Southern Arabian Peninsula Research Articles

Temporal and spatial diversification of the shrub Justicia areysiana Deflers (Acanthaceae) endemic to the monsoon affected coastal mountains of the southern Arabian Peninsula

Justicia areysiana Deflers (Acanthaceae) is an endemic shrub of the monsoon affected coastal mountains of the southern Arabian Peninsula with ballochorous seed dispersal. Its occurrence in a vegetation belt of relics of the (semi)-evergreen Afro-montane woodland characterised by Olea europaea subsp. cuspidata and Juniperus procera above an elevation of c. 750-800 m is strongly dependent on the activity of the Indian Ocean southwest monsoon. Therefore, the species offers a good model to study the palaeo-climate induced habitat fragmentation of the once continuous distribution range of the Afro-montane woodland belt on the southern Arabian Peninsula. Thirteen populations from the total distribution range of the species were analysed using AFLP fingerprinting and show a distinct geographic distribution pattern with a main split between eastern (Hawf Mountains/Dhofar) and western/central populations (Jabal Urays, Jabal Gedu, Kor Seiban). Our results on the genetic differentiation of populations clearly demonstrate the strong isolation among populations and confirm geographical patterns found in former studies based on chloroplast haplotypes. The dating of the main regional split between eastern and western/central populations based on nrDNA ITS sequence variation, is dated to 0.8–1.8 Myr before present. This indicates drastic habitat fragmentation processes during the Pleistocene which are compatible with periods of aridisation assumed for the African continent at around 1.7 Myr and 1.0 Myr before present.

Chloroplast DNA variation in the shrub Justicia areysiana (Acanthaceae) endemic to the monsoon affected coastal mountains of the southern Arabian Peninsula

The monsoon affected mountains of the southern Arabian Peninsula harbour in climatically favoured refugia vegetation elements of palaeo-African origin. To understand better the temporal and spatial differentiation of these refugia, chloroplast variation in Justicia areysiana Deflers (Acanthaceae), a shrub species endemic to the Yemeni and Omani mountains close to the Arabian Sea, was studied using PCR-RFLP and chloroplast microsatellite diversity. Eleven haplotypes were characterized and show a distinct geographical distribution pattern with a deep split between populations from south Yemeni fog oases and those from Hawf Mountains/Dhofar region in east Yemen and south Oman. Very limited haplotype diversity within populations (hS = 0.15) and a high level of population differentiation (GST = 0.81) demonstrate the strong genetic isolation of populations from each other. Past oscillations between humid and arid periods connected with glacial and interglacial episodes in the Pleistocene and Holocene are considered responsible for the observed patterns of genetic variation. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 148, 437–444.

Late Pleistocene eolian history of the Liwa region, Arabian Peninsula

The Liwa region of the United Arab Emirates is one of the most distinctive geomorphological features of the Rub Al Khali desert of southern Arabia. Characterized by a sharp crescentic boundary coincident with a N-S elevation drop of ∼65 m with the transverse ridges in Al Qâfa to the north, Liwa is an area of some of the world9s largest megabarchan dunes. Deep drilling of continuous cores has provided an opportunity to observe the internal structure and age of these two ergs. Subsurface stratigraphy is complex, reflecting rapid facies transitions between dune and interdune sub-environments. Most of the cored sediment is dominated by cross-bedded and structureless sand units of inferred eolian (transverse dune) depositional origin. A total of 56 optical ages for sand-sized quartz grains extracted from these cores provide a chronological framework for deposition of the late Quaternary ergs. A marine isotope stage (MIS) 5 erg is identified north of the Liwa crescent in the Al Qâfa region, which reaches vertical thicknesses >100 m. A MIS 1 erg in the form of megabarchan dunes is recorded south of the Liwa crescent. This was deposited on a pre–MIS 5 land surface, since ca. 6 ka, over a period of just a few thousand years. Contemporary bypassing of eolian sands via superimposed dunes in both Al Qâfa and Liwa appears to be in equilibrium with the current wind regime. A consideration of a variety of factors that control the availability, mobilization, and preservation of eolian sediments and resulting bedforms leads us to infer that the system is not sediment-supply or transport limited. Instead, the system is preservation limited, being controlled by a correlated combination of sea level and precipitation. Both of these factors are strongly linked to global climate variations in the eccentricity (ca. 100 ka) band. Paradoxically, the bulk of the preserved record of eolian activity in the southern Arabian Peninsula occurs within relatively humid interglacial phases rather than arid intervals. Evidence of eolian deposition during arid phases may not for the most part be preserved in large areas of the sand sea. Observed contrasts in the preserved record of eolian activity between Al Qâfa and Liwa, and the Wahiba Sand Sea, may in part relate to contrasting eolian bedform morphology.

