N enrichment among amino acids were consistent with known synthesis and transformation pathways, but it was not possible to discriminate between host feeding and de novo synthesis.</span></p> application/pdf 10.3354/meps262125 en Inter-Research Science Publisher Assimilation and partitioning of prey nitrogen within two anthozoans and their endosymbiotic zooxanthellae article