Colonization dynamics in trophic-functional patterns of biofilm-dwelling ciliates using two methods in coastal waters

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.

Influence of enumeration time periods on detecting community parameters of periphytic diatoms using an artificial substratum in coastal waters

Community parameters of diatoms have been used as useful bioindicators for bioassessment of both lentic and lotic systems. The influence of enumeration time periods on detecting community parameters of periphytic diatom assemblages within different exposure times was studied using an artificial substratum in coastal waters of the Yellow Sea, northern China, during the period May–June 2010. Samples were collected at a depth of 1 m, and were examined with different enumeration time periods. Enumeration time periods represented a significant influence on detecting the community features of periphytic diatoms, although no significant changes occurred in periphytic diatom community structure between two enumeration schemes (within 24 h and 24–48 h). The delayed enumeration (within 24–48 h) may result in the similarity of the communities being reduced 10–29%, and in species numbers decreasing and in abundance increasing with exposure duration, respectively. The diversity (richness, evenness and diversity of species) indices were significantly decreased in almost all samples with >10% standard errors at some exposure times by the delayed enumeration scheme. These results suggest that the delayed enumeration may have resulted in the species richness and individual abundance of periphytic diatoms significantly decreasing and increasing, respectively, and thus significantly affected the analyses of species diversity for assessing water quality in marine ecosystems.

Small-scale distribution patterns of two cirratulid species with a description of a peculiar early juvenile stage

An assemblage of cirratulids in a confined marine basin (Mediterranean Sea) was investigated at small spatio-temporal scales in an experiment in which artificial granules of expanded fire-clay were used as a bare substratum for colonization. Analysis of core samples of 3.5 l undisturbed natural sediments (source area) and equal volumes of artificial substratum (new settlement area), plunged into the sea bottom were carried out from May to July 2008 after 0, 15, 30 and 60 days.Caulleriella bioculatashowed the highest total mean density of 10.1 ± 5.8 N l−1in the natural sediment, and the lowest at 0.13 ± 0.08 N l−1in the artificial substratum, with a marked temporal decrease. Individuals were not strongly aggregated and were found in a deeper sediment layer. The density of largeCirriformia tentaculatawas 0.5 ± 0.3 N l−1, with individuals more aggregated and confined to shallower sediments, versus 0.10 ± 0.06 N l−1but found deeper in the artificial substratum; temporal trends were not straightforward for this species. The adult stage of sedentary cirratulids appeared to actively move into the new available substratum from the neighbouring sediments. An early cirratulid juvenile stage was observed in both microhabitats at a comparable density of 1.8 ± 2.8 N l−1with highly aggregated individuals (cohorts). The peculiar morphology of branchiae, the threadlike body shape and the multivariate morphological differences between two sub-populations settled in the different substrata are reported for these problematic specimens.

Colonization dynamics of periphytic ciliate communities on an artificial substratum in coastal waters of the Yellow Sea, northern China

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.