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Sample records for arabian sea

  1. Submarine physiography off Lakshadweep Islands, Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Chaubey, A.K.

    Analysis of echosoundings, side scan sonar and shallow seismic data, supplementEd. by 152 sediment samples, collected along 150 km around Lakshadweep Islands, Arabian Sea, revealed that the islands have a very narrow shelf, and an abrupt, shelf...

  2. Salinity extrema in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S; Shetye, S; Gouveia, A.D.; Michael, G.S

    Levitus (1982) climatology has been used to identify four extrema, three maxima and one minimum, in the vertical salinity profiles in the Arabian Sea. Their geographical distribution, depths, theta-S characteristics, and seasonal variability...

  3. Primary productivity of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Pant, A.

    Reversal of surface circulation during the monsoons, patchy nutrient distributions and high light intensity drive phytoplankton production processes in the tropical Arabian Sea. Available data are discussed in the light of these driving phenomena...

  4. Hydrography of the eastern Arabian Sea during summer monsoon 2002

    Digital Repository Service at National Institute of Oceanography (India)

    Shankar, D.; Shenoi, S.S.C.; Nayak, R.K.; Vinayachandran, P.N.; Nampoothiri, G.S.; Almeida, A.M.; Michael, G.S.; RameshKumar, M.R.; Sundar, D.; Sreejith, O.P.

    Hydrographic observations in the eastern Arabian Sea (EAS) during summer monsoon 2002 (during the first phase of the Arabian Sea Monsoon Experiment (ARMEX)) include two approximately fortnight-long CTD time series. A barrier layer was observed...

  5. Ecology and biology of luminous bacteria in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Chandramohan, D.

    Extensive studies on occurrence, distribution and species composition of luminous bacteria in the Arabian Sea were carried out from various habitats. Luminous bacterial population was by far the highest in the environs of the Arabian Sea...

  6. Winter cooling in the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Prasad, T.G.

    forcing that leads to the observed high productivity during winter in the northern Arabian Sea. The weak northerly winds and increased solar insolation during the inter-monsoon period, led to the development of a highly stratified upper layer with warm sea...

  7. Arabian Sea oceanography and fisheries

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; Nair, K.N.V.; Venugopal, P.; Gauns, M.; Haridas, P.; Gopalakrishnan, T.C.; Nair, K.K.C.

    The physical and chemical forcing which drive the Arabian production is now fairly well understood. The main attributes, which contribute to the productivity are (1) the boundary processes which manifest as upwelling during summer monsoon and (2...

  8. The nitrogen cycle in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bange, H.W.; Naqvi, S.W.A.; Codispoti, L.A.

    to enhanced rates of denitrification that occur in suboxic portions of the water column in the Arabian Sea. Sedimentary denitrification is small compared to water column denitrification, and additions of fixed-N via N sub(2) fixation also are small compared...

  9. Marine magnetic anomalies in the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhattacharya, G.C.; Chaubey, A; Murty, G.P.S.; Rao, D.G.; Scherbakov, V.S.; Lygin, V.A; Philipenko, A; Bogomyagkov, A

    Based on the analysis of some additional magnetic profiles, an updated correlation and identification of the sea-floor spreading type magnetic lineations in the northeastern Arabian Sea is presented. The anomaly 24 A-B sequence, characteris...

  10. Surface layer temperature inversion in the Arabian Sea during winter

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Ghosh, A.K.

    Arabian Sea shows a very strong locality. Surface layer temperature inversion in the south eastern Arabian sea and the south western Bay of Bengal is a small scale thermal feature very widely reported with little analysis (Panakala Rao et al., 1981... along the west coast of India. 1. Introduction Temperature inversion layers usually occur where the thermal structure is complicated and isotherms are rugged. Nagata (1968, 1979) studied temperature inversions in the seas adjacent to Japan using...

  11. Characteristics of humic and fulvic acids in Arabian Sea sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.

    Humic and fulvic acids isolated from some of the shelf, slope and offshore sediments of the Arabian Sea were studied. The molecular weight, functional groups, elemental composition and infrared spectra were examined. Humic substances, dominated...

  12. Measurement of inherent optical properties in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Kurian, J.; Mascarenhas, A.A.M.Q.

    Inherent optical properties, absorption and began attenuation were measured in situ using a reflective tube absorption meter at nint wavelength, 412, 440, 488, 510, 555, 630, 650, 676 and 715 nm, in the Arabian Sea during March. Since inherent...

  13. A revised nitrogen budget for the Arabian Sea

    OpenAIRE

    Bange, Hermann W.; T. Rixen; Johansen, A. M.; Siefert, R. L.; Ramesh, R.; Ittekott, V.; Hoffmann, M. R.; Andreae, M. O.

    2000-01-01

    Despite its importance for the global oceanic nitrogen (N) cycle, considerable uncertainties exist about the N fluxes of the Arabian Sea. On the basis of our recent measurements during the German Arabian Sea Process Study as part of the Joint Global Ocean Flux Study (JGOFS) in 1995 and 1997, we present estimates of various N sources and sinks such as atmospheric dry and wet depositions of N aerosols, pelagic denitrification, nitrous oxide (N_2O) emissions, and advective N input from the south...

  14. Salinity pathways between Arabian Sea and Bay of Bengal

    Science.gov (United States)

    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.

  15. Distribution and ecology of the Trichodesmium spp. in the Arabian Sea: Ship and satellite studies

    Digital Repository Service at National Institute of Oceanography (India)

    Parab, S.G.; Matondkar, S.G.P.; Raman, M.; Dwivedi, R.M.

    . During our special cruises to the Arabian Sea we collected data to understand the seasonality of Trichodesmium spp. Trichodesmium starts appearing just after the SW monsoon in the offshore waters of the Arabian Sea. Massive blooms of Trichodesmium...

  16. Geographical extent of denitrification in the Arabian Sea in relation to some physical processes

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    in the Arabian Sea. Nitrite distribution shows little correspondence with primary productivity, and the three major sites of seasonal upwelling appear to be located outside the zone of intense denitrification. This distinguishes the Arabian Sea from the other two...

  17. Acoustic tomography experiment in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Murty, T.V.R.; Somayajulu, Y.K.; Saran, A.K.; Navelkar, G.S.; Almeida, A.M.; Fernando, V.; Murty, C.S.

    An acoustic transmission experiment was conducted in the eastern Arabian Sea along 12.5 degrees N latitude for a duration of ten days (2-12 May, 1993), with two transceiver systems deployed on deep sea moorings, separated by a range of 270.92 km...

  18. Hydrography of the eastern Arabian Sea during summer monsoon 2002

    Indian Academy of Sciences (India)

    D Shankar; S S C Shenoi; R K Nayak; P N Vinayachandran; G Nampoothiri; A M Almeida; G S Michael; M R Ramesh Kumar; D Sundar; O P Sreejith

    2005-10-01

    Hydrographic observations in the eastern Arabian Sea (EAS)during summer monsoon 2002 (during the first phase of the Arabian Sea Monsoon Experiment (ARMEX))include two approximately fortnight-long CTD time series.A barrier layer was observed occasionally during the two time series. These ephemeral barrier layers were caused by in situ rainfall,and by advection of low-salinity (high-salinity)waters at the surface (below the surface mixed layer).These barrier layers were advected away from the source region by the West India Coastal Current and had no discernible effect on the sea surface temperature.The three high-salinity water masses,the Arabian Sea High Salinity Water (ASHSW),Persian Gulf Water (PGW),and Red Sea Water (RSW),and the Arabian Sea Salinity Minimum also exhibited intermittency:they appeared and disappeared during the time series.The concentration of the ASHSW,PGW,and RSWdecreased equatorward,and that of the RSW also decreased offshore.The observations suggest that the RSW is advected equatorward along the continental slope off the Indian west coast.

  19. Abundance of Thraustochytrid fungi in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, S.; Raghukumar, C.; Rajendran, A.

    1989 and in revised form 10 April 1990 Keywords: thraustochytrid fungi; abundance; Arabian Sea Numbers of tbraustochytrid marine fungi were estimated in the waters of the Arabian Sea during four cruises in 1987-88 and at the mouth of the Zuari... estuary in Goa during two series of samplings in 1987. Thraustochytrids varied from < 6 to > 1100 1-l of seawater. Highest average numbers of 207 and 331 l- ’ of water were found at 0 and 30 m in the nearshore stations during the monsoon cruise SK 33...

  20. Carbon and nitrogen budgets of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Somasundar, K.; Rajendran, A.; DileepKumar, M.; SenGupta, R.

    and nitrogen budgets have been estimated for the Arabian Sea (0- 25 °N, 50-80°E), taking into consideration the possible sources of fluxes. By our model calculations the annual fluxes into and out of the Arabian Sea were estimated to be 446 and 530 trillion...) were obtained from Brewer and Dyrssen (1985 ) and Papaud and Poisson (1986), respectively. The details of the data and their sources are given in Table 1. The methods of calculating the fluxes of carbon and nitrogen are discussed below. RESULTS...

  1. Coccolithophores from the central Arabian Sea: Sediment trap results

    Indian Academy of Sciences (India)

    Lina P Mergulhao; Rahul Mohan; V S N Murty; M V S Guptha; D K Sinha

    2006-08-01

    Sediment trap samples collected from a depth of 1018 m in the Central Arabian Sea Trap (CAST) at 14° 28.2′N, 64° 35.8′E were analyzed for temporal variation of coccolithophore fluxes from October 1993 to August 1994.Out of the twenty species of coccolithophores encountered, \\tetit {Gephyrocapsa oceanica,Emiliania huxleyi,Umbilicosphaera sibogae} and Umbellosphaera irregularis were the most abundant.The total coccolithophore fluxes ranged from 28.5 × 106 m−2 d−1 to 50.3 × 106 m−2 d−1 showing seasonality with higher fluxes during the northeast (NE) monsoon and lower fluxes during the spring intermonsoon. The higher fluxes were attributed to the enhancement of primary production in the central Arabian Sea due to southward extent of nutrients from the northeast Arabian Sea by the prevailing surface currents. Similarly, the occurrences of relatively lower coc-colithophore fluxes during the spring intermonsoon and southwest (SW) monsoon were attributed to the low nutrients in the warm, shallow surface mixed layer and downwelling to the south of Findlater Jet respectively in the central Arabian Sea.Some of the coccolithophore species such as E.huxleyi, G.oceanica, Calcidiscus leptoporus and Umbellosphaera tenuis showed signs of dissolution.

  2. Biogeochemical ocean-atmosphere transfers in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Bange, H.W.; Gibb, S.W.; Goyet, C.; Hatton, A.D.; Upstill-Goddard, R.C.

    fluxes is through the production of N sub (2) and N sub (2) O facilitated by an acute, mid-water deficiency of dissolved oxygen (O sub (2) );emissions of these gases to the atmosphere from the Arabian Sea are globally significant. For the other...

  3. Evidence for change in depositional environment in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.; Rao, Ch.M.

    Sediments of late Pleistocene and Holocene periods, from a 12 m long core collected at a depth of 3627 m from the Arabian Sea, have been studied in order to understand the depositional environment. Sub-samples selected at 5 cm and occasionally at 10...

  4. The Arabian Sea: Physical environment, zooplankton and myctophid abundance

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, K.K.C.; Madhupratap, M.; Gopalakrishnan, T.C.; Haridas, P.; Gauns, M.

    that there are considerable spatial and temporal variations in the area in primary productivity. Nonetheless, contrary to earlier thinking, it would seem that the mesozooplankton abundance in the Arabian Sea is fairly high in the mixed layer all through the year. This paradox...

  5. Spreading history of the Arabian Sea: Some new constraints

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A; Bhattacharya, G.C.; Murty, G.P.S.; Desa, M.

    Based on a new identification of magnetic anomalies, additional constraints are provided on the two episodes of spreading history of the Arabian Sea. Commencing at A27, the older phase ended at A21 and sprading of the younger phase started shortly...

  6. State of oil pollution in the northern Arabian Sea after the 1991 Gulf oil spill

    Digital Repository Service at National Institute of Oceanography (India)

    Sengupta, R.; Fondekar, S.P.; Alagarsamy, R.

    Following the enormous oil spills resulting from the 1990-91 military conflict in the Gulf, fears were expressed concerning dissipation of oil from the Gulf into the Arabian Sea and Indian Ocean. To investigate contamination of the northern Arabian...

  7. The relationship between Arabian Sea upwelling and Indian monsoon revisited

    OpenAIRE

    Yi, X; B. Hünicke; N. Tim; E. Zorita

    2015-01-01

    Studies based on upwelling indices (sediment records, sea-surface temperature and wind) suggest that upwelling along the western coast of Arabian Sea is strongly affected by the Indian summer monsoon (ISM). In order to examine this relationship directly, we employ the vertical water mass transport produced by the eddy-resolving global ocean simulation STORM driven by meteorological reanalysis over the last 61 years. With its very high spatial resolution (10 ...

  8. Remotely Searching for Noctiluca Miliaris in the Arabian Sea

    Science.gov (United States)

    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].

  9. Nitrogen cycling in the suboxic waters of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Devol, A.H.; Naqvi, S.W.A.; Codispoti, L.A.

    in the oceans. Isotope measurements have been made for three of the major nitrogen species involved in nitrogen cycling in the Arabian Sea ODZ [8,72,73,98]. At a station in the heart of the ODZ with a well developed SNM, the isotopic composition of NO3... the S'~N of N03- increases dramatically to NITROGEN CYCLING IN THE SUBOXIC WATERS OF THE ARABIAN SEA 299 6 l5 N2 6 l5NO, - 0.2 0.4 0.6 6 10 14 I;iR~lre 8. Composite profiles of 6ISN2 and 6'%Oi^ froin profiles taken in the heart of the ODZ (Data...

  10. On the spectra and coherence of some surface meteorological parameters in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Fernandes, A.A.

    Spectra and cross-spectra of monthly time series of the surface meteorological parameters, sea surface temperature, air temperature, cloudiness, wind speed and sea level pressure were computed for the period 1948-1972 over the Arabian Sea...

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

    KAUST Repository

    Prakash, P. Jish

    2016-09-26

    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

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

    Science.gov (United States)

    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

  13. 'Shamal' swells in the Arabian Sea and their influence along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Aboobacker, V.M.; Vethamony, P.; Rashmi, R.

    on the meteorological and oceanographic conditions of the Arabian Sea, and this has not been studied so far. Rapid changes in wind patterns during these shamal events can alter the wave characteristics of the Arabian Sea. This has motivated us to take up the present...

  14. Hydrography and water masses in the southeastern Arabian Sea during March-June 2003

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Shankar, D.; Michael, G.S.; Kurian, J.; Varma, K.K.; RameshKumar, M.R.; Almeida, A.M.; Unnikrishnan, A.S.; Fernandes, W.A.; Barreto, N; Gnanaseelan, C.; Mathew, R.; Praju, K.V.; Mahale, V.

    that the intermittency of the RSW in the eastern Arabian Sea may be due to the occurrence of the RSW even in the northwestern Arabian Sea in the form of patches or lenses (Shapiro et al 1994; Beal et al 2000), which are advected to the northern end of the Indian west...

  15. Why is Bay of Bengal warmer than Arabian Sea during the summer monsoon?

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Shankar, D.; Shetye, S.R.

    The near-surface Bay of Bengal remains significantly warmer than the Arabian Sea during summer monsoon (June-September). Analysis of the heat budgets of the near-surface Arabian Sea and Bay of Bengal shows significant differences between them during...

  16. Formation and spreading of Arabian Sea high-salinity water mass

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Prasad, T.G.

    The formation and seasonal spreading of the Arabian Sea High-Salinity Water (ASHSW) mass were studied based on the monthly mean climatology of temperature and salinity in the Arabian Sea, north of the equator and west of 80 degrees E, on a 2 degrees...

  17. Oscillating environmental responses of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Gerson, V.J.; Madhu, N.V.; Jyothibabu, R.; Balachandran, K.K.; Nair, M.; Revichandran, C.

    Journal of Geo-Marine Sciences Vol. 43(1), January 2014, pp. 67-75 Oscillating environmental responses of the eastern Arabian Sea Vijay John Gerson1*, Madhu N V2, Jyothibabu R2, Balachandran K K2, Maheswari Nair2 & Revichandran C2 1St.Albert’s College.... Present study attempts to investigate the seasonal patterns and stratification of nutrients to evaluate its distribution and related biological responses along the west coast of India. Materials and Methods The study is based on the oceanographic data...

  18. Remote forcing annihilates barrier layer in southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Shankar, D.; Shetye, S.R.

    -1 GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, Remote forcing annihilates barrier layer in southeastern Arabian Sea S. S. C. Shenoi, D. Shankar, and S. R. Shetye National Institute of Oceanography, Goa, India. Time-series measurements... thick barrier layer (BL) exists during March{April ow- ing to a surface layer of low-salinity waters advected earlier during December{January from the Bay of Bengal. The BL is almost annihilated by 7 April owing to upwelling. The relic BL that survives...

  19. On the distribution of pelagic cephalopods in the Arabian Sea

    OpenAIRE

    Piatkowski, Uwe; Welsch, Wolfgang

    1991-01-01

    From April to June of 1987 R/V Meteor collected zooplankton and micronekton samples in the northeastern part of the Arabian Sea. One hundred and fifty-seven cephalopod specimens were captured by oblique IKMT hauls through water depths from 1,000 to 0 m and identified to the lowest possible taxon. Thirteen species of nine families were recorded. The majority of the specimens were early life stages of pelagic oceanic species. The cranchiid squid Liocranchia reinhardti was the dominant form (108...

  20. Nitrous oxide emissions from the Arabian Sea: A synthesis

    Digital Repository Service at National Institute of Oceanography (India)

    Bange, H.W.; Andreae, M.O.; Lal, S.; Law, C.S.; Naqvi, S.W.A.; Patra, P.K.; Rixen, P.K.; Upstill-Goddard, R.C.

    and Sarmiento, 2000). Here we present a comprehensive compilation of N2O measurements from the Arabian Sea surface layer from 1977 to 1997. These data were used to calculate mean seasonal and annual climatological N2O fields with a 1◦ latitude × 1◦ longitude... recalculated the Weiss et al. (1992) N2O concentrations with the reported water temperature, a mean seasonal salinity of 35.75, as calculated from climatologi- cal salinity data (see below), and an atmospheric pressure of 1 atm (Weiss and Price, 1980). We...

  1. Impact of tropical cyclone on biogeochemistry of the central Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, H.; Naqvi, S.W.A.; Suresh, T.; Narvekar, P.V.

    Remotely sensed data are combined with shipboard measurements to investigate biogeochemical changes caused by a moderate tropical cyclone in the central Arabian Sea in December 1998. The sea surface temperature decreased by approx. 4 degrees C...

  2. Reduced near-surface thermal inversions in 2005-06 in the southeastern Arabian Sea (Lakshadweep Sea)

    Digital Repository Service at National Institute of Oceanography (India)

    Nisha, K.; Rao, S.A.; Gopalakrishna, V.V.; Rao, R.R.; GirishKumar, M.S.; Pankajakshan, T.; Ravichandran, M.; Rajesh, S.; Girish, K.; Johnson, Z.; Anuradha, M.; Gavaskar, S.S.M.; Suneel, V.; Krishna, S.M.

    Repeat XBT transects made at near-fortnightly intervals in the Lakshadweep Sea (southeastern Arabian Sea) and ocean data assimilation products are examined to describe the year-to-year variability in the observed near-surface thermal inversions...

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

    Science.gov (United States)

    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.

  4. Downward flux of particulate fatty acids in the Central Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Reemtsma, T.; Haake, B.; Ittekkot, V.; Nair, R.R.; Brockmann, U.H.

    ) 183-202 183 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands Downward Flux of Particulate Fatty Acids in the Central Arabian Sea THORSTEN REEMTSMA 1 , BIRGIT HAAKE 1 , VENUGOPALAN ITTEKKOT 1, RAVINDRANATH R. NAIR 2 and UWE... fatty acids in the Central Arabian Sea. Mar. Chem., 29: 183-202. Particulate matter collected at 732 and 2914 m during a time-series sediment trap experiment (sampling interval 13 days ) in the Central Arabian Sea (14 ° 29'N, 64 ° 46'E; water depth...

  5. Surface buoyancy flux in Bay of Bengal and Arabian Sea

    Directory of Open Access Journals (Sweden)

    G. Anitha

    2008-03-01

    Full Text Available The seasonal variation of thermal, haline, net surface buoyancy flux, the Monin-Obukhov length (M-O length, L and stability parameter, i.e. the ratio of M-O length to mixed layer depth (h were studied in the Bay of Bengal (BoB and the Arabian Sea (AS for the years 2003 and 2004 using Argo temperature and salinity profiles. The relative quantitative influence of winds to surface buoyancy and the applicability of scaling mixed layer using M-O length in BoB and AS was brought out. Rotation and light penetration modify the mixed layer depth from M-O length during shoaling in spring giving L/h<1.

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

    Science.gov (United States)

    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.

  7. Climate oscillations reflected in the Arabian Sea subseafloor microbiome

    Science.gov (United States)

    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.

  8. Ecology and distribution of recent planktonic foraminifera in eastern part of Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.; Jayalakshmy, K.V.; Kutty, M.K.

    Thirty species of living planktonic foraminifera have been studied from 97 plankton tows collected from the eastern Arabian Sea with an accent on their ecological and distributional aspects. Species density is higher with less dominance in the deep...

  9. Directionality and spread of shallow water waves along the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Anoop, T.R.

    The directional characteristics of shallow water waves are described based on measured data during 2011 at two locations spaced at 350 km along the eastern Arabian Sea. Study shows that, for high swells (significant wave height > 1 m) approaching...

  10. Monsoon induced cobalt enrichment in Porites (coral) from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.A; Nath, B.N.

    Cobalt concentrations in growth bands of a reef building coral (Porites sp.) collected from Kalpeni Atoll of the Lakshadweep group of islands (Arabian Sea), rvealed that cobalt concentrations and Co/Ca ratios exhibit similar trend. Study indicates...

  11. Numerical experimentation of a diagnostic model of 3-D circulation in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shaji, C.; Bahulayan, N.; Dube, S.K.; Rao, A.D.

    Climatic circulation in the upper levels of the Arabian Sea and western equatorial Indian Ocean are computed using a 3-dimensional, 33 level diagnostic circulation model. A steady state solution is obtained within 30 days of model integration. Model...

  12. A note on the Pavonina flabelliformis D'Orbigny (benthic foraminifera) from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Khare, N.

    The detailed study of the inner shelf surface sediments off Karwar (India) revealed the occurrence of a benthic foraminiferal species Pavonina flabelliformis. This is the first report of this species in the Arabian Sea. The ecological set up of P...

  13. Marine sediments and palaeoclimatic variations since the Late Pleistocene: An overview for the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Hashimi, N.H.

    A large number of surfacial and sub-surface sediments from the Arabian Sea have been studied to enhance our understanding of palaeoclimatic variations over the Indian region. Bsically the surficial sediments have been studied for their living...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, P.; PrasannaKumar, S.

    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...

  15. Temporally invariable bacterial community structure in the Arabian Sea oxygen minimum zone.

    Digital Repository Service at National Institute of Oceanography (India)

    Jain, A.; Bandekar, M.; Gomes, J.; Shenoy, D.M.; Meena, R.M.; Naik, H.; Khandeparkar, R.; Ramaiah, N.

    The Northeastern Arabian Sea (NEAS) is a recognized region of intense denitrification, with a 200 to 1200 m anoxic water column. We studied the abundance of bacteria, viral particles and the bacterial community (BC), in addition to various chemical...

  16. Bacterial abundance and production in the central and eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Raghukumar, S.; Gauns, M.

    Seasonal and spatial variations in bacterial and picoplankton abundances and bacterial production (thymidine incorporation rates) were determined in the water column up to 150 m in several stations in the central and eastern Arabian Sea. Higher...

  17. Spatial distribution and general population characteristics of Pseudanchialina pusilla (Crustacea: Mysida) in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Biju, A.

    The distribution and general population characteristics of Pseudanchialina pusilla (Sars, 1883) were evaluated based on zooplankton collections obtained from different seasonal surveys conducted in 2004-2006 in the eastern Arabian Sea as part of a...

  18. Seafloor characterisation using echo peak amplitudes of multibeam hydrosweep system - A preliminary study at Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Sudhakar, T.

    In this paper an interface to acquire 59-beams echo peak amplitudes of the Hydrosweep Multibeam system is established. The echo peak amplitude values collected at varying seabed provinces of Arabian sea are presented. The study reveals...

  19. Seasonal and spatial variability in N sub(2)O distribution in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Patra, P.K.; Lal, S.; Venkataramani, S.; DeSousa, S.N; Sarma, V.V.S.S.; Sardessai, S.

    Extensive measurements of nitrous oxide (N sub(2)O) were made in the central and eastern Arabian Sea during the northeast monsoon (February-March), intermonsoon (April-May) and southwest monsoon (July-August) seasons. The latitudinal...

  20. Microdistribution of zooplankton in the neustonic realm of the eastern Arabian Sea during southwest monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Achuthankutty, C.T.; Nair, S.R.S.; Nair, V.R.; Padmavati, G.; Madhupratap, M.

    During the southwest monsoon season of 1987, the zooplankton distributions in the neustonic realm (upper 50 cm) of the eastern Arabian Sea were studied and compared with those in the water column. The upper microlayer (upper 15 cm) had generally...

  1. Phytoplankton production and chlorophyll distribution in the eastarn and central Arabian Sea in 1994-1995

    Digital Repository Service at National Institute of Oceanography (India)

    Bhattathiri, P.M.A.; Pant, A.; Sawant, S.S.; Gauns, M.; Matondkar, S.G.P.; Mahanraju, R.

    Measurements of primary production, chlorophyll a, particulate organic carbon (POC) and nitrogen (PON) were carried out during the inter-monsoon winter monsoon and summer monsoon seasons of 1994-95 in the central and eastern Arabian Sea...

  2. Arabian Sea Biogeochemistry from 27 August 1994 to 19 December 1994 (NODC Accession 0000064)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Arabesque was a multidisciplinary oceanographic research project focused on the Arabian Sea and Northwest Indian Ocean during the monsoon and intermonsoon season in...

  3. Secchi depth analysis using bio-optical parameters measured in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Naik, P.; Bandishte, M.; Desa, E.; Mascarenhas, A.A.M.Q.; Matondkar, S.G.P.

    Secchi depth provides the oceanographer with the first hand information about transparency and penetration of light in the water. Results of the Secchi depth and the optical properties measured in the Arabian Sea is presented. Our analyses show...

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

    Digital Repository Service at National Institute of Oceanography (India)

    VimalKumar, K.G.; DineshKumar, P.K.; Smitha, B.R.; Rahman, H.H.; Jacob, J.; Muraleedharan, K.R.; Sanjeevan, V.N.; Achuthankutty, C.T.

    . Achuthankutty Received: 30 September 2006 /Accepted: 3 July 2007 /Published online: 2 August 2007 # Springer Science + Business Media B.V. 2007 Abstract Seasonal variation of the hydrography along the southeast Arabian Sea is described using data collected...

  5. Productivity fluctuations in the southeastern Arabian Sea during the last 140 ka

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Toshiyuki Masuzawab; Naidu, P.D.; Parthiban, G.; Mineko Yamamoto

    Detailed analyses of multiple geochemical productivity proxies such as calcium carbonate, biogenic opal, biogenic Ba, organic carbon and total nitrogen have been carried out on a sediment core from the southeastern Arabian Sea to trace...

  6. Seasonal variability in distribution and fluxes of methane in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Patra, P.K.; Lal, S.; Venkataramani, S.; Gauns, M.; Sarma, V.V.S.S.

    Methane, a biogeochemically important gas in Earth's atmosphere was measured in the water column and air in the Arabian Sea in different seasons, viz., northeast monsoon, intermonsoon, and southwest monsoon, as part of the Joint Global Ocean Flux...

  7. Penaeoid and sergestoid shrimps from the deep scattering layer (DSL) in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Karuppasamy, P.K.; Menon, N.G.

    Results of a preliminary study on the occurrence and distribution of seventeen species of Penaeoid and Sergestoid shrimps from the deep scattering layer (DSL) of the Indian EEZ of Arabian Sea are presented here based on the IKMT samples collected...

  8. Studies on the microzooplankton from the central and eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Gauns, M.; Mohanraju, R.; Madhupratap, M.

    Numerical abundance and composition of microzooplankton in the upper 200 m were studied from the central and eastern Arabian Sea during three seasons. Protozoans, comprising of ciliates (loricates and aloricates), flagellates and sarcodines were...

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    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...

  10. Microbial iron reduction and methane oxidation in subsurface sediments of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, C.E.G.; Judith, M.; Gonsalves, M.J.B.D.; Nazareth, D.R.; Nagarchi, L.; Kamaleson, A.S.

    Arabian Sea is one of the most productive regions of the world's ocean with seasonal upwelling and a characteristic oxygen minimum zone. It receives a continuous input of windborne iron-rich dust which possibly stimulates phytoplankton productivity...

  11. Biogeochemistry of lead in the eastern Arabian Sea and western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Rejomon, G.; DineshKumar, P.K.; Bahulayan, N.

    Biogeochemical cycling of lead (Pb) within the Indian Exclusive Economic Zone of the Arabian Sea and Bay of Bengal was examined in terms of the dissolved and particulate Pb concentration profiles. The relative distribution of Pb between...

  12. Influence of northeasterly trade winds on intensity of winter bloom in the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, R.M.; Raman, M.; Parab, S.; Matondkar, S.G.P.; Nayak, S.

    Chlorophyll and wind pattern retrieved from remote sensing data have been used to study biological activity in the oceanic waters of Northern Arabian Sea (NAS) during February–March 2002–05. Occurrence of algal bloom in these waters during...

  13. Seasonal spreading of the Persian Gulf water mass in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Prasad, T.G.; Ikeda, M.; PrasannaKumar, S.

    The characteristics of the subsurface salinity maximum associated with the Persian Gulf Water mass (PGW) are used to quantify the spreading and mixing of PGW in the thermocline of the Arabian Sea based on a bimonthly climatology of temperature...

  14. Elemental (C, H, N) composition of zooplankton from north Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Bhat, K.L.; Ansari, Z.A.; Parulekar, A.H.

    Zooplankton samples collected from north Arabian Sea during March 1992 were analysed for elemental (C,H,N) composition. Estimated carbon, hydrogen and nitrogen concentrations displayed variations among different groups but their ratios were nearly...

  15. Sea surface temperature anomalies in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.

    . Further analysis has shown that the sea surface anomalies are well correlated to the anomalies of air temperature and latent heat flux values; whereas they are least correlated to the anomalies of wind stress and net radiation values, except over...

  16. Variability in biological responses influenced by upwelling events in the Eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Habeebrehman, H.; Prabhakaran, M.P.; Jacob, J.; Sabu, P.; Jayalakshmi, K.J.; Achuthankutty, C.T.; Revichandran, C.

    in the P. Sabu, K.J. Jayalakshmi, Systems er.com/locate/jmarsys compared to the surrounding area (Mantora et al.,1993). As a consequence of this enrichment, a high productivity occurs in the Arabian Sea during the season. The upwelling phenomenon... (LSM) summer monsoon. , Table 2 Phytoplankton species identified during the different phases of summer monsoon in the southeastern Arabian Sea Class: Bacillariophyceae Order: Dinophysales Family: RhizosoleniaceaeOrder: Biddulphiales Family...

  17. Global change in marine ecosystems: implications for semi-enclosed Arabian seas

    KAUST Repository

    Duarte, Carlos M.

    2015-12-07

    Global Change has been defined as the impact of human activities on the key processes that determine the functioning of the Biosphere. Global Change is a major threat for marine ecosystems and includes climate change as well as other global impacts such as inputs of pollutants, overfishing and coastal sprawl. The Semi-enclosed Arabian Seas, including the Arabian Gulf and the Red Sea, have supported human livelihoods in the Arabian Peninsula over centuries and continue to do so, but are also threatened by Global Change. These threats are particularly severe as Semi-enclosed Arabian Seas already present rather extreme conditions, in terms of temperature, salinity and oxygen concentration. The vulnerability of the unique marine ecosystems of the Semi-enclosed Arabian Seas to Global Change vectors is largely unknown, but predictions based on first principles suggest that they may be at or near the tipping point for many pressures, such as warming and hypoxia. There is an urgent need to implement international collaborative research programs to accelerate our understanding of the vulnerability of Semi-enclosed Arabian Seas to Global Change vectors in order to inform conservation and management plans to ensure these Seas continue to support the livelihoods and well-being of the Arab nations.

  18. Chlorophyll modulation of sea surface temperature in the Arabian Sea in a mixed-layer isopycnal general circulation model

    Digital Repository Service at National Institute of Oceanography (India)

    Nakamoto, S.; PrasannaKumar, S.; Muneyama, K.; Frouin, R.

    , embedded in the ocean isopycnal general circulation model (OPYC). A higher abundance of chlorophyll in October than in April in the Arabian Sea increases absorption of solar irradiance and heating rate in the upper ocean, resulting in decreasing the mixed...

  19. Chemistry of the sea-surface microlayer. 3. Studies on the nutrient chemistry of the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Singbal, S.Y.S.; Narvekar, P.V.; Nagarajan, R.

    Nutrients showed enrichment in the surface microlayer compared to those in sub-surface water and there was a decreasing trend in the enrichment factor from nearshore to offshore in Northern Arabian Sea. The nutrient concentrations were correlated...

  20. Monsoon control on trace metal fluxes in the deep Arabian Sea

    Indian Academy of Sciences (India)

    T M Balakrishnan Nair

    2006-08-01

    Particulate fluxes of aluminium,iron,magnesium and titanium were measured using six time-series sediment traps deployed in the eastern, central and western Arabian Sea. Annual Al fluxes at shallow and deep trap depths were 0.47 and 0.46 gm−2 in the western Arabian Sea,and 0.33 and 0.47 g m−2 in the eastern Arabian Sea. There is a difference of about 0.9-1.8gm−2 y−1 in the lithogenic fluxes determined analytically (residue remaining after leaching out all biogenic particles) and estimated from the Al fluxes in the western Arabian Sea. This arises due to higher fluxes of Mg (as dolomite) in the western Arabian Sea (6-11 times higher than the eastern Arabian Sea). The estimated dolomite fluxes at the western Arabian Sea site range from 0.9 to 1.35gm−2 y−1. Fe fluxes in the Arabian Sea were less than that of the reported atmospheric fluxes without any evidence for the presence of labile fraction/excess of Fe in the settling particles. More than 75% of Al, Fe, Ti and Mg fluxes occurred during the southwest (SW) monsoon in the western Arabian Sea. In the eastern Arabian Sea, peak Al, Fe, Mg and Ti fluxes were recorded during both the northeast (NE) and SW monsoons. During the SW monsoon, there exists a time lag of around one month between the increases in lithogenic and dolomite fluxes. Total lithogenic fluxes increase when the southern branch of dust bearing northwesterlies is dragged by the SW monsoon winds to the trap locations. However, the dolomite fluxes increase only when the northern branch of the northwesterlies (which carries a huge amount of dolomite accounting 60% of the total dust load) is dragged, from further north, by SW monsoon winds. The potential for the use of Mg/Fe ratio as a paleo-monsoonal proxy is examined.

  1. Nitrogen Uptake in the Northeastern Arabian Sea during Winter Cooling

    Directory of Open Access Journals (Sweden)

    S. Kumar

    2010-01-01

    Full Text Available The uptake of dissolved inorganic nitrogen by phytoplankton is an important aspect of the nitrogen cycle of oceans. Here, we present nitrate (NO3- and ammonium (NH4+ uptake rates in the northeastern Arabian Sea using 15N tracer technique. In this relatively underexplored region, productivity is high during winter due to supply of nutrients by convective mixing caused by the cooling of the surface by the northeast monsoon winds. Studies done during different months (January and late February-early March of the northeast monsoon 2003 revealed a fivefold increase in the average euphotic zone integrated NO3- uptake from January (2.3 mmolN m−2d−1 to late February-early March (12.7 mmolN m−2d−1. The f-ratio during January appeared to be affected by the winter cooling effect and increased by more than 50% from the southernmost station to the northern open ocean stations, indicating hydrographic and meteorological control. Estimates of NO3- residence time suggested that NO3- entrained in the water column during January contributed to the development of blooms during late February-early March.

