Hatchery production of bivalves requires unicellular algae-based feed. Producing the algae for feed can be costly, labour intensive, and tricky. In the future, biorefinery by-products may offer a viable alternative feed source, but further research is still needed.

During the process of converting macroalgae into biofuel, significant biomass waste occurs. By employing enzymatic saccharification (breaking sucrose down into glucose and fructose), the theory goes, this waste could be converted into a single-cell detritus product - and potentially fed to farmed bivalves, such as oysters.

With macroalgae for biofuels still in the early stages of development, the possibility of using biorefinery by-products is still some time off. Nevertheless, the idea does present an interesting direction for the development of microalgal feed – and potentially an additional source of revenue for biorefineries.

To test how well this biorefinery by-product can perform as a feed, Dr Stefano Carboni (University of Stirling) and fellow scientists put together six different diets, which they fed to juvenile oysters (Crassostrea gigas).

Alongside the single-cell detritus product (the biorefinery by-product feed), the team put together a natural detritus-based diet consisting of farmed sea-urchin digesta, and two microalgae-based diets, one mixed with 50 per cent of the urchin-based detritus, and the other with 50 per cent of the single-cell detritus.

They also tested a live microalgal diet and an algal paste diet, both of which are already commonly used as feed in the aquaculture industry.

Source: The Fish Site  // Original Article