scholarly journals Birth of a large volcanic edifice offshore Mayotte (Comoros Island, Western Indian Ocean)

2020 ◽  
Author(s):  
Nathalie Feuillet ◽  
Stephan Jorry ◽  
Wayne Crawford ◽  
Christine Deplus ◽  
Isabelle Thinon ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Noble Gas ◽  
Low Frequency ◽  
Volcanic Eruptions ◽  
Western Indian Ocean ◽  
Volcanic Edifice ◽  
East African ◽  
Chemical Signatures ◽  
Acoustic Anomaly ◽  
Magmatic Event

<p>Volcanic eruptions are foundational events shaping the Earth’s surface and providing a window into deep Earth processes. We document here an ongoing magmatic event offshore Mayotte island (Western Indian Ocean) unprecedented in terms of emitted volume of lava and duration of the seismic crisis.This event gave birth to a deep-sea volcanic edifice 820m tall and ~ 5 km<sup>3</sup> in volume, located 50 km from Mayotte. A plume with distinct chemical signatures compared to open-ocean seawater emanated from the edifice, generating an exceptional 1900m-high vertical acoustic anomaly in the water column. Noble gas analyses in the vesicles from a popping rock dredged on the flank of the edifice, indicate rapid magma transfer from the asthenosphere. The edifice is located at the tip of a WNW-ESE–striking volcanic ridge composed of many other edifices, cones and lava flows constructed by past eruptions. Starting in May 2018 thousand of earthquakes were triggered by the magmatic event. The space-time distribution of the seismicity suggests that magma below the center of the ridge was transported to the new edifice over a few weeks in dikes that penetrated the brittle mantle a result of a lithosphere-scale extensional episode accommodating motion along a transfer zone between the East-African rifts and Madagascar. Since the eruption’s onset, the seismicity is mostly concentrated closer to the island, in an exceptionally deep zone (25-50 km) overlain by a zone of enigmatic, very low frequency, tremors.</p>

scholarly journals Impact of the East African Rift System on the routing of the deep‐water drainage network offshore Tanzania, western Indian Ocean

2019 ◽  
Vol 32 (5) ◽  
pp. 789-803 ◽  
Author(s):  
Vittorio Maselli ◽  
Dick Kroon ◽  
David Iacopini ◽  
Bridget S. Wade ◽  
Paul N. Pearson ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Deep Water ◽  
Western Indian Ocean ◽  
East African Rift ◽  
Rift System ◽  
Drainage Network ◽  
East African Rift System ◽  
Water Drainage ◽  
East African ◽  
African Rift

scholarly journals Expansion of the mangrove species Rhizophora mucronata in the Western Indian Ocean launched contrasting genetic patterns

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ludwig Triest ◽  
Tom Van der Stocken ◽  
Dennis De Ryck ◽  
Marc Kochzius ◽  
Sophie Lorent ◽  
...  
Keyword(s):  
Gene Flow ◽  
Indian Ocean ◽  
Large Scale ◽  
Geographic Distance ◽  
Western Indian Ocean ◽  
Coastal Current ◽  
Rhizophora Mucronata ◽  
East African ◽  
Mangrove Species ◽  
Mozambique Channel

AbstractEstimates of population structure and gene flow allow exploring the historical and contemporary processes that determine a species’ biogeographic pattern. In mangroves, large-scale genetic studies to estimate gene flow have been conducted predominantly in the Indo-Pacific and Atlantic region. Here we examine the genetic diversity and connectivity of Rhizophora mucronata across a > 3,000 km coastal stretch in the Western Indian Ocean (WIO) including WIO islands. Based on 359 trees from 13 populations and using 17 polymorphic microsatellite loci we detected genetic breaks between populations of the (1) East African coastline, (2) Mozambique Channel Area (3) granitic Seychelles, and (4) Aldabra and northern Madagascar. Genetic structure, diversity levels, and patterns of inferred connectivity, aligned with the directionality of major ocean currents, driven by bifurcation of the South Equatorial Current, northward into the East African Coastal Current and southward into the Mozambique Channel Area. A secondary genetic break between nearby populations in the Delagoa Bight coincided with high inbreeding levels and fixed loci. Results illustrate how oceanographic processes can connect and separate mangrove populations regardless of geographic distance.

