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Gulf
Kinds of Gulf Terms modified by Gulf Selected AbstractsA JÖKULHLAUP FROM A LAURENTIAN CAPTURED ICE SHELF TO THE GULF OF MEXICO COULD HAVE CAUSED THE BØLLING WARMINGGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2 2008ULF ERLINGSSON ABSTRACT. Since the rapid rate of global warming at the onset of the Bølling interstadial became evident, its cause has been under debate. It coincides closely in time with a strong global transgression called meltwater pulse 1a. One attempt at solution says that a meltwater pulse of Antarctic origin could cause an increase in North Atlantic Deep Water formation, and thus give rise to the Bølling interstadial. However, others have disputed that Antarctic meltwater would have that effect, and furthermore, the start of the Bølling interstadial is not even associated with an increase in North Atlantic Deep Water. A controversial hypothesis says that some Laurentian meltwater came from a jökulhlaup (sub-glacial outburst flood), but no study has yet shown unequivocally that sufficient amounts of water could be stored under the ice. Furthermore, according to all available data a melt-water pulse from the Laurentian ice would give rise to strong cooling, not warming. Nevertheless, meg-afloods appear instrumental in accumulating the Mississippi Fan, created entirely during the Quaternary period, and dramatic climate changes are characteristic of this period. This paper presents a hypothetical chain of events, building on the published literature and simple calculations, to investigate whether the order of magnitude is reasonable. The hypothesis is that a jökulhlaup from a Laurentian captured ice shelf flowed out through the Mississippi, boosted the Gulf Stream, reinvigorated the North Atlantic circulation, and as a result triggered the Bølling warm phase. [source] GEOCHEMICAL CHARACTERIZATION OF A BIODEGRADED CRUDE OIL, ASSRAN FIELD, CENTRAL GULF OF SUEZJOURNAL OF PETROLEUM GEOLOGY, Issue 4 2009A. H. Hegazi A crude oil sample from the Assran field in the Central Gulf of Suez (Egypt) was analysed geochemically and characterized in terms of a variety of source and maturity dependent biomarkers. Biodegradation was indicated by increasing concentration ratios of Pr/n-C17 and Ph/n-C18. However, biodegradation was only slight as GC-MS analyses of the saturate and aromatic fractions showed that hopanes, steranes, aromatic steroids and polycyclic aromatic compounds including sulphur heterocycles remained intact. The sterane and hopane distributions showed a predominance of C27 steranes, a low diasterane index, an abundance of gammacerane, a high homohopane index and an oleanane index < 0.2. The results indicate that the Assran-10 crude oil was derived from a marine carbonate source deposited in a highly reducing saline environment with a high bacterial contribution, consistent with the Upper Cretaceous Brown Limestone or Lower Eocene Thebes Formation containing Type IIS kerogen. Maturity parameters based on changes in the stereochemistry at chirality centres in hopane and sterane nuclei, such as C30,,/(,,+,,) and C31 22S/(22S+22R) hopanes and C29,,/(,,+,,) and C29 20S/(20S+20R) steranes, together with triaromatic sterane cracking ratios, indicate that the oil sample was marginally mature. The results also suggest that biodegradation is probably due to sulphate-reducing anaerobic bacteria. [source] THERMAL HISTORY RECONSTRUCTION IN THE SOROOSH AND NOWROOZ FIELDS, PERSIAN GULF, BASED ON APATITE FISSION TRACK ANALYSIS AND VITRINITE REFLECTANCE DATAJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2008A. Bashari The thermal history of the sedimentary successions at the Soroosh-17, Soroosh-02 and Nowrooz-16 wells in the northern Persian Gulf have been studied using apatite fission track analysis and vitrinite reflectance data. These data were used to identify and quantify episodes of heating and cooling which have affected the sections penetrated by these wells. This information was synthesised to provide a thermal history framework for the wells, within which the history of hydrocarbon generation, as well as regional structural development, can be understood. Preliminary hydrocarbon generation histories are presented for the Soroosh and Nowrooz oilfields and nearby areas. Modelling of hydrocarbon generation histories based on the AFTA- and VR-derived thermal histories, assuming a dominant Type III kerogen for possible Albian Kazhdumi Formation source rocks and a dominant Type II kerogen for possible Neocomian Fahliyan (Lower Ratawi) Formation source rock, suggest that local sourcing of oil from the Kazhdumi Formation is unlikely. The most likely source rock for oil in the Burgan Formation reservoir at Soroosh-17 and Nowrooz-16 is interpreted to be the Fahliyan Formation based on the available data. On the other hand, speculative modelling of the Hendijan-I well down-dip from the Nowrooz field does allow some oil to be generated from the Kazhdumi sequence at that location, and this might be available for migration to the Nowrooz field. [source] CYLINDRICAL AND CONICAL FOLD GEOMETRIES IN THE CANTARELL STRUCTURE, SOUTHERN GULF OF MEXICO: IMPLICATIONS FOR HYDROCARBON EXPLORATIONJOURNAL OF PETROLEUM GEOLOGY, Issue 3 2006J. J. Mandujano V. The NW-SE trending Cantarell structure in the Gulf of Campeche hosts the largest oilfield in Mexico. The oil occurs predominantly in latest Cretaceous , earliest Tertiary breccias with subsidiary reserves in Upper Jurassic (Oxfordian and Kimmeridgian) and Lower Cretaceous oolitic and partially dolomitized limestones, dolomites and shaly limestones. Cantarell has been interpreted both as a fold-and-thrust zone and as a dextral transpressional structure. Analysis of structure contours at 100m intervals, on the tops of the Tertiary breccia and the Kimmeridgian (Upper Jurassic) dolomite, indicates that the structure is an upright cylindrical fold with gently plunging conical terminations; there is also a conical portion in the central part of the structure. The axes of the central, NW and SE cones are subvertical. This geometry indicates that the two fold terminations and the central cone are aprons rather than points, with the NW and central cone axes intersecting the