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1

Larval Pseudoproleptus sp. (Nematoda: Cystidicolidae) found in the Amazon river prawn Macrobrachium amazonicum (Decapoda: Palaemonidae) in Brazil.  

PubMed

Previously undescribed infective larvae of the cystidicolid nematode Pseudoproleptus sp. (probably conspecific with the nematode originally described as Heliconema izecksohni Fabio, 1982, a parasite of freshwater fish in Brazil), were found encapsulated in the hemocel of the Amazon river prawn Macrobrachium amazonicum (Heller) (Decapoda: Palaemonidae) from the natural canals on the Mexiana Island (Amazon River Delta), Pardá State, Brazil. The prevalence in prawns (body length 48-110 mm) examined in January and March 2008 (n = 44) was 32%, with an intensity of 1-6 (mean 2) larvae per crustacean. The nematode larvae (body length 19.7-25.7 mm), characterized by the cephalic end provided with a helmet-like cuticular structure having a thickened free posterior margin, are described based on light and scanning electron microscopy. Apparently prawns play a role as intermediate hosts for this nematode species. This is the first record of a larval representative of Cystidicolidae in South America and the first record of a species of Pseudoproleptus Khera, 1955, in the Neotropics. Heliconema izecksohni is transferred to Pseudoproleptus as Pseudoproleptus izecksohni (Fabio, 1982) n. comb. PMID:19014207

Moravec, Frantisek; Santos, Cláudia P

2009-06-01

2

Social, economic, and production characteristics of giant river prawn Macrobrachium rosenbergii culture in Thailand  

Microsoft Academic Search

The objective of this study was to review the state of grow-out production for giant river prawns (Macrobrachium rosenbergii) in Thailand, assess the perceived ecological impacts of the industry, and suggest avenues by which farmers might adopt more environmentally sound culture systems. A socioeconomic and technical survey of 100 prawn farmers was conducted during 1 May to 31 July 2005

Vicki S. Schwantes; James S. Diana; Yang Yi

2009-01-01

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.

U.S. Geological Survey

1967-01-01

4

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

5

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

6

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

7

cDNA Cloning and Expression Analysis of Gustavus Gene in the Oriental River Prawn Macrobrachium nipponense  

PubMed Central

The gustavus gene is required for localizing pole plasm and specifying germ cells. Research on gustavus gene expression will advance our understanding of the biological function of gustavus in animals. A cDNA encoding gustavus protein was identified and termed MnGus in the oriental river prawn Macrobrachium nipponense. Bioinformatic analyses showed that this gene encoded a protein of 262 amino acids and the protein belongs to the Spsb1 family. Real-time quantitative PCR analyses revealed that the expression level of MnGus in prawn embryos was slightly higher at the cleavage stage than at the blastula stage, and reached the maximum level during the zoea stage of embryos. The minimum level of MnGus expression occurred during the perinucleolus stage in the ovary, while the maximum was at the oil globule stage, and then the level of MnGus expression gradually decreased with the advancement of ovarian development. The expression level of MnGus in muscle was much higher than that in other tissues in mature prawn. The gustavus cDNA sequence was firstly cloned from the oriental river prawn and the pattern of gene expression was described during oocyte maturation, embryonic development, and in other tissues. The differential expression patterns of MnGus in the embryo, ovary and other somatic tissues suggest that the gustavus gene performs multiple physiological functions in the oriental river prawn.

Zhang, Fengying; Chen, Liqiao; Qin, Jianguang; Zhao, Weihong; Wu, Ping; Yu, Na; Ma, Lingbo

2011-01-01

8

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

9

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

10

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

11

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

12

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

13

Screening of parasitic and IHHNV infections in wild giant freshwater prawn Macrobrachium rosenbergii from Rejang River at Kuching, Sarawak.  

PubMed

A preliminary survey of parasitic and infectious hypodermal and haematopoietic necrosis virus (IHHNV) infections in giant freshwater prawn from the Damak Sea of Rejang River, Kuching, Sarawak was conducted. Symptoms of black spots/patches on the rostrum, carapace, pleopods or telson were observed in most of the 107 samples collected. Parasitic examination revealed sessiline peritrichs such as (Zoothamnium sp.), nematode larvae, gregarine stage and cocoon of leech with prevalences of 1.2%, 1.2%, 5% and 17% respectively. Under histopathological examination, changes like accumulation of hemocytes around hepatopancreatic tubules due to vibriosis, basophilic intranuclear inclusions in the epithelium and E-cell of hepatopancreatic tubules as a result of HPV were seen through the section. No positive infection of IHHNV was detected in 78 samples. As such, the wild giant freshwater prawns in Damak Sea of Rejang River in Kuching are IHHNV-free though infections of parvo-like virus and bacteria were seen in histopathology. PMID:21602773

Kua, Beng Chu; Choong, F C; Hazreen Nita, M K; Muhd Faizul H, A H; Bhassu, S; Imelda, R R; Mohammed, M

2011-04-01

14

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

15

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

16

Seasonality of Reproduction in Amazon River Dolphins (Inia geoffrensis) in Three Major River Basins of South America  

Microsoft Academic Search

Reproduction of Amazon River Dolphins, Inia geoffrensis, is generally reported to be highly seasonal; however, this conclusion is based on studies from only one area of Inia distribution from throughout the Amazon and Orinoco river basins. Our observations of live dolphins from the Orinoco, Amazon, and Mamore river basins (in Venezuela, Peru and Bolivia, respectively) indicate that reproduction in Inia

Tamara L. McGuire; Enzo R. Aliaga-Rossel

2007-01-01

17

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

18

Genetic variation based on microsatellite analysis of the oriental river prawn, Macrobrachium nipponense from Qiandao Lake in China.  

PubMed

The oriental river prawn (Macrobrachium nipponense) is an important freshwater prawn species in China. We collected 236 oriental river prawns from four wild stocks from Qiandao Lake, Zhejiang, China, and used nine polymorphic microsatellite markers to investigate their genetic diversity and structure, to facilitate the development of a selective breeding program. We found 185 alleles at nine loci in this sample. The observed heterozygosity (H(O)) and expected heterozygosity (H(E)) ranged from 0.43 to 0.89 and 0.56 to 0.95, respectively. The four stocks of M. nipponense displayed high genetic diversity (14.33-15.89 alleles/locus, H(O) = 0.66-0.77 and H(E) = 0.78-0.88). Genetic diversity of the stock from Weiping town was lower than the stocks from the other locations. Mutation-drift equilibrium analysis showed no significant bottleneck effect. F-statistics among stocks ranged from 0.03 to 0.07, indicating a moderate level of differentiation. Based on genetic structure analysis, the 236 individuals from the four wild stocks could be divided into two potential populations. Overall, the 09CA, 09AY and 09JJ wild stocks had higher allelic and genetic diversity than the upstream 09WP stock. These three wild stocks could be used as founders for selective breeding. PMID:23079984

Ma, K Y; Feng, J B; Li, J L

2012-12-06

19

Trace Elements and Radionuclides in the Connecticut River and Amazon River Estuary.  

National Technical Information Service (NTIS)

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 an...

E. P. Dion

1983-01-01

20

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

21

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

22

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

23

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

24

Nutrient and phytoplankton biomass in the Amazon River shelf waters.  

PubMed

The Amazon River estuary is notable at the Amazon Continental Shelf, where the presence of the large amount of water originating from the Amazon during the river's falling discharge period was made evident by the low salinity values and high nutrient levels. Even so, the presence of oceanic waters in the shelf area was significant. Dissolved organic nitrogen was the predominant species of the nitrogen cycle phases, followed by total particulate nitrogen, nitrate, ammonium and nitrite. The chlorophyll a data in the eutrophic area indicated that there is sufficient nitrogen in the area to withstand productivity, though dissolved inorganic nitrogen removal processes are faster than regeneration or mineralization. The anomalous amounts of inorganic dissolved nitrogen showed more removal than addition. The simulations with the bidimensional MAAC-2D model confirmed that high nutrient waters are displaced northwest-ward (two cores at 2.5 degrees N-50 degrees W and 4 degrees N-51 degrees W) by the stronger NBC during falling river discharge. During high river flow period these nutrient-rich lenses are distributed around 0.5 degrees N-48.5 degrees W as well as along the shallow Amazonian shelf (20 m-50 m depth, 1 degree N-3.5 degrees N), as a result of the spreading of Amazon freshwater outflow. PMID:19039493

Santos, Maria L S; Muniz, Kátia; Barros-Neto, Benício; Araujo, Moacyr

2008-12-01

25

Biological uptake of dissolved silica in the Amazon river estuary.  

PubMed

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 they deposit in dunes and layers on and within mud and sand bars. PMID:17789156

Milliman, J D; Boyle, E

1975-09-19

26

Seasonality of Rare Earth Element concentrations and fluxes in the Amazon river and its main tributaries  

Microsoft Academic Search

Many studies carried out on the Amazon River illustrate the complex functioning of this river in terms of geochemistry. Concerning the REE, (Sholkovitz and Szymczak 2000) and (Hannigan and Sholkovitz 2001, Gerard et al, 2003) summarized the actual knowledge we have on the Amazon river. In this study we present a 2-year time series on dissolved REE geochemistry in the

P. Seyler; J. Sonke; J. Viers; G. Barroux; G. R. Boaventura; T. Rousseau

2008-01-01

27

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

28

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

29

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

30

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

31

South America South of the Amazon River--A Climatological Study.  

National Technical Information Service (NTIS)

A climatological study of South America south of the Amazon River. The study area includes Brazil south of the Amazon, Peru south of 5 degrees south and south of the Maranon River, and the countries of Argentina, Bolivia, Chile, Paraguay and Uruguay. It a...

M. T. Gilford M. J. Vojtesak G. Myles R. C. Bonam D. L. Martens

1992-01-01

32

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

33

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

34

Watershed Metabolism Expression in Rivers of the Amazon  

NASA Astrophysics Data System (ADS)

The Amazon basin holds a wide variety of river waters with characteristic chemical signatures imprinted by basin geomorphology, rock types and weathering environments. Extremely contrasting cases are rivers such as the Solimoes, which drains Andean terrain with resulting high ionic content and suspended sediments and the ionic-poor blackish waters of the Negro, which drains highly weathered flat terrain. Such differences in landscape and water types translate into distinct seasonal patterns in their chemical composition. However, when biogenic species are concerned (such as dissolved gases O2 and CO2) rivers of all types and scales we have studied at Amazon present the same seasonal pattern. From the larger tributaries Solimoes and Negro to headwater streams of first order in Mato Grosso and Rondonia, DOC and CO2 increase with discharge, whereas O2 and pH decrease. Our results from smaller scale headwater streams show that seasonality in stream water follows precisely respiration in forest soils, indicating a tight land-water connection at this scale that probably propagates in the riverine network to express the functioning of the watershed as an integrated unit of the landscape.

Krusche, A. V.; Ballester, M. V.; Victoria, R. L.; Montebelo, A.; da Cunha, H. B.; Neu, V.; Richey, J. E.

2011-12-01

35

Mercury in the Tapajós River basin, Brazilian Amazon: a review.  

PubMed

This paper presents a review about mercury contamination and human exposure in the Tapajós River basin (Brazil), one of the major tributaries of the Amazon impacted by traditional gold mining from the mid 1980s. The most recent review in this region was published more than ten years ago and since then many articles about environment and especially human populations have revealed new aspects of mercury toxicology. Additionally, new biomarkers of mercury exposure and toxicity have been studied in these populations. However, there are still many open, about both mercury's biogeochemical cycle and mercury health risks. Further environmental and human risk research directions are proposed. PMID:20483161

Berzas Nevado, J J; Rodríguez Martín-Doimeadios, R C; Guzmán Bernardo, F J; Jiménez Moreno, M; Herculano, A M; do Nascimento, J L M; Crespo-López, M E

2010-05-16

36

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.

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

2011-01-01

37

Similarities and differences between a large meandering river and an anabranching river: the Ucayali and Amazon River cases  

NASA Astrophysics Data System (ADS)

The Ucayali is one of the largest freely meandering rivers in the world and its planform migration produces complex meander shapes dominated by not only fluvial erosion but mainly geotechnical processes since changes on water stage are appreciable compared to medium- and small-meander rivers. The Amazon is one of the largest anabranching rivers in the world and it is formed by the confluence of the anabranching Marañon River together with the meandering Ucayali River. The seasonal increase and decrease in water and sediment discharges from the Amazonian lowland rivers produce changes in the river’s planform configuration, river flooding, and streambank erosion affecting nearby towns and navigation and shoaling issues. Even though, extensive work has been dedicated to understand both river systems, there is still no absolute understanding of their physically-based formation processes and dynamics, especially at large scales as these lowland Amazonian rivers. The Ucayali Meandering River migrates at greater rates than the Amazon Anabranching River mainly due to their single channel condition; however localized secondary channels of the latter could behave as meandering channels dominating and modifying the planform dynamics of the entire anabranching system. Insights on how a large meandering river (Ucayali) is similar and at the same time different from an anabranching river (Amazon) will be described herein. A team composed of the Earth Processes & Environmental Flows Group (EPEF) at the University of Pittsburgh and the Directorate of Hydrology and Navigation (DHN) from the Peruvian Navy is working towards gathering information and field measurements concerning the dynamics of the Amazonian rivers. Therefore, based on three-dimensional velocity and bed morphodynamic measurements (performed in both river systems using acoustic profilers and echo sounders respectively) combined with mathematical hydrodynamic models, some insights on the flow structure, bed morphology and planform dynamics of large meandering and anabranching systems are presented.

Abad, J. D.; Paredes, J. R.; Montoro, H.

2010-12-01

38

Prawn Park - Taupo, New Zealand  

SciTech Connect

A freshwater prawn farm enterprise was established in 1987 in New Zealand to make use of geothermal waste heat from the Wairakei power generating field on the North Island. Approximately 2200 tons of prawns are imported each year into New Zealand, therefore, an effort was initiated to try and capture some of this market with a domestic product. Presently, there are 19 ponds varying in size from 0.2 to 0.35 ha (0.5 to 0.9 acres) with an average temperature of 24{degrees}C. The water comes from two different sources: river water and heated water from the plate heat exchanger. The farm is presently capable of producing up to 30 tonnes (33 tons) of prawns per annum of prawns, with plans for expansion of the operation in the near future.

Lund, J.W.; Klein, R. [Prawn Park, Taupo (New Zealand)

1995-10-01

39

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

40

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

41

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

42

Spatio-temporal geochemistry of mercury in the waters of the Tapajós and Amazon rivers, Brazil  

Microsoft Academic Search

Spatial and temporal variations of mercury (Hg) concentrations were monitored in the surface waters from the lower portion of the Tapajos River, the Arapiuns River, its principal tributary, and the Amazon River at its confluence with the Tapajos. In the rivers, Hg concentrations in the water column are governed by the concentration of suspended particles. Hg in the filtered water

M. Roulet; M. Lucotte; R. Canuel; N. Farella; Y. G. De Freitos Goch; J. R. Pacheco Peleja; J.-R. D. Guimarães; D. Mergler; M. Amorim

2001-01-01

43

Grain size control of river suspended sediment geochemistry: Clues from Amazon River depth profiles  

NASA Astrophysics Data System (ADS)

Residual solid products of erosion display a wide range of size, density, shape, mineralogy, and chemical composition and are hydrodynamically sorted in large river channels during their transport. We characterize the chemical and isotopic variability of river sediments of the Amazon Basin, collected at different water depths, as a function of grain size. Absolute chemical concentrations and Sr and Nd isotopic ratios greatly varies along channel depth. The Al/Si ratio, tightly linked to grain size distribution, systematically decreases with depth, mostly reflecting dilution by quartz minerals. A double-normalization diagram is proposed to correct from dilution effects. Elements define fan-shaped patterns and can be classified in three different groups with respect to hydrodynamic sorting during transport in the Amazon: (1) "poorly sorted" insoluble elements like Al, Fe, Th, and REEs, (2) "well-sorted" insoluble elements like Zr and Ti, mainly carried by heavy minerals, and (3) alkali (Na to Cs) and alkali-earth elements (Mg to Ba), for which a large variety of patterns is observed, related, for alkali, to their variable affinity for phyllosilicates. Sr isotopes show that the Amazon River at the mouth is stratified, the Madeira- and Solimões-derived sediments being preferentially transported near the channel surface and at depth, respectively. The comparison between the Solimões and Madeira rivers shows how the interplay between grain sorting, weathering, and crustal composition controls the composition of the suspended river sediments.

Bouchez, Julien; Gaillardet, JéRôMe; France-Lanord, Christian; Maurice, Laurence; Dutra-Maia, Poliana

2011-03-01

44

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

45

Isotope composition of iron delivered to the oceans by intertropical rivers: The Amazon River Basin case  

NASA Astrophysics Data System (ADS)

Riverborne iron is a notable source for this biogeochemically key element to the oceans. Recent investigations have shown that its isotopic composition may vary significantly in oceanic waters. Hence, a proper understanding of the Fe cycle at the surface of the Earth requires a good characterization of the isotopic composition of its various reservoirs. However, as the database growths, it appears that the isotope composition of the riverborne Fe delivered to the oceans may be more varied than initially thought, in agreement with inferences from soil studies from different climatic contexts. It is therefore important to compare major rivers from different latitudes. We focused our attention on the Amazon River and its tributaries that represent ca. 20% of the freshwater delivered to the oceans by world rivers. Preliminary experiments suggest that water filtration may induce biases in stable Fe isotope composition. Therefore, we worked first on bulk waters, sampled during multidisciplinary field campaigns on the Amazon River and its tributaries, including the Solimoes, Negro, Madeira and Tapajos Rivers. Besides a complete sample physical-chemical characterization, Fe isotope determinations were conduced after water sample mineralization, iron purification and MC-ICP-MS analysis. Our first results reveal that most bulk water samples cluster close to the continental crust value (0.1% ?57FeIRMM-14) with an overall range of 0.2%. This is consistent with the restricted range found in lateritic soils elsewhere that represent 80% of the Amazon basin surface. Only black water rivers flowing over the podzols of the northern portion of the Amazon basin tend to show lighter isotopic compositions, down to -0.18%. However, sediment analyses suggest that this light Fe isotopic is lost through sedimentation on the river bed, thereby leading the waters to have Fe isotope compositions remaining close to that of the continental crust. This constant isotopic signature holds whatever the relative proportion of dissolved Fe in the bulk waters budget, that ranges from 5 to 50% in these waters, whatever the sample depth and whenever the samples were taken in the river cycle. Hence, given that several studies have shown that Fe loss through flocculation in estuaries does not affect Fe isotope signatures, we conclude that the bulk waters from the Amazon River delivered to the ocean should have an isotopic composition close to that of the continental crust.

Poitrasson, F.; Vieira, L. C.; Seyler, P.; dos Santos Pinheiro, G. M.; Mulholland, D. S.; Ferreira Lima, B. A.; Bonnet, M.; Martinez, J.; Prunier, J.

2011-12-01

46

A first quantitative estimate of trace metal fluxes from Amazon river and its main tributaries  

NASA Astrophysics Data System (ADS)

The trace metal (V, Cr, Mn, Co, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Cs, Ba, U) concentrations and temporal variabilities of the Amazon river and its main tributaries are studied on time series basis in the major tributaries of Amazon river (Negro, Madeira and Solimões Rivers) and at Obidos station on the Amazon mainsteem which represents 90% of the total discharge of Amazon river to the Ocean. Variations of river chemistry may reflect variations of the sources. The “Shield” rivers (as the Rio Negro) have typically depleted concentrations in As, Sr, Ba, Cu, and V as compared with Andean rivers. Elements such Mn and As are mainly transported by the flood flows. These elements are known to be concentrated in lateric (ferricrete) soils which represent 80% in the Amazon basin, suggesting that these elements are washed away in solution during the high discharge. Moreover, these elements can be stored in the surrounding floodplain areas (varzea) where deposition/resuspension cycles as well as the exchange rate between floodplain and mainstream channel may control at least partially the temporal variation of redox element concentrations such Mn and As. Implication on these results on the trace element flux from Amazon River to the Atlantic Ocean is discussed.

Seyler, P. T.; Pinelli, M.; Boaventura, G. R.

2003-05-01

47

Floodplain channel morphology and networks of the middle Amazon River  

NASA Astrophysics Data System (ADS)

Floodplain channels are important components of river-floodplain systems and are known to play a key role in hydrodynamic exchange and sediment transport. The Amazon floodplain exhibits complex networks of these channels, and despite their potential importance to this globally important wetland system, these floodplain channels are relatively unstudied. The research presented here is the first systematic and detailed study of the network and morphologic characteristics of a large number of these channels in the middle reach of the central Amazon River using analysis of data derived from Landsat Enhanced Thematic Mapper Plus (ETM+) mosaic and field survey. Our findings show that the channels are ubiquitous, their width varies widely, and some of their characteristics can be fitted using power laws, potentially much like the self-similar or fractal-like behavior hypothesized for other types of fluvial networks. In all, 96% of the floodplain channels are not wide enough to be represented well, or at all, in the ˜90 m Shuttle Radar Topography Mission data. Channel depths are tied closely to the local amplitude of the passing main river flood wave (p value of 0.75), except where there are local runoff inputs, which results in substantially deeper channels which provide preferential flow paths across the floodplain. Channel networks imply that areas of the floodplain function for large parts of the flood cycle as separate hydrogeomorphic land units, here termed floodplain hydrological units (FHUs). These hypothesized FHUs also have distinct spatial and pattern characteristics, and it is suggested here that their differences could provide the beginnings of a framework for understanding the detailed hydrodynamics of the floodplain. In particular, different types of FHUs have differences in flood water source, which will have important implications for biogeochemical studies of the wetlands.

Trigg, Mark A.; Bates, Paul D.; Wilson, Matthew D.; Schumann, Guy; Baugh, Calum

2012-10-01

48

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

49

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

Technology Transfer Automated Retrieval System (TEKTRAN)

Toxoplasma gondii is an important pathogen in aquatic mammals and its presence in these animals may indicate water contamination of aquatic environment by oocysts. Serum samples from 95 dolphins from free-living Amazon River dolphins (Inia geoffrensis) from Sustainable Development Reserve Mamirauá (...

50

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

Technology Transfer Automated Retrieval System (TEKTRAN)

Toxoplasma gondii is an important pathogen in aquatic mammals and its presence in these animals may indicate water contamination of aquatic environment by oocysts. Serum samples from 95 dolphins from free-living Amazon River dolphins (Inia geoffrensis) from Sustainable Development Reserve Mamirauá (...

