Dissertationen zum Thema „Ostracoda“
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1
Morais, Anderson Luiz Martins de. „Ostracodes (Crustacea, Ostracoda) das praias rochosas de Santa Catarina, Brasil“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/153380.
Annotation:
Os ostracodes são microcrustáceos predominantemente bentônicos que deixaram rico registro fóssil, constituindo-se em importante ferramenta para a interpretação paleoambiental e bioestratigráfica. Estudos que tratam dos ostracodes recentes são de grande importância à Paleomicrontologia, pois muitos gêneros e até mesmo espécies do Cenozoico ainda são encontrados nos mares atuais. Diversos estudos versam sobre os Ostracoda na plataforma continental e talude superior no Brasil, mas são raras as pesquisas nas águas mais rasas do infralitoral. O principal objetivo deste estudo foi identificar e ilustrar a riqueza de espécies ao longo de uma ampla área litorânea do sul do Brasil, cuja costa é formada por numerosas pequenas praias guardadas por promontórios rochosos. Discutir aspectos relacionados à zoo- e à paleozoogeografia em especial dos elementos autóctones desta ostracofauna, além de introduzir a discussão sobre a fidelidade composicional entre associação viva e morta na área de estudo, estão entre os objetivos subsequentes.Dezoito famílias, 33 gêneros e 46 espécies foram identificados nesse estudo. A família Hemicytheridae é a mais representativa com 18 espécies, seguida por Cytheruridae com seis espécies. Duas espécies do gênero Xestoleberis Sars foram identificadas como prováveis novos táxons para Xestoleberididae. Preliminarmente, a fidelidade composicional é baixa, com maior riqueza na associação morta, bem como grande dominância e baixa riqueza na associação viva, um padrão esperado para zonas marinhas rasas como o infralitoral.Ostracoda are microcrustaceans with predominantly benthic habit which exhibit an abundant fossil record and constitute an important tool for paleoenvironmental and biostratigraphic studies. Research about recent ostracodes are extremely relevant to Paleomicrontology since many genera and even species from Cenozoic are still found nowadays. Several studies on Ostracoda from Brazil have focused on continental shelf and upper slope. The present work aims to identify and illustrate the species richness over a broad coastal area from southern Brazil, which coast is represented by numerous small sandy beaches guarded by rock promontories. Also, discuss zoo- and paleozoogeographic aspects, mainly related to autochthonous elements of this ostracofauna, and to introduce the discussion of compositional fidelity between living and dead ostracode assemblages, are among the subsequent objectives. Eighteen families, 33 genera and 46 species were identified. The family Hemicytheridae is the most representative with 18 species followed by Cytheruridae with six species. Two Xestoleberididae species herein identified are probably new taxa. A preliminary analysis showed low compositional fidelity with richness higher in death than in living assemblages. The living assemblage showed high dominance and low richness. This pattern is common for shallow marine zones such the infralittoral.
2
Wood, Roland Neville. „Ecology of Lake District Ostracoda“. Thesis, University of Greenwich, 1992. http://gala.gre.ac.uk/6348/.
Annotation:
Freshwater ostracods are potentially useful for environmental monitoring and, since their calcified valves may be preserved in lake sediments, are also valuable in palaeolimnological studies of environmental pollution such as eutrophication and surface water acidification. To establish a data-base of ostracod ecology, biannual survey work in 1989-1990 was performed in 75 lakes and tarns of a wide range of physico-chemical characteristics in the Lake District in Cumbria, ranging from large eutrophic lakes such as Windermere and Ullswater to tiny, upland acidic tarns. pH ranged from 4.3 (Black Pool) to 8.0 (Browns Tarn). Littoral margin samples were taken from all 75 sites and yielded 31 ostracod species, of which 8 were new to the Lake District fauna. The collection of multiple littoral samples from two sites demonstrated that a single sample produced an adequate faunal representation if it encompassed a variety of microhabitats. Statistical analysis, incorporating a multistage, multivariate technique, has shown that 18 species make up over 99% of the data set, and that 5 species, Cvpria ophthalmica, Cvclocypris ovum. Metacvpris cordata. Candona Candida and Cvpridopsis vidua. dominate the community in 71% of the sites containing ostracods, forming eight distinct assemblage groups. No ostracods were found in 13 of the 75 sites, 11 of which were acidic, having a pH of below 5.7. Equations were derived to predict both species distribution and diversity. Important predictors of community structures were shown to be pH, [Ca] 2+ , [Mg] 2+ , substrate, lake size and altitude. The equations were tested by further sampling of additional sites in the Lake District. Predictions of total species number and density generally provided an excellent fit to the observed data, although individual species predictions were poorer, especially in alkaline conditions. Substrate was not included in the analysis, due to quantitative difficulties, but this factor must be included in future predictive models as it was shown to be an important parameter in determining distribution. Deep-water sampling was carried out in 6 lakes. 10 species were collected, including Candona necrlecta, which was absent in the littoral samples. 9 species contributed to over 99% of the data set, and 2, Cypria ophthalmica and Candona Candida dominated the community in 75% of the sites containing ostracods. Community structure was predominantly determined by water depth (together with the associated temperature effect) and substrate. The sex ratio of Cyclocvpris ovum was shown be biased towards the female only at high alkalinities. Other species had sex ratios biased towards the male or female, the values independent of water quality. Large, swimming ostracod species were absent in sites containing fish. A series of laboratory experiments using three species of Ostracoda, (Cvpria ophthalmica. Cvpricercus fuscatus. and Eucvpris virens), and a predator (Gasterosteus aculeatus) correlated increasing ostracod size with an increased rate of predation, suggesting that predation could limit ostracod distribution. From the results of principal component analysis, it was concluded that the main characteristics that chemically differentiate the sites are calcium, magnesium, hydrogen and sodium ion concentrations. Toxicity tests were used to expose selected species to a wide range of calcium, magnesium, sodium and aluminium concentrations, at both neutral and acidic pH levels. Aluminium was selected as it has been highlighted as a major factor in the toxicity of acid waters. All species tolerated a wider spectrum of ionic concentrations than those in which they were recorded in the field, although the order of species survival in the experiments was similar to that found in the Lake District. It is suggested that whilst adult Ostracoda do not suffer from the acute toxicity of pH or aluminium, they may be unable to successfully reproduce in harsh environmental conditions. The waters of the English Lake District are not particularly species-rich due primarily to low alkalinity and low levels of dissolved cations, but also because they are cold. Only in small, ion-enriched pools is ostracod density sufficiently high to warrant their consideration as important detritivorous contributors in the cycling of nutrients. The Lake District fauna is compared with those recorded in other parts of Britain and Europe.
3
Reeves, Jessica Marie. „The use of ostracoda in the palaeoenvironmental reconstruction of the Gulf of Carpentaria, Australia, from the last interglacial to present“. Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050111.153534/index.html.
4
Gaiger, Frances Jean. „Mid-Pleistocene Extinction of Deep-Sea Ostracoda?“ Thesis, University of Canterbury. Geological Sciences, 2006. http://hdl.handle.net/10092/1349.
Annotation:
A global extinction event has been documented in protozoan foraminifera in the late Pliocene to Pleistocene. The timing of the extinction event varied depending on location, however for Ocean Drilling Project Site 1125, disappearances occurred between 2.5 and 0.57 Ma, with the major decline approximately 1.1 Ma. In order to determine if this event affected benthic organisms other than protozoans, this study was undertaken to determine how podocopid ostracods (Crustacea) recovered Ocean Drilling Program Site 1125 responded. The present study was hindered by the small number of valves recovered; the fact that a large proportion of taxa found were undescribed and new to science; and the current state of taxonomic scheme that is under significant revision. These factors meant that a comprehensive comparison could not be achieved. Despite this, counts of ostracod valves and assessments of diversity from this study reveal a significant increase in both parameters from approximately 900-600 ka. Three possible causes were investigated to account for this increase, sediment type and sample size; affects of taphonomy, mainly dissolution; or an actual biotic 'event'. Statistical analyses showed that although sample size did have some effect, it was not the sole reason for the increase in ostracod numbers. Dissolution had an expected affect on the percentage of juveniles but no correlations were found with other sample characteristics. Sedimentation rate was investigated but this also proved unrelated. Therefore, it is suggested that the increase in total ostracod valves and diversity which occurs between 900 and 600 ka was in fact a natural, biotic 'event'. This preliminary evidence suggests that an oceanographic event that has negatively impacted on the foraminifers has had the reverse affect on the ostracod assemblage, in the sense that both population size and diversity increase during that time.
5
Wood, Adrian Mark. „Recent Ostracoda and Mid-Pilocene global warming“. Thesis, Aberystwyth University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496746.
6
Ferdinando, Darren. „Ostracode and foraminiferal taxonomy and palaeoecology of the Fossil Cliff Member of the Holmwood Shale, northern Perth Basin, Western Australia“. University of Western Australia. Dept. of Geology and Geophysics, 2001. http://theses.library.uwa.edu.au/adt-WU2003.0019.
Annotation:
The Sakmarian (Cisuralian, Permian) Fossil Cliff Member of the Holmwood Shale is situated in the northern Perth Basin, Western Australia, and consists of alternating beds of shale and silty calcarenite forming three parasequences. Within this member a diverse fauna of ostracodes and foraminifera are present. During the Cisuralian the northern Perth Basin formed part of the Gondwanan supercontinent and was linked to Greater India via an epeiric sea that opened to the north. The ostracode fauna is restricted to the calcareous beds of the member and consists of a diverse benthic fauna comprising 31 new species and 13 previously recorded species. Species from the Healdioidea, Bairdioidea, Youngielloidea, and Thlipsuroidea dominate the assemblage and suggest a normal-marine environment during the period represented by the calcareous beds, with an overall shallowing trend up the sequence. The fauna shows some similarity to faunas from the Tethyan deposits of North America and the Boreal deposits of Russia during the Late Carboniferous and Cisuralian. Twenty-eight species of foraminifera were recorded from the Fossil Cliff Member and underlying Holmwood Shale and comprise two distinct faunas, an agglutinated benthic foraminiferal fauna found within the shale beds and a calcareous benthic foraminiferal fauna present in the calcarenite units. The agglutinated foraminifera are inferred to represent deposition in dysoxic to suboxic (0.1-1.5 mL/LO2;), poorly circulated bottom waters below wave base. The calcareous foraminifera are inferred to represent deposition in normal-marine conditions. Both foraminiferal assemblages show a shallowing trend in their distribution that matches the trend identified in the ostracode fauna. Based upon the palaeoecology of the ostracode and foraminiferal faunas, the depositional environment for the Fossil Cliff Member is inferred to have been within shallow water in an epeiric basin during an overall marine regression that is overprinted by eustatic and isostatic oscillations resulting from deglaciation that occurred during the early Sakmarian (Cisuralian). These sea-level oscillations raised and lowered the oxic surface waters of the epeiric sea above and below the substrate resulting in a sparse agglutinated foraminiferal fauna or an abundant and diverse ostracode and calcareous foraminiferal fauna respectively.
7
Sartori, Lisandra Aparecida Alves. „Variações faunísticas ((Ostracoda) no testemunho G-77, quaternário tardio da Bacia de Campos, Brasil“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/38630.
