Northern Arabian Gulf Research Articles

Long-term NDVI and recent vegetation cover profiles of major offshore island nesting sites of sea turtles in Saudi waters of the northern Arabian Gulf

Abstract Vegetation is an important ecological component of offshore islands in the Arabian Gulf (AG), which maintains long-term resilience of these islands. This is achieved by influencing sediment retention and moisture acquisition via condensation during periods of high humidity and by providing a variety of microhabitats for island fauna. The resilience of offshore islands’ ecosystems in the Saudi waters is important because they host the largest number of nesting hawksbill and green turtles in the AG. This study defines the characteristics and the long-term trends in vegetation cover of the offshore islands used by sea turtles as nesting grounds in the northern AG. To establish a ground-validated baseline for vegetation profiles, a 50 m × 50 m grid system is developed on Karan and Jana islands (Is.) with photo-quadrats taken at each grid intersection. The 1,317 and 444 photo-quadrats, for Karan and Jana Is., respectively, were analyzed for maximum plant height and percent cover of living (green) plants, dead plants, and bare sand. Landsat 7 and 8 satellite top-of-atmosphere reflectance images were used to calculate the Normalized Difference Vegetation Index (NDVI) from 1999 through 2018 to analyze the long-term vegetation profiles of the islands. Monthly rainfall data from five meteorological stations along the Eastern Province of Saudi Arabia and Oceanic Nino Index (ONI) are presented to provide a context of the long-term NDVI time series variability. The ground-validated vegetation profiles provided baseline data during the onset of summer in 2017 and revealed differences in maximum plant height and the extent of living, dead vegetation and sand cover on Jana Is. (28.3 cm, 19.9%, 63.3%, and 16.8%) and Karan Is. (21.7 cm, 20.6%, 48.7%, and 30.7%), respectively. The NDVI data for both islands are grouped into three periods, namely: 2001–2007 - high winter, low summer; 2008–2013 – low winter, low summer; 2014–2018 – irregular high/low winter, low summer. The long-term trend showed a slightly decreasing NDVI when compared in the context of the high NDVI measured for the two islands during the early 2000 s, particularly during the winter time. An extended reduction in winter NDVI was recorded for six years from 2008 to 2013, which coincided with reduced rainfall in the region and prolonged La Nina. Five extreme dips in winter NDVI values coincided with strong (2000, 2008, and 2011) and moderate (2012 and 2018) La Nina events. Long-term vegetation profiles of the offshore islands seemed to be tightly coupled with long-term rainfall patterns.

Neap-spring variability of tidal dynamics in the Northern Arabian Gulf

Small-scale (periods < 24 h and horizontal length < 10 km) hydrodynamics are significantly influenced by tides in the Northern Arabian Gulf (NAG). Here we characterize, for the first time, the neap-spring variability of tidal currents and mixing in the NAG from field observations. During the experiment between 14–28 July 2017, measurements in the near bottom layer (~1.5–6.5 m above bottom) show: (1) semi-diurnal horizontal velocities induced by tides, with a maximum horizontal speed of ~0.5 m/s; (2) quarter-diurnal cycles in turbulent kinetic energy (TKE) dissipation rates, with inequalities between the daily two floods and two ebbs; (3) well-correlated relations between turbulent diffusivity and gradient Richardson number. Both current velocities and mixing intensity near the bottom increased from neap to spring tides: the mean horizontal speeds increased from 0.18 to 0.26 m/s; the mean TKE dissipation rates increased from 2.2 × 10-7 to 5.5 × 10-7 W/kg and the mean stratification decreased from 2.1 × 10-5 to 5.5 × 10-6 s-2. Thus, the enhanced near bottom turbulent mixing is likely to contribute more significantly to the vertical transports of nutrients and sediments during spring tides in this region. The mean tidal power input (2.6 × 10-2 W/m2), was found to be one order of magnitude larger than the mean wind power input (1.1 × 10-3 W/m2) with ~39% of the tidal energy being dissipated locally by turbulent mixing near the bottom.

