Use of single cell detritus (SCD) produced from Laminaria saccharina in the feeding of the clam Ruditapes decussatus (Linnaeus, 1758)

Abstract This study analyses the food value for bivalve mollusc seed of single cell detritus (SCD) from Laminaria saccharina , produced in accordance with the technique developed by Perez Camacho et al. [Perez Camacho, A., Salinas, J.M., Fuertes, C., Delgado, M., 2005. Preparation of single cell detritus from L. saccharina as a hatchery diet for bivalve mollusks. Mar. Biotechnol. 6, 642–649], which is based on the sequential action of two enzymes: endoglucanases and cellulases and two bacteria isolated in our laboratories: CECT 5255 and CECT 5256, which have high cellobiosic, proteolytic and alginolytic activities. Using this technique, L. saccharina meal is transformed in a suspension of algal cells and detritus of less than 20 μm in diameter, which can easily be filtered and digested by the bivalve molluscs. SCD from L. saccharina can replace between 80% and 90% of the live phytoplankton content in the feeding of R. decussatus , with growth rates equalling, and even surpassing, those resulting from live phytoplankton diets. If we then factor in the low sedimentation of this product, the lack of proliferation of pathogenic bacteria in the culture vessels (possibly as a consequence of the control exercised by the bacteria used in the SCE production process), and the high survival rates of the individuals used in our experiments, we can well conclude that SCD from L. saccharina is an effective complement to live phytoplankton diets for R. decussatus , its use reducing the need to produce phytoplankton in industrial bivalve mollusc hatcheries by up to 90%. Similarly, the introduction of this food would also appreciably diminish operating costs in this kind of industry, where phytoplankton culture accounts for some 30% of total production costs.