Figure 1. Map of the Grotta Grande del Vento-Grotta del Fiume complex of the Frasassi caves.

Black circles in main map mark sample collection sites. Geochemistry data have been reported earlier by [17]. Predominant biofilm clade determinations are based on FISH results [15], except for those marked with *, which were identified based on morphology [14]. bdl = below detection limit. Base map courtesy of the Gruppo Speleologico CAI di Fabriano.