| Abstract: | Enchytraeus albidus is a small euryhaline earthworm that is abundant in the supralittoral zone where it can be found in decaying seaweed. This species is readily mass‐cultured, and due to its relatively high contents of protein and polyunsaturated fatty acids (PUFAs), there has been a renewed interest in this species as an alternative source of valuable nutrients for fish feed. Here, we have investigated the influence of substrate salinity (0, 1, 2, 8, 15, 30 and 40 ppt) on reproduction, growth and nutrient content of worms. We found that intermediate salinities (8–15 ppt) of the substrate maximize biomass production as well as protein and PUFA contents of the worm tissue. In particular, we observed that the often used culturing of E. albidus in non‐saline growth medium resulted in low reproduction and biomass production. Increasing the salinity from 0 to 15 ppt resulted in a higher proportion of unsaturated fatty acids both in storage lipid and in membrane phospholipid fractions. |
