Data from: Regulation of fatty acid composition related to ontogenetic changes and niche differentiation of a common aquatic consumer

Fatty acids (FAs) are key nutrients for fitness which take part in
multiple physiological processes over the ontogeny of organisms. Yet, we
lack evidence on how FA nutrition mediates life-history trade-offs and
ontogenetic niche shifts in natural populations. In a field study, we
analyzed ontogenetic changes in the FAs of Eurasian perch (Perca
fluviatilis L.), a widespread fish that goes through ontogenetic
niche shifts and can have high individual niche specialization. Diet
explained most of the variation in the FA composition of perch dorsal
muscle over early ontogeny (28%), while the total length explained 23%,
suggesting that perch significantly regulated FA composition over early
ontogeny. Condition explained 1% of the remaining variation. 18:3n-3 (ALA)
and 18:4n-3 (SDA) indicated planktivory; 18:1n-7, benthivory; and 22:6n-3
(DHA), piscivory in perch diet. Conversely, perch regulated
long-chained polyunsaturated fatty acids (PUFAs), such as 20:5n-3 (EPA),
20:4n-6 (ARA) and 22:6n-3 (DHA) over ontogeny, emphasizing the role of
such FAs in early growth and sexual maturation. Adult perch increasingly
retained 16:1n-7 and 18:1n-9 suggesting higher energy storage in older
perch. Furthermore, differences in DHA availability in diet correlated
with intra-cohort differences in perch growth, potentially hindering the
overall use of benthic resources and promoting earlier shifts to piscivory
in littoral habitats. Overall, this study indicates that in addition to
diet, internal regulation may be more important for FA composition than
previously thought. Differences between FA needs and FA availability may
lead to life-history trade-offs that affect the ecology of consumers,
including their niche.