Susceptibilities of different-sized ciliates to direct suppression by small and large cladocerans

• 1 Laboratory experiments compared the susceptibilities of six ciliates and the rotifer Keratella cochlearis to predation and interference from Daphnia pulex and Bosmina longirostris.
• 2 Susceptibilities of the ciliates to D. pulex were similar to or less than that of the rotifer, and decreased with increasing ciliate size. Most ciliates were just as susceptible to B. longirostris as to the much larger D. pulex. The jumping response of the oligotrich Strobilidium gyrans appeared to be an effective defence against B. longirostris.
• 3 Clearance rates of B. longirostris and D. pulex on different ciliate species at a density of 1,3 ciliates ml^?1 ranged from 1–30 to 5–24ml ind.^?1 day^?1, respectively. In natural plankton communities, cladocerans could impose high mortality rates on ciliates and shift the size structure of ciliate assemblages towards larger and less susceptible species.

     

Spring bloom succession,grazing impact and herbivore selectivity of ciliate communities in response to winter warming

This study aimed at simulating different degrees of winter warming and at assessing its potential effects on ciliate succession and grazing-related patterns. By using indoor mesocosms filled with unfiltered water from Kiel Bight, natural light and four different temperature regimes, phytoplankton spring blooms were induced and the thermal responses of ciliates were quantified. Two distinct ciliate assemblages, a pre-spring and a spring bloom assemblage, could be detected, while their formation was strongly temperature-dependent. Both assemblages were dominated by Strobilidiids; the pre-spring bloom phase was dominated by the small Strobilidiids Lohmaniella oviformis, and the spring bloom was mainly dominated by large Strobilidiids of the genus Strobilidium. The numerical response of ciliates to increasing food concentrations showed a strong acceleration by temperature. Grazing rates of ciliates and copepods were low during the pre-spring bloom period and high during the bloom ranging from 0.06 (Δ0°C) to 0.23 day⁻¹ (Δ4°C) for ciliates and 0.09 (Δ0°C) to 1.62 day⁻¹ (Δ4°C) for copepods. During the spring bloom ciliates and copepods showed a strong dietary overlap characterized by a wide food spectrum consisting mainly of Chrysochromulina sp., diatom chains and large, single-celled diatoms. Priority programme of the German Research Foundation—contribution 4.     

Participation of a Specific Substrate Degrading Strain in a Mixed Bacteria Culture as a Result of Ciliate Grazing

Participation of nitrilotriacetic acid degrading bacterial strain NTA-1 in the continuous-cultivated mixed culture was studied under different conditions including predation pressure of the ciliate Dexiostoma campyla (STOKES , 1886). From the viewpoint of dispersed/flocculated biomass distribution, significant relationships between NTA-1 and total bacteria ratio, and dispersed and total biomass ratio were proved in the systems without high concentrations of ciliates. The ciliate concentrations reaching 10⁴ ml⁻¹ stabilized flocculated biomass growth without directly affecting NTA-1 portion. Using fluorescently labelled NTA-1 bacteria, filter feeding rates of ciliates were evaluated (maximum individual uptake rate upon NTA-1 bacteria as a number of bacteria per ciliate per hour being 120 h⁻¹ and 260 h⁻¹ under ciliate division rate of 0.3 day⁻¹ and 1 day⁻¹, respectively). Biomass balance showed that dispersed NTA-1 bacteria should not serve as the sole feeding source for these free-swimming ciliates. The role of diversity of mixed bacterial diet in ciliate growth and the role of ciliate predation in stabilizing bacterial assemblage structure was proved.     

A mechanism of transmission and factors affecting coral susceptibility to <Emphasis Type="Italic">Halofolliculina</Emphasis> sp. infection

Anecdotal evidence collected since 2004 suggests that infections caused by ciliates in the genus Halofolliculina may be related to coral mortality in more than 25 scleractinian species in the Caribbean. However, the relationship between the presence of ciliates and coral mortality has not yet been firmly established. Field and laboratory manipulations were used to test if ciliate infections harm corals, if ciliates are able to infect healthy colonies, and if coral susceptibility to ciliate infection depends on temperature, depth, distance to an infected colony, and the presence of injuries. Ciliate infections were always characterized by a visually detectable front of ciliates located on recently exposed coral skeletons. These infections altered the normal structure of the colony by causing tissue mortality (0.8 ± 0.95 cm month⁻¹, mean ± SD) and by delaying or preventing recovery from injuries. Under laboratory conditions, ciliates transmitted directly and horizontally from infected to healthy hosts, and coral susceptibility to ciliate infections increased with the presence of injuries. After invasion, the ciliate population grew, rapidly and after 8 d, produced tissue mortality on 32% of newly infected hosts. Thus, our results support the existence of a new Caribbean coral syndrome that is associated with tissue mortality, is infectious, and transmits directly and horizontally. Even though the role of ciliates in the development of lesions on coral tissues remains unclear, their presence is by far the most conspicuous sign of this syndrome; thus, we propose to name this condition Caribbean ciliate infection (CCI). Communicated by Biology Editor Dr Michael Lesser     

