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1

Amazon River  

... the Rio Solimoes and the Rio Negro converge to form the Amazon River. This image from the Multi-angle Imaging SpectroRadiometer (MISR) ... date:  Jul 23, 2000 Images:  Amazon River location:  South America thumbnail:  ...

2013-04-17

2

Amazon River  

article title:  Mouth of the Amazon River     View Larger Image ... Flowing over 6450 kilometers eastward across Brazil, the Amazon River originates in the Peruvian Andes as tiny mountain streams that ...

2013-04-17

3

The Amazon, measuring a mighty river  

USGS Publications Warehouse

The Amazon, the world's largest river, discharges enough water into the sea each day to provide fresh water to the City of New York for over 9 years. Its flow accounts for about 15 percent of all the fresh water discharged into the oceans by all the rivers of the world. By comparison, the Amazon's flow is over 4 times that of the Congo River, the world's second largest river. And it is 10 times that of the Mississippi, the largest river on the North American Continent.

1967-01-01

4

Numerical modeling of the Amazon River plume  

Microsoft Academic Search

Marine circulation above the northern Brazilian continental shelf is subject to energetic forcing factors of various origins: high water buoyancy fluxes induced by the Amazon River freshwater discharge, a strong coastal current associated with a mesoscale current (North Brazil Current (NBC)), a forcing by semidiurnal tide and by Northeast or Southeast trade winds according to the season. Using a three-dimensional

Oumarou Nikiema; Jean-Luc Devenon; Malika Baklouti

2007-01-01

5

Tectonics and paleogeography along the Amazon river  

Microsoft Academic Search

The main structural and geomorphological features along the Amazon River are closely associated with Mesozoic and Cenozoic tectonic events.The Mesozoic tectonic setting is characterised by the Amazonas and Marajó Basins, two distinct extensional segments. The Amazonas Basin is formed by NNE–SSW normal faults, which control the emplacement of dolerite dykes and deposition of the sedimentary pile. In the more intense

João Batista Sena Costa; Ruth Léa Bemerguy; Yociteru Hasui; Maur??cio da Silva Borges

2001-01-01

6

Biogeochemistry of carbon in the Amazon River  

Microsoft Academic Search

Depth-integrated, discharge-weighted water samples were collected over 1,800km ofthe Amazon River on eight cruises at different stages of the hydrograph, 1982-1984. Fine (FPOC, 163 pm) and coarse (CPOC, > 63 rm) particulate organic carbon as weight percentage of suspended sediment varied between 0.9-1.5% for FPOC and 0.5-3.49\\/o for CPOC. Concentrations of FPOC ranged from 5 mg liter-' upriver to 2

JEFFREY E. RICHEY; JOHN I. HEDGES; ALLAN H. DEVOL; PAUL D. QUAY; REYNALDO VICTORIA; LUIZ MARTINELLI; BRUCE R. FORSBERG

1990-01-01

7

Size distribution of Amazon River bed sediment  

USGS Publications Warehouse

The first recorded observations of bed material of the Amazon River were made in 1843 by Lt William Lewis Herndon of the US Navy, when he travelled the river from its headwaters to its mouth, sounding its depths, and noting the nature of particles caught in a heavy grease smeared to the bottom of his sounding weight1. He reported the bed material of the river to be mostly sand and fine gravel. Oltman and Ames took samples at a few locations in 1963 and 1964, and reported the bed material at O??bidos, Brazil, to be fine sands, with median diameters ranging from 0.15 to 0.25 mm (ref. 2). We present here a summary of particle-size analyses of samples of streambed material collected from the Amazon River and its major tributaries along a reach of the river from Iquitos in Peru, ???3,500 km above Macapa?? Brazil, to a point 220 km above Macapa??3. ?? 1980 Nature Publishing Group.

Nordin, C.F.; Meade, R.H.; Curtis, W.F.; Bosio, N.J.; Landim, P.M.B.

1980-01-01

8

Analysis of River Widths in the Amazon River Basin  

NASA Astrophysics Data System (ADS)

Rivers play a central role in the global hydrologic cycle, connecting atmospheric fluxes to soil moisture and groundwater storage through the circulation of water and transport of sediments from upland catchments to coastal settings over the landscape. River form on the regional-scale depends substantially on the variations in climate, drainage basin area, human activity, and substrate. Past studies of river form have focused mainly on small systems or network-form descriptions, rather than examining regional-scale continuous river morphology. This study represents the first-ever observational data set of continuous measurement of river widths in the Amazon River basin that are as wide as 50 meters or more. The widths are calculated using the RivWidth algorithm, which automatically calculates continuous river widths from satellite-derived water masks. We used Landsat TM and ETM+ images due to their long historical record, high spatial resolution, and wide global coverage. A total of 263 satellite images acquired during June to September, whenever possible, were used in creating the mask of Amazon River basin. A frequency analysis of river widths shows the wide variability in the distribution of complex-channels in the Amazon basin. The resulting map of river widths, when linked with Digital Elevation Models, can serve as an important tool in evaluating the basic control mechanisms on river formation and improve understanding of key relationships between width and variables such as basin area, lithology, climate, and human influence. The resulting width dataset will also be a significant contribution to the nascent Global River Width Database (GRWD) in the future.

Kustu, M. D.; Pavelsky, T. M.

2012-12-01

9

Chemical and physical denudation in the Amazon River Basin  

Microsoft Academic Search

We present major and trace element data on the suspended and dissolved phases of the Amazon River and its main tributaries. The Sr isotopic composition of the dissolved load is also reported. Special attention is paid to the abundances of REE and to their fractionation between the dissolved and suspended phase. The rivers of the Amazon Basin are among the

Jérôme Gaillardet; Bernard Dupre; Claude J. Allegre; Philippe Négrel

1997-01-01

10

Amazon River Discharge and Climate Variability: 1903 to 1985  

Microsoft Academic Search

Reconstruction of an 83-year record (1903 to 1985) of the discharge of the Amazon River shows that there has been no statistically significant change in discharge over the period of record and that the predominant interannual variability occurs on the 2- to 3-year time scale. Oscillations of river discharge predate significant human influences in the Amazon basin and reflect both

Jeffrey E. Richey; Carlos Nobre; Clara Deser

1989-01-01

11

Backwater effects in the Amazon River basin of Brazil  

Microsoft Academic Search

The Amazon River mainstem of Brazil is so regulated by differences in the timing of tributary inputs and by seasonal storage of water on floodplains that maximum discharges exceed minimum discharges by a factor of only 3. Large tributaries that drain the southern Amazon River basin reach their peak discharges two months earlier than does the mainstem. The resulting backwater

Robert H. Meade; José M. Rayol; Sylvio C. Da Conceicão; José R. G. Natividade

1991-01-01

12

Radium and barium in the Amazon River system  

SciTech Connect

Data for /sup 226/Ra and /sup 228/Ra in the Amazon River system show that the activity of each radium isotope is strongly correlated with barium concentrations. Two trends are apparent, one for rivers which drain shield areas and another for all other rivers. These data suggest that there has been extensive fractionation of U, Th, and Ba during weathering in the Amazon basin. The /sup 226/Ra data fit a flux model for the major ions indicating that /sup 226/Ra behaves conservatively along the main channel of the Amazon River.

Moore, W.S.; Edmond, J.M.

1984-03-20

13

Amazon River investigations, reconnaissance measurements of July 1963  

USGS Publications Warehouse

The first measurements of the flow of the Amazon River were made in July 1963 as a joint project of the University of Brazil, the Brazilian Navy, and the U.S. Geological Survey. The discharge of the Amazon River at Obidos was 7,640,000 cfs at an annual flood stage somewhat lower than the average. For comparison the maximum known discharge of the Mississippi River at Vicksburg is about 2,300,000 cfs. Dissolved-solids concentrations and sediment loads of the Amazon River and of several major tributaries were found to be low.

Oltman, Roy Edwin; Sternberg, H. O'R.; Ames, F.C.; Davis, L.C.

1964-01-01

14

Tectonics and paleogeography along the Amazon river  

NASA Astrophysics Data System (ADS)

The main structural and geomorphological features along the Amazon River are closely associated with Mesozoic and Cenozoic tectonic events. The Mesozoic tectonic setting is characterised by the Amazonas and Marajó Basins, two distinct extensional segments. The Amazonas Basin is formed by NNE-SSW normal faults, which control the emplacement of dolerite dykes and deposition of the sedimentary pile. In the more intense tectonic phase (mid-Late Cretaceous), the depocentres were filled with fluvial sequences associated with axial drainage systems, which diverge from the Lower Tapajós Arch. During the next subsidence phase, probably in the Early Tertiary, and under low rate extension, much of the drainage systems reversed, directing the paleo-Amazon River to flow eastwards. The Marajó Basin encompasses NW-SE normal faults and NE-SW strike-slip faults, with the latter running almost parallel to the extensional axes. The normal faults controlled the deposition of thick rift and post-rift sequences and the emplacement of dolerite dykes. During the evolution of the basin, the shoulder (Gurupá Arch) became distinct, having been modelled by drainage systems strongly controlled by the trend of the strike-slip faults. The Arari Lineament, which marks the northwest boundary of the Marajó Basin, has been working as a linkage corridor between the paleo and modern Amazon River with the Atlantic Ocean. The neotectonic evolution since the Miocene comprises two sets of structural and geomorphological features. The older set (Miocene-Pliocene) encompasses two NE-trending transpressive domains and one NW-trending transtensive domain, which are linked to E-W and NE-SW right-lateral strike-slip systems. The transpressive domains display aligned hills controlled by reverse faults and folds, and are separated by large plains associated with pull-apart basins along clockwise strike-slip systems (e.g. Tupinambarana Lineament). Many changes were introduced in the landscape by the transpressive and transtensive structures, such as the blockage of major rivers, which evolved to river-lakes, transgression of the sea over a large area in the Marajó region, and uplift of long and narrow blocks that are oblique to the trend of the main channel. The younger set (Pliocene-Holocene) refers to two triple-arm systems of rift/rift/strike-slip and strike-slip/strike-slip/rift types, and two large transtensive segments, which have controlled the orientation of the modern drainage patterns.

Costa, João Batista Sena; Léa Bemerguy, Ruth; Hasui, Yociteru; da Silva Borges, Maurício

2001-09-01

15

Radium and barium in the Amazon River system  

Microsoft Academic Search

Data for ²²⁶Ra and ²²⁸Ra in the Amazon River system show that the activity of each radium isotope is strongly correlated with barium concentrations. Two trends are apparent, one for rivers which drain shield areas and another for all other rivers. These data suggest that there has been extensive fractionation of U, Th, and Ba during weathering in the Amazon

Willard S. Moore; John M. Edmond

1984-01-01

16

River dynamics and the diversity of Amazon lowland forest  

Microsoft Academic Search

We suggest here that large-scale natural forest disturbance and primary succession in the lowland rainforests of the Peruvian Amazon is caused by lateral erosion and channel changes of meandering rivers. Our results indicate that in the upper Amazon region, primary succession on newly deposited riverine soils is a major mode of forest regeneration. Landsat imagery analyses show that 26.6% of

Jukka Salo; Risto Kalliola; Ilmari Häkkinen; Yrjö Mäkinen; Pekka Niemelä; Maarit Puhakka; Phyllis D. Coley

1986-01-01

17

Coagulation and settling of Amazon River suspended sediment  

Microsoft Academic Search

Sampling of the water column on the Amazon continental shelf was conducted in June July 1983, and shipboard measurements of the particle size distribution were accomplished utilizing techniques that permit measurement of flocs. These data indicated a volumetric concentration maximum about 100 km offshore from the Amazon River mouth, with maxima of the mean particle size in suspension in the

Ronald J. Gibbs; Lohit Konwar

1986-01-01

18

Backwater effects in the Amazon River basin of Brazil  

NASA Astrophysics Data System (ADS)

The Amazon River mainstem of Brazil is so regulated by differences in the timing of tributary inputs and by seasonal storage of water on floodplains that maximum discharges exceed minimum discharges by a factor of only 3. Large tributaries that drain the southern Amazon River basin reach their peak discharges two months earlier than does the mainstem. The resulting backwater in the lowermost 800 km of two large southern tributaries, the Madeira and Purús rivers, causes falling river stages to be as much as 2 3 m higher than rising stages at any given discharge. Large tributaries that drain the northernmost Amazon River basin reach their annual minimum discharges three to four months later than does the mainstem. In the lowermost 300 400 km of the Negro River, the largest northern tributary and the fifth largest river in the world, the lowest stages of the year correspond to those of the Amazon River mainstem rather than to those in the upstream reaches of the Negro River.

Meade, Robert H.; Rayol, José M.; da Conceicão, Sylvio C.; Natividade, José R. G.

1991-09-01

19

Backwater effects in the Amazon River basin of Brazil  

USGS Publications Warehouse

The Amazon River mainstem of Brazil is so regulated by differences in the timing of tributary inputs and by seasonal storage of water on floodplains that maximum discharges exceed minimum discharges by a factor of only 3. Large tributaries that drain the southern Amazon River basin reach their peak discharges two months earlier than does the mainstem. The resulting backwater in the lowermost 800 km of two large southern tributaries, the Madeira and Puru??s rivers, causes falling river stages to be as much as 2-3 m higher than rising stages at any given discharge. Large tributaries that drain the northernmost Amazon River basin reach their annual minimum discharges three to four months later than does the mainstem. In the lowermost 300-400 km of the Negro River, the largest northern tributary and the fifth largest river in the world, the lowest stages of the year correspond to those of the Amazon River mainstem rather than to those in the upstream reaches of the Negro River. ?? 1991 Springer-Verlag New York Inc.

Meade, R.H.; Rayol, J.M.; Da Conceicao, S.C.; Natividade, J.R.G.

1991-01-01

20

Hydrodynamic modelling of the Amazon River: Factors of uncertainty  

NASA Astrophysics Data System (ADS)

Hydrodynamic modelling of Amazonian rivers is still a difficult task. Access difficulties reduce the possibilities to acquire sufficient good data for the model calibration and validation. Current satellite radar technology allows measuring the altitude of water levels throughout the Amazon basin. In this study, we explore the potential usefulness of these data for hydrodynamic modelling of the Amazon and Napo Rivers in Peru. Simulations with a 1-D hydrodynamic model show that radar altimetry can constrain properly the calibration and the validation of the model if the river width is larger than 2500 m. However, sensitivity test of the model show that information about geometry of the river channel and about the water velocity are more relevant for hydrodynamic modelling. These two types of data that are still not easily available in the Amazon context.

Chávarri, Eduardo; Crave, Alain; Bonnet, Marie-Paule; Mejía, Abel; Santos Da Silva, Joecila; Guyot, Jean Loup

2013-07-01

21

Downstream Amazon river dynamics under oceanic tide influence  

Microsoft Academic Search

Effect of oceanic tide over downstream Amazon river dynamics has been monitored between 1999 and 2001. River topography and bathymetry has been determined, tide induced water levels fluctuations have been monitored at eleven gauging stations along a 1100 km long fluvial reach, water discharges fluctuations along a tide cycle have been measured at 9 sections during low, medium and high

P. Kosuth; A. Larque; M. Soussa da Silva; N. Filizola

2003-01-01

22

Biological Uptake of Dissolved Silica in the Amazon River Estuary  

Microsoft Academic Search

Approximately 25 percent of the dissolved silica carried by the Amazon River is depleted through diatom production in the inner estuary. Annual production of opaline frustules is estimated to be 15 million tons. However, few diatoms accumulate in modern shelf sediments and chemical recycling appears to be slight. Instead, many frustules apparently are transported landward into the river system, where

John D. Milliman; Edward Boyle

1975-01-01

23

Seasonal sediment storage on mudflats adjacent to the Amazon River  

Microsoft Academic Search

210Pb and 234Th activity profiles in sediment cores from underconsolidated mudflats 300 km downdrift of the Amazon river mouth record an ephemeral surface layer of fine-grained sediment up to 1.5 m thick. This layer contains about l.5 × 108 tons of Amazon sediment deposited rapidly (~1 cm\\/d) from a fluid-mud suspension (10–400 g\\/l) during the months between January and June.

M. A. Allison; C. A. Nittrouer; G. C. Kineke

1995-01-01

24

Amazon River enhances diazotrophy and carbon sequestration in the tropical North Atlantic Ocean  

E-print Network

#12;Amazon River enhances diazotrophy and carbon sequestration in the tropical North Atlantic Ocean in carbon sequestration. Here, we report that the Amazon River plume supports N2 fixation far from the mouth of atmospheric carbon to the deep ocean (3), or ``carbon sequestration'' (4). The Amazon River has the largest

Subramaniam, Ajit

25

Factors driving the biogeochemical budget of the Amazon River and its statistical modelling  

E-print Network

Factors driving the biogeochemical budget of the Amazon River and its statistical modelling the period 1982­1984 during the Carbon in the AMazon River Experiment (CAMREX) project. The relevant factors-regressive model coupled to variance analysis. Basically, the compositional fluctuations in the Amazon River

Paris-Sud XI, Université de

26

Organic carbon-14 in the Amazon River system  

Microsoft Academic Search

Coarse and fine suspended particulate organic materials and dissolved humic and fulvic acids transported by the Amazon River all contain bomb-produced carbon-14, indicating relatively rapid turnover of the parent carbon pools. However, the carbon-14 contents of these coexisting carbon forms are measurably different and may reflect varying degrees of retention by soils in the drainage basin. 20 references, 1 table.

J. I. Hedges; J. R. Ertel; P. D. Quay; P. M. Grootes; J. E. Richey; A. H. Devol; G. W. Farwell; F. W. Schmidt; E. Salati

1986-01-01

27

Organic carbon-14 in the Amazon River system  

SciTech Connect

Coarse and fine suspended particulate organic materials and dissolved humic and fulvic acids transported by the Amazon River all contain bomb-produced carbon-14, indicating relatively rapid turnover of the parent carbon pools. However, the carbon-14 contents of these coexisting carbon forms are measurably different and may reflect varying degrees of retention by soils in the drainage basin. 20 references, 1 table.

Hedges, J.I.; Ertel, J.R.; Quay, P.D.; Grootes, P.M.; Richey, J.E.; Devol, A.H.; Farwell, G.W.; Schmidt, F.W.; Salati, E.

1986-03-07

28

Dissolved humic substances of the Amazon River system1  

Microsoft Academic Search

Aquatic humic and fulvic acids from nine mainstem and seven major tributary sites in the Amazon River Basin are characterized by their elemental and lignin phenol compositions. Com- bined humic substances represent 60% of the riverine dissolved organic carbon (DOC), with fulvic to humic acid (FA : HA) ratios in the mainstem averaging 4.7 -t 1 .O. All dissolved humic

John R. Ertel; John I. Hedges; Allan H. Devol; Jefrey E. Richey

1986-01-01

29

The prawn Macrobrachium vollenhovenii in the Senegal River basin: towards sustainable restocking of all-male populations for biological control of schistosomiasis.  

PubMed

Early malacological literature suggests that the outbreak of schistosomiasis, a parasitic disease transmitted by aquatic snails, in the Senegal River basin occurred due to ecological changes resulting from the construction of the Diama dam. The common treatment, the drug praziquantel, does not protect from the high risk of re-infection due to human contact with infested water on a daily basis. The construction of the dam interfered with the life cycle of the prawn Macrobrachium vollenhovenii by blocking its access to breeding grounds in the estuary. These prawns were demonstrated to be potential biological control agents, being effective predators of Schistosoma-susceptible snails. Here, we propose a responsible restocking strategy using all-male prawn populations which could provide sustainable disease control. Male prawns reach a larger size and have a lower tendency to migrate than females. We, therefore, expect that periodic restocking of all-male juveniles will decrease the prevalence of schistosomiasis and increase villagers' welfare. In this interdisciplinary study, we examined current prawn abundance along the river basin, complemented with a retrospective questionnaire completed by local fishermen. We revealed the current absence of prawns upriver and thus demonstrated the need for restocking. Since male prawns are suggested to be preferable for bio-control, we laid the molecular foundation for production of all-male M. vollenhovenii through a complete sequencing of the insulin-like androgenic gland-encoding gene (IAG), which is responsible for sexual differentiation in crustaceans. We also conducted bioinformatics and immunohistochemistry analyses to demonstrate the similarity of this sequence to the IAG of another Macrobrachium species in which neo-females are produced and their progeny are 100% males. At least 100 million people at risk of schistosomiasis are residents of areas that experienced water management manipulations. Our suggested non-breeding sustainable model of control-if proven successful-could prevent re-infections and thus prove useful throughout the world. PMID:25166746

Savaya Alkalay, Amit; Rosen, Ohad; Sokolow, Susanne H; Faye, Yacinthe P W; Faye, Djibril S; Aflalo, Eliahu D; Jouanard, Nicolas; Zilberg, Dina; Huttinger, Elizabeth; Sagi, Amir

2014-08-01

30

The Prawn Macrobrachium vollenhovenii in the Senegal River Basin: Towards Sustainable Restocking of All-Male Populations for Biological Control of Schistosomiasis  

PubMed Central

Early malacological literature suggests that the outbreak of schistosomiasis, a parasitic disease transmitted by aquatic snails, in the Senegal River basin occurred due to ecological changes resulting from the construction of the Diama dam. The common treatment, the drug praziquantel, does not protect from the high risk of re-infection due to human contact with infested water on a daily basis. The construction of the dam interfered with the life cycle of the prawn Macrobrachium vollenhovenii by blocking its access to breeding grounds in the estuary. These prawns were demonstrated to be potential biological control agents, being effective predators of Schistosoma-susceptible snails. Here, we propose a responsible restocking strategy using all-male prawn populations which could provide sustainable disease control. Male prawns reach a larger size and have a lower tendency to migrate than females. We, therefore, expect that periodic restocking of all-male juveniles will decrease the prevalence of schistosomiasis and increase villagers' welfare. In this interdisciplinary study, we examined current prawn abundance along the river basin, complemented with a retrospective questionnaire completed by local fishermen. We revealed the current absence of prawns upriver and thus demonstrated the need for restocking. Since male prawns are suggested to be preferable for bio-control, we laid the molecular foundation for production of all-male M. vollenhovenii through a complete sequencing of the insulin-like androgenic gland-encoding gene (IAG), which is responsible for sexual differentiation in crustaceans. We also conducted bioinformatics and immunohistochemistry analyses to demonstrate the similarity of this sequence to the IAG of another Macrobrachium species in which neo-females are produced and their progeny are 100% males. At least 100 million people at risk of schistosomiasis are residents of areas that experienced water management manipulations. Our suggested non-breeding sustainable model of control—if proven successful—could prevent re-infections and thus prove useful throughout the world. PMID:25166746

Savaya Alkalay, Amit; Rosen, Ohad; Sokolow, Susanne H.; Faye, Yacinthe P. W.; Faye, Djibril S.; Aflalo, Eliahu D.; Jouanard, Nicolas; Zilberg, Dina; Huttinger, Elizabeth; Sagi, Amir

2014-01-01

31

Rates and mechanisms of shoreface progradation and retreat downdrift of the Amazon river mouth  

Microsoft Academic Search

Field surveys of the 350-km shoreline adjacent to the Amazon river mouth reveal three distinct types: erosional mud, accretionary sand, and accretionary mud. Formation of these zones is controlled by the delivery of Amazon suspended sediment, mediated by the hydrodynamic regime. Erosional mud shorelines extend from Rio Araguari (near the Amazon river mouth) northwestward 280 km to 3.5 °N (near

M. A. Allison; C. A. Nittrouer; L. E. C. Faria

1995-01-01

32

Suspended sediment dynamics in the Amazon River of Peru  

NASA Astrophysics Data System (ADS)

The erosion and transport of sediments allow us to understand many activities of significance, such as crust evolution, climate change, uplift rates, continental processes, the biogeochemical cycling of pollutants and nutrients. The Amazon basin of Peru has contrasting physiographic and climatic characteristics between the Andean piedmont and the plains and between the north and south of the basin which is why there are 8 gauging stations located along the principal rivers of the Andean piedmont (Marañón, Huallaga, Ucayali) and the plain (Marañón, Tigre, Napo, Ucayali and Amazon rivers). Since 2003, the ORE-Hybam (IRD-SENAMHI-UNALM) observatory has performed out regular measurements at strategic points of the Amazon basin to understand and model the systems, behavior and long-term dynamics. On the Andean piedmont, the suspended yields are governed by a simple model with a relationship between the river discharge and the sediment concentration. In the plain, the dilution effect of the concentrations can create hysteresis in this relationship on a monthly basis. The Amazon basin of Peru has a sediment yield of 541 *106 t year-1, 70% comes from the southern basin.

Armijos, Elisa; Crave, Alain; Vauchel, Philippe; Fraizy, Pascal; Santini, William; Moquet, Jean-Sèbastien; Arevalo, Nore; Carranza, Jorge; Guyot, Jean-Loup

2013-07-01

33

Effects of Amazon River Discharge on the Oceanic Physics and Surrounding Circulation System  

NASA Astrophysics Data System (ADS)

The Amazon River contributes about 20% of the global river discharge to the oceans; hence, the Amazon River freshwater input may have profound effect on the coastal sea surface salinity, which, by mixing processes, can change the ocean stratification and halocline structure. The river discharge potentially alters the circulation pattern in the neighboring sea. For example, when Amazon River discharge is higher, the North Brazilian Current might transport less salt water to the northern region such as Caribbean Sea that further influences its hydrology and distribution of nutrients. In this study, the Parallel Ocean Program version 2 (POP2) is employed to test impacts of Amazon River discharge, which is parameterized as surface fluxes, on the tropical Atlantic. We analyze the variability of vertical structure and ocean dynamics under different amounts of river discharge from seasonal to interannual scale. Preliminary results show that the surrounding ocean hydrological cycle could be significantly modified due to the interannual variabilities in the Amazon River discharge.

Liang, Y.; Lo, M.; Famiglietti, J. S.; Lee, S.; Chen, S.; Tseng, Y.

2012-12-01

34

Phytoplankton biomass and productivity in the Amazon River plume: correlation with seasonal river discharge  

Microsoft Academic Search

Phytoplankton biomass and primary productivity were assessed on the continental shelf in the plume of the Amazon River during a series of cruises conducted within periods of minimum, maximum, rising and falling river discharge. Chlorophyll concentrations were greatest (up to 25.5 ?g l?1) in a zone located outside the turbid, high nutrient, low salinity riverine waters but shoreward of the

Walker O. Smith; David J. Demaster

1996-01-01

35

Bacterial carbon metabolism in the Amazon River system  

Microsoft Academic Search

Bacterial abundance and production and community respiration were measured at several mainstem and tributary stations in November-December 1988, April-May 1990, and August-September 199 1 in a 1,950- km reach of the Amazon River between Vargem Grande and Obidos, Brazil. Bacterial abundances averaged 1.1 x 1 O9 cells liter - L in the mainstem during the three cruises, and rates of

RONALD BENNER; STEPHEN OPSAHL; GERARDO CHIN-LEO; JEFFREY E. RICHEY; BRUCE R. FORSBERG

1995-01-01

36

Suspended sediments of the modern Amazon and Orinoco rivers  

USGS Publications Warehouse

The Amazon and Orinoco Rivers are massive transcontinental conveyance systems for suspended sediment. They derive about 90% of their sediment from the Andes that support their western headwaters, transport it for thousands of kilometers across the breadth of the continent and deposit it in the coastal zones of the Atlantic. At their points of maximum suspended-sediment discharge, the Amazon transports an average of 1100-1300 ?? 106 tons per year and the Orinoco transports about 150 ?? 106 tons per year. Relations of sediment discharge to water discharge are complicated by unusual patterns of seasonal storage and remobilization, increased storage and reduced transport of sediment in the middle Orinoco during periods of peak water discharge, and storage of suspended sediment in the lower Amazon during rising discharge and resuspension during falling discharge. Spatial distributions of suspended sediment in cross-sections of both rivers are typically heterogeneous, not only in the vertical sense but also in the lateral. The cross-channel mixing of tributary inputs into the mainstem waters is a slow process that requires several hundred kilometers of downriver transport to complete. Considerable fine-grained sediment is exchanged between rivers and floodplains by the combination of overbank deposition and bank erosion. ?? 1994.

Meade, R.H.

1994-01-01

37

Climatic variability between SST and river discharge at Amazon region  

NASA Astrophysics Data System (ADS)

Climatic variability, related both to precipitation and river discharge, has been associated to ocean variability. Authors commonly relate Pacific sea surface temperature (SST) variation to South America (SA) precipitation. Zonal displacement of Walker cell, with intensified subsidence over northern portion of SA, Subtropical Jet strengthening/weakening over extratropical latitudes of SA are, respectively, dynamical reasons scientifically accepted for increasing and depletion of precipitation at the respective areas. Many studies point out the influence of tropical Atlantic SST anomalies in relation to precipitation/river discharge variability over northeast of Brazil. Aliseos variability at tropical Atlantic is also a physic process that contributes to explain precipitation and river flow variability over SA, mainly over the north portion. In this study, we aim to investigate the temporal correlation between SST, mainly from Pacific and Atlantic oceans, and rivers discharge at the Amazon region. Ji-Parana, Madeira and Tapajós river discharge in monthly and annual scale, between 1968 and 2008, were the time series selected to reach the purpose. Time series for river discharge were obtained from Agência Nacional de Águas (ANA, in Portuguese) and, SST data were obtained from CDC/NOAA. Before linear correlation computations between river discharge and SST have been made, seasonal cycle and linear tendency were removed from all original time series. Areas better correlated to river discharge at Amazon region show oceanic patterns apparently associated to PDO (Pacific Decadal Oscillation) and ENSO (El Niño-South Oscillation) variability, with absolute values greater than 0.3 and reaching 0.5 or 0.6. The spatial pattern observed at Pacific basin is similar to that showed by the first mode of PCA (Principal Component Analysis), such seen in many studies (the "horse shoe" pattern). In general, negative correlation values appear far more to the west of Pacific basin while positive values are appear over areas a bit more to east. Central and east areas over Equatorial Pacific show negative values to the discharge series analyzed. ENSO events are well correlated to precipitation anomalies over Amazon region. Positive/negative SST anomalies over central-east Equatorial Pacific are associated to few/more precipitation/river discharge over Amazon region. Madeira discharge is especially well and negatively correlated to SST at tropical North Atlantic areas, showing absolute values greater than 0.5. In this case, the increase/decrease of river discharge over Amazon region when SST anomaly at the tropical north Atlantic is negative/positive can be explained by the strengthened/weakened winds over the equatorial side of the subtropical high during these situations. Pacific and Atlantic areas that show good correlations to river discharge at Amazon region may be potential variables in a linear model to simulation and prediction of discharge.

Silva, M. E.; Silva, E. R. L.

2012-04-01

38

The Amazon continuum dataset: quantitative metagenomic and metatranscriptomic inventories of the Amazon River plume, June 2010  

PubMed Central

Background The Amazon River is by far the world’s largest in terms of volume and area, generating a fluvial export that accounts for about a fifth of riverine input into the world’s oceans. Marine microbial communities of the Western Tropical North Atlantic Ocean are strongly affected by the terrestrial materials carried by the Amazon plume, including dissolved (DOC) and particulate organic carbon (POC) and inorganic nutrients, with impacts on primary productivity and carbon sequestration. Results We inventoried genes and transcripts at six stations in the Amazon River plume during June 2010. At each station, internal standard-spiked metagenomes, non-selective metatranscriptomes, and poly(A)-selective metatranscriptomes were obtained in duplicate for two discrete size fractions (0.2 to 2.0 ?m and 2.0 to 156 ?m) using 150 × 150 paired-end Illumina sequencing. Following quality control, the dataset contained 360 million reads of approximately 200 bp average size from Bacteria, Archaea, Eukarya, and viruses. Bacterial metagenomes and metatranscriptomes were dominated by Synechococcus, Prochlorococcus, SAR11, SAR116, and SAR86, with high contributions from SAR324 and Verrucomicrobia at some stations. Diatoms, green picophytoplankton, dinoflagellates, haptophytes, and copepods dominated the eukaryotic genes and transcripts. Gene expression ratios differed by station, size fraction, and microbial group, with transcription levels varying over three orders of magnitude across taxa and environments. Conclusions This first comprehensive inventory of microbial genes and transcripts, benchmarked with internal standards for full quantitation, is generating novel insights into biogeochemical processes of the Amazon plume and improving prediction of climate change impacts on the marine biosphere. PMID:24883185

2014-01-01

39

Daily water level by ENVISAT altimetry of the Amazon River  

NASA Astrophysics Data System (ADS)

Radar Altimetry is a remote sensing technique applied in order to obtain the level of water of the hydrological processes, mostly in remote regions such as in the Amazon basin. However, the altimetry satellites have a limitation in their temporal resolution, which in the case of ENVISAT is 35 days, which prevents the study of short-term hydrological events alert of floods and droughts and etc. Thus, a method of obtaining altimetric daily time series water level, based on a linear model of interpolation by optimization with multi-objective criteria was applied, using data from in situ on pluvial stations, along the Amazon River. The altimetry data validation show accurate results with a RMS of 11 cm, while the estimates carried out by the model obtained 63% of altimetric daily time series water level data with RMS less than 40 cm, thus allowing the use of altimetry data daily at various hydrological studies, hydrodynamic modeling and monitoring of extreme events.

Sousa, A. C.; Pereira, P.; Silva, J. S.; Calmant, S.; Seyler, F.

2013-05-01

40

2005 drought event in the Amazon River basin as measured by GRACE and estimated by climate models  

E-print Network

2005 drought event in the Amazon River basin as measured by GRACE and estimated by climate models J extreme drought event in the Amazon river basin, regarded as the worst in over a century. GRACE measures. Yang, and G. Y. Niu (2009), 2005 drought event in the Amazon River basin as measured by GRACE

Yang, Zong-Liang

41

PUBLISHED ONLINE: 21 NOVEMBER 2010 | DOI: 10.1038/NGEO1017 Miocene drainage reversal of the Amazon River  

E-print Network

of the Amazon River driven by plate­mantle interaction G. E. Shephard1 *, R. D. Müller1 , L. Liu2 and M. Gurnis2 by the formation of the eastward-draining Amazon River, which has been attributed to Andean uplift1­5 . However the establishment of the Amazon River, suggesting that mantle convection can profoundly affect the evolution

Liu, Lijun

42

The Amazon River exits the Andes mountains more than 4000 kilometers (km) from its estuary,but along its  

E-print Network

Articles The Amazon River exits the Andes mountains more than 4000 kilometers (km) from its estuary of the environment and distinct aquatic eco- systems of the lowland Amazon River (summarized in Sioli [1984], Junk source of sediments and solutes to the lower reaches of the Amazon River.The most visible characteristics

McClain, Michael

43

Photochemical and microbial consumption of dissolved organic carbon and dissolved oxygen in the Amazon River system  

Microsoft Academic Search

Bacterial and photochemical mineralization of dissolved organic matter were investigated in the Amazon River system. Dissolved oxygen, dissolved organic carbon (DOC), and bacterial growth were measured during incubations conducted under natural sunlight and in the dark. Substrate addition experiments indicated that the relatively low rates of bacterial activity in Amazon River water were caused by C limitation. Experiments to determine

R. M. W. Amon; R. Benner

1996-01-01

44

The history of the introduction of the giant river prawn, Macrobrachium cf. rosenbergii (Decapoda, Palaemonidae), in Brazil: New insights from molecular data  

PubMed Central

The giant river prawn, Macrobrachium cf. rosenbergii, is one of the most cultivated freshwater prawns in the world and has been introduced into more than 40 countries. In some countries, this prawn is considered an invasive species that requires close monitoring. Recent changes in the taxonomy of this species (separation of M. rosenbergii and M. dacqueti) require a re-evaluation of introduced taxa. In this work, molecular analyses were used to determine which of these two species was introduced into Brazil and to establish the geographic origin of the introduced populations that have invaded Amazonian coastal waters. The species introduced into Brazil was M. dacqueti through two introduction events involving prawns originating from Vietnam and either Bangladesh or Thailand. These origins differ from historical reports of the introductions and underline the need to confirm the origin of other exotic populations around the world. The invading populations in Amazonia require monitoring not only because the biodiversity of this region may be affected by the introduction, but also because admixture of different native haplotypes can increase the genetic variability and the likelihood of persistence of the invading species in new habitats. PMID:21637558

Iketani, Gabriel; Pimentel, Luciana; Silva-Oliveira, Glaucia; Maciel, Cristiana; Valenti, Wagner; Schneider, Horacio; Sampaio, Iracilda

2011-01-01

45

Amazon River carbon dioxide outgassing fuelled by wetlands.  

PubMed

River systems connect the terrestrial biosphere, the atmosphere and the ocean in the global carbon cycle. A recent estimate suggests that up to 3 petagrams of carbon per year could be emitted as carbon dioxide (CO2) from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon that has been previously fixed upstream by land plant photosynthesis, then transferred to soils, and subsequently transported downstream in run-off. But at the scale of entire drainage basins, the lateral carbon fluxes carried by small rivers upstream do not account for all of the CO2 emitted from inundated areas downstream. Three-quarters of the world's flooded land consists of temporary wetlands, but the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Here we show that wetlands pump large amounts of atmospheric CO2 into river waters in the floodplains of the central Amazon. Flooded forests and floating vegetation export large amounts of carbon to river waters and the dissolved CO2 can be transported dozens to hundreds of kilometres downstream before being emitted. We estimate that Amazonian wetlands export half of their gross primary production to river waters as dissolved CO2 and organic carbon, compared with only a few per cent of gross primary production exported in upland (not flooded) ecosystems. Moreover, we suggest that wetland carbon export is potentially large enough to account for at least the 0.21 petagrams of carbon emitted per year as CO2 from the central Amazon River and its floodplains. Global carbon budgets should explicitly address temporary or vegetated flooded areas, because these ecosystems combine high aerial primary production with large, fast carbon export, potentially supporting a substantial fraction of CO2 evasion from inland waters. PMID:24336199

Abril, Gwenaël; Martinez, Jean-Michel; Artigas, L Felipe; Moreira-Turcq, Patricia; Benedetti, Marc F; Vidal, Luciana; Meziane, Tarik; Kim, Jung-Hyun; Bernardes, Marcelo C; Savoye, Nicolas; Deborde, Jonathan; Souza, Edivaldo Lima; Albéric, Patrick; Landim de Souza, Marcelo F; Roland, Fabio

2014-01-16

46

Amazon River carbon dioxide outgassing fuelled by wetlands  

NASA Astrophysics Data System (ADS)

River systems connect the terrestrial biosphere, the atmosphere and the ocean in the global carbon cycle. A recent estimate suggests that up to 3 petagrams of carbon per year could be emitted as carbon dioxide (CO2) from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon that has been previously fixed upstream by land plant photosynthesis, then transferred to soils, and subsequently transported downstream in run-off. But at the scale of entire drainage basins, the lateral carbon fluxes carried by small rivers upstream do not account for all of the CO2 emitted from inundated areas downstream. Three-quarters of the world's flooded land consists of temporary wetlands, but the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Here we show that wetlands pump large amounts of atmospheric CO2 into river waters in the floodplains of the central Amazon. Flooded forests and floating vegetation export large amounts of carbon to river waters and the dissolved CO2 can be transported dozens to hundreds of kilometres downstream before being emitted. We estimate that Amazonian wetlands export half of their gross primary production to river waters as dissolved CO2 and organic carbon, compared with only a few per cent of gross primary production exported in upland (not flooded) ecosystems. Moreover, we suggest that wetland carbon export is potentially large enough to account for at least the 0.21 petagrams of carbon emitted per year as CO2 from the central Amazon River and its floodplains. Global carbon budgets should explicitly address temporary or vegetated flooded areas, because these ecosystems combine high aerial primary production with large, fast carbon export, potentially supporting a substantial fraction of CO2 evasion from inland waters.

Abril, Gwenaël; Martinez, Jean-Michel; Artigas, L. Felipe; Moreira-Turcq, Patricia; Benedetti, Marc F.; Vidal, Luciana; Meziane, Tarik; Kim, Jung-Hyun; Bernardes, Marcelo C.; Savoye, Nicolas; Deborde, Jonathan; Souza, Edivaldo Lima; Albéric, Patrick; Landim de Souza, Marcelo F.; Roland, Fabio

2014-01-01

47

Trace elements and radionuclides in the Connecticut River and Amazon River estuary  

SciTech Connect

The Connecticut River, its estuary and the Amazon River plume were studied to elucidate processes which control the flux of nuclides to the sea. Major ions (Ca, Mg, Na, Cl, Bicarbonate) and selected trace elements (Ra, Ba, Cu, Si) are introduced to the Connecticut River in proportion to the total dissolved load of various groundwaters. Si, Ra, and Ba are subject to removal from solution by seasonal diatom productivity; whereas the other groundwater-derived elements are found in proportion to TDS both time and space. These nuclides are released in the estuary when a portion of the Ra, Ba, and Si in riverine biogenic detritus is trapped in salt marshes and coves bordering the estuary where it redissolves and is exported to the main river channel at ebb tide. In the Amazon River estuary, the Ra and Ba are released in mid-salinity waters. Ra and Ba together with Si are subsequently removed by diatom productivity as reflected in increased Ra and Ba in the suspended particles and depleted dissolved nuclide concentrations in samples from the high productivity zone. In both the Connecticut River system and the Amazon River plume, Cu behaves conservatively; whereas the fates of Fe and Al are linked to soil-derived humic acids. Trace elements in Amazon plume sediments are found simply in proportion to the percentage of fine-grained size materials, despite low Th-228/Ra-228 mean residence times in the plume and the presence of Cs-137 in the sediment column. Estimates of the total flux of nuclides to the oceans can best be calculated on a mass balance basis using groundwater inputs. Unless significant repositories for nuclides exist in the river-estuarine system, the groundwater flux of dissolved nuclides is net flux to the ocean despite the reactions which occur in both rivers and estuaries.

Dion, E.P.

1983-01-01

48

Molecular cloning and characterization of the lipopolysaccharide and ?-1,3-glucan binding protein from oriental river prawn, Macrobrachium nipponense.  

PubMed

The lipopolysaccharide and ?-1,3-glucan binding protein (LGBP), one of the pattern recognition proteins, plays an important role in the innate immune response of invertebrates. A 1,506 bp full-length cDNA of a LGBP gene was cloned and characterized from the oriental river prawn Macrobrachium nipponense (named as MnLGBP). Analysis of the nucleotide sequence revealed that the cDNA clone has an open reading frame of 1,119 bp, encoding a protein of 372 amino acids including a 21-aa signal peptide. The calculated molecular mass of the mature protein (351 aa) was 39.9 kDa with an estimated pI of 4.63. The MnLGBP sequence contains: (1) two putative integrin-binding motifs, (2) a glucanase motif, (3) two putative N-glycosylation sites, (4) one protein kinase C phosphorylation site, and (5) a putative recognition motif for ?-1,3-linkage of polysaccharides. Sequence comparison based on the deduced amino acid sequence of MnLGBP showed varied identity of 89, 76 and 74% with those of Macrobrachium rosenbergii LGBP, Marsupenaeus japonicus ?-1,3-glucan binding proteins, and Fenneropenaeus chinensis LGBP, respectively. Quantitative RT-PCR results showed that MnLGBP was expressed in nerve, intestine, muscle, gill, heart, haemocytes and at the highest level in hepatopancreas. After challenge with the pathogen, Aeromonas hydrophila and Vibrio parahaemolyticus, the expression of MnLGBP mRNA was significantly upregulated in the hepatopancreas compared to the control group. At the same time, the mRNA level of MnproPO increased dramatically at 48 h after injection of bacteria. These data should be helpful to better understand the function of MnLGBP in the prawn immune system. PMID:24584659

Xiu, Yunji; Wu, Ting; Liu, Peng; Huang, Ying; Ren, Qian; Gu, Wei; Meng, Qingguo; Wang, Wen

2014-06-01

49

Contrasting iron isotopic compositions in river suspended particulate matter: the Negro and the Amazon annual river cycles  

NASA Astrophysics Data System (ADS)

Iron isotopic compositions (?FeIRMM-1456) of suspended particulate matter (SPM) from two major rivers in the Amazon Basin, the Amazon River itself (at the Óbidos Station) and the Negro River (at the Serrinha Station), were investigated in the present study. The main objective was to search for temporal variations during their annual river cycles. ?FeIRMM-1456 values for the Amazon River at Óbidos range between 0.00 and +0.15‰, indistinguishable from the average continental crust value. In contrast, the iron isotopic compositions of the Negro River (Serrinha Station) SPM vary between -0.34 and -0.82‰, whereas the dissolved matter is isotopically heavier in this river. The lack of significant isotopic variations in the Amazon River indicates that one individual SPM subsurface sample is representative of the river during the whole annual river cycle, in opposition to results obtained for the Negro River. The data suggest that in organic-poor white water rivers, such as the Amazon, iron isotopic signatures of the suspended fraction reflect a detrital crustal component with little isotopic fractionation. On the other hand, in the organic-rich Negro River, which has tropical podzols as the main iron source, the iron redox cycling at the water-soil interface influences the iron isotopic composition.

dos Santos Pinheiro, Giana Márcia; Poitrasson, Franck; Sondag, Francis; Cochonneau, Gérard; Vieira, Lucieth Cruz

2014-05-01

50

Contrasting patterns of habitat use by prawns and crayfish in a headwater marsh of the St. Johns River, Florida  

USGS Publications Warehouse

We compared seasonal patterns of habitat use by the prawn Palaemonetes paludosus and the crayfish Procambarus alleni in Blue Cypress Marsh Conservation Area, Florida. Prawn densities were similar to those found in other oligotrophic wetlands of southern Florida, whereas crayfish densities were much greater than reported previously for other wetlands in the area. Prawns and crayfish had strikingly different patterns of habitat use. Prawn density and biomass were similar in wet prairies and sloughs, whereas crayfish density and biomass were significantly higher in wet prairies. Within habitats, the abundance of prawns and crayfish generally increased with increasing structural complexity and the abundance of crayfish generally decreased with increasing water depth. Differences in risk of predation, frequency of agonistic encounters, food availability, and other factors likely contributed to observed patterns of habitat use. Because of differences in their ability to burrow and avoid concentration into dry-season refugia, prawns and crayfish responded very differently to seasonal variation in hydrologic conditions. Prawn densities were initially low (following a severe drought) and then increased during much of the study period, whereas crayfish densities were relatively stable throughout the study period. Overall, it appears that prawns are more responsive to antecedent hydrologic conditions and crayfish are more responsive to the availability of suitable habitats such as wet prairies.

Jordan, Frank; Babbitt, Kimberly J.; McIvor, Carole C.; Miller, Steven J.

2000-01-01

51

Microspatial gene expression patterns in the Amazon River Plume.  

PubMed

We investigated expression of genes mediating elemental cycling at the microspatial scale in the ocean's largest river plume using, to our knowledge, the first fully quantitative inventory of genes and transcripts. The bacterial and archaeal communities associated with a phytoplankton bloom in Amazon River Plume waters at the outer continental shelf in June 2010 harbored ? 1.0 × 10(13) genes and 4.7 × 10(11) transcripts per liter that mapped to several thousand microbial genomes. Genomes from free-living cells were more abundant than those from particle-associated cells, and they generated more transcripts per liter for carbon fixation, heterotrophy, nitrogen and phosphorus uptake, and iron acquisition, although they had lower expression ratios (transcripts ? gene(-1)) overall. Genomes from particle-associated cells contributed more transcripts for sulfur cycling, aromatic compound degradation, and the synthesis of biologically essential vitamins, with an overall twofold up-regulation of expression compared with free-living cells. Quantitatively, gene regulation differences were more important than genome abundance differences in explaining why microenvironment transcriptomes differed. Taxa contributing genomes to both free-living and particle-associated communities had up to 65% of their expressed genes regulated differently between the two, quantifying the extent of transcriptional plasticity in marine microbes in situ. In response to patchiness in carbon, nutrients, and light at the micrometer scale, Amazon Plume microbes regulated the expression of genes relevant to biogeochemical processes at the ecosystem scale. PMID:25024226

Satinsky, Brandon M; Crump, Byron C; Smith, Christa B; Sharma, Shalabh; Zielinski, Brian L; Doherty, Mary; Meng, Jun; Sun, Shulei; Medeiros, Patricia M; Paul, John H; Coles, Victoria J; Yager, Patricia L; Moran, Mary Ann

2014-07-29

52

Trace elements and radionuclides in the Connecticut River and Amazon River estuary  

SciTech Connect

The Connecticut River, its estuary, and the Amazon River estuary were studied to elucidate some of the processes which control river water chemistry and the flux of elements to the sea. The approach taken was to identify inputs to the Connecticut River and to investigate geochemical processes which modify the dissolved load. The form and quantity of nuclides which are in turn supplied to the estuary are altered by processes unique to that transition zone to the ocean. The Connecticut River estuary was sampled on a seasonal basis to investigate the role of the estuary in controlling the flux of elements to the sea. The knowledge gained from the Connecticut River study was applied to the quantitatively more significant Amazon River estuary. There a variety of samples were analyzed to understand the processes controlling the single greatest flux of elements to the Atlantic Ocean. The results indicate that estimates of the total flux of nuclides to the oceans can best be calculated based on groundwater inputs. Unless significant repositories for nuclides exist in the river-estuarine system, the groundwater flux of dissolved nuclides is that which will eventually be delivered to the ocean despite the reactions which were shown to occur in both rivers and estuaries. 153 references, 63 figures, 28 tables.

Dion, E.P.

1983-01-01

53

Degradation of terrestrially derived macromolecules in the Amazon River  

NASA Astrophysics Data System (ADS)

Temperate and tropical rivers serve as a significant source of carbon dioxide to the atmosphere. However, the source of the organic matter that fuels these globally relevant emissions is uncertain. Lignin and cellulose are the most abundant macromolecules in the terrestrial biosphere, but are assumed to resist degradation on release from soils to aquatic settings. Here, we present evidence for the degradation of lignin and associated macromolecules in the Amazon River. We monitored the degradation of a vast suite of terrestrially derived macromolecules and their breakdown products in water sampled from the mouth of the river throughout the course of a year, using gas chromatography time-of-flight mass spectrometry. We identified a number of lignin phenols, together with 95 phenolic compounds, largely derived from terrestrial macromolecules. Lignin, together with numerous phenolic compounds, disappeared from our analytical window following several days of incubation at ambient river temperatures, indicative of biological degradation. We estimate that the net rate of degradation observed corresponds to 30-50% of bulk river respiration. Assuming that a significant fraction of these compounds is eventually remineralized to carbon dioxide, we suggest that lignin and other terrestrially derived macromolecules contribute significantly to carbon dioxide outgassing from inland waters.

Ward, Nicholas D.; Keil, Richard G.; Medeiros, Patricia M.; Brito, Daimio C.; Cunha, Alan C.; Dittmar, Thorsten; Yager, Patricia L.; Krusche, Alex V.; Richey, Jeffrey E.

2013-07-01

54

Tidal controls on the formation of fine-scale sedimentary strata near the Amazon river mouth  

Microsoft Academic Search

The Amazon river mouth provides a dynamic setting for studying the formation of sedimentary strata under conditions where fluvial and marine processes merge. River-mouth anchor stations were occupied for diurnal tidal cycles during three stages of river flow, and reoccupied for consecutive spring and neap tides during two stages of river flow. At each anchor station, box cores were collected

John M. Jaeger; Charles A. Nittrouer

1995-01-01

55

The Amazon River plume during AMASSEDS: Spatial characteristics and salinity variability  

Microsoft Academic Search

The Amazon River discharge forms a plume of low-salinity water that extends offshore and northwestward over the north Brazilian shelf. Observations acquired as part of A Multidisciplinary Amazon Shelf SEDiment Study (AMASSEDS) are used to characterize the spatial structure and temporal variability of the Amazon Plume. Four shipboard conductivity-temperature-depth (CTD) surveys spanning the shelf from 1°S to 5°N during rising

Steven J. Lentz; Richard Limeburner

1995-01-01

56

Logging along the Amazon River and estuary: Patterns, problems and potential  

Microsoft Academic Search

Over the last several centuries most of the logging in the Brazilian Amazon has occurred along the Lower Amazon River and estuary and for good reason. Timber has been abundant there, the costs of wood extraction and transport have been low, and access to markets has been good. In this paper we first characterize the structure of the wood sector

Ana Cristina Barros; Christopher Uhl

1995-01-01

57

Mercury in Fish-eating Communities of the Andean Amazon, Napo River Valley, Ecuador  

E-print Network

in three communities of the Napo River Valley, Ecuadorian Andean Amazon, a region without gold mining and extensive land clearing due to pipeline and road con- struction and spontaneous colonization on access roads

Long, Bernard

58

The Late Miocene paleogeography of the Amazon Basin and the evolution of the Amazon River system  

NASA Astrophysics Data System (ADS)

On the basis of paleontological content (vertebrates and palynology) and facies analysis from river banks, road cuts, and three wells, we have assigned the uppermost levels of the Solimões Formation in western Amazonia, Brazil, to the Late Miocene. The vertebrate fossil record from outcropping sediments is assigned to the Huayquerian-Mesopotamian mammalian biozones, spanning 9-6.5 Ma. Additionally, we present results that demonstrate that deposits in Peruvian Amazonia attributed to Miocene tidal environments are actually fluvial sediments that have been misinterpreted (both environmentally and chronologically) by several authors. The entire Late Miocene sequence was deposited in a continental environment within a subsiding basin. The facies analysis, fossil fauna content, and palynological record indicate that the environment of deposition was dominated by avulsive rivers associated with megafan systems, and avulsive rivers in flood basins (swamps, lakes, internal deltas, and splays). Soils developed on the flatter, drier areas, which were dominated by grasslands and gallery forest in a tropical to subtropical climate. These Late Miocene sediments were deposited from westward of the Purus arch up to the border of Brazil with Peru (Divisor Ranges) and Bolivia (Pando block). Eastward of the Iquitos structural high, however, more detailed studies, including vertebrate paleontology, need to be performed to calibrate with more precision the ages of the uppermost levels of the Solimões Formation. The evolution of the basin during the late Miocene is mainly related to the tectonic behavior of the Central Andes (˜ 3°-15°S). At approximately 5 Ma, a segment of low angle of subduction was well developed in the Nazca Plate, and the deformation in the Subandean foreland produced the inland reactivation of the Divisor/Contamana Ranges and tectonic arrangements in the Eastern Andes. During the Pliocene southwestern Brazilian Amazonia ceased to be an effective sedimentary basin, and became instead an erosional area that contributed sediments to the Amazon fluvial system. At that time, the lowland fluvial systems of southwestern Amazonia (the Purus, Jurua and Javarí basins) become isolated from the Andes by the newly formed north-flowing Ucayali system and south-east flowing Madre de Dios System. It was during the early Pliocene that the Amazon fluvial system integrated regionally and acquired its present appearance, and also when it started to drain water and sediments on a large scale to the Atlantic Ocean.

Latrubesse, Edgardo M.; Cozzuol, Mario; da Silva-Caminha, Silane A. F.; Rigsby, Catherine A.; Absy, Maria Lucia; Jaramillo, Carlos

2010-05-01

59

Exportation of organic carbon from the Amazon River and its main tributaries  

Microsoft Academic Search

As part of a joint Brazilian-French project, entitled Hydrology and Geochemistry of the Amazon Basin, we carried out a seven-year study (1994-2000) on the distribution, behaviour and flux of particulate and dissolved organic carbon in the Amazon River and its main tributaries (the Negro, Solimões, Branco, Madeira, Tapajós, Xingú and Trombetas rivers).The concentrations of particulate and dissolved organic carbon varied

Patricia Moreira-Turcq; Patrick Seyler; Jean Loup Guyot; Henri Etcheber

2003-01-01

60

Seroprevalence of Toxoplasma gondii in free-living Amazon River dolphins (Inia geoffrensis) from central Amazon, Brazil.  

