Abstract
A previous study on the morphology of zooxanthellae, symbiotic dinoflagellates living inside marine invertebrates, has revealed that two distinct morphologies and motility patterns could be discerned. The motile type has an oval shape while the immotile type has a spherical shape. The model system Symbiodinium microadriaticum CCMP 829 was used to assess the possible implication of different nitrogen sources as inducers of these different motility patterns. S. microadriaticum was cultured in different NO3- and NH4+ concentrations and cell density and motility was estimated with a hemocytometer under a microscope. The ratio of motile to total cell number was then calculated. Results showed a proportional relationship between motility and NO3- concentration supplemented in the culture medium. These results, which suggest that NO3- is capable of inducing zooxanthellae motility, will be discussed in the light of a possible physiological change of zooxanthellae.
