Abstract

Habitat complexity is one of the key drivers that structure biodiversity and is positively associated with species richness, density, and diversity. In this work, we assessed and compared the biodiversity of mobile macro-invertebrates in temperate rocky reefs of the South Pacific by using taxonomic (species richness, diversity, and evenness) and functional diversity indices (functional entities richness, functional redundancy, functional over-redundancy, and functional vulnerability). In the present study, we surveyed four giant kelp (Macrocystis pyrifera) beds with varying holdfast densities and vertical relief in the Biobio region of Chile. Mobile macro-invertebrates larger than 2.5 cm in total length were recorded using an underwater visual census for one year during four seasons. To calculate functional diversity indices, we measured five functional traits: body size, body shape, diet, adult motility, and burying capacity. Our results show that species richness, diversity, and evenness were highest in Laraquete (South of Biobio). Functional entity richness was highest in Llico and lowest in Penco (northern Biobio). Redundancy and functional over-redundancy were also highest in Laraquete. The Generalized Linear Mixed Models revealed differences in functional diversity indices between localities, driven by medium and high substrate environments (p < 0.05). Our study suggests that taxonomic and functional diversity have a positive relationship with substrate height and underscores the importance of habitat complexity in marine conservation efforts.