Diversity and Distribution of Intertidal Cystoseira sensu lato Species Across Protection Zones in a Mediterranean Marine Protected Area

This study investigates the diversity and distribution of intertidal <i>Cystoseira sensu lato</i> (<i>s.l.</i>) species across different protection zones within the "Capo Gallo-Isola delle Femmine" Marine Protected Area (MPA) in the central Mediterranean Sea. Five <i>Cystoseira s.l.</i> species (<i>Cystoseira compressa, C. foeniculacea, Ericaria amentacea, E. brachycarpa</i> and <i>E. crinita</i>) were observed on the intertidal rocky shores, with varied abundances across the MPA's protection zones. <i>Ericaria amentacea</i> was the only species found in all zones, with a much higher cover percentage in the most protected area (zone A). However, its morpho-functional traits showed an inverse trend, with the largest thalli found in the moderately protected zone B and C. The remaining <i>Cystoseira s.l.</i> species were only found in zones B and C probably due to their wider area and greater habitat diversity compared to zone A. The presence of two non-indigenous species, <i>Asparagopsis taxiformis</i> and <i>Caulerpa cylindracea</i>, was observed exclusively in the less protected zones B and C. Our findings highlight the complex interactions between MPA protection levels and <i>Cystoseira s.l.</i> species conservation, with protection having, in some respects, a positive influence on selected <i>Cystoseira s.l.</i> species, indicating the importance of careful consideration in MPA design and management. Furthermore, this study provides a baseline for future monitoring of <i>Cystoseira s.l.</i> populations in light of ongoing environmental changes in the Mediterranean Sea.