Macroalgal responses to coastal urbanization: relative abundance of indicator species

This study aimed to evaluate and compare the intertidal macroalgae community from reef structures subject to different urbanization degrees. Samplings were made in 11 beaches from the Pernambuco coast, northeastern Brazil. The sites were classified according to the level of urbanization into three classes of increasing urbanization pressure: non urbanized (NU), in urbanization process (UP), and consolidated urbanization (UC). Macroalgae were identified in situ non-destructively. A total of 53 taxa were identified, 41 of these were macroalgae. Significant differences were observed in the composition of macroalgae according to the urbanization levels, with Palisada perforata , Gelidiella acerosa , and Caulerpa spp. dominating NU and UP sites, whereas Chondracanthus acicularis , Bryopsis sp., and Ulva spp. dominated UC sites. This work shows that urbanization can have a strong effect on the structure of rocky intertidal macroalgal assemblages and highlights some macroalgae species that can be used as bioindicators for assessing the impact of urbanization on coastal shores.