1. Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are key
structural lipids and their dietary intake is essential for brain
development of virtually all vertebrates. The importance of n-3 LC-PUFA
has been demonstrated in clinical and laboratory studies, but little is
known about how differences in availability of n-3 LC-PUFA in natural
prey influence brain development of wild consumers. The availability of
n-3 LC-PUFA in the prey communities is driven by primary producers and
it is therefore distributed heterogeneously, but predictably across
ecosystems, being higher in aquatic than in terrestrial food webs.
Consequently, the numerous consumers foraging on the interface of
aquatic and terrestrial food webs can differ substantially in their
intake of n-3 LC-PUFA, which may lead to in brain development, yet, this
hypothesis still remains to be tested.
2. Here we use the previously demonstrated shift towards higher reliance
on n-3 LC-PUFA deprived terrestrial prey of native brown
troutSalmo trutta living in sympatry with invasive brook
troutSalvelinus fontinalis to explore this hypothesis.
3. We found that the content of n-3 LC-PUFA in muscle tissues of brown
trout decreased with increasing consumption of n-3 LC-PUFA deprived
terrestrial prey. Brain volume was positively related to content of the
n-3 LC-PUFA, docosahexaenoic acid, in muscle tissues of brown trout.
4. Our study thus suggests that increased reliance on low quality diet
of n-3 LC-PUFA deprived subsidies from terrestrial food web can have a
significant negative impact on brain development of wild trout. These
findings provide the first evidence of an intra-specific link between
n-3 LC-PUFA content in natural prey and brain size of wild vertebrate
consumers.
5. Ongoing global change is predicted to reduce the availability of
dietary n-3 LC-PUFA across food webs. Therefore, our findings emphasise
the need for further research on how wild consumers adapt to the
shortage of dietary n-3 LC-PUFA in order to maintain optimal development
and functioning of their brain, which is crucial for their fitness.
Linking brain size in wild stream-dwelling brown trout with dietary supply of omega-3 fatty acids