51

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

52

Mercury in the environment and riverside population in the Madeira River Basin, Amazon, Brazil  

Microsoft Academic Search

This work presents quality control results on the mercury concentrations in different environmental (river sediments, forest soils, river suspended matter and fish) and human samples from the lower Madeira River, Amazon sampled between 2001 and 2003, about 15–20 years after the nearly cessation of gold mining activities in the region, which reached its peak in the late 1980s. The study

Wanderley Rodrigues Bastos; João Paulo Oliveira Gomes; Ronaldo Cavalcante Oliveira; Ronaldo Almeida; Elisabete Lourdes Nascimento; José Vicente Elias Bernardi; Luiz Drude de Lacerda; Ene Glória da Silveira; Wolfgang Christian Pfeiffer

2006-01-01

53

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

2011-06-12

54

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

55

Channel Slopes on Amazon Basin Rivers From the SRTM DEM  

NASA Astrophysics Data System (ADS)

Changes in surface water storage (S) and discharge (Q) are poorly known globally but are critical for constraining the terrestrial branch of the water cycle. To date, only the SRTM mission provides global measurements of both surface water area and elevation. However, little is known about the instrument performance for collecting delta-S and Q. The Amazon Basin is a particularly appealing target given its sparse gauge density, lack of continuous and reliable slope data that can be used in the estimation of discharge, and complexity of flow hydraulics. We have used SRTM elevation data in conjunction with flow distance to estimate water surface slope for the area 0S-8S, 72W-54W. Using a 3rd order polynomial fit to the distance-elevation data, slope values of the mainstem Amazon range from less than 0.5 cm km-1 downstream of Obidos to 4.10 cm km-1 3000 km upstream of this location. The central Amazon slope ranges from 1.86 cm km-1 to 3.10 cm km-1 from Manaus to the Rio Japura (about 800 km upstream). Local slopes for specific gauge locations were achieved using both a linear fit to the data and the polynomial fit. The slope value at Itapeua, about 430 km upstream of Manaus, was found to be 3.22 cm km-1 using a linear fit, and 2.65 - 2.79 cm km-1 using a 3rd order polynomial fit, for a reach of 24 km. The slope value for Manacapuru, about 90 km upstream of Manaus, was determined to be 3.56 cm km-1 using a linear fit and 1.97 - 2.12 cm km-1 for a reach of 70 km centered on the local gauge. This slope is used in the Manning equation (n = 0.03) with depth values from navigation charts and river width measured from JERS-1 SAR imagery to yield discharge values for Manacapuru of 93,500 m3 sec-1and for Itapeua of 81,900 m3 sec-1. The observed discharge value at the Manacapuru gauge is 96,300 m3 sec-1 over an 11-day average in February for the years 1973-1991. The average observed discharge value for Itapeua is 83,100 m3 sec-1 for the same time period.

Hendricks, G.; Alsdorf, D. E.

2004-12-01

56

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

57

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

58

Chemical and Carbon Isotope Composition of Varzeas Sediments and Its Interactions with Some Amazon Basin Rivers.  

National Technical Information Service (NTIS)

Varzea sediment samples were collected on the banks of Amazon rivers and in the most important tributaries. The samples were taken in three different river stages. The major cations, pH, total nitrogen, total phosphorus, carbon and delta(sup 13)C values w...

L. A. Martinelli

1986-01-01

59

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

60

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

2012-09-26

61

Sources and routing of the Amazon River Flood Wave  

NASA Astrophysics Data System (ADS)

We describe the sources and routing of the Amazon River flood wave through a 2000-km reach of the main channel, between São Paulo de Olivença and Obidos, Brazil. The damped hydrograph of the main stem reflects the large drainage basin area, the 3-month phase lag in peak flows between the north and south draining tributaries due to seasonal differences in precipitation, and the large volume of water stored on the floodplain. We examined several aspects of the valley floor hydrology that are important for biogeochemistry. These include volumes of water storage in the channel and the floodplain and the rates of transfer between these two storage elements at various seasons and in each segment of the valley. We estimate that up to 30% of the water in the main stem is derived from water that has passed through the floodplain. To predict the discharge at any cross section within the study reach, we used the Muskingum formula to predict the hydrograph at downriver cross sections from a known hydrograph at upstream cross-sections and inputs and outputs along each reach. The model was calibrated using three years of data and was successfully tested against an additional six years of data. With this model it is possible to interpolate discharges for unsampled times and sites.

Richey, Jeffrey E.; Mertes, Leal A. K.; Dunne, Thomas; Victoria, Reynaldo L.; Forsberg, Bruce R.; Tancredi, AntôNio C. N. S.; Oliveira, Eurides

1989-09-01

62

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

63

Space-time variability of the Amazon River plume based on satellite ocean color  

Microsoft Academic Search

Satellite ocean color images were used to determine the space-time variability of the Amazon River plume from 2000–2004. The relationship between sea-surface salinity (SSS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) absorption coefficient for dissolved and detrital material (adg) (r2=0.76, n=30, rmse=0.4) was used to identify the Amazon River plume low-salinity waters (<34psu). The plume's spatial information was extracted from

Gustavo S. F. Molleri; Evlyn M. L. de M. Novo; Milton Kampel

2010-01-01

64

Seasonality of Rare Earth Element concentrations and fluxes in the Amazon river and its main tributaries  

NASA Astrophysics Data System (ADS)

Many studies carried out on the Amazon River illustrate the complex functioning of this river in terms of geochemistry. Concerning the REE, (Sholkovitz and Szymczak 2000) and (Hannigan and Sholkovitz 2001, Gerard et al, 2003) summarized the actual knowledge we have on the Amazon river. In this study we present a 2-year time series on dissolved REE geochemistry in the Amazon River at Óbidos station (S01°56'50", W55°30'40"), which is the ultimate gauging station on the Amazon River upstream from the marine influence and from the three main Amazon River tributaries, The Negro River at Serrinha (S00°28'55", W064°49'48) station, the Solimões River at Manacapuru stations (S03°20'43", W60°33'12") and the Madeira River at Porto Velho (08°44'12", W63°55'13"), and the Curuaí floodplain, one of the largest várzea located in between Manaus and Óbidos. REE concentrations were measured by ICP-MS in LMTG Laboratory (France). The main results are: -a substantial seasonal variation in REE concentrations that is correlated with discharge. This variation repeats itself from yaer to year, and is also reflected in a compilation of literature data that reflects different years and dates of sampling; - an absence of seasonal variation in REE patterns and Ce* anomalies; - a monthly weighted annual Nd flux to the surface Atlantic Ocean of 607 ± 43 T.yr-1, which is at least 1.6 times larger than the currently used estimate based on one single measurement during the low water stage. A mass balance of the major tributaries shows quasi-conservative behavior of the LREE and an excess of observed HREE during the high water stage. Additional observations are necessary to see if this feature is recurrent or whether it reflects inherent organizational and analytical difficulties involved in the monthly sampling of all Amazonian rivers. Persistence of such a HREE excess requires a source such as suspended matter sorbed REE that transfer to the dissolved phase at tributary confluences or during passage through the adjacent floodplain lakes of the Amazon. This hypothesis is qualitatively supported by the observation that during the high water and falling water stage the floodplain exit waters display higher REE concentrations than Amazon mainstem.

Seyler, P.; Sonke, J.; Viers, J.; Barroux, G.; Boaventura, G. R.; Rousseau, T.

2008-12-01

65

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

66

Survey of protozoan, helminth and viral infections in shrimp Litopenaeus setiferus and prawn Macrobrachium acanthurus native to the Jamapa River region, Mexico.  

PubMed

We surveyed protozoan and metazoan parasites as well as white spot syndrome virus (WSSV) and infectious hypodermal hematopoietic necrosis virus (IHHNV) in white shrimp Litopenaeus setiferus and the palaemonid prawn Macrobrachium acanthurus native to the lower Jamapa River region of Veracruz, Mexico. The presence of parasites and the infection parameters were evaluated in 113 palaemonid prawns collected during the northwind (n = 45), rainy (n = 38) and dry seasons (n = 30) between October 2007 and July 2008, and in 91 shrimp collected in the rainy season between May and June 2008. In L. setiferus, ciliates of the subclass Apostomatia (Ascophrys sp.) were evident in gills, and third-stage larvae of the nematode Physocephalus sexalatus were evident in the stomach. Cestodes of the genus Prochristianella were evident in the hepatopancreas, while some gregarines of the genus Nematopsis, as well as unidentified larval cestodes, were observed in the intestine. Histology identified Ascophrys sp. in association with gill necrosis and tissue melanization. Slight inflammation was observed in intestinal epithelium near cestode larvae. In M. acanthurus, epibionts of the protozoans Epistylis sp., Acineta sp. and Lagenophrys sp. were observed under uropods, periopods and pleopods. An unidentified ciliate of the Apostomatia was also found in the gills, and Nematopsis was identified in the intestine. No histopathology was observed in association with these parasites. Moreover, neither WSSV nor IHHNV were detected by the polymerase chain reaction (PCR) in any of the L. setiferus or M. acanthurus analysed. PMID:22013749

Domínguez-Machín, Magda E; Hernández-Vergara, Martha P; Jiménez-García, Isabel; Simá-Alvarez, Raúl; Rodríguez-Canul, Rossanna

2011-09-01

67

Sediment transport in the Rio Grande, an Andean river of the Bolivian Amazon drainage basin  

Microsoft Academic Search

The Rio Grande is one of the main Andean tributaries of the Rio Mamore, a tributary of the Rio Madeira which is the main southern affluent of the Amazon. The use of historical (1969-1990) and unpublish­ ed data on sediment transport from 15 Andean gauging stations, made it possible to assess the very strong temporal variability of river sediment-transport. Most

JEAN LOUP GUYOT; JACQUES BOURGES; JOSE CORTEZ

1994-01-01

68

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

69

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

70

The water budget in the Amazon River basin during the FGGE period  

Microsoft Academic Search

The seasonal change of the water budget in the Amazon River basin during the FGGE period is investigated, using the global objective analysed data set, precipitation data and discharge data. Some difference is found between the annual water vapour flux convergence and the annual runoff obtained by discharge data. This is due to the characteristics of the global objective analysed

HIROSHI MATSUYAMA; KOOITI MASUDA

1993-01-01

71

Surface water quality monitoring in large rivers with MODIS data application to the amazon basin  

Microsoft Academic Search

In this study, we propose to assess the use of MODIS images to monitor interannual variation of sediment flow by comparing surface reflectance data and field measurements of suspended sediment (SS) concentration collected every 10 days in surface waters of different locations of the Amazon River in Brazil. These data come from the HYBAM measurement network that measures the hydrology

J. M. Martinez; J. L. Guyot; G. Cochonneau; F. Seyler

2007-01-01

72

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

73

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

74

Distribution of Agrobiodiversity in Home Gardens along the Corrientes River, Peruvian Amazon  

Microsoft Academic Search

Distribution of Agrobiodiversity in Home Gardens along the Corrientes River, Peruvian Amazon. This paper examines crop species diversity in home gardens of traditional communities along a remote tributary in northeastern\\u000a Peru. A large-scale survey was conducted of 300 gardens in 15 villages along a 150 km reach of the Corrientes River. Study\\u000a villages vary notably in community size, ethnicity of residents

Mathilde Perrault-Archambault; Oliver T. Coomes

2008-01-01

75

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

76

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

77

Mapping large-scale river flow hydraulics in the Amazon Basin  

NASA Astrophysics Data System (ADS)

Research on actual requirements for a numerically consistent representation of flow dynamics in large-scale river-flood models are needed to improve both modeling performance and computational efficiency. Still, regional- and global-scale characterizations of river hydrodynamics are absent. A first attempt to map river hydrodynamics in the Amazon Basin is presented. Flood wave type maps at 0.25° spatial resolution are derived from a classification method based on the analysis of Saint-Venant equation terms. Global river geometry data sets derived from both digital elevation models and empirical equations supported by stream gauge observations are used as input variables. Errors of input variables are estimated, and a sensitivity analysis is performed. Results show that 64.5% of rivers (headwaters and high-slope rivers) can be represented by the kinematic wave (KI), 34.5% (main Amazon tributaries, low slope, and wetland regions) by the diffusive wave (DF), and 1% (lower Amazon) by the full Saint-Venant equations (SV). In a rigorous scenario, i.e., a case where the most restricted classification of each grid cell is considered, ˜33% is classified as KI, ˜62% as DF, and ˜5% as SV. Most of the basin presents subcritical flow with very low Froude number (Fr), while the Andean region is dominated by larger Fr values and supercritical flow can be found. According to our evaluation mostly based on in situ data, the map has a percentage of detection of 83.4%.

Getirana, Augusto C. V.; Paiva, Rodrigo C. D.

2013-05-01

78

Mercury pollution in the Tapajos River basin, Amazon  

Microsoft Academic Search

There is increasing concern about the potential neurotoxic effects of exposure to methylmercury for the 6 million people living in the Amazon, even in regions situated far away from the gold mines (garimpos), considered to be the major source of mercury pollution. In November 1998, a spot investigation on mercury contamination was conducted in three fishing villages (Barreiras, Rainha, and

Masazumi Harada; Junko Nakanishi; Eiichi Yasoda; Maria da Conceicâo N Pinheiro; Teiichi Oikawa; Geraldo de Assis Guimarâes; Bernardo da silva Cardoso; Takako Kizaki; Hideki Ohno

2001-01-01

79

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

80

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

NASA Astrophysics Data System (ADS)

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 forest was derived from the soil respiration, and the CO2 input to air over the Amazon river was derived from the degassing of CO2 from the river. It was also found that plants growing at heights lower than 7 m assimilate soil-derived CO2 with a low C-13/C-12 ratio.

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

1989-12-01

81

Large-scale hydrologic and hydrodynamic modeling of the Amazon River basin  

NASA Astrophysics Data System (ADS)

In this paper, a hydrologic/hydrodynamic modeling of the Amazon River basin is presented using the MGB-IPH model with a validation using remotely sensed observations. Moreover, the sources of model errors by means of the validation and sensitivity tests are investigated, and the physical functioning of the Amazon basin is also explored. The MGB-IPH is a physically based model resolving all land hydrological processes and here using a full 1-D river hydrodynamic module with a simple floodplain storage model. River-floodplain geometry parameters were extracted from the SRTM digital elevation model, and the model was forced using satellite-derived rainfall from TRMM3B42. Model results agree with observed in situ daily river discharges and water levels and with three complementary satellite-based products: (1) water levels derived from ENVISAT altimetry data; (2) a global data set of monthly inundation extent; and (3) monthly terrestrial water storage (TWS) anomalies derived from the Gravity Recovery and Climate Experimental mission. However, the model is sensitive to precipitation forcing and river-floodplain parameters. Most of the errors occur in westerly regions, possibly due to the poor quality of TRMM 3B42 rainfall data set in these mountainous and/or poorly monitored areas. In addition, uncertainty in river-floodplain geometry causes errors in simulated water levels and inundation extent, suggesting the need for improvement of parameter estimation methods. Finally, analyses of Amazon hydrological processes demonstrate that surface waters govern most of the Amazon TWS changes (56%), followed by soil water (27%) and ground water (8%). Moreover, floodplains play a major role in stream flow routing, although backwater effects are also important to delay and attenuate flood waves.

de Paiva, Rodrigo Cauduro Dias; Buarque, Diogo Costa; Collischonn, Walter; Bonnet, Marie-Paule; Frappart, FréDéRic; Calmant, Stephane; Bulhões Mendes, Carlos André

2013-03-01

82

Dynamic boundary-monsoon intensity hypothesis: evidence from the deglacial Amazon River discharge record  

NASA Astrophysics Data System (ADS)

Glacioeustatic- and temperature-corrected planktonic foraminiferal oxygen isotope (??18O) records from ODP Site 942 on the Amazon Fan provide a means of monitoring past changes in the outflow of the Amazon River. This study focuses on the last deglaciation and reveals that during this period there were significant variations in the outflow, which implies large changes in moisture availability in the Amazon Basin. Aridity in the Amazon Basin seems to occur between 20.5 ka (calendar) to 17.0 ka and 13.6 ka to 11 ka. The second arid period correlates with the start of the Antarctic Cold Reversal and aridity continues throughout the Younger Dryas period. We find that the large-scale trends in Amazon River outflow are dissimilar to high-latitude variability in either hemisphere. Instead high-resolution variations correlate with the ?18O difference between Greenland and Antarctica ice core temperature records. This suggests a link between Hemispheric temperature gradients and moisture availability over the Amazon. Based on our results and previously published work we present a new testable 'dynamic boundary-monsoon intensity hypothesis', which suggests that tropical moisture is not a simple belt that moves north or south. Rather, the northern and southern boundaries of the South American Summer Monsoon (SASM) are independently dynamic and driven by temperature gradients within their individual hemispheres. The intensity of rainfall within the SASM, however, is driven by precessionally modulated insolation and the resultant convection strength. Combining these two influences produces the dynamic heterogenic changes in the moisture availability observed over tropical South America since the Last Glacial Maximum.

Maslin, M. A.; Ettwein, V. J.; Wilson, K. E.; Guilderson, T. P.; Burns, S. J.; Leng, M. J.

2011-12-01

83

Barbados Corals as Recorders of Amazon River Salinity Anomalies  

NASA Astrophysics Data System (ADS)

Low salinity plumes of Amazon and Orinoco sourced water have previously been detected around the island of Barbados. Barbados corals may therefore have the potential to record salinity anomalies governed by natural, climate-related, and anthropogenic changes in the Amazon and Orinoco Basin watersheds beyond the recent historic record. In order to determine whether Barbados corals record salinity variations associated with local or Amazon/Orinoco sourced signals, multiple specimens of Montastraea sp. and Siderastrea sp. coral skeletons were analyzed for stable C and O isotope and Sr/Ca variations. Corals were collected from the northwest, central-west, and southwest regions of the island to determine degree of salinity signal heterogeneity over a 5-6 year period at approximately monthly resolution. Four separate published paleotemperature equations were used to assess the importance of temperature on stable oxygen isotope composition. In situ temperature measurements obtained from NOAA show an annual sea surface temperature (SST) cycle of approximately 4 degrees Celsius off Barbados. If governed solely by SST, stable isotope data from all 8 corals in this study indicate a significantly greater annual temperature range of approximately 6 degrees Celsius. This suggests that salinity related fluctuations in oxygen isotopic composition of water are an important influence on the geochemistry of Barbados corals. Some regional differences in geochemical composition of corals were apparent. Corals from the southwest of Barbados showed the clearest sub-annual isotope signal, better correlations with mean annual SST measurements, and lowest mean salinity of the regions. Corals from the central-west and northwest showed distinctly higher mean, but more variable, salinity than corals from the south. Stable carbon isotope data from southwest corals also best potentially reflect the Suess Effect. Montastraea sp. corals generally show a higher paleotemperature offset from in situ values, suggesting that the ability to extract salinity data from Barbados corals may be species-specific. These results may have implications for understanding local eddy patterns as Amazon-sourced water encounters Barbados. It is possible that the central and northern lee coasts may be less impacted by Amazon water and more subject to local restriction from open marine conditions and/or increased evaporative effects.

Greer, L.; Telfeyan, K.; Arienzo, M. M.; Rosenberg, A. D.; Waite, A. J.; Swart, P. K.

2010-12-01

84

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

85

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

86

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

87

Particulate organic carbon, sterols, fatty acids and pigments in the Amazon River system  

Microsoft Academic Search

Water samples were collected from the Amazon River system during a high flood period, in June 1989, and lipids associated with particles retained on GF\\/F filters were examined. Particles showed a highly variable organic carbon content (1.8–29.0%). Corresponding organic carbon concentrations varied from 0.36 to 1.13 mg\\/l. The flood conditions encountered during the sampling period may feed exceptional inputs of

A. Saliot; L. Mejanelle; P. Scribe; J. Fillaux; C. Pepe; A. Jabaud; J. Dagaut

2001-01-01

88

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

89

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

NASA Astrophysics Data System (ADS)

The seasonal and interannual fluctuations of the biogeochemical budget (solutes, suspended matter, isotopes) of the Amazon River basin were analyzed, with a special focus on 44 physicochemical parameters monitored over the period 1982-1984 during the Carbon in the AMazon River Experiment (CAMREX) project. The relevant factors driving this variability were identified and sorted through the implementation of a statistical-regressive model coupled to variance analysis. Basically, the compositional fluctuations in the Amazon River are related (1) to the variable contribution of major tributaries (variable regional source) to the river flow but also (2) to the variable contribution of hydrological sources, (3) to river processes, i.e. in-stream diagenesis and sediment dynamics and (4) to the hydrological budget of the floodplains. Their respective contributions to the variability of chemical signals observed in the stream waters depend on which parameter was investigated but their combination explains on average 85% of the observed variability. The variability related to regional sources was captured by the compared measures of flow discharge and biogeochemical fluxes at the outlet of the major tributaries. The variability of hydrological sources was described by the variable contribution of three runoffs of distinct but constant composition: forwarded direct runoff, delayed floodplain runoff and baseflow. Several methods were tested to depict the seasonal and interannual variations of their individual discharges. Biologically-mediated processes were related to a hydrobiological index IBIO = [O 2]-[CO 2] which allows tracking the nature of the dominant ecological regime (autotrophy vs. heterotrophy). The alteration of chemical signals related to the intermittent discharge of the floodplains (where specific processes occur such as: gas exchanges at the air-water interface, sorption of dissolved organic matter, chemical weathering, deposition vs. remobilization of sediments, etc.) was simulated by taking into account the default of hydrological balance between inflows and outflows, used as a marker of floodplains discharge. This analysis shows that the chemical baseline observed in the waters of the Amazon River is mostly acquired upstream from the junction of major tributaries with the Amazon main reach.

Bustillo, Vincent; Victoria, Reynaldo Luiz; Moura, Jose Mauro Sousa de; Victoria, Daniel de Castro; Toledo, Andre Marcondes Andrade; Collicchio, Erich

2011-04-01

90

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

PubMed

The fresh water discharged by large rivers such as the Amazon is transported hundreds to thousands of kilometers away from the coast by surface plumes. The nutrients delivered by these river plumes contribute to enhanced primary production in the ocean, and the sinking flux of this new production results in carbon sequestration. Here, we report that the Amazon River plume supports N(2) fixation far from the mouth and provides important pathways for sequestration of atmospheric CO(2) in the western tropical North Atlantic (WTNA). We calculate that the sinking of carbon fixed by diazotrophs in the plume sequesters 1.7 Tmol of C annually, in addition to the sequestration of 0.6 Tmol of C yr(-1) of the new production supported by NO(3) delivered by the river. These processes revise our current understanding that the tropical North Atlantic is a source of 2.5 Tmol of C to the atmosphere [Mikaloff-Fletcher SE, et al. (2007) Inverse estimates of the oceanic sources and sinks of natural CO(2) and the implied oceanic carbon transport. Global Biogeochem Cycles 21, doi:10.1029/2006GB002751]. The enhancement of N(2) fixation and consequent C sequestration by tropical rivers appears to be a global phenomenon that is likely to be influenced by anthropogenic activity and climate change. PMID:18647838

Subramaniam, A; Yager, P L; Carpenter, E J; Mahaffey, C; Björkman, K; Cooley, S; Kustka, A B; Montoya, J P; Sañudo-Wilhelmy, S A; Shipe, R; Capone, D G

2008-07-22

91

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

92

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

2012-09-28

93

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

94

First report of major histocompatibility complex class II loci from the Amazon pink river dolphin (genus Inia)  

Microsoft Academic Search

We report the first major histocompatibility complex (MHC) DQB1 sequences for the two species of pink river dolphins (Inia geoffrensis and Inia boliviensis) inhabiting the Amazon and Orinoco River basins. These sequences were found to be polymorphic within the Inia genus and showed shared homology with cetacean DQB- 1 sequences, especially, those of the Monodontidae and Phocoenidae. On the other

M. Martínez-Agüero; S. Flores-Ramírez; M. Ruiz-García

2006-01-01

95

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

NASA Astrophysics Data System (ADS)

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 from one river to another and according to the season, but dissolved organic carbon (DOC) always accounted for about 70% of the total organic carbon (TOC). The mean concentration of dissolved organic carbon was 6·1 mg l-1 in the Madeira River, 5·83 mg l-1 in the Solimões River and 12·7 mg l-1 in the Negro River. The percentage in weight of the particulate organic carbon decreased as the concentration of suspended matter increased. The Solimões River contributed the most carbon to the Amazon River: about 500 kg C s-1 during the high water period and about 300 kg C s-1 during the low water period. However, the temporal variations in organic carbon in the Amazon River (i.e. downstream of Manaus) are basically controlled by inputs from the Negro River and its variations. The Negro River does not produce a simple dilution effect. During the high water period (between March and August) the TOC flux, calculated as the sum of the Solimões, Negro and Madeira tributaries, was about 5·7 × 1013 g C yr-1, whereas during the low water period (between September and February) the TOC flux was about 2·6 × 1013 g C yr-1.The mean annual flux of TOC at Óbidos (the final gauging station upstream of the estuary) was about 3·27 × 10Amazon River. These inputs can be attributed to the adjacent floodplain lake system, called várzea.

