Parana River Delta Research Articles

Phylogeography and Pleistocene demographic history of the endangered marsh deer (Blastocerus dichotomus) from the Río de la Plata Basin

The marsh deer is the largest neotropical cervid with morphological and ecological adaptations to wetlands and riparian habitats. Historically, this now endangered species occupied habitats along the major river basins in South America, ranging from southern Amazonia into northern Argentina to the Parana river delta. This particularly close association with wetlands makes marsh deer an excellent species for studying the effects of Pleistocene climatic changes on their demographic and phylogeographic patterns. We examined mitochondrial DNA variation in 127 marsh deer from 4 areas distributed throughout the Rio de la Plata basin. We found 17 haplotypes in marsh deer from Brazil, Bolivia and Argentina that differed by 1–8 substitutions in a 601 bp fragment of mitochondrial control region sequence, and 486 bp of cytochrome b revealed only 3 variable sites that defined 4 haplotypes. Phylogeny and distribution of control region haplotypes suggest that populations close to the Pantanal area in central Brazil underwent a rapid population expansion and that this occurred approximately 28,000–25,000 years BP. Paleoclimatic data from this period suggests that there was a dramatic increase for precipitation in the medium latitudes in South America and these conditions may have fostered marsh deer’s population growth.

Synoptic features associated with critical water level rises in the Río de la Plata

AbstractThis study aims to describe the synoptic features that caused the water level in the Río de la Plata estuary to rise above critical levels between December 1989 and December 1998. Floods in the estuary can seriously affect the land beside the river from Punta Indio (35.22°S,57.17°W) to the Paraná delta, including the lowlands of Buenos Aires City.Surface pressure patterns associated with floods in the Río de la Plata estuary were obtained by using Quartimax rotated T‐mode Principal Component Analysis (PCA) of 1000 hPa geopotential heights. The PCA patterns and 1000 hPa composite and anomaly fields show two main causes for overflows in the Río de la Plata estuary. First, the presence of a surface anticyclone, located south of Buenos Aires province and over northern Patagonia; and, second, cyclogenesis over northeastern Argentina or over Uruguay. The two synoptic features are often present simultaneously.Two representative points were selected in the area under study: one over the continent at the Aeroparque meteorological station (34.34°S,58.25°W) and another over the ocean between 36°S,56°W and 36°S,50°W. Predominant 1000 hPa wind directions associated with overflows were SE at the former location and SSW at the latter.Based on the analysis of the obtained fields, the relationship between the estuary overflow and blocking situations and/or positive pressure anomalies over southern South America and adjacent seas was studied. The zonal circulation index (I), used to detect blocking actions, was found to be useful for identifying synoptic situations related to the estuary swelling. The probability of water level rises in the Río de la Plata with a blocking or I > 0 at 70°W is 0.48, 0.72, 0.78 and 0.73, for summer, autumn, winter and spring, respectively. When I > 0 is observed over the Atlantic at 40°W the probability of flooding is 0.16 for the whole year, but it decreases to 0.028 in autumn, winter and spring.These results and weather charts from different numerical prediction models show that alerts of possible Río de la Plata estuary overflow can be released five days in advance. Copyright © 2005 Royal Meteorological Society

Biodiversity and biogeographical implications of silica-scaled chrysophytes (Chrysophyceae and Synurophyceae) of the northeast wetlands of Argentina

Wetlands and water bodies in the Parana Delta River and Ibera System of northeast Argentina were studied for scaled chrysophytes. The Delta region of the Pa- rana River is composed of a series of braided channels, streams and lagoons that ex- tend over 17,500km2. Although the Delta is situated in the temperate zone, it experien- ces a more subtropical climate. The water ways of the Ibera System consist of inter- connected ponds, lagoons, and creeks covering approximately 12,000 km2. Twenty sites were sampled and their physico-chemical data measured. Twenty-seven species belonging to the genera Spinijeromonas, Paraphysomonas, Chrysosphaerella, Chryso- didymus, Mallomonas and Synura were recorded and in all cases the geographical dis- tribution of these taxa were significantly expanded. A new variety, Mallomonas pseu- docratis var. deltaensis, is described. Lastly, the colorless flagellate Gyromitus diso- matus was found to be abundant in sites from Ibera.

Paraná river delta wetlands soil microfungi

Summary The Parana River Delta soils are affected by seasonal flooding coupled with rapidly flowing water from the Parana River and by the de la Plata River estuary tidal regime which reduces the seasonality of the Parana River regime. The present study is the first investigation undertaken to determine the fungal composition of different site soils and to evaluate if flooding and flowing water energy induced differences on fungal community. Five sites were selected and three plots at each site along a topographical gradient were examined. From all soil samples, 23041 isolates belonging to 74 taxa were obtained. Talaromyces flavus and Eupenicillium brefeldianum were the most frequent species and present with high densities. Several taxa were soil or site specific. A black yeast, Pseudeurotium zonatum, Phialemonium dimorphosporum, Eladia saccula, Phialophara spp., Aspergillus japonicus, Eupenicillium abidjanum, Arachnotheca albicans, Fusarium oxysporum and Westerdykella spp. also were common. Correspondence analysis evidenced differences among sites characterized by a set of several species. The distribution of these species shows little or no relationship with the overlying vegetation. The low microfungal biomass, the high number of taxa by 100 isolates, and the mainly dematiaceous and cleistothecial forms suggest that these soil fungal communities are disturbed. Differences among fungal communities at each site could reflect difterent disturbance conditions derived from the effect of flooding and flowing water at the Upper, Medium and Lower Parana River Delta as well as the Rio de la Plata estuary tidal regime.

