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Sample records for arabian sea

  1. 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.

    Despite their importance for the global oceanic nitrogen (N) cycle, estimates of N fluxes in the Arabian Sea remain in considerable uncertainty. In this report, we summarize current knowledge of important processes, including denitrification, N sub...

  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. Living coccolithophorids from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Mohan, R.; Muralinath, A.S.

    Coccolithophorids collected from the euphotic zone in the Arabian Sea during the tail end of summer monsoon (Sept. 20 to Oct. 06, 1992) were studied. Nineteen species were recorded, most abundant among them were, Emiliania buxleyi, Umbellosphaera...

  5. Submarine physiography off Lakshadweep Islands, Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S; Chaubey, A

    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...

  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. Nitrous oxide in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W; Noronha, R.J

    Measurements of nitrous oxide (N2O) at 16 stations in the Arabian Sea reveal high degrees of surface saturation (186 plus or minus 37%) and consequently large atmospheric fluxes of N2O (4.46 plus or minus 2.60 mu mol m-2day-1). Vertical distribution...

  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.

    production in the western Arabian Sea, relatively low CaCO sub(3) dissolution (approximately 100 mol dm/3 near and below 3000m) is attributed to skeletal material incorporation into faecal material and the subsequent faster deposition rates. Arabian Sea water...

  10. 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...

  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. Mechanism of the biological response to winter cooling in the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; PrasannaKumar, S.; Bhattathiri, P.M.A.; DileepKumar, M.; Raghukumar, S.; Nair, K.K.C.; Ramaiah, N.

    The Arabian Sea is one of the most biologically productive ocean regions, mainly due to the upwelling of nutrients during the summer (southwest) monsoon. But the northern Arabian Sea continues to sustain fairly high biological production after...

  16. 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.

  17. Abundance of Thraustochytrid fungi in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

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

    to 13 July 1987 during the monsoon period-61 samples from 23 stations in the upwelling parts of the south-eastern Arabian Sea. Surface and 30 m depth were sampled in the eight shallower, nearshore stations,A2, B2, Cl,Dl,El, Fl, Gl andH1 withdepthsnot... Estuarine, Coastal and Shelf Science (1990) 31,351-358 Abundance of Thraustochytrid Fungi in the Arabian Sea S. Raghukumar, Chandralata Raghukumar and A. Rajendran National Institute of Oceanography, Dona Paula, Goa 403 004, India Received 24 April...

  18. 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.

  19. 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.

    monsoons. Our revised estimate for the annual N sub(2)O flux from the Arabian Sea is much more tightly constrained than the previous consensus derived using averaged in-situ data from a smaller number of studies. However, the tendency to focus...

  20. 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.

    Air borne insects, mostly carried by wind currents, were trapped over the northern Arabian Sea (16 degrees to 20 degrees N; 68 degrees to 72 degrees E), in the course of cruise No. 111, ORV Sagar Kanya (March 14 to April 7, 1996). A total of 2...

  1. 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.

    in the intensity of the oxygen-deficient conditions is providEd. by data on the nitrogen system as well as the activity of the electron transport system (ETS). The results imply a quick renewal of the oxygen-depleted waters. Denitrification in the Arabian Sea...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.; 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...

  3. 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.

    due to nitrogen fixation either in the Arabian Sea or in the ODZ source waters, anammox, or sedimentary denitrification. Nitrate deficit based estimates of overall denitrification rate are about 40 Tg N a sup(-1), but if the larger excess nitrogen gas...

  4. 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.

    Sediment trap samples collected from a depth of 1018m in the Central Arabian Sea Trap (CAST) at 14 degrees 28.2 minutes N, 64 degrees 35.8 minutes E were analyzed for temporal variation of coccolithophore fluxes from October 1993 to August 1994. Out...

  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.

    climate of the eastern Arabian Sea (AS). Using measured, modeled and reanalysis wave data and reanalysis wind data, we show that the IOD plays a major role in the variability of wave climate of the study region. Due to the IOD-induced changes in equatorial...

  6. 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.

    tunicates which are able to feed on very small particles. It would seem that the Arabian Sea sustains a large biomass of mesopelagic fishes (about 100 million tonnes), mainly myctophids. They mostly live in the core of oxygen minimum layer and ascend...

  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.

    sub(2) and oxygen (O sub(2)), respectively] have been made in water column at several locations in the Arabian Sea, a region with one of the thickest and most intense O sub(2) minima observed in the open ocean. Microbially-mediated reduction of NO sub...

  8. 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 ...

  9. 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...

  10. 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].

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

    Directory of Open Access Journals (Sweden)

    H. W. Bange

    2001-09-01

    Full Text Available We computed high-resolution (1o latitude × 1o longitude seasonal and annual nitrous oxide (N2O concentration fields for the Arabian Sea surface layer using a database containing more than 2400 values measured between December 1977 and July 1997. N2O concentrations are highest during the southwest (SW monsoon along the southern Indian continental shelf. Annual emissions range from 0.33 to 0.70 Tg N2O and are dominated by fluxes from coastal regions during the SW and northeast monsoons. However, the tendency to focus on measurements in locally restricted features in combination with insufficient seasonal data coverage leads to considerable uncertainties of the concentration fields and thus in the flux estimates, especially in the coastal zones of the northern and eastern Arabian Sea.

  12. Nitrogen isotopic studies in the suboxic Arabian sea

    International Nuclear Information System (INIS)

    Measurements of 15N/14N in dissolved molecular nitrogen (N2), nitrate (NO3) and nitrous oxide (N2O) and 18O/16O in N2O [expressed as δ15N and δ18O, relative to atmospheric N2 and oxygen (O2), respectively] have been made in water column at several locations in the Arabian sea, a region with one of the thickest and most intense O2 minima observed in the open ocean

  13. 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...

  14. 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.

    The response of the Arabian Sea to global warming is the disruption in the natural decadal cycle in the sea surface temperature (SST) after 1995, followed by a secular warming. The Arabian Sea is experiencing a regional climate-shift after 1995...

  15. Composition of heteropods in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Aravindakshan, P.N.; Stephen, R.

    Distribution of species of Atlantidae, Carinariidae and Pterotracheidae in the Andaman Nicobar Sea is discussed in this paper based on samples of FORV Sagar Sampada. Oxygrus Keraudreni and Protatlanta souleyeti are reported for the first time from...

  16. 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...

  17. Sound speed structure in the Arabian Sea and the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Navelkar, G.S.; Murty, T.V.R.; Somayajulu, Y.K.; Murty, C.S.

    Sound speed computed from annual mean temperature and salinity data of Levitus reveals that spatial variation in the Arabian Sea is greater than that in the Bay of Bengal. Maximum spatial variation of sound speed in the Arabian Sea noticed between...

  18. 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... upwelling effects yet to reach the surface (Figures 3d, 3e & 3f). The vertical distribution of NO3- and SiO44- revealed high concentrations at the surface layers along south west coast of India (Fig. 3). Horizontal distribution of NO3- at the depths of 0, 10...

  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. Surface layer temperature inversion in the Arabian Sea during winter

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Ghosh, A.K.

    ; Prabhakara Rao et al., 1987; Rao et al., 1983). Since the feature is having a transient nature, a good data coverage both in time and space scale is required to study. The BT traces collected onboard RV. Gaveshani and ORV. Sagarkanya from this area form... is provided to examine the magnitude of the forcing mechanisms. 2. Material and Methods BT traces collected at 1132 stations from the south eastern Arabian Sea during different cruises of RV. Gaveshani (1976–1986) and ORV. Sagarkanya (1983–1986) have been...

  1. 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.

    , 2001; Upstill-Goddard, Barnes, Frost, Punshon, & Owens, 2000). Based on the only major study of CH 4 carried out in the Arabian Sea prior to JGOFS (Owens, Law, Mantoura, Burkill, & Llewellyn, 1991), it was thought that this region could be of key...–186%) in surface waters (Law & Owens, 1990; Naqvi & Noronha, 1991). This prompted additional, more-detailed investigations under JGOFS and other contemporary programs. In this section we provide a synthesis of the ensuing data, focusing primarily on the surface N 2...

  2. 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.

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

    OpenAIRE

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

    2009-01-01

    Abstract The response of the Arabian Sea to global warming is the disruption in the natural decadal cycle in the sea surface temperature (SST) after 1995, followed by a secular warming. The Arabian Sea is experiencing a regional climate-shift after 1995, which is accompanied by a 5-fold increase in the occurrence of ?most intense cyclones?. Signatures of this climate-shift are also perceptible over the adjacent landmass of India as: (1) progressively warmer winters, and (2) decreas...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.; DileepKumar, M.; Gauns, M.; Madhupratap, M.

    is to understand the seasonal variability in the surface pCO2 abundance and its control by physical and biological factors in the central and eastern Arabian Sea. 2. Methods Five cruises (figure 1) were undertaken on board ORV Sagar Kanya during April -- May 1994... in the Arabian Sea. In: A Voyage of Discovery (ed) M Angel, (Oxford: Pergamon Press) pp. 291--304 Somasunder K, Rajendran A, Kumar M D and Sen Gupta R 1990 Carbon and nitrogen budgets of the Arabian Sea; Mar. Chem. 30 363--377 Swallow J C 1984 Some aspects...

  5. '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.

    off Ratnagiri and Dwarka, and at 3 hours interval off Goa with a sampling period of 20 minutes. The wave rider buoy has an accuracy of 3% for wave height and within 0.5 - 2° for wave direction. Wind sea and swell parameters were calculated from..., especially in the north- western Arabian Sea and in the Arabian Peninsula. These winds are associated with shamal events (active shamal area is marked in Figure 1a). Typical wind vectors in the Arabian Sea during NE monsoon and during shamal events...

  6. 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.

    NO ~mol dm -3) 294.23 299.59 Denitrification in the Arabian Sea 601 I0 \\[ '' zx, . ,.339 zx,,,-o.99 / .., / 2! / il / ,o,. /. f.- . o l (tS*N) / ." J * J (16"30') / f AK(tS"N) / _ /~ +M(21"N)

  7. 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.

  8. 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.

  9. 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.

    . This provides a mechanism for the injection of appreciable quantities of labile dissolved organic carbon (DOC) into the oxygen-minimum layer and, in conjunction with the high horizontal diffusivity in the Arabian Sea, could account for the observed lack...

  10. 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...

  11. 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...

  12. 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...

  13. Abrupt climate-induced changes in carbonate burial in the Arabian Sea: Causes and consequences.

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Singh, A.D.; Ganeshram, R.S.; Bharti, S.K.

    experienced large declines in monsoon-driven productivity and greater penetration of Antarctica Intermediate Water (AAIW). Thus, pteropod preservation in the Arabian Sea appears to be linked to rapid climate change through atmospheric and oceanic...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.A.S.; 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...

  15. A first report on a bloom of the marine prymnesiophycean, Phaeocystis globosa from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; Sawant, S.S.; Gauns, M.

    A thick bloom of the marine prymnesiophycean, Phaeocystis globosa was observed in the central Arabian Sea during the summer monsoon period (July-August, 1996). The cells were mostly in colonial form, embedded in gelatinous matrics. The cell diameter...

  16. 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...

  17. 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.

    found to be much lower than the values presently used in routine conversion factors. Such factors are now essentially needed for accounting role of zooplankton in sediment trap collections in Arabian Sea region...

  18. 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...

  19. Early tertiary seafloor spreading magnetic anomalies and paleo-propagators in the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.; Bhattacharya, G.C.; Murty, G.P.S.; Srinivas, K.; Ramprasad, T.; Rao, D.G.

    Study of closely spaced new marine magnetic profiles, in conjunction with published magnetic data, provide an updated identification of linear magnetic anomalies in the northern Arabian Sea from the Owen Fracture Zone in the west to the Laxmi...

  20. 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...

  1. 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.

    in the total assemblage in addition to oxygen isotope variations in planktonic foraminifera. Using sub-surface sediments as the source, and the above techniques as tools, a number of palaeoclimatic reconstructions have been made for the Arabian Sea Region...

  2. 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...

  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. 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.

    WATERVAPOURFLUXDIVERGENCEOVERTHE ARABIAN SEA DURING 1987 SUMMER MONSOON USING SATELLITE DATA (Research Note) P. N. VINAYACHANDRAN and M. R. RAMESH KUMAR Physical Oceanography Division, National Institute of Oceanography, Dona Paula 403004, Goa, India (Received in final form... 19 September, 1989) Abstract. The evaporation rates over the Arabian Sea (AS) for the summer monsoon months (June to September) of 1987 have been computed using the bulk-aerodynamic formula. The satellite derived precipitation from the INSAT-1B...

  5. Carbonate and carbon fluctuations in the Eastern Arabian Sea over 140 ka: Implications on productivity changes?

    Science.gov (United States)

    Guptha, M. V. S.; Naidu, P. Divakar; Haake, Birgit Gaye; Schiebel, Ralf

    2005-07-01

    Biological productivity in the western Arabian Sea was higher during interglacial than glacial times. In the eastern Arabian Sea productivity was higher during the glacials compared to interglacials, which is in sharp contrast to the southwest monsoon intensity variations. To examine temporal changes in productivity in the eastern Arabian Sea over the last 140 ka, oxygen isotopes, calcium carbonate and organic carbon on three cores (SL-1 & 4 and SK 129-CR05) were analyzed. Oxygen isotope records display distinct glacial and interglacial transitions. In the northeastern (Core SL-1) and eastern Arabian Sea (Core SL-4) both calcium carbonate and organic carbon variations show no significant systematic relationship with glacial and interglacials periods. In the southeastern Arabian Sea (Core SK-129-CR05) calcium carbonate shows high and low values during interglacial and glacials, respectively, and temporal changes in organic carbon concentration are significant only during MIS 5. Differential variation of calcium carbonate and organic carbon concentration at the northeastern and southeastern Arabian Sea, and between glacials and interglacials, are attributed to regional differences in sedimentation rates, dilution and preservation, which modify the signal of carbonate and carbon production.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

    Time-series observations at a nominally fixed location in the northern Arabian Sea (21 degrees N, 64 degrees E) during the Northeast Monsoon (winter, February) of 1997 showed the prevalence of cold sea-surface temperatures (SST) and deep mixed...

  10. 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...

  11. The Arabian Sea as a high-nutrient, low-chlorophyll region during the late southwest monsoon

    Digital Repository Service at National Institute of Oceanography (India)

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

    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...

  12. 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.

    An analysis of the heat budgets of the near-surface Arabian Sea and Bay of Bengal shows significant differences between them during the summer monsoon (June-September). In the Arabian Sea the winds associated with the summer monsoon are stronger...

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    in the Arabian Sea is driven by net heat loss from the ocean, whereas the Bay of Bengal does not contribute to such large heat loss to the atmosphere. It appears that the subduction of high saline Arabian Sea water mass is the mechanism behind the formation of a...

  14. 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.

  15. 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.

  16. 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.

  17. Recently studied sedimentary records from the eastern Arabian Sea: Implications to Holocene monsoonal variability

    Digital Repository Service at National Institute of Oceanography (India)

    Agnihotri, R.; Kurian, S.

    ://www.earthscienceindia.info/Agnihotri.htm 1 of 14 10/15/2008 9:41 AM Earth Science India Vol.1 (IV), October, 2008, pp. 258-287 http://www.earthscienceindia.info/ Recently studied sedimentary records from the eastern Arabian Sea: Implications to Holocene monsoonal variability Rajesh... biogenic (organic and inorganic) proxies with minimal particle reworking through bioturbation. Agnihotri http://www.earthscienceindia.info/Agnihotri.htm 2 of 14 10/15/2008 9:41 AM Figure 1: Satellite pictures of the Arabian Sea revealing seasonal contrast...

  18. 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

    inflow in several branches from the east across the Arabian Sea, and then flows southwards to meet the northward- flowing East African Coastal Current at 2--4?S. These two flows supply the eastward- flowing South Equatorial Counter Current. Material... variation of pteropods from the Western Arabian Sea sediment trap R. Mohan*1, K. Verma1, L.P. Mergulhao3, D.K. Sinha2, S. Shanvas1, M.V.S. Guptha3# *Corresponding author: rahulmohan@ncaor.org 1National Centre for Antarctic and Ocean Research, Goa 403...

  19. 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 population, swarming of Ostracoda, Euphasidacea and Decapoda larvae occurred in many stations as observed in northern Arabian Sea (Paulinose and Aravindhakshan 1977, Daniel and Jyothi- nayagam 1977). The Average number for most of the plankton groups far... community. High density . of 105 per l00m3 was observed mostly in the northern Arabian Sea and in the Gulf of Aden. No marked diurnal variation was observed. Highest density of 386043 per 100 m3 was recorded at station 88. Ostracods were observed in swarms...

  20. 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

  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.

    ] and the Arabian Sea [Subrahmanyam et al., 2002] as also from other oceanic areas [e.g., Lin et al., 2003; Babin et al., 2004]. However, with few exceptions [e.g., Fogel et al., 1999], these reports have been based on satellite-derived ocean color and temperature... blooms of phytoplankton in the Arabian Sea as observed by the coastal zone color scanner, Mar. Ecol. Prog. Ser., 34, 201–211, doi:10.3354/meps034201. Barber, R. T., J. Marra, R. C. Bidigare, L. A. Codispoti, D. Halpern, Z. Johnson, M. Latasa, R. Goericke...

  2. Lithogenic fluxes to the deep Arabian Sea measurEd. by sediment traps

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Nair, R.R.; Manganini, S.J.; Haake, B.; Ittekkot, V.

    LLA and COUMES, 1984). Other sources, such as the rivers draining the west coast of India, as well as eolian input from the arid regions of North Africa, Arabia, Pakistan and India, also have contributed variable amounts of lithogcnic material (WEaER, 1974..., 1983, and references therein). The principal rivers draining into the Arabian Sea are the Indus, Narmada and Tapti (Fig. 1). Clay mineral studies of the Arabian Sea sediments show that illite (>40%), contributed mostly by the Indus River, is the most...

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. Inorganic combined nitrogen budget of the Arabian Sea: Some geochemical and climatic implications

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    Estimates of the local sources and sinks of inorganic combined nitrogen in the Arabian Sea suggest a net loss of sup(-)3 x 10 sup(13) gN y sup(-1). This seems to be made up largely by the upward flux facilitatEd. by a high rate of upwelling...