PubMed

Toxoplasma gondii is an important pathogen in aquatic mammals and its presence in these animals may indicate the water contamination of aquatic environment by oocysts. Serum samples from 95 free-living Amazon River dolphins (Inia geoffrensis) from the Mamirauá Sustainable Development Reserve (RDSM), Tefé, Amazonas, Central Amazon, Brazil were tested for T. gondii antibodies using the modified agglutination test (MAT). Antibodies (MAT ? 25) to T. gondii were found in 82 (86.3%) dolphins with titers of 1:25 in 24, 1:50 in 56, and 1:500 in 2. Results suggest a high level contamination of the aquatic environment of the home range of these animals. PMID:21764516

Santos, P S; Albuquerque, G R; da Silva, V M F; Martin, A R; Marvulo, M F V; Souza, S L P; Ragozo, A M A; Nascimento, C C; Gennari, S M; Dubey, J P; Silva, J C R

2011-12-29

61

PUBLISHED ONLINE: XX MONTH XXXX | DOI: 10.1038/NGEO1017 Miocene drainage reversal of the Amazon River  

E-print Network

of the Amazon River driven by plate­mantle interaction G. E. Shephard1 *, R. D. Müller1 , L. Liu2 and M. Gurnis2 by the formation of the4 eastward-draining Amazon River, which has been attributed5 to Andean uplift1­5 . However towards26 the Atlantic. This shift, initiating the fluviolacustrine system that27 is now the Amazon River

Müller, Dietmar

62

Sediment transport and distribution over continental shelves: a glimpse at two different river-influenced systems, the Cariaco Basin and the Amazon Shelf  

Microsoft Academic Search

The aim of this dissertation was to understand lithogenic suspended sediment transport mechanisms and distribution in two river-influenced margins: The Cariaco Basin, Venezuela, and the Amazon Shelf, Brazil. Lithogenic sediment input in the Cariaco Basin is controlled by small mountainous rivers (SMR), while in the Amazon Shelf it is dominated by the Amazon River, the largest river in the world

Laura Lorenzoni

2012-01-01

63

Interannual variability in water storage over 2003-2007 in the Amazon Basin2 from GRACE space gravimetry, in situ river level3  

E-print Network

2003-2007 of different hydrological parameters in28 the Amazon river basin: vertically-integrated water storage from the GRACE space gravimetry29 mission, surface water level over the Amazon River and its storage from GRACE and31 in situ river level along the Amazon River and its main tributaries. We also

Boyer, Edmond

64

Major and trace elements of stream sediments from the lowermost Amazon River  

Microsoft Academic Search

Geochemical results from river-bottom sediments taken from the lowermost Amazon River are presented. Bedload sediments were analyzed for 10 major and 38 minor elements. Mud bulk sediments exhibit a tendency to a slight enrichment in Cr, Mn, Rb, Sr, Zr, Cs, Ba and Hf, pointing to the importance of these elements in the silt fraction. Generally, Cu, Zn, Rb, Cs,

Helenice Vital; Karl Stattegger

2000-01-01

65

Vocalizations of Amazon River Dolphins, Inia geoffrensis: Insights into the Evolutionary Origins of Delphinid Whistles  

Microsoft Academic Search

Oceanic dolphins (Odontoceti: Delphinidae) produce tonal whistles, the structure and function of which have been fairly well characterized. Less is known about the evolutionary origins of delphinid whistles, including basic information about vocal structure in sister taxa such as the Platanistidae river dolphins. Here we characterize vocalizations of the Amazon River dolphin (Inia geoffrensis), for which whistles have been reported

Jeffrey Podos; Vera M. F. da Silva; Marcos R. Rossi-Santos

2002-01-01

66

Molecular cytogenetic characterization of the Amazon River dolphin Inia geoffrensis.  

PubMed

Classical and molecular cytogenetic (18S rDNA, telomeric sequence, and LINE-1 retrotransposon probes) studies were carried out to contribute to an understanding of the organization of repeated DNA elements in the Amazon River dolphin (boto, Inia geoffrensis). Twenty-seven specimens were examined, each presenting 2n = 44 chromosomes, the karyotype formula 12m + 14sm + 6st + 10t + XX/XY, and fundamental number (FN) = 74. C-positive heterochromatin was observed in terminal and interstitial positions, with the occurrence of polymorphism. Interstitial telomeric sequences were not observed. The nucleolar organizer region (NOR) was located at a single site on a smallest autosomal pair. LINE-1 was preferentially distributed in the euchromatin regions, with the greatest accumulation on the X chromosome. Although the karyotype structure in cetaceans is considered to be conserved, the boto karyotype demonstrated significant variations in its formula, heterochromatin distribution, and the location of the NOR compared to other cetacean species. These results contribute to knowledge of the chromosome organization in boto and to a better understanding of karyoevolution in cetaceans. PMID:23010983

Bonifácio, Heidi L; da Silva, Vera M F; Martin, Anthony R; Feldberg, Eliana

2012-09-01

67

Biogenic gases and the oxidation and reduction of carbon in Amazon River and floodplain waters  

Microsoft Academic Search

Concentrations of COZ, 02, CH4, and N,O in the Amazon River system reflect an oxidation- reduction sequence in combination with physical mixing between the floodplain and the mainstem. Concentrations of CO, ranged from 150 PM in the Amazon mainstem to 200-300 PM in aerobic environments and up to 1,000 PM in oxygen-depleted environments of the floodplain. Apparent oxygen utilization (AOU)

JEFFREY E. RICHEY; ALLAN H. DEVOL; STEVEN C. WOFSY; REYNALDO VICTORIA; MARIA N. G. RIBERIO

1988-01-01

68

Variations of Amazon River channel flow observed by satellite gravity data  

NASA Astrophysics Data System (ADS)

The hydrological cycle of Amazon River basin, which is the largest drainage in the world, plays important roles in global climate change. During the last decade, Amazonia has experienced abnormal climate events related with recent global climate change such as severe droughts in 2005 and 2010 and extreme flooding in 2009. In this study, we show the variations of Amazon River channel flow associated with the extreme climate events with satellite gravity observation. The channel flow signal is identified via applying Empirical Orthogonal Function (EOF) for GRACE gravity data. The leading principal component (PC) shows the similar temporal variations of the Amazon River water level from satellite altimetry observation, and its spatial pattern is similar to geographic location of the river channel. The 2nd mode exhibits the North-South dipole pattern of water mass variations with the river channel as the base, and this explains one of causes for the flooding and droughts. This study of the water mass variation along the river channel is potentially useful to examine Amazon River base flow when combined with the total discharge estimate from GRACE and reanalysis.

Eom, J.; Seo, K.

2013-12-01

69

Discharge and Suspended Sediment Flux Estimated along the Mainstream of the Amazon and the Madeira Rivers (from in situ and MODIS Satellite Data)  

E-print Network

are considered during the period 2000�2008 in a region including the full Amazon River from the confluence to stations located on the Amazon River; second to investigate the possibility to propagate the signal along the Amazon River which dynamics is coupled with floodplains dynamics; and third to produce optimal solutions

70

Large-scale hydrologic and hydrodynamic modelling of the Amazon River basin2 Rodrigo Cauduro Dias de Paiva1,2  

E-print Network

1 Large-scale hydrologic and hydrodynamic modelling of the Amazon River basin2 3 4 Rodrigo Cauduro/hydrodynamic modelling of the Amazon River basin24 is presented using the MGB-IPH model with a validation using remotely vulnerability to natural hazards, particularly in55 the Amazon River basin, where extreme hydrological events

Paris-Sud XI, Université de

71

Trapping of sediment along the Amazon tidal river in diverse floodplain environments  

NASA Astrophysics Data System (ADS)

The Amazon tidal river, the freshwater reach that is influenced by tides, extends roughly 800 kilometers upstream of the river mouth. Previous studies suggest that up to one third of the sediment measured at the upstream limit of tides does not reach the ocean, and is likely trapped along the tidal river. Here we present data from a variety of depositional environments along this reach, including intertidal vegetated floodplains, floodplain lakes, and drowned tributary confluences. Sediment delivery to each of these environments is temporally variable as a result of changing tides and river stage, and spatially variable along the continuum from the purely fluvial upstream condition to the strongly tidal downstream environment. Short-term instrument records and direct observations are paired with sedimentological and radiochemical techniques to identify mechanisms of sediment exchange between river and floodplain and associated patterns of sediment accumulation. Sediments in vegetated intertidal floodplains exhibit tidal laminations and incised channel networks similar to muddy marine intertidal areas. Floodplain lakes experience dramatic seasonal changes in size, and during high flows of the river skim water and sediment from the Amazon River by providing a shortcut relative to the meandering mainstem. Amazon sediment is fluxed into the drowned tributary confluences (rías) of the Xingu and Tapajos Rivers by density-driven underflows. In the Tapajos Ría, sediment from the Amazon River has built a 25-km long birdfoot delta, suggesting these tributaries may be net sinks of sediment, rather than sources. These findings help define the importance of each tidal environment in trapping Amazon sediment before it reaches the marine environment.

Fricke, A. T.; Nittrouer, C. A.; Ogston, A. S.; Nowacki, D. J.; Souza Filho, P. W.; Silveira, O.; Asp, N. E.

2013-12-01

72

Organic matter in Bolivian tributaries of the Amazon River: A comparison to the lower mainstream  

Microsoft Academic Search

We determined the concentrations and compositions of coarse particulate (.63 mm), fine particulate (0.1-63mm), and dissolved (0.001-0.1 mm) organic matter collected along a river reach extending from a first-order stream in the Bolivian Andes, through the Beni River system, to the lower Madeira and Amazon Rivers. Dissolved organic carbon (DOC) concentrations increased down the total reach from ;80 to 350

John I. Hedges; Emilio Mayorga; Elizabeth Tsamakis; Michael E. McClain; Anthony Aufdenkampe; Paul Quay; Jeffrey E. Richey; Ron Benner; Steve Opsahl; Brenda Black

2000-01-01

73

Fluid dynamics, sediment transport and turbulent mixing at large confluences of the Amazon River  

NASA Astrophysics Data System (ADS)

The Clim-Amazon Project aims to study temporal sedimentary records to understand the mechanisms involved in climate and geodynamic changes and the processes involved in dissolved and suspended load evolution of the Amazon River basin from the Miocene to present. The knowledge of the present Amazon River sediment discharge and of its variability is fundamental since it can be linked to the on-going climatic and erosion processes at the regional scale. Understanding the relationships between these processes will be helpful to better interpret the observations of the past sedimentation rates. Within this general objective the aim of this study is to investigate the complex fluid dynamics, sediment transport and water quality processes occurring at the large confluences in the Amazon River, through a combination of theoretical, experimental (field) and numerical research. In the last decades a wide body of theoretical, experimental, and field research has emerged on the fluvial dynamics of river confluences, which are integral and ubiquitous features of river networks. Through this research substantial advances have been made into understanding the hydrodynamics and morphodynamics of river confluences which will be outlined here. However, to date most experimental studies have focused either on laboratory confluences or on small to medium sized natural confluences, whereas an extremely limited number of investigations about the confluences on large rivers. Presently little is understood about how river confluence hydrodynamics may vary with the size of the river, especially in the largest rivers. The Amazon River is the largest river in the World, with approximately 15,000 sub-branches joining the Amazon River within the Amazon Basin including some of the largest confluences on Earth. A study region containing three of the larger confluences between Manacapuru and Itacoatiara will be used as part of this study, with the primary focus being the confluence of the Rio Negro and Rio Solimões. The primary objective of this study is to develop a conceptual model for flow dynamics and sediment transport about such large confluences through analysis of field data, to assist with general objectives of the Clim-Amazon Project and improve general understanding of large confluence dynamics. While another objective is to apply CFD methods based on field measurements to improve the understanding of the dynamical processes that determine water quality parameters and sediment transport, mixing and accumulation at the confluences of large rivers such as the Amazon River. Therefore the main focus of this presentation will be the proposed field methodology for collecting hydrodynamic, sediment transport, water quality and bathymetric data about these large confluences within the study region of the Amazon River. As well as how the data collected during these field measurements will be analysed and used to develop conceptual and numerical models of such large confluences.

Trevethan, Mark; Gualtieri, Carlo; Filizola, Naziano; Ianniruberto, Marco

2014-05-01

74

Storage and remobilization of suspended sediment in the lower amazon river of Brazil  

USGS Publications Warehouse

In the lower Amazon River, suspended sediment is stored during rising stages of the river and resuspended during falling river stages. The storage and resuspension in the reach are related to the mean slope of the flood wave on the river surface; this slope is smaller during rising river stages than during falling stages. The pattern of storage and resuspension damps out the extreme values of high and low sediment discharge and tends to keep them near the mean value between 3.0 ?? 106 and 3.5 ?? 106 metric tons per day. Mean annual discharge of suspended sediment in the lower Amazon is between 1.1 ?? 109 and 1.3 ?? 109 metric tons per year.

Meade, R.H.; Dunne, T.; Richey, J.E.; Santos, U.De. M.; Salati, E.

1985-01-01

75

The evolution of organic matter along the lower Amazon River continuum - Óbidos to the ocean  

NASA Astrophysics Data System (ADS)

The influence of the Amazon River on global hydrologic and biogeochemical cycling is well recognized. The Amazon River provides roughly 16% of the global freshwater supply to the ocean and is a significant source of CO2 to the atmosphere, outgassing 0.5 Pg C y-1 to the atmosphere--a flux roughly equivalent to the amount of carbon 'sequestered' by the Amazon rainforest (Field et al, 1998; Richey et al., 2002; Malhi et al., 2008). However, much of our understanding of the flux of matter from the Amazon River into the Atlantic Ocean (and atmosphere) is limited to measurements made at and upstream of Óbidos, 900 km upstream from the actual river mouth. Further, there are few to no observations documenting the transformation of organic matter in a parcel of water as it travels downstream of Óbidos into the ocean. Here we explore the hydrological and biogeochemical evolution of the lower Amazon River continuum, from Óbidos to the Atlantic Ocean. A suite of dissolved and particulate organic matter (OM) parameters were measured during a series of five river expeditions with stations at Óbidos, the Tapajós tributary, the mouth of the Lago Grande de Curuai floodplain lake, both the north and south channels of the Amazon River mouth near Macapá, and the confluence of the Amazon and Tocantins Rivers near Belém. In addition to bulk carbon isotopic signatures, a suite of biomarkers including dissolved and particulate lignin-derived phenols were measured to trace the sources and degradation history of terrestrial vascular plant derived OM throughout the continuum. Dissolved and particulate lignin phenol concentrations both correlated positively with river discharge in the Amazon River mainstem, with variable export patterns from the tributaries and floodplains. As organic matter travels along the continuum it is degraded by microbial composition, fuelling gross respiration and CO2 outgassing. The flux of organic carbon to the ocean is chemically recalcitrant as a result of the constant biological processing of labile OM throughout the lower river. We estimate that 40% of the vascular plant-derived organic carbon sequestered by the terrestrial biosphere is degraded within soils, 55% is degraded along the river continuum, and less than 5% is delivered to the ocean (Ward et al., 2013) References Cited Field, C., M. Behrenfeld, J. Randerson, and P. Falkowski. 1998. Primary production of the biosphere: Integrating terrestrial and oceanic components. Science 281, 237-240. Malhi, Y., Roberts, J.T., Betts, R.A., Killeen, T.J., Li, W., Nobre, C.A. 2008. Climate change, deforestation, and the fate of the Amazon. Science 319, 169-172. Richey, J. E., Melack, J. M., Aufdenkampe, A. K., Ballester, V. M. & Hess, L. L. 2002. Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2. Nature 416, 617-620. Ward, N.D.; Keil, R.G.; Medeiros, P.M.; Brito, D.C.; Cunha, A.C.; Dittmar, T.; Yager, P.L.; Krusche, A.V.; Richey, J.E. 2013. Degradation of terrestrially derived macromolecules in the Amazon River. Nature Geoscience. doi: 10.1038/ngeo1817

Ward, N. D.; Keil, R. G.; Medeiros, P. M.; Brito, D.; Cunha, A.; Sawakuchi, H. O.; Moura, J. S.; Yager, P. L.; Krusche, A. V.; Richey, J. E.

2013-12-01

76

Marine environmental changes at the Brazilian equatorial margin related to Amazon River evolution during the Neogene  

NASA Astrophysics Data System (ADS)

Today, the nutrient-rich Amazon River outflow causes massive algal blooms in the western equatorial Atlantic Ocean, forming a considerable carbon sink as well as a primary food source in the otherwise oligotrophic surface water. However, the history of this high-productivity system is largely unknown, although a strong relation to the evolution of the Amazon River can be expected. The Amazon submarine fan provides direct evidence for the development of a transcontinental river system, of which the base of the primarily Andean-sourced siliciclastic deposits is dated as late Miocene. Ditch cuttings from Amazon Fan exploration 'Well 2' were made available by Petrobras for microfossil and lithological research. 'Well 2' is located on the uppermost fan at a water depth of 750 meters. Organic-walled dinoflagellate cyst and foraminifer assemblages were studied to reconstruct Neogene marine environmental changes in relation to the Amazon River development. Planktonic foraminifera are present throughout the studied section and largely confirm the already available biostratigraphic age determination based on nannofossils. Benthic foraminifer assemblages indicate that the paleo-water depth has not substantially deviated from current conditions. The ecological affinities of most observed dinocyst taxa are well known, which allows us to reconstruct changes in paleo-productivity based on the assemblages. Mineral composition suggests that local river systems already drained into the Amazon basin before the onset of the transcontinental system, but environmental conditions remained oligotrophic at this time. Decreased abundances of both dinocysts and planktonic foraminifera during the Pleistocene are related to highest sedimentation rates (dilution effect). Overall, a complex interplay of orogenesis, climatic and sea level variations during the Neogene are responsible for the fluvially-induced changes in the marine environment at the Atlantic margin.

Lammertsma, Emmy; Troelstra, Simon; Sangiorgi, Francesca; Chemale, Farid, Jr.; do Carmo, Dermeval A.; D'Avila, Roberto; Soares, Emilson; Hoorn, Carina

2014-05-01

77

VENEZUELAN EQUINE ENCEPHALITIS FEBRILE CASES AMONG HUMANS IN THE PERUVIAN AMAZON RIVER REGION  

Microsoft Academic Search

A survey was conducted from October 1, 1993 to June 30, 1995 to determine the arboviral etiologies of febrile illnesses in the city of Iquitos in the Amazon River Basin of Peru. The study subjects were patients who were enrolled at medical care clinics or in their homes by Peruvian Ministry of Health (MOH) workers as part of the passive

DOUGLAS M. WATTS; JOHNNY CALLAHAN; CINDY ROSSI; M. STEVEN OBERSTE; J. T. ROEHRIG; MARK T. WOOSTER; JONATHAN F. SMITH; C. B. CROPP; ELMER M. GENTRAU; NICK KARABATSOS; DUANE GUBLER; CURT G. HAYES

78

Estimating suspended sediment concentrations in surface waters of the Amazon River wetlands from Landsat images  

Microsoft Academic Search

A method has been developed, based on spectral mixture analysis, to estimate the concentration of suspended sediment in surface waters of the Amazon River wetlands from Landsat MSS and TM images. Endmembers were derived from laboratory reflectance measurements of water-sediment mixtures with a range of sediment concentrations. Using these references spectra, the authors applied a linear mixture analysis to multispectral

L. A. K. Mertes; M. O. Smith; J. B. Adams

1993-01-01

79

The Amazon river breeze and the local boundary layer: I. Observations  

Microsoft Academic Search

Observations of the diurnal evolution of the planetary boundary layer over the Amazon rain forest, made at sites close to the confluence of the Solimões and Negro rivers (approximately at 3°S, 60°W) near Manaus, Amazonas, Brazil, show the existence of a diurnal rotation of the wind near the surface and the frequent presence of low-level nocturnal wind maxima. These circulations

AMAURI PEREIRA DE OLIVEIRA; David R. Fitzjarrald

1993-01-01

80

Source, transport and fluxes of Amazon River particulate organic carbon: Insights from river sediment depth-profiles  

NASA Astrophysics Data System (ADS)

In order to reveal particulate organic carbon (POC) source and mode of transport in the largest river basin on Earth, we sampled the main sediment-laden tributaries of the Amazon system (Solimões, Madeira and Amazon) during two sampling campaigns, following vertical depth-profiles. This sampling technique takes advantage of hydrodynamic sorting to access the full range of solid erosion products transported by the river. Using the Al/Si ratio of the river sediments as a proxy for grain size, we find a general increase in POC content with Al/Si, as sediments become finer. However, the sample set shows marked variability in the POC content for a given Al/Si ratio, with the Madeira River having lower POC content across the measured range in Al/Si. The POC content is not strongly related to the specific surface area (SSA) of the suspended load, and bed sediments have a much lower POC/SSA ratio. These data suggest that SSA exerts a significant, yet partial, control on POC transport in Amazon River suspended sediment. We suggest that the role of clay mineralogy, discrete POC particles and rock-derived POC warrant further attention in order to fully understand POC transport in large rivers.

Bouchez, Julien; Galy, Valier; Hilton, Robert G.; Gaillardet, Jérôme; Moreira-Turcq, Patricia; Pérez, Marcela Andrea; France-Lanord, Christian; Maurice, Laurence

2014-05-01

81

Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere  

Microsoft Academic Search

Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1,700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 ({plus minus} 20) mg CHâ m⁻² d⁻¹ and were

Allan H. Devol; Jeffrey E. Richey; Bruce R. Forsberg; Luiz A. Martinelli

1990-01-01

82

Iron isotopes in the Amazon River system: Weathering and transport signatures  

Microsoft Academic Search

Trace metal clean plankton tows, river samples, aerosol leachates, and porewater samples from the Amazon River system were measured for their iron isotopic composition. The overall isotopic range observed was 1.5‰ with Fe isotopic variability observed between different types of tributaries. Dissolved Fe and suspended load Fe from two main channel sites were isotopically similar (? ?0.1 to ?0.3‰). In contrast,

B. A. Bergquist; E. A. Boyle

2006-01-01

83

Microbial community composition and metagenomes across the river-to-ocean continuum of the Columbia and Amazon Rivers (Invited)  

NASA Astrophysics Data System (ADS)

Rivers are the primary conduits for land-to-ocean transfer of materials including terrestrial organic matter, nutrients and anthropogenic pollutants. Microbial communities in rivers, estuaries, and plumes regulate the nutrient concentrations and biogeochemistry of these riverborne materials and mediate their impact on carbon cycling. Despite their importance little is known about the composition and genetic capabilities of these organisms. Here we describe and compare the phylogeny and metagenomic profiles of microbial communities across the river-to-ocean gradients of two very large rivers: the tropical Amazon and temperate Columbia rivers. For the Amazon, samples were collected from the lower 600 km of the river and from surface waters across 1300 km of the plume in 2010 and 2011. For the Columbia, samples were collected along the gradient from river to deep ocean during 14 cruises between 2007 and 2010. Amplicon pyrosequencing of bacterial 16S rRNA genes showed that bacterial communities were similar along the length of the lower Amazon River with variability caused by inputs from major tributaries. Freshwater taxa from both rivers were very rare in plume waters, but in the Columbia River estuary freshwater taxa mixed with marine communities. Communities in both rivers shifted with local seasons, likely due to changes in river environmental conditions including dissolved and particulate organic matter, river flow, and light availability. Seasonal variability was less pronounced in river plumes where spatial variability was greater than temporal variability. Bacterial community composition was very different between the two systems, and was most similar at the marine end of the gradient outside the plumes. Illumina-based metagenomic analyses of a subset of these samples showed similarity in the relative abundance of many annotated gene categories despite differences in phylogeny across salinity gradients. However, several categories of genes varied in relative abundance including genes involved in carbon transformations, revealing distinct patterns in genomic capabilities across the Amazon and Columbia River systems. Together, these phylogenetic and metagenomic data provide insight into the spatial and seasonal succession of microbes and biogeochemical processes associated with riverborne material as it transits from the mountains to the oceans.

Crump, B. C.; Doherty, M.; Fortunato, C.; Simon, H. M.; Smit, M. W.; Krusche, A. V.; Brito, D.; Cunha, A.; Fernandes, M.; Zielinski, B.; Paul, J. H.; Ward, N. D.; Richey, J. E.; Satinsky, B. M.; Sharma, S.; Smith, C. B.; Moran, M.; Yager, P. L.

2013-12-01

84

Modeling River Hydrologic Regime and Spawning of Migratory Catfishes in Southeastern Peruvian Amazon  

NASA Astrophysics Data System (ADS)

Seasonal hydrologic conditions and catfish larvae production were evaluated in the Madre de Dios River in order to determine whether environmental conditions influence the reproductive activity of a group of large, commercially important catfishes, in the Southeastern Peruvian Amazon. A simple stochastic model of floods is presented to describe the influence of the natural high flow regime on observed patterns of catfish larvae release and drifting. Daily river stage records at Puerto Maldonado are related to weekly larval catches to determine the association between flood and spawning events. On the basis of hydroclimatologic characteristics of Andean- Amazon regions, available long-term historical rainfall records are employed to approximate the likely inter- annual variability of floods within this Amazon headwater basin. Major larval drift appeared associated with stages of over the 5 m, or "Biologic Hydrologic Significant Events" (BSE), which act as triggers, or a reasonable surrogates, for spawning responses of these species. The timing of BSEs, estimated from the historical rainfall records, appear to be uniformly distributed during the rain season and their inter-arrival times exponential. These observations provided the basis of the stochastic model describing the likelihood of volumes of larvae releases from the headwater region to lowland Amazon. The ecologically significant role of the hydroclimatology of this region in the complete life cycle of this important Amazon fish resource is illustrated.

Canas, C. M.; Waylen, P. R.

2008-05-01

85

The geochemistry of rare earth elements in the Amazon River estuary  

SciTech Connect

The estuarine geochemistry of rare earth elements (REEs) was studied using samples collected in the Amazon River estuary from the AmasSeds (Amazon Shelf SEDiment Study) cruise of August 1989. Extensive removal of dissolved (0.22 [mu]m filtered) trivalent REEs from river water occurs in the low (0--6) salinity region. Removal by the salt-induced coagulation of river colloids leads to fractionation among the REE(III) series; the order of removal is light REEs > middle REEs > heavy REEs. There also is the enhanced removal of Ce (relative to trivalent La and Nd) in the low salinity (0--6) zone and in the zone of high biological activity. This is the first field observation of strong Ce removal associated with coagulation of river colloids and biological productivity. The argument is made that the decrease in the Ce anomaly across a biological front is caused by biologically mediated oxidation of Ce(III) to Ce(IV). Coagulation of river colloids and biologically mediated oxidation of Ce(III) lead to fractionation of REE(III) and redox modification of Ce. These processes result in the REE composition becoming fractionated relative to the Amazon River water and crust and more evolved toward the REE composition of the oceans. This study implies that reactions in estuaries play significant, yet poorly understood roles in controlling the REE composition and Ce anomaly of the oceans. 46 refs., 9 figs., 2 tabs.

Shokovitz, E.R. (Woods Hole Oceanographic Institution, MA (United States))

1993-05-01

86

McClain ME, R Galarraga, CA Llerena & JE Ruiz. 2007. Linking Global Change Research to Improved Policies and Management for Rivers: Lessons from the Andean Amazon Rivers Analysis and Monitoring  

E-print Network

Policies and Management for Rivers: Lessons from the Andean Amazon Rivers Analysis and Monitoring Project and management for rivers: Lessons from the Andean Amazon Rivers Analysis and Monitoring project Michael E. Mc that climate changes will only exacerbate their current development problems (CONAM 2002). Rivers

McClain, Michael

87

Geochemical behavior of rare earth elements and other trace elements in the Amazon River  

NASA Astrophysics Data System (ADS)

Rivers transport large amounts of dissolved and suspended particulate material from the catchment area to the oceans and are a major source of trace metals to seawater. The Amazon River is the world's largest river and supplies approximately 20% of the oceans' freshwater (Molinier et al., 1997). However, the behavior of trace elements, especially particle-reactive elements such as the rare earth elements (REE), within the river as well as in the estuary is not well constrained and rather little is known about their transport mechanisms. This study aims at understanding the transport properties of particle-reactive elements in the Amazon River and some of its major tributaries, including the Rio Solimões, Rio Negro, Tapajos, Xingu and Jari Rivers. Samples were taken at 12 stations, seven of which were located in the Amazon mainstream, while the other five stations sampled its tributaries. To account for the effects of variable discharge, the samples were collected during periods of high and low discharge. We present data for major and trace elements, including REE, of the dissolved and suspended load of these samples. First results indicate that the shale-normalized REE pattern of the dissolved load (filtered through 0.2 µm membranes) of the Amazon mainstream and the Rio Solimões confirm earlier studies (Elderfield et al., 1990; Gerard et al., 2003) and show an enrichment of the middle REE relative to the light and heavy REE (LaSN/GdSN: 0.25 - 0.32; GdSN/YbSN: 1.54 - 1.78). In contrast to the Amazon mainstream and the Rio Solimões, which are considered to be whitewater rivers, blackwater rivers, such as the Rio Negro, have a flat REE pattern with higher REE concentrations than whitewater rivers. The third water-type found in the Amazon Basin is clearwater, e.g. Rio Tapajos, with REE patterns in between those of the other two types, i.e. LaSN/GdSN: 0.55 - 0.70; GdSN/YbSN: 1.26 - 1.55. A similar behavior can be identified for other major and trace elements. While elements such as Ca, Mg, Sr or U are relatively high in whitewater rivers, their concentrations are generally lower in clearwater rivers and lowest in blackwater rivers. In contrast, elements including Si, Rb and Cs have their highest concentrations in blackwater rivers, intermediate concentrations in clearwater rivers and their lowest concentrations in whitewater river. [1] Elderfield H., Upstill-Goddard R. and Sholkovitz E.R. (1990): The rare earth elements in rivers, estuaries and coastal seas and their significance to the composition of ocean waters. Geochim.Cosmochim.Acta, 54, 971-991 [2] Gerard M., Seyler P., Benedetti M.F., Alves V.P., Boaventura G.R. and Sondag, F. (2003): Rare earth elements in the Amazon basin. Hydrological Processes, 17, 1379-1392 [3] Molinier M., Guyot J.L., Callede J., Guimaraes V., Oliveira E. and Filizola N. (1997): Hydrologie du bassinamazonien. Evironment et développement en Amazonie brésiliènne, Thery H. (ed.), Berlin Publ., Paris; 24-41

Merschel, Gila; Bau, Michael; Dantas, Elton Luiz

2014-05-01

88

Distribution and flux of /sup 226/Ra and /sup 228/Ra in the Amazon River estuary  

SciTech Connect

Measurements of /sup 226/Ra and /sup 228/Ra in the Amazon River estuary show that desorption from riverborne suspended particulate matter in the estuary increases the riverine flux of both isotopes to the ocean by a factor of approximately 5 over the flux attributable to radium dissolved in the river water alone. The total Amazon flux supplies approximately 0.20% of the /sup 226/Ra and approximately 2.6% of the /sup 228/Ra standing crops in the near-surface Atlantic (0-200 m). Diffusive flux from estuarine and shelf sediments and desorption from resuspended sediments in the region of the estuary approximately double the estuarine /sup 226/Ra concentration and quadruple the estuarine /sup 228/Ra concentration above that caused by the dissolved and desorbed river components alone.

Key, R.M.; Sarmiento, J.L.; Stallard, R.F.; Moore, W.S.

1985-07-20

89

Source area and seasonal variation of dissolved Sr isotope composition in rivers of the Amazon basin  

NASA Astrophysics Data System (ADS)

We present dissolved Sr isotope data collected over 8 years from three main river systems from the Amazon Basin: Beni-Madeira, Solimões, Amazon, and Negro. The data show large 87Sr/86Sr ratio variations that were correlated with the water discharge and geology of the source areas of the suspended sediments. The Beni-Madeira system displays a high average 87Sr/86Sr ratio and large 87Sr/86Sr fluctuations during the hydrological cycle. This large average value and fluctuations were related to the presence of Precambrian rocks and Ordovician sediments in the source area of the suspended sediment of the river. In contrast, the Solimões system displays a narrow range of Sr isotope ratio variations and an average value close to 0.709. This river drains mostly Phanerozoic rocks of northern Peru and Ecuador that are characterized by low Sr isotope ratios. Despite draining areas underlain by Precambrian rocks and having high 87Sr/86Sr ratios, such rivers as the Negro and Tapajós play a minor role in the total Sr budget of the Amazon Basin. The isotopic fluctuations in the Beni-Madeira River were observed to propagate downstream at least as far as Óbidos, in the Amazon River. This signal is characterized by an inverse relationship between the concentration of elemental Sr and its isotopic ratios. During the raining season there is an increase in Sr isotopic ratio accompanied by a decrease in elemental Sr concentration. During the dry season, the Sr isotopic ration decreases and the elemental Sr concentration increases.

Santos, Roberto V.; Sondag, Francis; Cochonneau, Gerard; Lagane, Christelle; Brunet, Pierre; Hattingh, Karina; Chaves, Jeane G. S.

2014-05-01

90

The Amazon river breeze and the local boundary layer. I - Observations  

NASA Technical Reports Server (NTRS)

Observations of the diurnal evolution of the planetary boundary layer over the Amazon rain forest, made at sites close to the confluence of the Solimoes and Negro rivers (approximately at 3 deg S, 60 deg W) near Manaus, Amazonas, Brazil, show the existence of a diurnal rotation of the wind near the surface and the frequent presence of low-level nocturnal wind maxima. These circulations are shown to be plausibly explained as elements of a river and land breeze circulation induced by the thermal contrast between the rivers and the adjacent forest.

De Oliveira, Amauri P.; Fitzjarrald, David R.

1993-01-01

91

A RETROSPECTIVE STUDY OF PATHOLOGIC FINDINGS IN THE AMAZON AND ORINOCO RIVER DOLPHIN (INIA GEOFFRENSIS) IN CAPTIVITY  

Microsoft Academic Search

River dolphins are especially susceptible to negative human impacts. For their conservation, attempts of relocation or procreation ex situ may become important in the future to avoid their extinction. Additional knowledge and medical experiences of river dolphin management in captivity may aid such conservation efforts. The medical records and necropsy and histopathology reports on 123 captive Amazon River dolphins (Inia

Christopher J. Bonar; Ernesto O. Boede; Manuel García Hartmann; Joanne Lowenstein-Whaley; Esmeralda Mujica-Jorquera; Scott V. Parish; James V. Parish; Michael M. Garner; Cynthia K. Stadler

2007-01-01

92

Drainage reversal of the Amazon River due to the coupling of surface and lithospheric processes  

NASA Astrophysics Data System (ADS)

The uplift of central and northern Andes occurred concomitantly with an important reorganization of the drainage pattern in the northern South America. In Early Miocene, the fluvial systems that flowed from the Amazonian craton towards the sub-Andean basins and northward to the Caribbean were replaced by a megawetland, the Pebas system, covering more than 106 km in western Amazonia. By Late Miocene the Pebas system progressively disappeared and gave place to the transcontinental Amazon River, connecting the Andes and the equatorial Atlantic margin. A previous work suggested that the reversal of the Amazon River and the disappearance of the Pebas system were driven by dynamic topography promoted by mantle convection. Based on a three-dimensional numerical model that couple surface processes, flexural isostasy and crustal thickening due to orogeny, here I propose that the response of the surface processes to the uplift of the central and northern Andes, along with the flexural isostasy of the lithosphere, can explain the drainage reversal of the Amazon River during Miocene time with no need to invoke dynamic topography induced by mantle convection. Moreover, according to this new numerical model, the timing of the drainage reversal in the northern South America is mainly controlled by the efficiency of the sediment transport within the drainage basins and the rate of the Andean uplift. Also, the present numerical experiments were able to predict the increase in sedimentation rate in the Amazon fan after the drainage reversal of the Amazon River as observed in Late Miocene-Pliocene sedimentary record. However, the proposed model fails to fully reproduce the spacial and temporal evolution of the Pebas system as observed in geological data. Further investigation is therefore needed in order to understand the dynamic interaction between surface and tectonic processes and their implications on the development of a megawetland that preceded the reversal of Amazon River drainage. Nevertheless, this work can give new insights into the landscape and stratigraphic evolution of northern South America during Andean orogeny, providing quantitative constraints for the paleogeography reconstructions of Amazonia.

Sacek, Victor

2014-09-01

93

The prevalence of musculoskeletal disorders among prawn seed collectors of Sunderbans.  

PubMed

In India, particularly in Sunderban of West Bengal, collection of prawn seeds is one of the major earning resources among prawn seed collectors. They are compelled to carry out a considerable amount of hard, manual, rigorous tasks in the river of the Sunderban area for collecting prawn seeds. They have to adopt some undesirable postures that may lead to the development of musculo skeletal disorder (MSD). The main aim of the present study is to investigate the prevalent postures adopted by the prawn seed collectors during individual prawn seed collection and to analyze the causation of discomfort feeling related with those postures. For this study, 21 male and 25 female prawn seed collectors were selected randomly and a detailed posture analysis was performed among them by means of OWAS method. It was observed that these workers worked continuously in awkward postures during certain prawn seed collection activity and consequently they suffered from discomfort feeling (pain) in different parts of the body. PMID:19227195

Gangopadhyay, Somnath; Das, Banibrata; Ghoshal, Goutam; Das, Tamal; Ghosh, Tirthankar; Ganguly, Ramjyoti; Samanto, Kshinangsu

2008-12-01

94

Compositions and fluxes of particulate organic material in the Amazon River  

Microsoft Academic Search

Lignin, elemental, and stable carbon isotope compositions are reported for local plants and for coarse (>63 pm) and fine (~63 pm) suspended particulate materials collected along a 1,950-km reach of the lower Amazon River during four contrasting stages of the 1982-1983 hydrograph. Fluxes of chemically recognizable lignin in the two size classes generally parallel each other along the mainstem with

JOHN I. HEDGES; WAYNE A. CLARK; PAUL D. QUAY; JEFFREY E. RICHEY; ALLAN H. DEVOL; UMBERTO DE M. SANTOS

1986-01-01

95

C-13\\/C-12 of atmospheric CO2 in the Amazon basin - Forest and river sources  

Microsoft Academic Search

Results are presented of measurements of the CO2 concentrations and C-13\\/C-12 ratios in CO2 in air samples collected from within the Amazonian rain forest and over the Amazon river between 1982 and 1987. Results indicate the presence of a diurnal cycle in the CO2 concentration and the C-13\\/C-12 ratio. It was found that the CO2 input to air in the

Paul Quay; Stagg King; Dave Wilbur; Jeffrey Richey; Steven Wofsy

1989-01-01

96

Sr?Nd?Pb isotope systematics in Amazon and Congo River systems: constraints about erosion processes  

Microsoft Academic Search

87Sr86Sr, 143Nd144Nd, 206Pb204Pb, 207Pb204Pb and 208Pb204Pb isotopic ratios and Rb, Sr, Sm, Nd, U, Pb and Th concentrations have been measured in the suspended loads of the Congo and Amazon rivers and their tributaries. In the dissolved load, 87Sr86Sr, Rb, Sr, Nd, Sm, U, Pb and Th concentrations are also reported.These results show that Nd, Sm, Th and Pb are

Claude J. Allègre; Bernard Dupré; Philippe Négrel; Jérôme Gaillardet

1996-01-01

97

A significant CO2 sink in the tropical Atlantic Ocean associated with the Amazon River plume  

Microsoft Academic Search

During Meteor cruise 55 a strong undersaturation of surface seawater with respect to atmospheric CO2 was found in the Amazon River plume which is advected into the surface circulation of the tropical Atlantic. A conservative estimate of the plume-related CO2 sink in the tropical Atlantic yields a net air-sea flux of 0.014 +\\/- 0.005 Pg C yr-1. The corresponding average

Arne Körtzinger

2003-01-01

98

A macroscale hydrological data set of river flow routing parameters for the Amazon Basin  

NASA Astrophysics Data System (ADS)

Continental-scale hydrologic routing models, also known as macrohydrological routing models, have evolved considerably in the past few years. As the models have become more sophisticated, they have represented a variety of new processes and expanded their data requirements-either as input data or as validation for the model output. This paper presents a new data set of large-scale hydrological river flow routing parameters for the Amazon and Tocantins basins. Part of this data set was required by the development of the continental-scale hydrological routing model HYDRA and its application to the Amazon Basin. HYDRA represents phenomenalike floods, backwater effects, and seasonal hydrograph much more realistically than the previous generation of macrohydrological routing models. The data set contains data on (1) river network at 5-min (~9 km) resolution, (2) time series of monthly means of river discharge and river stage for 122 fluviometric stations spread throughout the basin, (3) sinuosity of each of the main rivers measured at 111 river sections in the basin, and (4) depth to the water table and transmissivity of the aquifer derived from measurements taken at 81 points throughout the basin.

Costa, Marcos Heil; Oliveira, Carlos Henrique C.; Andrade, Ricardo G.; Bustamante, Thiago R.; Silva, Fabrício A.; Coe, Michael T.

2002-08-01

99

Numerical simulation of drainage reversal of the Amazon River during Andean orogeny  

NASA Astrophysics Data System (ADS)

The uplift of Central and Northern Andes occurred concomitantly with an important reorganization of the drainage pattern in Northern South America. During the Early Miocene, the fluvial systems that flowed from the Amazonian Craton toward the sub-Andean basins and northward to the Caribbean were replaced by a megawetland, the Pebas system, covering a large fraction of the Western Amazonia. In the Late Miocene the Pebas system progressively disappeared and gave place to the transcontinental Amazon River, connecting the Andes and the equatorial Atlantic margin. A previous work suggested that the reversal of the Amazon River and the disappearance of the Pebas system were driven by dynamic topography promoted by mantle convection. Based on numerical models that couple surface processes, flexural isostasy and crustal thickening due to orogeny, here I propose that the response of the surface processes to the uplift of the Central and Northern Andes, along with the flexural isostasy of the lithosphere, can explain the drainage reversal of the Amazon River during the Miocene without invoking dynamic topography induced by mantle convection. In addition I observed that the existence, the permanence and the size of a megawetland in Northern South America is controlled by the rate of crustal thickening in the orogeny, the rate of erosion and, mainly, the efficiency of the sediment transport through the drainage basins during the Andean uplift.

Sacek, Victor

2014-05-01

100

Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere  

SciTech Connect

Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1,700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 ({plus minus} 20) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1} and were significantly lower than similar emissions determined previously for the high-water period, 184 ({plus minus} 41) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1} (July-August 1986). This difference was due to significantly lower emissions from floating macrophyte environments. Low-water emissions from open waters and flooded forest areas were not significantly different than at high water. A monthly time series of methane emissions from eight lakes located in the central Amazon basin showed similar results. Average annual emission from the lakes was 125 ({plus minus} 28) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1}. Methane emissions from lakes were significantly higher during the high water period, again primarily due to an increase in emissions from macrophyte habitats. The data were used to calculate a seasonally weighted annual emission to the troposphere from the Amazon River main stem floodplain of 5.1 Tg yr{sup {minus}1}, which indicates the importance of the area in global atmospheric chemistry.

Devol, A.H.; Richey, J.E. (Univ. of Washington, Seattle (USA)); Forsberg, B.R. (Instituto Nacional de Pesquisas da Amazonia, Manaus (Brazil)); Martinelli, L.A. (Centro de Energia Nuclear na Agricultura, Piracicaba (Brazil))

1990-09-20

101

Turbulent mixing in the Amazon River: The isotopic memory of confluences  

NASA Astrophysics Data System (ADS)

Rivers continuously discharge dissolved material to the oceans. Dissolved compounds partially result from water-rock interactions, which produce a large range of water chemical and isotopic compositions. These waters are collected by rivers, that are commonly assumed to be well-mixed with regard to their different tributaries, as a result of turbulent dispersion. In this paper, we test this hypothesis on the Solimões River (at Manacapuru), the largest tributary of the Amazon River, by analyzing the sodium concentration and strontium isotopic composition of river water on a transverse section at different depths. High-precision measurements reveal lateral heterogeneities. This reflects poor mixing between two main river masses, that have distinct chemical and isotopic signatures, a hundred kilometers downstream from their confluence: the Solimões mainstream and the Purús River. Using sodium concentration data, the transverse dispersion coefficient is estimated for the studied Solimões reach (the Earth's largest river on which such an estimate now exists), and is found to be 1.8 ± 0.2 m 2/s. Comparison with previously reported data highlights the potential role of bed morphology and islands in the efficiency of lateral mixing in large rivers. We finally demonstrate that the characteristic length of lateral mixing downstream from confluences in large rivers is at least of several tens of kilometers.

Bouchez, Julien; Lajeunesse, Eric; Gaillardet, Jérôme; France-Lanord, Christian; Dutra-Maia, Poliana; Maurice, Laurence

2010-02-01

102

Contributions from the Amazon River mouth to the carbonate and nutrient dynamics of the tropical Atlantic Ocean (Invited)  

NASA Astrophysics Data System (ADS)

The Amazon River contributes considerable freshwater and dissolved constituents to the global ocean, and its low-salinity plume offshore significantly impacts the carbon and nutrient cycles of the western tropical North Atlantic Ocean. Viewing the river-plume-ocean system as a continuum, rather than a point source, is a key component of the ROCA / ANACONDAS project effort. Here we report the findings of a multi-season field effort in the lower reach of the Amazon mainstem and offshore plume to determine the concentrations and variability of the full carbonate system as well as dissolved inorganic nitrogen, phosphorus, and silica at the mouth, providing for the first time the critical "river end members" for the Amazon's contribution to the sea. We find that concentrations at the mouth differ significantly from measurements made upriver at Manaus and Óbidos, historically used to represent the Amazon's contribution. With these new end members, the impact of the plume on the tropical marine ecosystem can be better determined, including its role as a globally significant atmospheric carbon dioxide sink and its sensitivity to change. These data, in combination with other microbial and geochemical data from the Amazon River continuum, improve our understanding of the links between the river, the plume, and the tropical Atlantic carbon cycle, as well as improve predictive capabilities of future climate change impacts. True color satellite image of Amazon River plume - NASA pCO2 versus salinity for outer Amazon River plume with color bar showing chlorophyll a fluorescence. Line is linear regression through the data, not a mixing line.

Yager, P. L.; Richey, J. E.; Page, B. P.; Ward, N.; Krusche, A. V.; Weber, S.; Montoya, J. P.; Rezende, C. E.

2013-12-01

103

Oropouche virus transmission in the Amazon River basin of Peru.  

PubMed

Seroepidemiologic studies were conducted to determine the prevalence of Oropouche (ORO) viral antibody, risk factors, and the incidence of infection among residents of the Amazon region of Peru. Blood samples, as well as demographic, cultural, and medical history data, were collected from residents in a sector of the city of Iquitos and in an adjacent rural and three neotropical rain forest communities. Blood specimens were obtained approximately one year later from a cohort of the same study subjects who were negative for ORO antibody on the initial cross-sectional survey. Sera were tested for ORO IgG antibody by an enzyme-linked immunosorbent assay. Antibody prevalences were 35% for residents of the urban population, 24-46% for the forest communities, and 18% for the rural community. Antibody prevalence increased with age, and subjects who were seropositive were significantly (P = 0.001) older (mean = 33 years) than the seronegative subjects (mean = 15 years). Multivariate analysis revealed that only age, urban and forest residence, and occupation as a farmer or housekeeper remained significantly associated with seropositivity. Seroconversion data for the same populations one year later demonstrated evidence of ORO viral infection among 28% of the residents in the rural community and 2% or less in the forest and urban communities. Oropouche virus infection was significantly associated with older age (P = 0.04) in the rural community (P < 0.001). These data support prior evidence of ORO viral infection among residents of Iquitos and surrounding villages and suggest that transmission of this virus occurs continuously in the population of this area of the Amazon basin. PMID:9080872

Watts, D M; Phillips, I; Callahan, J D; Griebenow, W; Hyams, K C; Hayes, C G

1997-02-01

104

Simulating hydrologic and hydraulic processes throughout the Amazon River Basin  

USGS Publications Warehouse

Presented here is a model framework based on a land surface topography that can be represented with various degrees of resolution and capable of providing representative channel/floodplain hydraulic characteristics on a daily to hourly scale. The framework integrates two models: (1) a water balance model (WBM) for the vertical fluxes and stores of water in and through the canopy and soil layers based on the conservation of mass and energy, and (2) a routing model for the horizontal routing of surface and subsurface runoff and channel and floodplain waters based on kinematic and diffusion wave methodologies. The WBM is driven by satellite-derived precipitation (TRMM_3B42) and air temperature (MOD08_M3). The model's use of an irregular computational grid is intended to facilitate parallel processing for applications to continental and global scales. Results are presented for the Amazon Basin over the period Jan 2001 through Dec 2005. The model is shown to capture annual runoff totals, annual peaks, seasonal patterns, and daily fluctuations over a range of spatial scales (>1, 000 to <4D7M km2). For the period of study, results suggest basin-wide total water storage changes in the Amazon vary by approximately +/-5 to 10 cm, and the fractional components accounting for these changes are: root zone soil moisture (20%), subsurface water being routed laterally to channels (40%) and channel/floodplain discharge (40%). Annual variability in monthly water storage changes by +/-2.5 cm is likely due to 0D5 to 1 month variability in the arrival of significant rainfall periods throughout the basin. Copyright ?? 2009 John Wiley & Sons, Ltd.

Beighley, R.E.; Eggert, K.G.; Dunne, T.; He, Y.; Gummadi, V.; Verdin, K.L.

2009-01-01

105

Particulate Organic Matter Distribution along the Lower Amazon River: Addressing Aquatic Ecology Concepts Using Fatty Acids  

PubMed Central

One of the greatest challenges in understanding the Amazon basin functioning is to ascertain the role played by floodplains in the organic matter (OM) cycle, crucial for a large spectrum of ecological mechanisms. Fatty acids (FAs) were combined with environmental descriptors and analyzed through multivariate and spatial tools (asymmetric eigenvector maps, AEM and principal coordinates of neighbor matrices, PCNM). This challenge allowed investigating the distribution of suspended particulate organic matter (SPOM), in order to trace its seasonal origin and quality, along a 800 km section of the Amazon river-floodplain system. Statistical analysis confirmed that large amounts of saturated FAs (15:0, 18:0, 24:0, 25:0 and 26:0), an indication of refractory OM, were concomitantly recorded with high pCO2 in rivers, during the high water season (HW). Contrastingly, FAs marker which may be attributed in this ecosystem to aquatic plants (18:2?6 and 18:3?3) and cyanobacteria (16:1?7), were correlated with higher O2, chlorophyll a and pheopigments in floodplains, due to a high primary production during low waters (LW). Decreasing concentrations of unsaturated FAs, that characterize labile OM, were recorded during HW, from upstream to downstream. Furthermore, using PCNM and AEM spatial methods, FAs compositions of SPOM displayed an upstream-downstream gradient during HW, which was attributed to OM retention and the extent of flooded forest in floodplains. Discrimination of OM quality between the Amazon River and floodplains corroborate higher autotrophic production in the latter and transfer of OM to rivers at LW season. Together, these gradients demonstrate the validity of FAs as predictors of spatial and temporal changes in OM quality. These spatial and temporal trends are explained by 1) downstream change in landscape morphology as predicted by the River Continuum Concept; 2) enhanced primary production during LW when the water level decreased and its residence time increased as predicted by the Flood Pulse Concept. PMID:23029412

Mortillaro, Jean-Michel; Rigal, Francois; Rybarczyk, Herve; Bernardes, Marcelo; Abril, Gwenael; Meziane, Tarik

2012-01-01

106

Particulate organic matter distribution along the lower Amazon River: addressing aquatic ecology concepts using fatty acids.  

PubMed

One of the greatest challenges in understanding the Amazon basin functioning is to ascertain the role played by floodplains in the organic matter (OM) cycle, crucial for a large spectrum of ecological mechanisms. Fatty acids (FAs) were combined with environmental descriptors and analyzed through multivariate and spatial tools (asymmetric eigenvector maps, AEM and principal coordinates of neighbor matrices, PCNM). This challenge allowed investigating the distribution of suspended particulate organic matter (SPOM), in order to trace its seasonal origin and quality, along a 800 km section of the Amazon river-floodplain system. Statistical analysis confirmed that large amounts of saturated FAs (15:0, 18:0, 24:0, 25:0 and 26:0), an indication of refractory OM, were concomitantly recorded with high pCO(2) in rivers, during the high water season (HW). Contrastingly, FAs marker which may be attributed in this ecosystem to aquatic plants (18:2?6 and 18:3?3) and cyanobacteria (16:1?7), were correlated with higher O(2), chlorophyll a and pheopigments in floodplains, due to a high primary production during low waters (LW). Decreasing concentrations of unsaturated FAs, that characterize labile OM, were recorded during HW, from upstream to downstream. Furthermore, using PCNM and AEM spatial methods, FAs compositions of SPOM displayed an upstream-downstream gradient during HW, which was attributed to OM retention and the extent of flooded forest in floodplains. Discrimination of OM quality between the Amazon River and floodplains corroborate higher autotrophic production in the latter and transfer of OM to rivers at LW season. Together, these gradients demonstrate the validity of FAs as predictors of spatial and temporal changes in OM quality. These spatial and temporal trends are explained by 1) downstream change in landscape morphology as predicted by the River Continuum Concept; 2) enhanced primary production during LW when the water level decreased and its residence time increased as predicted by the Flood Pulse Concept. PMID:23029412

Mortillaro, Jean-Michel; Rigal, François; Rybarczyk, Hervé; Bernardes, Marcelo; Abril, Gwenaël; Meziane, Tarik

2012-01-01

107

The impacts of land use changes in the mercury flux in the Madeira River, Western Amazon.  

