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Digitale Medien

Effects of Metazoan Predators on Ciliates in Freshwater Plankton Communities (1997)

JACK, JEFFREY D. ; GILBERT, JOHN J.

Oxford, UK : Blackwell Publishing Ltd

The @journal of eukaryotic microbiology 44 (1997), S. 0

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ISSN: 1550-7408

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: . Ciliates are often important members of aquatic communities in terms of their biomass, productivity, trophic roles, or numerical abundance. The interaction of metazoan predators with ciliates will be mediated by a number of biotic factors, including the potential of ciliate populations for growth, the relative size of ciliates and metazooplankton, the species structure of the metazooplankton, and the defenses of ciliates. This paper reviews some of the recent laboratory an field data pertaining to these particular factor. Studies have generally shown that metazoans can reduce ciliate population growth rates, but this impact varies greatly with the ciliate and metazoans involved. Smaller ciliates are generally more vulnerable to metazoan predators than larger species, although this relationship will be affected by the defenses a ciliate may possess. The structure of the metazooplankton community itself will also affect ciliatemetazoan interactions. The suppression of ciliate populations by metazoans has important ecological consequences, and more study is needed to understand the interaction of these groups in aquatic systems.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1550-7408.1997.tb05699.x

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2

Digitale Medien

Susceptibilities of different-sized ciliates to direct suppression by small and large cladocerans (1993)

JACK, JEFFREY D. ; GILBERT, JOHN J.

Oxford, UK : Blackwell Publishing Ltd

Freshwater biology 29 (1993), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: 〈list xml:id="l1" style="custom"〉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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.1993.tb00740.x

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3

Digitale Medien

The effect of suspended clay on ciliate population growth rates (1993)

JACK, JEFFREY D. ; GILBERT, JOHN J.

Oxford, UK : Blackwell Publishing Ltd

Freshwater biology 29 (1993), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: 〈list xml:id="l1" style="custom"〉1 Renewed batch cultures of three algivorous and one bacterivorous ciliate showed that ciliate reproductive rates increase with increasing food concentration up to an asymptote. Maximum rm values for Strobilidium gyrans, Bursaridium difficile and Euplotes eurystomus feeding on the cryptomonad alga Rhodomonas minuta were 0.87, 0.86 and 0.45 day-1, respectively, while Paramecium aurelia feeding on the bacterium Enterobactor aerogenes had an rm of 0.40 day-1. B. difficile had a food threshold (rm= 0) of 0.38 μg Cml-1 and P. aurelia had a threshold of 1.6μg Cml-1.2 The presence of suspended fine (particle size 〈1 μm) and coarse (particle size 1–2μm) clay suppressed the half maximum reproductive rate of the ciliate Strobilidium gyrans by up to 69% but had no effect on B. difficile, E. eurystomus or P. aurelia. Populations of ciliates unaffected by clay may be released in situations where suspended particles negatively affect their metazooplankton predators and competitors.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.1993.tb00773.x

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4

Digitale Medien

Effects of the benthic suspension feeder Dreissena polymorpha on zooplankton in a large river (2000)

Jack, Jeffrey D. ; Thorp, James H.

Oxford, UK : Blackwell Science Ltd

Freshwater biology 44 (2000), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: 1. We conducted a series of in situ enclosure experiments to assess the impact of zebra mussels (Dreissena polymorpha) on the plankton of the Ohio River. Adult mussels were suspended in pelagic enclosures (‘potamocorrals’) at three densities (0, 1000, 2500 mussels per corral) and incubated for 6 days with daily plankton and physiochemical sampling.  2. The presence of adult zebra mussels was correlated with a shift in composition of the phytoplankton community and a severe reduction in some rotifers. The effects of zebra mussels on the larger zooplankton were taxon-dependent, but bacterial density showed no trend among treatments.  3. Zebra mussels may have significant negative impacts on zooplankton, which may in turn alter riverine food webs.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-2427.2000.00609.x

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5

Digitale Medien

Dietary effects on life history traits of riverine Bosmina (2005)

ACHARYA, KUMUD ; JACK, JEFFREY D. ; BUKAVECKAS, PAUL A.

Oxford, UK : Blackwell Science Ltd

Freshwater biology 50 (2005), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: 1. We compared growth, reproduction and life history characteristics of Bosmina raised on Ohio River seston versus a unialgal culture (Scenedesmus acutus), to assess potential nutritional constraints experienced by riverine populations.2. Bosmina grew well in both treatments during their juvenile stage. Analysis of variance showed that Bosmina growth prior to the start of reproduction did not differ significantly between the treatments. After the onset of reproduction Bosmina fed on Scenedesmus grew faster and exhibited higher fecundity than their counterparts fed river seston.3. Significant quantities of triacylglycerol (visible lipid droplets) were gradually accumulated in Bosmina fed on Scenedesmus. Visual lipid ovary indices were positively correlated with adult growth rate and fecundity and negatively correlated with longevity.4. Biochemical analysis showed that Scenedesmus had significantly greater total ω3, ω6 and polyunsaturated fatty acids (PUFA) whereas river seston had more eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Thus, in contrast to Daphnia, EPA and DHA do not appear to influence Bosmina growth or reproductive performance, but linolenic acid or total PUFA may be important.5. Comparatively weak performance by Bosmina feeding on river seston suggest that nutritional constraints may be important despite high particulate organic carbon and low C : N and C : P of river seston.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.2005.01379.x

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6

Digitale Medien

Rotifers as predators on small ciliates (1993)

Gilbert, John J. ; Jack, Jeffrey D.

Springer

Hydrobiologia 255-256 (1993), S. 247-253

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ISSN: 1573-5117

Schlagwort(e): Asplanchna ; Brachionus ; ciliates ; predation ; rotifers ; Synchaeta

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Clearance rates of Synchaeta pectinata, Brachionus calyciflorus and Asplanchna girodi on Tetrahymena pyriformis (46 µm in length) at a density of 10 cells ml−1, in the presence of algal food, were 2.5 to 6.1 ml rot.−1 day−1. Clearance rates of these rotifers were, respectively, about 2, 3, and 13 times lower on Strobilidium gyrans (58 µm in length) than on T. pyriformis, indicating that the saltations of S. gyrans are an effective escape response. Clearance rates of S. pectinata were considerably lower on Colpidium striatum (81 µm) than on S. gyrans, suggesting that S. pectinata may not be able to ingest ciliates of this size. S. pectinata had a clearance rate of 19 ml rot.−1 day−1 on S. gyrans at a density of 1.2 cells ml−1, in the absence of edible algal food. Rotifers may prey extensively on ciliates in natural plankton communities, ingesting 25 to 50 individuals in the 45–60 µm size range day−1.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00025845

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