Northeastern Arabian Peninsula Research Articles

The Barremian–lower Aptian of NE Arabia: The Kharaib and Shu'aiba formations in Wadi Rahabah and Wadi Kebdah, Ras Al Khaimah, U.A.E.

We present a high-resolution record of carbonate depositional facies, biostratigraphy, stable-isotope and elemental geochemistry of the Kharaib and Shu'aiba formations exposed in Ras Al Khaimah, northern UAE. This is the first comprehensive study of these deposits in the northeastern Arabian Peninsula, which have previously been studied extensively in Abu Dhabi, Oman, NE Saudi Arabia, and southwestern Iran, and represents the most detailed biostratigraphic and chemostratigraphic record currently available from a continuous outcrop section of the Arabian Plate. The Barremian–Aptian boundary was approximated based on orbitolinid biostratigraphy, while a subdivision of the Barremain was not possible. There is no biostratigraphic evidence that the Shu'aiba Formation in the section studied ranges into the upper Aptian. Previously well-established depositional sequences of the Barremian–lower Aptian of the Arabian Plate are discussed in the context of carbonate textures, siliciclastic influx, and biotic assemblages. There is a general trend of decreasing siliciclastic components during the Barremian and earliest Aptian, and peaks in siliciclastic influx indicate episodes of maximum accommodation. Palaeogeographic implications of our data for the distribution of intrashelf basins and their connection to Neotethys are discussed. The negative carbon-isotope excursion that globally marks the onset of OAE1a is not evident in our dataset, while the positive excursion at the end of OAE1a is present in the late early Aptian. A comparison of carbon-isotope records across the early Aptian of the Arabian Plate highlights issues of correlations that are predominantly based on chemostratography in diagenetically altered platform carbonates.

Long-term changes in the Arabian Peninsula rainfall and their relationship with the ENSO signals in the tropical Indo-Pacific

We investigate long-term changes in winter rainfall patterns across the Arabian Peninsula (AP) through an analysis of the Climate Research Unit (CRU) gridded rainfall dataset, and long-term rainfall measurements collected at 39 stations distributed across the AP over the period 1951–2010. We reveal a long-term increase in winter rainfall of about 25–30% over the eastern AP and a long-term decrease of about 10–20% in the southern and northeastern AP. A partial correlation analysis suggests that canonical El Niños are associated with significant negative winter rainfall anomalies in the southern and southwest AP during the 1951–1980 period. However, the extent of the El Niño-induced rainfall deficit decreased in subsequent decades. In fact, a significant above-average rainfall occurs in recent decades over Ethiopia, southwest Yemen and central AP during canonical El Niños. Furthermore, positive phases of the Indian Ocean basin mode (IOBM), which lags the canonical ENSO signal by 3–4 months, are linked with significant below-average winter rainfall over the central and northern AP, but only until the 1970 s. We investigated the teleconnections between the variability of AP winter rainfall and various atmospheric parameters from the European Centre for Medium Range Weather Forecasting (ECMWF) twentieth century (ERA-20C) reanalysis. Notably, sub-tropical westerly jet (STJ) shifted southward and intensified over the AP during recent decades. This shift of the STJ favoured an increase in the frequent passage of transients, which contributed to increased winter rainfall over AP. These events anomalously strengthen the upper level westerlies during El Niño Modokis, adding to the recently-strengthened STJ over the AP, thereby further intensifying the transient activity. This large-scale background change likely weakened the impact of canonical El Niño and the IOBM events.

Population genetic structure of a major reef-building coral species Acropora downingi in northeastern Arabian Peninsula

