Past and present of Fucales from shallow and sheltered shores in Catalonia

Abstract Historical information on marine organisms needs to be incorporated to develop effective management plans and conservation targets. In the Mediterranean Sea most species of brown seaweeds of the order Fucales are threatened or endangered and need protection. Here we merge data on historical and current records to create the first reference dataset on past and present distributions of Fucales from shallow and sheltered shores of Catalonia (NW Mediterranean Sea). Most Cystoseira sensu lato populations were found in the northern shores, where the most suitable environments exist. Carpodesmia mediterranea and Cystoseira compressa are far more abundant in exposed than in shallow, sheltered shores. Populations of most of the taxa (i.e. Carpodesmia crinita, Treptacantha elegans, T. sauvageauana, T. barbata f. aurantia) have suffered an important regression and two taxa have apparently become locally extinct (Cystoseira foeniculacea, Treptacantha barbata f. barbata). Carpodesmia caespitosa is still widespread in sheltered environments from the northern shores and a previously unreported taxon has been found (T. ballesterosii var. tenuior). Our regional-scale study makes available a solid, comprehensive baseline for future monitoring and application of conservation measures for the several threatened species of Fucales.