scholarly journals ENSO-triggered floods in South America: correlation between maximum monthly discharges during strong events

Author(s):  
Federico Ignacio Isla

Abstract. ENSO-triggered floods altered completely the annual discharge of many watersheds of South America. Anomalous years as 1941, 1982–83, 1997–98 and 2015–16 signified enormous fluvial discharges draining towards the Pacific Ocean, but also to the Atlantic. These floods affected large cities built on medium-latitudinal Andes (Lima, Quito, Salta), but also those located at floodplains, as Porto Alegre, Blumenau, Curitiba, Asunción, Santa Fe and Buenos Aires. Maximum discharge months are particular and easily distinguished along time series from watersheds located at the South American Arid Diagonal. At watersheds conditioned by precipitations delivered from the Atlantic or Pacific anti-cyclonic centers, the ENSO-triggered floods are more difficult to discern. The floods of 1941 affected 70,000 inhabitants in Porto Alegre. In 1983, Blumenau city was flooded during several days; and the Paraná River multiplied 15 times the width of its middle floodplain. That year, the Colorado River in Northern Patagonia connected for the last time to the Desagûadero – Chadileuvú – Curacó system and its delta received saline water for the last time. During strong ENSO years the water balances of certain piedmont lakes of Southern Patagonia are modified as the increases in snow accumulations cause high water levels, with a lag of 13 months. The correlation between the maximum monthly discharges of 1982–83 and 1997–98 at different regions and watersheds indicates they can be forecasted for future floods triggered by same phenomena. South American rivers can be classified therefore into ENSO-affected and ENSO-dominated for those within the Arid Diagonal that are exclusively subject to high discharges during those years.

1984 ◽  
Vol 3 (2) ◽  
pp. 160-163 ◽  
Author(s):  
Frederick Burkhardt

Darwin's letters and some rough notes found in his field notebooks of 1835 confirm the statement in his Autobiography that he had formulated his theory of coral reef formation before the Beagle left South America and before he had seen a coral reef. His geological observations having convinced him of the elevation of the South American continent, Darwin predicted that evidence of a compensatory gradual subsidence of the Pacific Ocean floor would be found in the existence of shallow-water coral genera in the Pacific reef formations. The first draft of the theory was written on board the Beagle shortly after seeing the reefs of Moorea in November 1835. After visiting the Cocos (Keeling) Islands he wrote a summary of his view in a letter of April 1838, in which he expressed his conviction that he had found an explanation which would "put some of the facts in a more simple and connected point of view, than that in which they have hitherto been considered".


2021 ◽  
Author(s):  
Josefina Gutiérrez ◽  
Mauricio Seguel ◽  
Pablo Saenz‐Agudelo ◽  
Gerardo Acosta‐Jamett ◽  
Claudio Verdugo

2022 ◽  
Author(s):  
Hector Luis D’Antoni ◽  
Lidia Susana Burry ◽  
Patricia Irene Palacio ◽  
Matilde Elena Trivi ◽  
Mariano Somoza

Phytotaxa ◽  
2017 ◽  
Vol 319 (3) ◽  
pp. 254 ◽  
Author(s):  
M. ÁNGELES ALONSO ◽  
MANUEL B. CRESPO ◽  
HELMUT FREITAG

The name Salicornia cuscoensis given to a plant from high Andean saltmarshes near Cusco [Cuzco] and Ayacucho, Peru (South America) is validated by a diagnosis and description. The main morphological characters that separate S. cuscoensis from other closely related species are creeping habit, delicate branches, inflorescence of short and thin spikes, and seed indumentum. The new species clearly differs from other perennial Salicornia taxa growing in high Andean saltmarshes such as S. pulvinata and S. andina. The former forms small compact cushions producing very short, few-flowered inflorescences. The latter shows woody stems and forms larger rounded carpets. Morphologically, S. cuscoensis is also similar to S. magellanica, a species growing along the seashore in southern Patagonia and Tierra del Fuego, but the latter has shorter and wider inflorescences and larger seeds with a different type and arrangement of indumentum. Molecular analyses also supported the separation of S. cuscoensis. Data on habitat, distribution and phylogenetic relationships are presented for the new species and its relatives, and an identification key is given for the South American taxa of the genus Salicornia.


2020 ◽  
Vol 7 (2) ◽  
pp. 191558 ◽  
Author(s):  
Michael B. Herrera ◽  
Spiridoula Kraitsek ◽  
Jose A. Alcalde ◽  
Daniel Quiroz ◽  
Herman Revelo ◽  
...  

Chickens ( Gallus gallus domesticus ) from the Americas have long been recognized as descendants of European chickens, transported by early Europeans since the fifteenth century. However, in recent years, a possible pre-Columbian introduction of chickens to South America by Polynesian seafarers has also been suggested. Here, we characterize the mitochondrial control region genetic diversity of modern chicken populations from South America and compare this to a worldwide dataset in order to investigate the potential maternal genetic origin of modern-day chicken populations in South America. The genetic analysis of newly generated chicken mitochondrial control region sequences from South America showed that the majority of chickens from the continent belong to mitochondrial haplogroup E. The rest belongs to haplogroups A, B and C, albeit at very low levels. Haplogroup D, a ubiquitous mitochondrial lineage in Island Southeast Asia and on Pacific Islands is not observed in continental South America. Modern-day mainland South American chickens are, therefore, closely allied with European and Asian chickens. Furthermore, we find high levels of genetic contributions from South Asian chickens to those in Europe and South America. Our findings demonstrate that modern-day genetic diversity of mainland South American chickens appear to have clear European and Asian contributions, and less so from Island Southeast Asia and the Pacific Islands. Furthermore, there is also some indication that South Asia has more genetic contribution to European chickens than any other Asian chicken populations.


