Browsing by Author "UGARTE, R"

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    ALGAL LIFE-HISTORY STRATEGIES AND RESISTANCE TO DIGESTION
    (1987) SANTELICES, B; UGARTE, R
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    EXPERIMENTAL TANK CULTIVATION OF GRACILARIA-CHILENSIS IN CENTRAL CHILE
    (1992) UGARTE, R; SANTELICES, B
    Gracilaria chilensis was grown continuously in tanks over a 13-month period, changing the water only every 15 days, and adding CO2, air and nutrients. Biomass production was markedly seasonal, with a summer maximum of 100 g m-2 day-1 (wet) and a winter minimum of 10 g m-2 day-1. Average production was 4.1 kg m-2 year-1 (dry), fourfold greater than the production of wild beds. The material from tank cultivation contained 30-35% agar, as compared to 18% in wild G. chilensis. Epiphytism was the main problem in these cultures, and its control with chloride may reduce productivity by 40%. Pre-treatment of the water seems to be the best method to prevent epiphytes. The marked seasonality in biomass production suggests the need to change stock density, air bubbling frequency, levels of CO2 and nutrient enrichment, and harvest frequency from summer to winter. It was estimated that such adjustments could increase the productivity of this system to 6 kg m-2 year-1 of dry Gracilaria chilensis with an annual average agar yield of 30%.
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    PRODUCTION OF CHILEAN GRACILARIA - PROBLEMS AND PERSPECTIVES
    (1987) SANTELICES, B; UGARTE, R
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    THE ARRIVAL OF PROPAGULES OF MARINE MACROALGAE IN THE INTERTIDAL ZONE
    (1985) HOFFMANN, AJ; UGARTE, R
    The composition and abundance of macroalgal propagules contained in sea water arriving at intertidal rocky shores was estimated monthly at Pelancura, central Chile, from June to December, 1984. Samples from surface water and from water running off rocky platforms with mixed algal vegetation were cultured in laboratory conditions and examined for development of sporelings. Thirty eight macroalgal entities grew in the cultures, 75% of them with opportunistic life-styles. The total number of sporelings was similar in the surface water of sites separated by 300 m. Marked variability on composition and number of sporelings was, however, observed between samples taken simultaneously at one site and between different months, suggesting patchiness in the dispersal of propagules. Marked differences were established in the ratio run-off water/surface water in the number of sporelings, which could be related to the dispersal shadows of the various taxa. Sporelings of late successional algae showed marked spatial and temporal variations in number. Some taxa of opportunistic algae were characterized by the development of several thousand sporelings per litre of sea water while in others the number of sporelings was two or three orders of magnitude less, suggesting differences in reproductive effort.