Influence of life history and seasonal hydrology on lipid storage in three neotropical fish species

The seasonal dynamics of energy (lipid) storage in three neotropical fish species with differing life histories were evaluated. Lipid content was substantially greater in the liver than in dorsal musculature of all three species. Two piscivores (Cichla temensis and Serrasalmus manueli) showed large, statistically significant seasonal fluctuations in liver lipid content. Liver lipid content increased during high water, through the falling water, and into the early dry season for both piscivores. Seasonal variation in dorsal muscle lipid content was large and statistically significant for C. temensis, but was small and non-significant for S. manueli. Cichla temensis appeared to ‘finance’ costs associated with reproduction by accumulating lipids during the falling-water period when migratory prey allowed the species to subsidize their energetic dynamics. Semaprochilodus kneri, a migratory algivore and detritivore, showed no significant seasonal variation in dorsal muscle lipid content and minimally significant seasonal variation in liver lipid content. Statistically significant effects of lipid content on dC was observed when tissue lipid content varied by >12%, while biological interpretation of food web statistics based on dC values appears robust to minor variations in lipid content. Nonetheless, when lipid content varied by larger amounts (e.g. >35% forC. temensis andS.manueli liver tissue) lipids appeared tohave a large potential effect on dC and food web statistics calculated from such measurements may have been biased. Surprisingly, even large variation in tissue lipid content did not affect dN. # 2006 The Fisheries Society of the British Isles