Sea bream (Sparus aurata) intensive larval rearing : effects of microalgae and phages addition on the performance of the larvae

Abstract

Two different experiments were carried out with Sparus aurata larvae. In the first, the effects of microalgae addition (Chlorella minutissima) in the rearing system on growth performance (total length and wet weight), quality (% deformities) and survival of the larvae during the first 60 days post hatching were evaluated. Also, the ontogeny of the endogenous antioxidant defenses (superoxide dismutase, glutathione reductase, glutathione peroxidase, glutathione S-transferase and glutathione) and the pancreatic proteases (trypsin and chymotrypsin) was studied. Two groups of S. aurata larvae were reared until 60 days post hatch in a system with (pseudo-green water system, PGW) or without microalgae (clear water system, CW) and samples were taken at different developmental stages for the analysis of the enzymes. Additionally, at 120 days post hatching, survival and wet weight was evaluated. Up to our knowledge, this is the first time that the effects of green water on the antioxidant defences are studied. Significantly better growth performance was registered in the PGW group in terms of total length and wet weight. Differences between groups in the various antioxidant and digestive enzymes were discussed. The second experiment studied the effects of bacteriophages KVP40 addition to the larval rearing system (PH system) on the growth performance, quality and survival of the larvae during the first 120 days post hatch. Phages were added to the PH tanks at 4, 8 and 20 days post hatching. Differences, although not significant, in growth performance were detected between PH and CW groups.