Annotation:
Estudos recentes têm demonstrado significativas variações na composição da fauna de ostracodes batiais decorrentes de mudanças climáticas. Visando verificar como esses eventos afetaram a ostracofauna batial da bacia de Campos foram analisadas 15 amostras provenientes de um testemunho a pistão recuperado a 1.287 m de lâmina de água. Espécies alóctones e autóctones foram identificadas sendo apenas as últimas estudadas. A idade das amostras foi obtida com base na análise de isótopos estáveis de oxigênio em testas do foraminífero planctônico Globigerinoides ruber, e os resultados comparados com dados do SPECMAP (Spectral Mapping Project). Foram identificadas 50 espécies autóctones distribuídas em 26 gêneros e 17 famílias. Os gêneros Krithe e Cytheropteron foram os mais diversificados (sete e cinco espécies, respectivamente). A família mais diversificada foi Cytheruridae, corroborando outros estudos paleoceanográficos. Foi estabelecida a idade de 42 ka para a base e 200 anos para o topo do testemunho. A análise de agrupamento por similaridade de Jaccard dividiu as amostras em dois grupos separados na amostra 12 (17,3 ka), no limite Holoceno-Último Máximo Glacial. A diversidade oscilou significativamente entre períodos glaciais e interglaciais, sendo menor no primeiro (3,0 nats/ind-1) e maior no último (3,4 nat/ind-1). Foi observado o predomínio de Argilloecia e Cytheropteron durante a deglaciação, Saida no interglacial, Apatihowella no UMG, Krithe no glacial e Macropyxis durante o UMG e glacial. Xestoleberis, por sua vez, ocorreu com diversidade relativamente constante ao longo de todo o testemunho. A distância taxonômica entre as espécies que ocorrem no glacial e interglacial se mostrou dentro dos limites esperados, com pequena proximidade entre os limites superiores e inferiores, respectivamente. A fauna de ostracodes da Bacia de Campos respondeu às variações climáticas ocorridas no Quaternário, o que reforça seu grande potencial como indicadora de mudanças paleoceanográficas.Present studies have demonstrated significative changes in the composition of bathyal ostracode fauna caused by climatic events. With the objective of assess the influence of these events on the bathyal ostracodes from Campos Basin, 15 samples from a piston core taken at 1,287 m water depth were studied. Both allochthonous and autochthonous species were identified, however, only the latter were analyzed. The age of the samples was determined based on oxygen stable isotope data from tests of the planktonic foraminifer Globigerinoides ruber and compared to SPECMAP (Spectral Mapping Project) ones. Fifty autochthonous species belonging to 26 genera and 17 families were identified. The genera Krithe and Cytheropteron were the more diversified (seven and five species, respectively), while Cytheruridae was the most diversified family, supporting other paleoceanographic studies. The core bottom was dated as 42 ka, and the top 200 years. The Jaccard similarity grouping analysis shared the samples into two groups being the sample 12 (17.3 ka) the limit between them, which corresponds to the Holocene-Last Glacial Maximum transition. The diversity varied significantly between glacial and interglacial periods, being lower in the former (3.0 nats/ind-1) and higher in the latter (3.4 nat/ind-1). The predominance of Argilloecia and Cytheropteron during the deglacial, Saida during the interglacial, Apatihowella during LGM, Krithe on glacial, and Macropyxis during the glacial and LMG was recorded. Xestoleberis was registered with steady diversity values along the core. The taxonomic distances between the species in the glacial and interglacial presented ordinary values, with small distance between the upper and lower limits, respectively. The ostracode faunas from Campos Basin responded to the Quaternary climatic events, reinforcing the use of deep-sea ostracodes changes as a paleoceanographic proxy.
8
Pollicott, Paul D. „The Silurian Ostracoda of the Oslo region, Norway“. Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/34940.
Annotation:
A study of the ostracode fauna from the Silurian of Norway has been undertaken. All of the taxa recoverd and described are from the Llandovery and Wenlock Series; one species from the topmost part of the Ordovician of the Oslo region is also figured. Research has concentrated particularly upon the Palaeocopa Henningsmoen, 1954, but also includes the Leperditicopida Scott, 1961. The 'non-palaeocopes', because of particular problems related to preservation and taxonomy, are not treated as extensively. Primary revision has been made wherever possible. Such work has been augmented by studies of extensive new collections made from throughout the Oslo region, particularly from the Ringerike, Oslo-Asker and Holmestrand districts. This study has concentrated firstly on the taxonomy of the fauna. There are chapters on the Leperditicopa, Palaeocopa and 'non-palaeocopes'. Other chapters deal with the palaeoecology, biostratigraphy and correlation and affinities of the fauna. A full faunal and associated locality list, together with information on regional stratigraphy, is also presented. The fauna is 26 genera (2 new), 43 named species (14 new) and 15 other forms are described under open nomenclature. The Silurian ostracode fauna of Norway is mostly endemic (at specific level) but does have affinities with Gotland, Siberia and Britain. Ostracode potential for correlation between various districts of the Oslo region is best realised in the Steinsfjorden Formation. Standard micropalaeontological techniques have been used throughout, with most material being prepared by 'Vibrotool', and photographed on the Scanning Electron Microscope.
9
Larwood, Jonathan G. „Tertiary to recent evolution of Ostracoda on seamounts“. Thesis, Cardiff Metropolitan University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400645.
10
Syme, Anna. „A systematic revision of the cylindroleberididae (Crustacea Ostracoda Mydodocopa) /“. Connect to thesis, 2007. http://eprints.unimelb.edu.au/archive/00002921.
11
Gammudi, Amar Mohamed. „Lower Palaeogene ostracoda from the Sirt Basin of Libya“. Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299742.
12
Galoukas, Stylianos Filippos. „Late Cenozoic ostracoda of Cyprus and their palaeoenvironmental interpretation“. Thesis, University College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283679.
13
Slipper, Ian Jeffrey. „Turonian (Late Cretaceous) Ostracoda from Dover, south-east England“. Thesis, University of Greenwich, 1997. http://gala.gre.ac.uk/6302/.
Annotation:
Ostracod assemblages from samples collected through the Turonian Stage of the Late Cretaceous from Dover, Kent, south-east England, consist of one hundred and three species group taxa. These are described and illustrated. This represents a significant increase in the knowledge of the Turonian fauna, since previous estimates of the number of species present during the Turonian are less than thirty. This improvement has been brought about by the selection of an appropriate processing method. Freeze-thaw processing is recommended for chalks and hardgrounds which comprise much of the Turonian Stage. The white spirit, solvent method is shown to be preferable for marls. Nineteen species and six subspecies are here described as new: Polycope lunaplena sp. nov, Cytherella truncatoides sp. nov., Cytherella vulna sp. nov., Cytherella weaveri sp. nov., Cytherelloidea granulosa parca ssp. nov., Cardobairdia longitecta sp. nov., Bairdoppilata turonica sp. nov., Pontocyprella robusta cometa ssp. nov., Pterygocythereis (Diogmopteron) carolinae sp. nov., Bythoceratina (Bythoceratina) saxa sp. nov., Bythoceratina (Bythoceratina) staringi conmacula ssp. nov., Monoceratina minangulata sp. nov., Patellacythere weaveris sp. nov., Schulerides langdonensis sp. nov., Karsteneis nodifera tabasca ssp. nov., Karsteneis oculocosta sp. nov., Karsteneis petasus petasus sp. et ssp. nov., Karsteneis petasus antecursor sp. et ssp. nov., Karsteneis praekarsteni sp. nov., Idiocythere carburnensis sp. nov., Isocythereis postelongata sp. nov., Mauritsina? paradordoniensis sp. nov., Rehacythereis stellatus sp. nov., Rehacythereis venticursus venticursus sp. et ssp. nov., Rehacythereis venticursus patbrowni sp. et ssp. nov., and one new name, Bythoceratina (Bythocertatina) antetumida nom. nov. is introduced for a secondary junior homonym. By comparison with faunas from Devon and the Czech Republic, the biostratigraphical analysis is shown to only have only local significance due to diachronism of Ostracoda. This diachronism is used to explore migration pathways which suggest that the origin of the Turonian ostracod fauna may have had more than one source. A model relating ostracod diversity inversely to sea-level is given for the Cenomanian to Santonian stages of the Late Cretaceous which suggests that the sea-level at Dover during the Turonian was greater than previously thought, given its marginal setting.
14
Smith, Robin James. „Biology and ontogeny of Cretaceous and Recent Cyprididae Ostracoda (Crustacea)“. Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/30470.
Annotation:
Study of the biology and ontogeny of Cretaceous and Recent ostracods shows that the family Cyprididae exhibits conservative evolution over the last 100 million years. The Cretaceous cypridid ostracod Pattersoncypris micropapillosa Bate, 1972, with preserved appendages, is described and details of the limbs of its adults and juveniles are compared with Recent Cyprididae. A detailed study of the ontogeny of the Recent Cyprididae ostracod Eucypris virens Jurine, 1820) reveals that, with the exception of the last podomere on the antennules, the chaetotaxy (distribution pattern of setae) shows continual development on all podomeres of the limbs. Cyprididae ostracods have a pediform limb in the posterior part of the body, presumably to help them to attach to substrates; this is reflected by the pediform nature of one limb in all ontogenetic stages. This study has also shown that the fifth limb is more probably of thoracic origin and, hence, ostracods have only one pair of maxillae. The upper lip and hypostomes of 23 species of Cypridoidea (Podocopina) ostracods were studied and significant variation noted in morphology between species, genera and subfamilies. Several features of the upper lip and hypostome are described for the first time. The morphology of the upper lip can be used to identify species, but it cannot be used to diagnose genera or subfamilies. Spherical objects recovered from acetic acid preparation residues of vertebrate fossils from the Lower Cretaceous Santana Formation of north-east Brazil are postulated to be the eggs of the ostracod Pattersoncypris micropapillosa Bate, 1972. These spheres are phosphatized, range in diameter from 85 to 110 m, and are comparable in many respects to the eggs of several Recent ostracod species.
15
Williams, Mark. „Ostracoda (Arthropoda) of the middle Ordovician Simpson Group , Oklahoma, USA“. Thesis, University of Leicester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315262.
16
Machado, Cláudia Pinto. „(Paleo)zoogeografia dos ostracodes holocênicos das regiões leste e nordeste da plataforma continental brasileira“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/132777.
Annotation:
Os estudos com ostracodes recentes e sub-recentes da plataforma continental do Brasil têmse concentrado, até o momento, principalmente nas plataformas equatorial e sul/sudeste. A região leste/nordeste, localizada entre estas duas áreas, aqui considerada como a área entre o Cabo de São Roque (RN) e Cabo Frio (RJ), não foi devidamente estudada, apresentando diversas lacunas do ponto de vista taxonômico e zoogeográfico. Visando suprir esta carência, o presente trabalho tem por objetivo o estudo da taxonomia dos ostracodes das plataformas leste e nordeste do Brasil, buscando a integração destas informações à compreensão da sua origem e distribuição zoogeográfica. O material de estudo incluiu 102 amostras sedimentológicas, coletadas por amostradores tipo Phipps ou Van Veen, provenientes do projeto REMAC (Reconhecimento Global da Margem Continental), tratos 4 e 7, em profundidades que variaram de 12 a 110 m. Os ostracodes recuperados das amostras foram acondicionados em lâminas de células múltiplas através das técnicas usuais para a preparação e o estudo de carapaças e valvas de ostracodes. Foram reconhecidas 128 espécies não se descartando a possibilidade de espécies novas. A área de estudo é caracterizada por possuir 34% de espécies típicas de águas temperadas, 42% de águas quentes e 5% de espécies euritérmicas. As 19% restantes não puderam ser avaliadas por apresentarem baixa ocorrência. A comparação da distribuição da fauna de águas temperadas com a de águas quentes permitiu a identificação plena dos limites da zona de transição proposta por Coimbra & Ornellas (1989) e modificada por Coimbra et al. (1995). O levantamento total da fauna da porção setentrional da plataforma continental brasileira (entre o Cabo Orange e Cabo Frio) reconheceu 213 espécies, sendo 32% endêmicas. A análise da distribuição da ostracofauna permitiu o reconhecimento de cinco padrões de distribuição da fauna, todos aparentemente limitados por fatores ambientais. Baseado no grau de endemismo, na distribuição da fauna e nas características ambientais da área de estudo, foi proposta uma nova província zoogeográfica, a Província Brasileira, cujo limite sul está em torno das latitudes 15º/16ºS. O limite norte continua em aberto devido à inexistência de trabalhos para Ostracoda na região situada entre a Guiana Francesa e Guiana. Os representantes fósseis da Província Brasileira contam com espécies que ocorrem desde o Terciário. A ostracofauna não endêmica provavelmente teve seu sucesso de dispersão facilitado pelas variações eustáticas que ocorreram ao longo do Neógeno e Quaternário. A presença de massas d’água mais quentes é a característica que melhor explica a distribuição atual dos ostracodes marinhos rasos da porção setentrional da plataforma continental brasileira.The studies concerning Recent and Sub-Recent ostracodes from the Brazilian continental shelf have been so far devoted mainly to the Equatorial and to the South/Southeast shelves. The region between these two shelves, consisting of the area between Cabo de São Roque (RN) and Cabo Frio (RJ), has not been appropriately studied and displays several gaps in Ostracoda taxonomy and zoogeography. In order to improve these deficiencies, the present study approaches the taxonomy of ostracodes form the East and the Northeast Brazilian shelves, aiming at the understanding of its origin and zoogeographical distribution. The 102 samples on which this study is based on were collected by Phillips and Van Veen grabs samplers from Remac Project (legs 4 and 7), at depths that vary from 12 m to 110 m. One hundred twenty-eigth species have been identified, some of which may be new. 34% of the species found in the study area are typical of temperate water, 42% of warm water and 5% are eurythermal. The remaining 13% of the species could not be evaluated due to insufficient occurrence. The comparison of the distribution of the temperate water fauna with the warm water fauna allowed the full identification of the limits of the transition area proposed by Coimbra & Ornellas (1989) and modified by Coimbra et al. (1995). The complete review of the fauna of the northern portion of the Brazilian Continental Shelf from Cabo Orange (AM) to Cabo Frio (RJ) recognized 213 species, 32% of which are endemic. The analysis of the distribution of the ostracode fauna allowed the identification of five distribution patterns, all of which are apparently limited by ambiental factors. A new zoogeographical province (the Brazilian Province) has been proposed. Its southern limit is located in the 15º/16º S latitude. The northern limit remains indeterminate, due to the inexistence of ostracode studies in the region from French Guyana to Guyana. Fossil representatives for the Brazilian Province display specimens that are as old as the Tertiary. The non-endemic ostracode fauna probably has its dispersion success rendered easier by the sea-level fluctuations that occurred in the Neogene and Quaternary. The presence of warmer water masses is the factor that more appropriately explains the present distribution of shallow marine ostracodes in the northern portion of the Brazilian continental shelf.
