Ciliate Community Structure Research Articles

Diversity and distribution of small-sized planktonic ciliate communities in the East China Sea

Ciliates are an important ecological component in the microbial food web, but few studies have been conducted on the spatial distribution of small-sized planktonic ciliate communities in the East China Sea (ECS). Investigating ciliate communities using conventional morphological approaches is particularly difficult for the small, fragile, and naked species. Therefore, we applied DNA metabarcoding analysis to explore the spatial pattern of small-sized planktonic ciliate community structure within the surface, deep chlorophyll maximum (DCM), and bottom layers. Results showed the cosmopolitan species, Leegaardiella sp., was dominant and widespread in the ECS. The relative abundance of the mixotrophic family Tontonnidae decreased in the deeper layer. We characterized water masses of the ECS using environmental variables. In nano-sized ciliate communities, non-metric multidimensional scaling (NMDS) plots revealed a correlation with temperature, salinity, density, and depth. The circulation patterns were similar to cluster analysis results, suggesting that hydrographic conditions shaped small-sized ciliate community composition.

A study on spatio-temporal variations in physicochemical parameters and ciliate community structure of three freshwater bodies from Delhi, India

A study on spatio-temporal variations in physicochemical parameters and ciliate community structure of three freshwater bodies from Delhi, India

Insights into the pelagic ciliate community in the Bering Sea: Carbon stock, driving factors and indicator function for climate change

Microzooplankton carbon stock and its biotic-abiotic interactions are important linkage in marine carbon biogeochemistry, which remain poorly documented in the Bering Sea. In the summer of 2019, we investigated the community structure of pelagic ciliates from the surface to bottom (or up to 200 m) in the Bering Sea. High abundance and biomass of ciliate occurred mainly in waters shallower than 50 m. The average carbon stock of ciliates were 350.0 ± 96.4 mg C m−2 and 218.4 ± 148.8 mg C m−2 in oceanic and shelf regimes, respectively. Aloricate ciliates were the dominant group, with an average abundance proportion to total ciliates of over 80% at each depth. We identified 45 tintinnid species belonging to 15 genera, including 7 new record species in the Bering Sea. The abundance proportion of their lorica oral diameter (LOD) size-classes at each sampling depth was mainly within the fractions of 12–16 μm and 24–28 μm. Furthermore, both Codonellopsis frigida and Parafavella jorgenseni can act indicator species of Pacific inflows based on their distributions. Strong correlations were reflected between abiotic environmental factors and the distribution of these indicator species, for instance, the positive correlation between salinity and the cold water-adapted species C. frigida, confirming the dominant role of bottom-control on the ecosystem. Our study laid a foundation for deep understanding of ciliate community at summertime of the Bering Sea, and its role in driving biogeochemical fluxes.

Potential seamount effect on the distribution of the hydrographic features and community structure of pelagic ciliates at the Caroline seamount (tropical western Pacific) in late (2017) and early summer (2019)

Seamounts are ubiquitous features in the world ocean with potential for increasing plankton biodiversity and abundance, and providing important habitats for aquatic predators. Although ecological importance of seamount is well known, the mechanisms for supporting seamount-associated microzooplankton (e.g., pelagic ciliates) communities remains to be substantiated. In this study, pelagic ciliate community structure variations and their relationship with environmental variables were investigated in the Caroline seamount in late (2017) and early summer (2019). Above the seamount in 2019, ciliates exhibited higher abundance and biomass than off the seamount, which supported the classic hypothesis of seamount effect. Aloricate ciliate small size-fraction (10–20 μm) was dominant in bathypelagic (>1000 m) zone. Although relative abundance of small size-fraction was similar in both 2017 and 2019, the absolute abundance in 2019 seamount-effect stations were obviously higher than that in 2017. All abundant tintinnids were classified into surface- and DCM (deep Chl a maximum layer)-peak groups. Among them, four abundant tintinnids (Acanthostomella conicoides, Eutintinnus hasleae, Salpingella curta and S. minutissima) had higher abundance at DCM and might uplifted to shallower waters by upwelling at 2019 seamount-effect stations. The multivariate biota-environment analysis showed that environmental variables have significant impacts on the ciliate community structures in 2017 and 2019. Higher Chl a and nutrient concentrations, and sustained upwelling might be two potential mechanisms for microzooplankton seamount effect. Our study constitutes a rather solid foundation for quantitative and functional study of microzooplankton populations over oligotrophic tropical seamounts.

