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David J Horne - One of the best experts on this subject based on the ideXlab platform.
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The palaeopsychrosphere in the Devonian
Lethaia, 2018Co-Authors: Sylvie Crasquin, David J HorneAbstract:The interpretation of Palaeozoic marine benthonic ostracods of the Thuringian "Ecotype" or "Mega-assemblage" as indicative of a palaeopsychrosphere has been controversial. We review the evidence and conclude that the characteristics and distribution of these ostracods are consistent with the existence of deep, cold, well-oxygenated water masses, formed by high-latitude sinking of surface waters, in the Devonian oceans, comparable with those of the modern ocean that constitute the psychrosphere (waters below the thermocline with temperature < 10 °C). We present a new palaeoceanographic model for the Frasnian-Famennian (Late Devonian) Kellwasser events that resulted in the extinction of 75% of marine ostracod taxa, mostly neritic or pelagic forms, while the deep-water Thuringian Mega-assemblage was relatively unaffected. We offer an explanation for the unlikely preservation of examples of such a deep-water (bathyal to abyssal) ostracod fauna that involves upwelling of deep cold waters on continental margins. * Speaker
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Ostracoda from inland waterbodies with saline influence in central germany implications for palaeoenvironmental reconstruction
Palaeogeography Palaeoclimatology Palaeoecology, 2015Co-Authors: Anna Pint, David J Horne, Peter Frenzel, Julia Franke, Thomas Daniel, Antonia Burghardt, Benjamin Funai, Kristina Lippold, Gerhardt Daut, Volker WennrichAbstract:Abstract As a necessary precursor to reconstructing the palaeoenvironmental conditions likely to be temporarily influenced by salt bearing ground waters, modern sites of Central Germany, known from the literature to be continental salt water localities, were investigated for their ostracod faunas. Analysing their associations enables the test of several methods in palaeoenvironmental analysis based on ostracods. In total, 54 ostracod taxa are documented. One species, Microdarwinula zimmeri, is new for the area. Interesting is the historical occurrence of Cyprideis torosa and Cytheromorpha fuscata, typically regarded as indicators of brackish water. The draining of wetlands has led to the disappearance of many former inland salt sites so that only a few of the sampled water bodies still show slightly elevated salinity (oligohaline range). The most important factors for the distribution of ostracod associations are groundwater influence, turbidity and ecological stability, whereas the type of dominating ions is of lesser importance because of time-averaging using taphocoenoses from surface sediments in our study. The relative proportion of ecological groups of ostracods appears to be the best tool for reconstructing past habitat types. The newly established Ostracod Permanence Index and Ostracod Turbulence Index allow the recognition of the influx of ground and surface waters, perennial habitats and flowing waters. A test of the Mutual Ostracod Temperature Range (MOTR) method demonstrates its capability to reconstruct, with a precision of +/− 2 °C, the mean July and January air temperatures for the time interval 2002–2012. Additionally, the study contributes to the poorly known Recent distribution of ostracods in Central Germany.
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taxonomy morphology and biology of quaternary and living Ostracoda
Geophysical monograph, 2013Co-Authors: David J Horne, Anne Cohen, Koen MartensAbstract:Ostracods are one of the most diverse groups of living crustaceans, inhabiting marine, non-marine and even some semi-terrestrial habitats. They have an excellent fossil record, primarily due to their possession of a calcified bivalved carapace. A revised classification scheme is presented for Quaternary and living representatives of the Class Ostracoda, comprising the subclasses Myodocopa and Podocopa. The morphology, taxonomy, ontogeny and life histories of ostracods are reviewed and illustrated, paying attention to limbs (soft parts) as well as carapaces (hard parts), with emphasis on the Order Podocopida as the group most likely to be encountered in Quaternary deposits. Diagnostic carapace and limb characteristics are summarized for each of the higher taxonomic categories, including 10 suborders and 16 superfamilies of the orders Myodocopida, Halocyprida, Platycopida, Podocopida and Palaeocopida.
