EXPERIMENTAL TANK CULTIVATION OF GRACILARIA-CHILENSIS IN CENTRAL CHILE
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1992
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Abstract
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%.