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  • 1
    Online Resource
    Online Resource
    Diapause in Aquatic Invertebrates : Theory and Human Use. (2007)
    Dordrecht :Springer Netherlands,
    Details
    Keywords: Aquatic invertebrates -- Dormancy. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (275 pages)
    Edition: 1st ed.
    ISBN: 9781402056802
    Series Statement: Monographiae Biologicae Series ; v.84
    URL: https://ebookcentral.proquest.com/lib/geomar/detail.action?docID=301898
    DDC: 571.78512176
    Language: English
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of Metazoan Predators on Ciliates in Freshwater Plankton Communities (1997)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 44 (1997), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1997.tb05699.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Selective feeding and its effect on polymorphism and sexuality in the rotifer Asplanchna sieboldi (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 8 (1978), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. Campanulate females of A. sieboldi (clone 12C1) attack Asplanchna brightwelli and A. girodi much more readily than either the alga Volvox aureus or the rotifer Brachionus calyciflorus. Pre-feeding campanulates on B. calyciflorus prior to testing does not appreciably affect their response to this prey. Discrimination during feeding occurs immediately after the campanulate's corona contacts a potential food organism and is probably mediated by chemoreceptors. Once a food organism is attacked, the probabilities of it being captured and subsequently swallowed are high and similar for each of the four organisms tested.Since food organisms other than Asplanchna. such as V. aureus and B. calyciflorus, induce campanulates in this clone to produce cruciform, and thus frequently sexual, females in succeeding generations, a tendency of these campanulates to select congeneric prey would favour the maintenance of the campanulate morphotype and thus the continuation of parthenogenetic reproduction in the ensuing population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1978.tb01424.x
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  • 4
    Electronic Resource
    Electronic Resource
    Control of feeding behaviour and selective cannibalism in the rotifer Asplanchna (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 7 (1977), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. Feeding responses in campanulate females of Asplanchna sieboldi were induced with filtrates of homogenized saccate female clonemates, showing that such behaviour can be triggered entirely by chemical stimuli. The failure of campanulates to attack campanulate clonemates, however, probably cannot be explained by the tissue chemistry of these females – filtered and unfiltered homogenates of campanulates were as active as those of saccates—and appears to be a function of some property limited to the campanulate body surface.The roles of chemical and physical properties of food items in controlling feeding behaviour in Asplanchna and other rotifers are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1977.tb01681.x
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  • 5
    Electronic Resource
    Electronic Resource
    Susceptibilities of different-sized ciliates to direct suppression by small and large cladocerans (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 29 (1993), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 〈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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1993.tb00740.x
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  • 6
    Electronic Resource
    Electronic Resource
    Competition between Keratella cochlearis and Daphnia ambigua: effects of temporal patterns of food supply (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 25 (1991), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. Population growth rates and relative competitive abilities of the rotifer Keratella cochlearis f. tecta and the small-bodied cladoceran Daphnia ambigua were studied under different schedules of food addition but equal total food quantity (per 4-day interval). The initial population growth rate of Keratella was significantly affected by the feeding schedule and by the presence of competitors, while that of Daphnia was affected by neither factor. Population densities of both species tended to increase as the frequency of food addition increased.2. Daphnia suppressed and excluded Keratella from mixed-species cultures when food was provided intermittently at a high concentration, but it failed to exclude the rotifer when food was provided in a near-continuous supply at low concentration. Keratella had only a minor suppressive effect on Daphnia in all mixed-species treatments.3. Starvation experiments indicate that Daphnia is able to withstand food shortages for significantly longer periods of time than Keratella. These and other results indicate that the outcome of interspecific competition between these species may be influenced by me frequency and concentration at which food is supplied. Daphnia ambigua is competitively superior to K. cochlearis when food is concentrated or ‘pulsed’, but much less so when ambient food levels are chronically low. Patterns of food availability may have important effects in determining the relative abundance of rotifers and small cladocerans in natural zooplankton communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1991.tb00484.x
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  • 7
    Electronic Resource
    Electronic Resource
    Spatial and temporal variability in filament length of a toxic cyanobacterium (Anabaena affinis) (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 33 (1995), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. This study examines the distribution of Anabaena affinis filament lengths under natural conditions as a function of depth and season, and in the laboratory as a function of growth phase. Because Anabaena affinis is only toxic when consumed, both its filament length and position in the water column are important determinants of its potential impact on zooplankton populations.2. Star Lake (Norwich, Vermont, U.S.A.), a natural, eutrophic pond, remained thermally stratified throughout the Anabaena bloom. Filament number and length differed significantly with both sampling date and water depth. Most filaments occurred at 0.5 m, particularly at the height of the bloom. Throughout the entire water column average filament length decreased from approximately 0.53 mm in May to 0.14 mm in July. The shortest filaments occurred at the 2.5 m depth. Filament length distributions (combined for all depths) for 29 May, 12 June and 3 July, corresponding to the beginning, middle and end of the bloom, respectively, differed significantly among the three dates. These patterns most likely reflect variable growth conditions, both during the season and in the water column.3. In the laboratory, Anabaena filament length was affected by medium composition and growth phase. Filaments were significantly longer when grown in MBL than in ASM medium. Also, the average length of Anabaena filaments grown in MBL changed significantly as cultures aged; by day 13 filament length (2.01 ± 0.38 mm, mean ± SD) was twice that on day 0 (0.97 ± 0.71 mm). As cell concentration continued to increase, mean filament length gradually decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1995.tb00381.x
