Response of the Ciliates Fabrea salina and Condylostoma sp. to Different Salinities and Microalgal Feeds (original) (raw)
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Feeding With Various Microalgae The Salt “Loving” Ciliate Fabrea Salina in Normal Salinity of 35 ppt
International Journal of Food Science and Agriculture, 2019
In a laboratory study 6 microalgae species were tested as food for the extremely halotolerant ciliate Fabrea salina in salinity of 35 ppt. Rhodomonas salina was found to be the best food in terms of specific growth rate and generation time followed by Dunaliella salina and Asteromonas gracilis. Isochrysis galbana, Chlorella sp and Tetraselmis sp were found inferior to them. In order to get best results in 35 ppt, Fabrea salina should previously be acclimatized in salinities as low as 60 ppt at least (as compared to 90 ppt that is quite near to the salinities of above 100 ppt that are normal in the hypersaline ponds from where Fabrea is collected).
Use of Cell Cultures to Study the Interactions of Ciliates with Fish
Springer Science Reviews, 2013
How the ciliates of fish can be cultured and be used to study ciliate/fish interactions are reviewed. The culturing of ciliates is currently done in basal solutions based on either freshwater, seawater, or bodily fluids of vertebrates. These are supplemented either with bacteria, fish cells, or organic matter, which can be defined or more commonly undefined, with proteose peptone being a prominent example. Among pathogenic ciliates, the most difficult to culture has been Ichthyophthirius multifiliis. To contrast, Cryptocaryon irritans caused a similar disease and has been maintained successfully in co-cultures with fish cells. Pathogenic scuticociliates and tetrahymenas are more amenable to culture, and can be grown axenically. These cultures have been used to study pathogenic mechanisms and to screen drugs for their potential chemotherapeutic value. Ciliates may act directly on fish to cause disease, but may also influence fish health indirectly through their interactions with other types of fish pathogens, for example bacteria and fungi. For example, in culture Tetrahymena spp. have been shown to phagocytose pathogenic bacteria, Yersinia ruckerii, and microsporidia, Glugea hertwigi, where ciliates are not linked to disease, very different ciliate/fish interactions are possible. For some fish larvae, free-living ciliates are a source of nutrients. Large-scale cultures of both freshwater and marine ciliates have been achieved and could be a source of feed for fish larvae in aquaculture. Finally, ciliates have the potential to feed on fish carcasses and in doing so make nutrients available to the ecosystem. In the future cell cultures should be invaluable in studying these and other possible relationships between fish and ciliates. Keywords Ciliates Á Fish cell lines Á Culturing Á Media Á Fish pathogens Á Aquaculture
Marine Ecology Progress Series, 1995
The effect of the red tide dinoflagellate Gyrodinium aureolum on the growth of the tintinnid ciliate Favella ehrenbergii was studied The ciliate is unable to sustain growth with this alga as the only food source, Irrespective of concentration. Ciliate survival decreases at very high concentrations of G. aureolum probably due to toxic substances exuded from G aureolum to the medium. This assumption is supported by the fact that growth of the ciliate is not affected by even very high concentrations of a non-toxic dinoflagellate, Heterocapsa triquetra. However, direct attempts to demonstrate toxic effects of exudates, using filtrates of dense cultures of G. aureolum, failed. Growth and grazing experiments were also carried out in which the ciliate was fed mixtures of G, aureolum and H tliquetra at relatively low algal concentrations. The growth of the ciliate was unaffected until G. aul-eolum accounted for about 7 0 % of the total biomass. In cases where G. aureolum accounted for about 90% of the algal biomass, the growth rate of the ciliate was reduced by less than 25%. Grazing experiments demonstrated that F. ehrenbergii cannot selectively avoid ingestion of G. aureolum.