  2. Estimation of eddy diffusivity coefficient of heat in the upper layers of equatorial Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Zavialov, P.O.; Murty, V.S.N.

    in the Central Equatorial Arabian Sea (CEAS). A comparison of the model computed K sub(h) values with those estimated from the heat balance of the upper layer (50 m) of the sea shows good agreement in the region of weak winds (CEAS) or low turbulent mixing regime...

  3. Physical and biological response of the Arabian sea to tropical cyclone Phyan and its implications

    Digital Repository Service at National Institute of Oceanography (India)

    Byju, P.; PrasannaKumar, S.

    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...

  4. Foraminiferal production and monsoonal upwelling in the Arabian sea: evidence from sediment traps

    Digital Repository Service at National Institute of Oceanography (India)

    Curry, W.B.; Ostermann, D.R.; Guptha, M.V.S.; Ittekkot, V.

    (18) O values by about 1%, accurately reflecting the average 4 degrees C sea surface temperature decrease associated with the upwelling. The mean value of delta super(18) O for G. ruber was greater in the western Arabian Sea than in the central...

  5. Modeling the barrier-layer formation in the South-Eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Durand, F.; Shankar, D.; DeBoyer Montegut, C.; Shenoi, S.S.C.; Blanke, B.; Madec, G.

    The effect of salinity on the formation of the barrier layer (BL) in the South-Eastern Arabian Sea (SEAS) is investigated using an ocean general circulation model. In accordance with previous studies, the runoff distribution and the India-Sri Lanka...

  6. Preliminary results of an acoustic tomography experiment (ATE-93) in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Somayajulu, Y.K.; Murty, T.V.R.; Navelkar, G.S.; Saran, A.K.; Almeida, A.M.; Murty, C.S.

    An acoustic transmission experiment was conducted in the eastern Arabian Sea by deploying two transceiver systems on deep sea moorings separatEd. by 270 km. The experiment lasted for a duration of ten days (2-12 May 1993). The acoustic transmissions...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  9. Ammonia oxidation rates and nitrification in the Arabian Sea

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  11. Dissolved aluminium in the surface microlayer of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Narvekar, P.V.; Singbal, S.Y

    -94 85 Elsevier Science Publishers B.V., Amsterdam Dissolved aluminium in the surface microlayer of the eastern Arabian Sea P.V. Narvekar and S.Y.S. Singbal National Institute of Oceanography, Dona Paula, Goa 403 004, India (Received 5 November 1991...; revision accepted 26 August 1992) ABSTRACT Narvekar, P.V. and Singbal, S.Y.S., 1993. Dissolved aluminium in the surface microlayer of the eastern Arabian Sea. Mar. Chem., 42: 85-94. Measurements of dissolved aluminium (A1) in surface microlayer (SML...

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

    Science.gov (United States)

    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

  13. Hydrography and water masses in the southeastern Arabian Sea during March-June 2003

    Indian Academy of Sciences (India)

    S S C Shenoi; D Shankar; G S Michael; J Kurian; K K Varma; M R Ramesh Kumar; A M Almeida; A S Unnikrishnan; W Fernandes; N Barreto; C Gnanaseelan; R Mathew; K V Praju; V Mahale

    2005-10-01

    This paper describes the hydrographic observations in the southeastern Arabian Sea (SEAS)during two cruises carried out in March –June 2003 as part of the Arabian Sea Monsoon Experiment.The surface hydrography during March –April was dominated by the intrusion of low-salinity waters from the south;during May –June,the low-salinity waters were beginning to be replaced by the high- salinity waters from the north.There was considerable mixing at the bottom of the surface mixed layer,leading to interleaving of low-salinity and high-salinity layers.The flow paths constructed following the spatial patterns of salinity along the sections mimic those inferred from numerical models.Time-series measurements showed the presence of Persian Gulf and Red Sea Waters in the SEAS to be intermittent during both cruises:they appeared and disappeared during both the fortnight-long time series.

  14. Sensing Seasonality in the Arabian Sea: a coupled δ18O-Mg/Ca approach

    Directory of Open Access Journals (Sweden)

    W. Feldmeijer

    2014-09-01

    Full Text Available Millennial scale climate variability punctuates the record of Northern Hemisphere glacials in the form of Dansgaard–Oeschger cycles. The coldest episodes within these cycles have a marked impact on the location of the Inter-tropical Convergence Zone and thereby the intensity and extent of the Asian monsoon system. Arabian Sea oceanography is closely linked to the monsoon cycle and responds rapidly to changes therein. Seasonally varying upwelling intensity, adhesive mixing and the resulting variability on sea surface temperature and salinity, however, make it challenging to precisely reconstruct the behaviour of the Indian monsoon system through the Dansgaard–Oeschger cycles. To reconstruct impact of millennial-scale changes in the monsoon on the Arabian Sea, paired single-specimen Mg/Ca and stable oxygen isotope analyses were performed on three species of planktonic foraminifera from the northern as well as the western Arabian Sea. Mismatches between Mg/Ca- and δ18O-derived temperatures reflect changes in salinity caused by regional variability in the hydrological cycle. Comparison of Mg/Ca-derived temperatures from Globigerinoides ruber, Globigerina bulloides and Neogloboquadrina dutertrei over Heinrich Event 4 and Interstadial 8 allows for reconstructing the seasonal range in temperatures (minima and maxima and vertical stratification of the water column during these intervals. Results show that Arabian Sea surface water temperatures were lower during the North Atlantic Heinrich Event 4, and that temperatures in the northern and western Arabian Sea differed relatively much. This implies that the north east monsoon (i.e. boreal winter was enhanced during this interval. In contrast, the summer upwelling related species G. bulloides reveals lower temperatures during Interstadial 8 in the western Arabian Sea, showing an enhanced summer monsoon during the warmers stages of millennial-scale climate variability. Together, these results show that

  15. Modeling of Regional Climate over Red Sea and Arabian Peninsula

    KAUST Repository

    Stenchikov, Georgiy L.

    2011-04-09

    Observations, re-analyses, and climate model simulations show strong surface temperature trends in Middle East and Arabian Peninsula in the last 30 years. Trends are especially pronounced in summer exceeding +1K/decade. However, some regions, e.g., the So

  16. Sea surface temperature changes during May and August in the western Arabian Sea over the last 22 kyr: Implications as to shifting of the upwelling season

    Digital Repository Service at National Institute of Oceanography (India)

    Godad, S.P.; Naidu, P.D.; Malmgren, B.A.

    In the western Arabian Sea (WAS), the highest seasonal sea surface temperature (SST) difference presently occurs between May and August. In order to gain an understanding on how monsoonal upwelling modulates the SST difference between these two...

  17. Seasonal sea surface temperature contrast between the Holocene and last glacial period in the western Arabian Sea (Ocean Drilling Project Site 723A): Modulated by monsoon upwelling

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Malmgren, B.A.

    Annual, summer, and winter sea surface temperatures (SSTs) in the western Arabian Sea were reconstructed through the last 22 kyr using artificial neural networks (ANNs) based on quantitative analyses of planktic foraminifera. Down-core SST estimates...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Naik, Dinesh K.; Nigam, R.; Gaur, A.S.

    ), 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...

  19. Locating Noctiluca miliaris in the Arabian Sea: An optical proxy approach

    Digital Repository Service at National Institute of Oceanography (India)

    Thibodeau, P.S.; Roesler, C.S.; Drapeau, S.L.; Matondkar, S.G.P.; Goes, J.I.; Werdell, P.J.

    was deployed in the Arabian Sea. An acclimated culture of T. pseudonana (CCMP 1335) was grown in sterile filtered L1 medium (a vitamin-, trace metal–, and nutrient-enriched seawater; Guillard and Hargraves 1993, as modified by Guillard and Morton 2003) under...

  20. Influence of orographically enhanced SW monsoon flux on coastal processes along the SE Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Raghavan, B.R.; Singh, K.; Rajawat, A.S.; Ajai; Kader, U.S.A.; Nayak, S.

    , 501-511. Chauhan, O. S., E. Vogelsang, N. Basavaiah, and U. S. A. Kader (2010), Reconstruction of the variability of the southwest monsoon during the past 3 ka, from the continental margin of the southeastern Arabian Sea, J. Quaternary Sci., 25...

  1. Arabian Sea upwelling - A comparison between coastal and open ocean regions

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; PrasannaKumar, S.

    The response of the eastern Arabian Sea to prevailing winds during an upwelling event, in the peak of southwest monsoon, was studied at both coastal and open ocean environment based on the data collected as a part of the Indian Joint Global Ocean...

  2. Late quaternary variability of the Arabian Sea monsoon and oxygen minimum zone

    NARCIS (Netherlands)

    Reichart, Gert-Jan

    1997-01-01

    The Monsoon Among the first Europeans observing the Asiatic monsoon was Alexander the Great during his campaign to the mouth of the Indus (325 B.C.). The oldest known records of the Arabian Sea monsoonal climate, however, are shipping documents, dated about 2300 B.C., which refer to the use of the s

  3. On the dynamics of the Lakshadweep high and low in the southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shankar, D.; Shetye, S.R.

    chain in the vicinity of where they form, propagate westward, extending across the southern Arabian Sea a few months after genesis. We investigate the dynamics of the high and low with an analytic model and with numerical simulations using a dynamical...

  4. Fluxes of amino acids and hexosamines to the deep Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Haake, B.; Ittekkot, V.; Ramaswamy, V.; Nair, R.R.; Honjo, S.

    Results of organic carbon, total nitrogen, amino acid and hexosamine of samples collected during time-series sediment trap in investigations in the Arabian Sea are presented. Samples were taken over a period of 1 1/2 years at two depths at each...

  5. Settling barium fluxes in the Arabian Sea: Critical evaluation of relationship with export production

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, T.M.B.; Ittekkot, V.; Shankar, R.; Guptha, M.V.S.

    919 and 2002 m water depth in the western Arabian Sea. This increase may be due either to barite formation within the fecal pellets of mesozooplankton thriving at deeper levels or to scavenging of Ba by Mn oxyhydroxides. Manganese oxyhydroxides seem...

  6. Seasonal variability of the observed barrier layer in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Thoppil, P.; Rao, R.R.; Muraleedharan, P.M.; Somayajulu, Y.K.; Gopalakrishna, V.V.; Murthugudde, R.; Reddy, G.V.; Revichandran, C.

    The formation mechanisms of the barrier layer (BL) and its seasonal variability in the Arabian Sea (AS) are studied using a comprehensive dataset of temperature and salinity profiles from Argo and other archives for the AS. Relatively thick BL of 20...

  7. The value of C sub(e) for the Arabian Sea during summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, A.S.; Sadhuram, Y.; Krishna, V.V.G.

    We estimate, from the moisture budget the bulk aerodynamic coefficient for latent heat flux (C sub(e)) during the monsoon season over the central Arabian Sea. The average value of C sub(e) under active monsoon conditions was found to be 2.25 x 10...

  8. Distribution and abundance of pelagic shrimps from the deep scattering layer of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Karuppasamy, P.K.; Menon, N.G.; Nair, K.K.C.; Achuthankutty, C.T.

    The sonic scattering layer (SSL) or deep scattering layer (DSL) of the eastern Arabian Sea of India is found in depths between surfaces to 750 m with varying thicknesses and in multiple layers. There is a distinct resident community of pelagic...

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    it possible to schedule the R/V Roger Revelle to work in the Arabian Sea in 2007. We thank the master and crews of the R/V Knorr and R/V Roger 15        Revelle, and Jim Moffett who was chief scientist on the Knorr. This work was supported...

  10. Physical control of primary productivity on a seasonal scale in central and eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Madhupratap, M.; DileepKumar, M.; Gauns, M.; Muraleedharan, P.M.; Sarma, V.V.S.S.; DeSouza, S.N.

    Using in situ data collected during 1992-1997, under the Indian programme of Joint Global Ocean Flux Study (JGOFS), it is shown that the biological productivity of the Arabian Sea is tightly coupled to the physical forcing mediated through nutrient...

  11. Contribution of mesoscale processes to nutrient budgets in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Resplandy, L.; Levy, M.; Madec, G.; Pous, S.; Aumont, O.; DileepKumar, M.

    We examine the impact of mesoscale dynamics on the seasonal cycle of primary production in the Arabian Sea with an eddy-resolving (1/12 degrees) bio-physical model. Comparison with observations indicates that the numerical model provides a realistic...

  12. Heat budget parameters for the southwestern Arabian Sea during monsoon - 88 experiment

    Digital Repository Service at National Institute of Oceanography (India)

    RameshBabu, V.; Gopalakrishna, V.V.; Sastry, J.S.

    The temporal evolution of heat budget parameters for the southwestern Arabian Sea shows that the net surface heat balance is negative (approx 70 Wm sup(-2)) in May 1988 (phase 1) mainly due to excessive latent heat loss over the radiation income...

  13. Seasonal variation of pteropods from the Western Arabian Sea sediment trap

    Digital Repository Service at National Institute of Oceanography (India)

    Mohan, R.; Verma, K.; Mergulhao, L.P.; Sinha, D.K.; Shanvas, S.; Guptha, M.V.S.

    Sediment trap samples collected from the Western Arabian Sea yielded a rich assemblage of intact and non-living (opaque white) pteropod tests from a water depth of 919 m during January to September 1993. Nine species of pteropods were recorded, all...

  14. Particulate organic carbon and particulate humic material in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.; Sarma, V.V.S.S.; DileepKumar, M.

    more towards south indicating accumulation of humic material. In contrast, PHM occurred in north than in south in intermonsoon. The north south trends cloud be seen in POC and PHM along 64 degrees E in the Arabian Sea. The POC levels were lower...

  15. Variations in swells along Eastern Arabian Sea during the summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Johnson, G.; SanilKumar, V.; Sanjiv, P.C.; Singh, J.; Pednekar, P.S.; AshokKumar, K.; Dora, G.U.; Gowthaman, R.

    A study was carried out to find the variation in wave characteristics along the eastern Arabian Sea and the influence of swells in the nearshore waves at 3 locations during summer monsoon in 2010. Percentage of swells in the measured waves was 75...

  16. Seasonal variations in inorganic carbon components in the central and eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.; DileepKumar, M.; George, M.D.; Rajendran, A.

    and convective mixing. The partial pressure of carbon dioxide (pCO sub(2)) in surface layers was generally in excess over the atmospheriec value, suggesting that the central and eastern Arabian Sea is a perennial source to atmospheric carbon dioxide. The flux...

  17. Premonsoonal water characteristics and cirulation in the east central Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshBabu, V.; Sastry, J.S.; Gopalakrishna, V.V.; RamaRaju, D.V.

    The hydrographic structure in the east central Arabian Sea during premonsoon period undergoes significant temporal change in the thermal field of upper 100 m, wherein temperature rises by about 0.5 degrees C on an average from May to June. The major...

  18. Reduced iron associated with secondary nitrite maxima in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Moffetta, J.W.; Goepferta, T.J.; Naqvi, S.W.A.

    Dissolved iron and Fe(II) were measured in the oxygen minimum zone (OMZ) of the Arabian Sea in September 2004. The OMZ is a well-demarcated feature characterized by high rates of denitrification, and a deep nitrite maximum coinciding with oxygen...

  19. Diurnal and semi-diurnal tidal currents in the deep mid-Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Gouveia, A.D.; Shetye, S.R.

    Current meter records from two depths, approximately 1000 m, at three mooring in the deep mid-Arabian Sea were used to study tidal components. Tidal ellipses for the semi-diurnal (M2, S2 and K2) and the diurnal (K1 and P1) tidal constituents have...

  20. Evaluation of toxic trace metals Cd and Pb in Arabian Sea waters

    Digital Repository Service at National Institute of Oceanography (India)

    Sanzgiri, S.; Mesquita, A.; Kureishy, T.W.; SenGupta, R.

    An attempt has been made to present a picture of the distribution of toxic trace elements Cd and Pb in the Northern Arabian Sea by applying an improved analytical technique for the detection of dissolved forms of the metals at nanogram levels...

  1. Zooplankton standing stock, community structure and diversity in the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; Srivastava, Y.

    The effects of large scale oil spill, which occurred during the Gulf War in 1991 on zooplankton standing stock, community structure and diversity in the northern Arabian Sea were studied. Surface (1-0 m) and vertical zooplankton hauls (200-0 m, 250...

  2. Observed low-frequency currents in the deep mid-Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; Shenoi, S.S.C.; Sundar, D.

    Current meter records form approximately 1000 and 3000 m at three moorings with a zonal separation of about 5 degrees along the 15 degrees N latitude in the mid-Arabian Sea during May 1986 to May 1987 have used to described the low...

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

    Science.gov (United States)

    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.

  4. Nutrients, chlorophyll, fractional primary productivity in water column of the North Arabian Sea in support of the North Arabian Sea Environment and Ecosystem Research from 1992-1994 (NODC Accession 0000778)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Five cruises were carried out under the Pak-US cooperative project 'North Arabian Sea Environment and Ecosystem Research' (NASEER) from 1992-1994. The main...

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

    Science.gov (United States)

    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.

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

    Digital Repository Service at National Institute of Oceanography (India)

    Rajasabapathy, R.; Mohandass, C.; VijayRaj, A.S.; Madival, V.V.; Meena, R.M.

    Author version: Polish J. Microbiol., vol.62(4); 2013; 391-400 Iron bacterial phylogeny and their execution towards iron availability in Equatorial Indian Ocean and Coastal Arabian Sea RAJU RAJASABAPATHY, CHELLANDI MOHANDASS*, AJAKKALAMOOLE...

  7. Zooplankton data collected from THOMAS G. THOMPSON in Arabian Sea; 19 August 1995 to 22 December 1995 (NODC Accession 9800200)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net casts in Arabian Sea from THOMAS G. THOMPSON. Data were collected from 19 August 1995 to 22 December 1995 by...

  8. Variability of subsurface denitrification and surface productivity in the coastal eastern Arabian Sea over the past seven centuries

    Digital Repository Service at National Institute of Oceanography (India)

    Agnihotri, R.; Kurian, S.; Fernandes, M.; Reshma, K.; DeSouza, W.; Naqvi, S.W.A

    Temporal variations over the last approx. 700 years in surface productivity and subsurface denitrification in the coastal eastern Arabian Sea (off Goa, India), a hydrographically unique environment that experiences seasonal near-bottom anoxia, have...

  9. Activity of the respiratory electron transport system and respiration rates within the oxygen minimum layer of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Shailaja, M.S.

    Measurements of the activity of the respirtory electron transport system (ETS) at 15 stations in the Arabian Sea during the northeast monsoon (December 1988) yield high respiration rates that do not correlate with the trends in primary productivity...

  10. An evaluation of physical and biogeochemical processes regulating perennial suboxic conditions in the water column of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.

    that oxygen minimum zone (OMZ) in the Arabian Sea is regulated largely by physical processes in association with biogeochemical cycling of oxygen. This results in perennial suboxic conditions in the water column with no significant seasonal variability...

  11. Mixed layer processes of the Arabian Sea Warm Pool during spring intermonsoon: a study based on observational and satellite data

    Digital Repository Service at National Institute of Oceanography (India)

    Sabu, P.; Revichandran, C.

    The relative importance and contribution of various processes in the total heat budget in the mixed layer of the Arabian Sea Warm Pool (ASWP) during spring intermonsoon (March–April 2004) were studied using in situ observations and satellite data...

  12. Zooplankton data collected from THOMAS G. THOMPSON in Arabian Sea; 18 September 1994 to 27 December 1995 (NODC Accession 9800077)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net casts in Arabian Sea from THOMAS G. THOMPSON. Data were collected from 18 September 1994 to 27 December 1995...

  13. Intrusion of the Bay of Bengal water into the Arabian Sea during winter monsoon and associated chemical and biological response

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Narvekar, J.; Kumar, A.; Shaji, C.; Anand, P.; Sabu, P.; Rijomon, G.; Josia, J.; Jayaraj, K.A.; Radhika, A.; Nair, K.K.C.

    Situated in similar latitudes and subjected to similar atmospheric forcing, the tropical basins of the Arabian Sea looses fresh water due to excess evaporation over precipitation while Bay of Bengal receives freshwater via excess rain and river run...

  14. Offshore limit of coastal ocean variability identified from hydrography and altimeter data in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, M.K.; Swamy, G.N.; Somayajulu, Y.K.

    In this communication, we describe a hitherto-unknown offshore limit to the coastal ocean variability signatures away from the continental shelf in the eastern Arabian Sea, based on hydrographic observations and satellite altimeter (TOPEX...

  15. Nitrogen transformations as inferred from the activities of key enzymes in the Arabian Sea oxygen minimum zone

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Narvekar, P.V.; Alagarsamy, R.; Naqvi, S.W.A.

    Vertical distributions of the potential activities of some key enzymes mediating nitrification and denitrification were investigated within the oxygen (O2) minimum zone of the Arabian Sea at a number of locations between latitudes 17 and 21°N...

  16. Reconstruction of the Holocene monsoon climate variability in the Arabian Sea based on alkenone sea surface temperature, primary productivity and denitrification proxies

    OpenAIRE

    Böll, A.

    2014-01-01

    The Indian monsoon climate influences large parts of the world’s population. But relatively little is known about its decadal to centennial scale variation at time scales of societal relevance. The aim of this study was to reconstruct the Holocene history of summer and winter monsoon variability in high-resolution by analyzing sediment cores from different locations in the Arabian Sea (northern Indian Ocean). Oceanic properties and biogeochemical processes in the Arabian Sea, such as sea surf...

  17. Physical control of primary productivity on a seasonal scale in the central and eastern Arabian Sea

    Indian Academy of Sciences (India)

    S Prasanna kumar; M Madhupratap; M Dileep kumar; M Gauns; P M Muraleedharan; V V S S Sarma; S N De Souza

    2000-12-01

    Using in situ data collected during 1992-1997, under the Indian programme of Joint Global Ocean Flux Study (JGOFS), we show that the biological productivity of the Arabian Sea is tightly coupled to the physical forcing mediated through nutrient availability. The Arabian Sea becomes productive in summer not only along the coastal regions of Somalia, Arabia and southern parts of the west coast of India due to coastal upwelling but also in the open waters of the central region. The open waters in the north are fertilized by a combination of divergence driven by cyclonic wind stress curl to the north of the Findlater Jet and lateral advection of nutrient-rich upwelled waters from Arabia. Productivity in the southern part of the central Arabian Sea, on the other hand, is driven by advection from the Somalia upwelling. Surface cooling and convection resulting from reduced solar radiation and increased evaporation make the northern region productive in winter. During both spring and fall inter-monsoons, this sea remains warm and stratified with low production as surface waters are oligotrophic. Inter-annual variability in physical forcing during winter resulted in one-and-a-half times higher production in 1997 than in 1995.

  18. A comparison of Globigerinoides ruber calcification between upwelling and nonupwelling regions in the Arabian Sea

    Indian Academy of Sciences (India)

    Sushant S Naik; Shital P Godad; P Divakar Naidu; V Ramaswamy

    2013-08-01

    Shell weights of planktonic foraminifera species Globigerinoides ruber in the size range of 300–355 μm were measured from sediment traps in the western and eastern Arabian Sea which represent upwelling and non-upwelling conditions respectively. In the Western Arabian Sea Trap (WAST), G. ruber flux ranged from 33.3 to 437.3#/m2/day and shell weights ranged from 6.7 to 14.2 g. Whereas, in the Eastern Arabian Sea Trap (EAST), flux ranged from 0.7 to 164.6#/m2/day and shell weights ranged from 10.4 to 14.8 g. Shell weights of G. ruber versus flux showed significant correlation at both the sites which reveals that shell calcification mainly depends on optimal growth conditions. Though the WAST and EAST location have distinct difference in pCO2 and sea surface temperature (SST), the shell weights of G. ruber are similar in these two regions which suggest that surface water pCO2 and SST do not show dominant influence on shell calcification on a seasonal timescale.

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

    Science.gov (United States)

    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

  20. Variability of the Arabian Sea upwelling and intensity of the oxygen minimum zone over the late Pleistocene and Holocene

    Science.gov (United States)

    Gaye, Birgit; Böll, Anna; Rixen, Tim; Emeis, Kay-Christian; Ramaswamy, Venkitasubramani

    2016-04-01

    The northern Arabian Sea is one of the main oceanic regions with a permanent low oxygen layer at intermediate water depth that results in water column denitrification. While glacial/interglacial variations in the Arabian Sea oxygen minimum zone (OMZ) are relatively well studied, little is known about the spatial and temporal extent of mid-water oxygen throughout the Holocene. We compared alkenone derived sea surface temperatures of the last 25 kyrs from a core in the northern Arabian Sea with a core from the monsoonal upwelling area off Oman. The difference between the two temperature reconstructions indicates that monsoonal upwelling occurred during warm interstadials and during the entire Holocene. δ15N curves show that denitrification also matched with monsoonal upwelling. Comparison of δ15N records from different locations in the Arabian Sea reveal a Holocene shift in the location of the core OMZ from the northwestern (early Holocene) to the northeastern Arabian Sea (late Holocene). This shift was caused by (i) spatial differences in oxygen demand, caused by changes in SW- and NE-monsoon intensities and associated productivity changes, as well as (ii) changes in mid-water ventilation facilitated by sea level rise and inflow of Persian Gulf and Red Sea Water leading and changes of ventilation by Indian Ocean Central Water .

  1. Deglacial temperature patterns in the Arabian Sea and mechanisms for Indian monsoon failure

    Science.gov (United States)

    Tierney, J. E.; Pausata, F. S. R.; deMenocal, P. B.

    2015-12-01

    Both paleoclimate data and climate model simulations demonstrate that the Indian monsoon system responds to remote coolings in the North Atlantic. The textbook examples are the stadial events associated with the last deglaciation — the Younger Dryas and Heinrich Stadial 1 — when the monsoon weakened dramatically and caused drying throughout the Indian Ocean rim. The mechanism by which the North Atlantic influences the monsoon system is not completely clear: locally cool SSTs, increases in continental albedo, and southward migration of the intertropical convergence zone have all been raised as possibilities. Here we synthesize biomarker and foraminiferal estimates of temperature to study the evolution of the Arabian Sea water column during the deglaciation and test hypotheses of monsoon failure during stadials. Alkenone and Mg/Ca data clearly indicate that the Arabian Sea cools during the YD and H1, although H1 cooling is partly obscured by the overall warming trend associated with orbital forcing and rising greenhouse gases. In contrast, TEX86 data record warmings during the YD and H1. The stark difference between the TEX86 response and the alkenone and foraminiferal data, as well as comparison with climate model simulations, indicates that TEX86 is most likely acting as a subsurface temperature proxy in the Arabian Sea over these timescales. Taken together, the paleoclimate data describe a pattern of surface cooling and subsurface warming in response to North Atlantic cooling. This oceanographic response is in excellent agreement with both timeslice and transient model simulations spanning the last deglaciation, and strongly supports the hypothesis that locally cool SSTs are a requisite for monsoon failure. Furthermore, subsurface warming causes a destratification of the Arabian Sea water column and provides a mechanism for previously observed reductions in productivity during stadial events.

  2. Ecology of fungi in the denitrification zones of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Manohar, C.S.

    obtained from the anoxic Mediterranean basin, anoxic Meromictic Lake sediment and marine anoxic Bolinas Lagoon DNA and a few common culturable forms such as Penicillium and Aspergillus sp. Three clusters were seen within the basidiomycota belonging... aspects of P450nor came from studying the gene sequence. A cDNA sequence revealed that the polypeptide was about 403 amino 114 Ecology of fungi in the denitrification zones of the Arabian Sea acid residues, corresponding to a molecular weight of 44...

  3. Size segregated aerosol mass concentration measurements over the Arabian Sea during ICARB

    Indian Academy of Sciences (India)

    Vijayakumar S Nair; K Krishna Moorthy; S Suresh Babu; K Narasimhulu; L Siva Sankara Reddy; R Ramakrishna Reddy; K Rama Gopal; V Sreekanth; B L Madhavan; K Niranjan

    2008-07-01

    Mass concentration and mass size distribution of total (composite) aerosols near the surface are essential inputs needed in developing aerosol models for radiative forcing estimation as well as to infer the environment and air quality. Using extensive measurements onboard the oceanographic research vessel, Sagar Kanya, during its cruise SK223B in the second phase of the ocean segment of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), the spatial distribution of the mass concentration and mass size distribution of near-surface aerosols are examined for the first time over the entire Arabian Sea, going as far as 58°E and 22°N, within a span of 26 days. In general, the mass concentrations () were found to be low with the mean value for the entire Arabian Sea being 16.7 ± 7 g m−3; almost 1/2 of the values reported in some of the earlier campaigns. Coarse mode aerosols contributed, on an average, 58% to the total mass, even though at a few pockets accumulation mode contribution dominated. Spatially, significant variations were observed over central and northern Arabian Sea as well as close to the west coast of India. In central Arabian Sea, even though the was quite low, contribution of accumulation aerosols to the total mass concentration was greater than 50%. Effective radius, a parameter important in determining scattering properties of aerosol size distribution, varied between 0.07 and 0.4 m with a mean value of 0.2 m. Number size distributions, deduced from the mass size distributions, were approximated to inverse power-law form and the size indices () were estimated. It was found to vary in the range 3.9 to 4.2 with a mean value of 4.0 for the entire oceanic region. Extinction coefficients, estimated using the number-size distributions, were well-correlated with the accumulation mode mass concentration with a correlation coefficient of 0.82.

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

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Roshin, R.P.; Narvekar, J.; DineshKumar, P.K.; Vivekanandan, E

    version: Marine Environmental Research: 68(5); 2009; 217-222 Response of the Arabian Sea to global warming and associated regional climate shift S. Prasanna Kumar 1* , Raj P. Roshin 1 , Jayu Narvekar 1 , P.K. Dinesh Kumar 2 and E. Vivekanandan 3...; winter temperature; wheat production; food quantity; vegetation cover. _____________________________________________________________ * Corresponding Author. S. Prasanna Kumar, Tel. +91 832 2450300; Fax +91 2450608, E-mail address: prasanna...

  5. Denitrification exceeds anammox as a nitrogen loss pathway in the Arabian Sea oxygen minimum zone

    Digital Repository Service at National Institute of Oceanography (India)

    Bulow, S.E.; Rich, J.J.; Naik, H.; Pratihary, A.K.; Ward, B.B.

    ��������������������������� ��� � ��� � ��� � ��� � ��� � ��� � � � � Denitrification exceeds Anammox as a nitrogen loss pathway in the Arabian Sea Oxygen Minimum Zone...

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

    Directory of Open Access Journals (Sweden)

    P. Jish Prakash

    2014-07-01

    Full Text Available 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.

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

    KAUST Repository

    Jish Prakash, P.

    2015-01-12

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Cristina Pomilla

    Full Text Available 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.

  10. Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea

    Institute of Scientific and Technical Information of China (English)

    MINU P; SHAJU S S; MUHAMED ASHRAF P; MEENAKUMARI B

    2014-01-01

    Remote sensing applications are important in the fisheries sector and efforts were on to improve the predic-tions of potential fishing zones using ocean color. The present study was aimed to investigate the phyto-plankton dynamics and their absorption properties in the coastal waters of the southeastern Arabian Sea in different seasons during the year 2010 to 2011. The region exhibited 73 genera of phytoplankton from 19 orders and 41 families. The numerical abundance of phytoplankton varied from 14.235×103 to 55.075×106 cells/L. Centric diatoms dominated in the region and the largest family identified was Thalassiosiraceae with main genera asSkeletonemaspp.,Planktionellaspp.andThalassiosiraspp. Annual variations in abun-dance of phytoplankton showed a typical one-peak cycle, with the highest recorded during premonsoon season and the lowest during monsoon season. The species diversity index of phytoplankton exhibited low diversity during monsoon season. Phytoplankton with pigments Chlorophylla, Chlorophyllb, Chlorophyll c, peridinin, diadinoxanthin, fucoxanthin,β-carotene and phycoerythrobilin dominated in these waters. The knowledge on phytoplankton dynamics in coastal waters of the southeastern Arabian Sea forms a key parameter in bio-optical models of pigments and productivity and for the interpretation of remotely sensed ocean color data.

  11. Spectral wave climatology off Ratnagiri, northeast Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, M.A; SanilKumar, V.

    -annual variations in the direction of swell are marginal (<10°), whereas significant variations in wind-sea are observed during June to November. Parameters of the JONSWAP and Donelan model spectra are estimated for the corresponding sea-state by using a least...

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

    Science.gov (United States)

    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.

  13. Aerosol mass loading over the marine environment of Arabian Sea during ICARB: Sea-salt and non-sea-salt components

    Indian Academy of Sciences (India)

    Susan K George; Prabha R Nair

    2008-07-01

    Mass loading and chemical composition of atmospheric aerosols over the Arabian Sea during the pre-monsoon months of April and May have been studied as a part of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB). These investigations show large spatial variabilities in total aerosol mass loading as well as that of individual chemical species. The mass loading is found to vary between 3.5 and 69.2 g m−3, with higher loadings near the eastern and northern parts of Arabian Sea, which decreases steadily to reach its minimum value in the mid Arabian Sea. The decrease in mass loading from the coast of India towards west is estimated to have a linear gradient of 1.53 g m−3/◦ longitude and an e−1 scale distance of ∼2300 km. SO$^{2−}_{4}$, Cl− and Na+ are found to be the major ionic species present. Apart from these, other dominating watersoluble components of aerosols are NO$^{−}_{3}$ (17%) and Ca2+ (6%). Over the marine environment of Arabian Sea, the non-sea-salt component dominates accounting to ∼76% of the total aerosol mass. The spatial variations of the various ions are examined in the light of prevailing meteorological conditions and airmass back trajectories.

  14. What drives the increased phytoplankton biomass in the Arabian Sea?

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Roshin, R.P.; Narvekar, J.; DineshKumar, P.K.; Vivekanandan, E.

    Sea during 1997-2007 showed a weak increasing trend. Contrary to the earlier hypothesis, our analysis showed that this increased phytoplankton biomass was not driven by the strengthening winds during summer monsoon. In fact, the basin...

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

    Science.gov (United States)

    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

  16. Impact of continental meteorology and atmospheric circulation in the modulation of Aerosol Optical Depth over the Arabian Sea

    Indian Academy of Sciences (India)

    Sandhya K Nair; S Sijikumar; S S Prijith

    2012-04-01

    Time series analysis of Aerosol Optical Depth (AOD) derived from NOAA-AVHRR data during the period 1996–1999 and the MODIS data during 2000–2009 over the Arabian Sea revealed a systematic biennial variability in the high AOD during summer months. The variability is more prominent over the northern and central parts of the Arabian Sea and became less significant towards southern latitudes. The possible mechanisms for these are examined by estimating the source strength over coastal Arabia and AOD flow rate through the western boundary of the Arabian Sea. Both these show clear signatures of biennial variability with same phase as AOD for most of the years. This result indicates that the observed biennial variability in AOD is likely to be the outcome of combined effects of biennial variability in wind generated sea-salt aerosols and dust transported from Arabia.

  17. Seasonal changes in the denitrification regime of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Noronha, R.J.; Somasundar, K.; SenGupta, R.

    of wind-induced vertical mixing in regulating new production. It also could result in part from possible differences in food webs (MICHAELS and SXt.VER, 1988). In any event, it appears that, contrary to the prevalent belief, upwelling may play a... and the z~icrobial food web. Deep- Sea Research, 35, 473-490. MtLLEnO F. J., C. T. CHEN, A. L. BV, ADSHAW and K. SCHLEICHER (1980) A new high pressure equation of state for seawater. Deep-Sea Research, 27,255--264. MINS'rER J. F. and M. BOULAHZ)ID (1987...

  18. Lithospheric and Upper-Mantle Structure of the Red Sea and Arabian Peninsula

    Science.gov (United States)

    Hansen, S. E.; Schwartz, S. Y.; Rodgers, A. J.; Gaherty, J. B.; Al-Amri, A. M.