Influence of the antibiotic nitrofurazone on community dynamics of marine periphytic ciliates: Evidence from community-based bioassays

Marine periphytic ciliates play a pivotal role in shaping coastal ecosystems dynamics, thereby acting as robust biological indicators of aquatic ecosystem health and functionality. However, the understanding of the effects of veterinary antibiotics on composition and structure of periphytic ciliate communities remains limited. Therefore, this research investigates the influence of the veterinary antibiotic nitrofurazone on the community dynamics of marine periphytic ciliates through bioassay experiments conducted over a one-year cycle. Various concentrations of nitrofurazone were administered to the tested ciliate assemblages, and subsequent changes in community composition, abundance, and diversity were quantitatively analyzed. The research revealed significant alterations in periphytic ciliate communities following exposure to nitrofurazone. Concentration-dependent (0–8 mg L−1) decrease in ciliates abundance, accompanied by shifts in species composition, community structure, and community patterns were observed. Comprehensive assessment of diversity metrics indicated significant changes in species richness and evenness in the presence of nitrofurazone, potentially disrupting the stability of ciliate communities. Furthermore, nitrofurazone significantly influenced the community structure of ciliates in all seasons (winter: R2 = 0.489; spring: R2 = 0.666; summer: R2 = 0.700, autumn: R2 = 0.450), with high toxic potential in treatments 4 and 8 mg L−1. Differential abundances of ciliates varied across seasons and nitrofurazone treatments, some orders like Pleurostomatida were consistently affected, while others (i.e., Strombidida and Philasterida) showed irregular distributions or were evenly affected (e.g., Urostylida and Synhymeniida). Retrieved contrasting patterns between nitrofurazone and community responses underscore the broad response repertoire exhibited by ciliates to antibiotic exposure, suggesting potential cascading effects on associated ecological processes in the periphyton community. These findings significantly enhance the understanding of the ecological impacts of nitrofurazone on marine periphytic ciliate communities, emphasizing the imperative for vigilant monitoring and regulation of veterinary antibiotics to protect marine ecosystem health and biodiversity. Further research is required to explore the long-term effects of nitrofurazone exposure and evaluate potential strategies to reduce the ecological repercussions of antibiotics in aquatic environments, with a particular focus on nitrofurazone.

Pelagic ciliate (Ciliophora) communities in the Southern Ocean: Bioindicator to water mass, habitat suitability classification and potential response to global warming

Although the pelagic ciliate (microzooplankton) play important role in carbon flux of marine ecosystems, their ecological function, habitat suitability classification and response to global warming were poorly documented in the Southern Ocean (SO). During summer of 2020/2021, ciliate (including aloricate ciliates and tintinnids) communities in waters from surface to 1000 m were investigated in the SO. Rapid attenuation of ciliate abundance and biomass occurred at 100 m depth in most stations. According to distinctive hydrographic features, five water masses were identified in the SO with unique ciliate community structure. Aloricate ciliate small size-fraction (10–20 μm) was dominant in water masses deeper than 200 m. Tintinnids showed distinctive regional and vertical distribution characteristics, and their habitat suitability characterized by the Bio-index exhibiting different optimum survival zones. Variations in tintinnid habitat can be regarded as indicators for future SO climate change. Correlation between environment factors and biota revealed that depth, Chl a and dissolved oxygen were main factors determining ciliate composition. Combining tendency of phytoplankton and meso-/macro-zooplankton to rapid global warming, ciliates may become smaller and more prominent in the future SO marine pelagic ecosystem. Our study has laid a foundation for recognizing the ciliate community and reinforcing the ideas about tintinnid indication for the change of future SO marine ecosystem.

Diel variations in planktonic ciliate community structure in the northern South China Sea and tropical Western Pacific

Though diel variations are geographically widespread phenomena among phytoplankton and zooplankton, knowledge is limited regarding diel variations in planktonic ciliate (microzooplankton) community structure. In this study, we analyzed diel variations in community structure of planktonic ciliates in the northern South China Sea (nSCS) and tropical Western Pacific (tWP). Hydrological characteristics during day and night were slightly different over both the nSCS and tWP, while ciliate average abundance at night was clearly higher than in the day in the upper 200 m. In both the nSCS and tWP, abundance proportions of large size-fraction (> 30 μm) aloricate ciliates at night were higher than in the day. While for tintinnids, abundance proportion of large lorica oral diameter at night were lower than in the day. The relationship between environmental factors and ciliate abundance pointed out that depth and temperature were main factors influencing aloricate ciliate and tintinnid in both day and night. For some dominant tintinnid species, chlorophyll a was another important factor influencing their diel vertical distribution. Our results provide fundamental data for better understanding the mechanisms of planktonic ciliate community diel variation in the tropical Western Pacific Ocean.