Bacterivory by pelagic choreotrichous ciliates in coastal waters of the NW Mediterranean Sea
Marine Ecology Progress Series, 1989
Ability of natural assemblages of pelagic ciliates to ingest bacteria was tested using fluorescently labeled bacteria (FLB) prepared from in situ bacterioplankton. Ciliate bacterivory was analysed both in freshly collected samples from the mouth of Vlllefranche Bay, NW Mediterranean Sea, and in 50 pm screened water held in 201 plastic carboys in the laboratory. In various experiments, from 23 to 97 "h of the choreotrich assemblage ingested FLB added In tracer amounts (2 to 4 X 105 FLB ml-'), with average clearance rates ranging from 14 to 308 nl cell-' h-' Very little ingestion of FLB was observed for other types of ciliates, e.g. did~nids and hypotrichs, seen in the samples. Specific clearance rates (on the basis of FLB ingested) of individual morphological types of ciliates was on the order of 0 6 to 4 X 104 body volumes h-' for larger choreotrichs, and up to 2 X 10' body volun~es h-' for the smallest choreotrichs. We estimated that it would b e possible for choreotrichs < 15 pm in size to grow at a rate of about 0.5d-' on a n exclusive diet of bacteria at a concentrat~on of 10' bacteria ml-l, but that the larger cdiates were obtaining less than 15 % of their food rations a s bacteria. These data are the first direct evidence that some pelagic ciliates can be consumers of heterotrophic bacterioplankton in meso-to oligotrophic seawater.
Growth and grazing on Prochlorococcus and Synechococcus by two marine ciliates
Limnology and Oceanography, 1999
The two most abundant marine autotrophic prokaryotes, Prochlorococcus and Synechococcus, often have different distributions in the ocean. For example, Synechococcus is restricted to the first 100 m, whereas Prochlorococcus extends much deeper in oligotrophic waters. This is in part explained by differences in adaptation to nutrient and light regimes. However, they could also be subjected to different predation rates. To explore this hypothesis, we compared the consumption of these two picoplankters by an algivorous ciliate, Strombidium sulcatum, and a bactivorous ciliate, Uronema sp. For both ciliate species, removal rates were higher, by a factor of 3 to 10, for Synechococcus compared to Prochlorococcus when prey items were presented alone or together. The growth of the two ciliates fed Synechococcus and/or Prochlorococcus also differed. S. sulcatum grew well on both prey items, whether alone or together, whereas Uronema sp. grew slowly when fed Synechococcus and very poorly when fed Prochlorococcus either alone or with Synechococcus. Our results suggest that Prochlorococcus may be less subject to ciliate predation than Synechococcus.
Algal Research, 2018
Large-scale production of microalgae for biofuels is often hampered by contamination of cultures with predators that feed on microalgae. An important group of predators are ciliates. Some species of marine microalgae in natural ecosystems are known to produce chemicals that act as deterrents against predators. In this study, we tested whether these chemicals (trans,trans-2,4-decadienal, dimethyl sulfoniopropionate (DMSP), glycine betaine and proline) as well as a chemical analogue (methyl 3-(methylthio)propionate or MMP) can be used to control contamination of cultures of the microalga Chlamydomonas by the predatory ciliate Sterkiella. All chemicals were capable of rapidly eradicating the ciliates from a contaminated Chlamydomonas culture, but at a higher dose also had a negative effect on the microalga. For each chemical an optimal dose was determined at which ciliates were controlled and losses in microalgal biomass productivity were minimized (0.13 mM decadienal, 4.75 mM DMSP, 10 mM MMP, 250-300 mM proline and 250-2 300 mM glycine betaine). In the case of DMSP, MMP and proline, biomass productivity was even the same as that of a non-contaminated culture. The chemicals were also effective against other ciliates (Stylonychia notophora, Oxytricha sp. and 2 different Paramecium species). These chemicals therefore have potential to be used as natural pesticides to control contamination of microalgal cultures by ciliates. Of all chemicals tested, DMSP and MMP are the most promising because they are effective at a relatively low dose and have a limited negative effect on microalgal productivity.
