Bulk hydrogen isotope composition in seaweeds from Australia, Brazil and Argentina

CARVALHO, M.; SACHS, J.; DELLATORRE, F. G.; CARNEIRO, P. B. M.; GIBILISCO, P. E.; EYRE, B. D.

Gold Coast

Congreso; Golden Jubile; 2013

Australia Marine Science Association

Many studies have used carbon and nitrogen stable isotope composition of seaweeds to trace their use as a food sources in coastal ecosystems. In contrast, the bulk hydrogen stable isotope composition of seaweeds has not been investigated, with most previous papers dealing only with cellulose-nitrate extracts, which make only about 1% of seaweed dry weight. Here we report the bulk hydrogen isotope composition for seaweeds from widely different ecosystems: a tropical beach in Brazil, a temperate beach in Argentina, and a subtropical beach in Australia. In all cases, the hydrogen stable isotope values were very distinct between different taxonomic groups, with similar trends across different geographical locations. In particular, Ulva species had remarkably similar values irrespective of their origin. This could be useful to trace the fate of seaweed organic matter in coastal ecosystems, especially in cases of green tides, when Ulva species form massive blooms with negative consequences.