1 The microbial community of coral reefs: Biofilm  composition on artificial substrates under different  environmental conditions
Artificial reefs are used as tools for the restoration of degrading coral reefs by providingnew settlement substrates. The initial recruitment process consists of the formation ofmicrobial biofilms shortly after deployment. The aim of the present study is to comparebiofilm composition and development on artificial substrates at two different coral-reefsites. These locations differ in their environmental conditions, including their level ofanthropogenic impact. Substrate and seawater samples were collected four times duringthe first six months after deployment, using a new methodology termed 'tab-by-tab'.DNA was extracted, sequenced, and sorted for both prokaryotic (16s) and eukaryotic(18s) genes. No difference was found between the planktonic communities in the water,yet significant differences were observed in the biofilm communities on the structuresat the two sites. Moreover, differences were recorded in coral recruitment rates, whichare known to be affected by biofilm composition. Our findings suggest a potential roleof environmental conditions in the early biofilm stages (first few months), which in turnmay impact the succession and development of coral reef communities and the successof artificial reefs as restoration tools.