  8. Signatures of global warming and regional climate shift 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.

    is perceptible over the adjacent landmass of India, as decreased decadal monsoon rainfall and in the Arabian Sea as increase in phytoplankton biomass. The decrease in rainfall after 1995 was linked to the increase in the Eurasian winter snow cover. The increased...

  9. Controlling factors of the oxygen balance in the Arabian Sea's OMZ

    Digital Repository Service at National Institute of Oceanography (India)

    Resplandy, L.; Levy, M.; Bopp, L.; Echevin, V.; Pous, S.; Sarma, V.V.S.S.; Kumar, M.D.

    the processes governing OMZs. In this study, we examine the factors controlling the oxygen budget, i.e. the equilibrium between oxygen sources and sinks in the northern Arabian Sea OMZ using an eddy-resolving biophysical model. Our model confirms...

  10. 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...

  11. 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.

    of carbon dioxide to atmosphere reached a maximum of approx 40 m mole m sup(-2) d sup(-1) around 16 degrees N in the central Arabian SEa during monsoon season. The carbon dioxide regenerated from soft tissue was higher during winter and is the least...

  12. 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

    : JGOFS (INDIA) Seasonal variability in oxygen and nutrients in the central and eastern Arabian Sea S. N. de Sousa, M. Dileep Kumar, S. Sardessai, V. V. S. S. Sarma and P.V. Shirodkar National Institute of Oceanography, Dona Paula, Goa 403 004, India...

  13. 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...

  14. 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.

    this bloom flourishes in offshore waters of the Arabian Sea. T. erythraeum blooms were noticed in the coastal waters during the March to May and in the offshore waters during the April-May period. During the months from March-April a mixed bloom...

  15. 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...

  16. 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.

    The effect of a tropical cyclone on the variation of phytoplankton biomass in terms of surface chlorophyll-a is brought out based on satellite observations and mixed layer model simulations in the Arabian Sea during 21 May-3 June 2001. Along...

  17. 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.

    supersaturations are found to be 140 plus or minus 37, 173 plus or minus 54, and 200 plus or minus 74 in the northeast monsoon, intermonsoon, and southwest monsoon, respectively. Wind speed dependent flux estimation reveals the coastal region of the Arabian Sea...

  18. 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.

    are overlain by a thick and intense denitrification layer, which may cause reductive dissolution of Mn oxides from settling particles and consequently low Mn sub(ex) fluxes. As the exchange of intermediate waters between the Arabian Sea and the rest...

  19. Otoliths in continental shelf and slope surficial sediments off Saurashtra, Arabian Sea, India and their significance

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; John, S.; Rana, R.S.

    is in progress and will be reported in due course. This preliminary report which is the first report from the northern Arabian Sea on fossil fish otolith may help as an additional tool in the reconstruction of paleoenvironment and in assessing the latitudinal...

  20. Aerosol optical thickness and spatial variability along coastal and offshore waters of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Menon, H.B.; Sangekar, N.; Lotliker, A.; Moorthy, K.K.; Vethamony, P.

    Data from the ocean-colour monitor (OCM) on board the Indian Remote Sensing Satellite P4 were used to analyse the spatial and temporal distribution of aerosol optical thickness (AOT) over the coastal and offshore waters of the eastern Arabian Sea...

  1. Tracing the strength of the southwest monsoon using boron isotopes in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.S.; Naidu, P.D.; Foster, G.L.; Martínez-Boti, M.A.

    Here we present the first boron isotope-based pCO2sw (pCO2 of seawater) reconstruction from the eastern Arabian Sea using the planktic foraminifera species Globigerinoides ruber. Our results from sediment core AAS9...

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

    NARCIS (Netherlands)

    Reichart, G.-J.

    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. Seasonally reversing current bands across 15 degrees N in the Arabian Sea and their implications

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, M.K.; Shenoi, S.S.C.; Gopalakrishna, V.V.; Murty, C.S.; Rao, D.P.; Murty, V.S.N.; Sastry, J.S.

    Geostrophic currents computed from hydrographic data collected in different months from a section along 15 degrees N in the Arabian Sea show alternate N-S current bands. Flow directions of these bands are found to reverse with the change in season...

  4. 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...

  5. 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.

  6. Does SW Monsoon Influence Total Suspended Matter Flux into the Arabian Sea?

    Digital Repository Service at National Institute of Oceanography (India)

    Raghavan, B.R.; Chauhan, O.S.

    al., 1989; Haake et al., 1993; 1996; Rixen et al., 2009). These studies have reported an enhanced supply of particulate matter into the entire Arabian Sea during the southwest monsoon (SWM). The prevalence of an intense rainfall, an augmented... not enhance during the SWM. Besides land supply, water column biogeochemical processes sustaining marine productivity were linked also with the augmentation of flux of suspended particulate matter (Haake et al., 1993 and references therein). Sea bed...

  7. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Sanil Kumar, V.; Anoop, T.R. [CSIR-National Institute of Oceanography (Council of Scientific and Industrial Research), Goa (India)

    2013-11-01

    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 almost parallel to the coast, the difference between mean and principal wave direction at spectral peak is negligible. The directional spreading of wind-sea-dominated wave spectrum is less than that of the swell-dominated spectrum. Average value of the ratio of the directional width at twice the peak frequency and that at the peak frequency is 1.9 indicating that the directional width increased at higher frequency. Even though both locations studied are along the eastern Arabian Sea, there are more northwest waves due to shamal events and local winds found at the northern location (27 %) than at the southern location (7 %).

  9. 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...

  10. Lack of seasonal and geographic variation in mesozooplankton biomass in the Arabian Sea and its structure in the mixed layer

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; Gopalakrishnan, T.C.; Haridas, P.; Nair, K.K.C.; Aravindakshan, P.N.; Padmavati, G.; Paul, S.

    by carnivores. A few species, common in all seasons, accounted the majority of the population. The 'paradox' of the Arabian Sea, that zooplankton biomass remains more or less invariant, despite seasonally varying primary production regimes, could be explained...

  11. 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.

    Shell weights of planktonic foraminifera species Globigerinoides ruber in the size range of 300–355 mew m were measured from sediment traps in the western and eastern Arabian Sea which represent upwelling and non-upwelling conditions respectively...

  12. Clay minerals as palaeomonsoon proxies: Evaluation and relevance to the late Quaternary records from SE Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.

    as palaeoclimatic proxies are evaluated and discussed. Systematic investigations using several sediment cores from the SE Arabian Sea reveal that despite the influence of several complicating factors, variations in clay mineral composition during the late Quaternary...

  13. 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...

  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. 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...

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

    Directory of Open Access Journals (Sweden)

    Hui Zhao

    2008-08-01

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

  17. 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.

  18. 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.

  19. 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 .

  20. Distribution of mesopelagic micronekton in the Arabian Sea during the winter monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Karuppasamy, P.K.; Muraleedharan, K.R.; DineshKumar, P.K.; Nair, M.

    of the most widespread behaviour in the mesopelagic zone which influences the life history of nonmigrating and migrating fishes5. Thus, the migrating animals influence the feeding behaviour and spatial distribution patterns of the predators6. In the mid..., University of California, Davis, California 9, (1993),pp 105. 42 JGOFS, Joint Global Ocean Flux Study: Report of the Indian Ocean synthesis group on the Arabian Sea process study, JGFS Report No.35 (2002). 43 Gjosæter J, Abundance and production...

  1. 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.

    matter hydrolysis. As Strom (2008) suggested, knowledge of bacterial community composition and their spatial and temporal variation is important for understanding their role in marine biogeochemistry. Intermediate layers in some of the most productive... occurring within the OMZ, phylogenetic and metabolic diversity of the microorganisms inhabiting therein are poorly known (Riemann et al 1999; Fuchs et al 2005, Stevens and Ulloa, 2008). The Arabian Sea is an intensely dynamic region modulated seasonally...

  2. Trace metal concentrations in zooplankton from the eastern Arabian Sea and western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Rejomon, G.; Balachandran, K.K.; Nair, M.; Joseph, T.; DineshKumar, P.K.; Achuthankutty, C.T.; Nair, K.K.C.; Pillai, N.G.K.

    : [Petrisor, Ioana] At: 06:22 9 April 2008 Environmental Forensics, 9:22–32, 2008 Copyright C© Taylor & Francis Group, LLC ISSN: 1527–5922 print / 1527–5930 online DOI: 10.1080/15275920701506193 Trace Metal Concentrations in Zooplankton from the Eastern... to the bioavailability of this metal in the seawater. Keywords: Arabian Sea, Bay of Bengal, zooplankton, trace metals, bioaccumulation Introduction Trace metals in aquatic systems are distributed over different compartments, such as the dissolved state, colloidal state...

  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. 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.

  5. 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.

    phytoplankton productivity, and nitro- gen does not appear to be a factor limiting phytoplankton growth. Vertical mixing, however, also affects grazing by diluting micro-grazers along with phytoplankton. It is argued that mixed layer deepening acts as a natural... (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...

  6. Hydrometeorological Modeling Study of Tropical Cyclone Phet in the Arabian Sea in 2010

    OpenAIRE

    Hesham Badry; Mohammed Haggag

    2012-01-01

    Tropical cyclone Phet is the second strongest tropical cyclone ever recorded in the Arabian Sea. Phet made landfall in the northeast mountainous area of Oman in early morning on 4 June in 2010, causing a breaking record rainfall in this arid region of 488 mm/48 h. The cyclone heavy rainfall triggered flash floods causing enormous losses in lives and infrastructure in northeast Oman. The state of the art Advanced Research WRF model is used to study the atmospheric circulation and to reproduce ...

  7. Waves in the nearshore waters of northern Arabian Sea during the summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Singh, J.; Pednekar, P.S.; Gowthaman, R.

    comparative performance survey of methods used for estimating directional wave spectra from heave-pitch-roll data. Proceedings Coastal Engineering Conference, pp. 62-75. Besnard, J.C., Benoit, M., 1994. Representative directional wave parameters - Review...: Ocean Eng., vol.38(2-3); 2011; 382-388 Waves in the nearshore waters of northern Arabian Sea during the summer monsoon V. Sanil Kumar*, Jai Singh, P. Pednekar and R. Gowthaman Ocean Engineering, National Institute of Oceanography (Council...

  8. 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.

  9. 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.

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

    Science.gov (United States)

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

    2016-01-01

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

  11. 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.

  12. 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.

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

    Science.gov (United States)

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

    2013-12-01

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

  14. 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.

  15. 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...

  16. 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.

    the strongest observed in the world oceans and often sustains temperature inversions when the surface is cooled [Shetye et al., 1996]. Such a strati cation has two implications. First, it leads to thinner mixed layers there. Second, sea level fails to be a good.... is re ected in the underlying ocean, with mixed layers being thinner, and surface temperatures higher, in the bay. That spatial and temporal asymmetries associated with the monsoon determine the sea-level di erence be- tween the Bay-of-Bengal and Arabian...

  17. 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.

  18. Spectral wave climatology off Ratnagiri, northeast Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, M.A.; SanilKumar, V.

    and Methodology 2.1 Data Time series of wave spectral energy estimated from the measured translational motions of a Datawell directional wave rider buoy moored at 13 m water depth off Ratnagiri from 23 March 2010 to 6 November 2014 is used in the study (Fig. 1... complete description of the sea surface having waves with different frequencies and directions (Ochi 2005). The spectral representation of the sea-states is an important input for estimation of i) the response of floating bodies to the wave motion and ii...

  19. Variations in the inorganic carbon components in the thermal fronts during winter in the Northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.; Delabehra, H.B.; Sudharani, P.; Remya, R.; Patil, J.S.; Desai, D.V.

    In order to examine the variations in inorganic carbon components in the thermal fronts, seven fronts have been sampled in the northeastern Arabian Sea during winter. The sea surface temperature (SST) was cooler by 0.2 to 1.03 °C within the fronts...

  20. Seasonal variability of mixed layer in the central Arabian Sea and its implication on nutrients and primary productivity

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Narvekar, J.

    The upper layers of the ocean play an important role in the regulation of the ocean-atmosphere as a coupled system. The Arabian Sea, situated in the western part of the northern Indian Ocean, participates in the intense air-sea exchange processes...

  1. 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.

    , as discussed below, P from terrigenous material is also traceable on slope and deep-sea sediments. The productivity in the Arabian Sea is high during summer and winter monsoon/convection (Bhattathiri et al., 1996; Madhupratap et al., 1996). The fish catch...

  2. 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

  3. 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.

    the monsoonal and post-monsoonal months, but are generally not accounted for in the standard forc- ing strategy of numerical models, curb to some extent the salty bias of the SEAS simulations. The problem of simulating the arrival of low-salinity water...

  4. 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.

  5. 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.

  6. 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...

  7. 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

  8. 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

  9. 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.

    blocks are indicated by solid black. Magnetized layer (susceptibility 0.01 cgs units) is flat 2.0 km thick with its top at 5.5 km below sea surface. Other details are as in Fig. 2. 110 A.K. Chaubey et al. JMarine Geology 128 (1995) 105-l 14 N- MODEL... drill hole results. This age and crustal depth compatibil- ity, we believe, further strengthens the validity of the updated magnetic anomaly identifications proposed by us in this study. The identification presented in this study as well...

  10. Isotopic evidences of past upwelling intensity in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.

    : divakar@csnio.ren.nic.in (P.D. Naidu). intensity in the Sea Naidu * Paula 403 004, Goa, India 2003 www.elsevier.com/locate/gloplacha (2004) 285–293 the important role played by the upwelling zones on the ocean carbon cycle, it is important to identify... flux (Fig. 2a,b).Furthermore,G. bulloides flux and Dd 18 O obl-bul show significant in- verse ranking correlation coefficient (r=C00.56) (pV0.1). 5.2. Dd 13 C sac-dut G.bulloides d 13 Cvaluesarestronglyeffectedbythe vital effects (Naidu and Niitsuma...

  11. 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.

    collected using MOCNESS tows (see Wishner et al., 1998; and Smith et al., 1998, for processing and calibration details). An oxygen sensor (Seabird SBE 13) was included among the suite of instruments on the deep MOCNESS. Backscatter intensity data from... of the oxygen de"cit zone and its position in the water column relative to the sea surface. The 4.5 lM ‘suboxica boundary (delineated in Fig. 3 by bars) is an important biological boundary where oxygen apparently becomes physiologically limiting to many bacteria...

  12. Late quaternary variations in sedimentation rate in the Laccadive trough, southeast Arabian Sea

    International Nuclear Information System (INIS)

    Radiocarbon measurements of a core from the Laccadive trough, south east Arabian Sea have yielded ages which show that sediments from the Pleistocene, Holocene and a transition zone can be recognized by virtue of colour variation. The mean sedimentation rate decreases from 4.11 to 3.15 cm/103yr for Pleistocene and Holocene respectively, with a peak of 6.36cm/103yr determined for the transitional zone. A sediment slump or turbidite emplacement resulting from higher terrigenous influx during the transition period has been inferred. This is in contrast to the bioclastic turbidite of the central continental margin-pelagic region (off Bombay-Ratnagiri sector of western India). The decrease in sedimentation rate from Pleistocene to Holocene can be most likely ascribed to entrapment of riverine sediments in estuaries and continental shelf, as a result of Holocene sea level rise. The mean sedimentation rate in the Laccadive Trough (3.84 cm/103 yr) is lower than that on the northwestern continental margin of India (4.6-9.8 cm/103 yr) because of relatively low terrigenous influx from the small west-flowing rivers of Peninsular India. The Holocene sediment thickness in the Laccadive trough is 35 cm as against 50 cm in the northeastern Arabian Sea. The onset of environmental conditions representative of Holocene is estimated at ca. 9300 yr B.P. which corroborates the date proposed for the northern Indian Ocean. (author). 24 refs., 2 figs., 1 tab

  13. 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

    . Tel.: +91-832-2456700; Fax: +91-832-2456702. E-mail address: pattan@csnio.ren.nic.in (J.N. Pattan). PALAEO 3052 27-3-03 Palaeogeography, Palaeoclimatology, Palaeoecology 193 (2003) 575^590 www.elsevier.com/locate/palaeo column and upwelling promotes... carbonate content and in£uence of Indus discharge in two eastern Arabian sea cores. Palaeogeogr. Palaeoclimatol. Palaeoecol. 86, 255^263. Naidu, P.D., Malmgreen, B.A., 1995. Monsoon upwelling ef- fects on test size of some planktonic foraminiferal species...

  14. Post-tsunami oceanographic conditions in southern Arabian Sea and Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    AnilKumar, N.; Sarma, Y.V.B.; Babu, K.N.; Sudhakar, M.; Pandey, P.C.

    COMMUNICATIONS CURRENT SCIENCE, VOL. 90, NO. 3, 10 FEBRUARY 2006 421 *For correspondence. (e - mail: anil@ncaor.org) Post - tsunami oceanographic cond i tions in southern Arabian Sea and Bay of Be n gal N. Anilkumar 1, *, Y. V. B. Sarma 2 , K. N... the southwest transect. A well - deve l oped warm layer of > 28.5 ?C in the upper 100 m is seen north of 9 ?N. A rel a tively RESEARCH COMMUNICATIONS CURRENT SCIENCE, VOL. 90, NO. 3, 10 FEBRUARY 2006 423 Figure 3. Distribution of ( a ) mixed...

  15. 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.

    0;:/ COCHIIII · 10 4l~~, ·9 f"" Go CAPE OMORIIli I; ~~L ~ r 20~ fl . 7 D 6 76 . 7 19 eo·1a . II III Figure 2. A. Distribution of Globigerinoides sacculi/er (%). B. Distribution of G. ruber (%). C. Distribution of Globigerinelfa aequilareralis (%). D... species G. ruber N. dutertrei G. sacculi/er, G. hul/oides and G. men ardii. This suggests that the planktonic foraminiferal assemblage is of typical tropical Arabian Sea assemblage. Significantly high percentage of Neog/oboquadrina duterlrei (10...

  16. 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)

  17. 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.