Critical species of Odonata in northern Africa and the Arabian Peninsula

Abstract The region is broadly determined by desert, which forms a huge belt between the western Palaearctic and the Afrotropics. Fourteen out of the 125 odonate species recorded so far are endemics. There are two main centres of endemism in the region: the northern Maghreb and the southern Arabian Peninsula. Odonate habitats in the desert are especially endangered by dryness and pollution. Fourteen species - most of them endemics - are regarded as critical. Conservation measures are suggested.

Dust Storms in the Middle East: Sources of Origin and Their Temporal Characteristics

The spatial and temporal characteristics of dust storms in the Middle East were studied by an analysis of the visibility reduction in that region. Eight ‘three-hours’ mean values for each month for a period of 21 years (1973–1993) were used. Data were subjected to cluster analysis of their temporal behaviour. Four main regions were identified and mapped. Stations within each cluster (region) have a similar temporal behaviour different from the behaviour of stations out of that cluster. Sudan, Iraq, Saudi Arabia and the Persian Gulf, are the regions that reported the greatest occurrence of dust storms. Dust storms in Iran, north-eastern Iraq and Syria, the Persian Gulf and southern Arabian Peninsula are more frequent in summer. In western Iraq and Syria, Jordan, Lebanon, northern Israel, northern Arabian Peninsula and southern Egypt they occur mainly in the spring, while in southern Israel and in the Mediterranean parts of northern Egypt, in winter and spring.

SPRING MIGRATION ECOLOGY OF CRETZSCHMAR'S BUNTING (EMBERIZA CAESIA) THROUGH ELAT, ISRAEL

Cretzschmar’s bunting (Emberiza caesia) is a monotypic species with a very restricted distribution. It breeds only in the eastern Mediterranean warm-temperature zone of the western Palaearctic (Gillings and Hallmann, 1997). The species is migratory and winters in the subtropical zone in northeastern Africa and in the southern Arabian Peninsula. Migration is usually nocturnal, on a broad front, and staging stops can also be diurnal (Shirihai, 1996). Cretzschmar’s bunting circumnavigates the Mediterranean Sea by flying along the eastern flyway that passes through the Middle East. In Israel, Cretzschmar’s bunting is classified as a common autumn (mainly September) and very common spring (mainly March) passage migrant in most parts, and is also a fairly common breeding summer visitor in northern and central Israel. Shirihai (1996) reports that flocks of 500–1000 Cretzschmar’s buntings have also been documented in the same areas in the 1980s. Hence, in order to enhance our understanding of the migration ecology of the different age and sex groups of Cretzschmar’s bunting, we analyzed the data 1984–2000 for all individuals ringed at Elat, Israel. Data were obtained from the International Birding and Research Centre in Eilat (IBRCE). Just north of Elat (29°33N, 34°57E), it is the only long-term ringing station in the Middle East. Ringing was initiated in 1984; however, owing to changes in agricultural practices and political pressures, the ringing location has changed three times (Morgan and Shirihai, 1997). A total of 528 (range 3–161) Cretzschmar’s buntings have been ringed at Elat in the past 17 springs and none recovered or controlled elsewhere. We analyzed the data cumulatively for biometrics, and only data of springs 1984, 1990, and 2000 were further analyzed for phenology because only in these seasons was a large enough sample size caught and ringed. Arrival time is presented in Julian dates. Further, not all birds were sexed by the ringer, and data on wing chord length or body mass was not collected (methods Svensson, 1992) for all individuals, which has resulted in a large variation in sample sizes. We classified the birds into four age or sex classes—adult male, first calendar-year male, adult female, and first calendar-year female (cf. Small, 1992). Individuals not ascribed to one of these classes were not included in the biometric analyses. NOTE:

Zooplankton spatial distributions in coastal waters of the northern Arabian Sea, August, 1995