The Feeding Ecology of Actinophrys sol (Sarcodina: Heliozoa) in Chesapeake Bay

The occurrence of Actinophrys sol, a planktonic heliozoan, in Chesapeake Bay was monitored over a four-year period (1988–1991). Actinophrys sol was widely-distributed throughout Chesapeake Bay and could exceed densities of 5,000 cells liter ^?1. It was most abundant during the warmer months. Feeding experiments were conducted with field populations of heliozoa using 1-μm fluorescent microspheres to label ciliate prey. Two ciliates, a small Strobilidium sp. (30 μ in diameter) and a Pleuronema sp. (45 μ length), were the primary ciliate-prey items in the water column when the experiments were conducted, although a wide range of ciliate taxa was ingested. Two other ciliates not present in situ, a Cyclidium sp. (20 μ length) and a Uronema sp. (40 μ length), were also labeled and added at various concentrations to field populations of plankton containing A. sol. Heliozoan ingestion rates on in situ prey at concentrations of 30 Strohilidium and one Pleuronema ml^?1 were 0.2 to 0.3 prey heliozoan^?1 hour^?1. Ingestion rates increased to a maximum of 1.2 prey heliozoan ^?1 hour^?1 with additions of 100 Uronema ml^?1. A mean clearance rate of 0.15 ml heliozoan^?1 day^?1 did not change with increasing prey abundance. The abundance and distribution of A. sol suggests that these sarcodines may exert strong grazing pressure on the planktonic ciliate populations of Chesapeake Bay at certain times of the year, and may be important in shaping the ciliate community composition and distribution.     

Feeding response of a benthic copepod to ciliate prey type,prey concentration and habitat complexity

1. Protozoans are important consumers within microbial food webs and, in turn, they represent potential prey for small metazoans. However, feeding interactions within these food webs are rarely characterised and this is especially true for freshwater sediments. 2. We aimed to quantify the feeding links between a freshwater meiofaunal copepod and ciliates in two laboratory experiments. The first experiment addressed the response of Eucyclops serrulatus towards ciliate density and type (two ciliate species of the same genus differing in terms of body size). A second experiment assessed the effect of habitat structure on feeding rates by introducing different structural complexity into the feeding arena. In contrast to the first experiment, which was run only for one time period, this experiment also tested three different total feeding times (4, 7 and 9 h). 3. Eucyclops serrulatus exhibited high ingestion rates, with 3–69 ciliates copepod^?1 h^?1 consumed depending on food concentration, food type and habitat complexity. Copepods exhibited a preference for the smaller ciliate when total ciliate concentration was low, but selected both ciliates equally when food concentrations were medium or high. However, at very high food concentration, Eucyclops preferred the larger ciliate (which was 1/3 of its own body size), suggesting that the longer handling times of the larger prey are rewarding when the large prey is present in high numbers. In terms of total numbers consumed, copepods fed on more small ciliates, but in terms of carbon units both ciliates were selected equally when total prey concentration was low or medium. However, copepods derived more carbon from the larger prey at high and very high prey concentrations (up to 0.7 μgC out of a maximum of 1.1 μgC copepod^?1 h^?1). Habitat complexity influenced the feeding of copepods when it was observed over time. 4. The copepod–ciliate link is well known from the pelagic zone of both marine and freshwater habitats. We have shown its potential importance within the benthos, where it can be influenced by food identity, food quantity and possibly by habitat complexity.     