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Ostracoda as proxies for quaternary climate change overview and future prospects
In: Horne DJ and Holmes JA and Rodriguez-Lazaro J and Viehberg F (eds.) Ostracoda as Proxies for Quaternary Climate Change. (2012), 2012Co-Authors: J.a. Holmes, David J Horne, Julio Rodriguezlazaro, Finn ViehbergAbstract:Abstract Ostracod crustaceans are excellent Quaternary palaeoclimate proxies. As microfossils they supply evidence of past climatic conditions via indicator species, transfer function and mutual climatic range methods as well as the trace-element and stable-isotope geochemistry of their shells. We provide an overview of 17 contributions to the book Ostracoda as proxies for Quaternary climate change , highlight some of the emerging innovations and concerns, and assess the future prospects for ostracod applications in the field of Quaternary palaeoclimatology. The science of using ostracods as Quaternary palaeoclimate proxies has matured, well beyond the pioneering stage, and their application now needs to be tempered with critical awareness of their limitations. Key areas for future attention include palaeogenetics, improving knowledge of the ecology of living ostracods and the factors influencing their shell geochemistry, the establishment of global distributional databases and, as a necessary corollary to the last-mentioned, a programme of taxonomic harmonisation on a global scale. Finally, we emphasise the need for multi-proxy testing of methods, comparing ostracod-inferred climatic parameters with those derived from other proxies such as beetles, chironomids and foraminifera.
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global diversity of ostracods Ostracoda crustacea in freshwater
Hydrobiologia, 2008Co-Authors: Isa Schon, Koenraad Martens, Claude Meisch, David J HorneAbstract:There are close to 2,000 subjective spe- cies and about 200 genera of Recent non-marine Ostracoda. Together, Cyprididae (1,000 spp.) and Candonidae (c. 550 spp.) represent more than 75% of the extant specific diversity; the remaining 11 fam- ilies comprise the other 25% of the species. The Palaearctic region has the highest absolute non- marine ostracod diversity, followed by the Afrotrop- ical. The Australian region has the highest relative endemicity. About 90% of the species and 60% of the genera occur in one zoogeographical region only. This means that all the biological mechanisms which lead up to efficient dispersal and which are present in at least part of the non-marine Ostracoda (e.g. brooding, drought-resistant eggs, parthenogenesis) have not induced common cosmopolitan distributions in ostracods. Several habitats are hotspots for ostra- cod diversity and endemicity. For example, it appears that the ancient lakes hold up to 25% of the total ostracod diversity. Other speciation-prone habitats are groundwater, temporary pools and Australian salt lakes; in the latter two instances, cladogenesis has often been paralleled by gigantism. The present ostracod diversity results from 9 to 12 separate invasions of the non-marine habitat, starting about 400 Myr ago. Genetic diversity can be very different in different species, mostly, but not always, related to reproductive mode.
Koen Martens - One of the best experts on this subject based on the ideXlab platform.
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Association of body size and behavior of freshwater ostracods (Crustacea, Ostracoda) with aquatic macrophytes
Aquatic Ecology, 2015Co-Authors: Juliana Tiemi Matsuda, Luiz Felipe Machado Velho, Koen Martens, Fábio Amodêo Lansac-tôha, Roger Paulo Mormul, Janet HigutiAbstract:In aquatic systems, macrophytes play an important role in habitat structuring and can be relevant for the establishment and/or mobility of the organisms and might thus influence species composition. This study evaluates the influence of the structural complexity of aquatic plants on the community composition of Ostracoda in the upper Parana River floodplain. We tested the hypothesis that non-swimming and small-sized species have a higher association with more complex plants by a threshold indicator taxa analysis. Some small and non-swimming ostracod species had a significant affinity for macrophytes with higher complexity, especially Eichhornia crassipes. However, most species did not show an association with the structure of aquatic macrophytes, and there was only a slightly distinction among the communities of different plants. The results show that structural complexity is in some cases an important determining factor for the community composition of Ostracoda, but other factors may interact with and even override the effects of complexity. It can thus be concluded that the relation between habitat complexity and the Ostracoda community composition is complex and not always responds to general predictions.