Management of Platypus sulcatus Chap. population during three years in Parana delta (Argentina), with chemical control

The purpose of this study is to observe and measure the behaviour of a fruit and forest tree borer, isolated in an adult poplar plantation. Along the poplar growing period a pyrethroid and carbamic derivate insecticides were employed, looking for a less harmgull effect on the environment. A plot of australian poplar, Populus deltoides cv. 'I:125/68', infested with the borer, was selected for the essay. The sequence of spray rotation during a period of three years was the next: cypermethrin, cypermethrin and carbaryl; carbaryl, carbaryl and cypermethrin; and control, control and control, for the first, second and third year respectively. Each spray was apllied in spring, just in the peak of infestation, spraying poplar stems and branches until seven meter height, showing the active borer gelleries pre and post treatments. An ANOVA and Tuckey test concluded that carbaryl and cypermethrin were effective with the doses employed in this work

A quantitative phytogeographic analysis of species richness in forest communities of the Paraná River Delta, Argentina

A biogeographic analysis of 26 species of trees and shrubs occurring in the Parana River Delta (32° to 34 °30′ South latitude, 58° to 61° West longitude, Argentina) was performed to study the floristic and structural differences among deltaic woodland communities. Traditionally these variations have been interpreted as a consequence of the differential influence of local island geomorphology and flood dynamics on floristic successions. We performed a cluster analysis of collection site, obtained maps showing the joint occurrence of the species of each community, and related species ranges with the presence of possible migration corridors. Results suggest that, in addition to local variations in topography and flood persistence, changes in floristic richness can be understood as a consequence of the differential efficiency of the Parana and Uruguay Rivers as migration corridors for tropical species into temperate latitudes. Geomorphical stability of riverbeds and fluvial dynamic differences between rivers are discussed in relation to how they may explain the more efficient migration of species along the flood plain of the Uruguay River compared to the Parana River. Results allow us to re-interpret the relative importance of both rivers in the establishment of tropical and subtropical species in temperate latitudes, and to add a regional explanation for the observed floristic heterogeneity.

Podosphaera leucotricha . [Distribution map

Abstract A new distribution map is provided for Podosphaera leucotricha (Ell. & Everh.) Salm. Hosts: Apple ( Malus pumila ), pear ( Pyrus communis ), medlar ( Mespilus germanica ), quince ( Cydonia oblonga ). Information is given on the geographical distribution in AFRICA, Angola, Ethiopia, Kenya, Libya, Morocco, South Africa, Tanzania, Zimbabwe, ASIA, Afghanistan, China, India, Iran, Iraq, Israel, Japan, Korea, Lebanon, Nepal, Pakistan, Saudi Arabia, Syria, Taiwan, Turkey, USSR, AUSTRALASIA & OCEANIA, Australia, New Zealand, EUROPE, Austria, Belgium, Britain & Northern Ireland, Bulgaria, Cyprus, Czechoslovakia, Denmark, Finland, France, Germany, Greece, Hungary, Irish Republic, Italy, Netherlands, Norway, Poland, Portugal, Romania, Sweden, Switzerland, USSR, Yugoslavia, NORTH AMERICA, Canada, Mexico, USA, CENTRAL AMERICA & WEST INDIES, Centr. America, Guatemala, SOUTH AMERICA, Argentina (Parana delta), Brazil, Chile, Colombia, Ecuador, Peru, Uruguay.

Phytophthora cinnamomi . [Distribution map

Abstract A new distribution map is provided for Phytophthora cinnamomi Rands Ananas, Cinchona, Cinnamomum. Hosts: Castanea, Persea, Pinus, Rhododendron, and others. Information is given on the geographical distribution in AFRICA, Cameroon, Congo, Guinea, Ivory Coast, Kenya, Morocco, South Africa, Rhodesia, Uganda, Zambia, ASIA, India (Madras) (Andhra Pradesh), Indonesia (Java, Sumatra), Peninsular Malaysia, (Sabah), Philippines, Turkey, USSR (Georgian SSR), Vietnam, AUSTRALASIA & OCEANIA, Australia, Cook Islands, Fiji, Hawaii, New Zealand, Okinawa, Papua New Guinea, EUROPE, Azores, Belgium, Britain, France (incl. Corsica), Germany, Greece, Irish Republic, Italy, Netherlands, Portugal, Spain, Switzerland, USSR (Black Sea region), Yugoslavia, CENTRAL AMERICA & WEST INDIES, Barbados, Belize, Costa Rica, Cuba, Dominican Republic, Guatemala, Honduras, Jamaica, Panama, Puerto Rico, St. Lucia, St. Vincent, Salvador, Trinidad, NORTH AMERICA, Canada (British Columbia), Mexico, USA, SOUTH AMERICA, Argentina (Parana delta), Bolivia, Brazil (Sao Paulo), (Brasilia), Chile, Colombia, Guyana, Peru, Venezuela.