Current seawater temperatures around the northeastern Arabian Peninsula resemble future global forecasts as temperatures > 35 °C are commonly observed in summer. To provide a more fundamental aim of understanding the structure of wild populations in extreme environmental conditions, we conducted a population genetic study of a widespread, regional endemic table coral species, Acropora downingi, across the northeastern Arabian Peninsula. A total of 63 samples were collected in the southern Arabian/Persian Gulf (Abu Dhabi and Qatar) and the Sea of Oman (northeastern Oman). Using RAD-seq techniques, we described the population structure of A. downingi across the study area. Pairwise G’st and distance-based analyses using neutral markers displayed two distinct genetic clusters: one represented by Arabian/Persian Gulf individuals, and the other by Sea of Oman individuals. Nevertheless, a model-based method applied to the genetic data suggested a panmictic population encompassing both seas. Hypotheses to explain the distinctiveness of phylogeographic subregions in the northeastern Arabian Peninsula rely on either (1) bottleneck events due to successive mass coral bleaching, (2) recent founder effect, (3) ecological speciation due to the large spatial gradients in physical conditions, or (4) the combination of seascape features, ocean circulation and larval traits. Neutral markers indicated a slightly structured population of A. downingi, which exclude the ecological speciation hypothesis. Future studies across a broader range of organisms are required to furnish evidence for existing hypotheses explaining a population structure observed in the study area. Though this is the most thermally tolerant acroporid species worldwide, A. downingi corals in the Arabian/Persian Gulf have undergone major mortality events over the past three decades. Therefore, the present genetic study has important implications for understanding patterns and processes of differentiation in this group, whose populations may be pushed to extinction as the Arabian/Persian Gulf warms.

Morphology, vocalizations, and mitochondrial DNA suggest that the Graceful Prinia is two species

Abstract Prinias (Cisticolidae: Prinia) are resident warblers of open areas across Africa and Asia and include many polytypic species whose species limits have not been seriously reevaluated recently. Based on an integrative taxonomic analysis of morphology, song, and mitochondrial DNA (mtDNA), we suggest that 2 species should be recognized in the Graceful Prinia (Prinia gracilis) complex. In addition, our morphological analyses show the existence of a well-marked undescribed form in southeastern Somalia, which we name herein as a new subspecies. Prinia gracilis is a small, drab, long-tailed species with streaking above and plain pale underparts that has been suggested to fall into 2 groups: the southwestern nominate group (from Egypt to Oman) and the northeastern lepida group (from Turkey through India). However, the characters presented to justify this grouping are variable and show a mosaic pattern, and whether genetic and vocal differences exist is unknown. We found consistent between-group song differences, with the nominate group giving consistently longer inter-phrase intervals, whereas the members of the lepida group sing an essentially continuous reel. An mtDNA tree suggests a deep split between the nominate and lepida groups, with a coalescence time between these clades of ~ 2.2 million years ago. Vocal and mtDNA analyses provided evidence that the northeastern Arabian Peninsula taxon carpenteri belongs to the lepida group. We found that, of all the morphological characters proposed, only proportions and tail barring and spotting relatively consistently distinguish the 2 groups. However, these characters strongly suggest that the eastern Arabian Peninsula is populated by taxa of both the gracilis and lepida groups, in different areas, but we lack genetic and bioacoustic data to corroborate this. Although further study is needed in potential contact zones, we suggest that 2 species should be recognized in the P. gracilis complex, and we propose the retention of the English name Graceful Prinia for P. gracilis sensu stricto, while we suggest that P. lepida be known as Delicate Prinia.

Localized outbreaks of coral disease on Arabian reefs are linked to extreme temperatures and environmental stressors

The Arabian Peninsula borders the hottest reefs in the world, and corals living in these extreme environments can provide insight into the effects of warming on coral health and disease. Here, we examined coral reef health at 17 sites across three regions along the northeastern Arabian Peninsula (Persian Gulf, Strait of Hormuz and Oman Sea) representing a gradient of environmental conditions. The Persian Gulf has extreme seasonal fluctuations in temperature and chronic hypersalinity, whereas the other two regions experience more moderate conditions. Field surveys identified 13 coral diseases including tissue loss diseases of unknown etiology (white syndromes) in Porites, Platygyra, Dipsastraea, Cyphastrea, Acropora and Goniopora; growth anomalies in Porites, Platygyra and Dipsastraea; black band disease in Platygyra, Dipsastraea, Acropora, Echinopora and Pavona; bleached patches in Porites and Goniopora and a disease unique to this region, yellow-banded tissue loss in Porites. The most widespread diseases were Platygyra growth anomalies (52.9% of all surveys), Acropora white syndrome (47.1%) and Porites bleached patches (35.3%). We found a number of diseases not yet reported in this region and found differential disease susceptibility among coral taxa. Disease prevalence was higher on reefs within the Persian Gulf (avg. 2.05%) as compared to reefs within the Strait of Hormuz (0.46%) or Oman Sea (0.25%). A high number of localized disease outbreaks (8 of 17 sites) were found, especially within the Persian Gulf (5 of 8 sites). Across all regions, the majority of variation in disease prevalence (82.2%) was associated with the extreme temperature range experienced by these corals combined with measures of organic pollution and proximity to shore. Thermal stress is known to drive a number of coral diseases, and thus, this region provides a platform to study disease at the edge of corals’ thermal range.

