Monitoring Biolog patterns and <i>r/K</i> ‐strategists in the intensive culture of <i>Artemia</i> juveniles

Artemia juveniles were cultured under intensive conditions in three series of six tanks at different times. Both plate counts and Biolog GN microtitre plates were used to monitor the microbial community. Repetitions of the Artemia cultures in time revealed significant differences in Biolog patterns and bacterial counts, showing that normal culture practices, including chlorination of the sea water, does not allow control of the associated microbial community. However, the similarity among the Biolog fingerprints of all 18 tanks as determined by the Pearson correlation coefficient was always high. Both observations together indicate that the microbial community which colonizes the culture tanks seems to be determined by both deterministic factors (e.g. salinity, temperature, oxygen concentration, composition of the feed) and stochastic factors (micro-organisms still present in the sea water after chlorination, on the walls of the culture tanks or in the air around the culture tanks). When a high proportion of microbial r-strategists was present in the water at the beginning of the Artemia culture, the smallest differences in Biolog patterns among the tanks of one series throughout the culture period were observed. A parallelism between Artemia rearing success, functional fingerprint of the bacterial community and the proportion of r-strategists present, was observed. This suggests an important role of the bacterial community in the overall Artemia rearing success.