Abstract The spatial distribution of zooplankton biomass was surveyed in coastal waters of the northern Arabian Sea during the 1995 Southwest Monsoon (August) on cruise MB 95-06 of the NOAA Ship Malcolm Baldrige . Vertical patterns of displacement volumes from a limited set of paired day–night MOCNESS tows suggest there was little diel vertical migration in the coastal waters off the southern Arabian Peninsula. Zooplankton biomass varied from 5.2 to 15.1 g dw m −2 (178–517 mM C m −2 ) in the upper 200–300 m of Omani coastal waters. Distributions of acoustic backscatter were mapped in eight daytime acoustic Doppler current profiler transects in coastal waters off Oman and Somalia. Several transects contained maxima in acoustic backscatter that coincided with cool, fresh surface features that were several tens of kilometers wide. Although there was considerable scatter in the relationship between acoustically determined biomass (ADB) of zooplankton and surface temperature, there was a trend of increased biomass in the cool surface temperatures of the Omani upwelling zone. Acoustic transects crossed two filaments that extended seaward from upwelling centers off Oman and Somalia. Estimated zooplankton ADB exported from the upwelling zones in the surface features was on the order of 300 kg dw s −1 . The physical and biological characteristics of filaments maintain zooplankton associated with upwelling areas, such as Calanoides carinatus , as they are advected offshore from coastal upwelling zones.

Source Rock Distribution and Thermal Maturity in the Southern Arabian Peninsula

Source Rock Distribution and Thermal Maturity in the Southern Arabian Peninsula

Genetic Variation and Phylogeography of Central Asian and Other House Mice, Including a Major New Mitochondrial Lineage in Yemen

The mitochondrial DNA (mtDNA) control region and flanking tRNAs were sequenced from 76 mice collected at 60 localities extending from Egypt through Turkey, Yemen, Iran, Afghanistan, Pakistan, and Nepal to eastern Asia. Segments of the Y chromosome and of a processed p53 pseudogene (Psip53) were amplified from many of these mice and from others collected elsewhere in Eurasia and North Africa. The 251 mtDNA types, including 54 new ones reported here, now identified from commensal house mice (Mus musculus group) by sequencing this segment can be organized into four major lineages-domesticus, musculus, castaneus, and a new lineage found in Yemen. Evolutionary tree analysis suggested the domesticus mtDNAs as the sister group to the other three commensal mtDNA lineages and the Yemeni mtDNAs as the next oldest lineage. Using this tree and the phylogeographic approach, we derived a new model for the origin and radiation of commensal house mice whose main features are an origin in west-central Asia (within the present-day range of M. domesticus) and the sequential spreading of mice first to the southern Arabian Peninsula, thence eastward and northward into south-central Asia, and later from south-central Asia to north-central Asia (and thence into most of northern Eurasia) and to southeastern Asia. Y chromosomes with and without an 18-bp deletion in the Zfy-2 gene were detected among mice from Iran and Afghanistan, while only undeleted Ys were found in Turkey, Yemen, Pakistan, and Nepal. Polymorphism for the presence of a Psip53 was observed in Georgia, Iran, Turkmenistan, Afghanistan, and Pakistan. Sequencing of a 128-bp Psip53 segment from 79 commensal mice revealed 12 variable sites and implicated >/=14 alleles. The allele that appeared to be phylogenetically ancestral was widespread, and the greatest diversity was observed in Turkey, Afghanistan, Pakistan, and Nepal. Two mice provided evidence for a second Psip53 locus in some commensal populations.

Source Rock Distribution and Thermal Maturity in the Southern Arabian Peninsula

ABSTRACT Recent work by Phillips Petroleum in the Southern Arabian Peninsula has elucidated the source potential of the Palaeozoic strata. A group of newly drilled and older wells, together with exclusive and non-exclusive reports, have been used in order to develop improved maturation and migration models for emerging plays, and to gain a better understanding of the subsidence and maturation history of this large and diverse area. It has been possible to conduct comprehensive burial history modelling for a number of wells from Oman, Saudi Arabia and the United Arab Emirates. This, together with the modelling of hypothetical wells derived from depth structure maps, has improved our understanding of oil- and gas-prone source rocks in the Cretaceous, Jurassic and Palaeozoic strata. The resultant maturity distribution has been developed with the aid of a more detailed structural model for the Southern Arabian Peninsula. In tandem with this study, available cores and cuttings were analysed to measure source rock total organic carbon, maturity and richness parameters and summarised using proprietary techniques. It is concluded that the Jurassic Hanifa Formation is less mature and not source facies to the south and west of the Rub’ Al-Khali. The oil and gas mature source facies is present in the north and east of the Rub’ Al-Khali and in the Western Emirates. In addition, it is concluded that the oil mature Silurian source facies is confined to the narrow southern and western margins of the Rub’ Al-Khali. Outside this area the overmature area is in the core of the Rub’ Al-Khali extending northeast to the United Arab Emirates. The remaining area is modelled as gas mature in western Saudi Arabia and Qatar.