17
Pereira, Elise Vargas. „Taxonomia e ocorrência das espécies do gênero bromelícola Elpidium (Crustacea: Ostracoda) em áreas de mata atlântica no estado de Santa Catarina, Brasil“. Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-22102013-154642/.
Annotation:
Trabalhos recentes realizados no Brasil apresentaram pelo menos 5 espécies do gênero Elpidium, ostrácode de fitotelmata de bromélia, embora o trabalho de revisão desse gênero propusesse apenas a espécie tipo, E. bromeliarum, com registros do Rio Grande do Sul ao Espírito Santo. No presente trabalho, foram descobertas novas espécies de Elpidium, em amostras coletadas em 2009, em um transecto sul-norte no estado de Santa Catarina, incluindo regiões próximas à localidade tipo de E. bromeliarum. Os animais foram coletados com pipeta e conservados em álcool 70%; as valvas, fotografadas ao microscópio eletrônico de varredura e armazenadas em lâminas micropaleontológicas; os apêndices corporais, dissecados sob estereomicroscópio e transferidos para meio CMC-9AF. Ilustrações dos apêndices das espécies foram realizadas sob câmara clara, sendo que as características diferenciais para cada uma se localizaram no apêndice sexual masculino. Os 4.116 espécimes inventariados, foram contados por sexo, idade e espécie. Mensurações do comprimento, largura e altura das carapaças de 235 espécimes foram realizadas, resultando em 705 medidas. Foram encontradas três espécies de Elpidium: E. bromeliarum e mais duas espécies novas (E. fritzmulleri e E. coimbrai). Diferenças visualizadas nas abas terminais dos apêndices sexuais e tamanhos de carapaças para alguns espécimes de E. bromeliarum foram consideradas como variações intraespecíficas. Um indivíduo que na verdade pertence a E. fritzmulleri sp. n., encontrada em Araranguá, Laguna e Botuverá, havia sido registrado como E. bromeliarum, em Torres, Rio Grande do Sul, em um trabalho anterior. A segunda espécie nova foi encontrada em Içara e Imbituba. Foi elaborada uma chave dicotômica de identificação para as espécies formalmente descritas e nomeadas de Elpidium. As mensurações das carapaças das espécies novas revelaram diferentes tamanhos preferenciais entre as espécies, classificados como grande, médio e pequeno, variando entre 50 a 120 μm. As variáveis ambientais não interferiram de forma determinante na ocorrência das espécies encontradas.Recent studies conducted in Brazil have shown at least 5 species of Elpidium, ostracod from bromeliad phytotelmata, although the work of revision of this genus propose only the type species, E. bromeliarum, with records from Rio Grande do Sul to Espírito Santo. In the present work, were inventoried new species of Elpidium, obtained in samples collected in 2009, in a south-north transect in the state of Santa Catarina, including regions near the type locality of E. bromeliarum. The animals were collected with a pipette and preserved in 70% alcohol; valves were photographed under a scanning electron microscope and stored on micropaleontological slides; appendages were dissected on slides with glycerin under a stereomicroscope and transferred to CMC-9AF mounting medium. Illustrations of the appendages were performed under camera lucida, and the differential characteristics for each were located in the male sexual appendage. The 4.116 specimens inventoried were counted by sex, age and species. Measurements of length, width and height of the shell of 235 specimens were performed, resulting in 705 measures. Three species of Elpidium were recovered: E. bromeliarum and two new species (E. fritzmulleri e E. coimbrai). Differences seen in the end flap of the sexual appendages and sizes of shells of some specimens of E. bromeliarum were considered as intraspecific variation. An individual who actually belongs to E. fritzmulleri sp.n., found in Araranguá, Laguna and Botuverá, was recorded as E. bromeliarum in Torres, Rio Grande do Sul, in a previous work. The second new species was found in Içara and Imbituba. An dichotomous key for identification of species formally described and named of Elpidium was created. Measurements of shells of the new species revealed different preferred sizes between species, classified as large, medium and small, ranging from 50 to 120 μm. Environmental variables did not interfere significantly in the occurrence of species found.
18
El-Waer, Ahmed Ammar. „The Upper Cretaceous and Lower Tertiary Ostracoda from northwestern offshore Libya“. Thesis, University of Hull, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420751.
19
Dickson, Carol Paula. „Quaternary ostracoda from the Celtic and Irish seas : a palaeoenvironmental study“. Thesis, Aberystwyth University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603582.
20
De, Deckker P. „Australian Quaternary studies : a compilation of papers and documents submitted for the degree of Doctor of Science in the Faculty of Science, University of Adelaide /“. Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09SD/09sdd299.pdf.
21
Conway-Physick, Jessica Ann. „The holocene ostracods of the Agulhas Bank, South Africa : their classification, distribution and ecology“. Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/17467.
Annotation:
Bibliography: pages 69-77.An analysis of the Holocene ostracod fauna of the Agulhas Bank has been carried out on seventy-three surficial sediment samples. Sixty-six species of Ostracoda have been recorded, of which fifty-nine species are accounted for in forty genera and the remaining seven species are of indeterminate classification. The species are described and their distribution and ecology is given. An. analysis of the sedimentology, as well as an oceanographic analysis of the bottom water on the Agulhas Bank, has provided environmental parameters for each sediment sample location, enabling relationships to be described between ostracod faunas and environmental conditions. Quantitative factor analysis has been carried out on the twenty-four most abundant species, generating seven factor associations relating ostracod assemblages to a set of environmental parameters. The independent variables analyzed were the temperature, salinity and dissolved-oxygen content of the bottom water, as well as the sand content of the sediment. Contour maps of these variables have been drawn up using SADCO data for the oceanographic variables, and the sediment samples to calculate the sand content. The overall oceanography of the Agulhas Bank has been analyzed by relating the environmental parameters generated at each location to the water masses present on the shelf, and to the oceanic currents affecting them. Finally, the seven factor associations generated have been related directly to the substrate types, the water masses, and the currents present on the Agulhas Bank.
22
Boomer, Ian Desmond. „The taxonomy and temporal distribution of Lower Jurassic Ostracoda from North West Europe“. Thesis, University College London (University of London), 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582009.
23
Wakefield, Matthew Ian. „Ostracoda (Crustacea) of the Great Estuarine Group (Bathonian, Middle Jurassic), Inner Hebrides, Scotland“. Thesis, University of Leicester, 1991. http://hdl.handle.net/2381/34977.
Annotation:
The Ostracoda of the Great Estuarine Group, Inner Hebrides, Scotland are monographed. These are referred to Order Podocopida, Suborder Podocopina, superfamilies Cytheracea, Cypridacea and Darwinulacea, seven families, five subfamilies, 17 genera (three new) and 41 species (25 new, 11 in open nomenclature). The stratigraphic occurrence of the ostracod species is determined for the Islands of Skye, Eigg and Muck. The major lithostratigraphic subdivisions of the Great Estuarine Group are reflected in the ostracod fauna. The ostracod species are largely endemic to the Hebrides; there are generic level affinities with other British sequences. Ostracod genera are used to interpret the palaeosalinity of deposition of the Duntulm and Kilmaluag formations. In some cases the palaeosalinity of deposition of individual beds is corroborated using C & O stable isotope analyses. Three salinity controlled ostracod assemblages are recognised and are interpreted to have migrated within the Kilmaluag lagoon due to increased freshwater or brackish-marine water input. By comparison with the associated molluscs, conchostracans and algae, four salinity events are detected within the type section of the Kilmaluag Formation. The Kilmaluag Formation was deposited within shallow, low energy freshwater lagoons with a tenuous link to a water body of brackish-marine salinity producing a salinity gradient. Salinity is the primary control upon faunal and floral occurrences within the Lealt Shale Formation. Relative salinity tolerances are estimated for 26 ostracod species from the formation. Based upon ostracod and mollusc data this formation has rapidly and frequently fluctuating palaeosalinity values. O isotope analyses of the bivalve Praemytilus strathairdensis show a positive correlation with the palaeosalinity fluctuations; the percentage abundances of the alga Botryococcus show a negative correlation. Variations in the adductor muscle-scar rosette of Darwinula muscula are due to the mostly ontogenetic subdivision of scars. Different fossil and Recent species of Darwinula are shown to have different rosette patterns.
24
Park, Lisa Ellyn. „Assessing diversification patterns in an ancient tropical lake: Gomphocythere (Ostracoda) in Lake Tanganyika“. Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187316.
Annotation:
I examined the distribution of 70 morphological characters for 17 extant species of an ostracod genus, Gomphocythere, in Africa, to test hypotheses concerning character development and speciation patterns. Using heuristic searches conducted with the phylogenetic reconstruction program PAUP, I found 9 trees of 269 steps (CI = 0.45). The skewness of tree length distribution reveals significant phylogenetic structure in the data. Nodes are supported by 2 to 13 character state changes, and these character changes are sometimes reversed or paralleled elsewhere, accounting for much of the homoplasy in the reconstructions. The results suggest the presence of four new species (Gomphocythere coheni, G. downingi, G. wilsoni, G. woutersi). These species are relatively derived within the favored tree. Analyses were done to elucidate the effect of the exclusion of hard and soft part characters and the effects of differential fossil preservation on phylogenetic reconstruction. Eliminating the hard part characters caused the collapse of many branches as polytomies and decreased the agreement of the hard part trees. Excluding the soft part characters increased the number of most parsimonious trees, and decreased the resolution of the trees by creating many unresolved polytomies, but produced similar islands of stability as the complete analysis. I integrated phylogenetic and ecological data sets to examine ecological variables of substrate and depth range and their role in speciation of Gomphocythere in Lake Tanganyika. Using one-way MANOVAs on substrate distribution data, I found significant variability in the substrate distribution of (p =.001) seven species. In addition, principle components analysis and R-mode cluster analysis revealed close associations between certain species with respect to substrate ranges. Correlations exist between species and their ecological tolerances, indicating that environmental fluctuations could have had a profound effect on speciation. In addition, evidence for multiple invasions of Gomphocythere species exist from mapping endemism onto the phylogenetic tree. From this information, a model of speciation emerges in which there have been multiple invasions and subsequent radiations.
25
Frewin, J. „Palaeogene ostracods from the South African continental shelf“. Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/17003.
Annotation:
Bibliography: pages 147-155.92 cytheracean species, representing 44 genera are recorded from the Palaeogene Agulhas Bank and west coast margin of South Africa. 11 genera and 3 species are common with the Upper Cretaceous faunas. 12 genera (18 species) are left in open nomenclature. The following genera are represented:- Bythoceratina, Incongruellina, Ruggieria, Eucythere, Krithe, Parakrithe, Eucytherura, Cytheropteron, Ambostracon, Urocythereis, Muellerina, Leguminocythereis, Loxoconcha, Schlerochilus, Poseidonamicus, Bradleya, Agrenocythere, Australileberis, Chrysocythere, Costa, Echinocythereis, Haughtonileberis, Henryhowella, Parvacythereis, Phacorhabdotus, Soudanella, Stigmatocythere, Togoina, Trachyleberis, Veenia, Atlanticythere, Xestoleberis. Data on South African Cretaceous and Palaeogene ostracod faunas are discussed in terms of: faunal associations for the South African Palaeogene JC-1, Agulhas Bank and west coast provinces; characteristic species of Upper Eocene and Upper Eocene to Oligocene strata; generic variations across the Cretaceous/Tertiary boundary. Palaeo-environmental trends from a Cytheracea, Cypridacea + Bairdiacea, Cytherellidae (CCBC) plot indicate a sea level change from <100m (Palaeocene- Eocene), to shallower water with restricted circulation (Upper Eocene) to moderate depth, 100 - 200m (Lower Oligocene). South African faunas are compared with those from adjacent Palaeogene ostracod faunal provinces. Strong generic links occur with West Africa (8 genera in common) and Pakistan (9 genera in common) with only 3 genera in common with Australia and 3 with Argentina.