    2007-12-01

    Using broadband seismic data recorded by various networks, a variety of techniques have been employed to investigate the lithospheric and upper-mantle structure of the Red Sea and Arabian Peninsula. This presentation will summarize our findings and conclusions about the tectonic evolution and current state of the Arabian Plate. S-wave receiver functions provide constraints on the lithospheric thickness and reveal very thin lithosphere (40-80 km) along the Red Sea coast, which thickens rapidly toward the interior of the Arabian Shield (100-120 km). A step of 20-40 km in lithospheric thickness is also observed at the Shield-Platform boundary. Mantle anisotropy has been analyzed using shear-wave splitting of teleseismic SKS waveforms. The consistent north-south oriented fast directions are not adequately explained by end-member models of fossilized anisotropy and present-day plate motion and have instead been explained by a combination of plate- and density-driven flow in the asthenosphere. Further constraints on the upper mantle velocity and anisotropy have been obtained by jointly inverting the receiver function constraints with frequency dependent surface wave phase delays. The results demonstrate that the thin lithospheric lid is underlain by a pronounced low-velocity zone and that anisotropy is required in both the lithosphere and asthenosphere. Attenuation and thermal estimates are also being explored and preliminary results will be presented. The combined results of these studies support a two-stage rifting history for the Red Sea, where extension and erosion by asthenospheric flow are responsible for variations in the lithospheric thickness. These lithospheric variations guide asthenospheric flow beneath western Arabia and the Red Sea, leading to a large-scale thermal anomaly that is associated with Cenozoic uplift and volcanism. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National

  19. The influence of Indian Ocean Dipole (IOD) on biogeochemistry of carbon in the Arabian Sea during 1997–1998

    Indian Academy of Sciences (India)

    V V S S Sarma

    2006-08-01

    Data on ocean color chlorophyll (Chl )obtained using Sea-viewing Wide Field of view Sensor (SeaWiFS),sea surface temperature (SST)by Advanced Very High Resolution Radiometer (AVHRR),and sea surface height (SSH)by TOPEX/POSEIDON were analyzed to examine the influence of Indian Ocean Dipole (IOD)on the physical and biogeochemical processes with special reference to phytoplankton primary production and air –sea fluxes of carbon dioxide in the Arabian Sea.Positive SST anomalies (SSTA)were found in the Arabian Sea (0.4 to 1.8°C) with higher values in the southwestern Arabian Sea that decreased towards north.The SSH anomalies (SSHA)and turbulent kinetic energy anomalies (TKEA)suggest decreased mixing during the IOD compared to the normal period.Chlorophyll displayed significant negative correlations with SSTA and SSHA in the Arabian Sea.Consistently, Chl showed negative anomalies (low Chl )during the IOD period which could be due to reduced inputs of nutrients.The photic zone integrated primary production decreased by 30%during the IOD period compared to the normal whereas pCO2 levels were higher (by 10-20 atm). However,sea to air fluxes were lower by 10% during the IOD period due to prevailing weaker winds.Primary production seems to be the key process controlling the surface pCO2 levels in the Arabian Sea.In future,the in fluence of IOD on ecosystem structure,export production and bacterial respiration rates are to be probed through in situ time-series observations.

  20. Shallow water wave spectral characteristics along the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Shanas, P.R.; Dubhashi, K.K.

    , Kruseman P, Meerburg A, Muller P, Olbers DJ, Richter K, Sell W, Walden H (1973) Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP). Deutsche Hydrograph. Z. A12,95 Hasselmann K, Ross DB, Miller P, Sell W...

  1. Chemical, temperature, pressure, and salinity data from bottle and CTD casts in the Arabian Sea as part of the Joint Global Ocean Flux Study / Arabian Sea Process Studies (JGOFS/Arabian) project, from 1995-07-17 to 1995-09-15 (NODC Accession 9800037)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Chemical, temperature, pressure, and salinity data were collected using bottle and CTD casts from the R/V Thomas G. Thompson in the Arabian Sea. Data were collected...

  2. Mesoscale variability of water masses in the Arabian Sea as revealed by ARGO floats

    Directory of Open Access Journals (Sweden)

    X. Carton

    2012-03-01

    Full Text Available By analysing ARGO float data over the last four years, a few aspects of the mesoscale variability of water masses in the Arabian Sea are described.

    The Red Sea Outflow Water (RSOW is concentrated in the Southwestern Gulf of Aden, in particular when a cyclonic gyre predominates in this region. Salinities of 36.5 and temperatures of 16 °C are found in this area at depths between 600 and 1000 m. RSOW is more dilute in the eastern part of the Gulf, where intense and relatively barotropic gyres mix it with Indian ocean Central Water. RSOW is also detected along the northeastern coast of Socotra, and fragments of RSOW are found between one and three degrees of latitude north of this island. In the whole Gulf of Aden, the correlation between the deep motions of the floats and the sea-level anomaly measured by altimetry is strong, at regional scale. The finer scale details of the float trajectories are not sampled by altimetry and are often related to the anomalous water masses that the floats encounter.

    The Persian Gulf Water (PGW is found in the float profiles near Ras ash Sharbatat (near 57° E, 18° N, again with 36.5 in salinity and about 18–19 °C in temperature. These observations were achieved in winter when the southwestward monsoon currents can advect PGW along the South Arabian coast. Fragments of PGW were also observed in the Arabian Sea between 18 and 20° N and 63 and 65° E in summer, showing that this water mass can escape the Gulf of Oman southeastward, during that season.

    Kinetic energy distributions of floats with respect to distance or angle share common features between the two regions (Gulf of Aden and Arabian Sea, in particular peaks at 30, 50 and 150 km scales and along the axis of monsoon currents. Hydrological measurements by floats are also influenced by the seasonal variations of PGW and RSOW in these regions.

  3. Study of Arabian Red Sea coastal soils as potential mineral dust sources

    KAUST Repository

    Prakash, P. Jish

    2016-03-23

    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 Red Sea Arabian coastal plane, which in turn will help to improve assessment of dust effect on the Red Sea and land environmental systems and urban centers. Thirteen surface soils from the hot-spot areas of wind-blown 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 wide 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

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

    Directory of Open Access Journals (Sweden)

    P. Lam

    2011-03-01

    Full Text Available 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

  5. Indian Ocean dipole modulated wave climate of eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Anoop, T.R.; SanilKumar, V.; Shanas, P.R.; Glejin, J.; Amrutha, M.M.

    short-period waves during positive IOD and an increase dur- ing negative IOD. 1 Introduction The northern Indian Ocean (IO) is a unique ocean as com- pared to northern Atlantic and Pacific oceans. Because of the land-locked northern boundary, the wind..., J. A., Gienapp, H., Hasselmann, D. E., Kruseman, P., Meerburg, A., Müller, P., Olbers, D. J., Richter, K., Sell, W., and Walden, H.: Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JON- www.ocean-sci.net/12...

  6. Biogeochemical significance of eddies of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rejomon, G.; DineshKumar, P.K.; Nair, M.

    in the mixed layer of the Eastern Tropical Pacific on the vertical transport of nitrate. – Deep Sea Research 33: 733- 754. [20] Koblentz-Mishke, O.J., Volkovinsky, V.V., Kabanova, J.C. (1970): Plankton primary production of the world ocean. – In: Scientific... of coastally trapped Kelvin waves and offshore-propagating Rossby waves (Vinayachandran and Yamagata, 1998; Smitha et al., 2008). Nevertheless, eddies, which are ubiquitous features throughout the world oceans (Ediger et al. 2005; Whitney et al., 2005; Marra...

  7. Analysis of chlorophyll pigment concentration in the northern Arabian Sea using remote sensing and GIS

    Digital Repository Service at National Institute of Oceanography (India)

    Thapa, S.

    out my would like to express my earnest gratitude and thankfulness to guide, Dr. ful completion of my work. e words have always been lacking for a person who has been a us source of inspiration and motivation for me. It is my proud rivilege... extended from15oN to 25oN latitude and 45oE to 75oE .3 ABOUT THE PROJECT AND MOTIVATION Since to regu vels in the atmosphere with its implication to many s at understanding the hyll pigment concentration in the Northern Arabian Sea. Since the winds over...

  8. Influence of particulate matter on microfouling biomass in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Nandakumar, K.; Wagh, A.B.

    ) Adsorprion ofmiuoorganisms to sllr/aces. John Wiley & Sons Inc, New York. pp. 59-104 Baier R E (\\984) Initial events in microbial film formation. In: Costlow J D, Tipper R C (OOs) Mari/le BiodetcriurotioJl. Anlntcrdi.\\ciplinary Stlld\\,. US :'-JavaI Institute... in the central Arabian Sea. Proc Indian ..lead Sci (J:artlr Planet Sci) 98: 1-13 Camerson D B, RobinsCln A V (1968) Prevention of bacterial corrosion of mild s\\eel with painl films. In: Second In/ematiullal COllgress 011 .i!aril1e Corrosioll alld Fouling. Tech...

  9. Why is the Bay of Bengal less productive during summer monsoon compared to the Arabian Sea?

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Muraleedharan, P.M.; Prasad, T.G.; Gauns, M.; Ramaiah, N.; DeSouza, S.N.; Sardessai, S.; Madhupratap, M.

    . 1. Introduction The Bay of Bengal in the eastern part of the north Indian Ocean is a tropical basin. Like its western counterpart, the Arabian Sea, it is land locked in the north and forced by seasonally reversing monsoon winds. Accordingly... summer data of two different years, is based on the fact that though semi-annual switching of the winds may have inter-annual variability, on the whole, the summer monsoon is a highly regular phenomenon [Fieux and Stommel, 1977]. 3. Results...

  10. Water vapour flux divergence over the Arabian Sea during 1987 summer monsoon using satellite data

    Digital Repository Service at National Institute of Oceanography (India)

    Vinayachandran, P.N.; RameshKumar, M.R.

    with the mean monsoon rainfall along the west coast of India. 1. Introduction A detailed study of the heat and moisture budget over the Indian Ocean, Arabian Sea and Bay of Bengal is crucial in understanding the mechanisms through which the Asiatic summer... monsoon is maintained (Murakami et al., 1984). Knowledge of water vapour flux divergence over the AS is of vital importance from the Indian summer monsoon point of view. An exact estimate of the contribution of the moisture flux from AS is essential...

  11. Spatial distribution of toxic and trace elements in coastal marine environment of Arabian Sea

    International Nuclear Information System (INIS)

    To understand the impact of anthropogenic activity on coastal marine environment in Arabian Sea, the sediment samples were collected covering the entire coastal line of two Indian states Gujarat and Maharashtra. The elemental concentration of K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Pb, Rb and Sr was determined using Energy Dispersive X-ray Fluorescence (EDXRF) technique. The concentration of Pb was found higher (33.3 mg kg-1) at Daman where as sediment collected from Okha gives highest concentration of Ni as 105 mg kg-1. The result indicates the impact of land based source of pollutant in the few locations due to the anthropogenic activities. (author)

  12. Westward movement of eddies into the Gulf of Aden from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Al Saafani, M.A.; Shenoi, S.S.C; Shankar, D.; Aparna, M.; Kurian, J.; Durand, F.; Vinayachandran, P.N.

    stream_size 44732 stream_content_type text/plain stream_name J_Geophys_Res_C_112_C11004.pdf.txt stream_source_info J_Geophys_Res_C_112_C11004.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 Westward... movement of eddies into the Gulf of Aden from the Arabian Sea M. A. Al Saafani, 1,2 S. S. C. Shenoi, 3 D. Shankar, 3 M. Aparna, 3 J. Kurian, 4 F. Durand, 2,5 and P. N. Vinayachandran 4 Received 18 November 2006; revised 6 April 2007; accepted 13 June 2007...

  13. Influence of a tropical cyclone on chlorophyll-a concentration in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, B; Rao, K.H.; Rao, N.S.; Murty, V.S.N.

    in the eastern Arabian Sea during 21– 28 May (Figure 1). As the weather system intensified, it moved in a northwesterly direction from 14C176N, 71.8C176Eon22 May to 17C176N, 68C176E on 26 May. After 26 May, the cyclone weakened gradually and moved towards north...Eto71C176E and centered at 15C176N, 71.5C176E withrelativelyhigherchlorophyll-ainthecycloneinfluenced region.Thebloomslooklikeround-shapedcycloniceddiesof 250–300kmdiameter(Figure3b).Thesebloomspersistwith graduallyreducedchlorophyllconcentrationstill3...

  14. Nutrient biogeochemistry of the eastern Arabian Sea during the southwest monsoon retreat

    Digital Repository Service at National Institute of Oceanography (India)

    George, R.; Muraleedharan, K.R.; Martin, G.D.; Sabu, P.; Gerson, V.J.; Dineshkumar, P.K.; Nair, S.M.; Chandramohanakumar, N.; Nair, K.K.C.

    � Chlorophyll a Introduction The west coast of India is environmentally unique because it is bordering one of the most sensitive ecosystems in the world, the Arabian Sea, is an important site of biogeo- chemical ocean–atmosphere transfers which plays a crucial..., together with those found off Peru and off California, as one of the most important of the World’s oceans. Per unit area these upwelling systems are among the most productive marine ecosystems in the glo- bal ocean (Ryther 1969) and, while occurring over...

  15. A cold pool south of Indo-Sri Lanka channel and its intrus on into the southeastern Arabian Sea during winter

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, R.R.; GirishKumar, M.S.; Ravichandran, M.; Gopalakrishna, V.V.; Pankajakshan, T.

    northwestward by the Maldives Island Chain. The resultant near-surface circulation also appears to strengthen the amplitude of the near-surface thermal inversions observed in the SouthEastern Arabian Sea (SEAS)...

  16. Association between premonsoonal SST anomaly field in the eastern Arabian Sea and subsequent monsoon rainfall over the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; RameshBabu, V.; Gopalakrishna, V.V.; Sarma, M.S.S.

    Interannual variability of premonsoonal (April-May) surface heat flux parameters together with sea surface temperature (SST) anomaly field in the eastern Arabian Sea has been examined for the period 1975-1984 in relation to the post onset (June...

  17. A multi-sensor study of conditions leading to the formation of a cyclone over the Arabian Sea during 5–9 May 2004

    Digital Repository Service at National Institute of Oceanography (India)

    Rameshkumar, M.R.; Byju, P.

    Objectively Analyzed air–sea Flux (OAFlux) project, European Centre for Medium Range Weather Forecast (ECMWF) data products and new tools, such as moored buoys and Argo floats, would be useful for the study of cyclones over the Arabian Sea....

  18. Study of Diurnal Cycle Variability of Planetary Boundary Layer Characteristics over the Red Sea and Arabian Peninsula

    KAUST Repository

    Li, Weigang

    2012-07-01

    This work is aimed at investigating diurnal cycle variability of the planetary boundary layer characteristics over the Arabian Peninsula and the Red Sea region. To fulfill this goal the downscaling simulations are performed using Weather Research and Forecasting (WRF) model. We analyze planetary boundary layer height, latent and sensible heat fluxes, and surface air temperature. The model results are compared with observations in different areas, for different seasons, and for different model resolutions. The model results are analyzed in order to better quantify the diurnal cycle variability over the Arabian Peninsula and the Red Sea. The specific features of this region are investigated and discussed.

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

    Science.gov (United States)

    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.

  20. Reconstruction of sea surface temperature variations in the Arabian Sea over the last 23 kyr using organic proxies (TEX86 and UK'37)

    NARCIS (Netherlands)

    Huguet, C.; Kim, J.-H.; Sinninghe Damsté, J.S.; Schouten, S.

    2006-01-01

    Two sediment cores from the western Arabian Sea, NIOP905 and 74KL, were analyzed to determine sea surface temperature (SST) variations over the last 23 kyr. Two organic molecular SST proxies were used, the well-established UK'37 based on long-chain unsaturated ketones synthesized by haptophyte algae

  1. Measurements of the ion concentrations and conductivity over the Arabian Sea during the ARMEX

    CERN Document Server

    Siingh, Devendraa; Gopalakrishnan, V; Kamra, A K

    2009-01-01

    Measurements of the small-, intermediate-, and large-ion concentrations and the atmospheric electric conductivity of both polarities have been made over the Arabian Sea on four cruises of ORV Sagarkanya during the Arabian Sea Monsoon Experiment (ARMEX)during the monsoon and pre-monsoon seasons of 2002 and 2003. Seasonally averaged values of the total as well as polar conductivity are much higher during the monsoon than pre-monsoon season. Surprisingly, however, the concentration of small ions are less and those of large and intermediate ions are more during the monsoon than pre-monsoon season. The diurnal variations observed during the pre-monsoon season show that the nighttime small ion concentrations are about an order of magnitude higher than their daytime values. On the contrary, the daytime concentrations of the intermediate and large ions are much higher than those of their nighttime values. No such diurnal variations in ion concentrations are observed in monsoon season. Also examined are the variations...

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

    Science.gov (United States)

    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.

  3. Investigation of Channel Modeling and Simulation of OFDM Based Communication Near Northern Regions of Arabian Sea

    Directory of Open Access Journals (Sweden)

    Rehan Khan

    2013-02-01

    Full Text Available Wideband nature of oceanic channel when dealing with multicarrier acoustic subcarriers introduces severe Doppler shifts, little variations may cause overlapping of subcarriers such that entire signal can get completely distorted. Therefore, one of the major problems in OFDM based underwater acoustic communication is the sensitive nature of wideband acoustic subcarriers. In this study, Bellhop beam tracing is used to model two regions in the north of Arabian Sea and the two-step receiver algorithm is used over these channel models. Multipath with delay channel model is obtained using the Bellhop ray tracing algorithm while random Doppler shift is induced in MATLAB on each block and also in the complete OFDM packet. In the first step, resembling converts a wideband problem in to narrowband problem and in the second step; high resolution Carrier Offset Frequency (CFO tracking compensates the residual Doppler. Cyclic Prefix (CP OFDM scheme based on block-by-block processing is deliberated here for fast varying channel. In the proposed algorithm, null subcarriers are facilitated for Doppler removal while pilot bits are used for Least Square (LS channel estimation. Simulation on MATLAB is carried out on both channels, i.e., near Gawadar Coast and Karachi Harbor; satisfactory results are achieved in terms Low Bit Error Rates (BER even in high relative speed between transmitter and receiver. These results further suggested and make convinced for the experimental test/ trials, specifically in the region of north Arabian Sea.

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

    Science.gov (United States)

    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 (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 in foraminifera was elevated. In summary

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    KAUST Repository

    Roberts, May B.

    2015-11-20

    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.

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

    Directory of Open Access Journals (Sweden)

    S. Sedigh Marvasti

    2015-07-01

    Full Text Available 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.

  9. On an upwelling front, propagation of upwelling and vertical velocity in the eastern Arabian sea during monsoon, 1987

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, M.K.; Unnikrishnan, A.S.

    A coastal upwelling front parallel to the coast and identifiable upto a depth of 75 m was observed between 12.5 and 16 degrees N along the eastern Arabian Sea in September, 1987 from closely spaced digital BT data. With a north-south slope...

  10. Dissimilatory nitrate reduction by Aspergillus terreus isolated from the seasonal oxygen minimum zone in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Stief, P.; Fuchs-Ocklenburg, S.; Kamp, A.; Manohar, C.S.; Houbraken, J.; Boekhout, T.; deBeer, D.; Stoeck, T.

    in prokaryotes. Here, we report on the anaerobic nitrate metabolism of the fungus Aspergillus terreus (isolate An-4) that was obtained from sediment in the seasonal oxygen minimum zone in the Arabian Sea, a globally important site of oceanic nitrogen loss...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Ahmed, A.; Kurian, S.; Gauns, M.; ChndrasekharaRao, A.V.; Mulla, A.; Naik, B.; Naik, H.; Naqvi, S.W.A.

    version: Cont. Shelf Res., vol.119; 2016; 30-39 Spatial variability in phytoplankton community structure along the eastern Arabian Sea during the onset of south-west monsoon Ayaz Ahmed, Siby Kurian, Mangesh Gauns*, Chndrasekhararao A.V, Amara Mulla...

  12. Distribution and relative quantification of key genes involved in fixed nitrogen loss from the Arabian Sea oxygen minimum zone

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, A.; Naqvi, S.W.A.; Ward, B.B.

    The Arabian Sea (AS) oxygen minimum zone (OMZ) is one of the largest pelagic low-oxygen environments in the open ocean. It is responsible for the removal of up to 60 Tg of nitrogen annually, roughly an eighth of the global fixed nitrogen sink...

  13. Study of ecological consequence of the bloom (Noctiluca miliaris) in off shore waters of the Northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, R.M.; Chauhan, R.; Solanki, H.U.; Raman, M.; Matondkar, S.G.P.; Madhu, V.R.; Meenakumari, B.

    during February-March 2008 and 2009 in off shore waters of the Northeastern Arabian Sea Fishing Schedule Location Depth (M) Total Catch (Kg) CPUE Kg/Day Latitude (deg-min) N Longitude (deg-min) E 8-13/03/08 19 o 20’ N 68 o 57’ E 900 2700 450 8...

  14. Carbonate and organic carbon content changes over last 20 ka in the Southeastern Arabian Sea: Paleoceanographic implications

    Digital Repository Service at National Institute of Oceanography (India)

    Narayana, A.C.; Naidu, P.D.; Shinu, N.; Nagabhushanam, P.; Sukhija, B.S.

    Two Gravity cores (AAS 38-4 and AAS 38-5) recovered from the eastern Arabian Sea were analyzed for calcium carbonate (CaCO3), organic carbon, aluminium (Al) and titanium (Ti) in order to understand the calcium carbonate and terrigenous fluctuations...

  15. Early- to late-Holocene contrast in productivity, OMZ intensity and calcite dissolution in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.S.; Godad, S.P.; Naidu, P.D.; Tiwari, M.; Paropkari, A.L.

    The Oxygen Minimum Zone (OMZ) is a potential source of CO2 to the atmosphere, and the extensive OMZ spread to 1.37 × 106 km2 in the Northern Arabian Sea would be an important contributor to the CO2 budget...

  16. Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

    NARCIS (Netherlands)

    Kraal, P.; Slomp, C.P.; Reed, D.C.; Reichart, G.-J.; Poulton, S.W.

    2012-01-01

    In this study, we investigate phosphorus (P) and iron (Fe) cycling in sediments along a depth transect from within to well below the oxygen minimum zone (OMZ) in the northern Arabian Sea (Murray Ridge). Pore-water and solid-phase analyses show that authigenic formation of calcium phosphate minerals

  17. Altimeter-derived flow field over a newly identified coastal ocean boundary in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, M.K.; Somayajulu, Y.K.; Swamy, G.N.

    part, tapers off towards north and bulges towards south. In the present communication, the T/P-derived flow pattern over this new boundary is presented. The derived flow pattern shows the general dominance of meso-scale eddies in the Arabian Sea...

  18. VM-ADCP measured upper ocean currents in the southeastern Arabian Sea and Equatorial Indian Ocean during December, 2000

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Suryanarayana, A.; Somayajulu, Y.K.; Raikar, V.; Tilvi, V.

    The Vessel-Mounted Acoustic Doppler Current Profiler (VM-ADCP) measured currents in the upper 200 m along the cruise track covering the southeastern Arabian Sea and the Eastern Equatorial Indian Ocean during northern winter monsoon (10-31 December...

  19. Enumeration of bacteria from a Trichodesmium spp. bloom of the eastern Arabian Sea: Elucidation of their possible role in biogeochemistry

    Digital Repository Service at National Institute of Oceanography (India)

    Basu, S.; Matondkar, S.G.P.; Furtado, I.

    The carbon-flux via algal bloom events involves bacteria as an important mediator. The present study, carried out during the spring inter-monsoon month of April 2008 onboard CRV Sagar Manjusha-06 in the Eastern Arabian Sea, addresses the bloom...

  20. Processes controlling forms of phosphorus in surficial sediments from the eastern Arabian Sea impinged by varying bottom water oxygenation conditions

    Digital Repository Service at National Institute of Oceanography (India)

    PrakashBabu, C.; Nath, B.N.

    in OMZ sediments from the NE Arabian Sea may indicate a higher degree of regeneration and diagenetic transformation of labile forms of P to other phases. Authigenic phosphorus (P sub(aut)) fraction varies by a factor of 2-8 in sediments from the OMZ when...

  1. Corrosion of metals and alloys in the coastal and deep waters of the Arabian Sea and the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Venkat, K.; Wagh, A.B.

    Corrosion rate of mild steel (MS), stainless steel (SS), copper, brass and cupro-nickel has been determinEd. by exposing metallic coupons in coastal and oceanic waters of the Arabian Sea and Bay of Bengal. Amongst the metals and alloys under study...

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

    Indian Academy of Sciences (India)

    Sumita Kedia; S Ramachandran

    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 ± 1 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 (∼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.

  3. Species diversity variations in Neogene deep-sea benthic foraminifera at ODP Hole 730A, western Arabian Sea

    Indian Academy of Sciences (India)

    Yuvaraja Arumugm; Anil K Gupta; Mruganka K Panigrahi

    2014-10-01

    Deep-sea benthic foraminifera are an important and widely used marine proxy to understand paleoceanographic and paleoclimatic changes on regional and global scales, owing to their sensitivity to oceanic and climatic turnovers. Some species of benthic foraminifera are sensitive to changes in water mass properties whereas others are sensitive to organic fluxes and deep-sea oxygenation. Benthic faunal diversity has been found closely linked to food web, bottom water oxygen levels, and substrate and water mass stability. The present study is aimed at analyzing species diversity trends in benthic foraminifera and their linkages with Indian monsoon variability during the Neogene. Species diversity of benthic foraminifera is examined in terms of number of species (S), information function (H), equitability (E) and Sanders’ rarefied values, which were combined with relative abundances of high and low productivity benthic foraminifera at Ocean Drilling Program Hole 730A, Oman margin, western Arabian Sea. The Oman margin offers the best opportunity to understand monsoon-driven changes in benthic diversity since summer monsoon winds have greater impact on the study area. The species diversity was higher during the early Miocene Climatic Optimum (∼17.2–16.4 Ma) followed by a decrease during 16.4–13 Ma coinciding with a major increase in Antarctic ice volume and increased formation of Antarctic Bottom Water. All the diversity parameters show an increase during 13–11.6 Ma, a gradual decrease during 11.6–9 Ma and then an increase with a maximum at 7 Ma. Thereafter the values show little change until 1.2 Ma when all the parameters abruptly decrease. The benthic foraminiferal populations and diversity at Hole 730A were mainly driven by the Indian monsoon, and polar waters might have played a minor or no role since early Neogene period as the Arabian Sea is an enclosed basin.

  4. Carbon and oxygen isotope time series records of planktonic and benthic foraminifera from the Arabian Sea: Implications on upwelling processes

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Niitsuma, N.

    prevails during the fall and spring inter- monsoonseasons.Therefore,theseasonalreversal of the wind direction and associated circulation pattern have a direct bearing on the biological productivity in the Arabian Sea (Kobanova, 1968... stable strati¢cation of the water column (Locke and Thunell, 1988). Thus during deglaciation Red Sea out£ow originated fromintermediatedepthinsteadofbottomwater. The intermediate waters were characterized by low nutrients and enriched 13 C(Locke and Thu...

  5. Comparative Profiling of coral symbiont communities from the Caribbean, Indo-Pacific, and Arabian Seas

    KAUST Repository

    Arif, Chatchanit

    2014-12-01

    Coral reef ecosystems are in rapid decline due to global and local anthropogenic factors. Being among the most diverse ecosystems on Earth, a loss will decrease species diversity, and remove food source for people along the coast. The coral together with its symbionts (i.e. Symbiodinium, bacteria, and other microorganisms) is called the ‘coral holobiont’. The coral host offers its associated symbionts suitable habitats and nutrients, while Symbiodinium and coral-associated bacteria provide the host with photosynthates and vital nutrients. Association of corals with certain types of Symbiodinium and bacteria confer coral stress tolerance, and lack or loss of these symbionts coincides with diseased or bleached corals. However, a detailed understanding of the coral holobiont diversity and structure in regard to diseases and health states or across global scales is missing. This dissertation addressed coral-associated symbiont diversity, specifically of Symbiodinium and bacteria, in various coral species from different geographic locations and different health states. The main aims were (1) to expand the scope of existing technologies, (2) to establish a standardized framework to facilitate comparison of symbiont assemblages over coral species and sites, (3) to assess Symbiodinium diversity in the Arabian Seas, and (4) to elucidate whether coral health states have conserved bacterial footprints. In summary, a next generation sequencing pipeline for Symbiodinium diversity typing of the ITS2 marker is developed and applied to describe Symbiodinium diversity in corals around the Arabian Peninsula. The data show that corals in the Arabian Seas are dominated by a single Symbiodinium type, but harbor a rich variety of types in low abundant. Further, association with different Symbiodinium types is structured according to geographic locations. In addition, the application of 16S rRNA gene microarrays to investigate how differences in microbiome structure relate to

  6. Climatical Characterization of Northern Arabian Sea for OFDM Based Underwater Acoustic Communication

    Directory of Open Access Journals (Sweden)

    Rehan Khan

    2013-07-01

    Full Text Available The effects of climatic changes on the Underwater Acoustic (UWA communication are addressed here with the aim to evaluate the performance of proposed scheme in the whole year specifically for the north Arabian Sea. Oceanic channel is a most challenging medium for the design of underwater wireless communication as it offers various unwanted degradations in terms of frequency-dependent attenuation, multipath spread, long path delays, etc. Multipath spread having extended delay spread further deteriorates the communication packet (s and in result, mutilation of entire signal, i.e., Inter-Symbolic Interference (ISI is occurred. Detailed analysis for the interaction of sound wave with the water mass is essential for the design of Underwater Acoustic (UWA communication. In particular, at varying temperature and warm surface site like Ormara, Pakistan (north-western region of Arabian Sea, where a very strong seasonal dependency may be observed due to climatic changes. OFDM, being the most feasible communication scheme and well suited for underwater environment is utilized in this study for the effect’s monitoring. In this study, we are presenting the effects of climate on the selected region of North-west Arabian Sea and validating our work on Zero Padded (ZP OFDM scheme for UWA communication. Relevant meteorological and oceanic data are obtained from open source buoy ARGOS ID 2901374 and Global ARGOS marine atlas (Worldwide tracking and environmental monitoring by satellite. For each of March, June, September and December we find a temperature and salinity with respect to the depth and subsequently calculate the sound speed in the specific channel. Bellhop ray tracing program is used to obtain the receiving path's amplitudes and delays for respective channel modeling and ZP OFDM based communication system. Simulation results explain the effects of climate in the transmission and endorse that ZP-OFDM is a viable choice for high-rate communications in

  7. Dinoflagellate Bloom of Karenia mikimotoi along the Southeast Arabian Sea, Bordering Western India

    Directory of Open Access Journals (Sweden)

    R. S. Robin

    2013-01-01

    Full Text Available A harmful algal bloom (HAB occurred along the southeast Arabian Sea, bordering Western India, during September to November 2004. This bloom was unique in the region in terms of its large spatial extent, and the trend was weakened towards November. Mass mortality of fish, emanation of noxious odour, and respiratory problems among the children on the coastal stretch were noticed. The phytoplankton species Gymnodiniium, class Dinophyceae bloom accounted for 98% of the standing crop. The bloom Karenia mikimotoi showed a maximum density of 19.37×104 cells L−1 and 18.94×104 cells L−1 at nearshore and offshore, respectively. The remotely sensed chlorophyll a (Chl a data from seaWiFS, sea surface temperature (SST from advanced very high resolution radiometer (AVHRR, rainfall from tropical rainfall measuring Mission (TRMM, and Sea winds from QuickSCAT reflected the bloom due to Karenia mikimotoi, suggesting the advection process at the coastal waters. The release of toxins specifically the neurotoxic shellfish poisoning (NSP and azaspiracid shellfish poisoning (AZP from the bloom was assessed by chemical and mouse bioassay of the extract from mussel Perna indica, showing negative results. These indicate that asphyxiation and abnormal mucus secreted by the K. mikimotoi led to clogging of gills that accentuated the mass fish kills.

  8. Aerosol characteristics at a remote island: Minicoy in southern Arabian Sea

    Indian Academy of Sciences (India)

    V Vinoj; S K Satheesh; K Krishna Moorthy

    2008-07-01

    Extensive measurements of aerosol optical and microphysical properties made at a remote island, Minicoy in southern Arabian Sea for the period (February 2006–March 2007) are used to characterize their temporal variability and Black Carbon (BC) mass mixing ratio. Large decrease in aerosol BC (from ∼800 ng m−3 to ∼100 ng m−3) was observed associated with change in airmass characteristics and monsoon rains. The total aerosol mass varied between ∼80 and 20 g m−3. Though the total mass fell drastically, a slight increase in super micron mass was observed during the June–August period associated with high winds. The mass fraction of Black Carbon aerosols during the prevalence of continental airmass is found to be ∼1.2% of the composite aerosols, which is much lower than the values reported earlier for this region.

  9. Distribution and abundance of marine debris along the coast of karachi (arabian sea), pakistan

    International Nuclear Information System (INIS)

    This study reports the first assessment of distribution and abundance of marine debris along the coast of Karachi (Arabian Sea), Pakistan. The quadrate method was used for estimating the debris material. Total 40 quadrates were made for collecting the debris on 4 beaches: Sandspit, Buleji, Paradise Point and Korangi Creek in the year of 2012. Nine different types of debris comprising of plastics, glasses, thermopore, clothing, rubber, paper, pot pieces and cigarette filters were collected. The study revealed that, plastic was found in high quantity at all four beaches of Karachi. Other most common items were as follow: plastic at Paradise Point and Sandspit; pot pieces at Korangi Creek and rubber at Buleji. A total weight of 12277.45 g debris was recorded during the whole study period. It was also noted that Paradise Point is the dirtiest beach (5612.6 g) when compared with other studied beaches. (author)

  10. A Study on Multi-Path Channel Response of Acoustic Propagation in Northwestern Arabian Sea

    Directory of Open Access Journals (Sweden)

    Gang Qiao

    2013-05-01

    Full Text Available Multi-path interference due to boundary reflection and variation of sound speed profile in underwater water acoustic communication pose the major barrier to reliable high-speed underwater communication system. Based on the sound speed profiles and the bathymetry data of northwestern Arabian Sea, Multipath impulse response profiles of the area have been obtained using Bellhop. The derived parameters like delay structure, effective transmit and receive angles suitable depths etc. from the obtained impulse responses have also been discussed. The impulse responses have been obtained for different scenarios of transmitter and receiver geometry to arrive at optimal configuration of wireless Acoustic communication/telemetry system for that area. This work can be used as a guide for the practical design of underwater acoustic wireless communication/telemetry system to be operated in this area which is critical to world oil exports.

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

    Science.gov (United States)

    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

  12. Seasonal controls on surface pCO2 in the central and eastern Arabian Sea

    Indian Academy of Sciences (India)

    V V S S Sarma; M Dileep Kumar; M Gauns; M Madhupratap

    2000-12-01

    The variability in partial pressure of carbon dioxide (pCO2) and its control by biological and physical processes in the mixed layer (ML) of the central and eastern Arabian Sea during inter-monsoon, northeast monsoon, and southwest monsoon seasons were studied. The ML varied from 80-120 m during NE monsoon, 60-80 m and 20-30 m during SW- and inter-monsoon seasons, respectively, and the variability resulted from different physical processes. Significant seasonal variability was found in pCO2 levels. During SW monsoon, coastal waters contain two contrasting regimes; (a) pCO2 levels of 520-685 atm were observed in the SW coast of India, the highest found so far from this region, driven by intense upwelling and (b) low levels of pCO2 (266 atm) were found associated with monsoonal fresh water influx. It varied in ranges of 416-527 atm and 375-446 atm during inter- and NE monsoon, respectively, in coastal waters with higher values occurring in the north. The central Arabian Sea pCO2 levels were 351-433, 379-475 and 385-432 atm during NE- inter and SW monsoon seasons, respectively. The mixed layer pCO2 relations with temperature, oxygen, chlorophyll and primary production revealed that the former is largely regulated by physical processes during SW- and NE monsoon whereas both physical and biological processes are important in inter-monsoon. Application of Louanchi et al (1996) model revealed that the mixing effect is the dominant during monsoons, however, the biological effect is equally significant during SW monsoon whereas thermodynamics and fluxes influence during inter-monsoons.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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 (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 provided an organic-rich food source for foraminifera at these sites. Our data suggest that foraminifera in OMZ settings can utilise a variety of food sources and metabolic pathways to meet their energetic demands.

  15. Chemical data collected from THOMAS G. THOMPSON using CTD and bottle casts in Arabian Sea from 08 January 1995 to 26 November 1995 (NODC Accession 9800161)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Chemical data were collected using CTD and bottle casts in the Arabian Sea from THOMAS G. THOMPSON. Data were collected from 08 January 1995 to 26 November 1995 by...

  16. Atypical delta sup(13) C signature in Globigerina bulloides at the ODP site 723A (Arabian Sea): Implications of environmental changes caused by upwelling

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Niitsuma, N.

    Production of Globigerina bulloides generally increases during upwelling in the tropical ocean and, in particular, during southwest monsoon season in the Arabian Sea. We studied the delta sup(13) C signatures of Globigerina bulloides from Ocean...