PubMed

Changes in hydrochemistry and Hg distribution in the Madeira River from Porto Velho to the confluence with the Amazon River were studied in two cruises in 1997 and 2002. Water conductivity was similar in both periods, but the pH was significantly higher in 2002, in particular along the middle reaches of the river. Total suspended matter concentrations also increased from 1997 to 2002 along the same river portion, which is a result of forest conversion to other land uses, in particular pastures and agriculture accelerated during the interval between the cruises. Dissolved Hg concentrations were similar along the river in both cruises, but particulate Hg concentrations increased significantly along the middle portion of the river, although the suspended matter from 2002 was relatively poorer in Hg compared to that from 1997. Since particulate Hg represents more than 90% of the total Hg present in the river water, there was a significant increase in the total Hg transport in the Madeira River. Although gold mining has nearly ceased to exist in the region, the remobilization of Hg from forest soils through conversion to other land uses is responsible for maintaining relatively high Hg content in the Madeira River environment. PMID:22441596

Lacerda, Luiz D; Bastos, Wanderley R; Almeida, Marcelo D

2012-03-01

108

Fish assemblages of the Casiquiare River, a corridor and zoogeographical filter for dispersal between the Orinoco and Amazon basins  

Microsoft Academic Search

Aim The aim of this study was to determine whether the Casiquiare River functions as a free dispersal corridor or as a partial barrier (i.e. filter) for the interchange of fish species of the Orinoco and Negro\\/Amazon basins using species assemblage patterns according to geographical location and environmental features. Location The Casiquiare, Upper Orinoco and Upper Negro rivers in southern

Kirk O. Winemiller; Hernán López-Fernández; Donald C. Taphorn; Leo G. Nico; Aniello Barbarino Duque

2008-01-01

109

15 N natural abundance in plants of the Amazon River floodplain and potential atmospheric N 2 fixation  

Microsoft Academic Search

Summary The15N natural abundance values of various Amazon floodplain (várzea) plants was investigated. Samples of young leaf tissues were collected during three different periods of the river hydrography (low water, mid rising water and high water) and during one period in the Madeira River (high water). A large variation of15N abundance was observed, both among the different plant types and

L. A. Martinelli; R. L. Victoria; P. C. O. Trivelin; A. H. Devol; J. E. Richey

1992-01-01

110

Estimating suspended sediment concentrations in surface waters of the Amazon River wetlands from Landsat images  

SciTech Connect

A method has been developed, based on spectral mixture analysis, to estimate the concentration of suspended sediment in surface waters of the Amazon River wetlands from Landsat MSS and TM images. Endmembers were derived from laboratory reflectance measurements of water-sediment mixtures with a range of sediment concentrations. Using these references spectra, the authors applied a linear mixture analysis to multispectral images after accounting for instrument and atmosphere gains and offsets. Sediment concentrations were estimated for individual pixels from the mixture analysis results based on a nonlinear calibration curve relating laboratory sediment concentrations and reflectance to endmember fractions. The uncertainty in the sediment concentrations derived from this analysis for three Amazon images is predicted to be within [plus minus] 20 mg/L, and the concentrations fall within a range of concentrations of suspended sediment that were measured at several times and places in the field over the past 15 years. The emphasis of their work is to use the patterns of sediment concentrations to compute the approximate volumes of sediment that are transferred between the main channel and floodplain of the Amazon River. However, the methodology can be applied universally if the optical properties of water and sediment at the site are known, and it is, therefore, useful for the study of suspended sediment concentrations in surface waters of wetlands elsewhere.

Mertes, L.A.K.; Smith, M.O.; Adams, J.B. (Univ. of Washington, Seattle (United States))

1993-03-01

111

The Late Miocene paleogeography of the Amazon Basin and the evolution of the Amazon River system  

Microsoft Academic Search

On the basis of paleontological content (vertebrates and palynology) and facies analysis from river banks, road cuts, and three wells, we have assigned the uppermost levels of the Solimões Formation in western Amazonia, Brazil, to the Late Miocene. The vertebrate fossil record from outcropping sediments is assigned to the Huayquerian–Mesopotamian mammalian biozones, spanning 9–6.5Ma. Additionally, we present results that demonstrate

Edgardo M. Latrubesse; Mario Cozzuol; Silane A. F. da Silva-Caminha; Catherine A. Rigsby; Maria Lucia Absy; Carlos Jaramillo

2010-01-01

112

Differentiation in the fertility of Inceptisols as related to land use in the upper Solimões river region, western Amazon  

Microsoft Academic Search

The Upper Solimões river region, western Amazon, is the homeland of indigenous populations and contains small-scale agricultural systems that are important for biodiversity conservation. Although traditional slash-and-burn agriculture is being practiced over many years, deforestation there is relatively small compared to other Amazon regions. Pastures are restricted to the vicinity of cities and do not spread to the small communities

Fatima Maria de Souza Moreira; Rafaela Simão Abrahão Nóbrega; Ederson da Conceição Jesus; Daniel Furtado Ferreira; Daniel Vidal Pérez

2009-01-01

113

Phosphorus in sediments of the Amazon River and estuary: Implications for the global flux of phosphorus to the sea  

Microsoft Academic Search

The distribution of various forms of P in suspended and depositional bank sediments of the Amazon River and bottom sediments of the mixing and freshwater portions of the Amazon estuary and shelf have been determined using a modified sequential extraction method. Forms of P distinguished are: P associated with ferric oxides\\/hydroxides (Fe-P), organic P (org-P), P extracted with acetate buffer

Robert A. Berner; Ji-Long Rao

1994-01-01

114

Seasonal uranium distributions in the coastal waters off the Amazon and Mississippi Rivers  

USGS Publications Warehouse

The chemical reactivity of uranium was investigated across estuarine gradients from two of the world's largest river systems: the Amazon and Mississippi. Concentrations of dissolved (<0.45 ??m) uranium (U) were measured in surface waters of the Amazon shelf during rising (March 1990), flood (June 1990) and low (November 1991) discharge regimes. The dissolved U content was also examined in surface waters collected across estuarine gradients of the Mississippi outflow region during April 1992, August 1993, and November (1993). All water samples were analyzed for U by isotope dilution inductively coupled plasma mass spectrometry (ICP-MS). In Amazon shelf surface waters uranium increased nonconservatively from about 0.01 ??g l-1 at the river's mouth to over 3 ??g l-1 at the distal site, irrespective of river discharge stage. Observed large-scale U removal at salinities generally less than 15 implies a) that riverine dissolved U was extensively adsorbed by freshly-precipitated hydrous metal oxides (e.g., FeOOH, MnO2) as a result of flocculation and aggregation, and b) that energetic resuspension and reworking of shelf sediments and fluid muds on the Amazon shelf released a chemically reactive particle/colloid to the water column which can further scavenge dissolved U across much of the estuarine gradient. In contrast, the estuarine chemistry of U is inconclusive within surface waters of the Mississippi shelf-break region. U behavior is most likely controlled less by traditional sorption and/or desorption reactions involving metal oxides or colloids than by the river's variable discharge regime (e.g., water parcel residence time during estuarine mixing, nature of particulates, sediment storage and resuspension in the confined lower river), and plume dispersal. Mixing of the thin freshwater lens into ambient seawater is largely defined by wind-driven rather than physical processes. As a consequence, in the Mississippi outflow region uranium predominantly displays ConserVative behavior; removal is evident only during anomalous river discharge regimes. 'Products-approach' mixing experiments conducted during the Flood of 1993 suggest the importance of small particles and/or colloids in defining a depleted U versus salinity distribution.

Swarzenski, P.W.; McKee, B.A.

1998-01-01

115

Swath altimetry measurements of the mainstem Amazon River: measurement errors and hydraulic implications  

NASA Astrophysics Data System (ADS)

The Surface Water and Ocean Topography (SWOT) mission, scheduled for launch in 2020, will provide a step-change improvement in the measurement of terrestrial surface water storage and dynamics. In particular, it will provide the first, routine two-dimensional measurements of water surface elevations. In this paper, we aimed to (i) characterize and illustrate in two-dimensions the errors which may be found in SWOT swath measurements of terrestrial surface water, (ii) simulate the spatio-temporal sampling scheme of SWOT for the Amazon, and (iii) assess the impact of each of these on estimates of water surface slope and river discharge which may be obtained from SWOT imagery. We based our analysis on a "virtual mission" for a 300 km reach of the central Amazon (Solimões) River at its confluence with the Purus River, using a hydraulic model to provide water surface elevations according to SWOT spatio-temporal sampling to which errors were added based on a two-dimension height error spectrum derived from the SWOT design requirements. We thereby obtained water surface elevation measurements for the Amazon mainstem as may be observed by SWOT. Using these measurements, we derived estimates of river slope and discharge and compared them to those obtained directly from the hydraulic model. We found that cross-channel and along-reach averaging of SWOT measurements using reach lengths of greater than 4 km for the Solimões and 7.5 km for Purus reduced the effect of systematic height errors, enabling discharge to be reproduced accurately from the water height, assuming known bathymetry and friction. Using cross-section averaging and 20 km reach lengths, results show Nash-Sutcliffe model efficiency values of 0.99 for the Solimões and 0.88 for the Purus, with 2.6 and 19.1% average overall error in discharge, respectively.

Wilson, M. D.; Durand, M.; Jung, H. C.; Alsdorf, D.

2014-08-01

116

Remote sensing-based analysis of the planform changes in the Upper Amazon River over the period 1986-2006  

NASA Astrophysics Data System (ADS)

An analysis of the planform changes of the Colombian reach of the Amazon River was carried out over a period of 19.9 years. Remote sensing image processing techniques were applied to Landsat images acquired in 1986, 1994, 2001 and, 2006. These images were selected based on minimal daily water level variations, while providing the widest temporal span. Plan view river changes and geomorphologic characteristics were examined to identify which channel pattern classification best represents this large tropical river system. Discharge was also analyzed to determine whether changes in the river's plan view are a direct response to variations in discharge. The system had a depositional tendency between 1986 and 2006, with a period where erosion was more intense than deposition between 1994 and 2001. Percent change in the plan view area of the system (1.4% yr-1) and the maximum migration rates (125 m yr-1) suggest that this reach of the Amazon is less active than reaches upstream and the downstream reach between the confluences of the Jutaí and Japurá Rivers. Variations in discharge appear to be responsible for deposition and erosion dynamics observed after this remote sensing analysis in the Colombian reach of the Amazon River. Characteristics including multiple channels with vegetated islands developed from within-channel deposition, meandering planform, lateral activity of channel margins, and the absence of islands with saucer-like morphology suggest a multichannel, meandering pattern for this reach of the Amazon, that corresponds to a laterally active anabranching river.

Rozo, Max G.; Nogueira, Afonso C. R.; Castro, Carlomagno Soto

2014-04-01

117

Effects of DOM photochemistry on bacterial metabolism and CO 2 evasion during falling water in a humic and a whitewater river in the Brazilian Amazon  

Microsoft Academic Search

In the Amazon river system, the source of the large quantity of CO2 evading from river surfaces remains unidentified. Photochemical transformation of dissolved organic matter (DOM) into dissolved\\u000a inorganic carbon (DIC) and low molecular weight organic acids (LMWOAs) is a promising candidate. Few studies in the Amazon\\u000a river system, and river systems in general, have attempted to quantify the contribution

Alex Krusche; Jeff Richey

118

Rivers, refuges and population divergence of fire-eye antbirds (Pyriglena) in the Amazon Basin.  

PubMed

The identification of ecological and evolutionary mechanisms that might account for the elevated biotic diversity in tropical forests is a central theme in evolutionary biology. This issue is especially relevant in the Neotropical region, where biological diversity is the highest in the world, but where few studies have been conducted to test factors causing population differentiation and speciation. We used mtDNA sequence data to examine the genetic structure within white-backed fire-eye (Pyriglena leuconota) populations along the Tocantins River valley in the south-eastern Amazon Basin, and we confront the predictions of the river and the Pleistocene refuge hypotheses with patterns of genetic variation observed in these populations. We also investigated whether these patterns reflect the recently detected shift in the course of the Tocantins River. We sampled a total of 32 individuals east of, and 52 individuals west of, the Tocantins River. Coalescent simulations and phylogeographical and population genetics analytical approaches revealed that mtDNA variation observed for fire-eye populations provides little support for the hypothesis that populations were isolated in glacial forest refuges. Instead, our data strongly support a key prediction of the river hypothesis. Our study shows that the Tocantins River has probably been the historical barrier promoting population divergence in fire-eye antbirds. Our results have important implications for a better understanding of the importance of large Amazonian rivers in vertebrate diversification in the Neotropics. PMID:23442128

Maldonado-Coelho, M; Blake, J G; Silveira, L F; Batalha-Filho, H; Ricklefs, R E

2013-05-01

119

Phosphorus in sediments of the Amazon River and the global flux of P to the sea  

SciTech Connect

A modification of the sequential extraction method of Ruttenberg (1990), for the determination of various forms of phosphorus in soils and sediments, has been applied to suspended and bank sediments of the Amazon River and river-derived marine bottom muds of the Amazon shelf. The following forms of phosphate are distinguished: P associated with hydrous ferric oxides (Fe-P), organic P (org-P), detrital apatite (detr-P), authigenic and/or biogenic Ca-phosphates (auth-P), and total phosphorus. (Use of H[sub 2]O[sub 2] to determine org-P results in loss of phosphorus which renders it inferior to the Aspila or difference-by-ignition method). Results indicate that: (1) org-P drops as riverine sediments become deposited in the marine environment; (2) org-P and Fe-P both drop as sediment is deposited on river banks and subjected to plant growth; (3) detr-P anticorrelates with Fe-P due probably to the association of detr-P with coarser size fractions combined with the correlation of increased Fe-oxide content with finer size fractions; (4) auth-P undergoes negligible change between riverine and marine environments; (5) total P in marine sediments is distinctly lower than that in suspended sediment of the river. These results suggest that dissolved phosphorus is added to the oceans by rivers via the bacterial decomposition of river-transported organic matter and possibly by the desorption and possibly by the desorption of P from Fe-oxides, in addition to that carried in solution. If these results can be extrapolated to a global basis, presently used residence times for phosphate in seawater are too high.

Rao, Ji Long; Berner, R.A. (Yale Univ., New Haven, CT (United States). Dept. of Geology and Geophysics)

1992-01-01

120

Six chitinases from oriental river prawn Macrobrachium nipponense: cDNA characterization, classification and mRNA expression during post-embryonic development and moulting cycle.  

PubMed

Chitinase plays crucial physiological roles in crustaceans, including the digestion of chitin-containing food, moulting and the defense of shrimp against viruses. However, in contrast to insect species, no genome-wide analysis has been carried out in crustacean species and cDNAs encoding chitinase and chitinase-like proteins have been characterized in relatively few species. In this study, we identified six chitinase genes in the oriental river prawn, Macrobrachium nipponense, according to the established expressed sequence tag (EST) information using Rapid Amplification of the cDNA Ends (RACE) technique and homology cloning. We assigned these genes to three different chitinase groupings, which were designated MnCht1A, 1B, 3A, 3B, 3C and 4. The domain organization analysis of the six MnCht proteins revealed that only MnCht3C and MnCht4 possessed full structure, while MnCht1A, 1B, 3A and 3B lacked the serine/threonine (S/T)-rich linker and chitin-binding domains (CBDs). Their expression in different tissues and different developmental stages suggested that all of them have a function in the digestion of chitinous foods, modification of gut peritrophic membrane and degradation of the chitin exoskeleton. Analysis of the stage-specific moulting cycle and different temperature stimulation provided further evidence that MnCht1A, 1B and 3B have pivotal roles in the moulting cycle, while MnCht 4 only assists in the moulting process. This study provides important information for further investigations on the functions of chitinase in M. nipponense and other crustaceans. PMID:24096116

Zhang, Shiyong; Jiang, Sufei; Xiong, Yiwei; Fu, Hongtuo; Sun, Shengming; Qiao, Hui; Zhang, Wenyi; Jiang, Fengwei; Jin, Shubo; Gong, Yongsheng

2014-01-01

121

Studies on the ingestion characteristics of giant freshwater prawn, Chinese prawn and giant tiger prawn  

NASA Astrophysics Data System (ADS)

The ingestion of giant freshwater prawn, Chinese prawn and giant tiger prawn had continuity and the ingestion high peak occurred at night. Light and temperature had significant effects on the daily ingestion rate (DIR) of giant freshwater prawn Macrobrachium rosenbergii. Red light and blue light favorably induced favorable ingestion. In the adaptive range of temperature, the DIR increased with rising temperature and feeding frequency, but decreased with rising body weight.

Zang, Wei-Ling; Wang, Wei-Dong; Dai, Xi-Lin; Jiang, Min; Zhu, Zheng-Guo; Yang, Ming-Hui; Liu, Xian-Zhong; Xu, Gui-Rong; Ding, Fu-Jiang

2000-12-01

122

Integrating GRACE measured water storage change observations into the Hillslope River Routing (HRR) in the Amazon and Congo River Basins  

NASA Astrophysics Data System (ADS)

In this study, GRACE measured water storages are used to constrain the Hillslope River Routing (HRR) model in the Amazon and Congo River Basins. The GRACE measured water storages change observations are de-correlated, filtered and signal leakage corrected with an approximate spatial resolution of longer than 200 km (half-wavelength). The HRR model provides similar scale total water storage changes by integrating vertical water balance, lateral surface and subsurface kinematic wave routing, and channel plus floodplain diffusion wave routing models. The period of study is 2003 through 2008. The model forcing data are TRMM precipitation and MODIS air temperature, albedo, cloud cover and leaf area index. The HRR model parameters accounting for the thickness of the rooting zone layer, timing of the subsurface response to the channel network and speed of the flood wave are calibrated using the GRACE estimates of water storage change. The resulting model predictions are compared to corresponding streamflow data in the Amazon Basin and historical flow data in the Congo Basin. The results of this study quantify the predictive capabilities of a large scale hydrologic model driven primarily with Satellite data and without calibrating to in-situ streamflow data.

Beighley, R. E.; He, Y.; Ray, R. L.; Guo, J.; Shum, C.

2009-12-01

123

Study of the anabranch dynamics for different sinuosity stages in the Upper Amazon River Basin  

NASA Astrophysics Data System (ADS)

The Upper Peruvian Amazon River is characterized by a sequence of anabranching structures, which are composed by several channels behaving as non-developed and quasy-freely meandering channels. The widest channel in these anabranching structures is considered as the main channel or main anabranch while the other channels are secondary anabranches. Based on satellite imagery, it is observed that the main channels show different sinuosities along the Upper Peruvian Amazon River valley. Little is known about the effects of the planform characteristics of the main channel into the morphodynamics of the secondary anabranches. Thus, two study sites were selected to characterize anabranching structures with low and medium-high sinuosity main channels. For the low sinuosity main channel case, an area at the tri-point boundary between Colombia-Brazil and Peru was selected. For the medium-high sinuosity main channel case, an area upstream of Iquitos City (the largest city in the Peruvian Amazon Rainforest) was selected. A field campaign was carried out on 2010 and 2011 for the medium-high and low sinuosity stages respectively. On this field campaign velocity measurement, bathymetry and water surface elevations were obtained. With the field data it was possible to develop and validate a two dimensional shallow water numerical model to study the hydrodynamics on both sites. This allows us to discuss the effects of the current planform configuration of the anabranching structures into the short-term behavior of individual channels. In past studies, temporal analysis of the Amazon River planform have been carried out using satellite imagery with special focus into the floodplain, main channel, number of islands and valley slope. However, the dynamics in these anabranching structures containing multiple channels have not been studied in detailed. The metrics obtained for this study were sinuosity, channel width and annual migration rates. It was confirmed that in a medium to high sinuosity stage, the secondary anabranches behave as non-developed meanders. Also, it was concluded that the planform for secondary anabranches in all main channel sinuosity stages are controlled by the main anabranch migration.

Frias, C. E.; Mendoza, A.; Dauer, K.; Abad, J. D.; Montoro, H.; Paredes, J.; Vizcarra, J.

2013-12-01

124

The pathways and properties of the Amazon River Plume in the tropical North Atlantic Ocean  

NASA Astrophysics Data System (ADS)

The Amazon River Plume spreads across the tropical North Atlantic creating a barrier to vertical mixing. Here using a 1/6° HYCOM model and data from three research cruises in May-June 2010, September-October 2011, and July 2012, we investigate the pathways and properties of the plume. Four plume pathways for export of freshwater from the western tropical North Atlantic are identified. These consist of direct and indirect pathways to the northwest, and eastward pathways toward the subtropical gyre and toward Africa in the North Equatorial Counter Current. Because of the seasonality and cooccurrence of these pathways, plume characteristics are highly variable. Two pathways export water to the Caribbean, however the time scales associated with those direct and indirect pathways (3 versus 6+ months) differ, leading to different salinity characteristics of the plume water. Models results show that the Amazon river and tropical precipitation have similar magnitude impact on the observed seasonal cycle of freshwater within the western tropical Atlantic and at the 8°N, 38°W PIRATA mooring. Freshwater associated with the Amazon also influences surface salinity in winter as far as 20W in the model. The mean plume salinity minimum leads maximum discharge, highlighting the importance of currents and advection rather than discharge in maintaining plume properties. Plume pathways are tied to the underlying current structure, with the North Equatorial Counter Current jet preventing direct freshwater transport into the southern hemisphere. The plume influences underlying currents as well, generating vertical current shear that leads to enhanced eddy stirring and mixing in the model simulations.

Coles, Victoria J.; Brooks, Maureen T.; Hopkins, Julia; Stukel, Michael R.; Yager, Patricia L.; Hood, Raleigh R.

2013-12-01

125

Photochemical and microbial consumption of dissolved organic carbon and dissolved oxygen in the Amazon River system  

NASA Astrophysics Data System (ADS)

Bacterial and photochemical mineralization of dissolved organic matter were investigated in the Amazon River system. Dissolved oxygen, dissolved organic carbon (DOC), and bacterial growth were measured during incubations conducted under natural sunlight and in the dark. Substrate addition experiments indicated that the relatively low rates of bacterial activity in Amazon River water were caused by C limitation. Experiments to determine the photoreactivity of this biologically refractory DOC revealed unusually high rates of photochemical consumption of DOC (~4.0 ?M C h -1) and dissolved oxygen (~3.6 ?M O 2 h -1) in Rio Negro surface waters. In additional experiments we observed that bacterial growth and respiration were not significantly stimulated or inhibited during periods of sunlight exposure. The molar ratio of DOC to O 2 consumed during photochemical processes was close to one (1.11-1.14) in all photooxidation experiments. Sunlight exposure over 27 h showed that at least 15% of Rio Negro DOM was photoreactive. The rate of photochemical consumption of DOC was approximately sevenfold greater than bacterial DOC utilization in Rio Negro surface waters; however, integrated over the entire water column microbial remineralization was the dominant process for oxygen and DOC consumption. Photomineralization of biologically refractory riverine DOM appears to be more important than previously believed and could be a major removal mechanism for terrestrially-derived DOM in the coastal ocean.

Amon, R. M. W.; Benner, R.

1996-05-01

126

From the Andes to the Atlantic: the Evolution of Organic Matter in the Amazon River System  

NASA Astrophysics Data System (ADS)

We compare the compositions of dissolved, fine and coarse particulate organic matter fractions (DOM, FPOM and CPOM respectively) from 31 river sites in Bolivia and Peru with 18 sites along the Amazon mainstem. The diversity of sites - ranging from wet and dry Andean headwater environments, to depositional foreland reaches, to major lowland rivers - allows us to assess the compositional evolution of organic matter along a 5000 km transect draining Peru and a 3000 km transect draining Bolivia. Organic matter size fractions were assessed by concentration, elemental (%OC, %N, C/N), isotopic (13C, 14C, 15N), lignin phenol, hydrolysable amino acid, and mineral surface area analyses. Similar to previous results from the lower Amazon and from Bolivian tributaries, the degree of mineral association was the most important factor in determining the composition of riverine organic matter. However, organic matter within a size class evolves considerably from the Andes to the lowlands. The Bolivian transect showed OM fractions becoming more diagenetically altered downstream, but the Peruvian transect showed a more complicated picture. Together, data suggest that underlying changes to sediment surface area and mineralogy may be the primary control of organic matter composition with fractions, as well as between fractions. These findings highlight the importance of organo-mineral associations and the need to describe mineral phases associated with riverine organic matter.

Aufdenkampe, A. K.; Mayorga, E.; Hedges, J. I.; McClain, M. E.; Llerena, C. A.; Quay, P. D.; Krusche, A. V.; Richey, J. E.

2005-05-01

127

Regulation of laboratory populations of snails (Biomphalaria and Bulinus spp.) by river prawns, Macrobrachium spp. (Decapoda, Palaemonidae): implications for control of schistosomiasis.  

PubMed

Human schistosomiasis is a common parasitic disease endemic in many tropical and subtropical countries. One barrier to achieving long-term control of this disease has been re-infection of treated patients when they swim, bathe, or wade in surface fresh water infested with snails that harbor and release larval parasites. Because some snail species are obligate intermediate hosts of schistosome parasites, removing snails may reduce parasitic larvae in the water, reducing re-infection risk. Here, we evaluate the potential for snail control by predatory freshwater prawns, Macrobrachium rosenbergii and M. vollenhovenii, native to Asia and Africa, respectively. Both prawn species are high value, protein-rich human food commodities, suggesting their cultivation may be beneficial in resource-poor settings where few other disease control options exist. In a series of predation trials in laboratory aquaria, we found both species to be voracious predators of schistosome-susceptible snails, hatchlings, and eggs, even in the presence of alternative food, with sustained average consumption rates of 12% of their body weight per day. Prawns showed a weak preference for Bulinus truncatus over Biomphalaria glabrata snails. Consumption rates were highly predictable based on the ratio of prawn: snail body mass, suggesting satiation-limited predation. Even the smallest prawns tested (0.5-2g) caused snail recruitment failure, despite high snail fecundity. With the World Health Organization turning attention toward schistosomiasis elimination, native prawn cultivation may be a viable snail control strategy that offers a win-win for public health and economic development. PMID:24388955

Sokolow, Susanne H; Lafferty, Kevin D; Kuris, Armand M

2014-04-01

128

Carbon and metal concentrations, size distributions and fluxes in major rivers of the Amazon basin  

NASA Astrophysics Data System (ADS)

The chemical composition of the Amazon River results from the mixing of two water types: black water and white water. On-site fractionation by sequential tangential ultrafiltration (STUF) was used to differentiate transported organic carbon and to determine the distribution and association of major and trace elements with different size fraction of the organic carbon (OC). Several sampling campaigns (1994-1996) allow a monthly quantification of particulate (OCP, MeP), colloidal (OCC, MeC) and dissolved (OCD, MeD) organic carbon and metal ions inputs. In white rivers the OC is mainly concentrated in the low molecular weight fraction (OCD < 5000 D) while in black rivers most of the OC is in the heavier molecular weight fractions (OCP and OCC > 5 kDa). For Mg, Ca and K, 50% of the total amount of each element is found in fraction MeD while 15% and 35% are found in fractions MeC and MeP, respectively. Al and Fe are in the particulate fraction at 99% of the total metal concentration for all river samples. This work emphasizes the coagulation processes and the sink for elements in the mixing zone. These physicochemical transformations of the organic matter vary seasonally. The changes happen during the transition periods: before high-level waters and before low-level waters. By way of flux measurement, a seasonal carbon loss was observed. The estimated annual organic carbon flux of the Amazon at Òbidos is 28 × 106 t. At the same time, an average of 9 × 106 t of organic carbon per year is retained in the reach between Manaus and Òbidos, probably via coagulation processes.

Benedetti, Marc F.; Mounier, Stephane; Filizola, Naziano; Benaim, Jean; Seyler, Patrick

2003-05-01

129

Metagenomics of the Water Column in the Pristine Upper Course of the Amazon River  

PubMed Central

River water is a small percentage of the total freshwater on Earth but represents an essential resource for mankind. Microbes in rivers perform essential ecosystem roles including the mineralization of significant quantities of organic matter originating from terrestrial habitats. The Amazon river in particular is famous for its size and importance in the mobilization of both water and carbon out of its enormous basin. Here we present the first metagenomic study on the microbiota of this river. It presents many features in common with the other freshwater metagenome available (Lake Gatun in Panama) and much less similarity with marine samples. Among the microbial taxa found, the cosmopolitan freshwater acI lineage of the actinobacteria was clearly dominant. Group I Crenarchaea and the freshwater sister group of the marine SAR11 clade, LD12, were found alongside more exclusive and well known freshwater taxa such as Polynucleobacter. A metabolism-centric analysis revealed a disproportionate representation of pathways involved in heterotrophic carbon processing, as compared to those found in marine samples. In particular, these river microbes appear to be specialized in taking up and mineralizing allochthonous carbon derived from plant material. PMID:21915244

McMahon, Katherine D.; Toyama, Danyelle; Rinke, Raquel; Cristina Souza de Oliveira, Tereza; Wagner Garcia, Jose; Pellon de Miranda, Fernando; Henrique-Silva, Flavio

2011-01-01

130

Metagenomics of the water column in the pristine upper course of the Amazon river.  

PubMed

River water is a small percentage of the total freshwater on Earth but represents an essential resource for mankind. Microbes in rivers perform essential ecosystem roles including the mineralization of significant quantities of organic matter originating from terrestrial habitats. The Amazon river in particular is famous for its size and importance in the mobilization of both water and carbon out of its enormous basin. Here we present the first metagenomic study on the microbiota of this river. It presents many features in common with the other freshwater metagenome available (Lake Gatun in Panama) and much less similarity with marine samples. Among the microbial taxa found, the cosmopolitan freshwater acI lineage of the actinobacteria was clearly dominant. Group I Crenarchaea and the freshwater sister group of the marine SAR11 clade, LD12, were found alongside more exclusive and well known freshwater taxa such as Polynucleobacter. A metabolism-centric analysis revealed a disproportionate representation of pathways involved in heterotrophic carbon processing, as compared to those found in marine samples. In particular, these river microbes appear to be specialized in taking up and mineralizing allochthonous carbon derived from plant material. PMID:21915244

Ghai, Rohit; Rodriguez-Valera, Francisco; McMahon, Katherine D; Toyama, Danyelle; Rinke, Raquel; Cristina Souza de Oliveira, Tereza; Wagner Garcia, José; Pellon de Miranda, Fernando; Henrique-Silva, Flavio

2011-01-01

131

Origins and processing of organic matter in the Amazon River as indicated by carbohydrates and amino acids  

Microsoft Academic Search

Aldose, amino acid, and elemental compositions were determined for flux-weighted samples of coarse (> 63 pm) and fine (< 63 pm) particulate organic material and ultrafiltered (> 1,000 Daltons) dissolved organic matter collected at three sites along the Brazilian Amazon River and six of its major tributaries. Concentrations of total organic C (TOC) were relatively uniform (55Ok 100 PM) at

JOHN I. HEDGES; GREGORY L. COWIE; JEFFREY E. RICHEY; PAUL D. QUAY; RONALD BENNER; MIKE STROM; BRUCE R. FORSBERG

1994-01-01

132

Fatness and overweight in Amerindian women and children from riverine Amerindian communities of the Beni River (Bolivian Amazon)2  

E-print Network

1 Fatness and overweight in Amerindian women and children from riverine Amerindian communities of the Beni River (Bolivian Amazon)2 Running head title: Overweight in Amerindian children and women4 the survey; EB and SLM collected dietary, clinical and anthropometric data; SLM and SR performed

Paris-Sud XI, Université de

133

The influence of the Amazonian floodplain ecosystems on the trace element dynamics of the Amazon River mainstem (Brazil).  

PubMed

The purpose of this paper is to forecast the role of riverine wetlands in the transfer of trace elements. One of the largest riverine wetlands in the world is the floodplain (várzea) of the Amazon River and its tributaries (Junk and Piedade, 1997). The central Amazon wetlands are constituted by a complex network of lakes and floodplains, named várzeas, that extend over more than 300,000 km2 (Junk, W.J., The Amazon floodplain--a sink or source for organic carbon? In Transport of Carbon and Minerals in Major World Rivers, edited by E.T. Degens, S. Kempe, R. Herrera, SCOPE/UNEP; 267-283, 1985.) and are among the most productive ecosystems in the world due to the regular enrichment in nutrients by river waters In order to understand if the adjacent floodplain of Amazon River have a significant influence on the trace element concentrations and fluxes of the mainstem, the concentrations of selected elements (i.e., Al, Mn, Fe, Co, Cu, Mo, Rb, Sr, Ba, and U) have been measured in the Amazon River water (Manacapuru Station, Amazonas State, Brazil) and in lake waters and plants (leaves) from a várzea(Ilha de Marchantaria, Amazonas State, Brazil) during different periods of the hydrological cycle. Four plant species (two perennial species: Pseudobombax munguba and Salix humboldtiana, and two annual herbaceous plants: Echinochloa polystachya and Eichhornia crassipes) were selected to represent the ecological functioning of the site. Time series obtained for dissolved Mn and Cu (<0.20 microm) in Amazon River water could not be explained by tributary mixing or instream processes only. Therefore, the contribution of the waters transiting the floodplains should be considered. These results suggest that the chemical composition of the waters draining these floodplains is controlled by reactions occurring at sediment-water and plant-water interfaces. Trace elements concentrations in the plants (leaves) vary strongly with hydrological seasonality. Based on the concentration data and the biological productivity of floodplain ecosystems, a first order approximation of trace element storage (permanent or temporary) in the vegetation of these floodplains was made. It was found that floodplain-mainstem elemental fluxes make a significant contribution to the dissolved flux of the Amazon River. This study is part of the Brazilian_French joint research program Hybam (Hydrology and Geochemistry of the Amazonian Basin). PMID:15740771

Viers, Jérôme; Barroux, Guénaël; Pinelli, Marcello; Seyler, Patrick; Oliva, Priscia; Dupré, Bernard; Boaventura, Geraldo Resende

2005-03-01

134

Tracing soil organic carbon in the lower Amazon River and its tributaries using GDGT distributions and bulk organic matter properties  

NASA Astrophysics Data System (ADS)

In order to trace the transport of soil organic carbon (OC) in the lower Amazon basin, we investigated the distributions of crenarchaeol and branched glycerol dialkyl glycerol tetraethers (GDGTs) by analyzing riverbed sediments and river suspended particulate matter (SPM) collected in the Solimões-Amazon River mainstem and its tributaries. The Branched and Isoprenoid Tetraether (BIT) index, a proxy for river-transported soil OC into the ocean, was determined from the distributions of these GDGTs. The GDGT-derived parameters were compared with other bulk geochemical data (i.e. C:N ratio and stable carbon isotopic composition). The GDGT-derived and bulk geochemical data indicate that riverine SPM and riverbed sediments in the lower Amazon River and its tributaries are a mixture of C3 plant-derived soil OC and aquatic-derived OC. The branched GDGTs in the SPM and riverbed sediments did not predominantly originate from the high Andes soils (>2500 m in altitude) as was suggested previously. However, further constraint on the soil source area of branched GDGTs was hampered due to the deficiency of soil data from the lower montane forest areas in the Andes. Our study also revealed seasonal and interannual variation in GDGT composition as well as soil OC discharge, which was closely related to the hydrological cycle. By way of a simple binary mixing model using the flux-weighted BIT values at Óbidos, the last gauging station in the Amazon River, we estimated that 70-80% of the POC pool in the river was derived of soil OC. However, care should be taken to use the BIT index since it showed a non-conservative behaviour along the river continuum due to the aquatic production of crenarchaeol. Further investigation using a continuous sampling strategy following the full hydrological cycle is required to fully understand how soil-derived GDGT signals are transformed in large tropical river systems through their transport pathway to the ocean.

Kim, Jung-Hyun; Zell, Claudia; Moreira-Turcq, Patricia; Pérez, Marcela A. P.; Abril, Gwenaël; Mortillaro, Jean-Michel; Weijers, Johan W. H.; Meziane, Tarik; Sinninghe Damsté, Jaap S.

2012-08-01

135

Sr and Nd isotopes of suspended sediments from rivers of the Amazon basin  

NASA Astrophysics Data System (ADS)

The Rb-Sr and Sm-Nd isotopic systems are important tools to constrain the provenance of sediment load in river systems. This study presents the isotopic composition of Sr and Nd isotopes and major and minor elements in suspended sediments from the Marañón-Solimões, Amazonas and Beni-Madeira rivers. The data were used to constrain the source region of the sediments and to better understand the main seasonal and spatial transport processes within the basin based on the variations of the chemical and isotopic signals. They also allow establishing a relationship between sediment concentrations and flow rate values. The study presents data collected during a hydrological year between 2009 and 2010. The Marañón-Solimões River presents low Sr isotopic values (0.7090-0.7186), broad EpslonNd(0) range (-15.17 to -8.09) and Nd model (TDM) ages varying from 0.99 to 1.81 Ga. Sources of sediments to the Marañón-Solimões River include recent volcanic rocks in northern Peru and Ecuador, as well as rocks with long crustal residence time and carbonates from the Marañón Basin, Peru. The Beni-Madeira River has more radiogenic Sr isotope values (0.7255-0.7403), more negative EpslonNd(0) values (-20.46 to -10.47), and older Nd isotope model ages (from 1.40 to 2.35 Ga) when compared to the Marañón-Solimões River. These isotope data were related to the erosion of Paleozoic and Cenozoic foreland basins that are filled with Precambrian sediments derived from the Amazonian Craton. These basins are located in Bolivian Subandina Zone. The Amazon River presents intermediate isotopic values when compared to those found in the Marañón-Solimões and Beni-Madeira rivers. Its Sr isotope ratios range between 0.7193 and 0.7290, and its EpslonNd(0) values varies between -11.09 and -9.51. The Nd isotope model ages of the suspended sediments vary between 1.28 and 1.77 Ga. Concentrations of soluble and insoluble elements indicate a more intense weathering activity in sediments of the Beni-Madeira River. This river has a larger difference in the Sr isotopic composition between the diluted and solid phases, which has been assigned to the high level of weathering of its sediment source area. In the Beni-Madeira River sub-basin dominates weathering of silicate rocks, while in the Marañón-Solimões River sub-basin there also weathering of carbonate and evaporitic rocks.

Hatting, Karina; Santos, Roberto V.; Sondag, Francis

2014-05-01

136

Altimetric profiles of Amazon rivers and gage levels gained by GPS-PPP  

NASA Astrophysics Data System (ADS)

A key application of GNSS data for hydrology is the characterization of river altimetric profiles, including the levelling of gauges. In the present work we use the GINS-PC software developed at CNES/GRGS to determine thousands of kilometers long altimetric profile along the major rivers of the Amazon basin. The profiles are processed using data obtained from GPS receivers installed on board boats. We present the capability of the PPP kinematic with integer ambiguities fixing strategy implemented in GINS-PC in processing GPS data collected with moving stations. We point on the specific corrections and cautions that are necessary during the data collection and the data processing. The accuracy of the profiles is evaluated by comparing the results with fix points at gauge stations, or by comparing solutions obtained for several stations installed on the same boat Base applications of the method are to enable the leveling of 1- remote gages without any specific field work but initial installation of GPS stations on boats cruising the river network and 2- leveling of cross sections for the determination of the riverbed slope. Examples are presented with accuracy assessment. These profiles are further used to assess the capability of other space technics to provide altimetric profiles of rivers, namely DEMs such as SRTM, ACE2 or ASTER in the one hand and radar altimetry (JASON-2, ENVISAT) in the other hand.

Moreira, D. M.; Calmant, S.; Perosanz, F.; Rotunno Filho, O. C.; Santos, A.; Seyler, F.; Bonnet, M.; Gennero, M.; Monteiro, A. E.

2013-12-01

137

The effects of CO2 on phytoplankton community structure in the Amazon River Plume  

NASA Astrophysics Data System (ADS)

The Amazon River Plume results from an enormous discharge of freshwater and organic matter into the Atlantic Ocean. It is a unique environment with a natural pCO2 gradient in the surface waters of the plume that range from 130-950 ?atm. The response of coastal marine phytoplankton to increased anthropogenic CO2 emission is still unknown, hence the Amazon River Plume gradient can serve as a natural laboratory to examine the potential influence of atmospheric CO2 increases and ocean acidification on phytoplankton community composition. A two pronged study was undertaken: the first in which shipboard samples from a 2010 cruise to the Amazon River Plume were analyzed to examine the distribution of 3 major phytoplankton groups (diatoms, diatom-diazotroph associations [DDAs], and the diazotroph Trichodesmium spp.) with respect to the natural pCO2 gradient; the second in which the growth response of Thalassiosira weisflogii, a representative diatom species, was examined under experimentally manipulated CO2 conditions. Cruise data analysis showed that diatoms were found with higher cell counts around 150 ?atm; DDAs seemed to dominate waters within the narrow range of 350-400 ?atm CO2; and the diazotroph Trichodesmium spp. grew in a wide range of pCO2 conditions, but with higher cell counts at upwards of 500 ?atm. Phytoplankton group distributions along the CO2 gradient may be due to differences in their carbon-concentrating mechanism (CCMs) efficiencies. The CO2 manipulation apparatus was assembled such that the cells were grown under three different CO2 environments. Differential growth of T. weisflogii was observed at 150, 400, and 800 ppm CO2 treatment. T. weisflogii grew at all three CO2 concentrations, reflecting diatoms' physiological flexibility and efficient CCMs. Absorption spectra analysis of pigments and Fast Repetition Rate Fluorometer analysis indicate potential changes in photosynthetic machinery with different CO2 treatments. Future CO2 manipulation experiments on representative DDA and diazotroph species will be undertaken to compare the growth responses of the 3 major phytoplankton groups to changes in CO2. Additionally, analysis on fatty acid compositions with different CO2 treatments will be done to assess potential changes in nutritive value for higher trophic levels. Underway pCO2 measurements with overlaid cell counts from the 2010 cruise data CO2 manipulation experiment data- growth curve (in vivo chlorophyll a fluorescence) for the 3 CO2 treatments

Chen, T. L.; Goes, J. I.; Gomes, H. R.; McKee, K. T.

2013-12-01

138

A Mineralogical and Organic Geochemical Overview of the Effects of Holocene Changes in Amazon River Flow on Floodplain Lakes  

NASA Astrophysics Data System (ADS)

A synthesis of the impacts of the Amazon River hydrological changes on the sedimentation process of organic matter (OM) in three different floodplain lakes (Santa Ninha, Maracá, and Comprido lakes) is presented in this study. Today the Santa Ninha and Maracá lakes are directly and permanently connected with the main channel of the Amazon River, in contrast to Comprido Lake, which is indirectly and periodically influenced by the Amazon River due to its high distance from the main channel. All the sedimentary lake records showed a reduced river inflow due to dry climatic conditions during the Early and Middle Holocene followed by a humid Late Holocene with an increased fluvial input. In Santa Ninha and Maraca Lakes the reduced river inflow period was characterized by sediments with a low abundance of smectite (on average ~20 wt. %), a clay mineral mainly transported by the fluvial system, high total organic carbon (TOC) contents (on average ~8.2 wt. %) and a predominant acidic soil OM input evidenced by high branched glycerol dialkyl glycerol tetraethers (GDGT) concentrations (on average 180 ?g gTOC-1). During the Late Holocene, a higher smectite abundance (on average ~43 wt. %) and a low TOC content (on average ~1.4 wt. %) pointed to dilution with the riverine lithogenic matter. This was accompanied by a proportional increase in the aquatically-produced crenarchaeol, suggesting an increased lake water level. In Comprido Lake, a sedimentation gap occurred during the Early and Middle Holocene. The humid Late Holocene, after 3,000 cal years BP, was characterized by high TOC values (on average ~9 wt. %) as well as a sharp increase in soil OM input as revealed by the increase in branched GDGT concentrations (on average ~81 ?g gTOC-1), but the smectite content was low (on average ~14 %). This suggests that in Comprido Lake the soil OM input from the local catchment area was predominant during the humid Late Holocene due to its high distance from the Amazon River main stem. Consequently, our study shows that the sedimentation processes of OM in Amazonian floodplain lakes are strongly influenced by variations in the hydrodynamic regime of the Amazon River during the Holocene. However, its impacts on floodplain lakes were different, mainly depending on the distance from the main stem of the Amazon River.

Moreira, Luciane; Patricia, Moreira-Turcq; Kim, Jung-Hyun; Turcq, Bruno; Renato, Cordeiro; Sandrine, Caquineau; Sinninghe Damsté, Jaap

2014-05-01

139

Water Discharge and Suspended Sediment Concentrations in the Amazon River: 1982 1984  

NASA Astrophysics Data System (ADS)

An equal-width-increment procedure was developed to measure water discharge and the suspended sediment load of the Amazon River and its principal tributaries. A variable speed hydraulic winch deploys an instrument array of a sounding weight, Price current meter, and collapsible bag sampler by lowering it from the surface to the bottom and back at a constant velocity. Eighteen verticals are taken at main stem stations (fewer on tributaries), with positioning determined by shipboard observation with a sextant monitoring angles from a three-marker baseline on the shore. Confidence intervals (95%) for discharge and the fluxes of fine (< 0.063 mm) and coarse (> 0.063 mm) suspended sediments were 5%, 10%, and 20%, respectively. Water discharge varied from 31,700 m3/s to 69,700 m3/s upriver at Vargem Grande and from 91,700 m3/s to 203,000 m3/s downriver at Obidos. Concentrations of fine suspended sediments generally decreased downstream from 220-490 mg/L at Vargem Grande to 110-250 mg/L at Sao Jose do Amatari. Large concentrations of fines at high water in the Rio Madeira of 590-770 mg/L increased downstream concentrations of fines in the Amazon. Coarse suspended sediments had some of the same distribution and transport patterns as the fines but with only 20-30% of the concentration.

Richey, Jeffrey E.; Meade, Robert H.; Salati, Eneas; Devol, Allan H.; Nordin, Carl F., Jr.; Santos, Umberto Dos

1986-05-01

140

Transcriptome Analysis of Androgenic Gland for Discovery of Novel Genes from the Oriental River Prawn, Macrobrachium nipponense, Using Illumina Hiseq 2000  

PubMed Central

Background The oriental river prawn, Macrobrachium nipponense, is an important aquaculture species in China, even in whole of Asia. The androgenic gland produces hormones that play crucial roles in sexual differentiation to maleness. This study is the first de novo M. nipponense transcriptome analysis using cDNA prepared from mRNA isolated from the androgenic gland. Illumina/Solexa was used for sequencing. Methodology and Principal Finding The total volume of RNA sample was more than 5 ug. We generated 70,853,361 high quality reads after eliminating adapter sequences and filtering out low-quality reads. A total of 78,408 isosequences were obtained by clustering and assembly of the clean reads, producing 57,619 non-redundant transcripts with an average length of 1244.19 bp. In total 70,702 isosequences were matched to the Nr database, additional analyses were performed by GO (33,203), KEGG (17,868), and COG analyses (13,817), identifying the potential genes and their functions. A total of 47 sex-determination related gene families were identified from the M. nipponense androgenic gland transcriptome based on the functional annotation of non-redundant transcripts and comparisons with the published literature. Furthermore, a total of 40 candidate novel genes were found, that may contribute to sex-determination based on their extremely high expression levels in the androgenic compared to other sex glands,. Further, 437 SSRs and 65,535 high-confidence SNPs were identified in this EST dataset from which 14 EST-SSR markers have been isolated. Conclusion Our study provides new sequence information for M. nipponense, which will be the basis for further genetic studies on decapods crustaceans. More importantly, this study dramatically improves understanding of sex-determination mechanisms, and advances sex-determination research in all crustacean species. The huge number of potential SSR and SNP markers isolated from the transcriptome may shed the lights on research in many fields, including the evolution and molecular ecology of Macrobrachium species. PMID:24204682

Jin, Shubo; Fu, Hongtuo; Zhou, Qiao; Sun, Shengming; Jiang, Sufei; Xiong, Yiwei; Gong, Yongsheng; Qiao, Hui; Zhang, Wenyi

2013-01-01

141

Exchanges of sediment between the flood plain and channel of the Amazon River in Brazil  

USGS Publications Warehouse

Sediment transport through the Brazilian sector of the Amazon River valley, a distance of 2010 km, involves exchanges between the channel and the flood plain that in each direction exceed the annual flux of sediment out of the river at O??bidos (???1200 Mt yr-1). The exchanges occur through bank erosion, bar deposition, settling from diffuse overbank flow, and sedimentation in flood-plain channels. We estimated the magnitude of these exchanges for each of 10 reaches of the valley, and combined them with calculations of sediment transport into and out of the reaches based on sediment sampling and flow records to define a sediment budget for each reach. Residuals in the sediment budget of a reach include errors of estimation and erosion or deposition within the channel. The annual supply of sediment entering the channel from bank erosion was estimated to average 1570 Mt yr-1 (1.3 ?? the O??bidos flux) and the amount transferred from channel transport to the bars (380 Mt yr-1) and the flood plain (460 Mt yr-1 in channelized flow; 1230 Mt yr-1 in diffuse overbank flow) totaled 2070 Mt yr-1 (1.7 ?? the O??bidos flux). Thus, deposition on the bars and flood plain exceeded bank erosion by 500 Mt yr-1 over a 10-16 yr period. Sampling and calculation of sediment loads in the channel indicate a net accumulation in the valley floor of approximately 200 Mt yr-1 over 16 yr, crudely validating the process-based calculations of the sediment budget, which in turn illuminate the physical controls on each exchange process. Another 300-400 Mt yr-1 are deposited in a delta plain downstream of O??bidos. The components of the sediment budget reflect hydrologie characteristics of the valley floor and geomorphic characteristics of the channel and flood plain, which in turn are influenced by tectonic features of the Amazon structural trough.

Dunne, T.; Mertes, L.A.K.; Meade, R.H.; Richey, J.E.; Forsberg, B.R.

1998-01-01

142

Iron isotope composition of the suspended matter along depth and lateral profiles in the Amazon River and its tributaries  

NASA Astrophysics Data System (ADS)

Samples of suspended matter were collected at different locations, seasons, depths and lateral profiles in the Amazon River and three of its main tributaries, the Madeira, the Solimões and the Negro rivers. Their iron isotope compositions were studied in order to understand the iron cycle and investigate the level of isotopic homogeneity at the river cross-section scale. Samples from four depth profiles and three lateral profiles analyzed show suspended matter ?57Fe values (relative to IRMM-14) between -0.501 ± 0.075‰ and 0.196 ± 0.083‰ (2SE). Samples from the Negro River, a blackwater river, yield the negative values. Samples from other stations (whitewater rivers, the Madeira, the Solimões and the Amazon) show positive values, which are indistinguishable from the average composition of the continental crust (?57FeIRMM-14 ˜ 0.1‰). Individual analyses of the depth and lateral profiles show no significant variation in iron isotope signatures, indicating that, in contrast to certain chemical or other isotopic tracers, one individual subsurface sample is representative of river deeper waters. This also suggests that, instead of providing detailed information on the riverine iron cycling, iron isotopes of particulate matter in rivers will rather yield a general picture of the iron sources.

dos Santos Pinheiro, Giana Márcia; Poitrasson, Franck; Sondag, Francis; Vieira, Lucieth Cruz; Pimentel, Márcio Martins

2013-07-01

143

Old sediment in young rivers- a multiple cosmogenic nuclide study in the Amazon basin  

NASA Astrophysics Data System (ADS)

The burial dating technique using in-situ produced cosmogenic isotope pairs (26Al and 10Be) of stationary geomorphic units like terrace deposits has become a valuable tool in deriving sediment deposition chronologies or paleo-denudation rates. In this study, we use 26Al/10Be ratios in detrital sediment from Amazonian rivers to explore the degrees of pre-erosional floodplain burial duration and burial depth as well as degrees of sediment mixing between the active modern rivers and old floodplain reservoirs. 26Al/10Be ratios below a surface production rate ratio of ~6.5 indicate sediment burial, as production of nuclides ceases due to deep shielding in the floodplain and differential decay of 26Al over 10Be causes 26Al/10Be ratios to decrease. Burial depths and durations can be constrained from a modified version of the erosion island plot (26Al/10Be ratio vs. 10Be nuclide concentration diagram) calculated for continuous irradiation during shallow burial. In order to constrain sediment mixing, we analyzed >40 samples for their 26Al/10Be ratios, encompassing the Andean as well as the Guyana and Brazilian Shield headwaters, and the main Amazonian lowland rivers that receive sediment from these differently eroding source areas (Solimões, Amazon, Madeira, Tapajós). The following first-order implications emerge: (i) samples from rapidly denuding Andean headwater streams typically are not affected by burial. (ii) in the Guyana and Brazilian Shield headwaters, average 26Al/10Be ratios are ~5.0, with burial durations between 0.5-1.0 Myr at burial depths around 3 m. (iii) in lowland rivers of central Amazonia that mostly drain the cratonic headwaters (Tapajós, Madeira), coarser grain sizes (> 500 µm) yield 26Al/10Be ratios similar to their cratonic headwaters, whereas finer grain sizes (125-500 µm) reflect the unburied modern stream sediment. (iv) in lowland rivers receiving most sediment from Andean headwaters (Solimões, Amazon), no trend for burial ratio vs. grain size is observable, and typical 26Al/10Be ratios of the main Amazon River are ~5.3, with associated average burial durations of <1 Myr at average depths of ~12 m. Here, also finer grain sizes show deeper burial at ratios <5.0. We observe that when plotted in an erosion island plot, central Amazonian samples evolve along mixing lines between a non-buried Andean end member (represented by modern fluvial sediment produced from hillslope erosion in the source area under continuous cosmic-ray exposure), and a deeply buried end member represented by ~Miocene floodplain sediment. The slope of the mixing lines is hereby a function of the prevailing denudation rate prior burial. For the Miocene floodplain end member, very low burial ratios of ~ 3.0 and long burial durations of ~10 Myr have been measured (Wittmann and von Blanckenburg, 2009). This buried sediment is incorporated into modern, Andean-derived sediment during channel avulsions. Using this dataset, we cannot only constrain the mixing of sediments from different provenances in the classical sense, but can also trace mixing fractions and account for floodplain burial of sediment along the long transfer of sediment from their source areas to the central Amazonian lowlands.(Wittmann, H., and von Blanckenburg, F., 2009, Cosmogenic nuclide budgeting of floodplain sediment transfer: Geomorphology, v. 109, no. 3-4, p. 246-256.)

Wittmann, Hella; von Blanckenburg, Friedhelm; Maurice, Laurence; Guyot, Jean-Loup; Kubik, Peter

2010-05-01

144

Mercury Redox Chemistry in the Negro River Basin, Amazon: The Role of Organic Matter and Solar Light  

Microsoft Academic Search

Pristine water bodies in the Negro River basin, Brazilian Amazon, show relatively high concentrations of mercury. These waters\\u000a are characterized by acidic pH, low concentrations of suspended solids, and high amounts of dissolved organic matter and are\\u000a exposed to intense solar radiation throughout the year. This unique environment creates a very dynamic redox chemistry affecting\\u000a the mobility of mercury due

Wilson F. JardimMarcia; Márcia Cristina Bisinoti; Pedro Sérgio Fadini; Gilmar Silvério da Silva

2010-01-01

145

Physical observations in the plume region of the Amazon River during peak discharge---I. Surface variability  

Microsoft Academic Search

Satellite imagery in the 0.4-1.1 mum band from GOES, NOAA-7 and NIMBUS-7 and shipboard measurements of suspended sediment concentration and chlorophyll are synthesized. Five main surface features are delineated in the plume region of the Amazon during peak discharge: a River Zone (RZ), Interaction Zones A, B and C (IZA, IZB, IZC), and a Nearshore Zone (NZ). The loci, temporal

Thomas B. Curtin; Richard V. Legeckis

1986-01-01

146

A seasonal tropical sink for atmospheric CO 2 in the Atlantic ocean: the role of the Amazon River discharge  

Microsoft Academic Search

In the western equatorial Atlantic ocean, near-surface observations show that during summertime, the low-salinity oceanic water, arising from mixing with the Amazon River discharge at the equator, has low CO2 fugacity levels. Near the coast of South America where the salinities are the lowest (S<20), the fugacity of oceanic CO2 decreases down to 150 ?atm and the shelf area acts

J. F Ternon; C Oudot; A Dessier; D Diverres

2000-01-01

147

Role of gas exchange in the inorganic carbon, oxygen, and ²²²Rn budgets of the Amazon River  

Microsoft Academic Search

Dissolved oxygen, ²²²Rn, pCOâ, alkalinity, respiration rate, and discharge have been measured at eight mainstem and seven tributary stations during February-March 1984 in a 1700-km stretch of the Amazon River between Vargem Grande and Obidos in Brazil. Air-water gas exchange rates were estimated two ways: measurements of the flux of ²²²Rn int floating domes yielded an average boundary layer thickness

ALLAN H. DEVOL; PAUL D. QUAY; JEFFREY E. RICHEY; LUIZ A. MARTINELLI

1987-01-01

148

Excitation–emission fluorescence matrix to study pH influence on organic matter fluorescence in the Amazon basin rivers  

Microsoft Academic Search

A study of the three-dimensional excitation–emission fluorescence matrix (EEFM) of organic matter from the Amazon basin rivers is reported in this paper. The EEFM, applied to the fractions obtained from sequential tangential ultrafiltration (STUF), give spectroscopic informations on the fluorescent properties of particulate (>0.22?m), colloidal and dissolved (<5kD) organic matter. STUF process does not seem to alter the characteristic peaks

N. Patel-Sorrentino; S. Mounier; J. Y. Benaim

2002-01-01

149

Particle size of sediments collected from the bed of the Amazon River and its tributaries in June and July 1976  

USGS Publications Warehouse

Sixty-five samples of bed material were collected from the Amazon River and its major tributaries between Belem, Brazil, and Iquitos, Peru. Samples were taken with a standard BM-54 sampler, a pipe dredge, or a Helley-Smith bedload sampler. Most of the samples have median diameters in the size range of fine to medium sand and contain small percentages of fine gravel. Complete size distributions are tabulated.