26
Sepúlveda, Priscila dos Santos. „Uso da espectroscopia no infravermelho com transformada de Fourier na avaliação de efeitos ecotoxicológicos subletais sobre Ostracodes Chlamydoteca sp“. Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-29112018-103811/.
Annotation:
Com o crescimento populacional e aumento das atividades humanas, grandes quantidades de poluentes são despejadas diariamente no meio ambiente. Nos ecosssistemas aquáticos, organismos são expostos por longos períodos à baixas concentrações de contaminantes. Assim estudos que focam em novas metodologias que sejam rápidas e não invasivas, são necessários para a avaliação de efeitos subletais. Um exemplo é a espectroscopia no infravermelho com transformada de Fourier (FTIR). Esta técnica é capaz de detectar alterações macromoleculares em amostras biológicas de forma rápida e não destrutiva, sendo uma ferramenta atrativa para análises ecotoxicológicas. Assim, o objetivo deste estudo foi verificar a aplicabilidade do FTIR como metodologia alternativa, utilizando perfis de composição macromoleculares como indicadores de efeitos subletais, em organismos expostos a elementos-traço. Para tal, ostrácodes (Chlamydoteca sp.) foram expostos aos elementos Cu, Cd, Hg e Mn. As alterações em perfis biomoleculares foram avaliadas em ostrácodes expostos por 48h ao Mn. Os resultados revelaram uma correlação negativa entre concentração de exposição e proporção de ácidos graxos saturados e insaturados com relação à proteína em organismos expostos ao Mn e a mesma correlação foi observada para o conteúdo de ácidos nucléicos. Isto sugere que os organismos tiveram seu metabolismo lipídico e sua capacidade de produção de proteína celular alterados devido à exposição ao Mn. Ademais, foram realizados testes crônicos (9 dias) com ostrácodes expostos ao Cu, Cd, Hg e Mn. Foi observada a diminuição de lipídios saturados e insaturados em relação à proteína em organismos expostos ao Cd, sugerindo o uso de reservas lipídicas devido ao estresse fisiológico. Ostrácodes expostos ao Cu, tiveram o aumento dos ácidos nucléicos, no qual o DNA pode ter sido o componente dominante. Alterações significativas relacionadas ao conteúdo de carbonato de cálcio foram reveladas nos organismos expostos ao Cd e ao Cu, o que sugere mudanças na composição da carapaça e possível alteração na capacidade de muda e crescimento dos organismos. Portanto, este estudo permite concluir que a espectroscopia de FTIR é capaz de detectar indícios de efeitos subletais em organismos expostos a contaminantes e que as alterações de composição macromolecular são uma ferramenta complementar promissora para futuras avaliações ecotoxicológicas.With population growth and increases in human activities, large amounts of pollutants are released daily into the environment. In aquatic ecosystems organisms are exposed for long periods at low concentrations of contaminants. Therefore, studies that focus on fast and non-invasive new methodologies are necessary for the assessment of sublethal effects in organisms. An example is the Fourier Transform Infrared Spectroscopy (FTIR). This technique can detect macromolecular changes of biological samples in a fast, inexpensive and non-destructive way, all of which lend to the attractiveness of this methodology for ecotoxicological analyzes. Thus, the aim of this study was to verify the applicability of FTIR as an alternative methodology, using the composition of macromolecular profiles as an indicator of sublethal effects in organisms exposed to trace elements. For this, ostracods (Chlamydoteca sp.) were exposed to the elements Cu, Cd, Hg and Mn. Changes in biomolecular profiles were evaluated in ostracods exposed for 48h to Mn. The results showed a negative correlation between the concentration of exposure and the proportion of saturated and unsaturated fatty acids for protein in organisms exposed to Mn and the same correlation was observed for the content of nucleic acids. This suggests that the organisms had their lipid metabolism and their cellular protein production capacity altered due to Mn exposure. In addition, four chronic tests (9 days) were performed on ostracods exposed to the trace elements Cu, Cd, Hg and Mn. A decrease in saturated and unsaturated lipids in relation to the protein was observed in organisms exposed to Cd, suggesting that the use of lipid reserves was due to the physiological stress. Ostracods exposed to Cu had an increase in nucleic acids, in which DNA may have been the dominant component. Significant changes related to the calcium carbonate content were revealed in the organisms exposed to Cd and Cu, which suggests changes in carapace composition and the possible alteration in the organism capacity of molting and growth. Therefore, this study concludes that FTIR spectroscopy can detect indications of sublethal effects in organisms exposed to contaminants and that changes in macromolecular composition are a promising complementary tool for future ecotoxicological assessments.
27
Abke, Rodney Alan. „A fossil assemblage of ostracoda, foraminifera, and gastropoda of the West Texas salt flats“. Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/897497.
Annotation:
The salt flats of west Texas are large ephemeral lakes, Pleistocene to Holocene in age. The evaporite material in these lakes represents the sedimentary history of the lake and the surrounding area. Recently, a fossil assemblage was found in the sediments of this deposit. This assemblage includes four species of ostracoda (Limnocvthere staplini, Candona rawsoni, Candona thomasi, and Cvprideis salbrosa), two species of gastropoda, (Amnicola decepta, and Amnicola pilsbrvi), and discovery is significant because this assemblage has not been previously reported, and it provides an opportunity to reconstruct part of the physical and chemical environment of the salt flats during a portion of its history. Autecological comparison of these species indicate that they lived in a shallow, alkaline, brackish water environment. The known paleoclimate of the area, and the sedimentology support this interpretation.Department of Geology
28
Zazzali, Sindbad. „Paléobiodiversité des ostracodes à la limite Permien moyen - Permien supérieur“. Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066111/document.
Annotation:
Les ostracodes, microcrustacés (Arthropoda), sont relativement abondants dans les archives paléontologiques. Sensibles aux variations paléoenvironnementales, la composition des assemblages et leur diversité sont d’excellents marqueurs des changements qui affectent le benthos marin néritique. Leur diversité est connue pour être fortement affectée par la crise biologique marquant la limite Permien-Trias, mais leur histoire à la fin du Permien moyen reste peu documentée.Près de 10 Ma avant la limite Permien-Trias, à la fin du Permien moyen, un important épisode d’extinction intervient, préfigurant le déclin de la biodiversité à la fin du Paléozoïque.L’étude systématique des échantillons prélevés le long des coupes de Chaotian (province du Sichuan, Chine) et de Penglaitan (province du Guangxi, Chine) a permis l’identification de 115 espèces d’ostracodes, dont 7 nouvelles. Le travail réalisé sur ces coupes constitue la toute première étude des événements de la fin du Permien moyen et du début du Permien supérieur s’appuyant sur l’observation des assemblages d’ostracodes. L’état de conservation des carapaces d’ostracode, étudié lors de ce travail, enregistre les effets de la fin d’un épisode de régression et le début d’un épisode de transgression au sommet du Permien moyen à Penglaitan. Les résultats s’avèrent en accord avec les données lithologiques et paléontologiques présentées dans la littérature, un modèle de reconstitution paléoenvironnementale basé sur les données de préservation des ostracodes est proposé.Une analyse critique de la qualité du jeu de données a permis d’évaluer l’influence des biais d’échantillonnage sur la représentativité du matériel fossile dans les études sur la paléobiodiversité et la paléoécologie. Les biais peuvent être corrigés par un traitement méthodologique approprié qui rend valide la comparaison des données de biodiversité. La richesse générique et spécifique décroît sensiblement au cours du Capitanien. Le passage du Permien moyen au Permien supérieur enregistre une augmentation de la richesse spécifique, malgré une faible diversité générique. L’ordre des Palaeocopida apparait ici affecté par une baisse de diversité générique et spécifique au Wuchiapingien inférieur. Si ces résultats ne permettent pas pour l’iPermiannstant de caractériser un événement global de renouvellement des communautés d’ostracodes, l’étude de matériel fossile provenant d’autres régions du monde permettra de définir l’ampleur des phénomènes observésOstracods, microcrustaceans (Arthropoda), are quite abundant in the fossil record. Highly dependent to palaeoenvironmental conditions, their diversity and the assemblages’ composition are good indicators of changes affecting neritic marine benthos. Ostracods are known to be deeply affected by the Permian-Triassic crisis, but their history is poorly documented for the end of Middle Permian.About10 My before the Permian-Triassic boundary, the end of Middle Permian is characterized by a major extinction episode, which could be the first step of end-Palaeozoic biodiversity drop.Systematic study carried out on Chaotian section (Sichuan Province, P.R. China) and the Penglaitan section (Guangxi Province, P.R. China) samples allowed the identification of 115 species, including seven new species. The work carried out on these two sections provides the first study of end-Middle Permian extinction event, based on the observation of ostracod assemblages.Study of carapace preservation at Penglaitan section, highlighted the end of a regression phase and the beginning of a transgression phase at the top of Middle Permian. These results are relevant with lithologic and palaeontological data from literature. Thus, a palaeoenvironmental reconstruction model has been proposed, based on ostracod preservation data.An estimation of sampling bias consequences on fossil dataset representativeness in palaeobiodiversity and palaeoecology studies was realised. These biases could be corrected by an appropriate methodology allowing comparisons of biodiversity datum. Biodiversity data reveals a decrease of generic and specific richness during Capitanian. Specific richness increased passing the Middle-Upper Permian boundary. Palaeocopida order seems here affected by a generic and specific richness decline at basal Wuchiapingian. If these results do not allow for the time being to characterize a global ostracod turnover, further studies on material from other regions in the world will allow defining the extent of the observed phenomena
29
Al-Bashir, Jenan Mohammad T. „Cretaceous ostracoda of the super family Cytheracea from Iraq, their biostratigraphy and correlation with adjacent regions“. Thesis, University of Glasgow, 1986. http://theses.gla.ac.uk/1462/.
