Cystoseira senu lato forests play a central role in marine Mediterranean ecosystems. Over the last decades, Cystoseira s. l. suffered from a severe loss as a result of multiple anthropogenic stressors. In particular, Gongolaria barbata has faced multiple human-induced threats, and, despite its ecological importance in structuring rocky communities and hosting a large number of species, the natural recovery of G. barbata depleted populations is uncertain.

This study used nine microsatellite loci specifically developed for G. barbata to assess the genetic diversity of this species and its genetic connectivity among fifteen sites located in the Ionian, the Adriatic and the Black Seas.

The results show high genetic structure was observed among the three seas, with and estimated dispersal distance per generation smaller than 600 m, both in the Adriatic and Black Sea. The authors state that this strong genetic structure likely results from restricted gene flow driven by geographic distances and limited dispersal abilities, along with genetic drift within isolated populations.

It is concluded that the presence of genetically disconnected populations at small spatial scales (<10 km) has important implications for the identification of relevant conservation and management measures for G. barbata: each population should be considered as separated evolutionary units with dedicated conservation efforts.

Riquet et al. (2021) Highly restricted dispersal in habitat-forming seaweed may impede natural recovery of disturbed populations. Scientific Reports 11:16792.