Isthmus Of Central America Research Articles

Tracing Water Sources and Fluxes in a Dynamic Tropical Environment: From Observations to Modeling

Codigo de proyecto: Isotope Network for Tropical Ecosystem Studies (ISONet). Produccion relacionada con el Observatorio del Agua y Cambio Global (OACG).

Tracking the water fingerprints of Cocos Island: a stable isotope analysis of precipitation, surface water, and groundwater

<p>The use of stable isotopes of water, both <span>δ</span><sup>2</sup>H and <span>δ</span><sup>18</sup>O has provided novel insights in hydrological studies, ecological applications, understanding climate variability, and reconstructing paleoclimate. However, information on the stable isotope composition of water in tropical marine island environments is normally scarce within the Central America Isthmus. Here, we present the first isotopic characterization of precipitation, surface water, and groundwater at Cocos Island, Costa Rica within the eastern tropical Pacific Ocean region. Our results show that the Cocos Island MWL can be described as: <span>δ</span><sup>2</sup>H=8.39·<span>δ</span><sup>18</sup>O+13.3; r<sup>2</sup>=0.98 (n=29). Dry season rainfall events ranged from -4.9 ‰ <span>δ</span><sup>18</sup>O up to -2.4 ‰ <span>δ</span><sup>18</sup>O with a mean <em>d-</em>excess of 13.2 ‰. By the beginning of May, the Intertropical Convergence Zone reaches Costa Rica resulting in a notable depletion in isotope ratios (up to -10.4 ‰ <span>δ</span><sup>18</sup>O and -76.2 ‰ <span>δ</span><sup>2</sup>H). During the wet season, <span>δ</span><sup>18</sup>O composition averaged -6.1 ‰ <span>δ</span><sup>18</sup>O and -38.5 ‰ <span>δ</span><sup>2</sup>H with a mean <em>d-</em>excess of 9.9 ‰. HYSPLIT air mass back trajectories indicate a strong influence on the origin of precipitation of two main moisture transport mechanisms, the northeasterly (January-May) and southwesterly (May-November) trade winds. Small seasonal variations were observed in the isotopic composition of surface water throughout the year with mean values ranging from -3.9 ‰ <span>δ</span><sup>18</sup>O (dry season, n=19) up to -4.8 ‰ <span>δ</span><sup>18</sup>O (wet season, n=13). Groundwater samples exhibited a similar trend with more depleted composition during the wet season (-5.2 ‰ <span>δ</span><sup>18</sup>O and -29.8 ‰ <span>δ</span><sup>2</sup>H). Overall, the marine isotopic composition measured in meteoric water at Cocos Island serves to better delineate the isotopic contribution of Pacific moisture towards the Central America Isthmus. It also provides a valuable isotopic reference to discriminate from orographic distillation and Caribbean enriched rainfall inputs in continental studies.</p><div> </div>

Sea of Storms: A History of Hurricanes in the Greater Caribbean from Columbus to Katrina, by Stuart B. Schwartz