Annotation:
The cretaceous ostracods of Iraq are poorly known, so the aim of the project was to study their taxonomy and to discover their value in correlation between wells in Iraq and between Iraq and neighbouring countries. The Cenomanian-Santonian ostracods of the superfamily Cytheracea were studied in detail from five wells in central and southern Iraq (East Baghdad Well-3, South Rumaila Well-104, Safawi Well-1, Ghalaisan Well-1, and Kifl Well-2). 5 families, 6 subfamilies, 28 genera, 4 subgenera and 74 species were discovered. Two new genera, Iraqicythereis and Archeocosta (the latter published by Al-Bashir and Keen in 1984 during the preparation of this thesis) and one subgenus Peloriops (Hemipeloriops) are proposed; of the 74 species described 58 are new. Four ostracod biozones and three subzones are proposed for the areas studied on the basis of the Cytheracea ostracods; these are arranged from the base to the top as follows: Veeniacythereis streblolophata - Veeniacythereis maghrebensis - Total Range Zone (A-1); Dumontina? mdaouerensis - Partial Range Zone (A-2); Veeniacythereis ibnalhaithami - Partial Range Zone (A-3); Peloriops (Peloriops) alrazii - Partial Range Zone (A-4). The Veeniacythereis streblolophata - Veeniacythereis maghrebensis - Total Range Zone is subdivided into three subzones: A - Glenocythere bahrreinensis - Total Range Subzone (A-1a), B - Soudanella? alkhansai - Assemblage Subzone (A-1b), and C Cythereis alfarazdaki - Assemblage Subzone (A-1c). The ages of the zones and subzones have been determined from a study of the diagnostic ostracod species and stratigraphic position. A Cenomanian age is assigned to A-1 zone; the A-1a and A-1b subzones are of Lower Cenomanian age; a Lower Turonian age is suggested for the A-2 zone; Upper Turonian-Coniacian for the A-3 zone; and a Santonian age for the A-4 zone. The ostracod zones and subzones have been recognised in each of the wells studied. The age of the formations studied has been determined on the basis of the ostracod fauna and stratigraphic position. The upper part of the Mauddud Formation, and the Ahmadi Formation are assigned to the Lower Cenomanian; the Rumaila Formation is placed in the Upper Cenomanian; the Mishrif Formation is placed in the Upper Cenomanian to Lower Turonian; the Kifl Formation is placed in the Lower Turonian; the Khasib Formation is placed in the Upper Turonian-Lower Coniacian; the Tanuma Formation is placed in the Upper Coniacian, although it may include strata of Santonian age in some localities; and the Sadi Formation is assigned to the Santonian. The Ahmadi/Rumaila contact in Ghalaisan Well-1 is placed at the top of the Soudanella? alkhansal subzone. The lower part of the Rumaila Formation in East Baghdad Well-3 is contemporaneous with the Ahmadi Formation on the basis of the occurrence of the Glenocythere bahreinensis Subzone, and is considered to be of Lower Cenomanian age. In Kifl Well-2 the Maotsi Formation is probably of Upper Cenomanian age and the Mahilban and Fahad Formations may be of Lower Cenomanian age. The base of the Khasib Formation is marked by the appearance of many new ostracod species and genera such as Acanthocythereis, Brachycythere, Buntonia, Paracytheridea, Protobuntonia and Phymacythereis. This indicates a major faunal break between the Mishrif/Kifl Formation below and the Khasib Formation above. This faunal break is marked by an unconformity referred to as the Aruma-Wasi unconformity which is recognised throughout the Arabian Gulf. The ostracod biozones of Iraq have been correlated with corresponding zones in other Middle Eastern and North African countries. Problems of variation in the size of some ostracods have been studied. There is a considerable range in size of Peloriops (Peloriops) ulosa, Rehacythereis arabica, Brachycythere basrahaensis sp. nov., Archeocosta alkhazwinii, Veeniacythereis maghrebensis, and Veeniacythereis ibnalhaithami sp. nov. The size range appears to be continuous, and the smaller specimens are considered to be adult. This size variation appears to exclude precocious sexual dimorphism as well as the possibility of larger and smaller forms belonging to two closely related species. It is difficult to determine whether the size variation is due to environmental or genetic causes. Intra-specific variation in ornamentation of the following species has sbeen studied: Iraqicythereis Kadisiya gen. et sp. nov., Veeniacythereis ibnalhaithami sp. nov., Cythereis? ibnyunusi sp. nov., Peloriops (Peloriops) sphaerommata, Peloriops (Hemipeloriops) djabirbnhaiyani sp. nov., and Metacytheropteron berbericus. This variation may be continuous or discontinuous. In the first case it is difficult to recognise distinct morphotypes, but in the second case it is possible to separate them into distinct morphotypes. The morphotypes appear to represent a case of stable polymorphism. The variation is believed to be genetically controlled. The environments of deposition have been determined by using the characteristic ostracod species and other fauna (e.g. foraminifera), and type of sediment. The Ahmadi Formation was deposited in an open, shallow, neritic environment with restrictions in some areas. The Rumaila Formation is distinguished by its low species diversity and poor fauna, but this is considered to be due to preservation rather than environmental conditions. Generally the Rumaila Formation represents deeper water conditions than those of the Ahmadi Formation, becoming shallower with restrictions from the sea in some areas. The Mishrif Formation indicates open shallow water neritic conditions followed by a shallowing phase associated with oscillations of sea level, or with an influx of fresh water. The Kifl Formation represents shallow water conditions partly connected with the open sea, accompanied with the development of lagoonal areas. The Khasib and the Tanuma Formations indicate open shallow marine conditions (infra-neritic), but in some areas (in East Baghdad Well-3 and Kifl Well-2) coastal conditions are suggested, perhaps with restricted access to the open sea because of the presence of a poor ostracod fauna dominated by Ovocytheridea.
30
Miller, Christopher Giles. „Micropalaeontology (Conodonta, Ostracoda) across the Ludlow/Pridoli series boundary (Silurian) of Wales and the Welsh Borderland“. Thesis, University of Leicester, 1993. http://hdl.handle.net/2381/35070.
Annotation:
The ostracod and conodont micropalaeontology of the Silurian Ludlow/Pridoli series boundary is documented from 88 localities across Wales and the Welsh Borderland. Fourteen multielement conodont species (two in open nomenclature), eight unassigned Ozarkodina elements and ten ostracod species (four in open nomenclature) are described from the Upper Whitcliffe and Downton Castle Sandstone formations and their lateral equivalents in Wales and the Welsh Borderland. A septimembrate prionodontid conodont apparatus Coryssognathus dubius (Rhodes, 1953) is reconstructed from discrete elements. Original calcareous valves of the ostracod Frostiella groenvalliana and moulds of open and partially open ostracod carapaces are described for the first time from the Welsh Basin. The Upper Whitcliffe Formation and its lateral equivalents are characterised by the ostracod Calcaribeyrichia torosa and the conodonts Ozarkodina confluens, Ozarkodina excavata, Panderodus serratus and Coryssognathus dubius. The Downton Castle Sandstone Formation and its lateral equivalents are characterised by the ostracods F. groenvalliana, Londinia arisaigensis, Londinia fissurata and Nodibeyrichia verrucosa. Conodont trends across the shelf area of the Welsh Borderland reflect an increasingly turbulent environment towards the top of the Ludlow Series. The sudden ostracod faunal change at the base of the Downton Castle Sandstone at Ludlow (shelf) contrasts with a gradual change at Long Mountain (basin) and parallels shelf-basin palynofacies changes. Variations in ostracod frequency, faunal composition and carapace preservation in the Downton Castle Sandstone Formation at Ludlow coincide with minor lithofacies variations. Local variations in the frequency of ostracods and land plant spores may be related to proximal channels delivering sediment off an irregularly prograding shoreline. Ostracod faunas correlate the base of the Downton Castle Sandstone across the Welsh Borderland to localities in E central Wales where bone beds are absent. Combined conodont and ostracod evidence suggests that the base of the Pridoli Series is concurrent with the base of the Downton Castle Sandstone Formation in Britain.
31
Ingalls, Brian R. „Biotic and taphonomic response to lake level fluctuations in the Greater Green River Basin (Eocene), Wyoming“. University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1153505477.
32
Bottezini, Silvia Regina. „Ostracoda (Crustacea) holocênicos do Arquipélago de São Pedro e São Paulo: riqueza e aspectos ecológicos e zoogeográficos“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/131936.
Annotation:
O Arquipélago de São Pedro e São Paulo (ASPSP) localiza-se cerca de 1100 km do litoral do Rio Grande do Norte, e está constituído por quatro ilhas maiores dispostas em semicírculo formando uma enseada com profundidades que variam ente 3 a 18 m. Vários estudos sobre a fauna existente no ASPSP foram realizados, entretanto, este é apenas o segundo trabalho com foco na ostracofauna do arquipélago. No material analisado, coletado na enseada, foram reconhecidas 14 espécies, dez gêneros e oito famílias; dentre estes, foi descrito um gênero e espécie novos para a família Hemicytheridae e uma nova espécie para o gênero Keijcyoidea. Dez espécies foram deixadas em nomenclatura aberta, sendo muito provável a existência de outras espécies novas, já que o ASPSP é uma área muito distante tanto de outras ilhas oceânicas quanto de continentes. Aspectos ecológicos e zoogeográficos complementam o estudo da riqueza específica da fauna aqui analisada. Loxocorniculum tricornatum Krutak possui a maior abundância, perfazendo um total de 4214 espécimens (1150 coletados vivos). Keijcyoidea sp. nov. A (539 espécimens, sendo 153 vivos) e Xestoleberis sp. 2 (179 indivíduos, dos quais 69 vivos) ocupam o segundo e o terceiro lugar em abundância, respectivamente. As espécies L. tricornatum e Triebelina sertata Triebel, esta última um ostracode cosmopolita tropical, ocorrem no Brasil não somente no ASPSP, mas também no Atol das Rocas e nas regiões de águas quentes da plataforma continental brasileira; T. sertata é também registrada na Ilha da Trindade. Curiosamente, espécies pandêmicas de mares rasos e quentes, como Kangarina abyssicola (Mueller), Kotoracythere incospicua Brady, Keijia demissa Teeter, Neomonoceratina mediterranea (Ruggieri) e Tenedocythere ex. gr. transoceanica Teeter, não foram registrados no ASPSP.The Archipelago of São Pedro and São Paulo (ASPSP), located about 1,100 km of the coast of the Rio Grande do Norte State, consists of four major islands arranged in a semicircle forming a cove with depths between three and 18 m. Many studies on the archipelago fauna were performed, however, this is only the second one focusing its ostracode fauna. In the study material, 14 species, ten genera and eight families were identified, including a new genus and species of Hemicytheridae, and a new species of Keijcyoidea. Ten species were left in open nomenclature, and the existence of other new ones is very probable, since the ASPSP is very distant from both other oceanic islands and continents. Ecological and zoogeographical remarks complement this faunal study. Loxocorniculum tricornatum Krutak possesses the greatest abundance, with a total of 4214 specimens (1150 collected alive). Keijcyoidea sp. nov. A (539 specimens, being 153 alive) and Xestoleberis sp. 2 (179 individuals, being 69 alive) occupy the second and third place in abundance, respectively. The species L. tricornatum and Triebelina sertata Triebel, the latter a tropical cosmopolitan ostracode, occur in Brazil not only in the ASPSP, but also in the Rocas Atoll and in the region of warm waters of the Brazilian continental shelf; T. sertata is also recorded around the Trindade Island. Surprisingly, pandemic species of shallow and warm seas, as Kangarina abyssicola (Mueller), Kotoracythere incospicua Brady, Keijia demissa Teeter, Neomonoceratina mediterranea (Ruggieri) and Tenedocythere ex. gr. transoceanica Teeter, were not found in ASPSP.
33
White, Tom Samuel. „Late middle Pleistocene molluscan and ostracod successions and their relevance to the British Paleolithic record“. Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648393.
34
McFarland, Andrew J. „Using Ostracode Dynamics to Track Ecosystem Response to Climatically and Tectonically Induced Lake-Level Fluctuations in Fossil Basin, Green River Basin, Wyoming, USA“. University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1348242706.
35
Sipahioglu, Sara M. „Tracking storms through time event deposition and biologic response in Storr's Lake, San Salvador Island, Bahamas /“. Akron, OH : University of Akron, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1227031927.
Annotation:
Thesis (M.S.)--University of Akron, Dept. of Geology, 2008."December, 2008." Title from electronic thesis title page (viewed 12/13/2009) Advisor, Lisa E. Park; Faculty Readers, Ira D. Sasowsky, John Peck; Department Chair, John P. Szabo; Dean of the College, Ronald F. Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
36
Pyne, Rebecca Sian. „The biostratigraphy, palaeoecology and taxonomy of Upper Cretaceous (Coniacian to Lower Maastrichtian) Ostracoda from the chalk of East Anglia“. Thesis, Aberystwyth University, 2001. http://hdl.handle.net/2160/dee9218f-08c1-4d29-99ce-57a20d1343a1.
Annotation:
The thesis is based on 205 sediment samples supplied by the British Geological Survey from the Trunch Borehole and various outcrop localities in Norfolk and Suffolk. At least 80,000 ostracod specimens were recovered, belonging to 151 species and 53 genera. These are fully illustrated and described in a large systematic taxonomy chapter. Seventeen species and I subspecies were described as new. A stepped pattern of origination and extinction occurs throughout the Upper Chalk of East Anglia and the Ostracoda thereby display high biostratigraphical potential. The large number of Lazarus taxa in the Santonian and Lower Campanian is a distinctive feature. An analysis of the percentage of filter feeding platycopid Ostracoda, as a measure of palaeoxygen levels, reveals large variations in the amounts of dissolved oxygen in the Upper Cretaceous of East Anglia. High percentages of platycopids equate to low oxygen and vice versa. This is confirmed by the fact that high levels of platycopids are always associated with low species diversity. Using this technique, it was shown that the Coniacian was a time of low to very low oxygen, except for the upper part (coranguinum Zone) which was better ventilated. The Santonian and Lower Campanian were low to very low in dissolved oxygen, while the Upper Campanian and Lower Maastrichtian had much higher levels of dissolved oxygen. The term "Kenoxic Event" can be used to describe such periods of lowered oxygen, when instar-brooding platycopids display a preferential survival potential compared to podocopids. Notwithstanding these general trends, oxygen levels appear to have fluctuated rapidly throughout the interval of study. These fluctuations are thought to be due to the Oxygen Minimum Zone and its migrations onto the continental shelf and subsequent retreat to the continental slope; low oxygen levels on the continental shelf being extremely deleterious to all other Ostracoda other than platycopids resulting in low diversity. High diversity and high oxygen are associated with the retreat of the OMZ onto the continental shelf. This in turn is related to sea level fluctuations and the technique shows good potential for use in sequence stratigraphy. A model showing the position of the Oxygen Minimum Zone during the Upper Cretaceous in East Anglia was produced from platycopid data generated by this study
37
Miranda, Fabricia Sousa de. „Ocorrência de ostracoda no médio Rio Doce/MG e revisão do estado da arte do estudo desse grupo no Brasil“. Universidade Federal de Minas Gerais, 2008. http://hdl.handle.net/1843/BIRC-8A8SNM.