  17. Relationship between coccolith Sr/Ca ratios and coccolithophore production and export in the Arabian Sea and Sargasso Sea

    Science.gov (United States)

    Stoll, Heather M.; Ziveri, Patrizia; Shimizu, Nobumichi; Conte, Maureen; Theroux, Susanna

    2007-03-01

    Coccolithophore CaCO 3 production can account for 20-80% of biogenic carbonate exported from the photic zone, and coccoliths are a dominant biogenic carbonate in many deep-sea sediments. A new method for picking individual coccoliths from sediment traps and sediments for analysis using Secondary Ion Mass Spectrometry (ion probe) allows us to make precise Sr/Ca and Mg/Ca determinations on coccoliths from single species even in samples where material is limited. There are large biological effects in Sr/Ca partitioning in coccoliths that have been related to variations in coccolithophore productivity. In sediment traps from the Sargasso Sea at Bermuda and Arabian Sea in the Somali Basin, we can identify Sr/Ca variations in several species that are consistent with inferred seasonal variations in coccolithophore productivity in surface waters. In the Arabian Sea, coccolith Sr/Ca ratios in Calcidiscus leptoporus and Helicosphaera carteri are lowest during the nonproductive intermonsoon. They are highest during the upwelling of southwest monsoon and during the nutrient entrainment from strong winds of the northeast monsoon. These Sr/Ca variations match seasonal trends in coccolith export flux. Furthermore, Sr/Ca variations in C. leptoporus are larger, and this species also has the greater variation in export flux between southwest monsoon and intermonsoon seasons. At Bermuda, a 1996 fall bloom, driven by passage of a warm mode water eddy, induced a large increase in Sr/Ca of C. leptoporus coincident with an increase of C. leptoporus export. Over an annual series for 2004, highest Sr/Ca ratios of C. leptoporus in the summer months match the typical summer peak in surface standing stock of this species and the stimulation of its productivity by mesoscale cyclonic eddies and eddy-eddy interactions. High Sr/Ca did not coincide with the highest export of C. leptoporus coccoliths, likely because cyclonic eddies, unlike mode-water eddies, are dominated by small phytoplankton

  18. Effects of sea surface winds on marine aerosols characteristics and impacts on longwave radiative forcing over the Arabian Sea

    Directory of Open Access Journals (Sweden)

    Vijayakumar S. Nair

    2008-08-01

    Full Text Available Collocated measurements of spectral aerosol optical depths (AODs, total and BC mass concentrations, and number size distributions of near surface aerosols, along with sea surface winds, made onboard a scientific cruise over southeastern Arabian Sea, are used to delineate the effects of changes in the wind speed on aerosol properties and its implication on the shortwave and longwave radiative forcing. The results indicated that an increase in the sea-surface wind speed from calm to moderate (<1 to 8 m s−1 values results in a selective increase of the particle concentrations in the size range 0.5 to 5 μm, leading to significant changes in the size distribution, increase in the mass concentration, decrease in the BC mass fraction, a remarkable increase in AODs in the near infrared and a flattening of the AOD spectrum. The consequent increase in the longwave direct radiative forcing almost entirely offsets the corresponding increase in the short wave direct radiative forcing (or even overcompensates at the top of the atmosphere; while the surface forcing is offset by about 50%.

  19. The Dependency between the Arabian Peninsula Wet Events and Sea Level Pressure Patterns during Spring Season

    KAUST Repository

    El Kenawy, Ahmed M.

    2014-05-01

    This work investigates the relationships between regional extreme wet events in the Arabian Peninsula during the spring season (MAM) and sea level pressure (SLP) patterns. Based on NCEP/NCAR reanalysis data, S-mode principal components were computed from the de-seasonalized daily SLP for spring months between 1960 and 2013. The analysis covered a window for the region (15-70°E and 2.5-50°N). This window coupled different oceanic-land influences (e.g. the Indian, Mediterranean and the Sahara configurations) that may impart an effect on rainfall variations in the study domain. A set of eight significant circulation spatial patterns were retained, which explained 84.8% of the total explained variance. The derived patterns explained a wide variety of flows over the peninsula, with a clear distinction between zonal and meridional advections. The extreme wet events (R95 and R99) were defined from a relatively dense network of 209 observatories covering the peninsula, using the 95th and 99th percentile of rainfall distribution respectively. The links between the dominant SLP patterns and significant wet events were established and the physical interpretations of these associations were examined. The results, as revealed by the location and intensity of high pressure centers, highlight the strength of eastern and southeastern advections corresponding to these extreme events. Other patterns have a local character, suggesting an orographic origin of some wet events in the region. The relationships described in this research can advance the understanding of the large-scale processes that contribute to the wet weather events in the Arabian Peninsula. These findings can therefore contribute to better management of water resources and agricultural practices in the region.

  20. Carbon dioxide and water vapour characteristics on the west coast of Arabian Sea during Indian summer monsoon

    Indian Academy of Sciences (India)

    T Dharmaraj; M N Patil; R T Waghmare; P Ernest Raj

    2012-08-01

    Carbon dioxide, water vapour, air temperature and wind measurements at 10 Hz sampling rate were carried out over the coast of Arabian Sea, Goa (15°21′N, 73° 51′E) in India. These observations were collected, in association with the surface layer turbulent parameters for the Arabian Sea Monsoon Experiment (ARMEX). In the summer monsoon period, concentration of CO2 was in the range of 550–790 mg m−3 whereas the water vapour was in the range of 17.5–24.5 g m−3. The Fast Fourier Transform (FFT) analysis has been performed on these observations to investigate the spectral behaviour of CO2 and water vapour. The relation between CO2 and water vapour on various atmospheric scales has been proposed. CO2 and water vapour observations confirmed the existence of periodicities of large (11, 8 days), meso (5 days) and micrometeorological (20 min) scales.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Modeling a typical winter-time dust event over the Arabian Peninsula and the Red Sea

    KAUST Repository

    Kalenderski, S.

    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-1 and ?1.5 Tg day-1, 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 m-2, 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.

  3. Modeling a typical winter-time dust event over the Arabian Peninsula and the Red Sea

    Directory of Open Access Journals (Sweden)

    S. Kalenderski

    2013-02-01

    Full Text Available 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−1 and ~1.5 Tg day−1, 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 m−2, 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. Biogeographic Patterns of Reef Fish Communities in the Saudi Arabian Red Sea

    KAUST Repository

    Roberts, May B.

    2014-12-01

    As a region renowned for high biodiversity, endemism and extreme temperature and salinity levels, the Red Sea is of high ecological interest. Despite this, there is relatively little literature on basic broad scale characteristics of the biodiversity or overall reef fish communities and how they change across latitude. We conducted visual transects recording the abundance of over 200 species of fish from 45 reefs spanning over 1000 km of Saudi Arabian coastline and used hierarchical cluster analysis to find that for combined depths from 0m-10m across this geographical range, the reef fish communities are relatively similar. However we find some interesting patterns both at the community level across depth and latitude as well as in endemic community distributions. We find that the communities, much like the environmental factors, shift gradually along latitude but do not show distinct clusters within the range we surveyed (from Al-Wajh in the north to the Farasan Banks in the south). Numbers of endemic species tend to be higher in the Thuwal region and further south. This type of baseline data on reef fish distribution and possible factors that may influence their ranges in the Red Sea are critical for future scientific studies as well as effective monitoring and in the face of the persistent anthropogenic influences such as coastal development, overfishing and climate change.

  5. Summer monsoon intraseasonal oscillation over eastern Arabian Sea – as revealed by TRMM microwave imager products

    Indian Academy of Sciences (India)

    S H Rahman; B Simon

    2006-10-01

    The time evolution of atmospheric parameters on intraseasonal time scale in the eastern Arabian Sea (EAS) is studied during the summer monsoon seasons of 1998–2003 using Tropical Rainfall Measuring Mission Microwave Imager (TMI) data. This is done using the spectral and wavelet analysis. Analysis shows that over EAS, total precipitable water vapour (TWV) and sea surface wind speed (SWS) have a periodicity of 8–15 days, 15–30 days and 30–60 days during the monsoon season. Significant power is seen in the 8–15-day time scale in TWV during onset and retreat of the summer monsoon. Analysis indicates that the timings of the intensification of 8–15, 15–30, and 30–60 days oscillations have a profound effect on the evolution of the daily rainfall over west coast of India. The positive and negative phases of these oscillations are directly related to the active and dry spells of rainfall along the west coast of India. The spectral analysis shows interannual variation of TWV and SWS. Heavy rainfall events generally occur over the west coast of India when positive phases of both 30–60 days and 15–30 days modes of TWV and SWS are simultaneously present.

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

    Digital Repository Service at National Institute of Oceanography (India)

    Manohar, C.S.; Raghukumar, C.; Behnke, A.; Stoeck, T.

    Fungal diversity in oxygen-depleted regions of the Arabian Sea revealed by targeted environmental sequencing combined with cultivation Cathrine S Jebaraj 1, 2 , Chandralata Raghukumar 1 , Anke Behnke 2 , Thorsten Stoeck 2 1 National Institute... of Oceanography, (Council of Scientific and Industrial Research), Dona Paula, Goa 403 004, India; 2 School of Biology, University of Kaiserslautern, Kaiserslautern, Germany. Correspondence: Thorsten Stoeck, School of Biology, University of Kaiserslautern...

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

    Science.gov (United States)

    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.

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

    OpenAIRE

    Pitcher, A.; Villanueva, L; Hopmans, E.C.; Schouten, S.; G. J. Reichart; Sinninghe Damsté, J.S.

    2011-01-01

    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 ...

  9. Diversity of planktonic Ostracods (Crustacea: Ostracoda in the mixed layer of northeastern Arabian Sea during the summer monsoon

    Directory of Open Access Journals (Sweden)

    Jasmine Purushothaman

    2015-03-01

    Full Text Available Planktonic ostracods contribute significantly to the biomass of zooplankton in the Arabian Sea with an unusually high density due to swarming.  However, due to the small size, their abundance is often underestimated.  In this paper, the diversity of planktonic ostracods in the mixed layer depth of the northeastern Arabian Sea in relation to environmental parameters during the summer monsoon is presented.  The mean abundance in the mixed layer depth was very high.  About 26 species belonging to 17 genera representing two families were recognized.  Out of this, 25 species belonged to (3 sub families, 16 genera the order Myodocopa and one to the order Myodocopida.  The dominant species were Cypridina dentata, Euconchoecia aculeata, Conchoecia subarcuata and Orthoconchoecia atlantica.  Cypridina dentata and Euconchoecia aculeata contributed to about 89% of the total abundance.  The results suggest that the distribution and diversity of ostracods were very much influenced by the hydrographic conditions of the Arabian Sea during the summer monsoon. 

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

    Science.gov (United States)

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

    Directory of Open Access Journals (Sweden)

    R. M. Jeffreys

    2014-12-01

    Full Text Available 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 (−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

  12. Role of biology in the air–sea carbon flux in the Bay of Bengal and Arabian Sea

    Indian Academy of Sciences (India)

    M K Sharada; P S Swathi; K S Yajnik; C Kalyani Devasena

    2008-08-01

    A physical-biological-chemical model (PBCM)is used for investigating the seasonal cycle of air –sea carbon flux and for assessing the effect of the biological processes on seasonal time scale in the Arabian Sea (AS)and Bay of Bengal (BoB),where the surface waters are subjected to contrasting physical conditions.The formulation of PBCM is given in Swathi et al (2000),and evaluation of several ammonium-inhibited nitrate uptake models is given in Sharada et al (2005). The PBCM is here first evaluated against JGOFS data on surface pCO2 in AS, Bay of Bengal Process Studies (BoBPS)data on column integrated primary productivity in BoB,and WOCE I1 data on dissolved inorganic carbon (DIC)and alkalinity (ALK)in the upper 500 meters at 9°N in AS and at 10°N in BoB in September –October.There is good qualitative agreement with local quantitative discrepancies. The net effect of biological processes on air –sea carbon flux on seasonal time scale is determined with an auxiliary computational experiment,called the abiotic run,in which the biological processes are turned off.The difference between the biotic run and abiotic run is interpreted as the net effect of biological processes on the seasonal variability of chemical variables.The net biological effect on air –sea carbon flux is found to be highest in southwest monsoon season in the northwest AS, where strong upwelling drives intense new production.The biological effect is larger in AS than in BoB,as seasonal upwelling and mixing are strong in AS,especially in the northeast,while coastal upwelling and mixing are weak in BoB.

  13. The effect of Arabian Sea optical properties on SST biases and the South Asian summer monsoon in a coupled GCM

    Energy Technology Data Exchange (ETDEWEB)

    Turner, A.G.; Joshi, M.; Robertson, E.S.; Woolnough, S.J. [University of Reading, NCAS-Climate, Walker Institute for Climate System Research, Department of Meteorology, Reading (United Kingdom)

    2012-08-15

    This study examines the effect of seasonally varying chlorophyll on the climate of the Arabian Sea and South Asian monsoon. The effect of such seasonality on the radiative properties of the upper ocean is often a missing process in coupled general circulation models and its large amplitude in the region makes it a pertinent choice for study to determine any impact on systematic biases in the mean and seasonality of the Arabian Sea. In this study we examine the effects of incorporating a seasonal cycle in chlorophyll due to phytoplankton blooms in the UK Met Office coupled atmosphere-ocean GCM HadCM3. This is achieved by performing experiments in which the optical properties of water in the Arabian Sea - a key signal of the semi-annual cycle of phytoplankton blooms in the region - are calculated from a chlorophyll climatology derived from Sea-viewing Wide Field-of-View Sensor (SeaWiFS) data. The SeaWiFS chlorophyll is prescribed in annual mean and seasonally-varying experiments. In response to the chlorophyll bloom in late spring, biases in mixed layer depth are reduced by up to 50% and the surface is warmed, leading to increases in monsoon rainfall during the onset period. However when the monsoons are fully established in boreal winter and summer and there are strong surface winds and a deep mixed layer, biases in the mixed layer depth are reduced but the surface undergoes cooling. The seasonality of the response of SST to chlorophyll is found to depend on the relative depth of the mixed layer to that of the anomalous penetration depth of solar fluxes. Thus the inclusion of the effects of chlorophyll on radiative properties of the upper ocean acts to reduce biases in mixed layer depth and increase seasonality in SST. (orig.)

  14. Differential response of winter cooling on biological production in the northeastern Arabian Sea and northwestern Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Jyothibabu, R.; Maheswaran, P.A.; Madhu, N.V.; Asharaf, T.T.M.; Gerson, V.J.; Haridas, P.; Venugopal, P.; Revichandran, C.; Nair, K.K.C.; Gopalakrishnan, T.C.

    . Mohammed Ashraf, Vijay John Gerson, P. C. Haridas, P. Venugopal, C. Revichandran, K. K. C. Nair and T. C. Gopalakris h nan National Ins titute of Oceanography, Regional Centre, PB No. 1913, Kochi 682 018, I n dia The northern parts... basins, the Arabian Sea (AS) and the Bay of Bengal (BOB), is land - locked in the north by the Asian continent which separates the northern IO from the deep - reachin g vertical convection areas of the Arctic Seas and the cold climatic regions...

  15. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from the KNORR in the Andaman Sea or Burma Sea, Arabian Sea and others from 1994-12-01 to 1996-01-21 (NODC Accession 0115589)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115589 includes chemical, meteorological, physical and underway - surface data collected from KNORR in the Andaman Sea or Burma Sea, Arabian Sea,...

  16. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the KNORR in the Andaman Sea or Burma Sea, Arabian Sea and others from 1994-12-01 to 1996-01-23 (NODC Accession 0115009)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115009 includes chemical, discrete sample, physical and profile data collected from KNORR in the Andaman Sea or Burma Sea, Arabian Sea, Bay of...

  17. Bio-optical properties of gelbstoff in the Arabian Sea at the onset of southwest monsoon

    Indian Academy of Sciences (India)

    Wiebke Breves; Rainer Reuter

    2000-12-01

    As part of the German JGOFS Indian Ocean Programme, a cruise occurred in the Arabian Sea in May 1997 at the onset of the southwest monsoon. Data on gelbstoff, chlorophyll and tryptophan-like fluorescence as well as gelbstoff absorption were obtained. They indicate, that these optical parameters support the interpretation of hydrographic and biogeochemical conditions. Tryptophan-like fluorescence seems to be a useful indicator of changes in the constitution of the biomass. A comparison of gelbstoff absorption and fluorescence data from the upper 100 m reveals only a weak covariance. Special emphasis is given to the fit procedure used for retrieving the exponential slope of the spectral absorption coefficient. values with a mean of 0.016 nm-1 are found in the 350 to 480 nm wavelength range. A mean slope set to the frequently reported value of 0.014 nm-1 in the exponential description of gelbstoff absorption might lead to a systematic over/underestimation, and thus to systematic errors, if single-wavelength absorption values are extrapolated to other spectral regions on the basis of this parameter.

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

    Science.gov (United States)

    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.

  19. When biogeographical provinces collide: Hybridization of reef fishes at the crossroads of marine biogeographical provinces in the Arabian Sea

    KAUST Repository

    DiBattista, Joseph

    2015-04-01

    Aim: Suture zones are areas where closely related species from different biogeographical regions come into contact and interbreed. This concept originated from the study of terrestrial ecosystems but it remains unclear whether a similar phenomenon occurs in the marine environment. Here we investigate a potential suture zone from a previously unknown hybrid hotspot at the Socotra Archipelago (Yemen), located in the Arabian Sea, where fauna from the Red Sea, Gulf of Aden, Arabian Sea, western Indian Ocean and greater Indo-Polynesian Province intersect. Location: Red Sea, Gulf of Aden, Arabian Sea and Indian Ocean. Methods: Putative hybrid reef fish were identified based on intermediate coloration and morphology. Underwater observations and collections were conducted to determine: (1) whether parent species form heterospecific social groups or breeding pairs; (2) the sex and reproductive status of morphologically intermediate individuals; and (3) whether parent species were forming mixed species associations owing to a dearth of conspecific partners. To support hybrid status, morphologically intermediate and parental individuals were genotyped using mitochondrial DNA cytochrome c oxidase subunit I (COI), nuclear recombination-activating gene 2 (RAG2) and the nuclear TMO-4C4 (TMO) gene. Results: We observed putative hybrids involving 14 species from four reef fish families at Socotra. Most cases involved a parental species with a restricted distribution (e.g. Red Sea or Arabian Sea) and a broadly distributed Indo-Pacific species. In most cases, at least one of the parent species was rare at Socotra. Hybrid gene flow was largely unidirectional, and although introgression was rare, we found evidence that some butterflyfish and surgeonfish hybrids were fertile and formed breeding groups with parental species. Main conclusions: The rate of hybrid discovery at Socotra is much greater than that recorded elsewhere in the marine environment and involved both allopatric and

  20. Temperature, salinity, and other data from CTD casts in the Arabian Sea from the MANGEN and other platforms in support of the North Arabian Sea Environment and Ecosystem Research (NASEER) project from 10 January 1992 to 28 December 1994 (NODC Accession 0000512)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CTD data were collected in the Arabian Sea from the MANGEN and other platforms from 10 January 1992 to 28 December 1994. Data include profiles of temperature,...

  1. Temperature profile and water depth data collected from USNS SEALIFT ARABIAN SEA using BT and XBT casts in the NE/NW Pacific Ocean and other seas from 09 July 1986 to 15 February 1988 (NODC Accession 8800086)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and water depth data were collected using BT and XBT casts from the USNS SEALIFT ARABIAN SEA in the Northwest / Northeast Pacific Ocean,...

  2. The stratigraphic evolution of the Indus Fan and the history of sedimentation in the Arabian Sea

    Science.gov (United States)

    Clift, Peter; Gaedicke, Christoph; Edwards, Rosemary; Il Lee, Jae; Hildebrand, Peter; Amjad, Shahid; White, Robert S.; Schlüter, Hans-Ulrich

    The Indus Fan records the erosion of the western Himalayas and Karakoram since India began to collide with Asia during the Eocene, ~50 Ma. Multi-channel seismic reflection data from the northern Arabian Sea correlated to industrial well Indus Marine A-1 on the Pakistan Shelf show that sedimentation patterns are variable through time, reflecting preferential sedimentation in deep water during periods of lower sea-level (e.g., middle Miocene, Pleistocene), the diversion of sediment toward the east following uplift of the Murray Ridge, and the autocyclic switching of fan lobes. Individual channel-levee systems are estimated to have been constructed over periods of 105-106 yr during the Late Miocene. Sediment velocities derived from sonobuoys and multi-channel stacking velocities allow sections to be time-depth converted and then backstripped to calculate sediment budgets through time. The middle Miocene is the period of most rapid accumulation, probably reflecting surface uplift in the source regions and strengthening of the monsoon at that time. Increasing sedimentation during the Pleistocene, after a late Miocene-Pliocene minimum, is apparently caused by faster erosion during intense glaciation. The sediment-unloaded geometry of the basement under the Pakistan Shelf shows a steep gradient, similar to the continent-ocean transition seen at other rifted volcanic margins, with basement depths on the oceanward side indistinguishable from oceanic crust. Consequently we suggest that the continent-ocean transition is located close to the present shelf break, rather than >350 km to the south, as previously proposed.

  3. Observation of Oceanic Eddy in the Northeastern Arabian Sea Using Multisensor Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    R. K. Sarangi

    2012-01-01

    Full Text Available An oceanic eddy of size about 150 kilometer diameter observed in the northeastern Arabian Sea using remote sensing satellite sensors; IRS-P4 OCM, NOAA-AVHRR and NASA Quickscat Scatterometer data. The eddy was detected in the 2nd week of February in Indian Remote Sensing satellite (IRS-P4 Ocean Color Monitor (OCM sensor retrieved chlorophyll image on 10th February 2002, between latitude 16°90′–18°50′N and longitude 66°05′–67°60′E. The chlorophyll concentration was higher in the central part of eddy (~1.5 mg/m3 than the peripheral water (~0.8 mg/m3. The eddy lasted till 10th March 2002. NOAA-AVHRR sea surface temperature (SST images generated during 15th February-15th March 2002. The SST in the eddy’s center (~23°C was lesser than the surrounding water (~24.5°C. The eddy was of cold core type with the warmer water in periphery. Quickscat Scatterometer retrieved wind speed was 8–10 m/sec. The eddy movement observed southeast to southwest direction and might helped in churning. The eddy seemed evident due to convective processes in water column. The processes like detrainment and entrainment play role in bringing up the cooler water and the bottom nutrient to surface and hence the algal blooming. This type of cold core/anti-cyclonic eddy is likely to occur during late winter/spring as a result of the prevailing climatic conditions.

  4. Growth and Maturation of Plectropomus spp. in the Saudi Arabian Red Sea

    KAUST Repository

    DesRosiers, Noah

    2011-05-01

    Two species of plectropomid grouper (Plectropomus areolatus and P. pessuliferus) are found in the Red Sea. In Saudi Arabia these are the most valuable fishes by weight, averaging wholesale prices around US $15 per kilogram (personal observation). Over the past two decades, the number of fishing vessels in the Saudi Arabian Red Sea has tripled. Despite this increase in fishing effort Saudi Arabia has not implemented any marine resource management for Red Sea fisheries. Little biological data are currently available to inform managers. The research presented here addresses knowledge gaps on the growth pattern, longevity and sexual ontogeny of Plectropomus spp. in the Red Sea. Collections of each species were established by purchasing landed individuals from fishermen and fish markets distributed evenly between three latitudinal regions around the country. The total length of each fish was measured to the nearest millimeter. Age was estimated by enumerating annual bands visualized in transverse sections of sagittal otoliths. Sexual stage was determined via histological examination of gonadal tissue. Plots of total length versus age were fitted with reparameterized von Bertalanffy growth functions constrained to a size-at-settlement estimate of 20 mm. P. pessuliferus achieved a larger size (maximum 960 mm) and an older age (maximum 19 years) than P. areolatus (maximum size 570 mm, maximum age 9 years). While no regional patterns were found for P. pesuliferus, likelihood ratio tests revealed regional differences in growth pattern for P. areolatus, finding an increasing mean age, increasing mean length, and decreasing growth rate with decreasing latitude. In addition, males of P. areolatus were more abundant in the Southern region. These findings contradict existing theories about the effects of latitudinal temperature gradients on life history. It is hypothesized that the broader continental shelf in the Southern region may be providing a haven for these species in the

  5. The Role of Barrier Layer in Southeastern Arabian Sea During the Development of Positive Indian Ocean Dipole Events

    Institute of Scientific and Technical Information of China (English)

    GUO Feiyan; LIU Qinyu; ZHENG Xiao-Tong; SUN Shan

    2013-01-01

    Using data from Argo and simple ocean data assimilation (SODA),the role of the barrier layer (BL) in the southeastern Arabian Sea (SEAS:60°E-75°E,0°-10°N) is investigated during the development of positive Indian Ocean Dipole (IOD) events from 1960 to 2008.It is found that warmer sea surface temperature (SST) in the northern Indian Ocean appears in June in the SEAS.This warm SST accompanying anomalous southeastern wind persists for six months and a thicker BL and a corresponding thinner mixed layer in the SEAS contribute to the SST warming during the IOD formation period.The excessive precipitation during this period helps to form a thicker BL and a thinner mixed layer,resulting in a higher SST in the SEAS.Warm SST in the SEAS and cold SST to the southeast of the SEAS intensify the southeasterly anomaly in the tropical Indian Ocean,which transports more moisture to the SEAS,and then induces more precipitation there.The ocean-atmosphere interaction process among wind,precipitation,BL and SST is very important for the anomalous warming in the SEAS during the development of positive IOD events.

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

    Science.gov (United States)

    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

  7. Atmospheric deposition fluxes of 7Be, 210Pb and chemical species to the Arabian Sea and Bay of Bengal

    International Nuclear Information System (INIS)

    Aerosol samples collected close to the air-sea interface, between February 1997 to February 1999, over the Arabian Sea and Bay of Bengal were analyzed to determine the atmospheric dry-deposition of Fe (dust inputs), anthropogenic constituents (NO3-, SO42-) and environmental nuclides (7Be, 210Pb). In general, aerosol 210Pb concentrations showed a good correlation with 7Be, suggesting the long-range transport of 210Pb from the continents (via upper troposphere) and similarities in the processes governing their deposition through the marine boundary layer (MBL). The relatively low 7Be/210Pb ratios observed over the Bay of Bengal, during February 1999, are dominated by aerosol transport from the continental surface sources. The dry deposition fluxes of 210Pb and 7Be, to these two oceanic regions, average around 245 and 1860 Bq m-2 y-l, respectively. The non-sea-salt (nss) SO42- (range: 1.7 to 9.4 μg m-3) and NO3- (range: 0.6 to 4.1 μg m-3) are uncorrelated in the MBL, presumably because continental pollution sources for SO42- overwhelm the transport of NO3- from crustal dust and biomass burning. The oceanic biogenic emission (DMS) constitutes a very minor source for nss-SO42-. The enhanced concentrations of aerosol NO3- and Fe observed over the Arabian Sea are attributed to dust storm activities from the adjacent desert areas (Saudi Arabia and Thar). Significant scatter in the linear regression analyses indicate that the aerosol composition along the coastal tracks is different from those transported to the open ocean. On average, dry deposition fluxes of N-NO3 and non-marine SO42- are 150 and 1225 mg m-2 y-1, respectively. In contrast, dry deposition of Fe over the Arabian Sea (255 mg m-2 y-1) far exceeds that over the Bay of Bengal (93 mg m-2 y-1). Thus, dust from desert regions appears to be a potential source of micronutrients (Fe) to the surface Arabian Sea. (author)

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    P. L'Hégaret

    2015-03-01

    Full Text Available The Arabian Sea and Sea of Oman circulation and water masses, subject to the monsoon forcing, reveal a strong seasonal variability and intense mesoscale features. We describe and analyse this variability and these features, using both meteorological data (from ECMWF reanalyses, in-situ observations (from the ARGO float program and the GDEM climatology, satellite altimetry (from AVISO and a regional simulation with a primitive equation model (HYCOM. The EOFs of the seasonal variability of the water masses quantify their main changes in thermohaline characteristics and in position. The model and observations display comparable variability, and the model is then used to analyse the three-dimensional structure of eddies and water masses with a higher resolution. 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. This water mass is also captured inside the eddies via several mechanisms, keeping high thermohaline characteristics in the Arabian Sea. These characteristics are validated on the GOGP99 cruise data.

  10. Reconstruction of sea surface temperature variations in the Arabian Sea over the last 23 kyr using organic proxies (TEX86 and UK'37)

    OpenAIRE

    C. Huguet; Kim, J.-H.; Sinninghe Damsté, J.S.; Schouten, S.

    2006-01-01

    Two sediment cores from the western Arabian Sea, NIOP905 and 74KL, were analyzed to determine sea surface temperature (SST) variations over the last 23 kyr. Two organic molecular SST proxies were used, the well-established UK'37 based on long-chain unsaturated ketones synthesized by haptophyte algae and the newly proposed TEX86 derived from the membrane lipids of Crenarchaeota. Comparison of NIOP905 and 74KL core top data with present-day SST (0–10 m) values indicates that both proxies yield ...

  11. Reconstruction of sea surface temperature variations in the Arabian Sea over the last 23 kyr using organic proxies (TEX86 and U37K′)

    OpenAIRE

    Huguet, Carme; Kim, Jung-Hyun; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2006-01-01

    Two sediment cores from the western Arabian Sea, NIOP905 and 74KL, were analyzed to determine sea surface temperature (SST) variations over the last 23 kyr. Two organic molecular SST proxies were used, the well-established U37K′ based on long-chain unsaturated ketones synthesized by haptophyte algae and the newly proposed TEX86 derived from the membrane lipids of Crenarchaeota. Comparison of NIOP905 and 74KL core top data with present-day SST (0–10 m) values indicates that both proxies yield ...

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

    Science.gov (United States)

    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

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

    KAUST Repository

    Terraneo, Tullia Isotta

    2016-06-16

    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.

  14. Paleoenvironmental significance of clay mineral assemblages in the southeastern Arabian Sea during last 30 kyr

    Indian Academy of Sciences (India)

    Siddhartha Sankar Das; Ajai K Rai; Vaseem Akaram; Dhananjai Verma; A C Pandey; Koushik Dutta; G V Ravi Prasad

    2013-02-01

    A gravity core SK-221 recovered from the southeastern Arabian Sea near Laccadive–Chagos Ridge was examined to identify the sources of detrital clay minerals and to decipher paleoenvironmental changes for the last 30 kyr. The clay mineral assemblages predominantly consist of illite, kaolinite and chlorite with small amounts of smectite. Quartz, feldspar and occasionally gibbsite are the clay-sized non-clay minerals present in the examined section. The detrital clay minerals primarily originated from the hinterland and were supplied to the present site by the numerous small rivers draining western India during preglacial and Holocene periods, and partly by the strong reworking of Indian continental shelf during glacial period. The low values of humidity proxies (kaolinite content, kaolinite to illite and smectite to illite ratios) and better illite crystallinity indicate relatively weak summer monsoon condition that resulted in reduced chemical weathering during glacial period, which was interrupted by a discrete event of winter monsoon intensification at ∼20–17 ka. The increased kaolinite content, higher values of humidity indices and poorer illite crystallinity reflect high humidity that resulted in strong hydrolysis activity during the preglacial and Holocene periods. The increased CaCO3 during above periods also indicates less terrigenous dilution and intensified southwest monsoon-led upwelling which result in higher surface biogenic productivity. The characteristic clay mineral associations broadly suggest dry to semi-drier conditions during Heinrich Events H1, H2, and H3 and also during Younger Dryas. The low values of biogenic carbonate and organic carbon also indicate low productivity associated with weak summer monsoons during Heinrich Events. Abrupt increased humidity was recorded at 15–12.7 ka (Bølling/Allerød Event) sandwiched between two lows of Heinrich Events. Cycles of millennial timescale variations 2300, 1800, 1300 and 1000 yr have been

  15. Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Francis, C.A.; Naqvi, S.W.A.; Ward, B.B.

    the perennial oxygen minimum zone (OMZ) in © Inter-Research 2004 · www.int-res.com*Corresponding author. Email: bbw@princeton.edu Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea D. Amal Jayakumar 1 , Chris..., excess water was removed from the Sterivex using a syringe, and the capsule was capped using sealing clay and a luer lock cap, packed in polypropylene bags, and immediately frozen in liquid nitrogen. The samples were stored in liquid nitrogen, on dry ice...

  16. Phytoplankton, Bacteria and Heterotrophic Nanoflagellate studies using ship and OCM-2 data along a coastal transect in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Basu, S.; Parab, S.G.; Pednekar, S.; Niyati Hede, N.; Dwivedi, R.M.; Raman, M.; Babu, K.N.; Shukla, A.K.; Shirdhankar, M.M.

    predictable based upon insitu Chl a and Chl a retrieved by the OCM-II and other sensors. Of particular relevance to energy and material cycling in the marine habitat is the trophic relationship between algae and heterotrophic bacteria (Stewart et al. 2004..., Bacteria and Heterotrophic Nanoflagellate studies using ship and OCM-2 data along a coastal transect in the Arabian Sea S. G. Prabhu Matondkar 1 , S. Basu 1 , Sushma G. Parab 1 , Suraksha Pednekar 1 , Niyati Hede 1 , R. M. Dwivedi 2 , Mini Raman 2 , K...

  17. Evaporation-precipitation changes in the eastern Arabian Sea for the last 68 ka: Implications on monsoon variability

    Digital Repository Service at National Institute of Oceanography (India)

    Govil, P.; Naidu, P.D.

    , reconstructions of monsoon variability on glacial, interglacial and millennial time scales have been carried out using sediment cores from the western Arabian Sea (WAS). Most of these are based on indices for upwelling [Prell, 1984; Anderson and Prell, 1993... flow of low salinity Bay of Bengal water during MIS2. The strength of the SW monsoon appears to have been weaker during MIS2 than during MIS4 [Anderson and Prell, 1993], Consequently, evaporation was probably higher during MIS2 [Rostek et al., 1993...

  18. Designing Local-Scale Marine Protected Area Networks in the Central Saudi Arabian Red Sea

    KAUST Repository

    Khalil, Maha T.