Full-depth vertical distribution of planktonic ciliates (Ciliophora) and a novel bio-index for indicating habitat suitability of tintinnid in the Arctic Ocean

Despite the planktonic ciliate importance in the microzooplankton compartment, their full-depth vertical distribution in the Arctic Ocean was poorly documented as well as the related variations in different water masses. The full-depth community structure of planktonic ciliates was investigated in the Arctic Ocean during summer 2021. The ciliate abundance and biomass decreased rapidly from 200 m to bottom. Five water masses were identified throughout the water column and each one exhibited a unique ciliate community structure. Aloricate ciliates were singled out as the dominant group with average abundance proportion to total ciliates at each depth >95%. Large (>30 μm) and small (10–20 μm) size-fractions of aloricate ciliates were abundant in shallow and deep waters, respectively, which revealed an anti-phase relationship in vertical distribution. Three new record tintinnid species were found during this survey. Pacific-origin species Salpingella sp.1 and Arctic endemic species Ptychocylis urnula occupied the top abundance proportion in the Pacific Summer Water (44.7%) and three water masses (≥38.7%, Mixed Layer Water, Remnant Winter Water, Atlantic-origin Water), respectively. The habitat suitability of tintinnid abundant species was characterised by the Bio-index revealing a distinct death-zone for each species. Variations in survival habitat of abundant tintinnids can be regarded as indicators for the future Arctic climate change. These results provide fundamental data on the microzooplankton response to the intrusion of Pacific waters into the Arctic Ocean upon its rapid warming.

Community structure and diversity of epibenthic soil ciliates in a mangrove ecosystem on the southern coast of India

Marine biology,marine ecology,Phytoplankton, marine algae, zooplankton, nekton, benthos, corals and coral reefs, ecology, zoogeography and systematics, primary production and experimental work on ecosystem including energy flow at different trophic levels, population dynamics and theoretical models, recycling of matter, influence of environmental factors on metabolic activity, marine microbiology, mariculture and experimental work on propagation of cultivable species, biology of fishes, marine reptiles, sea birds and mammals, physical, chemical, geological and meteorological features of the environments related to marine biology, marine environmental damage caused by pollution and engineering works, underwater observations, conservation of living resources, modifications in methodology and techniques and development of new apparatus related to marine sciences

Planktonic ciliate community structure and its distribution in the oxygen minimum zones in the Bay of Bengal (eastern Indian Ocean)

Oxygen minimum zones (OMZs) are geographically widespread phenomena among world seas, while knowledge regarding planktonic ciliate (microzooplankton) community structure in the OMZ is lacking. In this study, we analyzed community structure of planktonic ciliates in the OMZ waters of the Bay of Bengal, eastern Indian Ocean. Both hydrological characteristics (temperature, salinity, chlorophyll a in vivo fluorescence (Chl a) and dissolved oxygen (DO)) and planktonic ciliate community showed obvious variations in vertical profile. An obvious higher ciliate abundance and biomass occurred in the thermocline zones (surface to 100 m) than in the OMZs (150–800 m). For aloricate ciliates, abundance proportions of small (10–20 μm) and large (> 30 μm) size-fractions showed increase and decrease characteristics from thermocline zones to OMZs, respectively. With regard to loricate ciliates (tintinnids), more species richness and higher abundance occurred in the thermocline zones than in the OMZs. Four vertical distribution patterns were classified for tintinnids. Three species only occurred in the OMZs. Three-dimensional representation of tintinnid lorica length, lorica oral diameter and abundance proportion revealed that small-sized species in thermocline zones decreased more sharply to OMZs compared to large-sized species. Relationship between environmental variables and ciliate abundance showed that temperature, DO and Chl a were main factors determining ciliate abundance. Our results provide fundamental data for better understanding on the ecological role of planktonic ciliates in the thermocline zones and OMZs of the Indian Ocean.

