The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
D. Allen Rutherford - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of cladoceran and copepod communities in floodplain habitats of the Atchafalaya River Basin
Hydrobiologia, 2000Co-Authors: Norman L. Davidson, William E. Kelso, D. Allen RutherfordAbstract:In the summer of 1994, floodplain habitats of the Atchafalaya River Basin were surveyed for cladocera and copepoda. Collection sites were grouped into three distinct habitat types (black-water, brown-water and green-water) based on a principal components analysis of five hydrographic variables (current velocity, Secchi disk depth, surface percent saturation of dissolved oxygen, dissolved oxygen differential and surface water temperature). An ANOVA of four community indices (total abundance, Shannon–Weiner diversity (H'), richness, and evenness) was performed on both cladoceran and copepod communities among the three floodplain habitats. Common species were compared among habitats (χ^2 goodness-of-fit) to determine where they were most abundant. Green-water habitats had the greatest overall abundance of cladocerans and copepods (dominated by Diaphanosoma birgei , Moina micrura and Mesocyclops edax ), but ranked lower in diversity and evenness than black-water and brown-water habitats where Ilyocryptus spinifer , Simocephalus serrulatus , Macrocyclops albidus (black-water) and Bosmina longirostris and Acanthocyclops vernalis (brown-water) were most abundant, respectively. These results indicate that the mosaic of floodplain habitats within large temperate river systems support unique zooplankton communities, and that these habitats are largely a function of seasonal hydrographic features.
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Relationships between environmental variables and the abundance of cladocerans and copepods in the Atchafalaya River Basin
Hydrobiologia, 1998Co-Authors: Norman L. Davidsonjr., William E. Kelso, D. Allen RutherfordAbstract:The relationship of species abundance to eight environmental variables was tested for 24 common species of crustacean zooplankton collected in the Atchafalaya River Basin during the summer of 1994. Stepwise regressions (α = 0.05) revealed significant relationships between zooplankton abundance and at least one environmental variable for 18 species ( R2 = 0.14-0.61, p < 0.0435-0.0001). The majority of these species' peak abundances were correlated with variables indicative of seasonal changes in floodplain habitat, as the Atchafalaya river receded, water temperature increased, and/or phytoplanktonic photosynthesis increased. Surface water temperature and the percent saturation of dissolved oxygen showed the most significant relationships, but specific conductance, current velocity, and Secchi disk depths were also related to abundance patterns of certain taxa. A principal components analysis of species abundances provided further insight into the partitioning of temporally-distinct zooplanton assemblages, showing that several species ( Bosmina longirostris, Daphnia parvula, Eurytemora affinis, and Ceriodaphnia quadrangula) predominated during early summer, and were supplanted by a distinct late-summer assemblage ( Diaphanosoma birgei, Moina micrura, Mesocyclops edax, and Daphnia lumholtzi) as time progressed. The transitional assemblage was dominated by Simocephalus serrulatus, Macrocyclops albidus, Microcyclops rubellus, and Thermocyclops inversus, all of which were most abundant in the hypoxic conditions characteristic of the latter stages of the Atchafalaya River flood-pulse.
Teruo Ishida - One of the best experts on this subject based on the ideXlab platform.