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

2003-05-01

96

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

97

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

98

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

99

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

100

Analysis of the water level dynamics simulated by a global river model: A case study in the Amazon River  

NASA Astrophysics Data System (ADS)

Water level dynamics in continental-scale rivers is an important factor for surface water studies and flood hazard management. However, most continental-scale river models have not focused on the reproduction of water level because the storage and movement of surface waters are regulated by smaller-scale topography than their grid resolutions. Here we analyzed the water level dynamics simulated by a state-of-the-art global river model, CaMa-Flood, with subgrid representation of floodplain topography. As a case study, hydrodynamics simulation in the Amazon River was accomplished, and the simulated water surface elevations along the main stem were compared against Envisat altimetry. The seasonal cycles of the simulated water surface elevations are in agreement with the altimetry (correlation coefficient >0.69, annual amplitude error <1.6 m). The accuracy of absolute water surface elevations was also good (averaged RMSE of 1.83 m), and the associated errors were within the range of the model uncertainty due to channel cross-section parameters. Then the ocean tide variation at river mouth was incorporated for simulating the tidal effect in the inland Amazon basin, which requires realistic representation of absolute water surface elevations. By applying power spectra analysis to the simulated water level variations, the 15 day cycle due to spring and neap tides was detected at Obidos, located 800 km upstream from the river mouth. The reproduction of the ocean tide propagation to the inland region suggests that CaMa-Flood includes the main physical processes needed to accurately simulate the water level dynamics in continental-scale rivers.

Yamazaki, Dai; Lee, Hyongki; Alsdorf, Douglas E.; Dutra, Emanuel; Kim, Hyungjun; Kanae, Shinjiro; Oki, Taikan

2012-09-01

101

Simulation of absolute water surface elevations in a global river model: a case study in the Amazon River  

NASA Astrophysics Data System (ADS)

Water level dynamics in continental-scale rivers is an important factor for surface water studies and flood hazard management. However, most continental-scale river models have not focused on the reproduction of water level because the storage and movement of surface waters are regulated by smaller scale topography than their grid resolutions. Here we analyzed the water level dynamics simulated by a state- of-the-art global river model, CaMa-Flood, with sub-grid representation of floodplain topography. As a case study, hydrodynamics simulation in the Amazon River was accomplished, and the simulated water surface elevations along the mainstem were compared against Envisat altimetry. The seasonal cycle of the simulated water surface elevations are in agreement with the altimetry (correlation coefficient >0.69, annual amplitude error <1.6 m). The accuracy of absolute water surface elevations was also good (averaged RMSE of 1.83 m), and the associated errors were within the range of the model uncertainty due to channel cross-section parameters. Then, the ocean tide variation at river mouth was incorporated for simulating the tidal effect in the inland Amazon basin, which requires realistic representation of absolute water surface elevations. By applying power-spectra analysis to the simulated water level variations, the 15-day cycle due to spring and neap tides was detected at Obidos located 800 km upstream from the river mouth. The reproduction of the ocean tide propagation to the inland region suggests that CaMa-Flood includes the main physical processes needed to accurately simulate the water level dynamics in continental-scale rivers.

Yamazaki, Dai; Lee, Hyongki; Alsdorf, Doug; Dutra, Emanuel; Kim, Hyungjun; Kanae, Shinjiro; Oki, Taikan; Bates, Paul

2013-04-01

102

Amazon river discharge variability at the Obidos gauging station during the last century  

NASA Astrophysics Data System (ADS)

The Amazon river at Obidos, the greatest hydrological station of the world (4 676 000 km^2 drainage basin), is monitored by the Brazilian Water Agency (ANA) since 1968. Using historical gauge river data from other stations and organisms, daily discharge data was reconstitued for the 1902-1999 period (Callède et a., 2002). Results show a mean annual discharge of 163 000 m^3.s-1 for the whole period, with a tendency to the increase during the century. The statistical analysis of the annual mean, maximum and minimum shows on several tests (Petitt, Hubert, Lee &Heghinian) the appearance of a break about 1970, which is not detected on the average pluviometry of the basin. This break, followed by an increase in flow, was observed on the majority of the rivers of South America and, in opposite direction, on the rivers of the African Sahel. From 1980, the medium flows of the Amazon increase by 5%, the maximum ones (risings) of 7%, whereas the minima (low water levels) decrease by 8%. This recent increase in the extremes (risings and low water levels), which represents an increase in the streaming, could be the consequence of the deforestation of certain parts of the basin in the last 20 years.

Callède, J.; Guyot, J. L.; Ronchail, J.; Seyler, F.; Guimarães, V.; de Oliveira, E.

2003-04-01

103

Assessment of the Relationship between Andean Ice Core Precipitation Indicators and Amazon River Discharge  

NASA Astrophysics Data System (ADS)

Prior to the last 100 years, there is a significant lack of hydrologic knowledge for the Amazon Basin. A 100- year record of discharge from the city of Manaus, located at the confluence of the Solimoes and Negro rivers, is the most complete record for the basin. Inundated wetlands play a key role in carbon out-gassing to the atmosphere whereas discharge from the Amazon River contributes about 20% of the total freshwater flux delivered to the world's oceans. As discharge (Q) and inundation are directly related to precipitation, we are developing a method to extend our understanding of Q and inundation into the 19^{th} century. Using proxy data preserved in Andean glaciers and ice caps and recovered from ice cores, annually resolved histories of ?^{18)O and mass accumulation are available. The latter is a proxy for local precipitation amount whereas ?18O is influenced by continental scale processes (i.e., evaporation, convection) as well as by temperature and hence, by varying climate regimes. We have correlated the accumulation and ?18O records from Core 1 drilled on the Quelccaya ice-cap in the southern Andes of Peru with the Manaus discharge data. As ice core annual layers correspond to the thermal year (in Peru, July to June of the following year) and the discharge records are kept daily (January to December), we averaged 365 days of Q data seeking the optimal correlation for each start and end date. The best statistical relationship between ?18O and Q (r = -0.41, p = < 0.001) is attained when Q is averaged from March 16 to March 15 of the following year. We also correlated 23 years of ENSO events, which are linked to both Amazon River discharge and ice core ?18O (r = -0.60, p = < 0.001). These linear relationships are used to create Amazon discharge for the 20^{th} century and to extrapolate Q into the 19^{th} century. Previously developed relationships between Q and mainstem inundated area are then used to estimate inundated area along the main Amazon channel for the past 200 years. The ice core-derived estimate of inundated area for the past 100 years compares well with the previous and more straightforward estimates based on discharge and remote sensing data.

Johnson, N.; Alsdorf, D.; Thompson, L.; Mosley-Thompson, E.; Melack, J.

2006-12-01

104

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

105

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

2013-02-26

106

Temporal dynamics of water and sediment exchanges between the Curuaí floodplain and the Amazon River, Brazil  

NASA Astrophysics Data System (ADS)

The fluvial transport and storage of sediments within channel floodplain systems can act as important sinks of sediments. In this study, we document the role of an Amazonian floodplain (Curuaí) for sediment storage. Located on the right bank of the Amazon River, 900 km upstream of the mouth, the complex system contains more than 30 interconnected lakes linked to the mainstream by permanent and temporary channels. With an open-water area varying between 600 km2 and 2500 km2, it represents ˜13% of the total flooded area of the Amazon River, between Manaus and Óbidos. For the period 2000 2003, daily liquid and solid fluxes exchanged between the floodplain system and the Amazon River were determined using an hydrological model based on a network of gauging, meteorological and sediment monitoring stations and satellite data including radar altimetry data. Sediment accumulation occurs during the five months of the flood rise, from December to April. The export of sediments to the mainstream occurs during the low water stage while depositional processes in lakes and channels are disrupted by the wind induced re-suspension of sediments. The mean average sediment storage calculated varies between 558 and 828 × 103 t yr-1 corresponding to 5.4 (±19%) × 103 t km-1 yr-1 of sediment deposited along the 130 km reach between Juruti and Santarem. This annual storage represents between 41% and 53% of the annual flux of sediments entering this floodplain through the main channels. The associated mean specific sedimentation rate is ˜517 (±23%) t km-2 yr-1 leading to a sediment accretion rate of 1.6 mm yr-1 ± 23%.

Bourgoin, Laurence Maurice; Bonnet, Marie-Paule; Martinez, Jean-Michel; Kosuth, Pascal; Cochonneau, Gerard; Moreira-Turcq, Patricia; Guyot, Jean-Loup; Vauchel, Philippe; Filizola, Naziano; Seyler, Patrick

2007-03-01

107

Geodetic corrections to Amazon River water level gauges using ICESat altimetry  

NASA Astrophysics Data System (ADS)

Gauge stations are vital for monitoring water levels worldwide. However, many remote basins suffer from having gauges that are not tied to a common datum, making it impossible to know absolute water elevations, and therefore slope. This problem is known to exist on the River Amazon, for example, where water flux modeling efforts have been hampered by inconsistently leveled gauge data that serve as boundary conditions for these models. This paper presents a methodology for using Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry observations to geodetically level gauge stations. A proof-of-concept study was carried out to ascertain the feasibility and accuracy of the approach, and a mean absolute error of 19 cm was found. Once this was established, gauges within the Amazon Basin were geodetically leveled. This produced offsets for six gauges using a method that can be transferred to other locations and allows slope and discharge estimates to be calculated. The results are significant, with offsets as large as 13.37 m being added. The approach could provide improvements in modeling floodplain flow, processes, and fluxes in the Amazon Basin and worldwide.

Hall, Amanda C.; Schumann, Guy J.-P.; Bamber, Jonathan L.; Bates, Paul D.; Trigg, Mark A.

2012-06-01

108

Mercury pollution in the Tapajos River basin, Amazon: mercury level of head hair and health effects.  

PubMed

There is increasing concern about the potential neurotoxic effects of exposure to methylmercury for the 6 million people living in the Amazon, even in regions situated far away from the gold mines (garimpos), considered to be the major source of mercury pollution. In November 1998, a spot investigation on mercury contamination was conducted in three fishing villages (Barreiras, Rainha, and Sao Luiz do Tapajos) on the Tapajos River, an effluent of the Amazon, situated several hundred kilometers downstream from the gold-mining areas. A total of 132 fishermen and their families volunteered for the current study. As was anticipated, the total mercury levels in the head hair collected from the fishing villages were relatively high (14.1-20.8 ppm on the average) and the number of subjects with a high total mercury level over 10 ppm (the least upper bound of a normal value) was 103 (78.0%) in total, along with various symptoms, thereby suggesting wide mercury contamination in the Tapajos River basin. Moreover, in view of the absence of other diseases (e.g., alcoholism or malaria), a high intake of fish containing a methylmercury level, and high hair mercury levels in addition to the various symptoms such as sensory disturbance (especially glove-and-stocking type, which is characteristic of Minamata disease), tremor, failure in two-point discrimination, and slight balancing failure, several subjects examined were diagnosed with mild Minamata disease. The findings obtained suggest, thus, that the mercury pollution in the Amazon should be crucially observed for head hair mercury level and health in a much broader region. PMID:11686639

Harada, M; Nakanishi, J; Yasoda, E; Pinheiro, M C; Oikawa, T; de Assis Guimarâes, G; da Silva Cardoso, B; Kizaki, T; Ohno, H

2001-10-01

109

[The people of the black waters: the Amazon caboclo of the Negro river].  

PubMed

The article constructs a historically contextualized description of the people who live along the Negro river, a Brazilian affluent in the Amazon basin. Drawing on information about the daily social experience of the participants from the dawn of the twentieth century through the mid-1990s, the processes by which the population and communities took shape are identified. On the Negro river, contact between Brazilian society and the autochthonous, catechized indigenous groups living there was determinant in shaping the territory's caboclo identity. Starting in the last quarter of the nineteenth century, this nomenclature took root and entered the popular lexicon. Extractivist activities played a major role in spreading the term, within a context where the predominant social relations derived from the 'cultura do barracão'. PMID:18783146

dos Santos, Fernando Sergio Dumas

2007-12-01

110

Miocene drainage reversal of the Amazon River driven by plate-mantle interaction  

NASA Astrophysics Data System (ADS)

Northern South America experienced significant changes in drainage patterns during the opening of the South Atlantic Ocean. Disappearance of a mega-wetland in the western Amazonian basins was followed by the formation of the eastward-draining Amazon River, which has been attributed to Andean uplift. However, South America's westward motion over cold, dense subducted slabs implies that regional subsidence and uplift east of the Andes may have been driven by mantle convection. Here we use a coupled model of mantle convection and plate kinematics to show that dynamic subsidence of up to 40mMyr-1 initially formed the Amazonian mega-wetland. In our model, the sustained westward motion of continental South America over subducted slabs resulted in rebound of the Amazonian mega-wetland region at rates of up to 40mMyr-1 after 30million years ago, paired with continued subsidence of the eastern Amazonian sedimentary basins at 10-20mMyr-1. The resulting progressive tilt of northern South America to the east enabled the establishment of the Amazon River, suggesting that mantle convection can profoundly affect the evolution of continental drainage systems.

Shephard, G. E.; Müller, R. D.; Liu, L.; Gurnis, M.

2010-12-01

111

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

112

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.

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

113

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

2011-08-19

114

ASSESSMENT OF THE SENSORS MODIS\\/TERRA AND WFI\\/CBERS-2 FOR THE AMAZON RIVER SUSPENDED SEDIMENT MONITORING  

Microsoft Academic Search

Suspended sediment load plays an important role in coastal processes. They can be used as a proxy for water quality variables such as turbidity, pollution and primary production. The large spatial and temporal variability of coastal environments, e.g. Amazon River mouth, makes it difficult the acquisition of spatially meaningful in situ data on suspended sediments. To overcome that problem the

G. S. F. Molleri; E. M. L. M. Novo; M. Kampel; L. M. G. Fonsecaa

115

Fish contamination and human exposure to mercury in Tartarugalzinho River, Amapa State, Northern Amazon, Brazil. A screening approach  

Microsoft Academic Search

This study reports for the first time, the Hg concentrations in the fish fauna of the Tartarugalzinho river basin - an important gold mining region in Amapa State, Northern Amazon - and evaluates human exposure to Hg due to fish consumption in the area. We analyzed 16 fish species (carnivorous and omnivorous) common in the aquatic environment of the Tartarugalzinho

E. D. Bidone; Z. C. Castilhos; T. J. S. Santos; T. M. C. Souza; L. D. Lacerda

1997-01-01

116

Seasonal dissolved rare earth element dynamics of the Amazon River main stem, its tributaries, and the Curuaí floodplain  

Microsoft Academic Search

We present a comprehensive dissolved rare earth element (REE) data set for the Amazon River and its main tributaries, Rio Negro, Solimões, and Madeira, as well as the Curuaí floodplain. The two-year time series show that REE vary seasonally with discharge in each of the tributaries, and indicate a hydrologically dominated control. Upper crust normalized REE patterns are relatively constant

Gwénaël Barroux; Jeroen E. Sonke; Geraldo Boaventura; Jérôme Viers; Yves Godderis; Marie-Paule Bonnet; Francis Sondag; Sébastien Gardoll; Christelle Lagane; Patrick Seyler

2006-01-01

117

Monitoring flood extent in the lower Amazon River floodplain using ALOS\\/PALSAR ScanSAR images  

Microsoft Academic Search

Abstract \\u000aThe Amazon River floodplain is subject to large seasonal variations in water level and flood extent, due to the large size and low relief of the basin, and the large amount of precipitation in the region. Synthetic Aperture Radar (SAR) data can be used to map flooded area in these wetlands, given its ability to provide continuous information without

Allan S. Arnesen; Thiago S. F. Silva; Laura L. Hess; Evlyn M. L. M. Novo; Conrado M. Rudorff; Bruce D. Chapman; Kyle C. McDonald

2013-01-01

118

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

119

Hydrodynamic 1D model of the Amazon river applied to the sediment transport.  

NASA Astrophysics Data System (ADS)

We are building a one-dimensional hydrodynamic model of Amazon river and its main tributaries, which takes also into account the solid transport capacities. The model is now performed on a large part of the Brasilian network. At first, the fit of the hydrodynamic model on the observed flood hydrographs in Manaus and Obidos permits us to estimate the part of the floodable areas on the flows (major bed and varzeas) Complementarily, the use of the laws of solid transport capacities depending on the hydraulic conditions is a good tool to analyse, understand and quantify the processes of erosion or deposit. Campaign of measurements are done at different periods of the hydrologic cycle on Amazon, Madeira, Solimoes and Rio Negro rivers: cross sections, bed levels, hydraulic discharges and current profiles with ADCP. The solid discharges are also estimated by measuring a lot of vertical concentration profiles (by sampling, in three verticals for each cross section) in different reaches of the rivers. Grain size distributions are then obtained in laboratory. These data permit us to define the balances and fluxes of suspended matter. A loading law (Dauber-Lebreton or Han formulations) is used in the sediment transport model under non equilibrium conditions. That permits us to propose some assumptions on the reaches in which occur phenomena of deposition or erosion according the flow regime (high or low water). At least, the contribution of the flooded areas is considered. Measurements are done to estimate the input and output flows of suspended matter in the varzea of Curuai, which is choosen as a specimen of a flooded area. The obtained data give some interesting informations on the behaviour of such areas in the balance of sediments.

Baume, J. P.; Kosuth, P.; Le Guennec, B.; Netto, A.; Nicod, J.

2003-04-01

120

[Prevalence of arterial hypertension in communities along the Madeira River, Western Brazilian Amazon].  

PubMed

The aim of this cross-sectional study was to estimate the prevalence of hypertension among adults (n = 841) in communities along the Madeira River in the Brazilian Amazon, prior to startup of the Santo Antônio Hydroelectric Plant. The study gathered information on sociodemographic conditions, history of diseases, habits, fish consumption, and anthropometric parameters. Logistic regression was used to calculate odds ratios and the respective confidence intervals. Among the riverine communities, 26% (95%CI: 23%-29%) of adults presented hypertension (29% in men [95%CI: 24%-33%] and 23% in women [95%CI: 19%-27%]). Factors associated with hypertension were age, BMI, and place of residence in men and age, triglycerides, and blood glucose in women. The findings can contribute to strategies for state and municipal health services to monitor and prevent cardiovascular events. PMID:24005927

de Oliveira, Beatriz Fátima Alves; Mourão, Dennys de Souza; Gomes, Núbia; Costa, Janaina Mara C; de Souza, Andreia Vasconcelos; Bastos, Wanderley Rodrigues; Fonseca, Marlon de Freitas; Mariani, Carolina Fiorillo; Abbad, Guilherme; Hacon, Sandra S

2013-08-01

121

Ontogeny of the plastron of the giant Amazon River turtle, Podocnemis expanse (Schweigger, 1812) (Testudines, Podocnemididae).  

PubMed

Podocnemis expanse, known popularly as the giant Amazon river turtle, is widely exploited. This makes specimens available for various studies, and we used this opportunity to investigate aspects of the development of the plastron. We examined several stages of pre- and post- hatching development in embryos and hatchlings collected starting from day 18 of natural incubation. Embryos and hatchlings were cleared and double stained for cartilage and bone. The epiplastron, endoplastron, hyoplastron, hypoplastron, xiphiplastron, and mesoplastron bones form the complete plastron of this turtle. In stage 16, bone centers become visible in most of the bones of the plastron. Alizarin Red stain retention indicated that the sequence of bone ossification is as follows: first the hyoplastron and the hypoplastron, then the endoplastron followed by the xiphiplastron, and lastly the mesoplastron. The epiplastron bone shows an ossification center only in stage 20. All these elements have independent ossification centers and join together only later. The plastron closes completely seven months after hatching. PMID:19663644

Gonçalves Vieira, Lucélia; Quagliatto Santos, André L; Campos Lima, Fabiano; Souza Pinto, José G

2009-07-01

122

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

123

Preliminary Measurements Of N2O Partial Pressures In Rivers of Amazon Basin, Brazil  

NASA Astrophysics Data System (ADS)

The concentrations of nitrous oxide (N2O), an important component of the greenhouse effect and with a long residence time in the atmosphere, have significantly increased in this century. The reasons for this atmospheric increase in N2O are still partially unexplained. This uncertainty is worse in relation to aquatic environments. Here we report on preliminary measurements of N2O partial pressures in rivers of the Amazon basin. The study areas are in the state of Rondonia (rivers Ji Parana, Urupa, Comemoracao and Pimenta Bueno) and Amazonas (rivers Solimoes and Negro). The rivers were sampled from October 2005 to April 2006, using with immersion pumps, lowered in the middle of the channel to 60% of total depth. Water was pumped directly into a 1 l plastic bottle, which was overflown three times before closing. Using syringes, 60 ml of N2 were injected into the bottle, simultaenously to the withdrawn of 60 ml of sample. N2O was extracted into these 60 ml of N2 by shaking vigorously for 2 minutes. With the same syringes, the gas was taken from the bottles and injected into sealed evacuated 25 ml vials. Atmospheric samples were taken from one meter above the water column and stored the same way. N2O partial pressures were determined on a Shimadzu GC-14 Green House Gas Analyzer. All rivers showed little variations in N2O partial pressures. Average values in the rivers of Rondonia were around 0.41 ± 0.07 ? atm (n=46), whereas the Solimoes and Negro rivers, in the state of Amazonas, showed values around 0.43 ± 0.08 ? atm (n=131). Atmospheric averages were approximately 0.34 ± 0.04 ? atm (n=58) and 0.32 ± 0.03 ? atm (n=134) in the states of Rondonia and Amazonas, respectively. This means that, although these waters are supersatured in CO2, making evasive fluxes of this gas an important component of the C cycle in this basin, the same does not occur in the N cycle. Small differences in partial pressures of N2O between water and air will result in small fluxes of this gas to the atmosphere from the middle of the river channels. However, at the river margins and riparian zones, significantly different redox conditions may occur, which should be further investigated to fully understand the role of N2O fluxes in these riverine systems.

Oliveira, C. B.; Rasera, M. F.; Krusche, A. V.; Victoria, R. L.; Richey, J. E.; Cunha, H. B.; Gomes, B. M.

