Ciliate Community Research Articles

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.

The search finds an end: the morphologically chimeric hysterocinetids belong to the subclass Hymenostomatia (Ciliophora: Oligohymenophorea)

Abstract The digestive tract of oligochaetes harbours a diverse ciliate community embracing plagiotomids, nyctotherids, astomes, and hysterocinetids. Although several hundred intestinal ciliate species are known, only two hysterocinetids have been reported from the intestine of Holarctic lumbricid earthworms hitherto. The present study is focused on the taxonomy, morphology, and molecular phylogeny of two lumbricid-dwelling taxa, the insufficiently known Protoptychostomum simplex and Hysterocineta bellerophon sp. nov., detected in Central Europe. Diagnoses of the genera Protoptychostomum and Hysterocineta were improved taking into account also features of the oral ciliature for the first time. In the past, the proper classification of hysterocinetids in the class Oligohymenophorea was hampered by the dramatic remodelling of the anterior body end into a thigmotactic sucker, as well as by the helicalization and transfer of the oral apparatus to the posterior body pole. The present phylogenetic analyses of nuclear and mitochondrial genes robustly reject the classification of hysterocinetids in subclass Scuticociliatia or as a distinct subclass, Hysterocinetia. However, hysterocinetids were consistently and robustly nested deep in subclass Hymenostomatia in a sister-position to the free-living Tetrahymena paravorax. The hymenostome affinity of hysterocinetids is also corroborated by the parakinetal stomatogenesis and the stichodyad paroral membrane accompanied by three regularly organized membranelles.

Diversity Temporal-Spatial Dynamics of Potato Rhizosphere Ciliates and Contribution to Nitrogen- and Carbon-Derived Nutrition in North-East China.

Ciliates are an important component of the rhizosphere microorganism community, but their nutritional contribution to plants has not been fully revealed. In this paper, we investigated the rhizosphere ciliate community of potatoes during six growth stages, illustrated the spatial-temporal dynamics of composition and diversity, and analyzed the correlation between soil physicochemical properties. The contributions of ciliates to the carbon- and nitrogen-derived nutrition of potatoes were calculated. Fifteen species of ciliates were identified, with higher diversity in the top soil, which increased as the potatoes grew, while they were more abundant in the deep soil, and the number decreased as the potatoes grew. The highest number of species of ciliates appeared in July (seedling stage). Among the five core species of ciliates, Colpoda sp. was the dominant species in all six growth stages. Multiple physicochemical properties affected the rhizosphere ciliate community, with ammonium nitrogen (NH4+-N) and the soil water content (SWC) greatly influencing ciliate abundance. The key correlation factors of ciliates diversity were NH4+-N, available phosphorus (AP), and soil organic matter (SOM). The annual average contribution rates of carbon and nitrogen by rhizosphere ciliates to potatoes were 30.57% and 23.31%, respectively, with the highest C/N contribution rates reaching 94.36% and 72.29% in the seedling stage. This study established a method for estimating the contributions of carbon and nitrogen by ciliates to crops and found that ciliates could be potential organic fertilizer organisms. These results might be used to improve water and nitrogen management in potato cultivation and promote ecological agriculture.

Cilioplankton Communities as an Indicator of the Pollution Degree in the Caspian Sea

During 2014-2021 years a study of the species diversity of planktonic ciliates of the Caspian coast of the Absheron Peninsula was conducted. As a result of research in planktonic communities of free-living ciliates, 62 species, belonging to 22 families were observed. Among the recorded families, Strombidiidae takes first place in terms of the number of species. The families Uronychiidae, Nassulidae, Epistylidae, and Zoothamniidae were represented by only one species. A correlation between similarity of the planktonic ciliates species diversity and the degree of organic pollution of coastal area marine water has been established. The results of the cluster analysis showed that the highest similarity of the species diversity (95.5%) was noted for two collection points on the northern coast of Absheron, near the settlements of Novkhani and Bilgah. This is due to the fact that the northern coast is less polluted by oil products and domestic sewage. Thus, according to the similarity of species diversity of planktonic communities of ciliates on the coast of the Absheron Peninsula, the two clusters are clearly distinguished. One unites the cleanest sites (Novkhani and Bilgah — 95.5%), and all the other 4 stationary points of the collection (Sumgait, Turkan, Shikh, Sangachal — more than 50%) are combined into the second cluster.