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Copepods in the Mountain Waters of Kyushu, Tsushima
2015Co-Authors: Teruo Ishida, Eucyclops Sermlutus, Paracyclops Fimbriatus, Diacyclops Languidus, Mesocyclops Leuckaarti, Kyushu TsushimaAbstract:This report is a result of a faunistic study on the copepods gathered-by the author from the mountain waters of Kyushu, Tsushima I. and Ryukyu Is. (Fig. 1, 13 samples, April 1987 to March 1989). Having examined these specimens, I was able to determine 17 species of cyclopoids and 16 species of harpacticoids. Nine of the harpacticoid species (Ishida 1987) are common to Hokkaido, and 13 (Ishida 1989a) to Honshu. Of these species I remark on the distribution and habitats, and offer some illustrations for diagnosis. The methods of sampling in the fields and sorting in the laboratory are same as those The following species were found in the samples examined: reported in my previous report (Ishida 1987). Number of individuals obtained C yclopoida 1. Halicyclops sp. 2. Macrocyclops fuscus (Jurine) 3. Macrocyclops albidus (Jurine) 4. Macrocyclops sp. 5. Ectocyclops phaleratus (Koch
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Freshwater copepods from the east coast of the Kamchatka Peninsula, Russia
Journal of Marine Systems, 1998Co-Authors: Teruo IshidaAbstract:Detritus samples collected from freshwaters of the east coast of the Kamchatka Peninsula yielded 10 species of cyclopoid and 7 species of harpacticoid copepods, as follows: Macrocyclops albidus, Eucyclops serrulatus, E. speratus, Cyclops scutifer, Megacyclops viridis, Acanthocyclops vernalis, A. robustus, Diacyclops bicuspidatus, and Mesocyclops leuckarti; Attheyella nordenskjoldi, Maraenobiotus brucei, Epactophanes richardi, Moraria duthiei, Bryocamptus hiemalis, B. calvus, and B. umiatensis. Morphological variations of specimens from Alaskan and Japanese populations were examined. Elongation of the caudal rami of Eucyclops speratus and Diacyclops bicuspidatus, and fusion of the antennular articles of the latter species are noticeable.
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Planktonic cyclopoid copepods from small ponds in Kyushu, Japan. I. Subfamily Eucyclopinae with descriptions of micro-characters on appendages
Hydrobiologia, 1996Co-Authors: Hiroshi Ueda, Teruo Ishida, Jun-ichi ImaiAbstract:Four cyclopoid copepods of Eucyclopinae, Macrocyclops albidus, Eucyclops cf. serrulatus, E. cf. speratus and Tropocyclops prasinus , are described from small ponds in Kyushu. Special attention was paid to spinules on the appendages. Macrocyclops albidus and E. cf. serrulatus have some differences in those spinules from European forms described in previous studies. The Japanese E. serrulatus-speratus group probably consists of more than two species. Tropocyclops prasinus is identical to the description by Gurney (1933) in micro-characters but differs in setal lengths of the legs.
Victor Alekseev - One of the best experts on this subject based on the ideXlab platform.
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Taxonomic analysis of species characters for copepodid instars 4 and 5 of the subfamily Eucyclopinae of European Russia
Hydrobiologia, 2000Co-Authors: Victor AlekseevAbstract:Morphological characters useful for taxonomic identification of older copepodid instars of the subfamily Eucyclopinae were studied among 14 species of Eucyclops, Macrocyclops, Ectocyclops, Paracyclops and Tropocyclops known from European Russia. For taxonomic analysis, the following elements of copepodid morphology were chosen: armament and proportion of furcal rami; morphology of swimming legs and reduced 5th and 6th legs; antennule segmentation; and relative body length of copepodid instars in comparison with the female length. Changes in morphology of major copepodid instars of the subfamily Eucyclopinae during ontogenetic development are traced and noticeable differences among five genera and 14 species are described. These differences among major copepodid stages may be important for both taxonomic and ecological analysis. For taxonomy, they provide information on development of sexes and species during maturation. For ecology they allow identification of the specimens at 4–5 copepodid instars in diapause. A key to major copepodid instars of the species from the subfamily Eucyclopinae which are known from limnetic habitats of the European part of Russia is presented.
I. T. Van Der Veen - One of the best experts on this subject based on the ideXlab platform.
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Costly carotenoids: a trade‐off between predation and infection risk?
Journal of evolutionary biology, 2005Co-Authors: I. T. Van Der VeenAbstract:Carotenoid reserves in copepods seem costly in terms of predation risk because they make individuals conspicuous. However, carotenoids also seem to play an important role in immune defence as free radical scavengers. To test whether predation risk influences carotenoid levels and whether changes in carotenoid levels are related to changes in immune defence, I examined individual changes in large carotenoid and other lipid droplets upon exposure to predation risk and subsequent exposure to parasites in the copepod Macrocyclops albidus. Copepods reduced carotenoid reserves upon exposure to predators, through which they potentially avoided the costs of being conspicuous under predation risk. Thus, the size of carotenoid reserves is a plastic trait. Such a decrease in carotenoid reserves may also have a negative impact on the copepods’ immune system as individuals that decreased their reserves suffered higher parasite prevalence upon exposure to the cestode Schistocephalus solidus. These results suggest that carotenoid reserves may be individually optimized to trade-off each individual's unique costs (predation risk) and benefits (immune defence) of having these reserves.