cylindrical fold axis at the point where the geometry switches from conical to cylindrical. The apical angle (i.e. the angle between the fold and cone axes) varies as follows: (i) in the NW cone, it is ,70° in the breccia and ,76° in the Kimmeridgian dolomite; (ii) in the central cone, it is ,77° in the breccia and ,73° in the Kimmeridgian dolomite; and (iii) in the SE cone, it is ,64° in the breccia and ,57° in the Kimmeridgian dolomite. This indicates that whereas the fold opens with depth in the NW cone, it tightens with depth in the central and SE cones. Assuming a parallel fold geometry, these apical angles indicate an increase in volume in the NW cone (i.e. larger hydrocarbon reservoirs), compared to the central and SE cones. Theoretical considerations indicate that the curvature increases dramatically towards the point of the cone. In the case of the Cantarell structure, the apices of the cones are located at the conical-cylindrical fold junctions, where the highest curvature may have resulted in a higher degree of fracturing. The coincidence of maximum curvature and the intersection of the conical and cylindrical fold axes in the fold culminations with porous and permeable reservoir rocks may have made these locations favourable for the accumulation of hydrocarbons. [source] SEISMIC FACIES ANALYSIS BASED ON 3D MULTI-ATTRIBUTE VOLUME CLASSIFICATION, DARIYAN FORMATION, SE PERSIAN GULFJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2006P. Farzadi Interpretation of recently acquired 3D seismic data from the adjacent Sirri C and D oilfields in the SE Persian Gulf indicates that a 3D interpretation of seismic facies is crucial to resolve the internal stratal geometries of the Aptian Dariyan Formation. This carbonate formation passes southward into the Shu'aiba Formation, a prolific reservoir rock of similar facies in the UAE. Lack of exposures and limited cored intervals have forced reliance on the seismic data for evidence of the depositional environment and the internal architecture of potential reservoir rocks. The progradational nature of the Dariyan Formation and the occurrence of carbonate build-ups within it make this stratal geometry complex. The complex internal heterogeneity of the build-ups and presence of seismic noise make mapping of the build-ups in 3D space using conventional seismic interpretation tools difficult, despite the availability of high-quality 3D seismic data covering the area. The high quality seismic and limited well data from this field is one of the few datasets of this kind presented in the literature. A procedure for the hierarchical multi-attribute analysis of seismic facies using Paradigm's Seis Facies software is used in this study to provide a 3D interpretation of the stratal patterns. Principal component analysis reduces the noise and redundant data by representing the main data variances as a few vector components in a transformed coordinate system. Cluster analysis is performed using those components which have the greatest contribution to the maximum spread of the data variability. Six seismic attribute volumes are used in this study and the result is a single 3D classified volume. Important new information obtained from within the Dariyan Formation gives new insights into its stratigraphic distribution and internal variability. This method of processing seismic data is a step towards exploring for subtle stratigraphic traps in the study area, and may help to identify exploration targets. [source] DISTRIBUTION OF SOURCE ROCKS AND MATURITY MODELLING IN THE NORTHERN CENOZOIC SONG HONG BASIN (GULF OF TONKIN), VIETNAMJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2005C. Andersen The northern offshore part of the Cenozoic Song Hong Basin in the Gulf of Tonkin (East Vietnam Sea) is at an early stage of exploration with only a few wells drilled. Oil to source rock correlation indicates that coals are responsible for the sub-commercial oil and gas accumulations in sandstones in two of the four wells which have been drilled on faulted anticlines and flower structures. The wells are located in a narrow, structurally inverted zone with a thick predominantly deltaic Miocene succession between the Song Chay and Vinh Ninh/Song Lo fault zones. These faults are splays belonging to the offshore extension of the Red River Fault Zone. Access to a database of 3,500 km of 2D seismic data has allowed a detailed and consistent break-down of the geological record of the northern part of the basin into chronostratigraphic events which were used as inputs to model the hydrocarbon generation history. In addition, seismic facies mapping, using the internal reflection characteristics of selected seismic sequences, has been applied to predict the lateral distribution of source rock intervals. The results based on Yükler ID basin modelling are presented as profiles and maturity maps. The robustness of the results are analysed by testing different heat flow scenarios and by transfer of the model concept to IES Petromod software to obtain a more acceptable temperature history reconstruction using the Easy%R0 algorithm. Miocene coals in the wells located in the inverted zone between the fault splays are present in separate intervals. Seismic facies analysis suggests that the upper interval is of limited areal extent. The lower interval, of more widespread occurrence, is presently in the oil and condensate generating zones in deep synclines between inversion ridges. The Yükler modelling indicates, however, that the coaly source rock interval entered the main window prior to formation of traps as a result of Late Miocene inversion. Lacustrine mudstones, similar to the highly oil-prone Oligocene mudstones and coals which are exposed in the Dong Ho area at the northern margin of the Song Hong Basin and on Bach Long Vi Island in Gulf of Tonkin, are interpreted to be preserved in a system of undrilled NW,SE Paleogene half-grabens NE of the Song Lo Fault Zone. This is based on the presence of intervals with distinct, continuous, high reflection seismic amplitudes. Considerable overlap exists between the shale-prone seismic facies and the modelled extent of the present-day oil and condensate generating zones, suggesting that active source kitchens also exist in