Nordin, Carl F., Jr.; Meade, R.H.; Mahoney, H.A.; Delany, B.M.

1977-01-01

150

Particle size of sediments collected from the bed of the Amazon River and its tributaries in May and June 1977  

USGS Publications Warehouse

One-hundred-eight samples of bed material were collected from the Amazon River and its major tributaries between Belem, Brazil , and Iquitos, Peru. Samples were taken with a standard BM-54 sampler or with pipe dredges from May 18 to June 5, 1977. Most of the samples have median diameters in the size range of fine to medium sand and contain small percentages of fine gravel. Complete size distributions are tabulated. (Woodard-USGS)

Nordin, Carl F.; Meade, R.H.; Curtis, W.F.; Bosio, N.J.; Delaney, B.M.

1979-01-01

151

Flooding dynamics on the lower Amazon floodplain: 1. Hydraulic controls on water elevation, inundation extent, and river-floodplain discharge  

NASA Astrophysics Data System (ADS)

Modeling the routing of flood waters across large floodplains is challenging because flows respond to dynamic hydraulic controls from complex geomorphology, vegetation, and multiple water sources. In this study, we analyzed the topographic and hydrologic controls of inundation dynamics of a large floodplain unit (2440 km2) along the lower Amazon River. We combined land topography derived from the Shuttle Radar Topography Mission (SRTM) with underwater topography derived from an extensive echo-sounding survey to generate a seamless digital elevation model (DEM). Floodplain inundation was simulated using LISFLOOD-FP, which combines one-dimensional river routing with two-dimensional overland flow, and a local hydrological model. For the first time, accurate simulation of filling and drainage of an Amazon floodplain was achieved with quantification of changes in water elevation, flooding extent, and river-floodplain exchange. We examined the role of diffuse overbank versus channelized flows on river-floodplain exchange. Diffuse overbank flows represent 93% of total river to floodplain discharge and 54% of floodplain to river discharge. Floodplain discharge during high-water was four times higher than field observation values when the SRTM v.4 DEM with no correction was used for simulation because of a -4.4 m elevation bias originating from residual motion errors of the SRTM interferometric baseline.

Rudorff, Conrado M.; Melack, John M.; Bates, Paul D.

2014-01-01

152

Comparison of bacterial communities in the Solimões and Negro River tributaries of the Amazon River based on small subunit rRNA gene sequences.  

PubMed

The microbiota of the Amazon River basin has been little studied. We compared the structure of bacterial communities of the Solimões and Negro Rivers, the main Amazon River tributaries, based on analysis of 16S rRNA gene sequences. Water was sampled with a 3-L Van Dorn collection bottle; samples were collected at nine different points/depths totaling 27 L of water from each river. Total DNA was extracted from biomass retained by a 0.22-?m filter after sequential filtration of the water through 0.8- and 0.22-?m filters. The 16S rRNA gene was amplified by PCR, cloned and sequenced, and the sequences were analyzed with the PHYLIP and DOTUR programs to obtain the operational taxonomic units (OTUs) and to calculate the diversity and richness indices using the SPADE program. Taxonomic affiliation was determined using the naive Bayesian rRNA Classifier of the RDP II (Ribosomal Database Project). We recovered 158 sequences from the Solimões River grouped into 103 OTUs, and 197 sequences from the Negro River library grouped into 90 OTUs by the DOTUR program. The Solimões River was found to have a greater diversity of bacterial genera, and greater estimated richness of 446 OTUs, compared with 242 OTUs from the Negro River, as calculated by ACE estimator. The Negro River has less bacterial diversity, but more 16S rRNA gene sequences belonging to the bacterial genus Polynucleobacter were detected; 56 sequences from this genus were found (about 30% of the total sequences). We suggest that a more in-depth investigation be made to elucidate the role played by these bacteria in the river environment. These differences in bacterial diversity between Solimões and Negro Rivers could be explained by differences in organic matter content and pH of the rivers. PMID:22183948

Peixoto, J C C; Leomil, L; Souza, J V; Peixoto, F B S; Astolfi-Filho, S

2011-01-01

153

Mercury distribution and exchanges between the Amazon River and connected floodplain lakes.  

PubMed

This work presents the distribution and the partition of mercury (Hg) in the Curuai floodplain lakes along the Amazon River. The maximum Total Filtered Hg (T-FHg) concentrations in the floodplain lakes (28 to 52 pmol L(-1)) coincide with the maximum T-FHg concentrations of the Amazon River and are measured during the flooding period. The lowest T-FHg values (3 to 5 pmol L(-1)) are observed during the flood peak of the mainstream, during the rainy season, when waters are diluted by the local rainfall. In this system, Hg is mainly transported in the particulate phase, confirmed by elevated values of the Hg partition coefficient (4.77

Maia, Poliana Dutra; Maurice, Laurence; Tessier, Emmanuel; Amouroux, David; Cossa, Daniel; Pérez, Marcela; Moreira-Turcq, Patricia; Rhéault, Isabelle

2009-11-15

154

Calculations of river-runoff in the GISS GGM: impact of a new land-surface parameterization and runoff routing model on the hydrology of the Amazon River  

Microsoft Academic Search

This study examines the impact of a new land-surface parameterization and a river routing scheme on the hydrology of the Amazon basin, as depicted by the NASA\\/Goddard Institute of Space Studies (GISS) global climate model (GCM). The more physically realistic land surface scheme introduces a vegetation canopy resistance and a six-layer soil system. The new routing scheme allows runoff to

J. A. Marengo; J R Miller; G L Russell; C. E. Rosenzweig; F. Abramoloulos

1994-01-01

155

Reconnaissance investigations of the discharge and water quality of the Amazon River  

USGS Publications Warehouse

Selected published estimates of the discharge of Amazon River in the vicinity of Obidos and the mouth are presented to show the great variance of available information. The most reasonable estimates prepared by those who measured some parameters of the flow were studied by Maurice Parde, who concluded that the mean annual discharge is 90,000 to 100,000 cms (cubic meters per second) or 3,200,000 to 3,500,000 cfs (cubic feet per second). A few published estimates of discharge at mouth of 110,000 cms (3,900,000 cfs) based on rainfall-runoff relationships developed for other humid regions of the world are available. Three measurements of discharge made at the Obidos narrows in 1963-64 by a joint Brazil-United States expedition at high, low, and medium river stage are referred to the datum used at the Obidos gage during the period of operation, 1928-46, and a relationship between stage and discharge prepared on the basis of the measurements and supplementary data and computations. Recovery of the original Obidos gage datum is verified by referring the 1963-64 concurrent river stages at Manaus, Obidos, and Taperinha to gage relation curves developed for Manaus-Obidos and Obidos-Taperinha for periods of concurrent operation, 1928-46 and 1931-46, respectively. The average discharge, based on the stage-discharge relation and record of river stage for the period 1928-46, is computed to be 5,500,000 cfs (157,000 cms) for the Obidos site. The greatest known flood at Obidos, that of June 1953, is computed to have been a flow of 12,500,000 cfs (350,000 cms) at stage of 7.6 meters (24.9 feet) in the main channel and an indeterminate amount of overflow which, under the best assumed overflow conditions, may have amounted to about 10 percent of the main channel flow. Overflow discharge at stage equivalent to mean annual discharge is judged to be an insignificant percentage of flow down the main channel. Miscellaneous data collected during the flow measurements show that the tidal effect reaches upstream to Obidos at extremely low flows, the distribution of velocities in stream verticals is affected by large-scale turbulence, the standard procedure of basing mean velocity in vertical on the average of point velocities measured at 20 and 80 percent of the total depth is valid, and there is a low Manning roughness coefficient of 0.019 (English units). Samples of suspended sediment taken with a point sampler at various depths in selected verticals show, for the Obidos site, a variation in concentration from 300 to 340 mg/l (milligram per liter) near the streambed to 50 to 70 mg/l in the upper part of the verticals. Median diameter of bed material at Obidos averaged about 0.20 mm (millimeter) in a range of 0.15 to 0.25 ram. Analyses of water samples collected at Obidos in July and November 1963 and August 1964 are presented. The reconnaissance measurements of 1963-64 provide a well-supported value of mean annual water discharge of Amazon River at Obidos and the mouth. Many more measurements of flow and water-quality characteristics are needed to obtain more exact values of discharge, suspended sediment, and salt load.

Oltman, Roy Edwin

1968-01-01

156

Spatial patterns of hydrology, geomorphology, and vegetation on the floodplain of the Amazon river in Brazil from a remote sensing perspective  

Microsoft Academic Search

The spatial heterogeneity of hydrology and vegetation during high-water periods in geomorphically distinct reaches of the Amazon River in Brazil was determined based on semivariance statistics. The spatial statistics were derived from three classified Landsat Thematic Mapper images representing upstream to downstream geomorphic characteristics. In the upstream river reach, scroll-bar topography on the floodplain tends to channelize floodwater into floodplain

Leal A. K. Mertes; Darin L. Daniel; John M. Melack; Bruce Nelson; Luiz A. Martinelli; Bruce R. Forsberg

1995-01-01

157

Remote nautical bottom estimation for the safety of navigation offshore Amazon River mouth.  

PubMed

In muddy areas, the fluid sediment layer can reach a level of "nautical bottom" that can contact with a ships keel causing either damage or unacceptable effects on controllability and maneuverability. Consequently, the minimum depth and allowed draught need to be determined for the safety of navigation. An acoustic remote sensing technique is proposed to facilitate navigation safety applications through the determination of sediment layer properties. It uses range and frequency-dependent features of the vertical waveguide characteristic impedance, as defined by the ratio of pressure and vertical particle velocity (or pressure gradient) at a given frequency. Such ratio can circumvent inversion uncertainty due to insufficient knowledge of complex time-varying ship noise spectrum because of its source spectral level independent. Real ship noise data recorded on a compact array offshore at the mouth of the Amazon River in Brazil, 2012, are processed by a global optimization based inversion scheme. The inverted results demonstrate that technique can estimate the effective water depth through resolving sediment layers properties, especially the density. The promising results demonstrate the feasibility of this technique to facilitate safety navigation applications at port areas. PMID:25235106

Ren, Qunyan; Hermand, Jean-Pierre

2014-04-01

158

ENSO-Orchestrated Carbon Sequestration in Andean-Amazon River Basins by Erosion- Sedimentation Processes  

NASA Astrophysics Data System (ADS)

This interdisciplinary study investigates a three-step process that could represent a major carbon sink in Amazonian foreland basins. Stated as hypotheses, we propose: 1) extensive Andean hillslope failure and lowland channel migration during large La Nina-associated storms mobilizes vast quantities of sediment with low organic carbon (OC) content and vast quantities of fresh organic matter; 2) within the river, mineral surfaces acquire normal OC loadings via sorption of freshly leached dissolved organic matter and are rapidly evacuated from the mountainous source basins to adjacent foreland depocenters; and 3) deposited sediments preserve carbon within organo-mineral complexes and by deep burial in point bars and "crevasse-splay" deposits that have little potential for exchange with the biosphere and atmosphere. Preliminary calculations suggest that this process could sequester ~300 M tons of carbon per event in the Amazonian foreland and regulate the supply of particulate OC to the lower Amazon. When extrapolated globally to other humid tropical regions, these sequestration processes could account for 50-100% of the atmospheric CO2 anomalies typically observed during La Nina periods. We present here preliminary data supporting these hypotheses, based on surveys of source materials and floodplain deposits from the Rio Beni, Bolivia and the Rio Ucayali, Peru. Our data includes: application of a new geochronological method to quantify century-scale floodplain sedimentation rates, elemental and isotope analyses of plant and sediment samples, and organic carbon to mineral surface area ratios of at erosional and depositional sites.

Aufdenkampe, A. K.; Aalto, R.; Maurice-Bourgoin, L.

2006-05-01

159

Mid-Holocene Drought in the Andes and Associated Impacts on Hydrology of the Amazon River  

NASA Astrophysics Data System (ADS)

Pollen, charcoal, and radiocarbon analyses were performed on a 2m-long sediment core obtained from Lake Tapera (coastal Amapa) to provide the paleoenvironmental history of this part of Amazonia. Detrended Correspondence Analysis was applied to the pollen data to improve visualization of sample distribution and similarity. The chronology was based on seven AMS radiocarbon dates, which allowed the establishment of a basal age (8,060 yrs BP) and identification of a sedimentary hiatus lasting 5,500 years (c. 7,100-1600 yrs BP) in Lake Tapera. Because the timing of the hiatus overlapped with the highest Holocene sea-level (5,000 yrs BP), which would have increased the local water table preventing the lake from drying out, it is clear that sea-level was not important in maintaining the lake level. As Lake Tapera apparently depended on riverine flood waters, the sedimentary gap was probably caused by reduced Amazon River discharge, due to an extremely dry period in the Andes (8,000-5,000 years BP), when precipitation levels markedly decreased. One of the impacts of this drought in the Andes was a c. 100m drop in Lake Titicaca water depth. The contrasting presence before and after the hiatus of Andean pollen (river transported) in the record of Lake Tapera supports this interpretation. The pollen analysis also shows that when sedimentation resumed in 1,620 cal. years BP, vegetation around the lake was changed from forest into savanna. This record demonstrates the need to improve our understanding of climate changes and the extent of their associated impacts on the environment.

de Toledo, M. B.; Bush, M. B.; Figueiredo, A. G.

2007-05-01

160

Mega-pattern Analysis of Suspended Sediments Distribution in the Amazon River Using Multi-temporal Satellite Imageries  

NASA Astrophysics Data System (ADS)

Patterns of surface sediment concentration distribution in river are significant for understanding the broad ranges of its fluvial environmental systems. In the case of the Amazon basin, the complexity in the sediment patterns distribution is affected by the anabranching channel pattern of the Amazon River, the input by tributaries (some of them among the largest rivers in Earth) and the existence of a huge and complex floodplain. This study aims to improve understanding of the pattern of sediment distributions over a large scale in the Amazon River, by estimating sediment rate by remote sensing technique. Approximately 2 to 4 field acquired sediment concentration values (mg/L) per month were available from ORE-HYBAM project at three different gauge stations (Tabatinaga; Manacapuru; and Obidos) in the Amazon basin from 2000 to 2010. Eight days composite surface reflectance images (i.e. MOD09Q1/MYD09Q1) were used for calibration with field measured sediment concentration data. Also, hydrological behaviors of the rivers for different years were analyzed individually in order to assess the effects of changes in water stage on sediment concentration rates and sensitivity of reflectance to remote sensing images. Robust correlation between field measured data and MODIS band 1 (620 - 670 nm) which covers the red portion of visible spectrum was observed and models extracted from each station were integrated. Various statistical methods were carried out to retrieve model such as regression analysis, analysis of covariance, bootstrapping, and etc. The preliminary results in this study suggest that the regression relationship between sediment concentration rates and reflectance recorded in remote sensing instruments seems not to be affected by the hydrological cycle. Also, although field measured sediment concentration rates show different ranges for different gauge stations; this is concluded due to the natural regional variations rather than the truly different relationship between sediment concentration and reflectance in different regions. Since sedimentary process is the basis for changes in fluvial geomorphology, an easier way of monitoring the quantity of sediment concentration and its distribution into the multichannel channel system and through the floodplain will practically support the studies on tropical river system and fluvial ecology, in which sediment concentration works as a key variable in system function.

Park, E.; Latrubesse, E. M.

2012-12-01

161

Recruitment of postlarval prawns, Penaeus Orientalis , to a tidal estuary of Jiaozhou Bay, China  

Microsoft Academic Search

PostlarvalPenaeus orientalis kishinouye were simultaneously sampled at three fixed stations near the mouth of the Dagu River estuary in northwestern Jiaozhou\\u000a Bay, China, at hourly intervals over a 49-h period in mid-June, 1984. The purpose of this sampling was to investigate the\\u000a prawn’s recruitment into estuaries from coastal areas.\\u000a \\u000a The abundance of the postlarvae varied considerably between stations and time,

Yongshun Xiao; Ruiyu Liu; Yuheng Cui

1988-01-01

162

Increasing incidence of malaria in the Negro River basin, Brazilian Amazon  

Microsoft Academic Search

Malaria in Brazil is virtually restricted to the Amazon Region, where it has a heterogeneous geographic distribution. We reviewed secondary data in order to describe the regional and temporal distribution of 8018 malaria cases seen between 2003 and 2007 in Santa Isabel do Rio Negro, a municipality in the northwest Brazilian Amazon. A significant rise in malaria incidence, mainly in

A. C. Cabral; N. F. Fé; M. C. Suárez-Mutis; M. N. Bóia; F. A. Carvalho-Costa

2010-01-01

163

Simulation of Water Sources and Precipitation Recycling for the MacKenzie, Mississippi and Amazon River Basins  

NASA Technical Reports Server (NTRS)

An atmospheric general circulation model simulation for 1948-1997 of the water budgets for the MacKenzie, Mississippi and Amazon River basins is presented. In addition to the water budget, we include passive tracers to identify the geographic sources of water for the basins, and the analysis focuses on the mechanisms contributing to precipitation recycling in each basin. While each basin s precipitation recycling has a strong dependency on evaporation during the mean annual cycle, the interannual variability of the recycling shows important relationships with the atmospheric circulation. The MacKenzie River basin has only a weak interannual dependency on evaporation, where the variations in zonal moisture transport from the Pacific Ocean can affect the basin water cycle. On the other hand, the Mississippi River basin has strong interannual dependencies on evaporation. While the precipitation recycling weakens with increased low level jet intensity, the evaporation variations exert stronger influence in providing water vapor for convective precipitation at the convective cloud base. High precipitation recycling is also found to be partly connected to warm SSTs in the tropical Pacific Ocean. The Amazon River basin evaporation exhibits small interannual variations, so that the interannual variations of precipitation recycling are related to atmospheric moisture transport from the tropical south Atlantic Ocean. Increasing SSTs over the 50-year period are causing increased easterly transport across the basin. As moisture transport increases, the Amazon precipitation recycling decreases (without real time varying vegetation changes). In addition, precipitation recycling from a bulk diagnostic method is compared to the passive tracer method used in the analysis. While the mean values are different, the interannual variations are comparable between each method. The methods also exhibit similar relationships to the terms of the basin scale water budgets.

Bosilovich, Michael G.; Chern, Jiun-Dar

2005-01-01

164

Hydrological Controls of Riverine Ecosystems of the Napo River (Amazon Basin): Implications for the Management and Conservation of Biodiversity  

NASA Astrophysics Data System (ADS)

Scientific understanding of neotropical floodplains comes mainly from work on large rivers with predictable seasonal flooding regimes. Less studied rivers and floodplains on the Andean-Amazon interface are distinct in their hydrology, with more erratic flow regimes, and thus ecological roles of floodplain inundation differ in those ecosystems. Multiple and unpredictable flooding events control inundation of floodplains, with important implications for fish and wildlife, plant communities, and human activities. Wetlands along the river corridor exist across a continuum from strong river control to influence only by local waters, with the latter often lying on floodplain paleoterraces. The goal of this study was to understand the hydrological interactions and habitat diversity of the Napo River, a major Amazon tributary that originates in the Andes and drains exceptionally biodiverse Andean foreland plains. This river system is envisioned by developers as an industrial waterway that would require hydrological alterations and affect floodplain ecosystems. Water level regimes of the Napo River and its associated environments were assessed using networks of data loggers that recorded time under water across transects extending inland from the river across more than 100 sites and for up to 5 years. These networks also included rising stage samplers that collected flood water samples for determination of their origin (i.e., Andean rivers vs. local waters) based on hydrochemical composition. In addition, this work entails a classification of aquatic environments of the Napo Basin using an object-oriented remote sensing approach to simultaneously analyze optical and radar satellite imagery and digital elevation models to better assess the extent and diversity of flooded environments. We found out a continuum of hydrological regimes and aquatic habitats along the Napo River floodplains that are linked to the river hydrology in different degrees. Overall, environments that are proximal or that have high hydrological connectivity are riverine controlled versus systems that are distal or that have less or no connectivity that rely on rainwater or local runoff as a source of flooding. Outcomes of this research gave us insight on the extent and diversity of aquatic habitats of the Napo River, the role that the river has on their ecohydrology, the potential effects of different hydrologic scenarios on these ecosystems, and the management measures that need to be considered to support conservation in the region.

Celi, J. E.; Hamilton, S. K.

2013-12-01

165

A comparison of dissolved humic substances from seawater with Amazon River counterparts by sup 13 C-NMR spectrometry  

SciTech Connect

Although dissolved organic matter (DOM) in seawater constitutes one of the major reservoirs of reduced carbon on earth, the biochemical and geographic origins of this material and its hydrophobic humic component remain unclear. Rivers have been suggested as a potentially important source of marine DOM, but this implication has not yet been systematically tested by direct comparisons of the bulk structural characteristics of DOM isolated from representative ocean reservoirs and their major river sources. The authors report here such a comparison and find that dissolved humic substances isolated from surface and deep seawater in the East Equatorial and north Central Pacific are enriched in nitrogen and {sup 13}C and depleted in unsaturated carbon with respect to counterparts from the Amazon River system. Based on these observations, riverine dissolved humic substances appear to comprise a small fraction of seawater humic substances and therefore must be efficiently and rapidly removed from the ocean.

Hedges, J.I. (Univ. of Washington, Seattle (United States)); Hatcher, P.G. (Pennsylvania State Univ., University Park (United States)); Ertel, J.R. (Univ. of Georgia, Athens (United States)); Meyers-Schulte, K.J. (Naval Ocean Research Group, San Diego, CA (United States))

1992-04-01

166

Detection of Envisat RA2/ICE-1 retracked radar altimetry bias over the Amazon basin rivers using GPS  

NASA Astrophysics Data System (ADS)

Altimetry is now routinely used to monitor stage variations over rivers, including in the Amazon basin. It is desirable for hydrologic studies to be able to combine altimetry from different satellite missions with other hydrogeodesy datasets such as leveled gauges and watershed topography. One requirement is to accurately determine altimetry bias, which could be different for river studies from the altimetry calibrated for deep ocean or lake applications. In this study, we estimate the bias in the Envisat ranges derived from the ICE-1 waveform retracking, which are nowadays widely used in hydrologic applications. As a reference, we use an extensive dataset of altitudes of gauge zeros measured by GPS collocated at the gauges. The thirty-nine gauges are spread along the major tributaries of the Amazon basin. The methodology consists in jointly modeling the vertical bias and spatial and temporal slope variations between altimetry series located upstream and downstream of each gauge. The resulting bias of the Envisat ICE-1 retracked altimetry over rivers is 1.044 ± 0.212 m, revealing a significant departure from other Envisat calibrations or from the Jason-2 ICE-1 calibration.

Calmant, Stéphane; da Silva, Joecila Santos; Moreira, Daniel Medeiros; Seyler, Frédérique; Shum, C. K.; Crétaux, Jean François; Gabalda, Germinal

2013-04-01

167

Chain of commercialization of Podocnemis spp. turtles (Testudines: Podocnemididae) in the Purus River, Amazon basin, Brazil: current status and perspectives  

PubMed Central

Background Consumption of turtles by natives and settlers in the Amazon and Orinoco has been widely studied in scientific communities. Accepted cultural customs and the local dietary and monetary needs need to be taken into account in conservation programs, and when implementing federal laws related to consumption and fishing methods. This study was conducted around the Purus River, a region known for the consumption and illegal trade of turtles. The objective of this study was to quantify the illegal turtle trade in Tapauá and to understand its effect on the local economy. Methods This study was conducted in the municipality of Tapauá in the state of Amazonas, Brazil. To estimate turtle consumption, interviews were conducted over 2 consecutive years (2006 and 2007) in urban areas and isolated communities. The experimental design was randomized with respect to type of household. To study the turtle fishery and trade chain, we used snowball sampling methodology. Results During our study period, 100% of respondents reported consuming at least three species of turtles (Podocnemis spp.). Our estimates indicate that about 34 tons of animals are consumed annually in Tapauá along the margins of a major fishing river in the Amazon. At least five components related to the chain of commercialization of turtles on the Purus River are identified: Indigenous Apurinã and (2) residents of bordering villages (communities); (3) of local smugglers buy and sell turtles to the community in exchange for manufactured goods, and (4) regional smugglers buy in Tapauá, Lábrea, and Beruri to sell in Manaus and Manacapuru; Finally, (5) there are professional fishermen. Conclusions We quantify the full impact of turtle consumption and advocate the conservation of the region’s turtle populations. The Brazilian government should initiate a new turtle consumption management program which involves the opinions of consumers. With these measures the conservation of freshwater turtles in the Brazilian Amazon, is possible. PMID:24467796

2014-01-01

168

The distribution of thiamin and pyridoxine in the western tropical North Atlantic Amazon River plume.  

PubMed

B-vitamins are recognized as essential organic growth factors for many organisms, although little is known about their abundance and distribution in marine ecosystems. Despite their metabolic functions regulating important enzymatic reactions, the methodology to directly measure different B-vitamins in aquatic environments has only recently been developed. Here, we present the first direct measurements of two B-vitamins, thiamin (B1), and pyridoxine (B6), in the Amazon River plume-influenced western tropical North Atlantic (WTNA) Ocean, an area known to have high productivity, carbon (C) and dinitrogen (N2) fixation, and C sequestration. The vitamins B1 and B6 ranged in concentrations from undetectable to 230 and 40 pM, respectively. Significantly higher concentrations were measured in the surface plume water at some stations and variation with salinity was observed, suggesting a possible riverine influence on those B-vitamins. The influences of vitamins B1 and B6 on biogeochemical processes such as C and N2 fixation were investigated using a linear regression model that indicated the availability of those organic factors could affect these rates in the WTNA. In fact, significant increases in C fixation and N2 fixation were observed with increasing vitamin B1 concentrations at some low and mesohaline stations (stations 9.1 and 1; p value <0.017 and <0.03, respectively). N2 fixation was also found to have a significant positive correlation with B1 concentrations at station 1 (p value 0.029), as well as vitamin B6 at station 9.1 (p value <0.017). This work suggests that there can be a dynamic interplay between essential biogeochemical rates (C and N2 fixation) and B-vitamins, drawing attention to potential roles of B-vitamins in ecosystem dynamics, community structure, and global biogeochemistry. PMID:23471170

Barada, Laila P; Cutter, Lynda; Montoya, Joseph P; Webb, Eric A; Capone, Douglas G; Sañudo-Wilhelmy, Sergio A

2013-01-01

169

Amazon And Negro River Breeze And Manaus Urban Area Influence In Surface Wind And Water Vapor Daily Cycles  

NASA Astrophysics Data System (ADS)

Close to the urban area of Manaus the Negro and Amazon rivers provide a scenario where river breeze can be particularly well detected due to their width of about 5 - 10 km. Previous studies have looked into the river breeze in the Amazon Basin and detected their influence in surface data, particularly into the effect on wind and moisture. The heat island effect of the Manaus urban area has also been demonstrated using surface temperature data. Here we present an analysis using 35 years of surface weather station hourly data from the two Manaus airports, Eduardo Gomes (AEG) and Ponta de Pelada (APP). The location of these stations allows the analysis of local circulations contrasting the evolution close to the margin and in the Southern tip of the urban area and a more inland location (APP) about 25 km to the Northewest of AEG. We focus on dew point temperature, water vapor pressure, wind speed and direction providing direction statistics for the two stations and contrasting the evolution in the dry and wet seasons.In the AEG weather station data we found relatively high values of accumulated frequency of the southwest and northwest wind in the period from 9 am to 6 pm (local time - LT) due to the action of the river breeze associated to the Negro River. In June and July (dry season), when the wind was blowing from the Southeast (river-breeze wind), high values of vapor pressure (VP) were observed during the daytime due to the transport of moist air from river to land. In the wind frequency data of the APP weather station we verified maximums in nighttime and minimums in daytime period when the wind direction was from the Northwest. These characteristics of maximums and minimums of wind frequency were observed in Northeastern winds only in the dry season. High frequency of South winds in daytime and minimums in nighttime period also indicates the action of river breeze. When the wind direction was southern, we found high values of VP (e.g, higher than 30.5 hPa in several months). This occurs because southern wind, often times associated to river breeze, transports moist air from Negro River to land. The opposite, low levels of VP, was observed when the wind direction was northern, which in some cases are land-breeze wind. The northern wind transports dry air from Manaus city which decreases the values of VP over the APP region.

Dos Santos, M.; da Silva Dias, M. F.; Freitas, E. D.; Meteorologia Aplicada A Sistemas de Tempo Regionais-Master

2013-05-01

170

Tucurui dam.and the populations of the prawn Macrobrachium amazonicum in the Lower Tocantins (Pa-Brazil): a four year study  

Microsoft Academic Search

A four year survey of the prawn Manobrachimi atnazonicum (HELLER, 1862) on the Tocantins river studies che shon term impact of the Tucurui hydroelectric project on downstream fishery and reservoir populations. The furthest downstream site below the dam has been the most affected. Before the closure of the dam, the annual prawn catch in Camera and the flood intensity were

OLGA ODINETZ COLLART

171

Role of gas exchange in the inorganic carbon, oxygen, and /sup 222/Rn budgets of the Amazon River  

SciTech Connect

Dissolved oxygen, /sup 222/Rn, pCO/sub 2/, alkalinity, respiration rate, and discharge have been measured at eight mainstem and seven tributary stations during February-March 1984 in a 1700-km stretch of the Amazon River between Vargem Grande and Obidos in Brazil. Air-water gas exchange rates were estimated two ways: measurements of the flux of /sup 222/Rn int floating domes yielded an average boundary layer thickness of 78..mu..m, and oxygen mass balance calculations resulted in an average of 38..mu..m. Given a boundary layer thickness on the order of 50..mu..m, CO/sub 2/ loss to the atmosphere in the entire reach would have been 37.4 kmol s/sup -1/, which is about equal to the total tributary dissolved inorganic carbon (DIC) input and is about half of the total fluvial DIC input to the section. Thus, CO/sub 2/ evasion is a major component of Amazon River DIC balance. Because gas exchange within the section was rapid relative to water travel time through the section, a quasi-steady state was maintained between respiratory input and evasion of CO/sub 2/. Dissolved /sup 222/Rn activities in the mainstem varied from 3.5 to 8.3 dpm liter/sup -1/ and were always highly supersaturated with respect to the atmosphere. Dissolved radon was also not supported by decay of /sup 222/Ra in the mainstem. A /sup 222/Rn mass balance indicated that direct groundwater input into this stretch of the Amazon mainstem probably accounted for no more than 1% of water discharge.

Devol, A.H.; Quay, P.D.; Richey, J.E.; Martinelli, L.A.

1987-01-01

172

Influence of the Amazon River discharge on the biogeography of phytoplankton communities in the western tropical north Atlantic  

NASA Astrophysics Data System (ADS)

An Advanced Laser Fluorometer (ALF) capable of discriminating several phytoplankton pigment types was utilized in conjunction with microscopic data to map the distribution of phytoplankton communities in the Amazon River plume in May-June-2010, when discharge from the river was at its peak. Cluster analysis and Non-metric Multi-Dimensional Scaling (NMDS) helped distinguish three distinct biological communities that separated largely on the basis of salinity gradients across the plume. These three communities included an “estuarine type” comprised of a high biomass mixed population of diatoms, cryptophytes and green-water Synechococcus spp. located upstream of the plume, a “mesohaline type” made up largely of communities of Diatom-Diazotroph Associations (DDAs) and located in the northwestern region of the plume and an “oceanic type” in the oligotrophic waters outside of the plume made up of Trichodesmium and Synechococcus spp. Although salinity appeared to have a substantial influence on the distribution of different phytoplankton groups, ALF and microscopic measurements examined in the context of the hydro-chemical environment of the river plume, helped establish that the phytoplankton community structure and distribution were strongly controlled by inorganic nitrate plus nitrite (NO3 + NO2) availability whose concentrations were low throughout the plume. Towards the southern, low-salinity region of the plume, NO3 + NO2 supplied by the onshore flow of subsurface (?80 m depth) water, ensured the continuous sustenance of the mixed phytoplankton bloom. The large drawdown of SiO3 and PO4 associated with this “estuarine type” mixed bloom at a magnitude comparable to that observed for DDAs in the mesohaline waters, leads us to contend that, diatoms, cryptophytes and Synechococcus spp., fueled by the offshore influx of nutrients also play an important role in the cycling of nutrients in the Amazon River plume.

Goes, Joaquim I.; Gomes, Helga do Rosario; Chekalyuk, Alexander M.; Carpenter, Edward J.; Montoya, Joseph P.; Coles, Victoria J.; Yager, Patricia L.; Berelson, William M.; Capone, Douglas G.; Foster, Rachel A.; Steinberg, Deborah K.; Subramaniam, Ajit; Hafez, Mark A.

2014-01-01

173

Impact of seasonal hydrological variation on the distributions of tetraether lipids along the Amazon River in the central Amazon basin: implications for the MBT/CBT paleothermometer and the BIT index.  

PubMed

Suspended particulate matter (SPM) was collected along the Amazon River in the central Amazon basin and in three tributaries during the rising water (RW), high water (HW), falling water (FW) and low water (LW) season. Changes in the concentration and the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), i.e., the methylation index of branched tetraethers (MBT) and the cyclization of brGDGTs (CBT), were seen in the Amazon main stem. The highest concentration of core lipid (CL) brGDGTs normalized to particulate organic carbon (POC) was found during the HW season. During the HW season the MBT and CBT in the Amazon main stem was also most similar to that of lowland Amazon (terra firme) soils, indicating that the highest input of soil-derived brGDGTs occurred due to increased water runoff. During the other seasons the MBT and CBT indicated an increased influence of in situ production of brGDGTs even though soils remained the main source of brGDGTs. Our results reveal that the influence of seasonal variation is relatively small, but can be clearly detected. Crenarchaeol was mostly produced in the river. Its concentration was lower during the HW season compared to that of the other seasons. Hence, our study shows the complexity of processes that influence the GDGT distribution during the transport from land to ocean. It emphasizes the importance of a detailed study of a river basin to interpret the MBT/CBT and BIT records for paleo reconstructions in adjacent marine setting. PMID:23966986

Zell, Claudia; Kim, Jung-Hyun; Abril, Gwenaël; Sobrinho, Rodrigo Lima; Dorhout, Denise; Moreira-Turcq, Patricia; Sinninghe Damsté, Jaap S

2013-01-01

174

Impact of seasonal hydrological variation on the distributions of tetraether lipids along the Amazon River in the central Amazon basin: implications for the MBT/CBT paleothermometer and the BIT index  

PubMed Central

Suspended particulate matter (SPM) was collected along the Amazon River in the central Amazon basin and in three tributaries during the rising water (RW), high water (HW), falling water (FW) and low water (LW) season. Changes in the concentration and the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), i.e., the methylation index of branched tetraethers (MBT) and the cyclization of brGDGTs (CBT), were seen in the Amazon main stem. The highest concentration of core lipid (CL) brGDGTs normalized to particulate organic carbon (POC) was found during the HW season. During the HW season the MBT and CBT in the Amazon main stem was also most similar to that of lowland Amazon (terra firme) soils, indicating that the highest input of soil-derived brGDGTs occurred due to increased water runoff. During the other seasons the MBT and CBT indicated an increased influence of in situ production of brGDGTs even though soils remained the main source of brGDGTs. Our results reveal that the influence of seasonal variation is relatively small, but can be clearly detected. Crenarchaeol was mostly produced in the river. Its concentration was lower during the HW season compared to that of the other seasons. Hence, our study shows the complexity of processes that influence the GDGT distribution during the transport from land to ocean. It emphasizes the importance of a detailed study of a river basin to interpret the MBT/CBT and BIT records for paleo reconstructions in adjacent marine setting. PMID:23966986

Zell, Claudia; Kim, Jung-Hyun; Abril, Gwenael; Sobrinho, Rodrigo Lima; Dorhout, Denise; Moreira-Turcq, Patricia; Sinninghe Damste, Jaap S.

2013-01-01

175

The influence of historical and potential future deforestation on the stream flow of the Amazon River - Land surface processes and atmospheric feedbacks  

NASA Astrophysics Data System (ADS)

SummaryIn this study, results from two sets of numerical simulations are evaluated and presented; one with the land surface model IBIS forced with prescribed climate and another with the fully coupled atmospheric general circulation and land surface model CCM3-IBIS. The results illustrate the influence of historical and potential future deforestation on local evapotranspiration and discharge of the Amazon River system with and without atmospheric feedbacks and clarify a few important points about the impact of deforestation on the Amazon River. In the absence of a continental scale precipitation change, large-scale deforestation can have a significant impact on large river systems and appears to have already done so in the Tocantins and Araguaia Rivers, where discharge has increased 25% with little change in precipitation. However, with extensive deforestation (e.g. >30% of the Amazon basin) atmospheric feedbacks, brought about by differences in the physical structure of the crops and pasture replacing natural vegetation, cause water balance changes of the same order of magnitude as the changes due to local land surface processes, but of opposite sign. Additionally, changes in the water balance caused by atmospheric feedbacks are not limited to those basins where deforestation has occurred but are spread unevenly throughout the entire Amazon by atmospheric circulation. As a result, changes to discharge and aquatic environments with future deforestation of the Amazon will likely be significant and a complex function of how much vegetation has been removed from that particular watershed and how much has been removed from the entire Amazon Basin.

Coe, Michael T.; Costa, Marcos H.; Soares-Filho, Britaldo S.

2009-05-01

176

A clip-domain serine proteinase homolog (SPH) in oriental river prawn, Macrobrachium nipponense provides insights into its role in innate immune response.  

PubMed

In this study, a clip-domain serine proteinase homolog designated as MnSPH was cloned and characterized from a freshwater prawn Macrobrachium nipponense. The full-length cDNA of MnSPH was 1897 bp and contained a 1701 bp open reading frame (ORF) encoding a protein of 566 amino acids, a 103 bp 5'-untranslated region, and a 93 bp 3'-untranslated region. Sequence comparison showed that the deduced amino acids of MnSPH shared 30-59% identity with sequences reported in other animals. Tissue distribution analysis indicated that the MnSPH transcripts were present in all detected tissues with highest in the hepatopancreas and ovary. The MnSPH mRNA levels in the developing ovary were stable at the initial three developmental stages, then increased gradually from stage IV (later vitellogenesis), and reached a maximum at stage VI (paracmasis). Furthermore, the expression of MnSPH mRNA in hemocytes was significantly up-regulated at 1.5 h, 6 h, 12 h and 48 h post Aeromonas hydrophila injection. The increased phenoloxidase activity also demonstrated a clear time-dependent pattern after A. hydrophila challenge. These results suggest that MnSPH participates in resisting to pathogenic microorganisms and plays a pivotal role in host defense against microbe invasion in M. nipponense. PMID:24878742

Ding, Zhili; Kong, Youqin; Chen, Liqiao; Qin, Jianguang; Sun, Shengming; Li, Ming; Du, Zhenyu; Ye, Jinyun

2014-08-01

177

Discharge and suspended sediment flux estimated along the mainstream of the Amazon and the Madeira Rivers (from in situ and MODIS Satellite Data)  

NASA Astrophysics Data System (ADS)

Water and suspended sediment fluxes are considered during the period 2000-2008 in a region including the full Amazon River from the confluence of the Negro River to Santarém, the end part of the Solimões River, and the lower part of the Madeira River. Three types of data are used: water discharge estimated from field measurements, and suspended sediment obtained from field measurements and derived from MODIS satellite data. A generalized least square method including a propagating term is developed in order to propagate the signal upward and downward the river. The approach is introduced and tested. Several experiments are considered in order, first, to estimate the ability to propagate the signal from stations located before the confluences of Negro and Madeira Rivers to stations located on the Amazon River; second to investigate the possibility to propagate the signal along the Amazon River which dynamics is coupled with floodplains dynamics; and third to produce optimal solutions of water and sediment fluxes. For each experiment, the influence of field and satellite data is compared. The approach is efficient in the upper part of the region of study where the Solimões, the Negro and the Madeira Rivers meet and fails in the lower part of the region where interactions between Amazon River and floodplains play an important role on the fluxes' dynamics. The optimal experiment includes in situ and satellite data from all the stations available and is used to analyse the recent evolution of suspended sediment flux along the Amazon River and its interaction with the large coupled floodplains. A high accumulation rate is observed during the 2000-2002 period, followed by decreasing rates until 2005 and by increasing values in 2006 and 2007. Our results suggest that floodplains extending along a river reach of 390 km-long between Itacoatiara and Óbidos trap about 15% of the suspended sediment flux passing at Óbidos. The simulated deposition rate is of about 0.3 Mt km-1 yr-1 corresponding to an accretion rate of about 27 mm yr-1.

Mangiarotti, S.; Martinez, J.-M.; Bonnet, M.-P.; Buarque, D. C.; Filizola, N.; Mazzega, P.

2013-04-01

178

The relationship between the water level of the Amazon River and the fate of the zooplankton population in lago Jacaretinga. A Várzea Lake in the Central Amazon  

Microsoft Academic Search

In a várzea lake of the Central Amazon the planktonic crustaceans disappear almost completely after the inflow of suspension?rich Amazon water. An initial small increase in numbers of individuals is accompanied by increased egg production in Diaphanosoma sarsi and Notodiaptomus amazonicus, suggesting an improved food supply for the Zooplankton. Possible reasons for the complete disappearance of the crustaceans are discussed,

E. R. de Andrade

1978-01-01

179

Mapping the Amazon: Manaus  

NSDL National Science Digital Library

The largest city along the Amazon River is Manaus. NASAs mosaic says that thirty percent of the surrounding area is wetlands. Scientists listed worked as a team on Mosaicking Software and Mosaic Production.

Snodgrass, Stuart; Chapman, Bruce; Curkendall, David; Freeman, Tony; Miller, Craig; Siegel, Herb

2002-03-14

180

MERCURY IN FISH OF THE TAPAJS RIVER IN THE BRAZILIAN AMAZON  

E-print Network

Research Institute, La Paz, Bolivia; 3 Amazon Research Institute, Avenida Rui Barbosa, Santarém, Pará corresponding to the rainy season (April-May/2000) and rising water season (January/2001) are presented% in the rising water period. Linear or curvilinear positive correlations between Hg concentrations of muscular

Long, Bernard

181

Sediment budget of the Napo River, Amazon basin, Ecuador and Peru A., Laraque1  

E-print Network

of Ecuador, at the west of the Amazon basin. A comparative study was made, during 4 hydrological cycles (2001-2005) for 3 hydrological stations located upstream; and during 1 hydrological cycle (2004-2005) for the fourth reported in Bolivia at the southwest of the basin. Here, important sediment deposits are observed (Guyot et

Paris-Sud XI, Université de

182

General characteristics of benthic faunas on the Amazon inner continental shelf with comparison to the shelf off the Changjiang River, East China Sea  

NASA Astrophysics Data System (ADS)

Major patterns of bacteria, meiofauna, and macrobenthos distributions were examined from muddy sediments on the inner continental shelf near the Amazon River. The spatial distributions and functional groupings of the fauna were compared with faunal distributions on the East China Sea shelf off the Changjiang (Yangtze) River and used to assess the impact of long-term, large-scale physical processes on benthic community structure in shelf environments. Both areas are influenced by large discharges of fresh water and suspended solids, and have inner-shelf mud deposits. On the Amazon shelf, macrofauna were generally small in size or absent from highly mobile, muddy sediments on the inner shelf. Significant numbers occurred only in relatively stable sediments offshore or to the south or northeast of the mud belt. Macrobenthos reached greatest densities (3915 m -2) in a general area of firm muddy sediments (Stas 79 and 88) interbedded with sand and burrowed by the ghost shrimp Callianassa sp. At these stations, diversity was greatest, particularly in the dominant polychaete taxon. Macrofauna in the East China Sea, particularly epifaunal species, were reduced in abundance and biomass in inner-shelf areas of most active accumulation near the Changjiang River. However, macrofauna were 50-100 times more abundant (ranging to 10,000 m -2) than at sedimentologically comparable locations on the Amazon shelf. For areas of reduced deposition on the East China Sea shelf, diversity was also greater, with 50 species per sample as opposed to a maximum number of 19 per sample of comparable size on the Amazon shelf. Bacterial and meiofaunal abundances were low nearshore on the Amazon shelf compared with farther offshore or, in the case of meiofauna, other shelf environments. Average bacterial abundances for the top 10 cm of sediments ranged from 1.3 to 21 × 10 9 g -1 on the Amazon shelf and from 7.1 to 22 × 10 9 g -1 on the East China Sea shelf. Meiofauna on the Amazon shelf varied from none in the nearshore mobile mud belt to 2045 (10 cm -2) offshore on firm silty clay sediments. These densities compare with 66 (10 cm -2) near the Changjiang River mouth and 4870 (10 cm -2) farther offshore. Nematodes dominate the meiofauna on both shelves. The high degree of physical disturbance and unstable nature of the seabed coupled with reduced detrital food availability in bottom sediments appear to be the major factors limiting faunal abundances, controlling the taxonomic diversity of the meio- and macrofaunal species, and determining the functional groups of macrobenthos on the Amazon inner shelf, and, to a lesser extent on the East China Sea inner shelf.

Aller, Josephine Y.; Aller, Robert C.

183

The dispersal of the Amazon and Orinoco River water in the tropical Atlantic and Caribbean Sea: Observation from space and S-PALACE floats  

Microsoft Academic Search

Abstract The temporal,evolutionof,spatial pattern s of the colored water mass,associated with the discharges of the Amazon and Orinoco Rivers between,1997 and,2002 was,examined,using concurrent,in situ and,satellite observations,in the regionboun ded,by 0 1N–241 Na n d7,01W–401W. Patches of low-salinity (? 32–34) surface waters,were,frequently observed,with Salinity Profiling Autonomous,LAgrangian Current Explorer (S-PALACE) floats as far as 2000 km,away from the mouths,of the Amazon,and Orinoco

Chuanmin Hu; Ellyn T. Montgomery; Raymond W. Schmitt; Frank E. Muller-Karger

2004-01-01

184

Bioaccumulation of polychlorinated biphenyls and metals from contaminated sediment by freshwater prawns, Macrobrachium rosenbergii and clams, Corbicula fluminea  

Microsoft Academic Search

Freshwater prawns,Macrobrachium rosenbergii, and clams,Corbicula fluminea, were exposed for 48 or 50 days to three concentrations of a river sediment that contained environmental contaminants such as polychlorinated biphenyls (PCBs) and metals. Sediment was obtained twice during 1980 from the same location. Prawns were exposed to the first batch, sediment 5–80, which contained higher concentrations of some metals and PCBs compared

Henry E. Tatem

1986-01-01

185

Molecular differentiation of species of the genus Zungaro (Siluriformes, Pimelodidae) from the Amazon and Paraná-Paraguay River basins in Brazil.  

PubMed

Fish species of the Zungaro genus (Siluriformes, Pimelodidae) are amongst the largest migratory fish in Latin America and have considerable economic importance for commercial fishing in Brazil. However, natural populations of this large catfish are experiencing a severe decline. There are significant taxonomical inconsistencies for this fish. Two geographically separated species of the fish were initially described, one endemic in the Amazon and another in the Paraná-Paraguay River basins. A taxonomic review had recently proposed that there is only one Zungaro species in Brazil, based on morphological data. We made a molecular study of Zungaro populations in an attempt to solve taxonomical inconsistencies and to analyze genetic diversity in natural populations of this genus. We analyzed two regions of the mitochondrial DNA (the control region and the ATPase 6 gene region) of individuals sampled from the Paraná-Paraguay River and Amazon River basins. Analyses based on p-distances and maximum likelihood phylogenetic models showed a genetic difference between populations corresponding to different species. Genetic differentiation between Zungaro populations was at the same level as that observed between other Siluriformes species, using the same DNA sequences. We conclude that Zungaro species of the Paraná-Paraguay River basin do not belong to the same species found in the Amazon basin. This finding has a significant implication for conservation of this fish, given that populations are disappearing at a high rate in the Paraná-Paraguay River basin, mainly due to impoundments. PMID:22095604

Boni, T A; Padial, A A; Prioli, S M A P; Lucio, L C; Maniglia, T C; Bignotto, T S; Panarari-Antunes, R S; Prioli, R A; Prioli, A J

2011-01-01

186

Henneguya amazonica n.sp. (Myxozoa, Myxobolidae), parasitizing the gills of Crenicichla lepidota Heckel, 1840 (Teleostei, Cichlidae) from Amazon river.  

PubMed

The authors present light and electron microscopical data on a myxosporidian found in the gills of Crenicichla lepidota Heckel, 1840 (Teleostei, Cichlidae) from the Amazon river. Based on the spore morphology, it is concluded that this species belongs to the family Myxobolidae, genus Henneguya, and that it constitutes a new species: Henneguya amazonica n.sp. The fine structure of sporogenesis shows that the development follows, in general, the pattern of this and other genera. Nevertheless, some ultrastructural features are reported for the first time in the genus Henneguya: intercellular bridges between daughter generative cells as well as tubuli arranged in aggregates and dispersed within the capsular matrix. The structure of the trophozoite wall suggests that the species is not highly pathogenic, but, to ascertain the true pathogenicity of the species, further studies are needed. PMID:23195230

Rocha, E; Matos, E; Azevedo, C

1992-08-21

187

Amazon deforestation alters small stream structure, nitrogen biogeochemistry and connectivity to larger rivers  

Microsoft Academic Search

Human activities that modify land cover can alter the structure and biogeochemistry of small streams but these effects are\\u000a poorly known over large regions of the humid tropics where rates of forest clearing are high. We examined how conversion of\\u000a Amazon lowland tropical forest to cattle pasture influenced the physical and chemical structure, organic matter stocks and\\u000a N cycling of

Linda A. Deegan; Christopher Neill; Christie L. Haupert; M. Victoria R. Ballester; Alex V. Krusche; Reynaldo L. Victoria; Suzanne M. Thomas; Emily de Moor

188

Characteristics and spatio-temporal variability of the Amazon River Basin Water Budget  

Microsoft Academic Search

The spatio-temporal variations of the water budget components in the Amazon region are investigated by using a combination of hydrometeorological observations and moisture fluxes derived from the NCEP\\/NCAR reanalyses, for the period 1970–1999. The key new finding of this study identifies the major differences in the water balance characteristics and variability between the northern and southern parts of the basin.

Jose A. Marengo

2005-01-01

189

Human exposure to mercury due to goldmining in the Tapajos River basin, Amazon, Brazil: Speciation of mercury in human hair, blood and urine  

Microsoft Academic Search

To obtain the basic information on human exposure to mercury (Hg) due to gold mining activities in Amazon, total mercury (T-Hg) and methylmercury (MeI Ig) were determined for human hair, blood and\\/or urine samples collected from populations living in gold mining area and fishing villages upstream of the Tapajos River basin. Abnormally high levels of T-Hg were observed in hair

H. Akagi; O. Malm; F. J. P. Branches; Y. Kinjo; Y. Kashima; J. R. D. Guimaraes; R. B. Oliveira; K. Haraguchi; W. C. Pfeiffer; Y. Takizawa; H. Kato

1995-01-01

190

Composition of wax esters, triglycerides and diacyl glyceryl ethers in the jaw and blubber fats of the Amazon River dolphin ( Inia geoffrensis )  

Microsoft Academic Search

The lower jaw fat of the Amazon River dolphinInia geoffrensis contains 52.8% wax ester, 44.7% triglyceride and 2.5% diacyl glyceryl ether, while its dorsal blubber fat is >98% triglyceride.\\u000a Examination of the intact lipids, the derived fatty acids and the derived fatty alcohols by gas chromatography reveals that\\u000a the blubber triglycerides show characteristics of freshwater fish fats, but the jaw

R. G. Ackman; C. A. Eaton; Carter Litchfield

1971-01-01

191

The estuarine chemistry and isotope systematics of 234,238U in the Amazon and Fly Rivers  

USGS Publications Warehouse

Natural concentrations of 238U and ??234U values were determined in estuarine surface waters and pore waters of the Amazon and Fly (Papua New Guinea) Rivers to investigate U transport phenomena across river-dominated land-sea margins. Discharge from large, tropical rivers is a major source of dissolved and solid materials transported to the oceans, and are important in defining not only oceanic mass budgets, but also terrestrial weathering rates. On the Amazon shelf, salinity-property plots of dissolved organic carbon, pH and total suspended matter revealed two vastly contrasting water masses that were energetically mixed. In this mixing zone, the distribution of uranium was highly non-conservative and exhibited extensive removal from the water column. Uranium removal was most pronounced within a salinity range of 0-16.6, and likely the result of scavenging and flocculation reactions with inorganic (i.e., Fe/Mn oxides) and organic colloids/particles. Removal of uranium may also be closely coupled to exchange and resuspension processes at the sediment/water interface. An inner-shelf pore water profile indicated the following diagenetic processes: extensive (???1 m) zones of Fe(III) - and, to a lesser degree, Mn(IV) - reduction in the absence of significant S(II) concentrations appeared to facilitate the formation of various authigenic minerals (e.g., siderite, rhodocrosite and uraninite). The pore water dissolved 238U profile co-varied closely with Mn(II). Isotopic variations as evidenced in ??234U pore waters values from this site revealed information on the origin and history of particulate uranium. Only after a depth of about 1 m did the ??234U value approach unity (secular equilibrium), denoting a residual lattice bound uranium complex that is likely an upper-drainage basin weathering product. This suggests that the enriched ??234U values represent a riverine surface complexation product that is actively involved in Mn-Fe diagenetic cycles and surface complexation reactions. In the Fly River estuary, 238U appears to exhibit a reasonably conservative distribution as a function of salinity. The absence of observed U removal does not necessarily imply non-reactivity, but instead may record an integration of concurrent U removal and release processes. There is not a linear correlation between ??234U vs. 1/ 238U that would imply simple two component mixing. It is likely that resuspension of bottom sediments, prolonged residence times in the lower reaches of the Fly River, and energetic particle-colloid interactions contribute to the observed estuarine U distribution. The supply of uranium discharged from humid, tropical river systems to the sea appears to be foremost influenced by particle/water interactions that are ultimately governed by the particular physiographic and hydrologic characteristics of an estuary. ?? 2004 Elsevier Ltd. All rights reserved.