Annual Changes of Abundance and Biomass of Planktonic Ciliates in the Gdańsk Basin,Southern Baltic

Seasonal changes in the species composition, abundance and biomass of planktonic ciliates were determined every 2–3 weeks at two sites of 30 m depth and one location of 105 m depth in the southwestern Gdańsk Basin between January 1987 and January 1988. A total of 40 ciliate taxa were observed during this period. Autotrophic Mesodinium rubrum dominated ciliate abundance and biomass: maximal values of 50 · 10⁻¹ ind. ^1-1 and 65 μg C 1⁻¹ were recorded. The annual mean biomass of M. rubrum comprised 6 to 9% of the annual mean phytoplankton biomass. The highest abundances and biomasses of heterotrophic ciliates were noted at all stations in the spring and summer in the euphotic zone with maximum values of 28 · 10³ ind. 1⁻¹ and 23 μg C 1⁻¹. Three ciliates assemblages were distinguished in the epipelagic layer: large and medium-size non-predatory ciliates, achieving peak abundance in spring and autumn; small-size microphagous ciliates and epibiotic ciliates which were abundant in summer, and large-size predacious ciliates dominating in spring. Below 60 m, a separate deep-water ciliate community composed of Prorodon-like ciliates and Metacystis spp. was found. The ciliate biomass in the 60–105 m layer was similar to the ciliate biomass in the euphotic zone. The heterotrophic ciliate community contributed 10 to 13% to the annual mean zooplankton biomass. The potential annual production of M. rubrum comprised 6 to 9% of the total primary production. Carbon demand of non-predatory ciliates, calculated on the basis of their potential production, was estimated to be equivalent to 12–15% of the gross primary production.     

Interactions between gnathiid isopods,cleaner fish and other fishes on Lizard Island,Great Barrier Reef

The rate of emergence of micropredatory gnathiid isopods from the benthos, the proportion of emerging gnathiids potentially eaten by Labroides dimidiatus, and the volume of blood that gnathiids potentially remove from fishes (using gnathiid gut volume) were determined. The abundance (mean ±s.e .) of emerging gnathiids was 41·7 ± 6·9 m^?2 day^?1 and 4552 ± 2632 reef^?1 day^?1 (reefs 91–125 m²). The abundance of emerging gnathiids per fish on the reef was 4·9 ± 0·8 day^?1; but excluding the rarely infested pomacentrid fishes, it was 20·9 ± 3·8 day^?1. The abundance of emerging gnathiids per patch reef was 66 ± 17% of the number of gnathiids that all adult L. dimidiatus per reef eat daily while engaged in cleaning behaviour. If all infesting gnathiids subsequently fed on fish blood, their total gut volume per reef area would be 17·4 ± 5·6 mm³ m^?2 day^?1; and per fish on the reefs, it would be 2·3 ± 0·5 mm^?3 fish^?1 day^?1 and 10·3 ± 3·1 mm³ fish^?1 day^?1 (excluding pomacentrids). The total gut volume of gnathiids infesting caged (137 mm standard length, L_S) and removed from wild (100–150 mm L_S) Hemigymnus melapterus by L. dimidiatus was 26·4 ± 24·6 mm³ day^?1 and 53·0 ± 9·6 mm³ day^?1, respectively. Using H. melapterus (137 mm L_S, 83 g) as a model, gnathiids had the potential to remove, 0·07, 0·32, 0·82 and 1·63% of the total blood volume per day of each fish, excluding pomacentrids, caged H. melapterus and wild H. melapterus, respectively. In contrast, emerging gnathiids had the potential of removing 155% of the total blood volume of Acanthochromis polyacanthus (10·7 mm L_S, 0·038 g) juveniles. That L. dimidiatus eat more gnathiids per reef daily than were sampled with emergence traps suggests that cleaner fishes are an important source of mortality for gnathiids. Although the proportion of the total blood volume of fishes potentially removed by blood‐feeding gnathiids on a daily basis appeared to be low for fishes weighing 83 g, the cumulative effects of repeated infections on the health of such fish remains unknown; attacks on small juvenile fishes, may result in possibly lethal levels of blood loss.     

Sediment rejection by reef corals: The roles of behavior and morphology in Montastrea cavernosa (Linnaeus)

The sediment rejection abilities of colonies of Montastrea cavernosa (Linnaeus) were monitored in a series of field and laboratory experiments. Under conditions of natural sediment deposition, colonies were capable of removing virtually all sediment from their surfaces. Equivalent sections of dead coral skeleton accumulated as much as 345 mg sediment · 25 cm^?2 · day^?1. Laboratory experiments show the sediment rejection process to consist of passive and active phases. Passive movement of sediment off colonies occurs at the time of initial sediment impact. Fine grain size, tall polyps, and convex colonies all enhance passive removal. Active removal involves the behavioral responses of the colony and is independent of sediment type or colony morphology. The presence of appropriate morphologies can increase the proportion of sediment passively removed and reduce the amount of work a colony must perform to keep its surface clear of sediment.     