    2015-12-01

    Coral reefs around the world are at risk from overexploitation and climate change, and coral reefs of the Red Sea are no exception. Science-based designation of marine protected areas (MPAs), within which human activities are restricted, has become a popular method for conserving biodiversity, restoring degraded habitats, and replenishing depleted populations. The aim of this project was to explore adaptable methods for designing locally-manageable MPAs for various conservation goals near Thuwal in the central Saudi Arabian Red Sea while allowing human activities to continue. First, the potential for using simple spatial habitat distribution metrics to aid in designing MPAs that are well-connected with larval supply was explored. Results showed that the degree of habitat patchiness may be positively correlated with realized dispersal distances, making it possible to space MPAs further apart in patchier habitats while still maintaining larval connectivity. However, this relationship requires further study and may be informative to MPA design only in the absence of spatially-explicit empirical dispersal data. Next, biological data was collected, and the spatial variation in biomass, trophic structure, biodiversity, and community assemblages on Thuwal reefs was analyzed in order to inform the process of prioritizing reefs for inclusion in MPA networks. Inshore and offshore reef community assemblages were found to be different and indicated relatively degraded inshore habitats. These trends were used to select species and benthic categories that would be important to conserve in a local MPA. The abundances of these “conservation features” were then modeled throughout the study area, and the decision support software “Marxan” was used to design MPA networks in Thuwal that included these features to achieve quantitative objectives. While achieving objectives relevant to fisheries concerns was relatively more challenging, results showed that it is possible to

  19. Heavy mineral variation in the deep sea sediment of southeastern Arabian Sea during the past 32 kyr

    Indian Academy of Sciences (India)

    Vaseem Akaram; S S Das; R K Rai; Gaurav Mishra

    2015-03-01

    The present study is based on heavy mineral assemblages (HM) of top 104-cm thick section of gravity core SK 221 (Lat. 8°7.12′N; Long. 73°16.38′E and water depth – 2188 m) located near the Chagos–Laccadive Ridge in the southeastern Arabian Sea to evaluate the provenance and paleoenvironmental changes during the last 32 kyr. The biogenic carbonate, acid insoluble residue, magnetic susceptibility, total organic carbon (TOC) and clay based humidity index, i.e., kaolinite/illite ratio are also utilized to correlate with the above paleoenvironmental changes. Ilmenite, garnet, staurolite, pyroxenes, andalusite and zircon are the dominant HM with moderate to low ZTR (zircon-tourmaline-rutile) index indicating instability of the sediments and rapid erosion in the source region. The characteristic HM suggest their mixed sources from the basic igneous, gneisses/granites, high grade metamorphic rocks and sandstones occurring mainly in the western and southwestern India. The temporal variations of HM, AIR (acid insoluble residue), MS (magnetic susceptibility), biogenic carbonate and Corg (TOC) during preglacial and early Holocene suggest intensive weathering, erosion, and transportation of terrigenous detritus from continental region by fluvial processes and summer monsoon led high biogenic productivity, respectively. The convective mixing of waters due to intense winter monsoon resulted in very high biogenic carbonate content during the early stages of glacial period. The HM and associated proxies indicated that the winter monsoons of Heinrich (H3, H2, and H1) and Younger Dryas (YD) events and summer monsoons of Bølling/Allerød (BA) event were not strong enough to bring drastic changes in the above parameters.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  2. Abundance and relationship of bacteria with transparent exopolymer particles during the 1996 summer monsoon in the Arabian Sea

    Indian Academy of Sciences (India)

    N Ramaiah; V V S S Sarma; M Gauns; M Dileep Kumar; M Madhupratap

    2000-12-01

    Bacterial abundance and production, numbers, sizes and concentrations of transparent exopolymer particles (TEP) and total organic carbon (TOC) were measured during the 1996 summer monsoon to understand the relationship between TEP, the most labile particulate organic carbon, and bacteria. While high regional variability in the vertical distribution of TOC was discernible, TEP concentrations were high in surface waters at 18-20°N along 64°E with concentrations well over 25 mg alginic acid equivalents 1-1 due to upwelling induced productivity. Their concentrations decreased with depth and were lower between 200 and 500 m. Bacterial concentrations were up to 1.99 × 108 1-1 in the surface waters and decreased by an order of magnitude or more at depths below 500 m. A better relationship has been found between bacterial abundance and concentrations of TEP than between bacteria and TOC, indicating that bacterial metabolism is fueled by availability of TEP in the Arabian Sea. Assuming a carbon assimilation of 33%, bacterial carbon demand (BCD) is estimated to be 1.017 to 4.035 g C m-2 d-1 in the surface waters. The observed TEP concentrations appear to be sufficient in meeting the surface and subsurface BCD in the northern Arabian Sea.

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

    Institute of Scientific and Technical Information of China (English)

    BASU Subhajit; MATONDKAR SG 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 ofNAS (20°N-17°N and 64°E-70°E),during the spring-inter-monsoon cruise ofSagar 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 NaC1),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%NaC1 (w/v),and (2.82-9.49)× 102 cells/mL at 25% (w/v) NaC1 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) NaC1,and (0.4-7)× 104 CFU/mL at 25% NaC1 (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,Bacillusflexus,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.

  4. Planktic foraminiferal shell thinning in the Arabian Sea due to anthropogenic ocean acidification?

    Directory of Open Access Journals (Sweden)

    H. de Moel

    2009-02-01

    Full Text Available About one third of the anthropogenic carbon dioxide (CO2 released into the atmosphere in the past two centuries has been taken up by the ocean. As CO2 invades the surface ocean, carbonate ion concentrations and pH are lowered. Laboratory studies indicate that this reduces the calcification rates of marine calcifying organisms, including planktic foraminifera. Such a reduction in calcification resulting from anthropogenic CO2 emissions has not been observed, or quantified in the field yet. Here we present the findings of a study in the Western Arabian Sea that uses shells of the surface water dwelling planktic foraminifer Globigerinoides ruber in order to test the hypothesis that anthropogenically induced acidification has reduced shell calcification of this species. We found that light, thin-walled shells from the surface sediment are younger (based on 14C and δ13C measurements than the heavier, thicker-walled shells. Shells in the upper, bioturbated, sediment layer were significantly lighter compared to shells found below this layer. These observations are consistent with a scenario where anthropogenically induced ocean acidification reduced the rate at which foraminifera calcify, resulting in lighter shells. On the other hand, we show that seasonal upwelling in the area also influences their calcification and the stable isotope (δ13C and δ18O signatures recorded by the foraminifera shells. Plankton tow and sediment trap data show that lighter shells were produced during upwelling and heavier ones during non-upwelling periods. Seasonality alone, however, cannot explain the 14C results, or the increase in shell weight below the bioturbated sediment layer. We therefore must conclude that probably both the processes of acidification and seasonal upwelling are responsible for the presence of light shells in the top of the sediment and the age

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  7. Comparative organic geochemistry of Indian margin (Arabian Sea sediments: estuary to continental slope

    Directory of Open Access Journals (Sweden)

    G. Cowie

    2014-02-01

    Full Text Available Surface sediments from sites across the Indian margin of the Arabian Sea were analysed for their carbon and nitrogen compositions (elemental and stable isotopic, grain size distributions and biochemical indices of organic matter (OM source and/or degradation state. Site locations ranged from the estuaries of the Mandovi and Zuari rivers to depths of ~ 2000 m on the continental slope, thus spanning nearshore muds and sands on the shelf and both the semi-permanent oxygen minimum zone (OMZ on the upper slope (~ 200–1300 m and the seasonal hypoxic zone that impinges on the shelf. Source indices showed mixed marine and terrigenous OM within the estuaries, and overwhelming predominance (80%+ of marine OM on the shelf and slope. Thus, riverine OM is heavily diluted by autochthonous marine OM and/or is efficiently remineralised within or immediately offshore of the estuaries. Any terrigenous OM that is exported appears to be retained in nearshore muds; lignin phenols indicate that the small terrigenous OM content of slope sediments is of different origin, potentially from rivers to the north. Organic C contents of surface shelf and slope sediments varied from < 0.5 wt % in relict shelf sands to over 7 wt % at slope sites within the OMZ, decreasing to ≤ 1 wt % at 2000 m. Major variability (~ 5 wt % was found at slope sites within the OMZ of similar depth and near-identical bottom-water oxygen concentration. A strong relationship between organic C and sediment grain size was seen for sediments within the OMZ, but lower C loadings were found for sites on the shelf and below the OMZ. Diagenetic indices confirmed that lower C content below the OMZ is associated with greater extent of OM degradation, but that C-poor shelf sediments are not consistently more degraded than those within the OMZ. Together, the results indicate that OM enrichment on the upper slope can be explained by physical controls (winnowing and/or dilution on the shelf and progressive OM

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.S.; Flagg, C.N.; Shi, Y. [Brookhaven National Lab., Upton, NY (United States). Oceanographic and Atmospheric Sciences Div.

    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.

  9. Indian satellite IRS-P4 (OCEANSAT). Monitoring algal blooms in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Bhat, S.R.; Dwivedi, R.M.; Nayak, S.R.

    While there have been a number of reports on occurrences of algal blooms in the coastal waters of India, the observation on large scale Noctiluca bloom during FORV Sagar Sampada cruises (years 2003 and 2004), forms the first report from NE Arabian...

  10. Validation of MODIS derived aerosol optical depth and an investigation on aerosol transport over the South East Arabian Sea during ARMEX-II

    Energy Technology Data Exchange (ETDEWEB)

    Aloysius, M.; Mohan, M.; Suresh Babu, S.; Parameswaran, K.; Krishna Moorthy, K. [Indian Space Research Organisation, Trivandrum (India). Space Physics Lab.

    2009-07-01

    The influence of wind and humidity on aerosol optical depth (AOD) over the Arabian sea is being investigated using MODIS (Moderate Resolution Imaging Spectroradiometer) Level 3 (Collection-5) and NCEP (National Centres for Environmental Prediction) reanalysis data for the second phase of the Arabian Sea Monsoon Experiment (ARMEX-II) over the South East Arabian Sea (SEAS) in the pre-monsoon period (14 March-10 April 2003). In order to qualify MODIS data for this study, MODIS aerosol parameters were first compared with ship borne Microtops measurements. This showed correlations 0.96-0.97 in the case of spectral AODs and a correlation 0.72 for the angstrom exponents. The daily AOD data from MODIS and winds from NCEP reveal that the ship observed episodic enhancement and decay of AOD at the TSL (Time Series Location) during 23 March-6 April 2003 was caused by the southward drift of an aerosol pocket driven by an intensification and reduction of surface pressure in the North Western Arabian Sea with a low altitude convergence prevailing over SEAS. The AOD increase coincided with a decrease in the Angstrom exponent and the fine mode fraction suggesting the pocket being dominated by coarse mode particles. A partial correlation analysis reveals that the lower altitude wind convergence is the most influential atmospheric variable in modulating AOD over the ARMEX-II domain during the TSL period. However, surface winds at a distant zone in the north/north west upwind direction also had a moderate influence, though with a lag of two days. But this effect was minor since the winds were not strong enough to produce marine aerosols matching with the high AODs over the ARMEX-II domain. These findings and the similarity between MODIS column mass concentration and the ship borne QCM (Quartz Crystal Microbalance) measured coarse mode mass concentration, suggest that the aerosol pocket was mostly composed of coarse mode mineral dust in the lower atmospheric altitudes transported from

  11. Absence of genetic differentiation in the coral Pocillopora verrucosa along environmental gradients of the Saudi Arabian Red Sea

    KAUST Repository

    Robitzch, Vanessa S.N.

    2015-02-11

    Arabian Seas.

  12. Absence of genetic differentiation in the coral Pocillopora verrucosa along environmental gradients of the Saudi Arabian Red Sea

    Directory of Open Access Journals (Sweden)

    Vanessa eRobitzch

    2015-02-01

    -Pacific and Arabian Seas.

  13. Coupling Between The North Indian Ocean And The Monsoons: A Model Based Study Of The Thermal Structure Cycling In The Central Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nayak, R.K.

    over the one-year period of the JGOFS time-series starting from mid-October 1994 in the central Arabian Sea at (61.5°E & 15.5°N). Atmospheric forcing data are available from the moored array observations (Weller et al. [2]). The horizontal advective...

  14. Reconstruction of the variability of the southwest monsoon during the past 3 ka, from the continental margin of the southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Vogelsang; Basavaiah, N.; Kader, U.S.A.

    . Sci., vol.25(5); 2010; 798-807 Reconstruction of the variability of SW monsoon during the past 3 Ka from the continental margin of the South Eastern Arabian Sea Onkar S. Chauhan 1 , Elke Vogelsang 2 , Nathani Basavaiah 3 , U. Syed Abdul Kader 1...

  15. On the marine atmospheric boundary layer characteristics over Bay of Bengal and Arabian Sea during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB)

    Indian Academy of Sciences (India)

    Denny P Alappattu; D Bala Subrahamanyam; P K Kunhikrishnan; K M Somayaji; G S Bhat; R Venkatesan; C B S Dutt; A Bagavath Singh; V K Soni; A S Tripathi

    2008-07-01

    Detailed measurements were carried out in the Marine Atmospheric Boundary Layer (MABL) during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) which covered both Arabian Sea and Bay of Bengal during March to May 2006. In this paper, we present the meteorological observations made during this campaign. The latitudinal variation of the surface layer turbulent fluxes is also described in detail.

  16. Late Quaternary paleoceanographic features as deduced from calcium carbonate and faunal changes of planktonic foraminifers in core samples from northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.; Jayalakshmy, K.V.; Singh, A.D.

    Two pelagic core samples, ARB-52 and ARB-54 from 2240 m and 800 m depths respectively from the Arabian Sea off Bombay were analysed for determining climatic changes during the past 30,000 yr. based on the interpretation of changes in calcium...

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

    Directory of Open Access Journals (Sweden)

    S. W. A. Naqvi

    2010-07-01

    Full Text Available 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.

  18. Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

    Directory of Open Access Journals (Sweden)

    P. Kraal

    2012-07-01

    Full Text Available In this study, we investigate phosphorus (P and iron (Fe cycling in sediments along a depth transect from within to well below the oxygen minimum zone (OMZ in the northern Arabian Sea (Murray Ridge. Pore-water and solid-phase analyses show that authigenic formation of calcium phosphate minerals (Ca-P is largely restricted to where the OMZ intersects the seafloor topography, likely due to higher depositional fluxes of reactive P. Nonetheless, increased ratios of organic carbon to organic P (Corg/Porg and to total reactive P (Corg/Preactive in surface sediments indicate that the overall burial efficiency of P relative to Corg decreases under the low bottom water oxygen concentrations (BWO in the OMZ. The relatively constant Fe/Al ratio in surface sediments along the depth transect suggest that corresponding changes in Fe burial are limited. Sedimentary pyrite contents are low throughout the ~25 cm sediment cores at most stations, as commonly observed in the Arabian Sea OMZ. However, pyrite is an important sink for reactive Fe at one station in the OMZ. A reactive transport model (RTM was applied to quantitatively investigate P and Fe diagenesis at an intermediate station at the lower boundary of the OMZ (bottom water O2: ~14 μmol L−1. The RTM results contrast with earlier findings in showing that Fe redox cycling can control authigenic apatite formation and P burial in Arabian Sea sediment. In addition, results suggest that a large fraction of the sedimentary Ca-P is not authigenic, but is instead deposited from the water column and buried. Dust is likely a major source of this Ca-P. Inclusion of the unreactive Ca-P pool in the Corg/P ratio leads to an overestimation of the burial efficiency of reactive P relative to Corg along the depth transect. Moreover, the unreactive Ca-P accounts for ~85% of total Ca-P burial. In general, our results reveal

  19. Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

    Directory of Open Access Journals (Sweden)

    P. Kraal

    2012-03-01

    Full Text Available In this study, we investigate phosphorus (P and iron (Fe cycling in sediments along a depth transect from within to well below the oxygen minimum zone (OMZ in the northern Arabian Sea (Murray Ridge. Pore-water and solid-phase analyses show that authigenic formation of calcium phosphate minerals (Ca-P is largely restricted to where the OMZ intersects the seafloor topography, likely due to higher depositional fluxes of reactive P. Nonetheless, increased ratios of organic carbon to organic P (Corg/Porg and to total reactive P (Corg/Preactive in surface sediments indicate that the overall burial efficiency of P relative to Corg decreases under the low bottom water oxygen concentrations (BWO in the OMZ. The relatively constant Fe/Al ratio in surface sediments along the depth transect suggest that corresponding changes in Fe burial are limited. Sedimentary pyrite contents are low throughout the ~25-cm sediment cores at most stations, as commonly observed in the Arabian Sea OMZ. However, pyrite is an important sink for reactive Fe at one station in the OMZ. A reactive transport model (RTM was applied to quantitatively investigate P and Fe diagenesis at an intermediate station at the lower boundary of the OMZ (bottom water O2: ~14 μ mol l−1. The RTM results contrast with earlier findings in showing that Fe redox cycling can control authigenic apatite formation and P burial in Arabian Sea sediment. In addition, results suggest that a large fraction of the sedimentary Ca-P is not authigenic, but is instead deposited from the water column and buried. Dust is likely a major source of this Ca-P. Inclusion of the unreactive Ca-P pool in the Corg/P ratio leads to an overestimation of the burial efficiency of reactive P relative to Corg along the depth transect. Moreover, the unreactive Ca-P accounts for ~85% of total Ca-P burial. In general, our results reveal

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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 (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 (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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    L. Pozzato

    2013-06-01

    Full Text Available 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.

  5. Sea truth validation of sea WiFS ocean colour sensor in the coastal waters of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.S.; Suresh, T.; Matondkar, S.G.P.; Desa, E.

    SeaWifs/OCM wavebands that are on the in - water unit. Both wet and dry radiometers connect to a deck control unit that synchronizes the acquisition of the 21 channels of data, receives the data streams and r e transmits them to a log... Ed (0 ? ) = 0.96 Ed (0 + ) from Smith and Baker 7 could be used to t ranslate the pr o filer Ed (0 ? ) to Ed (0 + ). The sub - surface values Lu (0 ? ) and Ed (0 ? ) were dete r mined from vertical profiles of radiometric casts by first...

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

    Science.gov (United States)

    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 (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 characterized by an increased contribution of aeolian dust probably from

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

    KAUST Repository

    Kalenderski, Stoitchko

    2016-05-23

    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 component (WRF-Chem), 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 are underestimated by a factor of two. 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

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

    Science.gov (United States)

    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

  9. Physical and underway data collected aboard the ROGER REVELLE during cruise KNOX10RR in the Arabian Sea and Indian Ocean from 2007-10-22 to 2007-11-04 (NCEI Accession 0155744)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0155744 includes physical and underway data collected aboard the ROGER REVELLE during cruise KNOX10RR in the Arabian Sea and Indian Ocean from...

  10. Cloud amount/frequency, NITRATE and other data from CHARLES DARWIN in the Arabian Sea and Indian Ocean from 1986-12-20 to 1987-08-14 (NCEI Accession 9000045)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) data with oxygen was collected off of Indian Ocean and Arabian Sea using Charles Darwin ship as part of Monsoon And...

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

    Indian Academy of Sciences (India)

    Madan M Mahanty; 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 ∼ 28°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.

  12. Spatial zonation of zooplankton in the northwestern Arabian Sea: A multivariate approach

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.

    of the world's oceans. High zooplankton production was reported by Panikkar and Rao (1973) and Smith (1982) in Somali upwelling regions, mostly during the period of the southwest monsoon. Several reports are available on the zooplankton of the eastern Arabian..., West Coast of India. Indian Journal of Marine Sciences 25(3): 26S- 273. Panikkar, N.K. and Rao, T.S.S. 1973. Zooplankton investigations in Indian waters and the role of the Indian Ocean Biological Centre. Handbook to the International zooplankton...

  13. Dissolved inorganic carbon, alkalinity, temperature, salinity and DISSOLVED OXYGEN collected from profile and discrete sample observations using Alkalinity titrator, CTD and other instruments from the Pacific Celebes in the Alboran Sea, Arabian Sea and others from 2007-06-11 to 2012-03-18 (NODC Accession 0081040)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0081040 includes chemical, discrete sample, physical and underway - surface data collected from Pacific Celebes in the Alboran Sea, Arabian Sea,...

  14. Chlorophyll modulation of mixed layer thermodynamics in a mixed-layer isopycnal General Circulation Model - An example from Arabian Sea and equatorial Pacific

    Indian Academy of Sciences (India)

    S Nakamoto; S Prasanna Kumar; J M Oberhuber; H Saito; K Muneyama; R Frouin

    2002-09-01

    Western tropical Indian Ocean, Arabian Sea, and the equatorial Pacific are known as regions of intense bio-chemical-physical interactions: the Arabian Sea has the largest phytoplankton bloom with seasonal signal, while the equatorial Pacific bloom is perennial with quasi-permanent upwelling. Here, we studied three dimensional ocean thermodynamics comparing recent ocean observation with ocean general circulation model (OPYC) experiment combined with remotely sensed chlorophyll pigment concentrations from the Coastal Zone Color Scanner (CZCS). Using solar radiation parameterization representing observations that a higher abundance of chlorophyll increases absorption of solar irradiance and heating rate in the upper ocean, we showed that the mixed layer thickness decreases more than they would be under clear water conditions. These changes in the model mixed layer were consistent with Joint Global Ocean Flux Study (JGOFS) observations during the 1994-1995 Arabian Sea experiment and epi-fluorescence microscopy (EFM) on samples collected during Equatorial Pacific Ocean Climate Study (EPOCS) in November, 1988. In the Arabian Sea, as the chlorophyll concentrations peak in October (3mg/m3) after the summer plankton bloom induced by coastal upwelling, the chlorophyll induced biological heating enhanced the sea surface temperature (SST) by as much as 0.6°C and sub-layer temperature decreases and sub-layer thickness increases. In the equatorial Pacific, modest concentrations of chlorophyll less than 0.3mg/m3 is enough to introduce a meridional differential heating, which results in reducing the equatorial mixed layer thickness to more than 20 m. The anomalous meridional tilting of the mixed layer bottom enhances off equatorial westward geostrophic currents. Consequently, the equatorial undercurrent transports more water from west to east. We proposed that these numerical model experiments with use of satellite and in situ ocean observations are consistent under three

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

    Directory of Open Access Journals (Sweden)

    C. Caulle

    2015-02-01

    Full Text Available 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Reconstruction of upwelling intensity and paleo-nutrient gradients in the northwest Arabian Sea derived from stable carbon and oxygen isotopes of planktic foraminifera.

    OpenAIRE

    C. Moos

    2000-01-01

    The Asian Monsoon system dominates the climate over large areas of the Asian and Indian continents and the rainfall prevailing during SW-monsoon is decisive for the agriculture of the entire region. The atmospheric monsoon system dominates the oceanographic surface circulation of the northern Indian Ocean and causes strong upwelling off Somalia and Arabia during SW-monsoon and makes the northwestern Arabian Sea to one of the most productive areas in the world oceans. Thus, productivity and nu...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Manohar, C.S.; Menezes, L.D.; Ramasamy, K.P.; Meena, R.M.

    reduction activity resulting in ammonia fermentation and nitrous oxide production by Aspergillus terreus, obtained by enrichment culture techniques from the seasonal OMZ of the Arabian Sea (Stief et al. 2014). These reports clearly point out the importance... that this isolate is highly divergent and could be a new species. YK-22, YK-35 and YK-29 clustered with strong bootstrap close to Aspergillus spp., Eupenicillium and Penicillium sp., and the environmental sequences identified as Pezizomycotina clone group...

  19. Enhanced chlorophyll a and primary production in the northern Arabian Sea during the spring intermonsoon due to green Noctiluca scintillans bloom

    Digital Repository Service at National Institute of Oceanography (India)

    Madhu, N.V.; Jyothibabu, R.; Maheswaran, P.A.; Jayaraj, K.A.; Achuthankutty, C.T.

    : Mar. Biol. Res., vol.8; 2012; 182-188 Enhanced chlorophyll a and primary production in the northern Arabian Sea during the spring intermonsoon due to green Noctiluca (N. scintillans) bloom N. V. Madhu a, *, R. Jyothibabu a , P. A. Maheswaran b... (Hansen et al., 2004). In the Indian waters, blooms of N. scintillans are very common following the enhanced phytoplankton production due to coastal upwelling (Naqvi et al., 1998; Satish et al., 2005., Padmakumar et al., 2010) and winter convective...

  20. Rock magnetic and geochemical record in a sediment core from the eastern Arabian Sea: Diagenetic and environmental implications during the late quaternary

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Kessarkar, P.M.; Patil, S.K.; Ahmad, S.M.

    ; Rey et al., 2005). These sediment features will ultimately determine whether or not sub-oxic/anoxic conditions become established in the sediment. Therefore, understanding the impact of early diagenesis on magnetic minerals has been important...: Clift, P.D., et al. (Ed.), The Tectonic and Climatic Evolution of the Arabian Sea Region. Special Publication, Geological Society of London, vol. 195, pp. 407–419. Rey, D., Mohamed, K.J., Bernabeu, A., Rubio, B., Vilas, F., 2005. Early diagenesis...

  1. Definite records of Sperm Whale Physeter catodon (Linnaeus, Spinner Dolphin Stenella longirostris (Gray and Bottlenose Dolphin Tursiops truncatus (Montagu (Mammalia: Cetartiodactyla in the Arabian Sea

    Directory of Open Access Journals (Sweden)

    S. Pande

    2009-03-01

    Full Text Available Definite records of five Sperm Whales Physeter catodon (Liinaeus, 58 Spinner Dolphins Stenella longirostris (Gray and 12 Bottlenose Dolphins Tursiops truncatus (Montagu in the Arabian Sea, encountered during Ela Foundation’s Pelagic Birds Survey and ornithological expedition to Lakshadweep Archipelago from 12 to 16 March 2006, are presented along with notes on behaviour, key identification features, four photographs and the conservation status of each species.

  2. Characterization of phosphorus species in sediments from the Arabian Sea oxygen minimum zone: Combining sequential extractions and X-ray spectroscopy

    OpenAIRE

    Kraal, Peter; Bostick, Benjamin C.; Behrends, Thilo; Reichart, Gert-Jan; Slomp, Caroline P.

    2015-01-01

    The bulk phosphorus (P) distribution in sediment samples from the oxygen minimum zone of the northern Arabian Sea was determined using two methods: sequential chemical extraction (the ‘SEDEX’ procedure) and X-ray absorption near-edge structure (XANES) spectroscopy of the phosphorus K-edge. Our results show good agreement between iron (Fe-)associated P and calcium phosphate minerals (Ca-P) determined by both methods. Furthermore, we find that SEDEX exchangeable P likely represents loosely Fe-b...

  3. 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

    OpenAIRE

    Wahl, Martin; Al-Sofyani, Abdelmohsin; 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 pattern...

  4. 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

    OpenAIRE

    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 pattern...

  5. Is delta sup(15)N of sedimentary organic matter a good proxy for paleodenitrification in coastal waters of the eastern Arabian Sea?

    Digital Repository Service at National Institute of Oceanography (India)

    Agnihotri, R.; Naqvi, S.W.A.; Kurian, S.; Altabet, M.A.; Bratton, J.F.

    in Coastal Waters of the Eastern Arabian Sea? Rajesh Agnihotri, S. Wajih A. Naqvi, and Siby Kurian National Institute of Oceanography, Council of Scientific and Industrial Research, Dona Paula, India Mark A. Altabet School for Marine Sciences and Technology... OMZ in the world. With its upper boundary occurring at 100–150 m, the OMZ lies mostly beyond the continental shelves [Naqvi, 1991]. However, because of the semi-enclosed nature of the northern Indian Ocean, this region still accounts for two...

  6. Oxygen minimum zone of the open Arabian Sea: variability of oxygen and nitrite from daily to decadal time scales

    Directory of Open Access Journals (Sweden)

    K. Banse

    2013-09-01

    Full Text Available The oxygen minimum zone (OMZ of the Arabian Sea is the thickest of the three oceanic OMZs, which is of global biogeochemical significance because of denitrification in the upper part leading to N2 and N2O production. The residence time of the OMZ water is believed to be less than a decade. The upper few hundred meters of this zone are nearly anoxic but non-sulfidic and still support animal (metazoan pelagic life, possibly as a result of episodic injections of O2 by physical processes. The very low O2 values obtained with the new STOX sensor in the eastern tropical South Pacific probably also characterize the Arabian Sea OMZ, but there is no apparent reason as to why the temporal trends of the historic data should not hold. We report on discrete measurements of dissolved O2 and NO2-, besides temperature and salinity, made between 1959 and 2004 well below the tops of the sharp pycno- and oxyclines near 150, 200, 300, 400, and 500 m depth. We assemble nearly all O2 determinations (originally, 849 values, 695 in the OMZ by the visual endpoint detection of the iodometric Winkler procedure, which in our data base yields about 0.04 mL L−1 (∼2 μM O2 above the endpoint from modern automated titration methods. We find 632 values acceptable (480 from 150 stations in the OMZ. The data are grouped in zonally-paired boxes of 1° lat. and 2° long. centered at 8°, 10°, 12°, 15°, 18°, 20°, and 21° N along 65° E and 67° E. The latitudes of 8–12° N, outside the OMZ, are only treated in passing. The principal results are as follows: (1 an O2 climatology for the upper OMZ reveals a marked seasonality at 200 to 500 m depth with O2 levels during the northeast monsoon and spring intermonsoon season elevated over those during the southwest monsoon season (median difference, 0.08 mL L−1 [3.5 μM]. The medians of the slopes of the seasonal regressions of O2 on year for the NE and SW monsoon seasons are −0.0043 and −0.0019 mL L−1 a−1

  7. Validation of MODIS derived aerosol optical depth and an investigation on aerosol transport over the South East Arabian Sea during ARMEX-II

    Directory of Open Access Journals (Sweden)

    M. Aloysius

    2009-06-01

    Full Text Available The influence of wind and humidity on aerosol optical depth (AOD over the Arabian sea is being investigated using MODIS (Moderate Resolution Imaging Spectroradiometer Level 3 (Collection-5 and NCEP (National Centres for Environmental Prediction reanalysis data for the second phase of the Arabian Sea Monsoon Experiment (ARMEX-II over the South East Arabian Sea (SEAS in the pre-monsoon period (14 March–10 April 2003. In order to qualify MODIS data for this study, MODIS aerosol parameters were first compared with ship borne Microtops measurements. This showed correlations 0.96–0.97 in the case of spectral AODs and a correlation 0.72 for the angstrom exponents. The daily AOD data from MODIS and winds from NCEP reveal that the ship observed episodic enhancement and decay of AOD at the TSL (Time Series Location during 23 March–6 April 2003 was caused by the southward drift of an aerosol pocket driven by an intensification and reduction of surface pressure in the North Western Arabian Sea with a low altitude convergence prevailing over SEAS. The AOD increase coincided with a decrease in the Angstrom exponent and the fine mode fraction suggesting the pocket being dominated by coarse mode particles. A partial correlation analysis reveals that the lower altitude wind convergence is the most influential atmospheric variable in modulating AOD over the ARMEX-II domain during the TSL period. However, surface winds at a distant zone in the north/north west upwind direction also had a moderate influence, though with a lag of two days. But this effect was minor since the winds were not strong enough to produce marine aerosols matching with the high AODs over the ARMEX-II domain. These findings and the similarity between MODIS column mass concentration and the ship borne QCM (Quartz Crystal Microbalance measured coarse mode mass concentration, suggest that the aerosol pocket was mostly composed of coarse mode mineral dust in the lower atmospheric altitudes

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  10. Performance of operational satellite bio-optical algorithms in different water types in the southeastern Arabian Sea

    Directory of Open Access Journals (Sweden)

    P. Minu

    2016-10-01

    Full Text Available The in situ remote sensing reflectance (Rrs and optically active substances (OAS measured using hyperspectral radiometer, were used for optical classification of coastal waters in the southeastern Arabian Sea. The spectral Rrs showed three distinct water types, that were associated with the variability in OAS such as chlorophyll-a (chl-a, chromophoric dissolved organic matter (CDOM and volume scattering function at 650 nm (β650. The water types were classified as Type-I, Type-II and Type-III respectively for the three Rrs spectra. The Type-I waters showed the peak Rrs in the blue band (470 nm, whereas in the case of Type-II and III waters the peak Rrs was at 560 and 570 nm respectively. The shifting of the peak Rrs at the longer wavelength was due to an increase in concentration of OAS. Further, we evaluated six bio-optical algorithms (OC3C, OC4O, OC4, OC4E, OC3M and OC4O2 used operationally to retrieve chl-a from Coastal Zone Colour Scanner (CZCS, Ocean Colour Temperature Scanner (OCTS, Sea-viewing Wide Field-of-view Sensor (SeaWiFS, MEdium Resolution Imaging Spectrometer (MERIS, Moderate Resolution Imaging Spectroradiometer (MODIS and Ocean Colour Monitor (OCM2. For chl-a concentration greater than 1.0 mg m−3, algorithms based on the reference band ratios 488/510/520 nm to 547/550/555/560/565 nm have to be considered. The assessment of algorithms showed better performance of OC3M and OC4. All the algorithms exhibited better performance in Type-I waters. However, the performance was poor in Type-II and Type-III waters which could be attributed to the significant co-variance of chl-a with CDOM.

  11. Seasonality and interannual variability of particle-fluxes to the deep Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Haake, B.; Ittekkot, V.; Rixen, T.; Ramaswamy, V.; Nair, R.R.; Curry, W.B.

    : The biology of the Indian Ocean, B ZErrZSCHEL, editor, Springer, Berhn, pp. 37-52. CURRY W. B (1991) Satelhte-derived sea surface temperatures and forammlferal production in the Arabmn Sea EOS, 72, No. 44, Supplement, 267 (Abstract). Curry W B , D. R...

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

    Science.gov (United States)

    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

  13. Seasonal and spatial variations in settling manganese fluxes in the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, T.M.B.; Ramaswamy, V.; Shankar, R.; Ittekkot, V.

    and its importance to the microbial food web of the North western Indian Ocean. Deep-Sea Research II 40, 773}782. Campbell, L., Landry, M.R., Constantinou, J., Nolla, H.A., Brown, S.L., Liu, H., Caron, D.A., 1998. Response of microbial community structure... stream_size 32329 stream_content_type text/plain stream_name Deep-Sea_Res_(I)_46_1827.pdf.txt stream_source_info Deep-Sea_Res_(I)_46_1827.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8...

  14. A taxonomic survey of Saudi Arabian Red Sea octocorals (Cnidaria: Alcyonacea)

    KAUST Repository

    Haverkort-Yeh, Roxanne D.

    2013-05-04

    A preliminary survey of Saudi Arabian Alcyonacea is presented, which combines classical taxonomy, multilocus molecular barcodes, and in situ photographs. We explored 14 locations along the west coast of the Kingdom of Saudi Arabia to assess the regional taxonomic diversity of non-gorgonian alcyonaceans. We collected samples from a total of 74 colonies, distributed among four families: 18 colonies of Alcyoniidae, 14 of Nephtheidae, 9 of Tubiporidae, and 33 of Xeniidae. We sequenced the octocorals using multiple nuclear [ribosomal Internal Transcribed Spacers (ITS) and ATP Synthetase Subunit α (ATPSα)] and mitochondrial [MutS homolog (mtMutS) and Cytochrome C Oxidase subunit one (COI)] loci, providing molecular barcodes which will: (1) allow direct comparison of biodiversity from this location to others for which molecular data are available, and (2) facilitate future identifications of these taxa. Finally, this preliminary phylogeny of sampled taxa provides insights on the resolution of mitochondrial versus nuclear loci, and highlights octocoral taxa that require further taxonomic attention. © 2013 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg.

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

    Science.gov (United States)

    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.

  16. Behaviour of Short-finned Pilot Whales Globicephala macrorhynchus (Gray, 1846 (Mammalia: Cetartiodactyla: Delphinidae in the southeastern Arabian Sea

    Directory of Open Access Journals (Sweden)

    Kurichithara K. Sajikumar

    2014-10-01

    Full Text Available We report the presence and behaviour of a pod of short-finned pilot whale Globicephala macrorhynchus in the southeastern Arabian Sea. The pod was observed in the southeastern side of Minicoy Island, in the Nine degree channel (09°219′23′′N;74°39′529′′E on 03.02.2013. Later, on 06.02.2013,the same pod of pilot whales were observed near Kalpeni Island (10°02′402′′N; 73°39′579′′E 130 km northwest of the previous location. The average length of the whales was estimated as 550 cm and weight as approximately 1200 kg. They were travelling in a northwesterly direction. The pod size of the whales sighted was twelve and several species specific behaviour such as side rolling, spyhopping, lobtailing, peduncle arching and movement patterns such as synchronous travelling and logging could be observed. The occurrence of scars and injuries on the body of four whales in the pod are also reported.

  17. Spatiotemporal Spectral Variations of AOT in India’s EEZ over Arabian Sea: Validation of OCM-II

    Directory of Open Access Journals (Sweden)

    C. P. Simha

    2012-01-01

    Full Text Available We report the results of sun-photometric measurements of Aerosol Optical Thickness (AOT in India’s Exclusive Economic Zone (EEZ over the Arabian Sea along with synchronous Ocean Color Monitor (OCM-II derived AOT estimates during December 12, 2009–January 10, 2010. Relatively higher values of Angstrom exponent (α around 1.2 near coast and 0.2–0.8 in the India’s EEZ, observed during the cruise period, indicate the presence of smaller particles near the coast due to anthropogenic activities; and larger particles in the India’s EEZ due to advection of pollutants from Indian subcontinent via long-range transport. Results related to α and its derivative reveal four different aerosol types (urban-industrial, desert-dust, clean-marine, and mixed-type with varying fraction during the study period. Surface radiative forcing due to aerosols is found to be 20 W/m2 over India’s EEZ. OCM-derived AOTs showed good corroboration with in situ measurements with a correlation coefficient of about 0.95. A reasonably good correlation was also observed between AOT and wind speed (R = 0.6; AOT and relative humidity (R = 0.58. The concurrent MODIS AOT data also agree well with those observed by the OCEANSAT (OCM-II satellite during the campaign period.