Sea of Storms: A History of Hurricanes in the Greater Caribbean from Columbus to Katrina, by Stuart B. Schwartz. Lawrence Stone Lectures. Princeton, Princeton University Press, 2015. 472 pp. $35.00 US (cloth). Stuart Schwartz's Sea of Storms is an ambitious book. The geography of the book, the entire circum-Caribbean region, covers a variety of distinct nations and cultures--independent islands, small nations on the isthmus of Central America, and the Caribbean regions of Venezuela, the United States and Mexico--with complicated links to imperial rulers and each other. Chronologically, five centuries of hurricane history includes thousands of distinct events. As natural disasters go, hurricanes are complicated in their causes, predictability, and outcomes. Creating a cohesive narrative from his unwieldy topic, and doing so in an engaging lively manner, is a notable achievement. Schwartz mainly concentrates on three main themes: the social-political implications for societies in a hurricane-prone region, changes in the nature and understanding of hurricanes over the five centuries since Europeans first established a presence in the Caribbean, and environmental causes and results of hurricanes. The book's methodology relies on inserting hurricanes into the fairly accepted periodization and issues of Caribbean historiography. Schwartz judiciously does not assert that the experience with hurricanes was the causal factor shaping Caribbean societies; rather, he convincingly demonstrates that Caribbean history and society cannot be understood without taking account of these storms. Hurricanes are the ubiquitous known unknowns of the Caribbean. They will occur every year from late summer through autumn, with unknown strength, points of origin, paths, and numbers. One of the implicit conclusions of Sea of Storms is that, everywhere and always, planning for and response to these disasters is political. Ideology, expediency, and personality have determined whether a governing state will learn from past storms to build and provide in anticipation of future storms or will offer aid in recovery. Political actors have used hurricanes to build legitimacy and supportive constituencies when useful; others have left natural disaster to the realms of charity or individual resiliency. Juxtaposing the Cuban government's response to storms during the period from 1996 to 2002 with the US government's actions during Katrina in 2005 (chapter eight) is a persuasive tactic to argue that wealth and resources do not determine a state's preparation for, or response to, disaster. The state forms only part of the institutional story of hurricanes. We also learn about the nature of charity and community by inserting hurricanes into Caribbean history. Philanthropic debates about the nature and targets of charity got thorough workouts from storms. Community response has been more constant than that of other social institutions. With these responses, Schwartz demonstrates the effects of hurricanes on shaping Caribbean societies. He also emphasizes that empathetic and constructive community response has always been the norm, much more than the exaggerated narrative of social breakdown (p. 327) that grabs attention. Sea of Storms demonstrates that the experience of hurricanes was not uniformly diverse across time; Schwartz finds systematic change in important aspects of dealing with hurricanes. …

Monitoring Spatiotemporal Surface Soil Moisture Variations During Dry Seasons in Central America With Multisensor Cascade Data Fusion

Soil moisture is a critical element in the hydrological cycle, which is intimately tied to agriculture production, ecosystem integrity, and hydrological cycle. Point measurements of soil moisture samples are laborious, costly, and inefficient. Remote sensing technologies are capable of conducting soil moisture mapping at the regional scale. The advanced microwave scanning radiometer on earth observing system (AMSR-E) provides global surface soil moisture (SSM) products with the spatial resolution of 25 km which is not sufficient enough to meet the demand for various local-scale applications. This study refines AMSR-E SSM data with normalized multiband drought index (NMDI) derived from the moderate resolution imaging spectroradiometer (MODIS) data to provide fused SSM product with finer spatial resolution that can be up to 1 km. Practical implementation of this data fusion method was carried out in Central America Isthmus region to generate the SSM maps with the spatial resolution of 1 km during the dry seasons in 2010 and 2011 for various agricultural applications. The calibration and validation of the SSM maps based on the fused images of AMSR-E and MODIS yielded satisfactory agreement with in situ ground truth data pattern wise.

La evolución de las comunidades de moluscos y su relación con el desarrollo geológico del sur de América Central

Mollusks fossil communities found is southerm Central America developed in accordance to tectonic, and hence favorable enviromental conditions of the Isthmus evolution. The initial stage of the island arc, during the Late Cretaceous, determined the apperance of rudistic bioherms on the shallow platforms surrounding the islands. Later, during the Early Tertiary the predominance of deeper sedimentary environments and the intensive volcanic activity restricted the mollusks populations to rather small groups. During the Oligocene to Miocene, the island are evolved to a number of island of greater area separated by narrow channels. This provided an apropiate environment for the development of homogeneous malacological faunistic communities with hihg diversity of species. The final uplift of the Central America isthmus during the Pliocene stopped the faunistic intercahnge between Pacif and Caribeean communities which decrease diversification of species at the Caribeean side.

