SPATIAL AND TEMPORAL VARIATION IN MARINE BACTERIOPLANKTON DIVERSITY AS SHOWN BY RFLP FINGERPRINTING OF PCR AMPLIFIED 16S RDNA

We have applied a simple methodology based on restriction endonuclease digestion of the total bacterial and archaeal 16S rDNA amplified from sea water samples to compare the prokaryotic diversity present along a transect from coastal to offshore waters in the Mediterranean basin (from Barcelona to the Balearic Islands). Samples from the surface and deep-chlorophyll maximum (DCM) were obtained. Temporal Variation duri ng a short span was also investigated by repeating the sampling after 48 h. The patterns of digestion bands from the samples were compared t o detect major changes in the bacterial or archaeal groups present. Fo r bacteria the main difference was found between the free-living commu nity and that retained by the eukaryotic filter and assumed to be part icle attached. By contrast Archaea collected by the same means did not appear as a separate group. The other main variation was depth-relate d, with remarkably different communities at the surface, at the DCM, a nd a single sample taken at 400 m depth. On the other hand, the variat ion along the transect from the continental platform to an offshore (2 000 m maximum depth) station was relatively small. Temporal (48 h) and small scale spatial (a few km) variation was minimal.