Annotation:
The more important caracteristics of Ostracoda were reviewed, as well a survey of several scientific researches about freshwater and semi-terrestrial ostracods. Beyond these selections of researches about Brazilian fauna, this paper offers to reader a check list making evidence of
ostracods richness. The main idea was prepare a data basis which became promptness accessible the knowledge of relevant researches about Brazilian ostracods. It was found less searchers involved with recent ostracds than involved with fossil ostracods in Brazil. To finish, the kind of developed researches in another country, and in Brazil, it was organized to make easy the estimate to research that have ever being developed concerning recent Ostracoda.As características mais relevantes dos Ostracoda foram revisadas, bem como um levantamento dos trabalhos científicos de diversas naturezas sobre ostrácodes de água doce e ambientes semi -terrestres. Além deste levantamento sobre a fauna de ostrácodes do Brasil, o presente estudo ainda oferece ao leitor um check list evidenciando a riqueza desse grupo. A idéia principal seria disponibilizar ao leitor uma base de dados que torne prontamente acessível o conhecimento dos trabalhos de relevante interesse científico desenvolvidos por pesquisadores brasileiros sobre os ostrácodes. Foi observado menor número de pesquisadores que atuam diretamente com ostrácodes recentes de água doce que pesquisadores voltados para ostrácodes fósseis no Brasil. Para finalizar, os tipos de pesquisas desenvolvidas em outros países, bem como no Brasil, foram organizados para facilitar a apreciação dos estudos que vêm sendo desenvolvidos sobre Ostracoda recentes.
38
Sudomir, Judith C. „Effects of multiple time scale water level fluctuations on a Great Lakes Coastal Wetland Community“. Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1271704850.
39
Koyama, Kristina. „Studies on development in Euphilomedes ostracods: Embryology, nervous system development, and the genetics of sexually dimorphic eye development“. Scholarly Commons, 2017. https://scholarlycommons.pacific.edu/uop_etds/2978.
Annotation:
Model organism studies have been fundamental in understanding evolutionary and developmental biology. However, non-model organisms present opportunities to study unique characteristics and as comparisons to model organisms, leading us toward broader and more relevant perspectives on diversity. The Euphilomedes genus of ostracods is an example of a non-model group with potential for evolutionary and developmental studies.
Ostracoda is an ancient, basally branching lineage of Crustaceans with a complete and prodigious fossil record. Despite the group’s promise for evolutionary studies, much remains unknown about the basic biology of this clade. There are a limited number of embryogenesis studies in Ostracoda; here, I study development in Euphilomedes.
In Chapter 1, I study the main events in Euphilomedes’ embryology, focusing on cleavage and cell migration. I describe the general embryology of Euphilomedes, and devise a visual staging scheme for their development. Using fluorescent nuclear staining and microscopy, I visualize nuclei in cleavage throughout development of nuclear divisions and migrations during development. The meroblastic cleavage observed in Euphilomedes resembles that of another Myodocopid ostracod, Vargula hilgendorfii.
Finally, immunostaining for acetylated-alpha tubulin and phalloidin staining are used to visualize the general anatomy of the embryonic brain. This provides new protocols for visualizing the nervous system, enabling more detailed nervous system studies in the future.
In Chapter 2, I explore differential gene expression patterns in the developing eyes of juvenile Euphilomedes. Euphilomedes have sexually dimorphic eye types – males have lateral compound eyes, while females instead have eye rudiments. Previous studies in E. carcharodonta show that genes in the retinal determination and phototransduction gene networks have differential expression in males and females during eye development. In this thesis, we attempt to compare these patterns to expression in a sister species, E. morini.
40
Sipahioglu, Sara M. „Tracking Storms through Time: Event Deposition and Biologic Response in Storr’s Lake, San Salvador Island, Bahamas“. University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1227031927.
41
Luz, Nathália Carvalho da. „O gênero xestoleberis sars, 1866 (crustacea-ostracoda) nas plataformas norte, nordeste e leste e no arquipélago de São Pedro e São Paulo, Brasil“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/114395.
Annotation:
Os ostracodes constituem um importante grupo de microcrustáceos que tem despertado o interesse tanto das biociências quanto das geociências. Para tanto, é fundamental o estudo taxonômico destes organismos e o entendimento de sua distribuição e ecologia. Os trabalhos realizados na plataforma continental brasileira muito têm contribuído para o conhecimento do grupo, que é bastante diverso. Porém, a riqueza e complexidade dos ostracodes ressaltam a necessidade de mais estudos também na plataforma. Em ilhas oceânicas brasileiras, as pesquisas com ostracodes ainda é muito recente, com poucos trabalhos publicados. A importância de estudar os ambientes insulares reside no fato de tais áreas colaborarem para o entendimento da diversidade, biogeografia e evolução dos organismos. O presente trabalho visa aumentar o conhecimento do grupo na plataforma continental do Brasil, mais especificamente nas regiões Norte, Nordeste e Leste, e no Arquipélago de São Pedro e São Paulo (ASPSP), através do estudo do gênero Xestoleberis Sars. Este gênero é bastante diversificado e amplamente distribuído em todos os oceanos, e, no Brasil, ocorre ao longo de toda a plataforma, além das ilhas oceânicas. Foi registrado um total de oito espécies nas áreas estudadas, sendo duas endêmicas ao ASPSP e seis pertencentes à plataforma. Das espécies encontradas na plataforma continental, quatro são novas, uma foi mantida em nomenclatura aberta e uma já havia sido previamente descrita.The ostracods represent an important group of microcrustaceans that has aroused interest in biosciences and geosciences. For this, it is crucial the taxonomic study of these organisms and to understand their distribution and ecology. The works conducted in the Brazilian continental shelf contributed greatly to the knowledge of this group that is quite diverse. However, the great richness and complexity of ostracods highlight the need for more studies also in the platform. In the Brazilian oceanic islands, the searches on these crustaceans are still very recent, with a few numbers of published works. The study of insular habitat collaborates with the understanding of diversity, biogeography and evolution of the organisms. The present work aims to increase the knowledge of the group in the Brazilian continental shelf, specifically in the Northern, Northeastern and Eastern regions, and in the Archipelago of São Pedro and São Paulo (ASPSP), with the study of the genus Xestoleberis Sars. This genus is diversified and widely distributed in all oceans and in Brazil occurs along the entire shelf and in oceanic islands. Eight species were recorded in the study areas, two species are endemic to the ASPSP and six belong to the continental shelf. Among the platform species, four are new, one was maintained in open nomenclature and one was already described.
42
Bowles, Rachel E. „The Use of the Ostracode Cyprideis Americana (Sharpe) as a Proxy for Salinity in Bahamian Lake Systems“. TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1272.
Annotation:
Ostracodes, bi-valved crustaceans, are potentially excellent proxies for salinity.They are abundant, react to changes in salinity, and secrete low-magnesium calcite shells that preserve information about their host water chemistry. Changes in valve trace element concentration, stable isotope composition, and sieve pore shape values have been linked to changes in salinity. This study analyzed the response of the euryhaline ostracode, Cyprideis americana, to salinity in six lakes from two Bahamian islands across two seasons. The purpose of this work was to determine which compositional and morphological variables in C. americana are the most useful for paleosalinity reconstructions.Ostracode and water samples were collected from lakes of varying water chemistry on San Salvador Island (winter and summer seasons), and Exuma (winter season). Dissolved oxygen, pH, salinity, and temperature measurements were taken for each lake. The best-preserved valves from each lake were analyzed for sieve pore circularity, Mg and Ca concentrations, and δ18 O isotopic composition. Mg/Ca ratios and Kd[Mg] values were calculated for each lake. Each parameter was plotted against salinity for all of the lakes and for lakes from each season and island. Only the samples collected during the summer followed expected trends: with increases in lake water salinity, Mg/Ca ratio decreased, δ18 O composition increased, and sieve pore circularity decreased. Samples collected from the winter field sessions did not follow expected trends, potentially due to the breeding and moulting habits of C. americana. Temperature was more correlative with valve composition than a previous study of C. americana suggests, but is supportive of similar correlations of Cyprideis species in continental and other island settings. The valve Mg/Ca ratio and mean sieve pore circularity showed the best correlation with salinity and are the variables that will be most useful in paleosalinity studies from sediment cores. Future work should further investigate the relationship between mean sieve pore circularity and lake salinity as well as the breeding and moulting habits of C. americana. Such work may allow for past salinity ranges to be reconstructed from fossil C. americana samples.
43
Utida, Giselle. „Fósseis em micritos quaternários da Serra da Bodoquena, Bonito-MS e sua aplicação em estudos paleoambientais“. Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/44/44141/tde-08062009-163642/.
Annotation:
O município de Bonito e arredores em Mato Grosso do Sul apresentam atrações turísticas relacionadas a diversos tipos de depósitos carbonáticos quaternários, que formam cachoeiras, barragens naturais e tornam as águas de turbidez quase nula. A área está inserida no Parque Nacional da Serra da Bodoquena e na Reserva da Biosfera do Pantanal (UNESCO). As tufas calcárias são rochas porosas formadas pela precipitação do carbonato de cálcio em água doce e podem conter diversos tipos de fósseis. Apresentam-se sob a forma de cachoeiras, barragens e sedimentos lacustres que formam depósitos micríticos inconsolidados, descritos dentro da Formação Xaraiés. Os micritos são extensos e relativamente espessos em toda a região. Contudo, a maior parte das ocorrências está intemperizada, parcialmente erodida e distribuída em áreas limitadas. O presente estudo foca a caracterização paleontológica, granulométrica e geoquímica (elementos maiores, menores, traços e isótopos de carbono e oxigênio), através de levantamento de detalhe dos micritos da área da Mineração Calcário Xaraés, em Bonito (MS). As amostras foram obtidas por furo de trado, coleta de amostras superficiais e de bloco decimétrico orientado para estudo tafonômico, complementado com investigação de campo e amostragem de algumas áreas na Serra da Bodoquena, Pantanal e Corumbá. Os micritos da Mineração Calcário Xaraés, são depósitos lacustres e podem ser descritos em três eventos: 1: base afossilífera, oncólitos, argilominerais e dados isotópicos marcam um período de maior umidade; 2: ostracodes, algas caráceas e gastrópodes fósseis que colonizaram este estágio e a baixa variação dos dados isotópicos sugerem um período estável; 3: gastrópodes de água doce resistentes a ressecamento colonizaram esta etapa, em associação com os dados isotópicos sugerem processos alternados de evaporação e umidade. O topo da seção estudada é marcada por evaporação total da água do lago, morte em massa do gastrópode Biomphalaria e instalação do gastrópode Idiopyrgus. A ausência de estruturas sedimentares, orientação, seleção e fragmentação dos bioclastos e o empacotamento fraco a disperso e feições de alteração dos bioclastos por tempo de exposição na interface água-sedimento denotam condições estáticas do ambiente durante o processo final de deposição. Estas características também sugerem abastecimento do lago por águas subterrâneas, pois produzem menor taxa de alteração dos bioclastos e manutenção das condições químicas da água, como demonstrado pela homogeneidade dos dados geoquímicos. Outros depósitos estudados de micritos também apresentam resultados semelhantes. Há forte presença de indivíduos do gênero Biomphalaria e da Família Hydrobiidae nos depósitos. Dados de campo mostram os depósitos de tufas calcárias na região com extensão maior que as registradas, ocorrendo principalmente próximos aos leitos dos rios atuais, que os dissolvem nos períodos chuvosos. Os depósitos de tufas calcárias da Serra da Bodoquena, principalmente os micríticos, provavelmente foram formados nos últimos 10.000 anos, indicando período mais quente e seco que o atual. Os últimos 2.700 na região podem ser caracterizados por aumento da umidade, extinção dos depósitos micríticos e instalação dos depósitos de tufas de cachoeira e barragens.Bonito town and surrounding areas in Mato Grosso do Sul state are tourist attractions related with many quaternary carbonate deposits which form waterfalls, dams and render almost zero turbidity waters. That area is part of the National Park of Bodoquena Range and Pantanal Biosphere Reserve (UNESCO). Calcareous tufa are porous rocks formed by calcium carbonate laid down in freshwaters containg a great variety of fossils. They were presented in form of waterfalls, dams and lacustrine sediments, forming unconsolidated micritic deposits, being part of the Xaraés Formation. Micritic deposits are extensive and thick in whole area. Most of the deposits are weathered, partly eroded and distributed in restricted areas. The present study focuses on paleontological, granulometric, and geochemical (major, minor and trace elements, carbon and oxygen isotopes) data. The micritic deposits of Calcário Xaraés Mine in Bonito (MS) are detailed studied. Samples were obtained by auger drilling, also in outcrops area and one orientated centimetric indeformed block for taphomic study. The research was complemented with field study and sampling in the Bodoquena Range, Pantanal and Corumbá. Calcário Xaraés Mine micrites are lacustrine deposits. We described through three events: 1: their base does not contain fossils, but bears oncoids, clayminerals. Isotope data point to a wetter period, 2: ostracods, charophytes and gastropods fossils colonized this episode and homogeneity of isotope data suggest a stable event, 3: freshwater gastropods endured scarce water conditions so colonized the area. The isotope data then was varied suggesting alternated periods of evaporation and humidity. Total water lake evaporation resulted in the mass death of the Biomphalaria gastropod and consequent with diffusion of Idiopyrgus gastropod. Absence of sedimentary structures, bioclastic orientation, selection and fragmentation, weak to dispersal packing bioclast and bioclastic alteration features, are indications of long durantion in the water-sediment interface. These features suggest environmental static conditions during the final deposition. These features also suggest groundwater supplies to the lake, leading to less bioclastic alteration, and maintaing chemical water conditions, such as homogeneity of geochemical data. Other studied micritic deposits show almost the same results. There is strong presence of gastropod Biomphalaria and Hydrobiidae Family on these deposits. Field data show calcareous tufa deposits with an extension larger than the studied area, occurring mainly next to the rivers, which dissolve micritic in the rainy period. Bodoquena Range calcareous tufa deposits, mainly micritic sediments, probably were formed in the last 10.000 years, indicating a hotter and drier period than nowadays. The last 2.700 years in this region can be characterized by humidity increase, micritic deposits extinctions and installation of waterfalls and dams tufa depositions.
