Improvements in the culture of Sparus aurata L. larvae in relation to the use of antibiotics, phytoplankton and rearing system

Abstract

Rotifers were enriched for 24 h with a lipid emulsion and the algae Nannochloropsis sp. Some of the rotifers were treated with antibiotics (chloramphenicol and oxolinic acid). Larval sizes were recorded initially, at day 7 and at the end of the experiment. Larval survival rates were estimated at the end of the experiment. Rotifers and larvae were analysed for lipid and moisture as well as the fatty acid profile of total lipids. The number of bacterial colonies from rotifer and larvae culture was also recorded. The best growth rate was found in larvae reared in a recirculating system with addition of phytoplankton and antibiotics, although no significant differences (P < 0.05) were apparent with the same treatment without antibiotics. Larvae reared in a flow-through system with phytoplankton showed the best survival rates, but larvae receiving rotifers treated with antibiotics showed the lowest survival rates. The n−3 HUFA levels in rotifers and larvae treated with antibiotics were significantly lower than those in treatments without these chemicals. The results of this study suggest that antibiotics should not be used indiscriminately in hatcheries as they may exert an adverse effect on larval cultures.