You are here:
BIOMARKER LIPIDS IN RED TIDE (GYMNODINIUM BREVE) BLOOMS ALONG THE NORTHWEST FLORIDA COAST
Citation:
Leblond, J. D. AND P J. Chapman. BIOMARKER LIPIDS IN RED TIDE (GYMNODINIUM BREVE) BLOOMS ALONG THE NORTHWEST FLORIDA COAST. Presented at Symposium on Harmful Marine Algae in the U.S, Woods Hole, MA, December 5-9, 2000.
Description:
The ability to characterize phytoplankton communities and algal blooms using lipids as biomarkers requires knowledge of their distribution and taxonomic significance. Such an approach would have application, for example, in distinguishing and tracking certain dinoflagellates such as the toxic species Gymnodinium breve, which is responsible for red tide events in the Gulf of Mexico. To explore this possibility, the lipids of over forty laboratory-cultured dinoflagellates, including three different isolates of G. breve, and a number of representatives of other eukaryotic algal classes such as the Bacillarioiphyceae, Haptophyceae, and Raphidophyceae, have been examined for the presence of chemotaxonomically useful fatty acids and sterols. A dense bloom (over 20 million cells/L) of G. breve in the fall of 1999 in the near shore waters of the Gulf of Mexico from Destin to Pensacola in northwest Florida provided an opportunity to compare the lipids of the field-collected samples with those found in laboratory cultures.
Extracted lipids were fractionated into different classes (neutral, glyco-, and phospho-lipids) prior to conversion to gas chromatography/mass spectrometry (GC/MS)-amenable fatty acid methyl esters (FAMEs) and sterol-trimethylsilyl (TMS)/acetate derivatives. The bloom of G. breve was found to contain two principal 4-methyl sterols, (24S)-4a-methylergosta-8(14),22-dien-3b-ol (ED) and its 27-nor derivative (NED), recently described by Faraldos and Giner (1998). The bloom sample was also found to contain the highly unsaturated long chain fatty acid, octacosaoctaenoic acid (28:8), recently discovered in dinoflagellates by Mansour et al. (1999).
Characterization of free and esterified sterols from laboratory cultures of G. breve has confirmed the predominance of these two sterols. ED and NED were shown also to be the primary sterols of the closely related dinoflagellates, Gymnodinium mikimotoi and Gymnodinium galatheanum. The wider distribution of this sterol