Effects of Natural and Anthropogenic Stressors on Fucalean Brown Seaweeds Across Different Spatial Scales in the Mediterranean Sea

Algal habitat-forming forests composed of fucalean brown seaweeds ( Cystoseira , Ericaria and Gongolaria ) have severely declined along the Mediterranean coasts, endangering maintenance essential ecosystem services. Numerous factors determine loss these assemblages operate at different spatial scales, which must be identified to plan conservation restoration actions. To explore critical stressors (natural anthropogenic) that may cause habitat degradation, we investigated (a) patterns variability in percentage cover (abundance) three scales (location, forest, transect) by visual estimates or photographic sampling identify relevant variation, (b) correlation between semi-quantitative anthropogenic stressors, individually cumulatively (MA-LUSI index), including natural (confinement, sea urchin grazing), functional groups (perennial, semi-perennial) forest scale. The results showed impacts from mariculture urbanization seem main affecting species. In particular, while mariculture, urbanization, cumulative stress negatively correlated with perennial species, same were positively semi-perennial compressa C. subsp. pustulata . Our indicate human can fragmented heterogeneous marine habitats, thus stressing need carefully considering scale-dependent ecological processes support restoration.