Marine amphipods are a promising aquafeed ingredient for marine aquaculture. This potential is largely due to their natural levels of long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs), which are key for marine finfish and shrimp nutrition. Several amphipod species inhabit estuarine ecosystems and tolerate pronounced shifts in salinity, making them suitable candidates for large-scale production under natural conditions. However, to successfully mass-culture these organisms in coastal earth-ponds it is paramount to determine how salinity influences their fatty acid (FA) profile and identify optimal conditions for production. In the present study, we investigated the effects of three salinity levels (20, 25, and 30) on the FA profile of newly hatched Gammarus locusta reared until sexual maturity.
Newborn G. locusta were maintained under different salinity treatments for 40 days and fed with a commercial fish feed. Total lipid content and FA profiles of male and female specimens were determined using gas chromatography–mass spectrometry (GC-MS) and analysed through multivariate and univariate approaches. Overall, the FA composition of G. locusta was significantly influenced by salinity, with individuals reared at a salinity of 20 displaying distinct multivariate profiles compared to those at 25 and 30, regardless of sex. Although females exhibited increased total lipid content than males, amphipods maintained at a salinity of 20 showed higher levels of n-3 LC-PUFAs, including a higher concentration of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), than conspecifics cultured under the other salinities tested.
Our findings demonstrate that salinity plays a key role in shaping the FA composition of G. locusta. Rearing amphipods at brackish conditions enhances the synthesis of essential FAs, such as EPA and DHA, and promotes the accumulation of lipids, thereby improving their nutritional value. These results suggest that the use of specific salinity regimes in natural pond systems can optimize amphipods mass-production and make possible their use as a sustainable ingredient for aquafeeds.
This study was performed under project “BLUE BIOECONOMY PACT” (Project Nº. C644915664-00000026), co-funded by the Next Generation EU European Fund, under the incentive line “Agendas for Business Innovation” within Component 5—Capitalization and Business Innovation of the Portuguese Recovery and Resilience Plan (RRP), as well as project “PUFAPODS Merging blue and green food systems - Using marine gammarid amphipods supplied with plant food processing side streams to produce n-3 LC-PUFA” which is supported by FCT/MEC https://doi.org/10.54499/LA/P/0094/2020).