The Jal Az-Zor escarpment as a product of complex duplex folding and strike-slip tectonics; A new study in Kuwait, northeastern Arabian Peninsula

The origin of Jal Az-Zor escarpment has been equivocal due to limited exposure and subsurface data. The escarpment was assumed to be a result of differential weathering and erosion. Most recently mapping of basement lineaments suggested a deep fault system as a most likely cause. The aim of this article is to use shallow seismic data acquired across various locations along the escarpment to investigate the underlying geology, structural elements and link these features to surface observations.To understand the near subsurface geology, post-stack time processing was applied to 2D seismic data acquired recently in the area. The objective was to focus on the shallow intervals, represented by the Rus, Dammam and Kuwait Formations. The analyses revealed a train of tight concentric folds that increase in stage development towards the escarpment in the Dammam Formation. The shallower Kuwait Formation shows early stages of fault propagation folding as a result of the Kuwait Arch uplift towards the south of the escarpment. We suggest that friction along the Dammam Formation upper contact detachment planes increased towards the south, thus promoting the propagation of the fold reaching the surface, resulting in the Jal Az-Zor escarpment that we see today. Structural kinematic analysis suggests that the Jal Az-Zor escarpment is also a principal displacement zone (PDZ) that is dominated by dextral strike-slip motion and exhibits a series of restraining bends, positive-flower structures, and a horsetail splay. 2D structural restoration and balancing suggest a total shortening magnitude of approximately 6.25 km. Considering the Arabian and Eurasian plates velocity vectors, along with the relatively large amount of shortening, this deformation initiated during the early Pleistocene (Calabrian). The presence of tight concentric and fault propagation folds combined with dextral strike kinematics introduce new complexities into the structural styles and assemblages of the area otherwise thought to follow the overall northern Arabian Peninsula tectonics.

Neogene to Quaternary uplift history along the passive margin of the northeastern Arabian Peninsula, eastern Al Hajar Mountains, Oman

AbstractThis work explores the uplift history of the best exposed marine terraces in the northeastern Arabian Peninsula (eastern Al Hajar Mountains). A multidisciplinary approach was employed, including a topographic survey,14C dating, thin section studies, and scanning electron microscopy analyses. Six distinctive marine terraces with widths ranging from tenth of meters to kilometers and elevations from 5 to ~400 m were studied. These terraces record an along-strike heterogeneous uplift history, while they show temporally variable uplift rates ranging between 0.9 to 6.7 mm/yr, which correlates well with other published uplift rates of marine terraces of the eastern Arabian Peninsula. We attribute the variable uplift along strike of the terraces, to a combination of uplift mechanisms: (1) during early to mid-Miocene along deep-rooted reverse faults that bound large crustal-scale blocks, (2) Pliocene or post-Pliocene uplift on the outer wall of the forebulge of the lower Arabian Plate as it bends to enter the Zagros-Makran subduction zone, and (3) a possible slowdown of subduction for the past ~40 ka.