Intestinal ciliate composition found in the feces of the Turk rahvan horse Equus caballus, Linnaeus 1758

Species composition and distribution of large intestinal ciliates were investigated in the feces from 15 Turk rahvan horses, living in the vicinity of Izmir, Turkey. Twenty-two ciliate genera consisting of 36 species were identified. This is the first report on intestinal ciliates in Turk rahvan horses and no previously unknown species were observed. The mean number of ciliates was 14.2 ± 13.9 × 10⁴ cells ml⁻¹ of feces and the mean number of ciliate species per host was 9.9 ± 7.1. No ciliates were observed in 2 horses. Bundleia and Blepharocorys were considered to be the major genera since these ciliates were constantly found in high proportions. In contrast, Paraisotricha, Didesmis and Gassovskiella were only observed at low frequencies. The ciliates found in this survey had almost the same characteristics as those described in previous reports, suggesting that there was no significant geographic variation in the intestinal ciliate fauna of equids.     

Growth and survival of peritrich ciliates in an urban stream

Summary A computerized system was devised to trace the attachment, growth and disappearance of peritrich ciliates in an urban river. By tracing the development of each Carchesium polypinum colony in the river, it was possible to estimate the actual growth rate of this species without considering the effect of immigration. The survival and colonization rates of the colonies and individuals of solitary species could also be estimated. C. polypinum showed high growth rates (r=1.370 day^-1, doubling time 12.14 h). The number of daily colonizers also increased at a high rate, and the combination of growth and colonization caused very high population increase rates at the area level. Because of its low survivorship, the rate of Vorticella microstoma increase was much lower than previously reported. The survival of solitary species and small colonies was lower than with large colonies, and fewer new colonizers survived with the development of the attached microbial community.     

Predation on ciliates by freshwater calanoid copepods: rates of predation and relative vulnerabilities of prey

• 1 The susceptibility of ciliates in a mesotrophic lake to predation by Epischura lacustris, Diaptomus minutus and D. pygmaeus was assessed during summer. Oligotrichs, particularly Strobilidium velox (c. 43 μm), were removed efficiently by adult copepods and contributed substantially to the diet of female D. minutus. The presence of approximately 1,6 adult Epischura 1-^?1, or sixteen adult female Diaptomus 1-^?1, could halt the growth of S. vechx populations in summer.
• 2 Factors affecting the rate at which copepods prey on ciliates were examined in experiments with D. pygmaeus and cultured ciliates. Rate of predation on S. velox, the preferred species, became saturated at 5 S. velox ml^?1 (45ngCml^?1) and did not change with a 10-fold increase in alternative algal food.
• 3 Behavioural differences among ciliates, and the presence of other ciliates, contributed to differences in ciliate susceptibility to predation and suggest reasons why rates of removal of ciliates are not related to ciliate size.
• 4 By feeding selectively, at high rates, calanoids may suppress populations of some ciliates and thereby influence microzooplankton community structure.

     

Intestinal ciliate composition found in the feces of the Cypriot wild donkey,Equus asinus Linnaeus, 1758

Species composition and distribution of large intestinal ciliates was investigated in the feces from 13 Cypriot wild donkeys, free-living in the Karpaz national park, Northern Cyprus. We identified 16 ciliate genera and 22 species. This is the first report on intestinal ciliates in Cypriot wild donkeys, and no endemic species were observed. The genus Cycloposthium occurred in all animals. The mean number of ciliates was 3.0±2.5×10⁴ cells ml^?1 of feces and the mean number of ciliate species per host was 6.5±4.8. Characteristics of the wild donkey ciliates was almost identical to those reported in other equids from various regions around the world. We thus conclude that there is no pronounced geographic variation in the intestinal ciliate fauna of equids.     

Prevalent Ciliate Symbiosis on Copepods: High Genetic Diversity and Wide Distribution Detected Using Small Subunit Ribosomal RNA Gene

