Habitat complexity drives the turnover and nestedness patterns in a periphytic algae community

Abstract

Habitat complexity drives aquatic community attributes, including the beta diversity components. We tested the hypothesis that community diversity, richness and density are higher on complex artificial substrates than on simple ones. Additionally, we hypothesised that the species occurrence would change from the simplest substrates to the more complex ones because complex habitats provide more niches and methods of exploiting environmental resources, thereby supporting larger numbers of organisms. We expected that the periphytic community would present a nestedness pattern when considering the quantitative index and turnover for the qualitative index. The effect of habitat complexity on the beta diversity was mediated by the relative species abundances. The periphytic algae density was higher on the complex substrates, but contrary to our expectations, the species richness and diversity did not increase on the complex substrates. Based on our findings, we suggest that habitat complexity can play a crucial role in structuring beta diversity patterns. However, we highlight that the responses of species turnover and nestedness to the variation in habitat complexity contrasted with the abundance and species occurrence approach. Additionally, we suggest that the species richness patterns in the periphytic community are independent of increases in the number of individuals.