Internal Waves on the Continental Shelf of the Northwestern Arabian Gulf

The fluxes and turbulent mixing supported by internal waves (IWs) play a major role in transporting nutrients, affecting biological productivity and water-borne constituents such as contaminants and sediments. To better understand IWs on the continental shelf of the northwestern Arabian Gulf, off the coast of Kuwait, we conducted a study to examine the characteristics of these waves, and the associated energy cascade from IWs to turbulence. The study was conducted during midsummer (15 to 27 July, 2017), collected spatial transects and time series measurements at five moorings. Continuous turbulence profiles were taken at four locations in the vicinity of the moorings. Measurements of temperature, salinity, currents, turbidity, chlorophyll a and turbulence reveal that IW activity was consistent with the diurnal and semidiurnal tidal cycles. Based on cross-shore tracking of the IWs, we estimated that these waves propagated towards the coast at an average speed of 0.31 m/s, with amplitudes ranging from 7 to 9 m and generating intense mixing (> 10^-7 W/kg). In addition, we examined nighttime convective conditions driven by surface buoyancy flux which were estimated to contribute up to 70% of the turbulence kinetic energy (TKE) production. The results presented here shed new light on IW characteristics in the Northern Arabian Gulf, and offer the first detailed study of these waves in this region.

Physical response of the Northern Arabian Gulf to winter Shamals

Abstract Winter Shamals (strong northwesterly winds) are unique surface meteorological phenomena in the Northern Arabian Gulf (NAG). Here we report results from the first observational study designed to investigate the effects of winter Shamals on the hydrodynamics in the NAG. During the Shamal event of 24–26 March 2013, surface wind stress was observed to increase from 0.01 to 0.11 N/m2 and was followed by a decrease in relative humidity from 66.6 to 47.2%. The increase in wind speed and decrease in humidity resulted in a sixfold increase in latent heat loss (from 27.9 to 182.9 W/m2) at the air-sea interface. Such Shamal events were found to affect the hydrodynamics in four aspects: 1. increase of mean surface wave heights and periods, which are fetch limited, from 0.4 to 0.7 m and from 2.8 to 3.8 s, respectively; 2. residual (after removal of tides) surface elevation decrease of 0.6 m and change of residual cross-shore and along-shore velocity fields; 3. Significant increase in turbulent mixing as exemplified by a fivefold increase in mean turbulence kinetic energy dissipation rates from 2.3 × 10−7 to 1.2 × 10−6 W/kg; 4. An almost complete homogenization of the thermal structure.

Numerical Prediction of Background Buildup of Salinity Due to Desalination Brine Discharges into the Northern Arabian Gulf

Brine discharges from desalination plants into low-flushing water bodies are challenging from the point of view of dilution, because of the possibility of background buildup effects that decrease the overall achievable dilution. To illustrate the background buildup effect, this paper uses the Arabian (Persian) Gulf, a shallow, reverse tidal estuary with only one outlet available for exchange flow. While desalination does not significantly affect the long-term average Gulf-wide salinity, due to the mitigating effect of the Indian Ocean Surface Water inflow, its resulting elevated salinities, as well as elevated concentrations of possible contaminants (such as heavy metals and organophosphates), can affect marine environments on a local and regional scale. To analyze the potential effect of background salinity buildup on dilutions achievable from discharge locations in the northern Gulf, a 3-dimensional hydrodynamic model (Delft3D) was used to simulate brine discharges from a single hypothetical source location along the Kuwaiti shoreline, about 900 km from the Strait of Hormuz. Using nested grids with a horizontal resolution, comparable to a local tidal excursion (250 m), far field dilutions of about 28 were computed for this discharge location. With this far field dilution, to achieve a total dilution of 20, the near field dilution (achievable using a submerged diffuser) would need to be increased to approximately 70. Conversely, the background build-up means that a near field dilution of 20 yields a total dilution of only about 12.

