sampling was conducted around the intertidal coast of the Islas Cíes, (NW Spain) with the goal of determining the variation of the shore landspace, based on vertical zonation profiles of sessile organisms in relationship with the Atlantic Ocean influence. The Western Coast is heavy wave beaten and the Eastern Coast is sheltered. Many species coexist in a limited intertidal space of the sheltered than in the exposed shores. The sheltered coast presents in this way, a mosaic structure of their organisms. On the other hand few species dominated the cliffs of the west coast. In this section, the upper intertidal limit of distribution was raised by the increased of humidity caused by the splash and spray. The winds also favoured the presence at the high littoral level of organisms such as brown algae, lichens and vegetation. Multivariate techniques detected differences in the communities between exposed and sheltered shores as well as between the two main islands. Distribution of species in the intertidal zone was related to the particular geomorphological feature of the coast, such as coves, points or exposed cliffs. Four different landscape intertidal patterns of vertical zonation were represented by each island face. The algae, Asparagopsis armata and Bifurcaria bifurcata characterized the sheltered North Island. Pelvetica canaliculata and Fucus spiralis had a greater presence in the sheltered side of the South Island. The fucoids were absent at the wave beaten shore. The lichens, Verrucaria maura and Caloplaca marina, and the Rhodophyta belt had a higher upper limit of distribution at the exposed sides of the North Island. Bare rock and the crust phase of Mastocarpus stellatus had a greater presence at the exposed side of the South Island.

A photographically sampling was conducted at Islas Cíes, NW, Spain with the goal of determinate the upper and lower limits of vertical distribution of sessile organisms on the intertidal rocky shore of this National Park. The response of the species to different Atlantic Ocean exposure was tested at west coast (exposed) and east coast (sheltered) of Islas Cíes. The sampling was made following a hierarchical spatial design. The contribution in the variation around the mean of the intertidal limits of each organism at diverse spatial scales in the rocky shore was estimated with Linear Mixed Effects Model with software R. The majority of the species were found to increase their upper limits in the exposed coast of the two islands. Several intertidal algae, mainly the fucoids, were absent at the exposed shore and this pattern could be influenced by excessive turbulence. The variation at large spatial scales was related to changes in the degree of exposure between islands. Physical characteristics and biological interactions accounted for the variability observed on the intertidal. The spatial heterogeneity introduces variability from very small to mid spatial scale. The species presented in the low intertidal have more variation at small scale (meter to tens of meters), and the organisms in the high intertidal vary their limits at medium scale (tens to hundreds of meters). The life cycle, adaptations, ecology and natural history of the intertidal organisms described in previous studies of Galician, Portuguese, and the British shores may explain the patterns found in Islas Cíes.