    , at intervals of 12.5-13 days, from May 1986 to November 1987. Amino acids and hexosamines are typically labile components that are preferentially degraded during descent of particulate organic matter in the water column (Lee and Cronin, 1984; Ittekkot et al... be used to trace decompositional pathways and intensities (e.g. Lee, 1988). STUDY AREA Monsoons determine the climatic and hydrographic conditions of the Arabian Sea. Winds blowing from the SW in summer (rainy season) and from the NE in winter (dry...

  18. 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.

    waters into a region of high biological productivity. The open ocean upwelling [Bauer et al., 1991; Brock et al., 1991], wind-driven mixing [McCreary et al., 1996; Lee et al., 2000] and lateral advection [Young and Kindle, 1994; Prasanna Kumar et al... entrainment, as it happens in the Arabian Sea [Lee et al., 2000]. The fact that the upper 30m layer of the water column is nutrient-depleted and very low in PP suggests that wind-driven mixing may not be a dominant mechanism. The reason appears...

  19. Arsenic levels in ten species of fish from the east coat of the Arabian Sea, Pakistan

    International Nuclear Information System (INIS)

    Arsenic concentrations are estimated in ten marine fish species from the East Coast of the Arabian Sea, Pakistan, by the atomic absorption method. The following species are included in the study: Picnic seabream, Indian scad, Indian ariomma; Bigeye scad, Threadfins Cornet fish; Lefteye flounder, Goldband goatfish, Smooth dwarf monoclebream and half mourning coraker. A total of 716 fish samples within a preselected narrow weight range and comprising of 5-7 specimens of each species are analysed. Of all the species investigated the maximum concentration (17.602) micro g/g dry weight was found in goldband goatfish. (author)

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

    Digital Repository Service at National Institute of Oceanography (India)

    Roy, R.; Chitari, R.; Kulkarni, V.; Krishna, M.S.; Sarma, V.V.S.S.; Anil, A.C.

    and filaments) have chemical and biological manifestations (Brink et al., 1998; Belkin et al., 2009; Read et al., 2000) and are thought to be hotspots for phytoplankton blooms (Hesse et al., 1989, Franks et al., 1992). The Indian National Centre for Ocean... composition: Significance of the Arabian Sea. Current Sci. 78, 289-299. 14    Nayak, S., Solanki, HU., Dwivedi, R M., 2003. Utilization of IRS P4 ocean colour data for potential fishing zone-A cost benefit analysis. Indian. J. Mar. Sci. 32, 244-248. Olson...

  1. 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.

    of JGOFS (matter retained on <0.45-μm Opti pure fiber filter paper; [UNESCO 1994]). To strengthen the field observations we used the Indian Remote Sensing Ocean color monitor (IRS-P4 OCM) data for path-09 row-13 (spectral channel central wavelength....1016/0278-4343(95)00015-S. Chauhan, P., M. Mohan, R. K. Sarangi, B. Kumari, S. R. Nayak, and S. G. P. Matondkar (2002), Surface chlorophyll estimation in the Arabian Sea using IRS-P4 OCM Ocean Color Monitor (OCM) satellite data, Int J. Remote Sens., 23(8),1663–1676, doi...

  2. 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.

    agricultural field draining to Kochi backwater) alone is reported to be 20,240 t year-1 (Anonymous 1998). Naqvi et al. (2006) also reported a riv- erine flux (0.1 Tg N year-1) of dissolved inorganic nitrogen to the Arabian Sea. Earlier hydrographic studies... and phosphate inputs of 37.6 9 103 and 42.4 9 103 mol day-1 from the major rivers draining through the agricultural fields, with an export of nitrate and phosphate to the coastal waters off Kochi of 24.0 9 103 and 28.2 9 103 mol day-1, respectively (Naik 2000...

  3. ASYMMETRY ANALYSIS STUDY ON Callionymus margaretae REGAN, 1906 COLLECTED FROM THE ARABIAN SEA COASTS OF OMAN

    Directory of Open Access Journals (Sweden)

    J.M. Al-Mamry

    2011-03-01

    Full Text Available Asymmetry analyses have been carried out for some bilateral characters of Callionymus margaretae Regan, 1906 collected from the Arabian Sea coasts of Oman. The results showed that the level of asymmetry of the character postorbital length was the highest among those asymmetry values obtained for the remaining characters studied. The lowest value was that for the head length. An increasing trend in the asymmetry value with fish length is also obtained for preorbital and postorbital lengths. The possible cause of the asymmetry in this species is herein discussed in relation to different pollutants and their presence in the area.

  4. 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.

    –527. Agnihotri R, Siby K, Fernandes M, Reshma K, D’Souza W and Naqvi SWA (2008) Variability of subsurface denitrification and surface productivity in the coastal eastern Arabian Sea over the past seven centuries. Holocene 18(5): 755–764. Altabet MA, Murray DW... and Prell WL (1999) Climatically linked oscillations in Arabian Sea denitrification over the past lm.y. : Implications for the marine N cycle. Paleoceanography 14(6): 732-743. Altabet MA, Francois R, Murray DW and Prell WL (1995) Climate...

  5. Glacial to interglacial contrast in the calcium carbonate content and influence of Indus discharge in two eastern Arabian sea cores

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.

    -Murray Ridge on the west, and the Mid-Indian Ridge (Carlsberg Ridge) on the south. The Indus River, which drains through the Himalayas and the arid regions of Pakistan and India has transported 406 million metric tonnes of suspended sediments annually..., until recent dam constructions and has been the major fluvial source of the Arabian Sea (Kolla et al., 1981). Inspite of high rainfall, only small rivers and streams drains into the Arabian Sea from the western India. Of these Narmada and Tapti...

  6. 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.

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

    Digital Repository Service at National Institute of Oceanography (India)

    Boll, A.; Luckge, A.; Munz, P.; Forke, S.; Schulz, H.; Ramaswamy, V.; Rixen, T.; Gaye, B.; Emeis, K.-C.

    with mixed layer depth and wind suggesting a primarily physical control on carbon fixation in this part of the Arabian Sea [Prasanna Kumar et al., 2001]. In winter a reduction in solar insolation and dry continental air brought by prevailing north... et al., 2009]. A recently published global data set of proxy records indeed confirms a global cooling trend between 1580 and 1880 A.D. [PAGES 2k Consortium, 2013] that is preceded by a phase of low solar irradiance between 1450 to 1750 A.D. [Bard...

  8. 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

  9. The effect of millennial-scale changes in Arabian Sea denitrification on atmospheric CO2

    International Nuclear Information System (INIS)

    Most global biogeochemical processes are known to respond to climate change, some of which have the capacity to produce feedbacks through the regulation of atmospheric greenhouse gases. Marine denitrification - the reduction of nitrate to gaseous nitrogen - is an important process in this regard, affecting greenhouse gas concentrations directly through the incidental production of nitrous oxide, and indirectly through modification of the marine nitrogen inventory and hence the biological pump for C02. Although denitrification has been shown to vary with glacial-interglacial cycles, its response to more rapid climate change has not yet been well characterized. Here we present nitrogen isotope ratio, nitrogen content and chlorin abundance data from sediment cores with high accumulation rates on the Oman continental margin that reveal substantial millennial-scale variability in Arabian Sea denitrification and productivity during the last glacial period. The detailed correspondence of these changes with Dansgaard-Oeschger events recorded in Greenland ice cores indicates rapid, century-scale reorganization of the Arabian Sea ecosystem in response to climate excursions, mediated through the intensity of summer monsoonal upwelling. Considering the several-thousand-year residence time of fixed nitrogen in the ocean, the response of global marine productivity to changes in denitrification would have occurred at lower frequency and appears to be related to climatic and atmospheric C02 oscillations observed in Antarctic ice cores between 20 and A kyr ago. (author)

  10. 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 (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.

  11. 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...

  12. 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 (days) of organic carbon, nitrogen and nutritional demands of foraminifera at different oxygen concentrations on the continental margin in the eastern Arabian Sea. For the experiments, a single pulse of isotopically labeled phytodetritus was added to the sediment along a depth transect (540-1100 m) on the Indian Margin, covering the OMZ core and the lower OMZ boundary region. Uptake of phytodetritus within 4 days shows the relevance of phytodetritus as food source for foraminifera. Lower content of phytodetrital carbon recorded in foraminifera from more oxygenated depths shows greater food uptake by foraminifera in the OMZ core than in the OMZ boundary region. The foraminiferal assemblage living under almost anoxic conditions in the OMZ core is dominated by species typically found in eutroph environments (such as Uvigerinids) that are adapted to high flux of organic matter. The elevated carbon uptake can also result from missing food competition by macrofauna or from greater energy demand in foraminifera to sustain metabolic processes under hypoxic stress. Variable levels and ratios of phytodetrital carbon and nitrogen indicate specific nutritional demands and storage of food-derived nitrogen in some foraminifera species under near anoxia where the mean phytodetrital nitrogen content in

  13. 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

  14. 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

  15. 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.

  16. 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...

  17. 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.

    off. The hydrological imbalance thus created on an annual scale will have to be balanced by the inter-basin exchange. In winter this happens through the intrusion of Bay of Bengal waters into the Arabian Sea, when the southward flowing East India...

  18. 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.

    - dance (Caratini et al., 1994) and benthic forami- nifera proxy records (Nigam, 1993) in the Arabian Sea and N 13 C of peats from south India (Sukumaretal.,1993)con¢rmthataround3.5ka the river discharge decreased drastically, which implies that monsoon...

  19. Wave hindcast studies using SWAN nested in WAVEWATCH III - comparison with measured nearshore buoy data off Karwar, eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Amrutha, M.M.; SanilKumar, V.; Sandhya, K.G.; Nair, T.M.B.; Rathod, J.L.

    Waves in the nearshore waters (~15 m water-depth) of eastern Arabian Sea were simulated using SWAN nested in WAVEWATCH III (WW3) for the year 2014. The sensitivity of the numerical wave model WW3 towards different source term (ST) packages...

  20. 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...

  1. 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.

  2. 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.

  3. Biodiversity of Deep Sea Prawns in the Upper Continental Slope of Arabian Sea, off Kerala (south west India): A Comparison Between Depths and Years

    OpenAIRE

    R., Radhika Rajasree S.

    2011-01-01

    Univariate diversity indices and multivariate cluster analysis were performed in order to evaluate the year wise and depth wise bio diversity of deep sea prawns between 150-650m in the upper continental slope of Arabian Sea, off Kerala, South India. Data were collected from both exploratory surveys as well as commercial deep sea -to fishery off Kerala coast between latitudes 7to 13oN. Biodiversity and species assemblage are discussed considering the different environmental characters as well ...

  4. Air-sea exchange of CO2 in the Gulf of Kutch, northern Arabian Sea based on bomb-carbon in corals and tree rings

    International Nuclear Information System (INIS)

    Radiocarbon analyses were carried out in the annual bands of a 40 year old coral collected from the Gulf of Kutch (22.6degN, 70degE) in the northern Arabian Sea and in the annual rings of a teak tree from Thane (19deg14'N, 73deg24'E) near Bombay. These measurements were made in order to obtain the rates of air-sea exchange of CO2 and the advective mixing of water in the Gulf of Kutch. The Δ 14C peak in the Thane tree occurs in the year 1964, with a value of ∼630 part per thousand, significantly lower than that of the mean atmospheric Δ14C of the northern hemisphere (∼1000 part per thousand). The radiocarbon time series of the coral was modelled considering the supply of carbon and radiocarbon to the gulf through air-sea exchange and advective water transport from the open Arabian Sea. A reasonable fit for the coral data was obtained with an air-sea CO2 exchange rate of 11-12 mol m-2yr-1, and an advective velocity of 28 m yr-1 between the Arabian Sea and the Gulf of Kutch; this was based on a model generated time series for radiocarbon in the Arabian Sea. The deduced velocity (∼ 28 m yr-1) of the advective transport of water between the Gulf and the Arabian Sea is much lower than the surface tidal current velocity in this region, but can be understood in terms of net fluxes of carbon and radiocarbon to the gulf to match the observed coral Δ14C time series. (author). 30 refs., 7 figs., 2 tabs

  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. Arabian Sea GEOSECS stations revisited: Tracer-depth profiles reveal temporal variations?

    International Nuclear Information System (INIS)

    In March-April 1998, the Physical Research Laboratory and the Regional Research Laboratory (Ahmedabad, India) together with the IAEA Marine Environment Laboratory, Monaco, participated in the research mission to visit GEOSECS (Geochemical Ocean Sections Study) stations in the Arabian Sea. The main objective was to reoccupy these stations which were sampled in the early seventies to observe possible time variations in trace behaviour in this region. It is generally accepted that both natural (climate variations) and anthropogenic (greenhouse effect) changes can cause modifications of the oceanic characteristics and properties of deep waters on yearly and decadal scales. For long time-scales (100 to 1000 years) one needs to look at the sediments where these changes are subtly recorded. Tracers such as 14C and 3H (deep waters) and 228Ra surface waters are useful markers of water circulation patterns and changes. Also man-made radiotracers such as 90Sr, 137Cs, 99Tc, 238Pu, 239,240Pu and 241Am, can give information on air-sea exchange as well as penetration (vertical change) rates in the open ocean [2]. We visited GEOSECS stations 415 to 419. In each station, CTD profiles, 3H, 14C, 90Sr, 137Cs, Pu and Am profiles, nutrients, Be, TOC and oxygen were determined from surface to bottom. Also uranium and trace elements were sampled in function of the oxygen minimum zone. In this paper we report the findings on the physical properties as well as the variations in water circulation patterns and also vertical exchange rates in the Arabian Sea. PSU profiles collected in this mission compared with those PSU profiles measured in 1974 (GEOSECS) showed marked differences in those stations located in the southeast part of the Arabian Sea. In contrast, those located more towards the north (415-416) showed little temporal variation. We think these changes may be real given that the PSU values at depth are comparable and reflect the presence of deep Antarctic bottom waters in this

  8. 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.

  9. 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.

  10. 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)

  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. Spatio-temporal variations of nitrogen isotopic records in the Arabian Sea

    Directory of Open Access Journals (Sweden)

    S.-J. Kao

    2014-06-01

    Full Text Available Nitrogen and carbon contents vs. their isotopic compositions for past 35 ka for a sediment core (SK177/11 collected from the most southeastern part of the Arabian Sea (AS were presented. A one-step increase in δ15Nbulk starting at the deglaciation with a corresponding decrease in δ13CTOC was found similar to documentation elsewhere which showed a global coherence in general. We synthesized available reports including dissolved oxygen, δ15N of nitrate (δ15NNO3, as well as δ15N of total nitrogen (δ15Nbulk for trap material and surface/downcore sediments in the AS in order to explore the past nitrogen dynamics in the Arabian Sea. According to 25 μmol kg−1 dissolved oxygen isopleth at 150 m deep, we classified all reported data into northern and southern groups. We obtained geographically distinctive bottom-depth effects for northern and southern AS at different climate stages. By eliminating the bias caused by bottom depth, the modern day sedimentary δ15Nbulk values largely reflect the δ15NNO3 supply from the bottom of the euphotic zone; meanwhile, the diffusive sedimentary δ15Nbulk in long cores became confined revealing a more consistent pattern except recent 6 ka. The nitrogen cycle in entire AS apparently responded to open-ocean changes until 6 ka, during which further enhanced denitrification in the northern AS was likely local and driven by monsoon; while in the southern AS either nitrogen fixation was enhanced correspondingly to the continuously reduced δ15Nbulk for a compensation or the decreasing trend just followed the global pattern dominated by a longer term coupling of N2 fixation and denitrification.

  14. Large organic-walled Protista ( Gromia) in the Arabian Sea: Density, diversity, distribution and ecology

    Science.gov (United States)

    Aranda da Silva, A.; Gooday, A. J.

    2009-03-01

    The genus Gromia includes large marine protists ('gromiids') with filose pseudopodia and sack-like organic tests. The first deep-water species were discovered in the 1990s on the Oman Margin of the Arabian Sea and subsequently found on the Pakistan Margin. We present a survey of gromiids in samples collected off Oman in 2002 and off Pakistan in 2003. In addition to the two species ( Gromia sphaerica and Gromia pyriformis) already described from this area, at least eight undescribed gromiid species were present. Sausage shaped, grape shaped and spherical morphotypes were represented among this material. On the Oman Margin, gromiids occurred in densities up to several thousand individuals m -2 at 1400 and 1700 m but were much less common at 1100 and 2000 m. Apart from G. pyriformis, which was fairly common (several hundred individuals m -2) at 1000 m, gromiids were uncommon in core samples taken off Pakistan, with 11 indiv. m -2 at 1200 m and 19 indiv. m -2 at 1850 m. On both margins, these protists occurred at depths >1000 m where bottom-water oxygen concentrations exceeded ˜0.2 ml l -1 (=8.92 μM l -1) land sediments were fully bioturbated and oxidised. However, they were not observed at similar oxygen levels above the OMZ. Most gromiids lived on the sediment surface with their apertures facing down and their pseudopodia presumably deployed into the sediment to feed on surficial material and associated bacteria. We conclude that these large protists may play an important ecological role in the bathyal Arabian Sea, particularly in carbon cycling but also in structuring the surficial sediments. In addition, their tests, particularly those of G. sphaerica, provide substrates for attached Foraminifera.

  15. Palynological record of tropical rain forest vegetation and sea level fluctuations since 140 ka from sediment core, south-eastern Arabian sea.

    Digital Repository Service at National Institute of Oceanography (India)

    Farooqui, A.; Pattan, J.N.; Parthiban, G.; Srivastava, J.; Ranjana

    Palyno-chronological study of a 552 cm deep sediment core from the south-eastern Arabian Sea covers a time span of ~ 140 ka. The age estimate is based on oxygen isotopic data of planktic foraminifera. Six zones were identified on the basis...

  16. Seasonality in sub-surface chlorophyll maxima in the Arabian Sea: Detection by IRS-P4/OCM and implication of it to primary productivity

    Digital Repository Service at National Institute of Oceanography (India)

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

    Arabian Sea is highly influenced by monsoon systems like SW monsoon (June – September) and NE monsoon (December-February). This affects distribution pattern of phytoplankton, availability of nutrients and changing temperature specially during winter...

  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. 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.

  20. 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.

  1. 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.

  2. 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.

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

    Science.gov (United States)

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

    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.

  4. 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.

  5. 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.

