Ciliates are a primary component of the periphyton microfauna and play a crucial role in the functioning of microbial food webs. Seasonal variation in community structures of periphytic ciliate communities was studied, using glass slides as an artificial substratum, during a 1-year cycle (August 2011–July 2012) in coastal waters of the Yellow Sea, northern China. Samples were collected monthly at a depth of 1 m from four sampling stations. A total of 144 ciliate species representing 78 genera, 43 families, 17 orders and eight classes were recorded. Among these species, 31 distributed in all four seasons, while 11, 11, 13 and two forms occurred only in spring, summer, autumn and winter season, respectively. The species number and total abundance peaked in spring and autumn, with minimum values in winter. Ciliate community structures differed significantly between seasons, and were significantly correlated with the changes in environmental variables, especially temperature, pH, dissolved oxygen (DO) and the nutrients. Of 36 dominant species (top 15 ranked contributors in each season), nine (e.g. Pseudovorticella paracratera, Trochilia minuta and Zoothamnium sp.) were significantly correlated with pH, DO or nutrients. Species richness, evenness and diversity measures were significantly correlated with temperature, pH, DO or soluble reactive phosphates. Results demonstrated that periphytic ciliates exhibited a clear seasonal variation in community structures in response to environmental conditions and potentially might be used as a robust bioindicator for assessing environmental quality status in coastal waters.

Temporal variations in the taxonomic relatedness of periphytic ciliate microfauna during colonization periods were studied in coastal waters of the Yellow Sea, northern China, from May to June 2010. Samples were collected at two depths of 1 and 3 m, using glass slides as artificial substrates. The colonization dynamics of ciliate microfauna on the slides revealed similar patterns in species composition at both depths. In the immature communities (1–7 days), the taxonomic patterns showed high variability compared to those in the mature ones (10 days and more). However, taxonomic relatedness parameters at the two depths differed during early stages of colonization (e.g. 1–3 days). Taxonomic diversity (Δ) was subject to high variability (coefficients of variation >10%) in both immature and mature communities, whereas taxonomic distinctness (Δ*), average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) showed high stability (coefficients of variation <10%) during the colonization times of 3–21 days. These findings suggest that 3–21-day exposure times are sufficient to detect the taxonomic distinctness of periphytic ciliate microfauna at water depths of 1–3 m for the purposes of ecological research and monitoring of marine ecosystems.

Colonization dynamics of periphytic ciliate communities were studied in coastal waters of the Yellow Sea, northern China from May to June 2010, using an artificial substratum. Samples were collected at two depths of 1 and 3 m. The temporal patterns of ciliate colonization had similar dynamics and were fitted to the MacArthur–Wilson and logistic models in colonization and growth curves at both depths, respectively. The ciliate communities reached equilibrium in species composition within at least 10-days exposure time. However, they differed in both structural and functional parameters between the two layers, despite similar species composition. The species diversity, evenness, the colonization rate (G) and maximum abundance (Amax) were distinctly higher, but the time for reaching 90% equilibrium species number (T90%) was shorter at the depth of 1 m than those at a deeper layer. Results suggest that it is an optimal strategy to collect the ciliate communities within shorter exposure time at 1 m for ecological research and a monitoring programme in marine ecosystems.

Taxonomic diversity and temporal patterns in abundance of periphytic ciliate communities across taxonomic levels were studied to monitor water quality in Korean coastal waters during April 2007. Specifically we compared two methods based on an artificial substrate (glass slide): the polyurethane foam enveloped slide (PFES) and the conventional slide (CS) systems. The results demonstrated that: (1) the colonization patterns of the ciliate communities at all taxonomic levels showed a lower variability in the PFES system than those of the CS system; (2) The taxonomic diversity (Δ) and taxonomic distinctness (Δ*) were significantly higher in the PFES system than those in the CS system; and (3) all four taxonomic diversity/distinctness indices represented lower variability in the PFES system than those of the CS samples. These findings suggest that the PFES system is more effective than the CS system for measuring the colonization patterns and taxonomic distinctness parameters that are increasingly used as potential indicators of water quality. This conclusion supports our previous suggestion that the PFES system is a better tool than the CS system for monitoring water quality in the marine ecosystem, using periphytic ciliates.

Structural parameters of periphytic ciliate communities on a modified substrate were studied in Korean coastal waters during the period August–November 2007. In order to reduce the strong disturbances from tidal current and circulation in marine ecosystems, a modified slide method, named the polyurethane foam enveloped slide (PFES) system, was used to host ciliate communities. A total of 37 ciliate species, about half of which belong to the orders Hypotrichida and Cyrtophorida, were identified using living observation and silver impregnation method with this system. The sessile ciliates belonged to the orders Peritrichida and Suctorida, while the motile forms were represented primarily by the species of the orders Hypotrichida, Cyrtophorida and Pleurostomatida. The species diversity and evenness were significantly higher in the PFES system than those on the conventional slides (paired t-test: t = 2.384, 2.415; P < 0.05). Multivariate analysis revealed that the ciliate communities from both sampling systems had similar species composition, but represented significant differences in species distribution and temporal dynamics mainly due to the most dominant peritrich Zoothaminium duplicatum, which overly colonized the conventional slides. Results suggest that the PFES system is more effective than the conventional slide method for periphytic ciliate colonization with high species diversity, evenness and sensitive temporal dynamics mainly due to the reduction of disturbances from tidal current and circulation in marine ecosystems.