The use of NDVI and SPI values in the study of the Drought coefficient of Northern Arabian Gulf region

The study was conducted in the northern Arabian Gulf region using monthly rainfall data for the period 2003-2010 to calculate the SPI and a series of annual MODIS images for April of the same year for the calculation of NDVI. Changes in NDVI values were associated with changes in SPI values. The statistical study confirmed a strong and significant correlation between the SPI and NDVI indices at all stations and the highest value was recorded at Boubyan station (0.91). The values of NDVI in the study stations fluctuated with the changes in the annual intervals. The results also indicated the relationship strength and significant between rainfall and the NDVI index and the highest correlation strength at Abadan station (0.88). Based on the results of drought severity classification based on SPI values, the results showed that the study area was characterized by severe drought at most stations and most of the study period, especially in 2007 and 2008, and the lowest in 2003. The results of the study demonstrate the need to use this tool (NDVI) in relation to the SPI index to identify problem areas and thus formulate practical management decisions.

Life history traits of the narrow-barred Spanish mackerel (Scomberemorus commerson) across jurisdictions of the southeast Arabian Peninsula: Implications for regional management policies

The narrow-barred Spanish mackerel (Scomberomorus commerson) is a large neritic predatory fish targeted by several thousand artisanal boats across eight jurisdictions in the Arabian Gulf, Gulf of Oman, and Arabian Sea. First steps have been taken for a regional management of the stock across some of these jurisdictions. However, although the drive for regional management may be justified on the grounds of probable transborder population processes, it may err by ignoring smaller spatial scales in the structuring of stocks that function as meta-populations. We carried out a comparative analysis of life history traits of the narrow-barred Spanish mackerel using newly collected data as well as published data encompassing a region from the northern Arabian Gulf to the eastern Arabian Sea. We obtained substantial differences in somatic growth and reproduction processes while rates of natural mortality were homogeneous. In addition we show differences in length composition of the catch reflecting different levels of exploitation. Our results imply that management should be conducted primarily at the level of each national jurisdiction while regional-wide initiatives could be useful to resolve scientific issues about population structure.

Perspective and Prospect of Tidal Electricity Generation in Iraq

or a long time, Iraq has been suffering from environmental pollution and electricity crisis. Therefore, tidal energy is one of the best renewable sources should be used to solve together the environmental pollution and electricity crisis. Tidal energy is usually available in coastal areas. Southern of Iraq has coastal areas in Basra Governorate on the northern Arabian Gulf. Therefore, this study has been investigated the possibility of establishing tidal power stations in two locations in Basra, Um Qasr and Al-Faw. In the case of the construction of a 4km2 tidal barrage in Um Qasr, the electricity generated was 98.85MW and 197.69MW to meet the demand for electricity in Basra by 6.59% and 13.18% in the case of one-way and two-way generation, respectively. While in case of construction of a 4km2 tidal lagoon in Al-Faw, the electricity generated was 31.37MW and 62.73MW to meet the demand for electricity in Basra by 2.09% and 4.18% in the case of one-way and two-way generation, respectively. So, this study clearly shows that tidal energy can contribute significantly to relief the electricity crisis in Basra Governorate.

210Po concentration in selected calanoid copepods in the northern Arabian Gulf

Copepods are the most abundant metazoans, forming a vital food chain link between the primary producers the phytoplankton and fish. This study presents baseline information on the concentration of 210Po among calanoid copepods isolated from the Kuwait marine area. The concentration of 210Po in six species of copepod, including Subeucalanus flemingeri, Parvocalanus crassirostis, Acartia pacifica, Calanopia elliptica, Acrocalanus gibber, and Euterpina acutifrons were 151.3–158.8 Bq kg−1 wwt, 121.1–129.5 Bq kg−1 wwt, 51.23–54.91 Bq kg−1 wwt, 38.88–40.09 Bq kg−1 wwt, 38.07–38.29 Bq kg−1 wwt, and 33.46–36.50 Bq kg−1 wwt, respectively.The 210Po concentration in seawater shows a seasonal variation, with a higher concentration range of 0.58–0.70 mBq L−1 during summer and autumn, while a lower concentration is found (0.30–0.38 mBq L−1) during winter and spring. The concentration factor among the copepods varies between 8 ∗ 104 and 5 ∗ 105 that is an order of magnitude higher than the diatoms and dinoflagellates.