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taxonomy morphology and biology of quaternary and living Ostracoda
Geophysical monograph, 2013Co-Authors: David J Horne, Anne Cohen, Koen MartensAbstract:Ostracods are one of the most diverse groups of living crustaceans, inhabiting marine, non-marine and even some semi-terrestrial habitats. They have an excellent fossil record, primarily due to their possession of a calcified bivalved carapace. A revised classification scheme is presented for Quaternary and living representatives of the Class Ostracoda, comprising the subclasses Myodocopa and Podocopa. The morphology, taxonomy, ontogeny and life histories of ostracods are reviewed and illustrated, paying attention to limbs (soft parts) as well as carapaces (hard parts), with emphasis on the Order Podocopida as the group most likely to be encountered in Quaternary deposits. Diagnostic carapace and limb characteristics are summarized for each of the higher taxonomic categories, including 10 suborders and 16 superfamilies of the orders Myodocopida, Halocyprida, Platycopida, Podocopida and Palaeocopida.
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Preface: Ostracoda: biostratigraphy and applied ecology
Hydrobiologia, 2012Co-Authors: Dermeval Aparecido Do Carmo, Ricardo L. Pinto, Koen MartensAbstract:The series of International Symposia on Ostracoda started in 1963, when ISO1 was organised in the historic Zoological Station of Naples by Dr Harbans Singh Puri. Matzke-Karasz et al. (2007) analysed the content of the 15 first ISO proceedings and grouped the 906 papers published in the various proceeding volumes (in stand-alone books and in journals) into several categories. Biostratigraphy and (palaeo-) ecology have always constituted strong components in this series of proceedings, and this inspired the organisers of the ISO16 to determine biostratigraphy and applied ecology as the main themes of their symposium. The 16th International Symposium on Ostracoda was held in Brasilia, Brazil, between 26 and 30 July 2009. The scientific communities from 25 different countries had representatives among the 107 participants, who brought to the meeting an amount of 102 contributions: 46 oral communications, 52 poster presentations and four keynote lectures given by invited speakers. The present proceedings volume comprises ten papers, a small selection of these contributions, and will serve as a legacy to the memory of this highly successful event. As always, the communication of scientific results is of prime importance, but the personal contacts with distant colleagues often leads to fertilisation of ideas and to successful collaborations. The ISO16 meeting scored on both accounts! Furthermore, by holding an ISO for the first time in South America, we hope to have helped foster ostracodology on this continent. In spite of the emphasis given in the current version of the symposium to biostratigraphy and applied ecology, contributions comprised also other research lines, such as Taxonomy, Morphology, Biogeography, Systematics and Evolution. In terms of geological time, the present proceedings contain six papers on Recent faunas, one on Tertiary, two on Mesozoic and one on Palaeozoic Ostracoda. The papers in this volume are loosely organised to follow this chronological sequence. The volume opens with the paper by Decrouy et al. (this volume), who studied the Sediment Penetration Depth of epiand infaunal ostracods in the Swiss Lake Geneva. The relevance of this paper is clear: ostracods have to moult 8–9 times during their development and each time have to calcify their valves using chemical Guest Editors: D. A. Do Carmo, R. L. Pinto & K. Martens / Ostracoda – Biostratigraphy and Applied Ecology
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biodiversity of non marine ostracods crustacea Ostracoda in the alluvial valley of the upper parana river brazil
Brazilian Journal of Biology, 2009Co-Authors: Janet Higuti, Fabio Amodeo Lansactoha, Luiz Felipe Machado Velho, Koen MartensAbstract:In the present study, we test the relevance of a number of environmental factors on alpha and beta ostracod diversities, at species and family level. Ostracods were sampled from several substrates, including sediment and root systems of various floating aquatic macrophytes, from 48 environments (both lentic and lotic habitats, ranging from the river itself, over connecting channels linking with open lakes, and, finally closed lakes), belonging to four different systems (Parana, Ivinheima, Baia and Taquarucu), in the alluvial valley of the Upper Parana River. The faunistic survey recorded the presence of 54 species of Ostracoda, belonging to the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Various diversity estimators indicated that these recorded levels of specific diversity should be close to true values. Higher values of ostracods species richness (alpha diversity) were observed in the Baia and Ivinheima systems, while lotic habitats were richer than lentic ones. In addition, open lakes appeared to be more affected by the variable 'system' than closed ones, which can to some extend be explained by the putative effects of flood pulse on benthic communities. The two investigated factors have different effects on the four ostracod families. The present study also indicated that there is a large homogeneity within and between systems, as exemplified by the low beta-diversity levels.
