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Production of seaweeds in Chile has fluctuated between 74,000 and 322,000 wet metric tons/year during the last 14 years, involving different species of Phaeophyta and Rhodophyta. Among Rhodophyta, the most important harvested species include the carrageenophytes Sarcothalia crispata, Mazzaella laminarioides, Gigartina skottsbergii, Chondracanthus chamissoi, and the agarophytes Gracilaria chilensis and Gelidium lingulatum. Other less important taxa are Gel. rex, M. membranacea, Ahnfeltia plicata, Ahnfeltiopsis furcellata, Porphyra columbina, Callophyllis variegata, Mastocarpus papillatusand Chondrus canaliculatus. Chilean production comes mainly from wild stocks, as at present, cultivation on a commercial scale is restricted to Gra. chilensis. Total landings of Gracilaria currently stand at 120,000 wet tons. Large-scale cultivated biomass of this species, on the other hand, has been the result of a sharp increase in the number of farms, from less than 10 in 1982 to almost 322 in 1996. A basic understanding of key biological and ecophysiological aspects, as well as the availability of propagation methods, permitted the development of large-scale Gracilaria farming operations. However, during the cultivation process, new problems arose for the farmers, such as abrupt production decline, pests and pathogens. Similar key knowledge is lacking for other Chilean Rhodophyta, which creates a bottleneck that prevents the development of seaweed farming activities other than Gracilaria. This situation prevails in spite of the growing pressure on wild stocks triggered by an increase in the demand for raw material by the industry, with the obvious danger of over-exploitation and the resulting collapse of fisheries. Taking the above into consideration, an effort has been made in recent years to provide the basic knowledge necessary for the management and cultivation of some of the most valuable seaweed resources in Chile. Thus, the main objective of this contribution is to summarize the present situation of red seaweed cultivation in the country. We will address this issue by reviewing the landing statistics of these resources, followed by a summary of recent information that favours cultivation. These include propagation methods, culture conditions and techniques, product quality, pest management, strain selection and the diversification of seaweeds currently exploited in Chile.

The green seaweed Ulva reticulata used as co-culture species for monitoring the changes in toxic nitrogenous wastes in the shrimp culture system was found to efficiently remove ammonical nitrogen from 249.5 to 17.39 pmol nitrogen11 (94%). The nitrate nitrogen reduced from 28.39 to 24.21 pmol nitrogen 11 (5%) and nitrite nitrogen from 14.51 to 9.03 pmol nitrogen11 (22 %). The removal of total nitrogen from the aquaculture system was found to be 45 % when treated with seaweed. The concentration of toxic nitrogenous wastes was found to be always at a lower level in the integrated system when compared to the monoculture system. Seaweeds of economical importance can be used in aquaculture system to improve water quality and generate revenue for the industry.

Production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. This could replace fossil fuel-derived energy and reduce its environmental impacts, including global warming and acid rain. Although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through regulations, carbon taxes, and subsidies of biomass energy would make it cost competitive. Methane derived from anaerobic digestion is competitive in efficiencies and costs with other biomass energy forms including heat, synthesis gases, and ethanol. The objective of this paper is to review the results and conclusions of research on biomass energy conducted under the sponsorship of the gas industry with periodic co-funding from other agencies. The scope of this program was to determine the technical and economic feasibility of production of substitute natural gas (SNG) from marine and terrestrial biomass and organic wastes using anaerobic digestion as a conversion process. This work began in 1968 and continued until about 1990, ending as a result of low energy prices in the U.S. and reduced emphasis on renewable energy. For each of these feedstock categories, growth or collection (in the case of wastes), harvesting, conversion by anaerobic digestion, and systems and economic analysis were addressed. More recently the potential use of anaerobic digestion for stabilization and recovery of nutrients from solid wastes during space missions was studied with funding from NASA. The application of this process for that function as well as treatment of wastewater and waste gases generated during space missions is addressed.