Swarzenski, P.; Campbell, P.; Porcelli, D.; McKee, B.

2004-01-01

192

Estimation of erosion and sedimentation yield in the Ucayali river basin, a Peruvian tributary of the Amazon River, using ground and satellite methods  

NASA Astrophysics Data System (ADS)

Since 2003, the works of HYBAM observatory (www.ore-hybam.org) has allowed to quantify with accuracy, precision and over a long period Amazon's main rivers discharges and sediments loads. In Peru, a network of 8 stations is regularly gauged and managed in association with the national meteorological and Hydrological service (SENAMHI), the UNALM (National Agrological University of La Molina) and the National Water Agency (ANA). Nevertheless, some current processes of erosion and sedimentation in the foreland basins are still little known, both in volumes and in localization. The sedimentary contributions of Andean tributaries could be there considerable, masking a very strong sedimentation in subsidence zones localized between the control points of the HYBAM's network. The development of spatial techniques such as the Altimetry and reflectance measurement allows us today to complete the ground's network: HYBAM's works have allowed establishing a relation between surface concentration and reflectance in Amazonian rivers (Martinez et al., 2009, Espinoza et al., 2012) and reconstituting water levels series (Calmant et al., 2006, 2008). If the difficulty of calibration of these techniques increases towards the upstream, their use can allow a first characterization of the tributaries contributions and sedimentation zones. At world level, erosion and sedimentation yields in the upper Ucayali are exceptional, favored by a marked seasonality in this region (Espinoza et al., 2009, Lavado, 2010, Pépin et al., 2010) and the presence of cells of extreme precipitation ("Hotspots") (Johnson et al., 1976, Espinoza et al, 2009a). The upper Ucayali drainage basin is a Piggyback where the River run with a low slope, parallel to the Andean range, deposing by gravity hundred millions a year of sands, silts and clays. In this work, we thus propose an estimation of sedimentation and erosion yield in the Ucayali river basin using ground and satellite methods.

Santini, William; Martinez, Jean-Michel; Guyot, Jean-Loup; Espinoza, Raul; Vauchel, Philippe; Lavado, Waldo

2014-05-01

193

Turbulent mixing in the Amazon River: The isotopic memory of confluences  

Microsoft Academic Search

Rivers continuously discharge dissolved material to the oceans. Dissolved compounds partially result from water–rock interactions, which produce a large range of water chemical and isotopic compositions. These waters are collected by rivers, that are commonly assumed to be well-mixed with regard to their different tributaries, as a result of turbulent dispersion. In this paper, we test this hypothesis on the

Julien Bouchez; Eric Lajeunesse; Jérôme Gaillardet; Christian France-Lanord; Poliana Dutra-Maia; Laurence Maurice

2010-01-01

194

A retrospective study of pathologic findings in the Amazon and Orinoco river dolphin (Inia geoffrensis) in captivity.  

PubMed

River dolphins are especially susceptible to negative human impacts. For their conservation, attempts of relocation or procreation ex situ may become important in the future to avoid their extinction. Additional knowledge and medical experiences of river dolphin management in captivity may aid such conservation efforts. The medical records and necropsy and histopathology reports on 123 captive Amazon River dolphins (Inia geoffrensis) were re-viewed. Of these 123 animals, 105 were necropsied and 70 necropsies were supported with histopathology. Eighteen animals were not necropsied. Among wild-born animals, mortality was highest in the first 2 mo immediately postcapture and transport, accounting for 32 of 123 deaths. Pneumonia and skin lesions (cutaneous and subcutaneous ulcerations and abscesses) were the most common findings, found in 44 of 105 (42%) and 38 of 105 (36%) of gross diagnoses, respectively. At least 10 of 44 cases of pneumonia diagnosed grossly included a verminous component. Cachexia, from a variety of causes, was a major gross finding in 21 animals. Fifteen animals had histologic evidence of significant renal pathology, and this was the primary cause of death in 13 cases. Hepatic pathology was found in 18 cases, and bacterial sepsis was confirmed via histology in 16 cases. Based on these findings, it may be concluded that keys to successful maintenance of this species include 1) prophylactic anthelminthic and antibiotic therapy immediately post-capture; 2) maintenance of animals in larger enclosures than in past attempts, in compatible groups, and in facilities capable of separating aggressive animals; 3) maintenance in microbiologically hygienic water quality at all times; and 4) a proactive program of preventive medicine during the immediate postcapture, quarantine, and maintenance period of captivity. PMID:17679501

Bonar, Christopher J; Boede, Ernesto O; Hartmann, Manuel García; Lowenstein-Whaley, Joanne; Mujica-Jorquera, Esmeralda; Parish, Scott V; Parish, James V; Garner, Michael M; Stadler, Cynthia K

2007-06-01

195

Seasonal cycle and interannual variability in the Amazon hydrologic cycle  

E-print Network

], and historical Amazon River discharge. Over a seasonal cycle the precipitation is found to vary by 5 mm d 1­1996. The precipitation lags behind the Southern Oscillation Index by 3­4 months while the Amazon River discharge lags and accuracy [e.g., Xie and Arkin, 1996]. Together with the newly available long-term historical Amazon River

Zeng, Ning

196

Sciadicleithrum juruparii n. sp. (Monogenea: Ancyrocephalidae) from the gills of Satanoperca jurupari (Heckel) (Osteichthyes: Cichlidae) in the Guamá River, Amazon Delta, Brazil.  

PubMed

Sciadicleithrum juruparii n. sp. is described from the gills of the Neotropical cichlid fish Satanoperca jurupari (Heckel) caught in the Guamá River, in the delta of the Amazon River, at Belém, Pará State, Brazil. Diagnostic characters of the new species are a basally articulated male copulatory organ with clockwise coils and an accessory piece; a ventral bar with a median process; similar hooklets; vagina in the form of a sclerotised tube; and a sinistral vaginal aperture with a sclerotised papilla lying in a small surface depression. It is the only species of Sciadicleithrum Kritsky, Thatcher & Boeger, 1989 with a medial projection on the ventral bar. PMID:22581249

de Melo, Marly de Fátima Carvalho; dos Santos, Jeannie Nascimento; Santos, Cláudia Portes

2012-06-01

197

Mercury bioaccumulation patterns in fish from the Iténez river basin, Bolivian Amazon.  

PubMed

The bioaccumulation mechanism expresses an increment of mercury concentration along the lifetime of each individual. It is generally investigated along the age or size range of organisms from a same population. Water chemistry and trophic position are important factors that may influence the emergence of bioaccumulation patterns. In order to detect the influence of these parameters on fish mercury bioaccumulation patterns, we explored the relations between mercury concentration, size and isotopic trophic position of fish populations of six species (three non piscivorous and three piscivorous) in three rivers of the Iténez basin (Bolivia) with different sediment load in water and anthropogenic impact. Fishes of the Iténez basin showed fairly lower mercury contamination in relation to the regional context. They presented lower total mercury concentrations in unperturbed clear water river (average of 0.051 ?g g(-1) for non piscivores; 0.088 ?g g(-1) for piscivores), intermediate values (average of 0.05 and 0.104 ?g g(-1)) in unperturbed white water river, whereas the highest values (average of 0.062 and 0.194 ?g g(-1)) were found in the perturbed clear water river. Piscivore and invertivore species showed significant positive bioaccumulation patterns in the perturbed river and in the unperturbed white water river. No positive pattern was detected in the unperturbed clear water river. Positive patterns could not be attributed to differences in trophic condition and mean fish mercury concentration between populations. Bioaccumulation seems not to be the main factor to explain increased mercury concentrations in fish from the perturbed river. PMID:22727595

Pouilly, Marc; Pérez, Tamara; Rejas, Danny; Guzman, Fabiola; Crespo, Giovanni; Duprey, Jean-Louis; Guimarães, Jean-Remy D

2012-09-01

198

New views on "old" carbon in the Amazon River: Insight from the source of organic carbon eroded from the Peruvian Andes  

NASA Astrophysics Data System (ADS)

rivers play a key role in the delivery of particulate organic carbon (POC) to large river systems and the ocean. Due to the extent of its drainage area and runoff, the Amazon River is one of Earth's most important biogeochemical systems. However, the source of POC eroded from the humid region of the Eastern Andes and the input of fossil POC from sedimentary rocks (POCfossil) remains poorly constrained. Here we collected suspended sediments from the Kosñipata River during flood events to better characterize Andean POC, measuring the nitrogen to organic carbon ratio (N/C), stable carbon isotopes (?13Corg) and radiocarbon (?14Corg). ?14Corg values ranged from -711‰ to -15‰, and significant linear trends between ?14Corg, N/C and ?13Corg suggested that this reflects the mixing of POCfossil with very young organic matter (?14Corg ~ 50‰) from the terrestrial biosphere (POCnon-fossil). Using N/C and ?14Corg in an end-member mixing analysis, we quantify the fraction of POCfossil (to within 0.1) and find that it contributes a constant proportion of the suspended sediment mass (0.37 ± 0.03%) and up to 80% of total POC. In contrast, the relative contribution of POCnon-fossil was variable, being most important during the rising limb and peak discharges of flood events. The new data shed light on published measurements of "old" POC (low ?14Corg) in Andean-fed tributaries of the Amazon River, with their ?14Corg and ?13Corg values consistent with variable addition of POCfossil. The findings suggest a greater persistence of Andean POC in the lowland Amazon than previously recognized.

Clark, K. E.; Hilton, R. G.; West, A. J.; Malhi, Y.; GröCke, D. R.; Bryant, C. L.; Ascough, P. L.; Robles Caceres, A.; New, M.

2013-05-01

199

Correlation between river slope and meandering variability (obtained by DGPS data) and morphotectonics for two Andean tributaries of the Amazon river: the case of Beni (Bolivia) and Napo (Ecuador-Peru) rivers.  

NASA Astrophysics Data System (ADS)

The Beni river drains a catchment area of 282 000 km2 of which 40 percent are located in the Cordillera of the Bolivian and Peruvian Andes, and the rest in the Amazonian plain : the studied reaches runs from Guanay (Andean Piedmont) to Riberalta (junction with Madre de Dios river) that represents a distance by the river of 1055 km. The Napo river starts in the Ecuadorian Andes and leaves Ecuador in Nuevo Rocafuerte (27 400 km2) and enters in Peru until its junction with the Amazon river : the studied section runs from Misahualli (Andean Piedmont) to this junction, that represents a distance by the river of 995 km. The GPS data were acquired using a mobile GPS embarked on a boat and 4 fixed bases located along the Beni river, 6 along the Napo river and the two rivers profile calculated from post-treated differential GPS solutions. For the Beni river, two sectors were identified: - the upstream sector (~230 km) between Guanay (414 m) and 50 km downstream Rurrenabaque (245 m) is located in Andean Piedmont, which consists in a series of thrusts associated with anticlines and synclines (the subandean zone), and presents slope values range between 135 cm/km and 10 cm/km and an average index of sinuosity (IS) of 1.29, - the downstream sector (~ 820 km) which runs in Amazonian plain (until Riberalta -165 m-), is characterized by an average slope of 8 cm/km and an average IS of 2.06 (this sector is much more homogeneous and the Beni river shows a meandering channel). For the Napo River, three sectors were identified: - the first sector (~140 km) between Misahualli (401 m) and Coca (265 m), is located in Andean Piedmont (subandean zone) and presents slope values range between 170 cm/km and 30 cm/km and an average IS of 1.6, - the second sector (~250 km) between Coca (when the Napo river enters in the Amazonian plain) and Nuevo Rocafuerte (190 m), presents slope values range between 30 cm/km and 20 cm/km and an average IS of 1.2, and a convex-up shape profile corresponding to the preserved part of the Pastaza-Napo Megafan, not yet affected by headwater erosion, - the third sector (~600 km) between Nuevo Rocafuerte and the confluence with the Amazon river (101 m), where the Napo river flows through the quaternary deposits of the Pastaza-Napo Megafan, presents slope values ranging from 20 to 10 cm/km and an average IS of 1.2, and is characterized by a more classical concave-up shape profile. Our main results established using DGPS data (an important difference between the slope and IS averages of the Napo and the Beni rivers in their Amazonian part, respectively ~20 cm/km and ~8 cm/km, ie a ratio ~2.5, 1.2 and 2.06, ie a ratio ~0.6) bring an additional explanation to the results obtained by the preceding authors, with balance methods, and confirm respectively the erosion and the sedimentation behaviour of the Napo and the Beni rivers.

Bourrel, L.; Darrozes, J.; Guyot, J.; Christophoul, F.; Bondoux, F.

2007-05-01

200

Association of calcium with colloidal particles and speciation of calcium in the Kalix and Amazon rivers  

NASA Astrophysics Data System (ADS)

A considerable amount of colloidally bound Ca has been detected in water samples from Amazonian rivers and the Kalix River, a sub-arctic boreal river. Fractionation experiments using several analytical techniques and processing tools were conducted in order to elucidate the matter. Results show that on average 84% of the total Ca concentration is present as free Ca. Particulate, colloidal and complexed Ca constitute the remaining 16%, of which the colloidal fraction is significant. Ultrafiltration experiments show that the colloidal fraction in the sampled Amazonian rivers and the Kalix River range between 1% and 25%. In both the Amazonian and the Kalix rivers the technique of cross-flow ultrafiltration was used to isolate particles and colloids. The difference in concentration measured with ICP-AES and a Ca ion-selective electrode in identical samples was used to define the free Ca concentration and thus indirectly the magnitude of the particulate, colloidal and complexed fractions. Results from the Kalix and Amazonian rivers are in excellent agreement. Furthermore, the results show that the colloidal concentrations of Ca can be greatly overestimated (up to 227%) when conventional analysis and calculation of ultrafiltration data is used due to retention of free Ca ions during the ultrafiltration process. Calculation methods for colloidal matter are presented in this work, using complementary data from ISE analysis. In the Kalix River temporal changes in the fractionation of Ca were studied before, during and after a spring-flood event. Changes in the size distribution of colloidally associated Ca was studied using FlFFF (Flow Field-Flow Fractionation) coupled on-line to a HR ICP-MS. The FlFFF-HR ICP-MS fractograms clearly show the colloidal component of Ca, supporting the ultrafiltration findings. During winter conditions the size distribution of colloidally associated Ca has a concentration maximum at ˜5 to 10 nm in diameter, shifting to smaller sizes (<5 nm) during and after the spring flood. This shift in size distribution follows a change in the river during this period from ironoxyhydroxy colloids being the most important colloidal carrier phase to humic substances during and after the spring flood. WHAM and NICA-Donnan models were used to calculate the amount of colloidally bound Ca. The results similar for both models, show that on average 16% of the Ca may be associated to a colloidal phase, which is in broad agreement with the measurements.

Dahlqvist, Ralf; Benedetti, Marc F.; Andersson, Karen; Turner, David; Larsson, Tobias; Stolpe, Björn; Ingri, Johan

2004-10-01

201

Top-down, bottom-up and physical controls on diatom-diazotroph assemblage growth in the Amazon River Plume  

NASA Astrophysics Data System (ADS)

The nutrient-rich waters of the Amazon River Plume (ARP) support dense blooms of diatom-diazotroph assemblages (DDA) that introduce large quantities of new nitrogen to the planktonic ecosystem and, unlike other nitrogen-fixers, are likely to directly fuel vertical carbon flux. To investigate the factors controlling DDA blooms, we develop a five phytoplankton (cyanobacteria, diatoms, unicellular microbial diazotrophs, DDA, and Trichodesmium), two zooplankton model and embed it within a 1/6° resolution physical model of the tropical and subtropical Atlantic. The model generates realistic DDA blooms in the ARP and also exhibits basin-wide primary production, nitrogen fixation, and grazing rates consistent with observed values. By following ARP water parcels with synthetic Lagrangian drifters released at the river mouth we are able to assess the relative impacts of grazing, nutrient supply, and physical forcing on DDA bloom formation. DDA bloom formation is stimulated in the silica-rich water of the ARP by decreases in grazing pressure when mesozooplankton (which co-occur in high densities with coastal diatom blooms) concentrations decrease. Bloom termination is driven primarily by silica limitation of the DDA. In agreement with in situ data, this net growth niche for DDA exists in a salinity range from ~ 20-34 PSU, although this co-occurrence is coincidental rather than causative. Because net growth rates are relatively modest, bloom formation in ARP water parcels depends critically on the time spent in this ideal habitat, with high DDA biomass only occurring when water parcels spent > 23 days in the optimal habitat niche.

Stukel, M. R.; Coles, V. J.; Brooks, M. T.; Hood, R. R.

2013-08-01

202

Top-down, bottom-up and physical controls on diatom-diazotroph assemblage growth in the Amazon River plume  

NASA Astrophysics Data System (ADS)

The nutrient-rich waters of the Amazon River plume (ARP) support dense blooms of diatom-diazotroph assemblages (DDAs) that introduce large quantities of new nitrogen to the planktonic ecosystem and, unlike other nitrogen-fixers, are likely to directly fuel vertical carbon flux. To investigate the factors controlling DDA blooms, we develop a five phytoplankton (cyanobacteria, diatoms, unicellular microbial diazotrophs, DDAs, and Trichodesmium), two zooplankton model and embed it within a 1/6° resolution physical model of the tropical and subtropical Atlantic. The model generates realistic DDA blooms in the ARP and also exhibits basin-wide primary production, nitrogen fixation, and grazing rates consistent with observed values. By following ARP water parcels with synthetic Lagrangian drifters released at the river mouth we are able to assess the relative impacts of grazing, nutrient supply, and physical forcing on DDA bloom formation. DDA bloom formation is stimulated in the nitrogen-poor and silica-rich water of the ARP by decreases in grazing pressure when mesozooplankton (which co-occur in high densities with coastal diatom blooms) concentrations decrease. Bloom termination is driven primarily by silica limitation of the DDAs. In agreement with in situ data, this net growth niche for DDAs exists in a salinity range from ∼20-34 PSU, although this co-occurrence is coincidental rather than causative. Because net growth rates are relatively modest, bloom formation in ARP water parcels depends critically on the time spent in this ideal habitat, with high DDA biomass only occurring when water parcels spent >23 days in the optimal habitat niche.

Stukel, M. R.; Coles, V. J.; Brooks, M. T.; Hood, R. R.

2014-06-01

203

Floodplain hydrology in an Amazon floodplain lake (Lago Grande de Curuai)  

E-print Network

; accepted 16 October 2007 KEYWORDS Amazon river; Floodplain; River­floodplain interactions; Hydrologic with the Amazon River and its tributaries and these floodplains alter the transport of water and dissolved

Boyer, Edmond

204

Modelling the possible effects of climate change on an Australian multi-fleet prawn fishery  

Microsoft Academic Search

The operating model The model developed for the present study is a stag e\\/size-structured metapopulation model of the schoo l prawn stocks inhabiting the Clarence River. It incl udes individual-based population dynamics and movement between compartments that are both subject to the e ffects of temperature and river discharge. Three fi sheries exploit the modelled population with the fisher dyn

M. C. Ives; J. P. Scandol; S. S. Montgomery; I. M. Suthers

2009-01-01

205

Effects of temperature and dissolved oxygen content on oxygen consumption rate of Chinese prawn, giant tiger prawn and giant freshwater prawn  

Microsoft Academic Search

Temperature and the dissolved oxygen content affect the oxygen consumption of juveniles of Chinese prawn (Penaeus chinensis), giant tiger prawn (P. monodon) and giant freshwater prawn (Macrobrachium rosenbergii). There is good correlation between the oxygen consumption rate (V, mg\\/g·h) of the above three prawn species and the water temperature, and dissolved oxygen. In the range of test temperature,V increased with

Xi-Lin Dai; Wei-Ling Zang; Wei-Dong Wang; Yong-Hai Shi; Wen-Cui Liu; Gui-Rong Xu; Shi-Hua Li

1999-01-01

206

Methane flux from the Amazon River floodplain: Emissions during rising water  

Microsoft Academic Search

During April and May of 1987, an extensive methane flux data set from Amazonian wetland habitats was collected during the wet season as river water levels were high and rising. This work extends measurements made in the dry season of 1985, when water levels were falling. A total of 284 flux measurements were made in the three primary floodplain environments

Karen B. Bartlett; Patrick M. Crill; Jose A. Bonassi; Jeffrey E. Richey; Robert C. Harriss

1990-01-01

207

Fish assemblages of the Casiquiare River, a corridor and zoogeographical filter for dispersal between the Orinoco and Amazon basins  

USGS Publications Warehouse

Aim: The aim of this study was to determine whether the Casiquiare River functions as a free dispersal corridor or as a partial barrier (i.e. filter) for the interchange of fish species of the Orinoco and Negro/Amazon basins using species assemblage patterns according to geographical location and environmental features. Location: The Casiquiare, Upper Orinoco and Upper Negro rivers in southern Venezuela, South America. Methods: Our study was based on an analysis of species presence/absence data and environmental information (11 habitat characteristics) collected by the authors and colleagues between the years 1984 and 1999. The data set consisted of 269 sampled sites and 452 fish species (> 50,000 specimens). A wide range of habitat types was included in the samples, and the collection sites were located at various points along the entire length of the Casiquiare main channel, at multiple sites on its tributary streams, as well as at various nearby sites outside the Casiquiare drainage, within the Upper Orinoco and Upper Rio Negro river systems. Most specimens and field data used in this analysis are archived in the Museo de Ciencias Naturales in Guanare, Venezuela. We performed canonical correspondence analysis (CCA) based on species presence/absence using two versions of the data set: one that eliminated sites having < 5 species and species occurring at < 5 sites; and another that eliminated sites having < 10 species and species occurring at < 10 sites. Cluster analysis was performed on sites based on species assemblage similarity, and a separate analysis was performed on species based on CCA loadings. Results: The CCA results for the two versions of the data set were qualitatively the same. The dominant environmental axis contrasted assemblages and sites associated with blackwater vs. clearwater conditions. Longitudinal position on the Casiquiare River was correlated (r2 = 0.33) with CCA axis-1 scores, reflecting clearwater conditions nearer to its origin (bifurcation of the Orinoco) and blackwater conditions nearer to its mouth (junction with the Rio Negro). The second CCA axis was most strongly associated with habitat size and structural complexity. Species associations derived from the unweighted pair-group average clustering method and pair-wise squared Euclidean distances calculated from species loadings on CCA axes 1 and 2 showed seven ecological groupings. Cluster analysis of species assemblages according to watershed revealed a stronger influence of local environmental conditions than of geographical proximity. Main conclusions: Fish assemblage composition is more consistently associated with local environmental conditions than with geographical position within the river drainages. Nonetheless, the results support the hypothesis that the mainstem Casiquiare represents a hydrochemical gradient between clearwaters at its origin and blackwaters at its mouth, and as such appears to function as a semi-permeable barrier (environmental filter) to dispersal and faunal exchanges between the partially vicariant fish faunas of the Upper Orinoco and Upper Negro rivers. ?? 2008 The Authors.

Winemiller, K.O.; Lopez-Fernandez, H.; Taphorn, D.C.; Nico, L.G.; Duque, A.B.

2008-01-01

208

Impact of forested fallows on fertility and mercury content in soils of the Tapajós River region, Brazilian Amazon.  

PubMed

Recent research on slash-and-burn agriculture conducted in the Amazonian basin has suggested that soils must be left under forested fallows for at least 10 to 15 years to regain fertility levels comparable to non-disturbed forests in order to allow for short cycle crop cultivation. However, small scale farmers tend nowadays to re-burn secondary forests as soon as after 3 to 5 years, thus could contribute to further reduce soil fertility and could enhance the transfer of mercury (Hg) naturally present in soils of the region towards water courses. The present research project sets out to characterize the impact of forested fallows of differing age and land-use history on soils properties (fertility and Hg contents) in the region of the Tapajós River, an active pioneer front of the Brazilian Amazon. To do this, soil samples in forested fallows of variable age and in control primary forests were retrieved. In general, soil fertility of grouped forested fallows of different ages was similar to that of the primary forests. But when discriminating soils according to their texture, forested fallows on coarse grained soils still had much higher NH4/NO3 ratios, NH4 and Ca contents than primary forests, this even 15 years after burning. The impact of repeated burnings was also assessed. Fallows on coarse grained soils showed an impoverishment for all variables related to fertility when the number of burnings was 5 or more. For fallows on fine grained soils that underwent 5 or more burnings, NO3 contents were low although a cation enrichment was observed. Total soil Hg content was also sensitive to repeated burnings, showing similar losses for forested fallows established on both types of soil. However, Hg linked to coarse particles appeared to migrate back towards fine particles at the surface of coarse grained soils in fallows older than 7 years. PMID:23651778

Patry, Cynthia; Davidson, Robert; Lucotte, Marc; Béliveau, Annie

2013-08-01

209

Methane flux from the Amazon River floodplain: Emissions during rising water  

SciTech Connect

During April and May of 1987, an extensive methane flux data set from Amazonian wetland habitats was collected during the wet season as river water levels were high and rising. This work extends measurements made in the dry season of 1985, when water levels were falling. A total of 284 flux measurements were made in the three primary floodplain environments of open-water lakes and channels, floating grass mats, and flooded forests, along approximately 1,500 km of the central floodplain. Emissions (means and standard errors) were 74 {plus minus} 14 mg CH{sub 4}/m{sup 2}/d (open water), 201 {plus minus} 35 mg CH{sub 4}/m{sup 2}/d (grass mats), and 126 {plus minus} 20 mg CH{sub 4}/m{sup 2}/d (flooded forests). These values were not significantly different from the majority of those from 1985, in part due to the high variability in flux seen at both times. Although ebullition was a significant component of methane emissions at both periods, the frequency of bubbling and its contribution to total flux was lower during the period of rising water than during falling water. A prominent diurnal pattern in atmospheric methane concentrations was observed, with minimum levels of about 1.75 ppm at midday and a maximum of 2.12 ppm at about midnight. Given the relatively small season changes observed in flux at the two stages of the rivers hydrographic curve, earlier estimates of regional methane flux remain largely unchanged. Revision of global estimates of wetland methane sources based on these tropical data and recently published figures for northern peatlands indicated that tropical wetlands may be more important than previously suggested, but that wetland sources overall remain at approximately 110 Tg/yr.

Bartlett, K.B.; Crill, P.M. (College of William and Mary, Williamsburg, VA (USA)); Bonassi, J.A. (Universidade de Sao Paulo (Brazil)); Richey, J.E. (Univ. of Washington, Seattle (USA)); Harriss, R.C. (Univ. of New Hampshire, Durham (USA) NASA Langley Research Center, Hampton, VA (USA))

1990-09-20

210

Dams in the Amazon: Belo Monte and Brazil's Hydroelectric Development of the Xingu River Basin  

NASA Astrophysics Data System (ADS)

Hydroelectric dams represent major investments and major sources of environmental and social impacts. Powerful forces surround the decision-making process on public investments in the various options for the generation and conservation of electricity. Brazil’s proposed Belo Monte Dam (formerly Kararaô) and its upstream counterpart, the Altamira Dam (better known by its former name of Babaquara) are at the center of controversies on the decision-making process for major infrastructure projects in Amazonia. The Belo Monte Dam by itself would have a small reservoir area (440 km2) and large installed capacity (11, 181.3 MW), but the Altamira/Babaquara Dam that would regulate the flow of the Xingu River (thereby increasing power generation at Belo Monte) would flood a vast area (6140 km2). The great impact of dams provides a powerful reason for Brazil to reassess its current policies that allocate large amounts of energy in the country’s national grid to subsidized aluminum smelting for export. The case of Belo Monte and the five additional dams planned upstream (including the Altamira/Babaquara Dam) indicate the need for Brazil to reform its environmental assessment and licensing system to include the impacts of multiple interdependent projects.

Fearnside, Phillip M.

2006-07-01

211

On the offshore dispersal of the Amazon's Plume in the North Atlantic: Comments on the paper by A. Longhurst, "Seasonal  

E-print Network

space. In a recent paper by Longhurst (1993). the plume associated with the Amazon River was attributed plume originates at the Amazon River mouth near the equator, and the other at the Orinoco River mouth

McGillicuddy Jr., Dennis J.

212

Trophic Ecology of Frugivorous Fishes in Floodplain forests of the Colombian Amazon  

E-print Network

Diverse fish species consume fruits and seeds in the Neotropics, in particular in the lowland reaches of large rivers, such as the Amazon, Orinoco, and Parana in South America. Floodplains of the Amazon River and its lowland tributaries...

Correa Valencia, Sandra Bibiana

2012-10-19

213

Coupling a basin erosion and river sediment transport model into a large scale hydrological model: an application in the Amazon basin  

NASA Astrophysics Data System (ADS)

This study presents the first application and preliminary results of the large scale hydrodynamic/hydrological model MGB-IPH with a new module to predict the spatial distribution of the basin erosion and river sediment transport in a daily time step. The MGB-IPH is a large-scale, distributed and process based hydrological model that uses a catchment based discretization and the Hydrological Response Units (HRU) approach. It uses physical based equations to simulate the hydrological processes, such as the Penman Monteith model for evapotranspiration, and uses the Muskingum Cunge approach and a full 1D hydrodynamic model for river routing; including backwater effects and seasonal flooding. The sediment module of the MGB-IPH model is divided into two components: 1) prediction of erosion over the basin and sediment yield to river network; 2) sediment transport along the river channels. Both MGB-IPH and the sediment module use GIS tools to display relevant maps and to extract parameters from SRTM DEM (a 15" resolution was adopted). Using the catchment discretization the sediment module applies the Modified Universal Soil Loss Equation to predict soil loss from each HRU considering three sediment classes defined according to the soil texture: sand, silt and clay. The effects of topography on soil erosion are estimated by a two-dimensional slope length (LS) factor which using the contributing area approach and a local slope steepness (S), both estimated for each DEM pixel using GIS algorithms. The amount of sediment releasing to the catchment river reach in each day is calculated using a linear reservoir. Once the sediment reaches the river they are transported into the river channel using an advection equation for silt and clay and a sediment continuity equation for sand. A sediment balance based on the Yang sediment transport capacity, allowing to compute the amount of erosion and deposition along the rivers, is performed for sand particles as bed load, whilst no erosion or deposition is allowed for silt and clay. The model was first applied on the Madeira River basin, one of the major tributaries of the Amazon River (~1.4*106 km2) accounting for 35% of the suspended sediment amount annually transported for the Amazon river to the ocean. Model results agree with observed data, mainly for monthly and annual time scales. The spatial distribution of soil erosion within the basin showed a large amount of sediment being delivered from the Andean regions of Bolivia and Peru. Spatial distribution of mean annual sediment along the river showed that Madre de Dios, Mamoré and Beni rivers transport the major amount of sediment. Simulated daily suspended solid discharge agree with observed data. The model is able to provide temporaly and spatialy distributed estimates of soil loss source over the basin, locations with tendency for erosion or deposition along the rivers, and to reproduce long term sediment yield at several locations. Despite model results are encouraging, further effort is needed to validate the model considering the scarcity of data at large scale.

Buarque, D. C.; Collischonn, W.; Paiva, R. C. D.

2012-04-01

214

Influence of ecological factors and of land use on mercury levels in fish in the Tapajo s River basin, Amazon$  

E-print Network

in the hydrological cycle enable very good prediction of Hg levels in fish. Our cartographical data clearly showed Amazon is presently undergoing profound disruption, and current deforestation is not merely a consequence deforestation reflect the demographic structure of local households as well as the impacts of credit policies

Long, Bernard

215

Z .The Science of the Total Environment 00 2000 00 00 z /Is the Negro River Basin Amazon impacted by  

E-print Network

in the Brazilian Ama- zon region has been mostly associated to gold mining activities. This informal type of mining contamination and gold mining is not always clear in the Amazon, and has 0048-9697r00r$ - see front matter 2000, a region where gold mining activities are rare and under constant surveillance of the Fed- eral Police

Jardim, Wilson de Figueiredo

216

An Assessment of Rainforest Change Using Satellite Images for the Bragantina Region of the Amazon River Basin  

Microsoft Academic Search

Satellite technology has allowed for the evaluation of changes in the Amazon rain- forest that might otherwise be difficult to assess. This study focuses on the region of Bragantina in the state of Para, Brazil. Two Landsat Thematic Mapper satellite images, from 1984 and 1994, were analyzed to evaluate the change in forest area. A classification was made for both

Jonathan Hoekenga; Cynthia J. Berlin

217

The Pan-Amazonian Ucayali Peneplain, late Neogene sedimentation in Amazonia, and the birth of the modern Amazon River system  

Microsoft Academic Search

We review the Neogene geologic history of lowland Amazonia in an attempt to focus attention on areas of agreement, as well as areas in dispute, in this research arena. We reinterpret pre-existing hypotheses, present new data, and discuss new insights intended to support a unified synthesis of the Amazon Basin as a single sedimentary basin, albeit on a vast scale,

Kenneth E. Campbell Jr.; Carl David Frailey; Lidia Romero-Pittman

2006-01-01

218

Identification of Major and Minor Allergens of Black Tiger Prawn (Penaeus monodon) and King Prawn (Penaeus latisulcatus)  

PubMed Central

Background: Prawns and shrimp are a frequent cause of seafood allergy mediated by IgE antibodies. Penaeus monodon and Penaeus latisulcatus, commonly known as black tiger prawn and king prawn, respectively, are among the most frequently consumed prawns in Malaysia. The aim of this study was to identify the IgE-binding proteins of these 2 prawn species. Methods: Raw and boiled prawn extracts were prepared and then resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). IgE-immunoblotting was then performed using sera from patients with positive skin prick tests to the raw prawn extracts. Results: SDS-PAGE analysis of the raw extracts of both prawn species revealed 23 protein bands; the boiled extracts yielded fewer protein bands. The bands in the range of 40 to 100 kDa were sensitive to heat and therefore were not found in the boiled extracts. Immunoblot of raw extracts of black tiger prawns and king prawns yielded 14 and 11 IgE-binding proteins, respectively, with molecular weights of between 15 and 200 kDa. Proteins at 36, 42, and 49 kDa were detected as the major allergens in both species of prawns. A protein of 75 kDa was also identified as a major allergen in black tiger prawns. Other potential allergens were also observed at various molecular masses. Conclusion: Proteins of 36, 42, and 49 kDa were identified as the major allergens of both species of prawns. The 36 and 42 kDa proteins are hypothesised to be tropomyosin and arginine kinase, respectively. A high molecular weight protein of 75 kDa was found to be an additional major allergen in black tiger prawns. PMID:22135598

Sahabudin, Syuhaidah; Misnan, Rosmilah; Yadzir, Zailatul Hani Mohammad; Mohamad, Jamaludin; Abdullah, Noormalin; Bakhtiar, Faizal; Murad, Shahnaz

2011-01-01

219

A time series analysis of Prochilodus nigricans landings caught by small-scale fisheries in the lower stretch of the Amazon River.  

PubMed

We developed a time series analysis using data on curimatã (Prochilodus nigricans), which landed in Santarém, a small city located on the right banks of the Amazon River. A 10-year record of monthly average catches per day of P. nigricans was analyzed using forecasting procedures in the open-source software GRETL 1.7.8. We established two models from the identifications made with the correlograms of hyperparametrization and seasonal differences. The autoregressive terms of the model reach three years, indicating that individuals of the species are being caught around the age of three. This may indicate that the curimatãs in the landings at Santarém from 1992 to 2002 were more than two years old, potentially a sign of a lack of fishing pressure on the lower age groups. PMID:23644788

Santana, I F; Freitas, C E C

2013-02-01

220

(210)Pb and composition data of near-surface sediments and interstitial waters evidencing anthropogenic inputs in Amazon River mouth, Macapá, Brazil.  

PubMed

Activity profiles of excess (210)Pb determined in three sediment cores from Amazon River mouth, Macapá city, Brazil, provided the evaluation of sedimentation rates, contributing to a better knowledge of the hydrological conditions in the site that is the capital of Amapá State and is drained by the waters of the huge Amazon River. Chemical data were also determined in the sediments, allowing identify signatures coupled to anthropogenic inputs held in the past in Amapá State. Significant direct relationships between LOI (loss on ignition) and organic matter were found for all sediments profiles. Silica was found to be inversely related to organic matter in the three profiles; its decrease accompanied an increase on the specific surface of the sediments. This relationship was confirmed by a great number of inverse significant correlations among silica and oxides Na(2)O, K(2)O, CaO, MgO, Al(2)O(3), P(2)O(5), Fe(2)O(3) and MnO. It was possible to identify the role of organic matter on adsorption of several oxides in the core sediments profiles. Apparent sediment mass accumulation rates corresponding to values between 450 and 2510 mg cm(-2)yr(-1) were obtained, and are compatible with the results of others studies. The (210)Pb activities in one sampling point suggested the occurrence of anthropogenic inputs related to the initial period of the mining activities conducted in Serra do Navio, Amapá State, for the commercialization of Mn ores. This was reinforced by the abrupt fluctuations in chemical data obtained for the sediments and composition of the interstitial waters occurring there. The Atlantic hurricane activity also appeared to affect the sedimentation rates in the area, as two different values were recorded in each profile. PMID:21353731

Nery, José Reinaldo Cardoso; Bonotto, Daniel Marcos

2011-04-01

221

Water slope and discharge in the Amazon River estimated using the shuttle radar topography mission digital elevation model  

Microsoft Academic Search

We find that the standard deviation, hence error, of the water surface elevation data from the Shuttle Radar Topography Mission (SRTM) is 5.51 m for basin-wide, regional and local Amazon mainstem reaches. This error implies a minimum reach length of 733km in order to calculate a reliable water-surface slope. Resulting slopes are 1.92 +\\/- 0.19 cm\\/km for Manacapuru, 2.86 +\\/-

Gina LeFavour; Doug Alsdorf

2005-01-01

222

Mercury inputs into the Amazon Region, Brazil  

Microsoft Academic Search

Mercury inputs into the Brazilian Amazon ecosystem due to goldmining activities are quantified based on data from various Brazilian Mineral and Environmental Agencies as well as field works. Total losses of Hg were estimated to be 1.32 kg Hg\\/kg Au from which 45% are released into rivers and 55% into the atmosphere. Total Hg input to the Amazon may contribute

W. C. Pfeiffer; L. Drude de Lacerda

1988-01-01

223

Effects of temperature and dissolved oxygen content on oxygen consumption rate of Chinese prawn, giant tiger prawn and giant freshwater prawn  

NASA Astrophysics Data System (ADS)

Temperature and the dissolved oxygen content affect the oxygen consumption of juveniles of Chinese prawn ( Penaeus chinensis), giant tiger prawn ( P. monodon) and giant freshwater prawn ( Macrobrachium rosenbergii). There is good correlation between the oxygen consumption rate ( V, mg/g·h) of the above three prawn species and the water temperature, and dissolved oxygen. In the range of test temperature, V increased with water temperature and dissolved oxygen content. The V of the above three prawn species increased 0.085 mg/g·h, 0.093 mg/g·h and 0.08 mg/g·h respectively with each °C of rising temperature. The comatose point and stifling point of the juveniles rose obviously at unsuitable temperature.

Dai, Xi-Lin; Zang, Wei-Ling; Wang, Wei-Dong; Shi, Yong-Hai; Liu, Wen-Cui; Xu, Gui-Rong; Li, Shi-Hua

1999-06-01

224

Rice-Freshwater Prawn Integrated Culture in Tan Phu Thanh Village, Chau Thanh A district, Can Tho Province  

Microsoft Academic Search

Trials of freshwater prawn (Macrobrachium rosenbergii) farming in rice field and garden ditch is being conducted at JIRCAS project research site, Tan Phu Thanh village, Chau Thanh A, Can Tho province. It includes three rice-prawn farms and one garden ditch prawn farm. Juvenile prawns of 0,045 g\\/prawn in average were stocked at a density of 2 prawn\\/m2 in rice-prawn farms,

Nguyen Thanh Phuong; Vu Nam; Vo Thanh Toan; Tran Thi; Thanh Hien; Pham Minh Duc

225

The role of fluvial sediment supply and river-mouth hydrology in the dynamics of the muddy, Amazon-dominated Amapá-Guianas coast, South America: A three-point research agenda  

NASA Astrophysics Data System (ADS)

The morphology and sediment dynamics of the 1500 km-long coast of South America between the mouths of the Amazon and the Orinoco Rivers are largely dependent on the massive suspended-sediment discharge of the Amazon, part of which is transported alongshore as mud banks. These mud banks have an overwhelming impact on the geology, the geomorphology, the ecology and the economy of this coast. Although numerous field investigations and remote sensing studies have considerably enhanced our understanding of the dynamics of this coast over the last three decades, much still remains to be understood of the unique functional mechanisms and processes driving its evolution. Among the themes that we deem as requiring further attention three come out as fundamental. The first concerns the mechanisms of formation of individual mud banks from mud streaming on the shelf off the mouth of the Amazon. An unknown quantity of the fluid mud generated by offshore estuarine front activity is transported shoreward and progressively forms mud banks on the Amapá coast, Brazil. The volume of each mud bank can contain from the equivalent of the annual mud supply of the Amazon to several times this annual sediment discharge. The mechanisms by which individual banks are generated from the Amazon turbidity maximum are still to be elucidated. Areas of research include regional mesoscale oceanographic conditions and mud supply from the Amazon. The second theme is that of variations in rates of migration of mud banks, which influence patterns of coastal accretion. Research emphasis needs to be placed on the analysis of both regional meteorological-hydrodynamic forcing and distant Atlantic forcing, as well as on the hydrology of the large rivers draining the Guyana Shield. The rivers appear to generate significant offshore deflection of mud banks in transit alongshore, through a hydraulic-groyne effect. This may favour both muddy accretion on the updrift coast and downdrift mud liquefaction with probably lessened muddy deposition. The third theme concerns sand supply by the Guiana Shield rivers. The rare sand deposits are important in providing sites for human settlements and routes and for nesting by marine turtles. The limited presence of sand bodies on this coast may reflect 'mud blanketing', a hypothesis that requires verification through high-resolution seismic analyses of shelf deposits and coring operations. The large Guiana Shield rivers, especially in Surinam and Guyana, have supplied sand for the construction of significant bands of cheniers, probably enhanced by the afore-mentioned downdrift hydraulic-groyne effect on hindered mud deposition. In all the three themes of this future research agenda, two central elements are the sediment input of the rivers of the Amazon basin, starting with the massive mud supply from the Amazon catchment itself, followed by sand inputs by the Guiana Shield rivers and their river-mouth effects on mud banks.

Anthony, Edward J.; Gardel, Antoine; Proisy, Christophe; Fromard, François; Gensac, Erwan; Peron, Christina; Walcker, Romain; Lesourd, Sandric

2013-07-01

226

The impact of varying depositional processes on the preservation of lignin from the Mississippi and Amazon Rivers: A dual application of compound-specific and ramped pyrolysis radiocarbon dating  

NASA Astrophysics Data System (ADS)

The establishment of reliable terrestrial-marine particulate organic carbon (POC) fluxes is important to understanding biogeochemical cycling of carbon, reconstructing environmental and depositional processes, and organic carbon (OC) storage in continental margins. Marine preservation of riverine POC differs between river systems and depositional settings, determined by a combination of fluvial and marine processes. In this study, we compare the preservation of terrestrial OC in two depositional sediments related to major river systems - the Amazon and the Mississippi - using a combination of compound class extraction and radiocarbon determination and ramped pyrolysis radiocarbon determination that targets the bulk POC by separating it along lines of thermochemical stability. Submarine mudbanks emanating from the Amazon are continuously re-oxygenated on decadal timescales and have high iron and marine sulfate content. Conversely, subaerial marshes dominate the Mississippi delta, marked by low oxygen, iron, and sulfate content. These factors potentially result in a higher degree of selective preservation of terrestrial OC and different molecular components (Canfield, 1994; Zonneveld et al., 2010; Hedges et al., 1995) in Mississippi deltaic sediments than in the Amazon mudbank deposits. Because of these differing depositional conditions, we anticipate that more degradation-resistant terrestrial compounds, such as lignin, will be greater preserved in deltaic Mississippi River sediments versus in Amazon mudbank sediments. Preliminary results show that the Mississippi deltaic sediments have higher concentrations of lignin phenols (0.632 mg/mgOC) compared to the Amazon (Guianas mudbanks) sediments (0.176 mg/mgOC), consistent with rapid burial and less post-depositional marine processing in the wetlands. For both rivers, lignin phenol concentrations in the deposited sediment were higher than reported (Hedges et al., 1986; Onsted et al., 2000) suspended sediment lignin phenol concentrations from upstream POC (0.01 and 0.02 mg/mg OC for the Mississippi and Amazon Rivers, respectively). Lower values of %OC were observed in the deposited sediment (1.7% and 1.9% for mudbank and wetland sediments, respectively) than suspended upstream sediments (2.15% and 2.4% for the Amazon and Mississippi Rivers, respectively), implying selective preservation of lignin in both depositional environments. Preliminary ramped pyrolysis results show greater thermochemical stabilities in the mudbanks sediment compared to the wetland sediment, implying the presence of more resilient OC. Additionally, 14C results show that bulk sediments from the Mississippi River are younger (1010 ± 30) than sediment from the Amazon River (2300 ± 25), consistent with more fluvial and/or post-depositional marine processing in the mudbanks. We aim to compare the preservation of lignin in these sediments to the bulk stability and age of POC by comparing the stable carbon isotope and 14C content of extracted lignin phenols to ramped pyrolysis analysis of POC. This work is being completed as part of a NOSAMS graduate internship.

Williams, E. K.; Rosenheim, B. E.; McNichol, A. P.; Roberts, M.; Xu, L.

2012-12-01

227

TITLE: Seasonal and spatial variability of CO2 emission from a large floodplain lake in the1 lower Amazon2  

E-print Network

of the Amazon River in four hydrological phases. We calculated surficial17 CO2 concentrations from measurements Amazon River23 inflows. CO2 concentration was reduced in regions with phytoplankton blooms. The range of].51 The annual flood of the Amazon River influences the ecology and biogeochemistry52 within its floodplain

California at Santa Barbara, University of

228

Hydrologic benchmarking of meteorological drought indices at interannual to climate change timescales: a case study over the Amazon and Mississippi river basins  

NASA Astrophysics Data System (ADS)

Widely used metrics of drought are still derived solely from analyses of meteorological variables such as precipitation and temperature. While drought is generally a consequence of atmospheric anomalies, the impacts to society are more directly related to hydrologic conditions. The present study uses a standardized runoff index (SRI) as a proxy for river discharge and as a benchmark for various meteorological drought indices (scPDSI, SPI, SPEI_th, and SPEI_hg respectively). Only 12-month duration droughts are considered in order to allow a direct (no river routing) comparison between meteorological anomalies and their hydrological counterpart. The analysis is conducted over the Mississippi and Amazon river basins, which provide two contrasted test beds for evaluating drought indices at both interannual (using detrended data) and climate change (using raw data) timescales. Looking first at observations over the second half of the 20th century, the simple SPI based solely on precipitation is no less suitable than more sophisticated meteorological drought indices at detecting interannual SRI variations. Using the detrended runoff and meteorological outputs of a five-member single model ensemble of historical and 21th century climate simulations leads to the same conclusion. Looking at the 21st century projections, the response of the areal fraction in drought to global warming is shown to be strongly metric dependent and potentially overestimated by the drought indices which account for temperature variations. These results suggest that empirical meteorological drought indices should be considered with great caution in a warming climate and that more physical water balance models are needed to account for the impact of the anthropogenic radiative forcings on hydrological droughts.

Joetzjer, E.; Douville, H.; Delire, C.; Ciais, P.; Decharme, B.; Tyteca, S.

2013-12-01

229

Quantitative analysis of randomness exhibited by river channels using chaos game technique: Mississippi, Amazon, Sava and Danube case studies  

NASA Astrophysics Data System (ADS)

This paper presents a numerical evaluation of the randomness which can be observed in the geometry of major river channels. The method used is based upon that of generating a Sierpinski triangle via the chaos game technique, played with the sequence representing the river topography. The property of the Sierpinski triangle is that it can be constructed only by playing a chaos game with random values. Periodic or chaotic sequences always produce an incomplete triangle. The quantitative data about the scale of the random behaviour of the river channel pathway was evaluated by determination of the completeness of the triangle, generated on the basis of sequences representing the river channel, and measured by its fractal dimension. The results show that the most random behaviour is observed for the Danube River when sampled every 715 m. By comparing the maximum dimension of the obtained Sierpinski triangle with the gradient of the river we can see a strong correlation between a higher gradient corresponding to lower random behaviour. Another connection can be seen when comparing the length of the segment where the river shows the most random flow with the total length of the river. The shorter the river, the denser the sampling rate of observations has to be in order to obtain a maximum degree of randomness. From the comparison of natural rivers with the computer-generated pathways the most similar results have been produced by a complex superposition of different sine waves. By adding a small amount of noise to this function, the fractal dimensions of the generated complex curves are the most similar to the natural ones, but the general shape of the natural curve is more similar to the generated complex one without the noise.

Žibret, G.; Verbovšek, T.

2009-06-01

230

Effects of eyestalk ablation on growth and food conversion efficiency of the freshwater prawn Macrobrachium lanchesteri (de Man)  

Microsoft Academic Search

Bilateral eyestalk ablation in the freshwater prawn Macrobrachium lanchesteri results in high mortality, while unilateral eyestalk ablated prawns exhibited a high survival rate. There was marked increase in the growth of bilateral eyestalk-ablated prawns (47.70 mg\\/prawn) as compared to those that were unilaterally ablated (19.19 mg\\/prawn).

R. Ponnuchamy; S. Ravichandra Reddy; Katre Shakuntala

1981-01-01

231

Amazon flood wave hydraulics  

NASA Astrophysics Data System (ADS)

SummaryA bathymetric survey of 575 km of the central Amazon River and one of its tributaries, the Purus, are combined with gauged data to characterise the Amazon flood wave, and for hydraulic modelling of the main channel for the period June 1995-March 1997 with the LISFLOOD-FP and HEC-RAS hydraulic models. Our investigations show that the Amazon flood wave is subcritical and diffusive in character and, due to shallow bed slopes, backwater conditions control significant reach lengths and are present for low and high water states. Comparison of the different models shows that it is necessary to include at least the diffusion term in any model, and the RMSE error in predicted water elevation at all cross sections introduced by ignoring the acceleration and advection terms is of the order of 0.02-0.03 m. The use of a wide rectangular channel approximation introduces an error of 0.10-0.15 m on the predicted water levels. Reducing the bathymetry to a simple bed slope and with mean cross section only, introduces an error in the order of 0.5 m. These results show that when compared to the mean annual amplitude of the Amazon flood wave of 11-12 m, water levels are relatively insensitive to the bathymetry of the channel model. The implication for remote sensing studies of the central Amazon channel, such as those proposed with the Surface Water and Ocean Topography mission (SWOT), is that even relatively crude assumptions regarding the channel bathymetry will be valid in order to derive discharge from water surface slope of the main channel, as long as the mean channel area is approximately correct.

Trigg, Mark A.; Wilson, Matthew D.; Bates, Paul D.; Horritt, Matthew S.; Alsdorf, Douglas E.; Forsberg, Bruce R.; Vega, Maria C.

2009-07-01

232

Water quality changes in floodplain lakes due to the Amazon River flood pulse: Lago Grande de Curuaí (Pará).  

PubMed

Assurance of water quality for human consumption is essential for public health policies. In the Amazon floodplain, the seasonal water level variation causes periodic flooding of marginal areas that are usually used for settlements, agriculture and livestock. Therefore, the exchange of materials between the terrestrial and aquatic ecosystem affects the proportion of suspended and dissolved components in water and its physical-chemical characteristics, and consequently the quality of the water used by local people. Following this approach, the aim of this study is to evaluate changes in water quality in Lago Grande de Curuaí floodplain, Óbidos, Pará in response to the flood pulse, during one hydrological year from 2003 to 2004, based on water use classes (according to National Water Agency 357/2005 resolution) using chlorophyll-a and dissolved oxygen concentration as parameters and the eutrophication index. Ordinary kriging was applied to interpolate chlorophyll-a and dissolved oxygen and to predict values at non sampled locations. Each location was then classified according to water use acceptable parameters and to Carlson Trophic State Index modified by Toledo to map lake water classes and trophic status. The result showed that Lago Grande de Curuaí floodplain is a supereutrophic system, with levels of dissolved oxygen and chlorophyll-a not suitable for human supply during the receding water phase. These areas are located near the riverine communities, which can cause health problems due to the presence of potentially toxic algae. Therefore, monitoring water quality in Amazon lakes is essential to ensure the availability has appropriate quality for human and animal supplies. PMID:21881783

Affonso, A G; Barbosa, C; Novo, E M L M

2011-08-01

233

Ultrastructural description of Ceratomyxa microlepis sp. nov. (phylum Myxozoa): a parasite infecting the gall bladder of Hemiodus microlepis, a freshwater teleost from the Amazon River.  

PubMed

A new ceratomyxid parasite was examined for taxonomic identification, upon being found infecting the gall bladder of Hemiodus microlepis (Teleostei: Hemiodontidae), a freshwater teleost collected from the Amazon River, Brazil. Light and transmission electron microscopy revealed elongated crescent-shaped spores constituted by two asymmetrical shell valves united along a straight sutural line, each possessing a lateral projection. The spores body measured 5.2 ± 0.4 µm (n = 25) in length and 35.5 ± 0.9 µm (n = 25) in total thickness. The lateral projections were asymmetric, one measuring 18.1 ± 0.5 µm (n = 25) in thickness and the other measuring 17.5 ± 0.5 µm (n = 25) in thickness. Two equal-sized subspherical polar capsules measuring 2.2 ± 0.3 µm in diameter were located at the same level, each possessing a polar filament with 5-6 coils. The sporoplasm was binucleate. Considering the morphometric data analyzed from the microscopic observations, as well as the host species and its geographical location, this paper describes a new myxosporean species, herein named Ceratomyxa microlepis sp. nov.; therefore representing the first description of a freshwater ceratomyxid from the South American region. PMID:23579792

Azevedo, Carlos; Rocha, Sónia; Casal, Graça; São Clemente, Sérgio Carmona; Matos, Patrícia; Al-Quraishy, Saleh; Matos, Edilson

2013-04-01

234

Influence of the Amazon River on dissolved and intra-cellular metal concentrations in Trichodesmium colonies along the western boundary of the sub-tropical North Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Despite the ecological importance of Trichodesmium spp. for the global oceanic nitrogen budget, there is limited information on their trace metal composition in field samples. We report dissolved (<0.22 ?m) metal concentrations measured in surface waters (Ag, Cd, Co, Cu, Fe, Mo, Ni, P, Pb and V) and in the total and the intracellular pool (Ag, Al, Cd, Co, Cu, Fe, Mn, Mo, Ni, P, Pb, V) of Trichodesmium populations collected in the western subtropical North Atlantic Ocean (April-May 2003) within the influence of the Amazon River plume. Dissolved element distributions were strongly influenced by the River discharge, with concentrations of some elements varying directly (i.e. Cd, Mo and V) or inversely (Ag, Co, Cu, Fe, Ni, P and Pb) with surface salinity. Intracellular metal values to phosphorous ratios (mol:mol) for Cd, Co, Cu, Fe, Mn, Mo, Ni and V ranged from 9.0×10-6 for Cd to 4.4×10-2 for Fe. Although total metal composition was significantly correlated with the intracellular content in the Trichodesmium colonies for some elements (e.g., Co, Cu, V), metal pools in the phytoplankton did not co-vary with the dissolved metal concentrations, suggesting that water column measurements may not be good predictors of the intracellular metal concentrations. The impact of physical parameters and bioactive elements on biological processes in Trichodesmium such as nitrogen fixation, carbon drawdown and biomass production was explored by using a principal component analysis test (PCA). The analysis indicates that the biological drawdown of dissolved inorganic carbon (DIC) by Trichodesmium seems to be influenced by the internal content of Fe, Co, Cd, Cu and Mn, while nitrogen fixation seems more influenced by the internal concentration of Mo, Ni and V and by the dissolved phosphorous concentrations.