this part of the basin. Recently reported oil in a well located onshore (BIO-STB-IX) at the margin of the basin, which is sourced mainly from "Dong Ho type" lacustrine mudstones supports the presence of an additional Paleogene sourced petroleum system. [source] GEOLOGICAL INTERPRETATION OF WELL TEST ANALYSIS: A CASE STUDY FROM A FLUVIAL RESERVOIR IN THE GULF OF THAILANDJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2003S. Y. Zheng One problem with the inversion of transient well test data is that it can yield a non-unique solution. The uncertainty resulting from this type of approach can only be resolved by considering information from another source such as geology. Geological information will help to define the interpretation model which will ensure the correct analysis of the well test data. The results of well test analyses are of little value to reservoir characterisation and modelling unless they can be explained from a geological point of view. This last step is what we refer to here as geological interpretation. Other sources of information which can help with well test analyses come from seismic surveys and petrophysics. Modern well test interpretation therefore consists of two major steps: analysis of the well test data; and interpretation of the results. In detail, this should include the following: 1definition of an interpretation model , this requires the integration of geological, seismic and petrophysical data with transient pressure data 2analysis of the well test data based on the interpretation model defined 3geological interpretation of the results, which is necessary in order to explain or give meaning to the results. In this paper, we present a case study from a fluvial gas reservoir in the Gulf of Thailand which demonstrates these procedures. In the context of a defined geological environment, a transient pressure test has been fully analysed. Newly-developed software based on the finite element method has been used to forward model the test scenarios. This allowed the results of seismic and petrophysical analyses to be integrated into the well test model. This case study illustrates the integrated use of geological, petrophysical, well test and seismic attribute data in defining a reservoir model which respects both the reservoir geometry at some distance from the well location and also the reservoir's heterogeneity. We focus on a particular well in the Pattani Basin at which conventional well test analyses have been conducted. By considering the results of these analyses, forward modelling was carried out in which the drainage area was "cut" out of the structural map defined by seismic interpretation; also, the formation's internal heterogeneity was modelled according to well logs and petrophysical analyses. Finally, analytical and simulation results were compared with the transient pressure data. We conclude that the integration of geological, seismic, petrophysical and well test data greatly reduced uncertainties in well test interpretation. The consistency of the results and the fact that they satisfied all the relevant disciplines meant that much more confidence could be given to their interpretation. [source] PHYLOGENETIC AND BIOGEOGRAPHIC AFFINITIES OF THE HALYMENIALES AND RHODYMENIALES (RHODOPHYTA) FROM THE GULF OF MEXICOJOURNAL OF PHYCOLOGY, Issue 2000B. Gavio Generic and species concepts within the red algal assemblages Halymeniales and Rhodymeniales are discussed for taxa inhabiting the western Gulf of Mexico. Two principal biogeographic assemblages occur: an off-shore deep-water group (including Coelarthrum cliftonii, Halymenia spp., Botryocladia spp., Gloiocladia) representing remnants of a Tethyan distribution, and a near-shore intertidal flora (comprising Rhodymenia, Grateloupia and Prionitis) which instead reveals biogeographic affinities with the Carolinian Province. These two distinct marine floras will be contrasted phylogenetically based on DNA sequence analysis inferred from chloroplast-encoded rbcL. The generic descriptions of Grateloupia and Prionitis are in need of taxonomic revision based on a survey of species from Caribbean and Pacific Mexico. [source] GLOBAL SYSTEMATIC AND PHYLOGENETIC ANALYSIS OF SARGASSUM IN THE GULF OF MEXICO, CARIBBEAN AND PACIFIC BASINJOURNAL OF PHYCOLOGY, Issue 2000N. Phillips Sargassum is one of the most species-rich genera in the brown algae with over 400 described species worldwide. The bulk of these species occurs in Pacific-Indian ocean waters with only a small portion found on the Atlantic side of the Isthmus of Panama. Sargassum also has one of the most subdivided and complex taxonomic systems used within the algae. Systematic distinctions within the genus are further complicated by high rates of phenotypic variability in several key morphological characters. Molecular analyses in such systems should allow testing of systematic concepts while providing insights into speciation and evolutionary patterns. Global molecular phylogenetic analyses using both conserved and variable regions of the Rubisco operon (rbcL and rbcL-IGS-rbcS) were performed with species from the Gulf of Mexico, Caribbean, and Pacific basin. Results confirm earlier analyses based on rbcL-IGS- rbcS from Pacific species at the subgeneric and sectional level while providing additional insights into the systematics and phylogenetics on a global scale. For example, species east of the Isthmus of Panama form a distinct well-resolved clade within the tropical subgenus. This result in sharp contrast to traditional systematic treatments but provides a window into the evolutionary history of this genus in the Pacific and Atlantic Ocean basins and a possible means to time speciation events. [source] SEASONAL OCCURRENCE OF SPERM WHALE (PHYSETER MACROCEPHALUS) SOUNDS IN THE GULF OF ALASKA, 1999,2001MARINE MAMMAL SCIENCE, Issue 1 2004David K. Mellinger Abstract An acoustic survey for sperm whales was conducted in the Gulf of Alaska. Six autonomous hydrophones continuously recorded sound signals below 500 Hz from October 1999 to May 2001. After recovery, recordings were processed using an automatic process to detect usual clicks of sperm whales. The detection algorithm equalized background noise, summed the data in a frequency