Abstract
Mooring lines of floating offshore wind turbine (FOWT) provide a substrate for diverse biofouling species, thus ultimately influencing both ecological dynamics and their own structural performance. This study presents an analysis of spatial and temporal variations in community composition, coverage and thickness from the surface to the seabed through a four-year monitoring of biofouling development on two mooring lines of the FLOATGEN prototype. Along these lines, three distinct biofouling zones were identified with hard-bodied species dominating the water surface, mobile organisms prevalent at intermediate depths and soft-bodied species in deeper regions. Over time, biofouling coverage and thickness increased in deeper sections of the mooring lines, reflecting a progressive shift in community structure. A significant association was observed between fouling class (hard or soft), coverage and thickness, particularly in relation to depth. These results contribute to a better understanding of biofouling dynamics on floating offshore structures and underscore the need for reliable and standardized monitoring methods.