The brown alga Rugulopteryx okamurae: Insights into epifaunal diversity across marginal populations in Gran Canaria

Abstract

Biological invasions pose significant threats to biodiversity, primarily through the depletion of natural resources and the disruption of local ecosystems. Our study focuses on Rugulopteryx okamurae (E. Y. Dawson) I·K. Hwang, W.J. Lee, and H.S. Kim, an invasive alga proliferating in the Macaronesia and Mediterranean regions. This research examines the epifaunal assemblages associated with R. okamurae across eastern and northeastern zones in Gran Canaria, Canary Islands. A total of 11,398 individuals from 63 species within five taxonomic groups were collected, with Arthropoda dominating the samples (88.68 % of the overall abundance), particularly the amphipods Apohyale perieri and A. stebbingi. Significant differences in species richness and individual abundance were observed between populations from San Cristóbal, Jinámar and Ojos de Garza. The central populations exhibited the highest species richness, while the northern populations showed the lowest. Multivariate analyses revealed distinct community compositions between the edge and central populations, underscoring the invasive alga's capacity to support diverse and abundant epifaunal assemblages. Moreover, R. okamurae demonstrated remarkable dominance in the study area, achieving total coverage of up to 100 % at certain sampling sites. This extensive coverage highlights the alga's ability to sustain a rich and varied epifaunal community, characterized by both species abundance and high biodiversity. The findings emphasize the need for targeted conservation and management strategies to mitigate the spread of R. okamurae and protect local biodiversity from further disruption.