Regional and local environment drive biogeographic patterns in intertidal microorganisms

AbstractAimUnderstanding large‐scale spatial distribution patterns is not only a central goal of ecology but is also essential for conservation planning. Nevertheless, the biogeographical patterns of diversity and composition remain unclear for microorganisms and the role of various factors in structuring their assemblages is still poorly known. Here, we tested whether the diversity and community structure of ciliates are driven by both local environmental and regional dispersal‐related processes.LocationCoasts of China.TaxonBenthic ciliates.MethodsWe sampled ciliates at 30 sandy beaches covering a latitudinal range of over 2500 km from October to November 2020. We first used generalized linear models to examine the most important predictors of ciliate alpha diversity. Then, distance‐based linear models (DistLM) were used to identify the relative importance of local and regional variables in explaining community structure variability. We further used nonmetric multidimensional scaling (NMDS) and permutational multivariate analysis of variance (PERMANOVA) to reveal patterns in community structure.ResultsWe found that local environmental factors including beach index (BI), salinity and mean particle size (MPS) were more important in shaping ciliate alpha diversity than latitude. However, the Shannon alpha diversity index decreased with latitude, perhaps due to anthropogenic disturbances. DistLM analysis emphasized regional processes in shaping community structure. Both NMDS and PERMANOVA supported a clear separation among the three clusters matching with the ecoregional delineations suggested for macroorganisms. We also note that community trait composition was partially explained by a local factor, i.e. the maximum spring tide range of beaches.Main conclusionsCiliate communities were driven by both local environmental and regional factors. We suggest that these biogeographic patterns may have stemmed from large‐scale environmental filtering related to the outflow of Yangtze River, rather than from dispersal limitation or historical events. The current study provides a new understanding of the biogeographic patterns and underlying mechanisms of marine microorganisms, thus helping improve their management and conservation in the face of future global change.

Hydrographic Feature Variation Caused Pronounced Differences in Planktonic Ciliate Community in the Pacific Arctic Region in the Summer of 2016 and 2019.

Planktonic ciliates are an important component of microzooplankton, but there is limited understanding of their responses to changing environmental conditions in the Pacific Arctic Region. We investigated the variations of ciliate community structure and their relationships with environmental features in the Pacific Arctic Region in the summer of 2016 and 2019. The Pacific water was warmer and more saline in 2019 than in 2016. The abundance and biomass of total ciliate and aloricate ciliate were significantly higher in 2019 than those in 2016, while those of tintinnid were significantly lower. The dominant aloricate ciliate changed from large size-fraction (> 30 μm) in 2016 to small size-fraction (10–20 μm) in 2019. More tintinnid species belonging to cosmopolitan genera were found in 2019 than in 2016, and the distribution of tintinnid species (Codonellopsis frigida, Ptychocylis obtusa, and Salpingella sp.1) in 2019 expanded by 5.9, 5.2, and 8.8 degrees further north of where they occurred in 2016. The environmental variables that best-matched tintinnid distributions were temperature and salinity, while the best match for aloricate ciliate distributions was temperature. Therefore, the temperature might play a key role in ciliate distribution. These results provide basic data on the response of the planktonic ciliate community to hydrographic variations and implicate the potential response of microzooplankton to Pacification as rapid warming progresses in the Pacific Arctic Region.

Ecological Study of the Active Ciliate Community from Bromeliads during the Humid Season in Different Types of Forests of the Mexican Neotropics

Bromeliads are a Neotropical family of monocots, colonized by several families of ciliates, with some species that inhabit only this type of microecosystems. Ecological factors such as the presence of water, plant volume, seasonality and predators, have been recognized as important factors, which play a role in the ciliate community structure in tank bromeliads. The objective of this study is to describe different communities of active ciliates from epiphytic and terrestrial bromeliads that inhabit the dry tropical forest, montane cloud forest, oak forest and semideciduous tropical forest in the Mexican Neotropics during the humid season of the year 2016. We found 22 species of active ciliates. A higher richness of ciliate species was found in the bromeliads of the montane cloud forest. Based on statistical tests, we determine that the pH and water temperature, plant diameter, its distance above the ground and altitude above sea level in relation to ciliate abundance explain <50% of the variation; however, the combination of plant diameter and its distance above the ground shows a positive effect in relation to ciliate abundance. We provide new evidence that bromeliads that inhabit mountains and lowland forests in a larger geographic area host ciliate communities with different species composition.