Ceramics in Indian Ocean Trade

Matatu ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 35-45
Author(s):  
Villoo Nowrojee
Keyword(s):  
Indian Ocean ◽  
Western Europe ◽  
Western Indian Ocean ◽  
East African ◽  
East African Coast ◽  
Indian Ocean Trade ◽  
African Coast

Abstract Ceramics have been extensively imported on the East African Coast over many centuries. The principal sources have been Iran and China, the latter trans-shipped through the port of Malacca and the Indian ports of the western Indian Ocean. These ceramics were used to embellish the gates and mihrabs of mosques, and the exteriors of elaborate tombs. They were vessels in homes and decorations on buildings. In the last two centuries, the old ceramics came to be supplanted by imported ware more utilitarian in make and appearance. These came in mainly from Holland, England and Germany. These products of Western Europe were influenced by the Islamic markets they had entered, while in turn these plates became an important part of the East African Coast’s architecture and Swahili traditions and homes.

History, Politics, and Culture in Central Tanzania

2019 ◽  
Author(s):  
Philip Gooding
Keyword(s):  
Indian Ocean ◽  
19Th Century ◽  
Western Indian Ocean ◽  
Migrant Group ◽  
East African ◽  
Politics And Culture ◽  
Islam And Christianity ◽  
Indian Ocean World ◽  
Postcolonial Governance ◽  
The 19Th Century

Central Tanzania is a heterogenous region in the interior of East Africa. Its history, politics, and cultures have been affected by numerous outside influences. These outside influences have primarily come in the form of migrants from elsewhere in the East African interior and the Western Indian Ocean world, and in the form of “proto-colonial,” colonial, and postcolonial governance structures, whose centers since the mid-19th century have been located in Tanzania’s coastal or island regions. Despite the apparent “newness” that each migrant group or governor instituted, Central Tanzania’s politics and cultures have shown a remarkable adaptability to new influences, whether that be to ivory traders arriving in the region during the 19th century or to colonial rulers attempting to govern it during the 20th. Additionally, Islam and Christianity have taken a variety of forms within Central Tanzania, none of which exactly correspond to the ideals of those who originally brought them to the region. The peoples of Central Tanzania have acculturated to outside influences and reconciled them with their preexisting and developing political and cultural structures.

scholarly journals Author Correction: Large-scale mass wasting in the western Indian Ocean constrains onset of East African rifting

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Vittorio Maselli ◽  
David Iacopini ◽  
Cynthia J. Ebinger ◽  
Sugandha Tewari ◽  
Henk de Haas ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Large Scale ◽  
Western Indian Ocean ◽  
Mass Wasting ◽  
East African

Burcad Badeed as Grounds and Method in Literary Expressions of Somali Piracy

2020 ◽  
Vol 4 (1) ◽  
pp. 32-51
Author(s):  
Kelsey McFaul
Keyword(s):  
Indian Ocean ◽  
Knowledge Production ◽  
Western Indian Ocean ◽  
East African ◽  
East African Coast ◽  
Maritime Piracy ◽  
African Coast ◽  
The Indian Ocean ◽  
Indian Ocean World ◽  
The Relationship

The emergence of maritime piracy in the western Indian Ocean captured global attention from 2007 to 2012, resulting in simplistic and racialized representations of piracy in news and other media. In 2011, two diasporic Somali writers published literary works intervening in this representation: Nuruddin Farah’s novel Crossbones and Ubax Cristina Ali Farah’s essay “Un sambuco attraversa il mare” [“A dhow is crossing the sea”]. This essay reads Farah and Ali Farah’s alternative narratives of piracy through the Somali phrase burcad badeed, which both translate as ‘sea bandits’ or ‘pirates.’ As a method burcad badeed first historicizes contemporary piracy within the longue durée of the Indian Ocean world. Second, it draws on the ocean as an analogy and aggregator of dispersed forms of knowledge, thereby inviting comparative reading across conventional boundaries of generation, language, and form, and making visible practices of collective, embodied, and polyvocal knowledge production. Finally, burcad badeed complicates the distinctions between land and sea which undergird legal definitions of piracy to focalize particular landscapes: Namely the beach and the relationship between coast and hinterland. The beach foregrounds the ecological devastation to which piracy is a response, while the relationship between coast and hinterland frames practices of movement, complex racializations, and senses of belonging in Somalia and on the east African coast.