Toward understanding the genetic diversity and distribution of copepod-associated symbiotic ciliates and the evolutionary relationships with their hosts in the marine environment, we developed a small subunit ribosomal RNA gene (18S rDNA)-based molecular method and investigated the genetic diversity and genotype distribution of the symbiotic ciliates on copepods. Of the 10 copepod species representing six families collected from six locations of Pacific and Atlantic Oceans, 9 were found to harbor ciliate symbionts. Phylogenetic analysis of the 391 ciliate 18S rDNA sequences obtained revealed seven groups (ribogroups), six (containing 99% of all the sequences) belonging to subclass Apostomatida, the other clustered with peritrich ciliate Vorticella gracilis. Among the Apostomatida groups, Group III were essentially identical to Vampyrophrya pelagica, and the other five groups represented the undocumented ciliates that were close to Vampyrophrya/Gymnodinioides/Hyalophysa. Group VI ciliates were found in all copepod species but one (Calanus sinicus), and were most abundant among all ciliate sequences obtained, indicating that they are the dominant symbiotic ciliates universally associated with copepods. In contrast, some ciliate sequences were found only in some of the copepods examined, suggesting the host selectivity and geographic differentiation of ciliates, which requires further verification by more extensive sampling. Our results reveal the wide occurrence and high genetic diversity of symbiotic ciliates on marine copepods and highlight the need to systematically investigate the host- and geography-based genetic differentiation and ecological roles of these ciliates globally.     

Low temperature constrains growth rates but not short-term ingestion rates of Antarctic ciliates

Low environmental temperature is a major factor affecting the feeding activities, growth rates, and growth efficiencies of metazooplankton, but these features are poorly characterized for most protistan species. Laboratory experiments were conducted to examine the growth and ingestion rates of cultured herbivorous Antarctic ciliates. Three ciliates fed several algal species individually at 0 °C exhibited uniformly low growth rates (<0.26 day^?1), but the algae varied substantially in their ability to support ciliate growth. Specific ingestion rate (prey biomass consumed per unit ciliate biomass per unit time) was strongly affected by ciliate physiological state (starved vs. actively growing). Starved cells ingested many more prey than cells in balanced growth during short-term (minutes-to-hours) experiment but did not grow faster, indicating temperature compensation of ingestion rate but not growth rate. Field experiments were also conducted in the Ross Sea, Antarctica, to characterize the feeding rates of ciliates in natural plankton assemblages. Specific ingestion rates of two dominant ciliates were an order of magnitude lower than rates reported for temperate ciliates, but estimated rates were strongly affected by prey abundance. Our data indicate that short-term ingestion rates of Antarctic ciliates were not constrained by low environmental temperature although overall growth rates were, indicating the need for caution when designing experiments to measure the ingestion rates of these species at low environmental temperature. We present evidence that artifacts arising from estimating ingestion in short-term experiments may lead to errors in estimating feeding impact and growth efficiencies that are particularly large for polar protists.     

Partitioning of the food ration of marine ciliates between pico- and nanoplankton

Food size-range for 13 species of Tintinnina and 18 species of Oligotrichina were studied using electronic particle counting and in situ observation of food vacuole contents. Tintinnids consume nanoplankton in the size range 2–20 μm. Oligotrichous naked ciliates consume particles in the size range 0.5–10 μm. Ciliates smaller than 30 μm take 72% picoplankton and 28% nanoplankton. For ciliates between 30 μm and 50 μm the proportions are reversed (30% pico- and 70% nanoplankton), while the larger ciliates (> 50 μm) take nanoplankton almost exclusively (95% nano- and 5% picoplankton). A seasonal study of total Oligotrichida grazing showed that natural particles were consumed at rates that varied from 1 to 20 μg C 1⁻¹ day⁻¹. This included between 1 and 38% of the bacterioplankton production and 9 to 52% of the nanoplankton production. In the N-W Mediterranean the total ciliate production varied from 0.4 to 8.2 μg C 1⁻¹ day⁻¹. Research supported by CNRS-PIROCEAN AIP-RTM-953146-GRECO P4 and by CNRS-UA 716 (FR), and by the University of Nice and by the CNRS-GRECO 88 (MLP)     

Colonisation and succession of marine biofilm-dwelling ciliate assemblages on biocidal antifouling and fouling-release coatings in temperate Australia

Ciliate assemblages are often overlooked, but ubiquitous components of microbial biofilms which require a better understanding. Ciliate, diatom and bacterial colonisation were evaluated on two fouling-release (FR) coatings, viz. Intersleek 970 and Hempasil X3, and two biocidal antifouling (AF) coatings, viz. Intersmooth 360 and Interspeed 5640, in Port Phillip Bay, Australia. A total of 15 genera were identified during the 10 week deployment. Intersleek 970 displayed the most rapid fouling by ciliates, reaching 63.3(± 5.9) cells cm^?2. After 10 weeks, all four coatings were extensively fouled. However, the toxicity of the AF coatings still significantly inhibited microbial fouling compared to the FR coatings. On all treatments, colonies of sessile peritrichs dominated the ciliate assemblage in the early stage of succession, but as the biofilm matured, vagile ciliates exerted more influence on the assemblage structure. The AF coatings showed selective toxic effects, causing significant differences in the ciliate species assemblages among the treatments.     

