Analysis of the vagile and sesile community of the rocky intertidal of Cazones, Veracruz, Mexico

The rocky intertidal of Cazones, Veracruz already has information on biological diversity; however, it is necessary to know the community structure under a quantitative approach. The objective of the present research was to characterize the biological community of the high, middle, and low intertidal zones at three sampling sites. At each site, two 20 m long transects were laid at the high, middle and low intertidal levels, and in each transect, two quadrants of 50 x 50 cm were placed every 5 m to estimate the percentage cover of sessile species and the abundance of vagile species; additionally, alpha diversity indices (species richness, dominance, and true diversity) were estimated, and multivariate analysis determined significant differences between the intertidal strips. A total of 110 species were registered, which are grouped into three kingdoms: Chromista, Plantae, and Animalia; the last-mentioned kingdom presented seven phyla, Mollusca was the most diverse with 22 species recorded. The community structure in the upper level was homogeneous and not very diverse in species, and dominance prevailed; bivalves, bernacles, and gastropods were the most conspicuous. Towards the middle and lower intertidal, the species richness was higher, and the community structure was heterogeneous; seagrasses and macroalgae presented higher coverage at sites 1 and 2 and decreased towards the lower level; at this site, the vagile community was dominant, characterized by the abundance of sea urchins and anemones. While in the middle and lower levels of site 3, the community was equitable and was characterized by presenting the highest number of species diversity; the main component of the sessile community were macroalgae. The structure of the intertidal communities and the significant differences found in this study coincide with those reported for other rocky shores.