Tovar-Sanchez, A.; Sañudo-Wilhelmy, S. A.

2010-08-01

235

Influence of the Amazon River on dissolved and intra-cellular metal concentrations in Trichodesmium colonies along the western boundary of the sub-tropical North Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Despite the ecological importance of Trichodesmium spp. for the global oceanic nitrogen budget, there is limited information on their trace metal composition in field samples. We report dissolved (<0.22 ?m) metal concentrations measured in surface waters (Ag, Cd, Co, Cu, Fe, Mo, Ni, P, Pb and V) and in the total and the intracellular pool (Ag, Al, Cd, Co, Cu, Fe, Mn, Mo, Ni, P, Pb, V) of Trichodesmium populations collected in the western subtropical North Atlantic Ocean (April-May 2003) within the influence of the Amazon River plume. Dissolved element distributions were strongly influenced by the River discharge, with concentrations of some elements varying directly (i.e. Cd, Mo and V) or inversely (Ag, Co, Cu, Fe, Ni, P and Pb) with surface salinity. Intracellular metal values to phosphorous ratios (mol:mol) for Cd, Co, Cu, Fe, Mn, Mo, Ni and V ranged from 9.0 × 10-6 for Cd to 4.4 × 10-2 for Fe. Although total metal composition was significantly correlated with the intracellular content in the Trichodesmium colonies for some elements (e.g., Co, Cu, V), metal pools in the phytoplankton did not co-vary with the dissolved metal concentrations, suggesting that water column measurements may not be good predictors of the intracellular metal concentrations. The impact of physical parameters and bioactive elements on biological processes such as nitrogen fixation, carbon drawdown and biomass production in Trichodesmium colonies was explored by using a principal component analysis test (PCA). The analysis indicated that the biological drawdown of dissolved inorganic carbon (DIC) by Trichodesmium seems to be influenced by the internal content of Fe, Co, Cd, and Cu, while nitrogen fixation seems more influenced by mixed layer depth and dissolved Fe and Ni concentrations.

Tovar-Sanchez, A.; Sañudo-Wilhelmy, S. A.

2011-01-01

236

The Amazon basin in transition.  

PubMed

Agricultural expansion and climate variability have become important agents of disturbance in the Amazon basin. Recent studies have demonstrated considerable resilience of Amazonian forests to moderate annual drought, but they also show that interactions between deforestation, fire and drought potentially lead to losses of carbon storage and changes in regional precipitation patterns and river discharge. Although the basin-wide impacts of land use and drought may not yet surpass the magnitude of natural variability of hydrologic and biogeochemical cycles, there are some signs of a transition to a disturbance-dominated regime. These signs include changing energy and water cycles in the southern and eastern portions of the Amazon basin. PMID:22258611

Davidson, Eric A; de Araújo, Alessandro C; Artaxo, Paulo; Balch, Jennifer K; Brown, I Foster; C Bustamante, Mercedes M; Coe, Michael T; DeFries, Ruth S; Keller, Michael; Longo, Marcos; Munger, J William; Schroeder, Wilfrid; Soares-Filho, Britaldo S; Souza, Carlos M; Wofsy, Steven C

2012-01-19

237

River margins are valued for agriculture in the western Amazon because of their fertile soils and level  

E-print Network

soils and level surfaces. Riparian forests along river margins also provide valuable ecosystem services and plantains grown on upland soils. People valued riparian areas for their ecosystem services and generally, deforesta- tion, indigenous people, land use, riparian zone, Peru INTRODUCTION Land-use change in the humid

McClain, Michael

238

Total basin discharge for the Amazon and Mississippi River basins from GRACE and a land-atmosphere water balance  

Microsoft Academic Search

Freshwater discharge along continental margins is a key Earth system variable that is not well monitored globally. Here we propose a method for estimating monthly river basin outflows based on the use of new GRACE satellite estimates of terrestrial water storage changes in a coupled land-atmosphere water balance. Using GRACE land water storage changes (which include changes in groundwater storage)

T. H. Syed; J. S. Famiglietti; J. Chen; M. Rodell; S. I. Seneviratne; P. Viterbo; C. R. Wilson

2005-01-01

239

Flooding dynamics on the lower Amazon floodplain  

NASA Astrophysics Data System (ADS)

We analyzed flooding dynamics of a large floodplain lake in the lower reach of the Amazon River for the period between 1995 through 2010. Floodplain inundation was simulated using the LISFLOOD-FP model, which combines one-dimensional river routing with two-dimensional overland flow, and a local hydrological model. Accurate representation of floodplain flows and inundation extent depends on the quality of the digital elevation model (DEM). We combined digital topography (derived from the Shuttle Radar Topography Mission) with extensive floodplain echo-sounding data to generate a hydraulically sound DEM. Analysis of daily water balances revealed that the dominant source of inflow alternated seasonally among direct rain and local runoff (October through January), Amazon River (March through August), and seepage (September). As inflows from the Amazon River increase during the rising limb of the hydrograph, regional floodwaters encounter the floodplain partially inundated from local hydrological inputs. At peak flow the floodplain routes, on average, 2.5% of the total discharge for this reach. The falling limb of the hydrograph coincides with the locally dry period, allowing seepage of water stored in sediments to become a dominant source. The average annual inflow from the Amazon River was 58.8 km3 (SD = 33.5), representing more than three thirds (80%) of inputs from all sources, with substantial inter-annual variability. The average annual net export of water from the floodplain to the Amazon River was 7.9 km3 (SD = 2.7).

Rudorff, C.; Melack, J. M.; Bates, P. D.

2013-05-01

240

Apistogramma ortegai (Teleostei: Cichlidae), a new species of cichlid fish from the Ampyiacu River in the Peruvian Amazon basin.  

PubMed

Apistogramma ortegai, new species, is described from small streams tributaries of the Ampiyacu River near Pebas, in eastern Peru. It belongs to the Apistogramma regani species group and is distinguished from all other species of Apistogramma by the combination of contiguous caudal spot to bar 7, presence of abdominal stripes, short dorsal-fin lappets in both sexes, absence of vertical stripes on the caudal fin, and reduced number of predorsal and prepelvic scales. PMID:25283927

Britzke, Ricardo; Oliveira, Claudio; Kullander, Sven O

2014-01-01

241

Almeida, O.T. & Lorenzen, K. & McGrath, D.T. (2004) The fisheries sector in the Amazon regional economy.  

E-print Network

the magnitude of the fisheries sector along the Amazon River in Brazil. Total income and employment were interviewed in 15 cities along the Amazon River. The number of fishing boats and total catch were estimated tonnes in towns along the Amazon River. 15 Almeida O.1 Lorenzen K.2 McGrath D.1, 3 1 IPAM, Av. Nazaré

Lorenzen, Kai

242

Influence of ecological factors and of land use on mercury levels in fish in the Tapajós River basin, Amazon.  

PubMed

Mercury (Hg) contamination of riparian communities and of environmental compartments of the Amazon can be directly related to the occupation of the territory. The objective of this study was to identify the characteristics of aquatic environments that are associated with high levels of Hg in ichthyofauna. Our research aimed at determining the influence of variables related to fish ecology, types of aquatic environment, fishing activities by local riparian populations, and watershed use on the levels of contamination of ichthyofauna. Six sites were sampled during two distinct periods of the hydrological cycle: at the beginning of descending waters and during low waters. We focused on ten dominant fish species representing four trophic levels: Curimata inornata, Geophagus proximus, Schizodon vittatum, Leporinus fasciatus, Anostomoides laticeps, Hemiodus unimaculatus, Caenotropus labyrinthicus, Hoplias malabaricus, Plagioscion squamosissimus, Acestrorhynchus falcirostris. The study sites, which included lotic and lentic habitats, are exploited year-round by local riparian communities. Spatial variations in Hg contamination in ichthyofauna were determined by factorial analysis of variance taking into account fish diets, seasons, and sampling sites. Multiple regressions were used to check the influence of ecological and anthropogenic variables and variables related to watershed uses, on Hg levels in key species representing the four trophic groups. Each variable was checked independently. Next, multiple regressions were used to verify the concomitant influence of selected variables. Independently of the study site and the phase of the hydrologic cycle, fish Hg contamination followed the trend piscivores>omnivores>herbivores>detritivores. In all the aquatic study sites, Hg levels measured in predatory species were often higher than the 500 ng/g fresh weight threshold. Mean Hg levels in key species were significantly higher during descending waters in lotic environments, and during low waters in lentic environments. Data from this study demonstrated that simple models based on watershed use and on easily obtained variables such as the suspended particulate matter (SPM) load and SPM Hg concentrations, number of inhabitants, habitat types, and the stage in the hydrological cycle enable very good prediction of Hg levels in fish. Our cartographical data clearly showed that the watershed site with the highest aquatic vegetation cover (6% of the open water body) and with the lowest forest cover (62% of the land) corresponded to the highest Hg concentrations in fish. Conversely, the watershed site with 94% forest cover and 1% aquatic vegetation corresponded to the lowest levels Hg concentrations in fish. These results suggest that land uses of watersheds play a key role in the level of Hg contamination of local ichthyofauna. PMID:19356749

Sampaio da Silva, D; Lucotte, M; Paquet, S; Davidson, R

2009-05-01

243

Contributions of carbon and nitrogen from the Andes Mountains to the Amazon River: Evidence from an elevational gradient of soils, plants, and river material  

Microsoft Academic Search

We determined the carbon (C) and nitrogen (N) elemental and stable isotopic composition of riverine and ter- restrial organic matter (OM), as well as the concentration of dissolved organic C (DOC), d 15 NO3 2 and d 18 O of river water along an altitudinal (4,043-720 m above sea level (masl)) transect in the Andes of Peru. Plant d 13

Amy Townsend-Small; Michael E. McClain; Jay A. Brandes

2005-01-01

244

Geothermal aquaculture: a guide to freshwater prawn culture  

SciTech Connect

Biological data of the Malaysian prawn, Macrobrachium rosenbergii, are summarized. A history on its rearing techniques is given, but through the use of geothermal water or industrial warm water effluent, its range can be expanded. The use of wasted geothermal water at the Oregon Institute of Technology for prawn ponds is noted. Pond management and design; the hatchery design and function for larval culture; and geothermal applications (legal aspects and constraints) are discussed. (MCW)

Hayes, A.; Johnson, W.C.

1980-05-01

245

Amazon Interactive  

NSDL National Science Digital Library

As an extension of his graduate research, David Schaller of Educational Web Adventures has put together this resource on "indigenous ecotourism in the Ecuadorian Amazon." Using online games and activities, users explore the geography of the Ecuadorian Amazon and learn about the rainforest and its inhabitants. Through a series of questions and color photos, the site leads users down several lines of thought until they are eventually planning and managing a locally-controlled ecotourism project. While the site represents a well-intentioned learning tool and addresses several important points, the content (and Right/ Wrong format) is decidedly biased towards ecotourism and can tend to elide the conflicting complexities of such enterprises. Overall, this site could be a nice teaching tool, however, especially if its "Developed country" perspective is discussed (and not obscured) as part of the learning exercise.

Schaller, David T.

246

Phylogenetic relationships among Synallaxini spinetails (Aves: Furnariidae) reveal a new biogeographic pattern across the Amazon and Paraná river basins.  

PubMed

Relationships among genera in the tribe Synallaxini have proved difficult to resolve. In this study, I investigate relationships among Synallaxis, Certhiaxis and Schoeniophylax using DNA sequences from the mitochondrion and three nuclear regions. I implemented novel primers and protocols for amplifying and sequencing autosomal and sex-linked introns in Furnariidae that resolved basal relationships in the Synallaxini with strong support. Synallaxis propinqua is sister to Schoeniophylax phryganophilus, and together they form a clade with Certhiaxis. The results are robust to analytical approaches when all genomic regions are analyzed jointly (parsimony, maximum likelihood, and species-tree analysis) and the same basal relationships are recovered by most genomic regions when analyzed separately. A sister relationship between S. propinqua, an Amazonian river island specialist, and S. phryganophilus, from the Paraná River basin region, reveals a new biogeographic pattern shared by at least other four pairs of taxa with similar distributions and ecologies. Estimates of divergence times for these five pairs span from the late Miocene to the Pleistocene. Identification of the historical events that produced this pattern is difficult and further advances will require additional studies of the taxa involved and a better understanding of the recent environmental history of South America. A new classification is proposed for the Synallaxini, including the description of a new genus for S. propinqua. PMID:24867462

Claramunt, Santiago

2014-09-01

247

Distribution of fluid muds on the Amazon continental shelf  

Microsoft Academic Search

A comprehensive study of suspended-sediment transport on the Amazon shelf was conducted as part of the AmasSeds project (A Multidisciplinary Amazon Shelf SEDiment Study) to understand the link between physical processes and the fate of Amazon River sediment. A small instrumented tripod was used to measure the fluid, flow, and suspended-sediment characteristics throughout the water column on varying time scales

G. C. Kineke; R. W. Sternberg

1995-01-01

248

The M2 tide on the Amazon shelf  

Microsoft Academic Search

As part of A Multidisciplinary Amazon Shelf Sediment Study (AMASSEDS), moored and shipboard current measurements made over the Amazon shelf during 1990-1991 have been analyzed to determine the dominant semidiurnal tidal constituent, the M2. These results have been combined with coastal sea level data from within the Amazon and Para Rivers, the adjacent shelf, and with satellite-derived tidal elevation data

Robert C. Beardsley; Julio Candela; Richard Limeburner; W. Rockwell Geyer; Steven J. Lentz; Belmiro M. Castro; David Cacchione; Nelson Carneiro

1995-01-01

249

U-Pbdating on detrital zircon and Nd and Hf isotopes related to the provenance of siliciclastic rocks of the Amazon Basin: Implications for the origin of Proto-Amazonas River  

NASA Astrophysics Data System (ADS)

Previous provenance studies along the Amazonas river have demonstrated that the Amazon drainage basin has been reorganized since the Late Cretaceous with the uplift of the Andes and the establishment of the transcontinental Amazon fluvial system from Late Miocene to Late Pleistocene (Hoorn et al., 1995; Potter, 1997, Wesselingh et al., 2002; Figueiredo et al. 2009, Campbell et al., 2006, Nogueira et al. 2013).There is a lack of data from Eastern and Central Amazonia and only limited core data from the Continental Platform near to current Amazonas river mouth. Central Amazonia is strategic to unveil the origin of Amazonas River because it represents the region where the connection of the Solimões and Amazonas basin can be studied through time (Nogueira et al. 2013). Also, there is a shortage of information on the old Precambrian and Paleozoic sediment sources relative to Cretaceous and Miocene siliciclastic deposits of the Solimões and Amazonas basins. We collected stratigraphic data, detrital zircon U-Pb ages and Nd and Hf isotopes from Precambrian, Paleozoic, Cretaceous and Miocene siliciclastic deposits of the Northwestern border of Amazonas Basin. They are exposed in the Presidente Figueiredo region and in the scarps of Amazon River, and occur to the east of the Purus Arch. This Northwest-Southeast trending structural feature that divides the Solimões and Amazonas basin was active at various times since the Paleozoic. Detrital zircon ages for the Neoproterozoic Prosperança Formation yielded a complex signature, with different populations of Neoproterozoic (550, 630 and 800 Ma) and Paleoproterozoic to Archean sources (1.6, 2.1 and 2.6 Ga). Also Nd and Hf isotopes show two groups of TDM model ages between 1.4 to 1.53 Ga and 2.2 and 3.1 Ga. Sediments typical of Paleozoic sedimentary rocks of the Nhamundá and Manacapuru Formations revealed NdTDM model ages of 1.7, 2.2 and 2.7 Ga, but Hf isotopes and U-Pb zircon ages are more varied. They characterize a provenance dominated by Mesoproterozoic sources (1.0, 1.2 Ga) and subordinate Neoproterozoic(550-800 Ma) and Archean derivation (2.67 Ga). On the other hand, detrital zircon and Hf and NdTDM model ages for the Cretaceous Alter do Chão Formation yielded a unique Paleoproterozoicages between 2.0 and 2.3 Ga that can be correlated to sources derived from Maroni-Itacaiúnas and Central Amazonian basement provinces. The contribution of Precambrian and Paleozoic rocks exposed during the installationof the Amazonas drainage were probably significant .Such a large contribution from Neoproterozoic and Mesoproterozoic sources are not common in the proximal Amazon Craton basement .This new proposal open new perspectives to understand better the initial history of Amazon River with indication of the probable source areas during Late Cenozoic. Campbell Jr.; Frailey,C.D.; Romero-Pittman, G. 2006. The Pan-Amazonian UcayliPeneplain, late Neogenesedimentacion in Amazonia, and the Birth on the Modern Amazon River system.Palaeogeography,Palaeoclimatology, Palaeoecology. 239 (2006) 166-219 Figueiredo, J.,Hoorn, C., Van der Vem, P., Soares, E. 2009. Late Miocene onset of the Amazon River and the Amazon deep-sea fan: Evidence from the Fozdo Amazonas Basin. Geology, 37(7):619-622. Hoorn,C.; Guerrero, J.; Sarmiento, G. 1995. Andean tectonics as a cause for changing drainage patterns in Miocene Northern South America. Geology, v.23, p-237-240. Nogueira, A.C.R.; Silveira, R.R.; Guimarães, J.T.F. 2013. Neogene-Quaternary sedimentary and paleovegetation history of the eastern Solimões Basin, central Amazon region.Journal of South American Earth Sciences , v. 46, p. 89-99, 2013. Potter, P.E. 1997. The Mesozoic and Cenozoic paleodrainage of South America: a natural history. Journal of South American Earth Science.v.10. p.331-344 Wesselingh, F. P., et al., 2002. Lake-Pebas: a palaeocological reconstruction of a Miocene long-lived lake comples in Western Amazônia. Cainozoic Research 1 (1-2), 35-81.

Dantas, Elton Luiz; Silva Souza, Valmir; Nogueira, Afonso C. R.; Ventura Santos, Roberto; Poitrasson, Franck; Vieira Cruz, Lucieth; Mendes Conceição, Anderson

2014-05-01

250

T. F. Duda Jr S. R. Palumbi Population structure of the black tiger prawn, Penaeus monodon,  

E-print Network

T. F. Duda Jr á S. R. Palumbi Population structure of the black tiger prawn, Penaeus monodon, among Abstract We examined the population structure of the black tiger prawn, Penaeus monodon Fabricius, 1798 to be continuous. The black tiger prawn, Penaeus monodon, is distrib- uted from southeast Africa to eastern

Palumbi, Stephen

251

Effects of intrinsic and extrinsic factors on the haemocyte profile of the prawn, Macrobrachium rosenbergii  

Microsoft Academic Search

The giant freshwater prawn Macrobrachium rosenbergii was investigated for its total haemocyte count (THC) based on season, sex, size and feeding rate. The THC, when the prawns were subjected to injections of foreign materials was also investigated. The prawns displayed the highest and lowest THC in autumn and winter respectively, with no significant difference between male and female, or among

Winton Cheng; Jiann-Chu Chen

2001-01-01

252

Changes of Myofibrillar Proteins and Texture in Freshwater Prawn, Macrobrachium rosenbergii, During Iced Storage  

E-print Network

Changes of Myofibrillar Proteins and Texture in Freshwater Prawn, Macrobrachium rosenbergii prawn, Macrobrachium rosenbergii has been reported to be 3-4 days with devel opment of mushiness proteins and texture offreshwater prawn, Macrobrachium rosenbergii, during 14-day iced storage were studied

253

Microbiological Quality of Farmed Tropical Freshwater Prawn (Macrobrachium rosenbergii de Man)  

Microsoft Academic Search

The objective of this study was to determine the microbiological quality of farmed giant freshwater prawn (Macrobrachium rosenbergii) collected from four freshwater farms located in Kerala (India). Microbiological counts on whole, deheaded, and deheaded and deveined prawn as well as on head and intestine were determined. Average counts (log10 cfu g) on whole prawn were 6.9 (total mesophilic counts (TPC)

K. V. Lalitha; P. K. Surendran

2006-01-01

254

Microbiological changes in farm reared freshwater prawn ( Macrobrachium rosenbergii de Man) in ice  

Microsoft Academic Search

The microbiological changes in farm reared freshwater prawn (Macrobrachium rosenbergii de Man) during ice storage were studied. A total of 156 bacterial cultures from fresh and ice-stored farmed freshwater prawn were isolated and characterized. Total aerobic, mesophilic and psychrotrophic counts and hydrogen sulphide producing bacterial counts were determined. The total aerobic counts at 20 and 37°C on fresh prawn was

K. V. Lalitha; P. K. Surendran

2006-01-01

255

Parasitic fauna of eight species of ornamental freshwater fish species from the middle Negro River in the Brazilian Amazon Region.  

PubMed

Twenty-seven specimens of cardinal tetra Paracheirodon axelrodi, 33 rosy tetra Hyphessobrycon copelandi (Characidae), 28 marbled hatchetfish Carnegiella strigata, 26 blackwing hatchetfish Carnegiella martae (Gasteropelecidae), 27 bodó Ancistrus hoplogenys (Loricariidae), 31 brown pencilfish Nannostomus eques, 38 oneline pencilfish Nannostomus unifasciatus (Lebiasinidae) and 13 angelfish Pterophyllum scalare (Cichlidae) were collected from the middle Negro River, State of Amazonas, Brazil, for parasitological studies. Out of the total of 223 fish examined, 143 (64.1%) were parasitized by at least one parasite species. The highest prevalence rate was for Monogenea (36.7%), followed by Ichthyophthirius multifiliis (Ciliophora) (20.6%), Trichodina spp. (Ciliophora) (4.0%), Piscinoodinium pillulare (Dinoflagellida) (1.3%), Tetrahymena sp. (Ciliophora) (0.89%), and Procamallanus sp. (Nematoda) (0.4%). All eight fish species had Monogenea (Gyrodactylidae and Dactylogyridae) in the gills, but the highest prevalence occurred in P. scalare and the lowest in P. axelrodi and C. strigata. However, the highest mean intensity of Monogenea was found in P. scalare and A. hoplogenys. The protozoan I. multifiliis occurred in the six ornamental fish species examined, but C. strigata and C. martae had higher prevalence and mean intensity. Trichodina spp. were found only in the gills of C. strigata, C. martae and N. eques, and with higher mean intensity in C. strigata. On the other hand, the protozoan P. pilullare was found only in the gills of C. martae. This is the first report of Tetrahymena sp. in Brazil, and it occurred in the gills of C. strigata. PMID:20624347

Tavares-Dias, Marcos; Lemos, Jefferson Raphael Gonzaga; Martins, Maurício Laterça

2010-01-01

256

Are mangroves and seagrasses sources of organic carbon for penaeid prawns in a tropical Australian estuary? A multiple stable-isotope study  

Microsoft Academic Search

We used multiple stable-isotope analysis to investigate the importance of seagrasses, mangroves and other primary sources\\u000a (macroalgae, seston) to the food webs supporting penaeid prawns in the Embley River estuary and adjacent off-shore waters\\u000a in the north-eastern Gulf of Carpentaria, Australia. Mangroves, seagrass and macroalgae\\/seston were well separated on the\\u000a basis of their ?13C values in both the dry and

N. R. Loneragan; S. E. Bunn; D. M. Kellaway

1997-01-01

257

Reproductive indices in natural nests of giant Amazon river turtles Podocnemis expansa (Schweigger, 1812) (Testudines, Podocnemididae) in the Environmental Protection Area Meanders of the Araguaia River.  

PubMed

A count was made of unhatched eggs and hatchling live and dead Podocnemis expansa turtles in 327 natural nests located on the beaches of the Environmental Protection Area (EPA) Meanders of the Araguaia River, to determine the percentage of hatching (94.63%), non-hatching (5.37%), survival (94.24%) and hatchling mortality (5.76%), and the average percentage of dead hatchlings during the 15 days in the nursery (0.97%). The mean number of hatchlings per nest was determined from the sum of the number of live and dead hatchlings divided by the total number of nests, while the mean number of eggs per nest was determined from the sum of live and dead hatchlings and unhatched eggs divided by the number of nests. These calculations yielded the following mean values: live hatchlings (88.98 ± 23.94), dead hatchlings (0.37 ± 0.93), unhatched eggs (5.07 ± 9.57), and total number of eggs (94.42 ± 21.30). The reproductive efficiency of the wild population of P. expansa can be affected by many environmental factors such as temperature, humidity and rainfall. In addition, man-made factors like the presence of chemicals in the water and the potential for infectious disease also have significant impact. The reproductive indices data obtained from this study are indispensable for future investigations of hatching anomalies. PMID:22437402

Alves-Júnior, J R F; Lustosa, A P G; Bosso, A C S; Balestra, R A M; Bastos, L F; Miranda, L B; Santos, A L Q

2012-02-01

258

Geochemistry of Amazon Basin supported by the ADCP measurements  

NASA Astrophysics Data System (ADS)

The Amazon River is the largest river in the world in volume of water. The basin has 6.915.000 Km2, but the last gauging station of Amazon River with regular and continuous measurements of discharge and sediment transport are Óbidos station with 4.670.000 Km2. Óbidos It is also the last stream gauge station with no or less tidal effect observed from Atlantic Ocean and registered. The Clim-Amazon Project has been done the first measurements with the purpose to acquire geochemical and hydrological informations downstream Óbidos station. The system studied has input data of sediments load after Óbidos, and the output of the system, at the Amazon River is at Macapá, close to the mouth of Amazon river. And flow the main tributaries along this way, between these two stations. To evaluate the geochemical source, the mass balance, and isotopic geochemistry is necessary the informations about the traces the main chemical elements, transported by the discharge from the main rivers of this area: Tapajos, Xingu, Paru, Jari, and the Amazon River at Monte Alegre and at Macapá. The ADCP - Acoustic Doppler Current Profile, equipment is used to get the stream discharge value at the moment of transect. But also get two more informations necessary for the geochemistry, and do the collecting points profiles. The place with most velocity at transect or the place with more backscatter. These informations are related with the sediment load of the river. Or which one can provide the better idea of how are transported the sediments at the measured transects. What was to observe was the main speed of the stream flow or the main backscatter sectional. The main purpose of the work is to show how works the correlation between the backscatter and speed data given by the ADCP, downstream Óbidos, and the main confluences of Amazon River, until Macapá. The ADCP measurements support the geochemical studies and the course of sediments load transported by the discharge of these rivers.

Paca, Victor; Moreira, Daniel; Monteiro, Achiles; Roig, Henrique

2014-05-01

259

Assessment of deforestation in the Lower Amazon floodplain using historical Landsat MSS\\/TM imagery  

Microsoft Academic Search

The floodplain forests bordering the Amazon River have outstanding ecological, economic, and social importance for the region. However, the original distribution of these forests is not well known, since they have suffered severe degradation since the 16th century. The previously published vegetation map of the Amazon River floodplain (Hess et al., 2003), based on data acquired in 1996, shows enormous

Vivian F. Renó; Evlyn M. L. M. Novo; Chieno Suemitsu; Camilo D. Rennó; Thiago S. F. Silva

260

The {sup 18}O:{sup 16}O of dissolved oxygen in rivers and lakes in the Amazon Basin: Determining the ratio of respiration to photosynthesis rates in freshwaters  

SciTech Connect

The concentration and {sup 18}O:{sup 16}O ratio of dissolved oxygen were measured for 23 rivers and lakes of the Amazon Basin during 1988, 1990, and 1991. With only two exceptions, the rivers and lakes had dissolved oxygen concentrations that were at 20-90% of atmospheric saturation levels. The {delta}{sup 18}O of the dissolved oxygen ranged from 15 to 30% (vs. SMOW). The {delta}{sup 18}O for the lakes were the lowest at 15-23%. {delta}{sup 18}O < 24.2{per_thousand} (the atmospheric equilibrium value) are the result of photosynthetic oxygen input. The {delta}{sup 18}O of the rivers, in contrast, ranged from 24 to 30{per_thousand} > 24.2{per_thousand} resulted from respiration. Despite this clear difference between the {delta}{sup 18}O for rivers and lakes, these water bodies had similar levels of oxygen undersaturation. The {delta}{sup 18}O and dissolved oxygen concentrations are used to determine the ratio of community respiration (R) to gross photosynthesis (P) rates. R:P varied between {approximately}1 and 1.5 for lakes and between 1.5 and 4 for rivers. For all rivers and lakes, the measured {delta}{sup 18}O indicated the presence of photosynthetically produced oxygen, with the highest proportion occurring in lakes. The {delta}{sup 18}O of dissolved oxygen is a unique tracer of photosynthetic oxygen and provides, through a determination of R:P, a means of quantifying the heterotrophic state of freshwaters. 29 refs., 8 figs., 4 tabs.

Quay, P.D.; Wilbur, D.O.; Richey, J.E. [Univ. of Washington, Seattle, WA (United States)] [and others

1995-06-01

261

Methylmercury pollution in the Amazon, Brazil  

Microsoft Academic Search

In order to evaluate the extent of environmental mercury pollution due to goldmining activities in the Amazon, concentrations of total mercury and methylmercury were determined for human hair and fish samples from five fishing villages located mainly in the Tapajos river basin. Abnormally high levels of mercury were found in human hair from Jacareacanga and Brasilia Legal located near the

Hirokatsu Akagi; Olaf Malm; Yoshihide Kinjo; Masazumi Harada; Fernando J. P. Branches; Wolfgang C. Pfeiffer; Hiroo Kato

1995-01-01

262

THE BIOGEOCHEMISTRY OF THE AMAZON BASIN  

E-print Network

Ali-ferrasols, 62 alkalinity, 286 as a hydrological tracer, 253 allochthonous carbon, 253 alluminum Amazonian hydrologic cycle, 29 Amazon shelf, 14 carbon cycling, 345 nutrient trap behavior, 332 oxygen data black water rivers, 11, 188, 278 Bolivia, 323 Altiplano, 18 Bolivian high, 18 Brachiaria brizantha, 86

McClain, Michael

263

Prawn landings and their relationship with the extent of mangroves and shallow waters in western peninsular Malaysia  

NASA Astrophysics Data System (ADS)

This study investigated changes in landings of all prawns, white prawns (mainly Penaeus merguiensis), mangrove extent, rainfall and the area of shallow water in western peninsular Malaysia. The most important state for both the landings of all prawns and white prawns was Perak where about 50% of all prawns and 35% of white prawns were landed. This is also the state with the largest, and most stable, extent of mangrove forest reserve (40?000 ha) and the largest area of shallow water (<5 m deep). Juvenile prawns from Perak may contribute to the landings of the nearby, adjacent states of Penang and Selangor, where the second highest landings for white prawns and total prawns, respectively, were found. The area of shallow water accounted for the greatest proportion of variation in landings of both all prawns and white prawns, and was the most significant variable fitted to multiple regressions of landings and coastal attributes (area of shallow water, mangrove area, length of coastline). Although there was a significant linear relationship between the landings of total prawns and mangrove area in both the 1980s and 1990s, this was not the case for the mangrove-dependent white prawns where a significant relationship was found only for the 1990s. Furthermore, landings of all prawns and white prawns in Selangor and Johor, where large losses of mangrove forest reserve have been recorded, appear to have been maintained or increased in the 1990s. The lack of a clear relationship between mangrove loss and prawn landings may be due to the migration of prawns from adjacent areas or that other attributes of mangroves, such as the length of mangrove-water interface, may be more important for the growth and survival of prawn populations than total area of mangroves.

Loneragan, N. R.; Ahmad Adnan, N.; Connolly, R. M.; Manson, F. J.

2005-04-01

264

Meander Migration in the Amazon Basin  

NSDL National Science Digital Library

This activity is targeted at introductory to upper division undergraduate courses in geomorphology or Earth system science. Students view time series animation of satellite imagery of part of the Amazon River basin (Rio Ucayali) which is actively migrating. Students are asked to describe verbally and with sketches the changes in channel location and channel features over time. They then compare the very active section of the river with other rivers nearby to get a sense of overall activity of meandering streams. This is prelude to hypothesis development and testing: why is the Rio Ucayali so active? Students explore some potential causes to explain the cause of lateral mobility of this river.

Hasbargen, Les

265

Biology of penaeid prawns in the Suez Canal lakes  

Microsoft Academic Search

A study was made from January 1988 to March 1989 of the penaid prawns in the Great Bitter Lake and Lake Timsah located in the central part of the Suez Canal. Two species of Red Sea origin were investigated,Metapenaeus stebbingi andTrachypenaeus curvirostris; the former is by far the commoner. Both species displayed seasonal breeding over the period April to October,

A. A.-F. A. Gab-Alla; R. G. Hartnoll; A.-F. Ghobashy; S. Z. Mohammed

1990-01-01

266

Responses of freshwater prawn, Macrobrachium rosenbergii , to chemical attractants  

Microsoft Academic Search

Chemoreception in the adults of the freshwater prawnMacrobrachium rosenbergii was investigated under controlled laboratory conditions, using behavioral assays. Tests were carried out on groups, as well as on individuals, all at their intermolt stages of the molt cycle, and prestarved for three to four days. Of 28 different substances tested, the amino acids taurine, glycine, arginine, and betaine, as well

Sheenan Harpaz; David Kahan; Rachel Galun; Itzhak Moore

1987-01-01

267

Uranium in river water  

Microsoft Academic Search

The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains

M. R. Palmer; J. M. Edmond

1993-01-01

268

Stable isotope and trace metal compositions of Australian prawns as a guide to authenticity and wholesomeness.  

PubMed

This research has explored the potential of stable isotope and trace metal profiles to distinguish Australian prawns from prawns imported from neighbouring Asian countries. Australian prawns were collected mostly from the Brisbane area. Strong differences in Australian vs. imported prawns were evident from both the isotope and trace element data, with the differences most likely occurring because imported prawns are typically reared in aquaculture facilities and frozen prior to sale in Australia. The aquaculture origins are characterised by comparatively; low ?HVSMOW, ?(13)CVPDB values, low concentrations of arsenic, zinc and potassium, and high water contents (>80%). Relatively high arsenic and cadmium contents were found within Australian prawns, but the concentrations did not exceed local human health guidelines. PMID:25306341

Carter, J F; Tinggi, U; Yang, X; Fry, B

2015-03-01

269

Volatile components associated with bacterial spoilage of tropical prawns.  

PubMed

Analysis of headspace volatiles by gas chromatography/mass spectrometry from king (Penaeus plebejus), banana (P. merguiensis), tiger (P. esculentus/semisulcatus) and greasy (Metapenaeus bennettae) prawns stored in ice or ice slurry, which is effectively an environment of low oxygen tension, indicated the presence of amines at the early stages of storage (less than 8 days) irrespective of the nature of the storage media. Esters were more prevalent in prawns stored on ice (normal oxygen conditions) at the latter stages of storage (more than 8 days) and were only produced by Pseudomonas fragi, whereas sulphides and amines occurred whether the predominant spoilage organism was Ps. fragi or Shewanella putrefaciens. The free amino acid profiles of banana and king prawns were high in arginine (12-14%) and low in cysteine (0.1-0.17%) and methionine (0.1-0.2%). Filter sterilised raw banana prawn broth inoculated with a total of 15 cultures of Ps. fragi and S. putrefaciens and incubated for two weeks at 5 degrees C, showed the presence of 17 major compounds in the headspace volatiles analysed using gas chromatography/mass spectrometry (GC/MS). These were mainly amines, sulphides, ketones and esters. Principal Component Analysis of the results for the comparative levels of the volatiles produced by pure cultures, inoculated into sterile prawn broth, indicated three subgroupings of the organisms; I, Ps. fragi from a particular geographic location; II, S. putrefaciens from another geographic location; and III, a mixture of Ps. fragi and S. putrefaciens from different geographic locations. The sensory impression created by the cultures was strongly related to the chemical profile as determined by GC/MS. Organisms, even within the same subgrouping classified as identical by the usual tests, produced a different range of volatiles in the same uniform substrate. PMID:9706797

Chinivasagam, H N; Bremner, H A; Wood, A F; Nottingham, S M

1998-06-30

270

The Changing Nature of Amazon Drought  

NASA Astrophysics Data System (ADS)

While the Amazon river basin plays a critical role in global hydrologic cycle, coupled climate model simulations project that this enormous river basin, including its dense rain forest, will be converted to savanna. In recent years, notably in 2005 and in 2010, record breaking 'once-in-a-century' drought, struck the basin. However, the causes and impacts of the drought are still controversial, because the observed climatic phenomena and the responses of the terrestrial ecosystem are inconsistent with our current understanding. This study suggests that a recently recognized variation of El-Niño, the CP-type El-Niño, which has a peak temperature anomaly in the Central Pacific and induces anomalously warm northern Atlantic sea surface temperature (SST), is a key driver of the recent droughts. Our results demonstrate how the transition of such large-scale climatic patterns affects terrestrial hydrological cycles in the Amazon basin. We propose that the recent severe Amazon droughts were caused by Central Pacific warm pool, and by superimposed feedback from the CP-El-Niño-induced north Atlantic warm pool. If the frequency and intensity of the CP type El-Niño continue to increase as projected by climate change simulations, then Amazon River basin may well suffer more severe and frequent drought in the future.

Kim, H.; Kim, S.; Famiglietti, J. S.; Yu, J.

2011-12-01

271

Effect of cadmium on the ovarian development in the freshwater prawn Macrobrachium rosenbergii (De Man)  

Microsoft Academic Search

In this investigation, effect of cadmium chloride (25?g\\/l) on oogenesis of freshwater prawn, Macrobrachium rosenbergii was studied. In vivo experiments were performed with both intact and eyestalk ablated prawns. The intact, cadmium-exposed prawns exhibited decrease in Gonado Somatic Index (GSI) and ovarian development compared to controls. Whereas, ablated treated ovary showed reduction of yolk material and oocyte membrane thickness at

Peranandam Revathi; Lourduraj Arockia Vasanthi; Natesan Munuswamy

2011-01-01

272

NASA Earth Observatory: Escape from the Amazon  

NSDL National Science Digital Library

As part of NASA's Earth Observatory, visitors to the Escape from the Amazon Web site are invited to "Accompany NASA scientists as they explore our world and unravel the mysteries of climate and environmental change." The Escape from the Amazon feature focuses on the buildup of carbon dioxide and its effect on global climate change, and the role that forests play in reversing this trend. Also included as the second part of the feature is an introduction to the large-scale Biosphere-Atmosphere Experiment in Amazonia. This feature highlights the enormity and significance of the Amazon River Valley and its effect on global climate. This Web site is a great outreach and educational tool offered by NASA and should be interesting to lay readers, scientists, and teachers. Several great graphics help to illustrate the information provided.

Lindsey, Rebecca.; Simmon, Robert.

273

Expedition to Peruvian Andes Confirms the Source of the Amazon  

NSDL National Science Digital Library

A US-led, National Geographic Society expedition says it has confirmed the location for the exact source of the Amazon River. The source lies on a 5,597 meter high peak called Nevado Mismi in the Peruvian Andes. The National Geographic team had established Mismi as the river's source in 1971, but in recent years the possibility had been raised that the actual source was at another mountain. Pinpointing the Amazon's source was made possible through use of modern geographic information systems. This week's In the News investigates the geography and conservation issues of the mighty river and its basin.

Sanders, Hilary C.

2000-01-01

274

Variations of the sea level in the Amazon Estuary  

Microsoft Academic Search

We analyze the Geosat altimeter data off the mouth of the Amazon river. Variations of the sea level of up to 6 m are observed, which are correlated with bathymetry, and dominated by a complex tidal pattern. M2, N2 and O1 altimetric cotidal maps are constructed. Their amplitudes decrease strongly off the river mouth, probably by dissipation in the estuary.

J.-F. Minster; M.-L. Genco; C. Brossier

1995-01-01

275

Nouveautés sur les débits monstrueux de l'Amazone  

Microsoft Academic Search

After a first study about seasonal variations of the Amazon river, Maurice Pardé (1954) proposed Po hydrologic community, the value of 100000 to 110000 m3\\/s as the mean discharge of that giant river who drains a basin of more than 6000000 kmz. This result, which someone thaught excessive, was founded according Paul LeCointe observations and from a rudimentary water budget

Jean Loup GUYOT; Michel MOLINIER; Valdemar GUIMARAES; Eurides de OLIVEIRA

276

Hydrology and climate in the southwestern Amazon basin (Bolivia)  

Microsoft Academic Search

The variability of the runoff of the Bolivian tributaries of the Madeira River, the greatest southern affluent of the Amazon R., is of major importance for the riparian people safety and for the economic development of the region. We investigated whether the discharge of these rivers is predictable or not, using the Sea Surface Temperatures Anomalies (SSTAs) in the Equatorial

J. Ronchail; L. Bourrel; L. Maurice-Bourgoin; P. Vauchel; G. Cochonneau; J. L. Guyot; L. Phillips; A. Castro

2003-01-01

277

Bacterial Flora of Freshwater Prawn, Macrobrachium rosenbergii(de Man), Cultured in Concrete Tanks in Saudi Arabia  

Microsoft Academic Search

Bacterial counts and the aerobic heterotrophic bacterial flora in the digestive tract of the freshwater prawn, Macrobrachium rosenbergii, in Saudi Arabia were investigated, and the isolates were identified to the species level. Physicochemical characteristics, bacterial counts, and bacterial flora of freshwater prawn culture tank water, tank sediment, and freshwater prawn carapace were also investigated. Total viable bacterial counts ranged from

Ahmed H. Al-Harbi

2003-01-01

278

The impact of global positioning systems and plotters on fishing power in the northern prawn fishery, Australia  

Microsoft Academic Search

The impact of global positioning systems (GPS) and plotter systems on the relative fishing power of the northern prawn fishery fleet on tiger prawns (Penaeus esculentus Haswell, 1879, and P. semisulcatus de Haan, 1850) was investigated from commercial catch data. A generalized linear model was used to account for differences in fishing power between boats and changes in prawn abundance.

Carolyn M. Robins; You-Gan Wang; David Die

1998-01-01

279

Effect of Sodium Metabisulphite and Storage Temperature on the Survival of Vibrio cholerae on Prawns ( Penaeus monodon )  

Microsoft Academic Search

Sodium metabisulphite is traditionally used to control a non-microbiological spoilage symptom of prawns known as blackspot. This study was undertaken to evaluate the effect of sodium metabisulphite, at levels currently used to control blackspot, on the survival of V. cholerae on prawns during simulated commercial storage. Fresh prawns (Penaeus monodon) were divided into two batches, one of which was exposed

F. E. S. Januário; G. A. Dykes

2005-01-01

280

Fluid-mud processes on the Amazon continental shelf  

Microsoft Academic Search

A sediment transport study conducted on the Amazon continental shelf as part of AmasSeds (A Multi-disciplinary Amazon Shelf SEDiment Study) revealed extensive regions of dense nearbed suspensions of sediment, known as fluid mud (suspended-sediment concentration > 10 g1?1 ). Fluid mud was found near the river mouth on the inner- and middle-shelf, in the region of the bottom salinity front,

G. C. Kineke; R. W. Sternberg; J. H. Trowbridge; W. R. Geyer

1996-01-01

281

TITLE: Seasonal and spatial variability of CO2 emission from a large floodplain lake in the lower Amazon  

E-print Network

Amazon River inflows. CO2 concentration was reduced in regions with phytoplankton blooms. The range of CO of dissolved CO2 concentration and gas evasion in a large floodplain lake in the lower reach of the Amazon River in four hydrological phases. We calculated surficial CO2 concentrations from measurements of p

California at Santa Barbara, University of

282

A Bayesian analysis of NSW eastern king prawn stocks ( Melicertus plebejus) using multiple model structures  

Microsoft Academic Search

The eastern king prawn (Melicertus plebejus) is a valuable target species for commercial fisheries operating on the Australian east coast. The Bayesian analysis presented here aims to determine the current state and productivity of the NSW component of the eastern king prawn stock and analyse the possible consequences of altering commercial catches in the future. The Bayesian approach is well

Matthew C. Ives; James P. Scandol

2007-01-01

283

Observations on the behavior of the malaysian prawn, macrobrachium rosenbergii (de man), to artificial habitats  

Microsoft Academic Search

Six studies examined the spatial and temporal behavior of juvenile Macrobrachium rosenbergii prawns to a variety of habitat configurations and materials. Of the configurations tested, a layered habitat design was preferred. A significant (P < 0.001) preference for edge or perimeter areas of solid layer habitat units was displayed by the prawns. However, modification of the layers to consist of

Theodore I. J. Smith; Paul A. Sandifer

1979-01-01

284

??????????????????????????????????????????????????????????????????????????? Response to within-family selection on growth rate of freshwater prawn Macrobrachium rosenbergii de Man  

Microsoft Academic Search

Selective breeding program to improve growth rate of giant freshwater prawn Macrobrachium rosenbergii has been carried out at the National Aquaculture Genetics Research Institute during 1998 to 2000. Within-family selection procedure was applied on growth rate of culture prawns. The experiment consisted of two lines including a high growth selected line and a control line. The selection responses were estimated

Supattra Uraiwan; Surang Sumanojitraporn; Siriporn Jeenmauk

285

Nursing of Giant Freshwater Prawn (Macrobrachium rosenbergii) Postlarvae in Ponds with Different Stocking Densities  

Microsoft Academic Search

Study on the effects of different stocking densities on growth, survival rate and economic return of prawns from postlarvae to juvenile stage in ponds was conducted in Tam Binh district, Vinh Long province. Experiment was designed with two treatments of 50 and 100 PL\\/m2 and lasted for 45 days. During the experiment, prawns were fed commercial diet of 33 %

Nguyen Thanh Phuong; Ly Van Khanh; Marcy N. Wilder

286

The use of customised probiotics in the cultivation of western king prawns (Penaeus latisulcatus Kishinouye, 1896).  

PubMed

This study presents a comprehensive review of probiotics usage in aquaculture with a specific emphasis on our research series on the effectiveness of the customised probiotics, Pseudomonas synxantha and Pseudomonas aeruginosa on the cultivation of western king prawns, Penaeus latisulcatus. These customised probiotics resulted from tests using five inhibition test methods between the bacteria isolated from two commercial probiotic products and Vibrio spp. isolated from western king prawns and other aquatic animals. The results proved the suitability and safety of these probiotics in the cultivation of western king prawns as they conclusively met all the essential requirements for appropriate probiotics. These probiotics have shown similar beneficial effects as the common prebiotics, Bio-Mos and beta-1,3-d-glucan on the growth, survival and immune responses of the prawns. The supplementation of probiotics with the formulated feed was more efficacious and more practical than direct application into the rearing media. The prawns exposed to the combined probiotics were healthier than those exposed to the individual probiotics. P. aeruginosa was more effective for improving prawn health than P. synxantha. The probiotic-fed prawns were not influenced by Vibrio harveyi at 10(3) CFU ml(-1) for 36 h of challenge. In conclusion, these customised probiotics can be used as appropriate probiotics and as a suitable replacement of antibiotics, for disease control in western king prawn aquaculture. PMID:19463955

Van Hai, Ngo; Buller, Nicky; Fotedar, Ravi

2009-08-01

287

In: Biology, Evolution and Conservation of River Dolphins... ISBN 978-60876-633-8 Editors: Manuel Ruiz-Garcia and Joseph Shostell 2010 Nova Science Publishers, Inc.  

E-print Network

as in the Amazon River basin (Figure 1). Marine Sotalia are found from Honduras to the state of Santa Catarina and Colombia) and "lam" (Nicaragua). The distribution of riverine Sotalia comprises most of the Amazon River

Solé-Cava, Antonio M.

288

The JERS Amazon Multi-Season Mapping Study (JAMMS): Observation Strategies and Data Characteristics  

NASA Technical Reports Server (NTRS)

The JERS-1 Amazon Multi-season Mapping Study (JAMMS), part of the Global Rain Forest Mapping (GRFM) project led by the National Space Development Agency of Japan (NASDA), had an ambitious agenda to completely map the Amazon River floodpain (and surrounding areas) twice at high resolution.

Chapman, B.; Freeman, A.; Siqueira, P.

2000-01-01

289

Carbon isotopic composition of Amazon shelf sediments  

SciTech Connect

The distribution of carbon isotopes in Amazon shelf sediment is controlled by the same processes that are forming the modern subaqueous delta. The terrestrial (-27 to -25 per thousand) isotopic carbon signal observed in surficial sediments near the river mouth extends over 400 km northwest along the shelf. Terrestrial carbon is associated with areas of rapid sediment accumulation (topset and foreset regions). A sharp boundary between terrestrial (-27 to -25 per thousand) and marine (-23 to -22 per thousand) isotopic carbon values in surficial sediments is associated with a change in depositional conditions (foreset to bottomset regions) and a decrease in sediment accumulation rate. POC water-column isotopic values (-27 per thousand) near the river mouth are similar to the underlying surficial-sediment TOC isotopic values, but POC water-column samples collected 20 km off the river mouth have marine carbon isotopic values (-22 to -19 per thousand) and differ from the underlying surficial-sediment TOC isotopic values. These water column observations are related to variations in turbidity and productivity. Down-core isotopic variation is only observed in cores taken in areas of lower sediment accumulation rates. These observations indicate that the organic carbon in Amazon shelf sediment is dominantly terrestrial in composition, and the location of deposition of this carbon is controlled by modern processes of sediment accumulation. The modern Amazon shelf is similar to large clinoform shale deposits of the Cretaceous in North America. Thus, the stratigraphic setting may help predict the isotopic variations of carbon in ancient deposits.

Showers, W.J.; Angle, D.G.; Nittrouer, C.A.; Demaster, D.J.

1985-02-01

290

Mercury and flooding cycles in the Tapajós River basin, Brazilian Amazon: the role of periphyton of a floating macrophyte (Paspalum repens).  

PubMed

Methylmercury (MeHg) increases mercury (Hg) toxicity and is biomagnified in the trophic chain contaminating riverine Amazon populations. Freshwater macrophyte roots are a main site of Hg methylation in different Brazilian environments. Paspalum repens periphyton was sampled in four floodplain lakes during the dry, rainy and wet seasons for measurement of total Hg (THg), MeHg, Hg methylation potentials, %C, %N, ?(13)C, ?(15)N and bacterial heterotrophic production as (3)H-leucine incorporation rate. THg concentration varied from 67 to 198 ng/g and the potential of Me(203)Hg formation was expressive (1-23%) showing that periphyton is an important matrix both in the accumulation of Hg and in MeHg production. The concentration of MeHg varied from 1 to 6 ng/g DW and was positively correlated with Me(203)Hg formation. Though methylmercury formation is mainly a bacterial process, no significant correlation was observed between the methylation potentials and bacterial production. The multiple regressions analyses suggested a negative correlation between THg and %C and %N and between methylation potential and ?(13)C. The discriminant analysis showed a significant difference in periphyton ?(15)N, ?(13)C and THg between seasons, where the rainy season presented higher ?(15)N and the wet period lighter ?(13)C, lower THg values and higher Me(203)Hg formation. This exploratory study indicates that the flooding cycle could influence the periphyton composition, mercury accumulation and methylmercury production. PMID:21536317

Coelho-Souza, Sérgio A; Guimarães, Jean R D; Miranda, Márcio R; Poirier, Hugo; Mauro, Jane B N; Lucotte, Marc; Mergler, Donna

2011-06-15

291

Buy at Amazon Buy at Amazon  

E-print Network

and incitement CHAPTER 8 Formation of the theory of the selfish gene ­ Darwin, watch out ­ someone is after your, Mr. Darwin Farewell to selfish gene Prague 2008 Charles University in Prague, Faculty of Science Buy at Amazon #12;Flegr Jaroslav Frozen Evolution. Or, that's not the way it is, Mr. Darwin ­ Farewell

Flegr, Jaroslav

292

Metal accumulation in the greentail prawn, Metapenaeus bennettae, in Sydney and Port Hacking estuaries, Australia.  

PubMed

Metal concentrations of the inshore greentail prawn, Metapenaeus bennettae, and surface sediments from locations within Sydney estuary and Port Hacking (Australia) were assessed for bioaccumulation and contamination. The current study aimed to assess metal concentrations in prawn tissue (tail muscle, exoskeleton, hepatopancreas and gills), relate whole body prawn tissue metal concentrations to sediment metal concentrations and animal size, as well as assess prawn consumption as a risk to human health. Metal concentrations were highest in sediment and prawns from contaminated locations (Iron Cove, Hen and Chicken Bay and Lane Cove) in Sydney estuary compared with the reference estuary (Port Hacking). Concentrations in sediments varied considerably between sites and between metals (As, Cd, Cr, Cu, Ni, Pb and Zn), and although concentrations exceeded Interim Sediment Quality Guideline-Low values, metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were below Australian National Health and Medical Research Council human consumption guidelines in prawn tail muscle tissue. Metal concentrations in prawn tail muscle tissue were significantly different (p???0.05) amongst locations for Pb, Zn and Cd, and metal concentrations were generally highest in gills tissue, followed by the hepatopancreas, exoskeleton and tail muscle. The exoskeleton contained the highest Sr concentration; the hepatopancreas contained the highest As, Cu and Mo concentrations; and the gills contained the highest Al, Cr, Fe and Pb concentrations. Concentrations of Pb, As and Sr were significantly different (p???0.05) between size groups amongst locations. PMID:23852467

Lewtas, K L M; Birch, G F; Foster-Thorpe, C

2014-01-01

293

Radiocarbon and stable isotope geochemistry of organic matter in the Amazon headwaters, Peruvian Andes  

Microsoft Academic Search

We used ?13C, ?15N, and ?14C to determine the sources of riverine organic matter in the Pozuzo River, a tributary of the Pachitea River located in the mountainous headwaters of the Amazon. Particulate organic matter (POM) ?14C decreased downstream, suggesting that young organic matter (OM) introduced in small headwaters is respired preferentially in rivers or is diluted downstream with older

Amy Townsend-Small; Jorge L. Noguera; Michael E. McClain; Jay A. Brandes

2007-01-01

294

White Tail Disease of Freshwater Prawn, Macrobrachium rosenbergii.  

