994 resultados para Cocos (Keeling) Islands - History


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Mode of access: Internet.

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[EN]We present the first U-series ages of corals from emergent marine deposits on the Canary Islands. Deposits at +. 20. m are 481 ± 39 ka, possibly correlative to marine isotope stage (or MIS) 11, while those at +. 12 and +. 8. m are 120.5 ± 0.8. ka and 130.2 ± 0.8. ka, respectively, correlative to MIS 5.5. The age, elevations, and uplift rates derived from MIS 5.5 deposits on the Canary Islands allow calculations of hypothetical palaeo-sea levels during the MIS 11 high sea stand. Estimates indicate that the MIS 11 high sea stand likely was at least +. 9. m (relative to present sea level) and could have been as high as +. 24. m.

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Diamondback terrapins (Malaclemys terrapin) are native to the remote oceanic islands of Bermuda and presently inhabit only four small brackish water ponds on a private golf course. The life history of this species is poorly understood on Bermuda and so the aim of this study was to fill these knowledge gaps, to compare the results with what is known from other areas in the North American range, and to inform the development of a local management plan. The results of a mark-recapture census revealed that ca. 100 individuals ≥81 mm straight carapace length live on Bermuda, of which nearly half (48.5%) were considered sexually mature. The population is dominated by females (sex ratio 2.9:1) and annual recruitment over the three year period was found to be extremely low (approximately two terrapins). Female diamondback terrapins in Bermuda nest almost exclusively within a limited number of sand bunkers on the golf course. Nesting commenced in late March or early April and ended in late August. Peak oviposition was observed in May and June. Clutch size averaged 5.1 eggs (range 0-10; SD 2.4) and the incubation period averaged 61.8 days (range 49-83; SD 10.5). Delayed emergence was documented, with 43.8% of the hatchlings remaining in their natal nests over the winter months. The mean annual hatching success rate was determined to be 19% (range 17.6-21; SD 1.9). Radio-telemetry was used to investigate the movements and survivorship of postemergent hatchling diamondback terrapins. The results indicated that mangrove swamps and grass-dominated marshes adjacent to the ponds are important developmental habitats for hatchlings. Yellow-crowned night herons (Nyctanassa violacea) were found to be significant predators of small terrapins during spring emergence. Small aquatic gastropods comprised 66.7% of the faecal samples analysed from the Bermudian population. Scavenged fish and vertebrate animal remains, terrestrial arthropods, polychaete worms and bivalves were consumed in lesser amounts. Sediment from the pond environment was found in 74% of the faecal samples analysed and is believed to have been incidentally ingested while foraging for the small benthic gastropods. Eco-toxicological analyses of the pond sediment, prey and terrapin eggs showed that the Bermudian diamondback terrapins live and feed in wetland habitats characterised by chronic, multifactorial contamination; principally total petroleum hydrocarbons, polycyclic aromatic hydrocarbons and a variety of heavy metals. This study found that some of those contaminants are accumulating in the gastropod prey as well as being transferred to terrapin eggs. This may be reducing the incidence of successful embryonic development for this species in Bermuda and may likely contribute to the observed low hatching rates. These collective findings indicate that the Bermudian population is very vulnerable to local extirpation.

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The new model of North Island Cenozoic palaeogeography developed by Kamp et al. has a range of important implications for the evolution of New Zealand terrestrial taxa over the past 30 Ma. Key aspects include the prolonged isolation of the biota on the North Island landmass from the larger and more diverse greater South Island, and the founding of North Island taxa from the potentially unusual ecosystem of a small island around Northland. The prolonged period of isolation is expected to have generated deep phylogenetic splits within taxa present on both islands, and an important current aim should be to identify such signals in surviving endemics to start building a picture of the historical phylogeography, and inferred ecology of both islands through the Cenozoic. Given the potential differences in founding terrestrial species and climatic conditions, it seems likely that the ecology may have been very diferent between the North and South Islands. New genetic data from the 10 or so species of extinct moa suggest that the radiation of moa was much more recent than previously suggested, and reveals a complex pattern that is inferred to result from the interplay of the Cenozoic biogeography, marine barriers, and glacial cycles.