Marine Ecology Progress Series, 1990
Direct visual observations were made on the vacuole contents of the oligotrichous ciliate Strombidium cf. sulcatum fed 12 different types of food. These ranged in size from 0.6 to 11.9 pm and included one fluorescently labelled bacterium, 2 types of cyanobacteria and 9 species of algae. We determined (i) the turnover time of food vacuoles as a function of prey quality and size, (ii) rates of grazing and filtration, and volume-specific clearance as a functlon of prey quality and size, (iii) the food concentration threshold for effective food intake in S. sulcatum when fed different types of prey, and (iv) an optimal particulate food size for S. sulcatum. Our results indicate the shortest feeding turnover time (13.7 ? 2.2 min.) for 2.5 pm prey (Nannochloris sp.). The average number of prey per vacuole and the feeding rate increased with food size to reach a maximum for this flagellate. Feeding efficiency then decreased to zero for particles w i t h the size range 6.6 to 11.9 pm (Platymonas sp., Hymenomonas elongata). Finally, it 1s shown that for food particle concentrations comparable to those of oligotrophic marine environments (e.g. 0.1 to 0.2 ppm by volume) S. sulcatum depends on food particles measuring around 2.5 pm for growth.
Monoculture of the ciliate protozoan Euplotes sp. (Ciliophora; Hypotrichia) fed with different diets
Ciliate protozoa of the genus Euplotes commonly appears contaminating mass cultures of rotifers but also with potential to be used as live food in the larviculture of marine fish. To obtain a monoculture of Euplotes sp., three diets were tested: 1) microalgae Nannochloropsis oculata, 2) commercial diet for rotifers Culture Selco 3000, and 3) baker's yeast (Saccharomyces cerevisiae). The ciliates were inoculated at 10 ind. mL -¹. On day 5, protozoa densities in the groups fed the commercial diet (1,911.0 ± 248.7 ind. mL -¹) and the baker's yeast (2,600.0 ± 195.3 ind. mL -1 ) did not differ, but were higher than the group fed microalgae (2.0 ± 1.4 ind. mL -1 ) (p < 0.05). On day 6, the density in the group fed baker's yeast was higher (15,484.0 ± 1,164.9 ind. mL -¹) than in the groups fed microalgae (3.0 ± 1.4 ind. mL -¹) or commercial diet (11,287.0 ± 1,468.0 ind. mL -¹). An exponential growth curve was observed for the protozoa fed baker's yeast (R² = 0.992; p < 0.05) and commercial diet (R² = 0.979; p < 0.05). The microalgae diet did not result in satisfactory growth of the protozoan. Feeding baker's yeast or commercial rotifer's diet to a monoculture of Euplotes sp. can result in very high densities of this protozoan.
Marine Ecology Progress Series, 1986
Urcmema sp. of ca 12 X 5 p m and Euplotes sp. ca 20 X 10 pm were isolated from surface waters of the English Channel. The rapidly motile Uronerna sp. has a relative growth rate of 3.32 d-' and responds rapidly to the presence of bacterial food with a doubling time of only 5.01 h. Its mortality rate is 0.327 d-' and mortality time is therefore short at 50.9 h once the bacterial food resource has become h i t i n g . Uronema sp. therefore appears to be adapted to exploit transitory patches when bacterial prey abundance exceeds a concentration of ca 6 X 106 cells ml-'. In contrast, Euplotes sp. had a slower relative growth rate of 1.31 d-' and a doubling time of ca. 12.7 h, implying a slower response to peaks in bacterial food supply. The mortality rate of 0.023 d-' is considerably lower than In Uronema and mortality time is as much as 723 h. This suggests that, relative to Uronerna, the slower moving Euplotes has a more persistent strategy w h c h under the conditions of our experiment favours a stable e q u h b n u m wlth its food supply. Grazing activities of these 2 ciliates have an important influence on abundance and size-class structure of their bacterial prey. In the presence of both Uronema and Euplotes, there is some evidence of an initial removal of large rods and squat rods, followed by removal of the smaller cocci before the initial population of bacteria is consumed. This is followed by the appearance of a secondary bactenal assemblage which is associated only with the development of the grazlng chates and is dominated by small thin rods. Gross growth efficiency of Uronema and Euplotes is ca 27 and 19 '10 respectively. Hence as much as 73 to 81 % of the carbon ingested with the bactenal food is dissipated through respiration and excretion. Should this occur in natural euphotic waters this process may supplement the DOM release by primary producers. Extracellular DOM production by the ciliates may therefore be of major significance in the maintenance of the secondary population of bacteria, and emphasizes the close interdependence of ciliate predators and bacterial prey in rnicroheterotrophic food webs.