Unhinging an indenter: A new tectonic model for the internal deformation of Panama

[1] New paleoseismic results from Panama, conducted as part of the seismic hazard assessment for the expansion of the Panama Canal, have led to a reevaluation of the tectonic framework and geologic history of the isthmus of Central America. We propose a soft block indenter model wherein the collision of Central America and South America has resulted in significant internal deformation of the isthmus. Deformation is accommodated by both rapid slip on conjugate strike-slip faults within the isthmus, as well as the generally assumed flexure and northward buckling of Panama. The model is kinematically self-consistent in that there are little or no space problems created with 3 Ma of retrodeformation. Sparse GPS velocity data are consistent to within uncertainties with the new geologically constrained block model, supporting the rapid and extensive internal deformation of Panama. Together, the paleoseismologic and geodetic data suggest that central Panama is an area of high risk due to earthquakes, which is consistent with the historical occurrence of several moderate to large earthquakes in this region. However, this is generally counter to the current perception in central Panama where most people live and where there have been no large, damaging earthquakes for over 100 years.

Discordant patterns of evolutionary differentiation in two Neotropical treefrogs

Comparative studies of codistributed taxa test the degree to which historical processes have shaped contemporary population structure. Discordant patterns of lineage divergence among taxa indicate that species differ in their response to common historical processes. The complex geologic landscape of the Isthmus of Central America provides an ideal setting to test the effects of vicariance and other biogeographic factors on population history. We compared divergence patterns between two codistributed Neotropical frogs (Dendropsophus ebraccatus and Agalychnis callidryas) that exhibit colour pattern polymorphisms among populations, and found significant differences between them in phenotypic and genetic divergence among populations. Colour pattern in D. ebraccatus did not vary with genetic or geographic distance, while colour pattern co-varied with patterns of gene flow in A. callidryas. In addition, we detected significant species differences in the phylogenetic history of populations, gene flow among them, and the extent to which historical diversification and recent gene flow have been restricted by five biogeographic barriers in Costa Rica and Panama. We inferred that alternate microevolutionary processes explain the unique patterns of diversification in each taxon. Our study underscores how differences in selective regimes and species-typical ecological and life-history traits maintain spatial patterns of diversification.

The Dutch and the Company of Scotland trading to Africa and the Indies

The Company of Scotland trading to Africa and the Indies (Darien Company) was established by an act of parliament in 1695 as an overseas trading vehicle to boost the Scottish economy. Between 1698 and 1700 the Company unsuccessfully attempted to establish a colony at Darien on the isthmus of Central America. There were a number of Dutch influences on the Company and contacts between the Company and the Dutch. The economic success of the Dutch provided a model for the Scots and Dutch capital markets influenced Scottish exiles who became shareholders and directors of the Company. Amsterdam was a magnet for a significant amount of the Company's capital, a centre where ships were bought and constructed, a source of manpower, the centre of the Company payment system on the continent and a potential source of capital. Paradoxically the Dutch benefited from the cash of Scottish investors and facilitated the construction of the Company's fleet but frustrated its efforts to raise more capital.

A phytogeographic analysis of the woody elements of New World savannas

An analysis was made of the floristic composition of 45 savanna sites located throughout the southern neoarctic and neotropics. A total of 533 woody species were recorded from published and reliable unpublished floristic lists; of these, 234 species (44%) were from 10 Brazilian cerrado sites, with 187 (80%) of them restricted to the cerrado biome. The cerrados were clearly shown to be the most diverse New World savanna system with a high degree of endemism. The data were analysed using two multivariate techniques: TWINSPAN and DCA. Four phytogeographic zones were identified: Central Brazil and Bolivia extending to Southern Amazonia; north of Amazonia extending across the isthmus of Central America and including the Caribbean; Belize, Guatemala and Southern Mexico; and north of the Mexican Plateau. The analyses revealed gradients of floristic variation associated with latitude and longitude, and showed the great heterogeneity of savanna vegetation.

Rotation of the Chortís block causes dextral slip on the Guayape fault

The Chortís block is undergoing deformation as a direct result of large‐magnitude sinistral strike‐slip faulting on the North America‐Caribbean plate boundary. We have studied the Chortís block using geologic mapping, remote imagery, and earthquake seismology to evaluate the effect that large‐magnitude strike‐slip faulting has on an adjacent microcontinental block. In the eastern part of the Chortís block, recent geologic mapping has shown that the northeast striking Guayape fault is dextral instead of sinistral as previously assumed. Because this is a major fault that cuts most of the Central America isthmus, the new evidence for dextral slip necessitates a reinterpretation of the active tectonics of the Chortís block. The presence of several north trending rifts in the western part of the Chortís block has led previous workers to propose that the Chortís block is divided into smaller, independently rotating blocks. We use earthquake seismology and remote imagery data to extend this interpretation to the central portion of the Chortís block. However, we have modified their model to account for dextral slip on the Guayape fault. We believe that rotation of the Chortís block causes dextral slip on the Guayape fault even though Central America is undergoing large sinistral displacement with respect to North America.