  6. 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.

    is a potent greenhouse gas that is also in- volved in the destruction of the ozone layer (Crutzen 1979, Lashof & Ahuja 1990, Waibel et al. 1999). Water column denitrification in the Arabian Sea occurs in 2 geographically distinct locations, one within... takes place along the entire shelf of the southwest coast of India, inject- ing nitrate-rich waters into the photic layers. The intense productivity that ensues leads to O 2 depletion and then to denitrifying conditions in the subsurface shelf waters...

  7. 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.

    is derived from magnitude of particulate matter influx in three trap moorings at the central, the eastern and the western region of the Arabian Sea (Nair et al. 1989; Haake et al. 1993; 1996; Rixen et al. 2009). Prevalence of intense rainfall, augmented... al. 1999). Over the northern Indian Ocean, there are two dominant points of fluvial discharge fed by orographically augmented precipitation. The first one lies at the northern boundary of the Bay of Bengal, while the SW continental margin of India...

  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. 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.

  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. 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; Bratenkov, S.; Griffith, E.M.; Gurumurthy, G.P.; Hahn, A; Iwai, M.; Khim, B.-K.; Kumar, A; Kumar, A; 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; Steinke, S.; Suzuki, K.; Tauxe, L.; Tiwari, M.; Xu, Z.; Yu, Z.

    Sea, offers a unique opportunity to investigate tectonic–climatic interactions and the net impact of these processes on weathering and erosion of the western Himalaya. During International Ocean Discovery Program Expedition 355, two sites (U1456 and U...

  13. 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,...

  14. 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...

  15. 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.

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

    Science.gov (United States)

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

    2016-01-01

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

  17. 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

  18. 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,...

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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)

  5. A study of meteorologically and seismically induced water level and water temperature oscillations in an estuary located on the west coast of India (Arabian Sea)

    OpenAIRE

    P. Mehra; R. G. Prabhudesai; Joseph, A.; Kumar, V; Y. Agarvadekar; R. Luis; Viegas, B.

    2012-01-01

    The study examines the observed storm-generated sea-level oscillations (June 2007 and November 2009) along with the Sumatra geophysical tsunami (September 2007), indicating similarities in the sea-level response in the Mandovi estuary of Goa in the eastern Arabian Sea. Sea-level and surface meteorological measurements collected during storms exhibit strong synoptic disturbances leading to the coherent oscillations in the estuary with significant energy bands centred at periods of 24, 45, and ...

  6. A study of meteorologically and seismically induced water level and water temperature oscillations in an estuary located on the west coast of India (Arabian Sea)

    OpenAIRE

    P. Mehra; R. G. Prabhudesai; Joseph, A.; Kumar, V; Y. Agarvadekar; R. Luis; Viegas, B.

    2012-01-01

    The study examines the observed storm-generated sea-level oscillations (June 2007 and November 2009) along with the Sumatra geophysical tsunami (September 2007), indicating similarities in the sea-level response in the Mandovi estuary of Goa in the eastern Arabian Sea. Sea-level and surface meteorological measurements collected during storms exhibit strong synoptic disturbances leading to the coherent oscillations in the estuary with significant energy bands centred at perio...

  7. 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.

    . This faunal affinity suggests that changes in near-surface water temperatures during the last glacial period did not induce major alterations in the fauna and the fact that sea surface temperatures were slightly warmer in the Arabian Sea during Last Glacial...

  8. Stable isotopic variations in foraminiferal test from Arabian Sea and its relation to the annual south-west monsoonal rainfall over the Indian subcontinent

    Digital Repository Service at National Institute of Oceanography (India)

    Borole, D.V.

    degrees 45'E) shows very little variation during May to October 1987 - the period of intense southwest monsoon activity over the north Indian Ocean and the adjoining land mass. This implies that the sea surface temperature in this part of the Arabian Sea...

  9. 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.

    accounts for changes in the characteristics of PGW along these paths. Associated with the Findlater Jet during summer, the entire thermohaline structure is vertically displaced along the coasts of Somalia and Arabia. Ekman convergence in the central Arabian...

  10. 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

  11. 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 ...

  12. 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 ...

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

    Science.gov (United States)

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

    2010-12-01

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

  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. Characteristics of monsoon inversions over the Arabian Sea observed by satellite sounder and reanalysis data sets

    Science.gov (United States)

    Dwivedi, Sanjeev; Narayanan, M. S.; Venkat Ratnam, M.; Narayana Rao, D.

    2016-04-01

    Monsoon inversion (MI) over the Arabian Sea (AS) is one of the important characteristics associated with the monsoon activity over Indian region during summer monsoon season. In the present study, we have used 5 years (2009-2013) of temperature and water vapour measurement data obtained from satellite sounder instrument, an Infrared Atmospheric Sounding Interferometer (IASI) onboard MetOp satellite, in addition to ERA-Interim data, to study their characteristics. The lower atmospheric data over the AS have been examined first to identify the areas where MIs are predominant and occur with higher strength. Based on this information, a detailed study has been made to investigate their characteristics separately in the eastern AS (EAS) and western AS (WAS) to examine their contrasting features. The initiation and dissipation times of MIs, their percentage occurrence, strength, etc., has been examined using the huge database. The relation with monsoon activity (rainfall) over Indian region during normal and poor monsoon years is also studied. WAS ΔT values are ˜ 2 K less than those over the EAS, ΔT being the temperature difference between 950 and 850 hPa. A much larger contrast between the WAS and EAS in ΔT is noticed in ERA-Interim data set vis-à-vis those observed by satellites. The possibility of detecting MI from another parameter, refractivity N, obtained directly from another satellite constellation of GPS Radio Occultation (RO) (COSMIC), has also been examined. MI detected from IASI and Atmospheric Infrared Sounder (AIRS) onboard the NOAA satellite have been compared to see how far the two data sets can be combined to study the MI characteristics. We suggest MI could also be included as one of the semipermanent features of southwest monsoon along with the presently accepted six parameters.

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-25

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

  18. 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.

    stream_size 33831 stream_content_type text/plain stream_name Polish_J_Microbiol_62_391a.pdf.txt stream_source_info Polish_J_Microbiol_62_391a.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 1... 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...

  19. 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.

    the residual NO 3 – enriched with 15 N (Liu and Kaplan, 1989; Brandes et al., 1998; Altabet et al., 1999; Voss et al., 2001). As the isotopically heavier NO 3 – is brought up to the surface through upwelling and vertical entrainment through mixing... – in the seawater is on an average ~5‰ (Altabet, 2006), but in the perennial suboxic zone of the central Arabian Sea (~150-600 m; Naqvi, 1987), denitrification results in δ 15 N values as high as 15-18‰ (Brandes et al., 1998; Altabet et al., 1999). As most...

  20. 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

  1. 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.

  2. Retrieval of near-surface bio-optical properties of the Arabian Sea from remotely sensed ocean colour data

    Science.gov (United States)

    Pinkerton, M. H.; Trees, C. C.; Aiken, J.; Bale, A. J.; Moore, G. F.; Barlow, R. G.; Cummings, D. G.

    1999-03-01

    The use of CZCS-type band-ratio algorithms to estimate the diffuse attenuation coefficient, percentage light depths, and near-surface optically weighted phytoplankton pigment concentrations from remotely sensed ocean colour data was investigated on two cruises in the Arabian Sea and Gulf of Oman during autumn and winter 1994. The variations of upwelling radiance and downwelling irradiance with depth were measured along with phytoplankton pigment concentrations by HPLC. A spectroradiometer was used on the second cruise to investigate the feasibility of measuring water-leaving radiance from above the sea surface. Retrieval of the diffuse downwelling attenuation coefficient at 490 nm was accurate to within 22% of the actual value across both cruises. There was also a robust relationship between the diffuse attenuation coefficient and the 10, 1 and 0.1% light depths. Above-surface estimates of water-leaving radiance agreed with SeaWiFS-standard estimates to within 10% between 443 and 555 nm. The global 443 : 555 band-ratio algorithms of Aiken et al. [NASA Tech. Memo 104566, Vol. 29, SeaWiFS Technical Report Series, 34 pp] estimated near-surface chlorophyll- a and fluorometric pigment concentrations with mean absolute errors of less than 35% of the actual values (which were all less than 2.0 mg m -3). The performance of algorithms based on the 490 : 555 ratio was poorer. The estimates given by the algorithms were generally higher than the measured pigment concentrations and the variance of the accuracy of the estimates was high. There appears to be no significant change in the performance of the algorithms between cruises (approximately 2 1/2 months apart in time). There is no evidence that the Gulf of Oman should be treated as a separate bio-optical province to the Arabian Sea/Omani shelf area for the purpose of the retrieval of near-surface pigment concentrations from ocean colour observations.

  3. 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.

  4. 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.

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

    Science.gov (United States)

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

    2014-04-01

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

  6. 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.

  7. 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

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

    Directory of Open Access Journals (Sweden)

    H. de Moel

    2009-09-01

    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

  9. 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.

  10. 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

  11. 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.

  12. 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...

  13. 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.

  14. 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

  15. Monsoon related changes in sea surface productivity and water column denitrification in the Eastern Arabian Sea during the last glacial cycle

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Oba, T.; Chodankar, A.R.; Kuramoto, T.; Yamamoto, M.; Minagawa, M.

    Arabian Sea during the last glacial cycle V.K. Banakar a, * ,T.Oba b , A.R. Chodankar a , T. Kuramoto b , M. Yamamoto b , M. Minagawa b a National Institute of Oceanography, Dona Paula, Goa-403 004, India b Graduate School of Environmental Earth Science... a significant amount of southern Indian Ocean moisture to the northern Indian Ocean as well as to the Indian sub- continent. The increased salinity by ~1.5 psu evident in our results and a broken communication between the EAS and the BOB...

  16. 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.

  17. Spatio-temporal distributions of delta18O, delta D and salinity in the Arabian Sea: Identifying processes and controls

    Digital Repository Service at National Institute of Oceanography (India)

    Deshpande, R.D.; Muraleedharan, P.M.; Singh, R.L.; Kumar, B.; Rao, M.S.; Dave, M.; Sivakumar, K.U.; Gupta, S.K.

    Isotopic compositions ( delta18O and deltaD) and salinity (S) of 683 surface water samples from the Arabian Sea (AS) collected during 2008–2010, were measured to understand the factors controlling the spatio-temporal distribution...

  18. Formation of algal bloom in the northern Arabian Sea deep waters during January-March: A study using pooled in situ and satellite data

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, R.M.; Raman, M.; Babu, K.N.; Singh, S.K.; Vyas, N.K.; Matondkar, S.G.P.

    The formation of winter bloom (January-March) was studied in deep waters of the northeastern Arabian Sea (NAS) during 2003 and 2004. Six ship cruises were undertaken at different phases of the bloom to examine its formation. Along with physical...

  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. 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... it is known 4 that sub - micron particles in suspended sed i ments, phytoplankton and auxiliary pigments, detrital particle fractions and dissolved coloured substances will act to in crease the magnitude of backscatter coefficients b b at 555 nm...

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

    DEFF Research Database (Denmark)

    Stief, Peter; Fuchs-Ocklenburg, Silvia; Kamp, Anja; Manohar, Cathrine Sumathi; Houbraken, Jos; Boekhout, Teun; De Beer, Dirk; Stoeck, Thorsten

    2014-01-01

    Background: A wealth of microbial eukaryotes is adapted to life in oxygen-deficient marine environments. Evidence is accumulating that some of these eukaryotes survive anoxia by employing dissimilatory nitrate reduction, a strategy that otherwise is widespread 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 and nitrous oxide emission. Results: Axenic incubations of An-4 in the presence and absence...... dissimilatory nitrate reduction when oxygen is absent. In the currently spreading oxygen-deficient zones in the ocean, an as yet unexplored diversity of fungi may recycle nitrate to ammonium and nitrite, the substrates of the major nitrogen loss process anaerobic ammonium oxidation, and the potent greenhouse...

  3. 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.

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

    International Nuclear Information System (INIS)

    We have determined the calcium carbonate (CaCO3), organic carbon (Corg), trace element, and rare earth element (REE) composition of surface sediments collected from a transect on the central western continental shelf and slope of India in the Eastern Arabian Sea. The transect samples across the oxygen minimum zone (OMZ) allows us to compare the relative abundances of trace elements and REEs in the sediments beneath and beyond the OMZ. Shale-normalized REE patterns, Lan/Ybn ratios, and Eu/Eu* anamolies indicate that the sediments in the study area are either derived from the adjoining Archaean land masses or from distal Indus source. Sediment deposited in the OMZ have high U values from 3.6 to 8.1 ppm, with their Uexcess (of that can be supplied by continental particles) values ranging between 82-91% of the total U, indicating that the U may be precipitated as U+4 in the reducing conditions of OMZ. Sediments deposited beneath the intense OMZ (shale values are poorly related to U and Corg which are indicators of suboxic bottom waters. Normative calculations suggest that two sources, namely, terrestrial and seawater (terrestrial > seawater) contribute to the total Ce anomaly of the sediments. The Ce anomaly values of the calculated seawater derived component are similar to the anomalies reported for other coastal waters and the oxygenated surface waters of the Arabian Sea and do not show any correspondence to the lowered redox state of the overlying water, probably due to the redirection of dissolved Ce into the oxic deeper water. 103 refs., 6 figs., 3 tabs

  5. 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

  6. 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

  7. 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 (Indus River. In contrast, stadials are characterized by an increased contribution of aeolian dust probably from the Arabian Peninsula. Heinrich events are especially dry and dusty events, indicating a dramatically weakened Indian summer monsoon and increased continental aridity. These results strengthen the evidence that North Atlantic temperature changes and shifts on the hydrological cycle of the Indian monsoon system are closely coupled, and had a massive

  8. Impact of water mass mixing and dust deposition on Nd concentration and εNd of the Arabian Sea water column

    Science.gov (United States)

    Goswami, Vineet; Singh, Sunil K.; Bhushan, Ravi

    2014-11-01

    The concentration and isotopic composition (εNd) of dissolved Nd have been measured in the sub-oxic/denitrifying water column of the eastern Arabian Sea to explore the impact of water mass mixing and release from particles. Dissolved Nd in the north-eastern Arabian Sea is more radiogenic (εNd: -7 to -10) compared to its south-eastern part (εNd: -11 to -15) suggesting contribution of Nd from the Bay of Bengal (BoB). The vertical profile of Nd typically show higher values in surface waters (15.8-27.8 pmol/kg), followed by minima (12-18 pmol/kg) in the subsurface waters (200-300 m) and a gradual increase with depth thereafter. The Nd concentration does not seem to show any changes in the sub-oxic layers suggesting no impact of the sub-oxic/denitrifying conditions in this oceanic region on the biogeochemistry of Nd. The enrichment of Nd in surface waters can be explained either by supply from high Nd low salinity waters from the BoB to the Arabian Sea via the East India Coastal Current (EICC) or, alternatively the Nd surface excess can be result of release from aeolian dust depositing over the sea surface. Inverse modeling computations suggest that in addition to Nd contributed from water mass mixing, some additional excess Nd (Ndxs) is required to balance the Nd inventory in the water column. There is significant Ndxs in the surface waters of the north-eastern Arabian Sea with εNd ∼ -6, similar to that of dust depositing over the Arabian Sea. The fractional solubility of Nd released from the aeolian dust was estimated to be varying from ∼3% to 17% (for excess Nd inventory per unit area (Ndxs∗) of 20 μg m-2 with τNd ranging from 1 to 3 years). This study highlights the significance of aeolian dust deposition in controlling the abundance and distribution of Nd in the Arabian Sea, the western arm of the northern Indian Ocean, lying in the proximity to the arid landmass and characterized by high lithogenic aeolian dust deposition.

  9. 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.

  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 (NODC 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. Controls on organic carbon distribution in sediments from the eastern Arabian Sea margin

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.; Raju, S.V.

    on the continental slope of the eastern Arabian Margin. (L, continental slope cores; d, topo- graphic high cores; m, continental terrace core). A schematic cross section (o⁄ Goa) showing the location of topographic high on the slope is also inserted (transect x...), CaCO 3 , and sand content in the cores from the continental terrace and topo- graphic highs Sediment core from the terrace The OC content is 2.4% at the surface and also at the LGM. It initially decreases with increasing CaCO 3 and sand contents from...

  12. 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,...

  13. 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

  14. 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.

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

    Science.gov (United States)

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

    2015-09-01

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

  16. 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...

  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

    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...

  18. 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...

  19. 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.

    - enclosure morphology of the northern Arabian Sea (Wyrtki 1973; Shetye et al. 1994) are the main factors responsible for this low oxygen concentra- tion. Apart from this OMZ, a shallow water oxygen depleted zone (∼50–60 m) has been reported from different...- thic foraminifera groups, viz., the species under the genus Bolivina, in oxygen-depleted environments have been reported (Phleger and Soutar 1973; Mackensen and Douglas 1989; Bernhard 1993; Sen Gupta and Machain-Castillo 1993; Alve 1994, 1995; Bernhard...

  20. 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.

  1. 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...

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

    Science.gov (United States)

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

    2016-03-01

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

  3. 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

  4. 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

  5. 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

  6. 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.

    by two complementary processes, the arrival of low-salinity surface waters that are cooled en route to the SEAS and downwelling of waters mostly local to the SEAS in the subsurface layers. The surface waters are partly of Bay-of-Bengal origin...

  7. Characteristics of long-period swells measured in the near shore regions of eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Johnson, G.; SanilKumar, V.; Amrutha, M.M.; Singh, J.

    -peaked with peak wave period around 18.2 s, the secondary peak period around 13.3 s and the wind-sea peak period at 5 s. The ratio of the spectral energy of the wind-sea peak and the primary peak (swell) was slightly higher at the northern location (0.2) than...

  8. 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.

    .6°C, and a decrease of ~7°C. This indicates that cold air always advects towards the cyclogenesis area. The atmosphere gains more heat from the sea in the form of sensible heat flux; this heats the air in contact with the sea surface and produces... . The system again moved in the northwesterly direction on 8 th and 9 th of May and then dissipated off Sourashtra into a low pressure system. The weakening over the oceanic area could be attributed to the cold waters present over the northeastern Arabian...