band, and then used autocorrelation to detect the whales' highly regular clicks. Detections were checked manually, revealing that 98% of detections did contain clicks. Results indicate that sperm whales are present in the Gulf of Alaska year-round; this result extends what is known from whaling data, which were gathered principally in summer. Sperm whales were more common in summer than winter by a factor of roughly two, and occurred less often at the westernmost site surveyed (52°N, 157°W) than elsewhere in the Gulf. This is the first study of sperm whales based exclusively on remote acoustic sensing. This methodology is feasible because sperm whale clicks extend to frequencies (,100 Hz) low enough to be recorded by low-sample-rate instruments that operate continuously, and because the detection algorithm has a low false-detection rate. The methodology may be replicated to facilitate comparisons between different time periods and geographic regions. [source] ROYALTY INCENTIVES AND GULF OF MEXICO OIL PRODUCTIONNATURAL RESOURCE MODELING, Issue 3 2007MITCH KUNCE ABSTRACT. This paper employs field-specific estimates of Pindyck's (1978) widely cited model of natural resource supply to simulate effects of changes in federal royalty rates on the timing of exploration and output by firms in the deepwater Gulf of Mexico oil industry. Results suggest that deepwater Gulf oil production is highly inelastic with respect to changes in royalty rates. Royalty rate decreases are shown to increase early period exploration effort, result in little change in reserve additions and future production. Policy implications of this study suggest that public officials should be wary of arguments that large increases in deepwater Gulf oil field activity can be obtained from reductions in federal royalty rates-particularly reductions in the early years of oil field development. [source] Towards an integrated GIS-based coastal forecast workflowCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 14 2008Gabrielle Allen Abstract The SURA Coastal Ocean Observing and Prediction (SCOOP) program is using geographical information system (GIS) technologies to visualize and integrate distributed data sources from across the United States and Canada. Hydrodynamic models are run at different sites on a developing multi-institutional computational Grid. Some of these predictive simulations of storm surge and wind waves are triggered by tropical and subtropical cyclones in the Atlantic and the Gulf of Mexico. Model predictions and observational data need to be merged and visualized in a geospatial context for a variety of analyses and applications. A data archive at LSU aggregates the model outputs from multiple sources, and a data-driven workflow triggers remotely performed conversion of a subset of model predictions to georeferenced data sets, which are then delivered to a Web Map Service located at Texas A&M University. Other nodes in the distributed system aggregate the observational data. This paper describes the use of GIS within the SCOOP program for the 2005 hurricane season, along with details of the data-driven distributed dataflow and workflow, which results in geospatial products. We also focus on future plans related to the complimentary use of GIS and Grid technologies in the SCOOP program, through which we hope to provide a wider range of tools that can enhance the tools and capabilities of earth science research and hazard planning. Copyright © 2008 John Wiley & Sons, Ltd. [source] Black Gold, White Crude: An Essay on American Exceptionalism, Hierarchy, and Hegemony in the GulfDIPLOMATIC HISTORY, Issue 2 2002Robert Vitalis First page of article [source] Seismic microzonation of the greater Bangkok area using microtremor observationsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2004Rabin Tuladhar Abstract Bangkok, the capital city of Thailand, is located at a remote distance from seismic sources. However, it has a substantial risk from these distant earthquakes due to the ability of the underlying soft clay to amplify ground motions. It is therefore imperative to conduct a detailed seismic hazard assessment of the area. Seismic microzonation of big cities, like Bangkok, provides a basis for site-specific hazard analysis, which can assist in systematic earthquake mitigation programs. In this study, a seismic microzonation map for the greater Bangkok area is constructed using microtremor observations. Microtremor observations were carried out at more than 150 sites in the greater Bangkok area. The predominant periods of the ground were determined from the horizontal-to-vertical (H/V) spectral ratio technique. A microzonation map was then developed for the greater Bangkok area based on the observations. Moreover, the transfer functions were calculated for the soil profile at eight sites, using the computer program SHAKE91, to validate the results from the microtremor analysis. The areas near the Gulf of Thailand, underlaid by a thick soft clay layer, were found to have long natural periods ranging from 0.8s to 1.2s. However, the areas outside the lower central plain have shorter predominant periods of less than 0.4s. The study shows that there is a great possibility of long-period ground vibration in Bangkok, especially in the areas near the Gulf of Thailand. This may have severe effects on long-period structures, such as high-rise buildings and long-span bridges. Copyright © 2003 John Wiley & Sons, Ltd. [source] Nocturnal migration of dragonflies over the Bohai Sea in northern ChinaECOLOGICAL ENTOMOLOGY, Issue 5 2006HONG-QIANG FENG Abstract 1.,A sudden increase and subsequent sharp decrease of catches of dragonflies in a searchlight trap, with Pantala flavescens Fabricius (Odonata: Libellulidae) predominating, observed at Beihuang Island in the centre of the Bohai Gulf, in 2003 and 2004, indicated a seasonal migration of these insects over the sea during the night in China. The movements were associated with the onset of fog. 2.,Simultaneous radar observations indicated that the nocturnally migrating dragonflies generally flew at altitudes of up to 1000 m above sea level, with high density concentrations at about 200,300 or 500 m; these concentrations were coincident with the temperature inversion. 3.,During early summer, the dragonflies oriented in a downwind direction, so that the displacement direction varied between different altitudes. In contrast, during late summer, the dragonflies were able to compensate for wind drift, even headwind drift, so as to orient south-westward no matter how the wind changed, and thus the displacement direction was towards the south-west. 4.,The duration of flight, estimated from the variation of area density derived from radar data and hourly catches in the searchlight trap through the night, was about 9,10 h. The displacement speed detected using radar was ,5,11 m s,1. Therefore, the dragonflies might migrate 150,400 km in a single flight. 5.,The dragonflies were thought to originate in Jiangsu province and they migrated into north-east China to exploit the temporary environment of paddy fields in early summer. Their offspring probably migrated back south during late summer and autumn. [source] Habitat use of age 0 Alabama shad in the Pascagoula River drainage, USAECOLOGY OF FRESHWATER FISH, Issue 1 2010P. F. Mickle Mickle PF, Schaefer JF, Adams SB, Kreiser BR. Habitat use of age 0 Alabama shad in the Pascagoula River drainage, USA. Ecology of Freshwater Fish 2010: 19: 107,115. © 2009 John Wiley & Sons A/S Abstract,, Alabama shad (Alosa alabamae) is an anadromous species that spawns in Gulf of Mexico drainages and is a NOAA Fisheries Species of Concern. Habitat degradation and barriers to migration are considered contributing factors to range contraction that has left just the Pascagoula River drainage population in Mississippi. We studied juvenile life history and autecology in three rivers within the drainage. We collected fish, habitat and physicochemical data in three habitat types (sandbar, open channel and bank) from June to October 2004,2006. Sandbar habitat was favoured by smaller individuals early in the year. Catch per unit effort (CPUE) decreased through the summer as larger fish began occupying bank and open channel habitat. The most parsimonious model of abundance included year and river variables, while patterns of presence and absence were best explained by river, habitat type and physiochemical variables. While all three rivers in the drainage contained Alabama shad, fish were less abundant and had lower condition values in the Chickasawhay River. Earlier work suggested the Alabama shad may gradually move downstream towards the Gulf of Mexico in their first year. However, we found no evidence of this and captured large fish high in the drainage late in the year. [source] Lost zooplanktivorous cichlid from Lake Victoria reappears with a new tradeECOLOGY OF FRESHWATER FISH, Issue 4 2003E. F. B. Katunzi Abstract,,, The zooplanktivorous cichlid Haplochromis pyrrhocephalus, which was one of the most common haplochromine species in the Mwanza Gulf of Lake Victoria, had almost completely disappeared after the Nile perch upsurge in the 1980s. In the second half of the 1990s, this species suddenly reappeared in the strongly changed ecosystem. Gut content investigation revealed a change in diet. Currently, H. pyrrhocephalus eats large prey more frequently than in the past. These large prey comprise fish, shrimps and molluscs. The latter two were never encountered in specimens from the past. Particularly feeding on molluscs was unexpected, as it had been suggested that, because of anatomical constraints, molluscivory and zooplanktivory are incompatible in cichlid fish. Our observations provide a new example of the extreme versatility in feeding behaviour in haplochromine cichlids. [source] Descriptions of Immature Stages of Psammodius porcicollis, with Some Contribution on P. basalis (Col., Aphodiidae) from FranceENTOMOLOGICAL RESEARCH, Issue 2 2003Jin Ill KIM ABSTRACT Immature stages of Psammodius porcicollis (Illiger, 1803) from the seacoast of the Gulf of Lion, France are described, and some characteristics of larva of P. basalis are added. [source] Culture-independent evidence for the persistent presence and genetic diversity of microcystin-producing Anabaena (Cyanobacteria) in the Gulf of FinlandENVIRONMENTAL MICROBIOLOGY, Issue 4 2009David P. Fewer Summary The late summer mass occurrences of cyanobacteria in the Baltic Sea are among the largest in the world. These blooms are rarely monotypic and are often composed of a diverse assemblage of cyanobacteria. The toxicity of the blooms is attributed to Nodularia spumigena through the production of the hepatotoxic nodularin. However, the microcystin hepatotoxins have also been reported from the Baltic Sea on a number of occasions. Recent evidence links microcystin production in the Gulf of Finland directly to the genus Anabaena. Here we developed a denaturing gradient gel electrophoresis (DGGE) method based on the mcyE microcystin synthetase gene and ndaF nodularin synthetase gene that allows the culture-independent discrimination of microcystin- and nodularin-producing cyanobacteria directly from environmental samples. We PCR-amplified microcystin and nodularin synthetase genes from environmental samples taken from the Gulf of Finland and separated them on a denaturing gradient gel using optimized conditions. Sequence analyses demonstrate that uncultured microcystin-producing Anabaena strains are genetically more diverse than previously demonstrated from cultured strains. Furthermore, our data show that microcystin-producing Anabaena are widespread in the open Gulf of Finland. Non-parametric statistical analysis suggested that salinity plays an important role in defining the distribution of microcystin-producing Anabaena. Our results indicate that microcystin-producing blooms are a persistent phenomenon in the Gulf of Finland. [source] On the relationship between methane production and oxidation by anaerobic methanotrophic communities from cold seeps of the Gulf of MexicoENVIRONMENTAL MICROBIOLOGY, Issue 5 2008Beth! Orcutt Summary The anaerobic oxidation of methane (AOM) in the marine subsurface is a significant sink for methane in the environment, yet our understanding of its regulation and dynamics is still incomplete. Relatively few groups of microorganisms consume methane in subsurface environments , namely the anaerobic methanotrophic archaea (ANME clades 1, 2 and 3), which are phylogenetically related to methanogenic archaea. Anaerobic oxidation of methane presumably proceeds via a ,reversed' methanogenic pathway. The ANME are generally associated with sulfate-reducing bacteria (SRB) and sulfate is the only documented final electron acceptor for AOM in marine sediments. Our comparative study explored the coupling of AOM with sulfate reduction (SR) and methane generation (MOG) in microbial communities from Gulf of Mexico cold seep sediments that were naturally enriched with methane and other hydrocarbons. These sediments harbour a variety of ANME clades and SRB. Following enrichment under an atmosphere of methane, AOM fuelled 50,100% of SR, even in sediment slurries containing petroleum-associated hydrocarbons and organic matter. In the presence of methane and sulfate, the investigated microbial communities produce methane at a small fraction (,10%) of the AOM rate. Anaerobic oxidation of methane, MOG and SR rates decreased significantly with decreasing concentration of methane, and in the presence of the SR inhibitor molybdate, but reacted differently to the MOG inhibitor 2-bromoethanesulfonate (BES). The addition of acetate, a possible breakdown product of petroleum in situ and a potential intermediate in AOM/SR syntrophy, did not suppress AOM activity; rather acetate stimulated microbial activity in oily sediment slurries. [source] Polysaccharide hydrolysis in aggregates and free enzyme activity in aggregate-free seawater from the north-eastern Gulf of MexicoENVIRONMENTAL MICROBIOLOGY, Issue 2 2008Kai Ziervogel Summary Marine snow aggregates represent hotspots of carbon remineralization in the ocean. Various aspects of bacterial dynamics have been investigated on marine snow. To date, extracellular enzymatic activities in aggregates have been measured using small substrate proxies that do not adequately reflect the complexity of biomacromolecules such as polysaccharides, proteins and lipids. To address this issue, we used six structurally distinct, fluorescently labelled polysaccharides to measure enzymatic hydrolysis on aggregates formed with a roller table and in aggregate-free (ambient) seawater from two near-coast sites, north-eastern Gulf of Mexico. A single polysaccharide was incubated in aggregates and ambient seawater. Changes in polysaccharide molecular weight were monitored over time to measure the course of enzymatic hydrolysis. All six polysaccharides were hydrolysed in aggregates, indicating a broad range of enzyme activities in aggregate-associated bacteria. Four substrates were also hydrolysed in ambient waters. Epifluorescence microscopy revealed that nearly all of the bacteria present in original waters were incorporated into aggregates. Therefore hydrolytic activities in ambient waters were presumably due to enzymes spatially disconnected from cells and aggregates. Our results show substantial enzymatic activity in cell/aggregate-free seawater, suggesting a significant role of free enzymes in hydrolytic activity in waters from the north-eastern Gulf of Mexico. [source] Prokaryotic diversity and metabolically active microbial populations in sediments from an active mud volcano in the Gulf of MexicoENVIRONMENTAL MICROBIOLOGY, Issue 10 2006Robert J. Martinez Summary In this study, ribosomes and genomic DNA were extracted from three sediment depths (0,2, 6,8 and 10,12 cm) to determine the vertical changes in the microbial community composition and identify metabolically active microbial populations in sediments obtained from an active seafloor mud volcano site in the northern Gulf of Mexico. Domain-specific Bacteria and Archaea 16S polymerase chain reaction primers were used to amplify 16S rDNA gene sequences from extracted DNA. Complementary 16S ribosomal DNA (crDNA) was obtained from rRNA extracted from each sediment depth that had been subjected to reverse transcription polymerase chain reaction amplification. Twelve different 16S clone libraries, representing the three sediment depths, were constructed and a total of 154 rDNA (DNA-derived) and 142 crDNA (RNA-derived) Bacteria clones and 134 rDNA and 146 crDNA Archaea clones obtained. Analyses of the 576 clones revealed distinct differences in the composition and patterns of metabolically active microbial phylotypes relative to sediment depth. For example, ,- Proteobacteria rDNA clones dominated the 0,2 cm clone library whereas ,-Proteobacteria dominated the 0,2 cm crDNA library suggesting , to be among the most active in situ populations detected at 0,2 cm. Some microbial lineages, although detected at a frequency as high as 9% or greater in the total DNA library (i.e. Actinobacteria, ,- Proteobacteria), were markedly absent from the RNA-derived libraries suggesting a lack of in situ activity at any depth in the mud volcano sediments. This study is one of the first to report the composition of the microbial assemblages and physiologically active members of archaeal and bacterial populations extant in a Gulf of Mexico submarine mud volcano. [source] Inventory of shipping emissions in Izmit Gulf, TurkeyENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2010Alper Kiliç Abstract Ships are significant emissions sources in transportation sector. The environmental effects of shipping emissions become more serious because of insufficient international rules and inspections. Especially in inland waters, canals, straits, gulfs, and port areas emissions effects on environment and health are more important. Izmit Gulf is the major industrial, transport, and inland water region which is affected from shipping emissions with 37 ports and industrial plants. In this study, NOx, SO2, CO2, HC, and PM emission amounts from 11,645 ships called to Izmit Gulf in 2005. These emissions are classified according to ships operation modes and ship types. Annual shipping emissions are estimated as 5,356 t yr,1 for NOx, 4,305 t yr,1 for SO2, 254,261 t yr,1 for CO2, 232 t yr,1 for HC and 487 t yr,1 for PM. To determine the most probably effected regions in the gulf, the spatial distribution of NOx emissions within the Gulf region has been prepared in 1 × 1 Nm2 (Nautical miles) grid cells based on ship movement data along the various routes. Ships in Izmit Gulf contribute to urban pollution with sulfur dioxide significantly. © 2009 American Institute of Chemical Engineers Environ Prog, 2010 [source] Detection of nodularin in flounders and cod from the Baltic SeaENVIRONMENTAL TOXICOLOGY, Issue 2 2001Vesa Sipiä Abstract The brackish water cyanobacterium Nodularia spumigena regularly forms waterblooms in the Baltic Sea. Many N. spumigena strains can produce nodularin, a hepatotoxic penta-peptide, which has caused several animal poisonings in the Baltic Sea area. To improve our understanding of nodularin bioaccumulation in aquatic organisms this study measured nodularin in flounder and cod caught from the Baltic Sea. Flounders were collected from the western Gulf of Finland in July 1996, September 1997, and September 1998, and from the Gulf of Bothnia in August 1997 and September 1998. Flounders were also collected from the coastal areas of Sweden in the Baltic Proper during September 1998. Cod were caught from the southern Baltic Sea in August 1998. Livers and muscles of the 1997 fish were isolated, extracted, and analysed for nodularin using high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) and protein phosphatase 1 (PP1) inhibition assay. Approximately 30,70 ng of nodularin/g dry weight (maximum value 140 ng/g) were found in the liver tissue samples by ELISA and PP1 inhibition. These concentrations were below the detection limit of HPLC. PP1 assay showed inhibition also in muscle samples, but this may due to other compounds present in the muscle extracts rather than NODLN or due to matrix interference. The recovery of nodularin from liver tissue with ELISA and PP1 assays was about 30%. Nodularin concentrations in samples are not corrected for recovery. Although the concentrations of nodularin found in this study are low further studies of nodularin are needed to assess possible bioaccumulation in brackish water food webs. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 121,126, 2001 [source] Sediment quality in near coastal waters of the Gulf of Mexico: Influence of Hurricane Katrina,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010John M. Macauley Abstract The results of the present study represent a synoptic analysis of sediment quality in coastal waters of Lake Pontchartrain and Mississippi Sound two months after the landfall of Hurricane Katrina. Posthurricane conditions were compared to prehurricane (2000,2004) conditions, for sediment quality data. There were no exceedances of effects range median (ERM) sediment quality guideline values for chemical contaminants in any of the sediment samples collected from the Lake Pontchartrain or the Mississippi Sound study areas following the hurricane. Lower threshold effects range low (ERL) values were exceeded for As, Cd, and Ni at several stations in both survey areas, similar to levels of contamination observed prior to the hurricane. The comparison of sediment quality indicators before and after the hurricane suggests considerable stability of these systems with respect to short-term ecological impacts. Although other studies have shown storm-related changes could be detected (e.g., effects on benthic communities associated with shifts in salinity), there were no indications of widespread sediment contamination. Environ. Toxicol. Chem. 2010;29:1403,1408. © 2010 SETAC [source] Posidonia oceanica as a biomonitor of trace elements in the gulf of naples: Temporal trends by lepidochronology,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2004Stefania Ancora Abstract Levels of Hg, Cd, Pb, Cu, Zn, Fe, and Mn were assessed by using Posidonia oceanica as a bioindicator in the Gulf of Naples (southern Italy). Lepidochronology, which enables retroactive dating of scales and rhizomes of this seagrass, was combined with atomic spectrometry to assess temporal trends of trace elements in dated scales and rhizomes over a 10-year period. Lepidochronology occasionally has been used to monitor Hg in dated scales, but never has been used to determine concentrations of other trace elements in dated rhizomes. Data were compared between various structural parts of seagrass and between sampling sites. Concentrations of some elements found in dated scales or rhizomes showed a similar trend in most of the sites; increasing for Hg and Cu and decreasing for Pb, Fe, and Zn. Contaminant levels indicated by seagrass meadows varied from metal to metal. Concentrations of Hg, Cd, and Pb fell within the ranges measured in other areas considered to have low levels of heavy metal pollution, whereas Cu, Mn, and Zn had higher concentrations only in some years. However, on the basis of other studies, none of the sampling sites are considered to have high contamination levels. [source] Speciation of heavy metals in recent sediments of three coastal ecosystems in the Gulf of Cadiz, Southwest Iberian PeninsulaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2003Veronica Sáenz Abstract A five-step sequential extraction technique was used to determine the partitioning of Cr, Mn, Fe, Cu, Zn, Cd, and Pb among the operative sedimentary phases (exchangeable ions, carbonates, manganese and iron oxides, sulfides and organic matter, and residual minerals) in coastal sediment from three locations in the southwest Iberian Peninsula. Two sites are located close to industrial areas, the salt marshes of the Odiel River and Bay of Cádiz, and one in a nonindustrial area, the Barbate River salt marshes. The Odiel River salt marshes also receive the drainage from mining activities in the Huelva region. In the sediments from the Bay of Cádiz and Barbate River salt marshes, Cr, Cu, Fe, and Zn were extracted from the residual fraction at percentages higher than 60%. In the sediments from the Odiel River salt marshes, concentrations of all the metals, except Cu, zn, and cd, exceeded 60% in the residual fraction as well. In the sediments from the Bay of Cádiz and Barbate River salt marshes, the main bioavailable metals were Mn and Cd; in those from the Odiel River salt marshes, the main bioavailable metals were Zn and Cd, respectively. The environmental risk was determined by employing the environmental risk factor (ERF), defined as ERF = (CSQV , Ci/CSQV), where Ci is the heavy metal concentration in the first four fractions and CSQV is concentration sediment quality value (the highest concentration with no associated biological effect). Our results showed that the sediments from the Cádiz Bay and Barbate River salt marshes do not constitute any environmental risk under the current natural conditions. In contrast, in the Odiel River salt marshes, Cu, Zn, and Pb yielded ERFs of less than zero at several sampling stations and, consequently, pose a potential threat for the organisms in the area. This is a consequence of the high levels of metals in the area derived from the mining activity (pyrite) and industrial activities and the association of these heavy metals with more labile fractions of the sediments. [source] Quality of Life of People with Epilepsy in Iran, the Gulf, and Near EastEPILEPSIA, Issue 1 2005Gus A. Baker Summary:,Purpose: To study the impact of epilepsy and its treatment on the quality of life of people living in Iran and in countries in the Gulf and Near East. Methods: Clinical, demographic, and psychosocial details were collected through the use of a self-completed questionnaire distributed to patients attending hospital outpatient clinics. Results: Data were collected from 3,889 people with epilepsy from 10 countries. More than 40% of all respondents had frequent seizures, and reported levels of side effects from medication were high, the most commonly reported being nervousness, headaches, and tiredness. A significant number of respondents reported changing their medications because of side effects or poor seizure control. Respondents reported that epilepsy and its treatment had a significant impact on a number of different aspects of their daily lives. A significant number of respondents felt stigmatized by their epilepsy. Reported health status was reduced when compared with that of people without epilepsy, particularly for physical and social functioning and energy and vitality, as assessed by using a generic health status measure, the SF-36. Conclusions: This is the largest study to date documenting the impact of epilepsy and its treatment in Iran, the Gulf, and Near East regions. Differences were found between the quality-of-life profiles of respondents in this study and those who participated in an earlier parallel study in Europe. [source] VICARIANCE AND DISPERSAL ACROSS BAJA CALIFORNIA IN DISJUNCT MARINE FISH POPULATIONSEVOLUTION, Issue 7 2003Giacomo Bernardi Abstract., Population disjunctions, as a first step toward complete allopatry, present an interesting situation to study incipient speciation. The geological formation of the Baja California Peninsula currently divides 19 species of fish into disjunct populations that are found on its Pacific Coast and in the northern part of the Gulf of California (also called the Sea of Cortez), but are absent from the Cape (Cabo San Lucas) region. We studied the genetic makeup of disjunct populations for 12 of these 19 fish species. Phylogeographic patterns for the 12 species can be separated into two major classes: a first group (eight species) showed reciprocal monophyly and high genetic divergence between disjunct populations. A second group (four species) displayed what appeared to be panmictic populations. Population structure between Pacific Coast populations, across the Punta Eugenia biogeographic boundary, was also evaluated. While dispersal potential (inferred by pelagic larval duration) was a poor predictor of population structure between Gulf of California and Pacific populations, we found that population genetic subdivision along the Pacific Coast at Punta Eugenia was always positively correlated with differentiation between Pacific and Gulf of California populations. Vicariant events, ongoing gene flow, and ecological characteristics played essential roles in shaping the population structures observed in this study. [source] EVOLUTION OF POECILOGONY AND THE BIOGEOGRAPHY OF NORTH AMERICAN POPULATIONS OF THE POLYCHAETE STREBLOSPIOEVOLUTION, Issue 4 2000Stefan R. Schulze Abstract. Invertebrate interspecific developmental patterns can be highly variable and, taxonomically, are considered only weakly constrained. Intraspecifically, some invertebrate species possess multiple developmental modes,a condition known as poecilogony. Closer examination of most putative poecilogenous species, however, has not supported poecilogony, but rather has uncovered hidden or cryptic species. The polychaete Streblospio benedicti is a well-known, poecilogenous species found along the coast of North America. We collected mitochondrial cytochrome subunit I DNA sequence data from 88 individuals taken from 11 locations along the Atlantic, Gulf, and Pacific Coasts of the United States to provide a phylogenetic framework from which to interpret intraspecific variation in larval life history and brooding structure morphology in this species. Our results are consistent with a recent revision of the species into two separate species: S. benedicti, a pouched brooding form distributed along the Atlantic and Pacific Coasts, and S. gynobranchiata, a branchiate brooding form in the Gulf of Mexico. Contrary to the redescription, S. benedicti is paraphyletic because the pouched brooding population in Vero Beach, Florida shows strong genetic affinity with Gulf of Mexico populations (S. gynobranchiata). However, S. benedicti is a true poecilogenous species, with both lecithotrophic and planktotrophic individuals possessing identical mitochondrial DNA haplotypes. Crossbreeding experiments further support the molecular phylogeny with reproductive isolation demonstrated between, but not within, the major phylogenetic clades consistent with the previously described species. The genetic break near Vero Beach, Florida, corresponds to a well-known phylogeographic boundary, but the estimated time of separation for the Streblospio spp., approximately 10 million years before present, predates all other known phylogeographic subdivisions in this area. This suggests that biogeographic sundering in this region is a recurrent event. Divergence times within the major Streblospio spp. clades are recent and indicate that changes in larval life history as well as brooding structure morphology are highly plastic and can evolve rapidly. [source] | |||||||||||||||||||||||||||||||||||||||||||