STUDYING TROPHIC ECOLOGY IN MARINE ECOSYSTEMS USING FATTY ACIDS: A PRIMER ON ANALYSIS AND INTERPRETATION

Fatty acids (FA) represent a large group of molecules that comprise the majority of lipids found in all organisms. Their great diversity, biochemical restrictions and, in some cases, unique origin among plants and animals has fostered a number of areas of research, ranging from assessment of animal nutrition and metabolism, to investigating trophic interactions and ecosystem structure. Over the past three decades, we have observed the use of FA develop from a potential tool for delineating food webs (Ackman and Eaton 1966) to a powerful technique for quantitative assessment of predator diets (Iverson et al. 2004). Studies that have compared the FA found in predator fat stores with those found in their prey have allowed both qualitative (e.g., Horgan and Barrett 1985; Smith et al. 1996; Raclot et al. 1998; Dahl et al. 2000, 2003; Falk-Petersen et al. 2004) and quantitative or semi-quantitative analyses of diet (Kirsch et al. 2000; Iverson et al. 2001b, 2004; Iverson and Springer 2002) and