Profile. Source of taxon data: Ciliates; Latest Taxonomic scrutiny: W. Petz on Jun; Reference Site/Paper in which the taxon name was checked: Petz, W. Taxon identifier, Scientific name, Euplotes sp. Taxonomy navigation. Up › unclassified Euplotes. Down Terminal (leaf) node. Common name, -. Abstract: The locomotory and feeding responses of a Euplotes sp. to attached However, surface clearance rates for Euplotes sp. grazing on V. natriegens and.
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The effect on protist grazing of diel variation of carbon to nitrogen ratio C: N in algal prey was investigated using the dinoflagellate Lepidodinium sp. Both predator and prey cultures were maintained in light: Grazing experiments were conducted near the end of light light experiment and dark dark experiment phase with the algal prey in the same and opposite phases provided as mono-diets.
In all experiments, prey at the end of light phase day prey possessed higher C: N than prey at the eupltes of dark phase night prey. Grazing rates in the light experiments were higher than in the dark experiments for both predators. Grazing rates and C ingestion rates IRs on day prey were higher than that on night prey for both predators.
However, similar N IRs on day and night prey were observed in Lepidodinium sp. In addition to imposing a top-down control on phytoplankton biomass, microzooplankton grazing plays a role in shaping the composition of the phytoplankton community Landry et al. Further, microzooplankton grazing is regarded as an important mechanism euplotess dissolved organic carbon DOC production and nutrient regeneration Nagata, For example, it was observed that the production of DOC by the grazing of protists and copepods was higher than that from direct algal release, signifying the importance of the grazing processes in stimulating bacterial growth and eulotes cycling of carbon and nutrients Strom et al.
Food selectivity of protists is often concentration-dependent, i. Furthermore, different behavior of selectivity among protists with different feeding mechanisms has been reported Boenigk and Arndt, Among the prey properties that affect protist grazing preference, size euploges regarded as a primary physical constraint deciding the capability and efficiency of prey consumption for a specific predator.
For example, bacteria are usually too small to be captured efficiently by the maxillae of filter-feeding copepods. Phagotrophic protists are generally only able eupoltes ingest prey particles smaller than themselves Hansen et al.
Specific size relationships of predator and prey, i. Comparing to the effect of prey size, the effect of food nutritional quality on protistan grazing is being increasingly studied John and Davidson, ; Shannon et al. Studies have consistently suggested selectivity toward prey of higher food quality, those possessing lower carbon to nitrogen ratio C: On the contrary, inconsistent results have been reported among studies that used mono-diets of an algal prey of contrasting C: It was observed in two previous studies that euuplotes flagellates Paraphysomonas vestita and Ochromonas danica exhibited higher grazing activity eupllotes low C: N prey when they were provided with mono-diets of contrasting C: N euplotex John and Davidson, ; Shannon et al.
However, other studies reported opposite findings Grover and Chrzanowski, ; Siuda and Dam, ; Chrzanowski and Foster, For example, two recent studies have demonstrated that the ciliate Strombidinopsis sp. N than on N-replete low C: N algal and bacterial prey, respectively, Grover and Chrzanowski, ; Siuda and Dam, A similar result was observed in another recent study on the flagellate O.
N prepared from a matrix of 15 species and two euplites phases mid-exponential and late-stationary Chrzanowski and Foster, This increasingly observed higher protist ingestion on prey with lower food quality when they were provided as the only food source is in euplptes to that observed in mesozooplankton Hillebrand et al.
Diel variation in microzooplankton grazing has been reported Wikner et al. For example, a mechanism of light-aided digestion of algal prey was suggested to enhance the feeding rate of protists on phytoplankton prey under conditions of food saturation where prey digestion becomes a rate-limiting step in the prey consumption process Strom, In addition, a circadian rhythm of grazing activity was observed in several species of ciliate and dinoflagellate, where a diel rhythm of feeding was observed in 24 h darkness after previous exposure to diel light-dark cycle Jakobsen and Strom, Less studied has been the potential effect of diel variation of the algal prey properties on the diel rhythmic grazing of protists Ng and Liu, Diel periodicity in phytoplankton physiology has been well documented Prezelin, ; Vaulot and Marie, Among various physiological characteristics, the respective increasing and decreasing of cellular C: Euployes during day and night was reported in some phytoplankton species Stramski and Reynolds, ; Clark et al.
This interspecific characteristic in phytoplankton is based on the strong diel variation of C metabolism, with increase of algal C during day due to photosynthetic C euployes and decrease during night due to respiration, in contrast to the relatively small diel variation in assimilation of N DiTullio and Laws, ; Jauzein et al. While a feeding response to C: N of prey in protists has been reported in various studies John and Davidson, ; Shannon et al. N in algal prey would have an effect on the diel feeding behavior of protists.