Abundance and biomass of heterotrophic microorganisms in Lake Tanganyika

1. This study focused on heterotrophic microorganisms in the two main basins (north and south) of Lake Tanganyika during dry and wet seasons in 2002. Bacteria (81% cocci) were abundant (2.28–5.30 × 10⁶ cells mL^?1). During the dry season, in the south basin, bacterial biomass reached a maximum of 2.27 g C m^?2 and phytoplankton biomass was 3.75 g C m^?2 (integrated over a water column of 100 m). 2. Protozoan abundance was constituted of 99% of heterotrophic nanoflagellates (HNF). Communities of flagellates and bacteria consisted of very small but numerous cells. Flagellates were often the main planktonic compartment, with a biomass of 3.42–4.43 g C m^?2. Flagellate biomass was in the same range and often higher than the total autotrophic biomass (1.60–4.72 g C m^?2). 3. Total autotrophic carbon was partly sustained by the endosymbiotic zoochlorellae Strombidium. These ciliates were present only in the euphotic zone and usually contributed most of the biomass of ciliates. 4. Total heterotrophic ciliate biomass ranged between 0.35 and 0.44 g C m^?2. In 2002, heterotrophic microorganisms consisting of bacteria, flagellates and ciliates represented a large fraction of plankton. These results support the hypothesis that the microbial food web contributes to the high productivity of Lake Tanganyika. 5. As the sole source of carbon in the pelagic zone of this large lake is phytoplankton production, planktonic heterotrophs ultimately depend on autochthonous organic carbon, most probably dissolved organic carbon (DOC) from algal excretion.     

Climate change-predicted shifts in the temperature regime of shallow groundwater produce rapid responses in ciliate communities

The ciliates living in a shallow groundwater system in southern Ontario, Canada were subjected to an in situ temperature manipulation over 14 months. Ciliates were collected from the bed surface of a small springbrook and from interstitial water collected at five depths beneath its surface. Mean temperature elevations established at each depth (?20, ?40, ?60, ?80, and ?100 cm) between the experiment's control and treatment blocks were 1.9, 3.5, 3.9, 3.8, and 3.6 °C, respectively, and were based on global warming projections for the region. In total, 160 species of ciliate belonging to 85 genera were identified. Overall, the treatment block had a higher density (6510±342 cells L^?1; ±1 SE) than the control (5797±237 cells L^?1), but densities were both vertically and longitudinally variable. Control densities decreased with depth, whereas treatment densities were more equal among depths. Total species richness showed no significant difference between blocks when combining all sampling dates and depths, although species composition changed. The ciliate community was dominated by small (15–50 μm), followed by medium (50–200 μm), and only a few large‐sized (>200 μm) species. Small ciliates contributed 82–97% of the total density. Small ciliates also contributed more to the treatment (94%) than the control block (88%). The most common ciliate feeding groups were bacterivores, omnivores, predators, and algae‐diatom feeders, with bacterivores being most dominant (83–99% of the total numbers collected). Ordination analyses revealed that ciliate distribution was strongly correlated with groundwater temperature, although dissolved oxygen level, concentrations of ammonia and nitrate, and depth also appeared to be influential. Peak densities of many species occurred in either the control or treatment blocks, but not in both. The benefits of using ciliates as a proxy for higher, much longer‐lived, eukaryotes in climate change studies are discussed.     

Synergetic microorganismic convection generated by Opercularia asymmetrica ciliates living in a colony as effective fluid transport on the micro-scale

Ciliates, being one of the main substrates in granular activated sludge (GAS) formation, are treated as a major factor in granulation process. Cilia beats of Opercularia asymmetrica provide a continuous nutrient flux, enhancing the colonization of bacteria on Peritrichia stalks. Given that the ciliates tend to live in colonies, the main focus of the present work was an analysis and comparison of the flow effects induced by a single ciliate and by a colony. Investigations of the flow generated by Opercularia asymmetrica were carried out using micro-particle image velocimetry with biocompatible seeding. The results obtained showed different flow structures for a single ciliate and a colony. Moreover, the synergetic work of Opercularia asymmetrica living in a colony is considered as effective fluid transport. Additionally, analysis of the shear and normal strain rates provided information on mixing phenomena within the fluid on the micro-scale. The influence of seeding substance concentration on the flow pattern was also studied.