The widespread decline of canopy-forming macroalgal assemblages has been documented in many regions during the last decades. This pattern is often followed by the replacement of structurally complex algal canopies by more simplified habitats (e.g., turfs or sea urchin barren grounds).

This paper described an unexpected range and depth range expansion of the fucoid Treptacantha elegans, a large Mediterranean brown macroalga, along the northern coast of Catalonia over the last two decades. The study unravels ecological and demographic traits such as population dynamics and genetic patterns to provide an integrated view of the current status and geographical expansion for this species.

The results show that fast-growing dynamics, early fertile maturity, and high turnover rate are the main competitive advantages that allowed the expansion. The authors highlight that the deeper and exposed populations of T. elegans constitute a single group across the Catalan coast, with little genetic differentiation among populations. It is hypothesized that this could be the result of a unique source of spread in the last decades from the Medes Islands No-Take Zone towards both southern and northern waters.

Medrano et al. (2020) Ecologocial traits, genetic diversity and regional distribution of the macroalga Treptacantha elegans along the Catalan coast (NW Mediterranean Sea). Scientific Reports 10:19219.