Primary site and initial products of ammonium assimilation in the symbiotic sea anemone Anemonia viridis

Invertebrates containing endosymbiotic dinoflagellate algae (zooxanthellae) retain excretory nitrogen, and many are able to take up ammonium from the surrounding seawater. However, the site of assimilation and role of nitrogen recycling between symblont and host remains unclear. In the present study, ammonium uptake by the symbiotic sea anemone Anemonia viridis (Forskael) was examined by following the pathway of assimilation using 15 N-enriched ammonium.