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Is body size or activity of copepods related to ingestion of parasite larvae?
Parasitology, 2003Co-Authors: I. T. Van Der VeenAbstract:This study shows that ingestion of Schistocephalus solidus coracidia was related to general activity of Macrocyclops albidus copepods at the time of exposure. The lower the activity of the host, the fewer parasites it ingested. In an earlier study it was shown that large M. albidus copepods were less likely to become infected with S. solidus than small copepods, which could potentially be caused by differential ingestion of parasites. However, the current study did not show any evidence for such an effect arising through differential ingestion. Body size was not related to ingestion of parasites, but was positively correlated to activity. So, even though size did not significantly relate to ingestion of parasites, if anything, through their higher activity large copepods rather than small copepods may have ingested more parasites. This study indicates that differences in resistance to this parasite do not come about through differential ingestion of parasites. Also, an earlier study failed to show differential elimination of the parasite from the haemocoel. This leaves avoidance of penetration through the gut wall as the most plausible candidate causing large copepods to be more resistant to this parasite than small copepods.
William E. Kelso - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of cladoceran and copepod communities in floodplain habitats of the Atchafalaya River Basin
Hydrobiologia, 2000Co-Authors: Norman L. Davidson, William E. Kelso, D. Allen RutherfordAbstract:In the summer of 1994, floodplain habitats of the Atchafalaya River Basin were surveyed for cladocera and copepoda. Collection sites were grouped into three distinct habitat types (black-water, brown-water and green-water) based on a principal components analysis of five hydrographic variables (current velocity, Secchi disk depth, surface percent saturation of dissolved oxygen, dissolved oxygen differential and surface water temperature). An ANOVA of four community indices (total abundance, Shannon–Weiner diversity (H'), richness, and evenness) was performed on both cladoceran and copepod communities among the three floodplain habitats. Common species were compared among habitats (χ^2 goodness-of-fit) to determine where they were most abundant. Green-water habitats had the greatest overall abundance of cladocerans and copepods (dominated by Diaphanosoma birgei , Moina micrura and Mesocyclops edax ), but ranked lower in diversity and evenness than black-water and brown-water habitats where Ilyocryptus spinifer , Simocephalus serrulatus , Macrocyclops albidus (black-water) and Bosmina longirostris and Acanthocyclops vernalis (brown-water) were most abundant, respectively. These results indicate that the mosaic of floodplain habitats within large temperate river systems support unique zooplankton communities, and that these habitats are largely a function of seasonal hydrographic features.
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Relationships between environmental variables and the abundance of cladocerans and copepods in the Atchafalaya River Basin
Hydrobiologia, 1998Co-Authors: Norman L. Davidsonjr., William E. Kelso, D. Allen RutherfordAbstract:The relationship of species abundance to eight environmental variables was tested for 24 common species of crustacean zooplankton collected in the Atchafalaya River Basin during the summer of 1994. Stepwise regressions (α = 0.05) revealed significant relationships between zooplankton abundance and at least one environmental variable for 18 species ( R2 = 0.14-0.61, p < 0.0435-0.0001). The majority of these species' peak abundances were correlated with variables indicative of seasonal changes in floodplain habitat, as the Atchafalaya river receded, water temperature increased, and/or phytoplanktonic photosynthesis increased. Surface water temperature and the percent saturation of dissolved oxygen showed the most significant relationships, but specific conductance, current velocity, and Secchi disk depths were also related to abundance patterns of certain taxa. A principal components analysis of species abundances provided further insight into the partitioning of temporally-distinct zooplanton assemblages, showing that several species ( Bosmina longirostris, Daphnia parvula, Eurytemora affinis, and Ceriodaphnia quadrangula) predominated during early summer, and were supplanted by a distinct late-summer assemblage ( Diaphanosoma birgei, Moina micrura, Mesocyclops edax, and Daphnia lumholtzi) as time progressed. The transitional assemblage was dominated by Simocephalus serrulatus, Macrocyclops albidus, Microcyclops rubellus, and Thermocyclops inversus, all of which were most abundant in the hypoxic conditions characteristic of the latter stages of the Atchafalaya River flood-pulse.