44
Manica, Raquel de Mattos. „Ostracodes eomiocênicos da perfuração 2-RSS-1, Bacia de Pelotas, Atlântico Sudoeste“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/133201.
Annotation:
Ostracodes são microcrustáceos que possuem uma carapaça bivalve constituída por quitina e carbonato de cálcio, que vivem em ambientes marinhos e não-marinhos. São amplamente utilizados em estudos paleoceanográficos e paleoclimáticos, sendo bons indicadores batimétricos, de salinidade e de temperatura. Nas bacias brasileiras, os ostracodes têm larga aplicação bioestratigráfica, especialmente em intervalos não marinhos cretáceos. Por sua vez, os ostracodes marinhos têm se destacado pelos bons resultados paleoceanográficos em bacias marginais, entre elas a Bacia de Pelotas. Este trabalho propõe novas espécies eomiocênicas da família Cytherellidae e do gênero Actinocythereis. A partir do estudo taxonômico discutem-se implicações paleozoogeográficas de eventos como o estabelecimento da Corrente Circumpolar Antártica e da Corrente das Malvinas, cuja ação influenciou a dispersão dos ostracodes ora registrados na Bacia de Pelotas. A partir da análise do intervalo testemunhado 1300 m-1318 m do poço offshore 2-RSS-1 coletado pela Petrobras na década de 1970, são registradas cinco espécies da família Cytherellidae, duas das quais aqui descritas, como segue: Inversacytherella atlantica sp. nov., Cytherella pelotensis sp. nov., Cytherella sp. 1, Cytherella sp. 2 e Grammcythella? sp. É também proposta Actinocythereis imbeensis sp. nov., a qual constitui a segunda espécie descrita para o gênero no Brasil. São ainda registradas, Krithe coimbrai, Krithe gnoma e Henryhowella kempfi, atribuídas em trabalhos anteriores ao estabelecimento de massas de água frias na costa Sul-Brasileira. As ocorrências de Inversacytherella e Grammcythella, por sua vez, constituem evidências para o intercâmbio faunístico entre a América e a Oceania decorrentes de mudanças hidrológicas no Oceano Austral ao longo do Neogeno. O Apêndice 1 apresenta a lista e a documentação fotográfica das demais espécies registradas.Ostracods are microcrustaceans with a bivalve carapace composed by chitin and calcium carbonate, living in both marine and non-marine environments. They are broadly used in paleoceanographic and paleoclimatic studies as indicators of bathymetry, salinity and temperature. In the Brazilian sedimentary basins the ostracodes have biostratigraphic importance, mainly in Cretaceous non-marine sections. The marine species, on the other hand, supply good paleoceanographyc data in marginal basins, including Pelotas Basin. In this work new Early Miocene species of the family Cytherellidae and the of genus Actinocythereis are proposed. Based on this taxonomic study some paleozoogeographic remarks are made, linking to the inception of the Antarctic Circumpolar Current and the Malvinas Current, to the dispersal of the ostracodes recorded in the Pelotas Basin. From the analysis of the core section 1300 m-1318 m of the offshore well 2-RSS-1 drilled by Petrobras in the 1970 decade, five species of cytherellids are recorded, two of them herein described, as follows: Inversacytherella atlantica sp. nov., Cytherella pelotensis sp. nov., Cytherella sp. 1, Cytherella sp. 2 and Grammcythella? sp. It is also proposed Actinocythereis imbeensis sp. nov., which constitutes the second species described for the genus in Brazil. Moreover, Krithe coimbrai, Krithe gnoma and Henryhowella kempfi, assigned in previous studies to the inception of cool water masses in Southern Brazilian coast, are recorded. The presence of Inversacytherella and Grammcythella, supply additional evidence for the faunal interchange between America and Oceania influenced by hydrological events in Southern Ocean along the Neogene. The Appendix 1 features the list and photographic documentation of other species registered.
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Egerquist, Eva. „Ordovician (Billingen and Volkhov stages) Brachiopod Faunas of the East Baltic“. Doctoral thesis, Uppsala University, Palaeontology group, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4303.
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Lower-Middle Ordovician (Arenig) successions in the East Baltic have been investigated for more than one hundred and fifty years. Nevertheless detailed sampling still yields new species and better knowledge of the environment in which these organisms lived. The successions are well suited for bed by bed sampling because of the lack of tectonic disturbance and because the sequences are well documented.
This study analyses collections of Billingen-Volkhov age mainly from the St. Petersburg region, but also from Estonia. A great deal of the material was obtained from the marly to clayey, soft sediment that intercalates the compact packstones and wackestones in the succession. Twenty-nine of these clay horizons were used for diversity estimates on the fauna through the succession. The most thoroughly investigated groups for this investigation were rhynchonelliformean brachiopods, conodonts and ostracodes. The results indicate that variances in diversity and abundance levels for these groups were not correlated, either to each other or to the small-scale sea level fluctuations that have been suggested for the region. However, diversity dynamics of brachiopods and ostracodes confirm the large-scale upward shallowing of the basin into the Upper Volkhov. Comparison with fossils from the limestones did not reveal any differences in faunal composition between the two preservation modes.
The detailed sampling, coupled with sampling of the recently described mud mounds that occur in several outcrops, yielded large numbers of specimens. This enabled revision of earlier poorly known rhynchonelliformean genera such as Ujukella Andreev, as well as better known genera such as Porambonites Pander. In total the examined faunas include 31 genera assigned to 53 species of rhynchonelliformean brachiopods. Of these Leoniorthis and Eoporambonites are defined as new genera, and the following new species are described: Neumania paucicostata, Ranorthis rotunda, Orthidium gambolovensis, Orthidium lavensis, Skenidioides minutus, Tetralobula peregrina, Idiostrophia prima and Idiostrophia tenuicostata.
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Bony, Guénaëlle. „Contraintes et potentialités naturelles de quelques sites portuaires antiques de Méditerranée et de mer Noire (Fréjus, Ampurias, Kition, Istanbul, Orgamé)“. Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM3039.
Annotation:
Il y a 7000 ans BP, la stabilisation du niveau marin a entraîné la formation de deltas. Ces zones deltaïques abritent des milieux aux degrés de protection différents favorables à une activité maritime. Cependant, ces espaces sont soumis à des contraintes naturelles : à l'échelle de la longue durée, l'alluvionnement des deltas entraîne la mobilité des littoraux et le colmatage des milieux portuaires ; à l'échelle de l'événement, les tempêtes, les tsunamis et la mobilité crustale entraînent la destruction, la submersion ou le soulèvement des zones portuaires. Ce travail porte sur l'étude des contraintes et des potentialités environnementales de cinq ports antiques répartis dans le monde Méditerranéen en marge de deltas. L'objectif est d'estimer le poids de ces contraintes sur les sociétés via une approche statistique. Pour quatre des sites d'études, l'alluvionnement est le forçage majeur. A Kition et Orgame, l'impact de l'alluvionnement est indirect. La fermeture des baies marines par l'édification de cordons littoraux crée des environnements lagunaires propices à l'installation de zones portuaires. En revanche, Fréjus et Ampurias sont soumis à un alluvionnement direct qui a rapidement colmaté les bassins. A partir de l'époque romaine et avec l'invention de la pouzzolane, des zones portuaires sont installées en milieu littoral ouvert, comme à Istanbul. Dans un contexte tectoniquement actif, les tsunamis constituent la contrainte majeure opérant sur le port byzantin de Théodose à Istanbul. Un dépôt grossier et chaotique, contenant du matériel marin et archéologique remanié, compose une partie de la séquence stratigraphique de colmatage du bassin et témoigne de ce forçageThe stabilization of sea level at 7000 years ago led to the formation of deltaic areas. These areas constituted sheltered environments particularly conducive to maritime activity. However, these areas were also subject to natural constraints for human occupation: at long timescales, high sediment supply to deltaic areas led to significative coastal changes and the infilling of harbour areas; at shorter timescales, high-energy events and crustal mobility led to the destruction, submersion and/or uplift of harbour areas. This work focuses on the study of environmental constraints and potentialities governing five ancient harbours, located on deltaic margins in the Mediterranean. The study aims to semi-qualitatively measure of the weight of these constraints on harbour cities, using statistical approach. High sediment supply is the major natural forcing. At Orgame and Kition, the closure of marine bays by coastal barriers led to the formation of lagoon environments conducive to the installation of harbour areas. Frejus and Ampurias were subject to direct siltation which quickly infilled the harbour basin. The invention of the pozzolan in Roman times means that harbours could be constructed in coastal areas open to the sea and away from river mouths, such as Istanbul harbour. In a tectonically active context, tsunamis are the major constraint acting in the Byzantine harbour of Theodosius in Istanbul. There, the stratigraphic sequence contains a coarse and chaotic deposit composed of reworked marine and archaeological material which demonstrates the societal impacts of such a natural and destructive forcing agent
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Ceolin, Daiane. „Ostracodes do cretáceo-paleógeno inferior da Bacia de Pelotas“. Universidade do Vale do Rio dos Sinos, 2010. http://www.repositorio.jesuita.org.br/handle/UNISINOS/3084.
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Submitted by Vanessa Nunes (vnunes@unisinos.br) on 2015-03-21T13:53:52Z
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CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico
O presente trabalho consiste no estudo taxonômico dos ostracodes marinhos da bacia de Pelotas e os respectivos aspectos paleoecológicos da assembléia no intervalo Cretáceo e Cretáceo – Paleógeno Inferior. Foram analisadas 479 amostras de calha, provenientes dos cinco poços 1-RSS-2, 1-RSS-3, 2-RSS-1, 1-SCS-3B e 1-SCS-2. A fauna registrada totalizou 98 espécimes, distribuídos em nove famílias, 21 gêneros, 34 espécies. Dois gêneros e duas espécies foram mantidos como táxons indeterminados. As espécies identificadas foram: Cytherella cf. C. araucana Bertels, 1974; Cytherelloidea spirocostata Bertels, 1973; Bairdoppilata triangulata Edwards, 1944; Actinocythereis indígena Bertels, 1969; Brachycythere gr. sapucariensis Krömmelbein, 1964; Wichmannella araucana Bertels, 1969 e Wichmannella meridionalis Bertels, 1969. Os gêneros mais diversificados foram Cytherella e Paracypris com sete e quatro espécies, respectivamente. O intervalo Turoniano foi o mais abundante, com a significativa presença dos gêneros Brachycythere e Cytherella . A família mais abundante foi a Trachyleberididae, com oito gêneros e 12 espécies, seguida da família Cytherellidae com dois gêneros e oito espécies. A passagem do limite Cretáceo – Paleógeno Inferior (K– Pg) na bacia de Pelotas foi marcada por uma mudança faunística com o desaparecimento dos gêneros, therelloidea, Argilloecia, Cythereis, Brachycythere, Pondoina e Rostrocytheridea, e o aparecimento de Neonesidea, Bairdoppilata, Ambocythere, Buntonia, Langiella?, Trachyleberis e Krithe . A associação dos ostracodes cretácicos na bacia de Pelotas sugere um ambiente marinho nerítico com águas quentes.