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distribution and ecology of non marine ostracods crustacea Ostracoda from friuli venezia giulia ne italy
Journal of Limnology, 2009Co-Authors: Valentina Pieri, Koen Martens, Fabio Stoch, Giampaolo RossettiAbstract:From August 1981 to July 2007, 200 inland water bodies were sampled to gather information on the Recent ostracod fauna of Friuli Venezia Giulia (NE Italy). A total of 320 samples were collected from surface, interstitial and ground waters. Whenever possible, ostracod identification was performed at species level based on the morphology of both valves and limbs. Seventy-four taxa in 30 genera belonging to 9 different families (Darwinulidae, Candonidae, Ilyocyprididae, Notodromadidae, Cyprididae, Limnocytheridae, Cytheridae, Leptocytheridae and Xestoleberididae) were identified. The maximum number of taxa per site was seven. The most common species was Cypria ophthalmica (133 records), followed by Cyclocypris ovum (86 records), C. laevis (49 records), Cypridopsis vidua (40 records) and Notodromas persica (28 records). Of particular relevance is the occurrence of six species new to Italy: Microdarwinula zimmeri, Penthesilenula brasiliensis, Fabaeformiscandona wegelini, Pseudocandona semicognita, Candonopsis scourfieldi, and C. mediosetosa. Scanning electron microscopy images of valves are provided for most of the described taxa. Geographical distribution of ostracods and their occurrence in relation to environmental variables were examined. The results of this study indicate that Friuli Venezia Giulia hosts a very diverse ostracod fauna, representing a significant proportion of all ostracod taxa known thus far from Italy.
Peter Frenzel - One of the best experts on this subject based on the ideXlab platform.
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spatial distribution and ecology of the recent Ostracoda from tangra yumco and adjacent waters on the southern tibetan plateau a key to palaeoenvironmental reconstruction
Limnologica, 2016Co-Authors: Lailah Gifty Akita, Peter Frenzel, Junbo Wang, Nicole Borner, Ping PengAbstract:We elucidate the ecology of Recent Ostracoda from a deep brackish lake, Tangra Yumco (30°45′—31°22′N and 86°23′—86°49′E, 4595 m a.s.l.) and adjacent waters on the southern Tibetan Plateau. Ostracod associations (living and empty valves) in sixty-six sediment samples collected from diverse aquatic habitats (lakes, estuary-like water and lagoon-like water waters, rivers, ponds and springs) were quantitatively assessed. Eleven Recent Ostracoda were found (nine living and two as empty valves only). Cluster analysis established two significant (p < 0.05) habitat specific associations; (i) Leucocytherella sinensis, Limnocythere inopinata, Leucocythere? dorsotuberosa, Fabaeformiscandona gyirongensis and Candona xizangensis are lacustrine fauna. (ii) Tonnacypris gyirongensis, Candona candida, Ilyocypris sp., Heterocypris incongruens and Heterocypris salina are temporary water species. Ostracod distribution and abundance are significantly (p < 0.05) correlated to physico-chemical variables. The first two axes of a canonical correspondence analysis (CCA) explain 30.9% of the variation in the species abundance data. Conductivity and habitat types are the most influential ecological factors explaining the presence and abundance of ostracods. Spearman correlation analysis reveals that: (i) Two species, L.? dorsotuberosa (r = 0.25) and L. inopinata (r = 0.36) have a significant positive correlation with conductivity while one species, T. gyirongensis (r = −0.68) displays a significant negative correlation with conductivity. Limnocythere inopinata correlates significantly positive (r = 0.37) with alkalinity. Fabaeformiscandona gyirongensis correlates significantly positive (r = 0.28) with water depth. Key indicator living assemblages are: (i) L. sinensis dominates Ca-depleted brackish waters although ubiquitously distributed; (ii) L.? dorsotuberosa dwells in fresh to brackish waters; (iii) L. inopinata predominates in mesohaline to polyhaline waters; (iv) F. gyirongensis inhabits exclusively brackish-lacustrine deeper waters; (v) C. candida populates freshwaters; (vi) T. gyirongensis and Ilyocypris sp. are restricted to shallow temporary waters; (vii) H. incongruens occurs in ponds. Water depth indicators are F. gyirongensis and L.? dorsotuberosa, useful in ostracod assemblages for palaeo-water depth reconstruction. Our results expand the knowledge of the ecological significance of Recent Tibetan Ostracoda ecology. This is a new insight on habitat chacteristics of both living assemblages and sub-Recent associations of ostracods in mountain aquatic ecosystems. The new modern ostracod dataset can be used for the quantitative reconstruction of past environmental variables (e.g., conductivity) and types of water environment. The key indicator ostracods are relevant in palaeolimnological and climate research on the Tibetan Plateau.
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Ostracoda from inland waterbodies with saline influence in central germany implications for palaeoenvironmental reconstruction
Palaeogeography Palaeoclimatology Palaeoecology, 2015Co-Authors: Anna Pint, David J Horne, Peter Frenzel, Julia Franke, Thomas Daniel, Antonia Burghardt, Benjamin Funai, Kristina Lippold, Gerhardt Daut, Volker WennrichAbstract:Abstract As a necessary precursor to reconstructing the palaeoenvironmental conditions likely to be temporarily influenced by salt bearing ground waters, modern sites of Central Germany, known from the literature to be continental salt water localities, were investigated for their ostracod faunas. Analysing their associations enables the test of several methods in palaeoenvironmental analysis based on ostracods. In total, 54 ostracod taxa are documented. One species, Microdarwinula zimmeri, is new for the area. Interesting is the historical occurrence of Cyprideis torosa and Cytheromorpha fuscata, typically regarded as indicators of brackish water. The draining of wetlands has led to the disappearance of many former inland salt sites so that only a few of the sampled water bodies still show slightly elevated salinity (oligohaline range). The most important factors for the distribution of ostracod associations are groundwater influence, turbidity and ecological stability, whereas the type of dominating ions is of lesser importance because of time-averaging using taphocoenoses from surface sediments in our study. The relative proportion of ecological groups of ostracods appears to be the best tool for reconstructing past habitat types. The newly established Ostracod Permanence Index and Ostracod Turbulence Index allow the recognition of the influx of ground and surface waters, perennial habitats and flowing waters. A test of the Mutual Ostracod Temperature Range (MOTR) method demonstrates its capability to reconstruct, with a precision of +/− 2 °C, the mean July and January air temperatures for the time interval 2002–2012. Additionally, the study contributes to the poorly known Recent distribution of ostracods in Central Germany.