Functionally similar species of ciliates have similar dynamics: A biennial survey study in a large eutrophic lake

The spatial and temporal planktonic ciliate community structure of a large shallow eutrophic lake was described in detail based on a monthly monitoring campaign over 2 years using the quantitative protargol stain approach. We found that there was a large variety and low constancy of ciliate plankton and a clear advantage of several small species. Balanion planctonicum, Rimostrombidium brachykinetum, and Urotricha farcta contributed 19.7%, 13.4%, and 10.7% to the total abundance, respectively. The ciliate community was significantly varied in different lake regions of different eutrophication levels, and the distribution of some of the main species, especially prostomatids and scuticociliatids, might be closely related to the nutrient level of the lake regions. The seasonal dynamics of ciliate taxa with similar functional feeding habits across regions at different trophic levels are more convergent than those of species with very different functions, and the top-down effect (cladocerans, rotifers), nutrition, and water temperature were the key factors shaping ciliate community structure. The results of this study accentuate the important effects of species functional diversity on community differences and may improve our knowledge of ciliate diversity and functional ecology in shallow eutrophic lakes.

The influence of environmental characteristics on the distribution of ciliates in two coastal areas in the Eastern Mediterranean Sea (Gulf of Gabes, Tunisia)

Spatial variability of ciliates in relation to chlorophyll a, nutrients, and environmental variables were studied in lagoon (Boughrara lagoon) and marine ecosystems (Ghannouch coast) in the surface layer and at the water–sediment interface during autumn. Results revealed a striking difference between the two ecosystems, with higher nutrient concentrations at the Ghannouch coast, except for ammonium. Ciliate abundance was five to six times higher in the lagoon (123.43–126.80×102cellsl−1) than at the marine coast (21.80–24.50×102cellsl−1) (ANOVA, P < 0.001). Loricate ciliate attained high abundance in Boughrara lagoon (88%–90% of total ciliates abundance) and decreased at Ghannouch coast (44%–51% of total ciliate abundance). The species richness of the loricate ciliates was higher in Boughrara lagoon (68 taxa at both surface layer and water–sediment interface) than at Ghannouch coast (32 taxa at the surface layer and 23 taxa at the water–sediment interface). Naked ciliates were poorly represented (10%–12% of the total ciliate abundance) in the lagoon stations but had substantial percentages (49%–56% of the total ciliate abundance) at Ghannouch coast. The spatial distribution patterns of ciliate communities at both sites were strongly influenced by nutrient heterogeneity. Small species (naked ciliates) are favoured by higher nutrient concentrations at Ghannouch coast, whereas the contribution of large species (loricate ciliates) increased with the lower nutrient concentrations in Bouhgrara lagoon. It has been suggested that nutrient changes could drive shifts in ciliate community structure and abundance. The deteriorated water quality of the Ghannouch coast likely induces the low loricate ciliate abundance and diversity and the higher relative abundance of naked ciliates compared to the less polluted Boughrara lagoon.

Ciliates as bioindicators of environmental pressure in a karstic river

Ciliates (protozoa) are a very large and diverse group of microeukaryotes that occupy a central position in the trophic web of freshwater ecosystems. Ciliates exhibit high ecological sensitivity and have tremendous bioindicator potential, but they are largely ignored in routine biomonitoring, mainly due to limitations in morphological diagnosis, which is both time-consuming and costly. In this study, we combined molecular (Illumina sequencing of the hypervariable V9 region of the SSU rRNA gene) and morphological approaches to get a detailed insight into the periphytic ciliate community structure and function within a karst, tufa-precipitating hydrosystem (National Park Krka, Croatia). Periphyton (biofilm) was sampled from light- and dark-exposed lithified tufa/stones at four representative locations within the Krka River, including upstream, midstream, and downstream river sections. We identified hydrological parameters and saprobiological classification of the sampling locations as the main structuring factors for ciliate communities. The molecular approach showed a clear separation of sampling locations in beta diversity analyses, as confirmed by PERMANOVA test. In contrast, alpha diversity was mostly affected by light exposition of the lithified tufa/stones, as confirmed by morphological approach. Environmental conditions consistently affected ciliate community composition at all locations, resulting in clear separation of periphyton samples. Our results indicate that ciliates should be considered as important bioindicators in monitoring tufa-forming rivers and streams, and the molecular approach (V9 region) proved to be applicable because as it efficiently captured the diversity of ciliates in periphyton. Validation of such an approach would lead to significant progress in extending monitoring to a broader range of indicator organisms than those now included in standard monitoring.