  18. SEASONAL ASSESSMENT OF HYDROGRAPHIC VARIABLES AND PHYTOPLANKTON COMMUNITY IN THE ARABIAN SEA WATERS OF KERALA, SOUTHWEST COAST OF INDIA

    Directory of Open Access Journals (Sweden)

    Sushanth Vishwanath Rai

    2014-12-01

    Full Text Available The seasonal variation of the hydrographic variables and phytoplankton species in the Arabian Sea waters of the Kerala coast, Southern India was investigated during different seasons. The variables such as pH, temperature, salinity, turbidity and chlorophyll-a contents of water were found to be high during pre-monsoon season and the dissolved oxygen content was minimal. The concentration of nutrients viz., nitrate, phosphate, silicate varied independently. In the study a total of 53 species of phytoplankton were recorded. Their density was higher during the post-monsoon season than during other seasons and the diatoms were found to be the dominant species. The major phytoplankton in terms of frequency and abundance were the species namely, Biddulphia mobiliensis, Chaetoceros curvisetus, Licmophora abbreviata, Skeletonema costatum, Prorocentrum micans and Oscillatoria sp. They showed significant positive correlation with pH, temperature, salinity, nitrate, phosphate and chlorophyll-a contents, whereas turbidity, dissolved oxygen and silicate exhibited significant negative correlation. The Principal Component Analysis (PCA developed two principal components with 84.74% of total variability in the water quality which separated pre- and post-monsoon periods from the monsoon season on axis I, and pre-monsoon and monsoon periods from post-monsoon on axis II.

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

    Science.gov (United States)

    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.

  20. Marine sediments and palaeoclimatic variations since the Late Pleistocene: An overview for the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Hashimi, N.H.

    . These studies dealing mostly with sea level changes and the palaeomonsoon are classified in Stream 1 and Stream 2 according to the objectives of Past Global Changes (PAGES) studies under the International Geosphere Biosphere Program (IGBP)...

  1. Physical forcing of biological productivity in the northern Arabian Sea during the northeast monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Ramaiah, N.; Gauns, M.; Sarma, V.V.S.S.; Muraleedharan, P.M.; Raghukumar, S.; DileepKumar, M.; Madhupratap, M.

    to the inference that even a 1 degree C decrease in SST could lead to significantly higher primary productivity. Satellite data on sea surface temperature (advanced very high-resolution radiometer, AVHRR) and TOPEX/POSEIDON altimeter data suggest...

  2. Foraminifera [Marine Microfossil] as an additional tool for archaeologists - Examples from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    -chemical parameters and during their life time incorporate effect of prevailing parameters in their hard covering (test), which is made- up of calcium carbonate and has excellent fossilization potential. Because of these two properties, i.e. sensitivity... (1995) will serve a long standing need of a standard sea level curve for the future workers. The understanding developed for sea level fluctuations helped to explain two important archaeological findings i.e. Lothal dockyard and discovery of a...

  3. Why is mean sea level along the Indian coast higher in the Bay of Bengal than in the Arabian Sea?

    Digital Repository Service at National Institute of Oceanography (India)

    Shankar, D.; Shetye, S.R.

    in the strength of the winds increases the sea level di erence between Vishakhapatnam and Mumbai (Chennai and Manga- lore) by 13% (11%). Sea level see-saws along the coast of the subcontinent, with the southern tip of Sri Lanka 10 20 30 40 0 10 20 30 40...

  4. A Rapid Assessment of Scleractinian and Non-Scleractinian Coral Growth Forms Along the Saudi Arabian Coast, Red Sea

    Institute of Scientific and Technical Information of China (English)

    Abdulmohsin A. Al-Sofyani; N. Marimuthu; J. Jerald Wilson

    2014-01-01

    In this study we assessed the current status of coral reefs along the Saudi Arabian coast of the Red Sea. Among the three growth forms of Acroporid corals, the branching forms were found to dominate in the Farassan Islands (44.55%±11.10%cover) fol-lowed by tabular forms in the Doga Islands (ranging between 18%±6.47% and 18.30%±9.47% cover). Digitate forms were rarely found along the coast except at Maqna. Among the five growth forms of non-Acroporid corals, we observed maximum cover of branching forms in the Yanbu offshore area (58.89%±15.11% cover) followed by the Jeddah coast (24.76%±14.04% cover). The Millepora spp., a non-Scleractinian coral, was abundant at all the near-shore sites, such as Jeddah (10.70%±8.21%) and Al-Wajh (9.81%±6.69%). The live coral cover (including both Scleractinian and non-Scleractinian corals) of Saudi Red Sea coast was seen to be higher in the north and gradually decrease towards the south. Principal Component analysis showed that the contribution of Acro-porid corals was greater in the southern region than in the northern and middle regions, but vice-versa in the case of non-Acroporid corals. Bray-Curtis cluster analysis categorized all the study sites into two major clusters with 60% similarity. Among them, one cluster-forming sites from Maqna to Masturah (Northern region) and the second one comprised the middle and southern regions (Jeddah to Farassan Islands), and one outlier Rabigh.

  5. Fish market surveys indicate unsustainable elasmobranch fisheries in the Saudi Arabian Red Sea

    KAUST Repository

    Spaet, Julia L.

    2015-01-01

    Elasmobranch populations worldwide are severely threatened due to overexploited and unregulated fisheries. Despite the fact that sharks and rays are captured in fisheries operating along the Red Sea coast of the Kingdom of Saudi Arabia (KSA), information on any aspects of these fisheries are very limited. Here we document the structure, composition and biological characteristics of eastern Red Sea elasmobranch fisheries based on genetic identification and market survey data over an intensive two-year sampling period at the biggest Red Sea fish market in the KSA (Jeddah). Market surveys conducted two times per month between 2011 and 2013 revealed that 24 previously confirmed elasmobranch species for the Red Sea were landed by fishers and offered for sale. Genetic identification revealed two potentially undescribed guitarfish species as well as four batoid species not formerly reported from the Red Sea. Five coastal carcharhinid species dominated the landings-. Carcharhinus sorrah, C. amblyrhynchos, C. falciformis, C. limbatus, Rhizoprionodon acutus, together comprising 73% numerically of the total catch. Targeted shark fisheries reportedly exist in shark nursery areas. Most elasmobranchs outside of these areas were reportedly landed as bycatch. Most strikingly, the large majority of landed elasmobranchs were immature males or females below their reported size of sexual maturity, which suggests potential for both growth and recruitment overfishing and emphasizes the urgent need to implement region-specific management and conservation strategies to avoid the loss of these critical predators.

  6. Characteristic Study of the Boundary Layer Parameters over the Arabian Sea and the Bay of Bengal Using the QuikSCAT Dataset

    Institute of Scientific and Technical Information of China (English)

    V. HAMZA; C. A. BABU; T. P. SABIN

    2007-01-01

    The marine atmospheric boundary layer (MABL) plays a vital role in the transport of momentum and heat from the surface of the ocean into the atmosphere. A detailed study on the MABL characteristics was carried out using high-resolution surface-wind data as measured by the QuikSCAT (Quick scatterometer)satellite. Spatial variations in the surface wind, frictional velocity, roughness parameter and drag coefficient for the different seasons were studied. The surface wind was strong during the southwest monsoon season due to the modulation induced by the Low Level Jetstream. The drag coefficient was larger during this season, due to the strong winds and was lower during the winter months. The spatial variations in the frictional velocity over the seas was small during the post-monsoon season (~0.2 m s-1). The maximum spatial variation in the frictional velocity was found over the south Arabian Sea (0.3 to 0.5 m s-1) during the southwest monsoon period, followed by the pre-monsoon over the Bay of Bengal (0.1 to 0.25 m s-1).The mean wind-stress curl during the winter was positive over the equatorial region, with a maximum value of 1.5×10-7 N m-3, but on either side of the equatorial belt, a negative wind-stress curl dominated. The area average of the frictional velocity and drag coefficient over the Arabian Sea and Bay of Bengal were also studied. The values of frictional velocity shows a variability that is similar to the intraseasonal oscillation(ISO) and this was confirmed via wavelet analysis. In the case of the drag coefficient, the prominent oscillations were ISO and quasi-biweekly mode (QBM). The interrelationship between the drag coefficient and the frictional velocity with wind speed in both the Arabian Sea and the Bay of Bengal was also studied.

  7. A critical evaluation of depositional parameters controlling the variability of organic carbon in Arabian Sea sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L.; PrakashBabu, C.; Mascarenhas, A.

    Petroleum Source Rocks. Blackwell, London, pp. 137-151. Calvert, S.E., KaUin, R.E, Toolin, L.J., Donahue, D.J., Sou- thon, J.R. and Vogel, J.S., 1991. Low organic carbon accl:- mulation rates in Black Sea sediments. Nature, 6230: 692-695. Caratini, C...

  8. Seasonal variability in oxygen and nutrients in the central and eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    DeSousa, S.N.; DileepKumar, M.; Sardessai, S.; Sarma, V.V.S.S.; Shirodkar, P.V.

    hyphenminus411. 1. Swallow, J. C., Deep Sea Res., 1984, 31, 639hyphenminus650. 2. Smith, R. L. and Bottero, J. S., in A Voyage of Discovery, George Deacon 70th Anniversary Volume (ed Angel, M.), Pergamon Press, New York, 1977, pp. 291hyphenminus304. 3. Banse...

  9. Denitrification rates and excess nitrogen gas concentrations in the Arabian Sea oxygen deficient zone

    Digital Repository Service at National Institute of Oceanography (India)

    Devol, A.H.; Uhlenhopp, A.G.; Naqvi, S.W.A.; Brandes, J.A.; Jayakumar, D.A.; Naik, H.; Gaurin, S.; Codispoti, L.A.; Yoshinari, T.

    Sea. In contrast, N 2 :Ar profiles inside the denitrifying zone were strikingly different. Although the surface values were once again near 1.00, there was a distinct peak in the heart of the ODZ at about 200–300m where values reached 1.030–1.035 (Fig...

  10. The role of salinity on the dynamics of the Arabian Sea mini warm pool

    Digital Repository Service at National Institute of Oceanography (India)

    Nyadjro, E.S.; Subrahmanyam, B.; Murty, V.S.N.; Shriver, J.F.

    address the role of salinity and the upper layer heat and salt budgets in the formation and collapse of this ASMWP. An assessment of Level 3 sea surface salinity (SSS) data from the Soil Moisture and Ocean Salinity (SMOS) satellite mission for the year...

  11. Contamination of organochlorine pesticides in sediments from the Arabian Sea along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sarkar, A.; Nagarajan, R.; Chaphadkar, S.; Pal, S.; Singbal, S.Y.S.

    control programme. On with larger surface area and those with organic average the annual consumption of various pesti- content show the highest adsorption capacity (Elder cides in India is about 75,000 metric tons of which and Weber, 1980). 48... influence the variation in concentration of various PCB components. Neth. J. Sea Res. 17, 19-38. organochlorine pesticides in sediment of different Elder G. and Weber K. (1980) Chlorinated phenols in characteristics (Sarkar, 1994; Fisher et al., 1983...

  12. Environmental studies of the Arabian Sea using remote sensing, GIS and GPS techniques

    Digital Repository Service at National Institute of Oceanography (India)

    Saxena, A.

    (SST) Sea surface temperature is the water temperature at the surface. In practical terms, the exact meaning of "surface" will vary according to the measurement method used. A satellite radiometer "sees" a skin temperature representing the top... measured SST provides both a synoptic view of the ocean and a high frequency of repeat views, allowing the examination of basinwide upper ocean dynamics not possible with ships or buoys. In SST measurements, the radiation emanates from the top "skin...

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  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.

    Directory of Open Access Journals (Sweden)

    Martin Wahl

    Full Text Available 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.

  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.

    Science.gov (United States)

    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. Pre-monsoon living planktonic foraminifera from the Southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Naidu, P.D.; Muralinath, A.S.

    of June (SW monsoon period), highest ever reported. This may be due to the fact that Rao et af. (1988) have counted only the foraminifera less than )50 microns in size. For the convenience of interpretation, the present area has been divided into two..., where the sea surface 6$'· 658 M.V.S. GOPTHA AND OTHERS temperatures are between 10° and 18°C and salinities less than 35.5%. One of the three morphotypes of G. bulloides has been reported in upwelling regions off Somalia, off Gulf of Aden and southern...

  19. In situ profiling of eastern Arabian Sea coastal waters using a new autonomous vertical profiler

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.S.; Madhan, R.; Dabholkar, N.A.; Prabhudesai, S.P.; Navelkar, G.S.; Mascarenhas, A.A.M.Q.; Afzulpurkar, S.; Phaldesai, M.; Maurya, P.

    in the open ocean [3]–[5]. Each cycle of the float takes between 6 and 10 h to execute with the float descending at very low speeds of the order centimeters per second.t Therefore, open-ocean floats are unsuitable for shallow coastal waters where rapid... and execute dives at programmed intervals as before, but now as a fully autonomous platform. The inherent buoyancy is of prac- tical use during deployment at sea, as it enables the user to see the AVP float away from the proximity of the ship. In contrast...

  20. Bathymetric preference of four major genera of rectilinear benthic foraminifera within oxygen minimum zone in Arabian Sea off central west coast of India.

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumder, A.; Nigam, R.

    parts of world (Turner and Rabalais 1994; Sen Gupta et al. 1996; Malakoff 1998; Rabalais 2000; Osterman 2003), including eastern Arabian Sea (Naqvi et al. 2000). The level of oxygen concen- tration of this shallow water OMZ is much less than (<5 μmol.... Discussion Regions of less oxygen concentration in different parts of world oceans have been reported and stud- ied in different aspects (Wyrtki 1962; Sen Gupta et al. 1980; Turner and Rabalais 1994; Osterman 2003). Low oxygenated water with the concentra...

  1. Nitrogen transformations in the Arabian Sea Oxygen Minimum Zone as revealed by combined 15N-incubation experiments and functional gene expression analyses

    Science.gov (United States)

    Lam, P.; Jensen, M. M.; Lavik, G.; Kuypers, M. M. M.

    2009-04-01

    The Arabian Sea Oxygen Minimum Zone (OMZ) is considered to be one of the three major regions in the world's Ocean where nitrogen loss occurs in the water column. However, the exact pathway and the microbial players involved in the dinitrogen gas production, as well as the cycling of other inorganic nitrogen species, are not entirely clear. We performed incubation experiments with 15N-labeled substrates to investigate the vertical distribution of nitrogen-loss (denitrification and anammox) and other nitrogen transformations through the OMZ from the Omani shelf offshore towards the Indian coast. Intriguingly, there was no evidence of either anammox or denitrification in the northeastern Arabian Sea, which has generally been considered the main region of N-loss in the Arabian Sea. Instead, our results pointed to a substantial N-loss due to anammox from the Omani upwelling area. Moreover, a close coupling was demonstrated in the Omani shelf waters between anammox and DNRA (dissimilatory nitrate reduction to ammonium), with the latter process providing a substantial proportion of ammonium for the former. The co-occurrence of these processes was further confirmed by independent expression analyses of the functional gene biomarkers (anammox-type nirS, denitrifier-nirS and nrfA) for all these processes. Nitrification occurred particularly in the upper part of the OMZ and on the Omani shelf, predominantly mediated by crenarchaea over bacteria as shown by the expression of their respective ammonia monooxygenase genes (amoA). When detected, nitrification could supply at least 12% of the nitrite required by anammox. Meanwhile, nitrate reduction, traditionally regarded as the first step in denitrification, could be detected at higher rates than anammox and even at regions where dinitrogen gas production was not detected. This is consistent with the expression analyses of its biomarker gene (narG). In the northeastern Arabian Sea, our combined results suggested that there was

  2. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the MELVILLE in the Arabian Sea, Bay of Bengal and others from 1972-07-18 to 1978-04-28 (NODC Accession 0117677)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117677 includes chemical, discrete sample, physical and profile data collected from MELVILLE in the Arabian Sea, Bay of Bengal, Bering Sea, Gulf of...

  3. Merging Approaches to Explore Connectivity in the Anemonefish, Amphiprion bicinctus, along the Saudi Arabian Coast of the Red Sea

    KAUST Repository

    Nanninga, Gerrit B.

    2013-09-01

    The field of marine population connectivity is receiving growing attention from ecologists worldwide. The degree to which metapopulations are connected via larval dispersal has vital ramifications for demographic and evolutionary dynamics and largely determines the way we manage threatened coastal ecosystems. Here we addressed different questions relating to connectivity by integrating direct and indirect genetic approaches over different spatial and ecological scales in a coral reef fish in the Red Sea. We developed 35 novel microsatellite loci for our study organism the two-band anemonefish Amphiprion bicinctus (Rüppel 1830), which served as the basis of the following approaches. First, we collected nearly one thousand samples of A. bicinctus from 19 locations across 1500 km along the Saudi Arabian coast to infer population genetic structure. Genetic variability along the northern and central coast was weak, but showed a significant break at approximately 20°N. Implementing a model of isolation by environment with chlorophyll-a concentrations and geographic distance as predictors we were able to explain over 90% of the genetic variability in the data (R2 = 0.92). For the second approach we sampled 311 (c. 99%) putative parents and 172 juveniles at an isolated reef, Quita al Girsh (QG), to estimate self-recruitment using genetic parentage analysis. Additionally we collected 176 juveniles at surrounding locations to estimate larval dispersal from QG and ran a biophysical dispersal model of the system with real5 time climatological forcing. In concordance with model predictions, we found a complete lack (c. 0.5%) of self-recruitment over two sampling periods within our study system, thus presenting the first empirical evidence for a largely open reef fish population. Lastly, to conceptualize different hypotheses regarding the underlying processes and mechanisms of self-recruitment versus long-distance dispersal in marine organisms with pelagic larval stages, I

  4. Late Quaternary changes in surface productivity and oxygen minimum zone (OMZ) in the northwestern Arabian Sea: Micropaleontologic and sedimentary record at ODP site 728A

    Indian Academy of Sciences (India)

    Ajai K Rai; S S Das

    2011-02-01

    Changes in the abundance of selected planktic foraminiferal species and some sedimentological parameters at ODP site 728A were examined to understand the fluctuations in the surface productivity and deep sea oxygenation in the NW Arabian Sea during last ∼540 kyr. The increased relative abundances of high fertility taxa, i.e., Globigerinita glutinata and Globigerina bulloides mainly during interglacial intervals indicate intense upwelling. Strong SW summer monsoon probably increased the upwelling in the western Arabian Sea during interglacial intervals and caused high surface productivities due to the lateral transport of eutrophic waters. Most of the glacial periods (i.e., MIS 2, 4, 6, 8 and 12) are characterized by higher relative abundances of Neogloboquadrina pachyderma and Neogloboquadrina dutertrei associated with Globigerinoides ruber. The more stratified condition and deep mixed layer due to increased NE winter monsoon are mainly responsible for the higher relative abundances of N. pachyderma during glacial periods. Some of the glacial intervals (i.e., MIS 6 and 8) are also characterized by pteropod spikes reflecting deepening of aragonite compensation depth (ACD) and relatively less intense oxygen minimum zone (OMZ) in this region due to deep sea mixing and thermocline ventilation, and relatively less intense surface productivity during winter monsoon. The interglacial periods are largely devoid of pteropod shells indicating more aragonite dissolution due to increased intensity of OMZ in the northwestern Arabian Sea. In general, the interglacial periods are characterized by low sediment accumulation rates than the glacial intervals. On an average, the total biogenic carbonate percentages were higher during interglacial and during periods of higher surface productivity. Most terrigenous material was trapped on shelf during intervals of high sea level stands of interglacial, whereas more erosion of shelf increased the sedimentation rates during glacial

  5. Spatial distribution of atmospheric carbon monoxide over Bay of Bengal and Arabian Sea: Measurements during pre-monsoon period of 2006

    Indian Academy of Sciences (India)

    V R Aneesh; G Mohankumar; S Sampath

    2008-08-01

    Indian Space Research Organization (ISRO)conducted the ‘Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB)’for a two-month pre-monsoon period in 2006 with the ocean segment covering Bay of Bengal and Arabian Sea.During this campaign,carbon monoxide (CO) was continuously monitored using a non-dispersive IR analyser. Quantifying CO in ambient air is vital in determining the air quality of a region.Being toxic,CO is a criteria pollutant,but it is a weak green house gas.Globally,very few measurements exist over marine atmospheres to study its temporal pattern;particularly in situ CO measurements are few over the Bay of Bengal and Arabian Sea for comparison.Present measurements indicate:(i)predominant single peak in the diurnal pattern of CO over the marine atmosphere in contrast to the double peak over the continent, (ii)the mean diurnal CO over the marine atmosphere showing an increasing trend towards evening hours,(iii)the amplitude of the AN peaks over the marine atmosphere was ∼100 ppbv,while at a remote island site in the Indian Ocean it was ∼5 ppbv and (iv)high CO values were observed close to continent and the long range transport by wind also caused CO highs.

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

    Science.gov (United States)

    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. Heterogeneity in pre-monsoon aerosol types over the Arabian Sea deduced from ship-borne measurements of spectral AODs

    Directory of Open Access Journals (Sweden)

    D. G. Kaskaoutis

    2010-05-01

    Full Text Available Ship-borne sunphotometer measurements obtained in the Arabian Sea (AS in the pre-monsoon season (18 April–10 May 2006 during a cruise campaign (ICARB have been used to retrieve the Aerosol Optical Depth (AOD; τ and the Ångström wavelength exponent (α. The continents surrounding the AS produce natural and anthropogenic aerosols that have distinctive influences on α and its spectral distribution. The α values were estimated by means of the least-squares method over the spectral bands 340–1020 nm and 340–870 nm. The spectral distribution of AOD in logarithmic co-ordinates could be fit using a 2nd order polynomial with higher accuracy in the wavelength band 340–1020 nm than in the 340–870 nm band. A polynomial fit analytically parameterizes the observed wavelength dependencies of AOD with least errors in spectral variation of α and yields accurate estimates of the coefficients (a1 and a2. The coarse-mode (positive curvature in the lnτλ vs. lnλ aerosols are mainly depicted in the Northern part of the AS closely associated with the nearby arid areas while fine-mode aerosols are mainly observed over the far and coastal AS regions. In the study period the mean AOD at 500 nm is 0.25±0.11 and the α340-1020 is 0.90±0.19. The α340-870 exhibits similar values (0.92±0.18, while significant differences revealed for the constant terms of the polynomial fit (a1 and a2 proportionally to the wavelength band used for their determination. Observed day-to-day variability in the aerosol load and optical properties are direct consequence of the local winds and air-mass trajectories along with the position of the ship.

  8. Turbidity, SOLAR RADIATION - ATMOSPHERIC and other data from DARSHAK and DEEPAK in the Bay of Bengal and Arabian Sea from 1979-05-02 to 1979-08-01 (NCEI Accession 8700352)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data comprise XBT and MBT log sheets collected in the Arabian sea and the Bay of Bengal from May 16, 1979 to August 1, 1979. These data were collected by the...

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

    Science.gov (United States)

    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. The Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Naik, H.; Narvekar, P.V.

    the southwest monsoon current (SMC), a feature unique to the North Indian Ocean (it replaces the westward tlowing north equatorial current found in the other oceans). Coastal upwelling associated with this tlow regime is manifested by wedge-shaped features [dis... into the euphotic zone. The unique monsoon forcing provides the energy needed for this purpose. For example, summer upwelling raises surface NO,- concentrations up to 16-20~Moff Somalia (Smith & Codispoti, 1980), India (Naqvi etal., 1998) and Oman (Fig. 6...

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

    Science.gov (United States)

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

    Directory of Open Access Journals (Sweden)

    laura eVillanueva

    2014-02-01

    Full Text Available 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. Here, we sequenced genomic DNA from suspended particulate matter recovered at the upper (170 m deep and center (600 m area of the oxygen minimum zone 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.

  13. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the METEOR in the Arabian Sea, Arctic Ocean and others from 1997-06-11 to 1997-07-03 (NODC Accession 0115159)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115159 includes chemical, discrete sample, physical and profile data collected from METEOR in the Arabian Sea, Arctic Ocean, Gulf of Aden, Gulf of...

  14. Biological, physical, nutrients, sediment, and other data from sediment sampler-grab, bottle, and CTD casts in the Arabian Sea, Equatorial Pacific Ocean, Northeast Atlantic Ocean, and Southern Oceans as part of the Long Term Monitoring East-West Flower Garden Banks project from 08 January 1995 to 08 April 1998 (NODC Accession 0001155)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Biological, physical, nutrients, sediment, and other data were collected using sediment sampler-grab, bottle and CTD casts in the Arabian Sea, North/South Pacific...

  15. Influence of winds on temporally varying short and long period gravity waves in the near shore regions of Eastern Arabian Sea

    Directory of Open Access Journals (Sweden)

    J. Glejin

    2012-09-01

    Full Text Available Wave data collected off Ratnagiri, west coast of India during 1 May 2010 to 30 April 2012 is used in the study. Seasonal and annual variation in wave data controlled by the local wind system such as sea breeze and land breeze, and remote wind generated long period waves observed along the west coast of India, is studied. Sea breeze plays an important role in determining the sea state during pre and post monsoon seasons and the maximum wave height is observed during peak hours of sea breeze at 15:00 UTC. Long period waves (peak period over 13 s are observed mainly during the pre and the post monsoon season. Maximum peak period observed during the study is 22 s and is in the month of October. Long period waves observed during the south west monsoon period of 2011 are identified as swell propagated from the Southern Ocean with an estimated travelling time of 5–6 days. The swells reaching the Arabian Sea from the South Indian Ocean and Southern Ocean, due to storms during the pre and post monsoon periods will modify the near surface winds, due to the dominant wave induced wind regime. Energy spectrum of observed waves indicates onset and decline of strong south west monsoon winds. Convergence of energy-containing frequency bands corresponding to short period waves (Tp < 8 s and long period waves (Tp > 13 s to intermediate period waves (8 < Tp < 13 s are observed at the end of the pre monsoon season; divergence is observed during the start of the post monsoon period from intermediate period waves to short period waves and long period waves. South west monsoon period is characterized by the energy corresponding to the frequency band of intermediate period waves along the west coast of India.

  16. Chemical characteristics of aerosols in MABL of Bay of Bengal and Arabian Sea during spring inter-monsoon: A comparative study

    Indian Academy of Sciences (India)

    Ashwini Kumar; A K Sudheer; M M Sarin

    2008-07-01

    The chemical composition of aerosols in the Marine Atmospheric Boundary Layer (MABL) of Bay of Bengal (BoB) and Arabian Sea (AS) has been studied during the spring and inter-monsoon (March–May 2006) based on the analysis of water soluble constituents (Na+, NH$^{+}_{4}$, K+, Mg2+, Ca2+, Cl−, NO$^{−}_{3}$ and SO$^{2−}_{4}$), crustal elements (Al, Fe, and Ca) and carbonaceous species (EC, OC). The total suspended particulates (TSP) ranged from 5.2 to 46.6 g m−3 and 8.2 to 46.9 g m−3 during the sampling transects in the BoB and AS respectively. The water-soluble species, on average, accounted for 44% and 33% of TSP over BoB and AS respectively, with dominant contribution of SO$^{2−}_{4}$ over both the oceanic regions. However, distinct differences with respect to elevated abundances of NH$^{+}_{4}$ in the MABL of BoB and that of Na+ and Ca2+ in AS are clearly evident. The non-sea-salt component of SO$^{2−}_{4}$ ranging from 82 to 98% over BoB and 35 to 98% over AS; together with nss-Ca2+/nss-$SO^{2−}_{4}$ equivalent ratios 0.12 to 0.5 and 0.2 to 1.16, respectively, provide evidence for the predominance of anthropogenic constituents and chemical transformation processes occurring within MABL. The concentrations of OC and EC average around 1.9 and 0.4 g m−3 in BoB and exhibit a decreasing trend from north to south; however, abundance of these carbonaceous species are not significantly pronounced over AS. The abundance of Al, used as a proxy for mineral aerosols, varied from 0.2 to 1.9 g m−3 over BoB and AS, with a distinctly different spatial pattern – decreasing north to south in BoB in contrast to an increasing pattern in the Arabian Sea.

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

    Science.gov (United States)

    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

  18. 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

    OpenAIRE

    Schouten, S.; Pitcher, A.; Hopmans, E.C.; van Bleijswijk, J.; Sinninghe Damsté, J.S.

    2012-01-01

    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 upp...

  19. 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.

    Science.gov (United States)

    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

  20. THE POTENTIAL OF TSUNAMI GENERATION ALONG THE MAKRAN SUBDUCTION ZONE IN THE NORTHERN ARABIAN SEA. CASE STUDY: THE EARTHQUAKE AND TSUNAMI OF NOVEMBER 28, 1945

    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis

    2006-01-01

    Full Text Available Although large earthquakes along the Makran Subduction Zone are infrequent, the potential for the generation of destructive tsunamis in the Northern Arabian Sea cannot be overlooked. It is quite possible that historical tsunamis in this region have not been properly reported or documented. Such past tsunamis must have affected Southern Pakistan, India, Iran, Oman, the Maldives and other countries bordering the Indian Ocean.The best known of the historical tsunamis in the region is the one generated by the great earthquake of November 28, 1945 off Pakistan's Makran Coast (Balochistan in the Northern Arabian Sea. The destructive tsunami killed more than 4,000 people in Southern Pakistan but also caused great loss of life and devastation along the coasts of Western India, Iran, Oman and possibly elsewhere.The seismotectonics of the Makran subduction zone, historical earthquakes in the region, the recent earthquake of October 8, 2005 in Northern Pakistan, and the great tsunamigenic earthquakes of December 26, 2004 and March 28, 2005, are indicative of the active tectonic collision process that is taking place along the entire southern and southeastern boundary of the Eurasian plate as it collides with the Indian plate and adjacent microplates. Tectonic stress transference to other, stress loaded tectonic regions could trigger tsunamigenic earthquakes in the Northern Arabian Sea in the future.The northward movement and subduction of the Oman oceanic lithosphere beneath the Iranian micro-plate at a very shallow angle and at the high rate is responsible for active orogenesis and uplift that has created a belt of highly folded and densely faulted coastal mountain ridges along the coastal region of Makran, in both the Balochistan and Sindh provinces. The same tectonic collision process has created offshore thrust faults. As in the past, large destructive tsunamigenic earthquakes can occur along major faults in the east Makran region, near Karachi, as

  1. Absence of genetic differentiation in the coral Pocillopora verrucosa along environmental gradients of the Saudi Arabian Red Sea

    OpenAIRE

    Robitzch, Vanessa; Banguera-Hinestroza, Eulalia; Sawall, Yvonne; Al-Sofyani, Abdulmohsin; Voolstra, Christian R.

    2015-01-01

    The Red Sea is the world's northernmost tropical sea. The 2000 km long, but narrow basin creates distinct environmental conditions along its latitudinal spread. The Red Sea displays a pronounced salinity gradient from 41 to 37 PSU (north to south) with an opposing temperature gradient from 21 to 27°C in the north to 27–33.8°C in the south. The Red Sea further displays a decreasing nutrient gradient from south to north that can also influence underwater light fields due to higher phytoplankton...

  2. Absence of genetic differentiation in the coral Pocillopora verrucosa along environmental gradients of the Saudi Arabian Red Sea

    OpenAIRE

    Vanessa eRobitzch; Eulalia eBanguera-Hinestroza; Yvonne eSawall; Abdulmohsin eAl-Sofyani; Christian Robert Voolstra

    2015-01-01

    The Red Sea is the world’s northernmost tropical sea. The 2,000 km long, but narrow basin creates distinct environmental conditions along its latitudinal spread. The Red Sea displays a pronounced salinity gradient from 41 to 37 PSU (north to south) with an opposing temperature gradient from 21-27°C in the north to 27-33.8°C in the south. The Red Sea further displays a decreasing nutrient gradient from south to north that can also influence underwater light fields due to higher phytoplankton c...

  3. 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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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/TNcontamination from a potential fishery zone of Indian exclusive economic zone.

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

    Science.gov (United States)

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

    Science.gov (United States)

    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.

  7. Spatio-temporal variation of microphytoplankton in the upwelling system of the south-eastern Arabian Sea during the summer monsoon of 2009

    Directory of Open Access Journals (Sweden)

    Lathika Cicily Thomas

    2013-02-01

    Full Text Available The phytoplankton standing crop was assessed in detail along the South Eastern Arabian Sea (SEAS during the different phases of coastal upwelling in 2009. During phase 1 intense upwelling was observed along the southern transects(8°N and 8.5°N. The maximum chlorophyll a concentration (22.7 mg m-3 was observedin the coastal waters off Thiruvananthapuram (8.5°N. Further north there was no signature of upwelling, with extensive Trichodesmium erythraeum blooms. Diatoms dominated in these upwelling regions with thecentric diatom Chaetoceros curvisetus being the dominant species along the 8°N transect. Along the 8.5°N transect pennate diatoms like Nitzschia seriata and Pseudo-nitzschia sp. dominated. Duringphase 2, upwelling of varying intensity was observed throughout the study area with maximum chlorophyll a concentrations along the 9°N transect (25 mg m-3 with Chaetoceros curvisetus as the dominantphytoplankton. Along the 8.5°N transect pennate diatoms during phase 1 were replaced by centric diatoms like Chaetoceros sp. The presence of solitary pennate diatoms Amphora sp. and Navicula sp.were significant in the waters off Kochi. Upwelling was waning during phase 3 and was confined to the coastal waters of the southern transects with the highest chlorophyll a concentration of 11.2 mg m-3. Along withdiatoms, dinoflagellate cell densities increased in phases 2 and 3. In the northern transects (9°N and 10°N the proportion of dinoflagellates was comparatively higher and was represented mainly by Protoperidinium spp.

  8. A comparison of Globigerinoides ruber calcification between upwelling and non-upwelling regions in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.S.; Godad, S.P.; Naidu, P.D.; Ramaswamy, V.

    distinct difference in pCO2 and sea surface temperature (SST), the shell weights of G. ruber are similar in these two regions which suggest that surface water pCO2 and SST do not show dominant influence on shell calcification on a...

  9. Differences in heat budgets of the near-surface Arabian Sea and Bay of Bengal: Implications for the summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C; Shankar, D.; Shetye, S.R.

    that is stable and responds quickly to changes in the atmosphere. An implication is that sea surface temperature (SST) in the bay remains higher than 28 degrees C, thereby supporting large-scale deep convection in the atmosphere during the summer monsoon...

  10. Comparative accounts of biological productivity characteristics and estimates of carbon fluxes in the Arabian Sea and the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Gauns, M.; Madhupratap, M.; Ramaiah, N.; Jyothibabu, R.; Fernandes, V.; Paul, J.T.; PrasannaKumar, S.

    the sinking fluxes of the region. An attempt is made here to focus on factors responsible for fluxes of carbon from the upper layers to the deep sea. Higher fluxes are observed during southwest and northeast monsoon season in both the regions. In contrast...

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

    Science.gov (United States)

    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

  12. The relationship between volatile halocarbons and phytoplankton pigments during a Trichodesmium bloom in the coastal eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Roy, R.; Pratihary, A.; Narvenkar, G.; Mochemadkar, S.; Gauns, M.; Naqvi, S.W.A.

    chamber and examining through an Olympus inverted microscope (magnification 100-200X). Generic and species identifications were done according to various taxonomic keys following Subrahmanyam (1959), Lebour (1978) and Tomas (1996). 3. Result 3... hydrocarbons in the ocean, Journal of Geophysical Research 97, 12683-12687. Kononen, K., Leppänen, J-M., 1997. Patchiness, scales and controlling mechanisms of cyanobacterial blooms in the Baltic Sea: Application of a multiscale research strategy. In...

  13. Archaeal tetraether membrane lipid fluxes in the northeastern Pacific and the Arabian Sea: implications for TEX86 paleothermometry

    OpenAIRE

    Wuchter, C.; Schouten, S.; Wakeham, S.G.; Sinninghe Damsté, J.S.

    2006-01-01

    The newly introduced temperature proxy, the tetraether index of archaeal lipids with 86 carbon atoms (TEX86), is based on the number of cyclopentane moieties in the glycerol dialkyl glycerol tetraether (GDGT) lipids of marine Crenarchaeota. The composition of sedimentary GDGTs used for TEX86 paleothermometry is thought to reflect sea surface temperature (SST). However, marine Crenarchaeota occur ubiquitously in the world oceans over the entire depth range and not just in surface waters. We an...

  14. Carbon and nitrogen uptake of calcareous benthic foraminifera along a depth-related oxygen gradient in the OMZ of the Arabian Sea

    Directory of Open Access Journals (Sweden)

    Annekatrin Julie Enge

    2016-02-01

    Full Text Available 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 cal-careous 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 phy-todetrital carbon within 4 days by all investigated species shows that phytodetritus is a rele-vant 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 spe-cies. 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 condi-tions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availabil-ity and in the presence of other benthic organisms account for observed changes in the pro-cessing 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 bounda-ry region of the Indian margin as biological interactions and species distribution of foraminif-era change with depth and oxygen levels.

