Unraveling diet and feeding histories of fish using fatty acids as natural tracers

Abstract

Unraveling feeding histories of fish is important if ecologists are to describe the benefits obtained from habitats. I tested if fatty acid (FA) mass and percentage composition can describe fish diet, in the presence of competing factors of feeding duration and temperature. To determine the relative effects of diet, feeding duration (representing temporal dynamics of tissue turnover), and temperature (representing metabolic influence) on fish FA composition, fish were fed two diets that differed in FA composition, protein, and fats and reared at two different temperatures (16 and 23 °C) for different feeding durations (7 and 42 days). Fatty acid composition (total FA matrix) of fish differed with manipulations of diet (FA data as %) and feeding durations (FA data as weights), but not with temperature. Saturated, monounsaturated (MUFA), and polyunsaturated (PUFA) FAs also showed predictable influences of diet and feeding duration, and saturated FA was influenced by an interaction of diet and temperature. The independent effect of diet and feeding duration suggest that FAs are a reliable tracer of dietary history (composition) and also the duration of feeding on different diets. Where differences in diet exist between habitats, the data suggest that FAs may be used to express movement to and from a habitat based.