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"Arabian Peninsula Geography"
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review of contemporary patterns of endemism for shallow water reef fauna in the Red Sea
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 across taxa. The presence of physical barriers does not appear to explain species distributions, which are more likely determined by ecological plasticity and genetic diversity.
Journal Article
On the origin of endemic species in the Red Sea
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, circulation patterns and the constriction at the mouth of the Gulf of Aqaba. Endemics that evolved within the Red Sea basin had to survive glacial cycles in relatively low salinity refugia. It therefore appears that the unique conditions in the Red Sea, in addition to those characteristics of the Arabian Peninsula region as a whole, drive the divergence of populations via a combination of isolation and selection.
Journal Article
Food as a weapon? The geopolitics of food and the Qatar–Gulf rift
On 4 June 2017, Qatar was suddenly put under an embargo by its regional neighbors – an effort spearheaded by Saudi Arabia and the UAE, who cut off most of its existing land, sea, and air traffic routes. With no domestic agriculture to speak of, Qatar’s external logistics networks are essential for maintaining its food supply. The country’s 2.6 million residents, many of whom flooded the grocery stores, were understandably concerned about their ability to secure food when news about the embargo broke. Eventually, new food supply chains were established, primarily with the assistance of partners in Iran and Turkey. The ongoing rift between Qatar and its neighbors in the Arabian Peninsula, manifested only in part by this effort to undermine the country’s material supply networks raises a number of questions about an old idea: that of food as a ‘weapon’. This article puts this concept in historical and regional perspective in the Arabian Peninsula through the lens of critical geopolitics, tracing the securitizing discourses about food security and their intertwining with narratives about territorial sovereignty, nationalism, and essentialist understandings of geography to explain the causes and effects of the food embargo in the ongoing Qatar–Gulf rift.
Journal Article
Landslide susceptibility mapping using random forest, boosted regression tree, classification and regression tree, and general linear models and comparison of their performance at Wadi Tayyah Basin, Asir Region, Saudi Arabia
The purpose of the current study is to produce landslide susceptibility maps using different data mining models. Four modeling techniques, namely random forest (RF), boosted regression tree (BRT), classification and regression tree (CART), and general linear (GLM) are used, and their results are compared for landslides susceptibility mapping at the Wadi Tayyah Basin, Asir Region, Saudi Arabia. Landslide locations were identified and mapped from the interpretation of different data types, including high-resolution satellite images, topographic maps, historical records, and extensive field surveys. In total, 125 landslide locations were mapped using ArcGIS 10.2, and the locations were divided into two groups; training (70 %) and validating (25 %), respectively. Eleven layers of landslide-conditioning factors were prepared, including slope aspect, altitude, distance from faults, lithology, plan curvature, profile curvature, rainfall, distance from streams, distance from roads, slope angle, and land use. The relationships between the landslide-conditioning factors and the landslide inventory map were calculated using the mentioned 32 models (RF, BRT, CART, and generalized additive (GAM)). The models’ results were compared with landslide locations, which were not used during the models’ training. The receiver operating characteristics (ROC), including the area under the curve (AUC), was used to assess the accuracy of the models. The success (training data) and prediction (validation data) rate curves were calculated. The results showed that the AUC for success rates are 0.783 (78.3 %), 0.958 (95.8 %), 0.816 (81.6 %), and 0.821 (82.1 %) for RF, BRT, CART, and GLM models, respectively. The prediction rates are 0.812 (81.2 %), 0.856 (85.6 %), 0.862 (86.2 %), and 0.769 (76.9 %) for RF, BRT, CART, and GLM models, respectively. Subsequently, landslide susceptibility maps were divided into four classes, including low, moderate, high, and very high susceptibility. The results revealed that the RF, BRT, CART, and GLM models produced reasonable accuracy in landslide susceptibility mapping. The outcome maps would be useful for general planned development activities in the future, such as choosing new urban areas and infrastructural activities, as well as for environmental protection.
Journal Article
Late Holocene development of Bubiyan Island, Kuwait
Bubiyan Island, presently a vast sabkha and salt flat in the westernmost part of the Shatt Al-Arab delta, originated ca. 4000 cal yr BP as prodelta deposits from a paleochannel of the Euphrates River that flowed into a shallow sea. Southeastern Bubiyan Island first surfaced when spits and barrier islands formed on a 1–2 m forebulge caused by heavy sediment load to the northwest; the spits and barriers delineated an incipient shoreline and sheltered a shallow lagoon. Progradation of southeastern Bubiyan Island began when the spits and barriers were gradually stranded as beach ridges during minor sea-level fluctuations and continued marginal uplift. AMS dating of the beach ridges, which are ~1–5 km from the present shoreline, implies that Late Holocene relative sea level fell in three phases: ca. 3700–3400 cal yr BP, ca. 2600–1000 cal yr BP, and ca. 600–500 cal yr BP. Prior to each phase, relative sea level apparently stabilized to near stillstands, allowing spits and barriers to accrete. Torpedo-jar pottery sherds scattered on some of the most prominent beach ridges indicate Sasanian (AD ca. 300–650; 1650–1300 cal yr BP) to early Islamic (AD ca. 650–800; 1300–1150 cal yr BP) periods of human presence, concurrent with the Second phase of beach-ridge formation.
Journal Article