For the bioassessment of tropical marine ecosystem, a survey of protozoa colonizing artificial substrate was conducted in the coastal waters of northern Bay of Bengal, Bangladesh. Protozoan samples were collected using glass slides from 1 and 2 m water depths at time intervals of 3, 7, 10, 14, 21, and 28 days during winter and monsoon seasons. Thus, the colonization processes of protozoa were assigned into three stages namely the initial (3 days), transitional (7 days), and equilibrium stages (10–28 days) at two depths in two seasons. Regression analyses demonstrated that the colonization dynamics of protozoa were well fitted to the MacArthur-Wilson model and logistic equation. Species richness reached equilibrium after 10–14 days and species abundance was maximum at a depth of 1 m. These results suggest that samples of protozoa can be collected at 1 m depth in winter season for monitoring the ecological health of tropical marine ecosystems.

The temporal variation in the taxonomic distinctness of biofilm-associated diatom microflora within the colonization process was studied in coastal waters of the Yellow Sea, northern China from May to June 2014. Samples were collected at depths of 1 and 3 m, using glass slides as an artificial substratum. The colonization dynamics of diatom microflora showed similar species composition at both depths. In the young communities (1–7 days), the taxonomic patterns showed high variability compared with those in the mature ones (10 days and more). However, taxonomic distinctness indices at the two depths differed during early stages (e.g. 1–3 days). The taxonomic diversity (Δ) represented a high variability (coefficients of variation >10%) over all colonization periods, whereas the taxonomic distinctness (Δ*), average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) showed high stability (coefficients of variation <10%) after 7 days. Based on these findings, we suggest that the exposure time of more than 7 days may be sufficient to identify the taxonomic distinctness of biofilm-associated diatom microflora for both community research and monitoring programmes in marine ecosystems.

Biofilm-dwelling ciliates are a primary component of a biofilm, and play an important role in the functioning of microbial food webs by mediating carbon and energy flux into benthos from plankton. The carbon flux of biofilm-dwelling ciliates was studied at different trophic-functional levels within the colonization process in coastal waters of the Yellow Sea, northern China from May to June 2015. Samples were collected, using a glass slide method, at the time intervals of 1, 3, 7, 10, 14, 21 and 28 days from depths of 1 and 3 m. The carbon biomass of both total ciliates and all trophic-functional groups increased following the logistic growth curve model. During the whole colonization period, the bacterivores and non-selectives were generally the primary contributor to the carbon flux in young samples (<14 days), while the algivores and raptors predominated mature samples (14–28 days) at both depths. In terms of mature samples, however, the non-selectives and algivores were the primary contributors at a depth of 1 m, while the raptors accounted for primary contributions to the carbon flux at a depth of 3 m. Although the times to 50% maximum carbon biomasses were generally ranged 24 days at both depths, the maximum carbon biomasses were significantly higher at depth of 3 m than at 1 m. These results may provide useful information for ecological research on carbon flux from plankton to benthos in marine ecosystems.

The colonization dynamics in trophic-functional structure of biofilm-dwelling ciliate fauna were studied using two methods based on an artificial substratum in Korean coastal waters of the Yellow Sea during April 2007. Polyurethane foam enveloped slide (PFES) and conventional slide (CS) systems were used to collect ciliate samples at a depth of 1 m. The ciliate fauna represented similar colonization dynamics in trophic-functional patterns that were driven mainly by the algivores, bacterivores and non-selectives in both systems. Simple trophic-functional patterns (e.g. algivores and non-selectives) occurred within the ciliate fauna at the initial stage (1–3 days), while complex patterns (e.g. algivores, non-selectives and bacterivores) were established at the transitional (5–7 days) and equilibrium (9–19 days) stages. However, the time in which ciliate fauna reached a stable trophic-functional pattern was shorter in the PFES than in the CS system. Among four trophic-functional types, the algivores and bacterivores significantly fitted the MacArthur-Wilson and logistic models in colonization and growth curves in both systems, respectively. Furthermore, the species richness and diversity of algivores and bacterivores were significantly higher in the PFES system than in the CS. These results suggest that the PFES system was more effective than the conventional slide method for a colonization survey on trophic-functional patterns of biofilm-dwelling ciliate fauna in marine ecosystems.

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.