210Po concentration in selected diatoms and dinoflagellates in the northern Arabian Gulf

Marine phytoplankton is a primary producer in the ocean that forms the base of the marine food web and supports the pelagic food chain. The two dominant groups of phytoplankton observed in northern Gulf waters are diatoms and dinoflagellates. The diatoms outnumber dinoflagellates in the Gulf waters. This study presents baseline information on the concentration of 210Po among selected phytoplankton in the northern Gulf. The concentration among diatoms varies between 6.99 and 11.4 Bq kg−1 wwt, whereas a higher concentration range of 8.51–15.41 Bq kg−1 wwt was observed among dinoflagellates. The diatoms analyzed includes Thalassiosira spp. – 10.2–11.4 Bq kg−1 wwt; Chaetoceros spp. – 6.99–7.14 Bq kg−1 wwt; Rhizosolenia spp. – 9.12–9.95 Bq kg−1 wwt. The analyzed dinoflagellate genera include Gymnodinium spp. – 8.51–8.78 Bq kg−1 wwt; Noctiluca spp. – 15.2–15.4 Bq kg−1 wwt; and Karenia spp. – 14.1–14.9 Bq kg−1 wwt. The 210Po concentration in seawater shows a seasonal variation, with a higher concentration range of 0.70 and 0.58 mBq L−1 during summer and autumn, whereas a lower range in concentration of 0.38 and 0.30 mBq L−1 occurring during winter and spring. The resultant computed concentration factors vary between 2 ∗ 104–5 ∗ 104 demonstrating a significant 210Po enrichment in the base of the pelagic food chain.

High total organic carbon in surface waters of the northern Arabian Gulf: Implications for the oxygen minimum zone of the Arabian Sea

Measurements of total organic carbon (TOC) for two years in Kuwaiti waters showed high TOC levels (101.0–318.4, mean 161.2 μM) with maximal concentrations occurring within the polluted Kuwait Bay and decreasing offshore, indicating substantial anthropogenic component. Analysis of winter-time data revealed a large increase in density over the past four decades due to decrease in Shatt Al-Arab runoff, implying that the dissolved/suspended organic matter in surface waters of the northern Gulf could be quickly injected into the Gulf Deep Water (GDW). Our measurements together with an analysis of previously collected/published data suggest that the recent summer-time declining trend in oxygen in the GDW might be related to eutrophication. Higher preformed TOC and lower preformed dissolved oxygen contents of the high-salinity water mass that flows out of the Gulf and ventilates the mesopelagic oxygen minimum zone (OMZ) of the Northwestern Indian Ocean may cause expansion/intensification of the regional OMZ.

Coral nursery and transplantation of the staghorn coral, Acropora downingi in Sabah Al-Ahmad Sea City, Kuwait, Arabian Gulf

The present work describes the first attempt at cultivating corals in the northern Arabian Gulf where seawater temperature ranges from 13 to 33°C and salinity exceeds 40 psu, exceeding normal letha...

Phage and Nucleocytoplasmic Large Viral Sequences Dominate Coral Viromes from the Arabian Gulf.

Corals that naturally thrive under extreme conditions are gaining increasing attention due to their importance as living models to understand the impact of global warming on world corals. Here, we present the first metagenomic study of viral communities in corals thriving in a thermally variable water body in which the temperature fluctuates between 11 and 39°C in different seasons. The viral assemblages of two of the most abundant massive (Porites harrisoni) and branching (Acropora downingi) corals in offshore and inshore reef systems in the northern Arabian Gulf were investigated. Samples were collected from five reef systems during summer, autumn and winter of 2011/2012. The two coral viromes contain 12 viral families, including 10 dsDNA viral families [Siphoviridae, Podoviridae, Myoviridae, Phycodnaviridae, Baculoviridae, Herpesviridae, Adenoviridae, Alloherpesviridae, Mimiviridae and one unclassified family], one-ssDNA viral family (Microviridae) and one RNA viral family (Retroviridae). Overall, sequences significantly similar to Podoviridae were the most abundant in the P. harrisoni and A. downingi viromes. Various morphological types of virus-like particles (VLPs) were confirmed in the healthy coral tissue by transmission electron microscopy, including large tailless VLPs and electron-dense core VLPs. Tailed bacteriophages were isolated from coral tissue using a plaque assay. Higher functional gene diversity was recorded in A. downingi than in P. harrisoni, and comparative metagenomics revealed that the Gulf viral assemblages are functionally distinct from Pacific Ocean coral viral communities.