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Ostracoda crustacea as indicators of subaqueous mass movements an example from the large brackish lake tangra yumco on the southern tibetan plateau china
Palaeogeography Palaeoclimatology Palaeoecology, 2015Co-Authors: Lailah Gifty Akita, Peter Frenzel, Junbo Wang, Torsten Haberzettl, Thomas Kasper, Klaus ReicherterAbstract:Abstract A conceptual model of subaquaeous mass movements and ostracod distribution in lacustrine sediment event layers was tested. Integrated methods (geophysical, sedimentological and microfossil analyses) were performed on a short sediment core retrieved from 220 m water depth in the large brackish lake Tangra Yumco on the southern Tibetan Plateau, central Asia. The event layers of the core and their underlying and overlying sediments were investigated. Four major event layers composed of sandy silt with graded bedding are interpreted as turbidites. The fifth layer consisting of fine sand and silt and without graded bedding is characterized as a debrite. The ostracods, small bivalved aquatic crustaceans, identified are Leucocytherella sinensis Huang, 1982, Leucocythere ? dorsotuberosa Huang, 1982, Limnocythere inopinata (Baird, 1843) and Fabaeformiscandona gyirongensis (Huang, 1982). Ostracod evidence is a good proxy for the evaluation of massive sediment event layers formed by subaqueous mass movements. Four assumptions of a conceptual model were confirmed: (i) fine grained sediments of event layers (turbidite deposits) contain very low numbers of ostracods compared to the underlying and overlying sediments; (ii) ostracods are sorted according to size and display high abundance and high proportion of adult valves of Leucocytherella sinensis at the base of event layers; (iii) a relatively low number of carapaces is present within the event layers; and (iv) the recolonization of newly event-generated habitats by pioneer assemblages transforming into pre-event association gradually.
Lailah Gifty Akita - One of the best experts on this subject based on the ideXlab platform.
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spatial distribution and ecology of the recent Ostracoda from tangra yumco and adjacent waters on the southern tibetan plateau a key to palaeoenvironmental reconstruction
Limnologica, 2016Co-Authors: Lailah Gifty Akita, Peter Frenzel, Junbo Wang, Nicole Borner, Ping PengAbstract:We elucidate the ecology of Recent Ostracoda from a deep brackish lake, Tangra Yumco (30°45′—31°22′N and 86°23′—86°49′E, 4595 m a.s.l.) and adjacent waters on the southern Tibetan Plateau. Ostracod associations (living and empty valves) in sixty-six sediment samples collected from diverse aquatic habitats (lakes, estuary-like water and lagoon-like water waters, rivers, ponds and springs) were quantitatively assessed. Eleven Recent Ostracoda were found (nine living and two as empty valves only). Cluster analysis established two significant (p < 0.05) habitat specific associations; (i) Leucocytherella sinensis, Limnocythere inopinata, Leucocythere? dorsotuberosa, Fabaeformiscandona gyirongensis and Candona xizangensis are lacustrine fauna. (ii) Tonnacypris gyirongensis, Candona candida, Ilyocypris sp., Heterocypris incongruens and Heterocypris salina are temporary water species. Ostracod distribution and abundance are significantly (p < 0.05) correlated to physico-chemical variables. The first two axes of a canonical correspondence analysis (CCA) explain 30.9% of the variation in the species abundance data. Conductivity and habitat types are the most influential ecological factors explaining the presence and abundance of ostracods. Spearman correlation analysis reveals that: (i) Two species, L.? dorsotuberosa (r = 0.25) and L. inopinata (r = 0.36) have a significant positive correlation with conductivity while one species, T. gyirongensis (r = −0.68) displays a significant negative correlation with conductivity. Limnocythere inopinata correlates significantly positive (r = 0.37) with alkalinity. Fabaeformiscandona gyirongensis correlates significantly positive (r = 0.28) with water depth. Key indicator living assemblages are: (i) L. sinensis dominates Ca-depleted brackish waters although ubiquitously distributed; (ii) L.? dorsotuberosa dwells in fresh to brackish waters; (iii) L. inopinata predominates in mesohaline to polyhaline waters; (iv) F. gyirongensis inhabits exclusively brackish-lacustrine deeper waters; (v) C. candida populates freshwaters; (vi) T. gyirongensis and Ilyocypris sp. are restricted to shallow temporary waters; (vii) H. incongruens occurs in ponds. Water depth indicators are F. gyirongensis and L.? dorsotuberosa, useful in ostracod assemblages for palaeo-water depth reconstruction. Our results expand the knowledge of the ecological significance of Recent Tibetan Ostracoda ecology. This is a new insight on habitat chacteristics of both living assemblages and sub-Recent associations of ostracods in mountain aquatic ecosystems. The new modern ostracod dataset can be used for the quantitative reconstruction of past environmental variables (e.g., conductivity) and types of water environment. The key indicator ostracods are relevant in palaeolimnological and climate research on the Tibetan Plateau.
