Offspring of marine amphipods Gammarus locusta exclusively cultured with vegetable by-products can yield omega-3 LC-PUFA through trophic upgrading

The growing demand for sustainable aquafeeds underscores the need for new lipid sources that can reduce the use of fish meal and fish oil to deliver important fatty acids (FA). Amphipods, particularly Gammarus locusta, have emerged as promising candidates given their nutritional value and ability to thrive on plant-based diets and still yield omega-3 long-chain (LC) polyunsaturated FA (PUFA). In this study, G. locusta was cultured from hatching to sexual maturity under controlled conditions and supplied with mono-specific diets of vegetal by-products (carrots, green beans, and peas), with Ulva sp. being used as a control diet. After reaching sexual maturity, offspring and adults were collected for FA analysis using gas-chromatography-mass spectrometry.Despite the absence of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the vegetable diets, adults and offspring of G. locusta exhibited these long-chain n-3 PUFAs in their FA profile. When compared to their wild conspecifics, results revealed a clear separation between the FA profile of wild and cultured specimens, with adults of G. locusta supplied with green beans presenting the highest levels of DHA (0.49 ± 0.02, µg FA per mg of amphipod DW), surpassing those of wild adult conspecifics and their offspring.This study highlighted the potential of G. locusta as an emerging aquafeed ingredient, capable of converting low-value plant by-products into a nutrient-rich biomass, reducing dependence on traditional marine bioresources and supporting the development of more resilient and sustainable aquaculture systems.