Naturally Occurring Radioactive Material (NORM) in seawater of the northern Arabian Gulf – Baseline measurements

This study focuses on creating baseline for 238U, 235U, 234U, 210Pb, 210Po and 40K concentrations in the northern Arabian Gulf. The respective concentration ranges were 0.047–0.050, 0.00186–0.00198, 0.054–0.057, 0.00085–0.00092, 0.00051–0.00062 and 18.6–19.1Bql−1. These results suggest that the levels are generally comparable to other marine waters in the northern hemisphere. There were no hot spots observed from oil and gas industry. These data will serve as a baseline to gauge possible future inputs of TENORMs in the northern Gulf. A positive and linear correlation was observed between 238,234U, 40K isotopes and seawater salinity. The results also suggest significant fractionation between 210Po and 210Pb, attributed to rapid removal of 210Po by biota compared to 210Pb. The mean residence time for 210Po in the study area was 371days. The 234U/238U and 238U/235U activity ratios in seawater samples vary between 1.14–1.15, and 0.038–0.040. The 234U/238U and 235U/238U ratio is similar to the expected composition of seawater (1.148±0.002) and 0.0462.

Stress-dependent consolidation characteristics of marine clay in the Northern Arabian Gulf

Abstract The main objective of this paper is to study the variation of the coefficient of consolidation ( Cv ) with stress level for the marine clay in the Northern Arabian Gulf. Undisturbed samples were collected from three sites and laboratory-tested using the conventional Oedometer test. The variation of permeability with applied stress was expressed in terms of the Permeability Change Index. The Coefficient of Consolidation Change Index was introduced as a new parameter to quantify the change in Cv with stress level. Region-specific correlations were developed between these two indices and the Liquid Limit. The uncertainty in these correlations was quantified using statistical techniques and was found to be higher in the case of Cv . Accordingly, risk-based correction factors were introduced based on the target probability of unsatisfactory performance. Finally, a simplified methodology was proposed to estimate the stress-dependent Cv in the absence of site-specific consolidation tests.

Plutonium and cesium baseline concentrations in seawater from northern Arabian Gulf

The Arabian Gulf is a semi-enclosed water body that has witnessed accelerated anthropogenic activity, in terms of commissioning of nuclear power plants, desalination facilities, oil refineries and extensive coastal development. Furthermore, three wars during the past three decades is a potential worry. This study presents the first plutonium baseline in seawater from the Northern Arabian Gulf. The 239+240Pu concentrations in seawater vary, between 2.9 and 4.9mBqm−3, a range that is comparable to other water masses at this latitude. The 238Pu ranged between 0.04 and 0.05mBqm−3 and the 137Cs concentration between 1.04 and 1.18Bqm−3. The ratio of 238Pu/239+240Pu at all eight sampling stations was 0.01, while the ratio of 239+240Pu/137Cs varied between 0.01 and 0.02. The presence of 137Cs and 239+240Pu in seawater from this region can mainly be attributed to the global atmospheric deposition and fluvial transport. The seawater concentration of 239+240Pu is five order of magnitude lower than bottom sediments in the area.

A new genus and species of galeommatoid bivalve (Mollusca: Bivalvia: Montacutidae) from Kuwait Bay, Arabian Gulf

Larissamya comta gen. n., sp. n., is described from Kuwait Bay, northern Arabian Gulf. The hinge is identical to that seen in Kurtiella and Montacutona but the spined dorsal margin is unique. Anatomically Larissamya differs from Kurtiella in retaining both gill demibranchs and from both Kurtiella and Montacutona in having greatly unequal adductor muscles. Co-occurrence and density data suggest that L. comta may be associated with the ophuroid Amphiura fasciata.http://www.zoobank.org/urn:lsid:zoobank.org:pub:ECCB79FC-6EB2-4693-B1D4A014CB17C6D8

Residence and transport time scales associated with Shatt Al-Arab discharges under various hydrological conditions estimated using a numerical model

