SS4.07 Lipids/Fatty Acids in Ecological Research
Date: Tuesday, June 11, 2002
Time: 11:30:00 AM
Location: Saanich
 
TurnerJP, Texas A&M University at Galveston, Galveston, USA, turnerj@tamug.tamu.edu
Rooker, J, R, Texas A&M University at Galveston, Galveston, USA, rookerj@tamug.tamu.edu
Worthy, G, A, University of Central Florida, Orlando, USA, gworthy@mail.ucf.edu
 
TRACING FOOD-WEB INTERACTIONS WITHIN SARGASSUM COMMUNITIES USING FATTY ACIDS
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Fatty acids were quantified for flora and fauna associated with floating Sargassum mats in the NW Gulf of Mexico. Producers and consumers associated with the mat community were collected using several gears (plankton nets, hook-and-line, purse seine) and samples of representative taxa were removed for biochemical analysis. Fatty acids were isolated using chloroform/methanol extractions and signatures were determined using gas chromatography. Long-chain fatty acids (LCFA) accounted for approximately 40% of the total fatty acid content. LCFA signatures of primary producers (phytoplankton, Sargassum, epiphytic algae) were different, suggesting the approach has promise for determining source(s) of organic matter in Sargassum communities. Moreover, LCFA signatures of consumer groups (invertebrates, juvenile fishes, top predators) were distinct, particularly for certain fatty acids (18:3w4, 20:4w6, 20:5w3, 22:5w3, and 22:6w3). Using LCFA signatures of producers and consumers, classification and regression tree analysis was used to delineate trophic pathways within Sargassum communities.