The taxonomic study of marine ostracods from Pelotas Basin and the respectives paleoecological assemblages aspects in the Cretaceous and Cretaceous – Lower Paleogene interval were studied. 479 cutting samples from wells 1-RSS-2, 1-RSS-3, 2-RSS-1, 1-SCS-3B e 1-SCS-2 were analized. 98 specimes belonging to 9 families, 21 genera and 34 species. 2 genera and 2 species were supported as undetermined taxon. The species identified were: Cytherella cf. C. araucana Bertels, 1974; Cytherelloidea spirocostata Bertels, 1973; Bairdoppilata triangulata Edwards, 1944; Actinocythereis indígena Bertels, 1969; Brachycythere gr. sapucariensis Krömmelbein, 1964; ichmannella araucana Bertels, 1969 and Wichmannella meridionalis Bertels, 1969. The most diversified genera were Cytherella and Paracypris with 7 and 4 species, respectively. The Turonian was the most ostracodes-rich interval with significant presence of the genera Brachycythere and Cytherella. The most abundant families were Trachyleberididae and Cyther ellidae with 2 genera and 8 species. The K – Pg boundary in the Pelotas basin is marked by a faunal change which disappearance the genera Cytherelloidea, Argilloecia, Cythereis, Brachycythere, Pondoina and Rostrocytheridea, and the first occurrence of Neonesidea, Bairdoppilata, Ambocythere Buntonia, Langiella?, Trachyleberis and Krithe. The Cretaceous ostracods association in Pelotas Basin sugest a neritic marin e environment with warm water temperatures.
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Toth, Emoke. „Changements paléoenvironnementaux dans la Parathéthys Centrale pendant le Samartien (Miocène moyen) : étude paléontologique de microfaunes et analyses géochimiques“. Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00843092.
Annotation:
Les changements paléoenvironnementaux se produisant pendant le Sarmatien dans la Paratéthys Centrale ont été reconstitués par l'étude des foraminifères (36 espèces) et des ostracodes (28 espèces) de deux forages, combinée à une analyse géochimique de leurs squelettes calcitiques, des coquilles aragonitiques de gastéropodes et des dents phosphatiques de rongeurs.La composition de la microfaune indique que la connexion entre la Paratéthys et la Méditerranée est interrompue ou réduite à la base du Sarmatien mais qu'un bras de mer persiste entre Paratéthys Centrale et Paratéthys Orientale jusqu'à la fin du Sarmatien. Le Sarmatien inférieur est caractérisé par des eaux saumâtres peu profondes (maximum 80 m), bien ventilées, des températures stables (~ 15°C), un riche couvert végétal (algues et/ou phanérogames) et des efflorescences phytoplanctoniques périodiques. Un événement transgressif y est observé (TST de 3ème ordre; TB 2.6 du cycle global). Les changements faunistiques qui se produisent à la limite entre Sarmatien inférieur et moyen sont expliqués par un évènement de type HST accompagné de conditions dysoxiques. A la fin du Sarmatien moyen, une baisse du niveau marin relatif d'environ 50 m se produit et des eaux tempérées chaudes, plus saumâtres (17-23‰) et bien ventilées se mettent en place. Après un court épisode régressif, une connexion est rétablie entre la Paratéthys et la Méditerranée au début du Sarmatien supérieur. Des eaux chaudes (15-21° C), bien ventilées, correspondant à des lagunes marines et des marécages avec de fortes variations de la salinité (15-43 ‰) s'installent alors avant un isolement ultime de la Paratéthys qui se produit à la fin du Sarmatien.
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Medeiros, Caio Gurgel de. „Ostracodes da Formação Solimões, Brasil : contribuição à bioestratigrafia do Neógeno da Amazônia“. reponame:Repositório Institucional da UnB, 2017. http://repositorio.unb.br/handle/10482/23710.
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Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, Programa de Pós-Graduação em Geologia, 2017.Submitted by Raquel Almeida (raquel.df13@gmail.com) on 2017-06-20T20:32:49Z No. of bitstreams: 1 2017_CaioGurgeldeMedeiros.pdf: 3878046 bytes, checksum: b71e584315979e5bdda2c93c79ee65eb (MD5)
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A Formação Solimões compreende uma sucessão siliciclástica intercalada por níveis linhíticos, carbonáticos e ferruginosos, distribuindo-se espacialmente pelo noroeste do Brasil, sudeste da Colômbia e nordeste do Peru. O intervalo sedimentar estudado restringe-se ao Mioceno, sendo atribuído a uma sedimentação fluvial à fluvio-lacustre. A análise do material recuperado da sondagem 1-AS-33-AM, proveniente do Município de Atalaia do Norte, Estado do Amazonas, permitiu a identificação de 12 espécies de ostracodes e um nível de ocorrência de foraminíferos: Cyprideis aff. amazonica, Cyprideis caraionae, Cyprideis aff. graciosa, Cyprideis inversa, Cyprideis machadoi, Cyprideis multiradiata, Cyprideis pebasae, Cyprideis simplex, Cyprideis sulcosigmoidalis, Alicenula olivencae, Rhadinocytherura amazonensis e Perissocytheridea sp. A. Apesar do endemismo das espécies analisadas, foi possível a proposição de um zoneamento bioestratigráfico local em que os 404,15 metros da sondagem foram compartimentados em três biozonas e uma subzona: Biozona Cyprideis caraionae, Biozona Cyprideis multiradiata e Biozona Cyprideis sulcosigmoidalis, além da Subzona Rhadinocytherura amazonensis, inserida na Biozona Cyprideis multiradiata, de posição intermediária. O nível de ocorrência de foraminíferos assinala um evento ecológico local em que se observa o desaparecimento de seis espécies de ostracodes e uma visível alteração no sistema deposicional. Além da análise bioestratigráfica, dados geofísicos e petrográficos foram utilizados na compreensão deste episódio paleoambiental, interpretado como uma mudança ambiental provocada por uma incursão marinha no sistema fluvio-lacustre que dominou a atual região da bacia hidrográfica do rio Amazonas durante Mioceno. A correlação cronoestratigráfica foi realizada com base nas propostas de zoneamento efetuadas com base no material coletado na região fronteiriça entre Brasil, Colômbia e Peru.
The Solimões Formation comprises a siliciclastic succession with intercalated lignite, carbonate and ferruginous levels, spatially distributed throughout the northwest region of Brazil, southeast of Colombia and northeast of Peru. The studied sedimentary interval is restricted to the Miocene, being attributed to fluvial to fluvio-lacustrine sedimentation. The analysis of the material recovered from the 1-AS-33-AM core-drilling, from the Municipality of Atalaia do Norte, State of Amazonas, allowed the identification of 12 species of ostracode and one level of occurrence of foraminifera: Cyprideis aff. amazonica, Cyprideis caraionae, Cyprideis aff. graciosa, Cyprideis inversa, Cyprideis machadoi, Cyprideis multiradiata, Cyprideis pebasae, Cyprideis simplex, Cyprideis sulcosigmoidalis, Alicenula olivencae, Rhadinocytherura amazonensis and Perissocytheridea sp. A. The endemism of the analyzed species allowed the proposal of a local biostratigraphic zonation, in which the 404.15 meters of the core-drilling were compartmentalized in three biozones and one subzone: Cyprideis caraionae biozone, Cyprideis multiradiata biozone and Cyprideis sulcosigmoidalis biozone, in addition to the Rhadinocytherura amazonensis subzone, inserted in the Cyprideis multiradiata biozone, the intermediated one. The level of occurrence of foraminifera indicates a local ecological event in which the disappearance of six species of ostracods and a visible change in the depositional system are observed. In addition to the stratigraphic analysis, geophysical and petrographic data were used to recognize this palaeoenvironmental episode, interpreted as an environmental shift caused by a marine incursion into the fluvio-lacustrine system that dominated the region of the Amazon river basin during Miocene. The chronostratigraphic correlation was performed based on the zoning proposals made based on the material collected in the border region between Brazil, Colombia and Peru.
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Ben, Rouina Soumaya. „Reconstitution des paléoenvironnements et des évènements extrêmes au cours du Quaternaire à l'oued El Akarit (Golfe de Gabès, Sud de la Tunisie)“. Thesis, Perpignan, 2016. http://www.theses.fr/2016PERP0036/document.
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Trois carottes de 5 à 6 m de profondeur ont été prélevées tout au long de l’oued El Akarit (Golfe de Gabès, Sud tunisien) : deux sur la rive Nord et une à l’embouchure. L’étude sédimentologique (granulométrie), minéralogique (minéraux argileux) et micropaléontologique (ostracodes, foraminifères et charophytes) et leur étude quantitative et qualitative ainsi que le calcul des indices de diversités de Shannon et d’équitabilité nous a permis de reconstituer l’évolution des paléo-environnements succédés depuis le Pléistocène dans la région El Akarit. La carotte à l’embouchure de l’oued El Akarit (carotte AK1), nous a permis de dater avec précision les dépôts étudiés et de reconstituer la chronologie des évènements ayant contrôlé la sédimentation. La phase pléistocène (>45000 ans B.P), milieu continental estuarien évoluant vers unevaste lagune très ouverte à la mer lors de la transgression marine pléistocène (MIS5e), par la suite l’installation d’un cordon sableux isole cette lagune de l’environnement marin. Les dépôts holocènes inférieurs et moyens sont absents dans l’embouchure de l’oued El Akarit à cause d’une émersion et non dépôt et/ou d’une érosion des dépôts. La phase Holocène supérieur (derniers 3000 ans B.P), se caractérise par la succession de trois épisodes d’évènements extrêmes (crues et tempêtes). A 1 et 2 km du rivage actuel (carotte AK2 et AK3 respectivement), les dépôts généralementcontinentaux montrent des intercalations des dépôts marins et des niveaux à galets enregistrant des évènements extrêmes. Les dépôts de ̴ 8000ans B.P de la poche à « Cardium » à 9 m d’altitude de la mer actuelle, montrent une influence marine (abondance des foraminifères planctoniques), il s’agit évidemment d’un évènement extrême exceptionnel qui provoquerait le transport des foraminifères planctoniques à l’intérieur de la lagune El AkaritThree cores varying from 5 to 6 m of depth were taken throughout in the El Akarit River (Gulf of Gabes, south of Tunisia): two on the left river bank and the last at the mouth. The study of the sedimentology (particle size), mineral (clay minerals) and micropaleontology (quantitative and qualitative study of ostracods, foraminifera, charophytes and the calculation of the Shannon / equitability diversity index) deposits content allowed us to reconstruct the paleoenvironments evolution since the Pleistocene in this region. The mouth core (AK1), permitted us to date precisely the studied deposits and reconstruct the events chronology controlling the sedimentation. The Pleistocene phase (> 45 000 years BP) shows a continental estuarine environment evolving toward a vast open lagoon during the Pleistocene marine transgression (MIS5e). Then, the formation of a sand bar isolates the lagoon from the marine environment. The lower and middle Holocene deposits are absent in the mouth deposits. This could be interpreted by the emersion of the zone or by the erosion of deposits. The late Holocene (last 3000 years B.P) phase is characterized by the succession of three extreme events (floods and storms) episodes. At 1 and 2 km from the current shoreline (AK2 and AK3 cores respectively), the continental deposits show an intercalation of marine deposits and pebble levels suggestive of an extreme events occurrence. The existence of the 8000 yr BP deposits "Cardium pocket” at 9 m of the current sea, show a marine influence (planktonic foraminifera abundance). It is apparently an exceptional event that would cause extreme transport of planktonic foraminifera inside the El Akarit lagoon