Variability of tintinnid ciliate communities with water masses in the western Pacific Ocean

Abstract Tintinnids play a pivotal role in the marine plankton ecosystem and are model organisms in plankton studies. However, the biogeographic distribution type and community variation of tintinnids from coastal to open waters in the western Pacific have never been studied before. In the present study, 42 surface tintinnid samples were collected from coastal water to the western Pacific warm pool. A total of 84 tintinnid species were identified. The Kuroshio intrusion has obvious influence on tintinnid distribution and community structure. Fifty-two tintinnid species with relatively high occurrence frequency were classified into neritic, transitional, Kuroshio, warm-pool and cosmopolitan species. We verified the existence of tintinnid transitional species and community in Mixed Water between Neritic and Kuroshio Waters (KW). Tintinnid species richness, abundance, Shannon-Wiener index and Pielou index were higher in the KW than in the Warm-pool Water. The community complexity and stability was highest in the KW. Our findings provide a profound understanding of planktonic biogeography and community variation from nearshore to open waters in tropical and subtropical oceans.

Do marine planktonic ciliates follow Bergmann's rule?

Body size is a fundamental trait determining individual fitness and ecological processes. Reduction in body size with increasing temperature has been widely observed in most ectotherms and endotherms, known as Bergmann's rule. However, we lack data to assess if ciliates, the major consumers of marine primary production, follow Bergmann's rule and what drives the distributions of their cell size. Here, we examined a data set (287 samples) collected across the global oceans to investigate biogeographic patterns in the mean cell‐size of ciliate communities. By measuring the sizes of every ciliate cell (< 10 to > 300 per sample), we found that community cell‐size increased with increasing latitude, conforming to Bergmann's rule. We then addressed the cause. Temperature was a main driver of the trend. Ciliate community mean cell‐size decreased 34% when temperature increased from 3.5 to 31°C, implying that temperature may be a direct physiological driver. In addition, prey (phytoplankton) size also influenced the trend, with ciliate size increasing by 35% across the gradient of phytoplankton size (0.6–15.5 μm). Generally, these findings emphasized the importance of how both biotic and abiotic factors affect size distribution of marine ciliates, a key component of pelagic ecosystems. Our novel, extensive dataset and the predictive trends arising from them contribute to understanding how climate change will influence pelagic ecosystem functions.

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.

A Deep Seamount Effect Enhanced the Vertical Connectivity of the Planktonic Community Across 1,000 m Above Summit

AbstractSeamount effects, which are generally defined as hydrographic disturbances caused by topography and nutrient enrichment and biological aggregations around seamounts, are normally observed in shallow seamounts due to limited sampling efforts in deep seamounts. However, it remains unclear how and to what extent do deep seamounts leave their imprint on planktonic communities. Herein ciliates, a representative protist group, were chosen to explore the effect of deep seamount on planktonic community. By investigating the vertical and horizontal distribution of ciliate communities around the Kocebu Guyot (summit at −1,198 m) and in nonseamount area, we revealed an obvious deep seamount effect, which enhanced the vertical mixing of ciliate communities to an extent of over 1,000 m above the summit. The vertical mixing was manifested by a strong uplift of bottom dwellers from waters deeper than 500 m and a weak uplift from the 300 m layer to the deep chlorophyll maximum (about 150 m) layer. Network analysis showed that the ciliate cooccurrence relationship around the seamount was much more complex than that in nonseamount area. Statistical analysis indicated that seamount significantly weakened the limitation that water depth posed on vertical ciliate distribution. Overall, the ciliate communities presented a much higher‐resolution record of deep seamount effects than physico‐chemical data. Deep seamount could enhance the vertical mixing of waters and cooccurrence complexity of planktonic community to the euphotic layer. Considering the wide existence of deep seamounts, such an effect may have ecological significance and enhance the cycles of matter and energy of global oceans.

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.

Fauna of the endobiotic ciliates from the rumen of the red deer Cervus elaphus Linnaeus, 1758

Fauna of endobiotic ciliates of the red deer Cervus elaphus xanthopigus and of the Altai wapiti Cervus elaphus sibiricus in Asia was studied for the first time. In total, 14 species and 5 forms of ciliates belonging to 5 genera of Ophryoscolecidae and Isotrichidae were found. The species composition of endobiotic ciliates in all studied individuals of deer appeared to be rather similar. Most of the samples contained Entodinium wapiti , previously considered specific to the North American wapiti Cervus canadensis . The influence of different factors on the formation of a certain structure of communities of ciliates, endobionts of the rumen of the red deer Cervus elaphus , is discussed.