Settlement Patterns of Corals and other Benthos on Reefs with Divergent Environments and Disturbances Histories around the Northeastern Arabian Peninsula

Larval supply is a principal factor determining the establishment, structure, and diversity of sessile benthic assemblages on coral reefs. Benthic reef communities in north-eastern Arabia have been subject to recurrent disturbances in recent years, and subsequent recovery will be, in part, driven by variation in the supply of available colonists. Using settlement tiles deployed seasonally over one year at eight sites encompassing three environmentally divergent regions (southern Arabian Gulf, the Musandam Peninsula in the Strait of Hormuz, and the Sea of Oman) we assessed spatial and seasonal variability in settlement of benthic reef organisms. There was strong spatial variation in composition of new colonists among regions, mainly driven by the high abundance of coralline algae in the Arabian Gulf, colonial ascidians on the Musandam Peninsula and barnacles in the Sea of Oman. Seasonal differences in composition of new colonists were less important than regional differences, with seasonal variation in settlement not consistent among regions. The number of corals settling to the tiles was low compared to those reported for other regions, with mean densities ranging from 0 corals m-2 yr-1 in the Sea of Oman to 30 (± 0.6 SE) and 38 (± 0.5 SE) in Musandam and the Arabian Gulf, respectively. Peak coral settlement abundance in the Gulf occurred in summer and autumn (5 – 8 spat m-2) and in Musandam in spring (7 spat m-2). This work provides the first record of large-scale spatial and seasonal patterns of settlement in north-eastern Arabia and provides valuable information on the supply of settlers available to recolonize heavily disturbed reefs in this region. The extremely low rates of coral settlement suggest that these marginal reefs are likely to be extremely slow to recover from ongoing and future disturbances.

A new species of the genus Philbyella China (Hemiptera, Auchenorrhyncha, Fulgoroidea: Nogodinidae) from the United Arab Emirates

Philbyella aculeata sp. n. is described from Fujairah Emirate (UAE) in the northeastern Arabian Peninsula. This species differs from the other members of the genus Philbyella China in the presence of a pair of spiniform triangular processes on the posterior margin of the male pygofer and in the style with a massive capitulum without the neck.

Corrosion performance of aluminium in atmospheric, underground and seawater splatter zone in the northeastern coast of Arabian Peninsula

PurposeThe purpose of this study was to determine the atmospheric corrosion behavior of aluminium (Al) exposed to the industrial and coastal environments of northeastern Arabian Peninsula for a period of 15 months.Design/methodology/approachThe samples were exposed under atmospheric, underground and splatter zone conditions at the coastal region. Soil, groundwater, seawater and air particulate samples obtained from the exposure site were analyzed. Secondary electron microscopy was used to identify and study the microstructural features of the corrosion products formed at the surface of the test coupons. The corrosion rates of the samples were determined by the weight loss method.FindingsThe results showed that Al exhibited a moderate corrosion rate despite high degree of variation in temperature and humidity and large concentrations of chloride and sulfate in this region. Splatter zone environment was the most corrosive because of high chloride concentrations in seawater and the alternating wetting–drying cycles.Originality/valueIn this paper, corrosion of Al was evaluated in atmospheric, soil and splatter zone conditions along the northeastern coast of Arabian Peninsula and was also compared with the results of the test reported for other international locations.

Twenty-year changes in coral near Muscat, Oman estimated from manta board tow observations

The coastline of Muscat, Oman, contains some of the most extensive and diverse coral reefs in the northeastern Arabian Peninsula. In the past two decades this region has been impacted by expanding coastal development, the largest cyclone ever recorded in the Arabian Sea, and a large-scale harmful algal bloom which resulted in mass mortality of reefs elsewhere in the Gulf of Oman. In 2012 we estimated live and dead coral using manta tow observations on 370 transects at 13 locations along the coastline and nearshore islands of Muscat Oman. We compared these estimates against observations made on 389 transects at the same 13 locations two decades earlier (1993–94) in order to determine long-term changes in benthos along the Muscat coast. Results were mapped and differences in categorical mean values for transect locations were statistically compared between survey years. Live hard and soft coral decreased over the past two decades at most survey sites, and decreases were significant at three exposed coastline sites and one semi-enclosed embayment. One sheltered embayment site showed a significant increase in live hard coral over the study period. Declines in live hard coral were associated with increases in dead coral framework at 8 of the 13 sites, but these changes were non-significant. We attribute these changes primarily to long-term effects of Cyclone Gonu, which struck the Oman coast in June 2007. The study results suggest that the manta tow method can be an effective way to detect long-term changes in coral and other benthic parameters over large areas, despite limitations on its precision.

