Taxonomy.- Intrageneric differences in cystocarp structure in Gelidium and Pterocladia.- Seaweed resources.- Worldwide distribution of commercial resources of seaweeds including Gelidium.- Ecology and management.- Production ecology of Gelidium.- Biological criteria for the exploitation of the commercially important species of Gelidium in Spain.- Gelidium pristoides in South Africa.- Ecological-physiology.- Field studies and growth experiments on Gelidium latifolium from Asturias (northern Spain).- Photosynthesis of Gelidium sesquipedale: effects of temperature and light on pigment concentration, C/N ratio and cell-wall polysaccharides.- Physiological basis for the cultivation of the Gelidiaceae.- Cultivation.- Gelidium cultivation in the sea.- Spray system for re-attachment of Gelidium sesquipedale. (Clem.) Born. et Thur. (Gelidiales: Rhodophyta).- Artificial sporeling and field cultivation of Gelidium in China.- General principles of on-shore cultivation of seaweeds: effects of light on production.- Agars and utilization.- Chemical structure and physico-chemical properties of agar.- Agars from Chilean Gelidiaceae.- Agar and agarose biotechnological applications.- Biotechnology.- Genetic alleviation of the self-fertilization complication when hybridizing monoecious Gelidium vagum.- Actual, potential and speculative applications of seaweed cellular biotechnology: some specific comments on Gelidium.- Concluding remarks.