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  • Lake Baikal  (3)
  • sexual reproduction  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Description of the male of Potamocypris villosa (Jurine, 1820) (Crustacea, Ostracoda) (1985)
    Springer
    Hydrobiologia 127 (1985), S. 9-15 
    Details
    ISSN: 1573-5117
    Keywords: Cypridopsinae ; Potamocypris ; taxonomy ; morphology ; sexual reproduction ; Spain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bisexual population of Potamocypris villosa, found in Lago de Encina, a mesotrophic lake in the Cantabrian mountains, NW Spain, is the first certain record of the male of this species. Valves and soft parts are described. Males of Potamocypris-species lack a furca although a rudimentary furca is always present in females. The same applies to species of related genera, such as Tanganyikacypridopsis and Plesiocypridopsis. Some remarks on the position of the genus Potamocypris in the Cyprinopsinae are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004658
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of genotype and environment on phenotypic variability in Limnocythere inopinata (Crustacea: Ostracoda) (1999)
    Springer
    Hydrobiologia 400 (1999), S. 85-114 
    Details
    ISSN: 1573-5117
    Keywords: morphology ; clone ; temperature ; salinity ; parthenogenesis ; sexual reproduction ; cluster genotype ; general purpose genotype ; clonal taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Limnocythere inopinata (Baird) is a Holarctic species, widely distributed in non-marine waters, and mainly occurring in unisexual populations. It displays polymorphic traits which could be useful for taxonomical and (palaeo)ecological purposes, if the origin of these traits could be better understood. Three clones of L. inopinata were cultured in the laboratory under various temperature and salinity conditions (i.e. temperature 15, 20 and 25 °C, salinity expressed as electrical conductivity 400, 2000, 5000 and 8000 μS cm−1). Morphological traits for both the valves (shape and size) and soft parts (11 limb setae) were observed. Field populations from Chinese salt lakes and from Austrian lakes were also compared. The freshwater population from Mondsee and its derived clone M develop larger valves than those of the other two clones, clone N (from Neusiedlersee) and clone S (from Seewinkel, Oberer Stinkersee), which live exclusively in saline (alkaline) water. Parthenogenetic specimens from the freshwater lake Mondsee and sexually reproducing females from the Chinese salt lakes both have sub-rectangular valves with straight dorsal margin; the saline clones and populations have highly arched valves with rounded dorsal margin. No direct effects of temperature or salinity on valve ornamentation (reticulation, nodation) have been found. At least for nodation, a genetic factor seems apparent, as the saline clones N and S are never nodose, while the freshwater animals from Mondsee and the sexual animals from the Chinese salt lakes can be both with or without nodes. In the former case, number and position of nodes are variable. Both absolute and relative length of limb setae can be affected by environmental factors and by genotype, and this is the first time that this has been demonstrated in non-marine ostracods. Based on the present observations and experiments, it is concluded that L. inopinata is a variable, polymorphic species, consisting of a (semi-) continuous morphological cluster, in which both clonal genotypes and sexual haplotypes are nested. Therefore, Limnocythere sappaensis Staplin and L. binoda Huang are considered synonyms of L. inopinata; L. mongolica Daday is a possible synonym; L. sanctipatricii sensu Huang and L. dubiosa sensu Huang from Lake Qinghai are most likely erroneous identifications. Apparently recognisable clones with typical ecologies cannot be allocated a taxonomic rank, as this does not reflect a phylogenetic reality. Such links between recognisable morphologies and typical ecological ranges are useful for palaeoenvironmental reconstructions, but are applicable at a regional scale only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003759125903
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  • 3
    Electronic Resource
    Electronic Resource
    Oligochaeta from the abyssal zone of Lake Baikal (Siberia, Russia) (1999)
    Springer
    Hydrobiologia 406 (1999), S. 165-174 
    Details
    ISSN: 1573-5117
    Keywords: aquatic Oligochaeta ; Lake Baikal ; abyssal zone ; sediment ; abundance ; distribution ; diversity ; deep-water fauna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lake Baikal is unique because the water circulation carries oxygen to its deepest point (1637 m), which makes it the only freshwater lake in the world with an inhabitable abyssal area. The sampling of the abyssal of the Lake was recently made possible, allowing a study of the bathymetric and vertical distribution in the sediment of Oligochaeta. Samples were taken with a Reineck box corer and subsamples were extracted and subsequently divided into slices. Factors likely to affect oligochaete abundance with depth and in the sediment were then evaluated. Identification to the species-level allowed discussion of the possible role of the abyss of Lake Baikal in the origin of oligochaete taxa and to assess if genuine deep-water taxa exist. Abundance of Oligochaeta generally follows an exponential decline with depth. An exception was one station located near a deep hot vent. In the abyssal area, all families of Oligochaeta are concentrated near the surface of the sediment. While there are generally no Naididae below 50 m, Tubificidae, Lumbriculidae, Propappidae, Enchytraeidae and Haplotaxidae are present at all depths. Evidence suggests, for the first time, that food abundance is a limiting factor of oligochaete distribution. The possibility of a genuine deep-water oligochaete fauna in Lake Baikal cannot be excluded but the low densities and the very small sizes of animals in this environment might have caused biased samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003719430680
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of genotype and environment on phenotypic variability in Limnocythere inopinata (Crustacea: Ostracoda) (1999)
    Springer
    Hydrobiologia 400 (1999), S. 85-114 
    Details
    ISSN: 1573-5117