Comparison of microzooplankton community structure before and during Acromitus flagellatus swarm in the estuarine waters of northern Bay of Bengal

The scyphozoan jellyfish Acromitus flagellatus (Maas, 1903) formed massive aggregations in the River Saptamukhi channel, situated in Sundarbans, the world’s largest deltaic ecosystem. The present study in this mangrove-fringed estuary aims to find the variations in the community structure of microzooplankton (protists and metazoans of 20-200μm size class) before the onset of the swarm and during it. It also briefly documents the trophic cascade exerted by the swarming A. flagellatus on the lower trophic levels. The taxonomic groups representing the microzooplankton community from this study included ciliates, dinoflagellates (heterotrophic and mixotrophic), rotifers, foraminiferans, and metazoan larvae (copepod nauplii, bivalve larvae, gastropod larvae, polychaete larvae). Copepod nauplii dominated the abundance in all stations both before the swarm (BS) and during the swarm (DS). Regarding the species composition of protists, tintinnids dominated the ciliate community, while heterotrophic dinoflagellates dominated the dinoflagellate community, contributing 32% and 30% of protist composition in the BS survey and 37% and 23% of protist composition in the DS survey, respectively. The abundance of another protist group, the planktonic foraminiferans, was very low and was obtained only in the DS survey. In terms of diversity composition and abundance, the microzooplankton community when compared to the BS survey, showed little difference during the A. flagellatus swarming event (DS), except for a few exceptions. Notably, during the swarm period, microzooplankton abundance showed a positive relationship with A. flagellatus numbers, while the mesozooplankton abundance reduced significantly, exhibiting the top-down control by A. flagellatus in the pelagic food web.

Community assembly and co-occurrence network complexity of interstitial microbial communities in the Arctic (investigation of ciliates in the White Sea intertidal zone)

Arctic coastal ecosystems play a major role in global environmental system and have been altered significantly by climate changes. To better understanding the response of marine coastal ecosystems towards rapid Arctic climate changes, we examined the variation in diversity and community structure and provided insights into the co-occurrence network and community assembly of interstitial ciliates in the Kandalaksha Gulf of the White Sea from 2009 to 2019. Co-occurrence networks analysis indicated considerably high ration of positive correlations within a community that indicated low competition between interstitial ciliate species. Furthermore, we found that contribution of stochastic processes to the ciliate community assembly was insignificant. Compare with earlier data from the same ecosystem obtained in 1980s–1990s, the role of competitive factors is decreasing, and communities are becoming more spatially and temporally homogeneous. This community simplification is likely due to the response of the entire intertidal ecosystem to global climate change in Arctic.

Spatial and seasonal changes in microphytoplankton and ciliate communities in a stressed area of the southeastern Mediterranean coast (Tunisia)

Spatial and seasonal changes in microphytoplankton and ciliate communities in a stressed area of the southeastern Mediterranean coast (Tunisia)

The relative roles of multiple drivers on benthic ciliate communities in an intertidal zone

Intertidal biodiversity is being severely disrupted as a result of increased anthropogenic activity. However, our knowledge about how natural gradients, human induced disturbance and biotic interactions affect biodiversity is limited. So, we investigated how three facets of alpha diversity and community composition of benthic ciliates responded to environmental and biological gradients in the intertidal zone of Zhejiang, China. The key determinants and their relative effects on ciliate communities were identified using structural equation modeling, distance-based redundancy analysis and variation partitioning analysis. Our results revealed that sediment grain size was the most important factor affecting alpha diversity and community composition. Human induced eutrophication had significant effects on phylogenetic alpha diversity and community composition. However, the effects of biotic interactions on ciliate communities were relatively small. Moreover, we found community composition was more sensitive to human disturbance than alpha diversity, thus, more suitable for indicating human-induced eutrophication.

Ciliate Morpho-Taxonomy and Practical Considerations before Deploying Metabarcoding to Ciliate Community Diversity Surveys in Urban Receiving Waters.

Disentangling biodiversity and community assembly effects on ecosystem function has always been an important topic in ecological research. The development and application of a DNA metabarcoding method has fundamentally changed the way we describe prokaryotic communities and estimate biodiversity. Compared to prokaryotes (bacteria and archaea), the eukaryotic microbes (unicellular eukaryotes) also fulfill extremely important ecological functions in different ecosystems regarding their intermediate trophic positions. For instance, ciliated microbes (accounting for a substantial portion of the diversity of unicellular eukaryotes) perform pivotal roles in microbial loops and are essential components in different ecosystems, especially in water purification processes. Therefore, the community composition of ciliated species has been widely utilized as a proxy for water quality and biological assessment in urban river ecosystems and WWTPs (wastewater treatment plants). Unfortunately, investigating the dynamic changes and compositions in ciliate communities relies heavily on existing morpho-taxonomical descriptions, which is limited by traditional microscopic approaches. To deal with this dilemma, we discuss the DNA-based taxonomy of ciliates, the relative merits and challenges of deploying its application using DNA metabarcoding for surveys of ciliate community diversity in urban waterbodies, and provide suggestions for minimizing relevant sources of biases in its implementation. We expect that DNA metabarcoding could untangle relationships between community assembly and environmental changes affecting ciliate communities. These analyses and discussions could offer a replicable method in support of the application of evaluating communities of ciliated protozoa as indicators of urban freshwater ecosystems.

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.

Protist Diversity Responses to Experimental N Deposition in Biological Crusts of a Semiarid Mediterranean Ecosystem

Biological soil crusts (BSC) are associations of different macro and microorganisms and aggregated soil particles located on the surface of soils in many different habitats. BSC harbour a diverse and complex community of ciliates and testate amoebae. These phagotrophic protists play an important role in C and N recycling in soil ecosystems but have not been frequently studied in BSC. In this context, the effects of three increasing N inputs on ciliates and testate amoebae in crusts from a semi-arid Mediterranean ecosystem were evaluated. A field experiment with artificial N-deposition was designed to mimic the effects caused by anthropogenic N depositions. The results have shown that the protist populations of these semi-arid Mediterranean environments have lower species richness than other soil environments. The increase in N produces a net loss of diversity in the populations studied and shifts in the community structure. It has also been shown that some ciliates and testate amoebae, due to their population responses to increased N concentrations, could potentially be used as bio-indicators of N contamination in these BSCs.

Planktonic ciliate community driven by environmental variables and cyanobacterial blooms: A 9-year study in two subtropical reservoirs

It is well-established that environmental variability and cyanobacterial blooms have major effects on the assembly and functioning of bacterial communities in both marine and freshwater habitats. It remains unclear, however, how the ciliate community responds to such changes over the long-term, particularly in subtropical lake and reservoir ecosystems. We analysed 9-year planktonic ciliate data series from the surface water of two subtropical reservoirs to elucidate the role of cyanobacterial bloom and environmental variabilities on the ciliate temporal dynamics. We identified five distinct periods of cyanobacterial succession in both reservoirs. Using multiple time-scale analyses, we found that the interannual variability of ciliate communities was more strongly related to cyanobacterial blooms than to other environmental variables or to seasonality. Moreover, the percentage of species turnover across cyanobacterial bloom and non-bloom periods increased significantly with time over the 9-year period. Phylogenetic analyses further indicated that 84 %–86 % of ciliate community turnover was governed by stochastic dispersal limitation or undominated processes, suggesting that the ciliate communities in subtropical reservoirs were mainly controlled by neutral processes. However, short-term blooms increased the selection pressure and drove 30 %–53 % of the ciliate community turnover. We found that the ciliate community composition was influenced by environmental conditions with nutrients, cyanobacterial biomass and microzooplankton having direct and/or indirect significant effects on the ciliate taxonomic or functional community dynamics. Our results provide new insights into the long-term temporal dynamics of planktonic ciliate communities under cyanobacterial bloom disturbance.

Effects of nitrofurazone on ecosystem function in marine environments: A case study on microbial fauna.

To evaluate the effects of nitrofurazone on functional processes in marine ecosystems, periphytic protozoan communities were exposed to different concentrations of the antibiotic for a 10-day duration. Species trait distributions in the tested communities were observed during exposure to five concentrations of nitrofurazone. A fuzzy coding system with seven traits and seventeen categories was used to summarize the changes in functional patterns of the test organisms. Nitrofurazone had a significant influence on the function process of the periphytic ciliate communities. Bacterivores with flattened bodies were sensitive to the toxicant whereas sessile and cylindrical raptors showed a high tolerance to nitrofurazone, invariably dominating communities exposed to high concentrations. Bootstrapped-average analysis demonstrated a significant change in functional patterns at highest nitrofurazone concentrations (8mgl-1). Based on these findings, it is suggested that nitrofurazone may negatively influence ecosystem function in marine environments.

Distinct distribution patterns of planktonic ciliate communities along environmental gradients in a semi-enclosed bay

Jiaozhou Bay is a representative temperate coastal ecosystem and connects with the Yellow Sea by a narrow mouth. The eastern part of the Bay is more polluted than the western and outer parts due to the combined effects of urban sewage and weak water exchange between different water masses. However, the previous results from microscopy analyses did not show any distinct distribution pattern of planktonic ciliates, which are generally considered good bioindicators along environmental gradients. We hypothesize that ciliates may respond to environmental stress by regulating the community of rare taxa, which was not uncovered by morphological methods. The diversity and distribution patterns of planktonic ciliate communities were investigated through high-throughput DNA sequencing from 13 stations in the eastern, western and outer parts of Jiaozhou Bay. The alpha diversity indices showed an increasing trend from the east Bay to the west Bay to the outer Bay. Significant differences in planktonic ciliate communities from different zones of the Bay were mainly attributed to rare rather than abundant taxa. Correlation network analysis revealed that the rare taxa generally have positive correlations with other rare ones, while more negative correlations were found among abundant taxa. We further revealed the distributions of three dominant genera (Stenosemella, Tintinnopsis, and Strombidium) were significantly correlated with environmental variables, suggesting that they might be used as ecological indicators. Our results elucidate the bioindicator potential of ciliate along environmental gradients in a semi-enclosed bay.