Biological diversity of the microbial film associated to the central-Mediterranean Dendropoma cristatum (Biondi, 1859) reefs.

Microbial films may provide physical and bio-chemical cues which positively affect the settlement dynamic of a variety of benthic marine organisms, driving the development of ecosystems. Also for the Mediterranean intertidal reef-builder Dendropoma cristatum (Biondi, 1859), biofilm maturity has been found to enhance the settlement pattern. However, the microbial diversity associated with these bioconstructions has never been described. This study investigates the D. cristatum reef bacterial assemblage composition and temporal evolution in two localities in the northwest of Sicily. Biological diversity of the reef-associated biofilm and of 3 progressively older biofims obtained on artificial surfaces exposed in the field was described by Automated Ribosomal Intergenic Spacer Analysis (ARISA). Out of 55 detected OTUs, only 6 were shared between the 2 localities. Hierarchical grouping of taxa abundance showed two major groups that separated the 2 localities. Within each group, reef-associated and experimentally obtained biofilms formed individual clades. SSU-rRNA NGS sequencing of the reef-associated biofilm is in progress. These data highlight high variability in biofilm composition at local scale and between development stages, possibly responsible for the progressive increase of settlement of the Mediterranean biogenic engineer Dendropoma cristatum.