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Ostracoda crustacea as indicators of subaqueous mass movements an example from the large brackish lake tangra yumco on the southern tibetan plateau china
Palaeogeography Palaeoclimatology Palaeoecology, 2015Co-Authors: Lailah Gifty Akita, Peter Frenzel, Junbo Wang, Torsten Haberzettl, Thomas Kasper, Klaus ReicherterAbstract:Abstract A conceptual model of subaquaeous mass movements and ostracod distribution in lacustrine sediment event layers was tested. Integrated methods (geophysical, sedimentological and microfossil analyses) were performed on a short sediment core retrieved from 220 m water depth in the large brackish lake Tangra Yumco on the southern Tibetan Plateau, central Asia. The event layers of the core and their underlying and overlying sediments were investigated. Four major event layers composed of sandy silt with graded bedding are interpreted as turbidites. The fifth layer consisting of fine sand and silt and without graded bedding is characterized as a debrite. The ostracods, small bivalved aquatic crustaceans, identified are Leucocytherella sinensis Huang, 1982, Leucocythere ? dorsotuberosa Huang, 1982, Limnocythere inopinata (Baird, 1843) and Fabaeformiscandona gyirongensis (Huang, 1982). Ostracod evidence is a good proxy for the evaluation of massive sediment event layers formed by subaqueous mass movements. Four assumptions of a conceptual model were confirmed: (i) fine grained sediments of event layers (turbidite deposits) contain very low numbers of ostracods compared to the underlying and overlying sediments; (ii) ostracods are sorted according to size and display high abundance and high proportion of adult valves of Leucocytherella sinensis at the base of event layers; (iii) a relatively low number of carapaces is present within the event layers; and (iv) the recolonization of newly event-generated habitats by pioneer assemblages transforming into pre-event association gradually.
Klaus Reicherter - One of the best experts on this subject based on the ideXlab platform.
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Ostracoda crustacea as indicators of subaqueous mass movements an example from the large brackish lake tangra yumco on the southern tibetan plateau china
Palaeogeography Palaeoclimatology Palaeoecology, 2015Co-Authors: Lailah Gifty Akita, Peter Frenzel, Junbo Wang, Torsten Haberzettl, Thomas Kasper, Klaus ReicherterAbstract:Abstract A conceptual model of subaquaeous mass movements and ostracod distribution in lacustrine sediment event layers was tested. Integrated methods (geophysical, sedimentological and microfossil analyses) were performed on a short sediment core retrieved from 220 m water depth in the large brackish lake Tangra Yumco on the southern Tibetan Plateau, central Asia. The event layers of the core and their underlying and overlying sediments were investigated. Four major event layers composed of sandy silt with graded bedding are interpreted as turbidites. The fifth layer consisting of fine sand and silt and without graded bedding is characterized as a debrite. The ostracods, small bivalved aquatic crustaceans, identified are Leucocytherella sinensis Huang, 1982, Leucocythere ? dorsotuberosa Huang, 1982, Limnocythere inopinata (Baird, 1843) and Fabaeformiscandona gyirongensis (Huang, 1982). Ostracod evidence is a good proxy for the evaluation of massive sediment event layers formed by subaqueous mass movements. Four assumptions of a conceptual model were confirmed: (i) fine grained sediments of event layers (turbidite deposits) contain very low numbers of ostracods compared to the underlying and overlying sediments; (ii) ostracods are sorted according to size and display high abundance and high proportion of adult valves of Leucocytherella sinensis at the base of event layers; (iii) a relatively low number of carapaces is present within the event layers; and (iv) the recolonization of newly event-generated habitats by pioneer assemblages transforming into pre-event association gradually.