2006-12-01

124

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

125

Impact of diatom-diazotroph associations on carbon export in the Amazon River plume  

NASA Astrophysics Data System (ADS)

Offshore tropical river plumes are associated with areas of high N2 fixation (diazotrophy) and biological carbon drawdown. Episodic blooms of the diatom Hemiaulus hauckii and its diazotrophic cyanobacterial symbiont Richelia intracellularis are believed to dominate that carbon drawdown, but the mechanism is not well understood. We report primary productivity associated with blooms of these diatom-diazotroph assemblages (DDAs) in the offshore plume of the Amazon River using simultaneous measurements of O2/Ar ratios and the triple-isotope composition of dissolved O2. In these blooms, we observe peaks in net community productivity, but relatively small changes in gross primary productivity, suggesting that DDA blooms increase the ecosystem carbon export ratio more than twofold. These events of enhanced export efficiency lead to biological uptake of dissolved inorganic carbon and silicate, whose longer mixed-layer residence times otherwise obscure the differential impact of DDAs. The shorter-term rate estimates presented here are consistent with the results derived from longer-term geochemical tracers, confirming that DDAs drive a significant biological CO2 pump in tropical oceans.

Yeung, Laurence Y.; Berelson, William M.; Young, Edward D.; Prokopenko, Maria G.; Rollins, Nick; Coles, Victoria J.; Montoya, Joseph P.; Carpenter, Edward J.; Steinberg, Deborah K.; Foster, Rachel A.; Capone, Douglas G.; Yager, Patricia L.

2012-09-01

126

New dactylogyrids (Monogenea) parasitizing the gills of catfishes (Siluriformes) from the Amazon River basin in Peru.  

PubMed

Three dactylogyrid (Monogenea) species are described from the gills of siluriform fishes from the rivers around Iquitos, tributaries of the Amazon River in Peru: Demidospermus centromochli n. sp. from Centromochlus heckelii (de Filippi) (Auchenipteridae) and Demidospermus macropteri n. sp. and Ameloblastella unapi n. sp. from Calophysus macropterus (Lichtenstein) (Pimelodidae). The new species of Demidospermus differ from their congeners in having 2 different hook shapes. Ameloblastella unapi n. sp. differs from the other 3 species of the genus in having anchors with an elongate, straight shaft and a short point that forms a 90 degrees angle, a coiled (counterclockwise) male copulatory organ with 13-14 rings, and a coiled vaginal tube. Based on the present study, Pseudovancleaveus Franca, Issac, Pavanelli, and Takemoto, 2003, is regarded as a junior subjective synonym of Ameloblastella Kritsky, Mendoza-Franco, and Scholz, 2000. The finding of Demidospermus and Ameloblastella spp. on these siluriforms extends our host and geographic knowledge of species of these monogenean genera to Peru. PMID:19215149

Mendoza-Franco, Edgar F; Scholz, T

2009-08-01

127

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

128

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

129

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

130

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

131

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

132

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

133

Fish contamination and human exposure to mercury in Tartarugalzinho river, Amapa State, Northern Amazon, Brazil. A screening approach  

Microsoft Academic Search

This study reports for the first time, the Hg concentrations in the fish fauna of the Tartarugalzinho river basin — an important\\u000a gold mining region in Amapa State, Northern Amazon — and evaluates human exposure to Hg due to fish consumption in the area.\\u000a We analyzed 16 fish species (carnivorous and omnivorous) common in the aquatic environment of the Tartarugalzinho

E. D. Bidone; Z. C. Castilhos; T. J. S. Santos; T. M. C. Souza; L. D. Lacerda

1997-01-01

134

Excitation-emission fluorescence matrix to study pHinfluence 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 (>0.22mm), colloidal and dissolved (o5 kD) organic matter. STUF process does not seem to alter the characteristic

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

2002-01-01

135

Physical and biological contributions to the western tropical North Atlantic Ocean carbon sink formed by the Amazon River plume  

Microsoft Academic Search

Dissolved inorganic carbon (DIC) and total alkalinity (TA) were measured in the upper 1000 m of the western tropical North Atlantic Ocean (WTNA; study area 3–15°N, 40–59°W) in January–February and July–August 2001. Concentrations of DIC and TA in surface samples (0–10 m) influenced by the Amazon River plume were up to 400 ?mol C kg?1 (?20%) lower than oceanic surface

S. R. Cooley; P. L. Yager

2006-01-01

136

Venezuelan equine encephalitis febrile cases among humans in the Peruvian Amazon River region.  

PubMed

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 and active disease surveillance program of the MOH. The clinical criterion for enrollment was the diagnosis of a suspected viral-associated, acute, undifferentiated febrile illness of < or = 5 days duration. A total of 598 patients were enrolled in the study. Demographic information, medical history, clinical data, and blood samples were obtained from each patient. The more common clinical features were fever, headache, myalgia, arthralgia, retro-ocular pain, and chills. Sera were tested for virus by the newborn mouse and cell culture assays. Viral isolates were identified initially by immunofluorescence using polyclonal antibody. An ELISA using viral-specific monoclonal antibodies and nucleotide sequence analysis were used to determine the specific variety of the viruses. In addition, thin and thick blood smears were observed for malaria parasites. Venezuelan equine encephalitis (VEE) virus subtype I, variety ID virus was isolated from 10 cases, including three cases in October, November, and December 1993, five cases in January and February 1994, and two cases in June 1995. The ELISA for IgM and IgG antibody indicated that VEE virus was the cause of an additional four confirmed and four presumptive cases, including five from January through March 1994 and three in August 1994. Sixteen cases were positive for malaria. The 18 cases of VEE occurred among military recruits (n = 7), agriculture workers (n = 3), students (n = 3), and general laborers (n = 5). These data indicated that an enzootic strain of VEE virus was the cause of at least 3% (18 of 598) of the cases of febrile illnesses studied in the city of Iquitos in the Amazon Basin region of Peru. PMID:9452289

Watts, D M; Callahan, J; Rossi, C; Oberste, M S; Roehrig, J T; Wooster, M T; Smith, J F; Cropp, C B; Gentrau, E M; Karabatsos, N; Gübler, D; Hayes, C G

1998-01-01

137

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

2011-12-08

138

Prawns and probability  

NASA Astrophysics Data System (ADS)

We will deonstrate the use of (more or less!) Bayesian methods for inferring interaction rules between individuals in a system of collective animal motion. We examine a group of prawns moving in an effectively one-dimensional environment, which we reduce to a binary classification problem, aiming to infer the factors that predict whether an individual will change its direction of motion. Our results show that interactions are primarily driven by spatial proximity, that prawns tend to align with other individuals travelling in the opposite direction and that the effect of interactions persist over time to create a non-Markovian system. This extended introduction provides technical details of the models we examine and some preliminary findings. The full results of this analysis will be published when complete.

Mann, Richard P.; Perna, Andrea; Strömbom, Daniel; Sumpter, David J. T.; Garnett, Roman; Herbert-Read, James E.; Ward, Ashley J. W.

2012-05-01

139

Flow in prawn burrows  

Microsoft Academic Search

The hydrodynamic properties of U-tubes, simulating the burrows of thalassinid prawn, Upogebia africana Ortmann were examined. Flow was induced through the U-tube as a result of a reduced pressure gradient set up by the external stream as it passed over a cone-shaped elevation, the Bernoulli effect, and was proportional to tube Reynolds number and its aspect ratio. Animals within their

B. R. Allanson; D. Skinner; J. Imberger

1992-01-01

140

DDT and its metabolites in breast milk from the Madeira River basin in the Amazon, Brazil.  

PubMed

Until the 1990s the 1,1,1-trichloro-bis-2,2'-(4chlorophenyl) ethane (DDT) was sprayed in the walls of the house along the Madeira River basin, Brazilian Amazon, a region well known for its large number of malaria cases. In 1910, Oswaldo Cruz described the presence of malaria in 100% of the population living in some localities from the Madeira River basin. Data available in the literature point to the DDT contamination in fishes captured in Madeira River region. Fish is the major source of dietary protein to these people. DDT tends to accumulate in lipid rich tissues and is being eliminated by different events, including lactation. Considering the importance of feeding breast milk to the children, the associated risks of DDT exposure via breast milk intake to children must be assessed. This is the main objective of this work: to analyse the presence of the p,p'-DDT and its metabolites p,p'-DDE and p,p'-DDD in 69 human milk samples and to estimate the intake of DDT and its metabolite in terms of total DDT (total DDT=p,p'-DDE+p,p'-DDD+p,p'-DDT). All the samples showed contamination with DDT and its metabolites ranging from 25.4 to 9361.9 ng of total DDT/g of lipid (median=369.6 ng of total DDT/g of lipid) and 8.7% of the estimated daily intake (EDI), in terms of total DDT, which was higher than the acceptable daily intake proposed by the WHO. PMID:18495200

Azeredo, Antonio; Torres, João P M; de Freitas Fonseca, Márlon; Britto, José Lailson; Bastos, Wanderley Rodrigues; Azevedo E Silva, Cláudio E; Cavalcanti, Giselle; Meire, Rodrigo Ornellas; Sarcinelli, Paula N; Claudio, Luz; Markowitz, Steven; Malm, Olaf

2008-05-20

141

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

2009-09-11

142

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

143

How important is it to integrate riverine suspended sediment chemical composition with depth? Clues from Amazon River depth-profiles  

NASA Astrophysics Data System (ADS)

The vertical variability in mineralogical, chemical and isotopic compositions observed in large river suspended sediments calls for a depth-integration of this variability to accurately determine riverine geochemical fluxes. In this paper, we present a method to determine depth-integrated chemical particulate fluxes of large rivers, based on river sampling along depth-profiles, and applied to the Amazon Basin lowland tributaries. The suspended particulate matter (SPM) concentration data from depth-profiles is modeled for a number of individual grain size fractions using the Rouse model, which allows to predict the grain size distribution of suspended sediment throughout the whole river cross-section. Then, using (1) the relationship between grain size distribution and the Al/Si ratio (2) relationships between the Al/Si ratio and the chemical concentrations, the chemical composition of river sediment is predicted throughout the river cross-section, and integrated to yield the depth-integrated chemical particulate flux for a number of chemical elements (e.g. Si, Al, Fe, Na, REEs, …). For elements such as Al, Fe, REEs, Th, the depth-integrated flux is around twice as high as the one calculated from river surface sample characteristics. For Na and Si, the depth-integrated flux is three times higher than the "surface" estimate, due to the enrichment of albite and quartz at the bottom of the river. Depth-integrated 87Sr/ 86Sr composition of suspended sediment, also predictable using this method, differs by more than 10 -3 from the surface sample composition. Finally, potential implications of depth-integrated estimates of Amazon sediment chemistry are explored. Depth-integration of particulate 87Sr/ 86Sr isotopic ratios is necessary for a reliable use of Sr isotopes as a provenance tracer. The concept of steady-state weathering of a large river basin is revisited using depth-integrated sediment composition. This analysis shows that, in the Amazon Basin river, the previously observed discrepancy between (1) weathering intensities of channel surface sediment and (2) silicate-derived dissolved fluxes is only slightly accounted for by the vertical variability of suspended sediment weathering intensities. This observation confirms that most large rivers basins are not eroding at steady-state.

Bouchez, Julien; Lupker, Maarten; Gaillardet, Jérôme; France-Lanord, Christian; Maurice, Laurence

2011-11-01

144

Late Quaternary Paleohydrology of the Madre de Dios River, southwestern Amazon Basin, Peru  

NASA Astrophysics Data System (ADS)

Late Quaternary climatic and hydrologic variability triggered changes in fluvial deposition and erosion along the course of the Madre de Dios River, Peru, the largest tributary basin of the Madeira basin, itself the largest tributary basin of the Amazon. Three laterally extensive, Quaternary-age, terrace tracts are present within the Madre de Dios basin. Analysis of sedimentary facies, present in the modern cut banks and terraced sequences, along with radiocarbon dates on fossil wood and leaf material preserved in the terraced strata, allow reconstruction of the Late Quaternary depositional history of the sedimentary sequences, including determination of the approximate timing of aggradation and downcutting episodes and its relationship to the timing of past climate change in this portion of the Amazon basin and beyond. The Quaternary sediments underlying the terraces most often recorded deposition in a coarse-grained meandering fluvial system. The T3 terrace, the highest terrace, is underlain by the Miocene (?) Ipururi Formation, which is unconformably overlain by the late Miocene-Pleistocene (?) (> 48,000 cal yrs BP) Madre de Dios Formation, a multistory coarse-sandy to gravelly channel and point bar complex. The latter was downcut before 29,850 ± 100 cal yrs BP. This downcut landscape was infilled by meandering fluvial strata characterized by gravelly channel deposits in a sequence dominated by floodplain and lateral accretion deposits. These strata were in turn downcut to form the T2 terrace before 11,970 ± 100 cal yrs BP. A third episode of aggradation resulted in the deposition of a sand-dominated meandering channel complex that infilled the T2 valley and was subsequently downcut after 3780 ± 50 cal yrs BP. This most recent terrace is infilled by the modern fluvial sediment, which has been actively aggrading since at least 870 ± 50 cal yrs BP. Importantly, the Madre de Dios fluvial system actively aggraded between 30,000 and 25,000 cal yrs BP, (and likely much younger, as dated samples were, thus far, only found near the base of the T2 sequence). This observation implies that some combination of (1) increased precipitation and decreased temperature, (2) decreased evapotranspiration and increased runoff, (3) increased Andean glacial erosion and increased sediment supply, and (4) decreased atmospheric CO 2 (hence decreased rain-forest primary productivity and altered rain-forest physiology/ecology), entering the last glacial maximum period brought about increased floodplain deposition in the southwestern Amazon. Elsewhere in the Amazon basin few, if any, fluvial sediments of this age range have been observed. The start of the next major phase of aggradation coincided with the Younger Dryas and suggested that floodplain sedimentation in the lowlands was again related to cold and wet conditions in the adjacent highlands (and perhaps in the lowlands as well) and that Madre de Dios history was also tied to large-scale global climate. This aggradation may have continued throughout the early and mid-Holocene, until at least 3,780 cal yr BP. If so (and this is uncertain), this episode of sedimentation took place during a dry period.

Rigsby, Catherine A.; Hemric, Erin M.; Baker, Paul A.

2009-12-01

145

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

146

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

147

How plants of the Amazonian floodplain (Brazil) can affect the geochemical status of trace elements in the Amazon River mainstream?  

NASA Astrophysics Data System (ADS)

Multi-element analysis of plant tissue samples increased this last 20 years, in relation to chemical weathering processes. However, if plants play a key role in terms of storage and transfer of elements (major and trace) in natural ecosystems, our knowledge of transfer processes and fluxes are still poor. In the present study, we measured the concentrations of major and trace elements in the leaves of four different species (annual and perennial) of an amazonian floodplain during one hydrological period. The studied site is the “Ilha de Marchantaria" (3°15'S; 60°00'W) located on the Solimões River (Upper Amazon), near the city of Manaus. The results reveal high concentrations (from 10 to 1000 ppm for Al, Mn and Fe; from 10 to 100 ppm for Rb, Sr and Ba) in leaves and an annual variation wich is reverse of the river discharge (High concentrations for low water level and low concentrations for high water level). According with datas of net primary production (100 t.ha^{-1}y^{-1}) and of total floodplain area (200000 km^2), we estimate the amount of trace elements stored or recycled in the vegetation of the amazon floodplains. We also observed that the amount of trace metals exported by the amazon [9] is one hundred time less than the amount of trace metals stored or recycled by the vegetation.

Barroux, G.; Viers, J.; Seyler, P.; Oliva, P.; Dupré, B.; Guyot, J.-L.; Pinelli, M.

2003-05-01

148

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

NASA Astrophysics Data System (ADS)

The present study compares three meteorological drought indices (scPDSI, SPI and SPEI respectively) and their ability to account for the variations of annual mean river discharge on both interannual and climate change timescales. The Standardized Runoff Index (SRI) is used as a proxy of river discharge. The Mississippi and Amazon river basins provide two contrasted testbeds for this analysis. All meteorological drought indices are derived from monthly 2-meter temperature and/or precipitation, using either gridded observations or outputs of a global climate model. The SPI based solely on precipitation is not outperformed by the SPEI (accounting for potential evapotranspiration) and the scPDSI (based on a simplified water balance) at detecting interannual SRI variations. Under increasing concentrations of greenhouse gases, the simulated response of the areal fraction in drought is highly index-dependent, suggesting that more physical water balance models are needed to account for the impact of global warming on hydrological droughts.

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

2012-11-01

149

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

150

First report of major histocompatibility complex class II loci from the Amazon pink river dolphin (genus Inia).  

PubMed

We report the first major histocompatibility complex (MHC) DQB1 sequences for the two species of pink river dolphins (Inia geoffrensis and Inia boliviensis) inhabiting the Amazon and Orinoco River basins. These sequences were found to be polymorphic within the Inia genus and showed shared homology with cetacean DQB-1 sequences, especially, those of the Monodontidae and Phocoenidae. On the other hand, these sequences were shown to be divergent from those described for other riverine dolphin species, such as Lipotes vexillifer, the Chinese river dolphin. Two main conclusions can be drawn from our results: 1) the Mhc DQB1 sequences seem to evolve more rapidly than other nuclear sequences in cetaceans, and 2) differential positive selective pressures acting on these genes cause concomitant divergent evolutionary histories that derive phylogenetic reconstructions that could be inconsistent with widely accepted intertaxa evolutionary relationships elucidated with other molecular markers subjected to a neutral dynamics. PMID:17117356

Martínez-Agüero, M; Flores-Ramírez, S; Ruiz-García, M

2006-07-31

151

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

152

Microsatellite loci for population and parentage analysis in the Amazon River dolphin (Inia geoffrensis de Blainville, 1817).  

PubMed

We developed specific primers for microsatellite DNA regions for the Amazon River dolphin or boto Inia geoffrensis, for use in population and conservation genetic studies. We also tested their transferability for two other species, Pontoporia blainvillei (sister taxon of I. geoffrensis) and Sotalia guianensis. A total of 12 microsatellite loci were polymorphic for the boto. An additional 25 microsatellite loci previously isolated from other cetacean species were also tested in the boto. The 26 polymorphic microsatellite loci indicate they will be excellent markers for studies of population structure and kinship relations of the boto. PMID:21564703

Gravena, Waleska; Hrbek, Tomas; DA Silva, Vera M S; Astolfi-Filho, Spartaco; Farias, Izeni P

2009-01-31

153

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

2013-03-07

154

Evaluation of the Amazon River delta as a barrier to gene flow for the regional malaria vector, Anopheles aquasalis (Diptera: Culicidae) in northeastern Brazil.  

PubMed

The Neotropical malaria vector Anopheles aquasalis Curry is distributed predominantly along the Atlantic and Pacific Coasts because of its tolerance for breeding in salt water. We tested the hypothesis that the freshwater Amazon River acts as a barrier to gene flow in northeastern Brazil, by examining variation at a 588-nucleotide fragment of the mitochondrial cytochrome oxidase Igene from five populations. We identified 15 haplotypes of which 5 were shared both (1) between sample localities and (2) across the Amazon River Delta. Sequence divergence ranged from 0.0017-0.0272 (average = 0.0137). Estimates of genetic subdivision based on the presence of the Amazon Riverwere greatest within localities (phi = 0.029) and among regions (phi = 0.018), followed by among localities (phi = 0.011), but none were significant. Parsimony, neighbor-joining, and Nested Clade Analyses were used to estimate relationships among populations and infer evolutionary processes. Two phylogenetically distinct clusters of populations were moderately supported by parsimony. Neighbor-joining trees were poorly resolved, thus providing no geographical resolution and no support for the Amazon River as a barrier to migration. Phylogeographic structure as detected by the Nested Clade Analysis was consistent with restricted gene flow coupled with isolation by distance. Taken together, these analyses suggest that the localities within this region of northeastern Brazil constitute a single large population of An. aquasalis that spans the Amazon Delta. PMID:12495184

Fairley, T L; Póvoa, M M; Conn, J E

2002-11-01

155

Fluxes of Carbon from Land to the Sea: What happens in the last 900 km of the Amazon River?  

NASA Astrophysics Data System (ADS)

Just as the role of gas evasion has classically been overlooked in the carbon balance of fluvial systems, we have also neglected to fully examine the sequence of processes that occur when freshwater meets the sea. Most, if not all, characterizations of the mass flux of material from rivers to the ocean have been performed at the downstream-most gauging station on that river. Such stations are typically located a considerable distance from the actual confluence of the river with the sea, usually above tidal influences. In the case of the Amazon River, for example, the defining gauge is located at Óbidos, some 900 km from the sea. In the reach below Óbidos, three major tributaries plus many smaller tributaries and local flood plain drainages, add ~40,000 m3/s, or an additional 20% to the river's total annual discharge (about two Mississippi Rivers' worth, with very different chemistry, than upstream). Here we examine the transitions in OM, DIC, and O2 signatures, from Óbidos to the sea. For example, preliminary results from the lower river, December 2010 (low water), provide provocative evidence of the evolution of water parcels in transit to the ocean. The ?13C DIC becomes depleted downstream, and ?18O-O2 becomes more depleted, particularly on the Belem side. Again, the lower river receives considerable waters from the productive mouthbay rivers. That the R:P ratio is 1.93 even at Óbidos indicates that significant photosynthetically O2 is present, which is augmented downstream. The question is, how much of this oxygen is legacy produced within in floodplain or tributary environments or in the mainstem? How much production-derived OM accompanies the O2? What does this say about the evolution of terrestrial signals in transit to the sea, under current and changing conditions?

Richey, J. E.; Krusche, A.; Ward, N.

2011-12-01

156

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

157

Statistical analysis of climate-driven spatio-temporal variations of GRACE Total Water Storage in the Amazon River basin  

NASA Astrophysics Data System (ADS)

The hydrology of the Amazon River basin is characterized by a strong annual cycle due to the annual oscillation of the Inter Tropical Convergence Zone about the equator. However, this strong annual cycle shows significant inter-annual variations. For example, during the GRACE period, two severe drought periods occurred in 2005 and 2010 as well as strong floods in 2009. With now more than 9 years of GRACE data, investigation of such non-linear, long-period oscillations is possible. The Amazon River basin is strongly coupled with the climate system. Therefore, we investigate the possible relationships between total water storage variations from GRACE and different climate oscillations originating in the tropical Pacific and Atlantic Oceans (such as ENSO and AMO). Based on purely statistical methods (Rotated Empirical Orthogonal Functions and lead/lag correlation) we show that different sub-regions of the basin have different connections with different climate indices. In particular, we show the sensitivity of GRACE data to different types of El Niño. Finally, by means of a Multichannel Singular Spectrum Analysis we analyze and then compare the quasi-periodic constituents of GRACE total water storage and climate indices.

de Linage, C.; Kim, H.; Famiglietti, J.

2012-04-01

158

Seasonal dissolved rare earth element dynamics of the Amazon River main stem, its tributaries, and the Curuaí floodplain  

NASA Astrophysics Data System (ADS)

We present a comprehensive dissolved rare earth element (REE) data set for the Amazon River and its main tributaries, Rio Negro, Solimões, and Madeira, as well as the Curuaí floodplain. The two-year time series show that REE vary seasonally with discharge in each of the tributaries, and indicate a hydrologically dominated control. Upper crust normalized REE patterns are relatively constant throughout the year, with Ce/Ce* anomalies being positively related to discharge. We propose revised annual dissolved REE fluxes to the surface Atlantic Ocean based on an integration of the seasonal data. For Nd (<0.22 ?m) this results in an average flux of 607 ± 43 T/yr, which is at least 1.6 times larger than the previous estimate of 374 T/yr (<0.45 ?m) based on low water stage data. Moreover, during the high water season the maximum Nd flux measures 1277 t.yr-1, constituting 30% of the required flux to the Atlantic Ocean (Tachikawa et al., 2003). Consequently, a smaller contribution of Nd from atmospheric and river particle desorption is required than was previously suggested. A mass balance of Amazon tributaries and observed fluxes at Óbidos indicates that dissolved LREE behave quasi-conservatively. Conversely, the HREE mass balance presents a deficit during the high water stages, which could be related to the passage of water through the floodplain system accompanied by solid/dissolved phase transfer.