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  • 8
    Electronic Resource
    Electronic Resource
    Age-specific Chaoborus predation on rotifer prey (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 17 (1987), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. This is the first study to examine predator-prey interactions between Chaoborm instars and rotifer prey. The predatory behaviour of instars I–III of Chaoborus pimctipennis and the diet selectivity of instars I—IV feeding on rotifers were examined in the laboratory. Prey used in direct observations of predatory behaviour included a variety of rotifers (Symhacta pectlnata, S. ohUmga, Polyarthra remata, Asplanchna girodi, Keratella crassa, spined and unspined forms of Keratella cochlearis) and two crustaceans (Bosmitia longirostris, Mesocyclops edax nauplii.2. In general, strike efficiencies (percentage of strikes resulting in inges- tion) increased in successive instars I—III. Early instar (I and II) strike efficiencies were low when compared with other invertebrate predators. For a given instar. mean prey handling times varied among prey species more than strike efficiencies. Mean handling times for small, soft-bodied rotifers were lowest and those for wide, hard-bodied prey were highest.3. Instar I exhibited significantly greater selectivity for the small, soft- bodied S. obUmga than for the larger S. pectinata, hard-bodied K. crassa, and spined and unspined forms of K. cochlearis. Instars II—IV positively selected both the large and small Symhaeta species over all Keratella species. The relationship between Chaobortts selectivity and prey value (weight of prey per unit handling time) can be described by a power function. Ingestion rates of rotifers by older instars (III and IV) are among the highest reported for invertebrate predators.4. Rotifer vulnerability to Chaoborus predation probably depended on rotifer cuticle texture, body width, and hydrodynamic disturbances. Spined rotifers were not necessarily protected from Chaoborus predation because Chaohorus can manipulate and swallow them. Giguere et al.'s 1982) encounter rate model must be modified to predict encounter rates of slow-moving rotifer prey with Chaohorus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1987.tb01044.x
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  • 9
    Electronic Resource
    Electronic Resource
    Females from resting eggs and parthenogenetic eggs in the rotifer Brachionus calyciflorus: lipid droplets, starvation resistance and reproduction (2004)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 49 (2004), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. In the heterogonic life cycle of monogonont rotifers, amictic (female-producing) females develop from two types of eggs: fertilised resting (diapausing) eggs and parthenogenetic subitaneous eggs. Females hatched from resting eggs initiate clonal populations by female parthenogenesis and are called stem females. This study compares females from resting and parthenogenetic eggs that were produced under identical culture conditions and were of similar birth order.2. Newborn stem females had many more lipid droplets in their tissues than similar-sized, newborn females from parthenogenetic eggs. When neonates were stained with Nile Red and viewed under epifluorescent illumination, these droplets were shown to be sites of neutral-lipid storage products.3. Stem females had no posterolateral spines and short anterior spines, while their mothers and offspring in subsequent, parthenogenetic generations typically had long posterolateral spines and elongated anterior spines.4. Newborn stem females survived starvation significantly longer than newborn females from parthenogenetic eggs.5. When females from resting and parthenogenetic eggs were cultured from birth to death at a high food concentration, the reproductive potential (r day−1) of the stem females was significantly higher (0.82–0.88 versus 0.70), primarily because of egg production at an earlier age. The mean lifetime fecundity (Ro) of stem females was significantly greater than that of females from parthenogenetic eggs.6. Extensive lipid reserves should increase the ability of stem females to colonise new habitats. Firstly, compared with females from parthenogenetic eggs, stem females are more likely to experience starvation or food limitation. Resting eggs hatch in response to physical and chemical factors that are not directly related to food availability, and from sediments that may be far from food-rich surface waters. Secondly, when food is abundant, stem females have a greater reproductive potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01282.x
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  • 10
    Electronic Resource
    Electronic Resource
    Endogenous regulation of environmentally induced sexuality in a rotifer: a multigenerational parental effect induced by fertilisation (2002)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 47 (2002), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. Sexual reproduction in the heterogonic life cycle of many rotifers occurs when amictic females, which produce diploid eggs developing parthenogenetically into females, are environmentally induced to produce mictic females. Mictic females produce haploid eggs which develop parthenogenetically into males or, if fertilised, into resting eggs – encysted embryos which develop into amictic females after an obligatory diapause.2. A Florida strain of Brachionus calyciflorus was used to test the prediction that amictic females hatching from resting eggs (Generation 1), and those from the next few parthenogenetic generations, have a lower propensity to produce mictic daughters in response to crowding than those from later parthenogenetic generations. In 10 replicate clones, populations initiated by amictic females from generations 1, 5, 8, 12 and 18 were exposed to a standardised crowding stimulus, and the proportion of mictic females in the populations was determined. These proportions varied significantly across generations and clones. They were very low in the early generations and gradually increased to a mean of about 0.5 at Generation 12.3. The mechanism for the transgenerational plasticity in response to crowding is not known. One possibility is that resting eggs contain an agent from their fertilised mictic mother's yolk gland that prevents development into mictic females and is transmitted in increasingly low concentrations through successive parthenogenetic generations of amictic females.4. This parental effect may contribute to clonal fitness by ensuring that a clone developing from a resting egg will attain a higher population size through female parthenogenesis before maximising its commitment to sexual reproduction, even in the presence of a crowding stimulus from a high population density of other clones. Therefore, the number of resting eggs to which a clone contributes its genes should be maximised.5. The clonal variation in propensity to produce mictic females in this strain indicates genetic variation in the trade-off between maximising population growth via female parthenogenesis and increasing the probability of producing at least some resting eggs before local extinction from the plankton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2002.00900.x
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