Bio-mineralogy as a structuring factor for marine epibenthic communities

The mineralogical features of the substrate were generally considered a min or factor in structuring marine benthic communities. The aim of this work i s to verify whether the presence of quartz minerals in rock may explicate d ifferences, usually explained in terms of substrate roughness or other fact ors, in epibenthic communities. Laboratory tests on the hydroid Eudendrium glomeratum showed that its planulae settle preferentially on carbonatic, ra ther than quartzitic, substrates. To test the influence of quartz on establ ished communities, we analysed the species composition and quantitative str ucture of sublittoral sessile assemblages on different rocks in several loc alities of the Ligurian and Tyrrhenian seas. The observed differences appea red to be related to the presence of quartz in the substrate rock. The inte ractions between organisms and minerals (bio-mineralogy) might play a signi ficant role on benthic communities, affecting not only the initial colonisa tion, but also later assemblages. This potential role has been largely negl ected to date and further studies are needed to prove its importance.