A Revision of the Genus Neuracanthus (Acanthaceae)

Summary. The genus Neuracanthus is divided into 3 sections; 30 species are recognised, with a further 5 subspecies and 3 varieties. From tropical Asia (India to Vietnam) 4 species and one subspecies are recognised, all referred to sect. Neuracanthus which also has two species in north and northeast Africa. From Madagascar 6 species (3 newly described) are recognised, all of which are referred to sect. Didymosperma in which a further 6 species (1 described as new) from continental Africa are also included. The remaining 12 species (2 newly described) are referred to sect. Leucobarleria and are characteristic of the dry areas of northeastern tropical Africa and southern Arabian Peninsula. Many species appear to be very local and are poorly known. While the genus is clearly defined, its relationships to other genera and its position within the Acanthaceae are obscure.

Sarcostemma R. Br. (Asclepiadaceae) in East Africa and Arabia

The circumscription of the two Arabian species Sarcostemma forskaolianum Schult. and S. vanlessenii Lavranos is clarified. S. vanlessenii is identified as a widespread species, occurring in East Africa and the southern Arabian Peninsula. Within the Sarcostemma viminale complex, three new subspecies are delimitated. Subspecies odonlolepis (Balf.f.) Meve & Liede, comb, et stat. nov. is established for glabrous, strongly twinning plants close to those of subspecies brunonianum (Wight & Am.) P.I. Forst., but distinguished by flower-bearing laterals and an outer corona half as high as the gynostegium. Ecologically, this taxon is confined to coastal habitats in East Africa. Subspecies stipilaceum (Forssk.) Meve & Liede, comb, ct stat. nov. covers stout, non-twining representatives of East Africa and Arabia, also with short flower-bearing laterals. Subspecies suberosum Meve & Liede, subsp. nov. is newly described to accommodate the most frequent East African form of S. viminale, often mistaken for the typical subspecies. All taxa are described in detail, chromosome numbers are given and distribution maps are provided for S. forskaolianum, S. vanlessenii and S. viminale subsp. odontolepis. A synopsis of all taxa occurring in East Africa and Arabia and additional chromosome numbers are provided.

Kretazische Echinoiden vom Süden der Arabischen Halbinsel und ihre paläobiogeographische Bedeutung

Kretazische Echinoiden vom Süden der Arabischen Halbinsel und ihre paläobiogeographische Bedeutung

How wet is wet? Precipitation constraints on late quaternary climate in the southern Arabian Peninsula

It is generally recognized that the southern Arabian Peninsula has had two wet periods in the late Quaternary. To quantify ‘wet’ a 28 000 year old capillary surface associated with a paleowater-table was mapped and used as a surrogate for the water table in a ground-water model. Analysis of this model suggests 1.4 mm year −1 of recharge is necessary to support the water table at the mapped elevations during the wet period. Climatic relations between rainfall and recharge in arid areas infer that annual rainfall during this wet period was approximately 200 ± 50 mm year −1 or approximately five times the present rate.

Late Palaeozoic glacial sediments of the southern Arabian Peninsula: their lithofacies and hydrocarbon potential

Evidence of Late Palaeozoic glaciation is known in the southern Arabian Peninsula, in Yemen, Saudi Arabia and Oman. Palynological assemblages date these beds as Late Carboniferous to Early Permian (Sakmarian). The lithofacies consits of diamictites, varvites with dropstones, sandstones, siltstones and shales, suggesting depositional environments ranging from grounded tillites to glacio-lacustrine to marine. Oman oil is reported to be trapped primarily in the sands (in Haushi Group clastics), which are sealed by the Cretaceous Nahr Umr shales. The source is presumed to lie in the Late Precambrian marine algal limestones.

