The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform

Da Rocha, Carlos Eduardo Falavigna - One of the best experts on this subject based on the ideXlab platform.

Stuart H Hurlbert - One of the best experts on this subject based on the ideXlab platform.

  • Short term experiments on calanoid-cyclopoid-phytoplankton interactions
    Hydrobiologia, 1991
    Co-Authors: Doris Soto, Stuart H Hurlbert
    Abstract:

    To investigate their potential effects on each other in nature, calanoid ( Diaptomus clavipes and D. siciloides ) and cyclopoid ( Acanthocyclops vernalis and Mesocyclops edax ) copepod populations were manipulated in 5 liter aquaria in laboratory experiments of 20–60 days duration. Diaptomus generally had a strongly negative effect on both cyclopoid species. The cyclopoids established populations more successfully when introduced to aquaria before calanoids than they did when calanoids were already present. On the other hand, whether introduced earlier or later than the cyclopoids, Diaptomus populations were unaffected by Acanthocyclops and were strongly depressed by Mesocyclops . Diaptomus effects on the phytoplankton were often strong but varied markedly among experiments. They included reduction of populations of edible algae, such as Chlamydomonas , which are essential for both calanoid and cyclopoid nauplii, and large increases in inedible algae, such as Kirchneriella . Feeding experiments revealed that under conditions of food scarcity Acanthocyclops nauplii survived less well than did Diaptomus nauplii. Competition for edible phytoplankton seemed to be a key factor in the calanoid-cyclopoid interactions, since the survival of herbivorous cyclopoid larvae determined the abundance of the predaceous adults. This indicates that the competitive effects of calanoids on cyclopoids often may exceed the predative effects of cyclopoids on calanoids.

  • Long-Term Experiments on Calanoid-Cyclopoid Interactions
    Ecological Monographs, 1991
    Co-Authors: Doris Soto, Stuart H Hurlbert
    Abstract:

    Zooplankton species composition was manipulated in an 8-mo long series of experiments in outdoor 450-L tanks. The first experimental stage evaluated the impact of cyclopoids (Mesocyclops, Microcyclops, Cyclops) and calanoids (Diaptomus) on each other. The second and third stages evaluated the effects of Daphnia and mosquitofish (Gambusia affinis) on the calanoid-cyclopoid interaction. Cyclopoid predation initially caused a 50-70% reduction in calanoid abundance. After a few months, however, cyclopoids caused >300% increases in calanoid abundance, ap- parently by preventing calanoid overexploitation of the phytoplankton. The presence of calanoids depressed cyclopoid abundance by up to 70-90%, presumably by diminishing the availability of edible phytoplankton to cyclopoid nauplii and of prey, such as rotifers, to cyclopoid adults. The presence of Daphnia depressed calanoid abundance, probably by reducing the phytoplankton abundance, but did not affect cyclopoid abundance, perhaps because cyclopoid adults could feed on items other than phytoplankters. Coequality (i.e., similarity in abundance) of closely related taxa was in 4 of 5 cases favored by the addition of a more distantly related taxon. Thus the addition of cyclopoids favored the coequality of two Diaptomus species (D. clavipes, D. siciloides), the addition of these Diaptomus species favored the coequality of two cyclopoid genera (Mesocyclops, Microcyclops), and the ad- dition of Daphnia favored coequality of cyclopoids and calanoids and coequality of the two Diaptomus species, but the dominance of Microcyclops over Mesocyclops. Effects of Gambusia included a drastic reduction of Daphnia populations, moderate reduction of calanoid populations, and negligible effects on cyclopoid populations.

Edward J. Maly - One of the best experts on this subject based on the ideXlab platform.

  • Differential Predation by Chaoborus americanus on Males and Females of Two Species of Diaptomus
    Canadian Journal of Fisheries and Aquatic Sciences, 1993
    Co-Authors: Jules M. Blais, Edward J. Maly
    Abstract:

    Feeding experiments were performed to determine relative feeding rates of fourth-instar Chaoborus americanus larvae (Diptera) on both sexes of two calanoid copepod species, Diaptomus leptopus and D...