Barroux, GwéNaëL.; Sonke, Jeroen E.; Boaventura, Geraldo; Viers, JéRôMe; Godderis, Yves; Bonnet, Marie-Paule; Sondag, Francis; Gardoll, SéBastien; Lagane, Christelle; Seyler, Patrick

2006-12-01

159

Methylmercury exposure affects motor performance of a riverine population of the Tapajós river, Brazilian Amazon.  

PubMed

Gold mining and deforestation in the Brazilian Amazon are increasing mercury pollution of the extensive water system, exposing riverine populations to organic mercury through fish-eating. The aim of the present study was to evaluate the effect of such exposure on motor performance. This cross-sectional study was carried out in May 1996, in a village located on the banks of the Tapajós river in the Amazonian Basin, Brazil. Information concerning sociodemographics, health, smoking habits, alcohol drinking, dietary habits and work history were collected using an interview-administered questionnaire. Mercury concentrations were measured by cold vapor atomic absorption in blood and hair of each participant, of whom those aged between 15 and 79 years were assessed for motor performance (n = 84). Psychomotor performance was evaluated using the Santa Ana manual dexterity test, the Grooved Pegboard Fine motor test and the fingertapping motor speed test. Motor strength was measured by dynamometry for grip and pinch strength. Following the exclusion of 16 persons for previous head injury, working with mercury in the goldmining sites, or for diabetes, the relationship between performance and bioindicators of mercury was examined using multivariate statistical analyses, taking into account covariables. All participants in the study reported eating fish, which comprised 61.8% of the total meals eaten during the preceding week. The median hair total mercury concentration was 9 microg/g. Organic mercury accounted for 94.4 = 1.9% of the total mercury levels. Multivariate analysis of variance indicated that hair mercury was inversely associated with overall performance on the psychomotor tests, while a tendency was observed with blood mercury. Semipartial regression analyses showed that hair total mercury accounted for 8% to 16% of the variance of psychomotor performance. Neither hair nor blood total mercury was associated with the results of the strength tests in women and men. Although dose-effect relationships were observed in this cross-sectional study, they may reflect higher exposure levels in the past. The findings of this study demonstrated neurobehavioral manifestations of subtle neurotoxic effects on motor functions, associated with low-level methylmercury exposure. PMID:10787135

Dolbec, J; Mergler, D; Sousa Passos, C J; Sousa de Morais, S; Lebel, J

2000-04-01

160

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

NASA Astrophysics Data System (ADS)

We assessed the effects of hydrodynamical variations on the distributions and sources of branched and isoprenoid glycerol dialkyl glycerol tetraethers (brGDGTs and isoGDGTs, respectively) transported by the Amazon River in the central Amazon basin. Particulate suspended matter was collected in the Amazonian rivers and floodplain lakes at four different seasons (rising water, high water, falling water, and low water) at 6 stations along the main stem of the Amazon River, 3 tributaries (Negro, Madeira, and Tapajós) and 5 floodplain lakes (Manacapuru, Janauacá, Mirituba, Canaçari and Curuai). The concentration and distribution of brGDGTs of both core lipid (CL) and intact polar lipid (IPL)-derived fractions were investigated applying IPL-derived brGDGTs as an indicator of brGDGTs derived from recently-living cells. The organic carbon (OC)-normalized concentrations of CL brGDGTs mimicked the trend of the hydrological variation with highest concentrations during the high water season. The CL brGDGT distributions were most alike those of lowland Amazon (terra firme) soils during the high water season, indicating that input of soil-derived, allochthonous brGDGTs to the Amazon River was highest at that period. Accordingly, the methylation index of branched tetraethers (MBT) and the cyclization ratio of branched tetraethers (CBT) varied corresponding to the hydrological changes, with the increasing influence of in situ produced brGDGTs in rivers and floodplain lakes during the low water season. The concentrations of CL crenarchaeol were highest during the low water season, due to increased autochthonous production. The concentration changes of both brGDGTs and crenarchaeol lead to a variation of the branched and isoprenoid tetraether (BIT) index between 0.4 (low water) and 0.9 (high water). Hence, our study hints at the effect of hydrodynamical variations on the source of brGDGTs and isoGDGTs transported by rivers to the ocean and emphasized the importance of a detailed study of a river basin before applying the MBT/CBT paleothermometer and the BIT index in the adjacent marine setting.

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

2013-04-01

161

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

162

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

163

Mercury pollution in the Tapajos River basin, Amazon Mercury level of head hair and health effects  

Microsoft Academic Search

There is increasing concern about the potential neurotoxic effects of exposure to methylmercury for the 6 million people living in the Amazon, even in regions situated far away from the gold mines (garimpos), considered to be the major source of mercury pollution. In November 1998, a spot investigation on mercury contamination was conducted in three fishing villages (Barreiras, Rainha, and

Masazumi Haradaa; Maria da Conceicao; N. Pinheiroc; Hideki Ohnod

164

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

165

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

2011-11-10

166

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

167

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

168

Methylmercury exposure affects motor performance of a riverine population of the Tapajós river, Brazilian Amazon  

Microsoft Academic Search

Gold mining and deforestation in the Brazilian Amazon are increasing mercury pollution of the extensive water system, exposing\\u000a riverine populations to organic mercury through fish-eating. The aim of the present study was to evaluate the effect of such\\u000a exposure on motor performance. This cross-sectional study was carried out in May?1996, in a village located on the banks of\\u000a the Tapajs

J. Dolbec; D. Mergler; C.-J. Sousa Passos; S. Sousa de Morais; J. Lebel

2000-01-01

169

Evaluation of the Amazon River delta as a barrier to gene flow for the regional malaria vector, Anopheles aquasalis (Diptera: Culicidae) in northeastern Brazil  

Microsoft Academic Search

The Neotropical malaria vector Anopheles aquasalis Curry isdistributed predominantly along the Atlantic and PaciÞc Coasts because of its tolerance for breeding in salt water. We tested the hypothesisthat the freshwater Amazon River actsasa barrier to gene ßow in northeastern Brazil, by examining variation at a 588-nucleotide fragment of the mitochondrial cytochrome oxidase I gene from Þve populations. We identiÞed 15

T. L. Fairley; M. M. Póvoa; J. E. Conn

2002-01-01

170

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

171

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

172

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

173

How well does the ERA40 surface water budget compare to observations in the Amazon River basin?  

NASA Astrophysics Data System (ADS)

The surface water budget of the Amazon River basin derived from the ERA40 reanalysis is evaluated by comparing it with observed precipitation (P), streamflow/runoff (R), and evapotranspiration (ET) data sets for the period of 1980-2002. The rainfall is averaged over 90% of the Amazon River basin, corresponding to the catchments of the Óbidos and Altamira streamflow gauges. The annual rainfall and the interannual changes from ERA40 fall within the range of the two precipitation data sets. On the seasonal timescale, ERA40 reproduces well the rainfall during the dry and transition seasons, but it underestimates the wet season rainfall by 4-11% when compared with the two precipitation data sets. On the subbasin scale, the disparity in precipitation between ERA40 and observations is as much as ±40%. The annual runoff integrated over the two catchments is underestimated in ERA40 by 25%. The rain-rates in ERA40, which affect both throughfall and runoff, are comparable to those measured by the Tropical Rainfall Measurement Mission (TRMM 3B42V6), when these are rescaled to the resolution of the 2.5° ERA40 data. However, even the native resolution of ERA40 (˜1.125°) is greater than the scale of tropical convection. ET in ERA40 appears to be higher than observations by about 20%, although observed ET may have a 10% low bias. The difference between precipitation and runoff, P-R, in ERA40 generally agrees with observations. However, annual ERA40 ET is greater than P-R, because soil moisture nudging adds water to the soil. On the seasonal scale, soil moisture nudging is largest during the dry season, because ERA40 provides only a 45 mm surplus of P-R relative to ET during the wet season, whereas the deficit in the dry season is almost four times greater. This low bias in wet season soil moisture recharge may be caused by the underestimation of wet season rainfall in ERA40. It is possible that the model interception may have a high bias, which contributes to the high ET in the rainy season and reduces the wet season storage.

Fernandes, KáTia; Fu, Rong; Betts, Alan K.

2008-06-01

174

Microbiological quality of freshwater prawns during storage  

Microsoft Academic Search

Microbiological quality analysis of freshwater prawns from three sampling sites in Peninsular Malaysia viz: Site 1- Kg. Jumbang, Negri Sembilan; Site 2- Kg. Cangkat Tin, Perak and Site 3- Kg. Cenderiang, Perak for total mesophilic and psychrophilic aerobic counts, proteolytic bacterial counts, histamine producing bacteria, cadaverine producing bacteria and putrescine producing bacteria in the prawns and pond water for the

Abu Bakar; M. Basri

2008-01-01

175

Similarity between trace-element composition of river and seabed sediments in the Amazon system  

NASA Astrophysics Data System (ADS)

The aim of this paper was to study the elemental composition of sediments in the Amazon ecosystem by comparing bottom samples from the shelf with those from the floodplain of the Rio Amazonas. Trace elements measured by neutron activation analysis were used. The system is divided into three parts: the basin, including tributaries from the pre-Andean region to Óbidos; the delta—plain region between Óbidos and the mouth; and the continental shelf. Significant correlation was found between the shelf and floodplain sediments, especially those samples close to the mouth. In the shelf surface samples, Ta, Eu, La, and Ce (in this order) have the lowest coefficients of variation in concentration, whereas Hf, Br, and Cs have the greatest.

Ferraz, E. S. B.; Fernandes, E. A. N.; Oliveira, H.

1996-03-01

176

Physical and chemical post-dam alterations in the Jamari River, a hydroelectric-developed river of the Brazilian Amazon  

Microsoft Academic Search

The regulation of the Jamari River advanced peak floods by 1–2 months and increased dry-season discharges from 60 to 200 m3 s-1, resulting in water levels approximately 1 m above those recorded before regulation. Daily variation in water level associated with fluctuations in electricity production by the dam propagated to the lower reaches of the tributary Candeias River. Dissolved oxygen

João Paulo Viana

2002-01-01

177

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

2012-06-23

178

Redescription of Houssayela sudobim (Woodland, 1935) (Cestoda: Proteocephalidea), a parasite of Pseudoplatystoma fasciatum (Pisces: Siluriformes) from the River Amazon.  

PubMed

The proteocephalidean cestode Houssayela sudobim (Woodland, 1935), the type and only species of Houssayela Rego, 1987, is redescribed on the basis of re-examination of its type-specimens and freshly collected material found in the intestine of the barred sudobim Pseudoplatystoma fasciatum (Siluriformes: Pimelodidae) from the River Amazon in Peru. The validity of the genus is confirmed, but its diagnosis is amended because suckers possess four pairs of cone-shaped (papilla-like) projections on their anterior margins (rather than 16, as reported in the original description), the actual number of testes is more than 400 in a proglottis (not 150 as given by Woodland, 1935) and the vitelline follicles form one dorsolateral medullary band and one lateral cortical band on both sides of proglottides. In addition, the distal (terminal) portion of the vagina has a double sphincter and the cirrus-sac has very thick walls; neither of these characteristics was mentioned in the original description. The specimen collected in Peru represents the first record of the species since its original description in 1935. PMID:16315076

de Chambrier, Alain; Scholz, Tomás

2005-11-01

179

Carbon Sequestration by Coupled Landslide/Floodplain Deposition during Large Storms in River Basins of the Andean Amazon  

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 Niña-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 "fresh" 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 percent of the atmospheric CO2 anomalies typically observed during La Niña 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-Brougoin, L.

2006-12-01

180

[Adaptation and validation of the Alcohol Use Disorders Identification Test (AUDIT) for a river population in the Brazilian Amazon].  

PubMed

The objective of this study was to validate the Alcohol Use Disorders Identification Test (AUDIT) for a river population in the Brazilian Amazon. The original English version of AUDIT was translated into Portuguese, using the procedure recommended by the World Health Organization. The text was then back-translated and submitted to a native English translator, who approved the translation. AUDIT was administered to 361 inhabitants for a total of three times in two weeks. Data were analyzed for test/retest reliability and internal consistency. Cronbach's alpha was 0.87 at the first interview, 0.87 at the second, and 0.86 at the third. Test/retest reliability assessed via the intra-class correlation coefficient for the total AUDIT scale was 0.93. Area under ROC was 0.805 for a cutoff of seven (sensitivity 76.4%; specificity 75%). The validated AUDIT proved to be internally consistent and stable over time, but requires further investigation of its psychometric properties. PMID:21519700

Moretti-Pires, Rodrigo Otávio; Corradi-Webster, Clarissa Mendonça

2011-03-01

181

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

182

Use of Precipitation - Runoff Models to Generate Hydrologic Scenarios in a High-altitude Andean Basin of the Ecuadorian Amazon Region. Case study of the Quijos River Basin.  

NASA Astrophysics Data System (ADS)

Little is known of the hydrology and meteorology of the expansive Andean Amazon region in South America, which extends for approximately 600.000 Km2 and represents around the 10% of the total Amazon region. Climatic processes that occur in the Andean part of the Amazon influence the middle and lower parts of the Amazon Region. Consequently, there is a need to understand the hydro-climatic characteristics in the high lands of the Andean Amazon. Understanding hydrologic processes in the Andean Amazon is challenged by the lack of hydro meteorological data at all levels. Especially challenging is the absence of data at the appropriate scale for adequate calibration and verification of mathematical models, mainly for understanding precipitation - runoff of high altitude watersheds located on the western most part of the Amazon. The study area is located on the upper part of the Napo River named the Quijos river basin after the junction of the Oyacachi River with a surface area of about 2.500,00 Km2. It is composed mainly of high altitude lands named Paramo, Andean grass lands, primary cloudy forest known for their high water retention and regulatory capacity. The models used in the Quijos river basin in the upper part of the Amazon region of Ecuador are precipitation-runoff models widely used around the world. The Simulator for Water Resources in Rural Basins - Water Quality (SWRRBWQ ) (Arnold et. al. 1990, Williams et. al. 1985), works on a daily time steps basis with daily values of meteorological data both observed in the field or generated by the model, and by sub diving the main basin into a suitable number of sub basins with a meteorological station in it The second model used is the Hydrologic Modeling System from the Hydrologic Engineering Center which is a precipitation - runoff model run at a daily basis as well. Input data sets are basic climate data as precipitation, evapotranspiration, temperature, relative humidity basin wide at daily basis; land cover, soil type, soil characteristics, hydrographic characteristics, as well as registered discharge information in several control points of the basin, that were used for calibration purposes. Several runs of the models were done in order to assess parameter sensibility of the models using appropriate parameter for each case. Calibration for the two models were done for a period where enough information exists even though the time record for verification purposes is well ahead of time so it is assumed that basin wide conditions have not change in time. Three hydrologic scenarios for future discharge prediction based on conservation policies, urbanization, deforestation, or land use change on the area were generated by using HEC-HMS model for the January 1984 - December 1987 period because of its better performance in comparison to the SWRRBWQ model. Scenarios one and two showed almost no difference with the original discharge but scenario three showed an increase in water discharge with time. Results show that in high altitude basins the HEC-HMS performs better than SWRRBWQ model in determining mainly peak discharges but differed in reproducing the total volume of run-off, keeping a good agreement to reproduce seasonality patterns of water discharge. Better information of basin wide characteristics like soil antecedent moisture conditions, land cover, and surface albedo during the calibration period is needed in order to improve model results mainly in volume discharge.

Galarraga, R.; McClain, M.; Ortega, F.; Estacio, A.; Febres, A.

2007-05-01

183

Spatial and temporal coherence between Amazon River discharge, salinity, and light absorption by colored organic carbon in western tropical Atlantic surface waters  

NASA Astrophysics Data System (ADS)

The temporal evolution and spatial distribution of surface salinity and colored detrital matter (cdm) were evaluated within and adjacent to the Amazon River Plume. Study objectives were as follows: first, to document the spatial coherence between Amazon discharge, salinity, cdm, and the nature of the salinity-cdm relationship; second, to document the temporal and spatial variability of cdm along the trajectory of the low-salinity Amazon Plume, and third, to explore the departure of cdm from conservative mixing behavior along the plume trajectory into the open ocean. Time series (2003-2007) of surface salinity estimated using the Advanced Microwave Scanning Radiometer-Earth Observing System and corresponding satellite cdm absorption (acdm) data documented a plume of freshened, colored water emanating from the Amazon. Salinity and acdm were generally coherent, but there were regions in which spatial patterns of salinity and acdm did not coincide. Salinity was oppositely phased with discharge, whereas acdm was in phase but lagged discharge and typically remained high after maximum discharge. Along the river plume trajectory, acdm was inversely correlated with salinity, yet there was considerable deviation from conservative mixing behavior during all seasons. Positive anomalies in a linear relationship between salinity and acdm corresponded to areas of enhanced satellite-retrieved net primary productivity, suggesting the importance of phytoplankton biomass or its subsequent remineralization as a source of cdm. Negative anomalies tended to predominate at the distal sections of the plume trajectories, an observation consistent with the process of photo-oxidation of cdm over observed time scales of days to weeks.

Salisbury, J.; Vandemark, D.; Campbell, J.; Hunt, C.; Wisser, D.; Reul, N.; Chapron, B.

2011-07-01

184

Seasonal effects of wastewater to the water quality of the Caeté river estuary, Brazilian Amazon.  

PubMed

Bragança's socioeconomic situation is highly dependent on estuarine and marine biological resources that are influenced by tidal cycles and climatology. Field measurements (hydrological, hydrodynamic and microbiological variables) were taken in the most urbanized zone from Caeté estuary to characterise the quality of the local environment. During the dry period, the estuary was more eutrophic and presented the highest temperature (30.5 degrees C in Oct./06), salinity (17 psu in Feb./07), pH (8.24 in Feb./07) and fecal coliform (> 1000 MPN/100 ml in Dec./06 and Feb./07) values. The phytoplankton Cyclotella meneghiniana, Coscinodiscus centralis and other r-strategist species were observed. The lack of basic hydric canalization was responsible for the local contamination, especially during the dry period when more concentrated wastewater from the city was emitted into the estuary, showing the human influence on the reduction of local estuarine water quality. In Bragança, the fishery is considered one of the main economic activities so, this contamination is worrisome because a large part of the local economy depends on biological resources and, thus, the contamination could negatively affect the environmental health of this Amazon ecosystem. PMID:20563427

Pereira, Luci C C; Monteiro, Marcela C; Guimarães, Danielly O; Matos, Jislene B; Costa, Rauquírio M da

2010-06-01

185

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

186

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

187

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

188

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

Microsoft Academic Search

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

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

2010-01-01

189

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

2013-05-05

190

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

191

Detection of long-term trends in monthly hydro-climatic records of Colombia and the Amazon River basin through Empirical Mode Decomposition  

NASA Astrophysics Data System (ADS)

We search for long-term trends in 25- to 50-year records of monthly rainfall (100 stations), average river discharges (42 stations), and mean and minimum air temperature records (37 stations) in Colombia, as well as monthly records in 29 rain gauges within the Amazon River basin. Time series of average monthly river discharges are selected from 10 Colombian river basins with gauging stations located downstream along the main channel. The Empirical Mode Decomposition (EMD) method is used as a filtering process to decompose a given time series into a finite number of intrinsic mode functions (IMF), assuming that diverse simple oscillatory modes of different frequencies coexist in the series, and that the residual captures the long-term trend of the record. The Mann-Kendall test for autocorrelated data is used to assess the statistical significance of the trends, and the Sen test is used for the magnitude of the trends. Results show that 62% of monthly river discharge series exhibit decreasing trends between 0.01-1.92 m3/s yr-1. The identified trends are strongly consistent downstream, albeit with contrasting results for the ratios between the magnitude of the trend and mean discharges. Most minimum temperature series (87%) show increasing trends [0.01-0.08°C yr-1]. Results on precipitation are inconclusive as monthly records exhibit a mixed pattern of increasing (41%, between 0.1-7.0 mm yr-1) and decreasing (44%, between 0.1-7.4 mm yr-1) trends, except for the Pacific region, which shows clear-cut positive trends, consistently with an increasing trend identified in the strength of the Chocó low-level jet winds over the Pacific coast of Colombia, the main moisture advection mechanism into the region. Maximum trend magnitudes in precipitation records on the Amazon basin were found to be decreasing (53%, between 0.04 -9.1 mm yr-1), mostly around the basin's central and south-eastern regions. The highest decreasing trend magnitude in the Amazon was found to be -9.1mm yr-1.

Carmona, A. M.; Poveda, G.

2011-12-01

192

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

193

Use of Precipitation - Runoff Models to Generate Hydrologic Scenarios in a High-altitude Andean Basin of the Ecuadorian Amazon Region. Case study of the Quijos River Basin  

Microsoft Academic Search

Little is known of the hydrology and meteorology of the expansive Andean Amazon region in South America, which extends for approximately 600.000 Km2 and represents around the 10% of the total Amazon region. Climatic processes that occur in the Andean part of the Amazon influence the middle and lower parts of the Amazon Region. Consequently, there is a need to

R. Galarraga; M. McClain; F. Ortega; A. Estacio; A. Febres

2007-01-01

194

Mixing in the Amazon estuary  

NASA Astrophysics Data System (ADS)

The research area of this work is located at the estuary of the Amazon River (Brazil), near the river mouth. The results of air movement analysis on the surface atmospheric circulation over the Mouth of the Amazonas River, salinity and temperature measures as well as measurements of currents, carried out along a longitudinal section in the navigation canal region of the Northern Bar of the Amazon River (Barra Norte do Rio Amazonas) in June 2006, during the river flood season in the quadrature tide. The dynamics effects affect hydrodynamic,meteorological and hydrographical parameters at the river mouth. The conclusion drawn include that: a) the saline wedge-type stratification can be detected approximately 100km away from the mouth of the Amazon River during the end of the rainy season in the quadrature tide; b) probably, at the Amazon estuary the quadrature entrainment processes are dominant and they are the ones responsible for increased salinity detected in the surface layer, whereas turbulence scattering mixing is not so important. c) The large flow of fresh water from the Amazon River at the end of the rainy season implies the displacement of the saline front position over the internal Amazon continental platform, and d) The tidal wave shows a positive asymmetry in the canal, with floods lasting less than in the ebb tide. This asymmetry decreases towards the ocean, eventually becoming reversed in the presence of a saline wedge. The speeds, however, have a negative asymmetry, with more intense ebb tides, due to the river flow and is more evident by the existence of quadrature tides.

Bezerra, M. O.

2010-05-01

195

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

196

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

197

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

198

(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

2011-02-25

199

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

200

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

201

Raft River Geothermal Aquaculture Experiment. Phase II.  