Surface effects and tectonic setting of the 13 December 1982 North Yemen earthquake

Abstract The North Yemen earthquake (Mb = 6.0) of 13 December 1982 is the first earthquake in the southern Arabian Peninsula known to be accompanied by surface displacements. The extensive destruction and loss of lives resulted entirely from widespread collapse of unreinforced masonry and mud brick structures; maximum Modified Mercalli intensity was probably VII to VIII. The only surface manifestation of tectonic activity was the occurrence of earthquake-related extensional ground cracks in the epicentral region. The cracks occur mainly in four relatively continuous north- to northwest-trending linear zones that range from a few hundred meters to 15 km in length and in irregular areas of polygonal extension cracks. The area within which the cracks occur is 22.5 km long by about 10 km wide. Continued dilation across some cracks was measured almost 1 month after the main shock. Seismicity and active volcanism in this region are inferred to reflect slow extension of the southwestern margin of the Arabia plate perpendicular to the Red Sea spreading axis.

Rupture complexity of a moderate-sized (mb6.0) earthquake: Broadband body-wave analysis of the North Yemen earthquake of 13 December 1982

AbstractThe occurrence of the North Yemen earthquake of 13 December 1982 provides an important opportunity to study source properties of earthquakes in the southern Arabian Peninsula. Although moderate in size (mb 6.0), this earthquake is the largest to have occurred in the region since the deployment of the Global Digital Seismograph Network. P waves recorded at teleseismic distances can be obtained from stations of this network and of the Graefenberg array that are flat to displacement and velocity in the frequency range from 0.01 to 5.0 Hz. The broad bandwidth of the data is necessary for deriving a dynamic description of the earthquake as well as the static properties of the source. In contrast, inversions using only long-period data provide much less insight into the complexity of rupture. By fitting the displacement pulse shapes with synthetics, we find that the Yemen earthquake was a complex rupture consisting of two events that occurred about 3.0 sec apart. The depth of both hypocenters is estimated to be 7 km. The focal mechanisms of the events each have a nodal plane that strikes 340° and dips 60° to the east. However, the slip directions of the focal mechanisms are in slightly different directions, 230° and 300°, respectively. The total moment of the earthquake is 3.0 ×1025 dyne-cm, with the second event having three times the moment of the initial event. By inverting P-wave arrival time differences at each station, we find the second hypocenter is located 7.5 km from the initial hypocenter in a direction that is nearly colinear with the NNW-striking nodal plane of the focal mechanisms of each event. The trend of extensional ground cracks in the epicentral region and the predominant strike of composite focal mechanisms of locally recorded aftershocks are also in a NNW direction. From the consistency of these observations, we infer that the east-dipping NNW-striking nodal planes are the fault planes. The static stress drop of the first and second events are 44 and 31 bars, respectively. Inverting the energy flux in the velocity waveforms, we find the energy radiated by the earthquake is 4.8 ×1020 dyne-cm. This implies an average apparent stress of 4 bars.At different times during the aftershock sequence, seismicity tended to cluster about one or another of two different planes which, although having roughly the same strike, had conjugate dips. One of these planes, delineated late in the aftershock sequence, coincides with the inferred fault plane for the main shock. The complexity of the main shock and of the aftershock sequence suggests that strain accumulated on a system of strongly interdependent faults. As the region became critically loaded, the effect of a major rupture was to critically stress faults adjacent to the initial nucleation. The second event of the main shock represents the rapid release of stress from the fault system, while the ensuing aftershock sequence represents the gradual release of stress.

The Structure of the Arabian Heat Low. Part II: Bulk Tropospheric Heat Budget and Implications

An investigation of the Arabian heat low is carried out based on observations from various satellites, an experimental aircraft and a surface energy budget monitoring station. The observations suggest that during the spring period the Arabian heat low is nearly radiatively neutral and lacks the properties of an energy sink characteristic of conventional desert heat lows. Satellite derived top-of-atmosphere radiation budget analyses illustrate the high contrast properties of the radiative exchange fields over the southern Arabian Peninsula with respect to its surroundings. However, an examination of a four-month time series of daily averaged net radiative exchange over the Arabian Empty Quarter, derived from Nimbus-7 Earth Radiation Budget (ERB) measurements, indicates that the heat low region is in slight relative excess. Combining these results with estimates of the surface energy budget inside the Arabian Empty Quarter (described in Part I), and previously estimated tropospheric radiative heating rate profiles, provide a closed set of flux terms used to evaluate the energy exchange process within the heat low region. A synthesis of these results indicates that the heat low is a total energy source region. A conceptual structure of the heat low is offered based on a three-layer stratification of the heating mechanisms. The possible role of the Arabian heat low in controlling thermodynamic conditions and forcing baroclinicity in the western Arabian Sea is discussed. It is concluded that the surplus energy properties of the heat low may serve as an important mechanism in controlling moisture transport into the southwest monsoon rainfall regions.