The origin and development of the Journal of the Marine Biological Association of the United Kingdom is described on the occasion of the publication of the 100th volume. Papers in the Journal demonstrate how the techniques and approaches to the study of the marine environment have evolved over the 120 years of publication. The early papers provided a baseline description of the marine environment and of marine communities that allowed the effects of later perturbations of the environment to be determined. Both the early papers and the long time series of records have proved to be particularly relevant as marine scientists try to predict the long-term results of climatic and anthropogenic effects on the marine ecosystem. The Journal has now become increasingly international, with most papers coming from outside Europe.

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.

To analyse temporal distributions of microplankton populations and relationships to environmental conditions in marine ecosystems, a dataset of microplankton communities was investigated using a range of statistical methods. A total of 164 microplankton species comprising 100 microalgae and 64 ciliates were identified from 120 samples, respectively. Both planktonic microalga and ciliate assemblages showed temporal patterns and were significantly correlated between their temporal variations in abundance. The microplankton communities were characterized by 14 ciliates (e.g. Strombidium sulcatum, Tintinnopsis tubulosoides and Strombidium cheshiri) and 18 microalgae (e.g. Skeletonema costatum and Alexandrium tamarense). Multiple regression analyses showed that the interspecies correlations among these dominant species represented a complex network with a clear seasonal shift. Temporal pattern of microplankton communities was significantly correlated with the environmental variables such as temperature, salinity and nitrate nitrogen. The results suggest the clear species distribution and temporal dynamics of microplankton communities in response to environmental changes, and multivariate statistical approaches were a useful tool to reveal the species distribution patterns and complex microplanktonic interspecies correlations in marine ecosystems.

The annual variations in body-size spectra of planktonic ciliate communities and their relationships to environmental conditions were studied based on a 12-month dataset (June 2007 to May 2008) from Jiaozhou Bay on the Yellow Sea coast of northern China. Based on the dataset, the body sizes of the ciliates, expressed as equivalent spherical diameters, included five ranks: S1 (5–35 μm); S2 (35–55 μm); S3 (55–75 μm); S4 (75–100 μm); and S5 (100–350 μm). These body-size ranks showed a clear temporal succession of dominance in the order of S2 (January–April) → S1 (May–July) → S4 (August–September) → S3 (October–December). Multivariate analyses showed that the temporal variations in their body-size patterns were significantly correlated with changes in environmental conditions, especially water temperature, salinity, dissolved oxygen concentration (DO) and nutrients. In terms of abundance, rank S2 was significantly correlated with water temperature, DO and nutrients, whereas ranks S4 and S5 were correlated with the salinity and nutrients respectively (P < 0.05). These results suggest that the body-size patterns of planktonic ciliate communities showed a clear temporal pattern during an annual cycle and significantly associated with environmental conditions in 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.

The contribution of non-loricate ciliate assemblage to the ecological pattern of a ciliated protozoan community was studied based on a 1-year (June 2007–May 2008) dataset collected from Jiaozhou Bay, northern China. Samples were collected biweekly from five sampling sites. Results showed that: (1) the non-loricate ciliate assemblages were the primary components and significantly correlated with the total ciliate communities in terms of species number, abundance and biomass; (2) the ecological pattern of non-loricate ciliate assemblages was significantly related to that of both total ciliate communities and variations in environmental variables; and (3) spatio-temporal variations in biodiversity (richness, diversity and evenness of species) indices of non-loricate ciliate assemblages were significantly correlated with those of total ciliate communities and the environmental conditions, especially nutrients nitrate nitrogen, nitrite nitrogen and soluble reactive phosphorous. These results suggest that the non-loricate ciliates are a primary contributor to the ecological pattern of total ciliate communities and might be used as a potential bioindicator for bioassessment in marine ecosystems.

The Southern Ocean is unique among the world's oceans in its linkage across the other major ocean basins, its rich and unusual marine ecosystem, and its interaction between the physical climate system and the biogeochemistry of the region. This paper provides an overview and conclusions of a meeting at the Royal Society in London in which an Earth System Science approach was taken to our present and future understanding of the Southern Ocean. A brief summary of what Southern Ocean science has achieved to date, challenges that need to be confronted, and the key questions for the future within an Earth System Science approach are provided.