Phenology and small-scale distribution of some rhodomelacean red algae on a western Mediterranean rocky shore

Abstract

Distribution and phenology of some filamentous species of Rhodomelaceae in the low littoral and shallow sublittoral zones of an exposed, western Mediterranean rocky shore were studied for 1 year. The spatial distribution of many species shows a pronounced small-scale (metres or tens of metres) variability. Boergeseniella fruticulosa was most abundant in spring and fertile (tetrasporangia only) in spring and summer. Polysiphonia flocculosa was most abundant in spring and summer and reproductive throughout the year. Polysiphonia opaca was most abundant in summer and fertile in spring–summer. Maximal vegetative development and reproduction of Lophosiphonia cristata were observed in summer; conversely, Polysiphonia ceramiaeformis and Polysiphonia subulata were best developed and mostly reproductive in winter and spring. Womersleyella setacea was the least abundant of the studied species and apparently reproduced only by vegetative growth and fragmentation. The reproductive phenology of the species investigated is generally in agreement with reports for other Mediterranean regions. The life history traits of most species are typical of seaweeds in which environmental factors directly govern the onset of the main activities of the organism by meeting the primary physiological needs (‘season responders’).