title: Spatial variability in community composition on a granite breakwater versus natural rocky shores: lack of microhabitats suppresses intertidal biodiversity.
abstract: Strong differences have been observed between the assemblages on artificial reefs and on natural hard-bottom habitats worldwide, but little is known about the mechanisms that cause contrasting biodiversity patterns. We examined the influence of spatial attributes in relation to both biogenic and topographic microhabitats, in the distribution and composition of intertidal species on both artificial and natural reefs. We found higher small-scale spatial heterogeneity on the natural reef compared with the study breakwater. Species richness and diversity were associated with a higher availability of crevices, rock pools and mussels in natural habitats. Spatial distribution of certain grazers corresponded well with the spatial structure of microhabitats. In contrast, the lack of microhabitats on the breakwater resulted in the absence of several grazers reflected in lower species richness. Biogenic and topographic microhabitats can have interactive effects providing niche opportunities for multiple species, explaining differences in species diversity between artificial versus natural reefs.
authors.affiliation: Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile. Electronic address: moises.aguilera@ceaza.cl.
authors.forename: Moisés A
authors.initials: MA
authors.lastname: Aguilera
authors.affiliation: Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile.
authors.forename: Bernardo R
authors.initials: BR
authors.lastname: Broitman
authors.affiliation: Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile.
authors.forename: Martin
authors.initials: M
authors.lastname: Thiel
mesh_terms: D000818:Animals; D044822:Biodiversity; D005247:Feeding Behavior; D005399:Fishes / Q000145:classification / Q000502:physiology*; D007448:Invertebrates / Q000145:classification / Q000502:physiology*; D012822:Silicon Dioxide
chemical_list: C007886:granite; D012822:Silicon Dioxide
keywords: Artificial reefs; Biodiversity; Breakwater; Grazers; Microhabitats; Spatial heterogeneity