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Addressing environmental issues through foraminifera – Case studies from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    The present global scenario poses multiple environmental problems such as the green house effect, ozone holes, global warming and consequential sea level rise, all being attributed to anthropogenic contributions. Obviously, there is an increased...

  15. 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)...

  16. Dynamics of thraustochytrid protists in the water column of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, S.; Ramaiah, N.; Raghukumar, C.

    Thraustochytrids, a group of osmoheterotrophic chromistan protists are ubiquitous in the sea. However, little is known of their ecological role, particularly in oceanic waters. To obtain in insight into their dynamics in this realm, thraustochytrids...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Saxena, A.

    of information that the mission will be collecting about the Earth's water cycle, including evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover on the land and ice. Additional... every one to two days. The data will be used to derive products ranging from vegetation, land surface cover, and ocean chlorophyll fluorescence to cloud and aerosol properties, fire occurrence, snow cover on the land, and sea ice cover on the oceans...

  18. 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.

    with Chlorophyll values at 1 m depth. Relatively high enrichment factors, sea-surface microlayer (SML), in coastal waters could be attributed to the influence of freshwater carrying considerable quantities of nutrients into the sea either from land runoff or from...

  19. 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.

  20. 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.

  1. Fluorescence-based characterization of phycoerythrin-containing cyanobacterial communities in the Arabian Sea during the Northeast and early Southwest Monsoon (1994 1995)

    Science.gov (United States)

    Michelle Wood, A.; Lipsen, Michael; Coble, Paula

    1999-08-01

    Scanning fluorescence spectroscopy was used to investigate the spatial and temporal variability in the fluorescence signature of phycoerythrin-containing organisms in the Arabian Sea during the early Northeast and early Southwest Monsoon (1994-1995). Phycoerythrin (PE) emission spectra were relatively invariant among all the samples collected on either cruise; the relatively symmetrical PE emission peaks showed maxima at wavelengths ranging from 563-572 nm. PE excitation spectra always showed either a strong shoulder or a peak at wavelengths absorbed maximally by phycourobilin (PUB) chromophores as well as a peak at wavelengths absorbed maximally by phycoerythrobilin (PEB) chromophores. Thus, the Arabian Sea appears to be different from the Black Sea or Gulf of Maine in that PUB-lacking forms of PE rarely, if ever, dominate the PE signal. Fluorescence excitation signatures differed in the relative excitation of PE emission by wavelengths absorbed by PUB (˜495 nm, Ex PUB) and by wavelengths absorbed by PEB (˜550 nm, Ex PEB); these were distinguished by having either very low (˜0.6), very high (˜1.8), or intermediate Ex PUB:Ex PEB ratios. The distribution of samples with different PE fluorescence signatures was investigated extensively during the early Southwest Monsoon, and communities characterized by the low Ex PUB:Ex PEB ratios were closely associated with cooler (24-27°C), fresher (35.7-36.25 psu) water influenced by coastal upwelling. In general, "ambient" surface water of the Arabian Sea during the early Southwest Monsoon was of intermediate temperature (27-29°C) and salinity (36.15-36.4 psu) and showed intermediate or high values for Ex PUB:Ex PEB. This suggests that the PE fluorescence signature can be used to follow the fate of upwelling-influenced water masses and the populations they transport.

  2. 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...

  3. 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.

    (0-200 m) than in the surface (0-10 m) tows. Further, latitudinal gradient of some species which have a definite bearing on hydrography of the sea, has been outlined. Relative production of planktonic foraminifera shows that it is high in the southern...

  4. Corrosion behaviour of metals and alloys in the waters of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

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

    . Corrosion rate of metals and performance evaluation of anti-corrosive paint systems in Yishakhapatnam harbour. Proc.Symp. Protection ofmaterials in the sea. 107-114. 3. C.P.De. 1984. Present state of technology for control of marine corrosion and fouling...

  5. Phycoerythrin-containing picocyanobacteria in the Arabian Sea in February 1995:. diel patterns, spatial variability, and growth rates

    Science.gov (United States)

    Sherry, Nelson D.; Michelle Wood, A.

    The abundance of phycoerythrin-containing picocyanobacteria in the surface mixed layer was measured both along-shore and offshore between 8 and 23 February 1995 in the Northwestern Arabian Sea. Water samples from 3 m depth were taken at 2-h intervals and picocyanobacterial abundance and frequency of dividing cells were determined by epifluorescence microscopy. Cell counts showed an average diel change from a mid-day minimum of ˜50×10 3 cells ml -1 to an evening maximum of ˜180×10 3 cells ml -1. The diel change was greater than the differences observed between physically and spatially discrete water masses. By counting the frequency of dividing cells (FDC) and using a novel approach to estimating the length of time required to complete cell division, growth and loss rates were both estimated to be ˜2.9 d -1 with daily turnover being 140% of the mean standing stock. If differences in the intrinsic population growth rate ( μ) and the net rate of change in cell number ( r) are assumed to be due to grazing, then grazing occurred throughout the day at a relatively constant rate (reflecting phytoplankton loss rates of ˜0.12 h -1). Cell division rates peaked in the late afternoon and early evening. FDC decreased throughout the night, suggesting that dark-inhibition of cell division is weak or nonexistent in the picocyanobacteria we studied. While all cell types included in this study would be identified as Synechococcus by flow cytometry because they were small unicells with bright phycoerythrin fluorescence, morphological variability suggests that the community was actually taxonomically diverse and included cells other than Synechococcus, including Synechocystis. Despite this diversity, the strong diel patterns we observed persisted throughout the study region, suggesting that great care should be taken when interpreting picocyanobacterial survey data and experimental results that do not account for the effects of time-of-day.

  6. 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.

  7. 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.

  8. 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.

    during the winter seasons of 2002-06. Despite the existence of a large low-salinity water intrusion into the Lakshadweep Sea, there was an unusually lower number of nearsurface thermal inversions during the winter 2005/06 compared to the other winters...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Manohar, C.S.

    Peptone 2 MgSO 4 0.2 g Trace element solution 1 ml NaNO 3 10 mM Artificial Sea Water 1000 ml 2. Trace element solution FeSO 4 . 7H 2 O 0.2 g CoCl 2 . 6H 2 1.0 CuSO 4 . 6H 2 O 0.38 g Na 2 MoO 4 . 7H 2 8.6 mg CaCl 2 0...

  10. Seasonal variations and trophic ecology of microzooplankton in the southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

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

    . Introduction The microzooplankton (MZP), heterotrophic plankton with body size 20-200 µm, plays an important role in marine pelagic ecosystems in transferring primary organic carbon to higher trophic levels (Dussart, 1963; Godhantaraman et al., 2004...) was taken as the depth at which 1ºC drop of Sea Surface Temperature (SST) was observed (Prasannakumar et al., 1996). Niskin bottles mounted on a CTD rosette were used to collect water samples from 8 discrete standard depths (0.5, 10, 20, 30, 50, 75, 100...

  11. Blooms of Noctiluca miliaris in the Arabian Sea - An in situ and satellite study

    Digital Repository Service at National Institute of Oceanography (India)

    Gomes, H.R.; Goes, J.I.; Matondkar, S.G.P.; Parab, S.G.; Al-Azri, A.R.N.; Thoppil, P.G.

    for India’s first ocean color sensor, the Ocean Color Monitor (OCM-I), on board the satellite IRS-P4. In addition to detailing the community structure of phytoplankton, it documented for the first time ever the appearance of large-scale blooms of Noctiluca... mounted on a Sea Bird Electronics s CTD Rosette. Clean techniques (Knap et al., 1996) were used in all sampling. Sensors mounted on the CTD Rosette provided vertical profiles of salinity, tem- perature and dissolved oxygen. The depth of the euphotic zone...

  12. Unusual blooms of green Noctiluca miliaris (Dinophyceae) in the Arabian Sea during the winter monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Gomes, H.R.; Matondkar, S.G.P.; Parab, S.G.; Goes, J.I.; Pednekar, S.; Al-Azri, A.R.N.; Thoppil, P.G.

    Institute of Oceanography, Goa, India, in winter and in SIM, from 2003, onward, in support of the develop- ment of bio-optical algorithms for India ’s first ocean color sensor, the Ocean Color Monitor, on board the satellite IRS- P4 has provided the first... AL. 349 Plate 1. Sampling locations for cruises (a1) CR-1-JAN-2003, (a2) CR-2-MAR-2003, (a3) CR-3-MAR-2004, (a4) CR- 4-DEC-2004, and (a5) CR-5-MAR-2007 superimposed on 8-day composites of Sea-viewing Wide Field-of-view Sensor and Aqua...

  13. 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.

  14. 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

  15. 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

  16. 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...

  17. 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

  18. 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.

    -crossing analysis of the surface elevation time series was used to estimate maximum wave height (Hmax). Mean wave direction (Dp) is esti- mated based on circular moments [7]. Significant wave height (Hm0) = 04 m (1) Mean wave period (Tm02) = 0 2m m (2....5 9.5 4.9 - 13.9 8.8 THmax (s) M 6.5 - 15.0 10.0 6.2 - 14.7 10.0 5.5 - 15.4 9.5 H 201 - 302 261 190 - 290 262 240 - 314 264 R 191 - 315 258 228 - 291 261 221 - 290 260 Dp sea (deg) M 174 - 271 230 195 - 264 229 208 - 257 231 Copyright © 2012...

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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

    2015-10-01

    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

  4. 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...

  5. Nitrogen and oxygen isotopic composition of N sub(2)O from suboxic waters of the eastern tropical North Pacific and the Arabian Sea - measurement by continuous-flow isotope-ratio monitoring

    Digital Repository Service at National Institute of Oceanography (India)

    Yoshinari, T.; Altabet, M.A.; Naqvi, S.W.A.; Codispoti, L.; Jayakumar, D.A.; Kuhland, M.; Devol, A.

    Nitrous oxide (N sub(2)O) is a trace gas that is increasing in the atmosphere. It contributes to the greenhouse effect and influence the global ozone distribution. Recent reports suggest that regions such as the Arabian Sea may be significant...

  6. A study of meteorologically and seismically induced water level and water temperature oscillations in an estuary located on the west coast of India (Arabian Sea)

    Science.gov (United States)

    Mehra, P.; Prabhudesai, R. G.; Joseph, A.; Kumar, V.; Agarvadekar, Y.; Luis, R.; Viegas, B.

    2012-05-01

    The study examines the observed storm-generated sea-level oscillations (June 2007 and November 2009) along with the Sumatra geophysical tsunami (September 2007), indicating similarities in the sea-level response in the Mandovi estuary of Goa in the eastern Arabian Sea. Sea-level and surface meteorological measurements collected during storms exhibit strong synoptic disturbances leading to the coherent oscillations in the estuary with significant energy bands centred at periods of 24, 45, and 80 min. In particular, during the sporadic atmospheric event of June 2007, the atmospheric pressure dipped by ~12 mb, the wind direction stabilized to ~249° with peak wind speed up to 16 m s-1 and the positive sea-level surge swelled up by ~40 cm. Also, the water temperature cooled down by ~4.5 °C. Approximately 3 days prior to the 12 September 2007 Sumatra earthquake, the water temperature at Verem station started exhibiting a distinctly stronger semidiurnal oscillation (with a relatively larger variance of ~17.9 °C2 in contrast to a lesser variance of ~12 °C2 during the preceding normal days) and these well-defined oscillations continued to manifest for a week after the earthquake. The pre-earthquake enhanced seawater temperature oscillations observed at this tropical estuary provides an indication that routine monitoring of seawater temperature from tropical estuaries with fine temporal resolution may provide early information about impending coastal earthquakes.

  7. A study of meteorologically and seismically induced water level and water temperature oscillations in an estuary located on the west coast of India (Arabian Sea

    Directory of Open Access Journals (Sweden)

    P. Mehra

    2012-05-01

    Full Text Available The study examines the observed storm-generated sea-level oscillations (June 2007 and November 2009 along with the Sumatra geophysical tsunami (September 2007, indicating similarities in the sea-level response in the Mandovi estuary of Goa in the eastern Arabian Sea. Sea-level and surface meteorological measurements collected during storms exhibit strong synoptic disturbances leading to the coherent oscillations in the estuary with significant energy bands centred at periods of 24, 45, and 80 min. In particular, during the sporadic atmospheric event of June 2007, the atmospheric pressure dipped by ~12 mb, the wind direction stabilized to ~249° with peak wind speed up to 16 m s−1 and the positive sea-level surge swelled up by ~40 cm. Also, the water temperature cooled down by ~4.5 °C. Approximately 3 days prior to the 12 September 2007 Sumatra earthquake, the water temperature at Verem station started exhibiting a distinctly stronger semidiurnal oscillation (with a relatively larger variance of ~17.9 °C2 in contrast to a lesser variance of ~12 °C2 during the preceding normal days and these well-defined oscillations continued to manifest for a week after the earthquake. The pre-earthquake enhanced seawater temperature oscillations observed at this tropical estuary provides an indication that routine monitoring of seawater temperature from tropical estuaries with fine temporal resolution may provide early information about impending coastal earthquakes.

  8. The Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

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

    , during the same cruises are consistent with the results of size fractionated PP (Tarran etal., 1999). [n general, pico-planktonic prokaryotcs. Synechococcus and Prochlorococcus dominated the autotrophic assemblages, and of the nano- and micro..., high abundances of nano- and micro autotrophs extended much farther offshore on TN050 when blooms of the prymnesiophyte Phaeocysti" were found at Stas. S7 and S 1I (Garrison et aI., 1998). During the late NEM (January-February) of 1995, sampled on TN...

  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. 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

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

    OpenAIRE

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

    2013-01-01

    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 th...

  12. 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 depthsphotorespiration, 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.

  13. 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.

  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. 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...

  16. 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.

  17. 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.

  18. 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

  19. Assessing spatial and temporal variability in phytoplankton concentration through chlorophyll-a satellite data: a case study of northern arabian sea

    International Nuclear Information System (INIS)

    This study focuses on applying remote sensing technology to identify and assess seasonal and intra-annual variation of phytoplankton availability. A standard MODIS algorithm for Chlorophyll-a, is used to obtain a variation of phytoplankton with the help of MODIS time series images from April 2011 to March 2012 that describe the situation for a whole year, we also used periodical data for each three months, i.e., from April 2011 to June 2011, July 2011 to September 2011, October 2011 to December 2011 and finally January 2012 to March 2012. Chlorophyll-a (Chl-a), products were retrieved from the sensor data that demonstrates the spatio-temporal variability of phytoplankton concentration in the northern Arabian sea near the coastline and open sea water of Pakistan, India, Iran and Oman. High concentration of Chl-a, were observed during two periods August to September and February to March respectively. It was also revealed that Chl-a, concentration was almost identical between the latitude 20 and 21 degrees N throughout the year. (author)

  20. 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...

  1. 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

  2. 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.

    ; Sirocko et al., 1993; Naidu and Malmgren, 1995; 1996; Overpeck et al., 1996; Altabet et al., 2002; Gupta et al., 2003; Naidu, 2004]. However, such monsoon reconstructions effectively represent the SW monsoon wind strength rather than precipitation... and decay of continental ice sheets and by local sea surface temperature (SST) and sea surface salinity, the latter linked to the local evaporation-precipitation balance. Hence, without accounting contributions of continental ice volume, local SST and sea...

  3. 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...

  4. 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...

  5. Near-inertial kinetic energy budget of the mixed layer and shear evolution in the transition layer in the Arabian Sea during the monsoons

    Science.gov (United States)

    Majumder, Sudip; Tandon, Amit; Rudnick, Daniel L.; Thomas Farrar, J.

    2015-09-01

    We present the horizontal kinetic energy (KE) balance of near-inertial currents in the mixed layer and explain shear evolution in the transition layer using observations from a mooring at 15.26° N in the Arabian Sea during the southwest monsoon. The highly sheared and stratified transition layer at the mixed-layer base varies between 5 m and 35 m and correlates negatively with the wind stress. Results from the mixed layer near-inertial KE (NIKE) balance suggest that wind energy at times can energize the transition layer and at other times is fully utilized within the mixed layer. A simple two layer model is utilized to study the shear evolution in the transition layer and shown to match well with observations. The shear production in this model arises from alignment of wind stress and shear. Although the winds are unidirectional during the monsoon, the shear in the transition layer is predominantly near-inertial. The near-inertial shear bursts in the observations show the same phasing and magnitude at near-inertial frequencies as the wind-shear alignment term.

  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. Temporal variations in the wind and wave climate at a location in the eastern Arabian Sea based on ERA-Interim reanalysis data

    Directory of Open Access Journals (Sweden)

    P. R. Shanas

    2013-12-01

    Full Text Available Temporal variations of wind speed and significant wave height (SWH at a location in the eastern Arabian Sea is studied using ERA-Interim reanalysis data during 1979–2012. A Shallow water location is selected for the study since measured buoy data is available close to the location for comparison of the reanalysis data. Annual mean wind speed shows a statistically significant decreasing trend of 1.5 cm s-1 yr-1. Weakening of SWH during one of the peak monsoon month (August is identified from the monthly analysis of SWH, which shows higher upward trend in SWH during south west monsoon period with an exception during August. The annual mean SWH shows slight upward trend (0.012 cm yr-1, whereas larger upward trend (1.4 cm yr-1 is observed for annual maximum SWH. The influence of tropical cyclone activity is also studied and found that the maximum SWH and wind speed during 1996 is directly related to the cyclonic event. The relationship between annual maximum wave height and wind speed with ENSO and Indian Ocean Dipole (IOD are tested and found that larger waves are reported during strong El-Niño and negative IOD year, whereas decrease in maximum wave height and wind speed is observed during strong La-Niña and positive IOD year.

  8. 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.

    .J., Frost, B.W., 1989. Closing the Microbial loop: dissolved carbon pathway to heterotrophic bacteria from incomplete ingestion, digestion and absorption in animal. Deep-Sea Research 36, 483-495. Krishnaswamy, K., Nair R.R. (Eds.), 1996. Joint Global... of organic carbon in the two seas and 2) the reasons why the observed productivity in the two basins and particle fluxes to the deep do not often match. To address these questions, data sets collected from 1994 onwards under the programmes -Joint Global...