    Keywords: morphology ; clone ; temperature ; salinity ; parthenogenesis ; sexual reproduction ; cluster genotype ; general purpose genotype ; clonal taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Limnocythere inopinata (Baird) is a Holarctic species, widely distributed in non-marine waters, and mainly occurring in unisexual populations. It displays polymorphic traits which could be useful for taxonomical and (palaeo)ecological purposes, if the origin of these traits could be better understood. Three clones of L. inopinata were cultured in the laboratory under various temperature and salinity conditions (i.e. temperature 15, 20 and 25 °C, salinity expressed as electrical conductivity 400, 2000, 5000 and 8000 μS cm−1). Morphological traits for both the valves (shape and size) and soft parts (11 limb setae) were observed. Field populations from Chinese salt lakes and from Austrian lakes were also compared. The freshwater population from Mondsee and its derived clone M develop larger valves than those of the other two clones, clone N (from Neusiedlersee) and clone S (from Seewinkel, Oberer Stinkersee), which live exclusively in saline (alkaline) water. Parthenogenetic specimens from the freshwater lake Mondsee and sexually reproducing females from the Chinese salt lakes both have sub-rectangular valves with straight dorsal margin; the saline clones and populations have highly arched valves with rounded dorsal margin. No direct effects of temperature or salinity on valve ornamentation (reticulation, nodation) have been found. At least for nodation, a genetic factor seems apparent, as the saline clones N and S are never nodose, while the freshwater animals from Mondsee and the sexual animals from the Chinese salt lakes can be both with or without nodes. In the former case, number and position of nodes are variable. Both absolute and relative length of limb setae can be affected by environmental factors and by genotype, and this is the first time that this has been demonstrated in non-marine ostracods. Based on the present observations and experiments, it is concluded that L. inopinata is a variable, polymorphic species, consisting of a (semi-) continuous morphological cluster, in which both clonal genotypes and sexual haplotypes are nested. Therefore, Limnocythere sappaensis Staplin and L. binoda Huang are considered synonyms of L. inopinata; L. mongolica Daday is a possible synonym; L. sanctipatricii sensu Huang and L. dubiosa sensu Huang from Lake Qinghai are most likely erroneous identifications. Apparently recognisable clones with typical ecologies cannot be allocated a taxonomic rank, as this does not reflect a phylogenetic reality. Such links between recognisable morphologies and typical ecological ranges are useful for palaeoenvironmental reconstructions, but are applicable at a regional scale only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003759125903
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  • 5
    Electronic Resource
    Electronic Resource
    Depth distribution of oligochaetes in Lake Baikal (Siberia - Russia) (1994)
    Springer
    Hydrobiologia 278 (1994), S. 151-156 
    Details
    ISSN: 1573-5117
    Keywords: aquatic oligochaetes ; Lake Baikal ; bathymetric distribution ; vertical distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Au cours d'un programme d'échantillonnage préliminaire, les oligochètes du lac Baïkal ont été récoltés dans le sédiment mou prélevé le long de deux transects. Les oligochètes présents dans les échantillons ont simplement été dénombrés, sans identification déspèces. Les résultats suggèrent une diminution exponentielle du nombre d'individus en fonction de la profondeur du lac (11165 N m−2 à 21 m, 265 N m−2 à 1200 m). La plupart des oligochètes ont été trouvés dans les 7 premeirs cm de la couche supérieure du sédiment. La couleur orangée du sédiment suggère une grande disponibilité en oxygène, même aux profondeurs les plus grandes.
    Notes: Abstract In the course of a preliminary sampling program, oligochaetes were collected along two transects in soft sediments in Lake Baikal. The number of oligochaetes present in the samples was counted, without distinguishing between species. The results suggest an exponential decrease in number of individuals (N) relative to depth (11,165 N m−2 at 21 m, 265 N m−2 at 1200 m). Most oligochaetes were found in the top 7 cm of sediment. The orange colour of the sediments suggests a high oxygen availability, even at the greatest water depths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00142323
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  • 6
    Electronic Resource
    Electronic Resource
    Oxygen concentration profiles in sediments of two ancient lakes: Lake Baikal (Siberia, Russia) and Lake Malawi (East Africa) (1998)
    Springer
    Hydrobiologia 367 (1998), S. 163-174 
    Details
    ISSN: 1573-5117
    Keywords: oxygen microprofiles ; sediment ; ecological segregation ; Lake Baikal ; Lake Malawi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oxygen concentration profiles have been measured, by means of with microelectrodes in sediments of Lake Baikal and Lake Malawi, along transects allowing to give a survey of two major ancient Rift lakes: Lake Baikal (Eastern Siberia) and Lake Malawi (East Africa), along depth transects in the constitutive basins of the lakes and/or of relevant depths with regard to oxygen (including including the deepest point, 1680 m, in Lake Baikal). Sediment oxygen penetration depths (SOPs) display very different patterns, depending on the lake in the two lakes. In Lake Baikal, SOPs are variable, show no significant relationship with bathymetric depth and are surprisingly deep on Akademichesky ridge (〉 50.0 mm), emphasizing the distinctive feature of this region in the lake. While the Selenga river is an important source of eutrophication, the similarity of SOP-values in the Selenga shallow with those of most other sites suggests either a dilution of organic material by allochthonous matter, or a strong south-to-north transport of particles. In Lake Malawi, available oxygen is restricted to a maximum of three millimetres of the sediment, and there is a negative relationship with bathymetric depth, as a result of a steady decline of oxygen concentration with depth through the water column. Amongst the few parameters known to affect SOPs, the oxygen consumption by the sediment seems the most significant in both lakes. SOP-values furthermore confirm differences in the trophic status of Baikal and Malawi, respectively. The importance of oxygen as a factor likely to create ecological segregation for benthic organisms is discussed. Lake Malawi offers possibilities of bathymetric segregation but no vertical segregation in the sediment. In contrast, no bathymetric segregation related to oxygen is possible in Lake Baikal, but vertical segregation in the sediment is very likely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003280101128
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