National Technical Information Service (NTIS)

Channel catfish, tilapia and Malaysian prawns were cultured directly in geothermal water for approximately seven months at the Department of Energy, Raft River Geothermal Site, to evaluate the organisms throughout a grow-out cycle. Parameters evaluated in...

D. K. Campbell F. L. Rose J. C. Kent L. R. Watson J. F. Sullivan

1979-01-01

202

Southern oscillation and the northern australian prawn catch  

NASA Astrophysics Data System (ADS)

Associations are established between the southern oscillation index (SOI) and penaeid prawn catches within the northern Australian prawn fishery. Analysis involved calculation of correlations between Gulf of Carpentaria banana prawn andtiger prawn catches and Troup's SOI. Significant positive correlations are observed between catch size and SOI for specific months from pre-wet to post-wet seasons. For banana prawns, the results indirectly confirm some earlier observations of increased catches in conjunction with high rainfall during the onset of monsoon periods, but also indicate an association with late rains. However, the relationship with tiger prawns appears to be in the opposite direction, showing negative correlations with SOI for particular months. Some hypotheses are suggested to explain these results in terms of environmental effects on spawning populations, and comment is made on the potential for forecasting catch sizes.

Catchpole, A.; Auliciems, A.

203

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

204

Physical oceanography of the Amazon shelf  

Microsoft Academic Search

The Amazon shelf is subject to energetic forcing from a number of different sources, including near-resonant semi-diurnal tides, large buoyancy flux from the Amazon River discharge, wind stress from the northeasterly tradewinds and strong along-shelf flow associated with the North Brazil Current. Although the large volume of river discharge produces a pronounced salinity anomaly, the water motions on the shelf

W. Rockwell Geyer; Robert C. Beardsley; Steven J. Lentz; Julio Candela; Richard Limeburner; William E. Johns; Belmiro M. Castro; Ivan Dias Soares

1996-01-01

205

Microsatellite markers for the tambaqui (Colossoma macropomum, Serrasalmidae, Characiformes), an economically important keystone species of the Amazon River floodplain.  

PubMed

Colossoma macropomum is a keystone species of the Amazon floodplain, and is an important but severely overexploited commercial species. To provide tools for addressing ecological and conservation questions, we developed 14 highly polymorphic microsatellite markers that had between four and 21 alleles per locus in the 25 tested individuals. With the exception of comparisons involving the locus Cm1F5 that also showed heterozygosity deficiency, no pairs of loci were at linkage disequilibrium. Many of the microsatellite loci were also variable in three other serrasalmid species which span the phylogenetic depth of the Serrasalmidae. PMID:21564774

Santos, Maria D Conceição F; Hrbek, Tomas; Farias, Izeni P

2009-02-03

206

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

207

Effluent recycle and waste minimization in prawn farm effluent  

Microsoft Academic Search

Prawn farms withdraw huge quantities of sea water and discharge 5–30% of it back to the estuary during water exchange process. The effluent from the prawn ponds contains large quantities of solids, nitrogen, phosphorus and algae and it cannot be discharged into the estuary or ocean without proper effluent treatment. Sedimentation could form a partial treatment system. In this study,

S Vigneswaran; H. H Ngo; K. L Wee

1999-01-01

208

Reuse strategy of wastewater in prawn nursery by microbial remediation  

Microsoft Academic Search

A strategy of reusing the prawn nursery wastewater was developed by the previous remediation with Bacillus subtilis and nutrients addition. The suggested method was preliminarily verified in rearing prawn larval. Bacteria assimilation is proved as a main and powerful mechanism for removing dissolved organic matter (DOM) and total ammonia nitrogen (TAN) in the experiments. The process of microbial remediation could

Fei Liu; Wuying Han

2004-01-01

209

Electrophoretic studies on muscle myogens of some penaeid prawns  

Microsoft Academic Search

The muscle myogen patterns of some penaeid prawns studied by electrophoresis in cellulose acetate membrane are presented. Each pattern was species specific and appears to be independent of sex. The results suggest that muscle myogen patterns could be useful in taxonomic studies of penaeid prawns. Specimens preserved in phenoxyethanol were compared with fresh specimens. Preservation resulted in some losses of

T. K. Lim; S. S. Lee

1970-01-01

210

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

211

A new microsporidian parasite, Potaspora morhaphis n. gen., n. sp. (Microsporidia) infecting the Teleostean fish, Potamorhaphis guianensis from the River Amazon. Morphological, ultrastructural and molecular characterization.  

PubMed

A fish-infecting Microsporidia Potaspora morhaphis n. gen., n. sp. found adherent to the wall of the coelomic cavity of the freshwater fish, Potamorhaphis guianensis, from lower Amazon River is described, based on light microscope and ultrastructural characteristics. This microsporidian forms whitish xenomas distinguished by the numerous filiform and anastomosed microvilli. The xenoma was completely filled by several developmental stages. In all of these stages, the nuclei are monokaryotic and develop in direct contact with host cell cytoplasm. The merogonial plasmodium divides by binary fission and the disporoblastic pyriform spores of sporont origin measure 2.8+/-0.3 x 1.5+/-0.2 microm. In mature spores the polar filament was arranged into 9-10 coils in 2 layers. The polaroplast had 2 distinct regions around the manubrium and an electron-dense globule was observed. The small subunit, intergenic space and partial large subunit rRNA gene were sequenced and maximum parsimony analysis placed the microsporidian described here in the clade that includes the genera Kabatana, Microgemma, Spraguea and Tetramicra. The ultrastructural morphology of the xenoma, and the developmental stages including the spores of this microsporidian parasite, as well as the phylogenetic analysis, suggest the erection of a new genus and species. PMID:18694535

Casal, G; Matos, E; Teles-Grilo, M L; Azevedo, C

2008-08-01

212

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

213

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

2012-01-18

214

Inverse mercury and selenium concentration patterns between herbivorous and piscivorous fish in the Tapajos River, Brazilian Amazon.  

PubMed

We evaluated the levels of selenium and mercury in five fish species commonly eaten by local populations of the Brazilian Amazon. Fish specimens were sampled in two lotic and three lentic areas at two different phases of the hydrological cycle. Analyses of Carbon and Nitrogen stable isotopes allowed us to confirm the trophic levels of the fish species (one herbivorous, two omnivorous and two piscivorous) and verify that these levels remained unchanged with the habitats and the season. The levels of selenium and mercury in fish varied from 50ng/g to 1006ng/g and from 17ng/g to 3502ng/g respectively. For both seasons, fish from lotic ecosystems presented higher selenium concentrations. An inverse pattern was observed between selenium and mercury concentrations within the trophic chain, and this in both seasons. Indeed, the highest mean concentrations of selenium and lowest mean concentrations of mercury were measured in the herbivorous species and the opposite in the piscivorous species. Our results unequivocally demonstrate that local riverside populations will maximize the selenium health benefits of eating fish while minimizing their risk of being chronically exposed to mercury by preferentially consuming herbivorous species and to some extent omnivorous species, while avoiding piscivorous species. PMID:23921221

Sampaio da Silva, D; Lucotte, M; Paquet, S; Brux, G; Lemire, M

2013-08-06

215

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

216

Institutions and sustainable development in Amazon region  

Microsoft Academic Search

This article analyses recent efforts to create a different institutional framework in Pará State, Brazilian Amazon to promote sustainable development. The region is economically peripheral to capitalism. Historically, Amazon river delta has been used as source of raw materials since XVII century, but only from the 1970’s, when roads were built, is been massively occupied by frontier activities like timber,

Ana Paula Bastos; Maurilio Monteiro

2011-01-01

217

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

218

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

2009-04-08

219

Chemical weathering and atmospheric\\/soil CO 2 uptake in the Andean and Foreland Amazon basins  

Microsoft Academic Search

This study is a geochemical investigation of the Andean and Foreland basins of the Amazon River at high spatial and time resolution, carried out within the framework of the HYBAM research program (Hydro-geodynamics of the Amazon Basin). Monthly sampling was carried out at 27 gauging stations located in the upper tributaries of the Amazon Basin (from north to south: the

Jean-Sébastien Moquet; Alain Crave; Jérôme Viers; Patrick Seyler; Elisa Armijos; Luc Bourrel; Eduardo Chavarri; Christelle Lagane; Alain Laraque; Waldo Sven Lavado Casimiro; Rodrigo Pombosa; Luis Noriega; Andrea Vera; Jean-Loup Guyot

2011-01-01

220

Elemental gaseous mercury flux at the water/air interface over the Negro River basin, Amazon, Brazil.  

PubMed

The amount of dissolved gaseous mercury (DGM) released annually into the atmosphere by water bodies in each of the 18 major sub-basins of the Negro River tributaries has been estimated for the wet season and adopted for the entire year. Using Remote Sensors (RS) and the Geographic Information System (GIS), an estimate was made for the total flooded area during the period of the wet season (May-July), which corresponds to around 10% of the total basin area. The estimates of DGM evasive flux values were made during four scientific campaigns and ranged from 0.09 to 14 mug m(-2) y(-1). Mercury wet deposition to the same area was estimated using average values of the metal concentration in the rainwater (9.8 ng L(-1)), which varies from 17 to 27 microg m(-2) year(-1). Considering the flooded area of the Negro River Basin as 69,000 km(2), the total amount of mercury emitted by all bodies of water reaches nearly 0.26 ton year(-1), which represents not more than 2% of the total mercury found in wet deposition in this same area. PMID:16364409

da Silva, Gilmar Silvério; Jardim, Wilson F; Fadini, Pedro Sérgio

2005-12-20

221

Primary cell cultures isolated from Penaeus monodon prawns  

Microsoft Academic Search

We have devised a cell culture system for Penaeus monodon prawn cells that uses a defined synthetic medium. Organs were removed from adult prawns ranging in size from 13--19cm rostrum-to-telson length. Cultures consisted of either a blend of hematopoietic and lymphoid cells or ovarian cells. The cells divide rapidly in culture, doubling on average once per week for 5 to

T. Mahony; F. McCarthy; J. Watanabe; D. Hewitt; S. Hansford

1999-01-01

222

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

223

Trends in the hydrologic cycle of the Amazon basin  

Microsoft Academic Search

Although previous studies have considered the long-term variability of precipitation and river discharge in the Amazon basin, other components of the hydrologic cycle, such as evapotranspiration and the transport of water vapor, have not received the same attention. This study examines the 20-year variability of the full hydrologic budget of the Amazon basin, using a 1976 -1996 time series from

Marcos Heil Costa; Jonathan A. Foley

1999-01-01

224

Frozen Storage Stability of Whole and Headless Freshwater Prawns, 'Macrobrachium rosenbergii'.  

National Technical Information Service (NTIS)

The freshwater prawn, Macrobrachium rosenbergii, is being increasingly cultured in tropical regions and has aquacultural potential in temperate zones. In this study, frozen glazed prawns were stored whole (both raw and precooked) and deheaded (raw) for 9 ...

M. B. Hale M. E. Waters

1981-01-01

225

Joint effects of chromium and phenol on marine prawns ( Penaeus japonicus)  

Microsoft Academic Search

Marine prawns (Penaeus japonicus) were exposed to various combinations of chromium and phenol. The yield of prawns was synergistically inhibited by a 63-day exposure to combinations of chromium and phenol, when compared to controls and single-factor treatments. The accumulation of chromium in prawns was not only dependent on the concentration of chromium in the seawater, but was also related to

Zhou Qixing; Dai Limei

1995-01-01

226

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

227

Routine Metabolic Rate and Limiting Oxygen Concentration of Freshwater Prawn Macrobrachium rosenbergii Larvae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Malaysian prawns, Macrobrachium rosenbergii, are hatched and raised indoors in small tanks. Prawns may be raised and shipped at high densities which could result in low dissolved oxygen (DO) conditions. Because DO may play an important role in prawn development and survival, we measured routine me...

228

Raft River Geothermal Aquaculture Experiment. Phase II  

Microsoft Academic Search

Channel catfish, tilapia and Malaysian prawns were cultured directly in geothermal water for approximately seven months at the Department of Energy, Raft River Geothermal Site, to evaluate the organisms throughout a grow-out cycle. Parameters evaluated included survival, growth, bioaccumulation of metals and fluoride, collagen synthesis, and bone calcium levels. Growth at Raft River was slightly lower than at a companion

D. K. Campbell; F. L. Rose; J. C. Kent; L. R. Watson; J. F. Sullivan

1979-01-01

229

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

230

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

231

Solar aquaculture: A wintering technique for parent prawns  

SciTech Connect

A new method of providing the warm water needed for parent prawn wintering using solar energy is described. Using solar energy for prawn wintering involves heat collection, heat storage and temperature maintenance. The system designed provides sufficient energy for the safe wintering of prawns with suitable water temperatures. The temperature control facilities consist of three parts: a salt gradient solar pond, a shallow solar pond and a plastic house. The technique involves use of a shallow solar pond for collection and storage of heat. The average temperature in the wintering pond plastic house was 11 degrees C and the minimum temperature in January was 5.4 degrees C. This system allowed the wintering process to be conducted using solar energy alone and may extend aquaculture to higher latitudes. The ratio of net profit with the solar energy system over investment is 1.5 which makes it economically viable.

Cao Jin Long [Aquaculture Res. Inst., Shandong Province (China)

1994-09-01

232

Mechanisms of colour adaptation in the prawn Penaeus monodon.  

PubMed

Exposure of prawns to dark- or light-coloured substrates is known to trigger a strong colour adaptation response through expansion or contraction of the colouration structures in the prawn hypodermis. Despite the difference in colour triggered by this adaptive response, total levels of the predominant carotenoid pigment, astaxanthin, are not modified, suggesting that another mechanism is regulating this phenomenon. Astaxanthin binds to a specific protein called crustacyanin (CRCN), and it is the interaction between the quantities of each of these compounds that produces the diverse range of colours seen in crustacean shells. In this study, we investigated the protein changes and genetic regulatory processes that occur in prawn hypodermal tissues during adaptation to black or white substrates. The amount of free astaxanthin was higher in animals adapted to dark substrate compared with those adapted to light substrate, and this difference was matched by a strong elevation of CRCN protein. However, there was no difference in the expression of CRCN genes either across the moult cycle or in response to background substrate colour. These results indicate that exposure to a dark-coloured substrate causes an accumulation of CRCN protein, bound with free astaxanthin, in the prawn hypodermis without modification of CRCN gene expression. On light-coloured substrates, levels of CRCN protein in the hypodermis are reduced, but the carotenoid is retained, undispersed in the hypodermal tissue, in an esterified form. Therefore, the abundance of CRCN protein affects the distribution of pigment in prawn hypodermal tissues, and is a crucial regulator of the colour adaptation response in prawns. PMID:22189778

Wade, Nicholas M; Anderson, Mike; Sellars, Melony J; Tume, Ron K; Preston, Nigel P; Glencross, Brett D

2012-01-15

233

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

234

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

235

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

236

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

237

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.

238

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

239

The status of infectious disease in the Amazon region.  

PubMed

The Amazon River basin region is a vast territory with an area >7 million km2, encompassing parts of 9 South American countries: Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela. The Amazon River, the longest river in the world, traverses the region from west to east, fed by multiple tributaries. The region also contains the largest tropical rainforest in the world, situated on a massive plain whose altitude is near sea level. With a climate characterized by high temperatures and humidity and copious rainfall, the region has the densest and most varied ecosystem in the world. PMID:19331757

Tauil, Pedro Luiz

2009-04-01

240

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

PubMed

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 the end of 15 days exposure. Interestingly, the control prawn showed normal cellular architecture of gills, hepatopancreas and ovary with mature oocytes. But, the gills of treated prawns showed lamellar hypertrophy, cuticular dystrophy and irregular arrangement of epithelial cells. Hepatopancreas showed reduction in both tubular diameter and basement membrane thickness. Conspicuously, ovary showed hypertrophied primary oocytes with more vacuoles in intact-treated group. Cadmium had increased gonad inhibiting hormone (GIH) secretion and decreased gonad stimulating hormone (GSH) release as evident with the retardation of gonadal maturation in the intact prawns. PMID:21296420

Revathi, Peranandam; Vasanthi, Lourduraj Arockia; Munuswamy, Natesan

2011-02-05

241

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

242

Methylmercury in hair samples from different riverine groups, Amazon, Brazil  

Microsoft Academic Search

The present study was aimed to evaluate comparatively the levels of methylmercury (MeHg) in human hair, collected from different groups of Amazonian populations exposed to contamined fish. The study was undertaken in fishing villages and gold mining areas, mainly in the Tapajós and Madeira river basins, two of the main tributaries of Amazon river. The study population included 125 hair

H. A. Kehrig; O. Malm; H. Akagi

1997-01-01

243

An Appalachian Amazon? Magnetofossil evidence for the development of a tropical river-like system in the mid-Atlantic United States during the Paleocene-Eocene Thermal Maximum  

NASA Astrophysics Data System (ADS)

The Paleocene-Eocene Thermal Maximum is preserved within the mid-Atlantic Coastal Plain as a unique clay deposited in the Salisbury Embayment, a tectonic downwarp that stretches from southeastern Virginia to central New Jersey. The mostly massive and kaolinite-rich clay is distinct from the glauconitic sediments that otherwise characterize regional Paleocene and lower Eocene deposits. It contains abundant magnetite produced by magnetotactic bacteria and by larger, presumptively eukaryotic microorganisms not yet known from any other locality. Because most magnetotactic bacteria live within a specific, narrow redox environment -- the suboxic zone of a water column or sediments, where both oxygen and sulfide concentrations are low and iron concentrations relatively high -- their biominerals can be used as a paleoenvironmental tracer. High iron bioavailability indicates a relatively thick suboxic zone. The preservation of iron biominerals suggests that this zone was located in sediments, rather than in the water column, as water column suboxia is associated with high sedimentary organic carbon concentrations, which promote magnetite dissolution. The thickest modern, sedimentary, high-iron suboxic zones occur in tropical river-dominated shelves, such as the Amazon Shelf. These zones result from the combination of a moderately high input of reactive Fe (produced by tropical weathering conditions) with a high-energy environment (produced by tides, frontal-zone currents, and surface waves) that promotes the regular physical reworking of the sediments, thus allowing the re-oxidation of reduced Fe and increasing the availability of Fe as an electron acceptor. To test the "Appalachian Amazon" hypothesis, we mapped the distribution of magnetofossils throughout the Salisbury Embayment using ferromagnetic resonance spectroscopy and electron microscopy, supplemented by organic carbon isotope data. We find three magnetic facies in the clay: Facies 1, characterized by a mix of detrital particles and magnetofossils; Facies 2, with a higher magnetofossil-to-detrital ratio; and Facies 3, with only transient magnetofossils. Facies 1 occurs in inner-middle neritic deposits of central Maryland and northern Virginia, near where the modern Potomac crosses the Fall Line. Facies 2 occurs throughout the middle neritic deposits of eastern Maryland and Virginia and of southern New Jersey. Facies 3 occurs in the outer neritic deposits of eastern New Jersey and on the northern and southern flanks of the embayment. Consistent with the hypothesis, this distribution suggests a link between the magnetofossil distribution and a river system with an outlet in the vicinity of Facies 1. The development of such a river system may have been linked to a combination of more intense weathering, higher precipitation, and increased storminess.

Kopp, R. E.; Schumann, D.; Raub, T. D.; Powars, D. S.; Godfrey, L. V.; Swanson-Hysell, N.; Maloof, A. C.; Vali, H.

2009-12-01

244

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

245

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

246

Seasonal cycle and interannual variability in the Amazon hydrologic cycle  

Microsoft Academic Search

An analysis of the Amazon basin hydrologic cycle has been carried out using the NASA\\/Goddard Earth Observing System (GEOS-1) atmospheric reanalysis, observed rainfall of Xie and Arkin [1996], and historical Amazon River discharge. Over a seasonal cycle the precipitation is found to vary by 5 mmd-1, and the runoff is found to vary by 2 mmd-1, while the evaporation largely

Ning Zeng

1999-01-01

247

The turbidity behavior in an Amazon floodplain  

NASA Astrophysics Data System (ADS)

The main objective of this study is to understand the turbidity behavior of an Amazon Floodplain Lake. Observations of turbidity provide quantitative information about water quality. However, the number of available in situ measurements for water quality determination is usually limited in time and space. Here, we present an analysis of the temporal and spatial variability using two approaches: (i) the first is based on wavelet analysis of a turbidity time series measured by an automatic monitoring system; (ii) the second is based on turbidity samples measured in different locations and then interpolated by an ordinary kriging algorithm. The space/time turbidity variability is clearly related to the Amazon River flood pulses in the floodplain. When the water level in the floodplain is rising or receding, the exchange between the Amazon River and the floodplain is the major driving force in turbidity variability. At high water level, the turbidity variability is controlled by the lake bathymetry. Finally, when the water level is low, the wind action and lake morphometry are the main causes of turbidity variability. The combined use of temporal and spatial data showed a great potential for understanding the turbidity behavior in a complex aquatic system, like the Amazon floodplain.

Alcântara, E.; Novo, E.; Stech, J.; Lorenzzetti, J.; Barbosa, C.; Assireu, A.; Souza, A.

2009-05-01

248

Mining Induced Emissions of Sediment and Mercury in the Tapajós River Basin Pará, Brazilian Amazon, 1985-1998, determined from the Ground and from Space  

Microsoft Academic Search

Dissolved mercury concentrations in waters draining mining operations in the Reserva Garimpeira do Tapajós are elevated when compared to concentrations in pristine rivers and the Tapajós River. However, essentially all dissolved mercury concentrations fall below 0.1 ppb. Mercury bound to suspended sediment is roughly 600 and 200 times the concentration of dissolved mercury per litre of water in impacted areas

Kevin Telmer; Maycira Costa; Rômulo Simões Angélica; Eric S. Araujo; Yvon Maurice

2003-01-01

249

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

250

The Vine Trust's Amazon Hope boats--providing a dental service on the Amazon.  

PubMed

The Vine Trust's Amazon Hope Project is a medical and dental programme providing healthcare to communities along the Amazon River in Peru. Volunteers from the UK and other countries work alongside Peruvian staff employed by their partner organization, Union Biblica del Peru, to provide a health service from a boat which serves communities on several tributaries who otherwise would have no other access to care. The dental programme involves a basic restorative and extraction service, with scope to develop a preventive programme. Clinical Relevance: Dentists'and DCPs' skills are transferable globally: this article illustrates how one volunteer dental project is working to provide relevant and sustainable dental health care in the Amazon jungle. PMID:23505857

Mason, Shona M C

251

Characterization and Pathogenicity Studies on Vibrio Bacteria Isolated from Freshwater Prawn (Macrobrachium rosenbergii) Hatcheries  

Microsoft Academic Search

Phenotypic identification of fifty Vibrio bacterial strains, isolated from diseased and healthy larval prawn as well as larval rearing water in prawn hatcheries, together with twenty-two reference strains were investigated by Euclidean distance with unweighted average linkage clustering. Comparison based on fourty-seven phenotypic characters showed that these isolates mainly clustered in five groups of which four were equated with the

Dang Thi; Hoang Oanh; Tran Thi; Tuyet Hoa; Nguyen Thanh Phuong

252

Studies on the Functional Morphology and Ecology of the Atyid Prawns of Dominica  

Microsoft Academic Search

Six species of atyid prawns, representing five genera, occur in streams on the West Indian island of Dominica (figures 1-0). The ecology and habits of each are described and the relation of features of gross morphology to ways of life noted. Xiphocaris elongata, the most primitive living atyid, is a lightly built prawn whose adult habits are related to life

G. Fryer

1977-01-01

253

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

254

Reducing the short-term mortality of juvenile school prawns (Metapenaeus macleayi) discarded during trawling  

Microsoft Academic Search

A field experiment was carried out in southeastern Australia to assess the short-term mor- tality and stress incurred by juvenile school prawns (Metapenaeus macleayi) discarded from an estuarine trawler. Some 35% of the prawns died up to 72 h after being caught in a trawl, exposed to air during sorting and separation from the retained catch (as per normal commer-

William G. Macbeth; Matt K. Broadhurst; Brian D. Paterson; Michael E. L. Wooden

2006-01-01

255

Selectivity and gear efficiency of trammel nets for kuruma prawn ( Penaeus japonicus)  

Microsoft Academic Search

To study the effect of gear selectivity on kuruma prawn (Penaeus japonicus) fishing experiments using trammel nets with different mesh sizes were conducted in Ohmi Bay, Yamaguchi Prefecture, Japan. To provide comparative data the same nets were used on kuruma prawn of known size composition under controlled conditions in a water tank at the Yamaguchi Prefectural Naikai Fisheries Experimental Station.