2015 ◽  
Author(s):  
Eduardo A B Almeida ◽  
Fábio B Quinteiro

Neopasiphaeinae bees (Apoidea: Colletidae) are well known for their Amphinotic distribution in the Australian and Neotropical regions. Affinities between colletid taxa in Australia and South America have been speculated for decades, and have been confirmed by recent phylogenetic hypotheses that indicate a biogeographic scenario compatible with a trans-Antarctic biotic connection during the Paleogene. Despite this proximity, no species occurs on both sides of the Pacific Ocean, but the Neotropical species Hoplocolletes ventralis (Friese, 1924), which was described as an Australian taxon due to an error in the specimen labels. This mistake was recognized by C.D.Michener 50 years ago. We herein report that the same labeling problem also happened with Dasycolletes chalceus Friese, 1924, which remained as a tentatively placed species in the Australian genus Leioproctus until now. Moreover, Dasycolletes chalceus is interpreted as a synonym of Dasycolletes ventralis. We also provide a revised diagnosis for Hoplocolletes, describe the male of H. ventralis in detail for the first time, including a comparative study of its genitalia and associated sterna.


PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3401 ◽  
Author(s):  
Alejandra Rumi ◽  
Roberto Eugenio Vogler ◽  
Ariel Aníbal Beltramino

Schistosomiasis remains a major parasitic disease, endemic in large parts of South America. Five neotropical species of Biomphalaria have been found to act as intermediate hosts of Schistosoma mansoni in natural populations, while others have been shown to be susceptible in experimental infections, although not found infected in the field. Among these potential intermediate hosts, Biomphalaria peregrina represents the most widespread species in South America, with confirmed occurrence records from Venezuela to northern Patagonia. In this study, we report the southernmost record for the species at the Pinturas River, in southern Patagonia, which finding implies a southward reassessment of the limit for the known species of this genus. The identities of the individuals from this population were confirmed through morphological examination, and by means of two mitochondrial genes, cytochrome oxidase subunit I (COI) and 16S-rRNA. With both markers, phylogenetic analyses were conducted in order to compare the genetic background of individuals from the Pinturas River with previously genetically characterized strains of B. peregrina from various South-American locations. In addition, we produced a potential distribution model of B. peregrina in South America and identified the environmental variables that best predict that distribution. The model was estimated through a maximum entropy algorithm and run with occurrence points obtained from several sources, including the scientific literature and international databases, along with climatic and hydrographic variables. Different phylogenetic analyses with either the COI or 16S-rRNA sequences did not conflict, but rather gave very similar topological organizations. Two major groups were identified, with sequences from the Pinturas River grouping together with haplotypes from subtropical and temperate regions. The model developed had a satisfactory performance for the study area. We observed that the areas with higher habitat suitability were found to be mainly linked to subtropical and temperate regions of South America between 15° and 45° south latitude, with different moderate- and low-suitability areas outside this range. We also identified the coldest temperatures as the main predictors of the potential distribution of this snail. Susceptibility surveys would be required to evaluate if southern populations of B. peregrina still retain their potential as intermediate hosts of S. mansoni.


2021 ◽  
pp. 6
Author(s):  
Pavel Kuchinov

Since the XXI century the majority of South American countries call to create large integration transport corridors that provide interconnections between different parts of the region. The authors studied the projects of multimodal transport corridors implemented by the South American organization IIRSA (Initiative for the Integration of the Regional Infrastructure of South America), the purpose of which is the connection of the coasts of two oceans: the Atlantic and the Pacific. Analyzing the situation related to the latest Chinese investment and construction projects in South America within the framework of The Belt and Road Initiative, the authors question the feasibility and prospects the effectiveness of IIRSA's priority megaprojects. According to the developers, such initiatives, embodying infrastructure integration in the region, should contribute not only to the economic growth of the participating countries, but also to greater access to the global market for finance and services. The authors consider, although, that it is likely that this initiative risks being transformed into a tool for realizing China's economic and political interests.


Author(s):  
Stewart A. Weaver

‘Exploration and the Enlightenment ’ considers a “Second Great Age of Discovery” that came about during the eighteenth-century Enlightenment. It began with the 1735 Geodesic Mission to the Equator, designed to ascertain the true figure of the Earth. Never before had so large and learned a group of Europeans headed into the remote interior of the New World for an expressly scientific purpose or the results of an expedition been so elaborately publicized in maps, journals, and official reports back home. This trip is seen as the prototype of the modern exploring expedition. The voyages of Captain James Cook in the Pacific Ocean and Alexander von Humboldt's trip to South America provide further examples of Enlightenment exploration.


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