Structure and temporal dynamics of a seaweed assemblage dominated bythe invasive lineage 2 of Asparagopsis taxiformis (Bonnemaisoniaceae, Rhodophyta)in the Alboran Sea

Abstract

Asparagopsis taxiformis is a rhodophycean species composed of six genetic lineages, one of which is considered a relevant inva-sive component of Mediterranean flora. This study describes seasonal changes in the structure and biomass of the native commu-nity associated with A. taxiformis on the coast of Granada (southern Spain). The native community was represented by 18 Rhodo-phyta, 3 Chlorophyta, and 4 Ochrophyta species. Biomass was dominated by A. taxiformis and Halopteris filicina. In January, A. taxiformis represented only 16% of the whole community biomass, but 2 months later, more than 90% of the community biomass was formed by the invasive species. During the study period, species richness, the Shannon diversity index, and species evenness showed low and generally stable values. Given that A. taxiformis gametophytes are present throughout the year, they likely pose a constant stress to the development of the native community. This survey provides baseline information on the macroalgal commu-nity structure, which may be useful to further studies on the actual impact of the invasive lineage of A. taxiformis