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CARBON/NUTRIENT BALANCE IN RELATION TO BIOMASS PRODUCTION AND HALOGENATED COMPOUND CONTENT IN THE RED ALGA ASPARAGOPSIS TAXIFORMIS (BONNEMAISONIACEAE)

Authors

  • Leonardo Mata,

    1. Algae-Marine Plant Ecology Research Group, Center of Marine Sciences, Universidade do Algarve, 8005-139 Faro, Portugal
      School of Marine and Tropical Biology, James Cook University, Townsville, 4811 Queensland, Australia
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  • Helena Gaspar,

    1. Centro de Química e Bioquímica, DQB, Faculdade de Ciências da Universidade de Lisboa (FCUL), 1749-016 Lisbon, Portugal
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  • Rui Santos

    1. Algae-Marine Plant Ecology Research Group, Center of Marine Sciences, Universidade do Algarve, 8005-139 Faro, Portugal
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  • Received 12 November 2010. Accepted 1 June 2011.

Abstract

We tested how the availability of carbon and nitrogen determines both the production of Asparagopsis taxiformis (Delile) V. Trevis. and content of the two major halocarbons, bromoform and dibromoacetic acid. The halogenated secondary metabolites of Asparagopsis species are particularly interesting from an applied perspective due to their remarkable antimicrobial activity. Terrestrial ecologists named the relationship between resources and secondary metabolites as the carbon (C)/nutrient balance (CNB) hypothesis. This relationship was tested both in the laboratory, with a factorial analysis using different concentrations of total ammonia (TAN) and dissolved inorganic carbon (DIC), and in an integrated aquaculture system where TAN and DIC fluxes of fish effluent were manipulated. The total C/N content of A. taxiformis biomass cultivated in laboratory was highly significantly linearly related to the content of both halocarbons, as predicted by the CNB hypothesis. A. taxiformis cultivated at low levels of carbon and high levels of nitrogen (N) (lowest C/N ratio) had the lowest content in both halogenated metabolites. Increased availability of CO2 in the medium resulted in a general higher halocarbon content in the biomass, even though the effect was only statistically significant for bromoform at high levels of N. The farm experiments supported the results of the laboratory experiments. DIC fluxes had the highest effect on the production of both bromoform and biomass, as shown by multiple regression analysis. In A. taxiformis integrated aquaculture, C, rather than N, is the most important factor affecting the production of biomass and of valuable halocarbon secondary metabolites.

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