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

    Directory of Open Access Journals (Sweden)

    T. Caley

    2013-06-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. Thermodynamic structure of the Atmospheric Boundary Layer over the Arabian Sea and the Indian Ocean during pre-INDOEX and INDOEX-FFP campaigns

    Directory of Open Access Journals (Sweden)

    M. V. Ramana

    2004-09-01

    Full Text Available Spatial and temporal variability of the Marine Atmospheric Boundary Layer (MABL height for the Indian Ocean Experiment (INDOEX study period are examined using the data collected through Cross-chained LORAN (Long-Range Aid to Navigation Atmospheric Sounding System (CLASS launchings during the Northern Hemispheric winter monsoon period. This paper reports the results of the analyses of the data collected during the pre-INDOEX (1997 and the INDOEX-First Field Phase (FFP; 1998 in the latitude range 14°N to 20°S over the Arabian Sea and the Indian Ocean. Mixed layer heights are derived from thermodynamic profiles and they indicated the variability of heights ranging from 400m to 1100m during daytime depending upon the location. Mixed layer heights over the Indian Ocean are slightly higher during the INDOEX-FFP than the pre-INDOEX due to anomalous conditions prevailing during the INDOEX-FFP. The trade wind inversion height varied from 2.3km to 4.5km during the pre-INDOEX and from 0.4km to 2.5km during the INDOEX-FFP. Elevated plumes of polluted air (lofted aerosol plumes above the marine boundary layer are observed from thermodynamic profiles of the lower troposphere during the INDOEX-FFP. These elevated plumes are examined using 5-day back trajectory analysis and show that one group of air mass travelled a long way from Saudi Arabia and Iran/Iraq through India before reaching the location of measurement, while the other air mass originates from India and the Bay of Bengal.

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

    Science.gov (United States)

    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

  20. 16SrRNA and enzymatic diversity of culturable bacteria from the sediments of oxygen minimum zone in the Arabian Sea.

    Science.gov (United States)

    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

  1. Hydrographic features of the gas hydrate studies survey area of cruise AASGH2 in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Charyulu, R.J.K.; Fernandes, W.A.; Gawde, S.; Almeida, A.M.

    in the underwater unit. The CTD system used is SBE911plus, manufactured by M/S Seabird electronics Ltd , USA, which consists of an underwater unit and a deck unit and a single conductor wire rope connecting them. The winch used for lowering and hauling up... altimeter is attached to the CTD frame looking downwards which helps in knowing the height of CTD underwater unit from seabed by using acoustic pulses reflected from sea bottom. 6 All the sensors were factory-calibrated by manufacturers and only...

  2. Dispersal and sink pathways of suspended particulate matter from the orographically enhanced SWM regime of the SE Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Kader, U.S.A.; Vaidya, P.; Rajawat, A.S.; Ajai; Ramakrishnan, R.

    persisted during June through September. An evaluation of rain gauge data between 2001 and 2005 from two meteorological stations (Karwar, 14º N 74º E; Mangalore 12º N: 74º E; Chauhan OS and KV Singh 2010, unpublished data) reveals the occurrence of ~ 20... during NE monsoon. Deep-Sea Research part II, 52(14-15), pp. 2018-2030. doi:10.1016/j.dsr2.2005.05.012 CHAUHAN, O. S., VOGELSANG, E., BASAVAIAH, N. and KADER, U. S. A., 2010, Reconstruction of the variability of the southwest monsoon during the past...

  3. Diagnostic model of 3-D circulation in the Arabian Sea and western equatorial Indian Ocean: Results of monthly mean sea surface topography

    Digital Repository Service at National Institute of Oceanography (India)

    Bahulayan, N.; Shaji, C.

    A three-dimensional diagnostic model has been developed to compute the monthly mean circulation and sea surface topography in the Western Tropical Indian Ocean north of 20 degrees S and west of 80 degrees E. The diagnostic model equations...

  4. 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

    Directory of Open Access Journals (Sweden)

    H. Schulz

    2013-07-01

    Full Text Available 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

  5. A Study of the Pelagic Larval Duration of Acropora humilis, Coral Recruitment and Connectivity in the Saudi Arabian Red Sea

    KAUST Repository

    Khalil, Maha

    2011-12-12

    Combined knowledge of the pelagic larval duration of coral species and coral recruitment patterns can provide evidence of inter-reef connectivity and indicate a reef’s ability to recover. We attempted to determine the maximum pelagic larval duration of Acropora humilis. Larvae were reared in a controlled environment unfavorable for settlement. The larvae lived in a pelagic state for a maximum of 29 days, although this is probably an underestimate of actual longevity for this species. Given the information available from the literature with respect to larval dispersal rates, it is not expected that larvae with this longevity will disperse further than 10-20 km from their natal reef, if at all. A long-term recruitment monitoring project was also set up on Abu Shosha Reef, which suffered nearly complete coral loss due to a bleaching event in summer of 2010. In April 2011, 60 settlement plates were placed on the reef. In July, a total of 102 living scleractinian recruits were counted on the plates. While pocilloporids were the most dominant recruits on the reef (57.8%), about 20.6% of living recruits belonged to Acroporidae, a family whose live cover on the reef is extremely low (0.67%). However, the overall mean density of recruits was very low (1.7 living recruits/100cm2) compared to similar studies around the world despite the spawning season having just ended. Fish surveys showed herbivore biomass to be very low compared to other reef systems in the world, but densities were significantly higher than another reef in the Red Sea with about 10 times more live coral cover. Recovery from bleaching for Abu Shosha and similar reefs in the region may be very slow relative to rates observed in other parts of the world if recruitment rates and herbivore communities remain low.

  6. Glacial-interglacial productivity contrasts along the eastern Arabian Sea:Dominance of convective mixing over upwelling

    Institute of Scientific and Technical Information of China (English)

    Kumar Avinash; Busnur R.Manjunath; P.John Kurian

    2015-01-01

    The western continental margin of India is one of the highly productive regions in the global ocean. Primary productivity is induced by upwelling and convective mixing during the southwest and northeast monsoons respectively. Realizing the importance of high primary productivity, a sediment core was collected below the current oxygen minimum zone (OMZ) from the southwestern continental margin of India. This was dated by AMS radiocarbon and as many as 60 paleoclimate/paceoceanographic proxies, such as particle size, biogenic components, major, trace and rare earth elements (REEs) which were measured for the first time to determine sources of sediment, biogeochemical processes operating in the water column and their variations since the last glacial cycle. R-mode factor analysis of comprehensive data indicates that the dominant regulator of paleoproductivity is the southwest monsoon wind induced upwelling. Other paleoproductivity related factors identified are the marine biogenic component and biogenic detritus (as an exported component from the water column added to the bottom sediment). All paleoproductivity components increased significantly during the marine isotope stage-1 (MIS-1) compared to those accumulated from MIS-4 to MIS-2. The second group of factors identified are the terrigenous sediments with heavy minerals like zircon and ilmenite. The terrigenous sediment, in particular, increased during MIS-2 when the sea-level was lower; however, the heavy mineral compo-nent fluctuated over time implying pulsed inputs of sediment. The diagenetic fraction and reducing component are the third group of factors identified which varied with time with increased accumulation during the MIS transitions. The primary productivity along the southwestern continental margin of India seems to have been controlled principally by the upwelling during the southwest monsoon season that was weaker from MIS-4 to MIS-2, as relative to that during the MIS-1. In contrast, increased

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

    Science.gov (United States)

    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

  8. On the spatial structure and time evolution of shamal winds over the Arabian Sea – a case study through numerical modelling.

    Digital Repository Service at National Institute of Oceanography (India)

    VinodKumar, K.; Seemanth, M.; Vethamony, P.; Aboobacker, V.M.

    . Along the Arabian coast a temperature drop of 12°C is observed and along west coast of India a drop of 5°C. It gets dissipated when northeast monsoon winds dominate. Its speed reduces from 15ms-1 (Oman coast) to 9ms-1 (central AS...

  9. Biodiversity of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    stream_size 2 stream_content_type text/plain stream_name Biodiversity_Western_Ghats_Inf_Kit_1994_3.1_1.pdf.txt stream_source_info Biodiversity_Western_Ghats_Inf_Kit_1994_3.1_1.pdf.txt Content-Encoding ISO-8859-1 Content-Type text.../plain; charset=ISO-8859-1 ...

  10. Examination of aerosol distributions and radiative effects over the Bay of Bengal and the Arabian Sea region during ICARB using satellite data and a general circulation model

    Directory of Open Access Journals (Sweden)

    R. Cherian

    2012-02-01

    Full Text Available In this paper we analyse aerosol loading and its direct radiative effects over the Bay of Bengal (BoB and Arabian Sea (AS regions for the Integrated Campaign on Aerosols, gases and Radiation Budget (ICARB undertaken during 2006, using satellite data from the MODerate Resolution Imaging Spectroradiometer (MODIS on board the Terra and Aqua satellites, the Aerosol Index from the Ozone Monitoring Instrument (OMI on board the Aura satellite, and the European-Community Hamburg (ECHAM5.5 general circulation model extended by Hamburg Aerosol Module (HAM. By statistically comparing with large-scale satellite data sets, we firstly show that the aerosol properties measured during the ship-based ICARB campaign and simulated by the model are representative for the BoB and AS regions and the pre-monsoon season. In a second step, the modelled aerosol distributions were evaluated by a comparison with the measurements from the ship-based sunphotometer, and the satellite retrievals during ICARB. It is found that the model broadly reproduces the observed spatial and temporal variability in aerosol optical depth (AOD over BoB and AS regions. However, AOD was systematically underestimated during high-pollution episodes, especially in the BoB leg. We show that this underprediction of AOD is mostly because of the deficiencies in the coarse mode, where the model shows that dust is the dominant component. The analysis of dust AOD along with the OMI Aerosol Index indicate that missing dust transport that results from too low dust emission fluxes over the Thar Desert region in the model caused this deficiency. Thirdly, we analysed the spatio-temporal variability of AOD comparing the ship-based observations to the large-scale satellite observations and simulations. It was found that most of the variability along the track was from geographical patterns, with a minor influence by single events. Aerosol fields were homogeneous enough to yield a good statistical agreement

  11. Planktonic percentage of foraminiferal fauna in surface sediments of the Arabian sea (Indian Ocean) and a regional model for paleodepth determination

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Henriques, P.J.

    with previous studies in other areas that planktonic percentage increased with depth. The resultant pattern is compared with results from the Atlantic margin of the northeastern United States, Gulf of Mexico, Timor Sea and Red Sea. Comparisons reveal...

  12. 16S rRNA-based bacterial diversity in the organic-rich sediments underlying oxygen-deficient waters of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Divya, B.; Parvathi, A.; LokaBharathi, P.A.; Nair, S.

    ). Bootstrap analysis was carried out using 1000 iterations. Diversity analysis The clone library of AS-OMZ was compared with those of other anoxic sediments from Gulf of Mexico, North Sea and South China Sea (28, 60 and 87 sequences, respectively.... Figure 2d Bacterial diversity and richness To understand the bacterial diversity and richness of the AS-OMZ sediment clone library, comparisons were made with suboxic sediment clone libraries from South China Sea, North Sea and Gulf of Mexico...

  13. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Wind resource characterization in the Arabian Peninsula

    KAUST Repository

    Yip, Chak Man Andrew

    2015-12-28

    Wind energy is expected to contribute to alleviating the rise in energy demand in the Middle East that is driven by population growth and industrial development. However, variability and intermittency in the wind resource present significant challenges to grid integration of wind energy systems. These issues are rarely addressed in the literature of wind resource assessment in the Middle East due to sparse meteorological observations with varying record lengths. In this study, the wind field with consistent space–time resolution for over three decades at three hub heights (50m, 80m, 140m) over the whole Arabian Peninsula is constructed using the Modern Era Retrospective-Analysis for Research and Applications (MERRA) dataset. The wind resource is assessed at a higher spatial resolution with metrics of temporal variations in the wind than in prior studies. Previously unrecognized locations of interest with high wind abundance and low variability and intermittency have been identified in this study and confirmed by recent on-site observations. In particular, the western mountains of Saudi Arabia experience more abundant wind resource than most Red Sea coastal areas. The wind resource is more variable in coastal areas along the Arabian Gulf than their Red Sea counterparts at a similar latitude. Persistent wind is found along the coast of the Arabian Gulf.

  15. 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

    Science.gov (United States)

    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.

  16. Impact of temperature inversions on SST evolution in the South-Eastern Arabian Sea during the pre-summer monsoon season

    Digital Repository Service at National Institute of Oceanography (India)

    Durand, F.; Shetye, S.R.; Vialard, J.; Shankar, D.; Shenoi, S.S.C.; Ethe, C.; Madec, G.

    , an inversion in the upper layer can only be sustained by a sharp haline stratification, the so-called ‘‘barrier layer’’ [e.g., Lukas and Lindstrom, 1991]. In this paper, we analyze new observed datasets as well as state-of- the-art numerical model outputs... to address the following questions: [4] 1) Do the data show a marked inversion and a barrier layer in the SEAS in winter? Is our model consistent with the observed features? [5] 2) Is the peculiar thermal structure of the SEAS linked with the formation...

  17. Sediment sound velocities from sonobuoys: Arabian fan

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. New stable isotope records of sediment cores from the SE Arabian Sea - Inferences on the variations in monsoon regime during the late Quaternery

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.

    conditions. This includes a moderate sea surface cooling (~ 2°C) and an enhanced evaporation (increasing salinity by ~ 2.5 p.s.u.) during the LGM and/or increased precipitation during the early Holocene. The diminished Dd18O value of benthic records (~ 1...

  19. 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

    Science.gov (United States)

    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.

  20. Impact of sedimentary degradation and deep water column production on GDGT abundance and distribution in surface sediments in the Arabian Sea: Implications for the TEX86 paleothermometer

    Science.gov (United States)

    Lengger, Sabine K.; Hopmans, Ellen C.; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2014-10-01

    The TEX86 is a widely used paleotemperature proxy based on isoprenoid glycerol dibiphytanyl glycerol tetraethers (GDGTs) produced by Thaumarchaeota. Archaeal membranes are composed of GDGTs with polar head groups (IPL-GDGTs), most of which are expected to be degraded completely or transformed into more recalcitrant core lipid (CL)-GDGTs upon cell lysis. Here, we examined the differences in concentration and distribution of core lipid (CL)- and intact polar lipid (IPL)-GDGTs in surface sediments at different deposition depths, and different oxygen bottom water concentrations (TEX86 values of both IPL-derived GDGTs and CL-GDGTs decreased by ∼0.08 units with increasing water depth, in spite of the sea surface temperatures being identical for the restricted area studied. In situ production in sediments could be excluded as the main cause, due to the slow production rates of GDGTs in sediments, and previous observations of the same trends in TEX86 in sediment trap material. Instead, the incorporation of GDGTs produced in the oxygen minimum zone (with high TEX86 values) and their preferential degradation during the sinking through the water column, or differential degradation of IPL-GDGTs per head group could be the causes for the observed change in TEX86 values. The effect of differential degradation might cause differences between oxic and anoxically deposited sediments, and, together with a potential deep water contribution on TEX86 values, could translate into changes in reconstructed temperature of TEX86 calibration and paleotemperature studies of deep water sedimentary records.

  1. The Neolithic origins of seafaring in the Arabian Gulf

    Directory of Open Access Journals (Sweden)

    Robert Carter

    2002-10-01

    Full Text Available The inhabitants of the Arabian Gulf were among the world’s earliest maritime traders. Their ships sailed regularly between the Bronze Age civilizations of Mesopotamia, Bahrain and the Indus Valley, and they reached China by sea in the eighth century AD, thus bypassing the long and perilous overland Silk Road route across Central Asia. Now excavations at a coastal site in Kuwait by a team from the Institute have revealed even earlier evidence of maritime activity in the Gulf.

  2. GROWTH RATE OF ARABIAN FOALS

    Directory of Open Access Journals (Sweden)

    M. PIESZKA

    2013-12-01

    Full Text Available Arabian horses are treated as one of the most noble horse breed in the world. It isalso one of the oldest breed known as a root of many other breeds. Opposite toThoroughbred horses Arabian ones are very healthy, easy to keep with low fodderdemand. They are still incredibly resistant to environmental conditions. Growth anddevelopment of foals is also very interesting because it is more similar to growth ofprimitive than to noble foals. The object of this study was to analyse the growth rateof Arabian foals bred in Poland. 382 foals born in Bialka Stud in 1983-2003 weretaken under consideration. The height at withers, girth and cannon circumferencemeasured at 1 day and 6 and 18 months of life were analysed. On this base thegrowth rate was calculated. Horses were divided into different groups accordingtheir year of birth, sex, coat colour and sire and dam lines. The statistical differencesbetween particular groups were evaluated. It was stated that year of birth affectedsignificantly the growth rate of Arabian foals. Colts were characterized bysignificantly higher growth rate of cannon circumference. Horses of different coatcolour did not differ in growth rate of any parameter. Affiliation to particular sireand dam lines had some effects on growth rate of Arabian foals.

  3. Active NE-SW Compressional Strain Within the Arabian Plate

    Science.gov (United States)

    Floyd, M. A.; ArRajehi, A.; King, R. W.; McClusky, S.; Reilinger, R. E.; Douad, M.; Sholan, J.; Bou-Rabee, F.

    2012-12-01

    Motion of the Arabian plate with respect to Eurasia has been remarkably steady over more than 25 Myr as revealed by comparison of geodetic and plate tectonic reconstructions (e.g., McQuarrie et al., 2003, GRL; ArRajehi et al., 2010, Tectonics). While internal plate deformation is small in comparison to the rate of Arabia-Eurasia convergence, the improved resolution of GPS observations indicate ~ NE-SW compressional strain that appears to affect much of the plate south of latitude ~ 30°N. Seven ~ NE-SW oriented inter-station baselines all indicated shortening at rates in the range of 0.5-2 mm/yr, for the most part with 1-sigma velocity uncertainties < 0.4 mm/yr. Plate-scale strain rates exceed 2×10-9/yr. The spatial distribution of strain can not be resolved from the sparse available data, but strain appears to extend at least to Riyadh, KSA, ~ 600 km west of the Zagros Fold and Thrust Belt that forms the eastern, collisional boundary of the Arabian plate with Eurasia (Iran). Geodetic velocities in the plate tectonic reference frame for Arabia, derived from magnetic anomalies in the Red Sea (Chu and Gordon, 1998, GJI), show no significant E-W motion for GPS stations located along the Red Sea coast (i.e., geodetic and plate tectonic spreading rates across the Red Sea agree within their resolution), in contrast to sites in the plate interior and along the east side of the plate that indicate east-directed motions. In addition, NE-SW contraction is roughly normal to ~ N-S striking major structural folds in the sedimentary rocks within the Arabian Platform. These relationships suggest that geodetically observed contraction has characterized the plate for at least the past ~ 3 Myr. Broad-scale contraction of the Arabian plate seems intuitively reasonable given that the east and north sides of the plate are dominated by active continental collision (Zagros, E Turkey/Caucasus) while the west and south sides are bordered by mid-ocean ridge spreading (Red Sea and Gulf of

  4. Living coccolithophorids from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Mohan, R.; Muralinath, A.S.

    irregularis, Umbilicosphaera sibogae var. foliosa and Gephyrocapsa oceanica. Low fertility of water during September-October is believed to have caused tha abundance of E. buxleyi and U. irregularis. It has also been observed that malformation of E. buxleyi...

  5. Diseases of chaetognaths from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Santhakumari, V.

    Three different diseases, provisionally assigned as spot disease, swell disease and tail rot disease, were observed in chaetognaths Sagitta enflata Grassi and S. bedoti Bernaneck. The first two diseases showed high percentage of occurrence. The spot...

  6. Composition of heteropods in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Aravindakshan, P.N.; Stephen, R.

    stream_size 4 stream_content_type text/plain stream_name 2_Workshop_Scient_Result_FORV_Sagar_Sampada_Proc_1996_193.pdf.txt stream_source_info 2_Workshop_Scient_Result_FORV_Sagar_Sampada_Proc_1996_193.pdf.txt Content-Encoding ISO-8859...

  7. Nitrous oxide in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Noronha, R.J.

    HIDA et al., 1984), it was proposed that denitrification could be primarily responsible for the oceanic NzO production. The isotope data presented by YOSHtDA et al. (1989) appear to be in conflict with their main conclusion. The observed enrichment of t... and K. O. MUNNXCH (1986) ISOtopic and micrometeorologic COx fluxes: a serious conflict. Journal of Geophysical Research. 91,10517-10527. BtrrLEa J. H., .I.W. ELKtNS and T. M. THOMPSON (1989) Tropospheric and dissolved Nz O of the West Pacific and East...

  8. Organic carbon removal in the sea: the continental connection

    Digital Repository Service at National Institute of Oceanography (India)

    Ittekkot, V.; Haake, B.; Bartsch, M.; Nair, R.R.; Ramaswamy, V.

    Time series sediment traps have been deployed since May 1986 in the Arabian Sea and since October 1987 in the Bay of Bengal. The results of one and a half years from the western, central, and eastern Arabian Sea and of one year from the northern Bay...

  9. Potentiality of foraminifera in deciphering paleo-sea levels

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    the application of the foraminiferal distributional pattern in marine sediments (with special reference to the Arabian Sea), to decipher information about the paleo-sea level. Different strategies are being followed for different conditions. For example, (1) when...

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

    Science.gov (United States)

    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.

  11. A bridge too far: dispersal barriers and cryptic speciation in an Arabian Peninsula grouper (Cephalopholis hemistiktos)

    KAUST Repository

    Priest, Mark

    2015-12-12

    Aim: We use genetic and age-based analyses to assess the evidence for a biogeographical barrier to larval dispersal in the yellowfin hind, Cephalopholis hemistiktos, a commercially important species found across the Arabian Peninsula. Location: Red Sea, Gulf of Aden, Gulf of Oman and Arabian Gulf. Methods: Mitochondrial DNA cytochrome-c oxidase subunit-I and nuclear DNA (S7) sequences were obtained for C. hemistiktos sampled throughout its distributional range. Phylogeographical and population-level analyses were used to assess patterns of genetic structure and to identify barriers to dispersal. Concurrently, age-based demographic analyses using otoliths determined differences in growth and longevity between regions. Results: Our analyses revealed significant genetic structure congruent with growth parameter differences observed across sampling sites, suggesting cryptic speciation between populations in the Red Sea and Gulf of Aden versus the Gulf of Oman and Arabian Gulf. Coalescence analyses indicated these two regions have been isolated for > 800,000 years. Main conclusions: Our results indicate historical disruption to gene flow and a contemporary dispersal barrier in the Arabian Sea, which C. hemistiktos larvae are unable to effectively traverse. This provides yet another example of a (cryptic) species with high dispersive potential whose range is delimited by a lack of suitable habitat between locations or an inability to successfully recruit at the range edge. © 2015 John Wiley & Sons Ltd.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. Travelers' Health: MERS in the Arabian Peninsula

    Science.gov (United States)

    ... Travelers’ Health website for more information on healthy travel. Health care workers People who are traveling to provide health care services in the Arabian Peninsula should review CDC’s recommendations for infection control of confirmed or ...

  15. 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

    OpenAIRE

    Lengger, S. K.; Hopmans, E.C.; G. J. Reichart; Nierop, K. G. J.; Sinninghe Damsté, J.S.; Schouten, S.

    2012-01-01

    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 ...

  16. 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

    OpenAIRE

    Lengger, S. K.; Hopmans, E.C.; Reichart, G.-J.; Nierop, K. G. J.; Sinninghe Damsté, J.S.; Schouten, S.

    2012-01-01

    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 ...

  17. The influence of extreme winds on coastal oceanography and its implications for coral population connectivity in the southern Arabian Gulf.

    Science.gov (United States)

    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

  18. Mitochondrial DNA structure in the Arabian Peninsula

    Directory of Open Access Journals (Sweden)

    Cabrera Vicente M

    2008-02-01

    Full Text Available Abstract 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 (preHV1 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

  19. Potential uranium provinces in some arabian countries

    International Nuclear Information System (INIS)

    This work represents an attempt to delineate potential uranium provinces in some Arabian countries using various related recognition criteria. Definition of these provinces is based on the available geologic and tectonic setting beside geochronological sequence and some geochemical characteristics. This trial would be of a great help for interchanging the ideas and necessary data for the development in the fields of uranium exploration and production. As a result of this study, a number of promising potential uranium provinces are recommended in some arabian countries. 5 figs

  20. Thraustochytrid fungoid protists in faecal pellets of the tunicate Pegea confoederata, their tolerance to deep-sea conditions and implication in degradation processes

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, S.; Raghukumar, C.

    During a swarm of the tunicate Pegea confoederata (salp) in the northern Arabian Sea, we examined their faecal pellets for thraustochytrid protists and bacteria to understand the role of the former in decomposition processes in the sea. Fresh faecal...

  1. Saudi Arabian seismic-refraction profile: A traveltime interpretation of crustal and upper mantle structure

    Science.gov (United States)

    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

  2. Supersequence and composite sequence carbonate platform growth: Permian and Triassic outcrop data of the Arabian platform and Neo-Tethys

    Science.gov (United States)

    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

  3. Barotolerance of fungi isolated from deep-sea sediments of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C.; Raghukumar, S.

    Two species of filamentous fungi, Aspergillus ustus (Bain.) Thoms and Church and Graphium sp., were isolated from calcareous animal shells at depths of 860 m in the Arabian Sea and 965 m in the Bay of Bengal. Laboratory experiments showed...

  4. Population genetics of four heavily exploited shark species around the Arabian Peninsula

    KAUST Repository

    Spaet, Julia L. Y.

    2015-05-01

    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.

  5. Population genetics of four heavily exploited shark species around the Arabian Peninsula.

    Science.gov (United States)

    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

  6. Molecular biodiversity of Red Sea demosponges.

    Science.gov (United States)

    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. Molecular biodiversity of Red Sea demosponges

    KAUST Repository

    Erpenbeck, Dirk

    2016-01-07

    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.

  8. Wave energy resource assessment for the Indian shelf seas

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Anoop, T.R.

    power at 19 locations covering the Indian shelf seas using the ERA-Interim dataset produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim data is compared with the measured wave parameters in the Arabian Sea...

  9. Neoproterozoic tectonics of the Arabian-Nubian Shield

    NARCIS (Netherlands)

    Blasband, B.

    2006-01-01

    The Neoproterozoic tectonic development of the Arabian-Nubian Shield (ANS) can be divided in three parts: 1) the oceanic stage; 2) the arc-accretion stage; 3) the extensional stage. Three key-areas in the Arabian-Nubian Shield, namely the Bi'r Umq Complex, The Tabalah and Tarj Complex and the Wadi K

  10. Energy content of suspended detritus from Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumari, L.; Sumitra-Vijayaraghavan; Royan, J.P.

    Energy components of suspended matter included phytoplankton, zooplankton and detritus inclusive of microorganisms adsorbed to detritus. Of these, detritus contributed most of the energy (98%). The average caloric content of suspended detritus...

  11. Arabian Sea mini warm pool and the monsoon onset vortex

    Digital Repository Service at National Institute of Oceanography (India)

    Vinayachandran, P.N.; Shankar, D.; Kurian, J.; Durand, F.; Shenoi, S.S.C.

    consolidated account of what has been known and what should be the future direction. This need is the motivation for this review. Recent reviews have synthesized our current knowl- edge of the basin-scale monsoon circulation of the Indian Ocean12...

  12. Interannual variability of chlrophyll concentration in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Karanje, S.

    guidance, inspiration, support and encouragement during the course of this dissertation work. I am also grateful to him for motivating me towards new ideas and I take this opportunity to express my indebtedness and respect to him. Above all, I owe...

  13. Isotopic evidences of past upwelling intensity in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.

    in the higher d 18 O values, while the concurrent increase in nutrient content of upper water column increases the productivity, which results in higher d 13 C val- ues in planktic foraminifera. Very often, the d 13 C values of planktic foraminifera...

  14. Coastal versus open-ocean denitrification in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Naik, H.; Pratihary, A.K.; DeSouza, W.; Narvekar, P.V.; Jayakumar, D.A.; Devol, A.H.; Yoshinari, T.; Saino, T.

    is distin- guished by much higher concentrations of N2O (reaching up to similar0.8 ?M) as compared to the open ocean. The highest val- ues are unexpectedly associated with very high NO-2 (reach- ing up to 16 ?M) and low (near exhaustion) NO-3 levels of- ten... then account for the low delta15N-NO-3 val- ues. The few data on sedimentary denitrification, measured mostly during the upwelling period following the acetylene block technique, have yielded values ranging from 0.23 to 1.25 mmol NO-3 m-2 d-1, which...

  15. Methane in coastal and offshore waters of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Naqvi, S.W.A.; Narvekar, P.V.; George, M.D.

    capped Ž. by a thin 5–10 m lens of fresher water which originates in part from local precipitation and in part from runoff from the narrow coastal plain that re- ceives heavy SWM rainfall. The combination of upwelling and precipitation plus land runoff... to the develop- ment of suboxic conditions at shallow depths off the central and southwest coasts of India. Maximal CH 4 concentrations are frequently seen either at the sur- face, associated with the low salinity water mass which caps the upwelled water...

  16. Nitrogen uptake in the northeastern Arabian Sea during winter cooling

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, S.; Ramesh, R.; Dwivedi, R.M.; Raman, M.; Sheshshayee, M.S.; DeSouza, W.

    (-2) d sup(-1)). The f-ratio during January appeared to be affected by the winter cooling effect and increased by more than 50% from the southernmost station to the northern open ocean stations, indicating hydrographic and meteorological control...

  17. Carbon dioxide and nitrous oxide in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Sengupta, R.; DileepKumar, M.

    stream_size 8 stream_content_type text/plain stream_name Interaction_Between_Global_Clim_Subsyst_1993_85.pdf.txt stream_source_info Interaction_Between_Global_Clim_Subsyst_1993_85.pdf.txt Content-Encoding ISO-8859-1 Content...

  18. Coccolithophores from the central Arabian Sea: Sediment trap results

    Digital Repository Service at National Institute of Oceanography (India)

    Mergulhao, L.P.; Mohan, R.; Murty, V.S.N.; Guptha, M.V.S.; Sinha, D.K.

    of the twenty species of coccolithophores encountered, Gephyrocapsa oceanica, Emiliania huxleyi, Umbilicosphaera sibogae and Umbellosphaera irregularis were the most abundant. The total coccolithophore fluxes ranged from 28.5 × 10 sup(6) m sup(-2) d sup(-1...

  19. Miocene phosphorites from the Murray Ridge, northwestern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Hegner, E.; Naqvi, S.W.A.; Kessarkar, P.M.; Ahmad, S.M.; Raju, D.S.

    . In thin- section, the large nodules exhibit homogeneous light-colored The Murray Ridge and sample locality are indicated. micritic phosphate, surrounded by a thin dark-grey phosphate matrix (Fig. 2B). The small nodules reveal phosphate pellets surrounded... in the center of the pellets (Fig. 2C). The dark-grey portions of the phosphate matrix show a spongy texture with hollow sub-spherical components (Fig. 2D). Elsewhere rounded to ovoid aggregates with obscured internal structure are aligned parallel. SEM images...

  20. Seasonality and composition of phytoplankton in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Madhupratap, M.

    during the inter-monsoon. Integrated cell numbers in the upper 120 m was from 0.4 to 1.2, 1.7 to 170 and 0.3 to 10 (X 10 sup(8)) cells m sup(-2) during inter-monsoon, winter and summer monsoon periods, respectively. Diatoms comprised 86% of the total...

  1. Insect drift over the northern Arabian Sea in early summer

    Digital Repository Service at National Institute of Oceanography (India)

    Pathak, S.C.; Kulshrestha, V.; Choubey, A.K.; Parulekar, A.H.

    ,301 insects belonging to 8 different orders, 47 families and 173 species were trapped. Of these, Hymenoptera was represented by the largest number (1082), which was followed by Hemiptera (1586), Diptera (552), Coleoptera (51), Neuroptera (10), Trichoptera (03...

  2. Dust depositions leading to phytoplankton blooms in the Arabian sea.

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, P.; PrasannaKumar, S.

    the standard deviations of the climatological values, we took up those cases for further study. In total we could identify only six cases of Chl a enhancements that can be attributed to dust derived nutrients. Since the prevailing current comes from...., 1995) showed that the deepening of mixed layer due to wind mixing or winter convection cannot supply DFe required to support the observed levels of Chl a enhancements for the six cases. Calculations of DFe that can be derived from modelled dust...

  3. Photosynthetically available radiation in the central and eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Desai, R.G.P.; Jayaraman, A.; Mehra, P.

    collected with quantum PAR sensor and maritime solar radiation models for clear sky. The peak values observed were in the range of about 1700 to 1830 mu mole s sup(-1) m sup(-2) or equivalent to about 365 to 435 Wm sup(-2) . The radiative transfer models...

  4. The oxygen minimum zone in the Arabian Sea during 1995

    Digital Repository Service at National Institute of Oceanography (India)

    Morrison, J.M.; Codispoti, L.A; Smith, S.L.; Wishner, K.; Flagg, C.; Gardner, W.D.; Gaurin, S.; Naqvi, S.W.A; Manghnani, V.; Prosperie, L.; Gundersen, J.S.

    at these depths. There are at least two groups of organisms, one that stays in the upper mixed layer and another that makes daily excursions. A subsurface zooplankton peak in the lower OMZ (near the lower 4.5 mu M oxycline) was also typically present...

  5. Seafloor spreading magnetic anomalies in the southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.; Bhattacharya, G.C.; Rao, D.G.

    28 or anom- aly 27) when the spreading centre jumped between India and Seychelles. This phase of spreading possibly ceased or became very slow sometime after the formation of anomaly 21. The spreading of the later phase commenced in its present... in our study area. Schlich (1975) recognized the existence of a brief normal polarity interval within these two relatively long normal polarity intervals of anom- aly 24. This interval was included as the third subchron (24N2) in the recent...

  6. Polychaete community structure of Indian west coast shelf, Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Joydas, T.V.; Jayalakshmy, K.V.; Damodaran, R.

    . Warwick, R. M., Mar. Ecol. Prog. Ser., 1988, 46, 167–170. 4. Ferraro, S. P. and Cole, F. A., Mar. Ecol. Prog. Ser., 1990, 67, 251–262. 5. Gray, J. S., Clarke, K. R., Warwick, R. M. and Hobbs, G., Mar. Ecol. Prog. Ser., 1990, 66, 285–299. 6. Gesteira...

  7. Nitrogen isotopic studies in the suboxic Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A; Yoshinari, T.; Brandes, J.A; Devol, A; Jayakumar, D.A; Narvekar, P.V.; Altabet, M.A; Codispoti, L.A.

    are 22 ppt and 25 ppt, respectively. A strong decrease in delta sup(15)N of NO sub(3) sup(-) is observed from approx 200 m (> 11 ppt) to 80 m (approx 6 pp5); this is attributed to the input of isotopically light nitrogen fixation. Isotopic analysis of N...

  8. Warm pool thermodynamics from the Arabian Sea Monsoon Experiment (ARMEX)

    Digital Repository Service at National Institute of Oceanography (India)

    Sengupta, D.; Parampil, S.R.; Bhat, G.S.; Murty, V.S.N.; RameshBabu, V.; Sudhakar, T.; Premkumar, K.; Pradhan, Y.

    driven upper ocean currents (e.g. Sun and Liu [1996]; Loschnigg and Webster [2000]; Clement et al. [2005]), and (c) enhanced evaporation over warm SST and redistribution of boundary-layer moisture or of elevated latent heating by large scale atmospheric... observations show the presence of shallow mixed layers, barrier layers and temperature inversions (Shenoi et al [2004], Shankar et al [2004]). In addition to salinity effects, the north Indian Ocean warm pool also becomes increasingly stably stratified...

  9. Processes controlling carbon components in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.; Rajendran, R.; Somasundar, K.; Ittekkot, V.; Desai, B.N.

    regions, while the concentrations are the highest in the northern part. TCO sub(2) relations with apparent oxygen utilization and phosphate suggest northward decrease in carbon dioxide production per unit oxygen consumption. Despite the high biological...