PubMed

Macrobrachium rosenbergii is the most important cultured freshwater prawn in the world and it is now farmed on a large scale in many countries. Generally, freshwater prawn is considered to be tolerant to diseases but a disease of viral origin is responsible for severe mortalities in larval, post-larval and juvenile stages of prawn. This viral infection namely white tail disease (WTD) was reported in the island of Guadeloupe in 1995 and later in Martinique (FrenchWest Indies) in Taiwan, the People's Republic of China, India, Thailand, Australia and Malaysia. Two viruses, Macrobrachium rosenbergii nodavirus (MrNV) and extra small virus-like particle (XSV) have been identified as causative agents of WTD. MrNV is a small icosahedral non-enveloped particle, 26-27 nm in diameter, identified in the cytoplasm of connective cells. XSV is also an icosahedral virus and 15 nm in diameter. Clinical signs observed in the infected animals include lethargy, opaqueness of the abdominal muscle, degeneration of the telson and uropods, and up to 100 % within 4 days. The available diagnostic methods to detect WTD include RT-PCR, dot-blot hybridization, in situ hybridization and ELISA. In experimental infection, these viruses caused 100 % mortality in post-larvae but failed to cause mortality in adult prawns. The reported hosts for these viruses include marine shrimp, Artemia and aquatic insects. Experiments were carried out to determine the possibility of vertical transmission of MrNV and XSV in M. rosenbergii. The results indicate that WTD may be transferred from infected brooders to their offspring during spawning. Replication of MrNV and XSV was investigated in apparently healthy C6/36 Aedes albopictus and SSN-1 cell lines. The results revealed that C6/36 and SSN-1cells were susceptible to these viruses. No work has been carried out on control and prevention of WTD and dsRNA against protein B2 produced RNAi that was able to functionally prevent and reduce mortality in WTD-infected redclaw crayfish. PMID:23997437

Sahul Hameed, A S; Bonami, Jean-Robert

2012-09-01

295

Rivers  

NSDL National Science Digital Library

This video segment from IdahoPTV's D4K takes you on a trip down Idaho's Snake River near 1000 Springs and Blur Heart Springs while it explains how rivers are formed, their uses, and how they make valleys, canyons and even plains.

Ptv, Idaho

2011-09-04

296

Kinetic analysis of gill (Na?,K?)-ATPase activity in selected ontogenetic stages of the Amazon River shrimp, Macrobrachium amazonicum (Decapoda, Palaemonidae): interactions at ATP- and cation-binding sites.  

PubMed

We investigated modulation by ATP, Mg²?, Na?, K? and NH?? and inhibition by ouabain of (Na?,K?)-ATPase activity in microsomal homogenates of whole zoeae I and decapodid III (formerly zoea IX) and whole-body and gill homogenates of juvenile and adult Amazon River shrimps, Macrobrachium amazonicum. (Na?,K?)-ATPase-specific activity was increased twofold in decapodid III compared to zoea I, juveniles and adults, suggesting an important role in this ontogenetic stage. The apparent affinity for ATP (K(M) = 0.09 ± 0.01 mmol L?¹) of the decapodid III (Na?,K?)-ATPase, about twofold greater than the other stages, further highlights this relevance. Modulation of (Na?,K?-ATPase activity by K? also revealed a threefold greater affinity for K? (K?.? = 0.91 ± 0.04 mmol L?¹) in decapodid III than in other stages; NH?? had no modulatory effect. The affinity for Na? (K?.? = 13.2 ± 0.6 mmol L?¹) of zoea I (Na?,K?)-ATPase was fourfold less than other stages. Modulation by Na?, Mg²? and NH?? obeyed cooperative kinetics, while K? modulation exhibited Michaelis-Menten behavior. Rates of maximal Mg²? stimulation of ouabain-insensitive ATPase activity differed in each ontogenetic stage, suggesting that Mg²?-stimulated ATPases other than (Na?,K?)-ATPase are present. Ouabain inhibition suggests that, among the various ATPase activities present in the different stages, Na?-ATPase may be involved in the ontogeny of osmoregulation in larval M. amazonicum. The NH??-stimulated, ouabain-insensitive ATPase activity seen in zoea I and decapodid III may reflect a stage-specific means of ammonia excretion since functional gills are absent in the early larval stages. PMID:22544049

Leone, Francisco Assis; Masui, Douglas Chodi; de Souza Bezerra, Thais Milena; Garçon, Daniela Pereira; Valenti, Wagner Cotroni; Augusto, Alessandra Silva; McNamara, John Campbell

2012-04-01

297

Nitrogen dynamics in seasonally flooded soils in the Amazon floodplain  

Microsoft Academic Search

Large areas of the Amazon are subject to seasonal flooding due to water level changes of the river. This ‘flood pulse’ causes rapidly changing conditions for microorganisms living in the soils which affects the cycling of nitrogen in the ecosystem. An understanding of the nitrogen dynamics in the seasonally flooded soils is essential for the development of productive and sustainable

Matthias Koschorreck; Assad Darwich

2003-01-01

298

The riverine silicon isotope composition of the Amazon Basin  

NASA Astrophysics Data System (ADS)

We present here the first large-scale study of riverine silicon isotope signatures in the Amazon Basin. The Amazon and five of its main tributaries were studied at different seasons of the annual hydrological cycle. The ?30Si signature of the dissolved silicon (DSi) exported to the estuary (weighted for DSi flux) for the period considered is estimated at +0.92‰. A river cross-section shows the homogeneity of the Amazon River regarding DSi concentration and isotope ratio. The biogenic silica (BSi) concentration measured in surface water from all rivers is generally small compared to the DSi reservoir but large variations exist between rivers. Very low isotope signatures were measured in the upper Rio Negro (?30Si = +0.05 ± 0.06‰), which we explain both by an equilibrium between clay formation and dissolution and by gibbsite formation. The Si isotope fractionation in the Andean tributaries and the Amazon main stem can be explained by clay formation and follow either a Rayleigh or a batch equilibrium fractionation model. Our results also suggest that the formation of 2:1 clays induces a fractionation factor similar to that of kaolinite formation.

Hughes, H. J.; Sondag, F.; Santos, R. V.; André, L.; Cardinal, D.

2013-11-01

299

Fluid-mud processes on the Amazon continental shelf  

NASA Astrophysics Data System (ADS)

A sediment transport study conducted on the Amazon continental shelf as part of AmasSeds (A Multi-disciplinary Amazon Shelf SEDiment Study) revealed extensive regions of dense nearbed suspensions of sediment, known as fluid mud (suspended-sediment concentration > 10 g1 -1 ). Fluid mud was found near the river mouth on the inner- and middle-shelf, in the region of the bottom salinity front, and was most extensive during periods of rising and high river discharge. Fluid mud, up to 7.25 m thick, but generally 1-2 m thick, appears to form by processes similar to those occurring at an estuarine turbidity maximum, i.e. enhanced settling and lateral convergence of near-bottom flows. A modeling study showed that vertical mixing was controlled by the suppression of turbulence, due to the stratification induced by suspended sediment, and established an upper bound for the total amount of suspended sediment that may be carried in suspension. Sediment leaving the Amazon River appears to go through cycles of trapping and resuspension at the river mouth, before being partially advected seaward and alongshelf, where it is largely incorporated into fluid mud along the bottom salinity front. The fluid muds have far-reaching effects on the Amazon shelf system by reducing boundary shear stresses, affecting water-column seabed exchange, and serving as the agent of outward growth of the subaqueous delta through episodic offshore transport.

Kineke, G. C.; Sternberg, R. W.; Trowbridge, J. H.; Geyer, W. R.

1996-04-01

300

Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes-Amazon connectivity.  

PubMed

Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts. This lack of strategic planning is particularly problematic given the intimate link between the Andes and Amazonian flood plain, together one of the most species rich zones on Earth. We examined the potential ecological impacts, in terms of river connectivity and forest loss, of the planned proliferation of hydroelectric dams across all Andean tributaries of the Amazon River. Considering data on the full portfolios of existing and planned dams, along with data on roads and transmission line systems, we developed a new conceptual framework to estimate the relative impacts of all planned dams. There are plans for 151 new dams greater than 2 MW over the next 20 years, more than a 300% increase. These dams would include five of the six major Andean tributaries of the Amazon. Our ecological impact analysis classified 47% of the potential new dams as high impact and just 19% as low impact. Sixty percent of the dams would cause the first major break in connectivity between protected Andean headwaters and the lowland Amazon. More than 80% would drive deforestation due to new roads, transmission lines, or inundation. We conclude with a discussion of three major policy implications of these findings. 1) There is a critical need for further strategic regional and basin scale evaluation of dams. 2) There is an urgent need for a strategic plan to maintain Andes-Amazon connectivity. 3) Reconsideration of hydropower as a low-impact energy source in the Neotropics. PMID:22529979

Finer, Matt; Jenkins, Clinton N

2012-01-01

301

Ingestion and absorption of nutrients by the freshwater prawn (Macrobrachium rosengergii)  

E-print Network

INGESTION AND ABSORPTION OF NUTRIENTS BY THE FRESHWATER PRAWN (MACROBRACHIUM ROSENBERGII) A Thesis by SUCHAT TAECHANURUK Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OP SCIENCE May 1982 Major Subject: Wildlife and Fisheries Sciences INGESTION AND ABSORPTION OF NUTRIENTS BY THE FRESHWATER PRAWN (MACROBRACHIUM ROSENBERGII) A Thesis by SUCHAT TAECHANURUK Approved as to style and content by: (Chairman...

Taechanuruk, Suchat

2012-06-07

302

Antimicrobial activity of chitosan against vibrios from freshwater prawn Macrobrachium rosenbergii larval rearing systems.  

PubMed

Chitosan is a biocompatible and biodegradable natural polymer with established antimicrobial properties against specific microorganisms. The present study demonstrates its antibacterial activity against 48 isolates of Vibrio species from prawn larval rearing systems. The antibacterial activity had a positive correlation with the concentration of chitosan. This work opens up avenues for using chitosan as a prophylactic biopolymer for protecting prawn larvae from vibriosis. PMID:16385825

Anas, A; Paul, S; Jayaprakash, N S; Philip, R; Bright Singh, I S

2005-11-01

303

Development of cell culture system from the giant freshwater prawn Macrobrachium rosenbergii (de Man)  

Microsoft Academic Search

A new cell culture system (MRH) was developed for the first time from 2 months old freshwater prawn, Macrobrachium rosenbergii. Primary cultures were developed from heart tissues by explant culture technique. Cell outgrowth was obtained from the heart\\u000a explant after 14 days of explant culture. The culture medium used was Leibovitz-15 supplemented with 20% Fetal Bovine Serum\\u000a along with 1% prawn hemolymph

Mukunda Goswami; Wazir S. Lakra; T. Rajaswaminathan; Gourav Rathore

2010-01-01

304

The ecdysteroid titer in the female prawn, Macrobrachium rosenbergii during the molt cycle  

E-print Network

HPI C resolution of ecdysone and 20-hydroxyecdysone from prawn 823. HPLC resolution of ecdysone and 20-hydroxyecdysone from prawn PZ4. 40 43 44 INTRODUCTION Molting in crustaceans results from tissue response to high circula- ting ti ters of a... the silkworm ~Bomb x mori (Butenandt and Karlson, 1954) and its subsequent structure determination (Huber and Hoppe, 1965), other arthropod ecdysteroids have been isolated and identified: 20-hydroxyecdysone (crustecdysone, ecdysterone, a-ecdysone) (Hampshire...

Newitt, Richard Allen

2012-06-07

305

Improvement of red color development on the surface of kuruma prawn Marsupenaeus japonicus under various conditions.  

PubMed

The degree of red color development on the surface of prawns by cooking is an important index for food quality. In this study, we tested several factors that are thought to influence the red color development to identify possible correlations with various conditions. Live kuruma prawns, Marsupenaeus japonicus, (15.4 cm, 25.2 g on average) were used in this study. In case of cooking at 100 °C for 1 min after 24 h of storage at 0 °C, 5 °C, and 20 °C, the red color development rate of prawns stored at 5 °C and 20 °C was significantly lower than that of prawns cooked just after killing. In case of cooking at 100 °C, 80 °C, and 60 °C after storage for 24 h at 0 °C, there was no color development at 60 °C and significantly less color development at 80 °C compared to cooking just after killing. Preparation using 1% sodium carbonate before cooking at 80 °C could compensate for the lack of red color development. Short exposure of live kuruma prawns to low-oxygen conditions had no influence on the color development, but putting the prawns in freshwater for 3 h significantly reduced the red color development rate. In conclusion, the storage time has little influence on the red color development when the cooking temperature is sufficiently high. However, in case a large amount of prawns is cooked followed by lowering the cooking temperature and/or prawns are exposed to serious stresses before cooking, an alkaline preparation could compensate for the lack of red color development. PMID:24456388

Ando, Masashi; Fukai, Takamitsu; Kawasaki, Ken-Ichi; Itoh, Tomohiro; Tsukamasa, Yasuyuki

2014-02-01

306

Challenges and Opportunities for Co-Management of a Migratory Fish (Prochilodus nigricans) in the Peruvian Amazon  

Microsoft Academic Search

Fisheries co-management lies at the center of environmental, social, and economic issues in the lower Pastaza River basin in the Peruvian Amazon. In this remote region, the intermingling of black and white water systems creates unique aquatic habi- tats that harbor diverse assemblages of fishes, including Prochilodus nigricans, a migratory species of high ecological and socioeconomic importance throughout the Amazon.

Mariana Montoya

307

Lost in the Amazon  

NSDL National Science Digital Library

The Lost in the Amazon curricular unit is a series of minds-on and hands-on engineering activities based on an adventure scenario set in the Amazon rainforest in Brazil. Students imagine themselves to be a team of EnviroTech engineers returning to the U.S. from a conference in Brasilia, Brazil. When their plane crashes deep in the Amazon forest, they work in groups to overcome various obstacles in their quest to survive and reach the nearest city as quickly and safely as possible. Motivated by this adventurous theme, students discover, learn and apply the following: 1) classification of plants and insects; 2) general categorizing skills; 3) process skills: problem solving and critical thinking; 4) scientific testing and experimentation; 5) materials properties.

Adventure Engineering

308

The Amazon and climate  

NASA Technical Reports Server (NTRS)

The climatologies of cloudiness and precipitation for the Amazon, are reviewed and the physical causes of some of the observed features and those which are not well known are explained. The atmospheric circulation over the Amazon is discussed on the large scale tropical circulations forced by deep diabatic heating sources. Weather deforestation which leads to a reduction in evapotranspiration into the atmosphere, and a reduction in precipitation and its implicated for the gobal climate is discussed. It is indicated that a large scale clearing of tropical rainforests there would be a reduction in rainfall which would have global effects on climate and weather both in the tropical and extratropical regions.

Nobre, C. A.

1984-01-01

309

In-depth tanscriptomic analysis on giant freshwater prawns.  

PubMed

Gene discovery in the Malaysian giant freshwater prawn (Macrobrachium rosenbergii) has been limited to small scale data collection, despite great interest in various research fields related to the commercial significance of this species. Next generation sequencing technologies that have been developed recently and enabled whole transcriptome sequencing (RNA-seq), have allowed generation of large scale functional genomics data sets in a shorter time than was previously possible. Using this technology, transcriptome sequencing of three tissue types: hepatopancreas, gill and muscle, has been undertaken to generate functional genomics data for M. rosenbergii at a massive scale. De novo assembly of 75-bp paired end Ilumina reads has generated 102,230 unigenes. Sequence homology search and in silico prediction have identified known and novel protein coding candidate genes (?24%), non-coding RNA, and repetitive elements in the transcriptome. Potential markers consisting of simple sequence repeats associated with known protein coding genes have been successfully identified. Using KEGG pathway enrichment, differentially expressed genes in different tissues were systematically represented. The functions of gill and hepatopancreas in the context of neuroactive regulation, metabolism, reproduction, environmental stress and disease responses are described and support relevant experimental studies conducted previously in M. rosenbergii and other crustaceans. This large scale gene discovery represents the most extensive transcriptome data for freshwater prawn. Comparison with model organisms has paved the path to address the possible conserved biological entities shared between vertebrates and crustaceans. The functional genomics resources generated from this study provide the basis for constructing hypotheses for future molecular research in the freshwater shrimp. PMID:23734171

Mohd-Shamsudin, Maizatul Izzah; Kang, Yi; Lili, Zhao; Tan, Tian Tian; Kwong, Qi Bin; Liu, Hang; Zhang, Guojie; Othman, Rofina Yasmin; Bhassu, Subha

2013-01-01

310

Severe 2010 Amazon drought in historical context  

NASA Astrophysics Data System (ADS)

In 2005 a severe once-in-a-century drought struck the Amazon rain forest. Just 5 years later, an even more severe and widespread drought struck the region. How do these extreme events fit into the context of historical droughts? Marengo et al. looked at historical rainfall and river data sets to find out. They found that the 2010 drought was unique. It started in early summer during an El Niño event and intensified due to warming of the tropical North Atlantic, which was warmer than in any previous year in the records since 1903, including 2005. Their analysis indicates that warming in the tropical North Atlantic affects the hydrology of the Amazon region by promoting a longer dry season, which can be aggravated if there was low rainfall in the previous wet season. They observe that there has been an increase in dry and very dry events in the whole Amazon region since the middle 1970s as well as an increase in the length of the dry season. (Geophysical Research Letters, doi:10.1029/2011GL047436, 2011)

Balcerak, Ernie

2011-08-01

311

Amazon Deforestation Model  

NSDL National Science Digital Library

This series of animations depicts the results of a computer simulation of the effects of deforestation on the surface temperature and precipitation in the Amazon region. Six animations are shown - a control simulation, a deforestation simulation, and the difference between the two for both surface temperature and rainfall. The period simulated is the second half of 1987.

Thomson, Joycelyn

1994-03-13

312

Inundation, Wetland Vegetation and Biogeochemical Processes in the Amazon Basin  

NASA Astrophysics Data System (ADS)

Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of carbon dioxide emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (1979 to 1987) for the mainstem Amazon floodplain in Brazil, the Llanos de Moxos (Beni and Mamore rivers) in Bolivia, the Bananal Island (Araguaia River) and Roraima savannas. Maximum areas subject to inundation, including permanent open waters in rivers and lakes, were as follows (in km2): mainstem Amazon 97,400; Moxos 92,000; Bananal 58,500, and Roraima 16,500. Data from the Japanese Earth Resources Satellite-1, L-band synthetic aperture radar were used to determine inundation and wetland vegetation for a quadrat in the central Amazon basin (0o N to 8o S, 72o W to 54o W) at high water (May-June 1996) and low water (October 1995). Flooded area of rivers and floodplains (> 100 m in width) ranged from 79,000 km2 to 290,000 km2. When combined with estimates of inundation associated with streams not detected by the radar, a maximum area of 350,000 km2 (or 20% of the quadrat) was flooded. Combining the areal extent of flooding and measurements of free dissolved CO2 with an evasion model leads to outgassing of CO2 from inundated surfaces to the atmosphere in the central Amazon of 1.1 plus or minus 0.2 MgC ha-1 y-1. Extrapolated over the whole basin, the flux is 10 times the fluvial export of organic carbon to the ocean.

Melack, J. M.; Hess, L. L.; Hamilton, S. K.; Richey, J. E.; Novo, E. M.

2001-12-01

313

Amazon Forests Depleting Rapidly  

NSDL National Science Digital Library

Does Brazil have to choose between economic growth and preserving the endangered Amazon?http://www.economist.com/world/la/displayStory.cfm?story_id=2597880Deforestation patterns in the Amazonhttp://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=16511The causes of Deforestation are Complexhttp://earthobservatory.nasa.gov/Library/Deforestation/New highways drive accelerating deforestation in Amazonhttp://www.scienceblog.com/community/article2744.htmlStanford scientist develops satellite to study Amazonhttp://daily.stanford.edu/tempo?page=content&id=12852&repository=0001_articleAmazon drought emergency widenshttp://news.bbc.co.uk/2/hi/americas/4344310.stmDespite earlier claims by the Brazilian government that the rate of deforestation in the Amazon had fallen by as much as 50%, scientists from the U.S. and Brazil have found that the Amazon Rainforests are being depleted more rapidly than previously thought. The deforestation is so rapid and expansive that the only effective means by which to measure is by using satellite imagery. Satellite imagery not only detects vast tracts of clear cutting, it is also able to detect selective logging. Selective logging is a process in which loggers only cut down valuable trees, leaving the remainder of the forest alone. Logging companies claim that this process is much more environmentally friendly than clear cutting. While this may be true, environmentalists believe that tree removal of any kind can be detrimental to an ecosystem. They claim that the process of building roads and bringing heavy equipment into these forests is disruptive and damaging. The scientists producing this study claim that deforestation of the Brazilian Amazon has been underestimated by as much as 60%. The Brazilian government stated that although they welcomed the research the numbers were exaggerated. Deforestation is only one of many environmental calamities causing harm to the Amazon. A severe drought, coupled with severe cases of industrial pollution, is making the Amazon a severely endangered ecosystem. [CMH]The first link is to a BBC News article on the new evidence on âÂÂstealthâ logging as well as the new deforestation numbers based on the satellite images. The second link is to an article studying the economic issues of deforestation. The third link illustrates the deforestation patterns in the Amazon using the satellite images. The fourth is a link, which examines the many issues surrounding deforestation in social, economic, and environmental terms. The fifth link is an article discussing issues of highway construction and its connection to deforestation and pollution. The sixth link is to an article detailing the satellite developed at Stanford University designed to study the Amazon. The final link is an article by the BBC with information on the severe drought plaguing the Amazon. [CMH

2005-01-01

314

Simulation of SWOT measurements over the Amazon delta  

NASA Astrophysics Data System (ADS)

The purpose of our study is to evaluate SWOT’s skills with the high mode of resolution (pixel: 4m x 10 to 70m) to highlight estuaries dynamic or to complete a lack of in situ data used by the hydrodynamic models . To reach this goal we have two simulators: one end-to-end developed by S. Biancamaria at Legos and another one developed by the help of industrials Altamira Information and Cap Gemini which describes the physic phenomenon. Both of them need a full description of the instantaneous water states described by a DEM and model’s output. We present first results on the Amazon’s delta due to his peculiar tided-sensitivity. To perform our simulation we have used the hydrodynamic finite element model T-UGOm, the Ore-Hybam data base and data collected during a campaign realised in 2010 over the Amazon river.

Lion, C.; Lyard, F.; Calmant, S.; Crétaux, J.; Le Bars, Y.; Fjortoft, R.

2010-12-01

315

Seeing orange: prawns tap into a pre-existing sensory bias of the Trinidadian guppy  

PubMed Central

Sensory bias, a predisposition towards certain signals, has been implicated in the origin of mate preferences in some species. A risk associated with these biases is that they can be co-opted by predators as sensory lures. Here we propose that the orange spots on the brown pincers of a diurnal, predatory species of prawn function as lures for Trinidadian guppies, which have a sensory bias for orange. We exposed female guppies to (i) a life-like model of this Trinidadian prawn with orange, green or no spots on the pincers or (ii) a live, novel (non-Trinidadian) crustacean (crayfish), also with spotted pincers. First, we provide evidence that guppies sympatric with the prawn recognized our model as a potential predator. Next, we found that guppies spent more time in the dangerous head region of the model prawn with orange-spotted pincers compared with unspotted pincers. Finally, we show that allopatric, but not sympatric, guppies spent more time in the vicinity of the head of a live crayfish when orange spots were added to its pincers than when brown spots were added. Our results suggest that the orange spots on prawn pincers can act as a sensory lure. PMID:22593111

De Serrano, Alexandra R.; Weadick, Cameron J.; Price, Anna C.; Rodd, F. Helen

2012-01-01

316

TBT effects on the development of intersex (ovotestis) in female fresh water prawn Macrobrachium rosenbergii.  

PubMed

The impact of tributyltin (TBT) on the female gonad and the endocrine system in Macrobrachium rosenbergii was studied. Prawns were exposed to environmentally realistic concentrations of 10, 100, and 1000?ng/L of TBT for 6 months. Dose dependent effects were noticed in TBT exposed prawns. At 1000?ng/L TBT caused ovotestis formation (formation of male germ cells in ovary). Presence immature oocytes, fusion of developing oocytes, increase in interstitial connective tissues, and its modification into tubular like structure and abundance of spermatogonia in the ovary of TBT treated prawns. The control prawn ovary showed normal architecture of cellular organelles such as mature oocytes with type 2 yolk globules, lipid droplets, normal appearance of yolk envelop, and uniformly arranged microvilli. On the other hand, type 1 yolk globules, reduced size of microvilli, spermatogonial cells in ovary, spermatogonia with centrally located nucleus, and chromatin distribution throughout the nucleoplasm were present in the TBT treated group. Immunofluorescence staining indicated a reduction in vitellin content in ovary of TBT treated prawn. Moreover, TBT had inhibited the vitellogenesis by causing hormonal imbalance in M. rosenbergii. Thus, the present investigation demonstrates that TBT substantially affects sexual differentiation and gonadal development in M. rosenbergii. PMID:25121096

Peranandam, Revathi; Palanisamy, Iyapparaj; Lourdaraj, Arockia Vasanthi; Natesan, Munuswamy; Vimalananthan, Arun Prasanna; Thangaiyan, Suganya; Perumal, Anantharaman; Muthukalingan, Krishnan

2014-01-01

317

GYRKPPFNGSIFamide (Gly-SIFamide) Modulates Aggression in the Freshwater Prawn Macrobrachium rosenbergii  

PubMed Central

The freshwater prawn Macrobrachium rosenbergii is a tropical crustacean with characteristics similar to those of lobsters and crayfish. Adult males develop through three morphological types—small (SC), yellow (YC), and blue claws (BC)—with each representing a level in the dominance hierarchy of a group, BC males being the most dominant. We are interested in understanding the role played by neuropeptides in the mechanisms underlying aggressive behavior and the establishment of dominance hierarchies in this type of prawn. SIFamides are a family of arthropod peptides recently identified in the central nervous system of insects and crustaceans, where it has been linked to olfaction, sexual behavior, and gut endocrine functions. One of the six SIFamide isoforms, GYRKPPFNGSIFamide (Gly-SIFamide), is highly conserved among decapod crustaceans such as crabs and crayfish. We wanted to determine whether Gly-SIFamide plays a role in modulating aggression and dominant behavior in the prawn. To do this, we performed behavioral experiments in which interactions between BC/YC pairs were recorded and quantified before and after injecting Gly-SIFamide directly into the circulating hemolymph of the living animal. Behavioral data showed that aggression among interacting BC/YC prawns was enhanced by injection of Gly-SIFamide, suggesting that this neuropeptide does have a modulatory role for this type of behavior in the prawn. PMID:20040755

Vazquez-Acevedo, Nietzell; Rivera, Nilsa M.; Torres-Gonzalez, Alejandra M.; Rullan-Matheu, Yarely; Ruiz-Rodriguez, Eduardo A.; Sosa, Maria A.

2010-01-01

318

Fishing for prawn larvae in Bangladesh: an important coastal livelihood causing negative effects on the environment.  

PubMed

Freshwater prawn (Macrobrachium rosenbergii) farming in Bangladesh has, to a large extent, been dependent on the supply of wild larvae. Although there are 81 freshwater prawn hatcheries in the country, a lack of technical knowledge, inadequate skilled manpower, and an insufficient supply of wild broods have limited hatchery production. Many thousands of coastal poor people, including women, are engaged in fishing for wild prawn larvae along the coastline during a few months each year. On average, 40% of the total yearly income for these people comes from prawn larvae fishing activity. However, indiscriminate fishing of wild larvae, with high levels of bycatch of juvenile fish and crustaceans, may impact negatively on production and biodiversity in coastal ecosystems. This concern has provoked the imposition of restrictions on larvae collection. The ban has, however, not been firmly enforced because of the limited availability of hatchery-raised larvae, the lack of an alternative livelihood for people involved in larvae fishing, and weak enforcement power. This article discusses the environmental and social consequences of prawn larvae fishing and concludes that, by increasing awareness among fry fishers, improving fishing techniques (reducing bycatch mortality), and improving the survival of fry in the market chain, a temporal ban may be a prudent measure when considering the potential negative impacts of bycatch. However, it also suggests that more research is needed to find out about the impact of larvae fishing on nontarget organisms and on the populations of targeted species. PMID:20496649

Ahmed, Nesar; Troell, Max

2010-02-01

319

TBT Effects on the Development of Intersex (Ovotestis) in Female Fresh Water Prawn Macrobrachium rosenbergii  

PubMed Central

The impact of tributyltin (TBT) on the female gonad and the endocrine system in Macrobrachium rosenbergii was studied. Prawns were exposed to environmentally realistic concentrations of 10, 100, and 1000?ng/L of TBT for 6 months. Dose dependent effects were noticed in TBT exposed prawns. At 1000?ng/L TBT caused ovotestis formation (formation of male germ cells in ovary). Presence immature oocytes, fusion of developing oocytes, increase in interstitial connective tissues, and its modification into tubular like structure and abundance of spermatogonia in the ovary of TBT treated prawns. The control prawn ovary showed normal architecture of cellular organelles such as mature oocytes with type 2 yolk globules, lipid droplets, normal appearance of yolk envelop, and uniformly arranged microvilli. On the other hand, type 1 yolk globules, reduced size of microvilli, spermatogonial cells in ovary, spermatogonia with centrally located nucleus, and chromatin distribution throughout the nucleoplasm were present in the TBT treated group. Immunofluorescence staining indicated a reduction in vitellin content in ovary of TBT treated prawn. Moreover, TBT had inhibited the vitellogenesis by causing hormonal imbalance in M. rosenbergii. Thus, the present investigation demonstrates that TBT substantially affects sexual differentiation and gonadal development in M. rosenbergii. PMID:25121096

Peranandam, Revathi; Palanisamy, Iyapparaj; Lourdaraj, Arockia Vasanthi; Natesan, Munuswamy; Vimalananthan, Arun Prasanna; Thangaiyan, Suganya; Perumal, Anantharaman; Muthukalingan, Krishnan

2014-01-01

320

Regulation of essential heavy metals (Cu, Cr, and Zn) by the freshwater prawn macrobrachium malcolmsonii (Milne Edwards)  

SciTech Connect

Despite the low concentrations of heavy metals in the surrounding medium, aquatic organisms take them up and accumulate them in their soft tissues to concentrations several fold higher than those of ambient levels. Knowledge of accumulation patterns of a particular trace metal is a prerequisite for understanding the significance of an observed metal concentration in a particular animal, especially from the aspect of biomonitoring. Many marine invertebrates accumulate heavy metals without any regulation and the accumulation necessarily being associated with mechanisms to store the metals in a detoxified form. Two detoxification mechanisms have been described, both of which may occur in one specimen. Heavy metals can either be bound up in insoluble metalliferous {open_quote}granules{close_quote}, or are bound to soluble metal-binding ligands, such as metallothioneins. Some marine decapod crustaceans have an innate ability to regulate the internal concentrations of essential but potentially toxic metals within a constant level, presumably to meet their metabolic demands. However, at present, there is no such information relating to freshwater decapod crustaceans, especially shrimps which occupy a totally different environment. Macrobrachium malcolmsonii, a potential aquaculture species for freshwater is found in abundance in one of the major Indian rivers, the Cauvery. In the present study, an attempt was made to determine whether the freshwater prawn, M. malcolmsonlii, is able to regulate the three essential elements, copper, chromium and zinc, over a wide range of dissolved concentrations. These three metals were chosen because the Cauvery River receives pollutants containing these metals.

Vijayram, K. [Periyar E.V.R. College, Tiruchirappalli (India)] [Periyar E.V.R. College, Tiruchirappalli (India); Geraldine, P. [Bharathidasan Univ., Tiruchirappalli (India)] [Bharathidasan Univ., Tiruchirappalli (India)

1996-02-01

321

Was the 2009 flood the most hazardous or the largest ever recorded in the Amazon?  

NASA Astrophysics Data System (ADS)

Floods are fundamental components of Amazon nature and culture. The large flood of 2009, however, opened a new perspective on hazards and disasters in the Amazon basin. More than 238,000 residents from 38 municipalities were affected by floods along the Amazon River and lower reaches of its tributaries. Never before has a flood in the Amazon produced such a dramatic effect on the local population. The magnitude of the disaster suggested it was the largest recorded Amazon flood since the beginning of measurements in 1928 at Óbidos and that it could represent the largest recorded flood on Earth. A complex combination of atmospheric and hydrologic factors made the 2009 Amazon flood the most hazardous. It was the result of large scale and regional climatic events, non-typical mechanisms of flood transmission generating complex inter-relations in time and space between the main system and the tributaries, and recent urban growth of riverine cities without adequate planning. Our measurements at Óbidos, however, indicate that the 2009 flood was the highest recorded Amazon stage, but most likely not the largest water discharge. We propose as well that the magnitude of the Amazon floods at Óbidos has been overestimated for decades and that the available values of flood discharge have been a source of error for a multidisciplinary set of scientists developing climate and environmental modeling.

Filizola, Naziano; Latrubesse, Edgardo M.; Fraizy, P.; Souza, R.; Guimarães, V.; Guyot, J.-L.

2014-06-01

322

Uranium geochemistry on the Amazon shelf: Evidence for uranium release from bottom sediments  

SciTech Connect

In Amazon-shelf waters, as salinity increases to 36.5 x 10{sup {minus}3}, dissolved uranium activities increase to a maximum of 4.60 dpm 1{sup {minus}1}. This value is much higher than the open-ocean value (2.50 dpm 1{sup {minus}1}), indicating a source of dissolved uranium to shelf waters in addition to that supplied from open-ocean and riverine waters. Uranium activities are much lower for surface sediments in the Amazon-shelf sea bed (mean: 0.69 {plus minus} .09 dpm g{sup {minus}1}) than for suspended sediments in the Amazon river (1.82 dpm g{sup {minus}1}). Data suggest that the loss of particulate uranium from riverine sediments is probably the result of uranium desorption from the ferric-oxyhydroxide coatings on sediment particles, and/or uranium release by mobilization of the ferric oxyhydroxides. The total flux of dissolved {sup 238}U from the Amazon shelf (about 1.2 x 10{sup 15} dpm yr{sup {minus}1}) constitutes about 15% of uranium input to the world ocean, commensurate to the Amazon River's contribution to world river-water discharge. Measurement of only the riverine flux of dissolved {sup 238}U underestimates, by a factor of about 5, the flux of dissolved {sup 238}U from the Amazon shelf to the open ocean.

McKee, B.A.; DeMaster, D.J.; Nittrouer, C.A. (North Carolina State Univ., Raleigh (USA))

1987-10-01

323

The Amazon and climate  

NASA Technical Reports Server (NTRS)

The climatologies of cloudiness and precipitation for the Amazon are reviewed. The physical causes of observed features are explained. The question whether deforestation leads to a reduction in evapotranspiration into the atmosphere is examined, as well as the reduction in precipitation and its implication for the global climate. There are indications that for large scale clearing of tropical rain forests there would indeed be a reduction in rainfall, which would have global effects in terms of climate and weather.

Nobre, C. A.

1984-01-01

324

Flooding dynamics on the lower Amazon floodplain: 2. Seasonal and interannual hydrological variability  

NASA Astrophysics Data System (ADS)

We analyzed seasonal and interannual variability in hydrological fluxes and inundation dynamics of a large floodplain unit (2440 km2) along the lower Amazon River over a period of 15 years (1995-2010). Floodplain inundation was simulated using LISFLOOD-FP, which combines one-dimensional river routing with two-dimensional overland flow, and a local hydrological model. Dominant sources of inflow varied seasonally among direct rain and local runoff (November), Amazon River (December to August) and seepage (September and October). Shifts in timing of dominance among the water balance components occurred conform variations in annual peak stage. The period of dominance of river inflow over total floodplain influxes began about 1 month earlier and ended 1 month later in the 2009 high flood year compared to the 1998 low flood year. On average, river to floodplain discharge represented 0.75% of the Amazon River discharge at Óbidos and 82% of the annual hydrological influxes to the floodplain. We observed an up to ninefold variation in river-floodplain annual discharge. Relatively small increments in main stem peak discharge cause disproportionately large changes in the flow routed through the floodplain. Despite the higher frequency of years with lower minimum stages, the intensification of the hydrological cycle of the Amazon Basin is causing substantially greater amounts of riverine water to flow across floodplain environments.

Rudorff, Conrado M.; Melack, John M.; Bates, Paul D.

2014-01-01

325

Mapping the Amazon: The Mouth of the Amazon  

NSDL National Science Digital Library

The Amazon rain forest is the largest tropical forest in the world. It stretches across South America from nearly ocean to ocean. No seasonal view of this territory existed until a NASA-university collaboration began mapping the Amazon - from space. Scientists listed worked as a team on Mosaicking Software and Mosaic Production.

Snodgrass, Stuart; Chapman, Bruce; Curkendall, David; Freeman, Tony; Miller, Craig; Siegel, Herb

2002-03-14

326

Rivers of Destiny  

NSDL National Science Digital Library

These summaries and video excerpts examine the health of four river systems - the Mississippi, the Amazon, the Jordan and the Mekong, and how environmental problems are facing those who depend on them. There is an account of the flooding in Grafton, Illinois in 1993, one of many towns to suffer devastating damage when the upper Mississippi River overflowed its banks. The video excerpts are from the "Journey to Planet Earth" television series; each is approximately three minutes in length.

327

Dopaminergic modulation of neuromuscular transmission in the prawn.  

PubMed Central

The action of the putative crustacean neurohormone dopamine was examined in the fast extensor musculature of the prawn with intracellular and extracellular recording techniques. Dopamine produced a concentration-dependent (10(-7)-10(-5) M) decrease in the size of the excitatory junctional potential (e.j.p.). It had no effect on the muscle fibre resting membrane potential or input resistance. High concentrations (10(-5)M) of dopamine had no effect on the amplitude distribution or decay time of quantal unit currents, indicating that the agent does not act by blocking post-synaptic receptors or channels. Bath application of dopamine reduced the quantal content at single release sites with a similar time course and concentration dependence as that observed for the e.j.p. Dopamine had no effect on histograms of synaptic delays determined over a 10 degree C range, indicating that it does not modify the time course of phasic neurosecretion. Twin-impulse facilitation experiments showed a marked decrease in the duration of facilitation in the presence of dopamine. These results are interpreted according to recent theoretical and experimental findings as indicating that the dopamine-induced reduction in transmitter release is produced by a decrease in the entry of Ca during the nerve terminal action potential. PMID:2862279

Miller, M W; Parnas, H; Parnas, I

1985-01-01

328

Impact of cyclones and aquatic macrophytes on recruitment and landings of tiger prawns Penaeus esculentus in Exmouth Gulf, Western Australia  

NASA Astrophysics Data System (ADS)

The cover of seagrasses and macroalgae, landings and fishery-independent measures of spawning stock and recruitment for brown tiger prawns, were monitored immediately following a major cyclone in Exmouth Gulf, Western Australia in March 1999. Anecdotal evidence on the extent of seagrass from 1990 to 1998 suggests that the cyclone caused a major, immediate disruption and loss of the seagrass/macroalgal beds (to ?2% cover), the critical prawn nursery habitat, and mangroves in the shallow inshore waters of the system. Prawn landings and recruitment to the fishery were not affected in the year of the cyclone, but were markedly lower in the two years immediately afterwards and then increased as the cover of macrophytes increased to over 40% in 2003. Tiger prawn landings and catch rates were not affected in Shark Bay, a system 500 km south of Exmouth Gulf that did not experience cyclonic disturbance. Seagrasses in Exmouth Gulf showed a succession of species from small colonising species (Halophila ovalis and Halodule uninervis) to larger, broad-leaved species (Cymodocea serrulata, Syringodium isoetifolium) only two years after the cyclone. The recruitment and landings of tiger prawns were correlated significantly with the total cover of macroalgae and seagrass. The large loss of seagrass and macroalgae reduced the settling habitat for postlarvae and the nursery habitat for juvenile tiger prawns, probably leading to the lower recruitment to the fishery. These findings suggest that the extent of seagrass and macroalgae are some of the factors defining the productivity of the tiger prawn fishery in Exmouth Gulf.

Loneragan, N. R.; Kangas, M.; Haywood, M. D. E.; Kenyon, R. A.; Caputi, N.; Sporer, E.

2013-07-01

329

Amazon River Cycles Carbon Faster than Thought  

NSF Publications Database

... is carried by rains and groundwater into waterways from soils, decomposing woody debris, leaf litter ... waterways it is chewed up by microorganisms, insects and fish. The carbon dioxide they generate ...

330

Assessing the Amazon Basin Circulation with Stable Water Isotopes  

Microsoft Academic Search

The isotopic abundances of Oxygen-18 (delta 18O) and Deuterium (delta D) over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Tracking the two stable but rare isotopes of water (1HD16O and 1H218O) makes it possible to trace Amazonian regional evaporative and condensation processes. This offers isotopic constraints on

K. McGuffie; A. Henderson-Sellers

2004-01-01

331

Effect of hypoxia on the immune response of giant freshwater prawn Macrobrachium rosenbergii and its susceptibility to pathogen Enterococcus  

Microsoft Academic Search

Giant freshwater prawns Macrobrachium rosenbergii (14–19g) were challenged withEnterococcus (3×105cfu prawn?1) previously incubated in TSB medium for 24h, then placed in water having concentrations of dissolved oxygen (DO) at 7·75, 4·75, 2·75 and 1·75mg l?1. Onset of mortality occurred after 6h exposure to 1·75mg l?1 DO, and after 12h exposure to 2·75mg l?1 DO. Cumulative mortality of prawns at 1·75mg

Winton Cheng; Chun-Hung Liu; Jung-Ping Hsu; Jiann-Chu Chen

2002-01-01

332

Ecology of the river dolphin, Inia geoffrensis, in the Cinaruco River, Venezuela  

E-print Network

June 1994. . Stomach contents of one Inia geoffrensis. 10 10 32 47 50 52 52 52 53 60 62 INTRODUCTION River dolphins of the species Inia geoffiensis inhabit the massive Amazon and Orinoco River basins of South America (Best and da Silva... 1993). Throughout its range, fnia is known by many common names, including tonina and bufeo in Spanish, and bofo in Portuguese. In the English speaking world, inia is often referred to as the Amazon dolphin or the pink dolphin. The species...

McGuire, Tamara Lee

2012-06-07

333

The changing Amazon forest  

E-print Network

Long-term monitoring of distributed, multiple plots is the key to quantify macroecological patterns and changes. Here we examine the evidence for concerted changes in the structure, dynamics and composition of old-growth Amazonian forests in the late twentieth century. In the 1980s and 1990s, mature forests gained biomass and underwent accelerated growth and dynamics, all consistent with a widespread, long-acting stimulation of growth. Because growth on average exceeded mortality, intact Amazonian forests have been a carbon sink. In the late twentieth century, biomass of trees of more than 10 cm diameter increased by 0.62G0.23 t C ha K1 yr K1 averaged across the basin. This implies a carbon sink in Neotropical old-growth forest of at least 0.49G0.18 Pg C yr K1. If other biomass and necromass components are also increased proportionally, then the old-growth forest sink here has been 0.79G0.29 Pg C yr K1, even before allowing for any gains in soil carbon stocks. This is approximately equal to the carbon emissions to the atmosphere by Amazon deforestation. There is also evidence for recent changes in Amazon biodiversity. In the future, the growth response of remaining old-growth mature Amazon forests will saturate, and these ecosystems may switch from sink to source driven by higher respiration (temperature), higher mortality (as outputs equilibrate to the growth inputs and periodic drought) or compositional change (disturbances). Any switch from carbon sink to source would have profound implications for global climate, biodiversity and human welfare, while the documented acceleration of tree growth and mortality may already be affecting the interactions among millions of species.

Oliver L. Phillips; Simon L. Lewis; Timothy R. Baker; Kuo-jung Chao; Niro Higuchi

2008-01-01

334

Bioaccumulation of 210Pb in the Kaveri River ecosystem, India  

Microsoft Academic Search

Data on the concentrations of 210Pb in water, sediment and biota (plankton, weed, snail, bivalve, prawn and fish) of the Kaveri River ecosystem at Tiruchirappalli in South India are presented. The highest level of 210Pb activity was observed in the sediment (15.5 Bq kg?1 dry) and the lowest activity in water (2.7mBq l?1). The root of the aquatic weed, Eichhornia

M. A. R. Iyengar

1997-01-01

335

Major viral diseases of the black tiger prawn (Penaeus monodon) in Thailand  

Microsoft Academic Search

There are five different viruses which are currently being studied for their impact on commercial farming of the black tiger prawn (Penaeus monodon) in Thailand. Some of these viruses cause disease in other penaeid shrimp species and even other crustacean species. Some occur not only in cultivated shrimp in other Asian countries, but also in those from Australia and the

T. W. Flegel

1997-01-01

336

Nutritional requirements, feed formulation, and feeding practices for intensive culture of the freshwater prawn Macrobrachium rosenbergii  

Microsoft Academic Search

Research results concerning nutrition of the freshwater prawn Macrobrachium rosenbergii and applicability to the production of feed for intensive culture are presented. Future research approaches are recommended and comparisons to the nutrition of penaeid shrimp species are provided.Quantitative requirements of essential amino acids for M. rosenbergii are undefined; however, arginine, methionine, and lysine are suspected as being the first limiting

Louis R. DAbramo

1994-01-01

337

Effects and toxicity of phthalate esters to hemocytes of giant freshwater prawn, Macrobrachium rosenbergii  

Microsoft Academic Search

Phthalate esters (PAEs) have been considered as environmental pollutants and have been subject to control in the United States of America and Japan. The aim of this study was to investigate the effects and toxicity of eight PAEs to hemocytes and the defense functions of giant freshwater prawn (Macrobrachium rosenbergii), including hemocytic adhesion, pseudopodia formation, phenoloxidase (PO) activity, and superoxide

Hung-Hung Sung; Wei-Yi Kao; Yi-Jen Su

2003-01-01

338

Detection of white spot baculovirus (WSBV) in giant freshwater prawn, Macrobrachium rosenbergii, using polymerase chain reaction  

Microsoft Academic Search

White spot baculovirus (WSBV) is the causative agent of a disease which decimated some cultured penaeid shrimp populations and inflicted severe economic damage in Taiwan. Until very recently, the giant freshwater prawn Macrobrachium rosenbergii was thought to be unaffected by this virus, but now signs closely resembling white spot syndrome (WSS) have been observed on its exoskeleton. In this paper,

S. E Peng; C. F Lo; C. H Ho; C. F Chang; G. H Kou

1998-01-01

339

The Perfect Partnership Southside Virginia farmers are growing a new product: freshwater prawns  

E-print Network

of a network of agricultural producers, 2) expand the community's understanding and appreciation of local foods of using prawns as the key food for seafood events. www.ext.vt.edu Produced by Communications and Marketing Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, national

Liskiewicz, Maciej

340

The androgenic gland and monosex culture of freshwater prawn Macrobrachium rosenbergii (De Man): a biotechnological perspective  

Microsoft Academic Search

Males of the freshwater prawn Macrobrachium rosen- bergii (De Man) grow faster and reach a larger size at harvest than females of the species. It is thus obvious that culture of monosex all-male populations would be economically advantageous. Sexual di¡erentia- tion in crustaceans is regulated by the androgenic gland (AG), which plays a pivotal role in the regula- tion of

Amir Sagi; Eliahu D Aflalo

2005-01-01

341

Induced thermotolerance and stress resistance in larvae of the freshwater prawn, Macrobrachium rosenbergii (de Man, 1879)  

Microsoft Academic Search

Optimal conditions for heat shock (HS) were used to demonstrate induced thermotolerance (ITT) in larvae of the prawn, Macrobrachium rosenbergii. Larvae from three different broodstock nutritional regimes exhibited comparable degrees of ITT, which remained high for about 4 days. Survival and growth of larvae given the standard HS treatment (37 °C for 30min) were not statistically different from those of

M. M. Rahman; M. Wille; R. O. Cavalli; P. Sorgeloos; J. S. Clegg

2004-01-01

342

ONTOGENY OF SOCIAL STRUTURE AND POPULATION DYNAMICS IN THE GIANT FRESHWATER PRAWN, MACROBRACHIUM ROSENBERGII (DE MAN)  

Microsoft Academic Search

Social organization apparent in adult populations of giant freshwater prawn Macrobrachium rosenbergii was analyzed with respect to: a) the weight distribution of a mature population, b) morphological definition of the three male types, and c) growth and maturation characteristics of males and females, including behavioral observations. The ontogeny of social structure was then followed starting from newly metamorphosed postlarvae up

ZIVA RA' ANAN; DAN COHEN

343

Chromosome behaviour upon fertilization in eggs of the giant freshwater prawn, Macrobrachium rosenbergii (de Man)  

Microsoft Academic Search

Chronological changes of the chromosomes upon feritilization of the giant freshwater prawn, Macrobrachium rosenbergii (de Man), were followed. Egg chromosomes, within 2 min after spawning, were at the second meiotic metaphase whereas sperm nucleus retained a cupped shape of the base region. The egg chromosomes progressed to the second meiotic anaphase by 10–15 min and completed maturation by 20 min

PRANEET DAMRONGPHOL; NITTAYA EANGCHUAN; BOONSERM POOLSANGUAN

1991-01-01

344

Spermatogenesis and distinctive mature sperm in the giant freshwater prawn, Macrobrachium rosenbergii (De Man, 1879)  

Microsoft Academic Search

The structures of differentiating male germ cells in the testis of the giant freshwater prawn, Macrobrachium rosenbergii, were studied by light and electron microscopy. Based on ultrastructural characteristics, the developing male germ cells are classified into 12 stages, including spermatogonia, six phases of primary spermatocytes (leptotene, zygotene, pachytene, diplotene, diakinesis and metaphase), secondary spermatocyte, three stages of spermatids and mature

Jaruwan Poljaroen; Rapeepun Vanichviriyakit; Yotsawan Tinikul; Ittipon Phoungpetchara; Vichai Linthong; Wattana Weerachatyanukul; Prasert Sobhon

2010-01-01

345

CERVUS vs. COLONY for successful parentage and sibship determinations in freshwater prawn Macrobrachium rosenbergii de Man  

Microsoft Academic Search

This study assesses the properties of 10 microsatellite loci and two popular computer programs for likelihood-based parentage identification in commercial strains of the giant freshwater prawn Macrobrachium rosenbergii. It was our interest to determine the number of markers needed to optimize between genotyping cost and power of the test. Nine loci were informative, with average expected heterozygosity of 0.80 and

Thuchapol Karaket; Supawadee Poompuang

346

Broodstock Condition and Egg Quality in Tiger Prawn, Penaeus monodon , Resulting from Feeding Bioencapsulated Live Prey  

Microsoft Academic Search

This study was motivated by the need to find a solution to poor egg quality and the resulting mass mortality of hatchery-produced larvae of the tiger prawn, Penaeus monodon. The approach adopted sought to improve the broodstock condition and determine its effect on egg quality using rates of fertilization, hatching and metamorphosis. Broodstock specimens were given four separate dietary treatments

Annita Yong Seok Kian; Saleem Mustafa; Ridzwan A. Rahman

2004-01-01

347

A Simple "in Vitro" Culture of Freshwater Prawn Embryos for Laboratory Investigations  

ERIC Educational Resources Information Center

Giant freshwater prawn ("Macrobrachium rosenbergii" De Man) embryos can be cultured "in vitro" to hatching in 15% (v/v) artificial seawater (ASW). This technique can be applied as a bioassay for testing toxicity or for the effects of various substances on embryo development and can be used as a simple and low-cost model for studying embryo…

Porntrai, Supaporn; Damrongphol, Praneet

2008-01-01

348

Mercury and methylmercury in fish and human hair from the Tapajós river basin, Brazil  

Microsoft Academic Search

Mercury is being released in the Amazon in an abusive way due to goldmining activities. The Tapajós river basin was the first to be intensively exploited in the modern Amazon gold rush. Fish and hair samples as the best indicators of human methylmercury contamination were investigated in the main cities and villages along the Tapajós river basin. The upper basin

Olaf Malm; Fernando J. P. Branches; Hirokatsu Akagi; Miriam B. Castro; Wolfgang C. Pfeiffer; Masazumi Harada; Wanderley R. Bastos; Hiroo Kato

1995-01-01

349

Molecular and immunological responses of the giant freshwater prawn, Macrobrachium rosenbergii, to the organophosphorus insecticide, trichlorfon.  

PubMed

Trichlorfon is an organophosphorus (OP) insecticide that is used as an agriculture pesticide to destroy insects, a human medicine to combat internal parasites, and an ectoparasiticide in the livestock and aquaculture industries, but which has caused aquatic toxicity in the prawn industry. The aim of this study was to investigate the effects of trichlorfon on molecular and enzymatic processes of the immunological response of the giant freshwater prawn, Macrobrachium rosenbergii, at 0, 0.2, and 0.4mgL(-1) with 0, 3, 6, 12, and 24h of exposure. The total hemocyte count (THC), respiratory bursts (RBs), phenoloxidase (PO) activity, and superoxide dismutase (SOD) activity were examined to evaluate immunological responses and oxidative stress. Results showed that THCs of the prawn exposed to trichlorfon at both concentrations (0.2 and 0.4mgL(-1)) had increased after 12 and 24h; SOD and PO activities had significantly increased at 3h, whereas production of RBs had dramatically increased as oxidative stress at each sampling time after exposure to trichlorfon compared to the control. A potential biomarker of OPs, acetylcholinesterase (AChE) revealed a significant decrease after exposure for 6h, and showed a time-dependent tendency. Immune gene expressions, including prophenoloxidase (proPO), the lipopolysaccharide- and ?-1,3-glucan-binding protein (LGBP), peroxinectin (PE), ?2-macroglubulin (?2M), transglutaminase (TG), and copper, zinc (Cu,Zn)-SOD, of prawns exposed to trichlorfon at 0, 0.2, and 0.4mgL(-1) for 0, 6, and 24h were further evaluated. Expressions of all of the immune genes significantly decreased when prawns were exposed to 0.4mgL(-1) trichlorfon for 24h, and among them, an increase in SOD expression was seen after exposure to 0.4mgL(-1) for 6h. Prawns exposed to trichlorfon within 24h exhibited the decrease of circulating hemocytes, and also the induction of oxidative stress, which caused subsequent damage to DNA formation of immune genes. From these results, we concluded that immunological responses and immune gene expressions of prawn exposed to trichlorfon at 0.4mgL(-1) for 24h were perturbed, thus causing a deficiency in immunity and subsequent increased susceptibility to pathogen infections. PMID:23340335

Chang, Chin-Chyuan; Rahmawaty, Atiek; Chang, Zhong-Wen

2013-04-15

350

Molecular Characterisation of Colour Formation in the Prawn Fenneropenaeus merguiensis  

PubMed Central

Introduction Body colouration in animals can have a range of functions, with predator protection an important aspect of colour in crustaceans. Colour determination is associated with the carotenoid astaxanthin, which is taken up through the diet and stabilised in the tissues by the protein crustacyanin. As a variety of genes are found to play a role in colour formation in other systems, a holistic approach was employed in this study to determine the factors involved in Fenneropenaeus merguiensis colouration. Results Full length F. merguiensis crustacyanin subunit A and C sequences were isolated. Crustacyanin subunit A and C were found in the F. merguiensis transcriptomes of the muscle/cuticle tissue, hepatopancreas, eye stalk and nervous system, using 454 next generation sequencing technology. Custom microarray analysis of albino, light and dark F. merguiensis cuticle tissue showed genes encoding actin, sarcoplasmic calcium-binding protein and arginine kinase to be 4-fold or greater differentially expressed (p<0.05) and down-regulated in albinos when compared to light and dark samples. QPCR expression analysis of crustacyanin and total astaxanthin pigment extraction revealed significantly (p<0.05) lower crustacyanin subunit A and C gene transcript copy numbers and total astaxanthin levels in albinos than in the light and dark samples. Additionally, crustacyanin subunit A and C expression levels correlated positively with each other. Conclusions This study identified gene products putatively involved in crustacean colouration, such as crustacyanin, sarcoplasmic calcium-binding protein and forms of actin, and investigated differences in gene expression and astaxanthin levels between albino, light and dark coloured prawns. These genes open a path to enhance our understanding of the biology and regulation of colour formation. PMID:23441225

Ertl, Nicole G.; Elizur, Abigail; Brooks, Peter; Kuballa, Anna V.; Anderson, Trevor A.; Knibb, Wayne R.

2013-01-01

351

A prawn transglutaminase: molecular characterization and biochemical properties.  

PubMed

In this study, we report the bioinformatics characterization, gene expression, transglutaminase activity and coagulation assays of transglutaminase (TGase) of freshwater prawn Macrobrachium rosenbergii identified from the constructed cDNA library by GS FLX™ technology. Even though, TGase have sequence similarity, they differ extensively in their substrate specificity and are thought to play an important in variety of functions such as development, tissue differentiation and immune responses etc. Gene expression studies show that MrTGase is widely distributed in the tissues such as heart, muscle, intestine, brain, etc., but higher amounts are found in hemocyte. Results of TGase mRNA relative expression in hemocyte, before and after infected with white spot syndrome baculovirus (WSBV) and Vibrio harveyi show that the gene expression initially increases up to 24 h and then it falls down. Coagulation assay results showed that the endogenous TGase is involved in the rapid assembly of a specific, plasma clotting protein. Structural studies show that MrTGase contains a typical TGc domain between 323 and 424, and two putative integrin-binding motifs at Arg(180)-Gly(181)-Asp(182) and Arg(269)-Gly(270)-Asp(271). The predicted 3D model of MrTGase contains 47.04% coils (366 amino acid residues), 26.74% extended strand (208 residues), 21.72% ?-helix (169 residues) and 4.5% beta turns (35 residues). BLASTp analysis of MrTGase exhibited high sequence similarities with other crustacean TGase, with the highest observed in white shrimp (77.1%). Moreover, the phylogenetic analysis also showed that MrTGase clustered with the other members of crustacean TGase. Overall, these results suggested that MrTGase is a major and functional TGase of M. rosenbergii for haemolymph coagulation and also in spread of infection. PMID:24012776

Arockiaraj, Jesu; Gnanam, Annie J; Palanisamy, Rajesh; Kumaresan, Venkatesh; Bhatt, Prasanth; Thirumalai, Muthukumaresan Kuppusamy; Roy, Arpita; Pasupuleti, Mukesh; Kasi, Marimuthu; Sathyamoorthi, Akila; Arasu, Abirami

2013-12-01

352

A quick look at the 2012 record flood in the Amazon Basin  

NASA Astrophysics Data System (ADS)

The water level at the Manaus Port on the Negro River reached its record value of 29.97 m on 29 May 2012. This is higher than the previous record in the year 2009 by 20 cm. The rise of the level from November 2011 till the record maximum is the highest in the past several decades. A cooler South Atlantic and a normal or slightly warmer North Atlantic were associated with a record flood in the Amazon Basin in 2012. The seasonal atmospheric moisture convergence and the precipitation over the Amazon Basin are well correlated. During the period October 2011 through May 2012 the moisture-flux convergence was 38% more intense than climatology. The rainfall equivalence of this excess moisture convergence is about 2.5 mm d-1 in the western Amazon Basin and 1.8 mm d-1 in the whole Amazon Basin.

Satyamurty, Prakki; Costa, Claudia Priscila Wanzeler; Manzi, Antonio Ocimar; Candido, Luiz Antonio

2013-04-01

353

Radium226 levels in the Cauvery river ecosystem, India  

Microsoft Academic Search

We studied the natural radioactivity distribution of an ?-emitting radionuclide,226Ra in water, sediment and biota (plankton, weed, snail, bivalve, prawn and fish) of Cauvery river ecosystem extending a stretch\\u000a of 95 km. The dissolved226Ra concentration in river water ranged from 0.82mBq.I-1 to l 06mBq.l-1 (mean: 0.93mBq.l-1) and the activity in river sediments from 4.7Bq.kg-1 to 6.9Bq.Kg-1 (mean: 5.6Bq.kgg-1 dry wt.).

P. Shahul Hameed; K. Shaheed; S. S. N. Somasundaram; M. A. Riyengar

1997-01-01

354

Copepods and fishes in the Brazilian Amazon  

NASA Astrophysics Data System (ADS)

The Amazon basin comprises the largest river ecosystem in the world (7 million km 2) with annual high and low water peaks and a constant temperature near 29°C. Some 2000 fish species and 40 species of free-living copepods are known to occur in Amazonia. The free-living forms serve as food for most larval fishes and some adults, but they also transmit several parasites including representatives of the nematode family Camallanidae. About three dozen species of parasitic copepods have been described from the Brazilian Amazon. Females of Amazonian parasitic copepods are found on skin, gill filaments, gill rakers or within the nasal fossae. Parasitic copepods are found on fishes that are from a few millimeters long up to those over 2 m in length and they are usually quite host specific. All have body pigmentation in different patterns and colors (frequently blues, such as cerulean, cobalt, spectrum, smalt or campanula). It is suggested that the coloration serves to attract specific host fish. Copepods have evolved adaptations for attachment and feeding, especially in the second antennae and endopods. Examples of progenesis, phoresis and commensalism are shown. Some species produce pathology such as a tourniquet effect, hyperplasia, blood loss and anemia, and can kill fishes by limiting their respiration.

Thatcher, Vernon E.

1998-06-01

355

How Pecten Brazil drilled the Amazon basin  

SciTech Connect

Pecten Brazil overcame numerous obstacles to drill two exploratory wells in the Amazon Basin last year. These included: The threat of low water in normally navigable rivers. Dense jungle growth at both locations. Lack of suitable roads for heavy hauling. Inconvenient distances from supply points. An unusual basalt formation responsible for unique drilling problems. Hundreds of helicopter lifts to move drilling rigs, supplies, and personnel. Pecten contracted with Petrobras, the Brazilian national oil company, to evaluate three blocks in the Amazon jungle, each about 68 miles (110 km) on a side, through seismic study and ultimate drilling. Planning for the drilling phase got started on March 17, 1981 with December 1 targeted as spud date for the first well. Actual spud date was November 25, 5 days ahead of schedule, in spite of all obstacles. Pecten has a mid-Amazonas block now under seismic investigation for possible exploratory drilling. Logistics problems in this one provide new difficulties, as the area is extremely wet. Most work is carried on by boat. The company is also looking offshore Bahia, testing the possible extension of the Renconcavo basin. Two wells have already provided good shows of a high pour point oil, with flow rates from 400 to 1,000 b/d. Another area of interest to Pecten is offshore Rio Grande do Norte.

Bleakley, W.B.

1983-09-01

356

Apptication of Biofloc Technology (BFI) in Ihe nunery rearing and farming of giant freshwater prawn, Macrobrachillm rosenbergii (de Man).  

E-print Network

??This thesis Entitled Application of Biofloc technology (BFT) In the Nursery Rearing and Farming of Giant Freshwater Prawn,Macrobrachium Rosenbergii(De Man). Aquaculture, rearing plants and animals… (more)

Prajith, K K

2011-01-01

357

DNA microsatellite-based evaluation of early growth performance among strains of freshwater prawn Macrobrachium rosenbergii de Man  

Microsoft Academic Search

Microsatellite DNA markers were used to assess early growth performance among different strains of freshwater prawn under separate and communal rearing conditions. Two-hundred-and-twenty broodstock individuals from three prawn strains were collected and used as baseline populations for assignment tests. The exclusion–simulation approach was performed on different sets of one to seven microsatellite loci to determine the power of the assignment

Thuchapol Karaket; Supawadee Poompuang; Uthairat Na-Nakorn; Wongpathom Kamonrat; Eric M. Hallerman

2011-01-01

358

The On-Farm Trials of the Rotational Prawn-Rice Farming in a Semi-Deep Water Area  

Microsoft Academic Search

The on-farm trials of rotational rice-prawn farming in a semi-deep water area in the Mekong Delta of Vietnam was carried out in six rice fields (0.7–1.0 ha) to evaluate the production and economic efficiency of using low and high cost feed on prawn culture in paddies at different densities. Two stocking densities of 4 and 5 PL\\/m were investigated. Two

Lam My Lan; Jean-Claude Micha; Duong Nhut Long; Tran Thanh Hai

2008-01-01

359

All eyes on the Amazon  

Microsoft Academic Search

Meteorologist and biosphere scientist Carlos Nobre of Brazil's National Institute for Space Research in São Paulo has modelled the effects of deforestation and global warming on the Amazon. Nature talks to him about the future of the unique rainforest.

Jeff Tollefson

2008-01-01

360

Mapping the Amazon: Mosaic pan  

NSDL National Science Digital Library

Pan across Amazon rainforest mosaic showing low water season (blue) and high water season (yellow). Together, these snapshots reveal conditions on the ground. Scientists listed worked as a team on Mosaicking Software and Mosaic Production.

Snodgrass, Stuart; Chapman, Bruce; Curkendall, David; Freeman, Tony; Miller, Craig; Siegel, Herb

2002-03-14

361

On the sources of hydrological prediction uncertainty in the Amazon  

NASA Astrophysics Data System (ADS)

Recent extreme events in the Amazon River basin and the vulnerability of local population motivate the development of hydrological forecast systems (HFSs) using process based models for this region. In this direction, the knowledge of the source of errors in HFSs may guide the choice on improving model structure, model forcings or developing data assimilation (DA) systems for estimation of initial model states. We evaluate the relative importance of hydrologic initial conditions (ICs) and model meteorological forcings (MFs) errors (precisely precipitation) as sources of stream flow forecast uncertainty in the Amazon River basin. We used a hindcast approach developed by Wood and Lettenmaier (2008) that contrasts Ensemble Streamflow Prediction (ESP) and a reverse Ensemble Streamflow Prediction (reverse-ESP). Simulations were performed using the physically-based and distributed hydrological model MGB-IPH, comprising surface energy and water balance, soil water, river and floodplain hydrodynamics processes. Model was forced using TRMM 3B42 precipitation estimates. Results show that uncertainty on initial conditions play an important role for discharge predictability even for large lead times (~1 to 3 months) on main Amazonian Rivers. ICs of surface waters state variables are the major source of hydrological forecast uncertainty, mainly in rivers with low slope and large floodplains. ICs of groundwater state variables are important mostly during low flow period and southeast part of the Amazon, where lithology and the strong rainfall seasonality with a marked dry season may be the explaining factors. Analyses indicate that hydrological forecasts based on a hydrological model forced with historical meteorological data and optimal initial conditions, may be feasible. Also, development of DA methods is encouraged for this region.

Paiva, R. C. D.; Collischonn, W.; Bonnet, M. P.; Gonçalves, L. G. G.

2012-03-01

362

Water level dynamics in the Amazon floodplain  

NASA Astrophysics Data System (ADS)

Nonlinear analysis of Amazonian River systems suggests that water level variability is due to Brownian-like motions BH. Dynamical properties of the water level is probably a response of rainfall and runoff smoothing by the stored water in the floodplain; additional inputs of water results in attenuated perturbations of the water level. This implies that noise is a self-affine fractal with scale invariance, and in accordance with surrogate and correlation dimension analysis, which refused the hypothesis of low dimensional chaos for water level dynamics. Opposing to the chaotic approach, we present a fractal model formed by a periodic signal and a BH process that mimics original water level variability. Dynamical exponents are remarkably similar between real and modeled data when BH influence is about 1% the amplitude of the periodic signal. In comparison to natural systems, a hydroelectric reservoir produces different exponents, due to the control of the water level, as demonstrated for the Tucuru?´ dam in the Tocantins River. The Amazon floodplain at Óbidos and Curuai exhibits a fortnight cycle most probably due to bore tide influence in the river mouth.

Lima, Ivan Bergier Tavares; Rosa, Reinaldo Roberto; Ramos, Fernando Manuel; de Moraes Novo, Evlyn Márcia Leão

363

Low-water maps of the groundwater table in the central Amazon by satellite altimetry  

NASA Astrophysics Data System (ADS)

plays a fundamental role in rainforest environments, as it is connected with rivers, lakes, and wetlands, and helps to support wildlife habitat during dry periods. Groundwater reservoirs are however excessively difficult to monitor, especially in large and remote areas. Using concepts from groundwater-surface water interactions and ENVISAT altimetry data, we evaluated the topography of the groundwater table during low-water periods in the alluvial plain of the central Amazon. The water levels are monitored using an unprecedented coverage of 491 altimetric stations over surface waters in the central Amazon. The groundwater table maps interpolated at spatial resolutions ranging from 50 to 100 km are consistent with groundwater wells data. They provide evidence of significant spatiotemporal organization at regional scale: heterogeneous flow from the hillslope toward the main rivers is observed, as well as strong memory effects and contrasted hydrological behaviors between the North and the South of the Amazon.

Pfeffer, Julia; Seyler, Frédérique; Bonnet, Marie-Paule; Calmant, Stéphane; Frappart, Frédéric; Papa, Fabrice; Paiva, Rodrigo C. D.; Satgé, Frédéric; Silva, Joecila Santos Da

2014-03-01

364

Changes in the carbon cycle of Amazon ecosystems during the 2010 drought  

NASA Astrophysics Data System (ADS)

Satellite remote sensing was combined with the NASA-CASA (Carnegie Ames Stanford Approach) carbon cycle simulation model to evaluate the impact of the 2010 drought (July through September) throughout tropical South America. Results indicated that net primary production in Amazon forest areas declined by an average of 7% in 2010 compared to 2008. This represented a loss of vegetation CO2 uptake and potential Amazon rainforest growth of nearly 0.5 Pg C in 2010. The largest overall decline in ecosystem carbon gains by land cover type was predicted for closed broadleaf forest areas of the Amazon river basin, including a large fraction of regularly flooded forest areas. Model results support the hypothesis that soil and dead wood carbon decomposition fluxes of CO2 to the atmosphere were elevated during the drought period of 2010 in periodically flooded forest areas, compared to those for forests outside the main river floodplains.

Potter, Christopher; Klooster, Steven; Hiatt, Cyrus; Genovese, Vanessa; Castilla-Rubio, Juan Carlos

2011-07-01

365

Changes in the Carbon Cycle of Amazon Ecosystems During the 2010 Drought  

NASA Technical Reports Server (NTRS)

Satellite remote sensing was combined with the NASA-CASA carbon cycle simulation model to evaluate the impact of the 2010 drought (July through September) throughout tropical South America. Results indicated that net primary production (NPP) in Amazon forest areas declined by an average of 7% in 2010 compared to 2008. This represented a loss of vegetation CO2 uptake and potential Amazon rainforest growth of nearly 0.5 Pg C in 2010. The largest overall decline in ecosystem carbon gains by land cover type was predicted for closed broadleaf forest areas of the Amazon River basin, including a large fraction of regularly flooded forest areas. Model results support the hypothesis that soil and dead wood carbon decomposition fluxes of CO2 to the atmosphere were elevated during the drought period of 2010 in periodically flooded forest areas, compared to forests outside the main river floodplains.

Potter, Christophera; Klooster, Steven; Hiatt, Cyrus; Genovese, Vanessa; Castilla-Rubino, Juan Carlos

2011-01-01

366

Deforestation, floodplain dynamics, and carbon biogeochemistry in the Amazon Basin  

NASA Technical Reports Server (NTRS)

Three aspects of the physical geographic environment of the Amazon Basin are considered: (1) deforestation and reforestation, (2) floodplain dynamics, and (3) fluvial geomorphology. Three independent projects are coupled in this experiment to improve the in-place research and to ensure that the Shuttle Imaging Radar-B (SIR-B) experiment stands on a secure base of ongoing work. Major benefits to be obtained center on: (1) areal and locational information, (2) data from various depression angles, and (3) digital radar signatures. Analysis will be conducted for selected sites to define how well SIR-B data can be used for: (1) definition of extent and location of deforestation in a tropical moist forest, (2) definition and quantification of the nature of the vegetation and edaphic conditions on the (floodplain) of the Amazon River, and (3) quantification of the accuracy with which the geometry and channel shifting of the Amazon River may be mapped using SIR-B imagery in conjunction with other remote sensing data.

Bryan, M. L.; Dunne, T.; Richey, J.; Melack, J.; Simonett, D. S.; Woodwell, G.

1984-01-01

367

Ballast water: a threat to the Amazon Basin.  

PubMed

Ballast water exchange (BWE) is the most efficient measure to control the invasion of exotic species from ships. This procedure is being used for merchant ships in national and international voyages. The ballast water (BW) salinity is the main parameter to evaluate the efficacy of the mid-ocean ballast water exchange. The vessels must report to the Port State Control (PSC), via ballast water report (BWR), where and how the mid-ocean BWE was performed. This measure allows the PSC to analyze this information before the ship arrives at the port, and to decide whether or not it should berth. Ship BW reporting forms were collected from the Captaincy of Santana and some ships were visited near the Port of Santana, located in Macapá (Amazon River), to evaluate the BW quality onboard. We evaluated data submitted in these BWR forms and concluded that the BWE efficacy might be compromised, because data contained in these BWR indicate that some ships did not change their BW. We found mistakes in filling the BWR forms and lack of information. Moreover, these ships had discharged BW with high level of salinity, Escherichia coli and total coliforms into the Amazon River. We concluded that the authorities of the Amazon Region need to develop more efficient proceedings to evaluate the ballast water reporting forms and BW quality, as there is potential risk of future invasion of exotic species in Brazilian ports. PMID:24928458

Pereira, Newton Narciso; Botter, Rui Carlos; Folena, Rafael Dompieri; Pereira, José Pinheiro Fragoso Neto; da Cunha, Alan Cavalcanti

2014-07-15

368

New sediment budget calculations for the submarine Amazon Delta indicates enhanced modern sediment fluxes of the Amazon system  

NASA Astrophysics Data System (ADS)

The submarine Amazon Delta is one major sink in the Amazon source-to-sink system. It is estimated, that the Amazon transports around 1200 Mt/yr. Around 50% of this river sediment load, namely 400 - 800 Mt/yr, is stored on the submarine delta, leading to sedimentation rates of decimeters per year (Nittrouer et al., 1995). The majority of the remaining sediments is deposited on the lower delta plain of the Amazon, but another significant portion is accumulated at the Amapa shoreline or is bypassed further northwestwards. These sediment budget calculations are mainly based on radioisotopic profiles measured at sediment cores in the frame of the AmasSeds project, which was carried out in the 1980ties and 1990ties (Nittrouer et al., 1995). Here we present another approach for calculating mass fluxes in the Amazon system. Within the Project AMADEUS, a cooperation between the MARUM, Bremen, Germany and the University Sao Paulo, Brazil, high-resolution seismic multichannel seismic data and sediment echosounder data (PARASOUND) were collected during Cruise MSM20/3 in February/March 2012. Main emphases of the surveying were set to the forset and bottomset of the delta, where most of the accretion occurs. A special outcome of the new data is the comparison with PARASOUND data collected in 1996 during Cruise M34/4. Due to several crossing points of both data sets it is now possible to carry out direct measurements of the accumulation during these 16 years. Another time horizon is a prominent unconformity spreading over the submarine delta, since the sedimentation on top of this unconformity had been dated to start roughly 100 yrs ago (Sommerfield et al., 1995). Mapping of this unconformity as well as the reflector representing the seafloor of 1996 gives the opportunity to calculate volumes and mass of the sediment stored within the survey area for two different time spans. First calculations show, that the sediment accumulation on the submarine delta since 1996 is significantly enhanced compared to the 100 years before. Also the comparison of the accumulation from 1996 to 2012 with results from the AmasSeds project suggests that the storage of sediments notably increased within the last decades. Even the main survey area of MSM 20/3 comprises just <20% of the area of the entire submarine delta, the mass of sediments accumulated there is in the same order of magnitude as calculated for the complete submarine delta by Nittrouer et al. (1995). Additionally, a notable deposition between 1996 and 2012 is observed outside of the main survey area. These results indicate a considerable increase of the sediment delivery by the Amazon River in recent times instead of just a reorganization of the sediment distribution, which finally may suggest amplified erosion in the Amazon Basin. However, this new calculation gives a valuable contribution to understand the modern Amazon source-to-sink system. References: C. A. Nittrouer, S. A. Kuehl, R. W. Sternberg, A. G. Figueiredo Jr., L. E.C. Faria, 1995, An introduction to the geological significance of sediment transport and accumulation on the Amazon continental shelf, Marine Geology, 125, p. 177-192. C. K. Sommerfield, C. A. Nittrouer, A. G. Figueiredo, Stratigraphic evidence of changes in Amazon shelf sedimentation during the late Holocene, 1995, Marine Geology, 125, p. 351-371.

Schwenk, T.; Haberkern, J.; Mulitza, S.; Chiessi, C. M.

2013-12-01

369

Beryllium isotope geochemistry in tropical river basins  

Microsoft Academic Search

The distributions of beryllium-9 and beryllium-10 in rivers within the Orinoco and Amazon basins have been examined to extend the understanding of their geochemical cycles and to develop their use both in geochronometry, and in studying erosional processes. Analyses of ⁹Be in dissolved and suspended material from rivers with a wide range of chemical compositions indicate that its geochemistry is

E. T. Brown; J. M. Edmond; G. M. Raisbeck; D. L. Bourles; F. Yiou; C. I. Measures

1992-01-01

370

Uranium in river water  

SciTech Connect

The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains do not represent a significant source of U in river waters. In addition, the authors have determined dissolved U levels in forty rivers from around the world and coupled these data with previous measurements to obtain an estimate for the global flux of dissolved U to the oceans. The average concentration of U in river waters is 1.3 nmol/kg, but this value is biased by very high levels observed in the Ganges-Brahmaputra and Yellow rivers. When these river systems are excluded from the budget, the global average falls to 0.78 nmol/kg. The global riverine U flux lies in the range of 3-6 [times] 10[sup 7] mol/yr. The major uncertainty that restricts the accuracy of this estimate (and that of all other dissolved riverine fluxes) is the difficulty in obtaining representative samples from rivers which show large seasonal and annual variations in runoff and dissolved load.

Palmer, M.R. (Univ. of Bristol (United Kingdom)); Edmond, J.M. (Massachusetts Inst. of Technology, Cambridge, MA (United States))

1993-10-01

371

TROPHIC STRUCTURE AND BIOACCUMULATION OF MERCURY IN FISH OF THREE NATURAL LAKES OF THE BRAZILIAN AMAZON  

E-print Network

TROPHIC STRUCTURE AND BIOACCUMULATION OF MERCURY IN FISH OF THREE NATURAL LAKES OF THE BRAZILIAN was studied in three natural lakes lining the Tapaj´os River, Brazilian Amazon. The Hg content variations-piscivorous and piscivorous fish of the three lakes is observed. The correlation between the mercury concentrations

Long, Bernard

372

Evolution of the lowest amazon basin modeled from the integration of geological and SRTM topographic data  

Microsoft Academic Search

Morphologic features obtained from SRTM data, integrated with geologic information, are emphasized in this paper in order to provide the basis for understanding the development of the lowest Amazon drainage basin, focusing on the history of one of the largest Amazonian tributaries, the Tocantins River, and on the origin of the Marajó Island, throughout the Quaternary. This approach led to

Dilce F. Rossetti; Márcio M. Valeriano

2007-01-01

373

Stable Water Isotopes as Evaluation Tools for Global Climate Model Simulations of the Amazon Basin Circulation  

Microsoft Academic Search

The isotopic abundances of O-18 and Deuterium over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Based on data in the Global Network on Isotopes in Precipitation (GNIP) database, we analyze the simulation of the land surface hydrology and water cycling. Temporal changes between 1965 and 2000 in

K. McGuffie; A. Henderson-Sellers

2003-01-01

374

Influence of the Amazon\\/Orinoco Plume on the summertime Atlantic climate  

Microsoft Academic Search

A plume of fresh water forms in the Atlantic due to discharge from the Amazon and Orinoco rivers and creates a stable barrier layer near the surface that is associated with warm sea surface temperature anomalies (SSTAs). The boreal summer atmospheric response to this sea surface temperature (SST) forcing is investigated using a regional atmospheric model. Results from two ensembles,

Edward K. Vizy; Kerry H. Cook

2010-01-01

375

Aquculture and Deforestation in the Peruvian Amazon  

Microsoft Academic Search

This study examines whether aquaculture has the potential to reduce deforestation in the Peruvian Amazon. The natural resources of the Peruvian Amazon are subject to extreme pressures due to increases in subsistence farming, cattle ranching, and logging in the region. The resulting loss of biodiversity has affected the delicate soil balance that is characteristic of the Amazon, and has contributed

Gator Halpern

2012-01-01

376

Total and inorganic arsenic in freshwater fish and prawn in Thailand.  

PubMed

Total and inorganic arsenic levels were determined in 120 samples of eight freshwater animal species collected from five distribution centers in the central region of Thailand between January and March 2011. Eight species with the highest annual catch, consisting of seven fish species and one prawn species, were analyzed. Concentrations of inorganic arsenic (on a wet weight basis) ranged from 0.010 ?g/g in giant prawn (Macrobrachium rosenbergii) to 0.230 ?g/g in striped snakehead (Channa striata). Climbing perch (Anabas testudineus) exhibited the highest mean concentrations of total arsenic (0.459 ± 0.137 ?g/g), inorganic arsenic (0.121 ± 0.044 ?g/g), and percentage of inorganic arsenic (26.2%). Inorganic arsenic levels found in freshwater animals in this study were much lower than the Thai regulatory standard of 2 ?g/g. PMID:23043844

Saipan, Piyawat; Ruangwises, Suthep; Tengjaroenkul, Bundit; Ruangwises, Nongluck

2012-10-01

377

Effects of extracellular products of Vibrio alginolyticus on penaeid prawn plasma components.  

PubMed

The effects of both crude extracellular products (ECP) and a partially purified protease of Vibrio alginolyticus on the plasma components of kuruma prawn (Penaeus japonicus) and tiger prawn (P. monodon) were studied using crossed immunoelectrophoresis (CIE). A component of the plasma, tentatively identified as coagulogen, apparently disappeared after incubation with the ECP, while the amount of a component tentatively identified as haemocyanin decreased. The coagulogen and an unknown component (component 1) in the penaeid plasma showed an increased migration rate after incubation with a partially purified 33 kDa protease of the bacterium. In contrast, incubation with protease had no detectable effect on the amount of haemocyanin. These events may significantly contribute to the pathogenicity of Vibrio alginolyticus in penaeids. PMID:9281857

Lee, K K; Chen, F R; Yu, S R; Yang, T I; Liu, P C

1997-08-01

378

Hemostasis of tiger prawn Penaeus monodon affected by Vibrio harveyi, extracellular products, and a toxic cysteine protease.  

PubMed

The effects of bacterial cells, extracellular products (ECP) and a purified cysteine protease of Vibrio harveyi on hemostasis and plasma components of tiger prawn (Penaeus monodon) were studied. The clotting ability of the hemolymph withdrawn from moribund prawns pre-injected with the bacteria, ECP, cysteine protease of PBS (control) was observed for 2 h at 25 C. Of these, only the control group was clottable while all the other groups were unclottable. A component of the plasma, previously identified as coagulogen-like protein, was further confirmed to be a coagulogen by the comparison of plasma with serum on non-reduced SDS-PAGE or using rabbit antiserum to the coagulogen-like protein (R alpha coagulogen) to neutralize the clotting ability of normal prawn hemolymph. The coagulogen was reduced in amount in plasma of moribund prawns after injection with the bacteria, ECP or cysteine protease while it apparently disappeared after pre-incubation with the ECP or cysteine protease for 2 h at 25 C compared with normal prawn plasma as observed in crossed immunoelectrophoresis (CIE) gels. The reduction of the amount of coagulogen in plasma of moribund prawns was also evident in CIE gels using R alpha coagulogen. In addition, the apparent disapperance of the coagulogen mentioned above was eventually proven to be due to the change of its migration rate in CIE gels after pre-incubation with ECP or cysteine protease, since the disappeared coagulogen arc (arc 2) (migrated into arc 1) could be visualized by using R alpha coagulogen or by reducing the time for pre-incubation from 2 h to 30 min. Thus, the effects of cysteine protease on plasma coagulogen observed in vitro and in vivo may markedly interfere with hemostasis leading to the occurrence of unclottable hemolymph. These complex events may significantly contribute to the pathogenicity of V. harveyi in the prawn. PMID:10575544

Lee, K K; Chen, Y L; Liu, P C

1999-01-01

379

Effects of different ration levels on survival, moulting and food conversion in two freshwater prawns  

Microsoft Academic Search

Effects of different daily rations of the oligochaete wormTubifex tubifex on survival, moulting and food conversion ofMacrobrachium lanchesteri (Palaemonidae) andCaridina weberi (Atyidae) have been described. Moulting is a metabolic necessity for either species and occurs even at the expense of organic\\u000a reserves of starving prawns. The geometric derivation of the growth-feeding rate relations inM. Lanchesteri indicated that, 88, 162 and

R Ponnuchamy; S Ravichandra Reddy; Katre Shakuntala

1983-01-01

380

The virulence of Enterococcus to freshwater prawn Macrobrachium rosenbergii and its immune resistance under ammonia stress  

Microsoft Academic Search

Growth of pathogen bacterium, Enterococcus was not affected in tryptic soy broth (TSB) medium containing ammonia-N concentration in the range of 0–5·14mg l?1. Giant freshwater prawnMacrobrachium rosenbergii (8–12g) were challenged with Enterococcus which had been incubated for 24h in TSB medium containing different concentrations of ammonia-N at 0–5·14mg l?1. Cumulative mortality of M. rosenbergii was higher for the bacteria incubated

Winton Cheng; Jiann-Chu Chen

2002-01-01

381

A successful microbound diet for the larval culture of freshwater prawn Macrobrachium rosenbergii  

Microsoft Academic Search

A high moisture (63–71%), semi-purified microbound diet containing alginate was compared to newly hatched live Artemia nauplii as an exclusive diet for the culture of larval freshwater prawn Macrobrachium rosenbergii from 5th stage (weighted mean) through metamorphosis to postlarva. Two separate trials, representing larvae from different hatches, were conducted. Larvae were stocked at 50\\/l into cone-shaped vessels that contained 2

Ekaterina E Kovalenko; Louis R D'Abramo; Cortney L Ohs; Randal K Buddington

2002-01-01

382

Transcriptomics of a Giant Freshwater Prawn (Macrobrachium rosenbergii): De Novo Assembly, Annotation and Marker Discovery  

Microsoft Academic Search

BackgroundGiant freshwater prawn (Macrobrachium rosenbergii or GFP), is the most economically important freshwater crustacean species. However, as little is known about its genome, 454 pyrosequencing of cDNA was undertaken to characterise its transcriptome and identify genes important for growth.Methodology and Principal FindingsA collection of 787,731 sequence reads (244.37 Mb) obtained from 454 pyrosequencing analysis of cDNA prepared from muscle, ovary

Hyungtaek Jung; Russell E. Lyons; Hung Dinh; David A. Hurwood; Sean McWilliam; Peter B. Mather

2011-01-01

383

Effect of tributyltin on the early embryonic development in the freshwater prawn Macrobrachium rosenbergii (De Man)  

Microsoft Academic Search

Organotin compounds particularly tributyltin (TBT) has been used as an antifouling biocides. In the present investigation, effects of TBT on the embryonic development, growth, hatchability and hatching success of eggs exposed to TBT were studied in both control and treated groups of the freshwater prawn (brooder) Macrobrachium rosenbergii. Three concentrations viz. 0.78ppm, 1.56ppm and 3.12ppm were selected for treatment. TBT

Peranandam Revathi; Natesan Munuswamy

2010-01-01

384

ALTERNATIVE MATING STRATEGIES IN MALE MORPHOTYPES OF THE FRESHWATER PRAWN MACROBRACHIUM ROSENBERGH (DE MAN)  

Microsoft Academic Search

ABSTRACT Males in a mature, single-age, pond population of the freshwater prawn Macro brachium rosenbergii,can be divided into three distinct morphological types, repre sentingthreephasesin the maledevelopmentalpathway(Brodyet a!., 1980).Behavioral and physical characteristicsof all three morphotypeswere examined with regardto mating behavior and reproductiveprobabilities. Two alternativemating strategiesare described.The largest,dominant males ac tively courtand protectthe femalespriorto mating.Malesof the intermediatecategory demonstrate,a reduced,rate of reproductive,activities in

Ziva Ra'anan; Amir Sagi

385

Serotonin induces ovarian maturation in giant freshwater prawn broodstock, Macrobrachium rosenbergii de Man  

Microsoft Academic Search

This study investigated the effects of serotonin (5-hydroxytryptamine or 5HT) on ovarian development in Macrobrachium rosenbergii de Man. Adult female prawns at the ovarian stage I (spent) were injected with 5HT at 1, 5, 10, 20 and 50 ?g g?1 body weight (BW) intramuscularly on days 0, 5 and 10, and sacrificed on day 15. The doses as related to the

Prasert Meeratana; Boonsirm Withyachumnarnkul; Praneet Damrongphol; Kanokphan Wongprasert; Anchalee Suseangtham; Prasert Sobhon

2006-01-01

386

USING DIFFERENT SHELTER AREAS ON NURSING OF GIANT FRESHWATER PRAWN, Macrobrachium rosenbergii (de Man, 1879) POSTLARVA  

Microsoft Academic Search

Nursing of giant freshwater prawn, Macrobrachium rosenbergii (de Man, 1879) from the postlarval stage to the size of 2 cm with six different sizes shelters, including 0, 2, 4, 6, 8 and 10 m 2 , respectively. The experiment was carried out in 2.5 m diameter cement tank, contained 2.5 m 3 filtered water in 0.5 m water level. The

Supat Sripat; Nipon Chanprathad

387

Effects of dissolved oxygen on hemolymph parameters of freshwater giant prawn, Macrobrachium rosenbergii (de Man)  

Microsoft Academic Search

Profiles of changes in physiological parameters of freshwater giant prawns, Macrobrachium rosenbergii, exposed to various dissolved oxygen (DO) levels of 7.75, 4.75, 2.75, and 1.75 mg l?1 are reported. The parameters involved in osmoregulation and oxygen transport were monitored for a 6-day period. Notable depressions in hemolymph osmolality, Na+, K+, and Cl? contents were observed within 24 h after exposure

Winton Cheng; Chun-Hung Liu; Ching-Ming Kuo

2003-01-01

388

Salinity effects on reproduction of giant freshwater prawn Macrobrachium rosenbergii (de Man)  

Microsoft Academic Search

Understanding the role of salinity in breeding and growth has the potential to enhance production of giant freshwater prawn, Macrobrachium rosenbergii. This study investigated the reproduction of females reared in salinities of 0, 6, 12, and 18 g L?1. Mean weight of females decreased with increased salinity (31.40±1.54, 25.14±1.16, 20.80±0.81, and 16.62±1.04 g at 0, 6, 12, and 18 g L?1, respectively). Larval

Pham Truong Yen; Amrit N. Bart

2008-01-01

389

Identification of the major allergen of Macrobrachium rosenbergii (giant freshwater prawn)  

PubMed Central

Objective To characterize the major allergens of Macrobrachium rosenbergii (giant freshwater prawn). Methods Raw and cooked extracts of the giant freshwater prawn were prepared. The IgE reactivity pattern was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting technique with the sera of 20 skin prick test (SPT) positive patients. The major allergen identified was then characterized using the proteomics approach involving a combination of two-dimensional (2-DE) electrophoresis, mass spectrometry and bioinformatics tools. Results SDS-PAGE of the raw extract showed 23 protein bands (15–250 kDa) but those ranging from 40 to 100 kDa were not found in the cooked extract. From immunoblotting experiments, raw and cooked extracts demonstrated 11 and 5 IgE-binding proteins, respectively, with a molecular mass ranging from 15 to 155 kDa. A heat-resistant 36 kDa protein was identified as the major allergen of both extracts. In addition, a 42 kDa heat-sensitive protein was shown to be a major allergen of the raw extract. The 2-DE gel fractionated the prawn proteins to more than 50 different protein spots. Of these, 10 spots showed specific IgE reactivity with patients' sera. Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis led to identification of 2 important allergens, tropomyosin and arginine kinase. Conclusions It can be concluded that the availability of such allergens would help in component-based diagnosis and therapy of prawn allergies. PMID:23569834

Yadzir, Zailatul Hani Mohamad; Misnan, Rosmilah; Abdullah, Noormalin; Bakhtiar, Faizal; Arip, Masita; Murad, Shahnaz

2012-01-01

390

Stratigraphic age, sedimentation rate and source rocks of the Amazon Fan  

NASA Astrophysics Data System (ADS)

The evolution of Amazon Fan, a large sedimentary structure at the Brazilian passive margin, is directly connected with the Andean mountains and the Amazon River development. Sr, Nd and Pb isotopes studies combined with palynological information have been conducted in Late Miocene to Pleistocene section of the Amazon submarine fan to constrain the sedimentary age, source rocks and sedimentation rate of main sedimentary sequences deposited during the period. Age of the sedimentary rocks were inferred from the palynological data and Sr isotope signature from foraminifers, integrated with seismic and drill holes data. The whole section had a very high sedimentation rate with significant increase in the last 3 Ma, from Late Pliocene to present, which it may be related to uplift of the continental margin as a result of isotastic compensation due to load of Amazon Fan sedimentary package deposited from Late Miocene to Early Pliocene and main uplift of the Northern Andes. Although the most foraminifera shells have 87Sr/86Sr ratio in the range of the expected value for the estimated age, there were samples with 87Sr/86Sr ratio lower and higher than those used for the Sr isotope curve. The increase of 87Sr/86Sr ratio is assigned to Amazon River strontium fluxes whereas lower ratios may be due to diagenetic processes or fluid percolation driven by thick sedimentary overload, as much as 10,000 m, in the Amazon submarine fan. Contribution of the Precambrian rocks of the Amazonian Craton versus Andean rocks as source of the sediments for Amazon Fan during its evolution was estimated by the Sm-Nd and Pb isotope data in the pelitic rocks. Nd and Pb isotopes in fine-grained sediments allowed to identify both signal, where contribution Precambrian basement rocks are recognized by Archean and Paleoproterozoic Nd model ages and higher radiogenic Pb signature.

Chemale Junior, Farid; Ayup, Ricardo N.; Barboza, Eduardo; Moura, Candido A. V.

2014-05-01

391

Long-term simulations of discharge and floods in the Amazon Basin  

NASA Astrophysics Data System (ADS)

A terrestrial ecosystem model (integrated biosphere simulator (IBIS)) and a hydrological routing algorithm (HYDRA) are used in conjunction with long time series climate data to simulate the river discharge and flooded area of the Amazon/Tocantins River basin over the last 60 years. Evaluating the results of this modeling exercise over the entire basin yields three major results: (1) Observations at 121 stations throughout the basin show that discharge is well simulated for most tributaries originating in Brazil. However, the discharge is consistently underestimated, by greater than 20%, for tributaries draining regions outside of Brazil and the main stem of the Amazon. The discharge underestimation is most likely a result of underestimated precipitation in the data set used as model input. (2) A new flooding algorithm within HYDRA captures the magnitude and timing of the river height and flooded area in relatively good agreement with observations, particularly downstream of the confluence of the Negro and Solimões Rivers. (3) Climatic variability strongly impacts the hydrology of the basin. Specifically, we find that short (~3-4 years) and long (~28 years) modes of precipitation variability drive spatial and temporal variability in river discharge and flooded area throughout the Amazon/Tocantins River basins.

Coe, Michael T.; Costa, Marcos Heil; Botta, Aurélie; Birkett, Charon

2002-08-01

392

Long-term Simulations of Discharge and Floods in the Amazon Basin  

NASA Astrophysics Data System (ADS)

A terrestrial ecosystem model (IBIS) and a hydrological routing algorithm (HYDRA) are used in conjunction with long time-series climate data to simulate the river discharge and flooded area of the Amazon/Tocantins River Basin over the last 60 years. Evaluating the results of this modeling exercise over the entire basin against land and satellite based observations yields three major results: (1) Observations at 121 stations throughout the basin show that discharge is well simulated for most tributaries originating in Brazil. However, the discharge is consistently underestimated, by greater than 20%, for tributaries draining regions outside of Brazil and the main stem of the Amazon. The discharge underestimation is most likely a result of underestimated precipitation in the data set used as model input. (2) A new flooding algorithm within HYDRA captures the magnitude and timing of the river height, and flooded area in relatively good agreement with satellite based observations, particularly downstream of the confluence of the Negro and Solimões Rivers. (3) Climatic variability strongly impacts the hydrology of the basin. Specifically, we find that short ( ~3-4 year) and long ( ~28 year) modes of precipitation variability drive spatial and temporal variability in river discharge and flooded area throughout the Amazon/Tocantins River basins.

Coe, M. T.; Costa, M. H.; Botta, A.; Birkett, C.

2001-12-01

393

Sedimentation of the Brazos River System: Storage in the Lower River, Transport to Shelf and the Evolution of a Modern Subaqueous Delta  

E-print Network

of a river or estuary to the coastal ocean. For example, during the times of high discharge on the Amazon River, the salt front can be displaced from the river over 100 km from the mouth, both across the shelf as well as hundreds of kilometers along... of a river or estuary to the coastal ocean. For example, during the times of high discharge on the Amazon River, the salt front can be displaced from the river over 100 km from the mouth, both across the shelf as well as hundreds of kilometers along...

Carlin, Joseph A

2013-07-13

394

Sex and the Syndrome: Individual and Population Consistency in Behaviour in Rock Pool Prawn Palaemon elegans  

PubMed Central

Animal personality has been widely documented across a range of species. The concept of personality is composed of individual behavioural consistency across time and between situations, and also behavioural trait correlations known as behavioural syndromes. Whilst many studies have now investigated the stability of individual personality traits, few have analysed the stability over time of entire behavioural syndromes. Here we present data from a behavioural study of rock pool prawns. We show that prawns are temporally consistent in a range of behaviours, including activity, exploration and boldness, and also that a behavioural syndrome is evident in this population. We find correlations between many behavioural traits (activity, boldness, shoaling and exploration). In addition, behavioural syndrome structure was consistent over time. Finally, few studies have explicitly studied the role of sex differences in personality traits, behavioural consistency and syndrome structure. We report behavioural differences between male and female prawns but no differences in patterns of consistency. Our study adds to the growing literature on animal personality, and provides evidence showing that syndromes themselves can exhibit temporal consistency. PMID:23555034

Chapman, Ben B.; Hegg, Alexander; Ljungberg, Peter

2013-01-01

395

Nutrient budgets and effluent characteristics in giant freshwater prawn (Macrobrachium rosenbergii) culture ponds.  

PubMed

It is important to understand nutrient budgets of aquaculture practices for efficiency of input resources and to utilize all output nutrient sources. The aim of the present study was to develop a nutrient budget for giant freshwater prawn (Macrobrachium rosenbergii) culture ponds. The study was conducted in farmer's ponds (0.25-0.5 ha) of Odisha, India, and the results showed that feed accounted 97% total nitrogen (N), 98.7% total phosphorus (P) and 90% total organic carbon (OC), respectively. The harvested prawn accounted for recovery of 37% N, 10% P and 15% OC, respectively. The N, P and OC accumulated in sediment were 52%, 76%, and 65%, respectively. Nutrient loads in the effluents were 2.22 ± 0.66 kg inorganic N, 0.40 ± 0.15 kg P, and 21.01 ± 6.4 kg OC per ton of prawn production. The present study implicated that high nutrient values observed in both water and sediment provide important opportunities for nutrient reuse through pond sediment applications to croplands as an organic manure, as well as pond water irrigation to crops as a "liquid fertilizer". PMID:24522829

Adhikari, Subhendu; Sahu, Bharat Chandra; Mahapatra, Abhijit S; Dey, Lambodar

2014-05-01

396

The Concentrations of Vitellogenin (Vitellin) and Protein in Hemolymph, Ovary and Hepatopancreas in Different Ovarian Stages of the Freshwater Prawn, Macrobrachium rosenbergii  

Microsoft Academic Search

The objectives were to measure the concentrations of vitellogenin (vitellin) and protein in hemolymph, ovary, and hepatopancreas of the freshwater prawn, Macrobrachium rosenbergii, in different stages of ovarian development. The ovarian development of M. rosenbergii was classified into five developmental stages (Stages I–V). Vitellogenin concentrations increased in the hemolymph of prawns in the early stages of ovarian development (Stage I

Fang-Yi Lee; Ching-Fong Chang

1997-01-01

397

Cosmogenic nuclide-derived sediment budget of the Amazon basin  

NASA Astrophysics Data System (ADS)

Sediment gauging suggests that the annual sediment mass discharged into the main Amazon basin from the Andes and the cratonic shields is not in steady state with the mass discharged to the Atlantic Ocean. Here we use sediment production rates from cosmogenic 10Be in sediment to compare these with transport rates from river load gauging. About 1 million km2 or 95% of the total Andean area draining to the Amazon provide sediment to the central Amazon river with an averaged 10Be nuclide concentration of 5.0 +- 0.5x1e4 at/g(Qz). Average nuclide concentrations for Brazilian shield headwaters amount to 15.3 +- 1.2x1e4 at/g(Qz), and to 38.6 +- 2.4x1e4 at/g(Qz) for the Guyana shield headwaters, respectively. For the Andes, nuclide concentrations translate to an integrated Andean denudation rate of 0.35 ± 0.05 mm/yr. Sediment from the headwaters of the Brazilian and Guyana shields translate into very low denudation rates (0.02 and 0.01 mm/yr, respectively), as is expected for tectonically stable tropical highlands. These headwater 10Be nuclide concentrations and derived denudation rates can now be compared with those derived from central Amazon stream sediment including the main Amazon, which was sampled over ~1000 km from Manaus to Óbidos. Cosmogenic nuclide concentration analyses of several grain sizes (from 125 up to 800 µm) show large variations; we found that coarse-grained material records the nuclide signal of the cratonic shield areas, whereas the Andean signal is best represented by the fine sand fraction, which is preserved virtually unaltered over 1000s of km of sediment transport. In all central Amazon trunk stream samples and tributaries, the fine grain size fraction (125-250 µm) contains 10Be at 6.5 +- 1.2x1e4 at/g(Qz), which is similar to that of the Andean source areas. The integrated denudation rate from this fraction is 0.23 +- 0.04 mm/yr for the entire Amazon basin at Óbidos, which compares well with the mean Andean denudation rate of 0.35 +- 0.05 mm/yr. Coarse grain sizes (>500 µm) record the very low denudation rate of the cratonic shields. Given these low rates, the shields discharge only small amounts of sediment into the Amazon trunk stream. Multiplied with the area of the providing hinterland, we can use these erosion rates to calculate sediment mass budgets. The flux of sediment expected from cosmogenic nuclide-based denudation rates amounts to 540 Mt/yr at Óbidos. This flux compares to the total load of 1100 Mt/yr at Óbidos[1,2,3] as estimated from sediment gauging. This disparity is unexpected, as today at least 40% of the sediment discharged from the Andes is stored in floodplains[4]; a process not detected with cosmogenic 10Be. The longer denudation integration time scale of 8 kyr for cosmogenic nuclides possibly includes a period of drier climate than the wet conditions during the late Holocene, where a wetter modern climate possibly favors more rapid erosion in the Andes and more efficient sediment transport in the large rivers. 1 Gaillardet et al. (1997), Chemical Geology (142), 141-173. 2 Dunne et al. (1998), GSA Bulletin (110), 450-467. 3 Guyot et al. (2005), IAHS Publications (291), 1-8. 4 Guyot et al. (1996), IAHS Publications (236), 55-63.

Wittmann, Dr.; von Blanckenburg, Dr.; Guyot, Dr.; Maurice, Dr.; Kubik, Dr.

2009-04-01

398

Repeat-Pass Multi-Temporal Interferometric SAR Coherence Variations with Amazon Floodplain and Lake Habitats  

NASA Astrophysics Data System (ADS)

Monitoring discharge in the main channels of rivers and upland tributaries as well as storage changes in floodplain lakes is necessary for understanding flooding hazards, methane production, sediment transport, and nutrient exchange. Interferometric processing of synthetic aperture radar (SAR) data may enable hydrologists to detect environmental and ecological changes in hydrological systems over space and time. An aim of our experiments is to characterize interferometric SAR coherence variations that occur in Amazon aquatic habitats. We analyze coherence variations in JERS-1 data at three central Amazon sites; Lake Balbina, the Cabaliana floodplain, and the confluence of the Purus and Amazon rivers. Because radar pulse interactions with inundated vegetation typically follow a double-bounce travel path which returns energy to the antenna, coherence will vary with vegetation type, physical baseline, and temporal baseline. Balbina's vegetation consists mostly of forest and inundated trunks of dead, leafless trees as opposed to Cabaliana and Amazon- Purus (dominated by flooded forests), thus it serves to isolate the vegetation signal. Coherence variations with baselines were determined from 253 interferograms at Balbina, 210 at Calbaliana, and 153 at Purus. The average temporal and perpendicular baselines (mean std.) are 574 394 days and 1708 1159 m at Balbina, 637 435 days and 1381 981 m at Cabaliana, and 587 425 days and 1430 964 m at Purus. Balbina has a stronger coherence than either Cabaliana or Amazon-Purus. With results of Mann-Whitney statistical tests, Balbina has a difference between terre-firme and flooded coherence values plotted with perpendicular baseline but Cabaliana and Amazon-Purus do not show this difference. Balbina has a linearly decreasing trend in coherence plotted with temporal baseline whereas Cabaliana and Amazon-Purus have a steep drop-off, non- linear change. A strong annual periodicity is evident on power spectrums of the coherence values for Cabaliana and Amazon-Purus, but not in Balbina and is likely an indicator of the annual Amazon flood wave. Each ecological habitat is delineated in the Balbina coherence values plotted with temporal baseline, but only during high water and time-periods less than 2 years is such delineation visible in the Cabaliana and Amazon-Purus regions. Taken together, these observations suggest terre-firme does not have a seasonal variation whereas flooded areas vary with the season.

Jung, H.; Alsdorf, D.

2006-12-01

399

Comparison of river basin hydrometeorology in ERA-Interim and ERA-40 reanalyses with observations  

E-print Network

. For the Mississippi and Mackenzie river basins, the spin-up of precipitation in 24-h forecasts has been greatly in both seasons. For the Mackenzie river basin, similar reflective cloud changes in ERA-Interim improve] of three American river basins, the Amazon, Mississippi and Mackenzie Rivers, was compared against

400

Jotï ecogony, Venezuelan Amazon  

NASA Astrophysics Data System (ADS)

The current environmental crisis permeates the discourse and concerns of people all over the world. Consideration of diverse environmental ethics showing the alternative ways in which people conceptualize and relate to nature and natural resources are critical for bringing about more sustainable human behaviors. After a brief review of Western historical notions of nature, this work explores the ecogony, or causal reasons, that trigger the behavior of the Jotï, an Amerindian people of the Venezuelan Amazon, with other entities and the forest that they inhabit. The analysis presented synthesizes 15 years of transdisciplinary ethno-ecological research comprising quantitative and qualitative methods (collection of herbarium voucher specimens, floristic inventories in forest plots, structured interviews focused on plot vegetation, semi-structured interviews of life-histories, participant observation, time allocation studies, food resource accounting, focal person following observations, garden crop inventories and censuses, mapping of wild resource harvest locations, among others). Jotï pragmatic and ideological tenets generate a distinctive environmental ethics based on ecogonic nodes. Notions of interdependence, humanity and person are articulated on a daily basis through several dynamics: (1) hyper-awareness of all living things’ dependence on each other and other elements of the biophysical environment at macroscales and microscales, (2) the construction of human spiritual, conscious, physical and agentive constituents from a variety of diverse botanical and zoological species and mineral components of their homeland, and (3) an understanding of the aggregate surroundings, including a significant portion of the biotic and abiotic components, as potential subjects with awareness, creativity and moral stances. This condition of interdependence confers rights and duties on all the parts. Jotï horizontal communications with and among life-forms sustain their condition as committed actors in the configuration of the forests that they inhabit.

Zent, Egleé L.

2013-03-01

401

Cyclic sediment deposition within Amazon deep-sea fan  

SciTech Connect

The Upper and middle Amazon Fan has grown in a cyclic fashion. An individual deposition cycle consists of (1) a widespread basal, acoustically transparent seismic unit (interpreted as debris-flow deposits) that fills and levels preexisting topographic lows, and (2) a levee complex built of overlapping channel-levee systems. Two and possibly three cycles have been identified within the Amazon Fan. The levee complex beneath one debris flow originated from a different submarine canyon than did the levee complex above the debris flow, suggesting that these levee complexes formed during different sea level lowstands. Calculations based on present sediment discharge of the Amazon River suggest that an entire levee complex can form within the time span of a single glacial stage, such as the Wisconsin; however, the levee complex probably could not have formed during the relatively short time interval when sea level rose rapidly at the end of a glacial stage. The basal seismic units (debris-flow deposits) may have been deposited at any time during sea level fluctuations. Although seismic evidence suggests that this cyclic sedimentation pattern may be related to glacio-eustatic sea level variations, cyclic fan growth may be attributed to other processes as well. For example, a bottom-simulating reflector (BSR) observed within the upper fan appears to be a gas hydrate. Migration of the hydrate phase boundary during sea level fluctuations and diapiric activity may be mechanisms for initiating widespread debris flows. 10 figs.

Manley, P.L.; Flood, R.D.

1988-08-01

402

Weather types and rainfall in the Amazon basin  

NASA Astrophysics Data System (ADS)

A neuronal method (Self Organizing Maps or SOMs) is used to identify weather types over tropical South America from total wind at 850 hPa in ERA-40 reanalysis. Weather types are associated with daily rainfall in two regions of the Amazon basin where the long term hydrologic variability is the strongest. In the south-western basin, important rainfall is associated with a weather type characterized by negative geopotential anomalies over the Chaco region and positive ones behind, that promote the convergence of north-western wind anomalies (monsoon flux around summer) and southern anomalies over the Bolivian lowlands. In the north-western Amazon basin, important rainfall is associated with a weather regime characterized by positive geopotential anomalies over the Chaco region that promote strong southern wind anomalies over western Amazon and their convergence with the trade winds. We show that the progression of extra tropical perturbations and their incursion toward low latitude, favoured by the N-S orientation of the Andes, partly control the characteristics of weather types over tropical South America. The frequency of weather regimes allows explaining partially rainfall variability at interannual and pluriannual time scales. In addition, weather type's frequency is able to explain the occurrence of exceptional floods in the Amazonian Basin Rivers.

Espinoza, J. C.; Lengaigne, M.; Ronchail, J.; Janicot, S.; Guyot, J. L.

2009-04-01

403

Amazon Deforestation and Climate Change  

Microsoft Academic Search

A coupled numerical model of the global atmosphere and biosphere has been used to assess the effects of Amazon deforestation on the regional and global climate. When the tropical forests in the model were replaced by degraded grass (pasture), there was a significant increase in surface temperature and a decrease in evapotranspiration and precipitation over Amazonia. In the simulation, the

J. Shukla; C. Nobre; P. Sellers

1990-01-01

404

Amazon RainForest Fires  

Microsoft Academic Search

Charcoal is common in the soils of mature rain forests within 75 kilometers of San Carlos de Rio Negro in the north central Amazon Basin. Carbon-14 dates of soil charcoal from this region indicate that numerous fires have occurred since the mid-Holocene epoch. Charcoal is most common in tierra firme forest Oxisols and Ultisols and less common in caatinga and

Robert L. Sanford; Juan Saldarriaga; Kathleen E. Clark; Christopher Uhl; Rafael Herrera