An approach to determining homogeneity of body-size spectrum of biofilm-dwelling ciliates for colonization surveys

Body-size spectrum, as an inherent function of a community, has been considered as a feasible bioindicator for functional ecological research and global bioassessment. To determine the homogeneity of body-size spectrum of biofilm-dwelling ciliates in colonization surveys, a 1-month baseline study was conducted at two depths of 1 and 3 m in coastal waters of the Yellow Sea, northern China. The temporal variability in body-size spectrum of the ciliate communities represented a decreasing trend at both depths. The average body-size distinctness (Δz+) and variation in body-size distinctness (Λz+), which were proposed based on a trait hierarchy of body-size units, represented a high variability in the young samples (>10 days), but a low in the mature (10-28 days). The paired body-size distinctness measures (Δz+ and Λz+) showed a significant departure between young samples and the mature communities with an expected trait hierarchy of body-size spectrum. These results suggest that the paired body-size distinctness measures may be a useful indicator for determining the homogeneity of body-size spectrum in colonization surveys for biofilm-dwelling ciliates.