Over the last several decades, concerns in the Northwest Arabian Gulf have risen regarding water quality and ecological conditions, particularly near Kuwait. This interest is mainly attributed to the reduction of freshwater discharge and its associated constituents from the Shatt Al Arab as a result of human activities at diverse scales. From the hydrological perspective, the reduction has also resulted in alteration to the dynamic regime and related residence time and transport conditions. Using a previously well-validated three-dimensional numerical model of the Northern Arabian Gulf (NAG) (Alosairi and Pokavanich, 2017), the residence and transport conditions of numerical tracers have been assessed through a series of numerical tests. The results indicate that density-driven circulations have played a key role in reducing the residence time in the Northwest Gulf by approximately 15% to 20% compared to tidal forces only. The transport conditions correlated well with the Shatt Al Arab discharges, but they were only significant along the Kuwait coast due to counter-clockwise circulations and alongshore currents. Arrival times and mixing processes varied reasonably with the Shatt Al Arab discharges; the results exhibited the enhancement in mixing and transport with increases in discharge. Residence times in the NAG associated with Shatt Al Arab discharge displayed spatial variations, particularly in Kuwait Bay, where the residence time increased by 60days during low discharge compared to high discharge.

210Po bioaccumulation and trophic transfer in marine food chains in the northern Arabian Gulf

The tendency of 210Po to concentrate in body tissue poses a serious concern of radiological safety. This study compiles available information and presents recent 210Po data for the marine food web in the northern Gulf waters. Since 210Po is concentrated in marine biota, a large number of samples of various marine organisms covering several trophic levels, from microalgae to sharks, were analyzed. 210Po was found to be highly concentrated in several marine species with the highest 210Po concentrations found in yellowfin tuna, i.e. 37.3–44.9, 451–548, and 1511–1693 Bq kg−1 wwt in muscle, digestive system and liver, respectively. In most dissected fish samples, 210Po showed increasing concentrations in the following order: edible tissue, gills, digestive system, liver and fecal matter. Fish feces had 210Po concentrations several orders of magnitude higher than that in seawater, fish muscle, and the fishes' ingested food. The high 210Po concentration in fish fecal matter suggests that the bulk of 210Po content in fish is eventually excreted back into the environment as fecal pellets. In most fish high concentrations were noted in liver, with the highest 210Po concentration recorded in yellowfin tuna liver. Moreover, 210Po concentration in the soft tissue of tunicate and bryozoan samples were 872–1012 and 402–527 Bq kg−1 wwt, respectively, far higher than that in fish muscle (0.04–44.9 Bq kg−1 wwt). It was observed that the maximum 210Po concentration in edible fish tissue among the fish in trophic level 2 was an order of magnitude lower than those in trophic level 3 and two orders of magnitude lower compared to fish in trophic level 4. The highest concentrations in the muscle tissue were observed in the following order: tunicate > bryozoan > mollusc > crustacean > algae > fish. Among all the biota analyzed, the highest overall concentration of 210Po was noted in yellowfin tuna (Thunnus albacores) indicating a potential biomagnification of 210Po in this particular top predator species. In general, 210Po concentrations found in the commercially important fish from Kuwaiti waters were comparable to levels that have been reported for similar fish species from several other marine areas worldwide.

Spatial and temporal distributions of polycyclic aromatic hydrocarbons in the Northern Arabian Gulf sediments

Surficial sediment samples were collected from 25 locations within Kuwait Bay and outside the Bay, in the Northwestern Arabian Gulf, to access recent polycyclic aromatic hydrocarbon pollution in Kuwait. Time trends in the depositional history of PAHs to this portion of the Arabian Gulf was reconstructed from the analysis of a dated sediment core. Intersite differences in concentration exist although these differences were not statistically significant (p=0.08). However, organic carbon normalized concentrations within Kuwait Bay were 4 times higher than the average concentrations outside the Bay and were shown to be statistically significant (p<0.001). The sedimentary record showed that ΣPAHs concentration fluctuated between 12 and 25ngg−1 before 1970. Concentrations then increased sharply to a maximum of 45ngg−1 around the late 1970s and early 1980s followed by an exponential decrease in concentration to pre-1970 “background” concentrations of between 12 and 25ngg−1.