Multiple environmental factors influence the spatial distribution and structure of reef communities in the northeastern Arabian Peninsula

Multivariate analysis revealed distinct sub-regional coral communities among the southern Persian Gulf, Strait of Hormuz, and Gulf of Oman. Differences in community structure among locations were associated with considerable spatial heterogeneity in oceanic conditions, and strong directional environmental gradients. Despite clear community differences, considerable changes to coral community structure have occurred throughout the northeastern Arabian Peninsula as compared with previous studies. The most dramatic of these are the apparent changes from Acropora dominated to poritid and faviid dominated communities, particularly in the southern Persian Gulf and Strait of Hormuz. Although temperature and salinity have previously been cited as the major environmental factors structuring coral communities around the region, additional environmental parameters, including chlorophyll-a, surface currents and winds are shown to be important in structuring reef communities throughout the northeastern Arabian Peninsula.

Biogeographic patterns of reef fish community structure in the northeastern Arabian Peninsula

AbstractBurt, J. A., Feary, D. A., Bauman, A. G., Usseglio, P., Cavalcante, G. H., and Sale, P. F. 2011. Biogeographic patterns of reef fish community structure in the northeastern Arabian Peninsula. – ICES Journal of Marine Science, 68: 1875–1883. This study provides the first large-scale comparison of reef-associated fish communities in the northeastern Arabian Peninsula, with 24 sites spanning >3000 km of coastline in the southern Persian Gulf, the western Gulf of Oman, and the northwestern Arabian Sea, each with its own unique environmental conditions. Multivariate analyses revealed three distinct community types that were represented mainly by sites within each major water body, with >70% dissimilarity in community structure between each. Persian Gulf communities had low species richness, abundance, and biomass of reef fish compared with the other subregions, with communities dominated by herbivores and generalist predators that had little association with live coral. Reef fish biomass in the Gulf of Oman and Arabian Sea was comparable, and communities were dominated by fish with moderate coral association. However, there were relatively more herbivores and larger fish in the Arabian Sea than in the Gulf of Oman, where communities were dominated by planktivores. Species richness was highest in the Arabian Sea when differences in abundance among regions were accounted for. The influence of distinct environmental and oceanographic conditions on reef fish community structure in each of these areas is discussed.

Comparative analysis of groundwater formation in arid and super-arid deserts (with examples from Central Asia and northeastern Arabian Peninsula)

Groundwater formation within arid and super-arid deserts is discussed through comparative analysis. Although fresh groundwater is being formed in both types of deserts, mainly from infiltrated surface runoff, in arid deserts, infiltration is currently taking place, whereas in super-arid areas, it occurred mainly in the Pleistocene pluvial epoch. Groundwater discharge conditions are also different. In arid deserts, the discharge occurs mainly through transpiration by phreatophytes, which form phyto-hydrogeological ecosystems where the dominant factor is an interaction between groundwater and vegetation, with transpiration reaching over hundreds of mm/year and the thickness of the groundwater evaporation zone extending over 10 m. Active subsurface water exchange does not favor the preservation of Pleistocene fossil groundwater. Super-arid deserts, however, have an extremely scarce vegetative cover (low, if any), physical evaporation, a thin zone of evaporation influence, and slow water outflow. Favorable conditions therefore exist for the preservation of relict low-mineralized waters. Furthermore, arid and super-arid deserts differ by types of groundwater accumulation and horizontal and vertical zonalities. In arid deserts, hydrogeological problems are connected with the anthropogenic influence upon groundwater, and with control on rational use of surface water and groundwater. In super-arid deserts, the basic problem is depletion of fossil groundwater.

00/01474 Solar-energy availability in the north-eastern Arabian peninsula

00/01474 Solar-energy availability in the north-eastern Arabian peninsula

Solar-energy availability in the north-eastern Arabian peninsula

The solar energy potential of north-east Saudi Arabia is investigated based on measurements of a complete year's data at a coastal location near Dhahran. High resolution, real time solar radiation data were collected and processed. Hourly, daily and monthly statistics of solar radiation were made from the 1 min averaged recorded values. Clearness index is discussed on the basis of hourly, daily and monthly averages. The variation of the diffuse fraction of total radiation is also determined and the results discussed.