  9. Sulfate-reducing bacteria from the Arabian Sea - their distribution in relation to thiosulfate-oxidising and heterotrophic bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Chandramohan, D.

    and Tables 1-3. Water samples were collected using sterile JZ samplers. Sediment samples were collected using a Petersen's grab. Chemical and bacteriological analyses of the samples were carried out on board immediatelyaftercollection. Salinity, oxygen... in sterile sea water blanks before inoculation. Media and Technique. -Culturable aerobic heterotrophic bacteria (AB) were enumerated on nutrient agar (peptone, 5 g; beef extract, 1.5 g; yeast extract, I.S g; agar, 8 g; at pH 7.8) prepared in sea water (35%o...

  10. 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.

    , Durand et al. 2004, Gopalakrishna et al. 2005, Masson et al.2005). However, Kurian and Vinayachandran (2007) suggested the role of orographic effect due to the Western Ghats which reduces the wind speed over the SEAS, resulting in positive heat flux....e., vertical), where the warming is the resultant of the surface heat fluxes and the penetrative radiation. Thus, the previous studies in the SEAS during pre monsoon period suggested that the heat budget of the upper ocean is mainly a balance between...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Parab, S.G.; Matondkar, S.G.P.; Gomes, H.; Goes, J.I.

    from several stations during cruises. The primary purpose of the latter set of observations was to gather sea-truth data for development of bio- optical algorithms in support of India’s Ocean Colour Satellite, IRS-P4 OCM Sensor. Most of these satellite...

  12. 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...

  13. 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.

  14. 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/TNprotein/carbohydrate (PRT/CHO<1) displayed that the organic matter deposited of marine origin which is relatively old with potentially low nutritional value. The close relationship between biochemical components and phytopigments suggest a major contribution of autochthonous phytodetritus derived organic matter. The study provides important information about sediment biogeochemistry and metal contamination from a potential fishery zone of Indian exclusive economic zone.

  15. 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.

  16. 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

  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. Evaluation of changes in macrobenthic standing stock and polychaete community structure along the south eastern Arabian Sea shelf during the monsoon trawl-ban

    Science.gov (United States)

    Abdul Jaleel, K. U.; Parameswaran, Usha V.; Gopal, Aiswarya; Khader, Chippy; Ganesh, T.; Sanjeevan, V. N.; Shunmugaraj, T.; Vijayan, Anil Kumar; Gupta, G. V. M.

    2015-07-01

    The south eastern Arabian Sea is characterized by moderate coastal upwelling, high biological production and subsurface oxygen depletion during the southwest monsoon (June-September). Concurrently, a seasonal closure to trawling activities (15th June-31st July) is implemented here, as a sustainable ecosystem management practise. The effects of monsoon driven environmental changes and consequences of trawling cessation on macrofauna were assessed, based on surveys at 12 sites (30-200 m) preceding and during different phases of the southwest monsoon. Macrofaunal density and biomass increased considerably towards the mid and late monsoon along the inner shelf (30-50 m) where trawling is intense, while no temporal changes were observed along the outer shelf (100-200 m). Density increased four-folds at the 30 m contour and three-folds at 50 m, while biomass nearly doubled at both depths, reflecting a marked increase in density of polychaetes (61-87% of macrofauna). The disproportionate increase in faunal density and biomass along the inner shelf (30-50 m) was due to abundance of juvenile polychaetes and dominance of small-sized opportunists towards late monsoon (August-September). A concurrent hike in nominal species count of polychaetes was also observed in the study area. The increase in polychaete standing stock and high density of planktonic larvae during onset and peak monsoon, coupled with occurrence of juveniles as well as gamete-bearing adults in sediments, indicates that the southwest monsoon is a peak breeding season for the dominant polychaetes in the region. The trawl-ban during this period facilitates the recoupment of benthos by maximising spawning success and larval settlement, thereby enhancing overall ecosystem integrity.

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

    Science.gov (United States)

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

    2016-01-01

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

  20. Predicting the variability in the wavelength structures of the incoming radiation due to ozone layer depletion at Arabian sea

    International Nuclear Information System (INIS)

    In this communication we have investigated the variability in the wavelength structures of the radiation due to ozone layer depletion (OLD) using empirical modeling approach. A model has been developed for evaluating sea surface temperature using stratospheric ozone filter. This filter has been formulated taking into account of the ozone layer depletion (OLD) strategy for Pakistan atmospheric regions. For making predictions of various wavelength, stochastic analysis is implemented here for observing future prospects of the coming radiation. These predictions are useful for public, private and government organizations. (author)

  1. Impact of oxygen-depleted water on the vertical distribution of chaetognaths in the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Kusum, K.K.; Vineetha, G.; Raveendran, T.V.; Muraleedharan, K.R.; Nair, M.; Achuthankutty, C.T.

    (BT) to 300 m, 300 – 500 m and 500 – 1000 m, based on the temperature and density characteristics of the water column. The MLD was determined as the depth up to which a temperature decrease of 0.5° C occurred from the sea surface temperature... difference in abundance was observed at BT – 300 m between the northern [67743 ± 17334 ind. (1000 m) -3 ] and southern sectors [8057 ± 6644 ind. (1000 m) -3 ]. In depth zones below 300 m, the abundance was relatively higher in the southern region (Fig. 3a...

  2. Influence of upwelling on distribution of chaetognath (zooplankton) in the oxygen deficient zone of the eastern Arabian Sea.

    Digital Repository Service at National Institute of Oceanography (India)

    Kusum, K.K.; Vineetha, G.; Raveendran, T.V.; Muraleedharan, K.R.; Biju, A.; Achuthankutty, C.T.

    depth strata: mixed layer (MLD), top to base of thermocline (TC), base of thermocline (BT) to 300 m, 300–500 m and 500–1000 m based on temperature and density characteristics (see Table 1). MLD was fixed as the depth at which a temperature decrease... of 0.5°C occurred from the sea surface temperature, and BT was taken as the depth where temperature fell to 15°C. Chaetognaths were counted by species in the whole sample or from an aliquot (50%) using a Folsom splitter. The volume strained...

  3. Bottom water oxygenation history in southeastern Arabian Sea during the past 140 ka: Results from redox-sensitive elements

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Pearce, N.J.G.

    contents are almost uniform at an average content of 0.8 ppm (Fig. 2), slightly lower than the average crustal abundance of 1.0 ppm (Taylor and McLennan, 1985). Similarly, Mn contents are low (average ~0.016 %) and almost uniform. Piper (1994... of Youngest Toba Tuff origin (Pattan et al., 2001). 4.4 Vanadium In oxic sea waters, V is present as V(V) vanadate oxyanions. Vanadate rapidly adsorbs to both Fe-Mn oxyhydroxides (Calvert and Piper, 1984). In reducing conditions, V(V) is reduced...

  4. 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...

  5. 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

  6. 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.

  7. 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

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

    Science.gov (United States)

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

    2016-04-01

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

  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. 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.

  12. 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.

  13. 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.

  14. 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.

    IRS-P4 could substantiate the increased chlorophyll a in the northern AS towards the end of March (Sarangi et al., 2005; Dwivedi et al., 2006). Even though the satellite sensors are widely used to study the distribution of chlorophyll a, the in... estimated from the above mentioned depths. The incubation for primary productivity experiments were extended up to 12 hours (06.00 to 18.00hrs). Sea-viewing Wide Field-of-view Sensor’s (SeaWiFS) monthly mean images of chlorophyll a (9-km resolution data...

  15. Observed intra-seasonal to interannual variability of the upper ocean thermal structure in the southeastern Arabian Sea during 2002-2008

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishna, V.V.; Durand, F.; Nisha, K.; Lengaigne, M.; Boyer, T.P.; Costa, J.; Rao, R.R.; Ravichandran, M.; Amrithash, S.; John, L.; Girish, K.; Ravichandran, C.; Suneel, V.

    the salient features derived from a newly harvested observational dataset consisting of repeated fortnightly XBT transects in the SEAS over the period 2002-2008. The fortnightly resolution of such a multi-year record duration is unprecedented in this part...

  16. 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.

    During winter, south of the Indo-Sri Lanka Channel (ISLC), the observed sea-surface temperature (SST) distribution shows a distinct mini-cold pool (MCP) with relatively cooler waters (SST is less than 28 degrees C). All the available satellite...

  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. 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

    Science.gov (United States)

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

    2012-12-01

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

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

    Digital Repository Service at National Institute of Oceanography (India)

    Glejin, J.; SanilKumar, V.; Nair, T.M.B.; Singh, J.

    , simultaneous wind measurements were carried out using an Autonomous Weather Station (AWS) at every 10 min interval. The AWS measures the wind speed in the range 0–60 m s−1 with an accuracy of 0.2 m s−1 and direc- tion from 0 to 360◦ with an accuracy of 3... the variation in wave characteristics (Figs. 2 and 3) at the study location along with wind direc- tion and wind speed (Fig. 4) measured using an autonomous weather station. Neetu et al. (2006) reported the presence of a sea breeze system and its impact...

  1. Paleogene magnetic isochrons and palaeo-propagators in the Arabian and Eastern Somali basins, NW Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.; Dyment, J.; Bhattacharya, G.C.; Royer, J.-Y.; Srinivas, K.; Yatheesh, V.

    A revised magnetic isochron map of the conjugate Arabian and Eastern Somali basins based on an up-to-date compilation of Indian, French, and other available sea-surface magnetic data are presented. The magnetic anomaly and the modulus...

  2. 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.

  3. Identity of Arabian Scotophilus (Vespertilionidae)

    Czech Academy of Sciences Publication Activity Database

    Vallo, Peter; Benda, P.; Reiter, A.

    Kwaluseni: University of Swaziland, 2011. s. 88. [African Small Mammal Symposium /11./. 03.08.2011-08.08.2011, Kwaluseni] Institutional research plan: CEZ:AV0Z60930519 Keywords : bats * Arabian Peninsula Subject RIV: EG - Zoology

  4. 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.

  5. 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.

  6. 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

  7. 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...

  8. AoA Region: South Asian Seas

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    The South Asian Seas region lies in the northern extreme of the Indian Ocean. It includes the Arabian Sea and Bay of Bengal Large Marine Ecosystems (LME) along with their marginal basins as well as the Laccadive Sea and the Andaman Sea. Counties...

  9. Satellite and ship studies of phytoplankton in the Northeastern Arabian during 2000 – 2006 period

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Dwivedi, R.M.; Parab, S.G.; Pednekar, S.; Desa, E.S.; Mascarenhas, A.A.M.Q.; Raman, M.; Singh, S.K.

    of Noctiluca bloom was also conducted using OCM based chlorophyll images in NE Arabian Sea. During February chlorophyll a retrieved by OCM was 0.3 to 0.9 mgm-3. Pigment analysis of water samples indicated the equal important of accessory pigment like zeaxanthin...

  10. Duration of reproductive utilization of mares from Purebred arabian and Shagya-arabian breed

    OpenAIRE

    Maya Popova

    2014-01-01

    An analysis was made of the reproductive utilization of mares from the Purebred Arabian and Shagya-Arabian breed in the only National State Stud Farm Kabiyuk near Shumen. Stud book records and the breeding registers for a 32-year period (1980-2012) were used for the analysis. Thirty-nine Purebred Arabian mares and 52 mares from the Shagya-Arabian breed were included in the study. It was established that the average (LS) age at first covering of the mares of Purebred Arabian breed was 1584,2 ±...

  11. Sea surface temperature anomalies in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.

    temperature anomalies for the above regions respectively. An analysis has shown that most of the short duration anomalies (i.e., anomalies with periods less than 4 months) are driven by the surface heat fluxes. The medium duration anomalies (i.e., anomalies...

  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. Air sea interaction during summer monsoon period of 1979

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.

    of the summer monsoon over the Kerala Coast. (2) The weak zonal anomalies of SSTs off the Somali and Arabian coasts and the weak temperature gradient prevalent throughout the monsoon season in the Arabian Sea, Bay of Bengal and Indian Ocean are associated...

  14. Evidence for anomalous mantle upwelling beneath the Arabian Platform from travel time tomography inversion

    Science.gov (United States)

    Koulakov, Ivan; Burov, Evgeniy; Cloetingh, Sierd; El Khrepy, Sami; Al-Arifi, Nassir; Bushenkova, Natalia

    2016-01-01

    We present a new model of P-velocity anomalies in the upper mantle beneath the Arabian Peninsula, Red Sea, and surrounding regions. This model was computed with the use of travel time data from the global catalogue of the International Seismological Center (ISC) for the years of 1980-2011. The reliability of the model was tested with several synthetic tests. In the resulting seismic model, the Red Sea is clearly associated with a higher P-velocity anomaly in the upper mantle at least down to 300 km depth. This anomaly might be caused by upward deviation of the main mantle interfaces caused by extension and thinning of the lithosphere due to passive rifting. Thick lithosphere of the Arabian Platform is imaged as a high-velocity anomaly down to 200-250 km depth. Below this plate, we observe a low-velocity structure that is interpreted as a hot mantle upwelling. Based on the tomography results, we propose that this upper mantle anomaly may represent hot material that migrates westward and play a major role in the formation of Cenozoic basaltic lava fields in western Arabia. On the northeastern side of the Arabian Plate, we clearly observe a dipping high-velocity zone beneath Zagros and Makran, which is interpreted as a trace of subduction or delamination of the Arabian Plate lithosphere.

  15. 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

  16. Travelers' Health: MERS in the Arabian Peninsula

    Science.gov (United States)

    ... Arabian Peninsula View Larger Map Cases of MERS (Middle East Respiratory Syndrome) have been identified in multiple countries ... 7100). Additional Information: MERS Health Advisory Poster CDC Middle East Respiratory Syndrome (MERS) Middle East Respiratory Syndrome (MERS) ...

  17. 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 ...

  18. SADDLEBACK SYNDROME IN WILD SILVER POMFRET, Pampus argenteus (EUPHRASEN, 1788) (FAMILY: STROMATIDAE) FROM THE ARABIAN GULF COASTS OF OMAN

    OpenAIRE

    Juma Al-Mamry; Jawad, L. A.

    2012-01-01

    The saddleback syndrome is recorded for the second time in a wild fish population of the Arabian Sea coasts of Oman. The deformed specimens of Pampus argenteus present a typical saddleback phenotype of missing dorsal fin pterygiophores. The possible causative agents of the saddleback syndrome in fishes are discussed.

  19. SADDLEBACK SYNDROME IN WILD SILVER POMFRET, Pampus argenteus (EUPHRASEN, 1788 (FAMILY: STROMATIDAE FROM THE ARABIAN GULF COASTS OF OMAN

    Directory of Open Access Journals (Sweden)

    Juma Al-Mamry

    2012-10-01

    Full Text Available The saddleback syndrome is recorded for the second time in a wild fish population of the Arabian Sea coasts of Oman. The deformed specimens of Pampus argenteus present a typical saddleback phenotype of missing dorsal fin pterygiophores. The possible causative agents of the saddleback syndrome in fishes are discussed.

  20. 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 ...

  1. 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 ...

  2. 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

  3. Air-sea interactions and exchanges

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    and geographical variability. The seasonal contrasts in pCO sub(2) and in the air-sea flux are best marked in coastal waters, but large seasonality in the open ocean is also observed in the Southern Indian Ocean. The Arabian Sea appears to account for at least one...

  4. Comparison of Arabian plate motion using satellite laser ranging and GPS observations

    Science.gov (United States)

    Alothman, A. O.; Fernandes, R. M.; Schillak, S. R.

    2013-12-01

    Two different space based observations have been used to estimate the velocity of the Arabian plate motion. The first set of observations is using the Saudi Arabia Laser Ranging Observatory (SALRO - 7832), which is situated in the middle of Arabian tectonic plate. Satellite Laser Ranging (SLR) observations of about 20 global SLR stations to LAGEOS-1 and LAGEOS-2 satellites collected for 14 years (1996-2009) have been used to determine Riyadh SLR station positions. The NASA Godard's GEODYN-II orbital software has been used to perform orbit determination of these two satellites. The velocities of SALRO were computed in reference to the ITRF2008 terrestrial reference frame. The second set of observations consists of Global Positioning System (GPS) observations of 15 GPS stations acquired in campaign and continuous mode for the period 2003 to 2009 (having at least 3 years' data span). Multi-year processing of stations having at least 3 years' time span and excluding stations within the deformation zone of Red Sea Ridge, such that they are distributed evenly within the rigid (interior) part of the Arabian plate. The Bernese 5.0/ADNEQ2 and GIPSY/OASIS 6.1 software packages were used to compute the daily solutions of coordinate time series applying the Precise Point Positioning (PPP) strategy. The velocities were estimated with respect to ITRF2008 and four estimates of the angular velocities for the Arabian plate have been computed using different datasets: independent Bernese and GIPSY solutions, combination of the GPS solutions only, and including the SLR solution. We present direct comparison between all different solutions showing that the Arabian tectonic plate motion determined from Riyadh SLR data and GPS data are in a good agreement with recent estimates, in particular with the global geodetic model GEODVEL and the geophysical MORVEL model.

  5. 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

  6. 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...

  7. Identification of source for excess methane in marine atmosphere over Arabian coast

    Science.gov (United States)

    Kameswara Rao, D.; Jani, R. A.

    2012-12-01

    Systematic air sampling has been done on board 'Sagar Pachmi' in the costal region of Arabian Sea along the cruise track from Cochin to Goa during November 2010 to find the source for excess methane in marine atmosphere over Arabian Sea. Ambient air was collected into a 10L SS cylinders at 7bar pressure and also in a 200cc evacuated glass bulbs for isotopic and concentration measurements from a height of ~5 meters above Sea surface at different latitude intervals. The carbon isotopic composition (delta13C) in these samples were measured using dual inlet IRMS after methane is converted in to CO2 using conventional method. Methane concentrations in all these samples vary from 1880 to 1943 ppbv where as its delta13C value vary in a narrow range of -44.9 to -46.5‰. The CH4 concentrations are more than that of tropospheric values (1775 ppbv) over the costal waters of Arabian Sea from Kanyakumari to Mumbai during the month of November-December from 2003-2007. It is estimated that an excess methane of ~ 7 - 11% in these samples. In general, it is believed that CH4 concentrations in marine atmosphere are related to emissions from the Arabian Sea due to upwelling which brings methane rich water to the surface. The excess methane in these samples is either from methane rich water in surface waters or wind flown from land surface to sampling location. Our data suggests that excess methane must have come from land to Ocean surface since the wind direction is NE in these samples. Also, there is an increase of CH4 concentrations with increasing wind speed. This also indicates that CH4 emissions must have come from land surface. The values of delta13C of CH4 in these samples are enriched compared to that of from tropospheric value (-47.1‰) which indicates that the excess methane is thermogenic type and probably the methane must have come from land. We estimated the delta13C of CH4 for this excess methane and they vary between -39 to -25‰. It indicates that the source for

  8. 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.