Revision of the Parasesarma guttatum species complex reveals a new pseudocryptic species in south-east African mangroves

2019 ◽  
Author(s):  
Sara Fratini ◽  
Stefano Cannicci ◽  
Francesca Porri ◽  
Gianna Innocenti
Keyword(s):  
New Species ◽  
Indian Ocean ◽  
Species Complex ◽  
Taxonomic Revision ◽  
Western Indian Ocean ◽  
Morphological Characters ◽  
East African ◽  
Species Relationship ◽  
Biogeographic Patterns ◽  
Pseudocryptic Species

Parasesarma De Man, 1895 is the most speciose genus in the family Sesarmidae (Decapoda: Brachyura: Thoracotremata). In the western Indian Ocean, Parasesarma is represented by five species only, although some genetic evidence suggests that P. guttatum could be a species complex comprising two cryptic species. Accordingly, P. guttatum is here split into two pseudocryptic species, and a new species, Parasesarma capensis, sp. nov., is described. P. capensis, sp. nov. fills the same ecological niche as P. guttatum south of the Mozambique Channel. While variation in mitochondrial DNA and morphological differences clearly distinguish the two species, there is no nuclear genetic variation. This may reflect a short history of reproductive isolation. The distinguishing morphological characters of the new species are the 13–15 rounded tubercles on the movable finger, the upper surface of the palm with three transverse crests (one regularly tuberculate and two pectinated), and the shape of the first gonopod. Phylogenetic inference analyses show a sister-species relationship between P. guttatum and P. capensis, sp. nov., and strongly suggest that at least two East African Parasesarma species need a taxonomic revision. The description of this new sesarmid species from the south-eastern African coast sheds new light on the overall biogeographic patterns and general biodiversity of this taxon within the western Indian Ocean.

scholarly journals Deep-water Photinae (Gastropoda: Nassariidae) from eastern Africa, with descriptions of five new species

2020 ◽  
Vol 720 ◽  
pp. 144-169
Author(s):  
Koen Fraussen ◽  
Lee Ann Galindo ◽  
José Rosado
Keyword(s):  
Indian Ocean ◽  
Deep Water ◽  
Western Indian Ocean ◽  
Eastern Africa ◽  
East African ◽  
East African Coast ◽  
West Pacific ◽  
Deep Water Species ◽  
Pacific Species ◽  
Water Species

Deep-water species from the western Indian Ocean off the East African coast and Madagascar, belonging to the subfamily Photinae, are discussed and compared with species from the West Pacific. Phos elegantissimus Hayashi & Habe, 1965, P. hirasei Sowerby, 1913 and P. laevis Kuroda & Habe in Habe, 1961 are recorded from Mozambique and/or from Madagascar, hereby extending their known range considerably into the western Indian Ocean. The East African specimens formerly assigned to Phos roseatus Hinds, 1844 are found to differ from this West Pacific species. In total, five species are described as new: Phos ganii sp. nov., P. geminus sp. nov., P. ladoboides sp. nov., P. pulchritudus sp. nov. and P. testaceus sp. nov.

The meteorology of the Western Indian Ocean, and the influence of the East African Highlands

2005 ◽  
Vol 363 (1826) ◽  
pp. 25-42 ◽  
Author(s):  
Julia Slingo ◽  
Hilary Spencer ◽  
Brian Hoskins ◽  
Paul Berrisford ◽  
Emily Black
Keyword(s):  
Indian Ocean ◽  
Southeast Asia ◽  
General Circulation ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Western Indian Ocean ◽  
East African ◽  
The Indian Ocean ◽  
African Highlands ◽  
East African Highlands

This paper reviews the meteorology of the Western Indian Ocean and uses a state–of–the–art atmospheric general circulation model to investigate the influence of the East African Highlands on the climate of the Indian Ocean and its surrounding regions. The new 44–year re–analysis produced by the European Centre for Medium range Weather Forecasts (ECMWF) has been used to construct a new climatology of the Western Indian Ocean. A brief overview of the seasonal cycle of the Western Indian Ocean is presented which emphasizes the importance of the geography of the Indian Ocean basin for controlling the meteorology of the Western Indian Ocean. The principal modes of inter–annual variability are described, associated with El Niño and the Indian Ocean Dipole or Zonal Mode, and the basic characteristics of the subseasonal weather over the Western Indian Ocean are presented, including new statistics on cyclone tracks derived from the ECMWF re–analyses. Sensitivity experiments, in which the orographic effects of East Africa are removed, have shown that the East African Highlands, although not very high, play a significant role in the climate of Africa, India and Southeast Asia, and in the heat, salinity and momentum forcing of the Western Indian Ocean. The hydrological cycle over Africa is systematically enhanced in all seasons by the presence of the East African Highlands, and during the Asian summer monsoon there is a major redistribution of the rainfall across India and Southeast Asia. The implied impact of the East African Highlands on the ocean is substantial. The East African Highlands systematically freshen the tropical Indian Ocean, and act to focus the monsoon winds along the coast, leading to greater upwelling and cooler sea–surface temperatures.

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