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Mass flows on volcanic islands generated by volcanic lava dome collapse and by larger-volume flank collapse can be highly dangerous locally and may generate tsunamis that threaten a wider area. It is therefore important to understand their frequency, emplacement dynamics, and relationship to volcanic eruption cycles. The best record of mass flow on volcanic islands may be found offshore, where most material is deposited and where intervening hemipelagic sediment aids dating. Here we analyze what is arguably the most comprehensive sediment core data set collected offshore from a volcanic island. The cores are located southeast of Montserrat, on which the Soufriere Hills volcano has been erupting since 1995. The cores provide a record of mass flow events during the last 110 thousand years. Older mass flow deposits differ significantly from those generated by the repeated lava dome collapses observed since 1995. The oldest mass flow deposit originated through collapse of the basaltic South Soufriere Hills at 103-110 ka, some 20-30 ka after eruptions formed this volcanic center. A ∼1.8 km3 blocky debris avalanche deposit that extends from a chute in the island shelf records a particularly deep-seated failure. It likely formed from a collapse of almost equal amounts of volcanic edifice and coeval carbonate shelf, emplacing a mixed bioclastic-andesitic turbidite in a complex series of stages. This study illustrates how volcanic island growth and collapse involved extensive, large-volume submarine mass flows with highly variable composition. Runout turbidites indicate that mass flows are emplaced either in multiple stages or as single events.

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This thesis has created a space for women in the history of the decolonisation of the Gilbert Islands. It traces the historical development of the national women's interests program in the Republic of Kiribati (formerly of the Gilbert and Ellice Islands Colony (GEIC)) as it was implemented through a network of women's clubs during the 1960s and 1970s. This thesis has provided the first history and interpretation of the Indigenous women's interests movement as it impacted the Gilbert Islands. It offers a narrative of the movement in terms of three overlapping waves of women leaders, based on an analysis of fieldwork, archival research and interviews conducted on South Tarawa, Kiribati.

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Architecture in the South Pacific: The Ocean of Islands recounts the recent developments of the South Pacific and its fascinating architecture. This volume traces the European architectural overlay onto this scattered group of islands as well as the transition of these same islands towards a regional identity that has been fashioned by the remoteness of each location, the incomparable setting, and the distinctive ethnic mix of its inhabitants. A series of themed essays present the story of architectural development in the Solomon Islands, Vanuatu, New Caledonia, Fiji, Wallis and Futuna, Tonga, the Cook Islands, Samoa and American Samoa, and French Polynesia. Recent architecture typifies the evolution of the islands as they have been subjected to the transformative waves of alien trade, religion, colonization, war and tourism, followed by post-colonialism and revived nationalism. As with the Pacific region itself, the most prominent characteristic of the architecture is its diversity. The blending of the universal and the local sets the stage for a fresh vision of the South Pacific across a wide range of building types, from spectacular mission churches to sensational resorts in paradise. This book, in full colour, will appeal to architects, armchair-tourists, students and all those for whom the South Pacific is the idyll of their dreams.

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Pacific Neighbours: Understanding the Pacific Islands (2009) is a resource book to develop understanding of the region, its history and geography, its political and social development, and its people and their cultures. The accompanying CD-ROM contains PDFs of the book, a reformatted version of the book by country using an interactive map, and extra teacher and student resources.

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Aim: Resolving the origin of invasive plant species is important for understanding the introduction histories of successful invaders and aiding strategies aimed at their management. This study aimed to infer the number and origin(s) of introduction for the globally invasive species, Macfadyena unguis-cati and Jatropha gossypiifolia using molecular data. Location: Native range: Neotropics; Invaded range: North America, Africa, Europe, Asia, Pacific Islands and Australia. Methods: We used chloroplast microsatellites (cpSSRs) to elucidate the origin(s) of introduced populations and calculated the genetic diversity in native and introduced regions. Results: Strong genetic structure was found within the native range of M. unguis-cati, but no genetic structuring was evident in the native range of J. gossypiifolia. Overall, 27 haplotypes were found in the native range of M. unguis-cati. Only four haplotypes were found in the introduced range, with more than 96% of introduced specimens matching a haplotype from Paraguay. In contrast, 15 haplotypes were found in the introduced range of J. gossypiifolia, with all invasive populations, except New Caledonia, comprising multiple haplotypes. Main conclusions: These data show that two invasive plant species from the same native range have had vastly different introduction histories in their non-native ranges. Invasive populations of M. unguis-cati probably came from a single or few independent introductions, whereas most invasive J. gossypiifolia populations arose from multiple introductions or alternatively from a representative sample of genetic diversity from a panmictic native range. As introduced M. unguis-cati populations are dominated by a single haplotype, locally adapted natural enemies should make the best control agents. However, invasive populations of J. gossypiifolia are genetically diverse and the selection of bio-control agents will be considerably more complex.