  9. 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

  10. Temperature profile and water depth data collected from USS COCHRANE using BT and XBT casts in the Indian Ocean and other seas from 01 August 1987 to 27 September 1987 (NODC Accession 8700394)

    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 COCHRANE in the Indian Ocean, Arabian Sea, Laccadive Sea, and Philippine...

  11. Seasonal characteristics of the large-scale moisture flux transport over the Arabian Peninsula

    Science.gov (United States)

    Athar, H.; Ammar, K.

    2016-05-01

    The relationship between the lower tropospheric (1000 to 850 hPa) large-scale moisture flux transport and the precipitation over the Arabian Peninsula (AP), on a seasonal basis, using the NCEP-NCAR gridded dataset for the 53-year period (1958-2010), is investigated. The lower tropospheric moisture flux divergence occurs due to the Hadley cell-based descending air over the AP, as well as due to the presence of Somali jet in dry season (June to September) for the southern (≤22° N) AP domain, leading to significantly reduced precipitation in the AP. The AP thus acts more as a net transporter of moisture flux from adjacent Sea areas to nearby regions. The North Atlantic Oscillation (NAO) and the Artic Oscillation (AO) climatic indices are found to modulate significantly the net seasonal moisture flux into the AP region animating from the Mediterranean Sea, and the Arabian Sea, both for the northern (≥22° N) and southern AP domains.

  12. 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.

  13. 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

  14. 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.

    during the monsoons, annually, an eddy-mediated enhanced biological production, at regional to basin-wide scales is proposed. The enhanced production caused by a high nutrient supply mechanism such as a meso-scale eddy leads directly to organic carbon...

  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.

    - logical sciences and interpretation in the electron microscope. The authors feel that the summer school in electron microscopy, the first of its kind in India, has more than fulfilled the object of the organisers.. Dept. of Inorganic and Physical Chemistry... structure with function. Drs. P. Sadhukhan and D. N. Misra (Saha Institute of Nuclear Physics) dis- cussed the different procedures of "particle counting by electron microscopy and its applica- tion in quantitative virology" and "the mass thickness...

  16. 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...

  17. 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 ...

  18. 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.

    spe- cies, and the risk of potential taxonomic classification error is lower at a higher level of identification 7 . Ferraro and Cole 4,8 hypothesized that when a given stress increases, it successively affects individuals, species, genera.... This is in accordance with the study of Dethier and Schoch 10 , in which they explained weak estuarine gradients with family level patterns. The present study has no scope to take the taxonomic level higher than family (as only polychaetes are considered), how...

  19. 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; DeSouza, W.; Narvekar, P.V.; Jayakumar, D.A; Devol, A; Yoshinari, T.; Saino, T.

    to complete anoxia). Unlike the open-ocean system, the coastal system seems to have undergone a change (i.e., it has intensified) over the past few decades presumably due to gone enhanced nutrient loading from land. The two systems also differ from each other...

  20. 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...

  1. 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.

    -hourly currents, temperature (T) and salinity (S) at depths of 2 and 7 m (Make: FSI 2D), and hourly currents at 15 and 25 m (Aanderaa RCM9). In order to estimate lateral heat advection in the upper ocean using observed currents, we made repeat CTD (Idronaut...

  2. Biochemical composition of zooplankton from the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, K.L.; Sreepada, R; 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 ...

  3. Seasonality and composition of phytoplankton in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Madhupratap, M.

    population when three seasons were combined, followed by cyanobacteria (7%) and dinoflagellate (6%). The common diatoms were Nitzschia sp., N. seriata, N. longissima, Thalassiothrix spp., Rhizosolenia spp. and Chaetoceros spp. Some diatoms like Fragilaria sp...

  4. 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.

    . by turbidity currents and sediment gravity flows during the Late Pleistocene. Correlation between organic carbon (C) and sulfur (S) varied significantly and the sediments are enriched in sulfur compared to normal marine sediments. The C-S relationship...

  5. 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.

    , University of Kerala, 275 pp. Eppley, R.W. and Peterson, B.J., 1979. Particulate organic matter flux and planktonic new pro- duction in the deep ocean. Nature, 282: 677-680. Hargrave, B.T., 1984. Sinking of particulate matter from the surface water...

  6. 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 ...

  7. 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.

    spectra, the average difference between the spectral peaks was 0.11 Hz, and the average ratio of the spectral energy density at the two peaks was 0.5. Significant wave heights up to 4.2 m and a maximum wave height of 7 m were observed during the south...

  8. 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.

    stable eigen rays enabled reconstruction of temperature anomaly from the sound speed perturbation. A linear relation was used to transform sound speed perturbations in the vertical plane to temperature perturbations for the first four days of transmission...

  9. 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.

    (January and late February-early March) of the northeast monsoon 2003 revealed a fivefold increase in the average euphotic zone integrated NO sub (3) sup(-) uptake from January (2.3 mmolN m sup(-2) d sup(-1)) to late February-early March (12.7 mmolN m sup...

  10. 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.

    some of the earlier hydro- graphic observations. Acknowledgements A national programme like ARMEX would not have been possible without the support and co- operation of several groups. We thank them all. We thank the Department of Science and Technology...; the software pack- ages Ferret and GMT were used extensively. The harmonic analysis for internal tides was done using the package TASK. This is NIO contribution 3978. References Anonymous 1996 TASK: Tidal Analysis Software Kit, Proudman Oceanographic Laboratory...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Chandramohan, D.

    the water column with temperatures lower than 25 degrees C. Bacterial luminescence in all the seawater samples was very low indicating energy conservation mechanism in free living luminous procaryotes. In contrast, a 10000 fold higher bacterial luminescence...

  12. 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...

  13. 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...

  14. 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.

    in the mixed layer depth which, in turn, is controlled by the strength of the Findlater Jet and the curl of the wind stress. The increase in biogenic silica fluxes during the late SW monsoon is related to the advection of nutrient-rich water from the Oman...

  15. Interannual variability of chlrophyll concentration in the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Karanje, S.

    satellites measure the characteristics of light, or radiance, coming from the Earth's surface. To learn about what is in the water using observations from space, we must first know what influences the color of water. Samples of ocean water are taken.... In these cases, a fairly simple relationship exists between the color that the satellite observes and the density of phytoplankton. Ratios of light intensity detected at various wavelengths of the visible and infrared spectrum have been used in algorithms...

  16. 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.

    is annihilated later in May by up- welling, and by the in ow of high-salinity waters from the north and by mixing due to stronger winds, which deepen the mixed layer. We present evidence from satellite data and arguments based on existing theories to show...

  17. 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.

    stored at ;58C in a box containing ice and analysed immediately on arrival at the shore laboratory the same day. Subsamples for CH were drawn in ;125-ml 4 air-tight glass bottles, immediately after those for O , taking care not to introduce any air... bubbles. 2 These were preserved with 0.25 ml of saturated mercuric chloride solution and stored in the dark in a Ž. refrigerator temperature ;48C until analysis in the shore laboratory within a month of collection. It has been shown that poisoned seawater...

  18. 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...

  19. Dust depositions leading to phytoplankton blooms in the Arabian sea.

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, P.; PrasannaKumar, S.

    an oligotrophic region (direction south to north), the probability of advection of nutrients/Chl a can be ruled out for each of these cases. Also a careful examination of the water column dissolved iron (DFe) from profiles collected earlier (Takeda et al...

  20. 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.

    MurrayRidge (MR) located near the highly productive upwelling region of the Available online at www.sciencedirect.com Palaeogeography, Palaeoclimatology, Palaeoecolo and mid-water oxygen-minimum zone (Halbach and Manheim, 1. Introduction Open... cyanobacteria, which form nodules in particular in intertidal regions (Golubic, 1976). As the microbial filaments themselves were phospha- tized, it evidentlyoccurredbefore the complete decay oforganic matter associated with the sheath of the filaments...

  1. 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.

    and changes in H 2 CO 3 dissociation constants; such areas serve as important sites of CO 2 removal from the atmosphere. Conversely, oceanic areas of divergence, such as the eastern boundary up welling zones and the equatorial Pacific are principal sites...; in the absence of this mechanism the atmospheric CO 2 content would have been several-fold higher and consequently the earth would have been much warmer. Conversely, the high pCO 2 values in subsurface waters (particularly at intermediate depths...

  2. Neotectonic map of Syria and some aspects of Late Cenozoic evolution of the northwestern boundary zone of the Arabian plate

    Science.gov (United States)

    Rukieh, M.; Trifonov, V. G.; Dodonov, A. E.; Minini, H.; Ammar, O.; Ivanova, T. P.; Zaza, T.; Yusef, A.; Al-Shara, M.; Jobaili, Y.

    2005-09-01

    The neotectonic map of Syria, 1:500,000, was compiled by the authors in 2003-2004. The map shows tectonic features formed or continued to develop during the Neogene and Quaternary in Syria and adjacent territories, including the Mediterranean realm. The neotectonic structure of the region was formed as a result of three phases of deformation. During the Early Miocene first phase, the Arabian plate moved along the Dead Sea-Jordan segments of the Levant (Dead Sea) transform fault zone, Roum fault and its continuation in the continental slope of the Mediterranean. The chain of the coastal anticlines in the "Arabian" side of the transform zone and the Lattaqie oblique (sinistral-thrust) boundary fault zone in the north were formed under the NNW-trending compression. The Lattaqie zone continued by the Cyprus arc in the west and by the Taurus (Bitlis) thrust in the east and further by the Main Thrust of the Zagros. After "quiet" (for Syria) epoch of the Middle Miocene when the Arabian plate moved to the NE, during the Late Miocene second phase of deformation, the Arabian plate moved again to the NNW along the same transform boundary. But a part of the Late Miocene plate motion (up to 20 km) resulted by shortening in the Anti-Leban-Palmyride fold-thrust belt that separated the Aleppo block from the main part of the Arabian plate. During the Pliocene-Quaternary third phase of deformation, the recent structural pattern of the Levant zone was formed in Lebanon and the northwestern Syria. At the same time, the Serghaya and smaller sinistral faults branched out the Levant zone and the system of the W-E-trending convex to the south dextral faults ruptured the Palmyrides and the stable part of the Arabian plate. The total Pliocene-Quaternary sinistral offset on the young Levant zone segments and the associated faults has reached 35-40 km, like on the Dead Sea-Jordan segments of the Levant fault zone. The faults, demonstrating the Pliocene-Quaternary activity are still active now

  3. 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

  4. Air-sea coupling during the tropical cyclones in the Indian Ocean: A case study using satellite observations

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, B.; Murty, V.S.N.; Sharp, R.J.; O'Brien, J.J.

    . This contrasting oceanic response resulted mainly from the salinity stratification in the Bay of Bengal and thermal stratification in the Arabian Sea and the associated mixing processes. In particular, the cyclones moved over the region of low salinity and smaller...

  5. 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...

  6. 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.

  7. 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 

  8. 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

  9. 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. 

  10. New records and new species of Magelonidae (Polychaeta) from the Arabian Peninsula, with a re–description of Magelona pacifica and a discussion on the magelonid buccal region

    OpenAIRE

    Mortimer, Kate; Cassà, Susanna; Martin, Daniel; Gil, João

    2012-01-01

    Five Magelona species, M. cornuta, M. crenulifrons, M. obockensis, M. pulchella, and an undescribed species (identified by Louis Amoureux as M. cornuta in 1983 and described herein as M. montera sp. nov.) have been previously reported from the seas surrounding the Arabian Peninsula. The present study details a further six Magelona species off the coasts of Iran and Qatar, collected between 1998 and 2007. Five species are newly recorded for the region: Magelona cf. agoensis, Magelo...

  11. Rapid late Pleistocene/Holocene uplift and coastal evolution of the southern Arabian (Persian) Gulf

    Science.gov (United States)

    Wood, Warren W.; Bailey, Richard M.; Hampton, Brian A.; Kraemer, Thomas F.; Lu, Zhong; Clark, David W.; James, Rhodri H. R.; Al Ramadan, Khalid

    2012-03-01

    The coastline along the southern Arabian Gulf between Al Jubail, Kingdom of Saudi Arabia, and Dubai, UAE, appears to have risen at least 125 m in the last 18,000 years. Dating and topographic surveying of paleo-dunes (43-53 ka), paleo-marine terraces (17-30 ka), and paleo-marine shorelines (3.3-5.5 ka) document a rapid, > 1 mm/a subsidence, followed by a 6 mm/a uplift that is decreasing with time. The mechanism causing this movement remains elusive but may be related to the translation of the coastal area through the backbasin to forebulge hinge line movement of the Arabian plate or, alternatively, by movement of the underlying Infracambrian-age Hormuz salt in response to sea-level changes associated with continental glaciation. Independent of the mechanism, rapid and episodic uplift may impact the design of engineering projects such as nuclear power plants, airports, and artificial islands as well as the interpretation of sedimentation and archeology of the area.

  12. 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

  13. 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.

  14. Reproductive Performance of Arabian and Thoroughbred Mares under Subtropical Conditions of Pakistan

    OpenAIRE

    Warriach, H. M.; Memon, M. A.; Ahmad, N; Norman, S. T.; Ghafar, A.; Arif, M.

    2014-01-01

    Breeding records of 57 Arabian and 66 Thoroughbred mares were analysed to assess their reproductive performance under the subtropical conditions of Pakistan. The Arabian mares showed significantly higher conception rates (p

  15. 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.

    of Bengal show that particle flux patterns are related to the strong monsoon winds and heavy rains. Particle flux maxima in the Arabian Sea are mainly related to wind-induced deeper mixing and nutrient enrichment of surface waters during the SW and NE...

  16. 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...

  17. 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

  18. 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.

  19. 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.

  20. 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…

  1. 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.…

  2. 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…

  3. 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…

  4. Sebaceous adenitis in a 7-year-old Arabian gelding

    OpenAIRE

    Osborne, Christina

    2006-01-01

    A 7-year-old Arabian gelding was presented with a 9-month history of progressive patches of nonpruritic scaling, crusting, alopecia, and leukoderma of the periocular areas and muzzle, becoming generalized over time. Sebaceous adenitis was diagnosed on histopathologic examination. Lesions resolved without treatment, coinciding with regression of a sarcoid on the neck.

  5. "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…

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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

  12. 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...

  13. 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

  14. Microsatellite analysis of genetic diversity and population structure of Arabian horse populations.

    Science.gov (United States)

    Khanshour, Anas; Conant, Eleanore; Juras, Rytis; Cothran, Ernest Gus

    2013-01-01

    The Arabian horse ignites imagination throughout the world. Populations of this breed exist in many countries, and recent genetic work has examined the diversity and ancestry of a few of these populations in isolation. Here, we explore 7 different populations of Arabians represented by 682 horses. Three of these are Middle Eastern populations from near the historical origin of the breed, including Syrian, Persian, and Saudi Arabian. The remaining Western populations are found in Europe (the Shagya Arabian and Polish Arabian) and in America (American Arabian). Analysis of genetic structure was carried out using 15 microsatellite loci. Genetic distances, analysis of molecular variance, factorial correspondence analysis, and a Bayesian method were applied. The results consistently show higher level of diversity within the Middle Eastern populations than the Western populations. The Western Arabian populations were the main source among population variation. Genetic differentiation was not strong among all Middle Eastern populations, but all American Arabians showed differentiation from Middle Eastern populations and were somewhat uniform among themselves. Here, we explore the diversities of many different populations of Arabian horses and find that populations not from the Middle East have noticeably lower levels of diversity, which may adversely affect the health of these populations. PMID:23450090

  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. Guidelines to classification and nomenclature of Arabian felsic plutonic rocks

    Science.gov (United States)

    Ramsay, C.R.; Stoeser, D.B.; Drysdall, A.R.

    1986-01-01

    Well-defined procedures for classifying the felsic plutonic rocks of the Arabian Shield on the basis of petrographic, chemical and lithostratigraphic criteria and mineral-resource potential have been adopted and developed in the Saudi Arabian Deputy Ministry for Mineral Resources over the past decade. A number of problems with conventional classification schemes have been identified and resolved; others, notably those arising from difficulties in identifying precise mineral compositions, continue to present difficulties. The petrographic nomenclature used is essentially that recommended by the International Union of Geological Sciences. Problems that have arisen include the definition of: (1) rocks with sodic, zoned or perthitic feldspar, (2) trondhjemites, and (3) alkali granites. Chemical classification has been largely based on relative molar amounts of alumina, lime and alkalis, and the use of conventional variation diagrams, but pilot studies utilizing univariate and multivariate statistical techniques have been made. The classification used in Saudi Arabia for stratigraphic purposes is a hierarchy of formation-rank units, suites and super-suites as defined in the Saudi Arabian stratigraphic code. For genetic and petrological studies, a grouping as 'associations' of similar and genetically related lithologies is commonly used. In order to indicate mineral-resource potential, the felsic plutons are classed as common, precursor, specialized or mineralized, in order of increasing exploration significance. ?? 1986.

  17. 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.

    Sea and the southern Indian Ocean. An analysis of ten-day and monthly mean evaporation rates over the Arabian Sea and Bay of Bengal shows that the evaporation was higher in these areas during the low rainfall year (1987) indicating little...

  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

  1. Spatial and temporal variations of wave height in shelf seas around India

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Anoop, T.R.

    1979–2012, a weak statistically significant increasing trend (maximum ~0.20 cm/year) in wave height is observed in the northern and southern region of eastern Arabian Sea, whereas the middle region shows negligible negative trend. A weak decreasing...

