Microbial Conversion of Macroalgae into a Detrital Hatchery Diet

News source: National Research Institute of Fisheries Science, Japan
For further information: JARQ 33, 295-301, 1999, 2001-02-01

Breaking down Algae with Bacteria

At present, most aquaculture systems are based on the principle of the grazing food chain, and fish culture starts with the culture of unicellular algae as fish feed. However, the mass culture of unicellular algae is technically difficult and labor intensive. A large number of collections of macroalgae-decomposing bacteria were screened.

Selection of Bacterial Strains

One strain was found to have strong activity in decomposing macroalgae thalli to produce algal detrital particles in a completely cell-detached form, namely, single cell detritus (SCD). SCD displays three characteristics which make it suitable for feed for aquatic hatchery species: 1) The size of SCD is in the range of 2-14ƒÊm, which is similar to that of unicellular algae. 2) The cell wall components of SCD are partially degraded, which facilitates digestion. 3) Bacterial cells are attached to SCD, which modifies the algal detritus to protein-rich particles.

Single Cell Detritus As Hatchery Diet

The use of SCD as a potential hatchery diet instead of cultured algae was successfully demonstrated in feeding experiments using Artemia. The use of SCD diets in fish feeding regimes is an attempt to introduce the concept of the detrital food web to aquaculture systems. This could contribute to the development of sustainable fish nursery systems.

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