Abstract

Monthly and bathymetric variation of biomass, reproductive phases and chemical characterization of soluble polysaccharides in a shallow subtidal Rhodymenia howeana population at La Herradura of Guayacan Bay, Coquimbo (Chile), has been monitored between July 1994 and August 1995. Overall productivity of the population did not change during the study period, although the wet weight increased significantly with depth. The species showed winter peaks in reproductive activity, whereas in summer the frequency of reproductive plants was near zero. Throughout the study period the tetrasporic phase predominated over gametophytic phases. The non-fibrillar polysaccharides of Rhodymenia howeana were evaluated seasonally. Samples were sequentially extracted with water, acid and alkaline solutions and the extracts analysed by total hydrolysis, gas-liquid chromatography and infrared spectroscopy. The total yield of the extracts was 5.3% in winter, while in spring and summer values were close to 30%. The highest yields were obtained in aqueous and alkaline media and correspond mainly to a polysaccharide mixture of a sulphated galactan type and neutral glucans.