  • Size divergence and dietary partitioning enhance coexistence of two herbivorous species of Diaptomus (Copepoda: Calanoida) in some shallow Quebec lakes
    Canadian Journal of Zoology, 1992
    Co-Authors: Patricia Chow-fraser, Edward J. Maly
    Abstract:

    We examined the vertical and horizontal distribution patterns of Diaptomus minutus Lilljeborg and Diaptomus oregonensis Forbes in several shallow Quebec lakes where they occurred allopatrically and sympatrically within a small geographic region. Both species overlapped extensively in their vertical and temporal distributions and were found to be positively associated within and among lakes. Although size displacement could not be detected when body lengths of sympatric and allopatric populations were compared, in lakes where there was a reduction in size overlap between species, the two species coexisted at relatively high densities. This contrasted with situations where convergence in size between species was accompanied by a limited abundance of one or both diaptomids. We conducted stomach-content analyses on the sympatric populations of two of these lakes to determine if diet preference was related to copepod size divergence, and if algae were selected as a function of copepod size. We found that D. mi...

Perbiche-neves Gilmar - One of the best experts on this subject based on the ideXlab platform.

Doris Soto - One of the best experts on this subject based on the ideXlab platform.

  • Short term experiments on calanoid-cyclopoid-phytoplankton interactions
    Hydrobiologia, 1991
    Co-Authors: Doris Soto, Stuart H Hurlbert
    Abstract:

    To investigate their potential effects on each other in nature, calanoid ( Diaptomus clavipes and D. siciloides ) and cyclopoid ( Acanthocyclops vernalis and Mesocyclops edax ) copepod populations were manipulated in 5 liter aquaria in laboratory experiments of 20–60 days duration. Diaptomus generally had a strongly negative effect on both cyclopoid species. The cyclopoids established populations more successfully when introduced to aquaria before calanoids than they did when calanoids were already present. On the other hand, whether introduced earlier or later than the cyclopoids, Diaptomus populations were unaffected by Acanthocyclops and were strongly depressed by Mesocyclops . Diaptomus effects on the phytoplankton were often strong but varied markedly among experiments. They included reduction of populations of edible algae, such as Chlamydomonas , which are essential for both calanoid and cyclopoid nauplii, and large increases in inedible algae, such as Kirchneriella . Feeding experiments revealed that under conditions of food scarcity Acanthocyclops nauplii survived less well than did Diaptomus nauplii. Competition for edible phytoplankton seemed to be a key factor in the calanoid-cyclopoid interactions, since the survival of herbivorous cyclopoid larvae determined the abundance of the predaceous adults. This indicates that the competitive effects of calanoids on cyclopoids often may exceed the predative effects of cyclopoids on calanoids.

  • Long-Term Experiments on Calanoid-Cyclopoid Interactions
    Ecological Monographs, 1991
    Co-Authors: Doris Soto, Stuart H Hurlbert
    Abstract:

    Zooplankton species composition was manipulated in an 8-mo long series of experiments in outdoor 450-L tanks. The first experimental stage evaluated the impact of cyclopoids (Mesocyclops, Microcyclops, Cyclops) and calanoids (Diaptomus) on each other. The second and third stages evaluated the effects of Daphnia and mosquitofish (Gambusia affinis) on the calanoid-cyclopoid interaction. Cyclopoid predation initially caused a 50-70% reduction in calanoid abundance. After a few months, however, cyclopoids caused >300% increases in calanoid abundance, ap- parently by preventing calanoid overexploitation of the phytoplankton. The presence of calanoids depressed cyclopoid abundance by up to 70-90%, presumably by diminishing the availability of edible phytoplankton to cyclopoid nauplii and of prey, such as rotifers, to cyclopoid adults. The presence of Daphnia depressed calanoid abundance, probably by reducing the phytoplankton abundance, but did not affect cyclopoid abundance, perhaps because cyclopoid adults could feed on items other than phytoplankters. Coequality (i.e., similarity in abundance) of closely related taxa was in 4 of 5 cases favored by the addition of a more distantly related taxon. Thus the addition of cyclopoids favored the coequality of two Diaptomus species (D. clavipes, D. siciloides), the addition of these Diaptomus species favored the coequality of two cyclopoid genera (Mesocyclops, Microcyclops), and the ad- dition of Daphnia favored coequality of cyclopoids and calanoids and coequality of the two Diaptomus species, but the dominance of Microcyclops over Mesocyclops. Effects of Gambusia included a drastic reduction of Daphnia populations, moderate reduction of calanoid populations, and negligible effects on cyclopoid populations.