Yasuzumi Fujimori; Tadashi Tokai; Setsuhisa Hiyama; Ko Matuda

1996-01-01

256

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

2009-05-20

257

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

258

Rare earth elements in the Amazon basin  

NASA Astrophysics Data System (ADS)

The rare earth element (REE) concentrations of the dissolved and particulate fractions and bed sediment between Manaus and Santarém in the Amazon River, and in some major tributaries, were evaluated. A very important zone in the Amazon basin, the encontro das aguas area where the Rio Solimões and the Rio Negro meet, was especially sampled. Different size fractions were isolated by ultrafiltration. Water samples were collected at different stages of the mixing. Three groups of waters are distinguished: group I has a low pH (<5·5) and is represented by the Negro basin rivers; group II has alkalinity less than 0·2 meq l-1 and is represented by the Rios Tapajós and Trombetas; group III has high alkalinity (>0·2 meq l-1) and higher pH (>6·5) and is represented by the Madeira basin rivers, the Solimões and the Amazon. The highest dissolved REE concentration is in the Rio Negro and the lowest in the Rio Tapajós (dissolved REEs vary by more than a factor of ten). The solubility of REEs is pH dependent: in river waters with a pH < 6 the Ce concentration is twice that of La, whereas in rivers with a higher pH the concentrations of Ce and La are similar. Dissolved REE concentrations are positively correlated with the dissolved organic carbon. Correlations between Fe, Al, and La suggest that La is associated with Al (Fe)-rich organic matter and/or related to dissolved Fe-rich inorganic material. Dissolved REEs normalized to North American shale composite show an enrichment in intermediate/heavy REEs (from Eu to Er), except for the shields rivers (such as Rio Negro and Rio Trombetas). Both of them are depleted in heavy REEs and show a relative Ce enrichment. In contrast, for the Andeans rivers (such as Rio Solimões), light REEs are slightly depleted and a negative Ce relative anomaly occurs. The pattern of the Amazon River at Óbidos confirms the major influence of the Rios Negro and Solimões with REE fractionation. For the Rio Negro, 60 to 70% of REEs are concentrated in the particulate fraction (>0·2 µm), 20 to 30% are in the colloidal fraction (0·2 µm to 5000 Da) and less than 10% are in solution (<5000 Da). For the Solimões the distribution is different. More than 95% of REEs are in the particulate fraction. In the mixing area, the colloidal fraction is enriched in heavy REEs.

Gerard, M.; Seyler, P.; Benedetti, M. F.; Alves, V. P.; Boaventura, G. R.; Sondag, F.

2003-05-01

259

GBR-prawn: modelling ecosystem impacts of changes in fisheries management of the commercial prawn (shrimp) trawl fishery in the far northern Great Barrier Reef  

Microsoft Academic Search

GBR-prawn is a “mass-balance” trophic-based ecosystem model (ECOPATH II) of the Great Barrier Reef, which combines a model template of a generalised coral reef ecosystem with results from extensive cross-shelf surveys of the far northern Great Barrier Reef. The enhanced model includes both the trawl and line fisheries, but focuses on the effect of trawling on the penaeid prawn community

Neil A Gribble

2003-01-01

260

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

261

Monitoring water level in large trans-boundary ungauged basins with altimetry: the example of ENVISAT over the Amazon basin  

Microsoft Academic Search

Brasil and Bolivia have water plans projects on the Beni-Madeira river, a major tributary of the Amazon. There are four main tributaries to the Rio Madeira: the Guapore, the Mamore and the Beni rivers into the Bolivian territory, and the Madre de Dios River crossing the North of Bolivia, coming from Peru. Most parts of these rivers are very far

Frederique Seyler; Stephane Calmant; Joecila da Silva; Naziano Filizola; Emmanuel Roux; Gerard Cochonneau; Philippe Vauchel; Marie-Paule Bonnet

2009-01-01

262

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

2012-08-15

263

Hair Mercury Speciation as a Function of Gender, Age, and Body Mass Index in Inhabitants of the Negro River Basin, Amazon, Brazil  

Microsoft Academic Search

Human mercury contamination can be monitored through hair analysis of mercury's inorganic and organic form as methylmercury\\u000a (Me-Hg). Hair total mercury and Me-Hg were studied in a Negro River fish-eating population in relation to age, gender, and\\u000a body mass index (BMI). This riverbank population eats fish at least twice a day and is exposed to high levels of Me-Hg. Total

A. C. Barbosa; W. Jardim; J. G. Dórea; B. Fosberg; J. Souza

2001-01-01

264

Hair Mercury Speciation as a Function of Gender, Age, and Body Mass Index in Inhabitants of the Negro River Basin, Amazon, Brazil  

Microsoft Academic Search

Human mercury contamination can be monitored through hair analysis of mercury's inorganic and organic form as methylmercury (Me-Hg). Hair total mercury and Me-Hg were studied in a Negro River fish-eating population in relation to age, gender, and body mass index (BMI). This riverbank population eats fish at least twice a day and is exposed to high levels of Me-Hg. Total

A. C. Barbosa; W. Jardim; J. G. Dórea; B. Fosberg; J. Souza

2001-01-01

265

Spatial and temporal distribution in density and biomass of two Pseudodiaptomus species (Copepoda: Calanoida) in the Caeté river estuary (Amazon region--North of Brazil).  

PubMed

Spatial and temporal density and biomass distribution of the planktonic copepods Pseudodiaptomus richardi and P. acutus along a salinity gradient were investigated in the Caeté River Estuary (North-Brazil) in June and December, 1998 (dry season) and in February and May, 1999 (rainy season). Copepod biomass was estimated using regression parameters based on the relation of dry weight and body length (prosome) of adult organisms. The Caeté River Estuary was characterized by high spatial and temporal variations in salinity (0.8-37.2). Exponential length-weight relationships were observed for both Pseudodiaptomus species. Density and biomass values oscillated between 0.28-46.18 ind. m-3 and 0.0022-0.3507 mg DW. m-3 for P. richardi; and between 0.01-17.02 ind. m-3 and 0.0005-0.7181 mg DW. m-3 for P. acutus. The results showed that the contribution of P. richardi for the secondary production in the Caeté River Estuary is more important in the limnetic zone than in other zones where euhaline-polyhaline regimes were predominant. However, it was not possible to observe a clear pattern of spatial and temporal distribution for P. acutus. PMID:16862295

Magalhães, A; Costa, R M; Liang, T H; Pereira, L C C; Ribeiro, M J S

2006-05-01

266

Mercury contamination in the Brazilian Amazon. Environmental and occupational aspects  

Microsoft Academic Search

Mercury (Hg) contamination of miners, riparian and Indian populations and fish in the Amazon region, due to gold extracting activities, has been studied. Samples of hair, urine, and blood of Indians and prospectors, and hair from riparian fish-eating population and fishes from Madeira river, respectively, were collected and analyzed by Cold Vapor, Atomic Absorption Spectrometry (CV-AAS) techniques. The results obtained

A. C. Barbosa; A. A. Boischio; G. A. East; I. Ferrari; A. Gonçalves; P. R. M. Silva; T. M. E. da Cruz

1995-01-01

267

Lead exposure in indigenous communities of the Amazon basin, Peru  

Microsoft Academic Search

Since 2006, three studies have reported elevated levels of lead (Pb) among the indigenous population of the Corrientes river, in the Amazon basin of Peru. Due to the large evidence of environmental pollution related to oil exploitation in the area, this activity has been suggested as the source of exposure. This study aimed to evaluate Pb levels in the population

Cynthia Anticona; Ingvar A. Bergdahl; Thomas Lundh; Yuri Alegre; Miguel San Sebastian

268

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

269

Proliferation of Hydroelectric Dams in the Andean Amazon and Implications for Andes-Amazon Connectivity  

PubMed Central

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.

Finer, Matt; Jenkins, Clinton N.

2012-01-01

270

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

2012-04-28

271

Methylmercury in hair samples from different riverine groups, Amazon, Brazil  

Microsoft Academic Search

The present study was aimed to evaluate comparatively the levels of methylmercury (MeHg) in human hair, collected from different\\u000a groups of Amazonian populations exposed to contamined fish. The study was undertaken in fishing villages and gold mining areas,\\u000a mainly in the Tapajs and Madeira river basins, two of the main tributaries of Amazon river. The study population included\\u000a 125 hair

H. A. Kehrig; O. Malm; H. Akagi

1997-01-01

272

CTD Observations on the North Brazil Shelf during a Multidisciplinary Amazon Shelf SEDiment Study, AMASSEDS, August 1989.  

National Technical Information Service (NTIS)

CTD and acoustic Doppler current profiler (ADCP) observations were made on the North Brazil shelf adjacent to the mouth of the Amazon River during R/V Iselin cruise I8909 August 3-14, 1989 as part of A Multidisciplinary Amazon Shelf SEDiment Study (AMASSE...

R. Limeburner R. C. Beardsley

1989-01-01

273

Oxidation and Reduction Rates for Organic Carbon in the Amazon Mainstream Tributary and Floodplain, Inferred from Distributions of Dissolved Gases.  

National Technical Information Service (NTIS)

Concentrations of CO2, O2, CH4, and N2O in the Amazon River system reflect an oxidation-reduction sequence in combination with physical mixing between the floodplain and the mainstem. Concentrations of CO2 ranged from 150 microM in the Amazon mainstem to ...

J. E. Richey A. H. Devol S. C. Wofsy R. Victoria M. N. G. Riberio

1986-01-01

274

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

275

CTD Observations on the North Brazil Shelf during a Multidisciplinary Amazon Shelf SEDiment Study (AMASSEDS), May-June 1990.  

National Technical Information Service (NTIS)

Hydrographic (CTD) and acoustic Doppler current profiler (ADCP) observations were made on the North Brazil shelf adjacent to the mouth of the Amazon River during R/V Iselin cruise I9004 May 23-June 13, 1990 as part of A Multidisciplinary Amazon Shelf SEDi...

R. Limeburner R. C. Beardsley

1991-01-01

276

CTD Observations on the North Brazil Shelf during a Multidisciplinary Amazon Shelf SEDiment Study (AMASSEDS), February-March 1990.  

National Technical Information Service (NTIS)

Hydrographic (CTD) and acoustic Doppler current profiler (ADCP) observations were made on the North Brazil shelf adjacent to the mouth of the Amazon River during R/V Iselin cruise I9002 February 10-March 29, 1990 as part of A Multidisciplinary Amazon Shel...

R. Limeburner R. C. Beardsley

1991-01-01

277

Development of regional future climate change scenarios in South America using the Eta CPTEC/HadCM3 climate change projections: climatology and regional analyses for the Amazon, São Francisco and the Paraná River basins  

NASA Astrophysics Data System (ADS)

The objective of this study is to assess the climate projections over South America using the Eta-CPTEC regional model driven by four members of an ensemble of the Met Office Hadley Centre Global Coupled climate model HadCM3. The global model ensemble was run over the twenty-first century according to the SRES A1B emissions scenario, but with each member having a different climate sensitivity. The four members selected to drive the Eta-CPTEC model span the sensitivity range in the global model ensemble. The Eta-CPTEC model nested in these lateral boundary conditions was configured with a 40-km grid size and was run over 1961-1990 to represent baseline climate, and 2011-2100 to simulate possible future changes. Results presented here focus on austral summer and winter climate of 2011-2040, 2041-2070 and 2071-2100 periods, for South America and for three major river basins in Brazil. Projections of changes in upper and low-level circulation and the mean sea level pressure (SLP) fields simulate a pattern of weakening of the tropical circulation and strengthening of the subtropical circulation, marked by intensification at the surface of the Chaco Low and the subtropical highs. Strong warming (4-6°C) of continental South America increases the temperature gradient between continental South America and the South Atlantic. This leads to stronger SLP gradients between continent and oceans, and to changes in moisture transport and rainfall. Large rainfall reductions are simulated in Amazonia and Northeast Brazil (reaching up to 40%), and rainfall increases around the northern coast of Peru and Ecuador and in southeastern South America, reaching up to 30% in northern Argentina. All changes are more intense after 2040. The Precipitation-Evaporation (P-E) difference in the A1B downscaled scenario suggest water deficits and river runoff reductions in the eastern Amazon and São Francisco Basin, making these regions susceptible to drier conditions and droughts in the future.

Marengo, Jose A.; Chou, Sin Chan; Kay, Gillian; Alves, Lincoln M.; Pesquero, José F.; Soares, Wagner R.; Santos, Daniel C.; Lyra, André A.; Sueiro, Gustavo; Betts, Richard; Chagas, Diego J.; Gomes, Jorge L.; Bustamante, Josiane F.; Tavares, Priscila

2012-05-01

278

Competition and Habitat Partitioning by the Giant Freshwater Prawn 'Macrobrachium rosenbergii' (De Man) (Decapoda, Palaemonidae).  

National Technical Information Service (NTIS)

Under certain predictable conditions Macrobrachium rosenbergii kill one another. Under other 'field' conditions these prawns appear to segregate by molt state into different microhabitats. Experiments were conducted to determine if this segregation was th...

J. B. Peebles

1980-01-01

279

Prevalence of Microbial Load in Shrimp, Penaeus monodon and Prawn, Macrobrachium rosenbergii from Bangladesh  

Microsoft Academic Search

A comparative studies regarding prevalence of microbial flora in the muscle of locally available tiger shrimp (Penaeus monodon) and giant water prawn (Macrobrachium rosenbergii) have been analyzed in terms of aerobic plate count (APC), enterobacteriaceae and Salmonella-Shigella (SS) counts. The total counts ranged from 2.04x10 to 4.5x10 CFU\\/ml for shrimp and 1.08x10 to 1.2x10 CFU\\/ml for prawn. The total coliforms

Abu Hena Muhammad Yousuf; Sabina Yeasmin

280

CULTURE OF GIANT FRESHWATER PRAWN,Macrobrachium rosenbergii de Man, WITH AERATION BY USING PADDLE WHEEL  

Microsoft Academic Search

Experiment on rearing of giant freshwater prawn, Macrobrachium rosenbergii, with and without aeration were conducted in 1 rai earthen ponds at Kanchanadit Suratthani Thailand during July to December 2002. The paddle wheel aerator was used in the aeration treatment. Giant freshwater prawn, an initial size of 1.38 + 0.20 cm in length and 0.023 + 0.007 g in weight, were

Noppadol Jindaphan; Anchalee Tantikul

281

Modification and Modificatory Kinetics of the Active Center of Prawn ?-N-Acetyl-D-glucosaminidase  

Microsoft Academic Search

?-N-acetyl-D-glucosaminidase (NAGase, EC3.2.1.52) plays important role in molting, digestion of chitinous foods, and defense systems against parasites in prawn (Litopenaeus vannamei). However, study on functional groups and catalytic mechanism of NAGase are yet limited. The modification of the active center of NAGase from prawn has been first studied. The results demonstrate that the disulfide bonds and the carbamidine groups of

Xiao-Lan Xie; Qian-Sheng Huang; Ye Wang; Cai-Huan Ke; Qing-Xi Chen

2009-01-01

282

Distribution and partition of trace metals in the Amazon basin  

NASA Astrophysics Data System (ADS)

The distribution of trace metals (V, Cr, Mn, Co, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Cs, Ba, U) was investigated in surface waters and associated particulates in the Amazon mainstream (Solimões and Amazon rivers). Dissolved V, Cu, As, Sr, Ba, U correlate with major ions and appear to be predominantly derived from soluble rocks occurring in the Amazon upper basin. These elements appear conservative in waters and are progressively diluted by less-concentrated waters coming from the lowland and shield areas. A monthly time series obtained at the Óbidos gauging station shows that temporal variability of trace element concentrations reflects the source, remobilization and/or biological processes occurring in the channel or in the surrounding floodplain lakes. The trace element concentrations in the particulate matter show a clear relationship with the location of the samples. V, Co, Cr, Mn, Sr, Cs and Ba concentrations are higher in the Solimões and the Rio Negro is enriched in Fe, Al and Zn. In the Rio Solimões, V, Cr, Mn, Co, Ni, Zn, Cs and Pb are almost entirely carried by the river particulate matter; Cu, Rb, Sr, Ba and U are transported mainly by the suspended particles, but a dissolved phase contributes to the transport. In the Rio Negro, the proportion of elements transported by the dissolved phase is higher for the whole set of elements. The implications of these results allow us to compute the fluxes from the Amazon River to the Atlantic Ocean.

Seyler, Patrick T.; Boaventura, Geraldo R.

2003-05-01

283

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

284

Applications of GNSS data for hydrological studies in the Amazon basin.  

NASA Astrophysics Data System (ADS)

Applications of GNSS data is constantly being used in hydrology. The key applications are the levelling of hydrological gauge stations and characterization of river's longitudinal profiles, these information are required to develop hydrological and hydrodynamic studies and to evaluate the quality of data obtained through space altimetry techniques. Some factors illustrate the challenge of establishing quality altimetry data from a GNSS receivers to obtain rivers profiles in Amazon Basin. GNSS reference network is sparse, the distance between survey points and reference stations is large, rivers have an extension of several thousands of kilometers. All these factors contribute in limiting the efficiency of classical techniques of GNSS data processing like double difference. In addition the Amazon Basin are strongly affected by charge effects, mainly caused by the hydrological cycle of this basin. These effects can produce a variation of about 10 cm in amplitude of vertical coordinates In the present work we use the Gins-PC software developed at CNES / GRGS. We discuss the capability of kinematic processing strategy implemented in GINS-PC in use GNSS data to calculate river's longitudinal profiles in the Amazon Basin. The profiles will be processed using data obtained from GPS receivers on boarding boats along the rivers of Amazon Basin such as Negro river, Madeira river and Amazon/Solimões river. For this purpose, field campaigns were conducted between 2005 and 2011 by ANA ( Brazilian National Water Agency), CPRM (Brazilian Geologic Survey), IRD (French Institute of Research by Development), Hybam ( Hydrology of Amazon Basin), PROSUL (Research project by CNPQ/UFRJ) and FOAM (From Ocean to inland waters Altimetry Monitoring) river section project. The profiles are also used to levelling some gauge stations in Amazon Basin and gauge data are used to obtain a temporal variation of these profiles. GPS data are processed using a Double-Difference and a PPP strategy. The comparison of the series derived from the two approaches demonstrate the strength of PPP wherever reference stations can not be easily installed. The seasonal hydrological loading signal of these profiles will be removed by data derived from the series of permanent GNSS stations installed in the Amazon. GRACE data also be used to convert the hydrologic load into crustal displacements to remove hydrological loading effects. The results of the Amazon rivers profiles will be then compared with profiles obtained by water level variation data using altimetry data from tracks of the Jason-2 and ENVISAT missions.

Moreira, D.; Perosanz, F.; Calmant, S.; Santos, A.; Silva, J.; Ramillien, G.; Rotunno, O.; Seyler, F.; Monteiro, A.; Shum, C. K.

2012-04-01

285

In-Depth Tanscriptomic Analysis on Giant Freshwater Prawns  

PubMed Central

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.

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

286

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

287

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 Âstealth 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

288

Comparison of Late Quaternary Climate Development Between the Niger Catchment Area and the Amazon Basin  

Microsoft Academic Search

The inorganic terrigenous fraction of marine sediments offers a great number of different and well established proxy parameters to investigate the development of continental climate. In this study we present high resolution records of terrigenous source elements from the Niger River and the Amazon River fans. Sediment cores are well dated by radiocarbon measurements. Elemental records from both regions reveal

M. Zabel; V. Ettwein; M. Maslin; R. R. Schneider

2003-01-01

289

Infrared spectroscopy and X ray diffraction study on the morphological variations of carbonate and phosphate compounds in giant prawn ( Macrobrachium rosenbergii ) skeletons during its moulting period  

Microsoft Academic Search

A systematic study has been carried out on the quantitative and morphological variations of carbonate and phosphate compounds in giant prawn (Macrobrachium rosenbergii) skeletons during the moulting period on the basis of infrared spectroscopy and X ray diffraction (XRD) analyses. Skeletons samples were prepared from adult giant prawns, extracted from the intact skeletons of the prawns at the ages of

D. S. Soejoko; M. O. Tjia

2003-01-01

290

Incidence of haemolysin-positive and drug-resistant Aeromonas hydrophila in freshly caught finfish and prawn collected from major commercial fishes of coastal South India  

Microsoft Academic Search

The incidence of Aeromonas hydrophila in freshly caught finfish and prawns from four major commercial fish landing sites of coastal South India was studied for a period of one year. Among 514 analysed samples of seafood (410 finfish and 104 prawn), 37% of them (37.3% of finfish and 35.6% of prawn) were contaminated with A. hydrophila. A total of 255

Tha Thayumanavan; G Vivekanandhan; K Savithamani; R Subashkumar; P Lakshmanaperumalsamy

2003-01-01

291

Biogeochemical processes in Amazon shelf waters: chemical distributions and uptake rates of silicon, carbon and nitrogen  

Microsoft Academic Search

Biogeochemical processes in the Amazon River\\/ocean mixing zone were examined during four AmasSeds cruises between August 1989 and November 1991. On the Amazon shelf, the distributions of chlorophyll-a, oxygen supersaturation, pH and the biogenic-silica content of suspended matter all showed coherent patterns highlighting areas of high primary productivity. Phytoplankton blooms occurred seaward of the high-turbidity waters (suspended-solid concentration >10 mg

D. J. DeMaster; W. O. Smith; D. M. Nelson; J. Y. Aller

1996-01-01

292

75 FR 16436 - Certain Frozen Warmwater Shrimp From India: Initiation of Antidumping Duty Changed Circumstances...  

Federal Register 2010, 2011, 2012, 2013

...Penaeus vannemei), banana prawn (Penaeus merguiensis), fleshy prawn (Penaeus chinensis), giant river prawn (Macrobrachium rosenbergii), giant tiger prawn (Penaeus monodon), redspotted shrimp (Penaeus brasiliensis), southern...

2010-04-01

293

77 FR 40574 - Certain Frozen Warmwater Shrimp From Thailand: Final Results of Antidumping Duty Administrative...  

Federal Register 2010, 2011, 2012, 2013

...Penaeus vannemei), banana prawn (Penaeus merguiensis), fleshy prawn (Penaeus chinensis), giant river prawn (Macrobrachium rosenbergii), giant tiger prawn (Penaeus monodon), redspotted shrimp (Penaeus brasiliensis), southern...

