Reproductive biology of Gigartina skottsbergii (Gigartinaceae, Rhodophyta) from Chile

Reproductive phenology and spore viability were studied in a natural bed of Gigartina skottsbergii at the locality of Ancud, Chile. Monthly sampling of biomass and density disclosed a decrease of both parameters in time, from 40 g m−2 in June 1996 to 1 g m−2 December 1997 and from almost 4 thalli m−2 to 1 thallus m−2 in the same period, respectively. Mature reproductive structures, cystocarps and tetrasporangial sori, were observed over the whole study period. Greatest cystocarp densities occurred in October through February (16 to 29 cystocarps cm−2) and of tetrasporangial sori between July and October (66 to 88 sori cm−2). In both types of reproductive structures, sporulation is more frequent in winter and early spring. High mortality of carpospores and tetraspores was observed in laboratory experiments performed between June and September.