Abstract
Canopy-forming macroalgae are the main component in some of the most diverse and productive coastal habitats around the world. However, canopy-forming macroalgae are very sensitive to anthropogenic disturbances. In coastal urban areas, intertidal organisms are exposed to the interactive effect of several anthropogenic disturbances that can modify the community’s structure and diversity. Along the North-East Atlantic shores, many studies explored the effect of anthropogenic disturbances on canopy-forming macroalgae, but mainly focused on kelps and fucoids. However, along the intertidal rocky shores of the Atlantic coast of the Iberian Peninsula, the most abundant and frequent canopy-forming macroalgae belong to the family Sargassaceae. To explore the effect of urbanization on these intertidal canopy-forming species the diversity and assemblage structure of canopy species were compared between four urban and four non-urban shores in the north of Portugal. Intertidal canopy assemblages on urban shores were dominated by the non-indigenous Sargassum muticum that was the only canopy-forming species on three of the four studied urban shores. Canopy assemblages on all non-urban shores were more diverse. Moreover, stands of canopy-forming species on urban shores were always monospecific, while at non-urban shores multi-specific stands were common. Therefore, results suggest that urbanization reduces canopy´s biodiversity.
Highlights
Large perennial canopy-forming species are considered as good indicators of the ecological status of coastal habitats, because most of them are very sensitive to anthropogenic disturbances [2]
The contribution to percentage of dissimilarity of B. bifurcata, T. baccata and S. muticum was consistent among pair-wise comparisons of PERMDISP analysis indicated that the dispersion of samples did not contribute to the significant differences detected by the PERMANOVA analysis (F = 1.2, p > 0.05)
Despite the fact that species of the family Sargassaceae are very abundant and with ecological relevance along the Atlantic shores of the Iberian Peninsula, there is a lack of information about the effect of anthropogenic disturbances on their diversity, distribution or functioning
Summary
Canopy-forming macroalgae play a key role in the functioning of coastal ecosystems providing habitat and food for other organisms, sequestrating carbon and nitrogen from the environment, ameliorating the effect of waves and creating very diverse and productive coastal habitats [1]. Many efforts have focused on restoring the shores where canopy-forming species have been locally extinct [8]. Sargassaceae (i.e., most abundant and frequent intertidal canopy forming macroalgae belongs to the family genus Bifurcaria, Cystoseira, Sargassum and Treptacantha). Many studies explored the effect of anthropogenic disturbances such as pollution [11] or[10], urbanization [12] on canopy-forming species[12]. Eutrophication metal pollution [11] or urbanization on canopy-forming of the response to disturbance of the Sargassaceae intertidal canopy-forming species along the Atlantic. The main aim of this study was to structure of intertidal canopy-forming species between two areas characterized by different levels of compare the diversity and assemblage structure of intertidal canopy-forming species between two urbanization along the north coast of Portugal. Areas characterized by different levels of urbanization along the north coast of Portugal
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