This study aims at investigating the effect of euplohes varying C: N in algal prey in the diel cycle on the diel grazing rhythm of protists, using the dinoflagellate Lepidodinium sp. Both dinoflagellates and ciliates are regarded as major grazers in microbial food webs in marine systems Levinsen and Nielsen, ; Calbet, ; Jeong et al.
A dinoflagellate Lepidodinium sp. An additional set of prey cultures was maintained under the same growing conditions as described above but in a reversed This additional set of prey cultures was adapted to the reversed light-dark cycle for at least 8 weeks before the experiments were conducted. To characterize the predator—prey relationship of the two pairs of predators and prey, a curve of predator growth rate against different prey concentration was obtained for each pair.
Briefly, the predators were incubated with different initial prey concentrations for 2 days with the predators acclimated to the respective prey 1 week before the incubation.
Predators were counted at the beginning and end of incubation to obtain the predator growth rates.
WoRMS – World Register of Marine Species – Euplotes O.F. Müller,
The predators Lepidodinium sp. Pure cultures of the two predators were obtained from single cell isolation and were maintained in autoclaved filtered 0.
Predator cultures were subcultured to fresh autoclaved seawater every month, with algal food replenished every week. Species identification was carried out microscopically together with duplotes s rDNA sequencing. Briefly, for 18 s rDNA sequencing, predator cultures were left unfed for a week to minimize the presence of prey. MH and Lepidodinium chlorophorum and Euplotes sp. Rocke and Liu, Diel grazing experiments were conducted with the two predator—prey pairs, namely Lepidodinium sp.
Three experiments were carried out for each predator—prey pair with identical experimental procedures. From 1 week before each experiment, frequency of food replenishment to the euplltes cultures was increased to once per 1 or 2 days to ensure sufficient food supply for the exponential growth of the predators.
Each diel grazing experiment included two sections, one during the last hours of the light period light experiment and the other during the last hours of the dark period dark experiment. The timing of the experiments were chosen as such so that prey cells with the highest contrast of C: N in the diel cycle could be simultaneously available Ng and Liu, Before carrying out each grazing experiment i.
After the filtration process, microscopic examination was carried out to verify that ap swimming behavior and motion of predators were normal.
Prior testing has also shown that the growth of predators resumed upon replenishment of maintenance prey after the filtration treatment, hence ensuring the filtration process did not affect the grazing capability of the predators.
The relatively prey-free predator cultures were then used for the experimental setup. The experimental setup consisted of grazing treatments triplicate with the predators provided with mono-diets of exponentially growing prey in late light day prey and late dark night prey phases, together with the respective prey-only control treatments.
The predators were distributed into 50 mL polypropylene centrifuge tubes Falcon and autoclaved filtered 0. Rough estimation of prey and predator abundances for the experimental setup was achieved with a flow cytometer FCM and a Coulter Counter, respectively see below for details.
The experimental tubes were then incubated for 3 h under the same conditions i. Samples 1 mL for FCM analysis were taken at eupplotes beginning and end of the experiments for prey enumeration. Samples for determination of cellular carbon and nitrogen contents of prey and predators were prepared at the beginning of the experiments.
Three additional batch cultures in exponential phase of each alga were prepared in tandem with spp feeding experiments to monitor whether the C: N of the prey changed significantly during the 3 h incubation under opposite phasing condition. Samples for determination of cellular carbon and nitrogen contents of the algae were prepared at the beginning and end of incubation.
Cytograms were analyzed with the CellQuest software version 6. Samples were diluted with filtered 0. Initial prey abundances were calculated by multiplying the cell concentration of the prey culture sample for each experiment with respective volumetric proportion of added prey culture in each experimental tube.
Euplotes Sp. Ciliates
Statistical analysis with a mixed effect model and analysis of variance ANOVA was conducted with the software R version 2. N of prey on protist grazing, with the assumptions of ANOVA validated by examining the diagnostic plots of the residuals Galwey Growth rate of Lepidodinium sp.
Initial concentrations of day prey and night prey in light and dark grazing experiments of the predator—prey pairs Lepidodinium sp. Variation of initial cellular carbon to nitrogen molar ratio C: N in the grazing experiments A ps, B and average C: N during incubation of cells from the additional batch cultures CD of the green algae D. Labels on the x -axis indicate the experiment treatments.
Error bars indicate standard errors. Variation of initial cellular carbon AC and nitrogen BD in the grazing experiments of algal prey D. See caption of Fig. Variation of average cell volume during incubation of the green algae D. Effect of time of day day or night on cellular properties of the green algae D.
N in the grazing experiments Init C: Naverage C: N during incubation of cells from the additional batch cultures Ave C: N and average cell volume during incubation in the grazing experiments Cell vol.
A, B and ciliate grazer Euplotes sp. Fixed factors examined include the time of experiment Time light or dark and carbon to nitrogen molar ratio of prey C: