Science.gov

Sample records for arabian sea

  1. Arabian Sea

    Atmospheric Science Data Center

    2013-04-16

    ... sometimes results in copious phytoplankton production and oxygen depletion of the subsurface waters. Although red phytoplankton fluorescences have been associated with the low oxygen concentrations in the intermediate and deep waters of the Arabian Sea, ...

  2. Open Ocean Bilging, Arabian Sea

    NASA Technical Reports Server (NTRS)

    1989-01-01

    These dual oil slicks on the ocean surface are the result of tanker ships flushing their tanks (bilging) in the Arabian Sea (18.5N, 62.5E). These two ships flushed out their bilges, apparently contaminated with bunker oil, leaving oily residues on the ocean's surface. One wake, believed to have been done earlier than the other, has been broadened by the effects of surface winds and current.

  3. Wave Clouds over the Arabian Sea

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Like a massive, ethereal bird gliding into the Persian Gulf, a large cluster of wave clouds spans the Arabian Sea from Oman to India. This cloud formation is likely an undular bore, which is created in the interaction between the cool, dry air in a low-pressure system with a stable layer of warm, moist air. In this case, a low-pressure system probably sits over the Arabian Peninsula, the Gulf of Oman, and Iran and Pakistan. The strong winds generated by the low-pressure system are kicking up clouds of dust from Iran and Pakistan, and, to a lesser degree, Oman. The low-pressure system is also pushing air south-southeast, and this south-moving wave of displaced air pushes ahead of the low-pressure system like a mound of water moving ahead of a boat in calm water. The wave of cool, dry air pushes forward until it meets the wall of warm, moist air that blankets the Arabian Sea. When the two air masses clash, the cool air pushes the warm air up. The warm air rises, cools at the peak of the wave, falls again, and then rises to a slightly lower peak, and so forth, until the wave dissipates. Clouds form at the high-altitude peaks of the waves, with the most defined cloud at the front of the group, where the initial wave formed, followed by increasingly less-defined lines of cloud. The air that moves in front of the low-pressure system does not push forward in a uniform wall; instead it pushes forward in a ragged band, with one part racing ahead of another, like a line of crew racers on a river. Because the air is not uniform, there are small, interacting arcs of waves within the larger band of clouds. Undular bores are rare and hard to predict. This particular undular bore formed over the Arabian Sea on May 8, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite captured this photo-like image. Typical undular bore patterns might display one or two rows of clouds. With more than thirty waves of clouds, this cloud pattern is unusually

  4. Salinity pathways between Arabian Sea and Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Krishna Kailasam, Muni

    2016-07-01

    Surface as well as subsurface salinity are highly heterogeneous in the Arabian Sea and the Bay of Bengal. Due to the strong seasonal reversal of currents in the two seas tremendous salt exchange occurred. The present study focuses on the exchange of salt between the Arabian Sea and Bay of Bengal by using remote sensing observations like SMOS and Aquarius. Inflow of high salinity water from the central Arabians Sea into the south Bay of Bengal is significant and occurs during August-September. Freshwater transport out of the Bay of Bengal is southward throughout the year along the along the east coast of the Indian sub-continent. Only a small fraction of low salinity water is advected into the eastern Arabian Sea from the Bay of Bengal. The pathways of salinity between the two seas are also examined using SODA data. It shows that relatively low salinity Bay of Bengal water is transported southward across the equator throughout the year. A considerable southward cross-equatorial exchange of Arabian Sea water occurs during the southwest monsoon season.

  5. Cabled ocean observatories in Sea of Oman and Arabian Sea

    NASA Astrophysics Data System (ADS)

    DiMarco, Steven F.; Wang, Zhankun; Jochens, Ann; Stoessel, Marion; Howard, Matthew K.; Belabbassi, Leila; Ingle, Stephanie; du Vall, Ken

    2012-07-01

    An ocean observatory—consisting of a real-time, cabled array in the Sea of Oman and an internally recording, autonomous mooring array recently upgraded to a cabled array in the northern Arabian Sea—celebrated more than 2500 days of continuous operation in July 2012. The observatory, which measures a range of properties, such as water current velocities, temperature, salinity, pressure, dissolved oxygen, and turbidity, is part of the Lighthouse Ocean Research Initiative (LORI) project [du Vall et al., 2011], which was designed as a pilot project and installed in 2005 in the region off Abu Bakara (Figures 1a and 1b). The initial goal of the project was to prove that an in situ, cabled ocean observatory can return high-quality scientific data on a real-time basis over longer time periods than conventional moored systems. That same year, an autonomous array was deployed off Ras al Hadd and on Murray Ridge in the Arabian Sea (Figure 1a).

  6. Marine geology and oceanography of Arabian Sea and coastal Pakistan

    SciTech Connect

    Haq, B.U.; Milliman, J.D.

    1985-01-01

    This volume is a collection of papers presented at the first US-Pakistan workshop in marine science held in Karachi, Pakistan, in November 1982. Of the twenty-four contributions in this book, fourteen cover topics specific to the Arabian Sea-coastal Pakistan region. These include six papers on the geology, tectonics, and petroleum potential of Pakistan, four papers on sedimentary processes in the Indus River delta-fan complex, and four papers on the biological oceanography of the Arabian Sea and coastal Pakistan. The additional ten papers are overviews of shelf sedimentation processes, paleoceanography, the marine nutrient cycle, and physical and chemical oceanography.

  7. Remotely Searching for Noctiluca Miliaris in the Arabian Sea

    NASA Technical Reports Server (NTRS)

    Werdell, P. Jeremy; Roesler, Collin S.; Goes, Joaquim I.

    2014-01-01

    Reversing monsoonal winds in the Arabian Sea result in two seasons with elevated biological activity, namely the annual summer Southwest Monsoon (SWM; June to September) and winter Northeast Monsoon (NEM; November to March) [Wiggert et al., 2005]. Generally speaking, the SWM and NEM create two geographically distinct blooms [Banse and English, 2000; Levy et al., 2007]. In the summer, winds from the southwest drive offshore Ekman transport and coastal upwelling along the northwestern coast of Africa, which brings nutrient-rich water to the surface from below the permanent thermocline [Bauer et al., 1991]. In the winter, cooling of the northern Arabian Sea causes surface waters to sink, which generates convective mixing that injects nutrients throughout the upper mixed layer [Madhupratap et al., 1996]. This fertilization of otherwise nutrient-deplete surface waters produces one of the most substantial seasonal extremes of phytoplankton biomass and carbon flux anywhere in the world [Smith, 2005].

  8. Benthic nitrogen loss in the arabian sea off pakistan.

    PubMed

    Sokoll, Sarah; Holtappels, Moritz; Lam, Phyllis; Collins, Gavin; Schlüter, Michael; Lavik, Gaute; Kuypers, Marcel M M

    2012-01-01

    A pronounced deficit of nitrogen (N) in the oxygen minimum zone (OMZ) of the Arabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagic processes. However, the OMZ water is in direct contact with sediments on three sides of the basin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largely unassessed. In October 2007, we sampled the water column and surface sediments along a transect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering a range of station depths from 360 to 1430 m. Benthic denitrification and anammox rates were determined by using (15)N-stable isotope pairing experiments. Intact core incubations showed declining rates of total benthic N-loss with water depth from 0.55 to 0.18 mmol N m(-2) day(-1). While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46 mmol N m(-2) day(-1) with water depth, anammox rates increased from 0.21 to 0.89 mmol N m(-2) day(-1). Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360 m to 40% at 1430 m. This trend is further supported by the quantification of cd(1)-containing nitrite reductase (nirS), the biomarker functional gene encoding for cytochrome cd(1)-Nir of microorganisms involved in both N-loss processes. Anammox-like nirS genes within the sediments increased in proportion to total nirS gene copies with water depth. Moreover, phylogenetic analyses of NirS revealed different communities of both denitrifying and anammox bacteria between shallow and deep stations. Together, rate measurement and nirS analyses showed that anammox, determined for the first time in the Arabian Sea sediments, is an important benthic N-loss process at the continental margin off Pakistan, especially in the sediments at deeper water depths. Extrapolation from the measured benthic N-loss to all shelf sediments within the basin suggests that benthic N-loss may be

  9. Benthic Nitrogen Loss in the Arabian Sea Off Pakistan

    PubMed Central

    Sokoll, Sarah; Holtappels, Moritz; Lam, Phyllis; Collins, Gavin; Schlüter, Michael; Lavik, Gaute; Kuypers, Marcel M. M.

    2012-01-01

    A pronounced deficit of nitrogen (N) in the oxygen minimum zone (OMZ) of the Arabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagic processes. However, the OMZ water is in direct contact with sediments on three sides of the basin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largely unassessed. In October 2007, we sampled the water column and surface sediments along a transect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering a range of station depths from 360 to 1430 m. Benthic denitrification and anammox rates were determined by using 15N-stable isotope pairing experiments. Intact core incubations showed declining rates of total benthic N-loss with water depth from 0.55 to 0.18 mmol N m−2 day−1. While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46 mmol N m−2 day−1 with water depth, anammox rates increased from 0.21 to 0.89 mmol N m−2 day−1. Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360 m to 40% at 1430 m. This trend is further supported by the quantification of cd1-containing nitrite reductase (nirS), the biomarker functional gene encoding for cytochrome cd1-Nir of microorganisms involved in both N-loss processes. Anammox-like nirS genes within the sediments increased in proportion to total nirS gene copies with water depth. Moreover, phylogenetic analyses of NirS revealed different communities of both denitrifying and anammox bacteria between shallow and deep stations. Together, rate measurement and nirS analyses showed that anammox, determined for the first time in the Arabian Sea sediments, is an important benthic N-loss process at the continental margin off Pakistan, especially in the sediments at deeper water depths. Extrapolation from the measured benthic N-loss to all shelf sediments within the basin suggests that benthic N-loss may be

  10. Arabian Red Sea coastal soils as potential mineral dust sources

    NASA Astrophysics Data System (ADS)

    Jish Prakash, P.; Stenchikov, Georgiy; Tao, Weichun; Yapici, Tahir; Warsama, Bashir; Engelbrecht, Johann P.

    2016-09-01

    Both Moderate Resolution Imaging Spectroradiometer (MODIS) and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) satellite observations suggest that the narrow heterogeneous Red Sea coastal region is a frequent source of airborne dust that, because of its proximity, directly affects the Red Sea and coastal urban centers. The potential of soils to be suspended as airborne mineral dust depends largely on soil texture, moisture content and particle size distributions. Airborne dust inevitably carries the mineralogical and chemical signature of a parent soil. The existing soil databases are too coarse to resolve the small but important coastal region. The purpose of this study is to better characterize the mineralogical, chemical and physical properties of soils from the Arabian Red Sea coastal plain, which in turn will help to improve assessment of dust effects on the Red Sea, land environmental systems and urban centers. Thirteen surface soils from the hot-spot areas of windblown mineral dust along the Red Sea coastal plain were sampled for analysis. Analytical methods included optical microscopy, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), ion chromatography (IC), scanning electron microscopy (SEM) and laser particle size analysis (LPSA). We found that the Red Sea coastal soils contain major components of quartz and feldspar, as well as lesser but variable amounts of amphibole, pyroxene, carbonate, clays and micas, with traces of gypsum, halite, chlorite, epidote and oxides. The range of minerals in the soil samples was ascribed to the variety of igneous and metamorphic provenance rocks of the Arabian Shield forming the escarpment to the east of the Red Sea coastal plain. The analysis revealed that the samples contain compounds of nitrogen, phosphorus and iron that are essential nutrients to marine life. The analytical results from this study will provide a valuable input into dust emission models used in climate

  11. Seasonality in the Arabian Sea over glacial-interglacial cycles

    NASA Astrophysics Data System (ADS)

    de Nooijer, L. J.; Tjallingii, R.; Brummer, G. J.; Reichart, G. J.

    2012-04-01

    The Indian monsoon system controls seasonal precipitation alterations over the Indian continent and upwelling of nutrient-rich waters to the surface in the northern Arabian Sea. Functioning and strength of this weather system due to climate change is one of the important issues in predicting the effects of global warming on the region's economy, agriculture and social welfare. The strength of the Indian monsoon system through time can be studied by changes in seawater temperature and chemistry from single-specimen analysis of planktic foraminiferal calcite. Temperature reconstructions based on many single specimens allow reconstruction of past seasonal sea water temperatures ranges and thus seasonal temperature variability. . Here we present seawater reconstructions based on single-specimen Mg/Ca of the surface dweller Globigerinoides ruber and the deeper-living G. dutertrei of two sediment cores of the western equatorial Indian Ocean off Tanzania and the northern Arabian Sea. From both cores, specimens are analyzed for calcitic Mg/Ca using laser ablation-ICP-MS of time-intervals representing the Holocene optimum, Last Glacial Maximum, Marine Isotope Stage 4, MIS 5 and MIS6. The resulting temperature ranges allow reconstruction of variability in the strength of the Indian Monsoon as well as cross-equatorial heat transport during glacials and interglacials.

  12. Carbon fluxes in the Arabian Sea: Export versus recycling

    NASA Astrophysics Data System (ADS)

    Rixen, Tim; Gaye, Birgit; Ramaswamy, Venkitasubramani

    2016-04-01

    The organic carbon pump strongly influences the exchange of carbon between the ocean and the atmosphere. It is known that it responds to global change but the magnitude and the direction of change are still unpredictable. Sediment trap experiments carried out at various sites in the Arabian Sea between 1986 and 1998 have shown differences in the functioning of the organic carbon pump (OCP). An OCP driven by eukaryotic phytoplankton operated in the upwelling region off Oman and during the spring bloom in the northern Arabian Sea. Cyanobacteria capable of fixing nitrogen seem to dominate the phytoplankton community during all other seasons. The export driven by cyanobacteria was much lower than the export driven by eukaryotic phytoplankton. Productivity and nutrient availability seems to be a main factor controlling fluxes during blooms of eukaryotic phytoplankton. The ballast effect caused by inputs of dust into the ocean and its incorporation into sinking particles seems to be the main factor controlling the export during times when cyanobacteria dominate the phytoplankton community. C/N ratios of organic matter exported from blooms dominated by nitrogen fixing cyanobacteria are enhanced and, furthermore, indicate a more efficient recycling of nutrients at shallower water depth. This implies that the bacterial-driven OCP operates more in a recycling mode that keeps nutrients closer to the euphotic zone whereas the OCP driven by eukaryotic phytoplankton reduces the recycling of nutrients by exporting them into greater water-depth.

  13. Demersal Fisheries of the Arabian Sea, the Gulf of Oman and the Arabian Gulf

    NASA Astrophysics Data System (ADS)

    Siddeek, M. S. M.; Fouda, M. M.; Hermosa, G. V.

    1999-08-01

    The demersal fisheries of the Arabian Sea, the Gulf of Oman and the Arabian Gulf are reviewed. The region comprises eight countries: Oman, United Arab Emirates (U.A.E.), Qatar, Saudi Arabia, Bahrain, Kuwait, Iraq and Iran. Over 350 commercial fish species, eight shrimp species, two spiny lobster species, one shovel nose lobster species, one cuttlefish species, one crab species, and one abalone species support the demersal fisheries in the continental shelves of the three regions. Artisanal and industrial vessels with over 120 000 fishermen were involved in demersal fisheries. Fishing boats include fish and shrimp trawlers (wooden and steel hulled), large wooden boats (dhow) with inboard engines, small dhows with outboard engines, and fibreglass boats. Fishing gear consists of trawls, bottom gill nets, traps (wire mesh and plastic types), barrier traps, hand lines, and bare hands and knives (to dislodge abalone). Demersal fish (primarily Lethrinidae, Sparidae, Serranidae, Siganidae, Sciaenidae, Stromateidae, Lutjanidae, Trichiuridae, and Nemipteridae) and shrimp (primarily Penaeus semisulcatus, Metapenaeus affinis, Parapenaeopsis stylifera, and Penaeus merguiensis) were the two commercial demersal resources. Approximately 198 000-214 000 tonnes (t) of demersals were landed annually during 1988-1993, accounting for nearly 40% of the total marine landings (475 000-552 000 t). This percentage, however varied among countries: 25% in Oman, 32% in U.A.E., 71% in Qatar, 52% in Saudi Arabia, 56% in Bahrain, 55% in Kuwait, close to 100% in Iraq, and 41% in Iran. Fishing effort on certain stocks may have been below the optimum level (e.g. certain Omani demersal fish), near the optimum level (e.g. Omani shrimp), or above the optimum level (e.g. Arabian Gulf shrimp and demersal fish). Overexploitation led to restriction of fishing effort by limiting fishing licences, regulating fishing gear (mesh size) and capture size, closing fishing areas, restricting fishing season, and

  14. Origin of cold bias over the Arabian Sea in Climate Models.

    PubMed

    Sandeep, S; Ajayamohan, R S

    2014-09-17

    Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous cold winds from the north-western part of south Asian landmass during boreal winter. However, the origin of the anomalously strong cold winds over the Arabian Sea and its association with the large-scale circulation is obscure. Here we show that an equatorward bias in subtropical Jetstream during boreal spring season anomalously cools down the northern Arabian Sea and adjoining land regions in CMIP5 models. The models with stronger equatorward bias in subtropical jet are also the ones with stronger cold SST bias over the Arabian Sea. The equatorward shift coupled with enhanced strength of the subtropical jet produce a stronger upper tropospheric convergence, leading to a subsidence and divergence at lower levels over the Arabian deserts. The low entropy air flowing from the Arabian land mass cools the northern Arabian Sea. The weaker meridional temperature gradients in the colder models substantially weaken ISM precipitation.

  15. Origin of cold bias over the Arabian Sea in Climate Models

    NASA Astrophysics Data System (ADS)

    Sandeep, S.; Ajayamohan, R. S.

    2014-09-01

    Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous cold winds from the north-western part of south Asian landmass during boreal winter. However, the origin of the anomalously strong cold winds over the Arabian Sea and its association with the large-scale circulation is obscure. Here we show that an equatorward bias in subtropical Jetstream during boreal spring season anomalously cools down the northern Arabian Sea and adjoining land regions in CMIP5 models. The models with stronger equatorward bias in subtropical jet are also the ones with stronger cold SST bias over the Arabian Sea. The equatorward shift coupled with enhanced strength of the subtropical jet produce a stronger upper tropospheric convergence, leading to a subsidence and divergence at lower levels over the Arabian deserts. The low entropy air flowing from the Arabian land mass cools the northern Arabian Sea. The weaker meridional temperature gradients in the colder models substantially weaken ISM precipitation.

  16. Origin of cold bias over the Arabian Sea in Climate Models.

    PubMed

    Sandeep, S; Ajayamohan, R S

    2014-01-01

    Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous cold winds from the north-western part of south Asian landmass during boreal winter. However, the origin of the anomalously strong cold winds over the Arabian Sea and its association with the large-scale circulation is obscure. Here we show that an equatorward bias in subtropical Jetstream during boreal spring season anomalously cools down the northern Arabian Sea and adjoining land regions in CMIP5 models. The models with stronger equatorward bias in subtropical jet are also the ones with stronger cold SST bias over the Arabian Sea. The equatorward shift coupled with enhanced strength of the subtropical jet produce a stronger upper tropospheric convergence, leading to a subsidence and divergence at lower levels over the Arabian deserts. The low entropy air flowing from the Arabian land mass cools the northern Arabian Sea. The weaker meridional temperature gradients in the colder models substantially weaken ISM precipitation. PMID:25228235

  17. Origin of cold bias over the Arabian Sea in Climate Models

    PubMed Central

    Sandeep, S.; Ajayamohan, R. S.

    2014-01-01

    Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous cold winds from the north-western part of south Asian landmass during boreal winter. However, the origin of the anomalously strong cold winds over the Arabian Sea and its association with the large-scale circulation is obscure. Here we show that an equatorward bias in subtropical Jetstream during boreal spring season anomalously cools down the northern Arabian Sea and adjoining land regions in CMIP5 models. The models with stronger equatorward bias in subtropical jet are also the ones with stronger cold SST bias over the Arabian Sea. The equatorward shift coupled with enhanced strength of the subtropical jet produce a stronger upper tropospheric convergence, leading to a subsidence and divergence at lower levels over the Arabian deserts. The low entropy air flowing from the Arabian land mass cools the northern Arabian Sea. The weaker meridional temperature gradients in the colder models substantially weaken ISM precipitation. PMID:25228235

  18. Eddies reduce denitrification and compress habitats in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Lachkar, Zouhair; Smith, Shafer; Lévy, Marina; Pauluis, Olivier

    2016-09-01

    The combination of high biological production and weak oceanic ventilation in regions, such as the northern Indian Ocean and the eastern Pacific and Atlantic, cause large-scale oxygen minimum zones (OMZs) that profoundly affect marine habitats and alter key biogeochemical cycles. Here we investigate the effects of eddies on the Arabian Sea OMZ—the world's thickest—using a suite of regional model simulations with increasing horizontal resolution. We find that isopycnal eddy transport of oxygen to the OMZ region limits the extent of suboxia so reducing denitrification, increasing the supply of nitrate to the surface, and thereby enhancing biological production. That same enhanced production generates more organic matter in the water column, amplifying oxygen consumption below the euphotic zone, thus increasing the extent of hypoxia. Eddy-driven ventilation likely plays a similar role in other low-oxygen regions and thus may be crucial in shaping marine habitats and modulating the large-scale marine nitrogen cycle.

  19. Climate oscillations reflected in the Arabian Sea subseafloor microbiome

    NASA Astrophysics Data System (ADS)

    Orsi, William; Coolen, Marco; He, Lijun; Wuchter, Cornelia; Irigoien, Xabier; Chust, Guillem; Johnson, Carl; Hemingway, Jordon; Lee, Mitchell; Galy, Valier; Giosan, Liviu

    2016-04-01

    Marine sediment contains a vast microbial biosphere that influences global biogeochemical cycles over geological timescales. However, the environmental factors controlling the stratigraphy of subseafloor microbial communities are poorly understood. We studied a sediment core directly underlying the Arabian Sea oxygen minimum zone (OMZ), which exhibits organic carbon rich sapropelic laminae deposited under low oxygen conditions. Consistent with several other cores from the same location, age dating revealed the sapropelic layers coincide with warm North Atlantic millennial-scale Dansgaard-Oeschger events, indicating a direct link between the strength of the OMZ and paleoclimate. A total of 214 samples spanning 13 m and 52 Kyr of deposition were selected for geochemical analyses and paleoclimate proxy measurements, as well as high-throughput metagenomic DNA sequencing of bacteria and archaea. A novel DNA extraction protocol was developed that allowed for direct (unamplified) metagenomic sequencing of DNA from each sample. This dataset represents the highest resolved sedimentary metagenomic sampling profile to date. Analysis of these data together with multiple paleoceanographic proxies show that millennial-scale paleoenvironmental conditions correlate with the metabolism and diversity of bacteria and archaea over the last glacial-interglacial cycle in the Arabian Sea. The metabolic potential for bacterial denitrification correlates with climate-driven OMZ strength and concomitant nitrogen stable isotope fractionation, whereas catabolic potential reflects changing marine organic matter sources across the Last Glacial Maximum. These results indicate that the subsisting microbial communities had been stratified to a large extent by paleoceanographic conditions at the time of deposition. Paleoenvironmental conditions should thus be considered as a mechanism that can help explain microbiome stratigraphy in marine sediment.

  20. Primary productivity and nitrogen fixation by Trichodesmium spp. in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Parab, Sushma G.; Matondkar, S. G. P.

    2012-12-01

    Trichodesmium was studied with the purpose of understanding its distribution, organic production and nitrogen fixation in the Arabian Sea. Out of the 143 stations sampled, a total of 93 stations showed the presence of Trichodesmium filaments. Two species of Trichodesmium namely, T. thiebautii and T. erythraeum were found. These were distributed on the basis of the physico-chemical conditions of the Arabian Sea. This was the first time that we managed to detect and record the presence of Trichodesmium thiebautii bloom in the Arabian Sea at depths as deep as 60-70 m. Total counts of Trichodesmium varied between 0 and 400737 filamentsL- 1. T. thiebautii developed in offshore waters during the fall intermonsoon, when the water temperature was around 28 °C and nitrate content was as low as 0.34 μM. After the northeast monsoon, Trichodesmium erythraeum developed in the offshore area and then spread to coastal waters. Both species of Trichodesmium together produced a total of 0.263 TgCyear- 1 and fixed a total of 0.2976 TgNyear- 1 in the Arabian Sea. The study revealed that Trichodesmium was a major contributor to the organic matter productivity of the Arabian Sea during the period from November to April. The seasonality of the blooms of Trichodesmium is discussed with the help of Ocean Color Monitoring (OCM) data and biogeochemical implication of these findings in the Arabian Sea.

  1. Biological control of surface temperature in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Sathyendranath, Shubha; Gouveia, Albert D.; Shetye, Satish R.; Ravindran, P.; Platt, Trevor

    1991-01-01

    BY far the dominant variable parameter controlling the absorption cross-section for short-wavelength solar radiation incident on the ocean surface is the concentration of photosynthetic pigment contained in phytoplankton cells1,2. The abundance of phytoplankton depends on the intensity of incident radiation and on the supply of essential nutrients (nitrogen in particular). A higher abundance increases absorption of radiation and thus enhances the rate of heating at the ocean surface. In the Arabian Sea, the southwest monsoon promotes seasonal upwelling of deep water, which supplies nutrients to the surface layer3,4 and leads to a marked increase in phytoplankton growth. Using remotely sensed data on ocean colour, we show here that the resulting distribution of phytoplankton exerts a controlling influence on the seasonal evolution of sea surface temperature. This results in a corresponding modification of ocean-atmosphere heat exchange on regional and seasonal scales. Thus we show that this biological mechanism may provide an important regulating influence on ocean-atmosphere interactions.

  2. The Arabian scad Trachurus indicus, a new Indo-Pacific species in the Mediterranean Sea.

    PubMed

    Dalyan, C; Eryilmaz, L

    2009-05-01

    The Arabian scad Trachurus indicus is recorded for the first time from the Mediterranean Sea (Iskenderun Bay, Turkey). The presence of this Indo-Pacific fish in the Mediterranean Sea is probably because of migration from the Red Sea via the Suez Canal.

  3. Modelling the seasonality of subsurface light and primary production in the Arabian Sea

    USGS Publications Warehouse

    Brock, John C.; Sathyendranath, Shubha; Platt, Trevor

    1993-01-01

    Seasonal changes in mixed-layer depth and phytoplankton biomass in the Arabian Sea are assessed with climatologies of ship-based hydrographic measurements and ocean-color observations from satellite.  At the close of the intermonsoons in November and especially May, the open Arabian Sea resembles the stereotypic, unperturbed tropical ocean, with a thin oligotrophic mixed layer and a pronounced subsurface chlorophyll maximum.  Both the northeast and southwest monsoons disrupt this typical tropical hydrography through mixed-layer deepening and eutrophication in the central and northern Arabian Sea.  Computations using a spectral model of light penetration suggest that seasonal changes in mixed-layer thickness and phytoplankton concentration result in pronounced fluctuations through the annual cycle in the radiant flux reaching the base of the mixed layer.  At the close of the fall and spring intermonsoons the base of the model euphotic zone is in the thermocline across all of the open Arabian Sea.  The euphotic zone appears to rise into the mixed layer of the northern Arabian Sea during both the winter and summer monsoons.  Strong seasonality in total primary production and its partitioning between the mixed layer and thermocline is predicted byb a photo-synthesis-irradiance model for a site in the western Arabian Sea (14.36° N, 57.38° E).  Modeled mixed-layer primary production depicts an intense peak for the southwest monsoon and a secondary northeast monsoon peak separated by intermonsoon period of low production.  During the fall and spring intermonsoons, in the presence of a subsurface clorophyll maximum, the model estimate of primary production in the thermocline exceeds that in the mixed layer.  Our model calculations suggest that the subsurface clorophyll maximum present in the Arabian Sea during the spring intermonsoon is a precursor of the regional, summer, phytoplankton bloom.

  4. Arabian Sea tropical cyclones intensified by emissions of black carbon and other aerosols.

    PubMed

    Evan, Amato T; Kossin, James P; Chung, Chul Eddy; Ramanathan, V

    2011-11-02

    Throughout the year, average sea surface temperatures in the Arabian Sea are warm enough to support the development of tropical cyclones, but the atmospheric monsoon circulation and associated strong vertical wind shear limits cyclone development and intensification, only permitting a pre-monsoon and post-monsoon period for cyclogenesis. Thus a recent increase in the intensity of tropical cyclones over the northern Indian Ocean is thought to be related to the weakening of the climatological vertical wind shear. At the same time, anthropogenic emissions of aerosols have increased sixfold since the 1930s, leading to a weakening of the southwesterly lower-level and easterly upper-level winds that define the monsoonal circulation over the Arabian Sea. In principle, this aerosol-driven circulation modification could affect tropical cyclone intensity over the Arabian Sea, but so far no such linkage has been shown. Here we report an increase in the intensity of pre-monsoon Arabian Sea tropical cyclones during the period 1979-2010, and show that this change in storm strength is a consequence of a simultaneous upward trend in anthropogenic black carbon and sulphate emissions. We use a combination of observational, reanalysis and model data to demonstrate that the anomalous circulation, which is radiatively forced by these anthropogenic aerosols, reduces the basin-wide vertical wind shear, creating an environment more favourable for tropical cyclone intensification. Because most Arabian Sea tropical cyclones make landfall, our results suggest an additional impact on human health from regional air pollution.

  5. Response of the Arabian Sea to global warming and associated regional climate shift.

    PubMed

    Kumar, S Prasanna; Roshin, Raj P; Narvekar, Jayu; Kumar, P K Dinesh; Vivekanandan, E

    2009-12-01

    The response of the Arabian Sea to global warming is the disruption in the natural decadal cycle in the sea surface temperature (SST) after 1995, followed by a secular warming. The Arabian Sea is experiencing a regional climate-shift after 1995, which is accompanied by a five fold increase in the occurrence of "most intense cyclones". Signatures of this climate-shift are also perceptible over the adjacent landmass of India as: (1) progressively warmer winters, and (2) decreased decadal monsoon rainfall. The warmer winters are associated with a 16-fold decrease in the decadal wheat production after 1995, while the decreased decadal rainfall was accompanied by a decline of vegetation cover and increased occurrence of heat spells. We propose that in addition to the oceanic thermal inertia, the upwelling-driven cooling provided a mechanism that offset the CO(2)-driven SST increase in the Arabian Sea until 1995.

  6. Nematode abundance at the oxygen minimum zone in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Cook, Adam A.; Lambshead, P. John D.; Hawkins, Lawrence E.; Mitchell, Nicola; Levin, Lisa A.

    2000-01-01

    This paper supports the hypothesis that low oxygen does not influence deep-sea nematode abundance by investigating an oxygen minimum zone (OMZ) on the Oman slope in the Arabian Sea. Correlation with a number of environmental variables indicated that food quality (measured as the hydrogen index) rather than oxygen was the major predictor of nematode abundance. Nematode abundance was also positively correlated with abundance of total macrofauna, annelids, spionid polychaetes and macrofaunal tube builders. Comparison with published data showed Arabian Sea nematode abundance to be similar to that of the Porcupine Seabight and Bay of Biscay regions of the northeast Atlantic, which also receive significant quantities of phytodetritus but have no OMZ.

  7. Warming of the Eurasian landmass is making the Arabian Sea more productive.

    PubMed

    Goes, Joaquim I; Thoppil, Prasad G; Gomes, Helga do R; Fasullo, John T

    2005-04-22

    The recent trend of declining winter and spring snow cover over Eurasia is causing a land-ocean thermal gradient that is particularly favorable to stronger southwest (summer) monsoon winds. Since 1997, sea surface winds have been strengthening over the western Arabian Sea. This escalation in the intensity of summer monsoon winds, accompanied by enhanced upwelling and an increase of more than 350% in average summertime phytoplankton biomass along the coast and over 300% offshore, raises the possibility that the current warming trend of the Eurasian landmass is making the Arabian Sea more productive.

  8. A model study of seasonal mixed-layer primary production in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Brock, John; Sathyendranath, Shubha; Platt, Trevor

    1994-06-01

    We combined a surface irradiance model with a non-spectral photosynthesisirradiance model to estimate the daily, average rate of mixed-layer primary production in the Arabian Sea for the 15th day of months at the end of the northeast monsoon, the southwest monsoon, and the fall and spring inter-monsoons. Our model experiment uses climatologies of cloud cover, mixed-layer thickness, and satellite ocean-color observations of phytoplankton biomass. Modelled surface radiation is at an annual maximum in May beneath nearly cloud-free skies just prior to the summer solstice. The model estimate of surface radiation diminishes through the southwest monsoon over most of the northern Arabian Sea to an annual minimum in August due to intense cloudiness. In agreement with previous ship-based measurements, the photosynthesis-irradiance model predicts that the mixed-layer primary production in the Arabian Sea is extremely seasonal, and peaks annually during the southwest monsoon to the north-west of the atmospheric Findlater Jet and along the coast of Somalia. Northern Arabian Sea maxima predicted for both the summer and winter monsoons are separated by periods of low mixed-layer primary production, the fall and spring inter-monsoons. The annual cycles of modelled mixed-layer primary production differ by region in the Arabian Sea due to varying monsoon influence and circulation dynamics.

  9. Eastward shift and maintenance of Arabian Sea oxygen minimum zone: Understanding the paradox

    NASA Astrophysics Data System (ADS)

    Acharya, Shiba Shankar; Panigrahi, Mruganka K.

    2016-09-01

    The dominance of Oxygen Minimum Zone in the eastern part of the Arabian Sea (ASOMZ) instead of the more bio-productive and likely more oxygen consuming western part is the first part of the paradox. The sources of oxygen to the ASOMZ were evaluated through the distributions of different water masses using the extended optimum multiparameter (eOMP) analysis, whereas the sinks of oxygen were evaluated through the organic matter remineralization, using the apparent oxygen utilization (AOU). The contributions of major source waters to the Arabian Sea viz. Indian Deep water (dIDW), Indian Central water (ICW), Persian Gulf Water (PGW) and Red Sea Water (RSW) have been quantified through the eOMP analysis which shows that the PGW and RSW are significant for the eastward shift of ASOMZ instead of voluminous ICW and dIDW. The distribution of Net Primary Production (NPP) and AOU clearly suggest the transport of organic detritus from the highly productive western Arabian Sea to its eastern counterpart which adds to the eastward shifting of ASOMZ. A revised estimate of the seasonal variation of areal extent and volume occupied by ASOMZ through analysis of latest available data reveals a distinct intensification of ASOMZ by 30% and increase in its volume by 5% during the spring-summer transition. However, during this seasonal transition the productivity in the Arabian Sea shows 100% increase in mean NPP. This disparity between ASOMZ and monsoonal variation of productivity is the other part of the paradox, which has been constrained through apparent oxygen utilization, Net Primary Production along with a variation of core depths of source waters. This study reveals a subtle balance between the circulation of marginal oxygen-rich water masses from the western Arabian Sea and organic matter remineralization in the eastern Arabian Sea in different seasons that explains the maintenance of ASOMZ throughout the year.

  10. Diversity and distribution of winter phytoplankton in the Arabian Gulf and the Sea of Oman

    NASA Astrophysics Data System (ADS)

    Polikarpov, Igor; Saburova, Maria; Al-Yamani, Faiza

    2016-05-01

    The spatial distribution of the phytoplankton (diversity, composition, and cell abundance) was described in relation to local environmental conditions across the Arabian Gulf, the Strait of Hormuz, and the Sea of Oman based on data of ROPME cruise of winter 2006. The 376 phytoplankton taxa identified in these waters represented a diverse composition of species with a prevalence of dinoflagellates and diatoms. Three peaks in the phytoplankton abundance were recorded throughout the studied area associated with diatom-dominated phytoplankton blooms in the central and northwestern part of the Arabian Gulf and in the Sea of Oman and the adjacent waters. The studied area was divided into three main regions by cluster analysis based on differences in the phytoplankton composition and concentration. The Sea of Oman and the Strait of Hormuz were occupied by highly abundant, strongly diatom-dominated phytoplankton assemblage. The Arabian Gulf was divided into two main regions along a diagonal northwest-southeast axis, with rather diatom-dominated phytoplankton assemblage off the south and along the Iranian coast but with flagellate-dominated phytoplankton of the north and along the Arabian coast. The distance-based linear modeling revealed a significant relationship between the phytoplankton composition and water masses as indexed by salinity. Our results demonstrated that abundance and composition of winter phytoplankton were related to water circulation pattern in the Arabian Gulf and the Sea of Oman.

  11. Characteristics of convective boundary layer over the Arabian sea region

    SciTech Connect

    Parasnis, S.S.

    1996-12-31

    The Convective Boundary Layer (CBL) over the oceanic regions plays an important role in regulating the transport of energy and moisture upward into the atmosphere from the surface. CBL structure over the Arabian sea region has been explored using the aerological soundings at two ships viz. SHIRSHOV (12.5{degrees}N, 68{degrees}E ) and OKEAN (14.5{degrees} N, 66{degrees} E) during MONSOON-77. Conserved variable analysis of the mean data sets obtained during the period of 29 June - 16 July, 1977 revealed salient features of the CBL over these regions. The vertical gradients of saturation point parameters viz. virtual potential temperature ({Theta}{sub v}), equivalent potential temperature ({Theta}{sub e}), saturated equivalent potential temperature ({Theta}{sub es}), saturation pressure deficit (P*) and the mixing ratio (q) were used to characterize the different sublayers such as subcloud layer, cloud layer and inversion/stable layer. The mean cloud base was around 950 hPa and the subcloud layer has nearly constant {Theta}{sub v}. The moist layer was associated with unstable {Theta}{sub es} with nearly constant value of P* ({approximately} -40 hPa). This cloud layer was capped by the stable (over OKEAN). The {Theta}{sub e} minimum over OKEAN was observed at 650 hPa (50 hPa above the CBL top) indicating that at some time the convection had reached deeper levels. The {Theta}{sub e} -q diagrams showed a characteristic mixing line up through the cloud and stable layer to the top of CBL. The low level stability analysis using the {Theta}{sub e} and {Theta}{sub es} profiles indicated conditions favorable for shallow convection over OKEAN and for deep convection over SHIRSHOV. The above characteristic features could be attributed to the prevailing weather conditions at OKEAN and SHIRSHOV. The results are discussed.

  12. Ammonia oxidation rates and nitrification in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Newell, Silvia E.; Babbin, Andrew R.; Jayakumar, Amal; Ward, Bess B.

    2011-12-01

    Nitrification rates, as well as the relationships between rates and ammonia oxidizer abundance (both archaeal and bacterial), were investigated in the Arabian Sea. Ammonia oxidation rates were measured directly using 15N-NH4+stable isotope additions in gas-impermeable, trace metal clean trilaminate bags (500 mL) at in situ temperature. Tracer incubations were performed at three stations at depths above, below, and within the oxycline of the open-ocean oxygen minimum zone (OMZ). Ammonia oxidation rates were similar to previous open-ocean measurements, ranging from undetectable to 21.6 ± 0.1 nmol L-1 d-1. The highest rates at each station occurred at the primary nitrite maximum (above the OMZ), and rates were very low at depths greater than 900 m. The abundances of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were estimated using theamoA gene by quantitative polymerase chain reaction (qPCR). Both AOA and AOB amoA were detected above, within, and below the OMZ, although the AOA were always more abundant than the AOB, by a factor of 35-216. Nitrification rates were not directly correlated to AOA or AOB amoA abundance. These rates offer new insight into the role of nitrification in the mesopelagic zone. The abundance of AOA amoA genes at 1000 m suggests that ˜50% of the microbial biomass could be autotrophic. Additionally, the integrated nitrification rate at depth implies that nitrification could consume most of the ammonium produced by the flux of organic carbon in the mesopelagic zone.

  13. Inventory of released inorganic carbon from organic matter remineralization in the deeper Arabian Sea

    NASA Astrophysics Data System (ADS)

    Hupe, Axel; Thomas, Helmuth; Ittekkot, Venugopalan; Lendt, Ralf

    2001-12-01

    An attempt is made to quantify the biological carbon pump in Arabian Sea subsurface waters by estimating the total concentrations of remineralized dissolved inorganic carbon (DICrem) and its water column inventory. The influence of different sets of -ΔO2/ΔCorg ratios, which are either constant or variable with depth, on the estimate is assessed. Throughout the water column the horizontally mapped DICrem concentrations increase northward due to enlarged export fluxes of organic matter and subsequently enhanced remineralization processes as well as to the accumulation of remineralization products along the trajectory path of the water masses ventilating the Arabian Sea from the southern Indian Ocean. The choice of the remineralization ratios generates significant differences in the DICrem concentrations at specific depth horizons. The DICrem inventory of the Arabian Sea between 500 and 4500 m in the years 1995-1997 amounts to ˜39-44 Gt C depending on the applied remineralization ratios.

  14. Denitrification as the dominant nitrogen loss process in the Arabian Sea.

    PubMed

    Ward, B B; Devol, A H; Rich, J J; Chang, B X; Bulow, S E; Naik, Hema; Pratihary, Anil; Jayakumar, A

    2009-09-01

    Primary production in over half of the world's oceans is limited by fixed nitrogen availability. The main loss term from the fixed nitrogen inventory is the production of dinitrogen gas (N(2)) by heterotrophic denitrification or the more recently discovered autotrophic process, anaerobic ammonia oxidation (anammox). Oceanic oxygen minimum zones (OMZ) are responsible for about 35% of oceanic N(2) production and up to half of that occurs in the Arabian Sea. Although denitrification was long thought to be the only loss term, it has recently been argued that anammox alone is responsible for fixed nitrogen loss in the OMZs. Here we measure denitrification and anammox rates and quantify the abundance of denitrifying and anammox bacteria in the OMZ regions of the Eastern Tropical South Pacific and the Arabian Sea. We find that denitrification rather than anammox dominates the N(2) loss term in the Arabian Sea, the largest and most intense OMZ in the world ocean. In seven of eight experiments in the Arabian Sea denitrification is responsible for 87-99% of the total N(2) production. The dominance of denitrification is reproducible using two independent isotope incubation methods. In contrast, anammox is dominant in the Eastern Tropical South Pacific OMZ, as detected using one of the isotope incubation methods, as previously reported. The abundance of denitrifying bacteria always exceeded that of anammox bacteria by up to 7- and 19-fold in the Eastern Tropical South Pacific and Arabian Sea, respectively. Geographic and temporal variability in carbon supply may be responsible for the different contributions of denitrification and anammox in these two OMZs. The large contribution of denitrification to N(2) loss in the Arabian Sea indicates the global significance of denitrification to the oceanic nitrogen budget. PMID:19727197

  15. Denitrification as the dominant nitrogen loss process in the Arabian Sea.

    PubMed

    Ward, B B; Devol, A H; Rich, J J; Chang, B X; Bulow, S E; Naik, Hema; Pratihary, Anil; Jayakumar, A

    2009-09-01

    Primary production in over half of the world's oceans is limited by fixed nitrogen availability. The main loss term from the fixed nitrogen inventory is the production of dinitrogen gas (N(2)) by heterotrophic denitrification or the more recently discovered autotrophic process, anaerobic ammonia oxidation (anammox). Oceanic oxygen minimum zones (OMZ) are responsible for about 35% of oceanic N(2) production and up to half of that occurs in the Arabian Sea. Although denitrification was long thought to be the only loss term, it has recently been argued that anammox alone is responsible for fixed nitrogen loss in the OMZs. Here we measure denitrification and anammox rates and quantify the abundance of denitrifying and anammox bacteria in the OMZ regions of the Eastern Tropical South Pacific and the Arabian Sea. We find that denitrification rather than anammox dominates the N(2) loss term in the Arabian Sea, the largest and most intense OMZ in the world ocean. In seven of eight experiments in the Arabian Sea denitrification is responsible for 87-99% of the total N(2) production. The dominance of denitrification is reproducible using two independent isotope incubation methods. In contrast, anammox is dominant in the Eastern Tropical South Pacific OMZ, as detected using one of the isotope incubation methods, as previously reported. The abundance of denitrifying bacteria always exceeded that of anammox bacteria by up to 7- and 19-fold in the Eastern Tropical South Pacific and Arabian Sea, respectively. Geographic and temporal variability in carbon supply may be responsible for the different contributions of denitrification and anammox in these two OMZs. The large contribution of denitrification to N(2) loss in the Arabian Sea indicates the global significance of denitrification to the oceanic nitrogen budget.

  16. Detection and monitoring of super sandstorm and its impacts on Arabian Sea-Remote sensing approach

    NASA Astrophysics Data System (ADS)

    Kunte, Pravin D.; M. A., Aswini

    2015-06-01

    The present study addresses an intense sandstorm event over the Persian Gulf and its transport over the Arabian Sea region and the Indian sub-continent using satellite observations and measurements. MODIS data are used to analyze the temporal variation of the dust events that occurred from 17 to 24 March 2012 with the strongest intensity on 20 March over the Arabian Sea. MODIS images are examined to provide an independent assessment of dust presence and plume location and its migration over the Arabian Sea to the Indian sub-continent. Dust enhancement and dust detection procedure is attempted to demarcate the dust event. Dust source, formation, transportation path, and dissipation is studied using source-back-tracking, surface wind, and surface pressure, wind speed and direction, geo-potential height for different pressure level, and remote sensing methods. Finally, an attempt is made to investigate the impact of super sandstorm on the Arabian Sea by studying sea surface temperature and chlorophyll a variability during the events. It is noted that sea surface temperature is decreased and chlorophyll a concentration increased during the post-event period. The present study demonstrates the use of remote sensing data and geospatial techniques in detecting and mapping of dust events and monitoring dust transport along specific regional transport pathways over land and ocean.

  17. Past, present, and future changes in marine biogeochemistry in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Six, Katharina; Segschneider, Joachim

    2014-05-01

    The work presented here aims at a better understanding of the Asian Monsoon system including the marine biogeochemistry in the Arabian Sea. Changes in the past as recorded in marine sediments, as simulated over the past 1000 years, and under forcing by anthropogenic CO2 emissions by numerical model simulations are investigated. The investigation is based on three columns: a sediment core taken in the Arabian Sea (core SO130-275KL taken off Pakistan), a pre-industrial model run from 850 - 1850 with the Max Planck Institute's Earth System Model (MPI-ESM) including the marine and terrestrial carbon cycle and forced by solar variations and volcanic eruptions, and a continuation of this simulation to 2005 under the historical anthropogenic CO2 forcing which allows a comparison with present day climatology. In a first step we compare model results for a set of biogeochemical tracers within the water column and the sediment mixed with observations in the Arabian Sea. We further analyse correlations between Monsoon forcing (represented by zonal wind speed at 850 hPA, short wave radiation, Indian summer precipitation) and biogeochemical parameters, with particular focus on denitrification rates and fluxes to the sediment. This analysis is focused on three regions: off Somalia and off Oman for the summer monsoon, and the central Arabian Sea for the winter monsoon. For the summer monsoon, the highest correlation is found between zonal wind speed and calcite flux to the sediment off Somalia, for the winter monsoon the correlation is highest for short wave radiation in the central Arabian Sea. Time series of mixed layer depth and integrated primary production within the upper 100 m of the ocean from a CMIP5 historical experiment (1850-2005) show, at the location of the sediment core SO130-275KL, little correlation during the summer monsoon, but good correlation during the winter monsoon. As a result, the sediment core is more likely to document winter monsoon conditions

  18. Estimation of Phytoplankton Responses to Hurricane Gonu over the Arabian Sea Based on Ocean Color Data

    PubMed Central

    Wang, Dongxiao; Zhao, Hui

    2008-01-01

    In this study the authors investigated phytoplankton variations in the Arabian Sea associated with Hurricane Gonu using remote-sensing data of chlorophyll-a (Chl-a), sea surface temperature (SST) and winds. Additional data sets used for the study included the hurricane and Conductivity-Temperature-Depth data. Hurricane Gonu, presenting extremely powerful wind intensity, originated over the central Arabian Sea (near 67.7°E, 15.1°N) on June 2, 2007; it traveled along a northwestward direction and made landfall in Iran around June 7. Before Hurricane Gonu, Chl-a data indicated relatively low phytoplankton biomass (0.05-0.2 mg m-3), along with generally high SST (>28.5 °C) and weak wind (<10 m s-1) in the Arabian Sea. Shortly after Gonu's passage, two phytoplankton blooms were observed northeast of Oman (Chl-a of 3.5 mg m-3) and in the eastern central Arabian Sea (Chl-a of 0.4 mg m-3), with up to 10-fold increase in surface Chl-a concentrations, respectively. The Chl-a in the two post-hurricane blooms were 46% and 42% larger than those in June of other years, respectively. The two blooms may be attributed to the storm-induced nutrient uptake, since hurricane can influence intensively both dynamical and biological processes through vertical mixing and Ekman Pumping.

  19. Sea level rise within the west of Arabian Gulf using tide gauge and continuous GPS measurements

    NASA Astrophysics Data System (ADS)

    Ayhan, M. E.; Alothman, A.

    2009-04-01

    Arabian Gulf is connected to Indian Ocean and located in the south-west of the Zagros Trust Belt. To investigate sea level variations within the west of Arabian Gulf, monthly means of sea level at 13 tide gauges along the coast of Saudi Arabia and Bahrain, available in the database of the Permanent Service for Mean Sea Level (PSMSL), are studied. We analyzed individually the monthly means at each station, and estimated secular sea level rate by a robust linear trend fitting. We computed the average relative sea level rise rate of 1.96 ± 0.21 mm/yr within the west of Arabian Gulf based on 4 stations spanning longer than 19 years. Vertical land motions are included into the relative sea level measurements at the tide gauges. Therefore sea level rates at the stations are corrected for vertical land motions using the ICE-5G v1.2 VM4 Glacial Isostatic Adjustment (GIA) model then we found the average sea level rise rate of 2.27 mm/yr. Bahrain International GPS Service (IGS) GPS station, which is close to the Mina Sulman tide gauge station in Bahrain, is the only continuous GPS station accessible in the region. The weekly GPS time series of vertical component at Bahrain IGS-GPS station referring to the ITRF97 from 1999.2 to 2008.6 are downloaded from http://www-gps.mit.edu/~tah/. We fitted a linear trend with an annual signal and one break to the GPS vertical time series and found a vertical land motion rate of 0.48 ± 0.11 mm/yr. Assuming the vertical rate at Bahrain IGS-GPS station represents the vertical rate at each of the other tide gauge stations studied here in the region, we computed average sea level rise rate of 2.44 ± 0.21 mm/yr within the west of Arabian Gulf.

  20. Observational study of upper ocean cooling due to Phet super cyclone in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Muni Krishna, K.

    2016-05-01

    Phet super cyclone (31 May-7 June 2010) was the most intense and also the rarest of the rare track in Arabian Sea as per the recorded history during 1877-2009. The present study focuses on the ocean physical responses to Phet cyclone using satellite and Argo observations. The sea surface temperature is decreased to 6 °C with an approximately 350 km long and 100 km width area in the Arabian Sea after the cyclone passage. The translation speed of cyclone is 3.86 m/s, the mixed layer is 79 m, and thermocline displacement is 13 m at the cooling area. With the relationship of wind stress curl and Ekman pumping velocity (EPV), the author found that the speed of EPV was increased after the passage of cyclone. So the extent of the SST drop was probably due to the moving speed of cyclone and the depth of the mixed layer.

  1. Physical and biological response of the Arabian Sea to tropical cyclone Phyan and its implications.

    PubMed

    Byju, P; Prasanna Kumar, S

    2011-06-01

    The response to the tropical cyclone Phyan, which developed in the eastern Arabian Sea during 9-11 November 2009, was rapid cooling of sea surface temperature (SST), enhancement of chlorophyll a and two-fold increase in net primary productivity (NPP). Cooling of SST was immediate in response to the strong wind-mixing, and the subsequent upward Ekman pumping sustained the cooling even after the dissipation of Phyan. The biological response mediated by the upward Ekman pumping driven vertical transport of subsurface nutrient showed a time lag of 3-4 days. The CO₂ flux to the atmosphere associated with Phyan was 0.123 Tg C, which accounted for ~85% of the total out-gassing from the eastern Arabian Sea during November. Thus, an increased occurrence of cyclones in a warming environment will lead to an enhanced biomass production and also increase in CO₂ out-gassing.

  2. Origin and fate of the secondary nitrite maximum in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Lam, P.; Jensen, M. M.; Kock, A.; Lettmann, K. A.; Plancherel, Y.; Lavik, G.; Bange, H. W.; Kuypers, M. M. M.

    2011-06-01

    The Arabian Sea harbours one of the three major oxygen minimum zones (OMZs) in the world's oceans, and it alone is estimated to account for ~10-20 % of global oceanic nitrogen (N) loss. While actual rate measurements have been few, the consistently high accumulation of nitrite (NO2-) coinciding with suboxic conditions in the central-northeastern part of the Arabian Sea has led to the general belief that this is the region where active N-loss takes place. Most subsequent field studies on N-loss have thus been drawn almost exclusively to the central-NE. However, a recent study measured only low to undetectable N-loss activities in this region, compared to orders of magnitude higher rates measured towards the Omani Shelf where little NO2- accumulated (Jensen et al., 2011). In this paper, we further explore this discrepancy by comparing the NO2--producing and consuming processes, and examining the relationship between the overall NO2- balance and active N-loss in the Arabian Sea. Based on a combination of 15N-incubation experiments, functional gene expression analyses, nutrient profiling and flux modeling, our results showed that NO2- accumulated in the central-NE Arabian Sea due to a net production via primarily active nitrate (NO3-) reduction and to a certain extent ammonia oxidation. Meanwhile, NO2- consumption via anammox, denitrification and dissimilatory nitrate/nitrite reduction to ammonium (NH4+) were hardly detectable in this region, though some loss to NO2- oxidation was predicted from modeled NO3- changes. No significant correlation was found between NO2- and N-loss rates (p>0.05). This discrepancy between NO2- accumulation and lack of active N-loss in the central-NE Arabian Sea is best explained by the deficiency of labile organic matter that is directly needed for further NO2- reduction to N2O, N2 and NH4+, and indirectly for the remineralized NH4+ required by anammox. Altogether, our data do not support the long-held view that NO2- accumulation is a

  3. Origin and fate of the secondary nitrite maximum in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Lam, P.; Jensen, M. M.; Kock, A.; Lettmann, K. A.; Plancherel, Y.; Lavik, G.; Bange, H. W.; Kuypers, M. M. M.

    2011-03-01

    The Arabian Sea harbours one of the three major oxygen minimum zones (OMZs) in the world's oceans, and it alone is estimated to account for ~10-20% of global oceanic nitrogen (N) loss. While actual rate measurements have been few, the consistently high accumulation of nitrite (NO2-) coinciding with suboxic conditions in the central-northeastern part of the Arabian Sea has led to the general belief that this is the region where active N-loss takes place. Most subsequent field studies on N-loss have thus been drawn almost exclusively to the central-NE. However, a recent study measured only low to undetectable N-loss activities in this region, compared to orders of magnitude higher rates measured towards the Omani shelf where little NO2- accumulated (Jensen et al., 2011). In this paper, we further explore this discrepancy by comparing the NO2- producing and consuming processes, and examining the relationship between the overall NO2- balance and active N-loss in the Arabian Sea. Based on a combination of 15N-incubation experiments, functional gene expression analyses, nutrient profiling and flux modeling, our results showed that NO2- accumulated in the Central-NE Arabian Sea due to a net production via primarily active nitrate (NO3-) reduction and to a certain extent ammonia oxidation. Meanwhile, NO2- consumption via anammox, denitrification and dissimilatory nitrate/nitrite reduction to ammonium (NH4+) were hardly detectable in this region, though some loss to NO2- oxidation was predicted from modeled NO3- changes. No significant correlation was found between NO2- and N-loss rates (p>0.05). This discrepancy between NO2- accumulation and lack of active N-loss in the Central-NE Arabian Sea is best explained by the deficiency of organic matter that is directly needed for further NO2- reduction to N2O, N2 and NH4+, and indirectly for the remineralized NH4+ required by anammox. Altogether, our data do not support the long-held view that NO2- accumulation is a direct

  4. Environmental studies of the Arabian Sea using remote sensing and GIS

    NASA Astrophysics Data System (ADS)

    Saxena, Ashlesha; Menezes, Andrew

    2006-12-01

    The Arabian Sea, situated in the western part of the northern Indian Ocean is a tropical basin. It is bounded on the east by the Indian peninsula, on the north by Baluchistan and Sindh provinces of Pakistan and on the west by the landmass of Arabia and Africa. The environmental factors that influence this tropical basin are the seasonally changing winds from the northeast during winter (November-February) and southwest during summer (June to September). Accordingly, the waters of the basin will experience seasonal variations. The study aims at understanding the seasonal and inter-annual variation of the Arabian Sea using satellite-derived data. The spatial domain selected for the present study is 40 degrees E and 78 degrees E longitude and equator to 30 degrees N. The remote sensing data with respect to sea surface temperature (SST), sea surface wind, sea surface height (SSH), and chlorophyll pigment concentration during January 2002 to December 2005 were used to understand the spatio-temporal variability of the Arabian Sea. The monthly mean SST data was obtained from Modis aqua, winds from Quikscat and chlorophyll pigment concentration from SeaWiFS. The SSH anomaly data was obtained from the merged product - Topex/Poseidon ERS 1/2 satellite which is 7-day snapshot. The spatial resolution of these data is 0.3 degrees latitude x 0.3 degrees longitude. Geographical information system (GIS) was used for processing and analysing the above parameters to determine the variability and detection of oceanic processes that are responsible for such variability.The study showed a very strong inverse correlation between SST and chlorophyll concentrations. Arabian Sea undergoes cooling during summer due to upwelling and advection, and in winter due to surface cooling under reduced solar heating. Upwelling along the coasts of Somalia, Arabia, and the west coast of India brings cold and nutrient rich sub-surface waters to the surface, which supports the observed high chlorophyll

  5. Biomass of zooplankton estimated by acoustical sensors in the Arabian sea. Final report

    SciTech Connect

    Holliday, D.V.

    1996-11-22

    The long term goal of our overall research program is the development of data-based models to predict ecological relationships of zooplankton, phytoplankton and the physical environment in the sea. The overall objective of the work carried out within the scope of this particular contract was to acoustically measure the dynamics of zooplankton and micronekton in the northern Arabian Sea during several seasons. The scientific focus was to examine the impact, if any, of the two annual monsoons that are thought to drive the ecosystem response in the area. This particular project involved the design and construction of two sensors which were then deployed in the Arabian Sea by several of our co-PIVs in the ONR ARI on Forced Upper Ocean Dynamics during the time period in which the JGOFS program also focused their efforts on the northern Arabian Sea. This contract involved only the development, calibration and maintenance of the instrumentation. The data processing, other than that which has been necessary for the purposes of quality assurance, was not induded in our original proposal.

  6. Hydrography and biogeochemistry of the north western Bay of Bengal and the north eastern Arabian Sea during winter monsoon

    NASA Astrophysics Data System (ADS)

    Balachandran, K. K.; Laluraj, C. M.; Jyothibabu, R.; Madhu, N. V.; Muraleedharan, K. R.; Vijay, J. G.; Maheswaran, P. A.; Ashraff, T. T. M.; Nair, K. K. C.; Achuthankutty, C. T.

    2008-09-01

    The north eastern Arabian Sea and the north western Bay of Bengal within the Indian exclusive economic zone were explored for their environmental characteristics during the winter monsoons of 2000 and 2001 respectively. The two regions were found to respond paradoxically to comparable intensities of the atmospheric forcing. There is an asymmetry in the net heat exchange of these two basins with atmosphere because of the varying thickness of barrier layer. During winter, the convective mixing in the Arabian Sea is driven by net heat loss from the ocean, whereas the Bay of Bengal does not contribute to such large heat loss to the atmosphere. It appears that the subduction of high saline Arabian Sea water mass is the mechanism behind the formation of a barrier layer in the northeast Arabian Sea; whereas that in the Bay of Bengal and the southeast Arabian Sea are already established as due to low saline water mass. The weak barrier layer in the Arabian Sea yields to the predominance of convective mixing to bring in nitrate-rich waters from the deeper layers to the surface, thereby supporting enhanced biological production. On the other hand, the river discharge into the Bay of Bengal during this period results in the formation of a thick and stable barrier layer, which insulates vertical mixing and provide oligotrophic condition in the Bay.

  7. Benthic foraminifera from the Arabian Sea oxygen minimum zone: towards a paleo-oxygenation proxy.

    NASA Astrophysics Data System (ADS)

    Clemence, Caulle; Meryem, Mojtahid; Karoliina, Koho; Andy, Gooday; Gert-Jan, Reichart; Gerhard, Schmiedl; Frans, Jorissen

    2014-05-01

    Benthic foraminifera from the Arabian Sea oxygen minimum zone: towards a paleo-oxygenation proxy. C. Caulle1, M. Mojtahid1, K. Koho2,3, A. Gooday4, G. J. Reichart2,3, G. Schmiedl5, F. Jorissen1 1UMR CNRS 6112 LPG-BIAF, University of Angers, 2 bd Lavoisier, 49045 Angers Cedex 2Utrecht University, Faculty of Geosciences, Department of Earth Sciences, Budapestlaan 4, 3584 CD Utrecht, The Netherlands 3Royal Netherland Institute for Sea Research (Royal NIOZ), Landsdiep 4, 1797 SZ 't Horntje (Texel) 4Southampton Oceanography Centre, Empress Dock, European Way, Southampton SO14 3ZH, UK 5Department of Geosciences, University of Hamburg, Bundesstraße 55, 20146 Hamburg, Germany The thermohaline circulation oxygenates the deep ocean sediment and therefore enables aerobic life on the sea-floor. In the past, interruption of this deep water formation occurred several times causing hypoxic to anoxic conditions on the sea-floor leading to major ecological turnover. A better understanding of the interaction between climate and bottom water oxygenation is therefore essential in order to predict future oceanic responses. Presently, permanent (stable over decadal timescale) low-oxygen conditions occur naturally at mid-water depths in the northern Indian Ocean (Arabian Sea). Oxygen Minimum Zones (OMZ) are key areas to understand the hypoxic-anoxic events and their impact on the benthic ecosystem. In this context, a good knowledge of the ecology and life cycle adaptations of the benthic foraminiferal assemblages living in these low oxygen areas is essential. A series of multicores were recovered from three transects showing an oxygen gradient across the OMZ: the Murray Ridge, the Oman margin and the Indian margin. The stations located at the same depths showed slightly different oxygen concentrations and large differences in organic matter content. These differences are mainly related to the geographic location in the Arabian Sea. We investigated at these stations live and dead benthic

  8. Late quaternary time series of Arabian Sea productivity: Global and regional signals

    NASA Technical Reports Server (NTRS)

    Clemens, Steven C.; Prell, W. L.; Murray, D. W.

    1992-01-01

    Modern annual floral and faunal production in the northwest Arabian Sea derives primarily from upwelling induced by strong southwest winds during June, July, and August. Indian Ocean summer monsoon winds are, in turn, driven by differential heating between the Asian continent and the Indian ocean to the south. This differential heating produces a strong pressure gradient resulting in southwest monsoon winds and both coastal and divergent upwelling off the Arabian Peninsula. Over geologic time scales (10(exp 4) to 10(exp 6) years), monsoon wind strength is sensitive to changes in boundary conditions which influence this pressure gradient. Important boundary conditions include the seasonal distribution of solar radiation, global ice volume, Indian Ocean sea surface temperature, and the elevation and albedo of the Asian continent. To the extent that these factors influence monsoon wind strength, they also influence upwelling and productivity. In addition, however, productivity associated with upwelling can be decoupled from the strength of the summer monsoon winds via ocean mechanisms which serve to inhibit or enhance the nutrient supply in the intermediate waters of the Indian Ocean, the source for upwelled waters in the Arabian Sea. To differentiate productivity associated with wind-induced upwelling from that associated with other components of the system such as nutrient sequestering in glacial-age deep waters, we employ a strategy which monitors independent components of the oceanic and atmospheric subsystems. Using sediment records from the Owen Ridge, northwest Arabian Sea, we monitor the strength of upwelling and productivity using two independent indicators, percent G. bulloides and opal accumulation. We monitor the strength of southwest monsoon winds by measuring the grain-size of lithogenic dust particles blown into the Arabian Sea from the surrounding deserts of the Somali and Arabian Peninsulas. Our current hypothesis is that the variability associated

  9. Geochemical evidence for anoxic deep water in the Arabian Sea during the last glaciation

    SciTech Connect

    Sarkar, A.; Bhattacharya, S.K.; Sarin, M.M. )

    1993-03-01

    Various paleoceanographic studies have indicated that the deep ocean was probably depleted in dissolved oxygen during the last glacial period ([approximately]18 kyr B.P.; [delta][sup 18]O, stage 2) compared to present time. However, direct evidence of low oxygen content in the deep waters has been lacking. Here, the authors report geochemical evidence of near anoxic conditions in the deep Arabian Sea during the entire last glacial cycle ([delta][sup 18]O; stages 2, 3, and 4). Anoxia is inferred from the concomitant enrichment of organic carbon and authigenic uranium in the glacial sections of a core from the deep eastern Arabian Sea. The anoxic conditions during the last glacial period, probably caused by a change in deep water circulation, evidently enhanced preservation of organic matter and simultaneous removal of uranium from seawater. 57 refs., 3 figs., 2 tabs.

  10. The impact of dust storms on the Arabian Peninsula and the Red Sea

    NASA Astrophysics Data System (ADS)

    Jish Prakash, P.; Stenchikov, G.; Kalenderski, S.; Osipov, S.; Bangalath, H.

    2014-07-01

    Located in the dust belt, the Arabian Peninsula is a major source of atmospheric dust. Frequent dust outbreaks and some 15 to 20 dust storms per year have profound effects on all aspects of human activity and natural processes in this region. To quantify the effect of severe dust events on radiation fluxes and regional climate characteristics, we simulated the storm that occurred on 18-20 March 2012 using a regional weather research forecast model fully coupled with the chemistry/aerosol module (WRF-Chem). This storm swept over a remarkably large area affecting the entire Middle East, North-Eastern Africa, Afghanistan and Pakistan. It was caused by a southward propagating cold front and associated winds activated the dust production in river valleys of the lower Tigris and Euphrates in Iraq, the coastal areas in Kuwait, Iran, and the United Arab Emirates, Rub al Khali, An Nafud and Ad Dahna deserts, and along the Red Sea coast on the west side of the Arabian Peninsula. Our simulation results compare well with available ground-based and satellite observations. The total amount of dust generated by the storm reached 93.76 Mt. About 80% of this amount deposited within the calculation domain. The Arabian Sea and Persian Gulf received 5.3 Mt, and the Red Sea 1.2 Mt. Dust particles bring nutrients to marine ecosystems, which is especially important for the oligothrophic Northern Red Sea. However, their contribution to the nutrient balance in the Red Sea remains largely unknown. By scaling the effect of one storm to the number of dust storms observed annually over the Red Sea, we roughly estimate the annual dust deposition to the Red Sea to be 6 Mt.

  11. The impact of dust storms on the Arabian Peninsula and the Red Sea

    NASA Astrophysics Data System (ADS)

    Jish Prakash, P.; Stenchikov, G.; Kalenderski, S.; Osipov, S.; Bangalath, H.

    2015-01-01

    Located in the dust belt, the Arabian Peninsula is a major source of atmospheric dust. Frequent dust outbreaks and some 15 to 20 dust storms per year have profound effects on all aspects of human activity and natural processes in this region. To quantify the effect of severe dust events on radiation fluxes and regional climate characteristics, we simulated the storm that occurred from 18 to 20 March 2012 using a regional weather research forecast model fully coupled with the chemistry/aerosol module (WRF-Chem). This storm swept over a remarkably large area affecting the entire Middle East, northeastern Africa, Afghanistan, and Pakistan. It was caused by a southward propagating cold front, and the associated winds activated the dust production in river valleys of the lower Tigris and Euphrates in Iraq; the coastal areas in Kuwait, Iran, and the United Arab Emirates; the Rub al Khali, An Nafud, and Ad Dahna deserts; and along the Red Sea coast on the west side of the Arabian Peninsula. Our simulation results compare well with available ground-based and satellite observations. We estimate the total amount of dust generated by the storm to have reached 94 Mt. Approximately 78% of this dust was deposited within the calculation domain. The Arabian Sea and Persian Gulf received 5.3 Mt and the Red Sea 1.2 Mt of dust. Dust particles bring nutrients to marine ecosystems, which is especially important for the oligotrophic Northern Red Sea. However, their contribution to the nutrient balance in the Red Sea remains largely unknown. By scaling the effect of one storm to the number of dust storms observed annually over the Red Sea, we estimate the annual dust deposition to the Red Sea, associated with major dust storms, to be 6 Mt.

  12. Metagenomic analysis of nitrogen and methane cycling in the Arabian Sea oxygen minimum zone.

    PubMed

    Lüke, Claudia; Speth, Daan R; Kox, Martine A R; Villanueva, Laura; Jetten, Mike S M

    2016-01-01

    Oxygen minimum zones (OMZ) are areas in the global ocean where oxygen concentrations drop to below one percent. Low oxygen concentrations allow alternative respiration with nitrate and nitrite as electron acceptor to become prevalent in these areas, making them main contributors to oceanic nitrogen loss. The contribution of anammox and denitrification to nitrogen loss seems to vary in different OMZs. In the Arabian Sea, both processes were reported. Here, we performed a metagenomics study of the upper and core zone of the Arabian Sea OMZ, to provide a comprehensive overview of the genetic potential for nitrogen and methane cycling. We propose that aerobic ammonium oxidation is carried out by a diverse community of Thaumarchaeota in the upper zone of the OMZ, whereas a low diversity of Scalindua-like anammox bacteria contribute significantly to nitrogen loss in the core zone. Aerobic nitrite oxidation in the OMZ seems to be performed by Nitrospina spp. and a novel lineage of nitrite oxidizing organisms that is present in roughly equal abundance as Nitrospina. Dissimilatory nitrate reduction to ammonia (DNRA) can be carried out by yet unknown microorganisms harbouring a divergent nrfA gene. The metagenomes do not provide conclusive evidence for active methane cycling; however, a low abundance of novel alkane monooxygenase diversity was detected. Taken together, our approach confirmed the genomic potential for an active nitrogen cycle in the Arabian Sea and allowed detection of hitherto overlooked lineages of carbon and nitrogen cycle bacteria.

  13. The world's most isolated and distinct whale population? Humpback whales of the Arabian Sea.

    PubMed

    Pomilla, Cristina; Amaral, Ana R; Collins, Tim; Minton, Gianna; Findlay, Ken; Leslie, Matthew S; Ponnampalam, Louisa; Baldwin, Robert; Rosenbaum, Howard

    2014-01-01

    A clear understanding of population structure is essential for assessing conservation status and implementing management strategies. A small, non-migratory population of humpback whales in the Arabian Sea is classified as "Endangered" on the IUCN Red List of Threatened Species, an assessment constrained by a lack of data, including limited understanding of its relationship to other populations. We analysed 11 microsatellite markers and mitochondrial DNA sequences extracted from 67 Arabian Sea humpback whale tissue samples and compared them to equivalent datasets from the Southern Hemisphere and North Pacific. Results show that the Arabian Sea population is highly distinct; estimates of gene flow and divergence times suggest a Southern Indian Ocean origin but indicate that it has been isolated for approximately 70,000 years, remarkable for a species that is typically highly migratory. Genetic diversity values are significantly lower than those obtained for Southern Hemisphere populations and signatures of ancient and recent genetic bottlenecks were identified. Our findings suggest this is the world's most isolated humpback whale population, which, when combined with low population abundance estimates and anthropogenic threats, raises concern for its survival. We recommend an amendment of the status of the population to "Critically Endangered" on the IUCN Red List.

  14. Metagenomic analysis of nitrogen and methane cycling in the Arabian Sea oxygen minimum zone

    PubMed Central

    Kox, Martine A.R.; Villanueva, Laura; Jetten, Mike S.M.

    2016-01-01

    Oxygen minimum zones (OMZ) are areas in the global ocean where oxygen concentrations drop to below one percent. Low oxygen concentrations allow alternative respiration with nitrate and nitrite as electron acceptor to become prevalent in these areas, making them main contributors to oceanic nitrogen loss. The contribution of anammox and denitrification to nitrogen loss seems to vary in different OMZs. In the Arabian Sea, both processes were reported. Here, we performed a metagenomics study of the upper and core zone of the Arabian Sea OMZ, to provide a comprehensive overview of the genetic potential for nitrogen and methane cycling. We propose that aerobic ammonium oxidation is carried out by a diverse community of Thaumarchaeota in the upper zone of the OMZ, whereas a low diversity of Scalindua-like anammox bacteria contribute significantly to nitrogen loss in the core zone. Aerobic nitrite oxidation in the OMZ seems to be performed by Nitrospina spp. and a novel lineage of nitrite oxidizing organisms that is present in roughly equal abundance as Nitrospina. Dissimilatory nitrate reduction to ammonia (DNRA) can be carried out by yet unknown microorganisms harbouring a divergent nrfA gene. The metagenomes do not provide conclusive evidence for active methane cycling; however, a low abundance of novel alkane monooxygenase diversity was detected. Taken together, our approach confirmed the genomic potential for an active nitrogen cycle in the Arabian Sea and allowed detection of hitherto overlooked lineages of carbon and nitrogen cycle bacteria. PMID:27077014

  15. The World's Most Isolated and Distinct Whale Population? Humpback Whales of the Arabian Sea

    PubMed Central

    Collins, Tim; Minton, Gianna; Findlay, Ken; Leslie, Matthew S.; Ponnampalam, Louisa; Baldwin, Robert; Rosenbaum, Howard

    2014-01-01

    A clear understanding of population structure is essential for assessing conservation status and implementing management strategies. A small, non-migratory population of humpback whales in the Arabian Sea is classified as “Endangered” on the IUCN Red List of Threatened Species, an assessment constrained by a lack of data, including limited understanding of its relationship to other populations. We analysed 11 microsatellite markers and mitochondrial DNA sequences extracted from 67 Arabian Sea humpback whale tissue samples and compared them to equivalent datasets from the Southern Hemisphere and North Pacific. Results show that the Arabian Sea population is highly distinct; estimates of gene flow and divergence times suggest a Southern Indian Ocean origin but indicate that it has been isolated for approximately 70,000 years, remarkable for a species that is typically highly migratory. Genetic diversity values are significantly lower than those obtained for Southern Hemisphere populations and signatures of ancient and recent genetic bottlenecks were identified. Our findings suggest this is the world's most isolated humpback whale population, which, when combined with low population abundance estimates and anthropogenic threats, raises concern for its survival. We recommend an amendment of the status of the population to “Critically Endangered” on the IUCN Red List. PMID:25470144

  16. Metagenomic analysis of nitrogen and methane cycling in the Arabian Sea oxygen minimum zone.

    PubMed

    Lüke, Claudia; Speth, Daan R; Kox, Martine A R; Villanueva, Laura; Jetten, Mike S M

    2016-01-01

    Oxygen minimum zones (OMZ) are areas in the global ocean where oxygen concentrations drop to below one percent. Low oxygen concentrations allow alternative respiration with nitrate and nitrite as electron acceptor to become prevalent in these areas, making them main contributors to oceanic nitrogen loss. The contribution of anammox and denitrification to nitrogen loss seems to vary in different OMZs. In the Arabian Sea, both processes were reported. Here, we performed a metagenomics study of the upper and core zone of the Arabian Sea OMZ, to provide a comprehensive overview of the genetic potential for nitrogen and methane cycling. We propose that aerobic ammonium oxidation is carried out by a diverse community of Thaumarchaeota in the upper zone of the OMZ, whereas a low diversity of Scalindua-like anammox bacteria contribute significantly to nitrogen loss in the core zone. Aerobic nitrite oxidation in the OMZ seems to be performed by Nitrospina spp. and a novel lineage of nitrite oxidizing organisms that is present in roughly equal abundance as Nitrospina. Dissimilatory nitrate reduction to ammonia (DNRA) can be carried out by yet unknown microorganisms harbouring a divergent nrfA gene. The metagenomes do not provide conclusive evidence for active methane cycling; however, a low abundance of novel alkane monooxygenase diversity was detected. Taken together, our approach confirmed the genomic potential for an active nitrogen cycle in the Arabian Sea and allowed detection of hitherto overlooked lineages of carbon and nitrogen cycle bacteria. PMID:27077014

  17. The world's most isolated and distinct whale population? Humpback whales of the Arabian Sea.

    PubMed

    Pomilla, Cristina; Amaral, Ana R; Collins, Tim; Minton, Gianna; Findlay, Ken; Leslie, Matthew S; Ponnampalam, Louisa; Baldwin, Robert; Rosenbaum, Howard

    2014-01-01

    A clear understanding of population structure is essential for assessing conservation status and implementing management strategies. A small, non-migratory population of humpback whales in the Arabian Sea is classified as "Endangered" on the IUCN Red List of Threatened Species, an assessment constrained by a lack of data, including limited understanding of its relationship to other populations. We analysed 11 microsatellite markers and mitochondrial DNA sequences extracted from 67 Arabian Sea humpback whale tissue samples and compared them to equivalent datasets from the Southern Hemisphere and North Pacific. Results show that the Arabian Sea population is highly distinct; estimates of gene flow and divergence times suggest a Southern Indian Ocean origin but indicate that it has been isolated for approximately 70,000 years, remarkable for a species that is typically highly migratory. Genetic diversity values are significantly lower than those obtained for Southern Hemisphere populations and signatures of ancient and recent genetic bottlenecks were identified. Our findings suggest this is the world's most isolated humpback whale population, which, when combined with low population abundance estimates and anthropogenic threats, raises concern for its survival. We recommend an amendment of the status of the population to "Critically Endangered" on the IUCN Red List. PMID:25470144

  18. Bio-Optical Properties of the Arabian Sea as Determined by In-Situ and SeaWifs Data

    NASA Technical Reports Server (NTRS)

    Trees, Charles C.

    1998-01-01

    The overall objective of this work was to characterize optical and fluorescence properties in the euphotic zone during two British Ocean Flux Study (BOFS) Arabian Sea cruises. This was later expanded in 1995 to include three U.S. Joint Global Ocean Flux Study (JGOFS) Arabian Sea Cruises. The region was to be divided into one or more "bio-optical provinces", within each of which a single set of regression models was to be developed to relate the vertical distribution of irradiance attenuation and normalized fluorescence (SF and NF) to remote sensing reflectance and diffuse attenuation coefficient [K(490)]. The working hypothesis was that over relatively large spatial and temporal scales, the vertical profiles of bio-optical properties were predictable.

  19. Study of aerosol transport through precipitation chemistry over Arabian Sea during winter and summer monsoons

    NASA Astrophysics Data System (ADS)

    Praveen, P. S.; Rao, P. S. P.; Safai, P. D.; Devara, P. C. S.; Chate, D. M.; Ali, K.; Momin, G. A.

    Precipitation samples over the Arabian Sea collected during Arabian Sea Monsoon Experiment (ARMEX) in 2002-2003 were examined for major water soluble components and acidity of aerosols during the period of winter and summer monsoon seasons. The pH of rain water was alkaline during summer monsoon and acidic during winter monsoon. Summer monsoon precipitation showed dominance of sea-salt components (˜90%) and significant amounts of non-sea salt (nss) Ca 2+ and SO 42-. Winter monsoon precipitation samples showed higher concentration of NO 3- and NH 4+ compared to that of summer monsoon, indicating more influence of anthropogenic sources. The rain water data is interpreted in terms of long-range transport and background pollution. In summer monsoon, air masses passing over the north African and Gulf continents which may be carrying nss components are advected towards the observational location. Also, prevailing strong southwesterly winds at surface level produced sea-salt aerosols which led to high sea-salt contribution in precipitation. While in winter monsoon, it was observed that, air masses coming from Asian region towards observational location carry more pollutants like NO 3-and nss SO 42- that acidify the precipitation.

  20. Monsoon control on faunal composition of planktic foraminifera in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Munz, P.; Siccha, M.; Kucera, M.; Schulz, H.

    2013-12-01

    Being among the most productive open ocean basins, sea surface properties in the Arabian Sea are highly influenced by the seasonal reversal of the monsoonal wind system. During boreal summer wind direction from the southwest induces strong upwelling along the coast off Somalia and Oman. Vertical transport of cold and nutrient-rich deep-water masses by Ekman pumping reduces sea surface temperature and triggers primary productivity. Reversed cold and dry winds during boreal winter lead to cooling of the surface- and subsurface-waters and hereby to deep convective mixing, bringing nutrients into the photic zone and enhancing primary productivity especially in the northern part of the Arabian Sea. Here, we study the influence of the different seasonal monsoon systems on the faunal composition of planktic foraminifera, in order to improve our understanding how the faunal community record is influenced by the respective monsoon systems and to provide baseline information for the reconstruction of ancient monsoon conditions. We used published core-top foraminiferal databases, significantly increased in spatial coverage by new contributions. The resulting combined database consists of 413 core-top samples spanning the Arabian Sea and the Northern Indian Ocean to 10° S. The seasonal sea surface properties at these stations could be binned into categories of different monsoon influence, based on satellite-derived chlorophyll-a concentrations. Interpretation of species response to environmental control is based on multivariate statistical analyses of each of the categorical bins. First results show that samples influenced only by winter- and summer monsoon conditions, respectively, feature specifiable faunal composition. Globigerina bulloides is mostly associated with summer upwelling conditions, whereas Globigerina falconensis and Pulleniatina obliquiloculata are typical species of winter conditions. Redundancy analysis reveals preferences of species populations with

  1. Physical processes affecting availability of dissolved silicate for diatom production in the Arabian Sea

    NASA Technical Reports Server (NTRS)

    Young, David K.; Kindle, John C.

    1994-01-01

    A passive tracer to represent dissolved silicate concentrations, with biologically realistic uptake kinetics, is successfully incorporated into a three-dimensional, eddy-resolving, ocean circulation model of the Indian Ocean. Hypotheses are tested to evaluate physical processes which potentially affect the availability of silicate for diatom production in the Arabian Sea. An alternative mechanism is offered to the idea that open ocean upwelling is primarily responsible for the high, vertical nutrient flux and consequent large-scale phytoplankton bloom in the northwestern Arabian Sea during the southwest monsoon. Model results show that dissolved silicate in surface waters available for uptake by diatoms is primarily influenced by the intensity of nearshore upwelling from soutwest monsoonal wind forcing and by the offshore advective transport of surface waters. The upwelling, which in the model occurs within 200 +/- 50 km of the coast, appears to be a result of a combination of coastal upwelling, Elkman pumping, and divergence of the coastal flow as it turns offshore. Localized intensifications of silicate concentrations appear to be hydrodynamically driven and geographically correlated to coastal topographic features. The absence of diatoms in sediments of the eastern Arabian Basin is consistent with modeled distributional patterns of dissolved silicate resulting from limited westward advection of upwelled coastal waters from the western continental margin of India and rapid uptake of available silicate by diatoms. Concentrations of modeled silicate become sufficiently low to become unavailable for diatom production in the eastern Arabian Sea, a region between 61 deg E and 70 deg E at 8 deg N on the south, with the east and west boundaries converging on the north at approximately 67 deg E, 20 deg N.

  2. Spacebased Observations of the Oceanic Responses to Monsoons in South China Sea and Arabian Sea

    NASA Technical Reports Server (NTRS)

    Xie, Xiao-Su; Liu, W. Timothy

    2000-01-01

    A large percentage of the world's population and their agrarian economy must endure the vagaries of the monsoons over the tropical oceans between Africa and the Philippines. We know very little about the oceanic responses to changes of the monsoon in the South China Sea (SCS), which is under the influence of the East Asian Monsoon System, and the Arabian Sea (AS), which is dominated by the Indian Monsoon System; oceanic observations are sparse in both regions. Data from spaceborne microwave scatterometers and radiometers have been used to estimate the two major atmospheric forcing, momentum flux and latent heat flux (LHF), which change with the monsoon winds. Spaceborne sensors also observed the surface signatures of the oceanic response: SST and sea level changes (SLC. Sufficient durations of these data have recently become available to allow the meaningful studies of the annual cycles and interannual anomalies. In SCS, the winter monsoon is strong and steady but the summer monsoon is weak and has large intraseasonal fluctuations. In AS, the summer monsoon is much stronger than the winter monsoon. Significant correlations between LHF and SST tendency, and between curl of wind stress and SLC are found in both oceans. In the north SCS, winds are strong and dry, LHF is high, and ocean cooling is also large in fall; LHF is low and the ocean warms up in spring. In AS, LHF and SST tendency have a semi annual period; LHF is high in summer when the wind is strong and in winter when the wind is dry. Along the coast of Oman, the strong summer southwest monsoon causes intense upwelling, low SST and LHF in summer; such wind-driven SST changes is not as obvious along the Vietnam coast because of the weaker summer monsoon. The negative correlation between curl of wind stress and SLC found in the central basins of both SCS and AS agrees with a simple Ekman pumping scenario. Cyclonic winds drive surface divergence and upwelling in the ocean; the rise of the thermocline causes

  3. An overview of historical harmful algae blooms outbreaks in the Arabian Seas.

    PubMed

    Al Shehhi, Maryam R; Gherboudj, Imen; Ghedira, Hosni

    2014-09-15

    Harmful algae blooms (HABs), often composed of oceanic plants called phytoplankton, are potentially harmful to the marine life, water quality, human health, and desalination plants, a chief source of potable water in the Arabian Gulf. The last decade has seen a noticeable increase in the frequency of HAB outbreaks in the Arabian Seas. This increase is mainly caused by the unprecedented economic growth in the region. The increased human activities in the region have added more stress to the marine environment and contributed to the changes observed in the properties of the marine ecosystem: high temperature and salinity, high evaporation rates, limited freshwater inflow, shallow nature, pollution. However, very few studies that cover the HAB outbreaks, causes, impacts and biological characteristics over the region have been published. This work presents a comprehensive overview of historical HAB outbreaks recorded in the region, and investigate their causes and impact, and seasonal variability.

  4. Magmatic history of Red Sea rifting: perspective from the central Saudi Arabian coastal plain.

    USGS Publications Warehouse

    Pallister, J.S.

    1987-01-01

    An early stage of magmatism related to Red Sea rifting is recorded by a Tertiary dyke complex and comagmatic volcanic rocks exposed on the central Saudi Arabian coastal plain. Field relations and new K/Ar dates indicate episodic magmatism from approx 30 m.y. to the present day and rift-related magmatism as early as 50 m.y. Localized volcanism and sheeted dyke injection ceased at approx 20 m.y. and were replaced by the intrusion of thick gabbro dykes, marking the onset of sea-floor spreading in the central Red Sea. Differences in the depths and dynamics of mantle-melt extraction and transport may account for the transition from mixed alkaline-subalkaline bimodal magmatism of the pre-20 m.y. rift basin to exclusively subalkaline (tholeiitic) magmatism of the Red Sea spreading axis and the alkali basalt volcanism inland.-L.C.H.

  5. Diversity, distribution, and expression of diazotroph nifH genes in oxygen-deficient waters of the Arabian Sea.

    PubMed

    Jayakumar, Amal; Al-Rshaidat, Mamoon M D; Ward, Bess B; Mulholland, Margaret R

    2012-12-01

    The Arabian Sea oxygen minimum zone (OMZ), the largest suboxic region in the world's oceans, is responsible for up to half of the global mesopelagic fixed nitrogen (N) loss from the ocean via denitrification and anammox. Dinitrogen (N(2)) fixation is usually attributed to cyanobacteria in the surface ocean. Model prediction and physiological inhibition of N(2) fixation by oxygen, however, suggest that N(2) fixation should be enhanced near the oxygen-deficient zone (ODZ) of the Arabian Sea. N(2) fixation and cyanobacterial nifH genes (the gene encoding dinitrogenase reductase) have been reported in surface waters overlying the Arabian Sea ODZ. Here, water samples from depths above and within the Arabian Sea ODZ were examined to explore the distribution, diversity, and expression of nifH genes. In surface waters, nifH DNA and cDNA sequences related to Trichodesmium, a diazotroph known to occur and fix N(2) in the Arabian Sea, were detected. Proteobacterial nifH phylotypes (DNA but not cDNA) were also detected in surface waters. Proteobacterial nifH DNA and cDNA sequences, as well as nifH DNA and cDNA sequences related to strictly anaerobic N -fixers, were obtained from oxygen-deficient depths. This first report of nifH gene expression in subsurface low-oxygen waters suggests that there is potential for active N(2) fixation by several phylogenetically and potentially metabolically diverse microorganisms in pelagic OMZs.

  6. The Northeast Monsoon's Impact on Mixing, Phytoplankton Biomass and Nutrient Cycling in the Arabian Sea

    NASA Technical Reports Server (NTRS)

    Wiggert, J. D.; Jones, B. H.; Dickey, T. D.; Brink, K. H.; Weller, R. A.; Marra, J.; Codispoti, L. A.

    2000-01-01

    In the northern Arabian Sea, atmospheric conditions during the Northeast (winter) Monsoon lead to deep convective mixing. Due to the proximity of the permanent pyncnocline to the sea surface, this mixing does not penetrate below 125 m. However, a strong nitracline is also present and the deep convection results in significant nitrate flux into the surface waters. This leads to nitrate concentrations over the upper 100 m that exceed 4 micrometers toward the end of the Monsoon. During the 1994/1995 US JGOFS/Arabian Sea expedition, the mean areal gross primary production over two successive Northeast Monsoons was determined to be 1.35gC/sq m/d. Thus, despite the deep penetrative convection, high rates of primary productivity were maintained. An interdisciplinary model was developed to elucidate the biogeochemical processes involved in supporting the elevated productivity. This model consists of a 1-D mixed-layer model coupled to a set of equations that tracked phytoplankton growth and the concentration of the two major nutrients (nitrate and ammonium). Zooplankton grazing was parameterized by rate constant determined by shipboard experiments. Model boundary conditions consist of meteorological time-series measured from the surface buoy that was part of the ONR Arabian Sea Experiment's central mooring. Our numerical experiments show that elevated surface evaporation, and the associated salinization of the mixed layer, strongly contributes to the frequency and penetration depth of the observed convective mixing. Cooler surface temperatures, increased nitrate entrainment, reduced water column stratification, and lower near-surface chlorophyll a concentrations all result from this enhanced mixing. The model also captured a dependence on regenerated nitrogen observed in nutrient uptake experiments performed during the Northeast Monsoon. Our numerical experiments also indicate that variability in mean pycnocline depth causes up to a 25% reduction in areal chlorophyll a

  7. Estimates of upwelling rates in the Arabian Sea and the equatorial Indian Ocean based on bomb radiocarbon.

    PubMed

    Bhushan, R; Dutta, K; Somayajulu, B L K

    2008-10-01

    Radiocarbon measurements were made in the water column of the Arabian Sea and the equatorial Indian Ocean during 1994, 1995 and 1997 to assess the temporal variations in bomb 14C distribution and its inventory in the region with respect to GEOSECS measurements made during 1977-1978. Four GEOSECS stations were reoccupied (three in the Arabian Sea and one in the equatorial Indian Ocean) during this study, with all of them showing increased penetration of bomb 14C along with decrease in its surface water activity. The upwelling rates derived by model simulation of bomb 14C depth profile using the calculated exchange rates ranged from 3 to 9 m a(-1). The western region of the Arabian Sea experiencing high wind-induced upwelling has higher estimated upwelling rates. However, lower upwelling rates obtained for the stations occupied during this study could be due to reduced 14C gradient compared to that during GEOSECS.

  8. Carbon cycling in the Mesopelagic Zone of the central Arabian Sea: Results from a simple model

    NASA Astrophysics Data System (ADS)

    Anderson, Thomas R.; Ryabchenko, Vladimir A.

    Using a 3-D hydrodynamic-ecosystem model, Anderson et al. (2007) investigated the carbon budget of the mesopelagic zone of the central Arabian Sea and concluded that the vertical supply of sinking particles from the euphotic zone is sufficient to meet the carbon demand of the mesopelagic biota. Justifying this conclusion, they argued that the predicted rates of bacterial production (BP) and particle export, 1.92 and 6.97 mmol C m-2 d-1, respectively, were consistent with field estimates. Bacteria were, however, assumed to be the sole agents of detritus turnover (DT) in the mesopelagic, their production being calculated from the product of a fixed bacterial growth efficiency (BGE) of 0.27 and DT. A new model of the mesopelagic food web in the central Arabian Sea is presented in which both bacteria and zooplankton act as consumers of detritus and in which BGE is ⩽0.135. The predicted ratio of BP:DT in the mesopelagic zone was 0.10, with bacteria accounting for 82% of total respiration (zooplankton are responsible for the remainder). If the carbon budget of Anderson et al. (2007) is recalculated assuming BP:DT of 0.10 (rather than 0.27), the resulting BP is then only 1.07 mmol C m-2 d-1, less than half the observational estimate of 2.38 mmol C m-2 d-1. The results presented herein therefore reopen the debate as to whether BP in the central Arabian Sea is, at least in part, fueled by external sources of organic matter such as lateral advection from the western basin.

  9. The Effect of the South Asia Monsoon on the Wind Sea and Swell Patterns in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Semedo, Alvaro

    2015-04-01

    Ocean surface gravity waves have a considerable impact on coastal and offshore infrastructures, and are determinant on ship design and routing. But waves also play an important role on the coastal dynamics and beach erosion, and modulate the exchanges of momentum, and mass and other scalars between the atmosphere and the ocean. A constant quantitative and qualitative knowledge of the wave patterns is therefore needed. There are two types of waves at the ocean surface: wind-sea and swell. Wind-sea waves are growing waves under the direct influence of local winds; as these waves propagate away from their generation area, or when their phase speed overcomes the local wind speed, they are called swell. Swell waves can propagate thousands of kilometers across entire ocean basins. The qualitative analysis of ocean surface waves has been the focus of several recent studies, from the wave climate to the air-sea interaction community. The reason for this interest lies mostly in the fact that waves have an impact on the lower atmosphere, and that the air-sea coupling is different depending on the wave regime. Waves modulate the exchange of momentum, heat, and mass across the air-sea interface, and this modulation is different and dependent on the prevalence of one type of waves: wind sea or swell. For fully developed seas the coupling between the ocean-surface and the overlaying atmosphere can be seen as quasi-perfect, in a sense that the momentum transfer and energy dissipation at the ocean surface are in equilibrium. This can only occur in special areas of the Ocean, either in marginal seas, with limited fetch, or in Open Ocean, in areas with strong and persistent wind speed with little or no variation in direction. One of these areas is the Arabian Sea, along the coasts of Somalia, Yemen and Oman. The wind climate in the Arabian sea is under the direct influence of the South Asia monsoon, where the wind blows steady from the northeast during the boreal winter, and

  10. Evaluation of model simulated and MODIS-Aqua retrieved sea surface chlorophyll in the eastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Chakraborty, Kunal; Gupta, Anubhav; Lotliker, Aneesh A.; Tilstone, Gavin

    2016-11-01

    In this study we assess the accuracy of sea surface Chlorophyll-a (Chla) retrieved from satellite (MODIS-Aqua), using standard OC3M algorithm, and from a Regional Ocean Modelling System (ROMS) biophysical model against in situ data, measured in surface waters of the eastern Arabian Sea, from April 2009 to December 2012. MODIS-Aqua OC3M Chla concentrations showed a high correlation with the in situ data with slope close to unity and low root mean square error. In comparison, the ROMS model underestimated Chla, though the correlation was significant indicating that the model is capable of reproducing the trend in in situ Chla. Time Series trends in Chla were examined against wind driven Upwelling Indices (UIW) from April 2009 to December 2012 in north-eastern (Gujarat) and south-eastern (Kochi) coastal waters of the Arabian Sea. The annual peak in Chla along the Kochi coast during the summer monsoon was adequately captured by the model. It is well known that the peak in surface Chla along the Kochi and Gujarat coasts during the summer monsoon is the result of coastal upwelling, which the ROMS model was able to reproduce accurately. The maximum surface Chla along the Gujarat coast during the winter monsoon is due to convective mixing, which was also significantly captured by ROMS biophysical model. There was a lag of approximately one week between the maximum surface Chla and the peak in the Upwelling Index.

  11. The secondary calcification of Neogloboquadrina pachyderma assemblages in Arabian Sea waters and surface sediments

    NASA Astrophysics Data System (ADS)

    Abdolalipour, Samereh; Schulz, Hartmut; Darling, Kate F.

    2014-05-01

    The planktic foraminifer Neogloboquadrina pachyderma (N. pachyderma (sin); Darling et al., 2006) has been recently considered as a (paleo) climatic index in Arabian Sea waters, where increased abundance correlates to the South West monsoon upwelling. Genetic characterization of living specimens collected in multinets off the Oman margin and in the central Arabian Sea indicate the presence of an new genotype of N. pachyderma (Type VIII) (Darling et al., submitted) in the northwestern Indian Ocean. Ecological investigation on these samples reveals that this new genotype, which is the only one to date found in this region, can tolerate warm water temperatures of up to 28° C. It was also found alive below the photic zone within the prominent oxygen minimum zone (OMZ) of the Arabian Sea. To extend our knowledge and understanding of this N. pachyderma Type VIII genotype, we have focused on a morphological analysis of randomly picked specimens (live and dead) from the multinets collected from 200 m down to 700 m water column and from core top sediments distributed over a wide range of water depths (607-3951 m) off the Oman margin in the Arabian Sea. We here use Scanning Electron Microscopy (SEM) to determine the size, shape variation and test wall structure of the penultimate chamber. High resolution measurements confirm the model of chamber growth in non-spinose bilamellar foraminifera of a three or four-layered test wall. As ontogenetic calcite, we were able to visualize the inner lining, the outer layer and the outermost layer formed during the growth of the ultimate chamber. Some of the specimens also showed a fourth layer, which can be attributed to encrustation, observed in higher-latitude specimens of both hemispheres to result from secondary calcification as a terminal step in ontogenetic maturation. To verify the test wall growth and secondary calcification the measurements of the layers were related to the maximum test diameter of the shell. The measurement

  12. Timing, cause and consequences of mid-Holocene climate transition in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Saraswat, Rajeev; Naik, Dinesh Kumar; Nigam, Rajiv; Gaur, Anuruddh Singh

    2016-09-01

    We reconstruct centennial scale quantitative changes in surface seawater temperature (SST), evaporation-precipitation (from Mg/Ca and δ18O of surface dwelling planktic foraminifera), productivity (from relative abundance of Globigerina bulloides), carbon burial (from %CaCO3 and organic carbon [%Corg]) and dissolved oxygen at sediment-water interface, covering the entire Holocene, from a core collected from the eastern Arabian Sea. From the multi-proxy record, we define the timing, consequences and possible causes of the mid-Holocene climate transition (MHCT). A distinct shift in evaporation-precipitation (E-P) is observed at 6.4 ka, accompanied by a net cooling of SST. The shift in SST and E-P is synchronous with a change in surface productivity. A concurrent decrease is also noted in both the planktic foraminiferal abundance and coarse sediment fraction. A shift in carbon burial, as inferred from both the %CaCO3 and %Corg, coincides with a change in surface productivity. A simultaneous decrease in dissolved oxygen at the sediment-water interface, suggests that changes affected both the surface and subsurface water. A similar concomitant change is also observed in other cores from the Arabian Sea as well as terrestrial records, suggesting a widespread regional MHCT. The MHCT coincides with decreasing low-latitude summer insolation, perturbations in total solar intensity and an increase in atmospheric CO2.

  13. Monsoon-driven vertical fluxes of organic pollutants in the western Arabian Sea

    SciTech Connect

    Dachs, J.; Bayona, J.M.; Ittekkot, V.; Albaiges, J.

    1999-11-15

    A time series of sinking particles from the western Arabian Sea was analyzed for aliphatic and polycyclic aromatic hydrocarbons, polychlorinated biphenyls, 4,4{prime}-DDT and 4,4{prime}-DDE, to assess the role of monsoons on their vertical flux in the Indian Ocean. Concurrently, molecular markers such as sterols and linear and branched alkanes were analyzed enabling the characterization of the biogenic sources and biogeochemical processes occurring during the sampling period. Hierarchical cluster analysis (HCA) of the data set of concentrations and fluxes of these compounds confirmed a seasonal variability driven by the SW and NE monsoons. Moreover, the influence of different air masses is evidenced by the occurrence of higher concentrations of DDT, PCBs, and pyrolytic PAHs during the NE monsoon and of fossil hydrocarbons during the SW monsoon. Total annual fluxes to the deep Arabian Sea represent an important removal contribution of persistent organic pollutants, thus not being available for the global distillation process (volatilization and atmospheric transport from low or mid latitudes to cold areas). Therefore, monsoons may play a significant role on the global cycle of organic pollutants.

  14. Distribution of membrane lipids of planktonic Crenarchaeota in the Arabian Sea.

    PubMed

    Sinninghe Damsté, Jaap S; Rijpstra, W Irene C; Hopmans, Ellen C; Prahl, Fredrick G; Wakeham, Stuart G; Schouten, Stefan

    2002-06-01

    Intact core tetraether membrane lipids of marine planktonic Crenarchaeota were quantified in water column-suspended particulate matter obtained from four depth intervals ( approximately 70, 500, 1,000 and 1,500 m) at seven stations in the northwestern Arabian Sea to investigate the distribution of the organisms at various depths. Maximum concentrations generally occurred at 500 m, near the top of the oxygen minimum zone, and the concentrations at this depth were, in most cases, slightly higher than those in surface waters. In contrast, lipids derived from eukaryotes (cholesterol) and from eukaryotes and bacteria (fatty acids) were at their highest concentrations in surface waters. This indicates that these crenarchaeotes are not restricted to the photic zone of the ocean, which is consistent with the results of recent molecular biological studies. Since the Arabian Sea has a strong oxygen minimum zone between 100 and 1,000 m, with minimum oxygen levels of <1 microM, the abundance of crenarchaeotal membrane lipids at 500 m suggests that planktonic Crenarchaeota are probably facultative anaerobes. The cell numbers we calculated from the concentrations of membrane lipids are similar to those reported for the Central Pacific Ocean, supporting the recent estimation of M. B. Karner, E. F. DeLong, and D. M. Karl ( Nature 409:507-510, 2001) that the world's oceans contain ca. 10(28) cells of planktonic Crenarchaeota.

  15. Dust-induced episodic phytoplankton blooms in the Arabian Sea during winter monsoon

    NASA Astrophysics Data System (ADS)

    Banerjee, Priyanka; Prasanna Kumar, S.

    2014-10-01

    Phytoplankton blooms mediated by the oceanic supply of nutrients is a well-understood phenomenon in the Arabian Sea (AS), while the role of dust deposition in enhancing phytoplankton is less explored. In this paper, we show that during winter monsoon the central Arabian Sea (CAS), away from the realm of active winter convection, supports episodic phytoplankton blooms. These blooms cannot be fully explained by the oceanic input of nutrients through processes such as advection and mixing in the upper ocean. Using satellite images, we tracked about 45 dust storms over the AS during the winter monsoons of 2002-2003 to 2010-2011 of which only eight were followed by chlorophyll enhancements. We used a regional climate model to get possible fluxes of dust and the amount of nutrients (nitrate, phosphate, and iron) that can be derived from the dust depositions. Additionally, we used published in situ nutrients data in conjunction with carbon: nitrogen: phosphorus and iron: carbon molar ratios to compute the potential requirements of different nutrients for the eight cases of chlorophyll enhancements. It is likely that the deepening of the mixed layer can incorporate nitrate and phosphate, but not enough iron from the subsurface waters leading to potential iron limitation. Although, all the phytoplankton blooms within CAS were observed following episodic dust events, only four blooms can be attributed to dust depositions. Our work shows that phytoplankton blooms fueled by episodic dust storms are important in driving the interannual variability in chlorophyll in a region away from active winter convection.

  16. Characterizing Mineral Dust from the Arabian Coast of the Red Sea

    NASA Astrophysics Data System (ADS)

    Puthan Purakkal, J.; Stenchikov, G. L.; Engelbrecht, J. P.

    2014-12-01

    The Arabian Peninsula is one of the Earth's major sources of atmospheric dust. Along with profound negative effects on human activity and natural processes in this region, dust is an important nutrient source for the oligothrophic northern Red Sea. From preliminary observations it is estimated that some 18-20 major dust storms per year deposit about 6 Mt of mineral dust into the Red Sea. To better understand the optical properties, health, and ecological impacts of dust, we study the mineralogical, chemical and morphological properties of surface soil samples collected at prevbiously identified potential dust sources along the Arabian coast of the Red Sea. Many of these dust sources lie within a narrow coastal region and because of their proximity to the Red Sea, are important contributors to the dust/nutrient balance, during both dusty and fair weather conditions. Bulk samples were collected from the top 10 mm of soils from three sites along the Arabian coast of the Red Sea. The soil samples were sieved to separate the < 38μm particle fractions for chemical and mineralogical analysis. X-ray diffractometry (XRD) was applied to measure the mineral content of the dust. The chemical composition of individual particles was analyzed using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). From the XRD analysis of the sieved samples from An Masayat (23.3322 N, 38.9481 E), Buthna (23.2960 N, 38.9384 E) and Rabugh pipeline Road (23.292 N, 38.91 E), it was found that the dust was composed largely of hematite, goethite, calcite, dolomite, quartz, chlorite, muscovite, amphibole, epidote and plagioclase. Our results are being compared to, and show similarities to those of Engelbrecht et al. , collected at 15 Middle East sites. Both the mineralogical content and chemical composition of samples bear the signatures of the regional geology. Engelbrecht, J. P., McDonald, E. V., Gillies, J. A., Jayanty, R. K. M., Casuccio, G., and Gertler, A. W., 2009

  17. Response of benthic foraminifera to phytodetritus in the eastern Arabian Sea under low oxygen conditions

    NASA Astrophysics Data System (ADS)

    Enge, Annekatrin; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula; Hunter, William; Heinz, Petra

    2016-04-01

    At water depths between 100 and 1500 m a permanent Oxygen Minimum Zone (OMZ) impinges on the sea floor in the eastern Arabian Sea, exposing benthic organisms to anoxic to suboxic conditions. The flux of organic matter to the sea floor is relatively high at these depths but displays seasonal variation. Deposition of relatively fresh phytodetrital material (phytoplankton remains) can occur within a short period of time after monsoon periods. Several organism groups including foraminifera are involved to different extent in the processing of phytodetritus in the OMZs of the northern Arabian Sea. A series of in situ feeding experiments were performed to study the short-term processing (< 11 days) of organic carbon, nitrogen and nutritional demands of foraminifera at different oxygen concentrations on the continental margin in the eastern Arabian Sea. For the experiments, a single pulse of isotopically labeled phytodetritus was added to the sediment along a depth transect (540-1100 m) on the Indian Margin, covering the OMZ core and the lower OMZ boundary region. Uptake of phytodetritus within 4 days shows the relevance of phytodetritus as food source for foraminifera. Lower content of phytodetrital carbon recorded in foraminifera from more oxygenated depths shows greater food uptake by foraminifera in the OMZ core than in the OMZ boundary region. The foraminiferal assemblage living under almost anoxic conditions in the OMZ core is dominated by species typically found in eutroph environments (such as Uvigerinids) that are adapted to high flux of organic matter. The elevated carbon uptake can also result from missing food competition by macrofauna or from greater energy demand in foraminifera to sustain metabolic processes under hypoxic stress. Variable levels and ratios of phytodetrital carbon and nitrogen indicate specific nutritional demands and storage of food-derived nitrogen in some foraminifera species under near anoxia where the mean phytodetrital nitrogen content

  18. Dtection of Sea Level Rise within the Arabian Gulf Using Space Based GNSS Measurements and Insitu Tide Gauge data

    NASA Astrophysics Data System (ADS)

    Alothman, Abdulaziz; Ayhan, Mehmet

    In the 21st century, sea level rise is expected to be about 30 cm or even more (up to 60 cm). Saudi Arabia has very long coasts of about 3400 km and hundreds of islands. Therefore, sea level monitoring may be important in particular along coastal low lands on Red Sea and Arabian Gulf coasts. Arabian Gulf is connected to Indian Ocean and lying along a parallel course in the south-west of the Zagros Trust Belt. We expect vertical land motion within the area due to both tectonic structures of the Arabian Peninsula and oil production activities. Global Navigation Satellite System (GNSS) Continues observations were used to estimate the vertical crustal motion. Bahrain International GPS Service (IGS-GPS) station is the only continuous GPS station accessible in the region, and it is close to the Mina Sulman tide gauge station in Bahrain. The weekly GPS time series of vertical component at Bahrain IGS-GPS station referring to the ITRF97 from 1999.2 to 2008.6 are used in the computation. We fitted a linear trend with an annual signal and a break to the GPS vertical time series and found a vertical land motion rate of 0.46 0.11 mm/yr. To investigate sea level variation within the west of Arabian Gulf, monthly means of sea level at 13 tide gauges along the coast of Saudi Arabia and Bahrain, available in the database of the Permanent Service for Mean Sea Level (PSMSL), are studied. We analyzed separately the monthly mean sea level measurements at each station, and estimated secular sea level rate by a robust linear trend fitting. We computed the average relative sea level rise rate of 1.96 0.21 mm/yr within the west of Arabian Gulf based on 4 stations spanning longer than 19 years. Sea level rates at the stations are first corrected for vertical land motion contamination using the ICE-5G v1.2 VM4 Glacial Isostatic Adjustment (GIA) model, and the average sea level rate is found 2.27 0.21 mm/yr. Assuming the vertical rate at Bahrain IGS-GPS station represents the vertical rate

  19. Homogeneity of coral reef communities across 8 degrees of latitude in the Saudi Arabian Red Sea.

    PubMed

    Roberts, May B; Jones, Geoffrey P; McCormick, Mark I; Munday, Philip L; Neale, Stephen; Thorrold, Simon; Robitzch, Vanessa S N; Berumen, Michael L

    2016-04-30

    Coral reef communities between 26.8 °N and 18.6 °N latitude in the Saudi Arabian Red Sea were surveyed to provide baseline data and an assessment of fine-scale biogeography of communities in this region. Forty reefs along 1100 km of coastline were surveyed using depth-stratified visual transects of fish and benthic communities. Fish abundance and benthic cover data were analyzed using multivariate approaches to investigate whether coral reef communities differed with latitude. A total of 215 fish species and 90 benthic categories were recorded on the surveys. There were no significant differences among locations in fish abundance, species richness, or among several diversity indices. Despite known environmental gradients within the Red Sea, the communities remained surprisingly similar. The communities do, however, exhibit subtle changes across this span of reefs that likely reflect the constrained distributions of several species of reef fish and benthic fauna.

  20. Homogeneity of coral reef communities across 8 degrees of latitude in the Saudi Arabian Red Sea.

    PubMed

    Roberts, May B; Jones, Geoffrey P; McCormick, Mark I; Munday, Philip L; Neale, Stephen; Thorrold, Simon; Robitzch, Vanessa S N; Berumen, Michael L

    2016-04-30

    Coral reef communities between 26.8 °N and 18.6 °N latitude in the Saudi Arabian Red Sea were surveyed to provide baseline data and an assessment of fine-scale biogeography of communities in this region. Forty reefs along 1100 km of coastline were surveyed using depth-stratified visual transects of fish and benthic communities. Fish abundance and benthic cover data were analyzed using multivariate approaches to investigate whether coral reef communities differed with latitude. A total of 215 fish species and 90 benthic categories were recorded on the surveys. There were no significant differences among locations in fish abundance, species richness, or among several diversity indices. Despite known environmental gradients within the Red Sea, the communities remained surprisingly similar. The communities do, however, exhibit subtle changes across this span of reefs that likely reflect the constrained distributions of several species of reef fish and benthic fauna. PMID:26608504

  1. Hydrographic characterization of southeast Arabian Sea during the wane of southwest monsoon and spring intermonsoon.

    PubMed

    Vimal Kumar, K G; Dinesh Kumar, P K; Smitha, B R; Habeeb Rahman, H; Josia, Jacob; Muraleedharan, K R; Sanjeevan, V N; Achuthankutty, C T

    2008-05-01

    Seasonal variation of the hydrography along the southeast Arabian Sea is described using data collected onboard FORV Sagar Sampada in September--October 2003 (later phase of Southwest monsoon, SWM) and March--April 2004 (Spring inter monsoon, SIM). During the later phase of the SWM, upwelling was in the withdrawal phase and the frontal structure was clearer in the northern sections (13 and 15 degrees N lat) indicating strong upwelling in the area. The driving force of upwelling is identified as the combination of alongshore wind stress and remote forcing with a latitudinal variability. Although a more prominent upwelling was found in the north, a maximum surface Chlorophyll-a was found in the south (10 degrees N). During the SIM, the area was characterized by oligotrophic water with relatively high Sea Surface Temperature (>29 degrees C) and low salinity (33.8 to 35.4). During March, the surface hydrography was found to be controlled mainly by the intrusion of low-saline waters from the south, while during September by the high saline water from the north. The presence of various water masses [Arabian Sea High Salinity Water (ASHSW), Persian Gulf Water (PGW), Red Sea Water (RSW)] and their seasonal variations in the region is discussed and their decreasing influence towards the south is noted during both periods of observation. During the SWM, the dynamic topography showed the equator-ward flow of the West India Coastal Current (WICC) at the surface and a pole-ward coastal under current at sub-thermocline depth. During the SIM, surface circulation revealed the WICC flowing pole-ward north of 13 degrees N, but equator-ward flow in the south, with a clockwise circulation around the Lakshadweep High.

  2. Challenges in modelling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman

    NASA Astrophysics Data System (ADS)

    Sedigh Marvasti, S.; Gnanadesikan, A.; Bidokhti, A. A.; Dunne, J. P.; Ghader, S.

    2015-07-01

    We examine interannual variability of phytoplankton blooms in northwestern Arabian Sea and Gulf of Oman. Satellite data (SeaWIFS ocean color) shows two climatological blooms in this region, a wintertime bloom peaking in February and a summertime bloom peaking in September. A pronounced anti-correlation between the AVISO sea surface height anomaly (SSHA) and chlorophyll is found during the wintertime bloom. On a regional scale, interannual variability of the wintertime bloom is thus dominated by cyclonic eddies which vary in location from one year to another. These results were compared against the outputs from three different 3-D Earth System models. We show that two coarse (1°) models with the relatively complex biogeochemistry (TOPAZ) capture the annual cycle but neither eddies nor the interannual variability. An eddy-resolving model (GFDL CM2.6) with a simpler biogeochemistry (miniBLING) displays larger interannual variability, but overestimates the wintertime bloom and captures eddy-bloom coupling in the south but not in the north. The southern part of the domain is a region with a much sharper thermocline and nutricline relatively close to the surface, in which eddies modulate diffusive nutrient supply to the surface (a mechanism not previously emphasized in the literature). We suggest that for the model to simulate the observed wintertime blooms within cyclones, it will be necessary to represent this relatively unusual nutrient structure as well as the cyclonic eddies. This is a challenge in the Northern Arabian Sea as it requires capturing the details of the outflow from the Persian Gulf.

  3. The sensitivity of the southwest monsoon phytoplankton bloom to variations in aeolian iron deposition over the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Wiggert, Jerry D.; Murtugudde, Raghu G.

    2007-05-01

    A coupled, 3-D biophysical ocean general circulation model is used to investigate how aeolian iron deposition affects the Arabian Sea ecosystem. Two separate aeolian iron deposition fields, derived from the GISS and GOCART atmospheric transport models, have been applied as surface boundary conditions. The model results exhibit widespread biogeochemical sensitivity to the choice of deposition field. With GOCART deposition, SW Monsoon phytoplankton blooms in the western and central Arabian Sea are enhanced and exhibit greater realism. The central Arabian Sea bloom is supported by supplemental input of horizontally advected iron from a pool that undergoes a yearlong progression that begins in the Gulf of Oman, where the difference in aeolian iron enrichment between the two deposition fields is most prevalent. The GOCART-enhanced blooms result in a more pronounced shift toward netplankton, an increase in euphotic zone export flux of up to a 20% during the SW Monsoon and an additional annual biogenic export of 3.5 TgC. The potential ramifications of regional N-cycle alteration through stimulation of N2-fixation that is promoted by significant aeolian mineral flux needs to be explored. The canonical thinking that the northern Arabian Sea is invariably iron replete is now being challenged by both our model results and recent observational studies. As well, our results indicate that Arabian Sea iron concentrations are strongly modulated by the specific nature of aeolian mineral deposition. Thus climate or land use influences on dust mobilization could exercise leading-order controls on regional biogeochemical variability, metabolic status and air-sea exchanges of CO2.

  4. Evidence for eddy formation in the eastern Arabian Sea during the northeast monsoon

    NASA Technical Reports Server (NTRS)

    Bruce, John G.; Johnson, Donald R.; Kindle, John C.

    1994-01-01

    The seasonal formation of a large (500-800 km diameter) anticyclonic eddy in the upper 300-400 m of the eastern Arabian Sea during the northest monsoon period (December-April) is indicated fom hydrographic and satellite altimetry sea level observations, as well as from numerical model experiments. The center of the eddy circulation is approximately 10 deg N, 70 deg E, just to the west of the north-south Laccadive Island chain. In this paper the eddy is called the Laccadive High (LH). In some ways it is like a mirrorlike counterpart to the Great Whirl that develops during the southwest monsoon of the Somali coast (western Arabian Sea). The LH occurs at the same latitude but on the opposite side of the basin during the reversed monsoon. It is different from the Great Whirl, however, in its formation process, its intensity, and its decay. The hydrographic data obtained from surveys all during a single season give sufficiently close station spacing to allow reasonable contouring of the geopotential surfaces and of the properties within and around the LH region with minimum time aliasing. The Geostat altimeter record extends over 4 years, during which the seasonal variability of the LH indicates a dynamic relief of approximately 15-20 cm, which is in good agreement with the hydrographics observations. The altimetry time series also suggests a westward translation of the LH by January with a subsequent dissipation in midbasin. The model used is a wind-forced three-layer primitive equation model which depicts a LH agreement with the timing, position, and amplitude of both the hydrographic and altimetric measurements. The numerical simulation includes a passive tracer located in the Western Bay of Bengal; the western advection of the tracer around the south coasts of Sri Lanka and India in December and January is consistent with the appearance of low-salinity water observed to extend into the Arabian Sea during this period. The modeling studies suggest that both local and

  5. Latitudinal and longitudinal variation in aerosol characteristics from Sun photometer and MODIS over the Bay of Bengal and Arabian Sea during ICARB

    NASA Astrophysics Data System (ADS)

    Kedia, Sumita; Ramachandran, S.

    2008-07-01

    Spatial variations in aerosol optical properties as function of latitude and longitude are analysed over the Bay of Bengal and Arabian Sea during ICARB cruise period of March-May 2006 from in situ sun photometer and MODIS (Terra, Aqua) satellite measurements. Monthly mean 550 nm aerosol optical depths (AODs) over the Bay of Bengal and Arabian Sea show an increase from March to May both in spatial extent and magnitude. AODs are found to increase with latitude from 4°N to 20°N over the Bay of Bengal while over Arabian Sea, variations are not significant. Sun photometer and MODIS AODs agree well within ±1σ variation. Bay of Bengal AOD (0.28) is higher than the Arabian Sea (0.24) latitudinally. Aerosol fine mode fraction (FMF) is higher than 0.6 over Bay of Bengal, while FMF in the Arabian Sea is about 0.5. Bay of Bengal α(˜1) is higher than the Arabian Sea value of 0.7, suggesting the dominance of fine mode aerosols over Bay of Bengal which is corroborated by higher FMF values over Bay of Bengal. Air back trajectory analyses suggest that aerosols from different source regions contribute differently to the optical characteristics over the Bay of Bengal and Arabian Sea.

  6. Features of aerosol optical depths over the Bay of Bengal and the Arabian Sea during premonsoon season: Variabilities and anthropogenic influence

    NASA Astrophysics Data System (ADS)

    Kedia, Sumita; Ramachandran, S.

    2008-06-01

    Spectral aerosol optical depths (AOD) measured on board a cruise over the Bay of Bengal and the Arabian Sea during March-May 2006 are analyzed. Mean 0.5 μm AOD over the Bay of Bengal is higher (0.36) than the Arabian Sea (0.25). AODs obtained from MODIS Terra and Aqua are found to track well the Sun photometer AODs. A comparison between Sun photometer and MODIS AODs yielded a correlation coefficient of 0.96. MODIS fine mode fraction over the Bay of Bengal is higher (0.71) when compared to the Arabian Sea value of 0.60. Ångström exponent (α) over the Bay of Bengal is higher at 1.12, indicating the dominance of smaller size aerosols in the aerosol columnar distribution than the Arabian Sea (0.73), while Ångström coefficient (β) is comparable at 0.15 and 0.16 for the Bay of Bengal and the Arabian Sea. Background AODs are higher over the Bay of Bengal and the Arabian Sea indicating a strong continental influence. The scaling distance is lower over the Bay of Bengal due to nearly similar AODs, while the scaling distance over the Arabian Sea is about 2000 km. The anthropogenic influence in AODs over the Bay of Bengal and the Arabian Sea estimated using wind speed dependent AODs and maritime clean AODs are found to agree within ±1σ of the anthropogenic fraction obtained from MODIS AODs and FMFs. The mean anthropogenic contribution to the AODs estimated from the three methods is higher over the Bay of Bengal (68-75%) than the Arabian Sea (51-65%).

  7. Plio-Pleistocene paleoclimatic variability: results from the NW Arabian Sea

    NASA Astrophysics Data System (ADS)

    Prakasam, M.; Gupta, A. K.; Yuvaraja, A.; Velu, A.

    2014-12-01

    The Plio-Pleistocene period is marked by numerous changes in Earth's climate and tectonics. The early Pliocene average global surface temperature of ~3° C was warmer than today and the sea level was high around 10-20 m, whereas the continents adjudicated its present day position. In this study we discussed about Indian monsoon variability during the Plio-Pleistocene. Numerous investigations were carried out over the last two decades to understand Indian summer monsoon (ISM) variability and its relation to Himalayan tectonics. The ISM is a principal factor to the economy of the south Asian countries playing immense role in changing fauna and flora on land as well as socio-economic conditions of this region. The Arabian Sea is a natural laboratory to carry out paleoclimatic studies on marine sediments. In this study four Ocean Drilling Programme sediment cores were used from the northwestern Arabian Sea, Leg 117, Holes 722B, 731A (Owen Ridge) and 728B, 730A (Oman margin). The planktonic foraminiferal species abundances, Total Organic Carbon (TOC) wt.% and carbonate concentration (CaCO3) proxies were utilised to understand Plio-Pleistocene Indian monsoon variability. The relative abundances of Globigerina bulloides, Globigerinita glutinata and mixed layer species reveal changes in upwelling and mixed layer since the Pliocene. Our results demonstrate that intense upwelling occurred during 5 to ~3.7 Ma, 1.5Ma to Recent and an abrupt change was recorded around 0.1 Ma at all the Holes. The weakening of upwelling occurred from 3.5 Ma to ~1.5 Ma, hence we argue that this is due to Northern Hemisphere Glaciation. Mixed layer species show higher abundances from 2 Ma to 0.8 Ma. The TOC wt.% varies from 7.8% to 0.5% and productive increased many fold during 4 to 2 Ma. The results of TOC and CaCO3 are inversely correlated indicating role of carbonate dissolution.

  8. Challenges in modeling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman

    NASA Astrophysics Data System (ADS)

    Sedigh Marvasti, S.; Gnanadesikan, A.; Bidokhti, A. A.; Dunne, J. P.; Ghader, S.

    2016-02-01

    Recent years have shown an increase in harmful algal blooms in the Northwest Arabian Sea and Gulf of Oman, raising the question of whether climate change will accelerate this trend. This has led us to examine whether the Earth System Models used to simulate phytoplankton productivity accurately capture bloom dynamics in this region - both in terms of the annual cycle and interannual variability. Satellite data (SeaWIFS ocean color) show two climatological blooms in this region, a wintertime bloom peaking in February and a summertime bloom peaking in September. On a regional scale, interannual variability of the wintertime bloom is dominated by cyclonic eddies which vary in location from one year to another. Two coarse (1°) models with the relatively complex biogeochemistry (TOPAZ) capture the annual cycle but neither eddies nor the interannual variability. An eddy-resolving model (GFDL CM2.6) with a simpler biogeochemistry (miniBLING) displays larger interannual variability, but overestimates the wintertime bloom and captures eddy-bloom coupling in the south but not in the north. The models fail to capture both the magnitude of the wintertime bloom and its modulation by eddies in part because of their failure to capture the observed sharp thermocline and/or nutricline in this region. When CM2.6 is able to capture such features in the Southern part of the basin, eddies modulate diffusive nutrient supply to the surface (a mechanism not previously emphasized in the literature). For the model to simulate the observed wintertime blooms within cyclones, it will be necessary to represent this relatively unusual nutrient structure as well as the cyclonic eddies. This is a challenge in the Northern Arabian Sea as it requires capturing the details of the outflow from the Persian Gulf - something that is poorly done in global models.

  9. Variations in productivity and eolian fluxes in the northeastern Arabian Sea during the past 110 ka

    NASA Astrophysics Data System (ADS)

    Pourmand, Ali; Marcantonio, Franco; Schulz, Hartmut

    2004-04-01

    High-resolution (one to two samples/ka) radionuclide proxy records from core 93KL in the northeastern Arabian Sea provide evidence for millennial climate variability over the past 110 ka. We interpret 230Th-normalized 232Th fluxes as a proxy for eolian input, and authigenic uranium concentrations as a proxy for past productivity. We attribute orbital and suborbital variations in both proxies to changes in the intensity of the southwest Indian Ocean monsoon. The highest 230Th-normalized 232Th fluxes occur at times that are consistent with the timing of the Younger Dryas, Heinrich events 1-7 and cold Dansgaard-Oeschger stadial events recorded in the GISP2 ice core. Such high dust fluxes may be due to a weakened southwest monsoon in conjunction with strengthened northwesterlies from the Arabian Peninsula and Mesopotamia. Authigenic uranium concentrations, on the other hand, are highest during warm Dansgaard-Oeschger interstadials when the southwest monsoon is intensified relative to the northwesterly winds. Our results also indicate that on orbital timescales maximum average eolian fluxes coincide with the timing of marine isotopic stage (MIS) 2 and 4, while minimum fluxes occur during MIS 1, 3 and 5. Although the forcing mechanism(s) controlling suborbital variabilities in monsoonal intensity is still debated, our findings suggest an atmospheric teleconnection between the low-latitude southwest monsoon and North Atlantic climate.

  10. Scavenger assemblages under differing trophic conditions: a case study in the deep Arabian Sea

    NASA Astrophysics Data System (ADS)

    Janßen, Felix; Treude, Tina; Witte, Ursula

    Baited cameras and traps were deployed at four stations in the deep Arabian Sea to investigate the composition of the necrophagous fauna and to evaluate whether regional differences in trophic conditions are reflected by differing scavenger assemblages. The ophidiid fish Barathrites iris, the large lysianassoid amphipod Eurythenes gryllus, the aristeid prawn Plesiopenaeus armatus, and zoarcid fishes of the genus Pachycara were abundant at the bait at all stations. The ophidiid Holcomycteronus aequatorius, the liparid fish Paraliparis sp., and galatheid crabs of the genus Munidopsis occurred in considerable numbers at single sites. Trap catches further contained lysianassoid amphipods of the genera Paralicella, Abyssorchomene and Paracallisoma. In contrast to scavenger assemblages of the Atlantic and Pacific Ocean, macrourid fishes were virtually absent at the bait. E. gryllus and B. iris consumed the main proportion of the bait, while consumption was at most moderate in all other taxa. Feeding strategies of the respective taxa are inferred from their behavior at the bait and discussed with regard to the profit that can be drawn from food falls. Differences between stations were pronounced with respect to species dominating bait consumption. E. gryllus appeared in highest numbers at the bait in the productive northern and central Arabian Sea where a relatively high availability of food items is expected to sustain high population densities. High numbers of B. iris in the least productive southern part indicate their ability to persist under food-poor conditions and may correspond to a high dependency on food falls. E. gryllus and B. iris both occurred in smaller numbers in the particularly productive western Arabian Sea. This may reflect a reduced dependency on food falls, due to an access to alternative food sources, rather than small population densities. Smaller numbers of E. gryllus and B. iris resulted in slower bait consumption and gave Pachycara spp. the

  11. Late Holocene SST and primary productivity variations in the northeastern Arabian Sea as a recorder for winter monsoon variability

    NASA Astrophysics Data System (ADS)

    Böll, Anna; Gaye, Birgit; Lückge, Andreas

    2014-05-01

    Variability in the oceanic environment of the Arabian Sea region is strongly influenced by the seasonal monsoon cycle of alternating wind directions. Strong south-westerly winds during the summer monsoon induce upwelling of nutrient rich waters along the coast off Somalia, Oman and southwest India, which result in high rates of primary production. In the northeastern Arabian Sea off Pakistan on the other hand, primary production and sea surface temperatures are linked to northeast monsoonal winds that cool the sea surface and drive convective mixing and high surface ocean productivity during the winter season. In this study, we analyzed alkenone-derived sea surface temperature (SST) variations and proxies of primary productivity (organic carbon and δ15N) in a well-laminated sediment core from the Pakistan continental margin to establish the first high-resolution record of winter monsoon variability for the late Holocene. Over the last 2400 years reconstructed SST in the northeastern Arabian Sea decreased whereas productivity increased, imaging a long-term trend of northeast monsoon strengthening in response to insolation-induced southward migration of the Intertropical Convergence Zone. The comparison of our winter monsoon record with records of summer monsoon intensity suggests that summer and winter monsoon strength was essentially anti-correlated over the late Holocene throughout the Asian monsoon system. In addition, SST variations recorded off Pakistan match very well with Northern Hemisphere temperature records supporting the growing body of evidence that Asian climate is linked to Northern Hemisphere climate change. It reveals a consistent pattern of increased summer monsoon activity in the northeastern Arabian Sea during northern hemispheric warm periods (Medieval Warm Period, Roman Warm Period) and strengthened winter monsoon activity during hemispheric colder periods (Little Ice Age).

  12. Bio-Optical Properties of the Arabian Sea as Determined by In Situ and Sea WiFS Data

    NASA Technical Reports Server (NTRS)

    Trees, Charles C.

    1997-01-01

    The overall objective of this work was to characterize optical and fluorescence properties in the euphotic zone during two British Ocean Flux Study (BOFS) Arabian Sea cruises. This was later expanded in 1995 to include three U.S. JGOFS Arabian Sea Cruises. The region was to be divided into one or more "bio-optical provinces," within each of which a single set of regression models was to be developed to relate the vertical distribution of irradiance attenuation and normalized fluorescence (SF and NF) to remote sensing reflectance and diffuse attenuation coefficient. The working hypothesis was that over relatively large spatial and temporal scales, the vertical profiles of bio-optical properties were predictable. The specific technical objectives were: (1) To characterize the vertical distribution of the inherent and apparent optical properties by measuring downwelling and upwelling irradiances, upwelling radiances, scalar irradiance of PAR, and beam transmissions at each station - from these data, spectral diffuse attenuation coefficients, irradiance reflectances, remote sensing reflectances, surface-leaving radiances and beam attenuation coefficients were determined; (2) To characterize the spectral absorption of total particulate, detrital, and dissolved organic material at each station from discrete water samples; (3) To describe the vertical distribution of photoadaptive properties in the water column by measuring profiles of stimulated (SF) and natural (NF) fluorescence and examining relationships between SF and NF as a function of diffuse optical depth, pigment biomass and primary productivity; and (4) To establish locally derived, in-water algorithms relating remote sensing reflectance spectra to diffuse attenuation coefficients, phytoplankton pigment concentrations and primary productivity, through intercomparisons with in situ measurements, for application to SeaWiFS data.

  13. Late Holocene primary productivity and sea surface temperature variations in the northeastern Arabian Sea: Implications for winter monsoon variability

    NASA Astrophysics Data System (ADS)

    Böll, Anna; Lückge, Andreas; Munz, Philipp; Forke, Sven; Schulz, Hartmut; Ramaswamy, V.; Rixen, Tim; Gaye, Birgit; Emeis, Kay-Christian

    2014-08-01

    Variability in the oceanic environment of the Arabian Sea region is strongly influenced by the seasonal monsoon cycle of alternating wind directions. Prominent and well studied is the summer monsoon, but much less is known about late Holocene changes in winter monsoon strength with winds from the northeast that drive convective mixing and high surface ocean productivity in the northeastern Arabian Sea. To establish a high-resolution record of winter monsoon variability for the late Holocene, we analyzed alkenone-derived sea surface temperature (SST) variations and proxies of primary productivity (organic carbon and δ15N) in a well-laminated sediment core from the Pakistan continental margin. Weak winter monsoon intensities off Pakistan are indicated from 400 B.C. to 250 A.D. by reduced productivity and relatively high SST. At about 250 A.D., the intensity of the winter monsoon increased off Pakistan as indicated by a trend to lower SST. We infer that monsoon conditions were relatively unstable from ~500 to 1300 A.D., because primary production and SST were highly variable. Declining SST and elevated biological production from 1400 to 1900 A.D. suggest invigorated convective winter mixing by strengthening winter monsoon circulation, most likely a regional expression of colder climate conditions during the Little Ice Age on the Northern Hemisphere. The comparison of winter monsoon intensity with records of summer monsoon intensity suggests that an inverse relationship between summer and winter monsoon strength exists in the Asian monsoon system during the late Holocene, effected by shifts in the Intertropical Convergence Zone.

  14. Massive outbreaks of Noctiluca scintillans blooms in the Arabian Sea due to spread of hypoxia.

    PubMed

    do Rosário Gomes, Helga; Goes, Joaquim I; Matondkar, S G P; Buskey, Edward J; Basu, Subhajit; Parab, Sushma; Thoppil, Prasad

    2014-09-09

    In the last decade, the northern Arabian Sea has witnessed a radical shift in the composition of winter phytoplankton blooms, which previously comprised mainly of diatoms, the unicellular, siliceous photosynthetic organisms favoured by nutrient-enriched waters from convective mixing. These trophically important diatom blooms have been replaced by widespread blooms of a large, green dinoflagellate, Noctiluca scintillans, which combines carbon fixation from its chlorophyll-containing endosymbiont with ingestion of prey. Here, we report that these massive outbreaks of N. scintillans during winter are being facilitated by an unprecedented influx of oxygen deficient waters into the euphotic zone and by the extraordinary ability of its endosymbiont Pedinomonas noctilucae to fix carbon more efficiently than other phytoplankton under hypoxic conditions. We contend that N. scintillans blooms could disrupt the traditional diatom-sustained food chain to the detriment of regional fisheries and long-term health of an ecosystem supporting a coastal population of nearly 120 million people.

  15. Weight dependence of arsenic concentration in the Arabian Sea tuna fish

    SciTech Connect

    Ashraf, M.; Jaffar, M.

    1988-02-01

    The objective of the present investigation was to estimate the arsenic concentration in the edible muscle of Thunnus thynnus and Thunnus toggel (hereafter called tuna and longtail tune) as they have great commercial value. These fish are widely available along the coastal line of Pakistan and are consumed abundantly in large bulk. Thus, it was felt justifiable on the basis of safety of human health that data, in the first instance, be obtained on arsenic concentration in tuna as a function of weight to check whether the metal distribution was species-specific or it depended on individual mode of development. The data, the first of the kind so far presented on the Arabian Sea tuna, would thus provide the required baseline quantitative information needed in future studies on the physiological processes regulating the distribution and uptake of arsenic by these and other species of fish common to the region.

  16. Seasonal response of zooplankton to monsoonal reversals in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Smith, Sharon; Roman, Michael; Prusova, Irina; Wishner, Karen; Gowing, Marcia; Codispoti, L. A.; Barber, Richard; Marra, John; Flagg, Charles

    The US JGOFS Arabian Sea Process Study was designed to provide a seasonally and spatially resolved carbon budget for a basin exhibiting some of the highest and lowest concentrations of plant biomass in the world's ocean. During the US JGOFS Process Study in the Arabian Sea (September 1994-January 1996), the absolute maximum in biomass of epipelagic zooplankton in the entire study was observed during the Southwest Monsoon season inshore of the Findlater Jet in the area of upwelling. The greatest contrast between high and low biomass in the study area also was observed during the Southwest Monsoon, as was the strongest onshore-offshore gradient in biomass. Lowest biomass throughout the study was observed at the most offshore station (S15), outside the direct influence of the monsoon forcing. The greatest day/night contrasts in biomass were observed nearshore in all seasons, with nighttime biomass exceeding daytime in the Northeast Monsoon season, but daytime exceeding nighttime in the Southwest Monsoon season. The diel vertical migration patterns in general reversed between the monsoons at all stations in the southern part of the study area. Virtually, no diel vertical migration of zooplankton took place in any season at the station with strong, persistent subsurface suboxic conditions (N7), suggesting that these conditions suppress migration. Based on the distribution of biomass, we hypothesize that inshore of the Findlater Jet, zooplankton grazing on phytoplankton is the dominant pathway of carbon transformation during both monsoon seasons, whereas offshore the zooplankton feed primarily on microplankton or are carnivorous, conditions that result in reduction of the carbon flux mediated by the zooplankton. Predation by mesopelagic fish, primarily myctophids, may equal daily growth of zooplankton inshore of the Findlater Jet during all seasons. This suggests that the food web inshore of the Findlater Jet is well integrated, may have evolved during past periods of

  17. Response of subsurface waters in the eastern Arabian Sea to tropical cyclones

    NASA Astrophysics Data System (ADS)

    Rao, A. D.; Joshi, Madhu; Jain, Indu; Ravichandran, M.

    2010-11-01

    Thermister chain data at different depths for June 1998 cyclone in the Arabian Sea at a location (69.2 E,15.5 N) which is about 60 km to the left of the cyclone track indicates subsurface warming below 60 m and inertial oscillations of temperature with a periodicity of about 2 days. The oscillations continued for ˜15 days even after the cyclone crossed the coast. The analysis of the buoy, DS1 located at the same position also suggests a stabilized southward flow after about two weeks of the cyclone crossed the coast. Analysis of the buoy data for May 1999 cyclone in the same region also indicates similar pattern. In order to investigate the effect of cyclone-ocean interaction and primarily to understand the process for the subsurface warming, 3-dimensional Princeton Ocean Model is configured for the eastern part of the Arabian Sea. The model uses high horizontal resolution of about 6 km near the coast and a terrain following sigma coordinate in the vertical with 26 levels. The study focuses on surface cooling and temperature rise in the underlying waters and explains its mechanism through upwelling and downwelling respectively. The simulations in concurrence with the observations suggest that the occurrence of subsurface warming precedes the surface cooling with a lag of ˜a day as the cyclone advances DS1. The simulations also demonstrate local temperature stratification plays an important role for cooling of the upper ocean and warming of the subsurface waters and extent of warming is directly related to the depth of the thermocline.

  18. MODIS-Aqua detects Noctiluca scintillans and hotspots in the central Arabian Sea.

    PubMed

    Dwivedi, R; Priyaja, P; Rafeeq, M; Sudhakar, M

    2016-01-01

    Northern Arabian Sea is considered as an ecologically sensitive area as it experiences a massive upwelling and long-lasting algal bloom, Noctiluca scintillans (green tide) during summer and spring-winter, respectively. Diatom bloom is also found to be co-located with N. scintillans and both have an impact on ecology of the basin. In-house technique of detecting species of these blooms from Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua data was used to generate a time-series of images revealing their spatial distribution. A study of spatial-temporal variability of these blooms using satellite data expressed a cyclic pattern of their spread over a period of 13 years. An average distribution of the blooms for January-March period revealed a peak in 2015 and minimum in 2013. Subsequently, a time-series of phytoplankton species images were generated for these 2 years to study their inter-annual variability and the associated factors. Species images during active phase of the bloom (February) in 2015 indicated development of N. scintillans and diatom in the central Arabian Sea also, up to 12° N. This observation was substantiated with relevant oceanic parameters measured from the ship as well as satellite data and the same is highlight of the paper. While oxygen depletion and release of ammonia associated with N. scintillans are detrimental for waters on the western side; it is relatively less extreme and supports the entire food chain on the eastern side. In view of these contrasting eco-sensitive events, it is a matter of concern to identify biologically active persistent areas, hot spots, in order to study their ecology in detail. An ecological index, persistence of the bloom, was derived from the time-series of species images and it is another highlight of our study. PMID:26690080

  19. MODIS-Aqua detects Noctiluca scintillans and hotspots in the central Arabian Sea.

    PubMed

    Dwivedi, R; Priyaja, P; Rafeeq, M; Sudhakar, M

    2016-01-01

    Northern Arabian Sea is considered as an ecologically sensitive area as it experiences a massive upwelling and long-lasting algal bloom, Noctiluca scintillans (green tide) during summer and spring-winter, respectively. Diatom bloom is also found to be co-located with N. scintillans and both have an impact on ecology of the basin. In-house technique of detecting species of these blooms from Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua data was used to generate a time-series of images revealing their spatial distribution. A study of spatial-temporal variability of these blooms using satellite data expressed a cyclic pattern of their spread over a period of 13 years. An average distribution of the blooms for January-March period revealed a peak in 2015 and minimum in 2013. Subsequently, a time-series of phytoplankton species images were generated for these 2 years to study their inter-annual variability and the associated factors. Species images during active phase of the bloom (February) in 2015 indicated development of N. scintillans and diatom in the central Arabian Sea also, up to 12° N. This observation was substantiated with relevant oceanic parameters measured from the ship as well as satellite data and the same is highlight of the paper. While oxygen depletion and release of ammonia associated with N. scintillans are detrimental for waters on the western side; it is relatively less extreme and supports the entire food chain on the eastern side. In view of these contrasting eco-sensitive events, it is a matter of concern to identify biologically active persistent areas, hot spots, in order to study their ecology in detail. An ecological index, persistence of the bloom, was derived from the time-series of species images and it is another highlight of our study.

  20. Oxygen isotopic analyses of individual planktic foraminifera species: implications for seasonality in the western Arabian Sea

    NASA Astrophysics Data System (ADS)

    Naidu, P. D.; Niitsuma, N.; Naik, S.

    2014-09-01

    The variation of stable isotopes between individual shells of planktic foraminifera of a given species and size may provide short-term seasonal insight on Paleoceanography. In this context, oxygen isotope analyses of individual Globigerinoides sacculifer and Neogloboquadrina dutertrei were carried out from the Ocean Drilling Program Site 723A in the western Arabian Sea to unravel the seasonal changes for the last 22 kyr. δ18O values of single shells of G. sacculifer range from of 0.54 to 2.09‰ at various depths in the core which cover a time span of the last 22 kyr. Maximum inter-shell δ18O variability and high standard deviation is noticed from 20 to 10 kyr, whereas from 10 kyr onwards the inter shell δ18O variability decreased. The individual contribution of sea surface temperature (SST) and sea surface salinity (SSS) on the inter shell δ18O values of G. sacculifer were quantified. Maximum seasonal SST between 20 and 14 ka was caused due to weak summer monsoon upwelling and strong cold winter arid continental winds. Maximum SSS differences between 18 and 10 ka is attributed to the increase of net evaporation minus precipitation due to the shift of ITCZ further south. Overall, winter dominated SST signal in Greenland would be responsible to make a teleconnection between Indian monsoon and Greenland temperature. Thus the present study has wider implications in understanding wether the forcing mechanisms of tropical monsoon climate lies in high latitudes or in the tropics.

  1. Radionuclide fluxes in the Arabian Sea: the role of particle composition

    NASA Astrophysics Data System (ADS)

    Scholten, J. C.; Fietzke, J.; Mangini, A.; Stoffers, P.; Rixen, T.; Gaye-Haake, B.; Blanz, T.; Ramaswamy, V.; Sirocko, F.; Schulz, H.; Ittekkot, V.

    2005-02-01

    We investigated the influence of the composition of the vertical particle flux on the removal of particle reactive natural radionuclides ( 230Th and 231Pa) from the water column to the sediments. Radionuclide concentrations determined in sediment traps moored in the western, central and eastern Arabian Sea were related to the major components (carbonate, particulate organic matter (POC), opal, lithogenic material) of the particle flux. These data were combined with sediment trap data previously published from the Southern Ocean, Equatorial Pacific and North Atlantic [Z. Chase, R.F. Anderson, M.Q. Fleisher, P.W. Kubik, The influence of particle composition and particle flux on scavenging of Th, Pa and Be in the ocean, Earth Planet. Sci. Lett. 204 (2002) 215-229; J.C. Scholten, F. Fietzke, S. Vogler, M. Rutgers van der Loeff, A. Mangini, W. Koeve, J. Waniek, P. Stoffers, A. Antia, J. Kuss, Trapping efficiencies of sediment traps from the deep eastern North Atlantic: The 230Th calibration, Deep Sea Research II 48 (2001) 2383-2408]. The correlations observed between the particle-dissolved distribution coefficients ( Kd) of 230Th and 231Pa and the concentrations of the particle types depend on the sediment trap data set used. This result suggests that scavenging affinities of the nuclides differ between oceanic regions. Several factors ( Kd values, reactive surface areas of particles, inter-correlations in closed data set) can, however, influence the observed relationships and thus hamper the interpretation of these correlation coefficients as a measure of relative scavenging affinities of the nuclides to the particle types investigated. The mean fractionation factor ( F(Pa/Th)= Kd(Pa)/ Kd(Th)) from the Equatorial Pacific ( F=0.11±0.03) is similar to that from the North Atlantic ( F(Pa/Th)=0.077±0.026), and both are lower than the factors from the Arabian Sea ( F(Pa/Th)=0.35±0.12) and from the Southern Ocean ( F(Pa/Th)=0.87±0.4). For opal concentrations exceeding

  2. Tritirachium candoliense sp. nov., a novel basidiomycetous fungus isolated from the anoxic zone of the Arabian Sea.

    PubMed

    Manohar, Cathrine Sumathi; Boekhout, Teun; Müller, Wally H; Stoeck, Thorsten

    2014-02-01

    A fungal culture (FCAS11) was isolated from coastal sediments of the Arabian Sea during the anoxic season. Multigene phylogenetic analyses confidentially place the organism as a novel species within the recently defined class Tritirachiomycetes, subphylum Pucciniomycotina, phylum Basidiomycota. We named the new species Tritirachium candoliense and provide the first description of a member of this class from a marine environment. DNA sequences and morphological characters distinguish T. candoliense from previously described Tritirachium species. Its growth characteristics, morphology, and ultrastructural features showed that under anoxic conditions the species grows slowly and produces mainly hyphae with only few blastoconidia. Electron microscopy revealed differences when the culture was exposed to anoxic stress. Notable ultrastructural changes occur for example in mitochondrial cristae, irregularly shaped fat globules and the presence of intracellular membrane invaginations. We assume that the growth characteristics and substrate utilization patterns are an adaptation to its source location, the seasonally anoxic environment of the Arabian Sea.

  3. Modeling a Typical Winter-time Dust Event over the Arabian Peninsula and the Red Sea

    SciTech Connect

    Kalenderski, S.; Stenchikov, G.; Zhao, Chun

    2013-02-20

    We used WRF-Chem, a regional meteorological model coupled with an aerosol-chemistry component, to simulate various aspects of the dust phenomena over the Arabian Peninsula and Red Sea during a typical winter-time dust event that occurred in January 2009. The model predicted that the total amount of emitted dust was 18.3 Tg for the entire dust outburst period and that the two maximum daily rates were ~2.4 Tg/day and ~1.5 Tg/day, corresponding to two periods with the highest aerosol optical depth that were well captured by ground- and satellite-based observations. The model predicted that the dust plume was thick, extensive, and mixed in a deep boundary layer at an altitude of 3-4 km. Its spatial distribution was modeled to be consistent with typical spatial patterns of dust emissions. We utilized MODIS-Aqua and Solar Village AERONET measurements of the aerosol optical depth (AOD) to evaluate the radiative impact of aerosols. Our results clearly indicated that the presence of dust particles in the atmosphere caused a significant reduction in the amount of solar radiation reaching the surface during the dust event. We also found that dust aerosols have significant impact on the energy and nutrient balances of the Red Sea. Our results showed that the simulated cooling under the dust plume reached 100 W/m2, which could have profound effects on both the sea surface temperature and circulation. Further analysis of dust generation and its spatial and temporal variability is extremely important for future projections and for better understanding of the climate and ecological history of the Red Sea.

  4. CHEMTAX-derived phytoplankton community structure associated with temperature fronts in the northeastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Roy, Rajdeep; Chitari, Rajath; Kulkarni, Vinayak; Krishna, M. S.; Sarma, V. V. S. S.; Anil, A. C.

    2015-04-01

    Remotely sensed sea surface temperature (SST) and chlorophyll associated with fronts and filaments are used in India to generate potential fishing zone (PFZ) advisories in the north eastern Arabian Sea (NEAS). However, biological response to this potential nutrient enhancement has not been investigated. Here we present phytoplankton pigment signatures and nutrient distribution from a section that sampled across a filament and front in the NEAS. We show that nutrient concentrations were high within the filament and front compared to the surrounding waters and had a unique phytoplankton assemblage. Even though there was difference in the physical properties between the filament and front, chemical taxonomy (CHEMTAX) showed dominance of similar phytoplankton groups (prymnesiophytes and prasinophytes). In contrast, Prochlorococcus sp. contributed more than 50% to the total phytoplankton biomass in the surrounding waters and below the oxycline. In general, prymnesiophytes were ubiquitous, covarying with high nutrients and cold temperature, and contributed 60-70% to the total phytoplankton biomass. This study demonstrates that phytoplankton groups respond strongly to nutrient enhancement that is often encountered within the vicinity of the SST fronts that characterize the PFZs.

  5. Modeling of circulation in the Arabian Gulf and the Sea of Oman: Skill assessment and seasonal thermohaline structure

    NASA Astrophysics Data System (ADS)

    Al Azhar, Muchamad; Temimi, Marouane; Zhao, Jun; Ghedira, Hosni

    2016-03-01

    Hindcast simulations of the Arabian Gulf and the Sea of Oman using the Regional Ocean Modeling System (ROMS) are quantitatively evaluated with basin-wide hydrographic data and time series measurements. The model shows comparable skill in reproducing moored observations of current velocities structure in upper and bottom depths. The skill in simulating observed temperature is higher of 0.93 (scale 0-1) in upper depths compared to 0.52 in bottom depths. Model results are sensitive to parameterization of water clarity. A lower sensitivity was noticed to KPP, GLS, and MY2.5 turbulence closures. When coastal turbid water parameterization is used, accuracy of the model in reproducing seasonal and spatial variations of temperature and salinity increased by 25% compared to the clear water case whereas only 10% increase was noticed when applying KPP turbulent closure. The model reproduces well anticlockwise circulation in the Gulf. A stronger surface inflow of fresher water to the Arabian Gulf through the Strait of Hormuz is simulated in summer compared to winter conditions, mainly due to upper layer horizontal gradient of density between the Arabian Gulf and the Sea of Oman. Less seasonal variability of outflow between 0.15 and 0.20 m s-1 at 50 m to bottom depth around the Strait of Hormuz was noticed in the model results. Modeled surface layer stratification is stronger in summer than winter and varies spatially in the Arabian Gulf with highest stratification near the Strait of Hormuz. Overall, the stratification in shallow water area of the Arabian Gulf remains low throughout the year.

  6. Mesopelagic fishes of the Arabian Sea: distribution, abundance and diet of Chauliodus pammelas, Chauliodus sloani, Stomias affinis, and Stomias nebulosus

    NASA Astrophysics Data System (ADS)

    Butler, Mari; Bollens, Stephen M.; Burkhalter, Brenda; Madin, Laurence P.; Horgan, Erich

    Four species of predatory fishes - Chauliodus pammelas, Chauliodus sloani, Stomias affinis and Stomias nebulosus - were collected on two cruises to the Arabian Sea during 1995. We present data on the abundances, horizontal and vertical distributions, and diet of these fishes. We also discuss briefly the importance of the oxygen minimum zone and predation on myctophid fishes to the ecology of these mesopelagic predators. Chauliodus pammelas and C. sloani appear to have only partially overlapping horizontal distributions in the Arabian Sea, with C. pammelas more common to the north and C. sloani more common to the south. Our data support previous results suggesting that diel vertical migration is the norm for these species, with smaller individuals usually nearer to the surface and larger individuals tending to stay deeper. In contrast to Chauliodus, Stomias affinis and S. nebulosus appear to have largely overlapping horizontal distributions in the Arabian Sea. However, they may have slightly different vertical distributions, with S. affinis living slightly shallower (especially at night) than S. nebulosus. All four species spend most of their time in the oxygen minimum zone, entering the surface oxygenated waters (100-150 m) only at night (if at all). The diets of C. pammelas, C. sloani, and S. affinis consisted mainly of lanternfishes, Myctophidae, and other fishes. In contrast, S. nebulosus, the smaller of the two Stomias species, ate mostly copepods and other crustaceans. This differential feeding may allow the two Stomias species to co-occur. Three of these four stomiids appear to play an important role in predation on myctophid fish populations in the Arabian Sea.

  7. Heavy metals in fish from the Red Sea, Arabian Sea, and Indian Ocean: effect of origin, fish species and size and correlation among the metals.

    PubMed

    Obaidat, Mohammad M; Massadeh, Adnan M; Al-Athamneh, Ahmad M; Jaradat, Qasem M

    2015-04-01

    This study determined the levels of As, Cu, Pb, and Cd in fish from Red Sea, Arabian Sea, and Indian Ocean by graphite furnace atomic absorption spectrophotometry. Metal levels were compared with international standards. The levels among fish types and origin, the relationship among metals, and the correlation between the levels and fish size were statistically tested. Fish type and origin significantly affected the levels. None of the fish contained As, Cu, and Pb above the FAO and EU codes. However, Cd exceeded the Jordanian, FAO, and EC codes from the three origins. As and Cd positively correlated with each other in Arabian Sea fish. As and Pb correlated negatively, but Cu and Cd did not correlate with fish size. This study indicates that Cd is common in fish from the three origins regardless the fish size. This warrants continuous monitoring for heavy metals, especially Cd, in internationally traded fish.

  8. Heavy metals in fish from the Red Sea, Arabian Sea, and Indian Ocean: effect of origin, fish species and size and correlation among the metals.

    PubMed

    Obaidat, Mohammad M; Massadeh, Adnan M; Al-Athamneh, Ahmad M; Jaradat, Qasem M

    2015-04-01

    This study determined the levels of As, Cu, Pb, and Cd in fish from Red Sea, Arabian Sea, and Indian Ocean by graphite furnace atomic absorption spectrophotometry. Metal levels were compared with international standards. The levels among fish types and origin, the relationship among metals, and the correlation between the levels and fish size were statistically tested. Fish type and origin significantly affected the levels. None of the fish contained As, Cu, and Pb above the FAO and EU codes. However, Cd exceeded the Jordanian, FAO, and EC codes from the three origins. As and Cd positively correlated with each other in Arabian Sea fish. As and Pb correlated negatively, but Cu and Cd did not correlate with fish size. This study indicates that Cd is common in fish from the three origins regardless the fish size. This warrants continuous monitoring for heavy metals, especially Cd, in internationally traded fish. PMID:25822330

  9. Iron bacterial phylogeny and their execution towards iron availability in Equatorial Indian Ocean and coastal Arabian Sea.

    PubMed

    Rajasabapathy, Raju; Mohandass, Chellandi; Vijayaraj, Ajakkalamoole Srinivas; Madival, Varsha Vinayak; Meena, Ram Murti

    2013-01-01

    Based on distinct colony morphology, color, size, shape and certain other traits, 92 bacterial isolates were investigated to understand their managerial ability on iron from the Arabian Sea and Equatorial Indian Ocean samples. The ARDRA (amplified rDNA restriction analysis) applied to eliminate the duplication of the bacterial strains, resulted 39 different banding patterns. The 16S rRNA gene sequencing data indicate the dominancy of three phylogenetic groups, alpha-Proteobacteria (10.25%), gamma-Proteobacteria (35.89%) and Bacilli (53.84%) in these waters. Marinobacter and Bacillus were the only common genera from both of the regions. Pseudoalteromonas, Halomonas, Rheinheimera, Staphylococcus and Idiomarina were some of the other genera obtained from the Arabian Sea. Erythrobacter, Roseovarius, Sagittula and Nitratireductor were found mostly in Equatorial Indian Ocean. In addition, 16S rRNA gene sequence data of some of our iron bacterial strains belong to novel species and one isolate ASS2A could form a new genus. Close to 23% of the isolates were able to produce high affinity sets of ligands like siderophores to mediate iron transport into the cell. The current study indicated that the Equatorial Indian Ocean species were well adapted to oxidize iron as an electron acceptor and the Arabian Sea species preferably go through siderophore production.

  10. A four-dimensional validation of a coupled physical-biological model of the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Hood, Raleigh R.; Kohler, Kevin E.; McCreary, Julian P.; Smith, Sharon L.

    2003-11-01

    In this paper, we use a coupled biological/physical model to synthesize and understand observations taken during the US JGOFS Arabian Sea Process Study (ASPS). Its physical component is a variable-density, 4 1/2-layer model; its biological component consists of a set of advective-diffusive equations in each layer that determine nitrogen concentrations in four compartments, namely, nutrients, phytoplankton, zooplankton, and detritus. Solutions are compared to time series and cruise sections from the ASPS data set, including observations of mixed-layer thickness, chlorophyll concentrations, inorganic nitrogen concentrations, particulate nitrogen export flux, zooplankton biomass, and primary production. Through these comparisons, we adjust model parameters to obtain a "best-fit" main-run solution, identify key biological and physical processes, and assess model strengths and weaknesses. Substantial improvements in the model/data comparison are obtained by: (1) adjusting the turbulence-production coefficients in the mixed-layer model to thin the mixed layer; (2) increasing the detrital sinking and remineralization rates to improve the timing and amplitude of the model's export flux; and (3) introducing a parameterization of particle aggregation to lower phytoplankton concentrations in coastal upwelling regions. With these adjustments, the model captures many key aspects of the observed physical and biogeochemical variability in offshore waters, including the near-surface DIN and phytoplankton P concentrations, mesozooplankton biomass, and primary production. Nevertheless, there are still significant model/data discrepancies of P for most of the cruises. Most of them can be attributed to forcing or process errors in the physical model: inaccurate mixed-layer thicknesses, lack of mesoscale eddies and filaments, and differences in the timing and spatial extent of coastal upwelling. Relatively few are clearly related to the simplicity of the biological model, the model

  11. SSMI Wind Speed Climatology of the Time of Monsoon Wind Offset in the Western Arabian Sea

    NASA Technical Reports Server (NTRS)

    Halpern, David

    2000-01-01

    Forecasting the time of onset of monsoon wind in the western Arabian Sea, which is believed to precede the onset of rainfall along the west coast of India, is an important unsolved problem. Prior to measurements of the surface wind field by satellite, there was an absence of suitable surface wind observations. NASA scatterometer (NSCAT) surface wind vectors revealed that the time of the 1997 onset of 12 m/s southwest monsoon wind speeds in the western Arabian Sea preceded the onset of monsoon rainfall in Goa, India, by 3 - 4 days. Wind speed and direction data were necessary to establish a dynamical mechanism between times of onset of 12 m/s wind speed off Somalia and rainfall in Goa. Except for NSCAT, no satellite scatterometer wind product recorded adequately sampled 2-day 1deg x 1deg averaged wind vectors, which are the required space and time scales, to examine the wind-rain relationship in other years. However, the greater-than-95% steadiness of summer monsoon winds allows an opportunity to use satellite measurements of surface wind speed. The Special Sensor Microwave Imager (SSMI) recorded surface wind speed with adequate sampling to produce a 1-day, 1deg x 1deg data product during 1988 - 1998. SSMI data had been uniformly processed throughout the period. Times of onset of 12 m/s wind speed off Somalia determined with the SSMI data set were 21 May 1988, 24 May 1989, 17 May 1990, 28 May 1991, 8 June 1992, 28 May 1993, 30 May 1994, 7 June 1995, 29 May 1996, 12 June 1997, and 15 May 1998. Uncertainty of the 1992 and 1996 times of onset were increased because of the absence of SSMI data on 6 and 7 June 1992 and on 30 May 1996. Correlations of timing of monsoon wind onset with El Nino will be described. Variability of the time difference between times of onset of 12 m/s wind speed and Goa rainfall will be discussed. At the time of submission of the abstract, the Goa rainfall data have not arrived from the India Meteorological Department.

  12. The trophic and metabolic pathways of foraminifera in the Arabian Sea: evidence from cellular stable isotopes

    NASA Astrophysics Data System (ADS)

    Jeffreys, R. M.; Fisher, E. H.; Gooday, A. J.; Larkin, K. E.; Billett, D. S. M.; Wolff, G. A.

    2015-03-01

    The Arabian Sea is a region of elevated productivity with the highest globally recorded fluxes of particulate organic matter (POM) to the deep ocean, providing an abundant food source for fauna at the seafloor. However, benthic communities are also strongly influenced by an intense oxygen minimum zone (OMZ), which impinges on the continental slope from 100 to 1000 m water depth. We compared the trophic ecology of foraminifera on the Oman and Pakistan margins of the Arabian Sea (140-3185 m water depth). These two margins are contrasting both in terms of the abundance of sedimentary organic matter and the intensity of the OMZ. Organic carbon concentrations of surficial sediments were higher on the Oman margin (3.32 ± 1.4%) compared to the Pakistan margin (2.45 ± 1.1%) and sedimentary organic matter (SOM) quality estimated from the Hydrogen Index was also higher on the Oman margin (300-400 mg HC mg TOC-1) compared to the Pakistan margin (< 250 mg HC mg TOC-1). The δ13C and δ15N values of sediments were similar on both margins (-20 and 8‰, respectively). Stable isotope analysis (SIA) showed that foraminiferal cells had a wide range of δ13C values (-25.5 to -11.5‰), implying that they utilise multiple food sources; indeed δ13C values varied between depths, foraminiferal types and between the two margins. Foraminifera had broad ranges in δ15N values (-7.8 to 27.3‰). The enriched values suggest that some species may store nitrate to utilise in respiration; this was most notable on the Pakistan margin. Depleted foraminiferal δ15N values, particularly at the Oman margin, may reflect feeding on chemosynthetic bacteria. We suggest that differences in productivity regimes may be responsible for the differences observed in foraminiferal isotopic composition. In addition, at the time of sampling, whole jellyfish carcasses (Crambionella orsini) and a carpet of jelly detritus were observed across the Oman margin transect. Associated chemosynthetic bacteria may have

  13. The trophic and metabolic pathways of foraminifera in the Arabian Sea: evidence from cellular stable isotopes

    NASA Astrophysics Data System (ADS)

    Jeffreys, R. M.; Fisher, E. H.; Gooday, A. J.; Larkin, K. E.; Wolff, G. A.; Billett, D. S. M.

    2014-12-01

    The Arabian Sea is a region of elevated productivity with the highest globally recorded fluxes of particulate organic matter (POM) to the deep ocean, providing an abundant food source for fauna at the seafloor. However, benthic communities are also strongly influenced by an intense oxygen minimum zone (OMZ), which impinges on the continental slope at bathyal depths. We compared the trophic ecology of foraminifera on the Oman and Pakistan margins of the Arabian Sea (140-3185 m water depth). Organic carbon concentrations of surficial sediments were higher on the Oman margin (3.32 ± 1.4%) compared to the Pakistan margin (2.45 ± 1.1%) and sedimentary organic matter (SOM) quality estimated from the Hydrogen Index was also higher on the Oman margin (300-400 mg HC (mg TOC)-1) compared to the Pakistan margin (<250 mg HC (mg TOC)-1). δ13C and δ15N values of sediments were similar on both margins (-20 and 8‰, respectively). Stable isotope analysis (SIA) showed that foraminiferal cells had a wide range of δ13C values (-25.5 to -11.5‰), implying that they utilise multiple food sources; indeed δ13C values varied between depths, foraminiferal types and between the two margins. Foraminifera had broad ranges in δ15N values (-7.8 to 27.3‰). The enriched values suggest that some species may store nitrate to utilise in respiration; this was most notable on the Pakistan margin. Depleted foraminiferal δ15N values were identified on both margins, particularly the Oman margin, and may reflect feeding on chemosynthetic bacteria. We suggest that differences in productivity regimes between the two margins may be responsible for the differences observed in foraminiferal isotopic composition. In addition, at the time of sampling, whole jellyfish carcasses (Crambionella orsini) and a carpet of jelly detritus were observed across the Oman margin transect. Associated chemosynthetic bacteria may have provided an organic-rich food source for foraminifera at these sites. Our data

  14. Residence time of pollutants discharged in the Gulf of Kachchh, northwestern Arabian Sea.

    PubMed

    Patgaonkar, Rupali S; Vethamony, P; Lokesh, K S; Babu, M T

    2012-08-01

    A 2D Hydrodynamic-Particle Analysis model was applied to the Gulf of Kachchh (GoK) to estimate the residence time of pollutants. The tidal currents in the Gulf have a strong E-W component, which prevents the material in the north being transported towards south. In the regions situated very close to the open boundary, where the GoK waters exchange freely with the northern Arabian Sea, dilution takes place rapidly with the incoming waters and hence, the residence time is on the order of 1 day. Influence of eddies and a dynamic barrier across the Sikka-Mundra section on the residence time is apparent. Eastern GoK shows a relatively large residence time, on the order of 2-4 days, warranting caution while releasing industrial wastes in the northeastern Gulf. The region around location-5 behaves like a bay; the dissolved matter gets trapped in this bay and the residence time increases by 3-4 days.

  15. Evidence for the direct oxidation of organic nitrogen to N2 gas in the Arabian Sea.

    PubMed

    Trimmer, Mark; Purdy, Kevin J

    2012-09-01

    We performed a suite of (15)N incubations ((15)NO(2)(-), (15)NO(3)(-) and (15)NH(4)(+)) with and without the organic-nitrogen (N) compound allylthiourea (ATU), in the suboxic waters of the Arabian Sea. Production of (29)N(2) in control (-ATU) incubations with either (15)NH(4)(+)+(14)NO(2)(-), or their analogues, (15)NO(2)(-)+(14)NH(4)(+), though small, confirmed the presence of anammox. In contrast, when we added ATU, along with (15)NO(2)(-) and (14)NH(4)(+), there was a much greater production of (29)N(2), with 92% of the (15)N-label being recovered as (29)N(2) on average. Such stimulated production of (29)N(2) could not be due to anammox, as the addition of ATU, along with (15)NH(4)(+)+(14)NO(2)(-), only produced (29)N(2) equivalent to that in the controls. The ratios of (29)N(2) to (30)N(2) produced also precluded stimulation of denitrification. We present this as evidence for a hitherto uncharacterised metabolism potentially capable of oxidising organic-N (e.g. NH(2) groups) directly to N(2) gas at the expense of NO(2)(-).

  16. Trace metals health risk appraisal in fish species of Arabian Sea.

    PubMed

    Yasmeen, Kousar; Mirza, Muhammad Aslam; Khan, Namra A; Kausar, Nazish; Rehman, Atta-Ur; Hanif, Muddasir

    2016-01-01

    Fish is a vital food for humans and many animals. We report an environmental monitoring study to assess the trace metals in fish species caught from Arabian Sea and commercially available in the coastal city Karachi, Pakistan. Heavy metals such as copper, iron, lead and cadmium were determined in the skin, fillet and heart of the fish species Pampus argenteus, Epinephelus chlorostigma, Rachycentron canadum, Scomberomorus commerson, Johnius belangerii, Labeo rohita, Lutjanus argentimaculatus, Trachinotus blochii, Pomadsys olivaceum and Acanthopagrus berda by the atomic absorption spectrophotometer. The concentration (mg kg(-1), dry weight) range was: Cd (0.00-0.041), Cu (0.006-0.189), Fe (0.413-4.952) and Pb (0.00-0.569). Cadmium, copper and iron levels were below the tolerable limits whereas concentration of lead in the skins of S. commerson, E. chlorostigma, J. belangerii, A. berda; L. argentimaculatus, fillets of J. belangerii, E. chlorostigma and in the heart of J. belangerii exceeded the recommended limits. Therefore fish skin should be discouraged as food for humans or animals. The results indicate that a number of fish species have higher concentration of heavy metals dangerous for human health. Since the fish P. olivaceum (Dhotar) has the lowest level of trace metals therefore we recommend it for breeding and human consumption.

  17. Species identification of mixed algal bloom in the Northern Arabian Sea using remote sensing techniques.

    PubMed

    Dwivedi, R; Rafeeq, M; Smitha, B R; Padmakumar, K B; Thomas, Lathika Cicily; Sanjeevan, V N; Prakash, Prince; Raman, Mini

    2015-02-01

    Oceanic waters of the Northern Arabian Sea experience massive algal blooms during winter-spring (mid Feb-end Mar), which prevail for at least for 3 months covering the entire northern half of the basin from east to west. Ship cruises were conducted during winter-spring of 2001-2012 covering different stages of the bloom to study the biogeochemistry of the region. Phytoplankton analysis indicated the presence of green tides of dinoflagellate, Noctiluca scintillans (=N. miliaris), in the oceanic waters. Our observations indicated that diatoms are coupled and often co-exist with N. scintillans, making it a mixed-species ecosystem. In this paper, we describe an approach for detection of bloom-forming algae N. scintillans and its discrimination from diatoms using Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua data in a mixed-species environment. In situ remote sensing reflectance spectra were generated using Satlantic™ hyperspectral radiometer for the bloom and non-bloom waters. Spectral shapes of the reflectance spectra for different water types were distinct, and the same were used for species identification. Scatter of points representing different phytoplankton classes on a derivative plot revealed four diverse clusters, viz. N. scintillans, diatoms, non-bloom oceanic, and non-bloom coastal waters. The criteria developed for species discrimination were implemented on MODIS data and validated using inputs from a recent ship cruise conducted in March 2013.

  18. Transcriptionally active heterotrophic diazotrophs are widespread in the upper water column of the Arabian Sea.

    PubMed

    Bird, Clare; Wyman, Michael

    2013-04-01

    Pelagic nitrogen fixation makes an important contribution to the fixed nitrogen budget of the world's oceans. Filamentous and unicellular cyanobacteria are significant players in this process but less is known of the potential activity of heterotrophic diazotrophs, although they are present and can be quite numerous in the nitrogen-deplete surface waters of the tropical and sub-tropical oceans. In this study we focused on the potential activity of several clades of heterotrophic nitrogen-fixers identified by phylogenetic analysis of 44 non-Trichodesmium-related, nifH (encoding the Fe-subunit of nitrogenase) clones from the Arabian Sea. Specific Northern slot blot protocols were developed to quantify nifH mRNAs from each clade and showed that two groups of Gammaproteobacteria, including the previously characterized UMB clade, and a third, novel phylotype affiliated with cluster III anaerobes, were actively expressing nitrogenase in the equatorial waters of this region. Transcripts (nifH mRNAs) from the latter clade were particularly abundant and were also detected in the suboxic waters of the oxygen minimum zone further north. Like the gammaproteobacterial groups, nifH expression by these organisms appeared to be insensitive to combined nitrogen concentrations and was readily detected in the nutrient-replete waters below the upper mixed layer as well as at shallower depths.

  19. Potential new production in two upwelling regions of the western Arabian Sea: Estimation and comparison

    NASA Astrophysics Data System (ADS)

    Liao, Xiaomei; Zhan, Haigang; Du, Yan

    2016-07-01

    Using satellite-derived and in situ data, the wind-driven potential new production (nitrate supply) for the 300 km wide coastal band in two upwelling regions of the western Arabian Sea (AS) during the southwest monsoon is estimated. The upward nitrate flux to the euphotic zone is generally based on the physical processes of coastal transport (Ekman transport and geostrophic transport) and offshore Ekman pumping. The coastal geostrophic current in the western AS influences the upwelling intensity and latitudinal distributions of nitrate supply. The Oman and Somalia upwelling regions have similar level of potential new production (nitrate supply) during the summer monsoon, while the satellite estimates of primary production off Oman are 2 times greater than those off Somalia. The much higher potential f-ratio in the Somalia upwelling region indicates that the primary production could be limited by availability of other macronutrients (e.g., silicate). The correlation analysis of the primary production and the aerosol optical thickness shows that the Oman upwelling region displays a stronger coupling between the atmospheric deposition and the phytoplankton abundance. The high summertime dust levels in the atmosphere are suggested to contribute to the high primary production in the Oman upwelling region.

  20. Quantification of new production during a winter Noctiluca scintillans bloom in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Prakash, Satya; Ramesh, R.; Sheshshayee, M. S.; Dwivedi, R. M.; Raman, Mini

    2008-04-01

    We present new data on the nitrate (new production), ammonium, urea uptake rates and f-ratios for the eastern Arabian Sea (10° to 22°N) during the late winter (northeast) monsoon, 2004, including regions of green Noctiluca scintillans bloom. A comparison of N-uptake rates of the Noctiluca dominated northern zone to the southern non-bloom zone indicates the presence of two biogeochemical regimes during the late winter monsoon: highly productive north and less productive south. The conservative estimates of photic zone-integrated total N-uptake and f-ratio are high in the north (~19 mmolNm-2d-1 and 0.82, respectively) during the bloom and low (~5.5 mmolNm-2d-1 and 0.38 respectively) in the south. The present and earlier data imply persistence of high N-uptake and f-ratio during blooms year after year. This quantification of the enhanced seasonal sequestration of carbon is an important input to global biogeochemical models.

  1. Species identification of mixed algal bloom in the Northern Arabian Sea using remote sensing techniques.

    PubMed

    Dwivedi, R; Rafeeq, M; Smitha, B R; Padmakumar, K B; Thomas, Lathika Cicily; Sanjeevan, V N; Prakash, Prince; Raman, Mini

    2015-02-01

    Oceanic waters of the Northern Arabian Sea experience massive algal blooms during winter-spring (mid Feb-end Mar), which prevail for at least for 3 months covering the entire northern half of the basin from east to west. Ship cruises were conducted during winter-spring of 2001-2012 covering different stages of the bloom to study the biogeochemistry of the region. Phytoplankton analysis indicated the presence of green tides of dinoflagellate, Noctiluca scintillans (=N. miliaris), in the oceanic waters. Our observations indicated that diatoms are coupled and often co-exist with N. scintillans, making it a mixed-species ecosystem. In this paper, we describe an approach for detection of bloom-forming algae N. scintillans and its discrimination from diatoms using Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua data in a mixed-species environment. In situ remote sensing reflectance spectra were generated using Satlantic™ hyperspectral radiometer for the bloom and non-bloom waters. Spectral shapes of the reflectance spectra for different water types were distinct, and the same were used for species identification. Scatter of points representing different phytoplankton classes on a derivative plot revealed four diverse clusters, viz. N. scintillans, diatoms, non-bloom oceanic, and non-bloom coastal waters. The criteria developed for species discrimination were implemented on MODIS data and validated using inputs from a recent ship cruise conducted in March 2013. PMID:25638059

  2. Trace metals health risk appraisal in fish species of Arabian Sea.

    PubMed

    Yasmeen, Kousar; Mirza, Muhammad Aslam; Khan, Namra A; Kausar, Nazish; Rehman, Atta-Ur; Hanif, Muddasir

    2016-01-01

    Fish is a vital food for humans and many animals. We report an environmental monitoring study to assess the trace metals in fish species caught from Arabian Sea and commercially available in the coastal city Karachi, Pakistan. Heavy metals such as copper, iron, lead and cadmium were determined in the skin, fillet and heart of the fish species Pampus argenteus, Epinephelus chlorostigma, Rachycentron canadum, Scomberomorus commerson, Johnius belangerii, Labeo rohita, Lutjanus argentimaculatus, Trachinotus blochii, Pomadsys olivaceum and Acanthopagrus berda by the atomic absorption spectrophotometer. The concentration (mg kg(-1), dry weight) range was: Cd (0.00-0.041), Cu (0.006-0.189), Fe (0.413-4.952) and Pb (0.00-0.569). Cadmium, copper and iron levels were below the tolerable limits whereas concentration of lead in the skins of S. commerson, E. chlorostigma, J. belangerii, A. berda; L. argentimaculatus, fillets of J. belangerii, E. chlorostigma and in the heart of J. belangerii exceeded the recommended limits. Therefore fish skin should be discouraged as food for humans or animals. The results indicate that a number of fish species have higher concentration of heavy metals dangerous for human health. Since the fish P. olivaceum (Dhotar) has the lowest level of trace metals therefore we recommend it for breeding and human consumption. PMID:27386308

  3. Correlation between some selected trace metal concentrations in six species of fish from the Arabian Sea

    SciTech Connect

    Ashraf, M.; Jaffar, M.

    1988-07-01

    The role of trace metals in marine ecosystems has been keenly investigated during recent years. It is known that abundance of essential trace metals regulates the metal content in the organisms by homeostatic control mechanisms, which when cease to function cause essential trace metals to act in an either acutely or chronically toxic manner. Therefore, a correlation study based on essential and non-essential trace metal concentrations is imperative for extending the existing knowledge of bioaccumulation of trace metals in marine organisms. An attempt has been made in the present investigation to bring out quantitative correlations between the concentrations of iron, copper, lead and zinc in the edible muscle tissue of six species of marine fish: Salmon (salmon sole); tuna (thunnus thynnus); pomfret silver (pampus argenteus); Pomfret black (formioniger); long tail tuna (thynnus tonggel) and Indian oil sardine (sardinella longiceps). These fish are abundantly available in Pakistan along the coastal line of the Arabian Sea and have great commercial value. The computational analysis on the trace metal correlation was conducted using an MSTAT statistical package.

  4. Short-term fate of phytodetritus in sediments across the Arabian Sea Oxygen Minimum Zone

    NASA Astrophysics Data System (ADS)

    Andersson, J. H.; Woulds, C.; Schwartz, M.; Cowie, G. L.; Levin, L. A.; Soetaert, K.; Middelburg, J. J.

    2008-01-01

    The short-term fate of phytodetritus was investigated across the Pakistan margin of the Arabian Sea at water depths ranging from 140 to 1850 m, encompassing the oxygen minimum zone (~100-1100 m). Phytodetritus sedimentation events were simulated by adding ~44 mmol 13C-labelled algal material per m2 to surface sediments in retrieved cores. Cores were incubated in the dark, at in situ temperature and oxygen concentrations. Overlying waters were sampled periodically, and cores were recovered and sampled (for organisms and sediments) after durations of two and five days. The labelled carbon was subsequently traced into bacterial lipids, foraminiferan and macrofaunal biomass, and dissolved organic and inorganic pools. The majority of the label (20 to 100%) was in most cases left unprocessed in the sediment at the surface. The largest pool of processed carbon was found to be respiration (0 to 25% of added carbon), recovered as dissolved inorganic carbon. Both temperature and oxygen were found to influence the rate of respiration. Macrofaunal influence was most pronounced at the lower part of the oxygen minimum zone where it contributed 11% to the processing of phytodetritus.

  5. Short-term fate of phytodetritus across the Arabian Sea Oxygen Minimum Zone

    NASA Astrophysics Data System (ADS)

    Andersson, J. H.; Woulds, C.; Schwartz, M.; Cowie, G. L.; Levin, L. A.; Soetaert, K.; Middelburg, J. J.

    2007-07-01

    The short-term fate of phytodetritus was investigated across the Pakistan margin of the Arabian Sea at water depths ranging from 140 to 1850 m, encompassing the oxygen minimum zone (~100-1100 m). Phytodetritus sedimentation events were simulated by adding 13C-labelled algal material to surface sediments in retrieved cores. Cores were incubated at in situ temperature and oxygen concentrations. Overlying waters were sampled periodically, and cores were recovered and sampled (for organisms and sediments) after durations of two and five days. The labelled carbon was subsequently traced into bacterial lipids, foraminiferan and macrofaunal biomass, and dissolved organic and inorganic pools. The majority of the label was left unprocessed in the sediment at the surface. The largest pool of processed carbon was found to be respiration, recovered as dissolved inorganic carbon. Both temperature and oxygen were found to influence the rate of respiration. Macrofaunal influence was most pronounced at the lower part of the oxygen minimum zone where it dominated the processing of phytodetritus.

  6. Evolution to decay of upwelling and associated biogeochemistry over the southeastern Arabian Sea shelf

    NASA Astrophysics Data System (ADS)

    Gupta, G. V. M.; Sudheesh, V.; Sudharma, K. V.; Saravanane, N.; Dhanya, V.; Dhanya, K. R.; Lakshmi, G.; Sudhakar, M.; Naqvi, S. W. A.

    2016-01-01

    Observations along 10 shelf transects in 2012 near 10°N in the southeastern Arabian Sea revealed the usual warm oligotrophic conditions during the winter monsoon and upwelling of oxygen-deficient, nutrient-rich cool water during the summer monsoon (SM). By changing an oligotrophic to a nutrient-replete condition, the upwelling is the major process that regulates the biogeochemistry of this shelf. Its onset is perceptible at 100 m depth between January and March. The upwelling reaches the surface layer in May and intensifies during June-July but withdraws completely and abruptly by October. Despite the nutrient injection, the primary production during SM, integrated for euphotic zone, is comparable to that during the preceding spring intermonsoon (SIM). Again, as usual, the high oxygen demand coupled with low concentration in the upwelled subsurface waters causes severe oxygen depletion below the shallow pycnocline. The oxygen concentrations/saturations of 2012 on the midshelf are similar from those of mid-1958 to early 1960, except for marginally higher values during the peak upwelling period due to relatively weak upwelling in 2012. This implies little anthropogenic influence on coastal hypoxia unlike many other coastal regions. In 2012, the inner shelf system shifted from net autotrophy in SIM to net heterotrophy in SM but on an annual basis it was net autotrophic (gross primary production to community respiration ratio, GPP/R:1.11 ± 0.84) as organic production exceeded consumption.

  7. Seismic anisotropy and subduction-induced mantle fabrics beneath the Arabian and Nubian Plates adjacent to the Red Sea

    NASA Astrophysics Data System (ADS)

    Elsheikh, Ahmed A.; Gao, Stephen S.; Liu, Kelly H.; Mohamed, Abdelnasser A.; Yu, Youqiang; Fat-Helbary, Raafat E.

    2014-04-01

    For most continental areas, the mechanisms leading to mantle fabrics responsible for the observed anisotropy remain ambiguous, partially due to the lack of sufficient spatial coverage of reliable seismological observations. Here we report the first joint analysis of shear-wave splitting measurements obtained at stations on the Arabian and Nubian Plates adjacent to the Red Sea. More than 1100 pairs of high-quality splitting parameters show dominantly N-S fast orientations at all 47 stations and larger-than-normal splitting times beneath the Afro-Arabian Dome (AAD). The uniformly N-S fast orientations and large splitting times up to 1.5 s are inconsistent with significant contributions from the lithosphere, which is about 50-80 km thick beneath the AAD and even thinner beneath the Red Sea. The results can best be explained by simple shear between the lithosphere and the asthenosphere associated with northward subduction of the African/Arabian Plates over the past 150 Ma.

  8. The Lighthouse Ocean Research Initiative: Sustained Cabled Ocean Observing Systems in the Sea of Oman and Arabian Sea

    NASA Astrophysics Data System (ADS)

    Ingle, S.; Du Vall, K.; Dimarco, S. F.

    2011-12-01

    In 2003 Lighthouse R & D Enterprises, Inc. began developing an ocean observing system that would help the Sultanate of Oman better manage the health of their fisheries. The resulting cutting-edge, fiber-optic cabled ocean observatory was installed in the northern Sea of Oman and became operational in August of 2005; this summer the system surpassed the milestone of 2100 days of successful operation. A second, deepwater cabled observatory was installed farther to the south, where the Sea of Oman meets the Arabian Sea, in January, 2010. Both systems monitor physical properties throughout the water column including current velocity, temperature, pressure, conductivity, dissolved oxygen and turbidity. The entirely subsea nature of the fiber-optic cabled observatory capitalizes on several advantages over traditional buoyed systems including a lack of exposure to environmental wear and tear, collision, vandalism and theft. The systems are both cabled to nearby shore facilities, where the data are relayed instantly to Houston via satellite for processing, analysis and modeling - the data may also be used in making real time decisions. Many challenges were encountered between the design / development stage and the operation a reliable, long-term, real-time observing system in a dynamic marine environment. Examples of obstacles we encountered and overcame include: maintaining upright mooring strings under differential current velocities; minimizing points of weakness in the system, especially the number of wet mates; recognizing the need for cathodic protection in unanticipated places; protecting vulnerable sensors from biofouling; developing a climate-controlled shore facility in a harsh and remote environment; ensuring an uninterrupted power supply and availability of additional power bursts when required; and lengthening the life of the system while reducing the need for maintenance. The design and obstacles and scientific questions being addressed by the Lighthouse

  9. Particles size distribution and carbon flux across the Arabian Sea Oxygen Minimum Zone

    NASA Astrophysics Data System (ADS)

    Roullier, F.; Berline, L.; Guidi, L.; Sciandra, A.; Durrieu De Madron, X.; Picheral, M.; Pesant, S.; Stemmann, L.

    2013-12-01

    The goal of the Arabian Sea section of the TARA oceans expedition was to study Large Particulate Matter (LPM > 100 μm) distributions and possible impact of associated midwater biological processes on vertical carbon export through the Oxygen Minimum Zone (OMZ) of this region. We found that spatial patterns in LPM distribution resulted from the timing and location of surface phytoplankton bloom, lateral transport, microbial processes in the core of the OMZ, and zooplankton activity at the lower oxycline. Indeed, satellite-derived net primary production maps showed that the northern stations of the transect were under the influence of a previous major bloom event while, the most southern stations were in a more oligotrophic situation. Lagrangian simulations of particle transport showed that deep particles of the northern stations could originate from the surface bloom while the southern stations could be considered as driven by 1-D vertical processes. In the first 200 m of the OMZ core, minima in nitrate concentrations and the Intermediate Nepheloid Layer (INL) coincided with high concentrations of 100 μm < LPM < 200 μm. These particles could correspond to colonies of bacteria or detritus produced by anaerobic microbial activity. However, the calculated carbon flux through this layer was not affected. Vertical profiles of carbon flux indicate low flux attenuation in the OMZ, with a Martin model b exponent value of 0.22. At the lower oxycline, a deep nepheloid layer was associated to an increase of carbon flux and an increase in mesozooplankton abundance. Zooplankton feeding on un-mineralized sinking particles in the OMZ is proposed as a mechanism for the observed deep particle aggregation. These results suggest that OMZ may be regions of enhanced carbon flux to the deep sea relative to non-OMZ regions.

  10. Particle size distribution and estimated carbon flux across the Arabian Sea oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Roullier, F.; Berline, L.; Guidi, L.; Durrieu De Madron, X.; Picheral, M.; Sciandra, A.; Pesant, S.; Stemmann, L.

    2014-08-01

    The goal of the Arabian Sea section of the TARA oceans expedition was to study large particulate matter (LPM > 100 μm) distributions and possible impact of associated midwater biological processes on vertical carbon export through the oxygen minimum zone (OMZ) of this region. We propose that observed spatial patterns in LPM distribution resulted from the timing and location of surface phytoplankton bloom, lateral transport, microbial processes in the core of the OMZ, and enhanced biological processes mediated by bacteria and zooplankton at the lower oxycline. Indeed, satellite-derived net primary production maps showed that the northern stations of the transect were under the influence of a previous major bloom event while the most southern stations were in a more oligotrophic situation. Lagrangian simulations of particle transport showed that deep particles of the northern stations could originate from the surface bloom while the southern stations could be considered as driven by 1-D vertical processes. In the first 200 m of the OMZ core, minima in nitrate concentrations and the intermediate nepheloid layer (INL) coincided with high concentrations of 100 μm < LPM < 200 μm. These particles could correspond to colonies of bacteria or detritus produced by anaerobic microbial activity. However, the calculated carbon flux through this layer was not affected. Vertical profiles of carbon flux indicate low flux attenuation in the OMZ, with a Martin model b exponent value of 0.22. At three stations, the lower oxycline was associated to a deep nepheloid layer, an increase of calculated carbon flux and an increase in mesozooplankton abundance. Enhanced bacterial activity and zooplankton feeding in the deep OMZ is proposed as a mechanism for the observed deep particle aggregation. Estimated lower flux attenuation in the upper OMZ and re-aggregation at the lower oxycline suggest that OMZ may be regions of enhanced carbon flux to the deep sea relative to non OMZ regions.

  11. Identification of new deep sea sinuous channels in the eastern Arabian Sea.

    PubMed

    Mishra, Ravi; Pandey, D K; Ramesh, Prerna; Clift, Peter D

    2016-01-01

    Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geological record. The Indus Fan is the second largest modern submarine fan, having a well-developed active canyon and deep sea channel system. Previous studies from the upper Indus Fan have reported several active channel systems. In the present study, deep sea channel systems were identified within the middle Indus Fan using high resolution multibeam bathymetric data. Prominent morphological features within the survey block include the Raman Seamount and Laxmi Ridge. The origin of the newly discovered channels in the middle fan has been inferred using medium resolution satellite bathymetry data. Interpretation of new data shows that the highly sinuous deep sea channel systems also extend to the east of Laxmi Ridge, as well as to the west of Laxmi Ridge, as previously reported. A decrease in sinuosity southward can be attributed to the morphological constraints imposed by the elevated features. These findings have significance in determining the pathways for active sediment transport systems, as well as their source characterization. The geometry suggests a series of punctuated avulsion events leading to the present array of disconnected channels. Such channels have affected the Laxmi Basin since the Pliocene and are responsible for reworking older fan sediments, resulting in loss of the original erosional signature supplied from the river mouth. This implies that distal fan sediments have experienced significant signal shredding and may not represent the erosion and weathering conditions within the onshore basin at the time of sedimentation.

  12. Identification of new deep sea sinuous channels in the eastern Arabian Sea.

    PubMed

    Mishra, Ravi; Pandey, D K; Ramesh, Prerna; Clift, Peter D

    2016-01-01

    Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geological record. The Indus Fan is the second largest modern submarine fan, having a well-developed active canyon and deep sea channel system. Previous studies from the upper Indus Fan have reported several active channel systems. In the present study, deep sea channel systems were identified within the middle Indus Fan using high resolution multibeam bathymetric data. Prominent morphological features within the survey block include the Raman Seamount and Laxmi Ridge. The origin of the newly discovered channels in the middle fan has been inferred using medium resolution satellite bathymetry data. Interpretation of new data shows that the highly sinuous deep sea channel systems also extend to the east of Laxmi Ridge, as well as to the west of Laxmi Ridge, as previously reported. A decrease in sinuosity southward can be attributed to the morphological constraints imposed by the elevated features. These findings have significance in determining the pathways for active sediment transport systems, as well as their source characterization. The geometry suggests a series of punctuated avulsion events leading to the present array of disconnected channels. Such channels have affected the Laxmi Basin since the Pliocene and are responsible for reworking older fan sediments, resulting in loss of the original erosional signature supplied from the river mouth. This implies that distal fan sediments have experienced significant signal shredding and may not represent the erosion and weathering conditions within the onshore basin at the time of sedimentation. PMID:27386293

  13. Acoustic doppler current profiling from the JGOFS Arabian Sea cruises aboard the RV T.G. Thompson

    SciTech Connect

    Flagg, C.N.; Shi, Y.

    1995-04-01

    Acoustic Doppler Current Profiler (ADCP) data from the R/V T.G. THOMPSON is part of the core data for the US JGOFS Arabian Sea project along with hydrographic and nutrient data. Seventeen cruises on the THOMPSON are scheduled to take place between September 1994 and January 1996. The first of these cruises, a transit of the R/V THOMPSON into the northern Arabian Sea area from Singapore, was a calibration and training cruise that took place between September 18 and October 7, 1994. (The cruises on the THOMPSON are numbered consecutively from the ship`s commissioning with the first JOGFS cruise designated TN039.) The remaining cruises have been and will be staged from Muscat, Oman. Seven of these cruises, referred to as process cruises, will follow a set cruise track, making hydrographic, chemical and biological measurements. The remainder of the cruises while not restricted to the set cruise track, will generally stay within the region defined by the track during the deployment and retrieval of moored equipment and the towing of a SeaSoar. Each cruise will last between two weeks and one month. ADCP data will be collected on all the JGOFS Arabian Sea cruises using an autonomous data acquisition system developed for ship-of-opportunity cruises. This system, referred to as the AutoADCP, makes it possible to collect the ADCP data without the constant monitoring usually necessary and assures constant data coverage and uniform data quality. The AutoADCP system is an extension of RD Instrument`s DAS version 2.48 using enhancements made possible with ``user exit`` programs. This data report presents ADCP results from the first four JGOFS cruises, TN039 through TN042, concentrating on the data collection and processing methods.

  14. Mesoscale variability in the Arabian Sea from HYCOM model results and observations: impact on the Persian Gulf Water path

    NASA Astrophysics Data System (ADS)

    L'Hégaret, P.; Duarte, R.; Carton, X.; Vic, C.; Ciani, D.; Baraille, R.; Corréard, S.

    2015-09-01

    The Arabian Sea and Sea of Oman circulation and water masses, subject to monsoon forcing, reveal a strong seasonal variability and intense mesoscale features. We describe and analyze this variability and these features, using both meteorological data (from ECMWF reanalyses), in situ observations (from the ARGO float program and the GDEM - Generalized Digital Environmental mode - climatology), satellite altimetry (from AVISO) and a regional simulation with a primitive equation model (HYCOM - the Hybrid Coordinate Ocean Model). The model and observations display comparable variability, and the model is then used to analyze the three-dimensional structure of eddies and water masses with higher temporal and spatial resolutions than the available observations. The mesoscale features are highly seasonal, with the formation of coastal currents, destabilizing into eddies, or the radiation of Rossby waves from the Indian coast. The mesoscale eddies have a deep dynamical influence and strongly drive the water masses at depth. In particular, in the Sea of Oman, the Persian Gulf Water presents several offshore ejection sites and a complex recirculation, depending on the mesoscale eddies. The associated mechanisms range from coastal ejection via dipoles, alongshore pulses due to a cyclonic eddy, to the formation of lee eddies downstream of Ra's Al Hamra. This water mass is also captured inside the eddies via several mechanisms, keeping high thermohaline characteristics in the Arabian Sea. The variations of the outflow characteristics near the Strait of Hormuz are compared with variations downstream.

  15. Arabian Night and Sea Story - Biomarkers from a Giant Mass Transport Deposit.

    NASA Astrophysics Data System (ADS)

    Bratenkov, Sophia; Kulhanek, Denise K.; Clift, Peter D.; George, Simon C.

    2016-04-01

    The study of mass transport deposits (MTDs) is an important field of research due to the potential insights into catastrophic events in the past and modern geohazard threats (e.g. tsunamis). Submarine mass movements are very significant processes in sculpturing the structure of continental margins, particularly in their extent and magnitude that have consequences both in the modern day, as well as in the geological past. An understanding of the complex stratigraphy of a submarine mass transport deposit (MTD) might help in reconstructing the provenance and transport pathways of sedimentary material and thus give important insights into sedimentary dynamics and processes triggering specific events. Drilling operations during International Ocean Discovery Program (IODP) Expedition 355 Arabian Sea Monsoon, which took place during April and May, 2015 cored two sites in Laxmi Basin. Site U1456 was cored to 1109.4 m below seafloor (mbsf), with the oldest recovered rock dated to ~13.5-17.7 Ma. Site U1457 was cored to 1108.6 mbsf, with the oldest rock dated to ~62 Ma. At each site, we cored through ~330 m and ~190 m of MTD material. The MTD layers mainly consist of interbedded lithologies of dark grey claystone, light greenish calcarenite and calcilutite, and conglomerate/breccia, with ages based on calcareous nannofossil and foraminifer biostratigraphy ranging from the Eocene to early Miocene (Pandey et al., 2015). This MTD, known as Nataraja Slide, is the third largest MTD known from the geological record and the second largest on a passive margin. Calvés et al. (2015) identified a potential source area offshore Sourashstra on the Indian continental margin and invoked the single step mass movement model to explain the mechanism of emplacement. Initial shipboard work demonstrated the high variability in total organic carbon and total nitrogen levels in different layers within the MTD, which raises a number of questions related to the source and composition of the organic

  16. Plectranthias alcocki, a new anthiine fish species (Perciformes: Serranidae) from the Arabian Sea, off southwest India.

    PubMed

    Bineesh, K K; Akhilesh, K V; Gopalakrishnan, A; Jena, J K

    2014-04-04

    A new species of anthiine fish, Plectranthias alcocki n. sp. is described and illustrated based on two specimens, (63.7-72.5 mm SL), recently collected from deep-waters of the Arabian Sea, off Kollam, Kerala, India. The following combination of characters distinguishes it from all other congeners: Dorsal-fin rays X, 15; anal-fin rays III, 7; pectoral-fin rays 14, all unbranched; pelvic-fin rays I, 5; lateral-line complete, the pored lateral-line scales 28; scales above lateral line to origin of dorsal fin 1; scales dorsally on head extending to posterior nostrils; no scales on maxilla or chin; gill rakers 5 + 11 (2 + 7 developed); circumpeduncular scales 10; fourth dorsal spine longest, 2.8 (2.6) in head length (HL), longest dorsal-fin soft ray (second)  2.4 (2.7) in head length; body depth 34.4 (35)% SL; head length 46 (49.8)% SL; orbital length 8.6 in SL; margin of preopercle finely serrate, the serrae 33 (28), ventral edge without antrorse spines; dorsal fin continuous and notched; first anal-fin spine 4.9 (5.6) in HL, second anal-fin spine 2.2 (2.6) in HL; pelvic fins relatively short, 4.0-4.3 in SL; the dorsal fin with a black blotch at base of fourth to eighth spines, one at base of the last three spines, and two at base of soft portion of fin, the dark pigment extending onto adjacent body.

  17. PCR analysis of the distribution of unicellular cyanobacterial diazotrophs in the Arabian Sea.

    PubMed

    Mazard, Sophie L; Fuller, Nicholas J; Orcutt, Karen M; Bridle, Oliver; Scanlan, Dave J

    2004-12-01

    An oligonucleotide primer, NITRO821R, targeting the 16S rRNA gene of unicellular cyanobacterial N2 fixers was developed based on newly derived sequences from Crocosphaera sp. strain WH 8501 and Cyanothece sp. strains WH 8902 and WH 8904 as well as several previously described sequences of Cyanothece sp. and sequences of intracellular cyanobacterial symbionts of the marine diatom Climacodium frauenfeldianum. This oligonucleotide is specific for the targeted organisms, which represent a well-defined phylogenetic lineage, and can detect as few as 50 cells in a standard PCR when it is used as a reverse primer together with the cyanobacterium- and plastid-specific forward primer CYA359F (U. Nubel, F. Garcia-Pichel, and G. Muyzer, Appl. Environ. Microbiol. 63:3327-3332, 1997). Use of this primer pair in the PCR allowed analysis of the distribution of marine unicellular cyanobacterial diazotrophs along a transect following the 67 degrees E meridian from Victoria, Seychelles, to Muscat, Oman (0.5 degrees S to 26 degrees N) in the Arabian Sea. These organisms were found to be preferentially located in warm (>29 degrees C) oligotrophic subsurface waters between 0 and 7 degrees N, but they were also found at a station north of Oman at 26 degrees N, 56 degrees 35'E, where similar water column conditions prevailed. Slightly cooler oligotrophic waters (<29 degrees C) did not contain these organisms or the numbers were considerably reduced, suggesting that temperature is a key factor in dictating the abundance of this unicellular cyanobacterial diazotroph lineage in marine environments.

  18. Species delimitation in the coral genus Goniopora (Scleractinia, Poritidae) from the Saudi Arabian Red Sea.

    PubMed

    Terraneo, Tullia I; Benzoni, Francesca; Arrigoni, Roberto; Berumen, Michael L

    2016-09-01

    Variable skeletal morphology, genotype induced plasticity, and homoplasy of skeletal structures have presented major challenges for scleractinian coral taxonomy and systematics since the 18th century. Although the recent integration of genetic and micromorphological data is helping to clarify the taxonomic confusion within the order, phylogenetic relationships and species delimitation within most coral genera are still far from settled. In the present study, the species boundaries in the scleractinian coral genus Goniopora were investigated using 199 colonies from the Saudi Arabian Red Sea and sequencing of four molecular markers: the mitochondrial intergenic spacer between CytB and NAD2, the nuclear ribosomal ITS region, and two single-copy nuclear genes (ATPsβ and CalM). DNA sequence data were analyzed using a variety of methods and exploratory species-delimitation tools. The results were broadly congruent in identifying five distinct molecular lineages within the sequenced Goniopora samples: G. somaliensis/G. savignyi, G. djiboutiensis/G. lobata, G. stokesi, G. albiconus/G. tenuidens, and G. minor/G. gracilis. Although the traditional macromorphological characters used to identify these nine morphospecies were not able to discriminate the obtained molecular clades, informative micromorphological and microstructural features (such as the micro-ornamentation and the arrangement of the columella) were recovered among the five lineages. Moreover, unique in vivo morphologies were associated with the genetic-delimited lineages, further supporting the molecular findings. This study represents the first attempt to identify species boundaries within Goniopora using a combined morpho-molecular approach. The obtained data establish a basis for future taxonomic revision of the genus, which should include colonies across its entire geographical distribution in the Indo-Pacific.

  19. ITCZ-monsoonal association during the last glacial (Cariaco Basin, Northern Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Deplazes, G.; Haug, G. H.; Lueckge, A.

    2010-12-01

    The anoxic Cariaco Basin on the northern shelf of Venezuela preserves detailed records of past tropical climate variability. The sediment formation in this basin is controlled by the migration of the Atlantic Intertropical Convergence Zone (ITCZ) and the corresponding rain belt and trade winds. In the oxygen minimum zone off Pakistan in the northeastern Arabian Sea sediment archives of low-latitude monsoonal climate are preserved. In this study sediments from the two settings that cover the last 80,- to 110,000 years were analysed. Sediment color analysis resulted in reflectance records with a down to annual resolution. An age model was set up by correlation of these records to the δ18O record of Greenland ice (NGRIP). The major element chemistry of the sediments was analysed with X-ray fluorescence scanning. The new high resolution proxy records indicate an unbroken association between warm climate conditions over Greenland, a northerly position of the Atlantic Intertropical Convergence Zone, and a strong Indian summer monsoon since the last glacial. The tight coupling is explained by a dominant role of the North Atlantic that is communicated largely through the atmosphere. New insights of dynamical mechanisms arise from comparison of individual Dansgaard-Oeschger events. The tropical records and the Greenland δ18O record show both an abrupt change at the beginning of an interstadial. The δ18O of Greenland ice peaks early in the interstadials and then decreases more or less constantly toward stadial values. However, the tropical records have a tendency to maintain dark interstadial color on a similar level over several centuries. The following centennial-scale lightening toward the next stadial appears to be delayed compared to the δ18O ice record. This “resistance” of the tropics to the interstadial-stadial transitions suggests a threshold response of the tropics to North Atlantic cooling.

  20. Species delimitation in the coral genus Goniopora (Scleractinia, Poritidae) from the Saudi Arabian Red Sea.

    PubMed

    Terraneo, Tullia I; Benzoni, Francesca; Arrigoni, Roberto; Berumen, Michael L

    2016-09-01

    Variable skeletal morphology, genotype induced plasticity, and homoplasy of skeletal structures have presented major challenges for scleractinian coral taxonomy and systematics since the 18th century. Although the recent integration of genetic and micromorphological data is helping to clarify the taxonomic confusion within the order, phylogenetic relationships and species delimitation within most coral genera are still far from settled. In the present study, the species boundaries in the scleractinian coral genus Goniopora were investigated using 199 colonies from the Saudi Arabian Red Sea and sequencing of four molecular markers: the mitochondrial intergenic spacer between CytB and NAD2, the nuclear ribosomal ITS region, and two single-copy nuclear genes (ATPsβ and CalM). DNA sequence data were analyzed using a variety of methods and exploratory species-delimitation tools. The results were broadly congruent in identifying five distinct molecular lineages within the sequenced Goniopora samples: G. somaliensis/G. savignyi, G. djiboutiensis/G. lobata, G. stokesi, G. albiconus/G. tenuidens, and G. minor/G. gracilis. Although the traditional macromorphological characters used to identify these nine morphospecies were not able to discriminate the obtained molecular clades, informative micromorphological and microstructural features (such as the micro-ornamentation and the arrangement of the columella) were recovered among the five lineages. Moreover, unique in vivo morphologies were associated with the genetic-delimited lineages, further supporting the molecular findings. This study represents the first attempt to identify species boundaries within Goniopora using a combined morpho-molecular approach. The obtained data establish a basis for future taxonomic revision of the genus, which should include colonies across its entire geographical distribution in the Indo-Pacific. PMID:27321092

  1. Locating Noctiluca Miliaris in the Arabian Sea: An Optical Proxy Approach

    NASA Technical Reports Server (NTRS)

    Thibodeau, Patricia S.; Roesler, Collin S.; Drapeau, Susan L.; Matondkar, S. G. Prabhu; Goes, Joaquim I.; Werdell, P. Jeremy

    2014-01-01

    Coincident with shifting monsoon weather patterns over India, the phytoplankter Noctiluca miliaris has recently been observed to be dominating phytoplankton blooms in the northeastern Arabian Sea during the winter monsoons. Identifying the exact environmental and/or ecological conditions that favor this species has been hampered by the lack of concurrent environmental and biological observations on time and space scales relevant to ecologic and physiologic processes. We present a bio-optical proxy for N. miliaris measured on highly resolved depth scales coincident with hydrographic observations with the goal to identify conducive hydrographic conditions for the bloom. The proxy is derived from multichannel excitation chlorophyll a fluorescence and is validated with microscopy, pigment composition, and spectral absorption. Phytoplankton populations dominated by either diatoms or other dinoflagellates were additionally discerned. N. miliaris populations in full bloom were identified offshore in low-nutrient and low-N : P ratio surface waters within a narrow temperature and salinity range. These populations transitioned to high-biomass diatom-dominated coastal upwelling populations. A week later, the N. miliaris blooms were observed in declining phase, transitioning to very-low-biomass populations of non-N. miliaris dinoflagellates. There were no clear hydrographic conditions uniquely associated with the N. miliaris populations, although N. miliaris was not found in the upwelling or extremely oligotrophic waters. Taxonomic transitions were not discernible in the spatial structure of the bloom as identified by the ocean color Chl imagery, indicating that in situ observations may be necessary to resolve community structure, particularly for populations below the surface.

  2. Effects of composition of labile organic matter on biogenic production of methane in the coastal sediments of the Arabian Sea.

    PubMed

    Gonsalves, Maria-Judith; Fernandes, Christabelle E G; Fernandes, Sheryl Oliveira; Kirchman, David L; Bharathi, P A Loka

    2011-11-01

    Coastal regions are potential zones for production of methane which could be governed by ecological/environmental differences or even sediment properties of a niche. In order to test the hypothesis that methanogenesis in most marine sediments could be driven more by proteins than by carbohydrates and lipid content of labile organic matter (LOM), incubation experiments were carried out with sediments from different environmental niches to measure methane production. The methane production rates were examined in relationship to the sediment biochemistry, i.e., carbohydrates, proteins, and lipids. The gas production measured by head space method ranged from 216 ng g( -1) day( -1) in the mangrove sediments to 3.1 μg g( -1) day( -1) in the shallow Arabian Sea. LOM ranged from 1.56 to 2.85 mg g( -1) in the shallow Arabian Sea, from 3.35 to 5.43 mg g( -1) in the mangrove estuary, and from 0.66 to 0.70 mg g( -1) in the sandy sediments with proteins contributing maximum to the LOM pool. Proteins influenced methane production in the clayey sediments of shallow depths of the Arabian Sea (r = 0.933, p < 0.001) and mangrove estuary (r = 0.981, p < 0.001) but in the sandy beach sediments, carbohydrates (r = 0.924, p < 0.001) governed the net methane production. The gas production was more pronounced in shallow and surface sediments and it decreased with depth apparently governed by the decrease in lability index. Thus, the lability index and protein content are important factors that determine methane production rates in these coastal ecosystems.

  3. Seismic Velocity Structure and Depth-Dependence of Anisotropy in the Red Sea and Arabian Shield from Surface Wave Analysis

    SciTech Connect

    Hansen, S; Gaherty, J; Schwartz, S; Rodgers, A; Al-Amri, A

    2007-07-25

    We investigate the lithospheric and upper mantle structure as well as the depth-dependence of anisotropy along the Red Sea and beneath the Arabian Peninsula using receiver function constraints and phase velocities of surface waves traversing two transects of stations from the Saudi Arabian National Digital Seismic Network. Frequency-dependent phase delays of fundamental-mode Love and Rayleigh waves, measured using a cross-correlation procedure, require very slow shear velocities and the presence of anisotropy throughout the upper mantle. Linearized inversion of these data produce path-averaged 1D radially anisotropic models with about 4% anisotropy in the lithosphere, increasing to about 4.8% anisotropy across the lithosphere-asthenosphere boundary (LAB). Models with reasonable crustal velocities in which the mantle lithosphere is isotropic cannot satisfy the data. The lithospheric lid, which ranges in thickness from about 70 km near the Red Sea coast to about 90 km beneath the Arabian Shield, is underlain by a pronounced low-velocity zone with shear velocities as low as 4.1 km/s. Forward models, which are constructed from previously determined shear-wave splitting estimates, can reconcile surface and body wave observations of anisotropy. The low shear velocity values are similar to many other continental rift and oceanic ridge environments. These low velocities combined with the sharp velocity contrast across the LAB may indicate the presence of partial melt beneath Arabia. The anisotropic signature primarily reflects a combination of plate- and density-driven flow associated with active rifting processes in the Red Sea.

  4. Limpets of the genus Cellana (Patellogastropoda) from Pakistan, North Arabian Sea: species identification based on DNA sequencing.

    PubMed

    Zafar, Fatima Hayat Shaheen; Ayub, Zarrien; Begum, Samar; Siddiqui, Ghazala; Roberts, David

    2016-07-01

    The true limpets are found in the intertidal zone of the rocky shores of Pakistan, North Arabian Sea. Partial sequence of the mitochondrial cytochrome oxidase I was used to estimate the degree of genetic differentiation among the morphological forms of Cellana, which were considered as three separate species earlier in Pakistan. The study revealed that the three morphs of Cellana on COI sequence generated a single haplotype and matched with the COI sequence of Cellana karachiensis. This point out the phenotypic plasticity between the proposed species.

  5. Limpets of the genus Cellana (Patellogastropoda) from Pakistan, North Arabian Sea: species identification based on DNA sequencing.

    PubMed

    Zafar, Fatima Hayat Shaheen; Ayub, Zarrien; Begum, Samar; Siddiqui, Ghazala; Roberts, David

    2016-07-01

    The true limpets are found in the intertidal zone of the rocky shores of Pakistan, North Arabian Sea. Partial sequence of the mitochondrial cytochrome oxidase I was used to estimate the degree of genetic differentiation among the morphological forms of Cellana, which were considered as three separate species earlier in Pakistan. The study revealed that the three morphs of Cellana on COI sequence generated a single haplotype and matched with the COI sequence of Cellana karachiensis. This point out the phenotypic plasticity between the proposed species. PMID:26065851

  6. Extremely high aerosol loading over Arabian Sea during June 2008: The specific role of the atmospheric dynamics and Sistan dust storms

    NASA Astrophysics Data System (ADS)

    Kaskaoutis, D. G.; Rashki, A.; Houssos, E. E.; Goto, D.; Nastos, P. T.

    2014-09-01

    This study focuses on analyzing the extreme aerosol loading and the mechanisms, source areas and meteorological conditions that favored the abnormal dust exposure towards Arabian Sea during June 2008. The analysis reveals that the spatial-averaged aerosol optical depth (AOD) over Arabian Sea in June 2008 is 0.5 (78.2%) higher than the 2000-2013 mean June value and is mostly attributed to the enhanced dust activity and several (18) dust storms originated from the Sistan region (Iran-Afghanistan borders). Landsat images show that the marshy lakes in Sistan basin got dried during the second half of June 2008 and the alluvial silt and saline material got easily eroded by the intense Levar winds, which were stronger (>15-20 m s-1) than the climatological mean for the month of June. These conditions led to enhanced dust exposure from Sistan that strongly affected the northern and central parts of the Arabian Sea, as forward air-mass trajectories show. The NCEP/NCAR reanalysis reveals an abnormal intensification and spatial expansion of the Indian low pressure system towards northern Arabian Sea in June 2008. This suggests strengthening of the convection over the arid southwest Asia and exposure of significant amount of dust, which can reach further south over Arabian Sea favored by the enhanced cyclonic circulation. MODIS imagery highlighted several dust storms originated from Sistan and affecting Arabian Sea during June 2008, while the SPRINTARS model simulations of increased AOD and dust concentration over Sistan and downwind areas are in agreement with ground-based and satellite observations.

  7. Body and Surface wave tomography for the Arabian Peninsula and Red Sea

    NASA Astrophysics Data System (ADS)

    Park, Y.; Nyblade, A. A.; Rodgers, A.; Al-Amri, A.

    2006-12-01

    We have imaged tomographically the three-dimensional velocity structure of the upper mantle beneath the Arabian Peninsula using teleseismic P- and S-waves and Rayleigh wave phase velocities. The data for this study come from the Saudi Arabian National Digital Seismic Network (SANDSN) operated by King Abdulaziz City for Science and Technology (KACST: 21 broadband stations and 4 short-period stations). We augmented the SANDSN data with delay times measured from permanent Incorporated Research Institutions for Seismology (IRIS) stations in the region (RAYN, EIL and MRNI) and the 1996 Saudi Arabian PASSCAL Experiment (9 broadband stations). For the P-wave model 3416 ray paths from P- and PKP-waves and 1602 ray paths from S- and SKS-waves for the S-wave model were used. For the Rayleigh wave phase velocity tomography, we included data from the Ethiopian Broadband Seismic Experiment and obtained the maximum 1606 rays with the best coverage between periods of 44 and 140 s. The body and surface wave models yield consistent results, although the surface wave tomography shows poor horizontal resolution. The models show strong low velocity regions beneath the southeastern Arabian Shield and the northeastern edge of Arabian Shield. The low velocity anomaly in the southeastern part of the Arabian Shield is separated structure from the low velocity zone beneath the northeastern edge of the Arabian Shield and dips to the south in the body wave models. It likely represents the northeastern edge of the Afar hotspot. The origin of the low velocity anomaly beneath the northeastern part of the Shield is uncertain.

  8. Study of air-sea interaction processes over the Arabian Sea and the Bay of Bengal using satellite data

    SciTech Connect

    Gautam, N.; Simon, B.; Pandey, P.C.

    1995-12-01

    The main objective of this work is to study the latitudinal and seasonal variation of latent heat fluxes (LHF) and associated atmospheric and oceanic parameters over the Arabian Sea (AS) and the Bay of Bengal (BB) for the year 1988. A significant latitudinal variation is observed in LHF for most of the months over the AS and the BB, while other oceanic and atmospheric parameters are characterized by a strong latitudinal variation in nonmonsoon months. Seasonal variations in LHF are more significant at higher latitudes compared to lower latitudes over the AS and the BB. The effect of coastal upwelling near the Somali coast decreases LHF, while surface winds near the Indian coast during monsoon months increases LHF. A comparative study over the AS and the BB demonstrates higher PW and SST over the BB than over the AS. LHF is found to be greater over the AS than over the BB for nonmonsoon months. Correlation analysis indicates that LHF is found to be highly correlated with DQ (difference between the humidity at the surface and humidity near the surface) over the AS and weakly correlated over the BB during nonmonsoon months. Throughout the year, DQ is found to be a dominant factor for LHF over the AS. However, WS exercised better control over the BB in generating LHF. SST and PW are found to be highly correlated with each other over the AS (r = 0.87) and the BB (r = 0.75) for nonmonsoon months. The correlation becomes weakly negative over the AS (r = 0.15) and weak over the BB (r = 0.26) during monsoon months. Precipitable water is found to have a high correlation with WS over the AS (r = 0.72). This unique feature is revealed by SSM/I data and has not been reported earlier due to paucity of data over this region.

  9. Geochemical index of trace metals in the surficial sediments from the western continental shelf of India, Arabian Sea.

    PubMed

    Laluraj, C M; Nair, S M

    2006-12-01

    The present study focuses on the determination and abundance of trace metals (viz. Cu, Ni, Zn, Cr, Co, Cd, Mn and Fe) in the surficial sediments of west coast of Arabian Sea along the Indian subcontinent. Sediment samples were collected from three transects along the western continental shelf of Arabian Sea. The enrichment of Fe and Mn in coastal oxic-sediments indicates the precipitation of these redox sensitive elements as Fe- and Mn-hydroxides and oxides, whereas the low Fe and Mn concentrations in the oxygen deficient sediments of deeper stations reflects the dissolution of their hydroxides and oxides. Concentrations of fairly redox insensitive trace metals like Cu, Ni, Zn, Cr and Cd (with the exceptions of Cr) showed higher values at nearshore sediments, then it decreased towards seaward and again showed a slight increase at oxygen minimum stations in all the three transects. This geochemical variability in their distributional characteristics is mainly associated with the extent to which the precipitation or dissolution of Fe- and Mn-oxides/hydroxides occur since the scavenging or releasing effects of Fe- and Mn-oxides/hydroxides act as significant 'sinks' or 'sources' of heavy metals. The change in wind pattern, coastal upwelling and increased productivity are also the reported factors which influence the biogeochemical cycling of trace metals in the surface sediments of west coast of India. Enrichment factor generally showed a high gradient accumulation from nearshore to shelf.

  10. Deep-water Thyasiridae (Mollusca: Bivalvia) from the Oman Margin, Arabian Sea, new species and examples of endemism and cosmopolitanism.

    PubMed

    Oliver, P Graham

    2015-08-05

    Seven species of Thyasiridae are reported from the Oman Margin of the Arabian Sea at depths between 688 m and 3356 m. Hypoxic conditions exist at depths between 400 and 1200 m and three species are restricted to this zone and to the Arabian Sea. Leptaxinus indusarium has also been recorded from the Indus Fan and Channelaxinus investigatoris from off Sri Lanka. A new species Thyasira anassa sp. nov. is described from the hypoxic zone. Another four species are recorded from the abyssal zone where oxygen levels are typical for the deep ocean. Here another new species is described, Parathyasira bamberi sp. nov. but the other species could not be conclusively identified because of close affinity with populations from other oceans.  Deep water Atlantic species Axinulus croulinensis and Mendicula ferruginosa are apparently present in the abyssal Indian Ocean while another thyasirid shell is very close to Channelaxinus excavatus from the Eastern Pacific and C. perplicata from the Atlantic. Accompanying these abyssal thyasirids were other bivalve species, Deminucula atacellana, Limopsis pelagica and Bentharca asperula that cannot be distinguished by morphology from their Atlantic populations. It is concluded that using morphology alone that the abyssal species may well be cosmopolitan in distribution.

  11. Spatial variability in phytoplankton community structure along the eastern Arabian Sea during the onset of south-west monsoon

    NASA Astrophysics Data System (ADS)

    Ahmed, Ayaz; Kurian, Siby; Gauns, Mangesh; Chndrasekhararao, A. V.; Mulla, Amara; Naik, Bhagyashri; Naik, Hema; Naqvi, S. W. A.

    2016-05-01

    The Arabian Sea experiences moderate to weak upwelling along the south-west coast of India, which subsequently propagates towards the north. This causes variation in plankton community composition, which is addressed in the present study. Here we report the spatial variations in distribution of phytoplankton groups along the north-south transect in the eastern Arabian Sea based on marker pigments supported with flow-cytometric and microscopic analyses. 15 phytoplankton pigments were identified using High-performance liquid chromatography (HPLC) and the chemotaxonomic software (CHEMTAX) analysis associated these to seven major group of phytoplankton. The phytoplankton biomass, chlorophyll a (Chl a) was higher in southern stations with dominance of fucoxanthin whereas, divinyl chlorophyll a (divinyl Chl a), marker pigment of Prochlorococcus was present only in the northern region. Microscopic observation revealed the dominance of larger forms; diatoms (Chaetoceros coarctatum and Nitzschia sp.) and dinoflagellates (Scrippsiella sp., Oxytoxum nanum and Oxytoxum sp.) in the southern region. Furthermore, a study of plankton size distribution showed dominance of picoplankton (fpico) followed by nanoplankton (fnano) along the northern stations with comparatively higher microplankton (fmicro) in the south. This study clearly showed the influence of different environmental conditions on the phytoplankton community as reflected in dominance of diatoms in the southern (south of 12 °N) and that of picoplankton in the northern (north of 12 °N) region.

  12. Prediction of bathymetry from satellite altimeter based gravity in the Arabian Sea: Mapping of two unnamed deep seamounts

    NASA Astrophysics Data System (ADS)

    Jena, B.; Kurian, P. J.; Swain, D.; Tyagi, A.; Ravindra, R.

    2012-06-01

    This work attempts to predict bathymetry from satellite altimeter based gravity in the Arabian Sea. A collocated match-up database (n = 17,016) was created on Multibeam Echosounder (MBES) bathymetry and satellite gravity values (˜1 min spatial resolution) derived from remote sensing satellites. A Radial Basis Function (RBF) based Artificial Neural Network (ANN) model was developed to predict bathymetry from satellite gravity values. The ANN model was trained with variable undersea features such as seamount, knoll, abyssal plain, hill, etc. to familiarize the network with all possible geomorphic features as inputs through learning and the corresponding target outputs. The performance of the predictive model was evaluated by comparing bathymetric values with MBES datasets that were not used during the training and verification steps of the ANN model formulation. The model was then compared with MBES surveyed seamount observations (those were not used during ANN analysis) and global model bathymetry products. Results demonstrate better performance of ANN model compared to global model products for mapping of two unnamed seamounts in the Arabian Sea. These two unnamed seamounts have been predicted, mapped and their morphology is reported for the first time through this work.

  13. Deep-water Thyasiridae (Mollusca: Bivalvia) from the Oman Margin, Arabian Sea, new species and examples of endemism and cosmopolitanism.

    PubMed

    Oliver, P Graham

    2015-01-01

    Seven species of Thyasiridae are reported from the Oman Margin of the Arabian Sea at depths between 688 m and 3356 m. Hypoxic conditions exist at depths between 400 and 1200 m and three species are restricted to this zone and to the Arabian Sea. Leptaxinus indusarium has also been recorded from the Indus Fan and Channelaxinus investigatoris from off Sri Lanka. A new species Thyasira anassa sp. nov. is described from the hypoxic zone. Another four species are recorded from the abyssal zone where oxygen levels are typical for the deep ocean. Here another new species is described, Parathyasira bamberi sp. nov. but the other species could not be conclusively identified because of close affinity with populations from other oceans.  Deep water Atlantic species Axinulus croulinensis and Mendicula ferruginosa are apparently present in the abyssal Indian Ocean while another thyasirid shell is very close to Channelaxinus excavatus from the Eastern Pacific and C. perplicata from the Atlantic. Accompanying these abyssal thyasirids were other bivalve species, Deminucula atacellana, Limopsis pelagica and Bentharca asperula that cannot be distinguished by morphology from their Atlantic populations. It is concluded that using morphology alone that the abyssal species may well be cosmopolitan in distribution. PMID:26250317

  14. Retreived bacteria from Noctiluca miliaris (green) bloom of the northeastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Basu, Subhajit; Matondkar, S. G. Prabhu; Furtado, Irene

    2013-01-01

    In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea (NAS). This study provides the first characterization of bacteria from a seasonal bloom of green Noctiluca of NAS (20°N-17°N and 64°E-70°E), during the spring-inter-monsoon cruise of Sagar Sampada 253, in March 2007. Bacterial growth as assessed by most-probable number (MPN) and plate counts, revealed `variable-physiotypes' over a wide range of salinities (0%-25% w/v NaCl), pH levels (5-8.5), and organic nutrient strengths, in comparison to non-bloom waters. MPN indices of bacteria in surface waters of bloom stations *DWK and *PRB, corresponded to (3.08-4.41)×103 cells/mL at 3.5% NaCl (w/v), and (2.82-9.49)×102 cells/mL at 25% (w/v) NaCl in tryptone-yeast extract broth (TYE). Plate counts were (1.12-4)×106 CFU/mL at 0% (w/v) NaCl, (1.28-3.9)×106 CFU/mL at 3.5% (w/v) NaCl, and (0.4-7)×104 CFU/mL at 25% NaCl (w/v) on TYE. One-tenth-strength Zobell's gave (0.6-3.74)×105 CFU/mL at pH 5 to (3.58-7.5)×105 CFU/mL at pH 8.5. These bacteria were identified to the genera Bacillus, Cellulomonas, Staphylococcus, Planococcus, Dietzia, Virgibacillus, Micrococcus, Sporosarcinae, Leucobacter, and Halomonas. The identity of three strains (GUFBSS253N2, GUFBSS253N30, and GUFBSS253N84) was confirmed through 16S rDNA sequence homology as Bacillus cohnii, Bacillus flexus, and Bacillus cereus. The ˜2-3-fold higher plate counts of culturable bacteria from the open-waters of the NAS indicate that these bacteria could critically determine the biogeochemical dynamics of the bloom and its milieu. The role of these bacteria in sustaining/terminating the bloom is under evaluation.

  15. Inter-cohort growth patterns of pharaoh cuttlefish Sepia pharaonis (Sepioidea: Sepiidae) in Eastern Arabian Sea.

    PubMed

    Sasikumarl, Geetha; Mohamed, K S; Bhat, U S

    2013-03-01

    Sepia pharaonis is an important commercial species endemic to the tropical Indo-Pacific region. Despite its commercial significance, only few information on natural populations is available. This study was aimed to describe the aspects of size-composition, length-weight relationship, catch rates, seasonal recruitment and inter-cohort growth patterns of S. pharaonis population (Clade C), distributed along the Eastern Arabian Sea (South-West coast of India). For this, the Dorsal Mantle Length (DML) and weight of cuttlefishes was obtained from commercial trawl catches, from April 2002 to October 2006. Data was analyzed by normal length-weight methods such as von Bertalanffy. A total of 12454 cuttlefishes, ranging in length from four to 41cm were analyzed. Size-composition patterns discriminated two pulses in recruitment to the fishery, discernible by a decrease in the monthly mean size of the population. The DMLs of the two seasonal cohorts were subjected to modal-progression analysis using the Bhattacharya's method for the estimation of growth. The estimated parameters Linfinity and K in von Bertalanffy Growth Function (VBGF) were used to model growth curves in length for the cohorts. The first cohort, (post-monsoon cohort) which supports the major fishery, was composed of medium-sized, fast growing individuals, whereas the second cohort (pre-monsoon cohort), comprised of slow growing and large-sized individuals. There were differential growth characteristics between the sexes and the life span was estimated at less than 2.3 years for males and 2.1 years for females. Negative allometric growth in weight (W) with length (L) was observed for males (W=0.33069.L2.5389) and females (W=0.32542.L26057). The females were heavier compared to males at any given mantle length, and the males were found to attain larger ultimate lengths. The major fishing season for cuttlefish was from May to November, when higher monthly catch rates of 1.67-13.02kg/h were observed in comparison

  16. Seasonal and annual variability of vertically migrating scattering layers in the northern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Wang, Zhankun; DiMarco, Steven F.; Ingle, Stephanie; Belabbassi, Leila; Al-Kharusi, Lubna H.

    2014-08-01

    A 30-month time series of mean volume backscattering strength (MVBS) data obtained from moored acoustic Doppler current profilers (ADCPs) is used to analyze the evolution of vertically migrating scattering layers and their seasonal and annual variability in the Arabian and Oman Seas. Substantial diel vertical migration (DVM) is observed almost every day at all three mooring sites. Two daytime layers (Layers D1 and D2) and one nighttime layer (Layer E1) are typically present. The greatest biomass is observed near the surface during the night in Layer E1 and at depth between 250 and 450 m during the daytime in Layer D2. All layers are deepest during the spring inter-monsoon and shallowest during the summer/fall southwest monsoon (SWM). Seasonal modulation of the D2 biomass change is evident in our high-resolution data. The lowest biomass in D2 is measured in the early summer (May or June) followed by a rapid biomass increase during the SWM (June-November) until the biomass reaches a maximum at the end of the SWM season. Short-period oscillations in D2 biomass are often seen with periods ranging from days to one month. Occasionally, a lower nighttime layer E2 is formed between 180 and 270 m, mostly near the time of full moons. The upper daytime layer D1 is centered at 200 m and densely concentrated. It is only formed during the winter northeast monsoon (NEM) and the spring inter-monsoon. The influence of physical processes on layer distribution is also investigated. Interestingly, the two daytime layers are found to be formed at the two boundaries of the Persian Gulf outflow water (PGW) and follow the seasonal depth change of the PGW. The timing of the DVM and the formation, persistence, decay and reformation of the deep scattering layers seem to be governed by light, both solar and lunar. The scattering strength, the layer depth and the layer thickness are likewise closely related to the Moon phase at night. Cloud coverage, the isotherm and the isohaline also appear

  17. Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian Margin (Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

    2013-09-01

    Benthic foraminifera in sediments on the Indian margin of the Arabian Sea where the oxygen minimum zone (OMZ) impinges on the continental slope are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed at the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 ind. 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminifera population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up the labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). The uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen) and showed the successful application of 15N as tracer in foraminiferal studies. The short-term response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest that the observed species-specific differences are related to individual biomass of species and to specific

  18. Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian margin (Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

    2014-04-01

    Benthic foraminifera in sediments on the Indian margin of the Arabian Sea, where the oxygen minimum zone (OMZ) impinges on the continental slope, are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed on the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 individuals 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminiferal population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). Uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen). The response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing, whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest the observed species-specific differences are related to species biomass and specific feeding preferences. In summary, the experiment in the OMZ core region shows rapid processing of fresh

  19. Nitrogen production in the northern Arabian Sea during the Spring Intermonsoon and Southwest Monsoon seasons

    NASA Astrophysics Data System (ADS)

    Sambrotto, Raymond N.

    Planktonic nitrogen productivity and regeneration were measured with 15NO 3, 15NH 4 and 15N-urea tracers during the Spring Intermonsoon (SI) and Southwest Monsoon (SWM) seasons in the northern Arabian Sea from the Omani coast southeast to 10°N. On an areal basis, new (nitrate) productivity and the nitrogen f-ratio varied from 0.1 to 13 mmol m -2 d -1 and 0.03 to 0.4, respectively. Including urea in total nitrogen uptake lowered the f-ratio by 29% on average for individual samples, and during the SI was most important in offshore regions. The lowest nitrate productivity rates also were measured in offshore regions during the SI, where low, but detectable, nitrate levels limited uptake. The onset of the SWM was associated with an order of magnitude increase in nitrate uptake seaward of the Findlater Jet as compared to the SI. Apparently, the positive effect of the increased availability of nitrate and the Ekman transport of established phytoplankton populations to the region more than offset the degraded light conditions caused by the deep (>80 m) mixed layers. Despite the increases in offshore nitrate uptake, both a budget of surface particulate material and 234Th POC flux estimates indicated that the mid- SWM reduced the efficiency of material export from surface waters and disrupted the linkage between new production and export that was evident in the SI. In the mid-SWM, new production mainly accumulated in deeply mixed surface waters offshore, and may be responsible for the well documented lag between the onset of the SWM and export. In the coastal upwelling region, new production rates were significantly greater during the SWM only near filaments of coastal water advected offshore. Ammonium regeneration rates and concentrations increased significantly in coastal regions during the SWM, and nitrification likely was a significant sink for some of the ammonium produced there. The transport of some of the remainder of this reduced nitrogen offshore would fuel

  20. Response of the Surface Circulation of the Arabian Sea to Monsoonal Forcing

    NASA Astrophysics Data System (ADS)

    Beal, L. M.; Hormann, V.; Lumpkin, R.; Foltz, G. R.

    2014-12-01

    We use two decades of drifter and satellite data to examine the monthly evolution of the surface circulation of the Arabian Sea, which reverses annually in response to the Indian monsoon winds. Most significantly, we find that in the transition from winter to summer circulations, northward flow appears along the length of the western boundary as early as March or April, one or two months before the onset of the southwest monsoon winds. This reversal is initiated by annual Rossby waves, which in turn are initiated by wind curl forcing during the previous southwest monsoon. These results lead us to speculate that there is an oceanic mechanism through which one monsoon may precondition the next. Previous studies of monsoon circulations with lower temporal resolution have highlighted basin-wide currents and connections that are not found to exist in the monthly fields. In particular, we find that the Northeast Monsoon Current does not reach the western boundary and there is no counter-rotating gyre system during boreal winter. South of the equator, the eastward-flowing South Equatorial Counter Current (SECC) is present year-round, even though equatorial winds are strongly influenced by the monsoons. Semi-annual variability of the SECC is governed by Ekman pumping over the south equatorial gyre (or Seychelles dome) and, surprisingly, it is weakest during the northeast monsoon. This region has important influence on the atmosphere and its link to the monsoons deserves further investigation. The East African Coastal Current feeds into the SECC from the boundary. During the southwest monsoon it overshoots the equator and splits, feeding both northward into the Somali Current and eastward into the SECC after looping back across the equator. This apparent retroflection of the EACC is what was previously known as the southern gyre and is obscured at the surface by strong, locally wind-driven, cross-equatorial Ekman transport. Finally, there is broad, strong eastward flow at

  1. Acoustic Doppler current profiling from the JGOFS Arabian Sea cruises aboard the RV T.G. Thompson

    SciTech Connect

    Kim, H.S.; Flagg, C.N.; Shi, Y.

    1996-12-01

    Acoustic Doppler current profiler (ADCP) data is part of the core data for the US JGOFS Arabian Sea project, along with hydrographic and nutrient data. Seventeen cruises are scheduled to take place between September 1994 and January 1996 on the R/V T.G. Thompson. Seven of the cruises follow a standard cruise track, taking hydrographic, chemical and biological measurements. The rest of the cruises, which take place generally within the standard cruise region defined by a set track, are for the deployment and recovery of moored equipment and towing of a SeaSoar. Detailed description of ADCP hardware, the AutoADCP data acquisition system, and the collection of navigation and compass data on the Thompson is documented in Section 2. Followed by data collection for each cruise together with a cruise track, Section 3 presents the processing and analysis of velocity and acoustic backscatter intensity data. Section 5 shows results of profile quality diagnosis.

  2. The Arabian Sea as a high-nutrient, low-chlorophyll region during the late Southwest Monsoon

    NASA Astrophysics Data System (ADS)

    Naqvi, S. W. A.; Moffett, J. W.; Gauns, M. U.; Narvekar, P. V.; Pratihary, A. K.; Naik, H.; Shenoy, D. M.; Jayakumar, D. A.; Goepfert, T. J.; Patra, P. K.; Al-Azri, A.; Ahmed, S. I.

    2010-07-01

    Extensive observations were made during the late Southwest Monsoon of 2004 over the Indian and Omani shelves, and along a transect that extended from the southern coast of Oman to the central west coast of India, tracking the southern leg of the US JGOFS expedition (1994-1995) in the west. The data are used, in conjunction with satellite-derived data, to investigate long-term trends in chlorophyll and sea surface temperature, indicators of upwelling intensity, and to understand factors that control primary production (PP) in the Arabian Sea, focussing on the role of iron. Our results do not support an intensification of upwelling in the western Arabian Sea, reported to have been caused by the decline in the winter/spring Eurasian snow cover since 1997. We also noticed, for the first time, an unexpected development of high-nutrient, low-chlorophyll condition off the southern Omani coast. This feature, coupled with other characteristics of the system, such as a narrow shelf and relatively low iron concentrations in surface waters, suggest a close similarity between the Omani upwelling system and the Peruvian and California upwelling systems, where PP is limited by iron. Iron limitation of PP may complicate simple relationship between upwelling and PP assumed by previous workers, and contribute to the anomalous offshore occurrence of the most severe oxygen (O2) depletion in the region. Over the much wider Indian shelf, which experiences large-scale bottom water O2-depletion in summer, adequate iron supply from reducing bottom-waters and sediments seems to support moderately high PP; however, such production is restricted to the thin, oxygenated surface layer, probably because of the unsuitability of the O2-depleted environment for the growth of oxygenic photosynthesizers.

  3. Monsoon driven changes in phytoplankton populations in the eastern Arabian Sea as revealed by microscopy and HPLC pigment analysis

    NASA Astrophysics Data System (ADS)

    Parab, Sushma G.; Prabhu Matondkar, S. G.; Gomes, H. do R.; Goes, J. I.

    2006-12-01

    Like the rest of the Arabian Sea, the west coast of India is subject to semi-annual wind reversals associated with the monsoon cycle that result in two periods of elevated phytoplankton productivity, one during the northeast (NE) monsoon (November-February) and the other during the southwest (SW) monsoon (June-September). Although the seasonality of phytoplankton biomass in these coastal waters is well known, the abundance and composition of phytoplankton populations associated with this distinct and predictable seasonal cycle is poorly known. Here we present for the first time, the results of a study on the community structure of phytoplankton for this region, derived from HPLC pigment analysis and microscopic cell counts. Our sampling strategy allowed for large spatial and temporal coverage over regions representative of the coastal and offshore waters, and over seasons that included the NE and the SW monsoon. Monthly observations at a fixed coastal station in particular, allowed us to follow changes in phytoplankton community structure associated with the development of anoxia. Together these measurements helped establish a pattern of seasonal change of three major groups of phytoplankton: diatoms, dinoflagellates and cyanobacteria that appeared to be tightly coupled with hydrographic and chemical changes associated with the monsoonal cycle. During the SW monsoon when nitrate concentrations were high, diatoms were dominant but prymnesiophytes were present as well. By October, as nitrate fell to below detection levels and anoxic conditions began to develop on the shelf below the shallow pycnocline, both diatom and prymensiophytes declined sharply giving way to dinoflagellates. In the well oxygenated surface waters, where both nitrate and ammonium were below detection limits, pico-cyanobacterial populations became dominant. During the NE monsoon, a mixed diatom-dinoflagellate population was quickly replaced by blooms of Trichodesmium erythraeum and Noctiluca

  4. Evolution and variability of the Indian Ocean summer monsoon: Evidence from the western Arabian sea drilling program

    NASA Astrophysics Data System (ADS)

    Prell, Warren L.; Murray, David W.; Clemens, Steven C.; Anderson, David M.

    A number of forcing factors, including the tectonic evolution of Himalaya-Tibet and orbitally-induced changes in seasonal radiation, combine to cause the initiation, evolution, and variability of the Indian Ocean monsoon. Although climate model experiments can be used to estimate the variability attributed to each forcing factor, the only record of past monsoonal variation lies in the sediments of the northern Indian Ocean and the adjacent continents. A major goal of the regional survey cruise (RC27-04) and ODP Leg 117 was to recover the marine geologic record necessary to understand the history of the initiation, evolution and variability of the Indian Ocean summer monsoon and to provide an observational data set for comparison with model simulations of monsoon circulation. General Circulation Model (GCM) experiments show that orbitally-induced increases in solar radiation significantly strengthen the monsoon winds and precipitation over southern Asia, but that surface boundary conditions (including sea surface temperature, albedo) associated with glacial phases weaken monsoon winds and precipitation. Experiments with full (modem elevations) and reduced plateau-mountain elevations reveal stronger winds and higher precipitation as mountain elevation increases. These results indicate that monsoon strength is equally sensitive to changes in solar radiation (on orbital time scales) and orographic changes (on longer time scales). They also indicate that global cooling cannot intensify the monsoon, so that the onset of the monsoon is most likely related to increased mountain elevation. Sediments in the northwest Arabian Sea exhibit characteristic fauna (radiolarians and foraminifers) that are endemic to areas of strong upwelling. In the Arabian Sea, intense seasonal upwelling is induced by the southwesterly monsoon winds. Miocene to Recent sediments from the northwest Arabian Sea show distinct geochemical and biological changes which suggest that monsoonal upwelling

  5. Megafaunal responses to strong oxygen gradients on the Pakistan margin of the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Murty, Sarah J.; Bett, Brian J.; Gooday, Andrew J.

    2009-03-01

    The Arabian Sea oxygen minimum zone (OMZ), which intersects the continental margin between approximately 100 and 1200 m, is one of the world's largest deep-water oxygen-deficient water masses. We analysed megafaunal organisms seen in images obtained using a wide-angle survey photographic (WASP) system at nine sites (140-1850 m water depth) across the OMZ on the Pakistan Margin during the late-monsoon period (August-September 2003). The visible megafauna comprised: (1) the megabenthos sensu strictu ( s.s.), (2) large polychaetes and (3) the benthopelagic megafauna (fish, natant decapods and octopods). Large protozoans, mainly the foraminiferan Pelosina sp., were counted but not included in the megafauna. The megabenthos s.s. were rare at the seasonally hypoxic 140-m site (O 2=0.11 ml l -1), entirely absent in the OMZ core and most of the lower transition zone (300-900 m; O 2=0.12-0.15 ml l -1), but peaked in abundance (27.94 indiv. m -2) at 1000 m (O 2=0.16 ml l -1). Densities were much lower at 1100 and 1200 m (0.52-0.69 indiv. m -2; O 2=0.25-0.38 ml l -1), and declined to minimal values (0.01 indiv. m -2) at 1850 m (O 2=1.68 ml l -1). There was no correlation with depth, dissolved-oxygen concentration or sediment organic chemistry variables (%C org, %Total N, C:N, δ13C, δ15N). Pelosina sp. was the only strictly benthic organism visible at 400 and 700 m. Fish and natant decapods were fairly common at 300 m, and fish were the only metazoans seen in photographs from 700 m. Large polychaetes, almost certainly Linopherus sp., were very abundant in photographs from 900 m, where megabenthos s.s. were absent, and somewhat less abundant at 1000 m. Suspension-feeding cnidarians and tunicates were abundant at 1100 and 1200 m, respectively. The number of megabenthos s.s. species visible at each site ranged from six (1000 and 1850 m) to 11 (1100 and 1200 m). Diversity ( H'(log e)) was the lowest at 1000 and 1850 m and the highest at 1100 m, with intermediate values at 140

  6. Biodegradation of diesel oil by an Arabian Sea sediment culture isolated from the vicinity of an oil field.

    PubMed

    Mukherji, Suparna; Jagadevan, Sheeja; Mohapatra, Gita; Vijay, Avinash

    2004-12-01

    Laboratory scale batch studies were performed to test the diesel oil biodegradation ability of ES1 cultures isolated from Arabian Sea sediments obtained from the vicinity of an oil field. This culture could utilize diesel as the sole source of carbon and energy. Under aerobic conditions, 39% loss of diesel oil was observed over 8 days where 80% of the loss was due to aliphatic constituents. Under anoxic nitrate reducing conditions the rate and extent of degradation was significantly lower, i.e., 18% over 50 days. Salt acclimatized cultures could tolerate salinities up to 3.5% and demonstrated optimal performance at a salinity of 0.5%. The optimum N/P ratio for these cultures was found to be in the range of 2:1-5:1. Addition of two trace elemental substance formulations exhibited a significant inhibitory effect on culture growth. This culture has good potential for decontamination of oil-contaminated marine and subsurface environments.

  7. Trace metal enrichment and organic matter sources in the surface sediments of Arabian Sea along southwest India (Kerala coast).

    PubMed

    Sreekanth, Athira; Mrudulrag, S K; Cheriyan, Eldhose; Sujatha, C H

    2015-12-30

    The geochemical distribution and enrichment of trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) were determined in the surface sediments of Arabian Sea, along southwest India, Kerala coast. The results of geochemical indices indicated that surficial sediments of five transects are uncontaminated with respect to Mn, Zn and Cu, uncontaminated to moderately contaminated with Co and Ni, and moderately to strongly contaminated with Pb. The deposition of trace elements exhibited three different patterns i) Cd and Zn enhanced with settling biodetritus from the upwelled waters, ii) Pb, Co and Ni show higher enrichment, evidenced by the association through adsorption of iron-manganese nodules onto clay minerals and iii) Cu enrichment observed close to major urban sectors, initiated by the precipitation as Cu sulfides. Correlation, principal component analysis (PCA) and cluster analysis (CA) were used to confirm the origin information of metals and the nature of organic matter composition.

  8. Spatial distribution and transcriptional activity of an uncultured clade of planktonic diazotrophic gamma-proteobacteria in the Arabian sea.

    PubMed

    Bird, Clare; Martinez Martinez, Joaquín; O'Donnell, Anthony G; Wyman, Michael

    2005-04-01

    The spatial distribution of an uncultured clade of marine diazotrophic gamma-proteobacteria in the Arabian Sea was investigated by the development of a specific primer pair to amplify an internal fragment of nifH by PCR. These organisms were most readily detected in highly oligotrophic surface waters but could also be found in deeper waters below the nutricline. nifH transcripts originating from this clade were detected in oligotrophic surface waters and, in addition, in the deeper and the more productive near-coastal waters. The nifH sequences most closely related to the unidentified marine bacterial group are from environmental clones amplified from the Atlantic and Pacific Oceans. These findings suggest that these gamma-proteobacteria are widespread and likely to be an important component of the heterotrophic diazotrophic microbial community of the tropical and subtropical oceans.

  9. Sink or link? The bacterial role in benthic carbon cycling in the Arabian sea oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Pozzato, L.; Van Oevelen, D.; Moodley, L.; Soetaert, K.; Middelburg, J. J.

    2013-06-01

    The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic aquatic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea Oxygen Minimum Zone (OMZ) to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient in these sediments. Moreover, metazoans directly consume labile particulate organic matter resources and thus compete with bacteria for phytodetritus.

  10. Trace metal enrichment and organic matter sources in the surface sediments of Arabian Sea along southwest India (Kerala coast).

    PubMed

    Sreekanth, Athira; Mrudulrag, S K; Cheriyan, Eldhose; Sujatha, C H

    2015-12-30

    The geochemical distribution and enrichment of trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) were determined in the surface sediments of Arabian Sea, along southwest India, Kerala coast. The results of geochemical indices indicated that surficial sediments of five transects are uncontaminated with respect to Mn, Zn and Cu, uncontaminated to moderately contaminated with Co and Ni, and moderately to strongly contaminated with Pb. The deposition of trace elements exhibited three different patterns i) Cd and Zn enhanced with settling biodetritus from the upwelled waters, ii) Pb, Co and Ni show higher enrichment, evidenced by the association through adsorption of iron-manganese nodules onto clay minerals and iii) Cu enrichment observed close to major urban sectors, initiated by the precipitation as Cu sulfides. Correlation, principal component analysis (PCA) and cluster analysis (CA) were used to confirm the origin information of metals and the nature of organic matter composition. PMID:26602174

  11. Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone.

    PubMed

    Pitcher, Angela; Villanueva, Laura; Hopmans, Ellen C; Schouten, Stefan; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S

    2011-12-01

    Ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria have emerged as significant factors in the marine nitrogen cycle and are responsible for the oxidation of ammonium to nitrite and dinitrogen gas, respectively. Potential for an interaction between these groups exists; however, their distributions are rarely determined in tandem. Here we have examined the vertical distribution of AOA and anammox bacteria through the Arabian Sea oxygen minimum zone (OMZ), one of the most intense and vertically exaggerated OMZs in the global ocean, using a unique combination of intact polar lipid (IPL) and gene-based analyses, at both DNA and RNA levels. To screen for AOA-specific IPLs, we developed a high-performance liquid chromatography/mass spectrometry/mass spectrometry method targeting hexose-phosphohexose (HPH) crenarchaeol, a common IPL of cultivated AOA. HPH-crenarchaeol showed highest abundances in the upper OMZ transition zone at oxygen concentrations of ca. 5  μM, coincident with peaks in both thaumarchaeotal 16S rDNA and amoA gene abundances and gene expression. In contrast, concentrations of anammox-specific IPLs peaked within the core of the OMZ at 600  m, where oxygen reached the lowest concentrations, and coincided with peak anammox 16S rDNA and the hydrazine oxidoreductase (hzo) gene abundances and their expression. Taken together, the data reveal a unique depth distribution of abundant AOA and anammox bacteria and the segregation of their respective niches by >400  m, suggesting no direct coupling of their metabolisms at the time and site of sampling in the Arabian Sea OMZ.

  12. Trace and rare earth elemental variation in Arabian sea sediments through a transect across the oxygen minimum zone

    SciTech Connect

    Nath, B.N.; Rao, B.R.; Rao, C.M.; Bau, M.

    1997-06-01

    We have determined the calcium carbonate (CaCO{sub 3}), organic carbon (C{sub org}), trace element, and rare earth element (REE) composition of surface sediments collected from a transect on the central western continental shelf and slope of India in the Eastern Arabian Sea. The transect samples across the oxygen minimum zone (OMZ) allows us to compare the relative abundances of trace elements and REEs in the sediments beneath and beyond the OMZ. Shale-normalized REE patterns, La{sub n}/Yb{sub n} ratios, and Eu/Eu* anamolies indicate that the sediments in the study area are either derived from the adjoining Archaean land masses or from distal Indus source. Sediment deposited in the OMZ have high U values from 3.6 to 8.1 ppm, with their U{sub excess} (of that can be supplied by continental particles) values ranging between 82-91% of the total U, indicating that the U may be precipitated as U{sup +4} in the reducing conditions of OMZ. Sediments deposited beneath the intense OMZ (<0.2 mL/L) and away from the OMZ (1-2 mL/L) show slight negative Ce anomalies, with no significant differences between these two sets of sediments. The Ce/Ce*{sub shale} values are poorly related to U and C{sub org} which are indicators of suboxic bottom waters. Normative calculations suggest that two sources, namely, terrestrial and seawater (terrestrial > seawater) contribute to the total Ce anomaly of the sediments. The Ce anomaly values of the calculated seawater derived component are similar to the anomalies reported for other coastal waters and the oxygenated surface waters of the Arabian Sea and do not show any correspondence to the lowered redox state of the overlying water, probably due to the redirection of dissolved Ce into the oxic deeper water. 103 refs., 6 figs., 3 tabs.

  13. Live (Rose Bengal stained) foraminiferal faunas from the northern Arabian Sea: faunal succession within and below the OMZ

    NASA Astrophysics Data System (ADS)

    Caulle, Clemence; Koho, Karoliina; Mojtahid, Meryem; Reichart, Gert-Jan; Jorissen, Frans

    2014-05-01

    Live (Rose Bengal stained) benthic foraminifera from the Murray Ridge, within and below the northern Arabian Sea Oxygen Minimum Zone (OMZ), were studied in order to determine the relationship between faunal composition, bottom-water oxygenation (BWO), pore-water chemistry and organic matter (organic carbon and phytopigment) distribution. A series of multicores were recovered from a ten-station oxygen (BWO: 2µM - 78µM) and bathymetric (885 - 3010m depth) transect during the winter monsoon in January 2009. Foraminifera were investigated from three different size fractions (63-125µm, 125-150µm and >150µm). The larger foraminifera (>125µm) were strongly dominated by agglutinated species (e.g. Reophax spp.). In contrast, in the 63-125µm fraction, calcareous taxa were more abundant, especially in the core of the OMZ. On the basis of a Principal Components Analysis, three foraminiferal groups were identified and correlated to the environmental parameters by Canonical Correspondence Analysis. The faunas from the shallowest stations, in the core of the OMZ (BWO: 2µM), were composed of "low oxygen" species, typical of the Arabian Sea OMZ (e.g., Rotaliatinopsis semiinvoluta, Praeglobobulimina sp., Bulimina exilis, Uvigerina peregrina type parva). These taxa are adapted to the very low BWO conditions and to high phytodetritus supplies. The transitional group, typical for the lower part of the OMZ (BWO: 5-16µM), is composed of species, which are tolerant as well to low-oxygen concentrations, but may be less critical with respect to organic supplies (e.g. Globocassidulina subglobosa, Ehrenbergina trigona). Below the OMZ (BWO: 26-78µM), where food availability is more limited and becomes increasingly restricted to surficial sediments, cosmopolitan calcareous taxa were present, such as Bulimina aculeata, Melonis barleeanus, Uvigerina peregrina and Epistominella exigua. Miliolids were uniquely observed in this last zone, reflecting the higher BWO and/or lower organic

  14. Transfer of organic matter in the deep Arabian Sea zooplankton community: insights from δ15N analysis

    NASA Astrophysics Data System (ADS)

    Koppelmann, Rolf; Weikert, Horst

    Zooplankton samples were obtained in the central Arabian Sea using a 1 m2-MOCNESS with 333 μm mesh aperture to investigate the nitrogen stable isotopic composition of different mesozooplankton size classes (<0.5, 0.5-1, 1-2, 2-5 mm) from the surface down to 3900 m depth in intervals of ⩽500 m during April 1997 and February 1998. Samples from the upper 500 m indicated temporal differences between two years, with the lowest value (4.5 ‰) for the 1-2 mm size class between 250 and 500 m depth in April 1997 and the highest value (13.5 ‰) for the 2-5 mm size class in the same depths range in February 1998. The upper bathypelagic zone (1000-2500 m) showed an increase in δ15N with increasing depth for all size classes. In April 1997, the size-dependent distribution showed higher values in the larger size classes, indicating higher trophic levels as compared to smaller size classes. Such a size-dependent increase was not evident in February 1998. Below 2500 m, the δ15N values were more or less stable with increasing depth, or even decreased as exemplified by the smallest size class (<0.5 mm) . The size-dependent distribution for both investigated periods showed increasing δ15N values with increasing size. These results give an insight in the trophic structure of the zooplankton community in the deep Arabian Sea. Differences between size classes were less than one trophic level in the upper bathypelagic zone (1000-2500 m) and one to two trophic levels in the lower bathypelagic zone (>2500 m) . The amount of diet needed by the different mesozooplankton size classes to build up the measured biomass is estimated for the deep bathypelagic zone.

  15. Monsoon variability in the northeastern Arabian Sea on orbital- and millennial scale during the past 200,000 years

    NASA Astrophysics Data System (ADS)

    Lückge, Andreas; Groeneveld, Jeroen; Steinke, Stephan; Mohtadi, Mahyar; Westerhold, Thomas; Schulz, Hartmut

    2016-04-01

    The Dansgaard-Oeschger oscillations and Heinrich events described in the Greenland ice cores and in North Atlantic and Western Mediterranean sediments are also expressed in the climate of the tropics, for example, as documented in Arabian Sea sediments. However, little is known about these fluctuations beyond the reach of the Greenland ice cores. Here, we present high-resolution geochemical, sedimentological as well as micropaleontological data from two cores (SO130-283KL, 987m water depth and SO130-289KL, 571m) off the coast of Pakistan, extending the monsoon record on orbital and millennial scales to the past 200,000 years. The stable oxygen isotope record of the surface-dwelling planktonic foraminifer G. ruber shows a strong correspondence to Greenland ice core δ18O, whereas the deepwater δ18O signal of benthic foraminifera (U. peregrina and G. affinis) reflects patterns recorded in ice cores from Antarctica. Strong shifts in benthic δ18O during stadials/Heinrich events are interpreted to show frequent advances of oxygen-rich intermediate water masses into the Arabian Sea originating from the southern ocean. Alkenone-derived SSTs varied between 23 and 28° C. Highest temperatures were encountered during interglacial MIS 5. Rapid SST changes of 2° C magnitude on millennial scale are overlain by long-term SST fluctuations. Interstadials (of glacial phases) and the cold phases of interglacials are characterized by sediments enriched in organic carbon (up to 4 % TOC) whereas sediments with low TOC contents (< 1 % TOC) appear during stadials and Heinrich events. Shifts at climate transitions, such as onsets of interstadials, were coeval with changes in productivity-related and anoxia-indicating proxies. Interstadial inorganic elemental data consistently show that enhanced fluxes of terrestrial-derived sediments are paralleled by productivity maxima, and are characterized by an increased fluvial contribution from the Indus River. In contrast, stadials are

  16. High-resolution regional modeling of summertime transport and impact of African dust over the Red Sea and Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Kalenderski, Stoitchko; Stenchikov, Georgiy

    2016-06-01

    Severe dust outbreaks and high dust loading over Eastern Africa and the Red Sea are frequently detected in the summer season. Observations suggest that small-scale dynamic and orographic effects, from both the Arabian and African sides, strongly contribute to dust plume formation. To better understand these processes, we present here the first high-resolution modeling study of a dust outbreak in June 2012 developed over East Africa, the Red Sea, and the Arabian Peninsula. Using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) component, we identified several dust generating dynamical processes that range from convective to synoptic scales, including synoptic cyclones, nocturnal low-level jets, and cold pools of mesoscale convective systems. The simulations reveal an eastward transport of African dust across the Red Sea. Over the northern part of the Red Sea, most of the dust transport occurs above 2 km height, whereas across the central and southern parts of the sea; dust is mostly transported below 2 km height. Dust is the dominant contributor (87%) to the aerosol optical depth, producing a domain average cooling effect of -12.1 W m-2 at the surface, a warming of 7.1 W m-2 in the atmosphere, and a residual cooling of -4.9 W m-2 at the top of the atmosphere. Both dry and wet deposition processes contribute significantly to dust removal from the atmosphere. Model results compare well with available ground-based and satellite observations but generally underestimate the observed maximum values of aerosol optical depth. The satellite-retrieved mean optical depth at some locations is underestimated by a factor of 2. A sensitive experiment suggests that these large local differences may result from poor characterization of dust emissions in some areas of the modeled domain. In this case study we successfully simulate the major fine-scale dust generating dynamical processes, explicitly resolving convection and haboob formation. The future

  17. Analysis of humpback whale sounds in shallow waters of the Southeastern Arabian Sea: An indication of breeding habitat.

    PubMed

    Mahanty, Madan M; Latha, G; Thirunavukkarasu, A

    2015-06-01

    The primary objective of this work was to present the acoustical identification of humpback whales, detected by using an autonomous ambient noise measurement system, deployed in the shallow waters of the Southeastern Arabian Sea (SEAS) during the period January to May 2011. Seven types of sounds were detected. These were characteristically upsweeps and downsweeps along with harmonics. Sounds produced repeatedly in a specific pattern were referred to as phrases (PQRS and ABC). Repeated phrases in a particular pattern were referred to as themes, and from the spectrographic analysis, two themes (I and II) were identified. The variation in the acoustic characteristics such as fundamental frequency, range, duration of the sound unit, and the structure of the phrases and themes are discussed. Sound units were recorded from mid-January to mid-March, with a peak in February, when the mean SST is approx. 28 degree C, and no presence was recorded after mid-March. The temporal and thematic structures strongly determine the functions of the humpback whale song form. Given the use of song in the SEAS, this area is possibly used as an active breeding habitat by humpback whales during the winter season.

  18. Analysis of humpback whale sounds in shallow waters of the Southeastern Arabian Sea: An indication of breeding habitat.

    PubMed

    Mahanty, Madan M; Latha, G; Thirunavukkarasu, A

    2015-06-01

    The primary objective of this work was to present the acoustical identification of humpback whales, detected by using an autonomous ambient noise measurement system, deployed in the shallow waters of the Southeastern Arabian Sea (SEAS) during the period January to May 2011. Seven types of sounds were detected. These were characteristically upsweeps and downsweeps along with harmonics. Sounds produced repeatedly in a specific pattern were referred to as phrases (PQRS and ABC). Repeated phrases in a particular pattern were referred to as themes, and from the spectrographic analysis, two themes (I and II) were identified. The variation in the acoustic characteristics such as fundamental frequency, range, duration of the sound unit, and the structure of the phrases and themes are discussed. Sound units were recorded from mid-January to mid-March, with a peak in February, when the mean SST is approx. 28 degree C, and no presence was recorded after mid-March. The temporal and thematic structures strongly determine the functions of the humpback whale song form. Given the use of song in the SEAS, this area is possibly used as an active breeding habitat by humpback whales during the winter season. PMID:25963267

  19. Feeding ecology of the copepod Lucicutia aff. L. grandis near the lower interface of the Arabian Sea oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Gowing, Marcia M.; Wishner, Karen F.

    Feeding ecology of the calanoid copepod Lucicutia aff. L. grandis collected in the Arabian Sea at one station during the Spring Intermonsoon and during the Southwest Monsoon of 1995 was studied with transmission electron microscopy of gut-contents. Highest abundances of these animals occurred from ˜400 to 1100 m, near the lower interface of the oxygen minimum zone and at the inflection point where oxygen starts to increase. We expected that their gut-contents would include particles and cells that had sunk relatively undegraded from surface waters as well as those from within the oxygen minimum zone, and that gut-contents would differ between the Spring Intermonsoon and the more productive SW Monsoon. Overall, in both seasons Lucicutia aff. L. grandis was omnivorous, and consumed a variety of detrital particles, prokaryotic and eukaryotic autotrophs, gram-negative bacteria including metal-precipitating bacteria, aggregates of probable gram-positive bacteria, microheterotrophs, virus-like particles and large virus-like particles, as well as cuticle and cnidarian tissue. Few significant differences in types of food consumed were seen among life stages within or among various depth zones. Amorphous, unidentifiable material was significantly more abundant in guts during the Spring Intermonsoon than during the late SW Monsoon, and recognizable cells made up a significantly higher portion of gut-contents during the late SW Monsoon. This is consistent with the Intermonsoon as a time when organic material is considerably re-worked by the surface water microbial loop before leaving the euphotic zone. In both seasons Lucicutia aff. L. grandis had consumed what appeared to be aggregates of probable gram-positive bacteria, similar to those we had previously found in gut-contents of several species of zooplankton from the oxygen minimum zone in the eastern tropical Pacific. By intercepting sinking material, populations of Lucicutia aff. L. grandis act as a filter for carbon

  20. Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Caulle, C.; Mojtahid, M.; Gooday, A. J.; Jorissen, F. J.; Kitazato, H.

    2015-08-01

    Rose-Bengal-stained foraminiferal assemblages (> 150 μm) were analysed along a five-station bathymetric transect across the core and the lower part of the oxygen minimum zone (OMZ) on the Indian margin of the Arabian Sea. Sediment cores were collected using the manned submersible Shinkai 6500 during the RV Yokosuka cruise YK08-11 in the post-monsoon season (October 2008) at water depths ranging from 535 to 2000 m, along a gradient from almost anoxic to well-oxygenated (0.3 to 108 μM) bottom waters. Stained benthic foraminifera were investigated from two different size fractions (150-300 μm and > 300 μm). Stained foraminiferal densities were very high in the core of the OMZ (at 535 and 649 m) and decreased at deeper sites. The faunas (> 150 μm) were dominated (40-80 %) by non-calcareous taxa at all stations. These were mainly species of Reophax and Lagenammina but also included delicate monothalamous taxa (organic-walled "allogromiids", agglutinated saccamminids, psammosphaerids and tubular forms). These new data from the Indian margin are compared to previous studies from the Murray Ridge, the Pakistan margin and the Oman margin. The fact that similar species were found at sites with comparable bottom-water oxygen concentrations but with very different surface water productivity suggests that, within the strongly developed Arabian Sea OMZ, bottom-water oxygen concentration, and not the organic flux to the sea floor, is the main factor controlling the species composition of the foraminiferal communities. Several foraminiferal species (e.g. Praeglobobulimina sp. 1, Ammodiscus sp. 1, Bolivina aff. dilatata) were confined to the core of the OMZ. These species are presently known only from the Arabian Sea. Because of their association with extremely low oxygen concentrations, these species may be good markers for very low oxygen concentrations, and could be used to reconstruct past OMZ variability in the Arabian Sea.

  1. Living (Rose Bengal stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Caulle, C.; Mojtahid, M.; Gooday, A. J.; Jorissen, F. J.; Kitazato, H.

    2015-02-01

    Rose Bengal stained foraminiferal assemblages were analysed along a five-station bathymetric transect across the core and the lower part of the oxygen minimum zone (OMZ) on the Indian margin of the Arabian Sea. Sediment cores were collected using the manned submersible Shinkai 6500 during RV Yokosuka cruise YK08-11 in the post-monsoon season (October 2008) at water depths ranging from 535 to 2000 m, along a gradient from almost anoxic to well-oxygenated (0.3 to 108 μM) bottom waters. Stained foraminiferal densities were very high in the OMZ core (535 m) and decreased with depth. The faunas were dominated (40-80%) by non-calcareous taxa at all stations. These were mainly species of Reophax and Lagenammina but also included delicate monothalamous taxa (organic-walled "allogromiids", agglutinated saccamminids, psammosphaerids and tubular forms). These new data from the Indian margin are compared to previous studies from the Murray Ridge, the Pakistan margin and the Oman margin. The fact that similar species were found at sites with comparable bottom-water oxygen concentrations but with very different surface water productivity suggests that, within the strongly developed Arabian Sea OMZ, bottom-water oxygen concentration, and not the organic flux to the sea floor, is the main factor controlling the species composition of the foraminiferal communities. Several foraminiferal species (e.g. Praeglobobulimina sp. 1, Ammodiscus sp. 1, Bolivina aff. dilatata) were confined to the core of the OMZ and are presently known only from the Arabian Sea. Because of their association with extremely low-oxygen concentration, these species may prove to be good indicators of past OMZ variability in the Arabian Sea.

  2. Constraints on plate motions in southern Pakistan and the northern Arabian Sea from the focal mechanisms of small earthquakes

    NASA Astrophysics Data System (ADS)

    Quittmeyer, Richard C.; Kafka, Alan L.

    1984-04-01

    The focal mechanism and depth were determined for nine small earthquakes (M0<1025 dyn cm, M<5.5) that occurred in southern Pakistan and the northern Arabian Sea from an analysis of the vertical component of Rayleigh waves in combination with limited first-motion data. Focal parameters were determined from the Rayleigh waves by using an event-pair method of analysis. For earthquakes that are located very close to each other (<≈ 50 km), the event-pair method is able to remove a significant proportion of propagation effects at all periods in the range of interest (20-50 s). For events separated by more than ≈ 100 km the propagation effects are reduced for only the longer periods (≈ 40-50 s). The earthquakes that were studied provide evidence for a model of plate interactions in the vicinity of the southern Pakistan triple junction. The Owen fracture zone is a transform fault that accommodates right-lateral motion between the Indian and Arabian plates. The plate boundary in the vicinity of the Murray ridge is also partially made up of transform segments that strike subparallel to the Owen fracture zone. Spreading centers may also exist in the vicinity of the Murray ridge but were not documented by seismic or other evidence. The slip azimuths for earthquakes along this boundary are significantly more northerly than those predicted by various regional and worldwide models of plate motion. The Arabian plate is being subducted beneath the Eurasian plate along the southern coast of Pakistan. Slip vectors for earthquakes along this boundary trend northnortheasterly in general agreement with predicted directions. Left-lateral motion is documented along the boundary between the Indian and Eurasian plates in southern Pakistan. The predicted direction of relative motion between these plates is not significantly different from that observed. Two of the earthquakes studied appear to be intraplate in nature. The depth and focal mechanism of one intraplate event, which may

  3. Present-Day Kinematics of the Dead Sea Transform and Internal Deformation within the Sinai and Arabian Plates

    NASA Astrophysics Data System (ADS)

    Gomez, F. G.; Yassminh, R.; Cochran, W. J.; Reilinger, R. E.; Barazangi, M.

    2015-12-01

    An updated GPS velocity field along the Dead Sea Fault (DSF) provides a basis for assessing off-transform strain within the Sinai and Arabian plates along entire length of this left-lateral, continental transform. As one of the main tectonic elements in the eastern Mediterranean region, an improved kinematic view of the DSF elucidates the broader understanding of the regional tectonic framework, as well as contributes to refining the earthquake hazard assessment. Reconciling short-term (geodetic) measurements of crustal strain with neotectonic data on fault movements can yield insight into the mechanical and rheological properties of crustal deformation associated with transform tectonics. In addition to regional continuous GPS stations, this study assembles results from campaign GPS networks in Syria, Lebanon, and Jordan spanning more than a decade. 1-sigma uncertainties on velocities range from less than 0.4 mm/yr (continuous stations and older GPS survey sites) to about 1.0 mm/yr (newer survey sites). Analyses using elastic block models suggest slip rates of 4.0 - 5.0 mm/yr along the southern and central DSF and slip rates of 2.0 - 3.0 mm/yr along the northern DSF, and fault locking depths also vary along strike of the transform. Furthermore, the spatial distribution of GPS observations permits analyzing residual strains within the adjacent plates, after plate boundary strain is removed. A key observation is horizontal stretching within the Sinai plate, which may be related to pull by the subducted slab of the Sinai plate. Within the Arabian plate, areas of horizontal stretching generally correlate with locations of Quaternary volcanism.

  4. A Study of Tropical Cyclones over India (Bay of Bengal and Arabian Sea) and Solar Influence on It

    NASA Astrophysics Data System (ADS)

    Banerjee, Dhruba

    2016-07-01

    A prominent example of extreme weather event in India is Cyclonic Storm. In this paper annual variation of tropical Cyclonic Storm (CS), Severe Cyclonic Storm (SCS), Very Severe Cyclonic Storm (VSCS) and Super Cyclonic Storm (SuCS) over Bay Of Bengal (BOB) and Arabian Sea (ARS) during last 20 years (1990-2009) have been analyzed .The analysis revels that the total number of cyclone (TNC) has increased with high rate(gradient being +1.67 per year) and although C.S. is more over BOB than that over ARS.The rate of increase of C.S. over Arabian Sea is more than that over Bay of Bengal. Furthermore, two interesting features have been noted: (i) Monsoon tends to prohibit the formation of C.S (ii) Cyclonic Storm(C.S.) increases with the increase of Global Sea Surface Temperature (GSST) during said period.. Attempt has also been made to find out the influence of solar activity on these extreme weather events. Keeping in mind that the Sun Spot Number (SSN) is an indicator of the strength of solar effects, it has been found that in most of the times the high value of SSN is associated with small number of total cyclone (C.S.). Specifically, when only the years of high Sun's Spot Number (approximately greater than 90) are taken into consideration then Correlation Coefficient (C.C.) between SSN and number of cyclones comes out to be quite high (-0.78) significance at 99.99% level while Correlation Coefficient (C.C.) of cyclones with time is 0.53 and with SSN < 60 it is..095 . Thus it appears that although C.S. frequency is increasing with time, Sun's Spot's influence is such that it basically opposes the formation of cyclone provided SSN exceeds certain critical value (roughly 90). In principle, this is very important for any such event, and it is consistent with the trend of different phenomena occurring in nature. Key words: India, cyclone, solar influence, Critical Sun's Spot Number

  5. Passive Acoustic Recognition of Fishing Vessel Activity in the Shallow Waters of the Arabian Sea: A Statistical Approach

    NASA Astrophysics Data System (ADS)

    Kannan, R.; Sanjana, M. C.; Latha, G.

    2015-09-01

    The ambient noise system consisting of a vertical linear hydrophone array (VLA) with 12 elements was deployed in the waters of the Arabian Sea at a depth of 16m, off Goa, India, for extracting the ambient noise during the fishing season (March, April and May, 2013 before the onset of the south west monsoon). This study focuses on fishing vessel activity by finding the domination of the vessel and wind noise at two 12 hourly periodic cycles that start at midnight and noon, using the statistical analysis. It is performed using statistical parameters, like the mean, median, and standard deviation, skewness, percentile and spread of data. It is observed that the vessel noise dominates during the 12h period that starts at midnight and is an indication of the activity of fishing vessels while the wind generated noise is more during the 12h period that starts at noon, which is a sign of the domination of the sea breeze effects. This is the first time that a statistical analysis has been carried out to study the ambient noise data collected off Goa, in order to find the fishing vessel activity during the pre-monsoon season. The results are verified with the fishing information from the Directorate of Fisheries, Goa, ship traffic data from the Mormugao Port Trust and wind speed measurements.

  6. Acoustic Doppler current profiling from the JGOFS Arabian sea cruises aboard the RV T.G. Thompson

    SciTech Connect

    Kim, Hyun-Sook; Flagg, C.N.; Shi, Yan

    1996-06-01

    Acoustic Doppler current profiler (ADCP) data is part of the core data for the U.S. JGOFS Arabian Sea project, along with hydrographic and nutrient data. Seventeen cruises are scheduled to take place between September 1994 and January 1996 on the R/V T.G. Thompson. They are numbered consecutively from the ship`s commissioning with the first JGOFS cruise designated TN039. Table 1 lists start and end dates of each cruise with its mission. All but the first cruise have been or will be staged from Muscat, Oman. Each cruise is scheduled for a duration of between two weeks and one month. Seven of the cruises, referred to as process cruises, follow a standard cruise track, taking hydrographic, chemical and biological measurements. The rest of the cruises, which take place generally within the standard cruise region defined by a set track, are for the deployment and recovery of moored equipments and towing of a SeaSoar. ADCP data are collected using an autonomous data acquisition system developed for ship-of-opportunity cruises, named the AutoADCP system. The system is an extension of RD instrument`s DAS version 2.48 using enhancements made possible with {open_quotes}user-exit{close_quotes} programs. It makes it possible to collect ADCP data without the constant monitoring usually necessary and insures constant data coverage and uniform data quality.

  7. The release of 14C-depleted carbon from the deep ocean during the last deglaciation: Evidence from the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Bryan, Sean P.; Marchitto, Thomas M.; Lehman, Scott J.

    2010-09-01

    During the last deglaciation the concentration of CO 2 in the atmosphere increased and the radiocarbon activity (Δ 14C) of the atmosphere declined in two steps corresponding in timing to Heinrich Stadial 1 and the Younger Dryas. These changes have been attributed to the redistribution of 14C-depleted carbon from the deep ocean into the upper ocean and atmosphere. Recently, reconstructions of Δ 14C in intermediate waters of the eastern tropical Pacific have revealed pulses of very old water during the deglaciation, consistent with the release of 14C-depleted carbon from the deep ocean at this time. Here, we present reconstructions of intermediate water Δ 14C from the northern Arabian Sea near the coast of Oman. These reconstructions record significant aging of intermediate waters in the Arabian Sea during Heinrich Stadial 1 and, to a lesser extent, during the Younger Dryas. The timing and magnitude of 14C depletion in the Arabian Sea during Heinrich Stadial 1 is very similar to that previously observed in the eastern North Pacific near Baja California, indicating that similar mechanisms were involved in controlling Δ 14C at these two sites. The most parsimonious explanation of the Δ 14C records from the Arabian Sea and Baja California remains the release of 14C-depleted carbon from the deep ocean by renewal of upwelling and mixing in the Southern Ocean. These 14C-depleted waters would have been incorporated into thermocline and intermediate water masses formed in the Southern Ocean and spread northward into the Pacific, Indian and Atlantic Ocean basins.

  8. Speciation of phosphorus in the continental shelf sediments in the Eastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Acharya, Shiba Shankar; Panigrahi, Mruganka Kumar; Kurian, John; Gupta, Anil Kumar; Tripathy, Subhasish

    2016-03-01

    The distributions of various forms of phosphorus (P) and their relation with sediment geochemistry in two core sediments near Karwar and Mangalore offshore have been studied through the modified SEDEX procedure (Ruttenberg et al., 2009) and bulk chemical analysis. The present study provides the first quantitative analysis of complete phosphorus speciation in the core sediments of the Eastern Arabian shelf. The chemical index of alteration (CIA), chemical Index of Weathering (CIW) and Al-Ti-Zr ternary diagram suggest low to moderate source area weathering of granodioritic to tonalitic source rock composition, despite the intense orographic rainfall in the source area. Due to the presence of same source rock and identical oxic depositional environment, the studied sediments show the same range of variation of total phosphorus (24 to 83 μmol/g) with a down-depth depleting trend. Organic bound P and detrital P are the two major chemical forms followed by iron-bound P, exchangeable/loosely bound P and authigenic P. The authigenic P content in the sediments near Mangalore coast varies linearly with calcium (r=0.88) unlike that of Karwar coast. The different reactive-phosphorus pools exhibit identical depleting trend with depth. This indicates that the phosphorus released from the organic matter and Fe bound fractions are prevented from precipitating as authigenic phosphates in the deeper parts of the sediment column. The low concentration of total P, dominance of detrital non-reactive fraction of P and inhibition of formation of authigenic phosphate result in the absence of active phosphatization in the Eastern Arabian Shelf in the studied region. High sedimentation rate (35-58 cm/kyr) and absence of winnowing effect appear to be the dominant factor controlling the P-speciation in the studied sediments.

  9. Pore-water distribution and quantification of diffusive benthic fluxes of silicic acid, nitrate and phosphate in surface sediments of the deep Arabian Sea

    NASA Astrophysics Data System (ADS)

    Grandel, Sibylle; Rickert, Dirk; Schlüter, Michael; Wallmann, Klaus

    Benthic fluxes and pore-water compositions of silicic acid, nitrate and phosphate were investigated for surface sediments of the abyssal Arabian Sea during four cruises (1995-1998). Five sites located in the northern (NAST), western (WAST), central (CAST), eastern (EAST), and southern (SAST) Arabian Sea were revisited during intermonsoonal periods after the NE- and SW-Monsoon. At these sites, benthic fluxes of remineralized nutrients from the sediment to the bottom water of 36-106, 102-350 and 4-16 mmol m -2 yr -1 were measured for nitrate, silicic acid and phosphate, respectively. The benthic fluxes and pore-water compositions showed a distinct regional pattern. Highest fluxes were observed in the western and northern region of the Arabian Sea, whereas decreasing fluxes were derived towards the southeast. At WAST, the general temporal pattern of primary production, related to the NE- and SW-Monsoon, is reflected by benthic fluxes. In contrast, at sites NAST, SAST, CAST, and EAST a temporal pattern of fluxes in response to the monsoon is not obvious. Our results reveal a clear coupling between the general regional pattern of production in surface waters and the response of the benthic environment, as indicated by the flux of remineralized nutrients, though a spatially differing degree of decoupling during transport and remineralization of particulate organic matter and biogenic opal was observed. This has to be taken into account regarding budget calculations and paleoceanographic topics.

  10. Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall (Perciformes, Mullidae), a new subspecies of goatfish from the Red Sea and Arabian Sea.

    PubMed

    Fernandez-Silva, Iria; Randall, John E; Golani, Daniel; Bogorodsky, Sergey V

    2016-01-01

    The number of goatfish species has increased recently, thanks in part to the application of molecular approaches to the taxonomy of a family with conservative morphology and widespread intraspecific color variation. A new subspecies Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall is described from the Red Sea and Arabian Sea, including Socotra and Gulf of Oman. It is characterized by a yellow caudal fin, 25-28 gill rakers, and 37-38 lateral-line scales and it is differentiated from nominal subspecies Mulloidichthys flavolineatus flavolineatus by 1.7% sequence divergence at the mitochondrial cytochrome b gene. The morphometric examination of specimens of Mulloidichthys flavolineatus flavolineatus revealed variation in head length, eye diameter, and barbel length, in western direction from the Hawaiian Islands, South Pacific, Micronesia, and the East Indies to the Indian Ocean. The population of Mulloidichthys flavolineatus flavicaudus subsp. n. in the Gulf of Aqaba differs from that of the remaining Red Sea by shorter barbels, smaller eyes, shorter head, and shorter pelvic fins. We present a list of 26 endemic fishes from the Gulf of Aqaba and discuss the probable basis for the endemism in the light of the geological history of this region.

  11. Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall (Perciformes, Mullidae), a new subspecies of goatfish from the Red Sea and Arabian Sea.

    PubMed

    Fernandez-Silva, Iria; Randall, John E; Golani, Daniel; Bogorodsky, Sergey V

    2016-01-01

    The number of goatfish species has increased recently, thanks in part to the application of molecular approaches to the taxonomy of a family with conservative morphology and widespread intraspecific color variation. A new subspecies Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall is described from the Red Sea and Arabian Sea, including Socotra and Gulf of Oman. It is characterized by a yellow caudal fin, 25-28 gill rakers, and 37-38 lateral-line scales and it is differentiated from nominal subspecies Mulloidichthys flavolineatus flavolineatus by 1.7% sequence divergence at the mitochondrial cytochrome b gene. The morphometric examination of specimens of Mulloidichthys flavolineatus flavolineatus revealed variation in head length, eye diameter, and barbel length, in western direction from the Hawaiian Islands, South Pacific, Micronesia, and the East Indies to the Indian Ocean. The population of Mulloidichthys flavolineatus flavicaudus subsp. n. in the Gulf of Aqaba differs from that of the remaining Red Sea by shorter barbels, smaller eyes, shorter head, and shorter pelvic fins. We present a list of 26 endemic fishes from the Gulf of Aqaba and discuss the probable basis for the endemism in the light of the geological history of this region. PMID:27551217

  12. Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall (Perciformes, Mullidae), a new subspecies of goatfish from the Red Sea and Arabian Sea

    PubMed Central

    Fernandez-Silva, Iria; Randall, John E.; Golani, Daniel; Bogorodsky, Sergey V.

    2016-01-01

    Abstract The number of goatfish species has increased recently, thanks in part to the application of molecular approaches to the taxonomy of a family with conservative morphology and widespread intraspecific color variation. A new subspecies Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall is described from the Red Sea and Arabian Sea, including Socotra and Gulf of Oman. It is characterized by a yellow caudal fin, 25–28 gill rakers, and 37–38 lateral-line scales and it is differentiated from nominal subspecies Mulloidichthys flavolineatus flavolineatus by 1.7% sequence divergence at the mitochondrial cytochrome b gene. The morphometric examination of specimens of Mulloidichthys flavolineatus flavolineatus revealed variation in head length, eye diameter, and barbel length, in western direction from the Hawaiian Islands, South Pacific, Micronesia, and the East Indies to the Indian Ocean. The population of Mulloidichthys flavolineatus flavicaudus subsp. n. in the Gulf of Aqaba differs from that of the remaining Red Sea by shorter barbels, smaller eyes, shorter head, and shorter pelvic fins. We present a list of 26 endemic fishes from the Gulf of Aqaba and discuss the probable basis for the endemism in the light of the geological history of this region. PMID:27551217

  13. Live (Rose Bengal stained) foraminiferal faunas from the northern Arabian Sea: faunal succession within and below the OMZ

    NASA Astrophysics Data System (ADS)

    Caulle, C.; Koho, K. A.; Mojtahid, M.; Reichart, G. J.; Jorissen, F. J.

    2014-02-01

    Live (Rose Bengal stained) benthic foraminifera from the Murray Ridge, within and below the northern Arabian Sea oxygen minimum zone (OMZ), were studied in order to determine the relationship between faunal composition, bottom water oxygenation (BWO), pore water chemistry and organic matter (organic carbon and phytopigment) distribution. A series of multicores were recovered from a ten-station oxygen (BWO: 2-78 μM) and bathymetric (885-3010 m depth) transect during the winter monsoon in January 2009. Foraminifera were investigated from three different size fractions (63-125 μm, 125-150 μm and >150 μm). The larger foraminifera (>125 μm) were strongly dominated by agglutinated species (e.g. Reophax spp.). In contrast, in the 63-125 μm fraction, calcareous taxa were more abundant, especially in the core of the OMZ. On the basis of a principal components analysis, three foraminiferal groups were identified and correlated to the environmental parameters by canonical correspondence analysis. The faunas from the shallowest stations, in the core of the OMZ (BWO: 2 μM), were composed of "low oxygen" species, typical of the Arabian Sea OMZ (e.g. Rotaliatinopsis semiinvoluta, Praeglobobulimina sp., Bulimina exilis, Uvigerina peregrina type parva). These taxa are adapted to the very low BWO conditions and to high phytodetritus supplies. The transitional group, typical for the lower part of the OMZ (BWO: 5-16 μM), is composed of species that are tolerant as well to low-oxygen concentrations, but may be less critical with respect to organic supplies (e.g. Globocassidulina subglobosa, Ehrenbergina trigona). Below the OMZ (BWO: 26-78 μM), where food availability is more limited and becomes increasingly restricted to surficial sediments, cosmopolitan calcareous taxa were present, such as Bulimina aculeata, Melonis barleeanus, Uvigerina peregrina and Epistominella exigua. Miliolids were uniquely observed in this last zone, reflecting the higher BWO and/or lower organic

  14. How a seven-year ocean observatory is influencing our understanding of physical and biological processes in northern Arabian Sea?

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Dimarco, S. F.; Al-Kharusi, L. H.; Belabbassi, L.; Ingle, S.

    2012-12-01

    An ocean observatory—consisting of a real-time, cabled system in the Sea of Oman and an internally-recording, autonomous mooring system recently upgraded to a cabled system in the northern Arabian Sea—was installed in 2005. The two arrays have collected a continuous seven-year time series record of current velocities, temperature, pressure, salinity, dissolved oxygen, and turbidity in a region where several water masses converge and subsequently spread southward to the Indian Ocean. The systems have provided new insights into physical and biological oceanographic processes of the northwestern Indian Ocean, which is strongly affected by the monsoonal oscillation, along with lessons learned and best practices in the operation and application of ocean observatories to ocean science. In this presentation, we show four recent studies for the scientific highlights derived from the data collected from the two systems and supporting data from other sources. The topics of those four studies include: (1) The seasonality associated with the upwelling of low oxygen water on the northern Oman coast and insights on the inter-annual variability of this process; (2) The deep-water oceanic responses excited by the passage of Cyclone Gonu, the largest-ever recorded cyclone in the region; (3) The temporal and spatial evolution of an acoustic backscatter layer; (4) The pulse-like salinity/temperature events in the northeastern Arabian Sea and Gulf of Oman. In summary, the observatory provides a long-term time series with which to perform basic scientific research related to characterizing the general dynamical patterns of the region, quantifying seasonal variability of water column properties, and establishing a time series of sufficient duration to deduce the potential impacts of climate change. Furthermore, observations taken over the full, 20+ year lifetime of a typical cabled system will be extremely useful for evaluating numerical ocean circulation and coupled atmospheric

  15. Mechanisms and Effects of Summertime Transport of African Dust Through the Tokar Mountain Gap to the Red Sea and Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Kalenderski, S.; Stenchikov, G. L.

    2015-12-01

    Very high dust loading over the Red Sea region in summer strongly affects the nutrition balance and thermal and dynamic regimes of the sea. The observations suggest that small-scale local dynamic and orographic effects, from both the Arabian and African sides, strongly contribute to dust plume formation. To better understand and quantify these processes we present here the first high resolution modeling study of the dust outbreak phenomena in June 2012 over East Africa, the Red Sea, and the Arabian Peninsula using the WRF-Chem model. We identified several dust generating dynamical processes that range from convective to synoptic scales, including: synoptic cyclones, nocturnal low-level jets, and cold pools of mesoscale convective systems. The simulations reveal an eastward transport of African dust across the Red Sea. Over the northern part of the Red Sea most of the dust transport occurs beyond 2 km above ground level and is strengthened by a pressure gradient formed by low pressure over the eastern Mediterranean and high pressure over the Arabian Peninsula. Across the central and southern parts of the Red Sea dust is mostly transported below 2 km height. During the study period dust is a dominant contributor (87%) to aerosol optical depth (AOD), producing a domain average cooling effect of -12.1 W m-2 at surface, a warming of 7.1 W m-2 in the atmosphere, and a residual cooling of -4.9 W m-2 at the top of the atmosphere. WRF-Chem simulations demonstrate that both dry and wet deposition processes contribute significantly to dust removal from the atmosphere. During the dust outbreak 49.2 Tg of dust deposits within the calculation domain, which is approximately 90% of the total dust emission of 54.5 Tg. Model results compare well with available ground-based and satellite observations but generally underestimate the observed AOD maximum values.

  16. Decadal- to biennial scale variability of planktic foraminifera in the northeastern Arabian Sea during the last two millennia: evidence for winter monsoon forcing mechanisms

    NASA Astrophysics Data System (ADS)

    Munz, Philipp; Lückge, Andreas; Siccha, Michael; Kucera, Michal; Schulz, Hartmut

    2015-04-01

    The Asian monsoon system is controlling the hydrologic cycle, and thus the agricultural and economic prosperity of the worlds most densely populated region. Strong and moisture-laden winds from the southwest induce upwelling and significant productivity in the western Arabian Sea during boreal summer. During boreal winter, weaker dry and cold surface winds from the northeast nourish ocean productivity mainly in the northeastern Arabian Sea. Instrumental records spanning the last century are too short to understand how the monsoon system reacts to external forcing mechanisms and to accurately determine its natural variability. Compared to the summer monsoon component, the dynamics of the winter monsoon are virtually unknown, due to the lack of adequate archives that are affected only by winter conditions. Here we present a decadal- to biennial-scale resolution record of past winter monsoon variability over the last two millennia, based on census counts of planktic foraminifera from two laminated sediment cores collected offshore Pakistan. One shorter box core (SO90-39KG) spans the last 250 years with an average ~2-year resolution, whereas the longer piston core (SO130-275KL) spans the last 2,100 years with a 10-year resolution. We use Globigerina falconensis as a faunal indicator for winter conditions, a species that is most abundant during winter in the NE Arabian Sea (Peeters and Brummer, 2002; Schulz et al., 2002). Our results show that during the past 2,100 years G. falconensis varied with significant periodicities centered on ˜ 60, ˜ 53, ˜ 40, ˜ 34 and ˜ 29 years per cycle. Some of these periods closely match cycles that are known from proxy records of solar irradiance, suggesting a solar forcing on winter monsoon variability. During the past 250 years G. falconensis varied in correlation with the (11-year) Schwabe and the (22-year) Hale solar cycles. Furthermore, a significant ˜ 7 year cyclicity could indicate a teleconnection to the El Niño Southern

  17. Determination and distribution of cry-type genes in halophilc Bacillus thuringiensis isolates of Arabian Sea sedimentary rocks.

    PubMed

    Baig, Deeba Noreen; Mehnaz, Samina

    2010-07-20

    Bacillus thuringiensis produces insecticidal crystal during its sporulation phase. In this study, marine sediments from Arabian Sea along coastal area of Pakistan were examined for the occurrence of B. thuringiensis. On the basis of morphological and biochemical properties, 31 out of 200 colonies were assigned to B. thuringiensis. Isolated strains were characterized on the basis of cry genes profile. PCR approach was used to analyze the presence of different crystal toxin encoding genes with six pairs of universal primers that could detect the cry1, cry4, cry7, cry8, cry9, and cry10 genes. Strains containing cry1 genes were the most abundant in our collection (49.5%). Seventeen different profiles of cry genes were identified, i.e., twelve harboring two cry genes while five profiles of more than two cry genes. The characterization of these strains provided useful information on the ecological patterns of distribution of B. thuringiensis and opportunities for the selection of new strains to develop novel bio-insecticidal products.

  18. Genetic and ecophysiological traits of Synechococcus strains isolated from coastal and open ocean waters of the Arabian Sea.

    PubMed

    Bemal, Suchandan; Anil, Arga Chandrashekar

    2016-11-01

    The picocyanobacterium Synechococcus is a prominent primary producer in the marine environment. The marine Synechococcus strains are clustered into different clades representing ecologically distinct genotypes. In this study, we compared phylogeny, photophysiology and cell cycles of four novel phycoerythrin-containing Synechococcus strains (clade II of subcluster 5.1) isolated from different depths of the water column (surface and subsurface waters) in coastal and offshore regions of the eastern Arabian Sea. The surface water strains possessed a lesser number of thylakoid layers and had a higher zeaxanthin to chlorophyll a ratio than subsurface strains indicating possible influence of light intensity available at their niche. The DNA distribution pattern of the four strains was bimodal in optimal cellular physiology conditions with cell division restricted to the light period and synchronized with the light-dark cycle. The presence of phycourobilin or phycoerythrobilin and the ratio between these two chromophores in all four strains varied according to available spectral wavelength in situ This study indicates that the timing of cell division is conserved within these genotypically identical Synechococcus strains, despite their having different chromophore ratios. We conclude that the timing of cell division of the Synechococcus strains has a genetic basis rather than being determined by phenotypic characters, such as chromophore content and ratio. PMID:27495242

  19. Microcotyle omanae n. sp. (Monogenea: Microcotylidae), a parasite of Cheimerius nufar (Valenciennes) (Sparidae) from the Arabian Sea.

    PubMed

    Machkewskyi, Volodymyr K; Dmitrieva, Evgenija V; Al-Jufaili, Sara; Al-Mazrooei, Nashwa A M

    2013-10-01

    Microcotyle omanae n. sp. (Monogenea: Microcotylidae) is described from the gills of Cheimerius nufar (Valenciennes) (Sparidae) from the Arabian Sea. The new species closely resembles Microcotyle arripis Sandars, 1945, M. helotes Sandars, 1944, M. caudata Goto, 1984 and M. sebastis Goto, 1984, which have also been found in the Indo-Pacific. Microcotyle omanae n. sp. differs from M. arripis, M. helotes and M. caudata by its greater number of testes, from M. arripis, M. helotes by its greater length of the genital atrium, length/width ratio of the genital atrium and length of the eggs, and from M. helotes also in greater width of the clamps, from M. caudata and M. sebastis in its greater number of clamps and additionally from M. sebastis by its smaller genital atrial spines and clamps and by the ratio between length and width of the genital atrium. Moreover, the mature specimens of the new species have greater average body length than all above mentioned species. Correlations between 15 morphometric characters and body length are analysed in the new species, and their significance for species differentiation is discussed.

  20. Defining the niche of Vibrio parahaemolyticus during pre- and post-monsoon seasons in the coastal Arabian Sea.

    PubMed

    Rehnstam-Holm, A-S; Atnur, V; Godhe, A

    2014-01-01

    The bacteria Vibrio parahaemolyticus is an important component of coastal ecosystems worldwide, and in recent years, V. parahaemolyticus has caused several cases of food-borne gastroenteritis. However, research investigating which parameters are important in regulating V. parahaemolyticus abundance in tropical areas with relatively stable temperatures and salinity are largely lacking. The objective here was to investigate which environmental forces are driving elevated abundances of V. parahaemolyticus in a tropical oligotrophic coastal area in the Arabian Sea. We analysed a large number of environmental parameters in parallel with cell densities of V. parahaemolyticus and Vibrio spp. Abundance data was obtained using real-time PCR, during two different sampling periods, representative for two distinct seasons. Water temperature and salinity were stable during and between sampling periods, but V. parahaemolyticus abundances were on average six times higher during the first sampling period in December, compared to the second period in February-March. V. parahaemolyticus abundance was found to be positively correlated to inorganic phosphate concentration and copepod abundance. We thus hypothesise that these are important factors regulating V. parahaemolyticus abundance in coastal tropical areas during these periods.

  1. Genetic and ecophysiological traits of Synechococcus strains isolated from coastal and open ocean waters of the Arabian Sea.

    PubMed

    Bemal, Suchandan; Anil, Arga Chandrashekar

    2016-11-01

    The picocyanobacterium Synechococcus is a prominent primary producer in the marine environment. The marine Synechococcus strains are clustered into different clades representing ecologically distinct genotypes. In this study, we compared phylogeny, photophysiology and cell cycles of four novel phycoerythrin-containing Synechococcus strains (clade II of subcluster 5.1) isolated from different depths of the water column (surface and subsurface waters) in coastal and offshore regions of the eastern Arabian Sea. The surface water strains possessed a lesser number of thylakoid layers and had a higher zeaxanthin to chlorophyll a ratio than subsurface strains indicating possible influence of light intensity available at their niche. The DNA distribution pattern of the four strains was bimodal in optimal cellular physiology conditions with cell division restricted to the light period and synchronized with the light-dark cycle. The presence of phycourobilin or phycoerythrobilin and the ratio between these two chromophores in all four strains varied according to available spectral wavelength in situ This study indicates that the timing of cell division is conserved within these genotypically identical Synechococcus strains, despite their having different chromophore ratios. We conclude that the timing of cell division of the Synechococcus strains has a genetic basis rather than being determined by phenotypic characters, such as chromophore content and ratio.

  2. Fungal diversity in oxygen-depleted regions of the Arabian Sea revealed by targeted environmental sequencing combined with cultivation.

    PubMed

    Jebaraj, Cathrine S; Raghukumar, Chandralata; Behnke, Anke; Stoeck, Thorsten

    2010-03-01

    In order to study fungal diversity in oxygen minimum zones of the Arabian Sea, we analyzed 1440 cloned small subunit rRNA gene (18S rRNA gene) sequences obtained from environmental samples using three different PCR primer sets. Restriction fragment length polymorphism (RFLP) analyses yielded 549 distinct RFLP patterns, 268 of which could be assigned to fungi (Dikarya and zygomycetes) after sequence analyses. The remaining 281 RFLP patterns represented a variety of nonfungal taxa, even when using putatively fungal-specific primers. A substantial number of fungal sequences were closely related to environmental sequences from a range of other anoxic marine habitats, but distantly related to known sequences of described fungi. Community similarity analyses suggested distinctively different structures of fungal communities from normoxic sites, seasonally anoxic sites and permanently anoxic sites, suggesting different adaptation strategies of fungal communities to prevailing oxygen conditions. Additionally, we obtained 26 fungal cultures from the study sites, most of which were closely related (>97% sequence similarity) to well-described Dikarya. This indicates that standard cultivation mainly produces more of what is already known. However, two of these cultures were highly divergent to known sequences and seem to represent novel fungal groups on high taxonomic levels. Interestingly, none of the cultured isolates is identical to any of the environmental sequences obtained. Our study demonstrates the importance of a multiple-primer approach combined with cultivation to obtain deeper insights into the true fungal diversity in environmental samples and to enable adequate intersample comparisons of fungal communities.

  3. Sink or link? The bacterial role in benthic carbon cycling in the Arabian Sea's oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Pozzato, L.; Van Oevelen, D.; Moodley, L.; Soetaert, K.; Middelburg, J. J.

    2013-11-01

    The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea's oxygen minimum zone (OMZ) to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the 7 day experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient, in sediments both inside and outside the OMZ. Moreover, metazoans directly consumed labile particulate organic matter resources and thus competed with bacteria for phytodetritus.

  4. Sedimentary pigments and nature of organic matter within the oxygen minimum zone (OMZ) of the Eastern Arabian Sea (Indian margin)

    NASA Astrophysics Data System (ADS)

    Rasiq, K. T.; Kurian, S.; Karapurkar, S. G.; Naqvi, S. W. A.

    2016-07-01

    Sedimentary pigments, carbon and nitrogen content and their stable isotopes were studied in three short cores collected from the oxygen minimum zone (OMZ) of the Eastern Arabian Sea (EAS). Nine pigments including chlorophyll a and their degradation products were quantified using High Performance Liquid Chromatography (HPLC). Astaxanthin followed by canthaxanthin and zeaxanthin were the major carotenoids detected in these cores. The total pigment concentration was high in the core collected from 500 m water depth (6.5 μgg-1) followed by 800 m (1.7 μgg-1) and 1100 m (1.1 μgg-1) depths respectively. The organic carbon did not have considerable control on sedimentary pigments preservation. Pigment degradation was comparatively high in the core collected from the 800 m site which depended not only the bottom dissolved oxygen levels, but also on the faunal activity. As reported earlier, the bottom water dissolved oxygen and presence of fauna have good control on the organic carbon accumulation and preservation at Indian margin OMZ sediments. The C/N ratios and δ13C values for all the cores conclude the marine origin of organic matter and δ15N profiles revealed signature of upwelling associated denitrification within the water column.

  5. Phytoplankton along the coastal shelf of an oligotrophic hypersaline environment in a semi-enclosed marginal sea: Qatar (Arabian Gulf)

    NASA Astrophysics Data System (ADS)

    Quigg, Antonietta; Al-Ansi, Mohsin; Al Din, Nehad Nour; Wei, Chih-Lin; Nunnally, Clifton C.; Al-Ansari, Ibrahim S.; Rowe, Gilbert T.; Soliman, Yousria; Al-Maslamani, Ibrahim; Mahmoud, Ismail; Youssef, Nabiha; Abdel-Moati, Mohamed A.

    2013-06-01

    Phytoplankton biomass (chlorophyll a concentration), primary production, abundance, species diversity and species groupings were measured in the coastal waters surrounding Qatar (Arabian Gulf) at 13 stations in February 2010, July 2010, February 2011 and May 2011. In addition, a broad suite of physico-chemical characteristics were measured: temperature, salinity, pH, dissolved oxygen, turbidity, and nutrients (dissolved and particulate). Waters surrounding the Qatari peninsula were found to be highly diverse (125 species of diatoms, dinoflagellates and cyanobacteria were identified) but were low in both biomass (0.18-2.19 μg Chl a l-1) and productivity (0.14-0.97 mg C m-2 day-1). Phytoplankton physiology (Fv/Fm, σPSII, τQa, p) revealed acclimation strategies consistent with phytoplankton populations receiving ample light but insufficient nutrients. The finding of low primary production is consistent with water column nutrient ratios (DIN:P and DIN:Si ratios<1) and nutrient enrichment experiments in which the addition of nitrate or the addition of near-bottom waters stimulated biomass production of phytoplankton. This study in an oligotrophic, hypersaline semi-enclosed marginal sea is intended to contribute to the growing body of ecological information on this ecosystem functions.

  6. Tectonic configuration of the western Arabian continental margin, southern Red Sea, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Bohannon, R.G.

    1987-01-01

    A tectonic reconstruction of pre-Red Sea Afro/Arabia suggests that the early rift was narrow with intense extension confined to an axial belt 20 to 40 km wide. Steep Moho slopes probably developed during rift formation as indicated by published gravity data, two published seismic interpretations and the surface geology.

  7. Past Temperature and Salinity of the Eastern Arabian Sea: Implications to Sun-Monsoon Precipitation Relationship over Past Couple of Millennia

    NASA Astrophysics Data System (ADS)

    Tiwari, Manish; Nagoji, Siddhesh; Ganeshram, Raja

    2016-04-01

    Eastern Arabian Sea is one of the few regions from where not many high-resolution records of sea surface temperature (SST) and salinity exist despite its hydrological importance vis-à-vis South Asian summer monsoon precipitation. During this period, significant changes in salinity occur in the eastern Arabian Sea due to orographic precipitation and runoff. Additionally, minimal bioturbation occurs in coastal sediments accumulating rapidly due to the presence of an oxygen minima zone (OMZ) in the Arabian Sea. The sediment core used in this study was collected offshore Mangalore from the middle of the OMZ from a water depth of 589 m. The core spans a period of 154 to 4772 yr BP. The average sedimentation rate is 8.96 cm/Kyr while the average resolution is ˜112 yrs/cm. The stable oxygen isotope content (δ18Oc) was determined on the planktic foraminifera Globigerinoides ruber while the past SST variations were determined using an independent parameter - Mg/Ca - in the same species. The salinity was obtained by delineating SST from the δ18Oc using empirical equations. The salinity varies from a maximum of 35.5 (arid) to a minimum of 32.4 (wet) while the SST varies from varies from a maximum of 29.9° C to a minimum of 27.5° C - a variability of 2.4° C. Such high variability could be during to its coastal location, which is affected by moderate upwelling during monsoon season. The long-term trend determined through linear regression shows that the salinity has been increasing since mid-Holocene implying increasing aridity. We identify periods of aridity during the Little Ice Age (and a few centuries prior to it) and at 1300 yr BP, 2000 yr BP, and 4600 yr BP. A few paleomonsoon records also exhibit prominent correspondence with solar activity during early Holocene and beyond. But despite the strong recent solar minima (e.g. Maunder, Spörer, Oort, Wolf), their correlation with monsoon precipitation is weak and inconclusive. Additionally, those from the western

  8. Vertical zonation and distributions of calanoid copepods through the lower oxycline of the Arabian Sea oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Wishner, Karen F.; Gelfman, Celia; Gowing, Marcia M.; Outram, Dawn M.; Rapien, Mary; Williams, Rebecca L.

    2008-08-01

    This paper provides the first comprehensive analysis of calanoid copepod vertical zonation and community structure at midwater depths (300-1000 m) through the lower oxygen gradient (oxycline) (0.02 to ∼0.3 ml/L) of an oxygen minimum zone (OMZ). Feeding ecology was also analyzed. Zooplankton were collected with a double 1 m 2 MOCNESS plankton net in day and night vertically-stratified oblique tows from 1000 m to the surface at six stations during four seasons as part of the 1995 US Joint Global Ocean Flux Study (JGOFS) Arabian Sea project. The geographic comparison between a eutrophic more oxygenated onshore station and an offshore station with a strong OMZ served as a natural experiment to elucidate the influence of depth, oxygen concentration, season, food resources, and predators on the copepod distributions. Copepod species and species assemblages of the Arabian Sea OMZ differed in their spatial and vertical distributions relative to environmental and ecological characteristics of the water column and region. The extent and intensity of the oxycline at the lower boundary of the OMZ, and its spatial and temporal variability over the year of sampling, was an important factor affecting distributional patterns. Calanoid copepod species showed vertical zonation through the lower OMZ oxycline. Clustering analyses defined sample groups with similar copepod assemblages and species groups with similar distributions. No apparent diel vertical migration for either calanoid or non-calanoid copepods at these midwater depths was observed, but some species had age-related differences in vertical distributions. Subzones of the OMZ, termed the OMZ Core, the Lower Oxycline, and the Sub-Oxycline, had different copepod communities and ecological interactions. Major distributional and ecological changes were associated with surprisingly small oxygen gradients at low oxygen concentrations. The calanoid copepod community was most diverse in the most oxygenated environments (oxygen

  9. Temperature and aridity of the African-Arabian desert belt since 1750 CE reconstructed from Red Sea coral Sr/Ca and δ18O

    NASA Astrophysics Data System (ADS)

    Felis, T.; Rimbu, N.; Ionita, M.; Kölling, M.

    2015-12-01

    Throughout the desert regions of the globe, annually to seasonally resolved proxy records of temperature and aridity that extend the short observational record are sparse. For the African-Arabian desert belt, proxy records of temperature are virtually absent in reconstructions of continental-scale temperature variability during the past millennia. Here we present a new reconstruction of temperature from the African-Arabian desert belt back to 1750 CE, derived from bimonthly analysis of the Sr/Ca-temperature proxy in a northern Red Sea Porites coral (Ras Umm Sidd, Sinai, Egypt). The annual average coral Sr/Ca record is significantly correlated with land surface temperature throughout the eastern Sahara and the Arabian Desert during the last century. The coral Sr/Ca record is also significantly correlated with sea surface temperature (SST) in the Red Sea, Mediterranean Sea and North Atlantic Ocean, but not with Indian Ocean SST. Correlation with sea level pressure (SLP) fields identifies the advection of relatively cold continental air from southeastern Europe toward the Middle East and northeastern Africa as physical mechanism that controls temperature variability at interannual timescales. We combined the Sr/Ca record with a previously reported δ18O record from the same coral, and generated an annually resolved reconstruction of seawater δ18O. Correlation of the annual seawater δ18O reconstruction with SLP and 850 hPa geopotential height fields identifies the advection of relatively dry desert air from the eastern Sahara toward the northern Red Sea as physical mechanism that controls seawater δ18O variability at interannual timescales. This regional mechanism is associated with large-scale SLP anomalies of opposite sign throughout the Northern Hemisphere subtropics and the Arctic. The most striking feature of the seawater δ18O reconstruction is an abrupt regime shift toward fresher conditions in northern Red Sea surface waters between 1850 and 1855 CE. Because

  10. Premonsoon shortwave aerosol radiative forcings over the Arabian Sea and tropical Indian Ocean: Yearly and monthly mean variabilities

    NASA Astrophysics Data System (ADS)

    Ramachandran, S.

    2005-04-01

    The yearly and monthly mean variations in the clear-sky shortwave aerosol direct radiative forcings are estimated over Coastal India (CI), the Arabian Sea (AS), and tropical Indian Ocean (TIO) during winter monsoon seasons of 1996-2000. The 5-year mean TOA forcings are estimated to be -10, -9, and -4 W m-2 over CI, AS, and TIO. Surface (SFC) forcings are estimated to be -29, -22, and -5 W m-2 over CI, AS, and TIO, respectively. Atmosphere absorptions are quite large over CI and AS at +19 and +13 W m-2, indicating a significant influence of soot emitted from fossil fuel, biomass burning, and mineral dust. The yearly and monthly mean aerosol forcings are found to exhibit variations. The large atmospheric absorption estimated over CI and AS is found to be a feature of the other polluted ocean and land regions. The influence of relative humidity on the aerosol forcing is estimated. It is shown that as the single scattering albedo increases, the TOA forcing increases while the SFC forcing decreases. With an increase in aerosol optical depths the forcings at TOA and SFC are found to increase substantially, while an increase in the asymmetry parameter is found to decrease both TOA and SFC forcings. The effective factors (forcing at 80% RH/forcing at 30% RH) for the surface are found to be about 1.2 over CI, AS, and 1.4 over TIO. The effective factors estimated over these oceanic regions are found to be smaller than those obtained over the southeastern United States and the mid-Atlantic coast, indicating that the composition of aerosols found over these regions is different.

  11. Characterization of harmful algal blooms (HABs) in the Arabian Gulf and the Sea of Oman using MERIS fluorescence data

    NASA Astrophysics Data System (ADS)

    Zhao, Jun; Temimi, Marouane; Ghedira, Hosni

    2015-03-01

    In this study, MERIS fluorescence data were utilized to monitor a toxin-producing dinoflagellate Cochlodinium bloom in 2008 in the Arabian Gulf and the Sea of Oman. The bloom was characterized using modified fluorescence line height (MFLH), enhanced Red-Green-Blue (ERGB) and true color composites, and the ratio of particulate backscattering (bbp) to MFLH (bbp/MFLH). In addition to high MFLH values and dark colors in ERGB images which are generally observed when blooms happen, it was found that the Cochlodinium bloom indicated species-specific signatures which consisted of reddish brown colors in true color composites and bbp/MFLH values below 0.2 mW-1 cm2 μm m-1 sr. Based on these findings, Cochlodinium blooms were successfully distinguished from blooms dominated by other species that were found in the study area, like diatom, Noctiluca, and Trichodesmium. Qualitative analysis showed that the fluorescence-based approach presented better performance than the chlorophyll-a anomaly approach for HAB detection, despite the sensitivity to atmospheric perturbations, benthic vegetation in coastal shallow waters, and variations in environmental conditions. The applicability of the HAB characterization approach tested for the first time over the study area using MERIS data was discussed and can be anticipated with sufficient knowledge of local bloom history. Combing different ocean color products is strongly recommended to improve our understanding of HAB dynamics and enhance our ability to characterize them. This is of great importance for marine environment protection and management and can lead to valuable information for contingency planning.

  12. Live-dead agreement of benthic communities under pressure by chronic oil pollution in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Albano, Paolo G.; Tomašových, Adam; Stachowitsch, Michael; Filippova, Nadezhda; Steger, Jan; Zuschin, Martin

    2014-05-01

    Mismatch between the richness or species composition of a death assemblage (DA) and the local living assemblage (LA) is typically attributed to natural post-mortem processes, particularly preservational bias. Recent research, however, suggests that live-dead (LD) agreement is significantly lower in anthropogenically disturbed settings. This reflects the so-called "compositional inertia" of DAs to recent environmental change, i.e., DAs still capture earlier community states not affected by such disturbance. The inertia to changing ecological conditions should be particularly likely under conditions of anthropogenic modification because the rapidity of many human-driven changes is unprecedented in natural systems. Our research tests this hypothesis by evaluating the agreement between the LA and DA in benthic communities around the Zakum oil field in the Southern Arabian Sea, off the coast of the United Arab Emirates. This is an area of intense oil extraction, with almost 800 offshore oil and gas platforms and 25 major terminals, but no studies on the related impacts are widely available. This approach also sheds light on chronic pollution in tropical settings, an underrepresented topic in the literature. The size fraction between 2 and 5 mm was sorted for living molluscs and empty shells, which were then segregated to morphospecies and identified. The agreement was evaluated in terms of fidelity of species richness, evenness, and rank-order agreement. Compositional fidelity was also evaluated by multivariate analysis. The communities are dominated by bivalves. Polyplacophorans and scaphopods are occasionally present. Gastropod abundance is marginal compared to the bivalves, although their contribution is more significant when species diversity is taken into consideration. Moreover, the living assemblage in the studied size range was particularly poor in terms of species abundance.

  13. Surface distributions of O 3, CO and hydrocarbons over the Bay of Bengal and the Arabian Sea during pre-monsoon season

    NASA Astrophysics Data System (ADS)

    Srivastava, S.; Lal, S.; Venkataramani, S.; Gupta, S.; Sheel, V.

    2012-02-01

    Mixing ratios of ozone (O 3), carbon monoxide (CO), methane (CH 4) and few light non methane hydrocarbons (NMHCs) were measured on board the ocean research vessel Sagar Kanya over the Bay of Bengal and the Arabian Sea during the spring of 2006 as a part of an Integrated Campaign for Aerosol, gases and Radiation Budget (ICARB). North-westerly winds prevailing during this period transport large amount of anthropogenic pollutants from the Indo-Gangetic Plain (IGP) to the northern part of Bay of Bengal. The south-westerly and north-westerly winds carried cleaner marine air having lower abundance of pollutants over the southern Bay of Bengal and Arabian Sea. Ozone, CH 4, CO, ethane and n-butane are found to be well correlated with each other over the northern Bay of Bengal indicating their common co-located sources. The latitudinal gradients of these species are found to be significant (O 3 ˜ 5.4 ppbv deg -1, CH 4 ˜ 5.3 ppbv deg -1, CO ˜ 10 ppbv deg -1, ethane ˜ 93.2 pptv deg -1 and n-butane ˜ 59.7 pptv deg -1) over this region. Surprisingly, and in contrast to over the Bay of Bengal, the mixing ratios of these trace gases over the Arabian Sea are found comparatively higher over the southern region than over the northern region leading to negative latitudinal gradients. The short lived species with oceanic sources like ethene and propene show large variability and higher mixing ratios over southern parts of both the marine regions. These observations are compared with previous measurements made over these marine regions and the results obtained from the 3D MOZART chemistry transport model. The present study shows that the two marine regions adjacent to the Indian subcontinent are completely different from the perspective of surface level distributions of these species.

  14. Variability in aerosol optical and physical characteristics over the Bay of Bengal and the Arabian Sea deduced from Ångström exponents

    NASA Astrophysics Data System (ADS)

    Kedia, Sumita; Ramachandran, S.

    2009-07-01

    Spectral distribution of aerosol optical depths (AODs) measured in the 0.4-0.875 μm wavelength region using a Sun photometer over Bay of Bengal and Arabian Sea during the 2006 premonsoon season are analyzed to obtain more interesting information on the physical and optical characteristics of aerosols. Examination of spectral AODs measured over the Bay of Bengal and the Arabian Sea by deriving the Ångström exponent (α) for the entire spectral range (0.4-0.875 μm), α for different spectral ranges, and second derivative (α') showed that the aerosol size distribution is of mixed type or bimodal with contributions from fine and coarse modes. The α-AOD relationships in short (0.4-0.5 μm), long (0.65-0.9 μm), and full (0.4-0.9 μm) spectral ranges determined for various aerosol models (urban, maritime clean, maritime polluted, and desert) suggest that the α-AOD relationship can vary depending on whether the size distribution is unimodal, mixed type, or bimodal, similar to the results obtained for measured AOD spectra. Significant curvature in the ln AOD versus ln λ is observed which causes spectral variation in α derived in different spectral ranges. Over the Bay of Bengal for 76% of AOD spectra, α2 - α1 is >1, suggesting the presence of fine-mode aerosols from a wide variety of fine-mode fractions or a mixture of modes, while over the Arabian Sea, α2 - α1 is <1 for 84% of AOD spectra, clearly indicating the dominance of coarse-mode aerosols. These characteristics can be used in modeling the regional and seasonal aerosol radiative effects and in remote sensing.

  15. Large scale patterns of antimicrofouling defenses in the hard coral Pocillopora verrucosa in an environmental gradient along the Saudi Arabian coast of the Red Sea.

    PubMed

    Wahl, Martin; Al Sofyani, Abdulmohsin; Saha, Mahasweta; Kruse, Inken; Lenz, Mark; Sawall, Yvonne

    2014-01-01

    Large scale patterns of ecologically relevant traits may help identify drivers of their variability and conditions beneficial or adverse to the expression of these traits. Antimicrofouling defenses in scleractinian corals regulate the establishment of the associated biofilm as well as the risks of infection. The Saudi Arabian Red Sea coast features a pronounced thermal and nutritional gradient including regions and seasons with potentially stressful conditions to corals. Assessing the patterns of antimicrofouling defenses across the Red Sea may hint at the susceptibility of corals to global change. We investigated microfouling pressure as well as the relative strength of 2 alternative antimicrofouling defenses (chemical antisettlement activity, mucus release) along the pronounced environmental gradient along the Saudi Arabian Red Sea coast in 2 successive years. Microfouling pressure was exceptionally low along most of the coast but sharply increased at the southernmost sites. Mucus release correlated with temperature. Chemical defense tended to anti-correlate with mucus release. As a result, the combined action of mucus release and chemical antimicrofouling defense seemed to warrant sufficient defense against microbes along the entire coast. In the future, however, we expect enhanced energetic strain on corals when warming and/or eutrophication lead to higher bacterial fouling pressure and a shift towards putatively more costly defense by mucus release.

  16. Large scale patterns of antimicrofouling defenses in the hard coral Pocillopora verrucosa in an environmental gradient along the Saudi Arabian coast of the Red Sea.

    PubMed

    Wahl, Martin; Al Sofyani, Abdulmohsin; Saha, Mahasweta; Kruse, Inken; Lenz, Mark; Sawall, Yvonne

    2014-01-01

    Large scale patterns of ecologically relevant traits may help identify drivers of their variability and conditions beneficial or adverse to the expression of these traits. Antimicrofouling defenses in scleractinian corals regulate the establishment of the associated biofilm as well as the risks of infection. The Saudi Arabian Red Sea coast features a pronounced thermal and nutritional gradient including regions and seasons with potentially stressful conditions to corals. Assessing the patterns of antimicrofouling defenses across the Red Sea may hint at the susceptibility of corals to global change. We investigated microfouling pressure as well as the relative strength of 2 alternative antimicrofouling defenses (chemical antisettlement activity, mucus release) along the pronounced environmental gradient along the Saudi Arabian Red Sea coast in 2 successive years. Microfouling pressure was exceptionally low along most of the coast but sharply increased at the southernmost sites. Mucus release correlated with temperature. Chemical defense tended to anti-correlate with mucus release. As a result, the combined action of mucus release and chemical antimicrofouling defense seemed to warrant sufficient defense against microbes along the entire coast. In the future, however, we expect enhanced energetic strain on corals when warming and/or eutrophication lead to higher bacterial fouling pressure and a shift towards putatively more costly defense by mucus release. PMID:25485603

  17. Large Scale Patterns of Antimicrofouling Defenses in the Hard Coral Pocillopora verrucosa in an Environmental Gradient along the Saudi Arabian Coast of the Red Sea

    PubMed Central

    Wahl, Martin; Al Sofyani, Abdulmohsin; Saha, Mahasweta; Kruse, Inken; Lenz, Mark; Sawall, Yvonne

    2014-01-01

    Large scale patterns of ecologically relevant traits may help identify drivers of their variability and conditions beneficial or adverse to the expression of these traits. Antimicrofouling defenses in scleractinian corals regulate the establishment of the associated biofilm as well as the risks of infection. The Saudi Arabian Red Sea coast features a pronounced thermal and nutritional gradient including regions and seasons with potentially stressful conditions to corals. Assessing the patterns of antimicrofouling defenses across the Red Sea may hint at the susceptibility of corals to global change. We investigated microfouling pressure as well as the relative strength of 2 alternative antimicrofouling defenses (chemical antisettlement activity, mucus release) along the pronounced environmental gradient along the Saudi Arabian Red Sea coast in 2 successive years. Microfouling pressure was exceptionally low along most of the coast but sharply increased at the southernmost sites. Mucus release correlated with temperature. Chemical defense tended to anti-correlate with mucus release. As a result, the combined action of mucus release and chemical antimicrofouling defense seemed to warrant sufficient defense against microbes along the entire coast. In the future, however, we expect enhanced energetic strain on corals when warming and/or eutrophication lead to higher bacterial fouling pressure and a shift towards putatively more costly defense by mucus release. PMID:25485603

  18. Culturable bacterial flora associated with the dinoflagellate green Noctiluca miliaris during active and declining bloom phases in the Northern Arabian Sea.

    PubMed

    Basu, Subhajit; Deobagkar, Deepti D; Matondkar, S G Prabhu; Furtado, Irene

    2013-05-01

    A massive algal bloom of the dinoflagellate Noctiluca miliaris (green) was located in the Northern Arabian Sea by IRS-P4-2 (OCM-II) for microbiological studies, during two consecutive cruises of February-March 2009. Culturable bacterial load during bloom were ≈ 2-3-fold higher in comparison to non-bloom waters and ranged from 3.20 × 10(5) to 6.84 × 10(5) cfu ml(-1). An analysis of the dominant heterotrophs associated with Noctiluca bloom resulted in phylogenetic and a detailed metabolic characterization of 70 bacterial isolates from an overlapping active and declining bloom phase location near north-central Arabian Sea. The active phase flora was dominated by Gram-positive forms (70.59 %), a majority of which belonged to Bacillus (35.29 %) of Firmicutes. As the bloom declined, Gram-negative forms (61.11 %) emerged dominant, and these belonged to a diverse γ-proteobacterial population consisting of Shewanella (16.67 %) and equal fractions of a Cobetia-Pseudomonas-Psychrobacter-Halomonas population (36.11 %). A Unifrac-based principal coordinate analysis of partial 16S rDNA sequences showed significant differences among the active and declining phase flora and also with reported endocytic flora of Noctiluca (red). A nonparametric multidimensional scaling (NMDS) of antibiogram helped differentiation among closely related strains. The organic matter synthesized by N. miliaris appears to be quickly utilized and remineralized as seen from the high efficiency of isolates to metabolize various complex and simple C/N substrates such as carbohydrates, proteins/amino acids, lipids, sulfide production from organic matter, and solubilize phosphates. The ability of a large fraction of these strains (50-41.67 %) to further aerobically denitrify indicates their potential for nitrogen removal from these high-organic microniches of the Noctiluca bloom in the Arabian Sea, also known for high denitrification activity. The results indicate that culturable euphotic bacterial

  19. Culturable bacterial flora associated with the dinoflagellate green Noctiluca miliaris during active and declining bloom phases in the Northern Arabian Sea.

    PubMed

    Basu, Subhajit; Deobagkar, Deepti D; Matondkar, S G Prabhu; Furtado, Irene

    2013-05-01

    A massive algal bloom of the dinoflagellate Noctiluca miliaris (green) was located in the Northern Arabian Sea by IRS-P4-2 (OCM-II) for microbiological studies, during two consecutive cruises of February-March 2009. Culturable bacterial load during bloom were ≈ 2-3-fold higher in comparison to non-bloom waters and ranged from 3.20 × 10(5) to 6.84 × 10(5) cfu ml(-1). An analysis of the dominant heterotrophs associated with Noctiluca bloom resulted in phylogenetic and a detailed metabolic characterization of 70 bacterial isolates from an overlapping active and declining bloom phase location near north-central Arabian Sea. The active phase flora was dominated by Gram-positive forms (70.59 %), a majority of which belonged to Bacillus (35.29 %) of Firmicutes. As the bloom declined, Gram-negative forms (61.11 %) emerged dominant, and these belonged to a diverse γ-proteobacterial population consisting of Shewanella (16.67 %) and equal fractions of a Cobetia-Pseudomonas-Psychrobacter-Halomonas population (36.11 %). A Unifrac-based principal coordinate analysis of partial 16S rDNA sequences showed significant differences among the active and declining phase flora and also with reported endocytic flora of Noctiluca (red). A nonparametric multidimensional scaling (NMDS) of antibiogram helped differentiation among closely related strains. The organic matter synthesized by N. miliaris appears to be quickly utilized and remineralized as seen from the high efficiency of isolates to metabolize various complex and simple C/N substrates such as carbohydrates, proteins/amino acids, lipids, sulfide production from organic matter, and solubilize phosphates. The ability of a large fraction of these strains (50-41.67 %) to further aerobically denitrify indicates their potential for nitrogen removal from these high-organic microniches of the Noctiluca bloom in the Arabian Sea, also known for high denitrification activity. The results indicate that culturable euphotic bacterial

  20. A new species of the rare nematode genus Paramicrolaimus Wieser, 1954 (Chromadorida: Paramicrolaimidae) from the south eastern Arabian Sea.

    PubMed

    Jacob, Jini; Jaleel K U, Abdul; Vijayan, Anil Kumar

    2015-01-08

    A new paramicrolaimid nematode, Paramicrolaimus damodarani sp. nov., is described based on specimens from the continental shelf (95 m) of the south eastern Arabian Sea. Paramicrolaimus damodarani sp. nov. differs from other known species of the genus in having a smaller body size, form of the spicular apparatus, presence of 7 cuticularised protruding precloacal supplements and a strongly cuticularised terminal spinneret. This is the first record of the genus Paramicrolaimus from the northern Indian Ocean. A pictorial key to the four species of Paramicrolaimus is also provided, supplemented with comparative characters, based on published information.

  1. A new species of the rare nematode genus Paramicrolaimus Wieser, 1954 (Chromadorida: Paramicrolaimidae) from the south eastern Arabian Sea.

    PubMed

    Jacob, Jini; Jaleel, Abdul K U; Vijayan, Anil Kumar

    2015-01-01

    A new paramicrolaimid nematode, Paramicrolaimus damodarani sp. nov., is described based on specimens from the continental shelf (95 m) of the south eastern Arabian Sea. Paramicrolaimus damodarani sp. nov. differs from other known species of the genus in having a smaller body size, form of the spicular apparatus, presence of 7 cuticularised protruding precloacal supplements and a strongly cuticularised terminal spinneret. This is the first record of the genus Paramicrolaimus from the northern Indian Ocean. A pictorial key to the four species of Paramicrolaimus is also provided, supplemented with comparative characters, based on published information. PMID:25660800

  2. Chlorinated pesticide residues in sediments from the Arabian Sea along the central west coast of India

    SciTech Connect

    Sarkar, A.; Gupta, R.S.

    1987-12-01

    The problem of environmental contamination by persistent chlorinated pesticides still evokes major concern due to the presence of their residues in the environment and in human tissues. In developing countries like India organochlorine insecticides, especially DDT are extensively being used in agriculture and vector control programs. Few data are available on their levels of concentration from the seas around India. Persistent pesticides residues can be expected to accumulate in marine sediments. However, very little data on this are available along the Indian coast. An attempt has been made in the present communication to identify and quantify some of the chlorinated pesticides residues in the marine sediments collected from different region along the central west coast of India. This is a part of our ongoing project to monitor and map pollutants within the exclusive economic zone of India.

  3. Tectonic map of the Arabian Peninsula

    USGS Publications Warehouse

    Brown, Glen F.

    1972-01-01

    This tectonic map of the Arabian peninsula, prepared for the Audi Arabian Ministry of Petroleum and Mineral Resource, is the first of a series of peninsular maps that attempt to show regional features. Much recent information resulting from detailed geologic mapping notably within the Arabian craton, from geophysical surveys, both airborne and oceanographic in adjacent seas, from deep exploratory drilling, and from photography from the Gemini and Apollo space programs, has been used in the tectonic evaluation.

  4. Gamma-emitting radionuclides in the shallow marine sediments off the Sindh coast, Arabian Sea.

    PubMed

    Akram, M; Qureshi, Riffat M; Ahmad, Nasir; Solaija, Tariq Jamal

    2006-01-01

    Determination of gamma emitting radionuclides in shallow marine sediments off the Sindh coast has been carried out using a gamma spectrometry technique. The activity concentration measured in various sediment samples off the Sindh coast has been found to vary from 15.93 +/- 5.22 to 30.53 +/- 4.70 Bq kg(-1) for 226Ra, from 11.72 +/- 1.22 to 33.94 +/- 1.86 Bq kg(-1) for 228Ra and from 295.22 +/- 32.83 to 748.47 +/- 28.75 Bq kg(-1) for 40K. The calculated mean values of radium equivalent activity, absorbed dose rate and effective dose are 98 Bq kg(-1), 49 nGy h(-1) and 0.06 mSv y(-1), respectively. No artificial radionuclide was detected in the samples measured from the study area. As no data on radioactivity of the coastal environment of Pakistan are available, the data presented here will serve as baseline information on radionuclide concentration in shallow sea sediments off the Sindh coast. The data will also be useful for tracking pollution inventories from unusual radiological events (if any) in the territorial waters of the study area. Further, the information presented will contribute to modelling of a regional radioactivity database from the perspectives of the International Atomic Energy Agency's Asia-Pacific Marine Radioactivity Database and Global Marine Radioactivity Database.

  5. Shotgun metagenomic data reveals significant abundance but low diversity of "Candidatus Scalindua" marine anammox bacteria in the Arabian Sea oxygen minimum zone.

    PubMed

    Villanueva, Laura; Speth, Daan R; van Alen, Theo; Hoischen, Alexander; Jetten, Mike S M

    2014-01-01

    Anaerobic ammonium oxidizing (anammox) bacteria are responsible for a significant portion of the loss of fixed nitrogen from the oceans, making them important players in the global nitrogen cycle. To date, marine anammox bacteria found in both water columns and sediments worldwide belong almost exclusively to "Candidatus Scalindua" species. Recently the genome assembly of a marine anammox enrichment culture dominated by "Candidatus Scalindua profunda" became available and can now be used as a template to study metagenome data obtained from various oxygen minimum zones (OMZs). Here, we sequenced genomic DNA from suspended particulate matter recovered at the upper (170 m deep) and center (600 m) area of the OMZ in the Arabian Sea by SOLiD and Ion Torrent technology. The genome of "Candidatus Scalindua profunda" served as a template to collect reads. Based on the mapped reads marine anammox Abundance was estimated to be at least 0.4% in the upper and 1.7% in the center area. Single nucleotide variation (SNV) analysis was performed to assess diversity of the "Candidatus Scalindua" populations. Most highly covered were the two diagnostic anammox genes hydrazine synthase (scal_01318c, hzsA) and hydrazine dehydrogenase (scal_03295, hdh), while other genes involved in anammox metabolism (narGH, nirS, amtB, focA, and ACS) had a lower coverage but could still be assembled and analyzed. The results show that "Candidatus Scalindua" is abundantly present in the Arabian Sea OMZ, but that the diversity within the ecosystem is relatively low.

  6. Inhibition of mixed-layer deepening during winter in the northeastern Arabian Sea by the West India Coastal Current

    NASA Astrophysics Data System (ADS)

    Shankar, D.; Remya, R.; Vinayachandran, P. N.; Chatterjee, Abhisek; Behera, Ambica

    2016-08-01

    Though the deep mixed layers (MLs) that form in the northeastern Arabian Sea (NEAS) during the winter monsoon (November-February) have been attributed to convective mixing driven by dry, cool northeasterly winds from the Indian subcontinent, data show that the deepest MLs occur in the northern NEAS and the maxima of latent-heat and net heat fluxes in the southern NEAS. We use an oceanic general circulation model to show that the deep MLs in the NEAS extend up to ~20°N till the end of December, but are restricted poleward of ~22°N (~23°N) in January (February). This progressive restriction of the deep mixed layers within the NEAS is due to poleward advection of water of lower salinity by the West India Coastal Current (WICC). The deep MLs are sustained till February in the northern NEAS because convective mixing deepens the ML before the waters of lower salinity reach this region and the wind stirring and convective overturning generate sufficient turbulent energy for the ML to maintain the depth attained in January. Though the atmospheric fluxes tend to cool the ML in the southern NEAS, this cooling is countered by the warming due to horizontal advection. Likewise, the cooling due to entrainment, which continues in the southern NEAS even as the ML shallows during January-February, is almost cancelled by the warming caused by a downwelling vertical velocity field. Therefore, the SST changes very little during December-February even as the ML shallows dramatically in the southern NEAS. These deep MLs of the NEAS also preclude a strong intraseasonal response to the intraseasonal variability in the fluxes. This role of horizontal advection implies that the ML depth in the NEAS is determined by an interplay of physical processes that are forced differently. The convective mixing depends on processes that are local to the region, but the advection is due to the WICC, whose seasonal cycle is primarily forced by remote winds. By inhibiting the formation of deep MLs in

  7. Evolution and sub-surface characteristics of a sea-surface temperature filament and front in the northeastern Arabian Sea during November-December 2012

    NASA Astrophysics Data System (ADS)

    Vipin, P.; Sarkar, Kankan; Aparna, S. G.; Shankar, D.; Sarma, V. V. S. S.; Gracias, D. G.; Krishna, M. S.; Srikanth, G.; Mandal, R.; Rama Rao, E. P.; Srinivasa Rao, N.

    2015-10-01

    We used satellite-derived sea-surface-temperature (SST) data along with in-situ data collected along a meridional transect between 18.85 and 20.25°N along 69.2°E to describe the evolution of an SST filament and front during 25 November to 1 December in the northeastern Arabian Sea (NEAS). Both features were ~ 100 km long, lasted about a week, and were associated with weak temperature gradients (~ 0.07 °C km- 1). The in-situ data were collected first using a suite of surface sensors during a north-south mapping of this transect and showed the existence of a chlorophyll maximum within the filament. This surface data acquisition was followed by a high-resolution south-north CTD (conductivity-temperature-depth) sampling along the transect. In the two days that elapsed between the two in-situ measurements, the filament had shrunk in size and moved northward. In general, the current direction was northwestward and advected these mesoscale features. The CTD data also showed an SST front towards the northern end of the transect. In both these features, the chlorophyll concentration was higher than in the surrounding waters. The temperature and salinity data from the CTD suggest upward mixing or pumping of water from the base of the mixed layer, where a chlorophyll maximum was present, into the mixed layer that was about 60 m thick. A striking diurnal cycle was evident in the chlorophyll concentration, with higher values tending to occur closer to the surface during the night. The in-situ data from both surface sensors and CTD, and so also satellite-derived chlorophyll data, showed higher chlorophyll concentration, particularly at sub-surface levels, between the filament and the front, but there was no corresponding signature in the temperature and salinity data. Analysis of the SST fronts in the satellite data shows that fronts weaker than those associated with the filament and the front had crossed the transect in this region a day or two preceding the sampling of the

  8. Symbiodinium thermophilum sp. nov., a thermotolerant symbiotic alga prevalent in corals of the world's hottest sea, the Persian/Arabian Gulf.

    PubMed

    Hume, B C C; D'Angelo, C; Smith, E G; Stevens, J R; Burt, J; Wiedenmann, J

    2015-02-27

    Coral reefs are in rapid decline on a global scale due to human activities and a changing climate. Shallow water reefs depend on the obligatory symbiosis between the habitat forming coral host and its algal symbiont from the genus Symbiodinium (zooxanthellae). This association is highly sensitive to thermal perturbations and temperatures as little as 1°C above the average summer maxima can cause the breakdown of this symbiosis, termed coral bleaching. Predicting the capacity of corals to survive the expected increase in seawater temperatures depends strongly on our understanding of the thermal tolerance of the symbiotic algae. Here we use molecular phylogenetic analysis of four genetic markers to describe Symbiodinium thermophilum, sp. nov. from the Persian/Arabian Gulf, a thermally tolerant coral symbiont. Phylogenetic inference using the non-coding region of the chloroplast psbA gene resolves S. thermophilum as a monophyletic lineage with large genetic distances from any other ITS2 C3 type found outside the Gulf. Through the characterisation of Symbiodinium associations of 6 species (5 genera) of Gulf corals, we demonstrate that S. thermophilum is the prevalent symbiont all year round in the world's hottest sea, the southern Persian/Arabian Gulf.

  9. Symbiodinium thermophilum sp. nov., a thermotolerant symbiotic alga prevalent in corals of the world's hottest sea, the Persian/Arabian Gulf.

    PubMed

    Hume, B C C; D'Angelo, C; Smith, E G; Stevens, J R; Burt, J; Wiedenmann, J

    2015-01-01

    Coral reefs are in rapid decline on a global scale due to human activities and a changing climate. Shallow water reefs depend on the obligatory symbiosis between the habitat forming coral host and its algal symbiont from the genus Symbiodinium (zooxanthellae). This association is highly sensitive to thermal perturbations and temperatures as little as 1°C above the average summer maxima can cause the breakdown of this symbiosis, termed coral bleaching. Predicting the capacity of corals to survive the expected increase in seawater temperatures depends strongly on our understanding of the thermal tolerance of the symbiotic algae. Here we use molecular phylogenetic analysis of four genetic markers to describe Symbiodinium thermophilum, sp. nov. from the Persian/Arabian Gulf, a thermally tolerant coral symbiont. Phylogenetic inference using the non-coding region of the chloroplast psbA gene resolves S. thermophilum as a monophyletic lineage with large genetic distances from any other ITS2 C3 type found outside the Gulf. Through the characterisation of Symbiodinium associations of 6 species (5 genera) of Gulf corals, we demonstrate that S. thermophilum is the prevalent symbiont all year round in the world's hottest sea, the southern Persian/Arabian Gulf. PMID:25720577

  10. Numerical Study of OrograPhic-Convective Precipitation over the Eastern Arabian Sea and the Ghat Mountains during the Summer Monsoon.

    NASA Astrophysics Data System (ADS)

    Ogura, Yoshi; Yoshizaki, Masanori

    1988-08-01

    When the western coast of India lies in the path of the low-level west-southwest wind crossing the Arabian Sea during the summer monsoon season, deep convection frequently develops over the ocean off the coast. In such a situation, the maximum rainfall occurs near the coast, not over the Western Ghats. In order to study the physics underlying orographic-convective precipitation over this area, a two-dimensional compressible moist cloud model is applied. The model is written in terrain-following coordinates and includes the Coriolis force and a planetary boundary layer parameterization. The initial fields of thermodynamic variables are specified using observed data gathered upstream of the offshore precipitating systems over the Arabian Sea. Two wind profiles are considered: vertically uniform and nonuniform flows. The latter profile represents a monsoonal westerly jet at low levels and easterlies in the layer above 5 km. Three cases are considered for each wind profile by including or omitting moisture in the atmosphere and heat and moisture fluxes from the ocean.Among six cases considered, results from the moist and nonuniform wind profile case with heat and moisture fluxes from the ocean are found to be the most consistent with observations of precipitation rate, preferred location of rainfall, and lack of high-level clouds in the downwind side of the mountain. When fluxes from the ocean are excluded, the predicted rainfall accumulation is about the same. However, the maximum rainfall rate occurs over the mountain peak area, in disagreement with the observation. When fluxes from the ocean are included, but with the vertically uniform basic flow, the predicted maximum rainfall occurs at the coast. However, its rate is about half that observed. It is thus concluded that, in order to account for the observed features of rainfall over the Arabian Sea and the Ghat Mountains during the summer monsoon season, two factors, the strongly sheared environment and fluxes of

  11. Three-dimensional imaging of the S-velocity structure for the crust and the upper mantle beneath the Arabian Sea from Rayleigh wave analysis

    NASA Astrophysics Data System (ADS)

    Corchete, V.

    2016-07-01

    A 3D imaging of S-velocity for the Arabian Sea crust and upper mantle structure is presented in this paper, determined by means of Rayleigh wave analysis, for depths ranging from zero to 300 km. The crust and upper mantle structure of this region of the earth never has been the subject of a surface wave tomography survey. The Moho map performed in the present study is a new result, in which a crustal thickening beneath the Arabian Fan sediments can be observed. This crustal thickening can be interpreted as a quasi-continental oceanic transitional structure. A crustal thickness of up to 20 km also can be observed for the Murray Ridge system in this Moho map. This crustal thickening can be due to that the Murray Ridge System consists of Indian continental crust. This continental crust is extremely thinned to the southwest of this region, as shown in this Moho map. This area can be interpreted as oceanic in origin. In the depth range from 30 to 60 km, the S-velocity presents its lower values at the Carlsberg Ridge region, because it is the younger region of the study area. In the depth range from 60 to 105 km of depth, the S-velocity pattern is very similar to that shown for the previous depth range, except for the regions in which the asthenosphere is reached, for these regions appear a low S-velocity pattern. The lithosphere-asthenosphere boundary (LAB), or equivalently the lithosphere thickness, determined in the present study is also a new result, in which the lithosphere thickness for the Arabian Fan can be estimated in 60-70 km. The lower lithospheric thickness observed in the LAB map, for the Arabian Fan, shows that this region may be in the transition zone between continental and oceanic structure. Finally, a low-velocity zone (LVZ) has been determined, for the whole study area, located between the LAB and the boundary of the asthenosphere base (or equivalently the lithosphere-asthenosphere system thickness). The asthenosphere-base map calculated in the

  12. Dissolved Fe(II) in the Arabian Sea oxygen minimum zone and western tropical Indian Ocean during the inter-monsoon period

    NASA Astrophysics Data System (ADS)

    Kondo, Yoshiko; Moffett, James W.

    2013-03-01

    The concentration of iron(II) (Fe(II)) in seawater was investigated throughout the water column in the Arabian Sea and western tropical Indian Ocean including the oxygen minimum zone (OMZ) as part of the 2009 Japanese GEOTRACES cruise using a luminol-chemiluminescence detection based flow injection analysis technique. A novel modification was the adjustment of the sample pH to 7.2 with a 3-(N-morpholino) propanesulfonic acid (MOPS) buffer to minimize Fe(II) oxidation during sampling. At stations in the Arabian Sea OMZ, Fe(II) had subsurface maxima in the oxygen-deficient and high nitrite layers; fully 7-29% of total dissolved Fe existed as Fe(II) in these samples. Subsurface Fe(II) maxima were not observed in stations south of the oxygen minimum zone. Within the OMZ, the distribution of Fe(II) resembled previous data obtained during the 2004 southwest monsoon, indicating that the Fe(II) maxima are seasonally and interannually persistent feature. These results confirm the close relationship between Fe(II) and the secondary nitrite maxima and suggest that the rich microbial community within this feature is closely involved with Fe redox cycling. Fe(II) concentrations near the seafloor were elevated in locations underlying the OMZ but nowhere else, possibly reflecting inputs from reducing sediments. To the south, a clear maximum in dissolved Fe from the Rodriguez Triple Junction hydrothermal system showed no evidence of Fe(II). The center location of the Rodriguez Triple Junction is 25° 35'S, 70° 00'E (Gamo et al., 2001), more than 800 km southwest of station ER10 (the closest station), so hydrothermally-derived Fe(II) was probably oxidized.

  13. Denitrifying alphaproteobacteria from the Arabian Sea that express nosZ, the gene encoding nitrous oxide reductase, in oxic and suboxic waters.

    PubMed

    Wyman, Michael; Hodgson, Sylvia; Bird, Clare

    2013-04-01

    Marine ecosystems are significant sources of the powerful greenhouse gas nitrous oxide (N2O). A by-product of nitrification and an intermediate in the denitrification pathway, N2O is formed primarily in oxygen-deficient waters and sediments. We describe the isolation of a group of alphaproteobacteria from the suboxic waters of the Arabian Sea that are phylogenetically affiliated with Labrenzia spp. and other denitrifiers. Quantitative PCR assays revealed that these organisms were very broadly distributed in this semienclosed ocean basin. Their biogeographical range extended from the productive, upwelling region off the Omani shelf to the clear, oligotrophic waters that are found much further south and also included the mesotrophic waters overlying the oxygen minimum zone (OMZ) in the northeastern sector of the Arabian Sea. These organisms actively expressed NosZ (N2O reductase, the terminal step in the denitrification pathway) within the OMZ, an established region of pelagic denitrification. They were found in greatest numbers outside the OMZ, however, and nosZ mRNAs were also readily detected near the base of the upper mixed layer in nutrient-poor, oxic regions. Our findings provide firm molecular evidence of a potential sink for N2O within well-ventilated, oceanic surface waters in this biogeochemically important region. We show that the Labrenzia-like denitrifiers and their close relatives are habitual colonizers of the pseudobenthic environment provided by Trichodesmium spp. We develop the conjecture that the O2-depleted microzones that occur within the colonies of these filamentous, diazotrophic cyanobacteria might provide unexpected niches for the reduction of nitrogen oxides in tropical and subtropical surface waters.

  14. Denitrifying Alphaproteobacteria from the Arabian Sea That Express nosZ, the Gene Encoding Nitrous Oxide Reductase, in Oxic and Suboxic Waters

    PubMed Central

    Hodgson, Sylvia; Bird, Clare

    2013-01-01

    Marine ecosystems are significant sources of the powerful greenhouse gas nitrous oxide (N2O). A by-product of nitrification and an intermediate in the denitrification pathway, N2O is formed primarily in oxygen-deficient waters and sediments. We describe the isolation of a group of alphaproteobacteria from the suboxic waters of the Arabian Sea that are phylogenetically affiliated with Labrenzia spp. and other denitrifiers. Quantitative PCR assays revealed that these organisms were very broadly distributed in this semienclosed ocean basin. Their biogeographical range extended from the productive, upwelling region off the Omani shelf to the clear, oligotrophic waters that are found much further south and also included the mesotrophic waters overlying the oxygen minimum zone (OMZ) in the northeastern sector of the Arabian Sea. These organisms actively expressed NosZ (N2O reductase, the terminal step in the denitrification pathway) within the OMZ, an established region of pelagic denitrification. They were found in greatest numbers outside the OMZ, however, and nosZ mRNAs were also readily detected near the base of the upper mixed layer in nutrient-poor, oxic regions. Our findings provide firm molecular evidence of a potential sink for N2O within well-ventilated, oceanic surface waters in this biogeochemically important region. We show that the Labrenzia-like denitrifiers and their close relatives are habitual colonizers of the pseudobenthic environment provided by Trichodesmium spp. We develop the conjecture that the O2-depleted microzones that occur within the colonies of these filamentous, diazotrophic cyanobacteria might provide unexpected niches for the reduction of nitrogen oxides in tropical and subtropical surface waters. PMID:23396348

  15. Phylogenetic analyses and nitrate-reducing activity of fungal cultures isolated from the permanent, oceanic oxygen minimum zone of the Arabian Sea.

    PubMed

    Manohar, Cathrine Sumathi; Menezes, Larissa Danielle; Ramasamy, Kesava Priyan; Meena, Ram M

    2015-03-01

    Reports on the active role of fungi as denitrifiers in terrestrial ecosystems have stimulated an interest in the study of the role of fungi in oxygen-deficient marine systems. In this study, the culturable diversity of fungi was investigated from 4 stations within the permanent, oceanic, oxygen minimum zone of the Arabian Sea. The isolated cultures grouped within the 2 major fungal phyla Ascomycota and Basidiomycota; diversity estimates in the stations sampled indicated that the diversity of the oxygen-depleted environments is less than that of mangrove regions and deep-sea habitats. Phylogenetic analyses of 18S rRNA sequences revealed a few divergent isolates that clustered with environmental sequences previously obtained by others. This is significant, as these isolates represent phylotypes that so far were known only from metagenomic studies and are of phylogenetic importance. Nitrate reduction activity, the first step in the denitrification process, was recorded for isolates under simulated anoxic, deep-sea conditions showing ecological significance of fungi in the oxygen-depleted habitats. This report increases our understanding of fungal diversity in unique, poorly studied habitats and underlines the importance of fungi in the oxygen-depleted environments.

  16. Rainouts over the Arabian Sea and Western Ghats during moisture advection and recycling explain the isotopic composition of Bangalore summer rains

    NASA Astrophysics Data System (ADS)

    Rahul, P.; Ghosh, Prosenjit; Bhattacharya, S. K.

    2016-06-01

    Variations in the isotope ratios (18O/16O and D/H) of meteoric water at continental stations serve as valuable tracers for the hydrological cycle. In the present study, we investigated the role of sea surface temperature, wind speed, relative humidity, and rainout processes on the stable isotopic composition of the 2010 monsoon rainwater of Bangalore. The wind over the ocean influences the sea surface temperature and humidity which in turn influence the vapor isotopic composition. The rainout over the Arabian Sea and the land mass (Western Ghats) during advection of the air parcel to Bangalore and its recycling further modify the vapor composition. The isotopic ratios (δ18O, δD, and d-excess) of the precipitation at Bangalore was estimated following a Rayleigh fractionation model involving rainout and recycling processes yield values consistent with our observation. In some samples, however, the observed isotopic ratios are higher (by 2 to 5‰), and a few of them are associated with high d-excess values. These discrepancies could be due to limitation of the model assumptions.

  17. Phylogenetic analyses and nitrate-reducing activity of fungal cultures isolated from the permanent, oceanic oxygen minimum zone of the Arabian Sea.

    PubMed

    Manohar, Cathrine Sumathi; Menezes, Larissa Danielle; Ramasamy, Kesava Priyan; Meena, Ram M

    2015-03-01

    Reports on the active role of fungi as denitrifiers in terrestrial ecosystems have stimulated an interest in the study of the role of fungi in oxygen-deficient marine systems. In this study, the culturable diversity of fungi was investigated from 4 stations within the permanent, oceanic, oxygen minimum zone of the Arabian Sea. The isolated cultures grouped within the 2 major fungal phyla Ascomycota and Basidiomycota; diversity estimates in the stations sampled indicated that the diversity of the oxygen-depleted environments is less than that of mangrove regions and deep-sea habitats. Phylogenetic analyses of 18S rRNA sequences revealed a few divergent isolates that clustered with environmental sequences previously obtained by others. This is significant, as these isolates represent phylotypes that so far were known only from metagenomic studies and are of phylogenetic importance. Nitrate reduction activity, the first step in the denitrification process, was recorded for isolates under simulated anoxic, deep-sea conditions showing ecological significance of fungi in the oxygen-depleted habitats. This report increases our understanding of fungal diversity in unique, poorly studied habitats and underlines the importance of fungi in the oxygen-depleted environments. PMID:25688692

  18. Population history of the Red Sea--genetic exchanges between the Arabian Peninsula and East Africa signaled in the mitochondrial DNA HV1 haplogroup.

    PubMed

    Musilová, Eliška; Fernandes, Verónica; Silva, Nuno M; Soares, Pedro; Alshamali, Farida; Harich, Nourdin; Cherni, Lotfi; Gaaied, Amel Ben Ammar El; Al-Meeri, Ali; Pereira, Luísa; Cerný, Viktor

    2011-08-01

    Archaeological studies have revealed cultural connections between the two sides of the Red Sea dating to prehistory. The issue has still not been properly addressed, however, by archaeogenetics. We focus our attention here on the mitochondrial haplogroup HV1 that is present in both the Arabian Peninsula and East Africa. The internal variation of 38 complete mitochondrial DNA sequences (20 of them presented here for the first time) affiliated into this haplogroup testify to its emergence during the late glacial maximum, most probably in the Near East, with subsequent dispersion via population expansions when climatic conditions improved. Detailed phylogeography of HV1 sequences shows that more recent demographic upheavals likely contributed to their spread from West Arabia to East Africa, a finding concordant with archaeological records suggesting intensive maritime trade in the Red Sea from the sixth millennium BC onwards. Closer genetic exchanges are apparent between the Horn of Africa and Yemen, while Egyptian HV1 haplotypes seem to be more similar to the Near Eastern ones. PMID:21660931

  19. Population history of the Red Sea--genetic exchanges between the Arabian Peninsula and East Africa signaled in the mitochondrial DNA HV1 haplogroup.

    PubMed

    Musilová, Eliška; Fernandes, Verónica; Silva, Nuno M; Soares, Pedro; Alshamali, Farida; Harich, Nourdin; Cherni, Lotfi; Gaaied, Amel Ben Ammar El; Al-Meeri, Ali; Pereira, Luísa; Cerný, Viktor

    2011-08-01

    Archaeological studies have revealed cultural connections between the two sides of the Red Sea dating to prehistory. The issue has still not been properly addressed, however, by archaeogenetics. We focus our attention here on the mitochondrial haplogroup HV1 that is present in both the Arabian Peninsula and East Africa. The internal variation of 38 complete mitochondrial DNA sequences (20 of them presented here for the first time) affiliated into this haplogroup testify to its emergence during the late glacial maximum, most probably in the Near East, with subsequent dispersion via population expansions when climatic conditions improved. Detailed phylogeography of HV1 sequences shows that more recent demographic upheavals likely contributed to their spread from West Arabia to East Africa, a finding concordant with archaeological records suggesting intensive maritime trade in the Red Sea from the sixth millennium BC onwards. Closer genetic exchanges are apparent between the Horn of Africa and Yemen, while Egyptian HV1 haplotypes seem to be more similar to the Near Eastern ones.

  20. Calappid and leucosiid crabs (Crustacea: Decapoda: Brachyura) from Kerala, India, with the description of a new species of Mursia Desmarest, 1823, from the Arabian Sea and redescription of M. bicristimana Alcock & Anderson, 1894.

    PubMed

    Kumar, Biju A; Kumar, M Sushil; Galil, Bella S

    2013-12-13

    Eleven species of calappid and leucosiid crabs were identified from by-catch landed by trawlers at four fishing ports in Kerala, India that were surveyed in 2007 and supplemented by material obtained in January 2013. Four species are reported for the first time from India, six are new records for Kerala. The status of Mursia bicristimana Alcock & Anderson, 1894, is clarified and the species redescribed. A new species of Mursia is described from the Gulf of Aden, Arabian Sea

  1. The middle Holocene climatic records from Arabia: Reassessing lacustrine environments, shift of ITCZ in Arabian Sea, and impacts of the southwest Indian and African monsoons

    NASA Astrophysics Data System (ADS)

    Enzel, Yehouda; Kushnir, Yochanan; Quade, Jay

    2015-06-01

    A dramatic increase in regional summer rainfall amount has been proposed for the Arabian Peninsula during the middle Holocene (ca. 9-5 ka BP) based on lacustrine sediments, inferred lake levels, speleothems, and pollen. This rainfall increase is considered primarily the result of an intensified Indian summer monsoon as part of the insolation-driven, northward shift of the boreal summer position of the Inter-Tropical Convergence Zone (ITCZ) to over the deserts of North Africa, Arabia, and northwest India. We examine the basis for the proposed drastic climate change in Arabia and the shifts in the summer monsoon rains, by reviewing paleohydrologic lacustrine records from Arabia. We evaluate and reinterpret individual lake-basin status regarding their lacustrine-like deposits, physiography, shorelines, fauna and flora, and conclude that these basins were not occupied by lakes, but by shallow marsh environments. Rainfall increase required to support such restricted wetlands is much smaller than needed to form and maintain highly evaporating lakes and we suggest that rainfall changes occurred primarily at the elevated edges of southwestern, southern, and southeastern Arabian Peninsula. These relatively small changes in rainfall amounts and local are also supported by pollen and speleothems from the region. The changes do not require a northward shift of the Northern Hemisphere summer ITCZ and intensification of the Indian monsoon rainfall. We propose that (a) latitudinal and slight inland expansion of the North African summer monsoon rains across the Red Sea, and (b) uplifted moist air of this monsoon to southwestern Arabia highlands, rather than rains associated with intensification of Indian summer monsoon, as proposed before, increased rains in that region; these African monsoon rains produced the modest paleo-wetlands in downstream hyperarid basins. Furthermore, we postulate that as in present-day, the ITCZ in the Indian Ocean remained at or near the equator all

  2. Planktic foraminiferal assemblages from laminated sediments of the northeastern Arabian Sea: a high-resolution study over the last two millennia

    NASA Astrophysics Data System (ADS)

    Munz, Philipp; Lückge, Andreas; Siccha, Michael; Kucera, Michal; Schulz, Hartmut

    2014-05-01

    Modern planktic foraminiferal assemblages in the Arabian Sea are largely controlled by seasonal shifts of surface water properties. Boreal summer (June-September) heating of the Asian landmass and Tibetan Plateau leads to northward migration of the ITCZ and develops an intense atmospheric pressure gradient. Strong monsoonal winds from the southwest lead to coastal- and open ocean upwelling, especially in the western Arabian Sea along the coast of Somalia and Oman. Opposite directed dry and cold winds lead to deep convective mixing during boreal winter (January-March) and breakup of the thermal stratification. Deepening of the mixed-layer thus enables nutrient transport into the photic zone with enhanced primary production. Here we study planktic foraminiferal assemblages from the dominantly winter monsoon controlled Pakistan Margin off Karachi. We sampled annually laminated sediments from box core SO90-39KG and ca. 2-m-long piston core SO130-275KL from the same station. High sedimentation rates and varve-like lamination provides a particular record with very precise age control. Box core 39KG offers a record of the last 100 years with 2-year-resolution and 275KL provides a ca. 10-year-resolution during the last 2100 years. We calculated foraminiferal flux rates after photometric identification and subtraction of light-colored event layers, consisting solely of terrigeneous matter to enable comparison with flux rates from sediment trap stations. We identified a total of 28 planktic foraminiferal (PF) species/morphotypes in the fraction >150μm. During the relatively short period of the past two millennia, several species showed comparatively large fluctuations on decadal time scales, not seen in bioturbated records. Globigerina bulloides, a species generally associated with high primary production rates, fluctuates between ca. 10% and 45%. Highest relative share was observed during periods 1593-1413, 1023-923, 483-393, 63- -7 years AD. Average PF accumulation rates

  3. Catch composition, reproductive biology and diet of the bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae) from the south-eastern Arabian Sea.

    PubMed

    Akhilesh, K V; Bineesh, K K; White, W T; Shanis, C P R; Hashim, M; Ganga, U; Pillai, N G K

    2013-11-01

    Fishery and biological data are presented for the poorly known bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae), from the deep waters of the south-eastern Arabian Sea. A total of 5318 individuals from by-catch landings of deep-water bottom set longlines, gillnets and shrimp trawl fisheries operating at depths of 200-1200 m were recorded between January 2008 and December 2011 at the Kochi Fisheries Harbour (Kerala). A total of 431 individuals, from 46 to 318 cm total length (L(T)) and 0·8 to 132 kg total mass (M(T)), were examined to determine biological data for this species. The LT at which 50% were mature (L(T)50) for females and males was estimated at 189 and 187 cm LT. Litter size ranged from 10 to 36 and size at birth was between 42 and 46 cm L(T). Dietary analysis of stomach contents revealed E. brucus feeds on a variety of prey including crustaceans (69% index of relative importance, I(RI)), teleosts (25·8% I(RI)), cephalopods (1·7% I(RI)) and elasmobranchs (0·7% I(RI)). This study provides the first detailed biological data for this species and also highlights the extent of the by-catch fishery for this species in Indian waters.

  4. The Jebel Ohier deposit—a newly discovered porphyry copper-gold system in the Neoproterozoic Arabian-Nubian Shield, Red Sea Hills, NE Sudan

    NASA Astrophysics Data System (ADS)

    Bierlein, F. P.; McKeag, S.; Reynolds, N.; Bargmann, C. J.; Bullen, W.; Murphy, F. C.; Al-Athbah, H.; Brauhart, C.; Potma, W.; Meffre, S.; McKnight, S.

    2016-08-01

    Ongoing exploration in the Red Sea Hills of NE Sudan has led to the identification of a large alteration-mineralization system within a relatively undeformed Neoproterozoic intrusive-extrusive succession centered on Jebel Ohier. The style of mineralization, presence of an extensive stockwork vein network within a zoned potassic-propylitic-argillic-advanced argillic-altered system, a mineralization assemblage comprising magnetite-pyrite-chalcopyrite-bornite (±gold, silver and tellurides), and the recurrence of fertile mafic to intermediate magmatism in a developing convergent plate setting all point to a porphyry copper-gold association, analogous to major porphyry Cu-Au-Mo deposits in Phanerozoic supra-subduction settings such as the SW Pacific. Preliminary U-Pb age dating yielded a maximum constraint of c. 730 Ma for the emplacement of the stockwork system into a significantly older ( c. 800 Ma) volcanic edifice. The mineralization formed prior to regional deformation and accretion of the host terrane to a stable continental margin at by c. 700 Ma, thus ensuring preservation of the deposit. The Jebel Ohier deposit is interpreted as a relatively well-preserved, rare example of a Neoproterozoic porphyry Cu-Au system and the first porphyry Cu-Au deposit to be identified in the Arabian-Nubian Shield.

  5. Carbon cycling in primary production bottle incubations: inferences from grazing experiments and photosynthetic studies using 14C and 18O in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Laws, Edward A.; Landry, Michael R.; Barber, Richard T.; Campbell, Lisa; Dickson, Mary-Lynn; Marra, John

    Estimates of photosynthesis based on the incorporation of 14C-labeled inorganic carbon into particulate carbon were compared to estimates of gross photosynthesis based on net O 2 production and the production of 18O2 from H218O during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea process cruises. For samples incubated below the surface and at optical depths<3, the 14C uptake : gross photosynthesis ratio averaged 0.45±0.1. This result is in accord with theoretical considerations of the combined effects of the Mehler reaction, photorespiration, dark respiration, excretion, and grazing effects on the two estimates of photosynthesis. The 14C uptake : gross photosynthesis ratio was distinctly higher (0.62) for samples incubated at the surface. This result is likely due to UV light effects, since the O 2 and 14C incubations were done in quartz and polysulfone bottles, respectively. The 14C uptake : gross photosynthesis ratio was lower (0.31) for bottles incubated at optical depths>3. This result probably reflects an increase in the ratio of dark respiration to net photosynthesis in the vicinity of the compensation light level.

  6. Catch composition, reproductive biology and diet of the bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae) from the south-eastern Arabian Sea.

    PubMed

    Akhilesh, K V; Bineesh, K K; White, W T; Shanis, C P R; Hashim, M; Ganga, U; Pillai, N G K

    2013-11-01

    Fishery and biological data are presented for the poorly known bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae), from the deep waters of the south-eastern Arabian Sea. A total of 5318 individuals from by-catch landings of deep-water bottom set longlines, gillnets and shrimp trawl fisheries operating at depths of 200-1200 m were recorded between January 2008 and December 2011 at the Kochi Fisheries Harbour (Kerala). A total of 431 individuals, from 46 to 318 cm total length (L(T)) and 0·8 to 132 kg total mass (M(T)), were examined to determine biological data for this species. The LT at which 50% were mature (L(T)50) for females and males was estimated at 189 and 187 cm LT. Litter size ranged from 10 to 36 and size at birth was between 42 and 46 cm L(T). Dietary analysis of stomach contents revealed E. brucus feeds on a variety of prey including crustaceans (69% index of relative importance, I(RI)), teleosts (25·8% I(RI)), cephalopods (1·7% I(RI)) and elasmobranchs (0·7% I(RI)). This study provides the first detailed biological data for this species and also highlights the extent of the by-catch fishery for this species in Indian waters. PMID:24580658

  7. Metal concentrations in pearl oyster, Pinctada radiata, collected from Saudi Arabian coast of the Arabian Gulf

    SciTech Connect

    Sadig, M.; Alam, I.

    1989-01-01

    The Arabian Gulf is a shallow semi-closed water body. Several industrial complexes have been established along its coast line during the past decade. The effluent from these facilities is being discharged into the Gulf. These discharges pose potential hazards to the marine environment of the Arabian Gulf. The Saudi Arabian government is striving to protect the marine environment of the Gulf and has commissioned several studies to assess the damage from the industrial and municipal discharges. In these studies, marine organisms, for example, fish, clams, sea urchins, oysters, and plankton, along with sediments and seawater, have been analyzed for various pollutants. This study reports metal concentrations in pearl oysters collected from the Saudi Arabian coastal areas of the Arabian Gulf.

  8. Joint influence of the Indo-Pacific Warm Pool and Northern Arabian Sea Temperatures on the Indian Summer Monsoon in a Global Climate Model Simulation

    NASA Astrophysics Data System (ADS)

    Befort, Daniel J.; Leckebusch, Gregor C.; Cubasch, Ulrich

    2016-04-01

    Proxy-based studies confirmed that the Indian Summer Monsoon (ISM) shows large variations during the Holocene. These changes might be explained by changes in orbital conditions and solar insolation but are also thought to be associated to changes in oceanic conditions, e.g. over the Indo-Pacific-Warm-Pool region. However, due to the nature of these (proxy-based) analyses no conclusion about atmospheric circulation changes during dry and wet epochs are possible. Here, a fully-coupled global climate simulation (AOGCM) covering the past 6000 years is analysed regarding ISM variability. Several dry and wet epochs are found, the most striking around 2ka BP (dry) and 1.7ka BP (wet). As only orbital parameters change during integration, we expect these "shorter-term" changes to be associated with changes in oceanic conditions. During 1.7ka BP the sea surface temperatures (SST) over the Northern Arabian Sea (NARAB) are significantly warmer compared to 2ka BP, whereas cooler conditions are found over the western Pacific Ocean. Additionally, significant differences are found over large parts of the North Atlantic. To explain in how far these different ocean basins are responsible for anomalous conditions during 1.7ka BP, several sensitivity experiments with changed SST/SIC conditions are carried out. It is found that neither the SST's in the Pacific nor in the Indian Ocean are able to reproduce the anomalous rainfall and atmospheric circulation patterns during 1.7ka on its own. Instead, anomalous dry conditions during 2ka BP and wet conditions during 1.7ka BP are associated with a shift of the Indo-Pacific-Warm-Pool (IPWP) and simultaneous anomalous sea-surface temperatures over the NARAB region. Eventually, it is tested in how far this hypothesis holds true for other dry and wet events in the AOGCM data during the whole 6000 years. In general, a shift of the IPWP without anomalous SST conditions over the NARAB region (and vice versa) is not sufficient to cause long

  9. Evaluation of metal enrichment and trophic status on the basis of biogeochemical analysis of shelf sediments of the southeastern Arabian Sea, India

    NASA Astrophysics Data System (ADS)

    Cheriyan, Eldhose; Sreekanth, Athira; Mrudulrag, S. K.; Sujatha, C. H.

    2015-10-01

    The present study investigated the distribution of environmentally relevant metals and organic matter in the shelf sediments of the southeastern Arabian Sea using biogeochemical proxies for the assessment of environmental quality and trophic status. The distribution of metals in the study site followed the order: Fe>Mg>Pb>Ni>Mn>Co>Cu>Zn>Cd. High biological productivity associated with upwelling leads to significant accumulation of Cd higher than crustal abundance in the shelf region. The enrichment factor (EF) of metals demonstrate enrichment of Pb and Co which suggests the anthropogenic influence and not redox conditions. The sediment quality guidelines (SQG) in comparison with metal concentration revealed adverse effects, possibly occurring in marine benthic species. The spatial trend of metal enrichment along transects is appreciably controlled by the adsorption to fine grained sediments. The multivariate statistical analyses, such as correlations and principal component analysis (PCA) clearly indicated the control of texture, association of clay minerals in the degree of trace metal (Cd, Pb, Ni and Co) contamination from anthropogenic as well as natural sources. Low levels of Zn, preferably display scavenging by Fe/Mn metal oxides. Biochemical descriptors in sediments indicated meso-oligotrophic conditions prevailing in the summer monsoon. The ratios among various biogeochemical parameters such as total organic carbon/total nitrogen (TOC/TN<10), protein/carbohydrate (PRT/CHO<1) displayed that the organic matter deposited of marine origin which is relatively old with potentially low nutritional value. The close relationship between biochemical components and phytopigments suggest a major contribution of autochthonous phytodetritus derived organic matter. The study provides important information about sediment biogeochemistry and metal contamination from a potential fishery zone of Indian exclusive economic zone.

  10. The abundance of functional genes, cbbL, nifH, amoA and apsA, and bacterial community structure of intertidal soil from Arabian Sea.

    PubMed

    Keshri, Jitendra; Yousuf, Basit; Mishra, Avinash; Jha, Bhavanath

    2015-06-01

    The Gulf of Cambay is a trumpet-shaped inlet of the Arabian Sea, located along the west coast of India and confronts a high tidal range with strong water currents. The region belongs to a semi-arid zone and saline alkaline intertidal soils are considered biologically extreme. The selected four soil types (S1-S4) were affected by salinity, alkalinity and sodicity. Soil salinity ranged from 20 to 126 dS/m, soil pH 8.6-10.0 with high sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP). Abundance of the key functional genes like cbbL, nifH, amoA and apsA involved in biogeochemical cycling were targeted using qPCR, which varied from (2.36 ± 0.03) × 10(4) to (2.87 ± 0.26) × 10(8), (1.18 ± 0.28) × 10(6) to (1.01 ± 0.26) × 10(9), (1.41 ± 0.21) × 10(6) to (1.29 ± 0.05) × 10(8) and (8.47 ± 0.23) × 10(4) to (1.73 ± 0.01) × 10(6) per gram dry weight, respectively. The microbial community structure revealed that soils S1 and S3 were dominated by phylum Firmicutes whereas S4 and S2 showed an abundance of Proteobacterial clones. These soils also represented Bacteroidetes, Chloroflexi, Actinobacteria, Planctomycetes and Acidobacteria clones. Molecular phylogeny showed a significant variation in the bacterial community distribution among the intertidal soil types. A high number of novel taxonomic units were observed which makes the intertidal zone a unique reservoir of unidentified bacterial taxa that may be explored further.

  11. 16SrRNA and enzymatic diversity of culturable bacteria from the sediments of oxygen minimum zone in the Arabian Sea.

    PubMed

    Divya, Baby; Soumya, K V; Nair, Shanta

    2010-06-01

    Sediment underlying the oxygen minimum zone of the eastern Arabian Sea is rich in organic matter. Bacteria in this sediment-water interface are of great ecological importance as they are responsible for decomposing, mineralizing and subsequent recycling of organic matter. This study has for the first time addressed the phylogenetic and functional description of culturable bacteria of this region. Genotypic characterization of the isolates using amplified rDNA restriction analysis (ARDRA) followed by 16SrRNA sequencing grouped them into various phylogenetic groups such as Firmicutes, Gammaproteobacteria, Low G+C Gram positive bacteria, Actinobacteria and unaffiliated bacteria. Among the enzyme activities, phosphatase was predominant (52%) and was associated with all the phylotypes followed by amylase (37%) and gelatinase (33%). These hydrolytic enzymes were expressed at a wide range of temperature and pH. Firmicutes expressed most of the hydrolytic activities, consistent with a role in degradation of organic matter. Multiple enzyme expression (>/=3) was exhibited by Actinobacteria (100%), followed by unaffiliated group (62.5%) and Firmicutes (61.5%). Besides hydrolytic enzymes, the phylotypes also elaborated functional enzymes such as nitrate reductase and catalase (58 and 81% of the isolates, respectively). In the oxygen minimum zone, the diversity was high with 28 phylotypes. Culturable bacterial assemblages encountered were Bacillus sp., Halobacillus sp., Virgibacillus sp., Paenibacillus sp., Marinilactibacillus sp., Kytococcus sp., Micrococcus sp., Halomonas sp. and Alteromonas sp. The high diversity and high percentage of extracellular hydrolytic enzyme activities of the culturable bacteria reflect their important ecological role in biogeochemical cycling of organic matter in the oxygen minimum zone.

  12. Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea.

    PubMed

    Enge, Annekatrin J; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F M; Hunter, William R; Heinz, Petra

    2016-01-01

    Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with (13)C and (15)N) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low-oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels.

  13. Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea

    PubMed Central

    Enge, Annekatrin J.; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F. M.; Hunter, William R.; Heinz, Petra

    2016-01-01

    Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with 13C and 15N) by calcareous foraminifera in the 0–1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low-oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels. PMID:26903959

  14. Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea.

    PubMed

    Enge, Annekatrin J; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F M; Hunter, William R; Heinz, Petra

    2016-01-01

    Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with (13)C and (15)N) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low-oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels. PMID:26903959

  15. The abundance of functional genes, cbbL, nifH, amoA and apsA, and bacterial community structure of intertidal soil from Arabian Sea.

    PubMed

    Keshri, Jitendra; Yousuf, Basit; Mishra, Avinash; Jha, Bhavanath

    2015-06-01

    The Gulf of Cambay is a trumpet-shaped inlet of the Arabian Sea, located along the west coast of India and confronts a high tidal range with strong water currents. The region belongs to a semi-arid zone and saline alkaline intertidal soils are considered biologically extreme. The selected four soil types (S1-S4) were affected by salinity, alkalinity and sodicity. Soil salinity ranged from 20 to 126 dS/m, soil pH 8.6-10.0 with high sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP). Abundance of the key functional genes like cbbL, nifH, amoA and apsA involved in biogeochemical cycling were targeted using qPCR, which varied from (2.36 ± 0.03) × 10(4) to (2.87 ± 0.26) × 10(8), (1.18 ± 0.28) × 10(6) to (1.01 ± 0.26) × 10(9), (1.41 ± 0.21) × 10(6) to (1.29 ± 0.05) × 10(8) and (8.47 ± 0.23) × 10(4) to (1.73 ± 0.01) × 10(6) per gram dry weight, respectively. The microbial community structure revealed that soils S1 and S3 were dominated by phylum Firmicutes whereas S4 and S2 showed an abundance of Proteobacterial clones. These soils also represented Bacteroidetes, Chloroflexi, Actinobacteria, Planctomycetes and Acidobacteria clones. Molecular phylogeny showed a significant variation in the bacterial community distribution among the intertidal soil types. A high number of novel taxonomic units were observed which makes the intertidal zone a unique reservoir of unidentified bacterial taxa that may be explored further. PMID:25862282

  16. Trophic organisation and predator-prey interactions among commercially exploited demersal finfishes in the coastal waters of the southeastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Abdurahiman, K. P.; Nayak, T. H.; Zacharia, P. U.; Mohamed, K. S.

    2010-05-01

    Trophic interactions in commercially exploited demersal finfishes in the southeastern Arabian Sea of India were studied to understand trophic organization with emphasis on ontogenic diet shifts within the marine food web. In total, the contents of 4716 stomachs were examined from which 78 prey items were identified. Crustaceans and fishes were the major prey groups to most of the fishes. Based on cluster analysis of predator feeding similarities and ontogenic diet shift within each predator, four major trophic guilds and many sub-guilds were identified. The first guild 'detritus feeders' included all size groups of Cynoglossus macrostomus, Pampus argenteus, Leiognathus bindus and Priacanthus hamrur. Guild two, named 'Shrimp feeders', was the largest guild identified and included all size groups of Rhynchobatus djiddensis and Nemipterus mesoprion, medium and large Nemipterus japonicus, P. hamrur and Grammoplites suppositus, small and medium Otolithes cuvieri and small Lactarius lactarius. Guild three, named 'crab and squilla feeders', consisted of few predators. The fourth trophic guild, 'piscivores', was mainly made up of larger size groups of all predators and all size groups of Pseudorhombus arsius and Carcharhinus limbatus. The mean diet breadth and mean trophic level showed strong correlation with ontogenic diet shift. The mean trophic level varied from 2.2 ± 0.1 in large L. bindus to 4.6 ± 0.2 in large Epinephelus diacanthus and the diet breadth from 1.4 ± 0.3 in medium P. argenteus to 8.3 ± 0.2 in medium N. japonicus. Overall, the present study showed that predators in the ecosystem have a strong feeding preference for the sergestid shrimp Acetes indicus, penaeid shrimps, epibenthic crabs and detritus.

  17. Southern Hemisphere imprint for Indo-Asian summer monsoons during the last glacial period as revealed by Arabian Sea productivity records

    NASA Astrophysics Data System (ADS)

    Caley, T.; Zaragosi, S.; Bourget, J.; Martinez, P.; Malaizé, B.; Eynaud, F.; Rossignol, L.; Garlan, T.; Ellouz-Zimmermann, N.

    2013-06-01

    The monsoon is one of the most important climatic phenomena: it promotes inter-hemispheric exchange of energy and affects the economical prosperity of several countries exposed to its seasonal seesaw. Previous studies in both the Indian and Asian monsoon systems have suggested a dominant north hemispheric (NH) control on summer monsoon dynamics at the scale of suborbital-millennial climatic changes, while the forcing/response of Indian and Asian monsoons at the orbital scale remains a matter of debate. Here nine marine sediment cores distributed across the whole Arabian Sea are used to build a regional surface marine productivity signal. The productivity signal is driven by the intensity of Indian summer monsoon winds. Results demonstrate the existence of an imprint of suborbital Southern Hemisphere (SH) temperature changes (i.e., Antarctica) on the Indian summer monsoon during the last glacial period, challenging the traditional and exclusive NH forcing hypothesis. Meanwhile, during the last deglaciation, the NH plays a more significant role. The δ18O signal recorded in the Asian monsoon speleothem records could be exported by winds from the Indian summer monsoon region, as recently proposed in modelling exercise, explaining the SH signature observed in Asian cave speleothems. Contrary to the view of a passive response of Indian and Asian monsoons to NH anomalies, the present results strongly suggest that the Indo-Asian summer monsoon plays an active role in amplifying millennial inter-hemispheric asymmetric patterns. Additionally, this study helps to decipher the observed differences between Indian and Asian-speleothem monsoonal records at the orbital-precession scale.

  18. Southern Hemisphere imprint for Indo-Asian summer monsoons during the last glacial period as revealed by Arabian Sea productivity records

    NASA Astrophysics Data System (ADS)

    Caley, T.; Zaragosi, S.; Bourget, J.; Martinez, P.; Malaizé, B.; Eynaud, F.; Rossignol, L.; Garlan, T.; Ellouz-Zimmermann, N.

    2013-11-01

    The monsoon is one of the most important climatic phenomena: it promotes inter-hemispheric exchange of energy and affects the economical prosperity of several countries exposed to its seasonal seesaw. Previous studies in both the Indian and Asian monsoon systems have generally suggested a dominant northern hemispheric (NH) control on summer monsoon dynamics at the scale of suborbital-millennial climatic changes, while the forcing/response of Indian and Asian monsoons at the orbital scale remains a matter of debate. Here, six marine sediment cores distributed across the whole Arabian Sea are used to build a regional surface marine productivity signal. The productivity signal is driven by the intensity of Indian summer monsoon winds. Our results demonstrate the existence of an imprint of suborbital southern hemispheric (SH) temperature changes (i.e. Antarctica) on the Indian summer monsoon during the last glacial period that is generally not recognized. During the last deglaciation, the NH played a more significant role. This suggests that fluctuations in the Indian monsoon are better explained in a bipolar context. The δ18O signal recorded in the Asian monsoon speleothem records could be exported by winds from the Indian summer monsoon region, as recently proposed in modelling exercise, explaining the SH signature observed in Asian cave speleothems. Contrary to the view of a passive response of Indian and Asian monsoons to NH anomalies, the present results appear to suggest that the Indo-Asian summer monsoon plays an active role in amplifying millennial inter-hemispheric asymmetric patterns. Additionally, this study confirms previously observed differences between Indian and Asian speleothem monsoonal records at the orbital-precession scale.

  19. 16SrRNA and enzymatic diversity of culturable bacteria from the sediments of oxygen minimum zone in the Arabian Sea.

    PubMed

    Divya, Baby; Soumya, K V; Nair, Shanta

    2010-06-01

    Sediment underlying the oxygen minimum zone of the eastern Arabian Sea is rich in organic matter. Bacteria in this sediment-water interface are of great ecological importance as they are responsible for decomposing, mineralizing and subsequent recycling of organic matter. This study has for the first time addressed the phylogenetic and functional description of culturable bacteria of this region. Genotypic characterization of the isolates using amplified rDNA restriction analysis (ARDRA) followed by 16SrRNA sequencing grouped them into various phylogenetic groups such as Firmicutes, Gammaproteobacteria, Low G+C Gram positive bacteria, Actinobacteria and unaffiliated bacteria. Among the enzyme activities, phosphatase was predominant (52%) and was associated with all the phylotypes followed by amylase (37%) and gelatinase (33%). These hydrolytic enzymes were expressed at a wide range of temperature and pH. Firmicutes expressed most of the hydrolytic activities, consistent with a role in degradation of organic matter. Multiple enzyme expression (>/=3) was exhibited by Actinobacteria (100%), followed by unaffiliated group (62.5%) and Firmicutes (61.5%). Besides hydrolytic enzymes, the phylotypes also elaborated functional enzymes such as nitrate reductase and catalase (58 and 81% of the isolates, respectively). In the oxygen minimum zone, the diversity was high with 28 phylotypes. Culturable bacterial assemblages encountered were Bacillus sp., Halobacillus sp., Virgibacillus sp., Paenibacillus sp., Marinilactibacillus sp., Kytococcus sp., Micrococcus sp., Halomonas sp. and Alteromonas sp. The high diversity and high percentage of extracellular hydrolytic enzyme activities of the culturable bacteria reflect their important ecological role in biogeochemical cycling of organic matter in the oxygen minimum zone. PMID:20229220

  20. Calappid and leucosiid crabs (Crustacea: Decapoda: Brachyura) from Kerala, India, with the description of a new species of Mursia Desmarest, 1823, from the Arabian Sea and redescription of M. bicristimana Alcock & Anderson, 1894.

    PubMed

    Kumar, Biju A; Kumar, M Sushil; Galil, Bella S

    2013-01-01

    Eleven species of calappid and leucosiid crabs were identified from by-catch landed by trawlers at four fishing ports in Kerala, India that were surveyed in 2007 and supplemented by material obtained in January 2013. Four species are reported for the first time from India, six are new records for Kerala. The status of Mursia bicristimana Alcock & Anderson, 1894, is clarified and the species redescribed. A new species of Mursia is described from the Gulf of Aden, Arabian Sea.  PMID:25113495

  1. Flux and accumulation of sedimentary particles off the continental slope of Pakistan: a comparison of water column and seafloor estimates from the oxygen minimum zone, NE Arabian Sea

    NASA Astrophysics Data System (ADS)

    Schulz, H.; von Rad, U.

    2013-07-01

    Due to the lack of bioturbation, the laminated muds from the oxygen-minimum zone (OMZ) off Pakistan provide a unique opportunity to precisely determine the vertical and lateral sediment fluxes in the near shore part of the northeastern Arabian Sea, and to explore the effects of the margin topography and the low oxygen conditions on the accumulation of organic matter and other particles. West of Karachi, in the Hab river area of EPT and WPT (Eastern and Western PAKOMIN Traps), 16 short sediment profiles from water depths between 250 m and 1970 m on a depth transect crossing the OMZ (~ 120 to ~ 1200 m water depth) were investigated, and correlated on the basis of a thick, light-gray- to reddish-colored turbidite layer. Varve counting yielded a date for this layer of AD 1905 to 1888. We adopted the young age which agrees with 210Pb- dating, and used this isochronous stratigraphic marker bed to calculate sediment accumulation rates, that we could directly compare with the flux rates from the sediment traps installed within the water column above. All traps in the area show exceptionally high, pulsed winter fluxes of up to 5000 mg m-2 d-1 in this margin environment. The lithic flux at the sea floor is as high as 4000 mg m-2 d-1 , and agrees remarkably well with the bulk winter flux of material. This holds as well for the individual bulk components (organic carbon, calcium carbonate, opal, lithic fraction). However, the high winter flux events (HFE) by their extreme mass of remobilized matter terminated the recording in the shallow traps by clogging the funnels. Based on our comparisons, we argue that HFE for the past 5000 yr most likely occurred as regular events within the upper OMZ off Pakistan. Coarse fraction and foraminiferal accumulation rates from sediment surface samples along the Hab transect show distribution patterns that seem to be a function of water depth and distance from the shelf. Some of these sediment fractions show sudden shifts at the lower boundary

  2. Regional variation in the structure and function of parrotfishes on Arabian reefs.

    PubMed

    Hoey, Andrew S; Feary, David A; Burt, John A; Vaughan, Grace; Pratchett, Morgan S; Berumen, Michael L

    2016-04-30

    Parrotfishes (f. Labridae) are a unique and ubiquitous group of herbivorous reef fishes. We compared the distribution and ecosystem function (grazing and erosion) of parrotfishes across 75 reefs in Arabia. Our results revealed marked regional differences in the abundance, and taxonomic and functional composition of parrotfishes between the Red Sea, Arabian Sea, and Arabian Gulf. High densities and diversity of parrotfishes, and high rates of grazing (210% year(-1)) and erosion (1.57 kgm(-2)year(-1)) characterised Red Sea reefs. Despite Arabian Sea and Red Sea reefs having broadly comparable abundances of parrotfishes, estimates of grazing (150% year(-1)) and erosion (0.43 kgm(-2)year(-1)) were markedly lower in the Arabian Sea. Parrotfishes were extremely rare within the southern Arabian Gulf, and as such rates of grazing and erosion were negligible. This regional variation in abundance and functional composition of parrotfishes appears to be related to local environmental conditions.

  3. Regional variation in the structure and function of parrotfishes on Arabian reefs.

    PubMed

    Hoey, Andrew S; Feary, David A; Burt, John A; Vaughan, Grace; Pratchett, Morgan S; Berumen, Michael L

    2016-04-30

    Parrotfishes (f. Labridae) are a unique and ubiquitous group of herbivorous reef fishes. We compared the distribution and ecosystem function (grazing and erosion) of parrotfishes across 75 reefs in Arabia. Our results revealed marked regional differences in the abundance, and taxonomic and functional composition of parrotfishes between the Red Sea, Arabian Sea, and Arabian Gulf. High densities and diversity of parrotfishes, and high rates of grazing (210% year(-1)) and erosion (1.57 kgm(-2)year(-1)) characterised Red Sea reefs. Despite Arabian Sea and Red Sea reefs having broadly comparable abundances of parrotfishes, estimates of grazing (150% year(-1)) and erosion (0.43 kgm(-2)year(-1)) were markedly lower in the Arabian Sea. Parrotfishes were extremely rare within the southern Arabian Gulf, and as such rates of grazing and erosion were negligible. This regional variation in abundance and functional composition of parrotfishes appears to be related to local environmental conditions. PMID:26608505

  4. A multiproxy approach to understanding the "enhanced" flux of organic matter through the oxygen-deficient waters of the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Keil, Richard G.; Neibauer, Jacquelyn A.; Biladeau, Christina; van der Elst, Kelsey; Devol, Allan H.

    2016-04-01

    Free-drifting sediment net traps were deployed 14 times at depths between 80 and 500 m for 1-3 days each during the late monsoon-intermonsoon transition in the central Arabian Sea. Two locations (19.5 and 15.5° N) were within the permanently oxygen-deficient zone (ODZ), and a third (11° N) had a shallow and thin oxygen minimum. The secondary nitrite maximum, which serves as a tracer of the ODZ, thinned from ˜ 250 m thick at stations 19.5 and 15.5° N to ˜ 50 m thick at station 11° N. Overall, organic carbon fluxes ranged from 13.2 g m2 yr-1 at 80 m to a minimum of 1.1 g m2 yr-1 at 500 m. Fluxes at the more oxygenated 11° N station attenuate faster than within the permanent ODZ. Martin curve attenuation coefficients for 19.5 and 15.5° N are respectively 0.59 and 0.63 and for 11° N it is 0.98. At least six potential mechanisms might explain why particles sinking through the ODZ are more effectively transferred to depth: (M1) oxygen effects, (M2) microbial loop efficiencies and chemoautotrophy, (M3) changes in zooplankton dynamics, (M4) additions of ballast that might sorb and protect organic matter from decay (M4a) or change sinking speeds (M4b), (M5) inputs of refractory organic matter and (M6) temperature effects. These mechanisms are intertwined, and they were explored using a combination of mineral (XPS) and organic matter characterizations of the sinking material, shipboard incubation experiments, and evaluations of existing literature. Direct evidence was found supporting an oxygen effect and/or changes in the efficiency of the microbial loop including the addition of chemoautotrophic carbon to the sinking flux in the upper 500 m. Less direct evidence was found for the other potential mechanisms. A simple conceptual model consistent with our and other recent data suggests that the upper ODZ microbial community determines the initial flux attenuation, and that zooplankton and sinking speed become more important deeper in the water column. The exact

  5. Laminated Sediments of the Northern Arabian Sea: Tracking Climatic and Human Impacts on Late Holocene Erosion and Weathering Intensities in SW Asia

    NASA Astrophysics Data System (ADS)

    Forke, Sven; Rixen, Tim

    2014-05-01

    In the face of recent climate change, the need of understanding the mechanisms of climate variability increases continuously. However, most palaeo-climatic and -oceanographic records are restricted to timescales that have too low resolutions to take immediate appeal. Besides tree ring, speleothem and coral records, laminated lacustrine and marine sediments offer the required temporal resolution of decadal and also interannual scales to decipher climatic changes properly. Laminated sediments of the northern Arabian Sea provide such an excellent high-resolution archive for marine and terrestrial environmental changes. Fluvial and aeolian transported detritus are the major constituents of the sediment succession and give good indications of natural climatic and human impact by integrating precipitation and erosion signals of large continental areas of SW Asia. We present data of the seasonal laminated sediment core SO130-275KL (Lat 24°82', Lon 65°91'; 782 mbsl) from the oxygen minimum zone (OMZ) off Karachi, eastern Pakistan. The sediment core is well dated by varve counting and AMS 14C methods, and comprises the late Holocene period (ca. 5,000 years). We applied grain-size analysis in combination with the chemical index on alteration (CIA) on the lithogenic matter portion of the sediment in order to investigate the regional impact of climatic variability and human land use change on soil erosion, soil transport, and silicate weathering. Our data implies a significant distal and proximal aeolian dust contribution to both lithotypes, which were probably re-deposited in combination with riverine sediment load. In doing so, strong aeolian-fluvial interactions as observed in other semi-arid and arid environments of today are very obvious. Fluvial mud and distal aeolian dust percentages show a near-parallel increase after ca. 2,700 years B.P. in combination with reduction of coastal dune activity. Therefore, we assume an increase in winter precipitation intensity due to

  6. Comparison of benthic foraminifera inside and outside a sulphur-oxidizing bacterial mat from the present oxygen-minimum zone off Pakistan (NE Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Erbacher, Jochen; Nelskamp, Susanne

    2006-05-01

    Assemblages of live (Rose-Bengal-stained) and dead benthic foraminifera and stable oxygen and carbon isotopic composition of live benthic foraminifera were studied in and outside a bacterial mat composed of the large sulphur-oxidizing bacteria Thioploca and Beggiatoa from the oxygen-minimum zone off Pakistan (NE Arabian Sea). Two cores from the same Multicorer retrieved a bacterial mat and ambient sediment. The dominant species ( Globobulimina affinis, G. turgida, Bolivina pacifica, B. pseudopunctata, Uvigerina peregrina and Buliminella tenuata) in both cores are characteristic for dysoxic oxygen minimum zone conditions. The most significant difference between the two cores is the reduced number of stained benthic foraminifera (SBF) in the top 0.5 cm of the bacterial mat. Faunal densities of stained species are more than four times higher in the sediment surface sample (0-0.5 cm) outside the bacterial mat, at a distance of only 1.5 m. All stained species, however, observed outside the Beggiatoa/Thioploca mat were also observed in the core with the mat. Two species, Virgulinella fragilis and Bolivina dilatata, occur exclusively in the core with the bacterial mat. The diversity within the bacterial mat core is thus slightly higher than outside. Furthermore, the abundances of the species Buliminella morgani, B. tenuata and Alliatina primitiva are substantially higher in the bacterial mat than outside. Globobuliminids, on the other hand, seem to prefer the conditions outside the bacterial mat and are five times more frequent in the core taken outside the bacterial mat. Benthic foraminifers inhabit a broader microhabitat range outside the bacterial mat (˜5 cm) than within (3.5 cm). A marked decrease in SBF abundances was observed at the level of a black sulphur-rich layer which is interpreted to mark the shallow redox front below the bacterial mat. Stable carbon isotope analyses on live benthic foraminifera do not support a relation of the investigated Beggiatoa

  7. Red Sea

    Atmospheric Science Data Center

    2013-04-16

    article title:  The Red Sea     View Larger Image ... Imaging SpectroRadiometer (MISR) image of the Red Sea was acquired on August 13, 2000. Located between the East African coast and the Saudi Arabian peninsula, the Red Sea got its name because the blooms of a type of algae,  Trichodesmium ...

  8. Lamellodiscus aff. euzeti Diamanka, Boudaya, Toguebaye & Pariselle, 2011 (Monogenea: Diplectanidae) from the gills of Cheimerius nufar (Valenciennes) (Pisces: Sparidae) collected in the Arabian Sea, with comments on the distribution, specificity and historical biogeography of Lamellodiscus spp.

    PubMed

    Machkewskyi, Volodymyr K; Dmitrieva, Evgenija V; Gibson, David I; Al-Jufaili, Sara

    2014-11-01

    Specimens of Lamellodiscus Johnston & Tiegs, 1922 (Monogenea: Diplectanidae) were collected from the gills of Cheimerius nufar (Valenciennes) (Sparidae) in the Arabian Sea. All of these parasites belonged to one and the same species, which is morphologically very close to L. euzeti Diamanka, Boudaya, Toguebaye & Pariselle, 2011. A different host, distant locality and small morphological differences compared with the original description of L. euzeti acted as a stimulus for a detailed redescription. The specimens from the Arabian Sea differ slightly in the details of the male copulatory organ (MCO) from the type-specimens of L. euzeti, which were re-examined, and from the respective drawings in its original description. Such differences include a longer inner process of the large element of the accessory piece associated with the proximal part of the copulatory tube, a longer point on the small element of the accessory piece associated with the distal part of the copulatory tube, and the presence of a smooth or slightly folded inner margin of this element rather than structures resembling spines which occur in the type-specimens of L. euzeti. Therefore, the present specimens infecting C. nufar in the Indo-Pacific may represent a different, but morphologically very similar species to the Atlantic form L. euzeti; consequently, they are recognised here as Lamellodiscus aff. euzeti. This form belongs to the 'ignoratus s. str.' subgroup of the genus. The composition of this subgroup is redefined to comprise 17 species, including L. corallinus Paperna, 1965 but excluding L. acanthopagri Roubal, 1981, and the morphology of the MCO of representatives of this group is clarified. A link between the diversity of Lamellodiscus species and the ancestral origin of present-day sparid species in the Tethys Sea is suggested. It is shown that Lamellodiscus spp. exhibit rather high levels of specificity to their hosts, since half of them parasitise only a single host species and c.90

  9. Acoustic Doppler current profiling from the JGOFS Arabian Sea cruises aboard the RV T.G. THOMPSON: TN043, January 8, 1995--February 4, 1995; TN044, February 8, 1995--February 25, 1995; TN045, March 14, 1995--April 10, 1995; TN046, April 14, 1995--April 29, 1995

    SciTech Connect

    Flagg, C.N.; Kim, H.S.; Shi, Y.

    1995-09-01

    Acoustic Doppler current profiler (ADCP) data from the R/V T.G. THOMPSON is part of the core data for the US JGOFS Arabian Sea project along with hydrographic and nutrient data. Seventeen cruises on the THOMPSON are scheduled to take place between September 1994 and January 1996. This is the second in a series of data reports covering the ADCP data from the Arabian Sea JGOFS cruises TNO43 through TNO46. ADCP data are being collected on all the JGOFS Arabian Sea cruises using an autonomous data acquisition system developed for ship-of-opportunity cruises. This system, referred to as the AutoADCP, makes it possible to collect the ADCP data without the constant monitoring usually necessary and assures constant data coverage and uniform data quality. This data report presents ADCP results from the second group of four JGOFS cruises, TNO43 through TNO46, concentrating on the data collection and processing methods. The ADCP data itself reside in a CODAS data base at Brookhaven National Laboratory and is generally available to JGOFS investigators through contact with the authors. The CODAS data base and associated ADCP processing software were developed over a number of years by Eric Firing and his group at the University of Hawaii. The CODAS software is shareware available for PC`s or Unix computers and is the single most widely used ADCP processing program for ship mounted units.

  10. High-resolution Sr/Ca ratios in a Porites lutea coral from Lakshadweep Archipelago, southeast Arabian Sea: An example from a region experiencing steady rise in the reef temperature

    NASA Astrophysics Data System (ADS)

    Sagar, Netramani; Hetzinger, Steffen; Pfeiffer, Miriam; Masood Ahmad, Syed; Dullo, Wolf-Christian; Garbe-Schönberg, Dieter

    2016-01-01

    Here we present the first record of Sr/Ca variability in a massive Porites lutea coral from the Lakshadweep Archipelago, Arabian Sea. The annual mean sea surface temperature (SST) in this region and the surrounding areas has increased steadily in the recent past. During some major El Niño events, SSTs are even higher, imposing additional thermal-stress on corals, episodically leading to coral bleaching. We infer from the coral-Sr/Ca record (1981-2008) that during some of these events high and persistent SSTs lead to a dampening of the temperature signal in coral-Sr/Ca, impairing the coral's ability to record full scale warming. Thus, coral-Sr/Ca may provide a history of past El Niño Southern-Oscillation (ENSO) induced thermal-stress episodes, which are a recurrent feature also seen in cross-spectral analysis between coral-Sr/Ca and the Nino3.4 index. Despite the impact of episodical thermal-stress during major El Niño events, our coral proxy faithfully records the seasonal monsoon-induced summer cooling on the order of ˜2.3°C. Calibration of coral-Sr/Ca with instrumental grid-SST data shows significant correlation to regional SST and monsoon variability. Hence, massive Porites corals of this region are highly valuable archives for reconstructing long-term changes in SST, strongly influenced by monsoon variability on seasonal scales. More importantly, our data show that this site with increasing SST is an ideal location for testing the future effects of the projected anthropogenic SST increase on coral reefs that are already under thermal-stress worldwide.

  11. Sediment sound velocities from sonobuoys: Arabian fan

    SciTech Connect

    Bachman, R.T.; Hamilton, E.L.

    1980-02-10

    Eight variable-angle seismic reflection stations in the Arabian Fan, Northwestern Indian Ocean, provided 40 determinations of sound velocity in sediment and sedimentary rock. Sound velocity in the homogeneous, largely terrigenous fan increases smoothly with depth. Regression analysis yielded the velocity-time relationship V (km/s)=1.510+1.863t, where V is instantaneous velocity and t is one-way travel time below the sea floor to 1 s. The velocity-depth function is V (km/s)=1.510+1.200h-0.253h/sup 2/+ 0.034h/sup 3/, where h is subbottom depth in km.

  12. Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

    NASA Astrophysics Data System (ADS)

    Lengger, Sabine K.; Hopmans, Ellen C.; Reichart, Gert-Jan; Nierop, Klaas G. J.; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2012-12-01

    The TEX86 is a proxy based on a ratio of pelagic archaeal glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), and used for estimating past sea water temperatures. Concerns exist that in situ production of GDGTs lipids by sedimentary Archaea may affect its validity. In this study, we investigated the influence of benthic GDGT production on the TEX86 by analyzing the concentrations and distributions of GDGTs present as intact polar lipids (IPLs) and as core lipids (CLs) in three sediment cores deposited under contrasting redox conditions across a depth range from 900 to 3000 m below sea level in and below the Arabian Sea oxygen minimum zone (OMZ). Direct analysis of IPLs with crenarchaeol as CL via HPLC/ESI-MS2 revealed that surface sediments in the OMZ were relatively depleted in the phospholipid hexose, phosphohexose (HPH)-crenarchaeol compared to suspended particulate matter from the water column, suggesting preferential and rapid degradation of this IPL. In sediment cores recovered from deeper, more oxic environments, concentrations of HPH-crenarchaeol peaked at the surface, probably due to in situ production by ammonia-oxidizing Archaea, followed by a rapid decrease with increasing depth. No surface maximum was observed in the sediment core from within the OMZ. In contrast, the glycolipids, monohexose-crenarchaeol and dihexose-crenarchaeol, did not change in concentration with depth in the sediment, indicating that they were relatively well preserved and likely mostly derived from fossil pelagic GDGTs. These results suggest that phospholipids are more sensitive to degradation, while glycolipids might be preserved over longer time scales, in line with previous incubation and modeling studies. Furthermore, in situ produced IPL-GDGTs did not accumulate as IPLs, and did not influence the CL-TEX86. This suggests that in-situ produced GDGT lipids were more susceptible to degradation than fossil CL and IPL and did not accumulate as CL. In agreement, no

  13. Distribution of Permo-Carboniferous clastics of Greater Arabian basin

    SciTech Connect

    Al-Laboun, A.A.

    1987-05-01

    Strikingly correlative sequences of sediments composed of sandstones, siltstones, shales, and thin argillaceous carbonate beds are present, practically everywhere, underlying the Late Permian carbonates in the Greater Arabian basin. The Greater Arabian basin as defined here occupies the broad Arabian Shelf that borders the Arabian shield. This basin is composed of several smaller basins. These clastics are exposed as thin bands and scattered small exposures in several localities around the margins of the basin. The Permo-Carboniferous clastics are represented by the Unayzah Formation of Arabia, the Doubayat Group of Syria, the Hazro Formation of southeast Turkey, the Ga'arah Formation of Iraq, the Faraghan Formation of southwest Iran, and the Haushi Group of Oman. A Late Carboniferous-Early Permian age is assigned to these clastics because they contain fossil plants and palynomorphs. These sediments represent time-transgressive fluctuating sea deposits following a phase of regional emergence, erosion, and structural disturbance which preceded the Permian transgression. The basal contact of these clastics is marked by a well-pronounced angular unconformity with various older units, ranging in age from early Carboniferous to late Precambrian. This regional unconformity is probably related to the Hercynian movements. The upper contact is conformable with the Permian carbonates. The porous sandstones of the Permo-Carboniferous sediments are important hydrocarbon exploration targets. These reservoir rocks sometimes overlie mature source rocks and are capped by shales, marls, and tight carbonates. Significant quantities of hydrocarbons are contained in these reservoirs in different parts of the Greater Arabian basin.

  14. Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone: I. Selective preservation and degradation in the water column and consequences for the TEX86

    NASA Astrophysics Data System (ADS)

    Schouten, Stefan; Pitcher, Angela; Hopmans, Ellen C.; Villanueva, Laura; van Bleijswijk, Judith; Sinninghe Damsté, Jaap S.

    2012-12-01

    Glycerol dibiphytanyl glycerol tetraether lipids (GDGTs) have proven to be important biomarker lipids for specific archaeal lineages and their distribution is used as a paleotemperature proxy. In this study, we analyzed GDGTs in suspended particles in the water column of the Arabian Sea at different positions above, in and below the oxygen minimum zone (OMZ). GDGTs, both as intact polar lipid (IPL) and as core lipids, were detected throughout the water column but were most abundant at the upper part of the OMZ. Core lipid GDGTs, derived from non-living organic matter, were always much more abundant than GDGTs released by acid hydrolysis of an IPL fraction (IPL-derived GDGTs). Comparisons with 16S rRNA gene abundance showed that likely only 1-14% of total archaeal cells present were caught on the 0.7 μm filter used for lipid analysis. Despite this undersampling, the depth profiles of crenarchaeol core lipid with a phosphohexose or dihexose head group match previously reported profiles of (expressed) genes specific for ammonia-oxidizing Thaumarchaeota, such as 16S rDNA and amoA. In contrast, the crenarchaeol with a hexose head group as well as core lipid and IPL-derived crenarchaeol matched the genetic depth profiles much less, suggesting a contribution of GDGTs from non-living matter. TEX86 values of both core lipid and IPL-derived GDGTs increased from surface waters to the core of the OMZ, below which they decreased again, and did not correlate with in situ water temperature. In contrast, TEX86 values of IPL-derived GDGTs correlated well the relative amount of glycosidic GDGTs and were consistently higher than that those of CL GDGTs. This suggests that selective preservation of glycosidic GDGTs may mask TEX86 values of in situ produced GDGTs in deep marine waters.

  15. Provenance of the Heavy Mineral-enriched Alluvial Deposits at the West Coast of Red Sea. Implications to the Evolution of Arabian-Nubian Crust

    NASA Astrophysics Data System (ADS)

    Mahar, M. A.; Ibrahim, T.; Goodell, P.

    2014-12-01

    Here we present the LA-ICP-MS U-Pb ages and Hf isotopic record of detrital zircons from the active alluvial fans at the west coast of the Red Sea. The Ras Manazal alluvial fan (primarily composed of zircon, magnetite with some rutile, ilmenite and monazite) yielded a relatively restricted age population ranges from 765 to 666 Ma. These ages and present-day drainage pattern is consistent that the sediments are primarily derived from erosion of nearby subduction related granitoids in the immediate west (i.e., not more than 50 km from the Red Sea coast) of the fan. In contrast, approximately 160 km south, at the Egypt-Sudan border, the Wadi Diit fan is relatively more enriched in ilmenite and REE-bearing phases (e.g., thorite, monazite, xenotime, garnet etc.) and yielded five zircon age populations of 1) 824-733 Ma, 2) 730-705 Ma, 3) 646-608 Ma, 4) 516-500 Ma, and 5) 134-114 Ma. The age populations 1-3 if coupled with the present-day drainage pattern can be related to the earlier subduction related and later post collision granitoids in the southern part of the South Eastern Desert and Gebeit terrane of northern Sudan. Sparse Early Cretaceous zircons (134-114 Ma) are derived from the Mesozoic volcanic suits in the source region. However, the age group 516-500 Ma is enigmatic. Wadi Diit zircons are primarily derived from granitoids in the broad S-N directed Hamisana Shear Zone and its subordinate SW to NE directed Onib-Sol-Hamed Suture Zone. These shear zones provided pathways for the present-day drainage system for sediment transportation to the Wadi Diit and adjacent coastal region. We infer that the ca. 500 Ma late-stage magmatic zircons represent a hitherto unknown magmatic event, possibly related to the shear heating associated with the crustal scale shear zones. This implies that the shear zones in the South Eastern Desert and northern Sudan remained thermally active as late as ~500 Ma. The time resolved hafnium composition (ɛHf (t)) of both fans varies from +3

  16. Provenance of the heavy mineral-enriched alluvial deposits at the west coast of the Red Sea. Implications for evolution of Arabian-Nubian crust

    NASA Astrophysics Data System (ADS)

    Mahar, Munazzam Ali; Ibrahim, Tarek M. M.; Goodell, Philip C.

    2014-12-01

    Here we present the LA-ICP-MS U-Pb ages and Hf isotopic record of detrital zircons from the active alluvial fans at the west coast of the Red Sea. The Ras Manazal alluvial fan (primarily composed of zircon, magnetite with some rutile, ilmenite and monazite) yielded a relatively restricted age population ranges from 765 to 666 Ma. These ages and present-day drainage pattern is consistent that the sediments are primarily derived from erosion of nearby subduction related granitoids in the immediate west (i.e., not more than 50 km from the Red Sea coast) of the fan. In contrast, approximately 160 km south, at the Egypt-Sudan border, the Wadi Diit fan is relatively more enriched in ilmenite and REE-bearing phases (e.g., thorite, monazite, xenotime, garnet, etc.) and yielded five zircon age populations of (1) 824-733 Ma, (2) 730-705 Ma, (3) 646-608 Ma, (4) 516-500 Ma, and (5) 134-114 Ma. The age populations 1-3 if coupled with the present-day drainage pattern can be related to the earlier subduction related and later post collision granitoids in the southern part of the South Eastern Desert and Gebeit terrane of northern Sudan. Sparse Early Cretaceous zircons (134-114 Ma) are derived from the Mesozoic volcanic suits in the source region. However, the age group 516-500 Ma is enigmatic. Wadi Diit zircons are primarily derived from granitoids in the broad S-N directed Hamisana Shear Zone and its subordinate SW to NE directed Onib-Sol-Hamed Suture Zone. These shear zones provided pathways for the present-day drainage system for sediment transportation to the Wadi Diit and adjacent coastal region. We infer that the ca. 500 Ma late-stage magmatic zircons represent a hitherto unknown magmatic event, possibly related to the shear heating associated with the crustal scale shear zones. This implies that the shear zones in the South Eastern Desert and northern Sudan remained thermally active as late as ∼500 Ma. The time resolved hafnium composition (εHf (t)) of both fans varies

  17. Distribution patterns of toxic metals in the marine oyster Saccostrea cucullata from the Arabian Sea in Oman: spatial, temporal, and size variations.

    PubMed

    Yesudhason, Poulose; Al-Busaidi, Moza; Al-Rahbi, Waleed Ak; Al-Waili, Aaliah S; Al-Nakhaili, Adel K; Al-Mazrooei, Nashwa A; Al-Habsi, Saoud H

    2013-12-01

    The variations in size and spatial and temporal variations in concentrations of toxic metals (cadmium, mercury, and lead) in oyster tissues were studied. Samples were collected at monthly intervals over a 1-year period from three locations along the southern coast of Oman (Mirbat, Hadbeen, and Sadah). Cadmium and lead were analyzed using an inductively coupled plasma atomic emission spectrometer, and mercury was analyzed using a direct mercury analyzer. The annual mean concentrations in oyster tissues sampled from the three locations and from different time periods ranged from 2.64 to 3.80 mg kg(-1) for cadmium, 0.009 to 0.02 mg kg(-1) for lead, and 0.01 to 0.02 mg kg(-1) for mercury. The temporal effect on cadmium concentrations was more distinct than the local site-specific effect, with higher concentrations recorded in tissues during the summer season than in the winter season. Moreover, within each site, a significant time-specific dependence on the toxic metal concentration differences was recorded. Lipid content was found to influence mercury concentrations in the oysters; however, there was no relationship between cadmium or lead and moisture or lipid content. No distinct relationships were observed between the size of oysters and metal uptake by the oyster. The results were discussed in relation to those obtained from related species in the seas of Oman and worldwide.

  18. Crustal evolution of the northern Arabian platform in Syria

    SciTech Connect

    Best, J.A.; Muawia, B.; Chaimov, T.A. ); Al-Saad, D.; Sawaf, T.; Gebran, A. )

    1991-03-01

    Analysis of available geological and geophysical data within Syria has allowed for further understanding of the geologic history of the northern Arabian platform from Proterozoic to present. Elements of the history involve: Proterozoic convergence and suturing of at least two distinct microplates, minor Cambrian extension and associated magmatism, development of a failed intracratonic rift in the early Mesozoic, and inversion of that sedimentary trough that began in the Late Cretaceous. The diverse Phanerozoic tectonic features in Syria may be due to reactivation along older zones of weaknesses in the northern Arabian plate; the proposed Proterozoic suture zone lies along strike of the present day Palmyride intracratonic mountain belt. The construction of isopach maps of the Ordovician through Quaternary sections in Syria based on regional well control and seismic reflection data demonstrates regional structural-stratigraphic relationships. Basement deformation maps, derived from superposition of the formation isopachs, indicate the transformation of an east-directed Paleozoic margin into a well-directed Mesozoic margin (Levantine margin). Contemporaneous with this margin transformation was the development of an east-northeast-trending rift (Palmyride trough) toward the craton interior. Finally, Cenozoic eastward tilting of the Arabian plate, associated with loading of the plate along the Mesopotamian foredeep and uplift of the plate along the Red Sea margin is observed across the southern Arabian platform. Eastward tilting is also observed across the southern Arabian platform. Eastward tilting is also observed on the northern platform with respect to the top of the crystalline basement, indicating a similarity in response of the entire Arabian plate to loading and uplift along its margins.

  19. Long-term Variability of Carbon and Nitrogen in the Bay of Bengal and Arabian Sea: Results from NGHP Expedition 1

    NASA Astrophysics Data System (ADS)

    Johnson, J. E.; Phillips, S. C.; Miranda, E.; Giosan, L.; Rose, K.

    2009-12-01

    During the 2006 National Gas Hydrate program of India’s Expedition 1 (NGHP-01), 30 holes at 21 sites were drilled and cored to study gas hydrate occurrences at four regions along the peninsular Indian continental margins and in the Andaman accretionary wedge. In order to characterize the host sedimentary environment for gas hydrate at these sites we investigate the source and long-term variability of carbon and nitrogen through measurements of total organic carbon (TOC), organic carbon and nitrogen ratios (C/N), and organic carbon and nitrogen isotopes (δ13C and δ15N). TOC and C/N measurements were made at 9 core sites and δ13C and δ15N were measured at 4 core sites throughout the four regions. In the Krishna-Godavari Basin the mean TOC content of the Quaternary age sediments recovered at Sites NGHP-01-5C/D, -10B/D, -14A, -15A, -16A, and -20A/B is 1.58 wt % (σ = 0.64), with no significant variability with depth or from site to site. Mean C/N from these sites is 12.9 (σ = 3.97), with some variability between sites. At Site NGHP-01-16A, δ13C and δ15N measurements yield average values of -16.07 ‰ and 4.34 ‰, respectively. An abrupt decrease in the δ13C variability also occurs at this site at ~100 mbsf; from 0-98 mbsf the mean δ13C = -17.65 ‰ (σ = 1.95) and from 111-218 mbsf the mean δ13C = -13.73 ‰ (σ = 0.37). In the Mahanadi Basin, at Site NGHP-01-19A sediments deposited during the last ~9 Ma contain a mean TOC content of 1.12 wt % (σ = 0.22). Mean C/N at this site is 11.09 wt % (σ = 2.29) and average δ13C and δ15N values at Site 19A are -19.83 ‰ and 4.03 ‰, respectively. An abrupt decrease in the δ13C variability occurs at ~85 mbsf at this site, coincident with an unconformity at that same depth; 0-85 mbsf have a mean δ13C = -18.92 ‰ (σ = 1.12); 85-299 mbsf have a mean. δ13C = -20.71 ‰ (σ = 0.73). In the Andaman Sea at Site NGHP-01-17A the mean TOC content of the sediments deposited during the last ~9.4 Ma is 0.73 wt % (σ = 0

  20. Tectonic and deposition model of late Precambrian-Cambrian Arabian and adjoining plates

    SciTech Connect

    Husseini, M.I. )

    1989-09-01

    During the late Precambrian, the terranes of the Arabian and adjoining plates were fused along the northeastern flank of the African plate in Gondwanaland. This phase, which ended approximately 640 to 620 Ma, was followed by continental failure (620 to 580 Ma) and intracontinental extension (600 to approximately 550 Ma). During the Infracambrian extensional phase, a triple junction may have evolved near the Sinai Peninsula and may have consisted of the (1) Jordan Valley and Dead Sea rift branch, (2) Sinai and North Egypt rift branch, and (3) the Najd wrench-rift branch. The Najd, Hawasina, and Zagros fault systems may have been transverse faults that accompanied rifting in the Arabian Gulf and Zagros Mountains, southern Oman, Pakistan, and Kerman in central Iran. While the area was extending and subsiding, the Tethys Ocean flooded the eastern side of the Arabian plate and Iran and deposited calcareous clastics, carbonates, and evaporites (including the Hormuz and Ara halites). This transgression extended into the western part of the Arabian plate via the Najd rift system. The termination of the extensional phase during the late Early Cambrian was accompanied by a major regression and terrestrial conditions on the Arabian Peninsula. However, by the Early Ordovician, as sea level peaked to a highstand, the Arabian plate was blanketed with marginal marine sediments. 11 figs., 2 tabs.

  1. Structure of the Lithosphere and Upper Mantle Across the Arabian Peninsula

    SciTech Connect

    Al-Amri, A; Rodgers, A

    2007-01-05

    Analysis of modern broadband (BB) waveform data allows for the inference of seismic velocity structure of the crust and upper mantle using a variety of techniques. This presentation will report inferences of seismic structure of the Arabian Plate using BB data from various networks. Most data were recorded by the Saudi Arabian National Digital Seismic Network (SANDSN) which consists of 38 (26 BB, 11 SP) stations, mostly located on the Arabian Shield. Additional data were taken from the 1995-7 Saudi Arabian IRIS-PASSCAL Deployment (9 BB stations) and other stations across the Peninsula. Crustal structure, inferred from teleseismic P-wave receiver functions, reveals thicker crust in the Arabian Platform (40-45 km) and the interior of the Arabian Shield (35-40 km) and thinner crust along the Red Sea coast. Lithospheric thickness inferred from teleseismic S-wave receiver functions reveals very thin lithosphere (40-80 km) along the Red Sea coast which thickens rapidly toward the interior of the Arabian Shield (100-120 km). We also observe a step of 20-40 km in lithospheric thickness across the Shield-Platform boundary. Seismic velocity structure of the upper mantle inferred from teleseismic P- and S-wave travel time tomography reveals large differences between the Shield and Platform, with the Shield being underlain by slower velocities, {+-}3% for P-waves and {+-}6% for S-waves. Seismic anisotropy was inferred from shear-wave splitting, using teleseismic SKS waveforms. Results reveal a splitting time of approximately 1.4 seconds, with the fast axis slightly east of north. The shear-wave splitting results are consistent across the Peninsula, with a slight clockwise rotation parallel for stations near the Gulf of Aqaba. In summary, these results allow us to make several conclusions about the tectonic evolution and current state of the Arabian Plate. Lithospheric thickness implies that thinning near the Red Sea has accompanied the rupturing of the Arabian

  2. Petroleum geology of Arabian Peninsula

    SciTech Connect

    Billo, S.M.

    1982-05-01

    Petroleum activities in the Arabian Peninsula show new trends in the 1980s. Petroleum exploration is intensified and huge discoveries are anticipated. A giant Jurassic gas field along the coast of the Arabian Gulf discovered recently tops 150 tcf, the largest single reserve ever. Other giant oil fields in the area are undergoing expansion in development and productivity. Today, the Peninsula, with a total area that surpasses one million square miles, produces and exports more oil and gas and has greater reserves than any other area in the world. The excellent reservoir rocks are located in the Jurassic and Cretaceous formations between the Arabian Shield and the Tethyan Seaway. They represent porous and permeable marine cyclical beds sealed by impervious shales and anhydrites. Reservoir sedimentology was affected by 2 orogenies during late Cretaceous and Pliocene time portrayed by the Cratonic area to the southwest and the orthogeosynclinal area to the northeast. The eastern part was little deformed by these movements.

  3. Arabian crude-oil residues evaluated

    SciTech Connect

    Ali, M.F.; Bukhari, A.; Hasan, M.; Saleem, M.

    1985-08-12

    This article evaluates detailed physical and chemical characteristics for four important Saudi Arabian resids. Petroleum residues are composed of a mixture of large and complex hydrocarbon molecules along with one or more heteroatoms such as sulfur, oxygen, nitrogen, vanadium, and nickel. The amount of residue and its physical and chemical composition depend on the source of the crude oil and methods of processing. Residues from four Saudi Arabian crude oils produced by the Arabian American Oil Co. (Aramco) were evaluated. The crude oils are 38.5 degrees API Arabian Extra Light, 33.8 degrees API Arabian Light, 30.4 degrees Api Arabian Medium, and 28.03 degrees API Arabian Heavy. Results are presented and residue preparation, and physical and chemical characteristics are analyzed.

  4. Biodeterioration of concrete piling in the Arabian Gulf

    SciTech Connect

    Jadkowski, T.K.; Wiltsie, E.A.

    1985-03-01

    Concrete is one of the most widely used materials in marine construction because of its characteristic durability in sea environments. Recent inspection of concrete piles installed in the Arabian Gulf has revealed that concrete with high content of calcareous aggregate is susceptible to biodeterioration. Marine rock borers and sponges, which are common in areas where the seabed is composed of limestone rock, have been identified as the marine species responsible for the biodeterioration. Boring organisms pose a significant threat to concrete pile structural integrity. Boreholes deteriorate concrete and expose outer pile reinforcement to seawater. This paper describes the causes and magnitude of biodeterioration of piles installed in the Arabian Gulf and presents design parameters and material specifications for the selected preventive repair system.

  5. Increasing Arabian dust activity and the Indian summer monsoon

    NASA Astrophysics Data System (ADS)

    Solmon, F.; Nair, V. S.; Mallet, M.

    2015-07-01

    Over the past decade, aerosol optical depth (AOD) observations based on satellite and ground measurements have shown a significant increase over Arabia and the Arabian Sea, attributed to an intensification of regional dust activity. Recent studies have also suggested that west Asian dust forcing could induce a positive response of Indian monsoon precipitations on a weekly timescale. Using observations and a regional climate model including interactive slab-ocean and dust aerosol schemes, the present study investigates possible climatic links between the increasing June-July-August-September (JJAS) Arabian dust activity and precipitation trends over southern India during the 2000-2009 decade. Meteorological reanalysis and AOD observations suggest that the observed decadal increase of dust activity and a simultaneous intensification of summer precipitation trend over southern India are both linked to a deepening of JJAS surface pressure conditions over the Arabian Sea. In the first part of the study, we analyze the mean climate response to dust radiative forcing over the domain, discussing notably the relative role of Arabian vs. Indo-Pakistani dust regions. In the second part of the study, we show that the model skills in reproducing regional dynamical patterns and southern Indian precipitation trends are significantly improved only when an increasing dust emission trend is imposed on the basis of observations. We conclude that although interannual climate variability might primarily determine the observed regional pattern of increasing dust activity and precipitation during the 2000-2009 decade, the associated dust radiative forcing might in return induce a critical dynamical feedback contributing to enhancing regional moisture convergence and JJAS precipitations over southern India.

  6. Interannual variability and predictability over the Arabian Penuinsula Winter monsoon region

    NASA Astrophysics Data System (ADS)

    Adnan Abid, Muhammad; Kucharski, Fred; Almazroui, Mansour; Kang, In-Sik

    2016-04-01

    Interannual winter rainfall variability and its predictability are analysed over the Arabian Peninsula region by using observed and hindcast datasets from the state-of-the-art European Centre for Medium-Range Weather Forecasts (ECMWF) seasonal prediction System 4 for the period 1981-2010. An Arabian winter monsoon index (AWMI) is defined to highlight the Arabian Peninsula as the most representative region for the Northern Hemispheric winter dominating the summer rainfall. The observations show that the rainfall variability is relatively large over the northeast of the Arabian Peninsula. The correlation coefficient between the Nino3.4 index and rainfall in this region is 0.33, suggesting potentially some modest predictability, and indicating that El Nino increases and La Nina decreases the rainfall. Regression analysis shows that upper-level cyclonic circulation anomalies that are forced by El Nino Southern Oscillation (ENSO) are responsible for the winter rainfall anomalies over the Arabian region. The stronger (weaker) mean transient-eddy activity related to the upper-level trough induced by the warm (cold) sea-surface temperatures during El Nino (La Nina) tends to increase (decrease) the rainfall in the region. The model hindcast dataset reproduces the ENSO-rainfall connection. The seasonal mean predictability of the northeast Arabian rainfall index is 0.35. It is shown that the noise variance is larger than the signal over the Arabian Peninsula region, which tends to limit the prediction skill. The potential predictability is generally increased in ENSO years and is, in particular, larger during La Nina compared to El Nino years in the region. Furthermore, central Pacific ENSO events and ENSO events with weak signals in the Indian Ocean tend to increase predictability over the Arabian region.

  7. The surface heat flow of the Arabian Shield in Jordan

    NASA Astrophysics Data System (ADS)

    Förster, A.; Förster, H.-J.; Masarweh, R.; Masri, A.; Tarawneh, K.; Desert Group

    2007-04-01

    Surface heat flow in southern Jordan (western part of the Arabian Plate) was determined in a dense cluster of five, up to 900-m-deep boreholes that have encountered sedimentary rocks of Paleozoic (Ordovician and Silurian) age. These rocks are underlain by an igneous and metamorphic basement, which has been studied for its radiogenic heat production, along the eastern margin of the Dead Sea Transform (DST) fault system. The heat flow, calculated from continuous temperature logs and laboratory-measured thermal conductivity of drillcores and surface samples, averages to 60.3 ± 3.4 mW m -2 and contrasts the common view of the late Proterozoic-consolidated Arabian Shield constituting a low heat-flow province of ⩽45 mW m -2. Although only characterizing an area of about 300 km 2, this average is unlikely representing a positive local anomaly caused by voluminous HHP granites/rhyolites at shallow depths. Instead, a heat flow of 60 mW m -2 is considered a robust estimate of the Phanerozoic conductive surface heat flow not only for Jordan, but for the Arabian Shield in areas unaffected by younger reactivation. The large variation in conductive heat flow (36-88 mW m -2) previously observed in Jordan, southern Syria, and Saudi Arabia is irreconcilable with their broad similarity in lithosphere structure and composition and rather reflects a combination of factors including low-quality temperature data and insufficient knowledge on thermal rock properties.

  8. [The Arabian Peninsula: demographic surprises].

    PubMed

    Courbage, Y

    1994-01-01

    A review of current demographic trends in the countries of the Arabian Peninsula is presented, based on a number of recent surveys of child health carried out in the early 1990s. Considerable diversity is noted among the countries examined in both demographic trends and levels of socioeconomic development. However, the status of women appears to be more advanced throughout the region than in most other Muslim countries, which could indicate that a reduction in fertility is probable. The author notes a general decline in oil revenues, accompanied by a decline in fertility, throughout the region.

  9. Zoonoses in the Arabian Peninsula

    PubMed Central

    Wernery, Ulrich

    2014-01-01

    The human population is rising and will soon reach 9 billion people. In parallel, the demand for animal protein is increasing and with it is the threat of zoonotic diseases. We must therefore be on our guard. The close association of people with animals promotes the opportunity for zoonotic infections and real danger may arise when animals are imported with no health background. Therefore, it is essential to implement strict import controls, and establish efficient quarantine facilities. Many viral, bacterial, and zoonotic diseases have been diagnosed on the Arabian Peninsula, either by isolating the pathogens or through serological surveys. Most of them are briefly discussed in this paper. PMID:25491209

  10. Hypoxia in the central Arabian Gulf Exclusive Economic Zone (EEZ) of Qatar during summer season

    NASA Astrophysics Data System (ADS)

    Al-Ansari, Ebrahim M. A. S.; Rowe, G.; Abdel-Moati, M. A. R.; Yigiterhan, O.; Al-Maslamani, I.; Al-Yafei, M. A.; Al-Shaikh, I.; Upstill-Goddard, R.

    2015-06-01

    One of the most fascinating and unexpected discoveries during the Qatar University Marine Expeditions to the marine Exclusive Economic Zone (EEZ) of Qatar in 2000-2001, was the detection of a hypoxic water layer in the central region of the Arabian Gulf in waters deeper than 50 m. Hypoxia was defined as the region where the concentration of dissolved oxygen was less than 2 mg L-1. This article presents the discovery of hypoxia in the Arabian Gulf, based on samples collected (mainly during evening or night time) from vertical profiles along transects of the EEZ of Qatar and analyzed for physico-chemical properties, nutrients and chlorophyll-a. Hypoxia occurred in the summer months caused by an interaction between physical stratification of the water column that prevents oxygen replenishment, and biological respiration that consumes oxygen. Strong south-westerly winds (the SW monsoon) from June to September drive the relatively low-salinity nutrient-rich surface water from the Arabian Sea/Arabian Gulf (Sea of Oman) through the Strait of Hormuz into the central-Arabian Gulf, and this surface current penetration fertilizes the deep central-Arabian Gulf during the summer period. A strong seasonal pycnocline is formed between deeper waters at an ambient temperature of 20.9 °C and surface waters at 31.9 °C. This prevents the mixing of supersaturated O2 (>100-130%) water from the upper layer that would otherwise raise concentrations of dissolved oxygen below the thermocline, thus resulting in deep water hypoxia, i.e. dissolved oxygen levels of less than 0.86 ml L-1 at 17.3% saturation. These are the lowest values ever recorded for the Arabian Gulf. The calculated area of hypoxia is around 7220 square kilometers, and occurs in a layer about ≥15 m thick above the sea floor which extends toward the deep part of the Qatar Exclusive Economic Zone (EEZ). The biological consequences of this hypoxia on the sea floor are yet to be investigated.

  11. New heat flow measurements in Oman in the Arabian plate

    NASA Astrophysics Data System (ADS)

    Rolandone, F.; Lucazeau, F.; Jaupart, C.; Leroy, S.; Bache, F.; Amerjeed, M.; Lally, J.

    2009-04-01

    Precambrian shields are viewed as low heat flow provinces but detailed studies in Canada, South Africa and India shields demonstrate that large heat flow differences exist between them and within a single province, related to differences of crustal structures. Very few heat flow measurements are available on the Arabian shield and its thermal structure is poorly constrained. Heat flow reported for the Arabian Shield and its immediate platform (36-88 mWm-2) is broad. Thermal regime has a control on rheology and on deformation and the Arabian shield is of particular interest because it was affected by geodynamic processes such as the Red Sea and Gulf of Aden riftings starting around 30 Ma ago and the formation of the Dead Sea Transform fault starting at about 20 Ma. In December 2006, a marine heat-flow survey in the Gulf of Aden provided 169 new heat-flow measurements along multi-channel seismic profiles. One of the main results is that the high heat-flow (~120 mWm-2), characteristic of oceanic domains, extends into the deep continental margin and switches abruptly in the proximal margin to a low value (~40 mWm-2) typical of stable Precambrian domain. These low values have been confirmed by estimates derived from oil exploration data in few locations south of Oman. These data indicate a strong contrast of thermal regimes within the continental margin. Recent tomography studies on Arabia in Oman show that the lithosphere is significantly affected within Arabia in the vicinity of the Red Sea and the Gulf of Aden. This pattern is apparently different from the observed heat-flow pattern, which needs to be confirmed and extended into the Arabian platform. The survey we conducted in October 2008 was to evaluate the thermal regime in the onshore domains of Oman. We measured the temperature gradient in 9 water wells in Dhofar south of Oman and in 8 mining wells in northern Oman in the ophiolite belt. The goal is to investigate the thermal structure of the Arabian plate and

  12. Relationship between Curie isotherm surface and Moho discontinuity in the Arabian shield, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Aboud, Essam; Alotaibi, Abdulrahman M.; Saud, Ramzi

    2016-10-01

    The Arabian shield is a Precambrian complex of igneous and metamorphic rocks located approximately one-third of the way across the western Arabian Peninsula, with uncommon exposures along the Red Sea coast. We used aeromagnetic data acquired by others over the past several decades to estimate the depth to the Curie temperature isotherm throughout this region. Our goal was to further understand the lithospheric structure, thermal activity, and seismicity to assist in geothermal exploration. We also compared the Curie temperature isotherm with the crustal thickness to investigate the possibility that mantle rocks are magnetic in some parts of the Arabian shield. Depths to the Curie isotherm were estimated by dividing the regional aeromagnetic grid into 26 overlapping windows. Each window was then used to estimate the shape of the power spectrum. The windows had dimensions of 250 × 250 km to allow investigation of depths as deep as 50 km. The results show the presence of a Curie isotherm at a depth of 10-20 km near the Red Sea, increasing to 35-45 km in the interior of the Arabian shield. The Curie isotherm generally lies above the Moho in this region but deepens into the mantle in some locations, notably beneath the Asir Terrane.

  13. The thermal state of the Arabian plate derived from heat flow measurements in Oman and Yemen

    NASA Astrophysics Data System (ADS)

    Rolandone, Frederique; Lucazeau, Francis; Leroy, Sylvie; Mareschal, Jean-Claude; Jorand, Rachel; Goutorbe, Bruno; Bouquerel, Hélène

    2013-04-01

    The dynamics of the Afar plume and the rifting of the Red Sea and the Gulf of Aden affect the present-day thermal regime of the Arabian plate. However, the Arabian plate is a Precambrian shield covered on its eastern part by a Phanerozoic platform and its thermal regime, before the plume and rifting activities, should be similar to that of other Precambrian shields with a thick and stable lithosphere. The first heat flow measurements in the shield, in Saudi Arabia, yielded low values (35-44 mW/m2), similar to the typical shields values. Recent heat flow measurements in Jordan indicate higher values (56-66 mW/m2). As part of the YOCMAL project (YOung Conjugate MArgins Laboratory), we have conducted heat flow measurements in southern and northern Oman to obtain 10 new heat flux values in the eastern Arabian plate. We also derived 20 heat flux values in Yemen and Oman by processing thermal data from oil exploration wells. The surface heat flux in these different locations is uniformly low (45 mW/m2). The heat production in samples from the Dhofar and Socotra Precambrian basement is also low (0.7 µW/m3). Differences in heat flow between the eastern (60 mW/m2) and the western (45 mW/m2) parts of Arabia reflect differences in crustal heat production as well as a higher mantle heat flux in the west. We have calculated a steady state geotherm for the Arabian platform that intersects the isentropic temperature profile at a depth of about 150 km, consistent with the seismic observations. Seismic tomography studies of the mantle beneath Arabia also show this east-west contrast. Seismic studies have shown that the lithosphere is rather thin, 100 km or less below the shield and 150 km below the platform. The lithospheric thickness for the Arabian plate is 150 km, and the progressive thinning near the Red Sea, caused by the thermal erosion of the plume material, is too recent to be detected at the surface. The Afar plume mostly affects the base of the Arabian lithosphere along

  14. Distribution of oceanic and continental leads in the Arabian-Nubian Shield

    USGS Publications Warehouse

    Stacey, J.S.; Stoeser, D.B.

    1983-01-01

    New common lead data for feldspar, whole-rock, and galena samples from the Arabian-Nubian Shield, together with data from previous work, can be divided into two main groups. Group I leads have oceanic (mantle) characteristics, whereas group II leads have incorporated a continental-crustal component of at least early Proterozoic age. The group I leads are found in rocks from the Red Sea Hills of Egypt and the western and southern parts of the Arabian Shield. Group II leads are found in rocks from the northeastern and eastern parts of the Arabian Shield, as well as from the southeastern Shield near Najran. They are also found in rocks to the south in Yemen, to the east in Oman, and to the west at Aswan, Egypt. This distribution of data suggests that the Arabian-Nubian Shield has an oceanic core flanked by rocks that have developed, at least in part, from older continental material. Two mechanisms are suggested by which this older lead component could have been incorporated into the late Proterozoic rocks, and each may have operated in different parts of the Shield. The older lead component either was derived directly from an underlying early Proterozoic basement or was incorporated from subducted pelagic sediments or sediments derived from an adjacent continent. New U-Pb zircon data indicate the presence of an early Proterozoic basement southeast of Jabal Dahul in the eastern Arabian Shield. These data, together with 2,000-Ma-old zircons from the Al Amar fault zone, verify the implication of the common lead data that at least a part of the eastern Arabian Shield has an older continental basement. Because continental margins are particularly favorable locations for development of ore deposits, these findings may have important economic implications, particularly for tin, tungsten, and molybdenum exploration. ?? 1983 Springer-Verlag.

  15. Arabian peninsula: zone of ferment

    SciTech Connect

    Stookey, R.W.

    1984-01-01

    The Arabian Peninsula is an area which must be approached in terms of its own values and traditions. The different states, however, present difficulties for even the most well-informed policymaker because the region is not homogeneous. Some of the states are tenuous congeries of tribal and sectarian communities that do not necessarily share the aims of the ruling group. The authors of these six essays consider (1) the economic position of the states, (2) how oil exports affect the economies of the exporting states, (3) how traditional tribal and religious societies react to change, (4) whether their social values are conducive to modernization, and (5) what factors lead to the development of dissent, and how they affect the expression of dissent. Separate abstracts were prepared for two of the essays selected for the Energy Data Base (EDB) and Energy Abstracts for Policy Analysis (EAPA). 23 tables.

  16. Dysgerminoma in an Arabian filly.

    PubMed

    Chandra, A M; Woodard, J C; Merritt, A M

    1998-07-01

    A yearling Arabian filly was referred to the Veterinary Medical Teaching Hospital with a history of weight loss, profound anemia, and peritoneal effusion. At necropsy, a large, soft, mottled tan and red neoplastic mass was at the pelvic inlet replacing the left ovary. Additional tumor nodules of various sizes were disseminated throughout the mesentery, diaphragm, and serosal surfaces of the abdominal viscera. Histologically, the neoplasm had sheets of large round to polygonal cells separated into lobules by fibrous connective tissue with multifocal areas of necrosis. Tumor cells stained strongly for alkaline phosphatase. Immunohistochemically, tumor cells expressed vimentin and were negative for cytokeratin. Ultrastructurally, the neoplastic cells had a characteristic nucleolus with an elaborate reticular nucleolonema in an irregular configuration. This is the first in-depth detailed report of this very rare germ cell tumor of the ovary in horses.

  17. Cenozoic epeirogeny of the Arabian Peninsula from drainage modeling

    NASA Astrophysics Data System (ADS)

    Wilson, J. W. P.; Roberts, G. G.; Hoggard, M. J.; White, N. J.

    2014-10-01

    is generally accepted that the Arabian Peninsula has been uplifted by subcrustal processes. Positive residual depth anomalies from oceanic crust in the Red Sea and in the Gulf of Aden suggest that a region surrounding this peninsula is dynamically supported. Admittance calculations, surface wave tomography studies, and receiver function analyses all imply that regional topography is generated and maintained by some combination of mantle convective circulation and lithospheric thickness changes. Despite these significant advances, the spatial and temporal uplift rate history of the Arabian Peninsula is not well known. Here we show that a regional uplift rate history can be obtained by jointly inverting 225 longitudinal river profiles that drain this peninsula. Our strategy assumes that shapes of individual river profiles are controlled by uplift rate history and moderated by erosional processes. We used local measurements of incision rate to calibrate the relevant erosional parameters. In our inverse algorithm, uplift rate is permitted to vary smoothly as a function of space and time but upstream drainage area remains invariant. We also assume that knickzone migration is not lithologically controlled. Implications of these important assumptions have been investigated. Our results suggest that the Arabian Peninsula underwent two phases of asymmetric uplift during the last 20-30 Ma at rates of 0.05-0.1 mm a-1. The southwestern flank of the peninsula has been uplifted by 1.5-2.5 km. Regional stratigraphic constraints, the age and composition of volcanism, paleosol formation, incised peneplains, emergent marine terraces, and thermochronometric measurements corroborate our calculated patterns of uplift. Progressive development of three domal swells along the western margin of the peninsula is consistent with localized upwelling of hot asthenospheric mantle.

  18. Peste des petits ruminants in Arabian wildlife.

    PubMed

    Kinne, J; Kreutzer, R; Kreutzer, M; Wernery, U; Wohlsein, P

    2010-08-01

    Recurrence of peste des petits ruminants (PPR) was diagnosed in the United Arabian Emirates in several wild ruminants confirmed by morphological, immunohistochemical, serological and molecular findings. Phylogenetic analysis revealed that the virus strain belongs to lineage IV, which is different to some previously isolated PPR strains from the Arabian Peninsula. This study shows that wild ruminants may play an important epidemiological role as virus source for domestic small ruminants.

  19. Arabian Peninsula and northeast Africa as seen from Gemini 11 spacecraft

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Arabian Peninsula (on left) and northeast Africa (on right) as seen from the Gemini 11 spacecraft at an altitude of 340 nautical miles during its 27th revolution of the earth, looking southeast. Saudia Arabia, South Arabia, Yemen and Aden Protectorate are at left. At bottom right is Ethiopia. French Somaliland is in center on right shore. Somali is at upper right. Body of water at bottom is Red Sea. Gulf of Aden is in center; and at top left is Indian Ocean.

  20. Fate of oil hydrocarbons in fish and shrimp after major oil spills in the Arabian Gulf

    SciTech Connect

    Fayad, N.M.; El-Mubarak, A.H.; Edora, R.L.

    1996-03-01

    Pollution of the marine environment with crude oil represents one of the most serious environmental problems that confront Saudi Arabia and other Gulf states. Oil pollution in the Arabian Gulf environment may affect the inhabitants through (1) human health hazard resulting from the consumption of contaminated sea food, (2) loss of food due to alteration of species productivity or elimination of some species, and (3) deterioration of recreation areas. Moreover, the problem of oil spill may be more severe in this part of the world. This is mainly because the source of drinking water in various Gulf states depends largely on sea water from which desalinated water is produced. Contamination of sea water with crude oil may adversely affect the quality of desalinated water and may badly damage desalination plants. During the last twelve years, the Arabian Gulf has been affected by two major oil spills. The first spill occurred on February 4, 1983 during the Iraq-Iran War, and the second major oil spill occured during the 1991 Gulf War. There is limited information about the level of oil hydrocarbons in edible fish, but two studies were carried out after both spills. This paper summarized the results of both studies carried out to assess the extent of contamination of various fish species of commercial value from the Arabian Gulf with oil hydrocarbons.

  1. Tectonic and depositional model of the Arabian and adjoining plates during the Silurian-Devonian

    SciTech Connect

    Husseini, M.I. )

    1991-01-01

    During the Late Ordovician and Early Silurian, the western part of the Arabian Peninsula was covered by polar glaciers that advanced from the south pole in African Gondwana. During this period, nondeposition, erosion, or marginal marine conditions prevailed in eastern and northern Arabia. When the glaciers melted in the Early Silurian, sea level rose sharply and the paleo-Tethys Ocean transgressed the Arabian and adjoining plates depositing a thick, organic-rich shale directly over the glaciogenic and periglacial rocks and related unconformities. The post-glacial sequence coarsens upward reflecting the passage of a coastline prograding northward from African and Arabian Gondwana to northern Arabia. A sea level drop in the Late Silurian placed the study area in a terrestrial environment; however, as sea level recovered in the Early Devonian, a carbonate sequence blanketed most of the area. The transgression, however, was interrupted by regional uplift and local orogenic movements in the Middle and Late Devonian. These movements constitute the onset of Hercynian tectonism, which resulted in erosion of the older sequences, depositional hiatuses, and regional facies changes.

  2. Saudi Arabian seismic deep-refraction profiles; final project report

    USGS Publications Warehouse

    Healy, J.H.; Mooney, W.D.; Blank, H.R.; Gettings, M.E.; Kohler, W.M.; Lamson, R.J.; Leone, L.E.

    1983-01-01

    In February 1978 a seismic deep-refraction profile was recorded by the U.S. Geological Survey along a 1000-km line across the Arabian Shield in western Saudi Arabia. The line begins in Mesozoic cover rocks near Riyadh on the Arabian Platform, leads southwesterly across three major Precambrian tectonic provinces, traverses Cenozoic rocks of the coastal plain near Jizan (Tihamat-Asir), and terminates at the outer edge of the Farasan Bank in the southern Red Sea. More than 500 surveyed recording sites were occupied, including 19 in the Farasan Islands. Six shot points were used: five on land, with most charges placed below the water table in drill holes, and one at sea, with charges placed on the sea floor and detonated from a ship. Slightly more than 61 metric tons of explosives were used in 19 discrete firings. Seismic energy was recorded by 100 newly-developed portable seismic stations deployed in approximately 200 km-long arrays for each firing. Each station consisted of a standard 2-Hz vertical component geophone coupled to a self-contained analog recording instrument equipped with a magnetic-tape cassette. In this final report, we fully document the field and data-processing procedures and present the final seismogram data set as both a digital magnetic tape and as record sections for each shot point. Record sections include a normalized set of seismograms, reduced at 6 km/s, and a true-amplitude set, reduced at 8 km/s, which have been adjusted for amplifier gain, individual shot size, and distance from the shot point. Appendices give recorder station and shot information, digital data set descriptions, computer program listings, arrival times used in the interpretation, and a bibliography of reports published as a result of this project. We used two-dimensional ray-tracing techniques in the data analysis, and our interpretation is based primarily on horizontally layered models. The Arabian Shield is composed, to first-order, of two layers, each about 20 km

  3. The influence of extreme winds on coastal oceanography and its implications for coral population connectivity in the southern Arabian Gulf.

    PubMed

    Cavalcante, Geórgenes H; Feary, David A; Burt, John A

    2016-04-30

    Using long-term oceanographic surveys and a 3-D hydrodynamic model we show that localized peak winds (known as shamals) cause fluctuation in water current speed and direction, and substantial oscillations in sea-bottom salinity and temperature in the southern Persian/Arabian Gulf. Results also demonstrate that short-term shamal winds have substantial impacts on oceanographic processes along the southern Persian/Arabian Gulf coastline, resulting in formation of large-scale (52 km diameter) eddies extending from the coast of the United Arab Emirates (UAE) to areas near the off-shore islands of Iran. Such eddies likely play an important role in transporting larvae from well-developed reefs of the off-shore islands to the degraded reef systems of the southern Persian/Arabian Gulf, potentially maintaining genetic and ecological connectivity of these geographically distant populations and enabling enhanced recovery of degraded coral communities in the UAE.

  4. The influence of extreme winds on coastal oceanography and its implications for coral population connectivity in the southern Arabian Gulf.

    PubMed

    Cavalcante, Geórgenes H; Feary, David A; Burt, John A

    2016-04-30

    Using long-term oceanographic surveys and a 3-D hydrodynamic model we show that localized peak winds (known as shamals) cause fluctuation in water current speed and direction, and substantial oscillations in sea-bottom salinity and temperature in the southern Persian/Arabian Gulf. Results also demonstrate that short-term shamal winds have substantial impacts on oceanographic processes along the southern Persian/Arabian Gulf coastline, resulting in formation of large-scale (52 km diameter) eddies extending from the coast of the United Arab Emirates (UAE) to areas near the off-shore islands of Iran. Such eddies likely play an important role in transporting larvae from well-developed reefs of the off-shore islands to the degraded reef systems of the southern Persian/Arabian Gulf, potentially maintaining genetic and ecological connectivity of these geographically distant populations and enabling enhanced recovery of degraded coral communities in the UAE. PMID:26506023

  5. Quaternary coastal evolution of Oman (Arabian Peninsula) - a quantitative approach

    NASA Astrophysics Data System (ADS)

    Hoffmann, G.; Rupprechter, M.; Roepert, A.; Quraishi, K. Al; Balushi, N. Al; Grützner, C.; Reicherter, K.

    2012-04-01

    The paper reviews the Quaternary coastal evolution of Oman. Emphasise is put on quantifying the different forcing factors. The plate tectonic setting, the Quaternary climate evolution, the sea-level history and the impact of natural hazards are identified as key factors of coastal evolution. The Arabian Plate is characterized by a northward movement forming a continent-continent collision zone in the west and the Makran Subduction Zone in the east. As a result differential land movement is observable in Oman. The Quaternary climate evolution is well understood. Besides other proxies notably spelothems and aeolian deposits allow to draw a consistent picture. It is understood that changes in the position of the intertropical convergence zone result in intensity-changes of the summer monsoon. These changes are related to global atmospheric circulation patterns. Data on the sea-level history are sparse; despite general assumptions of a sea-level lowstand, correlating with the last glacial maximum, resulting in terrestrial conditions within the Arabian Gulf. Furthermore, a mid-Holocene sea level highstand in the range of +2m is documented in several locations. The coastlines of Oman are affected by tsunami and hurricanes. However, almost no instrumental or historical data on the impact of such natural hazards are available due to the isolation of the country in the past. Several Quaternary deposits have been investigated in a reconnaissance survey. There is sound geological evidence for a tsunami to have affected the coastline in 1945, with the possibility of older tsunami events being also recorded in the geological record. There is strong evidence of differential land movement along the coastline; locally indicated by marine terraces in elevations of up to 400m (Rupprechter at al. 2012). By quantifying the differential land movement for numerous sites, the sea-level history will be revealed. Ultimately the data will be utilized to form the base of a modeling approach

  6. Mitochondrial DNA structure in the Arabian Peninsula

    PubMed Central

    2008-01-01

    Background Two potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed. These are the two natural passageways that connect both continents: the northern route through the Sinai Peninsula and the southern route across the Bab al Mandab strait. Recent archaeological and genetic evidence have favored a unique southern coastal route. Under this scenario, the study of the population genetic structure of the Arabian Peninsula, the first step out of Africa, to search for primary genetic links between Africa and Eurasia, is crucial. The haploid and maternally inherited mitochondrial DNA (mtDNA) molecule has been the most used genetic marker to identify and to relate lineages with clear geographic origins, as the African Ls and the Eurasian M and N that have a common root with the Africans L3. Results To assess the role of the Arabian Peninsula in the southern route, we genetically analyzed 553 Saudi Arabs using partial (546) and complete mtDNA (7) sequencing, and compared the lineages obtained with those present in Africa, the Near East, central, east and southeast Asia and Australasia. The results showed that the Arabian Peninsula has received substantial gene flow from Africa (20%), detected by the presence of L, M1 and U6 lineages; that an 18% of the Arabian Peninsula lineages have a clear eastern provenance, mainly represented by U lineages; but also by Indian M lineages and rare M links with Central Asia, Indonesia and even Australia. However, the bulk (62%) of the Arabian lineages has a Northern source. Conclusion Although there is evidence of Neolithic and more recent expansions in the Arabian Peninsula, mainly detected by (preHV)1 and J1b lineages, the lack of primitive autochthonous M and N sequences, suggests that this area has been more a receptor of human migrations, including historic ones, from Africa, India, Indonesia and even Australia, than a demographic expansion center along the proposed southern coastal

  7. Comparison of Arabian plate motion using satellite laser ranging and GPS observations

    NASA Astrophysics Data System (ADS)

    Alothman, A. O.; Fernandes, R. M.; Schillak, S. R.

    2013-12-01

    Two different space based observations have been used to estimate the velocity of the Arabian plate motion. The first set of observations is using the Saudi Arabia Laser Ranging Observatory (SALRO - 7832), which is situated in the middle of Arabian tectonic plate. Satellite Laser Ranging (SLR) observations of about 20 global SLR stations to LAGEOS-1 and LAGEOS-2 satellites collected for 14 years (1996-2009) have been used to determine Riyadh SLR station positions. The NASA Godard's GEODYN-II orbital software has been used to perform orbit determination of these two satellites. The velocities of SALRO were computed in reference to the ITRF2008 terrestrial reference frame. The second set of observations consists of Global Positioning System (GPS) observations of 15 GPS stations acquired in campaign and continuous mode for the period 2003 to 2009 (having at least 3 years' data span). Multi-year processing of stations having at least 3 years' time span and excluding stations within the deformation zone of Red Sea Ridge, such that they are distributed evenly within the rigid (interior) part of the Arabian plate. The Bernese 5.0/ADNEQ2 and GIPSY/OASIS 6.1 software packages were used to compute the daily solutions of coordinate time series applying the Precise Point Positioning (PPP) strategy. The velocities were estimated with respect to ITRF2008 and four estimates of the angular velocities for the Arabian plate have been computed using different datasets: independent Bernese and GIPSY solutions, combination of the GPS solutions only, and including the SLR solution. We present direct comparison between all different solutions showing that the Arabian tectonic plate motion determined from Riyadh SLR data and GPS data are in a good agreement with recent estimates, in particular with the global geodetic model GEODVEL and the geophysical MORVEL model.

  8. Conservation in the Arabian Gulf countries

    SciTech Connect

    Akkad, A.A.

    1990-05-01

    In the Arabian Gulf region in general, and in Saudi Arabia in particular, demand for water in the agricultural, domestic, and industrial sectors has increased dramatically as a result of rapid development, and improved standard of living, and diversification of economic activity in agriculture and industry. This article presents an overview of supply and demand situations prevailing in the Arabian Gulf region and discusses various conventional and unconventional alternatives for meeting the growing demand for water. It also describes conservation measures and their socioeconomic effects.

  9. Sequential stratigraphy of Jurassic and Cretaceous in the central Saudi Arabian platform

    SciTech Connect

    Le Nindre, Y.M.; Manivit, J.; Vaslet, D. ); Manivit, H. Univ. Pierre et Marie Curie, Paris )

    1991-08-01

    Depositional sequences and system tracts in the Jurassic and Cretaceous sedimentary rocks of the Central Saudi Arabian platform have been established on the basis of precise lithofacies analysis, detailed sedimentologic interpretation, and accurate age determination by ammonites, nautoli, brachipods, echinoids, and nannoflora. A eustatic depositional model integrated with accepted worldwide sequential stratigraphic data is proposed, and appears to correlate fairly well with the 1988 global sea level chart by Haq and others, particularly for the Lower and Middle Jurassic and the Middle and Upper Cretaceous. Ages determined by accurate biostratigraphic data enable time correlations to be made with third-order eustatic cycles from Vail's 1988 global chart. Eustatic changes therefore appear to be the main factors of sedimentary control during the Jurassic and Cretaceous on the Arabian platform.

  10. Mandibular degloving injury in an Arabian filly.

    PubMed

    Tirosh-Levy, Sharon; Tatz, Amos; Kelmer, Gal

    2013-06-01

    A 6-month-old Arabian filly escaped its handler while being led and slipped on pavement. The referring veterinarian recognized severe, soft tissue damage to the filly's lower jaw and referred the filly to the Veterinary Teaching Hospital for surgical management.

  11. Tectonic synthesis of the northern Arabian platform

    SciTech Connect

    Everett, J.R.; Russell, O.R.; Stasxkowski, R.J.; Loyd, S.P.; Tabbutt, V.M. ); Dolan, P.; Stein, A. ); Scott, J. )

    1990-05-01

    The creation and destruction of Tethys oceans from the early Mesozoic to the present has created a complex suture zone along the Zagros/Bitlus trend. The fundamental interactions are between the Arabian and Euasian plates, but several microplates trapped between the major plates further complicate the tectonic fabric of the region. On the west, the Arabian plate slides past the African plate and the Sinai microplate along the Levant fault. The Palmyrides are related to a bend in this plate boundary and are not an offset extension of the Syrian arc. As Arabia penetrates Eurasia the Anatolian block is escaping to the west along the northern (right-lateral) and eastern (left-lateral) faults. Convergence of the Eurasian and Arabian plates resulted in ophiolite abduction (Late Cretaceous), followed by continent-continent collision (Miocene to present). The zone of collision is marked by the Bitlis-Zagrosa suture. Structural features associated with the collision include overthrusting, impactogens, and complexly folded and faulted mountain systems. Intensity and complexity of structuring decreases southward into open long-wavelength folds on the Arabian Platform. The fortuitous combination of rich source rocks, abundant reservoir rocks with primary and fracture porosity, and numerous trapping structures make this an extraordinary prolific hydrocarbon province. A structural and lithologic interpretation of 53 contiguous Landsat Multispectral Scanner scenes covering all of Syria, Iraq, and Kuwait, and portions of Turkey, Iran, Jordan, Lebanon, and Saudi Arabia has provided insights into the tectonic history of this area and its hydrocarbon accumulation.

  12. Mandibular degloving injury in an Arabian filly.

    PubMed

    Tirosh-Levy, Sharon; Tatz, Amos; Kelmer, Gal

    2013-06-01

    A 6-month-old Arabian filly escaped its handler while being led and slipped on pavement. The referring veterinarian recognized severe, soft tissue damage to the filly's lower jaw and referred the filly to the Veterinary Teaching Hospital for surgical management. PMID:24155453

  13. Saudi Arabian seismic-refraction profile: A traveltime interpretation of crustal and upper mantle structure

    USGS Publications Warehouse

    Mooney, W.D.; Gettings, M.E.; Blank, H.R.; Healy, J.H.

    1985-01-01

    The crustal and upper mantle compressional-wave velocity structure across the southwestern Arabian Shield has been investigated by a 1000-km-long seismic refraction profile. The profile begins in Mesozoic cover rocks near Riyadh on the Arabian Platform, trends southwesterly across three major Precambrian tectonic provinces, traverses Cenozoic rocks of the coastal plain near Jizan, and terminates at the outer edge of the Farasan Bank in the southern Red Sea. More than 500 surveyed recording sites were occupied, and six shot points were used, including one in the Red Sea. Two-dimensional ray-tracing techniques, used to analyze amplitude-normalized record sections indicate that the Arabian Shield is composed, to first order, of two layers, each about 20 km thick, with average velocities of about 6.3 km/s and 7.0 km/s, respectively. West of the Shield-Red Sea margin, the crust thins to a total thickness of less than 20 km, beyond which the Red Sea shelf and coastal plain are interpreted to be underlain by oceanic crust. A major crustal inhomogeneity at the northeast end of the profile probably represents the suture zone between two crustal blocks of different composition. Elsewhere along the profile, several high-velocity anomalies in the upper crust correlate with mapped gneiss domes, the most prominent of which is the Khamis Mushayt gneiss. Based on their velocities, these domes may constitute areas where lower crustal rocks have been raised some 20 km. Two intracrustal reflectors in the center of the Shield at 13 km depth probably represent the tops of mafic intrusives. The Mohorovic??ic?? discontinuity beneath the Shield varies from a depth of 43 km and mantle velocity of 8.2 km/s in the northeast to a depth of 38 km and mantle velocity of 8.0 km/s depth in the southwest near the Shield-Red Sea transition. Two velocity discontinuities occur in the upper mantle, at 59 and 70 km depth. The crustal and upper mantle velocity structure of the Arabian Shield is

  14. Saudi Arabian seismic-refraction profile: A traveltime interpretation of crustal and upper mantle structure

    NASA Astrophysics Data System (ADS)

    Mooney, W. D.; Gettings, M. E.; Blank, H. R.; Healy, J. H.

    1985-02-01

    The crustal and upper mantle compressional-wave velocity structure across the southwestern Arabian Shield has been investigated by a 1000-km-long seismic refraction profile. The profile begins in Mesozoic cover rocks near Riyadh on the Arabian Platform, trends southwesterly across three major Precambrian tectonic provinces, traverses Cenozoic rocks of the coastal plain near Jizan, and terminates at the outer edge of the Farasan Bank in the southern Red Sea. More than 500 surveyed recording sites were occupied, and six shot points were used, including one in the Red Sea. Two-dimensional ray-tracing techniques, used to analyze amplitude-normalized record sections indicate that the Arabian Shield is composed, to first order, of two layers, each about 20 km thick, with average velocities of about 6.3 km/s and 7.0 km/s, respectively. West of the Shield-Red Sea margin, the crust thins to a total thickness of less than 20 km, beyond which the Red Sea shelf and coastal plain are interpreted to be underlain by oceanic crust. A major crustal inhomogeneity at the northeast end of the profile probably represents the suture zone between two crustal blocks of different composition. Elsewhere along the profile, several high-velocity anomalies in the upper crust correlate with mapped gneiss domes, the most prominent of which is the Khamis Mushayt gneiss. Based on their velocities, these domes may constitute areas where lower crustal rocks have been raised some 20 km. Two intracrustal reflectors in the center of the Shield at 13 km depth probably represent the tops of mafic intrusives. The Mohorovičić discontinuity beneath the Shield varies from a depth of 43 km and mantle velocity of 8.2 km/s in the northeast to a depth of 38 km and mantle velocity of 8.0 km/s depth in the southwest near the Shield-Red Sea transition. Two velocity discontinuities occur in the upper mantle, at 59 and 70 km depth. The crustal and upper mantle velocity structure of the Arabian Shield is interpreted

  15. Supersequence and composite sequence carbonate platform growth: Permian and Triassic outcrop data of the Arabian platform and Neo-Tethys

    NASA Astrophysics Data System (ADS)

    Weidlich, O.; Bernecker, M.

    2003-05-01

    Permian and Triassic carbonate platforms of the Arabian Peninsula (Gondwana) and seamounts of the Neo-Tethys (Hawasina and Batain basins) are characterized by distinctive supersequences (second order, duration 5-20 million years, my) and composite sequences (third order, duration 0.5-5 my). The presented sequence stratigraphic framework will be compared with existing sea level curves to discuss the validity of different regional oscillations during the dispersal of Pangea. The carbonate succession of the Haushi and Akhdar Groups of the Arabian platform is composed of four Permian (P1-P4) and four Triassic supersequences (Tr1-Tr4). Isolated platforms of the Hawasina and Batain basins comprise two Permian supersequences and one Triassic supersequence. In contrast to the continuous development of the Arabian shield, carbonate platform growth of the seamounts was restricted to the Guadalupian-Lopingian and to the Middle-Upper Triassic, and ceased after drowning events. Composite sequences exhibit a well-developed stacking pattern during the Guadalupian-Lopingian (Saiq Formation). Lowstand systems tracts (LSTs) occur during the Cisuralian (Gharif Formation, Haushi Group) and Triassic (Mahil Formation, Akhdar Group). Open-marine depositional environments prevail during transgressive systems tracts (TSTs) with diverse biota including rugose and scleractinian corals, chaetetids, bryozoans, and crinoids. Highstand system tracts (HSTs) exhibit a twofold pattern: During the transgressive phase of supersequences, composite sequence highstands are dominated by reef or level-bottom communities with corals. Cyclic platform deposits or monotonous mud- and wackestone accumulated during the turnaround or late second-order highstand of a supersequence. Correlation of maximum flooding surfaces with published data suggests that supersequences P1, P2, and Tr4 can be traced across the Arabian platform into the Neo-Tethys basins, while supersequences P3, P4, and Tr1-Tr3 resulted from

  16. Climatic controls of the interannual to decadal variability in Saudi Arabian dust activity: Towards the development of a seasonal prediction tool

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Notaro, M.; Liu, Z.; Alkolibi, F.; Fadda, E.; Bakhrjy, F.

    2013-12-01

    Atmospheric dust significantly influences the climate system, as well as human life in Saudi Arabia. Skillful seasonal prediction of dust activity with climatic variables will help prevent some negative social impacts of dust storms. Yet, the climatic regulators on Saudi Arabian dust activity remain largely unaddressed. Remote sensing and station observations show consistent seasonal cycles in Saudi Arabian dust activity, which peaks in spring and summer. The climatic controls on springtime and summertime Saudi Arabian dust activity during 1975-2010 are studied using observational and reanalysis data. Empirical Orthogonal Function (EOF) of the observed Saudi Arabian dust storm frequency shows a dominant homogeneous pattern across the country, which has distinct interannual and decadal variations, as revealed by the power spectrum. Regression and correlation analyses reveal that Saudi Arabian dust activity is largely tied to precipitation on the Arabian Peninsula in spring and northwesterly (Shamal) wind in summer. On the seasonal-interannual time scale, warm El Niño-Southern Oscillation (ENSO) phase (El Niño) in winter-to-spring inhibits spring dust activity by increasing the precipitation over the Rub'al Khali Desert, a major dust source region on the southern Arabian Peninsula; warm ENSO and warm Indian Ocean Basin Mode (IOBM) in winter-to-spring favor less summer dust activity by producing anomalously low sea-level pressure over eastern north Africa and Arabian Peninsula, which leads to the reduced Shamal wind speed. The decadal variation in dust activity is likely associated with the Atlantic Multidecadal Oscillation (AMO), which impacts Sahel rainfall and North African dust, and likely dust transport to Saudi Arabia. The Pacific Decadal Oscillation (PDO) and tropical Indian Ocean SST also have influence on the decadal variation in Saudi Arabian dust activity, by altering precipitation over the Arabian Peninsula and summer Shamal wind speed. Using eastern

  17. Crustal Deformation at the Arabian Plate-Boundary observed by InSAR

    NASA Astrophysics Data System (ADS)

    Jonsson, S.; Cavalié, O.; Akoglu, A. M.; Wang, T.; Xu, W.; Feng, G.; Dutta, R.; Abdullin, A. K.

    2013-12-01

    The Arabian plate is bounded by a variety of active plate boundaries, with extension in the Red Sea and Gulf of Aden to the south, compression in Turkey and Iran to the north, and transform faults to the west and to the east. Internally, however, the Arabian plate has been shown to be tectonically rather stable, despite evidence of recent volcanism and earthquake faulting. We use InSAR observations to study recent tectonic and volcanic activity at several locations at the Arabian plate boundary as well within the plate itself. The region near the triple junction between the Arabian, Eurasian, and Anatolian plates has often been the focus of studies on continental deformation behavior and interseismic deformation. Here we use large-scale InSAR data processing to map the deformation near the triple junction and find the deformation to be focused on major faults with little intra-plate deformation. The eastern part of the East Anatolian Fault appears to have a very shallow locking depth with limited fault-normal deformation. Several major earthquakes that have occurred in recent years on the Arabian plate boundary, including the 2011 magnitude 7.1 Van earthquake in eastern Turkey. It occurred as a result of convergence of the Arabian plate towards Eurasia and caused significant surface deformation that we have analyzed with multiple coseismic InSAR, GPS, and coastal uplift observations. We use high-resolution Cosmo-Skymed and TerraSAR-X data to derive 3D coseismic displacements from offsets alone, as some of the interferograms are almost completely incoherent. By identifying point-like targets within the images, we were able to derive accurate pixel offsets between SAR sub-images containing such targets, which we used to estimate the 3D coseismic displacements. The derived 3D displacement field helped in constraining the causative northward dipping thrust-fault. The Qadimah fault is a recently discovered fault located on the Red Sea coast north of Jeddah and under the

  18. Acidification in Arabian Gulf--insights from pH and temperature measurements.

    PubMed

    Uddin, S; Gevao, B; Al-Ghadban, A N; Nithyanandan, M; Al-Shamroukh, D

    2012-05-01

    The detrimental effects of increasing atmospheric levels of carbon dioxide (CO(2)) and other greenhouse gases since the industrial revolution has led to a concerted international effort to control their release and abate the environmental and human health impacts. CO(2) is removed from the atmosphere by photosynthesis of plants in the terrestrial environment and by aquatic sequestration. In the Middle East and other arid countries, terrestrial removal is minimal. The most likely removal pathway for CO(2) in arid regions around the world is by aquatic sequestration. In the Middle East the major sink is the Arabian Gulf which leads to acidification of the marine environment. Biweekly pH concentration measurements in surface waters of the northern Arabian Gulf over a four year period in this study suggest that the Arabian Gulf waters are becoming increasingly acidic with time. Supporting evidence for increased CO(2) sequestration comes from increased marine primary productivity over the past decade. Biological effects, such as coral bleaching, observed during this period suggest that urgent action is required to reverse the trend and protect marine life. The data highlight the fact that this semi-enclosed sea is undergoing a rapid degradation which may affect the oceanic chemistry and biogeochemical cycle much earlier than predicted for most oceanic waters.

  19. Population genetics of four heavily exploited shark species around the Arabian Peninsula.

    PubMed

    Spaet, Julia L Y; Jabado, Rima W; Henderson, Aaron C; Moore, Alec B M; Berumen, Michael L

    2015-06-01

    The northwestern Indian Ocean harbors a number of larger marine vertebrate taxa that warrant the investigation of genetic population structure given remarkable spatial heterogeneity in biological characteristics such as distribution, behavior, and morphology. Here, we investigate the genetic population structure of four commercially exploited shark species with different biological characteristics (Carcharhinus limbatus, Carcharhinus sorrah, Rhizoprionodon acutus, and Sphyrna lewini) between the Red Sea and all other water bodies surrounding the Arabian Peninsula. To assess intraspecific patterns of connectivity, we constructed statistical parsimony networks among haplotypes and estimated (1) population structure; and (2) time of most recent population expansion, based on mitochondrial control region DNA and a total of 20 microsatellites. Our analysis indicates that, even in smaller, less vagile shark species, there are no contemporary barriers to gene flow across the study region, while historical events, for example, Pleistocene glacial cycles, may have affected connectivity in C. sorrah and R. acutus. A parsimony network analysis provided evidence that Arabian S. lewini may represent a population segment that is distinct from other known stocks in the Indian Ocean, raising a new layer of conservation concern. Our results call for urgent regional cooperation to ensure the sustainable exploitation of sharks in the Arabian region.

  20. Population genetics of four heavily exploited shark species around the Arabian Peninsula

    PubMed Central

    Spaet, Julia L Y; Jabado, Rima W; Henderson, Aaron C; Moore, Alec B M; Berumen, Michael L

    2015-01-01

    The northwestern Indian Ocean harbors a number of larger marine vertebrate taxa that warrant the investigation of genetic population structure given remarkable spatial heterogeneity in biological characteristics such as distribution, behavior, and morphology. Here, we investigate the genetic population structure of four commercially exploited shark species with different biological characteristics (Carcharhinus limbatus, Carcharhinus sorrah, Rhizoprionodon acutus, and Sphyrna lewini) between the Red Sea and all other water bodies surrounding the Arabian Peninsula. To assess intraspecific patterns of connectivity, we constructed statistical parsimony networks among haplotypes and estimated (1) population structure; and (2) time of most recent population expansion, based on mitochondrial control region DNA and a total of 20 microsatellites. Our analysis indicates that, even in smaller, less vagile shark species, there are no contemporary barriers to gene flow across the study region, while historical events, for example, Pleistocene glacial cycles, may have affected connectivity in C. sorrah and R. acutus. A parsimony network analysis provided evidence that Arabian S. lewini may represent a population segment that is distinct from other known stocks in the Indian Ocean, raising a new layer of conservation concern. Our results call for urgent regional cooperation to ensure the sustainable exploitation of sharks in the Arabian region. PMID:26120422

  1. Assessing the potential of Landsat 8 OLI for retrieving salinity in the hypersaline Arabian Gulf

    NASA Astrophysics Data System (ADS)

    Zhao, Jun; Temimi, Marouane

    2016-04-01

    The Arabian Gulf, located in an arid region in the Middle East, has high salinity that can exceed 43 practical salinity units (psu) due to its special conditions, such as high evaporation, low precipitation, and desalination discharge. In this study, a regional algorithm was developed to retrieve salinity using in situ measurements conducted between June 2013 and November 2014 along the western coast of Abu Dhabi, United Arab Emirates (UAE). A multivariate linear regression model using the visible bands of Operational Land Imager (OLI) was proposed and indicated good performance with a determination coefficient (R2) of 0.7. The algorithm was then applied to an OLI scene, which revealed the spatial distribution of salinity over the study area. The findings are favorable for better interpretation of the complex water mass exchange between the Arabian Gulf and the Sea of Oman through the Strait of Hormuz, validating salinity from numerical models, studying the effects of anthropogenic activities and climate change on ecosystem in the hypersaline Arabian Gulf, etc.

  2. Population genetics of four heavily exploited shark species around the Arabian Peninsula.

    PubMed

    Spaet, Julia L Y; Jabado, Rima W; Henderson, Aaron C; Moore, Alec B M; Berumen, Michael L

    2015-06-01

    The northwestern Indian Ocean harbors a number of larger marine vertebrate taxa that warrant the investigation of genetic population structure given remarkable spatial heterogeneity in biological characteristics such as distribution, behavior, and morphology. Here, we investigate the genetic population structure of four commercially exploited shark species with different biological characteristics (Carcharhinus limbatus, Carcharhinus sorrah, Rhizoprionodon acutus, and Sphyrna lewini) between the Red Sea and all other water bodies surrounding the Arabian Peninsula. To assess intraspecific patterns of connectivity, we constructed statistical parsimony networks among haplotypes and estimated (1) population structure; and (2) time of most recent population expansion, based on mitochondrial control region DNA and a total of 20 microsatellites. Our analysis indicates that, even in smaller, less vagile shark species, there are no contemporary barriers to gene flow across the study region, while historical events, for example, Pleistocene glacial cycles, may have affected connectivity in C. sorrah and R. acutus. A parsimony network analysis provided evidence that Arabian S. lewini may represent a population segment that is distinct from other known stocks in the Indian Ocean, raising a new layer of conservation concern. Our results call for urgent regional cooperation to ensure the sustainable exploitation of sharks in the Arabian region. PMID:26120422

  3. A comparative study of aerobic capacity and fitness in three different horse breeds (Andalusian, Arabian and Anglo-Arabian).

    PubMed

    Castejón, F; Rubio, D; Tovar, P; Vinuesa, M; Riber, C

    1994-11-01

    Aerobic capacity and fitness was studied in three different horse breeds (Andalusian, Arabian and Anglo-Arabian) using a four-level exercise test of gradually increasing intensity (15, 20, 25 and 30 km/h). The lactate concentration at the first three exercise levels was significantly lower for Arabian and Anglo-Arabian horses relative to Andalusian horses, but similar for the three breeds at the last level. Arabian and Anglo-Arabian horses reached a higher rate than Andalusian horses at plasma lactate concentration of 2 mmol/l (VLA2) and 4 mmol/l (VLA4). Andalusian horses exhibited a significantly lower heart rate at rest than the other two breeds, but the differences virtually disappeared at 15 km/h. At 20 km/h, Andalusian horses reached a higher heart rate than Arabian and Anglo-Arabian horses; at 25 km/h, however, their heart rate only exceeded that of Anglo-Arabian horses. Finally, no significant differences between breeds were observed at 30 km/h. No differences between breeds as regards heart rate were found if this was expressed as a function of lactate plasma concentrations of 2 mmol/l (HRLA2) and 4 mmol/l (HRLA4). At a heart rate of 150 (VHR150) and 200 beta/min (VHR200), Andalusian horses achieved the lowest speeds.

  4. Seasonal characteristics of the large-scale moisture flux transport over the Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Athar, H.; Ammar, K.

    2016-05-01

    The relationship between the lower tropospheric (1000 to 850 hPa) large-scale moisture flux transport and the precipitation over the Arabian Peninsula (AP), on a seasonal basis, using the NCEP-NCAR gridded dataset for the 53-year period (1958-2010), is investigated. The lower tropospheric moisture flux divergence occurs due to the Hadley cell-based descending air over the AP, as well as due to the presence of Somali jet in dry season (June to September) for the southern (≤22° N) AP domain, leading to significantly reduced precipitation in the AP. The AP thus acts more as a net transporter of moisture flux from adjacent Sea areas to nearby regions. The North Atlantic Oscillation (NAO) and the Artic Oscillation (AO) climatic indices are found to modulate significantly the net seasonal moisture flux into the AP region animating from the Mediterranean Sea, and the Arabian Sea, both for the northern (≥22° N) and southern AP domains.

  5. Molecular biodiversity of Red Sea demosponges.

    PubMed

    Erpenbeck, Dirk; Voigt, Oliver; Al-Aidaroos, Ali M; Berumen, Michael L; Büttner, Gabriele; Catania, Daniela; Guirguis, Adel Naguib; Paulay, Gustav; Schätzle, Simone; Wörheide, Gert

    2016-04-30

    Sponges are important constituents of coral reef ecosystems, including those around the Arabian Peninsula. Despite their importance, our knowledge on demosponge diversity in this area is insufficient to recognize, for example, faunal changes caused by anthropogenic disturbances. We here report the first assessment of demosponge molecular biodiversity from Arabia, with focus on the Saudi Arabian Red Sea, based on mitochondrial and nuclear ribosomal molecular markers gathered in the framework of the Sponge Barcoding Project. We use a rapid molecular screening approach on Arabian demosponge collections and analyze results in comparison against published material in terms of biodiversity. We use a variable region of 28S rDNA, applied for the first time in the assessment of demosponge molecular diversity. Our data constitutes a solid foundation for a future more comprehensive understanding of sponge biodiversity of the Red Sea and adjacent waters.

  6. Molecular biodiversity of Red Sea demosponges.

    PubMed

    Erpenbeck, Dirk; Voigt, Oliver; Al-Aidaroos, Ali M; Berumen, Michael L; Büttner, Gabriele; Catania, Daniela; Guirguis, Adel Naguib; Paulay, Gustav; Schätzle, Simone; Wörheide, Gert

    2016-04-30

    Sponges are important constituents of coral reef ecosystems, including those around the Arabian Peninsula. Despite their importance, our knowledge on demosponge diversity in this area is insufficient to recognize, for example, faunal changes caused by anthropogenic disturbances. We here report the first assessment of demosponge molecular biodiversity from Arabia, with focus on the Saudi Arabian Red Sea, based on mitochondrial and nuclear ribosomal molecular markers gathered in the framework of the Sponge Barcoding Project. We use a rapid molecular screening approach on Arabian demosponge collections and analyze results in comparison against published material in terms of biodiversity. We use a variable region of 28S rDNA, applied for the first time in the assessment of demosponge molecular diversity. Our data constitutes a solid foundation for a future more comprehensive understanding of sponge biodiversity of the Red Sea and adjacent waters. PMID:26776057

  7. Deposition Rates and Characterization of Arabian Mineral Dust

    NASA Astrophysics Data System (ADS)

    Puthan Purakkal, J.; Stenchikov, G. L.; Engelbrecht, J. P.

    2015-12-01

    Airborne mineral dust directly and indirectly impacts on global climate, continental and marine biochemistry, human and animal health, agriculture, equipment, and visibility. Annual global dust emissions are poorly known with estimates differing by a factor of at least two. Local dust emission and deposition rates are even less quantified. Dust deposition rate is a key parameter, which helps to constrain the modeled dust budget of the atmosphere. However, dust deposition remains poorly known, due to the limited number of reliable measurements. Simulations and satellite observations suggest that coastal dusts contribute substantially to the total deposition flux into the Red Sea. Starting December 2014, deposition samplers, both the "frisbee" type, and passive samplers for individual particle scanning electron microscopy were deployed at King Abdullah University of Science and Technology (KAUST), along the Red Sea in Saudi Arabia. Sampling periods of one month were adopted. The deposition rates range from 3 g m-2 month-1 for fair weather conditions to 23 g m-2 month-1 for high dust events. The X-ray diffraction (XRD) analyses of deposited dust samples show mineralogical compositions different from any of the parent soils, the former consisting mainly of gypsum, calcite, and smaller amounts of albite, montmorillonite, chlorite, quartz and biotite. The deposited dust samples on the other hand contain more gypsum and less quartz than the previously collected soil samples. This presentation discusses the results from XRD, chemical analysis and SEM-based individual particle analysis of the soils and the deposited dust samples. The monthly dust accumulation rates and their seasonal and spatial variability are compared with the regional model predictions. Data from this study provide an observational basis for validating the regional dust mass balance along the Arabian Red Sea coastal plain.

  8. Neotectonic Stress Analysis Of The Red Sea Rift By Finite Element Modeling

    NASA Astrophysics Data System (ADS)

    Dwivedi, S. K.; Hayashi, D.

    2006-12-01

    The Red Sea is a tectonic rift that was formed in the late Oligocene-early Miocene when the originally connected African and Arabian land masses broke apart. At first it was a continental rift, then, as Arabia drifted away, developed into an intercontinental system that today separates the independent Arabian plate from the African plate. The Red Sea rift is part of an extensive global system of faults running approximately north to south. In the present study, numerical modeling on the Saudi Arabian seismic reflection profile is carried out to examine the neotectonic stress field in the south western Red Sea-Arabian plate margin to reveal kinetics of active fault system using two-dimensional elastic finite element method under plane strain condition. The Mohr-Coulomb failure criterion has been adopted to analyze the relationship between stress distribution and fault formation. A Saudi Arabian reflection profile is adopted for the modeling and extensional displacement boundary condition is imposed along NE-SW direction. Our result shows the extensional displacement and physical properties of rock layer control the distribution, orientation, magnitude and intensity of the stress and fault development. According to the calculated stress patterns of failure elements, normal faults develop in the Red Sea and Arabian Plate margin. The results from our simulation are in good agreement with those of the seismicity, focal mechanism solution of earthquakes and active faulting in the Red Sea. Key words: Red Sea rift, numerical modeling, extension, neotectonics

  9. Climatic controls on the interannual to decadal variability in Saudi Arabian dust activity: Toward the development of a seasonal dust prediction model

    NASA Astrophysics Data System (ADS)

    Yu, Yan; Notaro, Michael; Liu, Zhengyu; Wang, Fuyao; Alkolibi, Fahad; Fadda, Eyad; Bakhrjy, Fawzieh

    2015-03-01

    The observed climatic controls on springtime and summertime Saudi Arabian dust activities during 1975-2012 are analyzed, leading to development of a seasonal dust prediction model. According to empirical orthogonal function analysis, dust storm frequency exhibits a dominantly homogeneous pattern across Saudi Arabia, with distinct interannual and decadal variability. The previously identified positive trend in remotely sensed aerosol optical depth since 2000 is shown to be a segment of the decadal oscillation in dust activity, according to long-duration station record. Regression and correlation analyses reveal that the interannual variability in Saudi Arabian dust storm frequency is regulated by springtime rainfall across the Arabian Peninsula and summertime Shamal wind intensity. The key drivers of Saudi Arabian dust storm variability are identified. Winter-to-spring La Niña enhances subsequent spring dust activity by decreasing rainfall across the country's primary dust source region, the Rub' al Khali Desert. A relatively cool tropical Indian Ocean favors frequent summer dust storms by producing an anomalously anticyclonic circulation over the central Arabian Peninsula, which enhances the Shamal wind. Decadal variability in Saudi Arabian dust storm frequency is associated with North African rainfall and Sahel vegetation, which regulate African dust emissions and transport to Saudi Arabia. Mediterranean sea surface temperatures (SSTs) also regulate decadal dust variability, likely through their influence on Sahel rainfall and Shamal intensity. Using antecedent-accumulated rainfall over the Arabian Peninsula and North Africa, and Mediterranean SSTs, as low-frequency predictors, and tropical eastern Pacific and tropical Indian Ocean SSTs as high-frequency predictors, Saudi Arabia's seasonal dust activity is well predicted.

  10. NASA Sees Heavy Rain in Arabian Sea Tropical Cyclone

    NASA Video Gallery

    On June 29, GPM showed Tropical Cyclone 02A had a few powerful convective thunderstorms southwest of the center of circulation were dropping rain at the extreme rate of over 209 mm (8.2 inches) per...

  11. The climatology of dust aerosol over the arabian peninsula

    NASA Astrophysics Data System (ADS)

    Shalaby, A.; Rappenglueck, B.; Eltahir, E. A. B.

    2015-01-01

    Dust storms are considered to be a natural hazard over the Arabian Peninsula, since they occur all year round with maximum intensity and frequency in Spring and Summer. The Regional Climate Model version 4 (RegCM4) has been used to study the climatology of atmospheric dust over the Arabian Peninsula from 1999 to 2012. This relatively long simulation period samples the meteorological conditions that determine the climatology of mineral dust aerosols over the Arabian Peninsula. The modeled Aerosol Optical Depth (AOD) has been compared against ground-based observations of three Aerosol Robotic Network (AERONET) stations that are distributed over the Arabian Peninsula and daily space based observations from the Multi-angle Imaging SpectroRadiometer (MISR), the Moderate resolution Imaging SpectroRadimeter (MODIS) and Ozone Monitoring Instrument (OMI). The large scale atmospheric circulation and the land surface response that lead to dust uplifting have been analyzed. While the modeled AOD shows that the dust season extends from March to August with two pronounced maxima, one over the northern Arabian Peninsula in March with AOD equal to 0.4 and one over the southern Arabian Peninsula in July with AOD equal to 0.7, the observations show that the dust season extends from April to August with two pronounced maxima, one over the northern Arabian Peninsula in April with AOD equal to 0.5 and one over the southern Arabian Peninsula in July with AOD equal to 0.5. In spring a high pressure dominates the Arabian Peninsula and is responsible for advecting dust from southern and western part of the Arabian Peninsula to northern and eastern part of the Peninsula. Also, fast developed cyclones in northern Arabian Peninsula are responsible for producing strong dust storms over Iraq and Kuwait. However, in summer the main driver of the surface dust emission is the strong northerly wind ("Shamal") that transport dust from the northern Arabian Peninsula toward south parallel to the

  12. Middle Tertiary continental rift and evolution of the Red Sea in southwestern Saudi Arabia

    USGS Publications Warehouse

    Schmidt, Dwight Lyman; Hadley, Donald G.; Brown, Glen F.

    1983-01-01

    Throughout early Tertiary time, the Arabian Shield erosion surface remained near sea level. First-stage uplift of the Red Sea Escarpment began during middle Miocene time, as evidenced by the coarse polymictic boulder conglomerate of the Bathan formation. Second-stage scarp uplift and second-stage sea-floor spreading followed during Pliocene, Pleistocene, and Holocene time.

  13. Data Collection in the Arabian Peninsula for Nuclear Explosion Monitoring

    SciTech Connect

    Rodgers, A; Tkalcic, H; Al-Amri, A M S

    2003-07-11

    We report results from the second year of our project (ROA0101-35) to collect seismic event and waveform data recorded in and around the Arabian Peninsula. This effort involves several elements. We have a temporary broadband seismic station operating near the IMS primary array site (PS38) in central Saudi Arabia. We recently installed two temporary broadband stations in the United Arab Emirates (funded by NNSA NA-24 Office of Non-Proliferation & International Security). We are working with King Abdulaziz city for Science and Technology to collect and analyze data from the Saudi National Seismic Network, that consist of 37 digital three-component stations (26 broadband and 11 short-period). We are collaborating with Kuwait Institute for Scientific Research (KISR) to analyze data from their 8 station national seismic network. We participated in the Workshop on Reference Events odnear the Dead Sea Rift held in Paris, France in October 2002. In this paper we present results of these efforts including integration of the raw data into LLNL's Seismic Research Database and preliminary analysis of event locations and source parameters and inference of earth structure.

  14. Stratigraphy and paleogeography of the Cretaceous in Arabian Peninsula

    SciTech Connect

    Alsharhan, A.S.; Nairn, A.E.M.

    1986-05-01

    The Cretaceous of the Arabian Peninsula is divided into three major units by regional unconformities: Lower Cretaceous Thamama Group (Berriasian-middle Aptian), middle Cretaceous Wasia Group (Albian-Turonian), and Upper Cretaceous Aruma Group (Coniacian-Maestrichtian). The profusion of named stratigraphic units in the area reflects not only the lithologic variation resulting from facies changes, but also terminologies adopted by different companies. The authors provide a stratigraphic nomenclature defining standard type sections and indicate synonymies, which follow the recommendation of 10th Geological Liaison Meeting and hence are acceptable to operators in the area. The sedimentologic history of the area was presented in a series of paleogeographic maps, which they relate to the regional tectonic framework. The maps show a predominantly carbonate shelf ramp bordering a land area to the north and west. The principal change in depositional environment occurs during the Upper Cretaceous, as a result of tectonic activity. Less significant changes are attributed to eustatic sea level fluctuations, on which tilting caused by tectonic movement may be superposed during the Lower and middle Cretaceous. The major producing horizons lie below the regional unconformities; secondary porosity in the shelf reefal buildups was developed during subaerial exposure in the Shuaiba Formation (early-middle Aptian), in the Mishrif Formation (late Cenomanian), and in the Simsima Formation (Maestrichtian).

  15. Probiotics in the Arabian Gulf Region

    PubMed Central

    Senok, Abiola C.

    2009-01-01

    Objective Available reports on adherence to recommended guidelines for labeling of probiotic products are based on assessment of these products in developed countries. In the Arabian Gulf region, there is a paucity of data on the characterization of probiotic products and an absence of local guidelines for their labeling. This study, carried out in the United Arab Emirates (UAE), represents the first evaluation of probiotic products available in the Arabian Peninsula. Methods Probiotic products were purchased over the counter from a variety of sources, including pharmacies, healthfood stores, and supermarkets across the UAE. All identified products were listed and information regarding type of product preparation and labeling information were recorded. Results A total of 37 probiotic products, 15 dairy-based and 22 non-dairy-based were identified. The dairy products comprised of 12 yogurts, two fermented milk products and one powdered baby formula. The majority of non-dairy products were in capsule form (n = 16). While all the non-dairy products gave information about the strain of probiotic microorganism and number present at time of manufacture, this information was provided for only one dairy-based product. Strains of Lactobacillus acidophilus were the most common probiotic organisms identified. However, one probiotic product listed Enterococcus faecalis (750 million viable bacteria per capsule) as a component. With the exception of one non-dairy-based product, all health-related claims were structure/function statements, according to the US Food and Drug Administration nomenclature. Conclusion These findings indicate that a wide variety of probiotic products are available in the Arabian Gulf. Development of guidelines for labeling of these probiotic products and use of structure/function statements and health claims should be addressed. PMID:19266044

  16. Arabian plate hydrocarbon geology and potential

    SciTech Connect

    Beydoun, Z.R.

    1991-01-01

    This book provides a thought-provoking, succinct presentation of the geologic evolution and hydrocarbon potential of the world's most prolific petroleum province. The fascinating subjects discussed and documented include: What are the unique geologic factors that make the Middle East such a prolific province Where are the future Mesozoic and Tertiary plays What is the virtually untapped potential of the Paleozoic section What are the play potentials for underexplored areas such as Jordan, Syria, Yemen How are deeper drilling results shaping and modifying concepts of the Arabian plate history and pointing the way to future hydrocarbon targets

  17. Interpretation of the data of USGS seismic refraction profile across the Arabian Shield in western Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Prodehl, C.

    Based on the record sections distributed a preliminary traveltime interpretation assuming horizontally flat layering is presented in the form of velocity-depth functions and a corresponding cross section of the lithosphere to a depth of 60 to 80 km across the Arabian Shield in western Saudi Arabia. The crust thickens abruptly from 15 km beneath the Red Sea Rift to about 40 km beneath the Arabian Shield. The upper crust of the western Arabian Shield yields relatively high-velocity material at about 10 km depth underlain by velocity inversions, while the upper crust of the eastern Shield is relatively uniform. The lower crust with a velocity of about 7 km/s is underlain by a transitional crust-mantle boundary. For the lower lithosphere beneath 40 km depth a laterally discontinuous lamellar structure may exist where high-velocity zones are mixed with zones of lower velocities. Beneath the crust-mantle boundary of the Red Sea Rift strong velocity inversions with velocities as low as 6.0 km/s may be encountered between 25 and 44 km depth. This model was prepared before the CCSS workshop. The model was tested using ray-tracing and amplitude studies and agreed well with observed traveltimes, except between shotpoints 5 and 6.

  18. Uppermost mantle Pn Velocity of the Arabian Plate, a Preliminary study

    NASA Astrophysics Data System (ADS)

    Al-Lazki, A. I.; Al-Damegh, K. S.; Al-Enizi, A.; Elhusain, I.; Al-Mahrooqi, I.

    2005-12-01

    The Arabian plate represents a unique tectonic setup. The uniqueness of this plate is its boundaries that constitute the three known types of plate boundaries. The Red Sea and the Gulf of Aden represent the south and southwest plate boundary with Africa plate. Farther north the Dead Sea Fault system represents the remainder of the northwestern boundary with Africa plate. Continent-continent collision along the Bitlis-Zagros Suture zones represents the northern and northeastern boundary with Eurasia plate. Farther south the convergent plate boundary is manifested by the Makran Subduction Zone. Finally, the Owen and Murray Transform Faults represent the southeast boundary of Arabia with India plate. The broad objective of this study is to map uppermost mantle Pn velocity and anisotropy within the Arabian plate and around its boundaries. Zones that are along the north and the northeast boundaries of Arabia plate historically and in recent years has been effected by devastating earthquakes, a recent example is the Bam earthquake on December, 2003. In this region, accurate earthquake location is essential to delineate seismically active zones, where, without proper velocity models for the region, located earthquake may have large location error. In this preliminary study we present uppermost mantle Pn velocity tomography results of the north and northeastern regions of Arabia plate. We used in this study Pn phase data from the bulletins of Oman Seismic Network, Saudi Seismic Network, Kuwait Seismic Network, International Seismological Center and the National Earthquake Information Center,USA.

  19. Assessment of arsenic in coastal sediments, seawaters and molluscs in the Tarut Island, Arabian Gulf, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    El-Sorogy, Abdelbaset S.; Youssef, Mohamed; Al-Kahtany, Khaled; Al-Otaiby, Naif

    2016-01-01

    In order to assess arsenic on the Tarut coast, Saudi Arabian Gulf, 38 sediment samples, 26 seawater samples and 40 gastropod and bivalve specimens were collected for analyses by Inductively Coupled Plasma-Mass Spectrometer. The Enrichment Factor (EF), the Geoaccumulation Index (Igeo) and the Contamination Factor (CF) indicated that coastal sediments of Tarut Island are severely enriched, strongly polluted and very highly contaminated with arsenic as a result of anthropogenic inputs. Comparison with arsenic in coastal sediments, seawaters and molluscs in the Red Sea, the Arabian Gulf and abroad coasts suggested that the studied samples have higher concentrations of As. The suggested natural sources of arsenic in the study area are the weathering and decomposition of neighboring deserts. The anthropogenic sources include the land reclamation, petrochemical industries, boat exhaust emissions, oil leakage, desalination plants and sewage effluents. These anthropogenic sources are the dominant sources of As in the study area and mostly came from Al Jubail industrial city to the north.

  20. Patterns of knee osteoarthritis in Arabian and American knees.

    PubMed

    Hodge, W Andrew; Harman, Melinda K; Banks, Scott A

    2009-04-01

    This study illustrates differences in the cartilage degeneration in osteoarthritic knees in patients with more frequent hyperflexion activities of daily living compared with Western patients. Proximal tibial articular cartilage wear and cruciate ligament condition were assessed in Saudi Arabian and North American patients with varus osteoarthritis undergoing total knee arthroplasty. In anterior cruciate ligament (ACL) intact knees, there were significant differences in wear location, with a clearly more anterior pattern in Saudi Arabian knees. Complete ACL deficiency occurred in 25% of North American knees but only 14% of Saudi Arabian knees. These ACL-deficient knees showed the most severe cartilage wear in both groups and posterior medial wear patterns. Biomechanical descriptions of knee flexion and axial rotation during kneeling or squatting are consistent with the more pronounced anteromedial and posterolateral cartilage wear patterns observed on the Saudi Arabian knees. These observations provide insight into altered knee mechanics in 2 culturally different populations with different demands on knee flexion.

  1. Environmental protection in the Arabian Gulf

    SciTech Connect

    Al-Minhali, A.A.N.

    1996-12-31

    The Arabian Gulf had been subjected to tremendous development activities in the past 40 years, this, in addition to two fierce wars which must have had some impact on the marine environment. This paper will investigate and summarize through review of numerous scientific studies, the recommended applied and or implemented strategies for conservation and how these may have an impact on the Offshore Oil and Gas Industry. The conclusions and recommendations made (in both, global terms and for oil and gas industry) primarily represent the author`s own views and in some parts acknowledged views of a number of professionals who were asked to contribute their vision on the future of protection of the Gulf marine environment. Whilst this paper is directed towards the Marine Environment, similar conclusions can be drawn for land and atmospheric issues.

  2. Carbon isotope stratigraphy of the upper Kharaib and Shuaiba formations: Implications for the Early Cretaceous evolution of the Arabian Gulf Region

    SciTech Connect

    Vahrenkamp, V.C.

    1996-05-01

    The carbon isotope profiles of shallow-marine carbonates from the Barremian-Aptian Kharaib and Shuaiba formations of the Arabian Gulf region range between 0.5 and 7{per_thousand} {delta}{sup 13}C PDB (Peedee belemnite). Systematic variations can be correlated with isotope profiles reported from Tethyan pelagic limestone sequences. The detailed correspondence between the isotopic signature of the relatively well-dated pelagic limestones and the poorly dated shallow-water limestones from the Arabian Gulf region suggests that global marine carbon isotope changes apparently affected deep-sea and shallow-water carbonate sediments similarly and at a similar time resolution. Although oxygen isotopes have been reset during diagenesis, carbon isotopes appear to have maintained their primary marine signature through time. No evidence has been found to connect carbon isotope trends to subaerial exposure or later meteoric diagenesis. In combination with other data, the investigated carbon isotope profiles can be used for basin-to-platform and regional correlations beyond the current resolution of biostratigraphy in shallow-water limestones. Carbon isotope stratigraphy confirms significant hiatuses in the investigated shallow-water carbonate sequences. Using carbon isotope trends as a proxy for sea level fluctuations, the carbon isotope cycles of the late Early Cretaceous of the Arabian Gulf region may represent four cycles of rising and falling sea level with a duration corresponding to that of third-order sea level fluctuations. Regional correlations derived from isotope trends provide a scenario for the larger scale stratigraphic evolution of the Arabian peninsula during the end of the Early Cretaceous.

  3. Rapid late Pleistocene/Holocene uplift and coastal evolution of the southern Arabian (Persian) Gulf

    NASA Astrophysics Data System (ADS)

    Wood, Warren W.; Bailey, Richard M.; Hampton, Brian A.; Kraemer, Thomas F.; Lu, Zhong; Clark, David W.; James, Rhodri H. R.; Al Ramadan, Khalid

    2012-03-01

    The coastline along the southern Arabian Gulf between Al Jubail, Kingdom of Saudi Arabia, and Dubai, UAE, appears to have risen at least 125 m in the last 18,000 years. Dating and topographic surveying of paleo-dunes (43-53 ka), paleo-marine terraces (17-30 ka), and paleo-marine shorelines (3.3-5.5 ka) document a rapid, > 1 mm/a subsidence, followed by a 6 mm/a uplift that is decreasing with time. The mechanism causing this movement remains elusive but may be related to the translation of the coastal area through the backbasin to forebulge hinge line movement of the Arabian plate or, alternatively, by movement of the underlying Infracambrian-age Hormuz salt in response to sea-level changes associated with continental glaciation. Independent of the mechanism, rapid and episodic uplift may impact the design of engineering projects such as nuclear power plants, airports, and artificial islands as well as the interpretation of sedimentation and archeology of the area.

  4. Study of some natural radionuclides near the Saudi coast of the Arabian Gulf

    NASA Astrophysics Data System (ADS)

    Al-Kheliewi, A. S.; Shabana, S. I.; Farouk, M. A.

    2012-06-01

    There is no authoritative study on marine radioactivity in the Arabian Gulf of Saudi Arabia nor is there any trusty measurements in the Red Sea's side of Saudi Arabia as well. Different surface sediment samples have been collected in three coastal areas from the the Saudi side of the Arabian Gulf‥ Those samples were collected at different depths varying from 5 to 25 meters, depending on the surface type and its geological composition, from 11 locations along the gulf coast. Activity concentrations of measured radionuclides 40K, 238U, 235U, 230Th, 226Ra, 232Th, 228Th, and 228Ra were: 23.69-253.3, 23.11 - 39.76, 1.05 - 1.65, 0.20 - 1.83, 1.99 - 9.46, 0.12 - 0.95, 0.11 - 1.15, 1.25 - 10.26 Bq/Kg respectivelty. All natural radionuclides measurements fall within the international accepted limits.

  5. Monitoring of oil pollution in the Arabian Gulf based on medium resolution satellite imagery

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Ghedira, H.

    2013-12-01

    A large number of inland and offshore oil fields are located in the Arabian Gulf where about 25% of the world's oil is produced by the countries surrounding the Arabian Gulf region. Almost all of this oil production is shipped by sea worldwide through the Strait of Hormuz making the region vulnerable to environmental and ecological threats that might arise from accidental or intentional oil spills. Remote sensing technologies have the unique capability to detect and monitor oil pollutions over large temporal and spatial scales. Synoptic satellite imaging can date back to 1972 when Landsat-1 was launched. Landsat satellite missions provide long time series of imagery with a spatial resolution of 30 m. MODIS sensors onboard NASA's Terra and Aqua satellites provide a wide and frequent coverage at medium spatial resolution, i.e. 250 m and 500, twice a day. In this study, the capability of medium resolution MODIS and Landsat data in detecting and monitoring oil pollutions in the Arabian Gulf was tested. Oil spills and slicks show negative or positive contrasts in satellite derived RGB images compared with surrounding clean waters depending on the solar/viewing geometry, oil thickness and evolution, etc. Oil-contaminated areas show different spectral characteristics compared with surrounding waters. Rayleigh-corrected reflectance at the seven medium resolution bands of MODIS is lower in oil affected areas. This is caused by high light absorption of oil slicks. 30-m Landsat image indicated the occurrence of oil spill on May 26 2000 in the Arabian Gulf. The oil spill showed positive contrast and lower temperature than surrounding areas. Floating algae index (FAI) images are also used to detect oil pollution. Oil-contaminated areas were found to have lower FAI values. To track the movement of oil slicks found on October 21 2007, ocean circulations from a HYCOM model were examined and demonstrated that the oil slicks were advected toward the coastal areas of United Arab

  6. Continental margin evolution of the northern Arabian platform in Syria

    SciTech Connect

    Best, J.A.; Barazangi, M. ); Al-Saad, D.; Sawaf, T.; Gebran, A. )

    1993-02-01

    Synthesis of available geological and geophysical data in the Syrian Arab Republic permits a descriptive account of the pre-Cenozoic geologic history of the northern Arabian platform. The northern Arabian platform appears to be a composite plate similar up to that interpreted in the rocks of the Arabian shield. The structural and stratigraphic relationships of the Paleozoic and Mesozoic sedimentary sections in Syria record the transformation of an eastward-facing Gondwana passive margin in the early Paleozoic into a westward-facing Levantine margin in the Mesozoic, at which time the northern platform was closely associated with the creation of the eastern Mediterranean basin. Timing of the margin transformation is inferred from the orientation and thickness variations of Lower Triassic rocks, but the transformation may have initiated as early as the Permian. The diversity and timing of geological features in Syria suggest that the northern Arabian platform did not behave as a rigid plate throughout its geological history. The present-day Palmyride mountain belt, located within the northern Arabian platform in Syria and initiated in the early Mesozoic as a northeast-trending rift nearly perpendicular to the Levantine margin, subsequently was inverted in the Cenozoic by transpression. The location of the rift may be associated with the reactivation of a zone of crustal weakness, i.e., a Proterozoic suture zone previously proposed from modeling of Bouguer gravity data. Thus, the northern and southern parts of the Arabian platform are similar in their respective geologic histories during the Proterozoic and Paleozoic; however, the northern Arabian platform was greatly affected by Mesozoic rifting and the creation of the eastern Mediterranean basin during the Mesozoic. 13 figs.

  7. Dynamics of sea level variations in the coastal Red Sea

    NASA Astrophysics Data System (ADS)

    Churchill, James; Abulnaja, Yasser; Nellayaputhenpeedika, Mohammedali; Limeburner, Richard; Lentz, Steven

    2016-04-01

    Sea level variations in the central Red Sea coastal zone span a range of roughly 1.2 m. Though relatively small, these water level changes can significantly impact the environment over the shallow reef tops prevalent in the central Red Sea, altering the water depth by a factor or two or more. While considerable scientific work has been directed at tidal and seasonal variations of Red Sea water level, very little attention has been given to elevation changes in an 'intermediate' frequency band, with periods of 2-30 d, even though motions in this band account for roughly half of the sea level variance in central Red Sea. We examined the sea level signal in this band using AVISO sea level anomaly (SLA) data, COARDAS wind data and measurements from pressure sensors maintained for more than five years at a number of locations in Saudi Arabian coastal waters. Empirical orthogonal function analysis of the SLA data indicates that longer-period (10-30 d) sea level variations in the intermediate band are dominated by coherent motions in a single mode that extends over most of the Red Sea axis. Idealized model results indicate that this large-scale mode of sea level motion is principally due to variations in the large-scale gradient of the along-axis wind. Our analysis indicates that coastal sea level motions at shorter periods (2-10 d) are principally generated by a combination of direct forcing by the local wind stress and forcing associated with large-scale wind stress gradients. However, also contributing to coastal sea level variations in the intermediate frequency band are mesoscale eddies, which are prevalent throughout the Red Sea basin, have a sea level signal of 10's of cm and produce relatively small-scale (order 50 km) changes in coastal sea level.

  8. Perspective View, Landsat Overlay, Salalah, Oman, Southern Arabian Peninsula

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This perspective view includes the city of Salalah, the second largest city in Oman. The city is located on the broad, generally bright coastal plain and includes areas of green irrigated crops. This view was generated from a Landsat image draped over a preliminary elevation model produced by the Shuttle Radar Topography Mission (SRTM). The edges of the dataset are to the upper right, left, and lower left. The Arabian Sea (lower right) is represented by the blue false-colored area. Vertical exaggeration of topography is 3X.

    This scene illustrates how topography determines local climate and, in turn, where people live. The Arabian Peninsula is very arid. However, the steep escarpment of the Qara Mountains wrings moisture from the summer monsoons allowing for growth of natural vegetation (green along the mountain fronts and in the canyons), and soil development (dark brown areas), as well as cultural development of the coastal plain. The monsoons also provide moisture for Frankincense trees growing on the desert (north) side of the mountains. In ancient times, incense derived from the sap of the Frankincense tree was the basis for an extremely lucrative trade.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot)spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was provided to the SRTM project by the United States Geological Survey, Earth Resources Observation Systems (EROS) Data Center,Sioux Falls, South Dakota.

    Elevation data used in this image was acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar(SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was

  9. Environmental assessment of coastal surface sediments at Tarut Island, Arabian Gulf (Saudi Arabia).

    PubMed

    Youssef, Mohamed; El-Sorogy, Abdelbaset; Al Kahtany, Khaled; Al Otiaby, Naif

    2015-07-15

    Thirty eight surface sediments samples have been collected in the area around Tarut Island, Saudi Arabian Gulf to determine the spatial distribution of metals, and to assess the magnitude of pollution. Total concentrations of Fe, Mn, As, B, Cd, Co, Cr, Cu, Hg, Mo, Pb, Se, and Zn in the sediments were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). Nature of sediments and heavy metals distribution reflect marked changes in lithology, biological activities in Tarut bay. Very high arsenic concentrations were reported in all studied locations from Tarut Island. The concentrations of Mercury are generally high comparing to the reported values from the Gulf of Oman, Red Sea. The concentrations of As and Hg exceeded the wet threshold safety values (MEC, PEC) indicating possible As and Hg contamination. Dredging and land filling, sewage, and oil pollution are the most important sources of pollution in the study area.

  10. Monitoring red tide with satellite imagery and numerical models: a case study in the Arabian Gulf.

    PubMed

    Zhao, Jun; Ghedira, Hosni

    2014-02-15

    A red tide event that occurred in August 2008 in the Arabian Gulf was monitored and assessed using satellite observations and numerical models. Satellite observations revealed the bloom extent and evolution from August 2008 to August 2009. Flow patterns of the bloom patch were confirmed by results from a HYCOM model. HYCOM data and satellite-derived sea surface temperature data further suggested that the bloom could have been initiated offshore and advected onshore by bottom Ekman layer. Analysis indicated that nutrient sources supporting the bloom included upwelling, Trichodesmium, and dust deposition while other potential sources of nutrient supply should also be considered. In order to monitor and detect red tide effectively and provide insights into its initiation and maintenance mechanisms, the integration of multiple platforms is required. The case study presented here demonstrated the benefit of combing satellite observations and numerical models for studying red tide outbreaks and dynamics.

  11. The gravity field and crustal structure of the northwestern Arabian Platform in Jordan

    NASA Astrophysics Data System (ADS)

    Batayneh, A. T.; Al-Zoubi, A. S.

    2001-01-01

    The Bouguer gravity field over the northwestern Arabian Platform in Jordan is dominated by large variations, ranging from -132 to +4 mGal. A study of the Bouguer anomaly map shows that the gravity field maintains a general north-northeasterly trend in the Wadi Araba-Dead Sea-Jordan Riff, Northern Highlands and Northeast Jordanian Limestone Area, while the remainder of the area shows north-northwesterly-trending gravity anomalies. Results of 2-D gravity modeling of the Bouguer gravity field indicate that the crustal thickness in Jordan is ˜ 38 km, which is similar to crustal thicknesses obtained from refraction data in northern Jordan and Saudi Arabia, and from gravity data in Syria.

  12. Environmental assessment of coastal surface sediments at Tarut Island, Arabian Gulf (Saudi Arabia).

    PubMed

    Youssef, Mohamed; El-Sorogy, Abdelbaset; Al Kahtany, Khaled; Al Otiaby, Naif

    2015-07-15

    Thirty eight surface sediments samples have been collected in the area around Tarut Island, Saudi Arabian Gulf to determine the spatial distribution of metals, and to assess the magnitude of pollution. Total concentrations of Fe, Mn, As, B, Cd, Co, Cr, Cu, Hg, Mo, Pb, Se, and Zn in the sediments were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). Nature of sediments and heavy metals distribution reflect marked changes in lithology, biological activities in Tarut bay. Very high arsenic concentrations were reported in all studied locations from Tarut Island. The concentrations of Mercury are generally high comparing to the reported values from the Gulf of Oman, Red Sea. The concentrations of As and Hg exceeded the wet threshold safety values (MEC, PEC) indicating possible As and Hg contamination. Dredging and land filling, sewage, and oil pollution are the most important sources of pollution in the study area. PMID:25963571

  13. Investigating Transition Zone Thickness Variation under the Arabian Plate: Evidence Lacking for Deep Mantle Upwellings

    NASA Astrophysics Data System (ADS)

    Juliá, J.; Tang, Z.; Mai, P. M.; Zahran, H.

    2014-12-01

    Cenozoic volcanic outcrops in Arabia - locally known as harrats - span more than 2000 km along the western half of the Arabian plate, from eastern Yemen to southern Syria. The magmatism is bimodal in character, with older volcanics (30 to 20 My) being tholeiitic-to-transitional and paralleling the Red Sea margin, and younger volcanics (12 Ma to Recent) being transitional-to-strongly-alkalic and aligning in a more north-south direction. The bimodal character has been attributed to a two-stage rifting process along the Red Sea, where the old volcanics would have produced from shallow sources related to an initial passive rifting stage, and young volcanics would have originated from one or more deep-seated mantle plumes driving present active rifting. Early models suggested the harrats would have resulted from either lateral flow from the Afar plume in Ethiopia, or more locally from a separate mantle plume directly located under the shield. Most recently, tomographic images of the Arabian mantle have suggested the northern harrats could be resulting from flow originating at a deep plume under Jordan. In this work, we investigate the location of deep mantle plumes under the Arabian plate by mapping transition zone thickness with teleseismic receiver functions. The transition zone is bounded by seismic discontinuities, nominally at 410 and 660 km depth, originating from phase transitions in the olivine-normative component of the mantle. The precise depth of the discontinuities is strongly dependent on temperature and, due to the opposing signs of the corresponding Clapeyron slopes, positive temperature anomalies are expected to result in thinning of the transition zone. Our dataset consists of ~5000 low-frequency (fc < 0.25 Hz) receiver function waveforms obtained at ~110 broadband stations belonging to a number of permanent and temporary seismic networks in the region. The receiver functions were migrated to depth and stacked along a ~2000 km long record section

  14. Change Detection Analysis of Costal Habitat Using Remote Sensing Technologies in the Western Arabian Gulf (Saudi Arabian Coast) over a Thirty-Year Period.

    NASA Astrophysics Data System (ADS)

    El-Askary, H. M.; Idris, N.; Johnson, S. H.; Qurban, M. A. B.

    2014-12-01

    Many factors can severely affect the growth and abundance of the marine ecosystems. For example, due to anthropogenic and natural forces, benthic habitats including but not limited to mangroves, sea grass, salt marshes, macro algae, and coral reefs have been experiencing high levels of declination. Furthermore, aerosols and their propellants are suspected contributors to marine habitat degradation. Although several studies reveal that the Arabian Gulf habitats have suffered deleterious impacts after the Gulf War and the following six month off-shore oil spill, limited research exists to track the changes in benthic habitats over the past three decades using remote sensing. Document changes in costal habitats over the past thirty years were better observed with the use of multispectral remote sensors such as Landsat-5, Landsat-7, and Landsat8 (OLI). Change detection analysis was performed on the three Landsat images (Landsat-5 for the 1987 image, Landsat-7 for the 2000, and Landsat-8 for the 2013 image). The images were then modified, masked off from open water and land. An unsupervised classification was performed which cluster similar classes together. The supervised classification displayed the seven following classes: coral reefs, macro algae, sea grass, salt marshes, mangroves, water, and land. Compared to 1987 image to 2000 scene, there was a noticeable increase in the extensiveness of salt marsh and macro algae habitats. However, a significant decrease in salt marsh habitats were apparent in the 2013 scene.

  15. Skin lipids from Saudi Arabian birds.

    PubMed

    Khan, Haseeb A; Arif, Ibrahim A; Williams, Joseph B; Champagne, Alex M; Shobrak, Mohammad

    2014-04-01

    Skin lipids play an important role in the regulation of cutaneous water loss (CWL). Earlier studies have shown that Saudi desert birds exhibit a tendency of reduced CWL than birds from temperate environment due to adaptive changes in composition of their skin lipids. In this study, we used thin-layer chromatography (TLC) for separation and detection of non-polar and polar lipids from the skin of six bird species including sooty gull, brown booby, house sparrow, Arabian waxbill, sand partridge, and laughing dove. The lipids were separated and detected on Silica gel G coated TLC plates and quantified by using densitometric image analysis. Rf values of the non-polar lipids were as follows: cholesterol (0.29), free fatty acids (0.58), triacylglycerol (0.69), fatty acids methyl esters (0.84) and cholesterol ester (0.97). Rf values for the polar lipids were: cerebroside (0.42), ceramide (0.55) and cholesterol (0.73). The results showed the abundance of fatty acids methyl esters (47.75-60.46%) followed by triacylglycerol (12.69-24.14%). The remaining lipid compositions were as follows: cholesterol (4.09-13.18%), ceramide (2.18-13.27%), and cerebroside (2.53-12.81%). In conclusion, our findings showed that TLC is a simple and sensitive method for the separation and quantification of skin lipids. We also reported a new protocol for lipid extraction using the zirconia beads for efficient disruption of skin tissues. This study will help us better understand the role of skin lipids in adaptive physiology towards adverse climatic conditions.

  16. Skin lipids from Saudi Arabian birds.

    PubMed

    Khan, Haseeb A; Arif, Ibrahim A; Williams, Joseph B; Champagne, Alex M; Shobrak, Mohammad

    2014-04-01

    Skin lipids play an important role in the regulation of cutaneous water loss (CWL). Earlier studies have shown that Saudi desert birds exhibit a tendency of reduced CWL than birds from temperate environment due to adaptive changes in composition of their skin lipids. In this study, we used thin-layer chromatography (TLC) for separation and detection of non-polar and polar lipids from the skin of six bird species including sooty gull, brown booby, house sparrow, Arabian waxbill, sand partridge, and laughing dove. The lipids were separated and detected on Silica gel G coated TLC plates and quantified by using densitometric image analysis. Rf values of the non-polar lipids were as follows: cholesterol (0.29), free fatty acids (0.58), triacylglycerol (0.69), fatty acids methyl esters (0.84) and cholesterol ester (0.97). Rf values for the polar lipids were: cerebroside (0.42), ceramide (0.55) and cholesterol (0.73). The results showed the abundance of fatty acids methyl esters (47.75-60.46%) followed by triacylglycerol (12.69-24.14%). The remaining lipid compositions were as follows: cholesterol (4.09-13.18%), ceramide (2.18-13.27%), and cerebroside (2.53-12.81%). In conclusion, our findings showed that TLC is a simple and sensitive method for the separation and quantification of skin lipids. We also reported a new protocol for lipid extraction using the zirconia beads for efficient disruption of skin tissues. This study will help us better understand the role of skin lipids in adaptive physiology towards adverse climatic conditions. PMID:24600311

  17. Skin lipids from Saudi Arabian birds

    PubMed Central

    Khan, Haseeb A.; Arif, Ibrahim A.; Williams, Joseph B.; Champagne, Alex M.; Shobrak, Mohammad

    2013-01-01

    Skin lipids play an important role in the regulation of cutaneous water loss (CWL). Earlier studies have shown that Saudi desert birds exhibit a tendency of reduced CWL than birds from temperate environment due to adaptive changes in composition of their skin lipids. In this study, we used thin-layer chromatography (TLC) for separation and detection of non-polar and polar lipids from the skin of six bird species including sooty gull, brown booby, house sparrow, Arabian waxbill, sand partridge, and laughing dove. The lipids were separated and detected on Silica gel G coated TLC plates and quantified by using densitometric image analysis. Rf values of the non-polar lipids were as follows: cholesterol (0.29), free fatty acids (0.58), triacylglycerol (0.69), fatty acids methyl esters (0.84) and cholesterol ester (0.97). Rf values for the polar lipids were: cerebroside (0.42), ceramide (0.55) and cholesterol (0.73). The results showed the abundance of fatty acids methyl esters (47.75–60.46%) followed by triacylglycerol (12.69–24.14%). The remaining lipid compositions were as follows: cholesterol (4.09–13.18%), ceramide (2.18–13.27%), and cerebroside (2.53–12.81%). In conclusion, our findings showed that TLC is a simple and sensitive method for the separation and quantification of skin lipids. We also reported a new protocol for lipid extraction using the zirconia beads for efficient disruption of skin tissues. This study will help us better understand the role of skin lipids in adaptive physiology towards adverse climatic conditions. PMID:24600311

  18. Breastfeeding patterns in the Arabian Gulf countries.

    PubMed

    Musaiger, A O

    1995-01-01

    The rapid economic change experienced in the Arab Gulf countries in the past two decades has resulted in a dramatic decline in the number of infants breast fed and the duration of breast feeding. This survey describes the current status of breast feeding in the Arabian Gulf countries in terms of the duration of exclusive breast feeding; initiation, frequency, and duration of breast feeding; bottle feeding practices; breast feeding and fertility; reasons for cessation of breast feeding; and the relationship between breast feeding and gastroenteritis. After a brief discussion of weaning practices, the paper considers factors influencing the decision to breast feed, including mothers age, education, urban-rural residence, and employment status; the influence of house maids and health workers; and the sex of the child. The marketing of baby foods in the area is described, as are various programs to support breast feeding, such as maternity protection, educational activities, marketing activities, support of appropriate weaning practices, workshops and seminars, and research activities. It is concluded that these programs have had very little effect on the promotion of breast feeding in the region for the following reasons: 1) lack of coordination; 2) lack of health regulations covering formulas and baby foods; 3) the encouragement of bottle feeding in private hospitals; 4) insufficient knowledge of managing breast feeding among health personnel; 5) a shortage of studies relating to breast feeding; and 6) insufficient training of health personnel. The institution of a global promotional policy is recommended. Such a policy would include the development of strict regulations covering marketing of substitutes, training of health workers, mass media campaigns, school and university curricula changes, and convincing policy-makers that breast feeding is beneficial.

  19. The Tetramorium squaminode species group (Hymenoptera, Formicidae) in the Arabian Peninsula, with a new record from the Kingdom of Saudi Arabia and keys to Arabian species

    PubMed Central

    Sharaf, Mostafa R.; Al Dhafer, Hathal M.; Aldawood, Abdulrahman S.

    2015-01-01

    Abstract The Arabian species of the Tetramorium squaminode-group are treated. Tetramorium squaminode Santschi, 1911 is recorded for the first time from the Kingdom of Saudi Arabia and the Arabian Peninsula. Keys to the two Arabian species of the Tetramorium squaminode-group, Tetramorium latinode Collingwood & Agosti, 1996 and Tetramorium squaminode, based on worker and queen castes, are given and a regional distribution map is provided. Notes on habitats of Tetramorium squaminode are presented. PMID:26019665

  20. Kinematic characteristics of Andalusian, Arabian and Anglo-Arabian horses: a comparative study.

    PubMed

    Cano, M R; Vivo, J; Miró, F; Morales, J L; Galisteo, A M

    2001-10-01

    The aim of this study was to compare the kinematic trot characteristics of three different breeds of horse: Andalusian (AN, n = 15), Arabian (AR, n = 7) and Anglo-Arabian (AA, n = 5) using standard computer-assisted videography (25 Hz). Linear, temporal and angular parameters in fore- and hind limbs were analysed in six randomly selected strides per horse. Normalised angle-time diagrams along the complete stride were obtained for all joints angles in each breed and specific kinematic characteristics were detected graphically. AA horses displayed longer swing durations in both limbs ans a shorter angular range of motion (ARM) in scapula and pelvis inclination and in shoulder, hip and forelimb retraction-protraction angles. At lift off, stifle and tarsal joint angles were more flexed. In general, only small differences were observed in AR horse kinematics when compared with the other 2 breeds. AN horses presented negative overtracking length, which was positive in AR and AA. In AN horses the elbow and carpal joints were more flexed at the moment of maximal elevation, elbow and fore-fetlock joints also exhibited a larger ARM due to a smaller angle at maximal flexion. In the hind limbs, tarsal, hind fetlock and retraction-protraction angles presented a larger ARM in AN horses due to greater maximal flexion in the tarsal and hind fetlock joints. Fore- and hind fetlocks were also more flexed in horses from this breed. In conclusion, differences between kinematic variables at the trot were observed in the three breeds studied here, mainly in forelimb joints. The most outstanding feature was the greater forelimb flexion recorded in AN horses than in the other breeds which is consistent with the elevated movements in this breed. In AA horses, the ARM of proximal joints involved in retraction protraction in both fore- and hind limbs was smaller. All the differences observed highlighted the idiosyncratic nature of the trot in each breed; this may influence the functional

  1. Selected Lexical Patterns in Saudi Arabian Sign Language

    ERIC Educational Resources Information Center

    Young, Lesa; Palmer, Jeffrey Levi; Reynolds, Wanette

    2012-01-01

    This combined paper will focus on the description of two selected lexical patterns in Saudi Arabian Sign Language (SASL): metaphor and metonymy in emotion-related signs (Young) and lexicalization patterns of objects and their derivational roots (Palmer and Reynolds). The over-arcing methodology used by both studies is detailed in Stephen and…

  2. "Going Mobile" in Business Communication at an Arabian Gulf University

    ERIC Educational Resources Information Center

    Rapanta, Chrysi; Nickerson, Catherine; Goby, Valerie Priscilla

    2014-01-01

    In this article, we describe a project in which undergraduate business seniors at a university in the Arabian Gulf created or evaluated the chapters of an iBook as part of their final course in business communication. Students were surveyed throughout the project, and they also participated in a focus group discussion at the end. The aim was to…

  3. On Selected Phonological Patterns in Saudi Arabian Sign Language

    ERIC Educational Resources Information Center

    Tomita, Nozomi; Kozak, Viola

    2012-01-01

    This paper focuses on two selected phonological patterns that appear unique to Saudi Arabian Sign Language (SASL). For both sections of this paper, the overall methodology is the same as that discussed in Stephen and Mathur (this volume), with some additional modifications tailored to the specific studies discussed here, which will be expanded…

  4. Academic Integrity and Oral Examination: An Arabian Gulf Perspective

    ERIC Educational Resources Information Center

    Thomas, Justin; Raynor, Monique; McKinnon, Merryn

    2014-01-01

    Academic dishonesty is a major challenge facing educational institutions worldwide. Within the context of undergraduate education in the Arabian Gulf, oral assessment can help validate the originality of student work, whilst simultaneously facilitating assessment in a mode highly resonant with the region's own educational traditions and…

  5. Observations on Word Order in Saudi Arabian Sign Language

    ERIC Educational Resources Information Center

    Sprenger, Kristen; Mathur, Gaurav

    2012-01-01

    This article focuses on the syntactic level of the grammar of Saudi Arabian Sign Language by exploring some word orders that occur in personal narratives in the language. Word order is one of the main ways in which languages indicate the main syntactic roles of subjects, verbs, and objects; others are verbal agreement and nominal case morphology.…

  6. Upper mantle structure under western Saudi Arabia from Rayleigh wave tomography and the origin of Cenozoic uplift and volcanism on the Arabian Shield

    SciTech Connect

    Park, Y; Nyblade, A; Rodgers, A; Al-Amri, A

    2007-11-09

    The shear velocity structure of the shallow upper mantle beneath the Arabian Shield has been modeled by inverting new Rayleigh wave phase velocity measurements between 45 and 140 s together with previously published Rayleigh wave group velocity measurement between 10 and 45 s. For measuring phase velocities, we applied a modified array method that minimizes the distortion of raypaths by lateral heterogeneity. The new shear velocity model shows a broad low velocity region in the lithospheric mantle across the Shield and a low velocity region at depths {ge} 150 km localized along the Red Sea coast and Makkah-Madinah-Nafud (MMN) volcanic line. The velocity reduction in the upper mantle corresponds to a temperature anomaly of {approx}250-330 K. These finding, in particular the region of continuous low velocities along the Red Sea and MMN volcanic line, do not support interpretations for the origin of the Cenozoic plateau uplift and volcanism on the Shield invoking two separate plumes. When combined with images of the 410 and 660 km discontinuities beneath the southern part of the Arabian Shield, body wave tomographic models, a S-wave polarization analysis, and SKS splitting results, our new model supports an interpretation invoking a thermal upwelling of warm mantle rock originating in the lower mantle under Africa that crosses through the transition zone beneath Ethiopia and moves to the north and northwest under the eastern margin of the Red Sea and the Arabian Shield. In this interpretation, the difference in mean elevation between the Platform and Shield can be attributed to isostatic uplift caused by heating of the lithospheric mantle under the Shield, with significantly higher region along the Red Sea possibly resulting from a combination of lithosphere thinning and dynamic uplift.

  7. Links between Synoptic Weather Types and Extreme Wet Events in the Arabian Peninsula (1960-2100)

    NASA Astrophysics Data System (ADS)

    Kenawy, Ahmed; McCabe, Matthew; Stenchikov, Georgiy; Raj, Jerry

    2014-05-01

    In this work, an automated version of the Lamb weather type classification scheme was applied to classify daily weather types in the Arabian Peninsula. The output catalogue included ten basic weather types, which describe the direction and vorticity of airflow in the peninsula (i.e., cyclonic, anticyclonic and directional). These large-scale patterns were first defined for the observed climate (1960-2013), allowing for an assessment of the spatial and temporal variations in circulation-rainfall relationships over the peninsula using rainfall data from 209 weather observatories. The same methodology was then applied to assess how the defined weather types will be presented in future climate simulations (under RCP45 and RCP85 emission scenarios) and to explore their probable dependency with rainfall characteristics. In this regard, daily simulated SLP derived from an ensemble of 12 climate models within the CMIP5 project were used for two future time-slices (2035-2060 and 2075-2100). Our findings indicate that the cyclonic (C) type represented the most frequent classification with 69.2% of days, followed by SE directional flows (21%). It was also found that the main circulation features influencing winter (spring) rainfall across the peninsula are the strong influence of the anticyclonic (easterly and southeasterly) air masses. Generally, the role of airflows originating from the Indian Ocean is larger than those of the Mediterranean and the Red Seas. The trend results of defined weather types show that the cyclonic (anticyclonic) conditions tend to decrease (increase). This picture is likely to continue during the 21st century. The only exception corresponds to the summer season. Here, understanding the association between atmospheric circulation patterns and rainfall in the Arabian Peninsula can be important for the understanding of climatic variability and thus developing circulation-based downscaling methods in this region.

  8. Major events in the late Precambrian to early Triassic geohistory of the Arabian Peninsula

    SciTech Connect

    Stump, T.E.; Connally, T.C.; Van der Eem, J.G.L.A. )

    1993-09-01

    The late Precambrian to Early Triassic of the Arabian Peninsula occur in five supergroups. Their geohistory resulted from sedimentation along fluvial to midshelf facies tracts, eustatic oscillation and periodic uplift. The first supergroup, Plate Precambrian-Middle Cambrian, includes the Siq/Salib and Yatib formations. Deposited by north-eastward-flowing braided streams, they eroded and buried an Arabian shield topography. The Saq Formation lies in angular unconformity on the Siq which documents early Middle Cambrian uplift. Supergroup two, Middle Cambrian-middle Caradocian, the Burj and Saq formations, the Hanadir, Kahfah, and Ra'an members, Qasim Formation, were deposited on a stable continental margin in fluvio-deltaic to midshelf settings. Coastal onlap occurred in the Middle Cambrian, early Llanvirn, middle Llandeilo and early Caradoc. Middle Caradocian uplift deeply eroded parts of central and southern Arabia. Supergroup three of middle Caradocian-early Llandoverian are the Quwarah Member, Qasim Formation and the Zarqa/Sarah formations. They were deposited in a fluvio-deltaic shallow shelf. Late Ashgill uplift, combined with glacially induced sea level lowering, incised valleys up to 2000 ft (610 m) deep. Supergroup four, early Llandovery-Middle Carboniferous, includes the Qalibah, Tawil, Jauf, Jubah and Berwath formations. They were deposited in a fluvio-deltaic marine, river dominated system. The Quysaiba and Sharawra members, Qalibah Formation, were the offshore clays and prodelta sands, the Tawil-Jubah were the fluvial to delta front, and the Berwath the delta plain facies. Deep pre-Tawil erosion documents late Silurian-Early Devonian uplift. The fifth supergroup are the Juwayl, Unayzah, Khuff and Sudair formations. The first two units were deposited in a glacio-fluvial system which eroded and infilled a Hercynian topography. The Khuff transgression occurred during the Artinsklan-Tartarian and the Early Triassic regressive Sudair documents renewed uplift.

  9. Early cretaceous platform-margin configuration and evolution in the central Oman mountains, Arabian peninsula

    SciTech Connect

    Pratt, B.R. ); Smewing, J.D. )

    1993-02-01

    The Hajar Supergroup (Middle Permian-Lower Cretaceous) of northeastern Oman records rifting and development of a passive margin along the edge of the Arabian platform facing Neo-Tethys. The Jurassic and Lower Cretaceous part, comprising the Sahtan, Kahmah, and Wasia groups, was deposited during the maximum extent of the broad epicontinental sea landward of this margin. These limestone units reach a total of 1500 m in thickness and correlate with the hydrocarbon reservoirs of the Arabian Peninsula. The trace of the Jurassic and Cretaceous margin in northeastern Oman followed a zigzag series of rift segments, resulting in promontories and reentrants that changed in position through time in response to the configuration and differential motion of underlying rift blocks. Synsedimentary normal faulting occurred locally in the Middle Jurassic, whereas in the Late Jurassic, the margin was eroded from variable uplift of up to 300 m before subsiding to below storm wave base. This uplift may have been caused by compression from oceanic crust that obducted along the southeastern side of the platform. The Lower Cretaceous succession in the central Oman Mountains and adjacent subsurface began with regional drowning around the Jurassic-Cretaceous boundary. The succession in the east (Saih Hatat) records a single regressive sequence, ending in the progradation of the shallow-water carbonate platform by the Cenomanian. However, the succession in the west (Jebel Akhdar and interior) is dominated by shallow-water carbonate facies, but punctuated by a second regional drowning in the late Aptian. A third, Late Cretaceous drowning terminated deposition of the Wasia Group in the Turonian and was caused by convergence of oceanic crust and foreland basic formation. The record of tectonic behavior of carbonate platforms has important implications for the development of hydrocarbon source rocks and porosity. 68 refs., 11 figs., 1 tab.

  10. Microsatellite analysis of genetic diversity and population structure of Arabian horse populations.

    PubMed

    Khanshour, Anas; Conant, Eleanore; Juras, Rytis; Cothran, Ernest Gus

    2013-01-01

    The Arabian horse ignites imagination throughout the world. Populations of this breed exist in many countries, and recent genetic work has examined the diversity and ancestry of a few of these populations in isolation. Here, we explore 7 different populations of Arabians represented by 682 horses. Three of these are Middle Eastern populations from near the historical origin of the breed, including Syrian, Persian, and Saudi Arabian. The remaining Western populations are found in Europe (the Shagya Arabian and Polish Arabian) and in America (American Arabian). Analysis of genetic structure was carried out using 15 microsatellite loci. Genetic distances, analysis of molecular variance, factorial correspondence analysis, and a Bayesian method were applied. The results consistently show higher level of diversity within the Middle Eastern populations than the Western populations. The Western Arabian populations were the main source among population variation. Genetic differentiation was not strong among all Middle Eastern populations, but all American Arabians showed differentiation from Middle Eastern populations and were somewhat uniform among themselves. Here, we explore the diversities of many different populations of Arabian horses and find that populations not from the Middle East have noticeably lower levels of diversity, which may adversely affect the health of these populations.

  11. Microsatellite analysis of genetic diversity and population structure of Arabian horse populations.

    PubMed

    Khanshour, Anas; Conant, Eleanore; Juras, Rytis; Cothran, Ernest Gus

    2013-01-01

    The Arabian horse ignites imagination throughout the world. Populations of this breed exist in many countries, and recent genetic work has examined the diversity and ancestry of a few of these populations in isolation. Here, we explore 7 different populations of Arabians represented by 682 horses. Three of these are Middle Eastern populations from near the historical origin of the breed, including Syrian, Persian, and Saudi Arabian. The remaining Western populations are found in Europe (the Shagya Arabian and Polish Arabian) and in America (American Arabian). Analysis of genetic structure was carried out using 15 microsatellite loci. Genetic distances, analysis of molecular variance, factorial correspondence analysis, and a Bayesian method were applied. The results consistently show higher level of diversity within the Middle Eastern populations than the Western populations. The Western Arabian populations were the main source among population variation. Genetic differentiation was not strong among all Middle Eastern populations, but all American Arabians showed differentiation from Middle Eastern populations and were somewhat uniform among themselves. Here, we explore the diversities of many different populations of Arabian horses and find that populations not from the Middle East have noticeably lower levels of diversity, which may adversely affect the health of these populations. PMID:23450090

  12. Polynuclear aromatic hydrocarbons (PAHs) in fish from the Arabian Gulf

    SciTech Connect

    DouAbdul, A.A.Z.; Abaychi, J.K.; Al-Edanee, T.E.; Ghani, A.A.; Al-Saad, H.T.

    1987-03-01

    Emphasis has been placed upon the identification and qualification of compounds with potential adverse health effects on humans. Prominent among this group are polynuclear aromatic hydrocarbons (PAHs), several of which are known or suspected carcinogens. PAHs enter the marine environment from a variety of sources including petroleum pollution, industrial and domestic effluents, atmospheric particles, and biosynthesis by plants and microorganisms. Although one-third of the world's oil is produced around the Arabian Gulf, no detailed analysis have been conducted to determine PAHs in this region. Nevertheless, numerous investigations have shown the ability of marine organisms including fish to accumulation PAHs from solution or dispersion in seawater. When fish are harvested, a human health hazard may result. In the present communication, high performance liquid chromatography (HPLC) was used to identify and measure sixteen PAHs priority pollutants issued by US Environmental Protection Agency (EPA) in fourteen species of commercially significant fish from the NW Arabian Gulf.

  13. Continuous quality improvement. A proposal for Arabian Gulf Medical Associations.

    PubMed

    Al-Shahri, M Z; Kinchin-White, J

    2000-02-01

    Having well-established and active medical associations in the Arabian Gulf countries is a promising event. Ideally, however, it must be assured that these associations are efficiently and effectively functioning in a manner designed to serve the ultimate goal of promoting the standards of the medical profession and thus, the quality of health care in the region. This paper is designed to promote the application of Continuous Quality Improvement principles by the medical associations in the Arabian Gulf. The paper is presented in a general format so as to allow for appropriate modifications according to the specific objectives of different medical associations. The indicators identified in this proposal to assess the quality of structure, process or outcome are not intended as a comprehensive list. Rather, the authors aim at establishing a framework on which various fine-tuned and appropriately tailored systems can be based.

  14. Pelger-Huët anomaly in an Arabian horse.

    PubMed

    Grondin, Tanya M; DeWitt, Shane F; Keeton, Kerry S

    2007-09-01

    A 9-year-old Arabian mare was evaluated for a 7-day history of malaise. Results of a CBC included a leukocyte concentration within the reference interval (8.4 x 10(3)/microL, reference interval 6.0-14.0 x 10(3)/microL) with an apparent degenerative left shift (segmented neutrophils 1.2 x 10(3)/microL, reference interval 2.5-7.5 x 10(3)/microL; hyposegmented neutrophils 1.8 x 10(3)/microL, reference interval 0.0-0.2 x 10(3)/microL). Serum clinical chemistry results included increased aspartate transaminase, alkaline phosphatase, and gamma-glutamyltransferase activities. A presumptive diagnosis of hepatitis or cholangiohepatitis was made. The horse was treated with antimicrobials and the malaise quickly resolved. However, in a recheck CBC on day 13, the apparent degenerative left shift remained. Further evaluation of the blood smear revealed many hyposegmented granulocytes with coarse mature chromatin and normal cytoplasmic features. On the basis of the microscopic examination, the horse was diagnosed with Pelger-Huët anomaly. The patient's offspring was subsequently also diagnosed with Pelger-Huët anomaly on the basis of blood film examination. Neutrophil, eosinophil, and basophil mean nuclear scores in both affected horses (mare, range 1.5-2.6; offspring, range 1.6-3.2) were lower than those in 2 unrelated Arabian horses (range, 2.8-5.0) and 5 non-Arabian control horses (range, 2.8-5.0). Results of immunophenotyping and phagocytosis/oxidative burst assays via flow cytometry showed no difference in the expression of myeloid-specific or adhesion molecules or in neutrophil function between affected and control horses. This is the second known report of equine Pelger-Huët anomaly, both of which affected Arabian horses.

  15. Multiscale Local Forcing of the Arabian Desert Daytime Boundary Layer, and Implications for the Dispersion of Surface-Released Contaminants.

    NASA Astrophysics Data System (ADS)

    Warner, Thomas T.; Sheu, Rong-Shyang

    2000-05-01

    Four 6-day simulations of the atmospheric conditions over the Arabian Desert during the time of the 1991 detonation and release of toxic material at the Khamisiyah, Iraq, weapons depot were performed using a mesoscale model run in a data-assimilation mode. These atmospheric simulations are being employed in a forensic analysis of the potential contribution of the toxic material to so-called Gulf War illness. The transport and concentration of such surface-released contaminants are related strongly to the planetary boundary layer (PBL) depth and the horizontal wind speed in the PBL. The product of the PBL depth and the mean wind speed within it is referred to as the ventilation and is used as a metric of the horizontal transport within the PBL. Thus, a corollary study to the larger forensic analysis involves employing the model solutions and available data in an analysis of the multiscale spatial variability of the daytime desert PBL depth and ventilation as they are affected by surface forcing from terrain elevation variations, coastal circulations, and contrasts in surface physical properties.The coarsest computational grid spanned the entire northern Arabian Desert and surrounding areas of the Middle East, and represented the large-scale PBL modulation by the orography. The PBL depths were greatest over the high elevations of the western Arabian Peninsula and over the Zagros Mountains in western Iran and were shallowest over water bodies and the lower elevations in the Tigris-Euphrates Valley. Higher-resolution grids in the nest (the smallest grid increment was 3.3 km) showed that the PBL depth minimum in the Tigris-Euphrates Valley was likely a consequence of compensating subsidence associated with the thermally forced daytime upward motion over the Zagros Mountains to the east in Iran, with possible contributions from an elevated mixed layer. Further local modulation of the daytime desert PBL occurred as a result of the inland penetration of the coastal sea

  16. Multiple sclerosis in the Arabian Gulf countries: a consensus statement.

    PubMed

    Bohlega, Saeed; Inshasi, Jihad; Al Tahan, Abdel Rahman; Madani, Abu Bakr; Qahtani, Hussien; Rieckmann, Peter

    2013-12-01

    The epidemiology of multiple sclerosis (MS) is rapidly changing in many parts of the world. Based on the Kurtzke classification, the Arabian Gulf Region is located in a low-risk zone for MS; however, recent studies suggest a moderate-to-high prevalence nearby (31-55 MS per 10,0000 individuals), with an increase in incidence in recent years. The relapsing-remitting disease course ratio is 2.5:1 versus the primary progressive type. In a geographic area that was previously associated with low prevalence; the recent high prevalence and fast rising incidence of MS in the gulf countries, encouraged the neurologists of this region to meet in a consensus panel, in order to share our latest findings in terms of MS epidemiology and consent on MS management in the Arabian Gulf. Therefore 20 key opinion leader neurologists and MS experts representing various countries of the Arabian Gulf have met in Dubai on the 2 and 3 February 2012, they shared their latest epidemiological findings, discussed recent MS aspects in the region, and consented on MS management relevantly to this geographic area.

  17. Guidelines to classification and nomenclature of Arabian felsic plutonic rocks

    USGS Publications Warehouse

    Ramsay, C.R.; Stoeser, D.B.; Drysdall, A.R.

    1986-01-01

    Well-defined procedures for classifying the felsic plutonic rocks of the Arabian Shield on the basis of petrographic, chemical and lithostratigraphic criteria and mineral-resource potential have been adopted and developed in the Saudi Arabian Deputy Ministry for Mineral Resources over the past decade. A number of problems with conventional classification schemes have been identified and resolved; others, notably those arising from difficulties in identifying precise mineral compositions, continue to present difficulties. The petrographic nomenclature used is essentially that recommended by the International Union of Geological Sciences. Problems that have arisen include the definition of: (1) rocks with sodic, zoned or perthitic feldspar, (2) trondhjemites, and (3) alkali granites. Chemical classification has been largely based on relative molar amounts of alumina, lime and alkalis, and the use of conventional variation diagrams, but pilot studies utilizing univariate and multivariate statistical techniques have been made. The classification used in Saudi Arabia for stratigraphic purposes is a hierarchy of formation-rank units, suites and super-suites as defined in the Saudi Arabian stratigraphic code. For genetic and petrological studies, a grouping as 'associations' of similar and genetically related lithologies is commonly used. In order to indicate mineral-resource potential, the felsic plutons are classed as common, precursor, specialized or mineralized, in order of increasing exploration significance. ?? 1986.

  18. Paleomagnetism and 40Ar / 39Ar Geochronology of Yemeni Oligocene volcanics: Implications for timing and duration of Afro-Arabian traps and geometry of the Oligocene paleomagnetic field

    NASA Astrophysics Data System (ADS)

    Riisager, Peter; Knight, Kim B.; Baker, Joel A.; Ukstins Peate, Ingrid; Al-Kadasi, Mohamed; Al-Subbary, Abdulkarim; Renne, Paul R.

    2005-09-01

    A combined paleomagnetic and 40Ar / 39Ar study was carried out along eight stratigraphically overlapping sections in the Oligocene Afro-Arabian flood volcanic province in Yemen (73 sites). The composite section covers the entire volcanic stratigraphy in the sampling region and represents five polarity zones that are correlated to the geomagnetic polarity time scale based on 40Ar / 39Ar ages from this and previous studies. The resulting magnetostratigraphy is similar to that of the conjugate margin in Ethiopia. The earliest basaltic volcanism took place in a reverse polarity chron that appears to correspond to C11r, while the massive rhyolitic ignimbrite eruptions correlated to ash layers in Oligocene Indian Ocean sediment 2700 km away from the Afro-Arabian traps, appear to have taken place during magnetochron C11n. The youngest ignimbrite was emplaced during magnetochron C9n. Both 40Ar / 39Ar and paleomagnetic data suggest rapid < 1 Ma eruption of the basal basalt units and punctuated eruption of the upper silicic units over a duration potentially as long as 3 Ma with interspersed eruptive hiatuses. Eruption of the basal basalts may have preceded the Oi2 cooling event. The paleomagnetic pole λ = 74.2°N, φ = 249.1°E (A95 = 3.6°; N = 48) is supported by a positive reversal test. Paleosecular variation, estimated as the angular standard deviation of the VGP distribution 14.2° + 2.3° / - 1.7°, is close to expected, suggesting that the paleomagnetic pole represents a time-averaged field. The pole is in excellent accord with the paleomagnetic poles obtained from the Ethiopian part of the Afro-Arabian province, after closure of the Red Sea. By analyzing Afro-Arabian paleomagnetic data in conjunction with contemporaneous paleomagnetic poles available from different latitudes we argue that the Oligocene paleomagnetic field was dominated by the axial dipole with insignificant non-dipole field contributions.

  19. Estimation of Dust Emission from the Western Coastal Plains of Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Anisimov, Anatolii; Stenchikov, Georgiy

    2016-04-01

    This study is aimed at quantifying local-scale dust emission from the coastal areas of western Arabian Peninsula. The dust emitted from these areas is frequently deposited directly to the Red Sea, acting as an important component of the nutrient balance of marine ecosystems. Most chemicals including iron, phosphorus, and nitrogen are introduced to the Red Sea with airborne dust. This process is especially significant for the oligotrophic northern Red Sea, where nutrients from the Indian Ocean cannot reach and the nutrient supply from land river discharge is negligible. The dust deposition to the Red Sea associated with major dust storms was recently estimated to be about 6 Tg/yr, but this estimate does not account for local, small-scale dust outbreaks occurring during fair weather conditions or moderate winds. The seasonality and the magnitude of this nutrient supply are largely unknown. In the present study, we quantify dust emissions using the fine-scale off-line version-4 of the Community Land Model (CLM4) with the high-resolution datasets as input parameters. We examine the model sensitivity to the spatial resolution of input land cover and vegetation data, and compare the results with weather station observations and reanalysis to choose the best model configuration. The model results are shown to be in reasonable agreement with station visibility measurements and the frequency of dust event reports. To improve the spatial characteristics of dust emission, we apply two state-of-the-art dust source functions. We found that the source function based on measurements from SEVIRI satellite substantially improves the simulation results, being in good agreement with both reanalysis data and station measurements. We identify the major dust source hot-spot areas over the coastal plain and analyze the seasonal and diurnal variability of dust emissions. The annual dust generation from the 145000 km2 coastal area reaches 6 Tg/yr. Roughly half of emitted dust could be

  20. Assessment of heavy metal contamination in intertidal gastropod and bivalve shells from central Arabian Gulf coastline, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    El-Sorogy, Abdelbaset S.; Youssef, Mohamed

    2015-11-01

    In order to assess pollutants and impact of environmental changes along the Saudi Arabian Gulf coast, forty specimens of gastropod and bivalve shells belonging to Diodora funiculata, Lunella coronata, Cerithium caeruleum, Barbatia parva, Pinctada margaritifera, Amiantis umbonella, Acrosterigma assimile and Asaphis violascens from five localities are selected for Fe, Cu, Pb, Mn, Cd, Se, As, Co, B, Cr, Hg, Mo analysis. The analysis indicated that heavy metal values (except Fe) were less than those recorded in molluscan shells from Gulf of Oman, Red Sea and Indian Ocean. D. funiculate, L. coronata, B. parva and P. margaritifera are good accumulators of Cu, As, Cr. The other species gave a nearly constant concentration in all the studied areas. Al Jubail coast recorded the highest heavy metal concentrations (except Mn at Ras Al-Ghar and Se at Al Jubail industrial city). Heavy metal contamination is mostly attributed to anthropogenic sources, especially effluents from petrochemical industries, sewage and desalination plants.

  1. Three new species of Pararhabdepyris Gorbatovsky (Hymenoptera, Bethylidae) from Central Africa and the Arabian Peninsula.

    PubMed

    Vargas, Juan M; Azevedo, Celso O

    2016-06-01

    Three new species of Pararhabdepyris are described and illustrated: P. arabo sp. nov. (United Arabian Emirates and Yemen), P. wafrika sp. nov. (Central African Republic), P. ngangu sp. nov. (Central African Republic). The genus is recorded for the first time from the Saharo-Arabian region. A key for all species of the genus is presented.

  2. Three new species of Pararhabdepyris Gorbatovsky (Hymenoptera, Bethylidae) from Central Africa and the Arabian Peninsula.

    PubMed

    Vargas, Juan M; Azevedo, Celso O

    2016-01-01

    Three new species of Pararhabdepyris are described and illustrated: P. arabo sp. nov. (United Arabian Emirates and Yemen), P. wafrika sp. nov. (Central African Republic), P. ngangu sp. nov. (Central African Republic). The genus is recorded for the first time from the Saharo-Arabian region. A key for all species of the genus is presented. PMID:27395185

  3. The Dead Sea

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Dead Sea is the lowest point on Earth at 418 meters below sea level, and also one of the saltiest bodies of water on Earth with a salinity of about 300 parts-per-thousand (nine times greater than ocean salinity). It is located on the border between Jordan and Israel, and is fed by the Jordan River. The Dead Sea is located in the Dead Sea Rift, formed as a result of the Arabian tectonic plate moving northward away from the African Plate. The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride. In the early part of the 20th century, the Dead Sea began to attract interest from chemists who deduced that the Sea was a natural deposit of potash and bromine. From the Dead Sea brine, Israel and Jordan produce 3.8 million tons potash, 200,000 tons elemental bromine, 45,000 tons caustic soda, 25, 000 tons magnesium metal, and sodium chloride. Both countries use extensive salt evaporation pans that have essentially diked the entire southern end of the Dead Sea.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop

  4. Assessment of atmospheric correction models for ocean color applications through dusty atmospheres: Case of the Arabian Gulf

    NASA Astrophysics Data System (ADS)

    Ben Romdhane, H.; Zhao, J.; Ghedira, H.

    2013-12-01

    More than 90% of the signal measured by an ocean colour satellite sensor over the ocean is due to the confounding influence of the atmosphere. 0.5% error in atmospheric correction corresponds to possible of ~5% error in the derived ocean water-leaving radiance. The standard atmospheric correction scheme, referred to as black-pixel assumption, assumes that water-leaving radiance in the near-infrared part of the spectrum is negligible. It works well for clear open ocean waters. However, it induces significant errors when applied to the turbid coastal waters. In the region of the Arabian Gulf and the Gulf of Oman, satellite derived imagery is largely contaminated by the effects of atmospheric dust, which poses major challenges to researchers. Multi-temporal images have been and are being collected over the Arabian Gulf and the Gulf of Oman (including the littoral waters) via digital multispectral imaging systems. These synoptic remotely sensed data could be used for different applications, such as water quality monitoring, study of climate change. In order to maximise the utility of these multi-temporal remotely sensed data, accurate radiometric correction, atmospheric and water-column correction procedures are needed. Studies were conducted in the Arabian Gulf and the Gulf of Oman with the ultimate aim of deriving appropriate algorithms for the retrieval of true surface reflectance from Aqua/MODIS and VIIRS data. Rigorous atmospheric corrections using SeaDAS (V7.0) and 6S (V1) models coupled with the inputs of AERONET data and AVHRR satellite derived atmospheric products were carried out to derive the remote sensing reflectance (Rrs). Satellite-derived Rrs were compared with concurrent in situ measurements. Good correlations were observed between satellite-derived and in situ measurements for all models. The results from the two mentioned models showed good performance of SeaDAS and 6S. Our findings indicate that MODIS and VIIRS data are suitable for water quality

  5. Regional joint sets in the Arabian platform as indicators of intraplate processes

    SciTech Connect

    Hancock, P.L.; Sha'At, N.A.; Al Kadhi, A.

    1984-02-01

    The eastern part of the Saudi Arabian craton is a platform underlain by gently tilted and horizontal Mesozoic-Cenozoic sedimentary rocks. The platform contains several laterally extensive, but subdued, structures and lineaments. New microtectonic observations of dominant sets of extension and conjugate hybrid joints permit regionally significant extension directions to be inferred and the origin of the macrostructures to be assessed. The central Arabian arch developed during the Late Cretaceous to Eocene when the basin inverted as a consequence of the emplacement of ophiolite-bearing nappes on the Zagros and Oman margins. During arching, there was strike-parallel elongation of beds. At the same time as the arch amplified, the central Arabian graben system evolved as a result of the northward displacement of an East Arabian block. An important Neogene response in the Arabian platform to northeast-southwest shortening in the Zagros ranges was the formation of a swarm of northeast-striking master joints and lineaments. 41 references.

  6. Geodynamic and Magmatic Evolution of the Eastern Anatolian-Arabian Collision Zone, Turkey

    NASA Astrophysics Data System (ADS)

    Keskin, Mehmet

    2014-05-01

    The Eastern Anatolian-Arabian Collision Zone represents a crucial site within the Tethyan domain where a subduction system involving a volcanic arc (i.e. Cretaceous to Oligocene Pontide volcanic arc in the north) associated with a large subduction-accretion complex (i.e. Cretaceous to Oligocene Eastern Anatolian Accretionary Complex i.e. "EAAC" in the south) turned later into a major continental collision zone that experienced a series of geodynamic events including lithospheric delamination, slab-steepening & breakoff, regional domal uplift, widespread volcanism and tectonic escape via strike slip fault systems. The region includes some of the largest volcanic centers (e.g. Karacadaǧ, Aǧırkaya caldera, Ararat, Nemrut, Tendürek and Süphan volcanoes) and plateaus (e.g. The Erzurum-Kars Plateau) as well as the largest transform fault zones in the Mediterranean region. A recent geodynamic modeling study (Faccenna et al., 2013) has suggested that both the closure of the Tethys Ocean and the resultant collision were driven by a large scale and northerly directed asthenospheric mantle flow named the "Tethyan convection cell". This convection cell initiated around 25 Ma by combined effects of mantle upwelling of the Afar super plume located in the south, around 3,000 km away from the collision zone and the slab-pull of the Tethyan oceanic lithosphere beneath Anatolia in the north. The aforementioned mantle flow dragged Arabia to the north towards Eastern Anatolia with an average velocity of 2 cm/y for the last 20 My, twice as fast as the convergence of the African continent (i.e. 1 cm/y) with western and Central Turkey. This 1 cm/y difference resulted in the formation of the left lateral Dead Sea Strike Slip Fault between the African and Arabian plates. Not only did this mantle flow result in the formation of a positive dynamic topography in the west of Arabian block, but also created a dynamic tilting toward the Persian Gulf (Faccenna et al., 2013). Another

  7. The Arabian Cradle: Mitochondrial Relicts of the First Steps along the Southern Route out of Africa

    PubMed Central

    Fernandes, Verónica; Alshamali, Farida; Alves, Marco; Costa, Marta D.; Pereira, Joana B.; Silva, Nuno M.; Cherni, Lotfi; Harich, Nourdin; Cerny, Viktor; Soares, Pedro; Richards, Martin B.; Pereira, Luísa

    2012-01-01

    A major unanswered question regarding the dispersal of modern humans around the world concerns the geographical site of the first human steps outside of Africa. The “southern coastal route” model predicts that the early stages of the dispersal took place when people crossed the Red Sea to southern Arabia, but genetic evidence has hitherto been tenuous. We have addressed this question by analyzing the three minor west-Eurasian haplogroups, N1, N2, and X. These lineages branch directly from the first non-African founder node, the root of haplogroup N, and coalesce to the time of the first successful movement of modern humans out of Africa, ∼60 thousand years (ka) ago. We sequenced complete mtDNA genomes from 85 Southwest Asian samples carrying these haplogroups and compared them with a database of 300 European examples. The results show that these minor haplogroups have a relict distribution that suggests an ancient ancestry within the Arabian Peninsula, and they most likely spread from the Gulf Oasis region toward the Near East and Europe during the pluvial period 55–24 ka ago. This pattern suggests that Arabia was indeed the first staging post in the spread of modern humans around the world. PMID:22284828

  8. Analysis of the spatio-temporal variability of seawater quality in the southeastern Arabian Gulf.

    PubMed

    Mezhoud, Nahla; Temimi, Marouane; Zhao, Jun; Al Shehhi, Maryam Rashed; Ghedira, Hosni

    2016-05-15

    In this study, seawater quality measurements, including salinity, sea surface temperature (SST), chlorophyll-a (Chl-a), Secchi disk depth (SDD), pH, and dissolved oxygen (DO), were made from June 2013 to November 2014 at 52 stations in the southeastern Arabian Gulf. Significant variability was noticed for all collected parameters. Salinity showed a decreasing trend, and Chl-a, DO, pH, and SDD demonstrated increasing trends from shallow onshore stations to deep offshore ones, which could be attributed to variations of ocean circulation and meteorological conditions from onshore to offshore waters, and the likely effects of desalination plants along the coast. Salinity and temperature were high in summer and low in winter while Chl-a, SDD, pH, and DO indicated an opposite trend. The CTD profiles showed vertically well-mixed structures. Qualitative analysis of phytoplankton showed a high diversity of species without anomalous species found except in Ras Al Khaimah stations where diatoms were the dominating ones.

  9. Analysis of the spatio-temporal variability of seawater quality in the southeastern Arabian Gulf.

    PubMed

    Mezhoud, Nahla; Temimi, Marouane; Zhao, Jun; Al Shehhi, Maryam Rashed; Ghedira, Hosni

    2016-05-15

    In this study, seawater quality measurements, including salinity, sea surface temperature (SST), chlorophyll-a (Chl-a), Secchi disk depth (SDD), pH, and dissolved oxygen (DO), were made from June 2013 to November 2014 at 52 stations in the southeastern Arabian Gulf. Significant variability was noticed for all collected parameters. Salinity showed a decreasing trend, and Chl-a, DO, pH, and SDD demonstrated increasing trends from shallow onshore stations to deep offshore ones, which could be attributed to variations of ocean circulation and meteorological conditions from onshore to offshore waters, and the likely effects of desalination plants along the coast. Salinity and temperature were high in summer and low in winter while Chl-a, SDD, pH, and DO indicated an opposite trend. The CTD profiles showed vertically well-mixed structures. Qualitative analysis of phytoplankton showed a high diversity of species without anomalous species found except in Ras Al Khaimah stations where diatoms were the dominating ones. PMID:27012536

  10. Seismic reflection structure of intracratonic palmyride fold-thrust belt and surrounding Arabian platform, Syria

    SciTech Connect

    McBride, J.H.; Barazangi, M.; Best, J. ); Al-Saad, D.; Sawaf, T.; Al-Otri, M.; Gebran, A. )

    1990-03-01

    Seismic reflection and drill-hole data from central Syria provide a detailed view of the subsurface structure (10-15 km depth) of the relatively little-studied intracratonic Palmyride fold and thrust belt. The data set, together with surface geologic mapping, constrains a structural/stratigraphic section spanning the northeast sector of the belt and the surrounding subprovinces of the Arabian platform. The seismic reflection and drill-hole data show Mesozoic stratigraphic sequences thickening abruptly into the Palmyrides from the adjacent, arched Paleozoic platforms Neogene (alpine) folding and thrusting of the Mesozoic basin, as documented on the seismic data, are sharply restricted to the narrow width of the belt ({approximately}100 km), in contrast to the relatively undeformed Phanerozoic strata of the platforms to the north and south. The seismic and drill-hole data support the hypothesis that the palmyrides began as a Permian-Triassic failed rift connected to the Levantine passive continental margin, which was inverted and complexly deformed by the interfering effects of Cenozoic movements along the Dead Sea transform fault system and the Turkish Bitlis convergent zone. The seismic data provide a first view into the extent and depth of the early basin formation and subsequent compressional deformation, and as such represent a necessary element for constraining reconstructions of northern Middle East plate motions. 20 figs.

  11. Geology and hydrocarbon potential in the state of Qatar, Arabian Gulf

    SciTech Connect

    Alsharhan, A.S. ); Nairn, A.E.M. )

    1990-05-01

    The state of Qatar is situated in the southern Arabian Gulf and covers an area of 12,000 km{sup 2}. It is formed by a large, broad anticline, which is part of the regional south-southwest-north-northeast-trending Qatar-South Fars arch. The arch separates the two Infracambrian salt basins. The Dukhan field was the first discovery, made in 1939, in the Upper Jurassic limestones. Since then, a series of discoveries have been made so that Qatar has become one of the leading OPEC oil states. Hydrocarbon accumulations are widely dispersed throughout the stratigraphic column from upper Paleozoic to Cretaceous producing strata. The most prolific reservoirs are the Permian and Mesozoic shelf carbonate sequences. Minor clastic reservoirs occur in the Albian and Paleozoic sequences. Seals, mainly anhydrite and shale. occur both intraformationally and regionally. Several stratigraphic intervals contain source rocks or potential source rocks. The Silurian shales arc the most likely source of the hydrocarbon stored in the upper Paleozoic clastics and carbonates. The upper Oxfordian-middle Kimmeridgian rocks formed in the extensive starved basin during the Mesozoic period of sea level rise. Total organic carbon ranges between 1 and 6%, with the sulfur content approximately 9%. The source material consists of sapropelic liptodetrinite and algae. The geological background of the sedimentary facies through geologic time, stratigraphy, and structural evolution which control source, and the subsequent timing and migration of large-scale hydrocarbon generation are presented in detail.

  12. Helicopter Gravity Survey in the Dead Sea Area

    NASA Astrophysics Data System (ADS)

    Götze, H.-J.; Meyer, Uwe; Choi, Sungchan

    2010-03-01

    Earthquakes have been reported in the Middle East since biblical times. Seismological studies demonstrate that many damaging earthquakes occurred along the Dead Sea Transform (DST), a long shear zone that extends from the Gulf of Aqaba/Eilat through the Dead Sea into the Sea of Galilee. To better understand the behavior and dynamics of the Dead Sea Transform, the Dead Sea Integrated Research (DESIRE) interdisciplinary and international project was initiated in 2006. The DST, which forms one of the world’s largest pull-apart basins (120 kilometers long, 20 kilometers wide, and about 10 kilometers deep), is a system of left-lateral strike-slip faults that accommodates about 105 kilometers of relative motion between the African and Arabian plates. To study the DST in places where it is easily accessible, the DESIRE project area focused on the Dead Sea basin (Figure 1).

  13. Dominant role of winds near Sri Lanka in driving seasonal sea level variations along the west coast of India

    NASA Astrophysics Data System (ADS)

    Suresh, I.; Vialard, J.; Izumo, T.; Lengaigne, M.; Han, W.; McCreary, J.; Muraleedharan, P. M.

    2016-07-01

    The strong seasonal cycle of sea level along the west coast of India (WCI) has important consequences for ecosystem and fisheries, and the Lakshadweep high/low in the southeast Arabian Sea is important for fisheries and the Indian summer monsoon. Previous studies suggested that WCI sea level variability is primarily driven by remote wind forcing from the Bay of Bengal and equatorial Indian Ocean through coastal Kelvin wave propagation. Using a linear ocean model, we demonstrate that wind forcing in a relatively small region around the southern tip of India and east of Sri Lanka contribute to ~60% of this variability. Wind variations from the rest of the Bay and the equator only account respectively for ~20% and ~10%. Sea level signals forced by the "southern tip" winds extend westward into the eastern Arabian Sea through Rossby wave propagation, with more than 50% contribution in the Lakshadweep high/low region.

  14. Multifactorial inheritance of common white markings in the Arabian horse.

    PubMed

    Woolf, C M

    1990-01-01

    The results of a previous study were compatible with the hypothesis that common white facial markings in the Arabian horse have a multifactorial mode of inheritance. I expanded that study to (1) include the legs and therefore obtain insight into the heritability of common white markings in all peripheral regions (face and legs) of the Arabian horse and (2) investigate the influence of sex and the genotypes that produce the bay and chestnut phenotypes on the variation in common white markings. Both studies were based on computerized data obtained from the Arabian Horse Registry of America, Inc. Each leg of a horse was scored from 0 to 5 depending on the amount of whiteness present, and the four leg scores were added to obtain the total leg score for each horse. The facial region was divided into five areas, and each horse was given a score from 0 to 5 according to the number of areas with whiteness. Sire families were analyzed in which each sire family consisted of a sire, his foals, and the dams of those foals. There was a correlation between white facial scores and white leg scores, suggesting that both types of white markings are influenced by the same genetic mechanism. Sire-foal and dam-foal regression analyses were compatible with the hypothesis that common white leg markings also show multifactorial inheritance. Although the results support the model that additively acting genes (polygenes) influence the presence and extent of common white markings, the results also show that males are slightly more marked than are females and that chestnut horses are more heavily marked than are bay horses.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Depression, Anxiety and Stress among Saudi Arabian Dermatology Patients

    PubMed Central

    Ahmed, Anwar E.; Al-Dahmash, Abdulaziz M.; Al-Boqami, Qamra T.; Al-Tebainawi, Yazeed F.

    2016-01-01

    Objectives: This study aimed to determine the prevalence of depression, anxiety and stress among Saudi Arabian dermatology patients and to assess associations with sociodemographic and clinical characteristics. Methods: This cross-sectional study was conducted among 300 consecutive dermatology patients visiting King Abdulaziz Medical City in Riyadh, Saudi Arabia, in August 2015. The Arabic version of the Depression, Anxiety and Stress Scale was used to screen for symptoms of depression, anxiety and stress. Quality of life (QOL) was assessed using the Dermatology Life Quality Index. Results: A total of 254 dermatology patients participated in the study (response rate: 84.7%). The prevalence of depression, anxiety and stress was 12.6%, 22.1% and 7.5%, respectively. The presence of at least one of these negative emotional states was noted among 24.4% of the cohort (95% confidence interval: 19.3–30.2%). Depression was significantly higher among subjects who lacked family support (26.5% versus 10.7%; P = 0.006) while anxiety was less common among patients who engaged in physical exercise (14.5% versus 29.4%; P = 0.005). According to the multivariate logistic regression analysis, poor QOL and a lack of family support were significant predictors of a negative emotional state. Conclusion: Almost a quarter of the studied Saudi Arabian dermatology patients were found to suffer from at least one negative emotional state. A lack of family support and poor QOL were the primary factors associated with a negative emotional state. Interventional studies are needed to examine the effects of social and family support on psychological conditions among Saudi Arabian dermatology patients. PMID:27226914

  16. Insights into Seismic and Volcanic Processes around the Arabian Plate from InSAR Observations

    NASA Astrophysics Data System (ADS)

    Jónsson, Sigurjón; Wang, Teng; Akoglu, Ahmet; Feng, Guangcai; Xu, Wenbin; Harrington, Jonathan; Cavalié, Olivier

    2014-05-01

    We use InSAR observations to study a variety of seismic and volcanic processes at the plate boundary surrounding the Arabian plate. The plate-boundary motion ranges from extension in the Red Sea and Gulf of Aden to the south, to compression in Turkey and Iran to the north, with transform motion to the west and to the east. Many large earthquakes have occurred during the past two decades in the region, some of which we are studying, including the 1995 magnitude 7.2 earthquake in the Gulf of Aqaba, the 2011 magnitude 7.1 Van earthquake in eastern Turkey, the 2012 Ahar earthquake duplet in northwestern Iran, as well as the 2013 magnitude 7.7 Baluchistan (Pakistan) earthquake. These earthquakes took place in tectonic settings ranging from a transtension in the Gulf of Aqaba, to transpression in Baluchistan, to almost pure compression in eastern Turkey. For the Aqaba earthquake we add previously unused InSAR data and use modern data processing methods to improve earlier fault-model estimations. In the case of the Baluchistan earthquake we find surprisingly uniform and simple fault slip along the over 200 km long rupture, with maximum slip of almost 10 m near the surface. In addition, for the Van earthquake we use SAR-image offset tracking in the near-field, as some of the interferograms are almost completely incoherent. By identifying point-like targets within the images, we are able to derive better pixel offsets between SAR sub-images than with standard offset-tracking methods. We use the azimuth- and range offsets to derive the 3D coseismic displacements, which help constraining the geometry and slip of the causative northward-dipping thrust fault. Further west, in the region near the triple junction between the Arabian, Eurasian, and Anatolian plates, we use large-scale InSAR data processing to map the interseismic deformation near the triple junction and find very shallow locking depth of the eastern part of the East Anatolian Fault, indicating limited strain

  17. XY male pseudohermaphroditism in a captive Arabian oryx (Oryx leucoryx).

    PubMed

    Padilla, Luis R; Dutton, Christopher J; Bauman, Joan; Duncan, Mary

    2005-09-01

    A 2-yr-old Arabian oryx (Oryx leucoryx) was presented for evaluation of abnormal genitalia and infantile behavior. The oryx had a penis and a scrotum, but testes were not palpable within the scrotum or inguinal canal. The total serum testosterone for the individual was lower than in age-matched males of the same species. Surgical exploration showed markedly hypoplastic intra-abdominal gonads, which demonstrated both testicular and uterine tissue on histologic examination. After karyotype analysis, the individual was classified as an XY male pseudohermaphrodite. This condition resembles two human intersex syndromes: embryonic testicular regression syndrome and partial gonadal dysgenesis syndrome, which occur in familial lines. PMID:17312771

  18. Arabian killifish (Aphanius dispar) embryos: A model organism for the risk assessment of the Arabian Gulf coastal waters.

    PubMed

    Saeed, Suhur; Al-Naema, Nayla; Butler, Josh D; Febbo, Eric J

    2015-12-01

    Fish embryos are excellent models for studies aimed at understanding toxic mechanisms and indications of possible acute and chronic effects. For the past 3 yr, an Arabian killifish (Aphanius dispar) fish embryo test has been developed in the authors' laboratory as a routine ecotoxicological test that can be used to support risk assessment of potential contaminants in Arabian Gulf coastal waters. Tests were conducted with 3 reference toxicants (3,4-dichloroaniline [DCA], sodium dodecyl sulfate, and zinc sulfate [Zn]) and chlorine, a disinfectant used widely in industrial cooling systems around the Arabian Gulf region. The 50% effect concentration (EC50) for DCA was 0.47 mg/L and 1.89 mg/L for embryos exposed before 6 hpf and after 168 hpf, respectively. Sublethal effects were mainly observed at concentrations above 2.5 mg/L, the effects included severe pericardial edema and tail shortage. The sodium dodecyl sulfate ionic surfactant caused mortality at both early and late stages of embryo development; it caused coagulation, severe deformity, and hemolysis. Both the EC50 and the 50% lethal concentration (LC50) for sodium dodecyl sulfate were 9.37 mg/L. Salinity influenced the toxicity of Zn to killifish embryos: at 40 psu Zn was found not to be toxic, whereas at 20 psu toxicity had increased significantly (p < 0.05). Values of EC50 and LC50 were 2.5 mg/L and 4 mg/L, respectively. Concentrations above 15 mg/L in embryos were often accompanied by upper abdominal edema and inhibition of growth, especially evident in the tail. Chlorine caused mortality at a lower concentration; for example, at 0.05 mg/L 33% of embryos were found dead at the end of the experiment. The LC50 for chlorine was determined to be 0.08 mg/L. Examination of the existing literature showed similar results to the present study's findings. The results suggest a more comparable sensitivity of killifish embryos to that of other fish embryo test recommended species. The present study

  19. Arabian killifish (Aphanius dispar) embryos: A model organism for the risk assessment of the Arabian Gulf coastal waters.

    PubMed

    Saeed, Suhur; Al-Naema, Nayla; Butler, Josh D; Febbo, Eric J

    2015-12-01

    Fish embryos are excellent models for studies aimed at understanding toxic mechanisms and indications of possible acute and chronic effects. For the past 3 yr, an Arabian killifish (Aphanius dispar) fish embryo test has been developed in the authors' laboratory as a routine ecotoxicological test that can be used to support risk assessment of potential contaminants in Arabian Gulf coastal waters. Tests were conducted with 3 reference toxicants (3,4-dichloroaniline [DCA], sodium dodecyl sulfate, and zinc sulfate [Zn]) and chlorine, a disinfectant used widely in industrial cooling systems around the Arabian Gulf region. The 50% effect concentration (EC50) for DCA was 0.47 mg/L and 1.89 mg/L for embryos exposed before 6 hpf and after 168 hpf, respectively. Sublethal effects were mainly observed at concentrations above 2.5 mg/L, the effects included severe pericardial edema and tail shortage. The sodium dodecyl sulfate ionic surfactant caused mortality at both early and late stages of embryo development; it caused coagulation, severe deformity, and hemolysis. Both the EC50 and the 50% lethal concentration (LC50) for sodium dodecyl sulfate were 9.37 mg/L. Salinity influenced the toxicity of Zn to killifish embryos: at 40 psu Zn was found not to be toxic, whereas at 20 psu toxicity had increased significantly (p < 0.05). Values of EC50 and LC50 were 2.5 mg/L and 4 mg/L, respectively. Concentrations above 15 mg/L in embryos were often accompanied by upper abdominal edema and inhibition of growth, especially evident in the tail. Chlorine caused mortality at a lower concentration; for example, at 0.05 mg/L 33% of embryos were found dead at the end of the experiment. The LC50 for chlorine was determined to be 0.08 mg/L. Examination of the existing literature showed similar results to the present study's findings. The results suggest a more comparable sensitivity of killifish embryos to that of other fish embryo test recommended species. The present study

  20. Seascape genetics along environmental gradients in the Arabian Peninsula: insights from ddRAD sequencing of anemonefishes.

    PubMed

    Saenz-Agudelo, Pablo; Dibattista, Joseph D; Piatek, Marek J; Gaither, Michelle R; Harrison, Hugo B; Nanninga, Gerrit B; Berumen, Michael L

    2015-12-01

    Understanding the processes that shape patterns of genetic structure across space is a central aim of landscape genetics. However, it remains unclear how geographical features and environmental variables shape gene flow, particularly for marine species in large complex seascapes. Here, we evaluated the genomic composition of the two-band anemonefish Amphiprion bicinctus across its entire geographical range in the Red Sea and Gulf of Aden, as well as its close relative, Amphiprion omanensis endemic to the southern coast of Oman. Both the Red Sea and the Arabian Sea are complex and environmentally heterogeneous marine systems that provide an ideal scenario to address these questions. Our findings confirm the presence of two genetic clusters previously reported for A. bicinctus in the Red Sea. Genetic structure analyses suggest a complex seascape configuration, with evidence of both isolation by distance (IBD) and isolation by environment (IBE). In addition to IBD and IBE, genetic structure among sites was best explained when two barriers to gene flow were also accounted for. One of these coincides with a strong oligotrophic-eutrophic gradient at around 16-20˚N in the Red Sea. The other agrees with a historical bathymetric barrier at the straight of Bab al Mandab. Finally, these data support the presence of interspecific hybrids at an intermediate suture zone at Socotra and indicate complex patterns of genomic admixture in the Gulf of Aden with evidence of introgression between species. Our findings highlight the power of recent genomic approaches to resolve subtle patterns of gene flow in marine seascapes.

  1. Seascape genetics along environmental gradients in the Arabian Peninsula: insights from ddRAD sequencing of anemonefishes.

    PubMed

    Saenz-Agudelo, Pablo; Dibattista, Joseph D; Piatek, Marek J; Gaither, Michelle R; Harrison, Hugo B; Nanninga, Gerrit B; Berumen, Michael L

    2015-12-01

    Understanding the processes that shape patterns of genetic structure across space is a central aim of landscape genetics. However, it remains unclear how geographical features and environmental variables shape gene flow, particularly for marine species in large complex seascapes. Here, we evaluated the genomic composition of the two-band anemonefish Amphiprion bicinctus across its entire geographical range in the Red Sea and Gulf of Aden, as well as its close relative, Amphiprion omanensis endemic to the southern coast of Oman. Both the Red Sea and the Arabian Sea are complex and environmentally heterogeneous marine systems that provide an ideal scenario to address these questions. Our findings confirm the presence of two genetic clusters previously reported for A. bicinctus in the Red Sea. Genetic structure analyses suggest a complex seascape configuration, with evidence of both isolation by distance (IBD) and isolation by environment (IBE). In addition to IBD and IBE, genetic structure among sites was best explained when two barriers to gene flow were also accounted for. One of these coincides with a strong oligotrophic-eutrophic gradient at around 16-20˚N in the Red Sea. The other agrees with a historical bathymetric barrier at the straight of Bab al Mandab. Finally, these data support the presence of interspecific hybrids at an intermediate suture zone at Socotra and indicate complex patterns of genomic admixture in the Gulf of Aden with evidence of introgression between species. Our findings highlight the power of recent genomic approaches to resolve subtle patterns of gene flow in marine seascapes. PMID:26577830

  2. Trace metals in gills of fish from the Arabian Gulf

    SciTech Connect

    Al-Yakoob, S.; Bahloul, M. ); Bou-Olayan, A.H.

    1994-11-01

    Complexation of metals by coordinate linkages with appropriate organic molecules in biological tissues is an important process involved in metal accumulation by aquatic organisms. Fish respiratory systems differ from all other systems because damage to gills has immediate impacts on the rest of the fish's body. Veer et al. observed significant correlation between gill-metal concentration and whole-body weight. More nickel is accumulated in gill tissue of the catfish (Clarias batrachus) than in the liver or intestine. More cadmium is accumulated in gill tissue of the fish Heteropneustes fossilis (Bloch) and Channa punctatus (Bloch) than in the liver or kidney. When exposed to lethal and sublethal concentrations of copper, gills of the freshwater fish Labeo rohita (Hamilton) showed the highest degree of copper accumulation. Petroleum and petrochemical industry wastes contribute significantly to metal enrichment of the Arabian Gulf marine environment. Because accumulation of metal ions is significant in gills, levels of Cd, Cr, Cu, Ni and Pb were investigated in gills of fish from potentially impacted areas along the western side of the Arabian Gulf after the 1991 oil-spill. 15 refs., 3 figs., 1 tab.

  3. The M0:mb Discriminant in the Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Maggi, A.; Priestley, K.

    2001-05-01

    We develop M0:mb relationships for the eastern Arabian peninsula using regional waveform data. We use recordings of earthquakes in the Zagros mountains of southern Iran by the permanent broad band station at RAYN and the 1995--1997 Passcal deployment in the surrounding region. We follow a similar procedure to Priestley and Patton (1997). We obtain seismic moments by applying the Bolt and Herraiz (1983) method, which uses the amplitude decay of the Lg phase, calibrated by the using Harvard CMT moments of the larger events. We establish the regional magnitude scales mb(P_n) and mb(L_g) by determining the attenuation rates of Pn and Lg waves, calibrating the mb(P_n) against the teleseismic mb, and applying the Nuttli (1973) method to determine mb from Lg waves. Preliminary results show that the calibration curve for M0( CMT) against M0(L_g) for the Arabian peninsula is approximately parallel to that for central Asia, but offset by an extra 0.25~mu. We also find that M0 vs mb values for Arabia plot consistently above those for central Asia by 0.25~mu.

  4. Evaluation of the long-term variability of seawater salinity and temperature in response to natural and anthropogenic stressors in the Arabian Gulf.

    PubMed

    Elhakeem, Abubaker; Elshorbagy, Walid

    2013-11-15

    Evaluating the long-term variability of the seawater salinity and temperature due to climate change is a limiting economical and operational factor in planning the design of new and expansion of existing desalination plants. This need is amplified in the Arabian Gulf due to the natural arid climate and anthropological stresses related to energy exploration and ongoing major developments. The lack of data in this region further adds additional dimension to the problem. The present work represents a systematic innovative approach to evaluate the anticipated long-term changes in the seawater salinity and temperature under the stresses of projected climate change and massive industrial effluents using statistical correlation and hydrodynamic simulation. The proposed approach employs the direct relation between the net freshwater losses (evaporation) entrenched with the investigated stressors and the mean sea salinity and sea temperature variation of an inverse estuary to formulate the statistical correlation and the hydrodynamic simulation conditions.

  5. Style of extensional tectonism during rifting, Red Sea and Gulf of Aden

    USGS Publications Warehouse

    Bohannon, R.G.

    1989-01-01

    Geologic and geophysical studies from the Arabian continental margin in the southern Red Sea and LANDSAT analysis of the northern Somalia margin in the Gulf of Aden suggest that the early continental rifts were long narrow features that formed by extension on closely spaced normal faults above moderate- to shallow-dipping detachments with break-away zones defining one rift flank and root zones under the opposing rift flank. The rift flanks presently form the opposing continental margins across each ocean basin. The detachment on the Arabian margin dips gently to the west, with a breakaway zone now eroded above the deeply dissected terrain of the Arabian escarpment. A model is proposed in which upper crustal breakup occurs on large detachment faults that have a distinct polarity. -from Author

  6. Geodynamic and Magmatic Evolution of the Eastern Anatolian-Arabian Collision Zone, Turkey

    NASA Astrophysics Data System (ADS)

    Keskin, Mehmet

    2014-05-01

    The Eastern Anatolian-Arabian Collision Zone represents a crucial site within the Tethyan domain where a subduction system involving a volcanic arc (i.e. Cretaceous to Oligocene Pontide volcanic arc in the north) associated with a large subduction-accretion complex (i.e. Cretaceous to Oligocene Eastern Anatolian Accretionary Complex i.e. "EAAC" in the south) turned later into a major continental collision zone that experienced a series of geodynamic events including lithospheric delamination, slab-steepening & breakoff, regional domal uplift, widespread volcanism and tectonic escape via strike slip fault systems. The region includes some of the largest volcanic centers (e.g. Karacadaǧ, Aǧırkaya caldera, Ararat, Nemrut, Tendürek and Süphan volcanoes) and plateaus (e.g. The Erzurum-Kars Plateau) as well as the largest transform fault zones in the Mediterranean region. A recent geodynamic modeling study (Faccenna et al., 2013) has suggested that both the closure of the Tethys Ocean and the resultant collision were driven by a large scale and northerly directed asthenospheric mantle flow named the "Tethyan convection cell". This convection cell initiated around 25 Ma by combined effects of mantle upwelling of the Afar super plume located in the south, around 3,000 km away from the collision zone and the slab-pull of the Tethyan oceanic lithosphere beneath Anatolia in the north. The aforementioned mantle flow dragged Arabia to the north towards Eastern Anatolia with an average velocity of 2 cm/y for the last 20 My, twice as fast as the convergence of the African continent (i.e. 1 cm/y) with western and Central Turkey. This 1 cm/y difference resulted in the formation of the left lateral Dead Sea Strike Slip Fault between the African and Arabian plates. Not only did this mantle flow result in the formation of a positive dynamic topography in the west of Arabian block, but also created a dynamic tilting toward the Persian Gulf (Faccenna et al., 2013). Another

  7. Dust aerosol optical depth above Sahara and Arabian Peninsula from CALIOP: comparison with MODIS Deep Blue and MISR

    NASA Astrophysics Data System (ADS)

    Tsamalis, Christoforos; Chédin, Alain

    2013-04-01

    Sahara is the biggest desert of the Earth contributing about half the global dust emissions. Dust aerosols emitted from Sahara are transported to Atlantic Ocean, Mediterranean Sea and Middle East, while they can reach Americas and Europe. The Arabian Peninsula is also an important dust source region. In situ systematic measurements of the aerosol optical depth AOD above desert areas are very sparse due to extreme meteorological conditions. At the same time, retrieving the AOD from space-borne instruments above deserts is less straightforward than over sea or land. As an active instrument, the space-borne two-wavelength lidar CALIOP has the advantage to be far less affected by the desert high albedo in comparison to passive instruments measuring in the visible, while it is able to take measurements during nighttime. CALIOP was launched on board CALIPSO in April 2006 with principal aim to characterize aerosols and clouds vertical distribution on a global scale. Thanks to depolarisation at 532 nm, CALIOP is able to discriminate between dust and other types of aerosols, which generally do not depolarize light. However, being an elastic lidar in its retrieval of the AOD, a crucial assumption about the lidar ratio has to be done. In order to assess the quality of the CALIOP-retrieved AOD (532 nm) above Sahara and Arabian Peninsula we compare it with retrievals from MODIS (Aqua) Deep Blue (550 nm) and MISR (555 nm). For this purpose, the L2 5 km aerosol layer product (version 3.01) is used for the 5-year period June 2006 - May 2011. Only nighttime data are taken into consideration due to better signal to noise ratio and only the aerosols layers with the best quality of discrimination from clouds. The aerosols classes "dust" and "polluted dust" from the L2 product are used and seasonal maps with 1 degree horizontal resolution are established. The choice of seasonal maps permits to overcome the difficulty of CALIOP's low daily spatial coverage (beam diameter of 70 m at the

  8. Remnants of Miocene fluvial sediments in the Negev Desert, Israel, and the Jordanian Plateau: Evidence for an extensive subsiding basin in the northwestern margins of the Arabian plate

    NASA Astrophysics Data System (ADS)

    Zilberman, Ezra; Calvo, Ran

    2013-06-01

    fluvial sediments, reflecting a subsidence of the northern margins of the African continent (Arabian plate) before its breakup and the splitting of the Sinai-Israel subplate by the Dead Sea Transform. During the early Middle Miocene the subsidence was inversed as the mountainous backbone of Israel was uplifted. The uplift triggered a large scale denudation that removed the thick Early Miocene fluvial sequence from the Negev and transported the eroded sediments northwestward toward the eastern Mediterranean basin. Additional uplift during the late-Middle Miocene was associated with entrenchment of the Be'er Sheva Valley between the Judea Mountains in the north and the Negev Highlands in the south. This valley was flooded by the sea during the Late Miocene. We suggest that the formation of the Early Miocene subsiding basin at the northern edge of the Arabian sub-plate predated the breakup of the Arabian plate by the DST. The inversion of the subsiding regime, which led to the establishment of the Negev Highlands seems to be intimately related to the detachment of the Sinai-Israel sub-plate from the Arabian plate during the Middle Miocene.

  9. Neoproterozoic structural evolution of the NE-trending Ad-Damm Shear Zone, Arabian Shield, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Hamimi, Zakaria; El-Sawy, El-Sawy K.; El-Fakharani, Abdelhamid; Matsah, Mohamed; Shujoon, Abdulrahman; El-Shafei, Mohamed K.

    2014-11-01

    The Ad-Damm Shear Zone (AdSZ) is a major NE- (to NNE-) trending fault zone separating Jiddah and Asir tectonic terranes in the Neoproterozoic Juvenile Arabian Shield (AS). AdSZ is characterized by the development of dextral transcurrent shear-sense indicators and moderately to steeply NW plunging stretching lineations. It is mainly developed under high amphibolite-to greenschist-facies conditions and extends ∼380 km, with an average width ∼2-4 km, from the conspicuous Ruwah Fault Zone in the eastern shield to the Red Sea Coastal plain. It was believed to be one of the conjugate shears of the NW- to NNW-trending sinistral Najd Shear System. This assumption is, based on the noteworthy dextral shear criteria recorded within the 620 Ma mylonitic granite of No'man Complex. A total shear-zone strike length exceeding 117 km is carefully investigated during this study to reconstruct its structural evolution. Shear-sense indicators and other field observations including overprinting relations clearly demonstrate a complicated Neoproterozoic history of AdSZ, involving at least three phases of deformations (D1-D3). Both D1 and D2 phases were of contractional regime. During D1 phase a NW-SE compression led to the formation of NE-oriented low-angle thrusts and tight-overturned folds. D2 is represented by a NE-SW stress oriented that led to the development of an open folding. D3 is expressed by the NE-SW intensive dextral transcurrent brittle-ductile shearing. It is overprinting the early formed fabrics and played a significant role in the creation of AdSZ and the mega-scale related folds. Such deformation history reflects the same Neoproterozoic deformation regime recognized in the NE-trending shear zones in the Arabian-Nubian Shield (ANS).

  10. Using NASA EOS in the Arabian and Saharan Deserts to Examine Dust Particle Size and Spectral Signature of Aerosols

    NASA Astrophysics Data System (ADS)

    Brenton, J. C.; Keeton, T.; Barrick, B.; Cowart, K.; Cooksey, K.; Florence, V.; Herdy, C.; Luvall, J. C.; Vasquez, S.

    2012-12-01

    Exposure to high concentrations of airborne particulate matter can have adverse effects on the human respiratory system. Ground-based studies conducted in Iraq have revealed the presence of potential human pathogens in airborne dust. According to the Environmental Protection Agency (EPA), airborne particulate matter below 2.5μm (PM2.5) can cause long-term damage to the human respiratory system. Given the relatively high incidence of new-onset respiratory disorders experienced by US service members deployed to Iraq, this research offers a new glimpse into how satellite remote sensing can be applied to questions related to human health. NASA's Earth Observing System (EOS) can be used to determine spectral characteristics of dust particles, the depth of dust plumes, as well as dust particle sizes. Comparing dust particle size from the Sahara and Arabian Deserts gives insight into the composition and atmospheric transport characteristics of dust from each desert. With the use of NASA SeaWiFS DeepBlue Aerosol, dust particle sizes were estimated using Angström exponent. Brightness Temperature Difference (BTD) equation was used to determine the distribution of particle sizes, the area of the dust storm, and whether silicate minerals were present in the dust. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra satellite was utilized in calculating BTD. Minimal research has been conducted on the spectral characteristics of airborne dust in the Arabian and Sahara Deserts. Mineral composition of a dust storm that occurred 17 April 2008 near Baghdad was determined using imaging spectrometer data from the Jet Propulsion Laboratory Spectral Library and EO-1 Hyperion data. Mineralogy of this dust storm was subsequently compared to that of a dust storm that occurred over the Bodélé Depression in the Sahara Desert on 7 June 2003.

  11. Analysis of Shuttle Multispecral Infrared Radiometer measurements of the western Saudi Arabian shield.

    USGS Publications Warehouse

    Rowan, L.C.; Goetz, A.F.H.; Abbott, E.

    1987-01-01

    During the November 12-14, 1981 mission of the space shuttle Columbia, the Shuttle Multispectral Infrared Radiometer (SMIRR) recorded radiances in 10 channels along a 100m wide groundtrack across the western Saudi Arabian shield.-from Authors

  12. Application of Space Technology to Discovery of Ancient Desert Trade Routes in the Southern Arabian Peninsula

    NASA Technical Reports Server (NTRS)

    Blom, Ronald; Crippen, Robert; Hedges, George; Zarins, Juris

    1997-01-01

    Over the last decade, an unusual combination of historical research, traditional archaeology, and application of space technolgy has demonstrated the existence of trans-desert trade routes in the sourthern Arabian peninsula.

  13. Decadal stability of Red Sea mangroves

    NASA Astrophysics Data System (ADS)

    Almahasheer, Hanan; Aljowair, Abdulaziz; Duarte, Carlos M.; Irigoien, Xabier

    2016-02-01

    Across the Earth, mangroves play an important role in coastal protection, both as nurseries and carbon sinks. However, due to various human and environmental impacts, the coverage of mangroves is declining on a global scale. The Red Sea is in the northern-most area of the distribution range of mangroves. Little is known about the surface covered by mangroves at this northern limit or about the changes experienced by Red Sea mangroves. We sought to study changes in the coverage of Red Sea mangroves by using multi-temporal Landsat data (1972, 2000 and 2013). Interestingly, our results show that there has been no decline in mangrove stands in the Red Sea but rather a slight increase. The area covered by mangroves is about 69 Km2 along the African shore and 51 Km2 along the Arabian Peninsula shore. From 1972 to 2013, the area covered by mangroves increased by about 0.29% y-1. We conclude that the trend exhibited by Red Sea mangroves departs from the general global decline of mangroves. Along the Red Sea, mangroves expanded by 12% over the 41 years from 1972 to 2013. Losses to Red Sea mangroves, mostly due to coastal development, have been compensated by afforestation projects.

  14. Hydrocarbon group analysis of Arabian crude oils TBP-fractions

    SciTech Connect

    Beg, S.A.; Mahmud, F.; AlHarbi, D.K. )

    1990-02-01

    The authors present experimental studies carried out on hydrocarbon group analysis of commercial Arabian crude oil fractions corresponding to the true boiling point ranges of 200-400{sup 0}F, 400-500{sup 0}F, 500-650{sup 0}F, 650-850{sup 0}F and 850{sup 0}F+. The crude oils included Arab heavy (API{sup 0} = 28.0), Arab medium (API{sup 0} = 30.0), Arab light (API{sup 0} = 33.3), and Arab Berry extra light (API{sup 0} = 36.9). Waters Hydrocarbon Group Analyzer (HGA) system interfaced with model 730 Data Module has been used to obtain the compositional analysis in terms of saturates, neutral aromatics, polar aromatics and asphaltenes.

  15. Long-term hydrodynamic modeling of the Arabian Gulf.

    PubMed

    Elhakeem, Abubaker; Elshorbagy, Walid; Bleninger, Tobias

    2015-05-15

    A 3-D prognostic baroclinic hydrodynamic model of the Arabian Gulf (AG) was developed using Delft3D-FLOW. The model was forced with long-term time averaged climatological data over the computational domain and long-term salinity and temperature boundary conditions applied at its tidal open boundary. The model simulation results were thoroughly validated against measured tides from 5 stations and measured currents at 4 locations in the central and southern parts. Water salinity and temperature were validated in space and time using observations spanning over 73 years from 1923 to 1996 for the AG, the Strait of Hormuz and the Gulf of Oman. The bottom flow of the AG basin at the vicinity of the Strait of Hormuz was also validated against the available measurements. Seasonal evaporation and surface density spatial distribution maps were produced and compared with available records. The developed model setup successfully generated the AG seasonal stratification and hydrographic conditions. PMID:25819446

  16. SEISMIC DATA FOR NUCLEAR EXPLOSION MONITORING IN THE ARABIAN PENINSULA

    SciTech Connect

    Rodgers, A; Al-Amri, A

    2004-07-08

    We report results from the third and final year of our project (ROA0101-35) to collect seismic event and waveform data recorded in and around the Arabian Peninsula. This effort involves several elements. We are working with King Abdulaziz City for Science and Technology to collect data from the Saudi National Seismic Network, that consists of 38 digital three-component stations (27 broadband and 11 short-period). We have an ongoing collaboration with the Kuwait Institute for Scientific Research, which runs the eight station Kuwait National Seismic Network. We installed two temporary broadband stations in the United Arab Emirates (funded by NNSA NA-24 Office of Non-Proliferation & International Security). In this paper we present a summary of data collected under these efforts including integration of the raw data into LLNL's Seismic Research Database and preliminary analysis of souce parameters and earth structure.

  17. Wintertime precipitation variability over the Arabian Peninsula and its relationship with ENSO in the CAM4 simulations

    NASA Astrophysics Data System (ADS)

    Niranjan Kumar, K.; Ouarda, T. B. M. J.; Sandeep, S.; Ajayamohan, R. S.

    2016-10-01

    The climate variability on Earth is strongly influenced by the changes in the Sea Surface Temperature (SST) anomalies in the tropical oceans. More specifically, the inter-annual climate variability in the tropics as well as extra-tropical areas has large impact due to the anomalous SSTs in the tropical Pacific coupled with the El Niño Southern Oscillation (ENSO) through atmospheric teleconnections. However, the effect of ENSO on Middle Eastern region, specifically the Arabian Peninsula (AP) is marginally explored in previous studies. Hence, this study explicitly focuses on the assessment of ENSO variability and its winter climate teleconnections to the AP using the Community Atmospheric Model Version 4.0 (CAM4) simulations and Reanalysis datasets. ENSO teleconnections are also evaluated based on two sensitivity experiments (ENSO-related and ENSO-unrelated) using the CAM4 model. It is observed that during El Niño years the peninsular region receives more rainfall through enhanced moisture transport associated with anomalous westerly winds from adjoining Seas. The Rossby wave energy propagation in the atmosphere underlies important teleconnections involving ENSO. It is also noticed that there exist a distinct change in the phase of the Rossby wave pattern during El Niño and La Niña years which further causes the shift in the position of the jet stream over the Middle East.

  18. The ant genus Carebara Westwood in the Arabian Peninsula (Hymenoptera, Formicidae)

    PubMed Central

    Sharaf, Mostafa R.; Aldawood, Abdulrahman S.

    2013-01-01

    Abstract The ant genus Carebara of the Arabian Peninsula is revised. Carebara abuhurayri Sharaf & Aldawood, 2011 is synonymized under Carebara arabica Collingwood & van Harten, 2001. Carebara arabica is redescribed and a Neotype is fixed based on a specimen collected from southwestern Kingdom of Saudi Arabia. A new species, C. fayrouzae sp. n. is described from Saudi Arabia based on queens, major and minor workers. Keys to major and minor workers of the two Arabian Carebara species are given. PMID:24363580

  19. Oil exploration in Central Arabian Arch using Landsat images

    SciTech Connect

    Sabins, F.F.

    1996-12-31

    Beginning in 1988, the Chevron Remote Sensing Research Group and Aramco digitally processed and interpreted seven Landsat thematic mapper images of the Central Arabian Arch for two purposes: 1. Map geology at 1:250,000 scale; 2. Identify anomalies that may be surface expression of structural traps. The well-exposed outcrops are predominantly marine strata of Mesozoic age with regional dips to east and southeast at less than 2{degrees}. This structural setting lacks the patterns of arcuate and offset beds that characterize folds and faults in more strongly deformed terrains. Therefore we developed a model to predict the image expression of structures in this homoclinal terrain. We based the model on oil fields in the Arabian Gulf region that are drape anticlines overlying high-angle faults that offset basement rocks and Palecizoic strata. The anticlines grade upward into structural terraces caused by flattening of the regional dip. Erosion of the terraces produces subtle topographic and stratigraphic anomalies that are recognizable on the images. The model was used to interpret a number of image anomalies. We field-checked the anomalies and eliminated a few. Aramco then acquired seismic data for several of the more promising anomalies that confirmed the presence of subsurface structure. Drilling resulted in discovery of Raghib and Dilam fields that produce from the Unayzah Sandstone (Permian). Initial production in the discovery and development wells ranges from 3000 to 4300 BOPD with gravity of 44 to 46{degrees} API. The source of this high-quality oil is the Qusaiba Shale (Silurian). The new discoveries are approximately 100 km from the nearest fields. Less than two years elapsed from beginning of digital image processing to completion of the discovery wells.

  20. Oil exploration in Central Arabian Arch using Landsat images

    SciTech Connect

    Sabins, F.F. )

    1996-01-01

    Beginning in 1988, the Chevron Remote Sensing Research Group and Aramco digitally processed and interpreted seven Landsat thematic mapper images of the Central Arabian Arch for two purposes: 1. Map geology at 1:250,000 scale; 2. Identify anomalies that may be surface expression of structural traps. The well-exposed outcrops are predominantly marine strata of Mesozoic age with regional dips to east and southeast at less than 2[degrees]. This structural setting lacks the patterns of arcuate and offset beds that characterize folds and faults in more strongly deformed terrains. Therefore we developed a model to predict the image expression of structures in this homoclinal terrain. We based the model on oil fields in the Arabian Gulf region that are drape anticlines overlying high-angle faults that offset basement rocks and Palecizoic strata. The anticlines grade upward into structural terraces caused by flattening of the regional dip. Erosion of the terraces produces subtle topographic and stratigraphic anomalies that are recognizable on the images. The model was used to interpret a number of image anomalies. We field-checked the anomalies and eliminated a few. Aramco then acquired seismic data for several of the more promising anomalies that confirmed the presence of subsurface structure. Drilling resulted in discovery of Raghib and Dilam fields that produce from the Unayzah Sandstone (Permian). Initial production in the discovery and development wells ranges from 3000 to 4300 BOPD with gravity of 44 to 46[degrees] API. The source of this high-quality oil is the Qusaiba Shale (Silurian). The new discoveries are approximately 100 km from the nearest fields. Less than two years elapsed from beginning of digital image processing to completion of the discovery wells.

  1. Grandidierella bonnieroides Stephensen, 1948 (Amphipoda, Aoridae)-first record of an established population in the Mediterranean Sea.

    PubMed

    Brutto, Sabrina Lo; Iaciofano, Davide; Lubinevsky, Hadas; Galil, Bella S

    2016-01-01

    The first record in the Mediterranean Sea of the invasive aorid amphipod crustacean Grandidierella bonnieroides is presented. A widespread circumtropical species, recorded off the Saudi coast of the Arabian Gulf, the Red Sea and the Suez Canal, it may have been introduced into the Mediterranean through the Suez Canal. This tube-builder species of soft bottoms recently established a population in the polluted Haifa Bay, Israel. Further, this is the first Mediterranean record of the genus. PMID:27394471

  2. Grandidierella bonnieroides Stephensen, 1948 (Amphipoda, Aoridae)-first record of an established population in the Mediterranean Sea.

    PubMed

    Brutto, Sabrina Lo; Iaciofano, Davide; Lubinevsky, Hadas; Galil, Bella S

    2016-03-17

    The first record in the Mediterranean Sea of the invasive aorid amphipod crustacean Grandidierella bonnieroides is presented. A widespread circumtropical species, recorded off the Saudi coast of the Arabian Gulf, the Red Sea and the Suez Canal, it may have been introduced into the Mediterranean through the Suez Canal. This tube-builder species of soft bottoms recently established a population in the polluted Haifa Bay, Israel. Further, this is the first Mediterranean record of the genus.

  3. Tomographic Imaging of Upper Mantle P- and S-wave Velocity Heterogeneity Beneath the Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Park, Y.; Nyblade, A. A.; Rodgers, A.; Al-Amri, A.

    2005-12-01

    We have studied the three-dimensional P- and S-wave velocity structure beneath the Arabian Peninsula estimated from teleseismic travel time delay tomography. We have completed travel time measurements and inversion of a data set provided by King Abdulaziz City for Science and Technology (KACST: 21 broadband stations and 4 short-period stations). We augmented the KACST data with delay times measured from permanent Incorporated Research Institutions for Seismology (IRIS) stations in the region (RAYN, EIL and MRNI) and the 1996 Saudi Arabian PASSCAL Experiment (9 broadband stations). We used 401 earthquakes resulting in 3416 ray paths with P- and PKP-wave arrivals for the P-wave tomography, and 1602 ray paths with S- and SKS-wave arrivals came from 201 earthquakes for the S-wave tomography. Although the total number of rays for the S-wave model is a half of the rays for the P-wave model, the event distribution shows better azimuthal coverage. The P and S wave models yield consistent results. The models show strong low velocity regions beneath the southeastern Arabian Shield and the mid-eastern edge of Arabian Shield. The low velocity anomaly in the southeastern part of the Arabian Shield does not extend north of 21°N and dips to south. It likely represents the northeastern edge of the Afar hotspot. The origin of the low velocity region under the eastern edge of the Arabian Shield is uncertain.

  4. Upper Mantle Structure Beneath The Arabian Peninsula From body and Surface Wave Tomography

    NASA Astrophysics Data System (ADS)

    Park, Y.; Nyblade, A.; Rodgers, A.; Al-Amri, A.

    2006-05-01

    We have imaged tomographically the three-dimensional velocity structure of the upper mantle beneath the Arabian Peninsula using teleseismic P- and S-waves and Rayleigh wave phase velocities. The data came from the Saudi Arabian National Digital Seismic Network (SANDSN) operated by King Abdulaziz City for Science and Technology (KACST: 21 broadband stations and 4 short-period stations). We augmented the KACST data with delay times measured from permanent Incorporated Research Institutions for Seismology (IRIS) stations in the region (RAYN, EIL and MRNI) and the 1996 Saudi Arabian PASSCAL Experiment (9 broadband stations). The P- and S wave models were inverted from 401 earthquakes resulting in 3416 ray paths with P- and PKP-wave arrivals, and 1602 ray paths with S- and SKS-wave arrivals came from 201 earthquakes, respectively. The P and S wave models yield consistent results. The models show strong low velocity regions beneath the southeastern Arabian Shield and the mid-eastern edge of Arabian Shield. The low velocity anomaly in the southeastern part of the Arabian Shield does not extend north of 21°N and dips to south. It likely represents the northeastern edge of the Afar hotspot. Surface wave tomography is being performed using fundamental mode Rayleigh wave phase velocities measured across the SANDSN. Preliminary phase velocity maps will be provided and compared to the body wave tomographic results.

  5. Tomographic Imaging of Upper Mantle P- and S-wave Velocity Heterogeneity Beneath the Arabian Peninsula

    SciTech Connect

    Park, Y; Nyblade, A; Rodgers, A; Al-Amri, A

    2005-08-30

    We report the estimates of three-dimensional P- and S-wave velocity structure beneath the Arabian Peninsula estimated from travel time delay tomography. We have completed travel time measurements and inversion of a partial data set provided by King Abdulaziz City for Science and Technology (KACST). This study builds on previous work by Benoit et al. (2003) following the methods of VanDecar and Crosson (1990) and VanDecar (1991). Data were collected from the Saudi Arabian National Digital Seismic Network (SANDSN) operated by KACST. The network consists of 38 stations (27 broadband and 11 short-period). We augmented the KACST data with delay times measured from permanent Incorporated Research Institutions for Seismology (IRIS) stations in the region (RAYN, EIL and MRNI) and the 1996 Saudi Arabian PASSCAL Experiment. This study shows the inverted P- and S-wave models computed with the combined data with all three different seismic networks (KASCST, IRIS, and the 1996 Saudi Arabian PASSCAL experiment) with best coverage beneath the Arabian Shield. Tomographic images reveal low velocity features in the upper mantle along a north-south line from the southern Asir region to the northeastern portion of the Arabian Shield.

  6. Causing Factors for Extreme Precipitation in the Western Saudi-Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Alharbi, M. M.; Leckebusch, G. C.

    2015-12-01

    In the western coast of Saudi Arabia the climate is in general semi-arid but extreme precipitation events occur on a regular basis: e.g., on 26th November 2009, when 122 people were killed and 350 reported missing in Jeddah following more than 90mm in just four hours. Our investigation will a) analyse major drivers of the generation of extremes and b) investigate major responsible modes of variability for the occurrence of extremes. Firstly, we present a systematic analysis of station based observations of the most relevant extreme events (1985-2013) for 5 stations (Gizan, Makkah, Jeddah, Yenbo and Wejh). Secondly, we investigate the responsible mechanism on the synoptic to large-scale leading to the generation of extremes and will analyse factors for the time variability of extreme event occurrence. Extreme events for each station are identified in the wet season (Nov-Jan): 122 events show intensity above the respective 90th percentile. The most extreme events are systematically investigated with respect to the responsible forcing conditions which we can identify as: The influence of the Soudan Low, active Red-Sea-Trough situations established via interactions with mid-latitude tropospheric wave activity, low pressure systems over the Mediterranean, the influence of the North Africa High, the Arabian Anticyclone and the influence of the Indian monsoon trough. We investigate the role of dynamical forcing factors like the STJ and the upper-troposphere geopotential conditions and the relation to smaller local low-pressure systems. By means of an empirical orthogonal function (EOF) analysis based on MSLP we investigate the possibility to objectively quantify the influence of existing major variability modes and their role for the generation of extreme precipitation events.

  7. Geological evolution of the Iraqi Mesopotamia Foredeep, inner platform and near surroundings of the Arabian Plate

    NASA Astrophysics Data System (ADS)

    Sissakian, Varoujan K.

    2013-08-01

    west of the Ga'ara Depression, represented by Early-Late Paleocene phosphatic facies, which is well developed east of Rutbah Uplift and extends eastwards in the Foredeep. Eocene rocks; west of Rutbah Uplift are represented by marine carbonates that has wide aerial coverage in south Iraq. Locally, east of Rutbah Uplift unconformable contacts are recorded between Early, Middle and Late Eocene rocks. During Oligocene, in the eastern margin of the Inner Platform, the Outer Platform was uplifted causing very narrow depositional Oligocene basin. Therefore, very restricted exposures are present in the northern part of the Inner Platform (north of Ga'ara Depression), represented by reef, forereef sediments of some Oligocene formations. The Miocene rocks have no exposures west of Rutbah Uplift, but north and northwestwards are widely exposed represented by Early Miocene of marine carbonates with marl intercalations. Very locally, Early Miocene deltaic clastics and carbonates, are interfingering with the marine carbonates. The last marine open sea sediments, locally with reef, represent the Middle Miocene rocks and fore reef facies that interfingers with evaporates along the northern part of Abu Jir Fault Zone, which is believed to be the reason for the restriction of the closed lagoons; in the area. During Late Miocene, the continental phase started in Iraq due to the closure of the Neo-Tethys and collision of the Sanandaj Zone with the Arabian Plate. The continental sediments consist of fine clastics. The Late Miocene - Middle Pliocene sediments were not deposited in the Inner Platform. The Pliocene-Pleistocene sediments are represented by cyclic sediments of conglomeratic sandstone overlain by fresh water limestone, and by pebbly sandstone. The Quaternary sediments are poorly developed in the Inner Platform. Terraces of Euphrates River and those of main valleys represent pleistocene sediments. Flood plain of the Euphrates River and those of large valleys represent Holocene

  8. New records of species of Saemundssonia (Insecta: Phthiraptera: Philopteridae) infesting breeding terns in the Arabian Peninsula, with notes on their phylogeny and ecology.

    PubMed

    Shobrak, Mohammed; Alahmed, Azzam; Palma, Ricardo; Almalki, Mohammed; Nasser, Mohamed Gamal El-Den

    2015-07-01

    Six species of terns, which breed on the Arabian Peninsula, were examined for head chewing lice of the genus Saemundssonia in four different islands around the coasts of Saudi Arabia, both in the Red Sea and in the Arabian Gulf. Four louse species were collected: Saemundssonia laticaudata, Saemundssonia melanocephalus, Saemundssonia meridiana and Saemundssonia sternae, of which three are recorded for the first time from this region. Also, we record three new host-louse associations for the world-Saemundssonia laticaudata and Saemundssonia sternae from white-cheeked terns and Saemundssonia melanocephalus from Saunders's terns-including a host-switch event of Saemundssonia laticaudata on white-cheeked terns in the Karan Island population. Gene bank data for the COI gene from seven species of Saemundssonia that infest marine birds were used to propose evolutionary trees using two different statistical methods: maximum parsimony (MP) and neighbour joining (NJ). The result indicated that the tree which was produced by NJ is likely to be more accurate as it appeared more compatible with hosts' phylogeny. The trees indicate relationships between tern Saemundssonia and congeneric species from other marine birds, especially from gulls. An ANOVA was also conducted to test the mean parasite load for each tern species studied, and results indicate that there is a relation between louse loads and colonization behaviour of the hosts. Data from lice examined and illustrations of lice and their hosts are also included.

  9. New records of species of Saemundssonia (Insecta: Phthiraptera: Philopteridae) infesting breeding terns in the Arabian Peninsula, with notes on their phylogeny and ecology.

    PubMed

    Shobrak, Mohammed; Alahmed, Azzam; Palma, Ricardo; Almalki, Mohammed; Nasser, Mohamed Gamal El-Den

    2015-07-01

    Six species of terns, which breed on the Arabian Peninsula, were examined for head chewing lice of the genus Saemundssonia in four different islands around the coasts of Saudi Arabia, both in the Red Sea and in the Arabian Gulf. Four louse species were collected: Saemundssonia laticaudata, Saemundssonia melanocephalus, Saemundssonia meridiana and Saemundssonia sternae, of which three are recorded for the first time from this region. Also, we record three new host-louse associations for the world-Saemundssonia laticaudata and Saemundssonia sternae from white-cheeked terns and Saemundssonia melanocephalus from Saunders's terns-including a host-switch event of Saemundssonia laticaudata on white-cheeked terns in the Karan Island population. Gene bank data for the COI gene from seven species of Saemundssonia that infest marine birds were used to propose evolutionary trees using two different statistical methods: maximum parsimony (MP) and neighbour joining (NJ). The result indicated that the tree which was produced by NJ is likely to be more accurate as it appeared more compatible with hosts' phylogeny. The trees indicate relationships between tern Saemundssonia and congeneric species from other marine birds, especially from gulls. An ANOVA was also conducted to test the mean parasite load for each tern species studied, and results indicate that there is a relation between louse loads and colonization behaviour of the hosts. Data from lice examined and illustrations of lice and their hosts are also included. PMID:25924793

  10. Interannual variability of the Indian summer monsoon associated with the air-sea feedback in the northern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Shukla, Ravi P.; Huang, Bohua

    2016-03-01

    Using observation-based analyses, this study identifies the leading interannual pattern of the Indian summer monsoon rainfall (ISMR) independent of ENSO and examines the potential mechanisms of its formation. For this purpose, an objective procedure is used to isolate the variability of the summer precipitation associated with the contemporary ENSO state and in previous winter-spring, which influence the Indian summer monsoon (ISM) region in opposite ways. It is shown that the leading pattern of these ENSO-related monsoon rainfall anomalies reproduces some major ISMR features and well represents its connections to the global-scale ENSO features in both lower and upper troposphere. On the other hand, the leading pattern derived from the precipitation anomalies with the ENSO component removed in the ISM and surrounding region also accounts for a substantial amount of the monsoon precipitation centered at the eastern coast of the subtropical Arabian Sea, extending into both the western Indian Ocean and the Indian subcontinent. The associated atmospheric circulation change is regional in nature, mostly confined in the lower to mid troposphere centered in the Arabian Sea, with a mild connection to an opposite tendency centered at the South China Sea. Further analyses show that this regional pattern is associated with a thermodynamic air-sea feedback during early to mid summer season. Specifically, before the monsoon onset, an anomalous atmospheric high pressure over the Arabian Sea causes excessive shortwave radiation to the sea surface and increases SST in May. The warm SST anomalies peak in June and reduce the sea level pressure. The anomalous cyclonic circulation generates regional convection and precipitation, which also induces subsidence and anticyclonic circulation over the South China Sea. The combined cyclonic-anticyclonic circulation further transport moisture from the western Pacific into the Indian Ocean and causes its convergence into the Arabian Sea. As a

  11. Monsoon oscillations regulate fertility of the Red Sea

    NASA Astrophysics Data System (ADS)

    Raitsos, Dionysios E.; Yi, Xing; Platt, Trevor; Racault, Marie-Fanny; Brewin, Robert J. W.; Pradhan, Yaswant; Papadopoulos, Vassilis P.; Sathyendranath, Shubha; Hoteit, Ibrahim

    2015-02-01

    Tropical ocean ecosystems are predicted to become warmer, more saline, and less fertile in a future Earth. The Red Sea, one of the warmest and most saline environments in the world, may afford insights into the function of the tropical ocean ecosystem in a changing planet. We show that the concentration of chlorophyll and the duration of the phytoplankton growing season in the Red Sea are controlled by the strength of the winter Arabian monsoon (through horizontal advection of fertile waters from the Indian Ocean). Furthermore, and contrary to expectation, in the last decade (1998-2010) the winter Red Sea phytoplankton biomass has increased by 75% during prolonged positive phases of the Multivariate El Niño-Southern Oscillation Index. A new mechanism is reported, revealing the synergy of monsoon and climate in regulating Red Sea greenness.

  12. 75 FR 2920 - In the Matter of the Designation of al-Qa'ida in the Arabian Peninsula (AQAP), Also Known as al...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-19

    ... al-Qa'ida Organization in the Arabian Peninsula (AQAP), Also Known as al-Qa'ida in Yemen (AQY), Also... Organization in the Arabian Peninsula (AQAP), also known as al-Qa'ida in Yemen (AQY), also known as...

  13. Chromatographic metasomatism of the Arabian-Nubian lithosphere

    NASA Astrophysics Data System (ADS)

    Kessel, R.; Navon, O.; Stein, M.

    1997-11-01

    Trace elements and isotopic ratios of calc-alkaline and tholeiitic dikes from the very last stage of the late Proterozoic, Pan-African orogeny in the northern Arabian-Nubian Shield (ANS), and alkali basalts from the overlying Phanerozoic section are used to constrain the composition and model the evolution of the lithospheric mantle in this region. The dikes and basalts are interpreted as lithospheric melts formed during the post-orogenic (and post-subduction) history of the shield. While the mafic member of all suites share a primitive La/Th ratio, the Nb/Th and Ce/Pb are distinct for each suite. The (Nb/Th)PM (primitive mantle normalized) is ~0.2 in the calc-alkaline dikes and 1.4 in the tholeiitic dikes and the Phanerozoic alkali basalts. The (Ce/Pb)PM ratios are low in the dikes (0.4 in the calc-alkaline and 0.3 in the tholeiitic) and high in the Phanerozoic basalts (2.8). We suggest that the variations in the trace element ratios reflect sampling of different zones in the lithospheric mantle, which were formed by subduction related metasomatism of the mantle wedge. We constructed a chromatographic model to explain this zonation. In this model a plume-derived oceanic lithosphere is subducted and dehydrates at depth. Fluids released from the dehydrating slab metasomatize the overlying wedge and form amphibole-rich channels. Nb is preferentially taken by the amphibole and is enriched only in the lower zones of the column. The other elements (U, Th, REE and especially Pb and Rb) behave incompatibly. They are enriched in the fluid and transported efficiently to the melting zone in the centre of the wedge. Dehydration of the base of the wedge as it descends below the amphibole stability field depletes this region in Pb and Rb. After the end of subduction, the wedge is fossilized and forms the lithospheric mantle. The zone above the Nb concentration front is sampled by the calc-alkaline magmas. The tholeiitic magmas sample the zone below the Nb front. The Phanerozoic

  14. A relook into the crustal architecture of Laxmi Ridge, northeastern Arabian Sea from geopotential data

    NASA Astrophysics Data System (ADS)

    Nair, Nisha; Anand, S. P.; Rajaram, Mita; Rao, P. Rama

    2015-04-01

    In this study, we undertake analysis of ship-borne gravity-magnetic and satellite-derived free-air gravity (FAG) data to derive the crustal structure of Laxmi Ridge and adjacent areas. 2D and 3D crustal modelling suggests that the high resolution FAG low associated with the ridge is due to underplating and that it is of continental nature. From Energy Spectral Analysis, five-depth horizons representing interface between different layers are demarcated that match those derived from 2D models. Magnetic sources from EMAG2 data, various filtered maps and absence of underplating in the EW section suggest that the EW and NW-SE segment of the Laxmi Ridge is divided by the Girnar fracture zone and probably associated with different stages of evolution. From the derived inclination parameters, we infer that the region to the north of Laxmi Ridge, between Laxmi and Gop Basins, is composed of volcanic/basaltic flows having Deccan affinity, which might have been emplaced in an already existing crust. The calculated inclination parameters derived from the best fit 2D model suggests that the rifting in the Gop Basin preceded the emplacement of the volcanics in the region between Laxmi and Gop Basins. The emplacement of volcanic/basaltic flows may be associated with the passage of India over the Reunion hotspot.

  15. Trajectory of an oil spill off Goa, eastern Arabian Sea: field observations and simulations.

    PubMed

    Vethamony, P; Sudheesh, K; Babu, M T; Jayakumar, S; Manimurali, R; Saran, A K; Sharma, L H; Rajan, B; Srivastava, M

    2007-07-01

    An oil spill occurred off Goa, west coast of India, on 23 March 2005 due to collision of two vessels. In general, fair weather with weak winds prevails along the west coast of India during March. In that case, the spill would have moved slowly and reached the coast. However, in 2005 when this event occurred, relatively stronger winds prevailed, and these winds forced the spill to move away from the coast. The spill trajectory was dominated by winds rather than currents. The MIKE21 Spill Analysis model was used to simulate the spill trajectory. The observed spill trajectory and the slick area were in agreement with the model simulations. The present study illustrates the importance of having pre-validated trajectories of spill scenarios for selecting eco-sensitive regions for preparedness and planning suitable response strategies whenever spill episodes occur.

  16. Biodegradation of low-density polyethylene by marine bacteria from pelagic waters, Arabian Sea, India.

    PubMed

    Harshvardhan, Kumar; Jha, Bhavanath

    2013-12-15

    Sixty marine bacteria isolated from pelagic waters were screened for their ability to degrade low-density polyethylene; among them, three were positive and able to grow in a medium containing polythene as the sole carbon source. The positive isolates were identified as Kocuria palustris M16, Bacillus pumilus M27 and Bacillus subtilis H1584 based on the 16S rRNA gene sequence homology. The weight loss of polyethylene was 1%, 1.5% and 1.75% after 30 days of incubation with the M16, M27 and H1584 isolates, respectively. The maximum (32%) cell surface hydrophobicity was observed in M16, followed by the H1584 and M27 isolates. The viability of the isolates growing on the polyethylene surface was confirmed using a triphenyltetrazolium chloride reduction test. The viability was also correlated with a concomitant increase in the protein density of the biomass. Polyethylene biodegradation was further confirmed by an increase in the Keto Carbonyl Bond Index, the Ester Carbonyl Bond Index and the Vinyl Bond Index, which were calculated from FT-IR spectra.

  17. Himalaya evolution at Paleogene-Neogene boundary unraveled by zircon age spectrum from Arabian Sea Sediments

    NASA Astrophysics Data System (ADS)

    Feng, Han; Lu, Huayu; Zhang, Hanzhi

    2016-04-01

    Although virtually all the intensive orogenic activities of Himalaya occurred in Neogene, the tectonic evolution of this high mountain range in Paleogene is poorly understood. Investigations of tectonic change pattern at Paleogene-Neogene boundary are important to better understand the interaction between mountain building and climate evolution. Here we present new U-Pb ages of zircon grains from Indus Fan sediments to constrain the orogenic history of Himalaya at Paleogene-Neogene boundary. 11 samples between late Oligocene and early Miocene from ODP 117 cores are dated by the zircon U-Pb technique. We calculate relative contributions of potential sources by counting zircon grains for each sample, and the quantized results indicate Himalaya contributed sediments to the coring site, and an extremely high input from Great and Tethyan Himalaya during late Oligocene-early Miocene. Four samples in Pleistocene are also dated for comparison, which indicates that high proportion of Lesser Himalaya has contributed to the sediment in Pleistocene. Our results suggest that the high contribution of Great and Tethyan Himalaya at Paleogene-Neogene boundary might correlate with the beginning of activity of MCT and extension of STD with leucogranite intrusion along Himalaya, which give rise to the extensive Great Himalaya exhumation. Our study demonstrates that zircon U-Pb dating technique is a good tool to reconstruct erosional history of mountain building on a tectonic timescale. Key words: ODP, Himalaya, Indus Fan, zircon U-Pb dating, Paleogene-Neogene boundary

  18. The sacrificial cathodic protection of UNS C71500 heat exchanger tubes in Arabian Gulf sea water

    SciTech Connect

    Al-Hashem, A.; Carew, J.A.; Al-Sayegh, A.

    1997-12-01

    A laboratory investigation using a specially designed circulating test rig was carried out to study the effectiveness of achieving complete cathodic protection of UNS C71500 heat exchanger tubes in seawater applications. Results indicated that the galvanic current distribution covered the entire 6m length of the tube. The presence of sulfide ions as pollutants in seawater shifted the galvanic potentials of the tubes to more active potentials and prevented the formation of protective films that normally form.

  19. Denaturing gradient gel electrophoresis profiling of bacterial communities composition in Arabian Sea.

    PubMed

    Singh, Sanjay Kumar; Ramaiah, Nagappa

    2011-05-01

    Denaturing gradient gel electrophoresis (DGGE) was used to elucidate spatial and temporal variations in bacterial community composition (BCC) from four locations along the central west coast of India. DNA extracts from 36 water samples collected from surface, mid-depth (-10 m) and dose to bottom (-20 m) during premonsoon, postmonsoon, monsoon were analyzed by PCRfor amplifying variable region of 16S rRNAgene and subsequently through DGGE. Prominent bands were excised, cloned and sequenced indicated the preponderance of gammaproteobacteria, bacteroidetes and cyanobacteria. Non-metric dimensional scaling of the DGGE gels indicated that the spatial variations in BCC were prominent among the sampling locations. Temporal variations in the BCC appear to be influenced by monsoonal processes. The canonical correspondence analyses suggest that the concentration of chlorophyll a and nitrate are two important environmental factors for both spatial and temporal variations in BCC. Chlorophyll a seems to be impart a top-down control of BCC while nitrate, the bottom-up control. Our results also suggest that BCC can vary over a small geographic distance in highly dynamic, seasonally predisposed tropical coastal waters.

  20. Bhargavaea indica sp. nov., a member of the phylum Firmicutes, isolated from Arabian Sea sediment.

    PubMed

    Verma, Pankaj; Seong, Chi Nam; Pandey, Prashant Kumar; Bhonde, Ramesh Ramchandra; Spröer, Cathrin; Rohde, Manfred; Shouche, Yogesh Shreepad

    2013-02-01

    A Gram-positive, aerobic, coccoid-rod shaped, non-motile, catalase- and oxidase-positive bacterium, designated strain KJW98(T), was isolated from the marine sediment of Karwar jetty, west coast of India. The strain was β-haemolytic, non-endospore-forming and grew with 0-8.5% (w/v) NaCl, at 15-48°C and at pH 6.5-9.0, with optimum growth with 0.5% (w/v) NaCl, at 42°C and at pH 7.0-8.0. Phylogenetic analyses based on 16S rRNA and gyrB gene sequences showed that strain KJW98(T) forms a lineage within the genus Bhargavaea. The G+C content of the genomic DNA was 55 mol%. The DNA-DNA relatedness values of strain KJW98(T) with B. beijingensis DSM 19037(T), B. cecembensis LMG 24411(T) and B. ginsengi DSM 19038(T) were 43.2, 39 and 26.5%, respectively. The major fatty acids were anteiso-C15:0 (37.7%), iso-C15:0 (19.7%), anteiso-C17:0 (17.0%) and iso-C16:0 (11.1%). The predominant menaquinone was MK-8 and the cell-wall peptidoglycan was of A4α type with L-lysine as the diagnostic diamino acid. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The phenotypic, genotypic and DNA-DNA relatedness data indicate that strain KJW98(T) should be distinguished from the members of the genus Bhargavaea, for which the name Bhargavaea indica sp. nov. is proposed with the type strain KJW98(T) (=KCTC 13583(T) =LMG 25219(T)).

  1. Shewanella indica sp. nov., isolated from sediment of the Arabian Sea.

    PubMed

    Verma, Pankaj; Pandey, Prashant Kumar; Gupta, Arvind Kumar; Kim, Ho Jun; Baik, Keun Sik; Seong, Chi Nam; Patole, Milind Shivaji; Shouche, Yogesh Shreepad

    2011-09-01

    A Gram-negative, facultatively anaerobic, rod-shaped, catalase- and oxidase-positive bacterium, motile by means of a single polar flagellum and designated strain KJW27(T), was isolated from the marine sediment of Karwar jetty, west coast of India. The strain was β-haemolytic and grew with 0-10 % (w/v) NaCl, at 10-45 °C and at pH 6.5-10, with optimum growth with 2 % (w/v) NaCl, at 37 °C and at pH 7.5. The major fatty acids were iso-C₁₅:₀ (22.2 %), C₁₇:₁ω8c (21 %), summed feature 3 (comprising C₁₆:₁ω7c and/or C₁₆:₁ω6c; 10.2 %), C₁₆:₀ (7.1 %), iso-C₁₃:₀ (5.6 %) and C₁₇:₀ (4.4 %). The DNA G+C content was 51.2 mol%. Phylogenetic analysis based on 16S rRNA and gyrB gene sequences showed that strain KJW27(T) forms a lineage within the genus Shewanella and is closely related to Shewanella algae ATCC 51192(T) (98.8 %), Shewanella haliotis DW01(T) (98.8 %) and Shewanella chilikensis JC5(T) (98.2 %). Sequence identity with other members of this genus ranges from 92.2 to 96.4 %. The DNA-DNA relatedness of strain KJW27(T) with S. algae ATCC 51192(T), S. haliotis DW01(T) and S. chilikensis JC5(T) was 52, 44 and 33 %, respectively. The phenotypic, genotypic and DNA-DNA relatedness data indicate that strain KJW27(T) should be distinguished from S. algae ATCC 51192(T), S. haliotis DW01(T) and S. chilikensis JC5(T). On the basis of the data presented in this study, strain KJW27(T) represents a novel species, for which the name Shewanella indica sp. nov. is proposed. The type strain is KJW27(T) ( = KCTC 23171(T)  = BCC 41031(T)  = NCIM 5388(T)).

  2. Biodegradation of low-density polyethylene by marine bacteria from pelagic waters, Arabian Sea, India.

    PubMed

    Harshvardhan, Kumar; Jha, Bhavanath

    2013-12-15

    Sixty marine bacteria isolated from pelagic waters were screened for their ability to degrade low-density polyethylene; among them, three were positive and able to grow in a medium containing polythene as the sole carbon source. The positive isolates were identified as Kocuria palustris M16, Bacillus pumilus M27 and Bacillus subtilis H1584 based on the 16S rRNA gene sequence homology. The weight loss of polyethylene was 1%, 1.5% and 1.75% after 30 days of incubation with the M16, M27 and H1584 isolates, respectively. The maximum (32%) cell surface hydrophobicity was observed in M16, followed by the H1584 and M27 isolates. The viability of the isolates growing on the polyethylene surface was confirmed using a triphenyltetrazolium chloride reduction test. The viability was also correlated with a concomitant increase in the protein density of the biomass. Polyethylene biodegradation was further confirmed by an increase in the Keto Carbonyl Bond Index, the Ester Carbonyl Bond Index and the Vinyl Bond Index, which were calculated from FT-IR spectra. PMID:24210946

  3. The influence of changing plate kinematics on a continental transform fault; the example of the Dead Sea Fault Zone

    NASA Astrophysics Data System (ADS)

    Smit, J.; Brun, J. P.; Cloetingh, S.

    2003-04-01

    The Dead Sea Fault Zone forms the boundary between the Sinai and Arabian plates and links the Red Sea spreading center in the South to the Taurus Mountains in the North. From field observations along the Southern part of the Dead Sea Fault zone (DSFZ) and investigations in the Red Sea area it has been suggested that the Arabian plate moves northward along the DSFZ by a rotation along an Euler pole that for the last 4 Ma years is located at 33°N23°E. It has also been suggested that this Euler pole was located about 5° more to the West during the first episode of movement. This change in motion of the Arabian plate coincides with the initiation of the main subsidence in the Dead Sea basin and the Gulf of Aqaba. The geometry and timing of deformation along the Northern segment of the DSFZ is much less constrained and different models have been proposed for the history of this segment. To study the influence of the change in plate motion on the DSFZ, a series of laboratory experiments has been performed. Special attention is being paid to the influence of rheologies on the system, the development of the fault zones geometry in time and with depth and wether a new rotational pole forces the initiation of a new fault or that the movement is accommodated by trenspression-transtension along the old fault.

  4. Identification of upwelling areas in the Oman Sea Using Satellite Data

    NASA Astrophysics Data System (ADS)

    Moradi, Masoud

    2016-07-01

    Satellite-derived sea-surface temperature, TOPEX/POSEIDON (T/P) sea-level anomalies (SLAs), modeled wind data, and hydrodynamic data from World Ocean Database were used to characterize the upwelling along the Oman Sea coasts during 2002 - 2012. Principal Component Analysis (PCA) of the satellite-derived sea-surface temperature (SST) shows the first mode affected by upwelling processes, which represents a biannual variability. In addition, the SST shows the upwelling front moving offshore with the development of Southwest (SW) Monsoon in early June. SST shows the persistence of cold upwelling waters for nearly a month after the end of the SW Monsoon within the bays along the Oman coast. TOPEX/POSEIDON SLAs indicate that with the onset of the SW Monsoon, a 30-cm drop in height is observed along the Oman coast associated the presence of the cool upwelled waters. This drop in height sets up a horizontal pressure gradient and results in a compensating along-shore, northeastward flowing, geostrophic current (East Arabian Current) during the SW Monsoon. Similarly, the altimeter data slow an offshore decrease in height during the Northeast (NE) Monsoon, indicating a seasonal reversal in direction of the East Oman Currents with flow to the southwest. The following upwelling characteristics are identified for the Oman upwelling zone: 1- Upwelling zones have seen along Oman and Pakistan coasts and in the western coasts, like Iran, persistent upwelling zones are not available. 2- Upwelling zones along Oman coasts are more persistent and developed than in Pakistan coastal area. 3- Upwelling in the Oman and East Pakistan coasts starts with SW-Monsoon and will developed in the mid-August, adjusted with summer cooling. 4- Along Oman Sea, upwelling zones were developed between Rasal-Haddad and the southern bay. Mean SST during SW-Monsoon is about 22 °C. 5-Waters with temperature about 23°C were upwelled from depth 50-75 m along Oman coasts, and about 50 m along Pakistan coasts. 6

  5. A pedigree-based study of mitochondrial D-loop DNA sequence variation among Arabian horses.

    PubMed

    Bowling, A T; Del Valle, A; Bowling, M

    2000-02-01

    Through DNA sequence comparisons of a mitochondrial D-loop hypervariable region, we investigated matrilineal diversity for Arabian horses in the United States. Sixty-two horses were tested. From published pedigrees they traced in the maternal line to 34 mares acquired primarily in the mid to late 19th century from nomadic Bedouin tribes. Compared with the reference sequence (GenBank X79547), these samples showed 27 haplotypes with altogether 31 base substitution sites within 397 bp of sequence. Based on examination of pedigrees from a random sampling of 200 horses in current studbooks of the Arabian Horse Registry of America, we estimated that this study defined the expected mtDNA haplotypes for at least 89% of Arabian horses registered in the US. The reliability of the studbook recorded maternal lineages of Arabian pedigrees was demonstrated by haplotype concordance among multiple samplings in 14 lines. Single base differences observed within two maternal lines were interpreted as representing alternative fixations of past heteroplasmy. The study also demonstrated the utility of mtDNA sequence studies to resolve historical maternity questions without access to biological material from the horses whose relationship was in question, provided that representatives of the relevant female lines were available for comparison. The data call into question the traditional assumption that Arabian horses of the same strain necessarily share a common maternal ancestry.

  6. The potential of high heat generating granites as EGS source to generate power and reduce CO2 emissions, western Arabian shield, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Chandrasekharam, D.; Lashin, A.; Al Arifi, N.; Al Bassam, A.; El Alfy, M.; Ranjith, P. G.; Varun, C.; Singh, H. K.

    2015-12-01

    Saudi Arabia's dependence on oil and gas to generate electricity and to desalinate sea water is widely perceived to be economically and politically unsustainable. A recent business as usual simulation concluded that the Kingdom would become an oil importer by 2038. There is an opportunity for the country to over come this problem by using its geothermal energy resources. The heat flow and heat generation values of the granites spread over a cumulative area of 161,467 sq. km and the regional stress regime over the western Saudi Arabian shield strongly suggest that this entire area is potential source of energy to support 1) electricity generation, 2) fresh water generation through desalination and 3) extensive agricultural activity for the next two decades. The country can adopt a policy to harness this vast untapped enhanced geothermal systems (EGS) to mitigate climate and fresh water related issues and increase the quantity of oil for export. The country has inherent expertise to develop this resource.

  7. The Influence of Wind and Basin Eddies in Controlling Sea Level Variations in the Coastal Red Sea

    NASA Astrophysics Data System (ADS)

    Abualnaja, Yasser O.; Churchill, James H.; Nellayaputhenpeedika, Mohammedali; Limeburner, Richard

    2015-04-01

    Sea level variations in the central Red Sea coastal zone span a range of roughly 1.2 m. Though relatively small, these water level changes can significantly impact the environment over the shallow reef tops prevalent in the central Red Sea, altering the water depth by a factor or two or more. Roughly half of the coastal sea level variance in central Red Sea is due to elevation changes in an 'intermediate' frequency band, with periods between 2 days and 1 month. We examined the sea level signal in this band using the data from pressure sensors maintained for more than five years at a number of locations in Saudi Arabian coastal waters between 20.1 and 23.5 oN. We find that the intermediate-band sea level variations are strongly correlated with the local wind stress measured at a meteorological buoy. The maximum pressure-wind correlation occurs at wind direction closely aligned with the alongshore orientation and at a lag (wind leading) of 45 hr, which is consistent with the expected response of the coastal sea level to local wind forcing. However, less than half of the sea level variance in the intermediate band is related, through linear correlation, with local wind forcing. Our analysis indicates that the residual coastal sea level signal, not associated with wind forcing, is largely driven remotely by the passage of mesoscale eddies, revealed by satellite altimeter-derived sea level anomaly fields of the central Red Sea. These eddy-driven coastal sea level changes occur on time scales of 10-30 days. They span a range of 0.5 m, and thus constitute an import component of the sea level signal in the coastal Red Sea.

  8. Infectious diseases in the Arabian Peninsula and Egypt.

    PubMed

    Shibl, A; Senok, A; Memish, Z

    2012-11-01

    Infectious diseases are important causes of morbidity and mortality globally. Epidemiologically, differences in the patterns of infectious diseases and antimicrobial resistance exist across diverse geographical regions. In this review on infectious diseases in the Arabian Peninsula and Egypt, the epidemiology of tuberculosis, malaria and human immunodeficiency virus (HIV) infections will be addressed. The challenges of the hepatitis C epidemic in Egypt and the epidemiology of this infection across the region will be reviewed. In recent years, we have seen dengue endemicity become established, with major outbreaks in parts of the region. Emerging data also indicate that, across the region, there is an increasing burden of antibiotic resistance, with endemicity in healthcare settings and dissemination into the community. New challenges include the emergence of the Alkhurma haemorrhagic fever virus in Saudi Arabia. The annual Hajj pilgrimage in Saudi Arabia serves as a model for the control of infectious disease in mass gatherings. As most of these countries constantly experience a uniquely dynamic population influx in the form of expatriate workers, tourists, or pilgrims, concerted regional and international collaboration to address these public health concerns in a region that lies at the crossroads for the global spread of infectious pathogens is imperative.

  9. Late Quaternary delta evolution on an uplifted coastal area (Wadi Haida Sultanate of Oman, Arabian Peninsula)

    NASA Astrophysics Data System (ADS)

    Quraishi, K. Al; Balushi, N. Al; Roepert, A.; Rupprechter, M.; Hoffmann, G.

    2012-04-01

    The Sultanate of Oman is situated in the Northeastern part of the Arabian Peninsula. The coastal morphology allows delineating areas of subsidence and uplift. The study area is located on the eastern shoreline facing the Indian Ocean. The coast is characterized by 6-7 wave cut terraces which are situated up to 400 m above present sea level. Whereas the higher - and therefore older - terraces are mainly erosional, the lower ones are depositional in style. We aim at quantifying the differential land movement along the coast (Rupprechter et al. 2012, Hoffmann et al. 2012 ). The study presented here aims at revealing the processes that resulted in the formation of the depositional terraces. Relevant processes are: (a) ongoing land uplift; (b) sea-level oscillations; (c) faulting. Historic evidence gave rise to the speculation of recent earthquake activity: the city of Qalhat, situated 7 km south of the study site was probably destroyed by an earthquake at the end of the 15th century (Musson 2009). The delta under investigation here formed at the mouth of the 15 km long Wadi Haida that drains the adjacent Selma Plateau (up to 2000 m high). The apex is situated 1.6 km from the present shoreline and the delta is some 2 km across. The delta sediments make up the lowermost terrace and are exposed along a cliff section. In the central part the cliff is 12 m high and cliff heights are lower to the North and South, reflecting the convex shape of the delta. The Quaternary delta deposits were deposited on top of an Eocene limestone. This formation is only observed in the northern part of the study area. In the southern part the formation is located below beach level, due to normal faulting. The lowermost unit related to the delta formation is a mudstone with in-situ coral reefs. The maximum thickness observed is 3 m. The coral reefs are capped by a 1.5 m thick layer of unconsolidated gravel. The sorting is very poor, individual boulders are up to 70 cm in diameter and angular

  10. Allelic polymorphism in arabian camel ribonuclease and the amino acid sequence of bactrian camel ribonuclease.

    PubMed

    Welling, G W; Mulder, H; Beintema, J J

    1976-04-01

    Pancreatic ribonucleases from several species (whitetail deer, roe deer, guinea pig, and arabian camel) exhibit more than one amino acid at particular positions in their amino acid sequences. Since these enzymes were isolated from pooled pancreas, the origin of this heterogeneity is not clear. The pancreatic ribonucleases from 11 individual arabian camels (Camelus dromedarius) have been investigated with respect to the lysine-glutamine heterogeneity at position 103 (Welling et al., 1975). Six ribonucleases showed only one basic band and five showed two bands after polyacrylamide gel electrophoresis, suggesting a gene frequency of about 0.75 for the Lys gene and about 0.25 for the Gln gene. The amino acid sequence of bactrian camel (Camelus bactrianus) ribonuclease isolated from individual pancreatic tissue was determined and compared with that of arabian camel ribonuclease. The only difference was observed at position 103. In the ribonucleases from two unrelated bactrian camels, only glutamine was observed at that position. PMID:962846

  11. Local adaptation constrains the distribution potential of heat-tolerant Symbiodinium from the Persian/Arabian Gulf.

    PubMed

    D'Angelo, Cecilia; Hume, Benjamin C C; Burt, John; Smith, Edward G; Achterberg, Eric P; Wiedenmann, Jörg

    2015-12-01

    The symbiotic association of corals and unicellular algae of the genus Symbiodinium in the southern Persian/Arabian Gulf (PAG) display an exceptional heat tolerance, enduring summer peak temperatures of up to 36 °C. As yet, it is not clear whether this resilience is related to the presence of specific symbiont types that are exclusively found in this region. Therefore, we used molecular markers to identify the symbiotic algae of three Porites species along >1000 km of coastline in the PAG and the Gulf of Oman and found that a recently described species, Symbiodinium thermophilum, is integral to coral survival in the southern PAG, the world's hottest sea. Despite the geographic isolation of the PAG, we discovered that representatives of the S. thermophilum group can also be found in the adjacent Gulf of Oman providing a potential source of thermotolerant symbionts that might facilitate the adaptation of Indian Ocean populations to the higher water temperatures expected for the future. However, corals from the PAG associated with S. thermophilum show strong local adaptation not only to high temperatures but also to the exceptionally high salinity of their habitat. We show that their superior heat tolerance can be lost when these corals are exposed to reduced salinity levels common for oceanic environments elsewhere. Consequently, the salinity prevailing in most reefs outside the PAG might represent a distribution barrier for extreme temperature-tolerant coral/Symbiodinium associations from the PAG.

  12. Local adaptation constrains the distribution potential of heat-tolerant Symbiodinium from the Persian/Arabian Gulf

    PubMed Central

    D'Angelo, Cecilia; Hume, Benjamin C C; Burt, John; Smith, Edward G; Achterberg, Eric P; Wiedenmann, Jörg

    2015-01-01

    The symbiotic association of corals and unicellular algae of the genus Symbiodinium in the southern Persian/Arabian Gulf (PAG) display an exceptional heat tolerance, enduring summer peak temperatures of up to 36 °C. As yet, it is not clear whether this resilience is related to the presence of specific symbiont types that are exclusively found in this region. Therefore, we used molecular markers to identify the symbiotic algae of three Porites species along >1000 km of coastline in the PAG and the Gulf of Oman and found that a recently described species, Symbiodinium thermophilum, is integral to coral survival in the southern PAG, the world's hottest sea. Despite the geographic isolation of the PAG, we discovered that representatives of the S. thermophilum group can also be found in the adjacent Gulf of Oman providing a potential source of thermotolerant symbionts that might facilitate the adaptation of Indian Ocean populations to the higher water temperatures expected for the future. However, corals from the PAG associated with S. thermophilum show strong local adaptation not only to high temperatures but also to the exceptionally high salinity of their habitat. We show that their superior heat tolerance can be lost when these corals are exposed to reduced salinity levels common for oceanic environments elsewhere. Consequently, the salinity prevailing in most reefs outside the PAG might represent a distribution barrier for extreme temperature-tolerant coral/Symbiodinium associations from the PAG. PMID:25989370

  13. Local adaptation constrains the distribution potential of heat-tolerant Symbiodinium from the Persian/Arabian Gulf.

    PubMed

    D'Angelo, Cecilia; Hume, Benjamin C C; Burt, John; Smith, Edward G; Achterberg, Eric P; Wiedenmann, Jörg

    2015-12-01

    The symbiotic association of corals and unicellular algae of the genus Symbiodinium in the southern Persian/Arabian Gulf (PAG) display an exceptional heat tolerance, enduring summer peak temperatures of up to 36 °C. As yet, it is not clear whether this resilience is related to the presence of specific symbiont types that are exclusively found in this region. Therefore, we used molecular markers to identify the symbiotic algae of three Porites species along >1000 km of coastline in the PAG and the Gulf of Oman and found that a recently described species, Symbiodinium thermophilum, is integral to coral survival in the southern PAG, the world's hottest sea. Despite the geographic isolation of the PAG, we discovered that representatives of the S. thermophilum group can also be found in the adjacent Gulf of Oman providing a potential source of thermotolerant symbionts that might facilitate the adaptation of Indian Ocean populations to the higher water temperatures expected for the future. However, corals from the PAG associated with S. thermophilum show strong local adaptation not only to high temperatures but also to the exceptionally high salinity of their habitat. We show that their superior heat tolerance can be lost when these corals are exposed to reduced salinity levels common for oceanic environments elsewhere. Consequently, the salinity prevailing in most reefs outside the PAG might represent a distribution barrier for extreme temperature-tolerant coral/Symbiodinium associations from the PAG. PMID:25989370

  14. Current Arabian Plate Motion From Campaign GPS Measurements in Saudi Arabia: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Almuslmani, B.; Teferle, F. N.; Bingley, R. M.; Moore, T.

    2007-12-01

    Current investigations of the motions of the Arabian and its neighboring plates are primarily based on GPS measurements obtained in the surrounding areas of the Arabian plate, with few stations actually located on the Arabian plate itself in the Kingdom of Saudi Arabia. In order to advance the knowledge of the dynamics of the Arabian plate and its intra-plate deformations, the General Directorate of Military Survey (GDMS), through collaboration with the Institute of Engineering Surveying and Space Geodesy (IESSG), densified the GPS network in Saudi Arabia, covering nearly two thirds of the tectonic plate. Since July 2002, a network of 32 GPS stations has been established at locations of the Saudi Arabia geodetic network. At all of these GPS stations a concrete pillar has been used as the monument and the locations have been selected in order to give the broadest distribution of observing sites. During 2005, 27 additional GPS stations in the Hejaz and Asser Mountains, and the Farasan Islands, all in south-western Saudi Arabia, have been established, for which the past and future campaign GPS measurements will provide valuable data for investigations of crustal deformations close to the plate boundaries between the Nubia, Somalian and Arabian plates. In this presentation we will show results in the form of velocity field and plate motion estimates based on data from at least three campaigns occupying the initial 32 GDMS GPS network stations, but also from a number of IGS stations in the region. Our reference frame is aligned to ITRF2005 and uses approximately 40 IGS reference frame stations located on all major tectonic plates, e.g. Nubia and Somalia, surrounding the Arabian plate. Furthermore, we apply absolute satellite and receiver antenna phase center models together with newly available GPS products from a recent global re-processing effort.

  15. Water scarcity in the Arabian Peninsula and socio-economic implications

    NASA Astrophysics Data System (ADS)

    Odhiambo, George O.

    2016-06-01

    The Arabian Gulf, one of the driest parts of the world, is already passing the water scarcity line as defined by the World Health Organization (WHO). The scarcity of renewable water resources and the growing discrepancy between demand and supply of water is a major challenge. Water scarcity is further worsened by rapidly growing demands due to rapid population growth, unsustainable consumption, climate change and weak management institutions and regulations. Water scarcity erodes the socio-economic sustainability of the communities that depend on the depleting storage. In this paper, an analysis of the water security situation within the Arabian Gulf region and the consequent socio-economic implications is presented.

  16. Genetic influence on circulating vitamin D among Saudi Arabians

    PubMed Central

    Sadat-Ali, Mir; Al-Turki, Haifa A.; Azam, Mohammed Q.; Al-Elq, Abdulmohsen H.

    2016-01-01

    Objectives To examine the effect of most common studied single nucleotide polymorphisms (SNP) on serum 25-hydroxyvitamin D (25OHD) levels in Saudi Arabian population. Method A cross-sectional observational study was carried out between July 2014 and October 2015, at King Fahd Hospital of the University (KFHU), Al-Khobar, Kingdom of Saudi Arabia. After informed consent, blood samples from 283 subjects living in the Eastern province were collected for 25-OHD measurement and genetic analysis of SNPs in vitamin D receptor (VDR) [rs2228570 and rs1544410], Cytochrome, P450 family 2 (CYP2R1) [rs10741657 and rs1993116], and Group-specific components (GC) [rs2282679 and rs4588]. Results Vitamin D deficiency was found in 87.6% and insufficiency in 7.7%. The percentages of the different alleles of the 6 SNPs tested ranged between 0-62.5%. There was significant difference between the AA, AG, and GG alleles of VDR rs2228570. The carries of GG allele was associated with increased risks of vitamin D insufficiency (p<0.002) and deficiency (p≤0.005). The CYP2R1 rs10741657 gene showed that AG and GG allele carriers had significant risk of vitamin D deficiency. AG allele (normal versus Insufficiency p<0.02 and normal versus deficiency p<0.08) and GG allele normal versus deficiency (p<0.002) and insufficiency versus deficiency (p<0.001). For group-specific components (GC rs4588), there was only significant difference between the normal and deficiency for the AC allele (p<0.0001). Conclusion The presence of GG allele of the SNP rs2228570 of VDR gene, SNPs rs4588 of GC gene and CYP2R1 rs10741657 gene was associated with vitamin D deficiency. PMID:27570856

  17. Earliest Phanerozoic or latest Proterozoic fossils from the Arabian Shield

    USGS Publications Warehouse

    Cloud, P.; Awramik, S.M.; Morrison, K.; Hadley, D.G.

    1979-01-01

    We report here the first biologically definable fossils from pre-Saq (pre-Middle Cambrian) rocks of the Arabian Shield. They include the distinctive helically coiled tubular filaments of the oscillatorialean blue-green alga Obruchevella parva as well as two size classes of spheroidal unicells of uncertain affinity. Also present is the conical stromatolite Conophyton and unidentified stromatolites. All occur in cherty limestones of the Jubaylah Group, northern Saudi Arabia, a nonmarine to locally marine taphrogeosynclinal sequence that fills depressions along the northwest-trending Najd faults. Conophyton has heretofore been found only in strata older than about 680 Ma (except for puzzling records in modern hot springs) while Obruchevella is so far known only from rocks between about 680 and 470 Ma old. Thus it appears that the Jubaylah Group is close to the Proterozoic-Phanerozoic transition. The simple spheroidal nanno-fossils are not diagnostic as to age. Their relationships within what appears to be early diagenetic chert suggest a classical algal-mat association. The brecciated and microchanneled appearance of much of the fossiliferous rock, its locally dolomitic nature, and the prevalence of cryptalgalaminate favors a very shallow, locally turbulent, and perhaps episodically exposed marine or marginal marine setting. The Jubaylah Group lies unconformably beneath the Siq Sandstone (basal member of the Saq Sandstone) of medial Cambrian age, rests nonconformably on crystalline basement, and has yielded a K-Ar whole-rock age (on andesitic basalt) of ???540 Ma. To judge from the fossils, however, that age m