Growth of turbot (Scophthalmus maximus L.) during first feeding in relation to the proportion of r/K-strategists in the bacterial community of the rearing water

A first feeding experiment with turbot was arranged as a two factorial design with filtered vs. microbially matured water as one factor, and with vs. without microalgae added to the tanks as the other. Application of microbially matured water had a highly positive effect on the growth of the larvae from day 5 after hatching and onwards. Algal addition gave the greatest effect on size from day 12, although both factors were highly significant. A positive interaction effect of combining matured water with the addition of microalgae was also observed. The positive effects may be related to the observed delay in colonization of the larvae in the early stages of first feeding. Evaluation of the water microflora by criteria based on the degree of maturation showed a lower proportion of opportunistic (i.e., r-selected) bacteria in tanks with matured water containing microalgae. It is suggested that rearing of turbot larvae in microbially matured water to which microalgae are added will lower the proliferation of opportunistic bacteria on the mucosal surfaces of the larvae, with more viable and fast-growing larvae as the result. (C) 1999 Elsevier Science B.V. All rights reserved.