Vertical variability in taxonomic breadth of biofilm-dwelling ciliates in marine bioassessment surveys

Abstract To determine the effects of water depths on taxonomic breadth of biofilm-dwelling ciliates in marine ecosystems, (1-month) baseline survey was conducted in coastal waters of the Yellow Sea, northern China. Utilizing glass slides as artificial substrates, samples were collected at four depths of 1, 2, 3.5 and 5 m after a 14-day exposure period. Taxonomic patterns and taxonomic distinctness measures showed a significant difference among four water depths. Ellipse tests on the pairs of average taxonomic distinctness ( Δ + ) and variation in taxonomic distinctness ( Λ + ) demonstrated a vertical variability in taxonomic structure of the ciliate communities from 1 m to 5 m, with high levels at 1 and 2 m compared to those at the other two depths. These results suggest that water depth may significantly shape the taxonomic breadth of biofilm-dwelling ciliates, and that an optimal sampling strategy should be determined before monitoring surveys in marine ecosystems.