Ciliates (Alveolata, Ciliophora) as bioindicators of environmental pressure: A karstic river case

Ciliates are single celled eukaryotes recognized as key players in the microbial loop of aquatic ecosystems. The present study was carried out on the Krka River (Croatia), a karst freshwater ecosystem characterized by tufa barriers, biomineralization and highly diverse aquatic communities. The main aims of the study were to investigate ciliate community structure in the biofilm (i.e. periphyton) samples collected from light- and dark-exposed lithified tufa/stones. Furthermore, by establishing links between ciliate community patterns and environmental parameters, we aimed to assess the bioindicator potential of specific ciliate taxa for environmental monitoring of freshwater habitats. The periphyton sampling was performed at four representative sites of the river source, upstream, middle and downstream river sections. Ciliate community was investigated via traditional microscopy analyses and environmental DNA (eDNA) metabarcoding (Illumina sequencing of the hypervariable V9-region of the SSU rRNA gene). The molecular approach recorded a substantially higher number of ciliate taxa, most of which taxonomically belonging to genera typically occurring in tufa barriers. The results from microscopy analyses did not show any links between ciliate community structure and sampling location. However, eDNA approach indicated significant differences among the sampling locations regarding the ciliate community structure. Thereby, hydrological parameters and saprobiological classification of the sampling sites were the main structuring factors for ciliate community. The coupling of eDNA metabarcoding with the morphological approach provides a robust, in-depth analytical system in elucidating the bioindicator potential of ciliated protists.

Spatial distribution of planktonic ciliates in the western Pacific Ocean: along the transect from Shenzhen (China) to Pohnpei (Micronesia).

Planktonic ciliates have been recognized as major consumers of nano- and picoplankton in pelagic ecosystems, playing pivotal roles in the transfer of matter and energy in the microbial loop. However, due to the difficulties in identification, the species composition of ciliate assemblages, especially for the small, fragile, and naked species that usually dominate the ciliate communities in the oceanic waters, remains largely unknown. In the present study, 22 stations along the transect from Shenzhen (China) to Pohnpei (Micronesia) were sampled for the enumeration of picoplankton and nanoflagellates. In addition, pigment analysis of major phytoplankton groups along with the measurements of environmental variables including temperature, salinity, and nutrients were also carried out. Ciliates were identified at species level using quantitative protargol stain to reveal the species composition and their distribution patterns from off-shore to open ocean. Ciliate abundance was positively correlated with phosphate, silicate, and pico-sized pigmented eukaryotes (PPEs), whereas the biomass was closely related with PPEs, heterotrophic nanoflagellates, and chlorophytes. The combination of silicate and pigmented nanoflagellates was identified as the major factor driving the ciliate community composition. The close relationship between silicate and ciliate abundance and community structure needs further validation based on more data collected from oceanic waters. Our study showed the necessity of using techniques that can reveal the community composition at higher taxonomic resolutions in future studies on ciliates.

Community structure and vertical distribution of planktonic ciliates in the saline meromictic lake Shira during breakdown of meromixis

The study deals with the vertical distribution and seasonal dynamics of planktonic ciliates in the pelagic and littoral zones of a saline meromictic Lake Shira. Fourteen species of free-living ciliates have been found in the Lake, seven of them inhabiting the pelagic zone. The richness of ciliates is higher both in terms of the number of species and biomass in the littoral zone compared to the pelagic zone. Although the ciliate species diversity is low in the pelagic zone, in certain seasons, the biomass of some of the species may reach considerable values, up to 3.4 g m−2 in the water column. The biomass of ciliates in Lake Shira is generally comparable to the average values for other mesotrophic lakes. The abundance and composition of ciliate populations in Lake Shira vary considerably with depth.Changes in the Lake ecosystem caused by meromixis breakdown in 2015-2016, which induced considerable variations in many Lake components, affected the vertical distribution of planktonic ciliates. However, the annual average biomass of the species that inhabited the Lake before meromixis breakdown remained unchanged. The total ciliate biomass increased due to the presence of the new species.

Spatial distribution patterns of planktonic ciliate communities in the East China Sea: Potential indicators of water masses

The spatial distribution of planktonic ciliates over the coastal and continental shelf of the East China Sea were investigated using quantative protargol staining. Aloricate oligotrichs and choreotrichs were dominant in terms of species number, abundance and biomass. Ciliate densities varied between 3 and 2688 cells L−1 with higher values occurring in the coastal water and the mixing water than in the Yellow Sea coastal water and the Taiwan warm water. Ciliate biomass exhibited a similar pattern as abundance. A canonical analysis of principal coordinates demonstrated that the spatial patterns of ciliate community structure could be clearly discriminated in different water masses. Diversity parameters showed strong relationships with spatial changes in ciliate communities and might serve as predictors of water mass in future studies. Our findings provide evidence for using ciliate communtiy composition, supplemented with dominant species and diversity parameters, as potential indicators of water masses in complex marine environments.