AUTHOR=Orfanidis Sotiris , Rindi Fabio , Cebrian Emma , Fraschetti Simonetta , Nasto Ina , Taskin Ergun , Bianchelli Silvia , Papathanasiou Vasileios , Kosmidou Maria , Caragnano Annalisa , Tsioli Soultana , Ratti Stefano , Fabbrizzi Erika , Verdura Jana , Tamburello Laura , Beqiraj Sajmir , Kashta Lefter , Sota Denada , Papadimitriou Apostolos , Mahmoudi Ezzeddine , Kiçaj Hajdar , Georgiadis Konstantinos , Hannachi Amel , Danovaro Roberto 

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

JOURNAL=Frontiers in Marine Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.658417

DOI=10.3389/fmars.2021.658417

ISSN=2296-7745

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