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Arrowtooth flounder (Atheresthes stomias) has the highest biomass of any groundfish species in the Gulf of Alaska, is a voracious predator of age 1 walleye pollock (Theragra chalcogramma), and is a major component in the diet of Steller sea lions (Eumetopias jubatus). Owing to its ecological importance in the Gulf of Alaska and the limited information available on its reproduction, interest has intensified in describing its spawning and early life history. A study was undertaken in late January–February 2001–2003 in the Gulf of Alaska to obtain information on adult spawning location, depth distribution, and sexual maturity, and to obtain fertilized eggs for laboratory studies. Adults were found 200–600 m deep east of Kodiak Island over the outer continental shelf and upper slope, and southwest along the shelf break to the Shumagin Islands. Most ripe females (oocytes extruded with light pressure) were found at 400 m and most ripe males (milt extruded with light pressure) were found at depths ≥450 m. Eggs were fertilized and incubated in the laboratory at 3.0°, 4.5°, and 6.0°C. Eggs were reared to hatching, but larvae did not survive long enough to complete yolk absorption and develop pigment. Eggs were staged according to morphological hallmarks and incubation data were used to produce a stage duration table and a regression model to estimate egg age based on water temperature and developmental stage. Arrowtooth flounder eggs (1.58–1.98 mm in diameter) were collected in ichthyoplankton surveys along the continental shelf edge, primarily at depths ≥400 m. Early-stage eggs were found in tows that sampled to depths of ≥450 m. Larvae, which hatch between 3.9 and 4.8 mm standard length, increased in abundance with depth. Observations on arrowtooth flounder eggs and early-stage larvae were used to complete the description of the published partial developmental series.(PDF file contains 34 pages.)

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Long paleoseismic histories are necessary for understanding the full range of behavior of faults, as the most destructive events often have recurrence intervals longer than local recorded history. The Sunda megathrust, the interface along which the Australian plate subducts beneath Southeast Asia, provides an ideal natural laboratory for determining a detailed paleoseismic history over many seismic cycles. The outer-arc islands above the seismogenic portion of the megathrust cyclically rise and subside in response to processes on the underlying megathrust, providing uncommonly good illumination of megathrust behavior. Furthermore, the growth histories of coral microatolls, which record tectonic uplift and subsidence via relative sea level, can be used to investigate the detailed coseismic and interseismic deformation patterns. One particularly interesting area is the Mentawai segment of the megathrust, which has been shown to characteristically fail in a series of ruptures over decades, rather than a single end-to-end rupture. This behavior has been termed a seismic “supercycle.” Prior to the current rupture sequence, which began in 2007, the segment previously ruptured during the 14th century, the late 16th to late 17th century, and most recently during historical earthquakes in 1797 and 1833. In this study, we examine each of these previous supercycles in turn.

First, we expand upon previous analysis of the 1797–1833 rupture sequence with a comprehensive review of previously published coral microatoll data and the addition of a significant amount of new data. We present detailed maps of coseismic uplift during the two great earthquakes and of interseismic deformation during the periods 1755–1833 and 1950–1997 and models of the corresponding slip and coupling on the underlying megathrust. We derive magnitudes of Mw 8.7–9.0 for the two historical earthquakes, and determine that the 1797 earthquake fundamentally changed the state of coupling on the fault for decades afterward. We conclude that while major earthquakes generally do not involve rupture of the entire Mentawai segment, they undoubtedly influence the progression of subsequent ruptures, even beyond their own rupture area. This concept is of vital importance for monitoring and forecasting the progression of the modern rupture sequence.

Turning our attention to the 14th century, we present evidence of a shallow slip event in approximately A.D. 1314, which preceded the “conventional” megathrust rupture sequence. We calculate a suite of slip models, slightly deeper and/or larger than the 2010 Pagai Islands earthquake, that are consistent with the large amount of subsidence recorded at our study site. Sea-level records from older coral microatolls suggest that these events occur at least once every millennium, but likely far less frequently than their great downdip neighbors. The revelation that shallow slip events are important contributors to the seismic cycle of the Mentawai segment further complicates our understanding of this subduction megathrust and our assessment of the region’s exposure to seismic and tsunami hazards.

Finally, we present an outline of the complex intervening rupture sequence that took place in the 16th and 17th centuries, which involved at least five distinct uplift events. We conclude that each of the supercycles had unique features, and all of the types of fault behavior we observe are consistent with highly heterogeneous frictional properties of the megathrust beneath the south-central Mentawai Islands. We conclude that the heterogeneous distribution of asperities produces terminations and overlap zones between fault ruptures, resulting in the seismic “supercycle” phenomenon.