  2. The Dead Sea

    Science.gov (United States)

    2006-01-01

    The Dead Sea is the lowest point on Earth at 418 meters below sea level, and also one of the saltiest bodies of water on Earth with a salinity of about 300 parts-per-thousand (nine times greater than ocean salinity). It is located on the border between Jordan and Israel, and is fed by the Jordan River. The Dead Sea is located in the Dead Sea Rift, formed as a result of the Arabian tectonic plate moving northward away from the African Plate. The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride. In the early part of the 20th century, the Dead Sea began to attract interest from chemists who deduced that the Sea was a natural deposit of potash and bromine. From the Dead Sea brine, Israel and Jordan produce 3.8 million tons potash, 200,000 tons elemental bromine, 45,000 tons caustic soda, 25, 000 tons magnesium metal, and sodium chloride. Both countries use extensive salt evaporation pans that have essentially diked the entire southern end of the Dead Sea. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining

  3. Analysis of the spatio-temporal variability of seawater quality in the southeastern Arabian Gulf.

    Science.gov (United States)

    Mezhoud, Nahla; Temimi, Marouane; Zhao, Jun; Al Shehhi, Maryam Rashed; Ghedira, Hosni

    2016-05-15

    In this study, seawater quality measurements, including salinity, sea surface temperature (SST), chlorophyll-a (Chl-a), Secchi disk depth (SDD), pH, and dissolved oxygen (DO), were made from June 2013 to November 2014 at 52 stations in the southeastern Arabian Gulf. Significant variability was noticed for all collected parameters. Salinity showed a decreasing trend, and Chl-a, DO, pH, and SDD demonstrated increasing trends from shallow onshore stations to deep offshore ones, which could be attributed to variations of ocean circulation and meteorological conditions from onshore to offshore waters, and the likely effects of desalination plants along the coast. Salinity and temperature were high in summer and low in winter while Chl-a, SDD, pH, and DO indicated an opposite trend. The CTD profiles showed vertically well-mixed structures. Qualitative analysis of phytoplankton showed a high diversity of species without anomalous species found except in Ras Al Khaimah stations where diatoms were the dominating ones. PMID:27012536

  4. Environmental assessment of coastal surface sediments at Tarut Island, Arabian Gulf (Saudi Arabia)

    International Nuclear Information System (INIS)

    Highlights: • The present work deal with the environmental assessment of Tarut Island Coastal area. • Thirty eight surface sediments samples have been chemically analyzed. • Thirteen major and trace metals have been recorded. • The area of study is highly polluted with Arsenic and Mercury. - Abstract: Thirty eight surface sediments samples have been collected in the area around Tarut Island, Saudi Arabian Gulf to determine the spatial distribution of metals, and to assess the magnitude of pollution. Total concentrations of Fe, Mn, As, B, Cd, Co, Cr, Cu, Hg, Mo, Pb, Se, and Zn in the sediments were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). Nature of sediments and heavy metals distribution reflect marked changes in lithology, biological activities in Tarut bay. Very high arsenic concentrations were reported in all studied locations from Tarut Island. The concentrations of Mercury are generally high comparing to the reported values from the Gulf of Oman, Red Sea. The concentrations of As and Hg exceeded the wet threshold safety values (MEC, PEC) indicating possible As and Hg contamination. Dredging and land filling, sewage, and oil pollution are the most important sources of pollution in the study area

  5. Mangrove ecosystem of Red Sea coast (Saudi Arabia)

    OpenAIRE

    S. M. Saifullah

    1997-01-01

    The present paper reviews critically the existing information on mangrove ecosystem of Saudi Arabian Red Sea coast and identifies problems and shortcomings that should be removed or remedied. Mangrove structure and composition seems to have been substantially studied along with salient environmental features, and these are thoroughly summarized herewith. However, the functional aspects, especially energy flow through the ecosystem, remain totally neglected. Both the flora and fauna indicate s...

  6. Movement Patterns of Juvenile Whale Sharks Tagged at an Aggregation Site in the Red Sea

    OpenAIRE

    Berumen, Michael L.; Camrin D Braun; Cochran, Jesse E. M.; Skomal, Gregory B.; Simon R Thorrold

    2014-01-01

    Conservation efforts aimed at the whale shark, Rhincodon typus, remain limited by a lack of basic information on most aspects of its ecology, including global population structure, population sizes and movement patterns. Here we report on the movements of 47 Red Sea whale sharks fitted with three types of satellite transmitting tags from 2009-2011. Most of these sharks were tagged at a single aggregation site near Al-Lith, on the central coast of the Saudi Arabian Red Sea. Individuals encount...

  7. Insights into Seismic and Volcanic Processes around the Arabian Plate from InSAR Observations

    Science.gov (United States)

    Jónsson, Sigurjón; Wang, Teng; Akoglu, Ahmet; Feng, Guangcai; Xu, Wenbin; Harrington, Jonathan; Cavalié, Olivier

    2014-05-01

    We use InSAR observations to study a variety of seismic and volcanic processes at the plate boundary surrounding the Arabian plate. The plate-boundary motion ranges from extension in the Red Sea and Gulf of Aden to the south, to compression in Turkey and Iran to the north, with transform motion to the west and to the east. Many large earthquakes have occurred during the past two decades in the region, some of which we are studying, including the 1995 magnitude 7.2 earthquake in the Gulf of Aqaba, the 2011 magnitude 7.1 Van earthquake in eastern Turkey, the 2012 Ahar earthquake duplet in northwestern Iran, as well as the 2013 magnitude 7.7 Baluchistan (Pakistan) earthquake. These earthquakes took place in tectonic settings ranging from a transtension in the Gulf of Aqaba, to transpression in Baluchistan, to almost pure compression in eastern Turkey. For the Aqaba earthquake we add previously unused InSAR data and use modern data processing methods to improve earlier fault-model estimations. In the case of the Baluchistan earthquake we find surprisingly uniform and simple fault slip along the over 200 km long rupture, with maximum slip of almost 10 m near the surface. In addition, for the Van earthquake we use SAR-image offset tracking in the near-field, as some of the interferograms are almost completely incoherent. By identifying point-like targets within the images, we are able to derive better pixel offsets between SAR sub-images than with standard offset-tracking methods. We use the azimuth- and range offsets to derive the 3D coseismic displacements, which help constraining the geometry and slip of the causative northward-dipping thrust fault. Further west, in the region near the triple junction between the Arabian, Eurasian, and Anatolian plates, we use large-scale InSAR data processing to map the interseismic deformation near the triple junction and find very shallow locking depth of the eastern part of the East Anatolian Fault, indicating limited strain

  8. Purkinje cell apoptosis in arabian horses with cerebellar abiotrophy.

    Science.gov (United States)

    Blanco, A; Moyano, R; Vivo, J; Flores-Acuña, R; Molina, A; Blanco, C; Monterde, J G

    2006-08-01

    Purkinje cerebellar cells were studied in three Arabian horses aged between 6 and 8 months with clinical disorders in their movements, tremors and ataxia; the occurrence of apoptosis in this cell population was investigated by the (terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling (TUNEL) method. Both optical and electron microscopical images showed a scant number of Purkinje cells, most of them with morphological features of apoptosis such as condensation of the nucleus and cytoplasm as well as segregation and fragmentation of the nucleus into apoptotic bodies. The TUNEL technique revealed a substantial number (65%) of positive immunoreactive Purkinje cells. PMID:16901270

  9. XY male pseudohermaphroditism in a captive Arabian oryx (Oryx leucoryx).

    Science.gov (United States)

    Padilla, Luis R; Dutton, Christopher J; Bauman, Joan; Duncan, Mary

    2005-09-01

    A 2-yr-old Arabian oryx (Oryx leucoryx) was presented for evaluation of abnormal genitalia and infantile behavior. The oryx had a penis and a scrotum, but testes were not palpable within the scrotum or inguinal canal. The total serum testosterone for the individual was lower than in age-matched males of the same species. Surgical exploration showed markedly hypoplastic intra-abdominal gonads, which demonstrated both testicular and uterine tissue on histologic examination. After karyotype analysis, the individual was classified as an XY male pseudohermaphrodite. This condition resembles two human intersex syndromes: embryonic testicular regression syndrome and partial gonadal dysgenesis syndrome, which occur in familial lines. PMID:17312771

  10. Seascape genetics along environmental gradients in the Arabian Peninsula: insights from ddRAD sequencing of anemonefishes

    KAUST Repository

    Saenz Agudelo, Pablo

    2015-11-17

    Understanding the processes that shape patterns of genetic structure across space is a central aim of landscape genetics. However, it remains unclear how geographic features and environmental variables shape gene flow, particularly for marine species in large complex seascapes. Here, we evaluated the genomic composition of the two-band anemonefish Amphiprion bicinctus across its entire geographic range in the Red Sea and Gulf of Aden, as well as its close relative, Amphiprion omanensis endemic to the southern coast of Oman. Both the Red Sea and the Arabian Sea are complex and environmentally heterogeneous marine systems that provide an ideal scenario to address these questions. Our findings confirm the presence of two genetic clusters previously reported for A. bicinctus in the Red Sea. Genetic structure analyses suggest a complex seascape configuration, with evidence of both Isolation by Distance (IBD) and Isolation by Environment (IBE). In addition to IBD and IBE, genetic structure among sites was best explained when two barriers to gene flow were also accounted for. One of these coincides with a strong oligotrophic-eutrophic gradient at around 16-20˚N in the Red Sea. The other agrees with an historical bathymetric barrier at the straight of Bab al Mandab. Finally, these data support the presence of inter-specific hybrids at an intermediate suture zone at Socotra and indicate complex patterns of genomic admixture in the Gulf of Aden with evidence of introgression between species. Our findings highlight the power of recent genomic approaches to resolve subtle patterns of gene flow in marine seascapes.

  11. Geodynamic and Magmatic Evolution of the Eastern Anatolian-Arabian Collision Zone, Turkey

    Science.gov (United States)

    Keskin, Mehmet

    2014-05-01

    The Eastern Anatolian-Arabian Collision Zone represents a crucial site within the Tethyan domain where a subduction system involving a volcanic arc (i.e. Cretaceous to Oligocene Pontide volcanic arc in the north) associated with a large subduction-accretion complex (i.e. Cretaceous to Oligocene Eastern Anatolian Accretionary Complex i.e. "EAAC" in the south) turned later into a major continental collision zone that experienced a series of geodynamic events including lithospheric delamination, slab-steepening & breakoff, regional domal uplift, widespread volcanism and tectonic escape via strike slip fault systems. The region includes some of the largest volcanic centers (e.g. Karacadaǧ, Aǧırkaya caldera, Ararat, Nemrut, Tendürek and Süphan volcanoes) and plateaus (e.g. The Erzurum-Kars Plateau) as well as the largest transform fault zones in the Mediterranean region. A recent geodynamic modeling study (Faccenna et al., 2013) has suggested that both the closure of the Tethys Ocean and the resultant collision were driven by a large scale and northerly directed asthenospheric mantle flow named the "Tethyan convection cell". This convection cell initiated around 25 Ma by combined effects of mantle upwelling of the Afar super plume located in the south, around 3,000 km away from the collision zone and the slab-pull of the Tethyan oceanic lithosphere beneath Anatolia in the north. The aforementioned mantle flow dragged Arabia to the north towards Eastern Anatolia with an average velocity of 2 cm/y for the last 20 My, twice as fast as the convergence of the African continent (i.e. 1 cm/y) with western and Central Turkey. This 1 cm/y difference resulted in the formation of the left lateral Dead Sea Strike Slip Fault between the African and Arabian plates. Not only did this mantle flow result in the formation of a positive dynamic topography in the west of Arabian block, but also created a dynamic tilting toward the Persian Gulf (Faccenna et al., 2013). Another

  12. Oil pollution in the seas around India and application of remote sensing for its detection and monitoring

    Digital Repository Service at National Institute of Oceanography (India)

    Fondekar, S.P.

    products were trans ported along these routes through the Arabian Sea and the Bay of Bengal in 1987, thus exposing some of our coastal areas to 40 the risk of pollution. Plm)l!BT STATUS OIr OIL POLLUTION Observations on oil slicks. floating petroleum...

  13. Qualitative Hoof Characteristics in Anglo-Arabian Horses and Monterufoli Ponies Reared in the Same Farm

    OpenAIRE

    R. TOCCI; C. Sargentini; Martini, A.; A. Giorgetti

    2015-01-01

    This work aims the hof morphological, physical, chemical, and mineralogical characteristics in Anglo Arabian horses, and Monterufoli ponies reared in Tuscany. 28 nail samples from wal and sole of hof were analysed. Al fet were healthy and wel conformed. The hof of Monterufoli Pony was more cylindrical, and the Anglo Arabian hof was harder (H 12.8±4.9, and H 19.4±2.7 in sole and in wal respectively). The percentage of dry mater (83.03±0.67) was greater in Anglo-Arabian hof, w...

  14. A review of contemporary patterns of endemism for shallow water reef fauna in the Red Sea

    KAUST Repository

    DiBattista, Joseph

    2015-11-03

    Aim The Red Sea is characterised by a unique fauna and historical periods of desiccation, hypersalinity and intermittent isolation. The origin and contemporary composition of reef-associated taxa in this region can illuminate biogeographical principles about vicariance and the establishment (or local extirpation) of existing species. Here we aim to: (1) outline the distribution of shallow water fauna between the Red Sea and adjacent regions, (2) explore mechanisms for maintaining these distributions and (3) propose hypotheses to test these mechanisms. Location Red Sea, Gulf of Aden, Arabian Sea, Arabian Gulf and Indian Ocean. Methods Updated checklists for scleractinian corals, fishes and non-coral invertebrates were used to determine species richness in the Red Sea and the rest of the Arabian Peninsula and assess levels of endemism. Fine-scale diversity and abundance of reef fishes within the Red Sea were explored using ecological survey data. Results Within the Red Sea, we recorded 346 zooxanthellate and azooxanthellate scleractinian coral species of which 19 are endemic (5.5%). Currently 635 species of polychaetes, 211 echinoderms and 79 ascidians have been documented, with endemism rates of 12.6%, 8.1% and 16.5% respectively. A preliminary compilation of 231 species of crustaceans and 137 species of molluscs include 10.0% and 6.6% endemism respectively. We documented 1071 shallow fish species, with 12.9% endemic in the entire Red Sea and 14.1% endemic in the Red Sea and Gulf of Aden. Based on ecological survey data of endemic fishes, there were no major changes in species richness or abundance across 1100 km of Saudi Arabian coastline. Main conclusions The Red Sea biota appears resilient to major environmental fluctuations and is characterized by high rates of endemism with variable degrees of incursion into the Gulf of Aden. The nearby Omani and Arabian Gulfs also have variable environments and high levels of endemism, but these are not consistently distinct

  15. Decadal stability of Red Sea mangroves

    Science.gov (United States)

    Almahasheer, Hanan; Aljowair, Abdulaziz; Duarte, Carlos M.; Irigoien, Xabier

    2016-02-01

    Across the Earth, mangroves play an important role in coastal protection, both as nurseries and carbon sinks. However, due to various human and environmental impacts, the coverage of mangroves is declining on a global scale. The Red Sea is in the northern-most area of the distribution range of mangroves. Little is known about the surface covered by mangroves at this northern limit or about the changes experienced by Red Sea mangroves. We sought to study changes in the coverage of Red Sea mangroves by using multi-temporal Landsat data (1972, 2000 and 2013). Interestingly, our results show that there has been no decline in mangrove stands in the Red Sea but rather a slight increase. The area covered by mangroves is about 69 Km2 along the African shore and 51 Km2 along the Arabian Peninsula shore. From 1972 to 2013, the area covered by mangroves increased by about 0.29% y-1. We conclude that the trend exhibited by Red Sea mangroves departs from the general global decline of mangroves. Along the Red Sea, mangroves expanded by 12% over the 41 years from 1972 to 2013. Losses to Red Sea mangroves, mostly due to coastal development, have been compensated by afforestation projects.

  16. Decadal Stability of Red Sea Mangroves

    KAUST Repository

    Almahasheer, Hanan

    2015-12-15

    Across the Earth, mangroves play an important role in coastal protection, both as nurseries and carbon sinks. However, due to various human and environmental impacts, the coverage of mangroves is declining on a global scale. The Red Sea is in the northern-most area of the distribution range of mangroves. Little is known about the surface covered by mangroves at this northern limit or about the changes experienced by Red Sea mangroves. We sought to study changes in the coverage of Red Sea mangroves by using multi-temporal Landsat data (1972, 2000 and 2013). Interestingly, our results show that there has been no decline in mangrove stands in the Red Sea but rather a slight increase. The area covered by mangroves is about 69 Km2 along the African shore and 51 Km2 along the Arabian Peninsula shore. From 1972 to 2013, the area covered by mangroves increased by about 0.29% y-1. We conclude that the trend exhibited by Red Sea mangroves departs from the general global decline of mangroves. Along the Red Sea, mangroves expanded by 12% over the 41 years from 1972 to 2013. Losses to Red Sea mangroves, mostly due to coastal development, have been compensated by afforestation projects.

  17. Map Service Showing Geology and Geologic Provinces of the Arabian Peninsula

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The geology data set for this map includes arcs, polygons, and labels that outline and describe the general geologic age and type of bedrock of the Arabian...

  18. Bedrock geology of the Arabian Peninsula and selected adjacent areas (geo2bg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The data set for this coverage includes arcs, polygons, and polygon labels that outline and describe the general geologic age and type of bedrock of the Arabian...

  19. Target revenue theory and Saudi Arabian oil policy

    International Nuclear Information System (INIS)

    Shifts in Saudi Arabian oil policy are explained by using data covering public revenues and expenditures plus the balance of payments. It is concluded that, according to the target revenue theory, Saudi Arabia only for a very short time after the first and second oil crises was on the backward sloping part of the supply curve. Perhaps Saudi Arabia cut oil production during the two oil crises because it wanted big oil price increases to prevent budget cuts. In any case, it started to increase oil production in the middle of 1985 when its economy was in great imbalance. Furthermore, calculations for the period 1989-2000 reveal that Saudi Arabia will probably face economic problems in the 1990s so that it will not again be OPEC's swing producer. On the contrary, Saudi Arabia will probably increase its share of OPEC's oil production in the 1990s. (author)

  20. Coral-associated Actinobacteria from the Arabian Gulf: diversity, abundance and biotechnological potentials

    OpenAIRE

    Huda Mahmoud Mahmoud; Aisha Ahmad Kalendar

    2016-01-01

    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...