The recognition of new infant health paradigms in developing countries.

Costa Rica is situated in the Central America isthmus, with Panama and Nicaragua as its neighbours and surrounded by the Atlantic Ocean and the Pacific Ocean. Our country is not extensive, it has a territory 51,100 sq km and a population of 2·5 million. Among them, the rural population comprises 54% children under 15 years of age 36% and persons over 65 years 4%. Costa Rica was discovered in 1520. It abolished slavery in 1813 and became independent from Spain in 1821. After that, death penalty and the army were also abolished in 1882 and 1949 respectively. Its political system is very similar to the Western democratic set-up. The election has been held through direct and secret vote since 1928. Men got the right to vote in 1889 and women were not granted franchise until 1948. It is held every four years and in it the president and two vice presidents for the Republic and 57 congressment are elected. There is judiciary which is headed by the Supreme Court of Justice. It is composed of 17 magistrates. The main sources of income of our country are coffee, bananas and sugar eventhough, during the last two decades, the government has put special emphasis on the development of small and medium size industries and the tourism programmes as well. Education is very important for our country. Our first university was set up in 1843 and in 1869 and 1907 primary school and coeducational high school respectively became universal and compulsory. We believe in democracy, freedom, social justice and respect for laws. These have been religiously observed and jealously defended by the Costa Ricans during the last 1100 years. The government has adopted neutrality as the only way to preserve our peace in disturbed Central America.

MARINE FAUNAL DOMINANCE AND MOLLUSCAN SHELL FORM.

One of the most important ecological problems facing mankind is predicting the effects of breaking down barriers on a large scale between previously separated marine or terrestrial biotas. While opinions on this subject are numerous and conflicting, few data are available and little predictive theory has been developed (see Elton, 1958; Remington, 1967; Rubinoff, 1968; Topp, 1969; Por, 1971; Vuilleumier, 1971; Fooden, 1972). In this paper I examine in a hypothetical way the possible consequences of a proposed sea-level canal across the Isthmus of Central America (Rubinoff, 1968; Topp, 1969) in the light of differences in shell architecture among shallowwater marine molluscan assemblages which I believe to reflect differences in the ability to withstand predation.

A TRANSISTHMIAN SEA-LEVEL CANAL FOR CENTRAL AMERICA: PROPOSALS AND PROSPECTS

Abstract By the end of this century the Panama Canal will have reached its maximum capacity of 50,000 ship transits a year. If the needs of future inter-oceanic commerce are to be met it is imperative that a new and expanded waterway across the Isthmus of Central America be created. A sea-level type canal would best serve the demands of twenty-first century shipping. Two techniques are feasible for such a project: conventional and nuclear excavation. Each technique boasts of certain advantages over the other, the conventional being safer while the nuclear is faster and cheaper. Five routes have been scrutinized as a potential canal site. Prior to any final determination of either digging procedure or route location, problems such as safety, regional ecology, canal currents, and diplomatic and political agreements must be resolved—with 1985 looming as the latest judicious date to commence excavation.

Map of the Isthmus of Darien

Panama is an elongated strip of land. In the west are the foothills of the Talamanca mountain range (known as the Tasabara mountains in Panama), where very active volcanoes such as the Baru volcano have emerged. Panama forms part of a tectonic microplate resting on the Caribbean and Nazca plates. The center of the country, where the interoceanic canal was built, is also the most depressed, sunken part of the country. From this point to the east, Panama forms an arc ending with the Darien province, which connects the isthmus of Central America to the continent of South America.

Further Considerations on the Great Isthmus of Central America

Further Considerations on the Great Isthmus of Central America

Considerations on the Great Isthmus of Central America

Considerations on the Great Isthmus of Central America