Linking Omega-3 Polyunsaturated Fatty Acids in Natural Diet with Brain Size of Wild Consumers
Abstract 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 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 differences in brain development, yet, this hypothesis remains to be tested. Here we use the previously demonstrated shift towards higher reliance on n-3 LC-PUFA deprived terrestrial prey of native brown trout Salmo trutta living in sympatry with invasive brook trout Salvelinus fontinalis to explore this hypothesis. 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. Our study thus suggests that increased reliance on low quality diet of n-3 LC-PUFA deprived subsidies can have a significant negative impact on brain development of wild trout. Our findings are important, because ongoing global change is predicted to reduce the availability of dietary n-3 LC-PUFA across food webs and we showed here a first evidence of how brain of wild vertebrate consumers response to scarcity of n-3 LC-PUFA content in natural prey.