FIG. 4.

Persistence of protozoan phylotypes during the whole sampling campaign and across down periods. Pipeline, water, and miscellaneous habitats are represented by P, W, and M, respectively; A, B, and C refer to the three farms. Gray boxes indicate that the water habitat could not be sampled during the down periods (see Materials and Methods). Free-living protozoa are represented by their phylotype numbers (Table 1). Long, horizontal boxes represent phylotypes detected on all consecutive sampling occasions, while short, horizontal boxes contain phylotypes which persisted between two consecutive rearing cycles.