  10. Genetic characterization in four sciaenid species from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Menezes, M.R.; Naik, S.; Martins, M.

    stream_size 7 stream_content_type text/plain stream_name J_Fish_Biol_43_61.pdf.txt stream_source_info J_Fish_Biol_43_61.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  11. Factors controlling vertical fluxes of prrticles in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, T.M.B.; Ramaswamy, V.; Parthiban, G.; Shankar, R.

    whereas organic carbon percentages decreased. Particle flux patterns show a strong seasonality with peak fluxes during the southwest (SW) monsoon (June to September). Relatively high fluxes were also observed during the northeast (NE) monsoon (December...

  12. The biology of the Arabian Sea and Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Gauns, M.

    This article focusses on the variability in physics and chemistry of the region and investigate its influence on the biology. This article is largely based on the recent observations made during the India JGOFS and BOBPS (Bay of Bengal Process Study...

  13. Biochemical composition of zooplankton from the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, K.L.; Sreepada, R.A.; Ansari, Z.A.

    stream_size 7 stream_content_type text/plain stream_name Pak_J_Mar_Sci_2_17.pdf.txt stream_source_info Pak_J_Mar_Sci_2_17.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  14. Some aspects of the nitrogen cycling in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Noronha, R.J.; Shailaja, M.S.; Somasundar, K.; SenGupta, R.

    is unique in that it does not occur beneath centres of most intense seasonal upwelling; instead, it is most intense in offshore areas of relatively low primary productivity. Estimates of some important terms in the nitrogen cycling are evaluated...

  15. Upwelling in the Minicoy region of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, L.V.G.; Jayaraman, R.

    of the thin autoradio- graphic emulsion with improved resolution and the application of autoradiography to electron microscopy were considered by Dr. P. N. Shri- vastava (University of Rajasthan). Mr. S. D. Paiekar from the same University discussed...

  16. Ocean biogeochemistry and atmospheric composition: Significance of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Jayakumar, D.A.

    are mainly of biogenic origin 1 . Many organisms secrete CaCO 3 to build their hard skeletal parts either in the form of aragonite (e.g. corals) or calcite (e.g. foramini fera ). The oceanic surface waters are supersaturated with respect to both... these polymorphs, especially in the tropical regions, facilitating biological CaCO 3 production. The most important pathway through which the biota affects the carbon cycle is the fixation of inorganic carbon by organisms to build soft tissues. This is done...

  17. Status of mangroves along the countries bordering the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Untawale, A.G.; Wafar, S.; Jagtap, T.G.

    , the vegetation has been reduced completely. Deforestation and reclamation of mangrove forests for agriculture, construction purposes, urban development and industrialization are mainly responsible for its degradation...

  18. Biological control of surface temperature in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sathyendranath, S.; Gouveia, A.D.; Shetye, S.R.; Ravindran, P.; Platt, T.

    stream_size 99 stream_content_type text/plain stream_name Nature_349_54.pdf.txt stream_source_info Nature_349_54.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 © 1991 Nature Publishing Group... © 1991 Nature Publishing Group © 1991 Nature Publishing Group ...

  19. Meiofauna of the western continental shelf of India, Arabian Sea

    Science.gov (United States)

    Sajan, S.; Joydas, T. V.; Damodaran, R.

    2010-03-01

    Meiofaunal standing stock and nematode community structure were investigated in the western continental shelf of India by collecting samples from every degree square of the shelf during two cruises of the FORV ( Fishery and Oceanographic Research Vessel) Sagar Sampada, conducted in 1998 and 2001. Samples were collected from 30, 50, 100 and 200 m depths using a Smith Mc Intyre grab. Meiofaunal density ranged from 8 Ind. 10 cm -2 to 1208 Ind. 10 cm -2 and biomass from 0.07 mg 10 cm -2 to 6.11 mg 10 cm -2. Nematodes were the dominant meiofaunal group, contributing 88% of the density and 44% of the biomass. Harpacticoid copepods were the second important taxa, contributing 8% of both biomass and density. Altogether, 154 species of nematodes belonging to 28 families were recorded from the study area. Numerically, Desmodora spp., Dorylaimopsis sp. , Tricoma spp., Theristus spp. and Halalaimus spp. were the dominant species. In general, there was a decrease in biomass and density of meiofauna and species diversity of nematodes with increase in depth. There was a 67% drop in species number from 51 to 100 m (106 species) to the shelf edge (35 species). Species richness and diversity indices showed consistent decrease with depth. The species dominance index was higher below 150 m depth. ANOSIM (from PRIMER) showed a significant difference between the nematodes of the near shore and shelf edge. Latitudinal variation was observed only in the number of nematode species. Biomass and abundance of nematodes were found to increase from coarse to fine sediment, while copepods showed an opposite trend. Multivariate analyses of nematode communities did not reveal any latitudinal or substratum differences. Variables such as depth, latitude, organic matter (OM) and amount of clay were the most relevant parameters influencing the biomass and density of meiofauna, while depth and temperature were the important parameters explaining the distribution of the nematode communities along the western Indian shelf.

  20. The climatology of dust aerosol over the arabian peninsula

    Directory of Open Access Journals (Sweden)

    A. Shalaby

    2015-01-01

    Full Text Available 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

  1. Colour vision screening among Saudi Arabian children

    OpenAIRE

    O. Matthew Oriowo; Abdullah Z. Alotaibi

    2008-01-01

    Purpose: To determine the prevalence of congenital red-green colour vision defects among Saudi Arabian male and female children.Methods: The study involved 1638 elementary and high school participants (838 males, and 800 females), who were randomly selected and screened for red-green colour vision defects using the Ishihara (pseudo-isochromatic plates) test. Inclusion criteria were Snellen VA 20/20 or better and absence of known ocular pathologies.Among the females, 0.75% of the 800 participa...

  2. Uppermost mantle Pn Velocity of the Arabian Plate, a Preliminary study

    Science.gov (United States)

    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.

  3. Assessment of arsenic in coastal sediments, seawaters and molluscs in the Tarut Island, Arabian Gulf, Saudi Arabia

    Science.gov (United States)

    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.

  4. Distinctiveness of Saudi Arabian EFL Learners

    Directory of Open Access Journals (Sweden)

    Manssour Habbash

    2016-04-01

    Full Text Available In view of the increasing concern among English language teachers dealing with students from Saudi Arabia, as it manifests in TESOL community discussions, about the uniqueness of Saudi Arabian EFL learners, this paper attempts to document the outcome of a study of their distinctiveness from the perspective of expatriate teachers working for PYPs (Preparatory Year Programs in Saudi Arabia. This study examines the distinctiveness with regard to the learning attitudes of Saudi students that are often cultivated by the culture and academic environment in their homeland. Employing an emic approach for collecting the required data an analysis was carried out in light of the other studies on ‘education’ in Saudi Arabia that have particular reference to the factors that can positively influence student motivation, student success and the academic environment. The findings were used in constructing the rationale behind such distinctiveness. Assuming that the outcome of the discussion on the findings of this exploration can be helpful for teachers in adapting their teaching methodology and improving their teacher efficacy in dealing with students both from the kingdom and in the kingdom, some recommendations are made.Keywords: China Distinctiveness, Saudi Arabian University context, Expatriate teachers’ perspective, Distinctiveness Theory 

  5. Comparisons of the suture zones along a geotraverse from the Scythian Platform to the Arabian Platform

    Institute of Scientific and Technical Information of China (English)

    Ali Yılmaz; Shota Adamia; Hüseyin Yılmaz

    2014-01-01

    The area from the Greater Caucasus to the southeast Turkey is characterized and shaped by several major continental blocks. These are Scythian Platform, PontianeTranscaucasus Continent-Arc System (PTCAS), the AnatolianeIranian and the Arabian Platforms. The aim of this paper is to define these continental blocks and describe and also compare their boundary relationships along the suture zones. The Scythian Platform displays the evidence of the Hercynian and Alpine orogens. This platform is separated from the PTCAS by the Greater Caucasus Suture Zone. The incipient collision began along this suture zone before middleelate Carboniferous whereas the final collision occurred before Oligocene. The PTCAS can be divided into four structural units:(1) the Georgian Block e northern part of the PontianeTranscaucasian island-arc, (2) the southern and eastern Black Sea CoasteAdjaraeTrialeti Unit, (3) the ArtvineBolnisi Unit, comprising the northern part of the southern Transcaucasus, and (4) the Imbricated BayburteGarabagh Unit. The PTCAS could be separated from the AnatolianeIranian Platform by the North AnatolianeLesser Caucasus Suture (NALCS) zone. The initial collision was developed in this suture zone during Senonianeearly Eocene and final collision before middle Eocene or OligoceneeMiocene. The AnatolianeIranian Platform (AIP) is made up of the Tauride Platform and its metamorphic equivalents together with Iranian Platform. It could be separated from the Arabian Platform by the Southeastern Anatolian Suture (SEAS) zone. The collision ended before late Miocene along this suture zone. The southernmost continental block of the geotraverse is the Arabian Platform, which constitutes the northern part of the ArabianeAfrican Plate. This platform includes a sequence from the Precambrian felsic volcanic and clastic rocks to the Campanianeearly Maastrichtian flyschoidal clastics. All the suture zones include MORB and SSZ-types ophiolites in different ages. However, the ages of the

  6. Colour vision screening among Saudi Arabian children

    Directory of Open Access Journals (Sweden)

    O. Matthew Oriowo

    2008-01-01

    Full Text Available Purpose: To determine the prevalence of congenital red-green colour vision defects among Saudi Arabian male and female children.Methods: The study involved 1638 elementary and high school participants (838 males, and 800 females, who were randomly selected and screened for red-green colour vision defects using the Ishihara (pseudo-isochromatic plates test. Inclusion criteria were Snellen VA 20/20 or better and absence of known ocular pathologies.Among the females, 0.75% of the 800 participants showed CVD, with 0.25% and 0.5% demonstratingprotan and deutan defects, respectively.Conclusion: The results show that the prevalence of red-green colour deficiency among the female children from central Saudi Arabia is not significantly different from that of female populations inwestern countries.  The current prevalence among the males is higher than previously reported for central Saudi Arabia, but less than for Caucasian populations. 

  7. Monitoring of oil pollution in the Arabian Gulf based on medium resolution satellite imagery

    Science.gov (United States)

    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

  8. Remarks on the sea level records of the north Indian ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    - 1962) 25 Vishakhaptnam 0.34 90.0 Ko Taphao Noi (1940-2002) 58 Vishakhapatnam 0.29 95 Table 1: Linear correlation coefficient for the annual mean relative sea level for tide gauge records at stations in the Arabian Sea (Bay of Bengal...

  9. Between heaven and earth : the devil and the deep blue sea

    NARCIS (Netherlands)

    Linden, W.J.M. van der

    2006-01-01

    Between Heaven and Earth, The Devil and the Deep Blue Sea interweaves the story of planet Earth and the narrative of a marine geological expedition in the Arabian Sea. While specifically investigating the changes of the monsoon during Late Quaternary times, the expedition discloses aspects of the li

  10. Dynamics of sea level variations in the coastal Red Sea

    Science.gov (United States)

    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.

  11. The gravity field and crustal structure of the northwestern Arabian Platform in Jordan

    Science.gov (United States)

    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. Air-sea interaction over the Indian Ocean during the two contrasting monsoon years 1987 and 1988 studied with satellite data

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Schluessel, P.

    rainfall) and 1988 (excess rainfall). From these parameters the longwave radiative net flux at the sea surface and the ocean-air moisture flux are derived for further analysis of the air-sea interaction in the Arabian Sea, the Bay of Bengal, the south China...

  13. Temperature profile and water depth data collected from USS BARBEY using BT and XBT casts in the Indian Ocean and other seas from 02 December 1988 to 28 December 1988 (NODC Accession 8900015)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and water depth data were collected using BT and XBT casts from the USS BARBEY in the Indian Ocean, Arabian Sea, Gulf of Oman, Gulf of Iran, and...

  14. Meteorological fields variability over the Indian seas in pre and summer monsoon months during extreme monsoon seasons

    Indian Academy of Sciences (India)

    U C Mohanty; R Bhatla; P V S Raju; O P Madan; A Sarkar

    2002-09-01

    In this study, the possible linkage between summer monsoon rainfall over India and surface meteorological fields (basic fields and heat budget components) over monsoon region (30° E-120°E, 30°S-30°N) during the pre-monsoon month of May and summer monsoon season (June to September) are examined. For this purpose, monthly surface meteorological fields anomaly are analyzed for 42 years (1958-1999) using reanalysis data of NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research). The statistical significance of the anomaly (difference) between the surplus and deficient monsoon years in the surface meteorological fields are also examined by Student's t-test at 95% confidence level. Significant negative anomalies of mean sea level pressure are observed over India, Arabian Sea and Arabian Peninsular in the pre-monsoon month of May and monsoon season. Significant positive anomalies in the zonal and meridional wind (at 2m) in the month of May are observed in the west Arabian Sea off Somali coast and for monsoon season it is in the central Arabian Sea that extends up to Somalia. Significant positive anomalies of the surface temperature and air temperature (at 2m) in the month of May are observed over north India and adjoining Pakistan and Afghanistan region. During monsoon season this region is replaced by significant negative anomalies. In the month of May, significant positive anomalies of cloud amount are observed over Somali coast, north Bay of Bengal and adjoining West Bengal and Bangladesh. During monsoon season, cloud amount shows positive anomalies over NW India and north Arabian Sea. There is overall reduction in the incoming shortwave radiation flux during surplus monsoon years. A higher magnitude of latent heat flux is also found in surplus monsoon years for the month of May as well as the monsoon season. The significant positive anomaly of latent heat flux in May, observed over southwest Arabian Sea, may be considered

  15. The Caucasian-Arabian segment of the Alpine-Himalayan collisional belt:Geology, volcanism and neotectonics

    Institute of Scientific and Technical Information of China (English)

    E. Sharkov; V. Lebedev; A. Chugaev; L. Zabarinskaya; A. Rodnikov; N. Sergeeva; I. Safonova

    2015-01-01

    The Caucasian-Arabian belt is part of the huge late Cenozoic Alpine-Himalayan orogenic belt formed by collision of continental plates. The belt consists of two domains:the Caucasian-Arabian Syntaxis (CAS) in the south and the EW-striking Greater Caucasus in the north. The CAS marks a zone of the indentation of the Arabian plate into the southern East European Craton. The Greater Caucasus Range is located in the south of the Eurasian plate;it was tectonically uplifted along the Main Caucasian Fault (MCF), which is, in turn, a part of a megafault extended over a great distance from the Kopetdag Mts. to the Tornquist-Teisseyre Trans-European Suture Zone. The Caucasus Mts. are bounded by the Black Sea from the west and by the Caspian Sea from the east. The SN-striking CAS is characterized by a large geophysical isostatic anomaly suggesting presence of mantle plume head. A 500 km long belt of late Cenozoic volcanism in the CAS extends from the eastern Anatolia to the Lesser and Greater Caucasus ranges. This belt hosts two different types of volcanic rocks: (1) plume-type intraplate basaltic plateaus and (2) suprasubduction-type calc-alkaline and shoshonite-latite volcanic rocks. As the CAS lacks signatures of subduction zones and is characterized by relatively shallow earthquakes (50e60 km), we suggest that the “supra-subduction-type”magmas were derived by interaction between mantle plume head and crustal material. Those hybrid melts were originated under conditions of collision-related deformation. During the late Cenozoic, the width of the CAS reduced to ca. 400 km due to tectonic “diffluence” of crustal material provided by the continuing Arabia-Eurasia collision.

  16. The Origins of Islam in the Arabian context

    OpenAIRE

    Wang, Shutao

    2016-01-01

    This thesis investigates the origins of Islam, and their relations with the Arabian context, with the help of two types of materials - the Qur'an and Muslim tradition, and the archeological finds. First, I analyze the external and internal situations of pre-Islamic Arabia. Then, I discuss the conditions of Mecca and pre-Islamic Arabian polytheism, and their roles in the emergence of Islam. After that, I examine various monotheistic elements in Arabia that may form the origins of Islam, as wel...

  17. Radiation closure and diurnal cycle of the clear-sky dust instantaneous direct radiative forcing over Arabian Peninsula

    KAUST Repository

    Osipov, Sergey

    2015-04-01

    To better quantify radiative effects of dust over the Arabian Peninsula we have developed a standalone column radiation transport model coupled with the Mie calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments are carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18-20 March 2012. Comprehensive ground-based observations and satellite retrievals are used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing are estimated both from the model and from observations. Diurnal cycle of the the shortwave instantaneous dust direct radiative forcing is studied for a range of aerosol and surface characteristics representative for the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing are evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions along with anisotropic aerosol scattering are mostly responsible for diurnal effects. We also discuss estimates of the climatological dust instantaneous direct radiative forcing over land and the Red Sea using two approaches. The first approach is based on the probability density function of the aerosol optical depth, and the second is based on the climatologically average Spinning Enhanced Visible and Infrared Imager (SEVIRI) aerosol optical depth. Results are compared with Geostationary Earth Radiation Budget (GERB) derived top of the atmosphere climatological forcing over the Red Sea.

  18. On Selected Morphemes in Saudi Arabian Sign Language

    Science.gov (United States)

    Morris, Carla; Schneider, Erin

    2012-01-01

    Following a year of study of Saudi Arabian Sign Language (SASL), we are documenting our findings to provide a grammatical sketch of the language. This paper represents one part of that endeavor and focuses on a description of selected morphemes, both manual and non-manual, that have appeared in the course of data collection. While some of the…

  19. Observations on Word Order in Saudi Arabian Sign Language

    Science.gov (United States)

    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.…

  20. On Selected Phonological Patterns in Saudi Arabian Sign Language

    Science.gov (United States)

    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…

  1. Selected Lexical Patterns in Saudi Arabian Sign Language

    Science.gov (United States)

    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. The genus Nervilia (Orchidaceae) in Africa and the Arabian Peninsula

    NARCIS (Netherlands)

    Pettersson, Börge

    1991-01-01

    The orchidaceous genus Nervilia Comm. ex Gaud, is revised for Africa, including Madagascar and other islands, and the Arabian peninsula. Sixteen species are recognized, two of which are each subdivided into two varieties. Keys are presented for all taxa. Lectotypes or neotypes are given for all rele

  3. "Going Mobile" in Business Communication at an Arabian Gulf University

    Science.gov (United States)

    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…

  4. Five years MIQE guidelines: the case of the Arabian countries.

    Directory of Open Access Journals (Sweden)

    Afif M Abdel Nour

    Full Text Available The quantitative real time polymerase chain reaction (qPCR has become a key molecular enabling technology with an immense range of research, clinical, forensic as well as diagnostic applications. Its relatively moderate instrumentation and reagent requirements have led to its adoption by numerous laboratories, including those located in the Arabian world, where qPCR, which targets DNA, and reverse transcription qPCR (RT-qPCR, which targets RNA, are widely used for region-specific biotechnology, agricultural and human genetic studies. However, it has become increasingly apparent that there are significant problems with both the quality of qPCR-based data as well as the transparency of reporting. This realisation led to the publication of the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE guidelines in 2009 and their more widespread adoption in the last couple of years. An analysis of the performance of biomedical research in the Arabian world between 2001-2005 suggests that the Arabian world is producing fewer biomedical publications of lower quality than other Middle Eastern countries. Hence we have analysed specifically the quality of RT-qPCR-based peer-reviewed papers published since 2009 from Arabian researchers using a bespoke iOS/Android app developed by one of the authors. Our results show that compliance with 15 essential MIQE criteria was low (median of 40%, range 0-93% and few details on RNA quality controls (22% compliance, assays design (12%, RT strategies (32%, amplification efficiencies (30% and the normalisation process (3%. These data indicate that one of the reasons for the poor performance of Arabian world biomedical research may be the low standard of any supporting qPCR experiments and identify which aspects of qPCR experiments require significant improvements.

  5. Post-collisional deformation of the Anatolides and motion of the Arabian indenter: A paleomagnetic analysis

    International Nuclear Information System (INIS)

    In the Anatolides of Turkey the neotectonic (post collisional) phase of deformation embraces the period since final closure of the southern arm of Neotethys in mid-Miocene times. The Arabian Shield indenter has continued to deform into the weak Anatolian accretionary collage resulting from subduction of this ocean by a combination of differential movement relative to the African Plate and counterclockwise (CCW) rotation. Much of resulting deformation has been accommodated by slip along major transforms comprising the North Anatolian Fault Zone (NAFZ), the East Anatolian Fault Zone (EAFZ) and the northward extension of the Dead Sea Fault Zone (DSFZ) but has also been distributed as differential block rotations through the zone of weak crust in between. Facets of this deformation comprise crustal thickening and uplift to produce the Anatolian Plateau, establishment of transform faults and tectonic escape as Arabia has continued to impinge into the Anatolian collage. Paleomagnetic analysis of this deformation is facilitated by the widespread distribution of neotectonic volcanism and graben infills, and rotations relative to the Eurasian reference frame are recognised on two scales. Rapid rotation (up to 50/10,000 years) of small fault blocks is identified between master faults along the intracontinental transforms but deformation does not extend away from these zones and shows that seismogenic upper crust is decoupled from a lower continental lithosphere undergoing continuum deformation. The broad area of weak accreted crust between the transforms is dissected into large fault blocks which exhibit much lower rotation rates (mostly 0/100,000 years) that vary systematically across the Anatolides. Large CCW rotations near the Arabian indenter diminish westwards to become zero then CW near the limit of tectonic escape in western Turkey. The view that the collage has rotated anticlockwise as a single plate, either uniformly or episodically, during the Neotectonic era is

  6. Post-collisional deformation of the Anatolides and motion of the Arabian indenter: A paleomagnetic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Piper, J [Geomagnetism Laboratory, Department of Earth and Ocean Sciences, University of Liverpool, Liverpool, L69 7ZE (United Kingdom); Tatar, O; Gursoy, H; Mesci, B L; Kocbulut, F [Department of Geology, Cumhuriyet University, 58140 Sivas (Turkey); Huang, B [Palaeomagnetism and Geochronology Laboratory, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing (China)], E-mail: sg04@liverpool.ac.uk

    2008-07-01

    In the Anatolides of Turkey the neotectonic (post collisional) phase of deformation embraces the period since final closure of the southern arm of Neotethys in mid-Miocene times. The Arabian Shield indenter has continued to deform into the weak Anatolian accretionary collage resulting from subduction of this ocean by a combination of differential movement relative to the African Plate and counterclockwise (CCW) rotation. Much of resulting deformation has been accommodated by slip along major transforms comprising the North Anatolian Fault Zone (NAFZ), the East Anatolian Fault Zone (EAFZ) and the northward extension of the Dead Sea Fault Zone (DSFZ) but has also been distributed as differential block rotations through the zone of weak crust in between. Facets of this deformation comprise crustal thickening and uplift to produce the Anatolian Plateau, establishment of transform faults and tectonic escape as Arabia has continued to impinge into the Anatolian collage. Paleomagnetic analysis of this deformation is facilitated by the widespread distribution of neotectonic volcanism and graben infills, and rotations relative to the Eurasian reference frame are recognised on two scales. Rapid rotation (up to 5{sup 0}/10,000 years) of small fault blocks is identified between master faults along the intracontinental transforms but deformation does not extend away from these zones and shows that seismogenic upper crust is decoupled from a lower continental lithosphere undergoing continuum deformation. The broad area of weak accreted crust between the transforms is dissected into large fault blocks which exhibit much lower rotation rates (mostly < 1{sup 0}/100,000 years) that vary systematically across the Anatolides. Large CCW rotations near the Arabian indenter diminish westwards to become zero then CW near the limit of tectonic escape in western Turkey. The view that the collage has rotated anticlockwise as a single plate, either uniformly or episodically, during the

  7. Deep sea drilling in the Arabian Sea: Constraining tectonic-monsoon interactions in South Asia (Report)

    Digital Repository Service at National Institute of Oceanography (India)

    Pandey, D.K.; Clift, P.D.; Kulhanek, D.K.; Andò, S.; Bendle, J.A.P.; Bratenkov, S.; Griffith, E.M.; Gurumurthy, G.P.; Hahn, A.; Iwai, M.; Khim, B.-K.; Kumar, A.; Kumar, A.G.; Liddy, H.M.; Lu., H.; Lyle, M.W.; Mishra, R.; Radhakrishna, T.; Routledge, C.M.; Saraswat, R.; Saxena, R.; Scardia, G.; Sharma, G.K.; Singh, A.D.; Steinke, S.; Suzuki, K.; Tauxe, L.; Tiwari, M.; Xu, Z.; Yu, Z.

    @rediffmail.com Tallavajhala Radhakrishna Paleomagnetist/Petrologist Geosciences Division National Centre for Earth Science Studies Aakkulam Trivandrum 695031 India tradha1@rediffmail.com Claire M. Routledge Paleontologist (nannofossils) Department of Earth, Ocean... in this global type area for such studies. Introduction The theory of plate tectonics established that the solid Earth’s lithosphere interacts intimately with the underlying, circulating as- thenosphere. However, more recently the geoscience community has...

  8. Upper mantle structure under western Saudi Arabia from Rayleigh wave tomography and the origin of Cenozoic uplift and volcanism on the Arabian Shield

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Links between Synoptic Weather Types and Extreme Wet Events in the Arabian Peninsula (1960-2100)

    KAUST Repository

    El Kenawy, Ahmed M.

    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.

  10. Coral-associated Actinobacteria from the Arabian Gulf: diversity, abundance and biotechnological potentials

    Directory of Open Access Journals (Sweden)

    Huda Mahmoud Mahmoud

    2016-02-01

    Full Text Available Actinobacteria are widely distributed in terrestrial environments, where they are considered a significant source of bioactive compounds, mainly antibiotics. Marine Actinobacteria, particularly coral-associated Actinobacteria, have attracted attention recently. In this study, the abundance and diversity of Actinobacteria associated with Coscinaraea columna, Platygyra daedalea and Porites harrisoni, north of the Arabian Gulf were investigated. The corals of the Arabian Gulf, one of the world’s hottest seas, are thriving under extreme water temperatures that exceed 39°C during the summer. Similar water temperatures cause coral bleaching and death in other water bodies. For this reason, the corals of the Gulf are living models for investigating how corals in other settings may survive at the end of the current century.Different coral hosts have been found to harbor equivalent numbers of culturable Actinobacteria in their tissues but not in their mucus. However, different culturable actinobacterial communities have been found to be associated with different coral hosts. Differences in the abundance and diversity of Actinobacteria were detected between the mucus and tissue of the same coral host. In addition, temporal and spatial variations in the abundance and diversity of the cultivable actinobacterial communities were detected. In total, 19 different actinobacterial genera, namely Micrococcus, Brachybacterium, Brevibacterium, Streptomyces, Micromonospora, Renibacterium, Nocardia, Microbacterium, Dietzia, Cellulomonas, Ornithinimicrobium, Rhodococcus, Agrococcus, Kineococcus, Dermacoccus, Devriesea, Kocuria, Marmoricola and Arthrobacter, were isolated from the coral tissue and mucus samples. Furthermore, 82 isolates related to Micromonospora, Brachybacterium, Nocardia, Micrococcus, Arthrobacter, Rhodococcus and Streptomyces showed antimicrobial activities against representative Gram-positive and/or Gram-negative bacteria. Even though

  11. Major events in the late Precambrian to early Triassic geohistory of the Arabian Peninsula

    Energy Technology Data Exchange (ETDEWEB)

    Stump, T.E.; Connally, T.C.; Van der Eem, J.G.L.A. (Saudi Aramco, Dhahran (Saudi Arabia))

    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

  12. Arabian-Anatolian plate movements and related trends in Southeast Turkey's oilfields

    Energy Technology Data Exchange (ETDEWEB)

    Coskun, Bulent [Ankara Univ., Geological Engineering Dept., Ankara (Turkey)

    2004-09-15

    Two important tectonic phases generated by African and Arabian plate movements influenced the evolution of trends in SE Turkey's oilfields. The main phase occurred during the late Cretaceous (Maastrichtian) time, while the second phase reactivated the existing trends in Miocene. Paleogeological evolutions reveal that SE Turkey was tectonically stable from Paleozoic up to the end of Cretaceous, during which the structural trends were oriented in a WSW-ENE direction, contrarily, under the influence of opening of the Red Sea area, the existing trends rotated in a counterclockwise direction and oriented in a SW-NE direction. This rotational tectonic event is evidenced by SW-NE alignments of SE Turkey's oilfields in subsurface and Karacadag basaltic expansions and appearance of major faults, like the Dead Sea fault, Adiyaman fault, and Akcakale fault, on surface. Subsurface interpretations indicate that, contrarily to the previous works, which considered the Dead Sea fault and Adiyaman fault separate tectonic features from each other and also attached them to the East Anatolian fault, the Adiyaman fault is the continuity of the Dead Sea fault through the Adiyaman, Diyarbakir and Selmo areas. The Akcakale fault, which generated the Karacadag basaltic flows, is another tectonic element and has influenced the exploration activities in SE Turkey. Moreover, detailed interpretations of well data reveal that the SW-NE structural trends also improved reservoir conditions by creating fractures and dolomitizations in reservoir rocks, and the high geothermal and potential (piezometric) gradients and porosity trends are also aligned in the same direction. (Author)

  13. Ecology, genetic population structure, and molecular phylogeny of fishes on coral reefs in the Gulf of Aqaba and northern Red Sea

    OpenAIRE

    Kochzius, Marc

    2002-01-01

    Aim of this thesis is the study of biogeography and ecology, genetic population structure, and molecular phylogeny of fishes on coral reefs in the Gulf of Aqaba and northern Red Sea. Ecological and genetic pattern are compared on different spatial scales and molecular markers add a temporal scale to study of evolutionary processes.Biogeographic analysis supported the differentiation of the Arabian sub-province from the Indian Ocean, but the affiliation of the Arabian Gulf is not clear.The ana...

  14. DNA polymorphism of Arabian, thoroughbred and Anglo-Arabian Horses in Morocco: Application to identification of individual horses and parentage verification

    International Nuclear Information System (INIS)

    Full text: New techniques of molecular biology used in analyzing DNA polymorphism give access to the whole genetic variability of a given individual while the traditional blood typing (red cell typing and biochemical polymorphisms) gives access only to the transcribed fraction which is then translated to protein. In addition, this fraction represents only a very small part (5-10%) of the genome's incoding fraction. One of the newer testing methods in identifying horses is a DNA-based test using microsatellite marker analysis. The objective of this work was to evaluate the efficacy of this new technology in the identification and parentage verification of Arabian, Thoroughbred and Anglo-Arabian horses in Morocco. Anglo-Arabian horse is a crossbreed between Arabian and Thoroughbred. Three samples from the three breeds were analyzed for 12 microsatellites (HMS2, HMS3, HMS6, HMS7, HTG4, HTG6, HTG7, AHT4, AHT5, VHL20, HTG10 and ASB2). A total of 1541 horses were used: 804 Arabians, 559 Thoroughbreds and 178 Anglo-Arabians. Allelic frequencies of the 12 studied systems were calculated in the three groups. The results allowed the determination of intra-population genetic parameters: heterozygosity ratio (H), probability of identification (PI) and probability of exclusion (PE). Based on average heterozygosity ratio, variability was relatively lower in Thoroughbred horse (.7036), while it was almost the same in Arabian and Anglo-Arabian horses (respectively .7217 and .7232). Probabilities of exclusion obtained with the 12 systems were higher than 99.9% for the three studied populations and probabilities of identification of individual horses were 15 x 10-12, 4 x 10-12 and 20 x 10-12 in Thoroughbred, Arabian and Anglo-Arabian horses respectively. These results indicate that the test using microsatellite marker analysis constitute a highly efficient and reliable alternative for the identification of individual horses and parentage verification and is a useful tool for horse

  15. Evaluation of foaling heat in Arabian mares in Ninevah province

    OpenAIRE

    M. A. Rahawy

    2012-01-01

    The present study was conducted to study the relationship between breeding season of Arabian mares at first estrous afterfoaling and pregnancy rate. Thirty six mares were divided in to two groups according to foaling heat in breeding season,transitional periods. Animals included in this study were maintained with the same management and conditions in the specialbreeding stables. This study was performed in a farm located in Nineveh province during the period from June 2008 to June2010. The ma...

  16. Renewable energies management strategy challenges in the Arabian Gulf countries

    OpenAIRE

    Aloughani, Muhammad

    2015-01-01

    This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London The main source of energy in the Gulf Cooperation Council (GCC) remains fossil fuels (oil and gas). The massive and accelerated used of such sources of energy not only depletes the traditional energy sources in those states and thus undermines exports and long-term prosperity; it also causes devastating damages to the environment and to human health. The nature of the Arabian Peninsu...

  17. Multiscale Local Forcing of the Arabian Desert Daytime Boundary Layer, and Implications for the Dispersion of Surface-Released Contaminants.

    Science.gov (United States)

    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

  18. Forgotten in the taxonomic literature: Resurrection of the scleractinian coral genus Sclerophyllia (Scleractinia, Lobophylliidae) from the Arabian Peninsula and its phylogenetic relationships

    KAUST Repository

    Arrigoni, Roberto

    2014-11-21

    The monospecific scleractinian coral genus Sclerophyllia Klunzinger, 1879 was originally described from Al-Qusayr (Egypt) in the Red Sea based on a series of solitary specimens. Thenceforth, it has been considered a junior synonym of Symphyllia and Cynarina based on corallum macromorphology. In this study, several specimens of Sclerophyllia margariticola were collected on the coasts of Saudi Arabia in the northern and central Red Sea. Four molecular markers were sequenced, COI and the intergenic spacer between COI and l-rRNA from mitochondrial DNA and Histone H3 and ribosomal ITS2 from nuclear DNA. Phylogenetic trees and haplotype network analyses show that S. margariticola belongs to the family Lobophylliidae and that it is closely related to Acanthastrea maxima, an uncommon species from waters around the Arabian peninsula (the Gulf of Aden, Arabian Sea, Gulf of Oman and Persian Gulf). Sclerophyllia margariticola and A. maxima share several macro- and micromorphological characters, such as the presence of free septa, high elliptical septal teeth perpendicular to the septal margin, irregular lobate tips, very wide tooth spacing, a very strong granulation with granules scattered all along the septal sides, and a palisade interarea structure, and their micromorphology differs substantially from that of Acanthastrea echinata, the type species of Acanthastrea. Therefore, we formally resurrect Sclerophyllia, provide a revised diagnosis for the genus, and move A. maxima into Sclerophyllia.

  19. Arabian killifish (Aphanius dispar) embryos: A model organism for the risk assessment of the Arabian Gulf coastal waters.

    Science.gov (United States)

    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 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's findings support the ability of killifish to be an indicator organism for environmental risk assessments of Arabian Gulf waters. Benefits include sensitivity to a wide range of substances and conditions, animal alternative, ease of fish breeding, and clarity of the embryos. PMID:26184573

  20. On the origin of endemic species in the Red Sea

    KAUST Repository

    DiBattista, Joseph

    2015-10-19

    Aim The geological and palaeo-climatic forces that produced the unique biodiversity in the Red Sea are a subject of vigorous debate. Here, we review evidence for and against the hypotheses that: (1) Red Sea fauna was extirpated during glacial cycles of the Pleistocene and (2) coral reef fauna found refuge within or just outside the Red Sea during low sea level stands when conditions were inhospitable. Location Red Sea and Western Indian Ocean. Methods We review the literature on palaeontological, geological, biological and genetic evidence that allow us to explore competing hypotheses on the origins and maintenance of shallow-water reef fauna in the Red Sea. Results Palaeontological (microfossil) evidence indicates that some areas of the central Red Sea were devoid of most plankton during low sea level stands due to hypersaline conditions caused by almost complete isolation from the Indian Ocean. However, two areas may have retained conditions adequate for survival: the Gulf of Aqaba and the southern Red Sea. In addition to isolation within the Red Sea, which separated the northern and southern faunas, a strong barrier may also operate in the region: the cold, nutrient-rich water upwelling at the boundary of the Gulf of Aden and the Arabian Sea. Biological data are either inconclusive or support these putative barriers and refugia, but no data set, that we know of rejects them. Genetic evidence suggests that many endemic lineages diverged from their Indian Ocean counterparts long before the most recent glaciations and/or are restricted to narrow areas, especially in the northern Red Sea. Main conclusions High endemism observed in the Red Sea and Gulf of Aden appears to have multiple origins. A cold, nutrient-rich water barrier separates the Gulf of Aden from the rest of the Arabian Sea, whereas a narrow strait separates the Red Sea from the Gulf of Aden, each providing potential isolating barriers. Additional barriers may arise from environmental gradients