2012-07-10

294

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

295

OBSERVATIONS ON THE ARTISANAL PRAWN FISHERY IN THE, SHALLOW COASTAL WATERS OFF CHILAW DURING 1994-1995  

Microsoft Academic Search

A study was conducted to assess the impact of the imposition of the ban on the prawn trawl fishery in Chilaw areaon the artisanal prawn fishery in the sllallow coastal waters off Cldaw from Januaiy 1994 to December 1995. Fishing operations were mainly cal-ried out hy the traditional log rafts. In addition a few FRP boats were also engagedin exploitation

P. A. A. T. JAYAWARDANE; D. S. JAYAKODY

296

Occurrence of dolphins and seabirds and their consumption of by-catch during prawn trawling in Spencer Gulf, South Australia  

Microsoft Academic Search

In the Spencer Gulf prawn fishery prawns are caught at night by trawling. Groups of dolphins, the short-beaked common dolphin (Delphinus delphis) and the bottlenose dolphin (Tursiops truncatus), and seabirds, the silver gull and the pacific gull (Larus novaehollandiae, Larus pacificus), feed on discarded by-catch. The dolphins follow the cod ends as they appear close to or on the surface.

Ib Svane

2005-01-01

297

Quantifying the effects of bycatch reduction devices in Queensland's (Australia) shallow water eastern king prawn ( Penaeus plebejus) trawl fishery  

Microsoft Academic Search

This study presents results from an experimental 10-day research charter that was designed to quantify the effects of (a) a turtle excluder device (TED), (b) a radial escape section bycatch reduction device (BRD) and (c) both devices together, on bycatch and prawn catch rates in the Queensland shallow water eastern king prawn (Penaeus plebejus) trawl fishery. The bycatch was comprised

A. J. Courtney; M. L. Tonks; M. J. Campbell; D. P. Roy; S. W. Gaddes; P. M. Kyne; M. F. O’Neill

2006-01-01

298

GYRKPPFNGSIFamide (Gly-SIFamide) modulates aggression in the freshwater prawn Macrobrachium rosenbergii.  

PubMed

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

Vázquez-Acevedo, Nietzell; Rivera, Nilsa M; Torres-González, Alejandra M; Rullan-Matheu, Yarely; Ruíz-Rodríguez, Eduardo A; Sosa, María A

2009-12-01

299

Rivers  

NSDL National Science Digital Library

This site features pages to more than twenty NASA radar images of the world's major river systems. The image pages contain a brief description of the respective processes and setting, and are available for download. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing.

Pavlovsky, Rich

300

Fires in the Amazon  

NSDL National Science Digital Library

This week's In The News covers the issues around the massive fires burning in the Brazilian Amazon. The nine sites listed provide information and commentary on the global issue. Since July 1997, the media has paid attention to the Brazilian Amazon, as fires there increased and raged out of control. Thought to have been started by slash-and-burn agriculturists, these fires were influenced by El Nino weather patterns and spread in size and intensity until reaching devastating heights in late March, 1998. Although a fortuitous three-day rain extinguished most fires, experts warn that the threat of future fires remains high. While Brazil has received much attention in recent months, such fires are not limited to South America; Indonesia and other tropical countries face similar disturbances to their ecological and economic environments.

Payne, Laura X.

1998-01-01

301

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.

302

Group sizes and compositions of monkeys in the upper Amazon basin  

Microsoft Academic Search

Eleven species of New World monkeys inhabit the basin of the upper Amazon. Twice, for a total 16 months, the author studied\\u000a the group sizes and compositions of these species in the basin of the Rivers Caquet and Putumayo, particularly in the two\\u000a study areas established in the basin of the River Peneya, a tributary of the River Caquet.\\u000a \\u000a Data

Kosei Izawa

1976-01-01

303

Foods and feeding behavior of monkeys in the upper Amazon basin  

Microsoft Academic Search

Eleven species of the New World monkeys inhabit the basin of the River Caquet in the upper Amazon. Twice for a total of 16\\u000a months the author studied the foods and feeding behaviors of 10 species of monkeys in the basin of the River Caquet, particularly\\u000a in the two study areas established in the basin of the River Peneya, a

Kosei Izawa

1975-01-01

304

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

305

Identification and cloning of a selenium dependent glutathione peroxidase from giant freshwater prawn, Macrobrachium rosenbergii.  

PubMed

A selenium dependent glutathione peroxidase (Se-GPx) cDNA was cloned from haemocyte by a reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA (RACE). The 913 bp cDNA contained an open reading frame (ORF) of 558 bp encoded a deduced amino acid sequence of 186 amino acids. The prawn Se-GPx sequence contains a selenocysteine (Sec) residue which is encoded by the unusual stop codon, (115)TGA(117). According to the molecular modeling analysis, the active site Sec residue, located in the loop between beta3 and alpha2 in a pocket on the protein surface, and hydrogen bonded to Gln(73) and Trp(141). A GPx signature motif 2, (63)LAFPCNQF(70) and active site motif, (151)WNFEKF(156), two arginine (R) residues, R(89) and R(167) contribute to the electrostatic architecture that directs the glutathione donor substrate, and two putative N-glycosylation site, (75)NNT(77) and (107)NGS(109) were observed in the prawn Se-GPx sequence. In addition, the eukaryotic selenocysteine insertion sequence element is conserved in the 3'-UTR. Comparison of amino acid sequences showed that prawn Se-GPx is more closely related to vertebrate GPx 1. The prawn Se-GPx was synthesized in haemocyte, hepatopancreas, muscle, stomach, gill, intestine, eyestalk, heart, epidermis, lymph organ, ventral nerve cord, testis and ovary. The increase of respiratory burst in haemocyte was observed in pathogen, Debaryomyces hansenii-injected prawn in order to kill the pathogen, and the up-regulation in SOD and GPx acitivity, and prawn Se-GPx mRNA transcription were involved with the protection against damage from oxidation. PMID:19376233

Yeh, Shinn-Pyng; Liu, Kuan-Fu; Chiu, Shieh-Tsung; Jian, Shun-Ji; Cheng, Winton; Liu, Chun-Hung

2009-04-17

306

Sub-lethal impact of carbaryl on food utilization in the freshwater prawn Macrobrachium malcolmsonii.  

PubMed

This study determines the toxic effect of carbaryl (Sevin50% W.P) on the food utilization parameters in intermoult juveniles of the prawn, Macrobrachium malcolmsonii. The prawns (4.5-5.0 cm in length and 1.0-1.25 g wet wt.) were exposed to three sub-lethal concentrations of carbaryl (5.15, 7.73 and 15.47 microgl-1) for duration of 40 days. The toxic medium was renewed daily. The prawns were fed ad libitum with known energy quantity of boiled goat liver on daily basis. The overall wet weight gain was calculated. The energy lost through unconsumed food (15-60%), faeces (15-109%), ammonia excretion (9-27%) and moults (13-26%) of the prawns were calculated. The feeding rate, the rate and efficiency of absorption, the metabolic and food conversion rates and the gross and net food conversions efficiencies were found to be significantly declined (p<0.05) in test prawns when compared to that of the control. The energy lost through faeces, ammonia excretion and exuvia was found to be significantly elevated (p<0.05) in test prawns than that of the control. The effectof carbaryl on the bioenergetics parameters was severe in the highest sub-lethal concentration, less in the intermediate concentration and least in the lowest sub-lethal concentration. The results indicated that decrease in feeding, absorption, metabolism and food conversion are interdependent and toxicity of carbaryl diverting energy from production to maintenance pathways, which ultimately resulting in declined growth of M. malcolmsonii. PMID:22167951

Bhavan, P Saravana; Geraldine, P; Sowdeswari, R

2011-05-01

307

Glutathione S-transferase and metallothionein levels in the freshwater prawn Macrobrachium malcolmsonhi exposed to mercury.  

PubMed

Healthy juveniles of M. malcolmsoniiwere exposed to 24.1 microg l(-1) of mercury (96 hr LC50: 145 microg l(-1) Hg) for a period of 21 days. The hepatopancreas and gills of the prawns were sampled on 8th, 15th and 22nd day of exposure. Accumulation and elimination of Hg, activity of glutathione S-transferase (GST), content of glutathione (GSH) and metallothionein (MT) level were studied. Mercury accumulation was found to be higher in the hepatopancreas (88.60 microg g(-1)) and lower in the gills (67.8 microg g(-1)). However, Hg elimination was found to be faster in the gills (62%) and slower in the hepatopancreas (58%). Therefore, the rate of Hg elimination did not match the rate of its uptake. The activity of GST was found to be higher in tissues of test prawns (5.94-9.13 nmol mg(-1) protein min(-1)) on all sampling days when compared with controls (3.454.23 nmol mg(-1) protein min(-1)). Similarly, the content of GSH was found to be higher in tissues of test prawns (0.80-1.43 micromol g(-1) protein) on all sampling days when compared with controls (0.55-1.00 micromol g(-1) protein). These results indicate the formation of glutathione conjugate in test prawns to eliminate Hg. The induction of MT level was also found to be higher in tissues of test prawns (57.50-75.76 nmol g(-1) protein) on all sampling days when compared with control (20.24-45.22 nmol g(-1) protein). This indicates the fact that sequestration of Hg has occurred for its easy elimination. Thus, induction of GST-GSH and MT ensured protection and adaptation of test prawns to thrive in Hg contaminated environment. PMID:23033656

Yamuna, A; Bhavan, P Saravana; Geraldine, P

2012-01-01

308

Ontogenic study of isozymes in giant tiger prawn, Penaeus monodon (Crustacea: Decapoda)  

NASA Astrophysics Data System (ADS)

The patterns of isozyme variation throughout the life cycle of the giant tiger prawn, Penaeus monodon were described for ten enzyme systems (G3PD, MDH, LGG, GPI, MPI, FBP, PGM, LDH, PGD, and PROT). The zymograms showed little variation in the number of isozymic loci expressed during larval development compared with results reported for other penaeid prawns. There were specific ontogenic patterns at some loci. As larvae developed beyond the embryonic stage, there was a tendency for intensity of staining and complexity of banding patterns to increase.

Tong, Jin-Gou; Ballment, E.; Benzie, J. A. H.

1996-12-01

309

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

310

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

311

Telemedicine in extreme conditions: supporting the Martin Strel Amazon Swim Expedition.  

PubMed

Slovenian Martin Strel, the Guinness world record holder in ultra marathon swimming, recently set a new world record by swimming the entire Amazon River. Over a 66-day period beginning in Atalaya, Peru, he swam to the Atlantic Ocean at Belém, Brazil. This record-breaking swim was part of the Amazon Swim Expedition. This entire mission was supported by a comprehensive medical team, the Amazon Virtual Medical Team (AVMT), which provided medical support using telemedicine. The AVMT, a multinational volunteer group of specialists, physicians, and telemedicine experts, provided medical support 24/7 in some of the most remote, dangerous, basin. The AVMT was directed basin. The AVMT was directed by Dr. Rifat Latifi and expedition team physician, Dr. Mateja de Leonni Stanonik, who was aboard the boat during the entire expedition. The expedition provided a unique opportunity to promote telemedicine and e-health in over 17 communities in the Amazon basin. PMID:19199853

Latifi, Rifat; Stanonik, Mateja de Leonni; Merrell, Ronald C; Weinstein, Ronald S

2009-01-01

312

Methods of isolating the androgenic sex hormone from crustacean prawn and marine shrimp and methods of use  

US Patent & Trademark Office Database

This work constitutes a novel approach and methodology, e.g., the in vitro secretion method to isolate the androgenic polypeptide hormone (AH) from the androgenic gland of shrimp or prawns. Alternatively, the AH can be obtained recombinantly by cloning and expressing the AH gene. The AH polypeptide is used to produce phenotypic males, neomales, from genotypic female shrimp or prawns. The neomales find use in the production of sex-skewed and monosex offspring when mated with wild-type female shrimp or prawns. From the sequence of the purified AH polypeptide, oligonucleotide probes are synthesized to clone the AH encoding nucleic acid which is used for recombinant AH polypeptide expression.

Malecha; Spencer R. (Honolulu, HI); Sun; Piera S. (Honolulu, HI)

2004-05-25

313

Current Characterization at the Amazon estuary  

NASA Astrophysics Data System (ADS)

At the estuary there are several mechanisms that cause turbulence: influence of solid contours (estuary bottom and shores), speed vertical shearing (fluid inside), wind shearing stress (free surface) and surface and internal gravity waves. Turbulence intensity controls vertical distribution of estuary water mass property concentration. As flow into the estuary takes place during the transition or turbulent regimen, produced by small space and time scale movements, entrainment, turbulent scattering and advection are the processes responsible for fresh water mixing up with the sea and for local salinity variation, as well as for concentration of natural properties and man-made ones. According to this focus, we shall describe general circulation, conveyance and mixing characteristics of the Amazon low estuary waters. Amazon estuary shows unusual characteristics: it is of vast length and enormous outflow. It is extremely wide - 150 Km - and its discharge into the Atlantic amounts to 180,000 m3s-1 (Otman, 1968, Figueiredo et al, 1991), which means 18% of all water discharged by rivers into oceans; this is the largest punctual source of fresh water for oceans (Milliman and Meade, 1983). Maximum outflow is 2.5 x 105 m3s-1, and it happens at the end of May. Minimum outflow is 1.2 x 105 m3 s-1, and it takes place in November. At Amazon River, the Mixing Zone occurs where the Coastal Zone usually is. The reason for that is the extension of fresh water plume moves Northeast for over 1000 Km (Gibbs, 1970; Muller-Karger et al 1988). This is the most extensive estuarine plume ever found in the ocean. During low fluvial discharge (June-November) plume reaches 300 Km; however, on high discharge (November-May) plume reaches 500 Km. Plume already is 3 to 10 m thick and 80 to 300 Km wide (Lentz and Limeburner, 1995). From June to January plume moves towards Africa, from whence 70% of it goes east carried by North Brazil Current retroflection and 30% goes towards the Caribbean. From February to May, the plume goes northwest towards the Caribbean. As to classification according to salinity stratification, at the quadrature the Amazon estuary is considered as "Saline Wedge" type (highly stratified estuary), salinity at 120 Km way from river moth standing out, whereas at sysygy it can be classified as well mixed (Limeburner et al. 1991e 1992; Patchineelam, 2004). Fresh water is everywhere in the river area, salty or mixed water is located in the ocean. In this estuary 90 Km away from the mouth surface water salinity is less than 0.05 and bottom salinity at 14 m deep is about 19 at high water on quadrature at the end of the rainy season. This behavior produces marked difference in the vertical salinity profile, showing the current is moving in the opposite direction (river fresh water and salty water brought by the tide). In this scenario, speed shearing at the interface produces interfacial friction stress that, from the entrainment process carries portions of water from the sea to the upper part. Usually, therefore, in "saline wedge" (highly stratified estuary) type estuaries, when river discharge is more intensive than the tide wave, entrainment is the predominant mechanism; and the greater tide amplitude is, the greater will its influence be to produce turbulent scattering and mixing be. Probably, at Amazon estuary quadrature entrainment processes are predominant and are the ones responsible for increased salinity in surface layer, whereas turbulence scattering mixing is secondary to it. "Saline wedge" (highly stratified estuary) type estuaries are typical of large fluvial discharge and microtide regions. But although the Amazon estuary is a macrotide region, this stratification is due to the river's exceptional discharge. Due to the remarkable river plume discharge on the platform, the tide - a dominant in macrotide region estuarine circulation - now has a secondary role, albeit not a negligible one, with quadrature amplitudes varying from 2 m to 90 Km from the mouth. It is important to point out that tide-ind

Bezerra, M. O.

2009-04-01

314

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

315

Reexamining the late Cenozoic geologic evolution of the Amazon basin  

NASA Astrophysics Data System (ADS)

The recent geologic evolution of the Amazon basin has been the focus of many recent studies. Our own research and our review of the literature suggest a need for reevaluation of many aspects of this history including several key questions: What was the timing of Andean uplift (especially, the Western Cordillera)? What is the relationship between the northernmost Solimões Formation and northern Andean tectonic activity? What is the precise age of the lowermost levels of the Solimões Formation? Were there marine incursions? Are tidal deposits recorded in Amazonia? Was there a very large, long-lived, Miocene "Pebas" megalake in the western Amazon? When did the trans-continental, eastern outlet, Amazon drainage become established? What is the antiquity of the Amazon fan? Correct answers to these questions are essential in order to gain a better understanding of the climatic and biogeographic history of the Amazon basin. Although several authors have suggested the existence of late Miocene tidal sediments deposited during a sea-level high stand and marine transgressions into the Amazon basin from the north (Caribbean Sea) or from the south (Paranáense Sea), both the existence of a late Miocene seaway through western Amazonia and the existence of thousands of square kilometers affected by tides are difficult to support. The faunal composition and pollen content of the upper Miocene Solimões Formation are inconsistent with tidal/marine environments. And, as we have demonstrated, deposits in Peruvian Amazonia that have been attributed to Miocene tidal environments are actually fluvial sediments that have been environmentally and chronologically misinterpreted. Further, the existence of a giant paleolake in western Amazonia during the middle to late Miocene is inconsistent with our paleoenvironmental reconstructions of shifting rivers in aggradational conditions - reconstructions that are consistent with the interpretations of the Solimões Formation in other parts of the basin and with sedimentary architecture at both basin scale and depositional-system scale. We have previously suggested that ca. 5 Ma, during the period when low-angle subduction was fully developed in the Nazca Plate between ~3° and 15°S, reorganization of drainage resulted in the transformation of the southwestern Brazilian Amazon from a basin that trapped sediments to an erosional region that contributed sediments to the Amazon fluvial system. It is likely that at that time the lowland fluvial systems of southwestern Amazonia began to drain to the Atlantic Ocean. A ca. 5 Ma reorganization of the Amazon fluvial system and its connection with the Atlantic Ocean is consistent with the record of terrigenous deposits in the Ceara Rise, close to the Amazon cone. Our analysis of new cores and seismic data from the Amazon fan, as well as a combined morphostratigraphic and biostratigraphic analysis of the western Amazonian lowlands, will provide additional clues to the relationship between tectonics, sea level, and the evolution of the trans-continental Amazon drainage.

Rigsby, C. A.; Latrubesse, E. M.; Baker, P. A.; Silva, C. G.

2010-12-01

316

Constancy in the vegetation of the Amazon Basin during the late Pleistocene: Evidence from the organic matter composition of Amazon deep sea fan sediments  

NASA Astrophysics Data System (ADS)

Analyses of more than 60 sediment samples from the Amazon deep sea fan show remarkably constant terrigenous biomarkers (lignin phenols and cutin acids) and stable carbon isotopic compositions of organic matter (?13COM) deposited from 10 to 70 ka. Sediments from the nine Amazon deep sea fan channel-levee systems investigated in this study yielded relatively narrow ranges for diagnostic parameters such as organic carbon (OC) normalized total lignin yields (? = 3.1 ± 1.1 mg/100 mg OC), syringyl:vanillyl phenol ratios (S/V = 0.84 ± 0.06), cinnamyl:vanillyl phenol ratios (C/V = 0.08 ± 0.02), isomeric abundances of cutin-derived dihydroxyhexadecanoic acid (f10,16-OH = 0.65 ± 0.02), and ?13COM (-27.6% ± 0.6 ‰). Our measurements support the hypothesis that the vegetation of the Amazon Basin did not change significantly during the late Pleistocene, even during the Last Glacial Maximum. Moreover, the compositions obtained from the Amazon deep sea fan are similar to those of modern Amazon River suspended sediments. Such results strongly indicate that the current tropical rainforest vegetation has been a permanent and dominant feature of the Amazon River watershed over the past 70 k.y. Specifically, we found no evidence for the development of large savannas that had been previously postulated as indicators of increased glacial aridity in Amazonia. Climate models need to be modified to account for the uninterrupted input of moisture to the tropical Amazon region over the late Pleistocene Holocene period.

Kastner, Thomas P.; Goñi, Miguel A.

2003-04-01

317

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

318

Allosteric cotransport of sodium, chloride, and calcium by the intestine of freshwater prawns  

Microsoft Academic Search

Summary The apical membrane of the intestinal epithelium of the freshwater prawn,Macrobrachium rosenbergii, has been found to possess an apparently unique allosteric carrier mechanism for the simultaneous cotransport of sodium, chloride, and calcium from mucosal solution to cytosol. Influxes of the two monovalent ions individually were sigmoidal functions of their respective luminal concentrations, and their kinetics followed the Hill equation

Gregory A. Ahearn

1978-01-01

319

Incidental capture, direct mortality and delayed mortality of sea turtles in Australia's Northern Prawn Fishery  

Microsoft Academic Search

The species composition, catch and mortality rates of sea turtles captured incidentally by the tiger prawn fishery on Australia's northern coast in 1989 and 1990 were estimated by monitoring the fishery's catch. In 1990, the delayed rate of mortality from damage was estimated and the size composition was measured. Five species of turtles were captured: the flatback (Natator depressa, 59%

I. R. Poiner; A. N. M. Harris

1996-01-01

320

Manual for the Determination of Egg Fertility in Penaeus monodon (a wild prawn)  

NSDL National Science Digital Library

The Australian Institute of Marine Science (AIMS) has posted online this manual for determining egg fertility in the prawn Penaeus monodon. The manual contains dozens of clear, color images and concise summaries giving identification tips and techniques. Specific in its application, this resource nevertheless provides helpful background images to aid in data interpretation.

321

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

322

Follow-up of mercury levels in fish, human hair and urine in the Madeira and Tapajós basins, Amazon, Brazil  

Microsoft Academic Search

Informal economy of gold mining has contaminated some important river basins in Amazon. Follow-up studies on critical compartments showed some areas with high Hg levels in fish as well as in human hair samples. Average Hg in piscivorous fish in the Madeira river itself was 846 ppb (N=284) with a maximum of 3921 ppb. Mercury in fish from non polluted

O Malm; JRD Guimarães; MB Castro; WR Bastos; JP Viana; FJP Branches; EG Silveira; WC Pfeiffer

1997-01-01

323

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 using process based models for this region. In this direction, the knowledge of the source of errors in hydrological forecast systems may guide the choice on improving model structure, model forcings or developing data assimilation systems for estimation of initial model states. We evaluate the relative importance of hydrologic initial conditions and model meteorological forcings errors (precipitation) as sources of stream flow forecast uncertainty in the Amazon River basin. We used a hindcast approach that compares 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. The model was forced using TRMM 3B42 precipitation estimates. Results show that uncertainty on initial conditions plays an important role for discharge predictability, even for large lead times (∼1 to 3 months) on main Amazonian Rivers. Initial conditions of surface waters state variables are the major source of hydrological forecast uncertainty, mainly in rivers with low slope and large floodplains. Initial conditions of groundwater state variables are important, mostly during low flow period and in the 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 data assimilation methods is encouraged for this region.

Paiva, R. C. D.; Collischonn, W.; Bonnet, M. P.; de Gonçalves, L. G. G.

2012-09-01

324

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

325

Effect of Pseudomonas aeruginosa on the giant freshwater prawn, Macrobrachium rosenbergii--histopathological and electron microscopic study.  

PubMed

The giant freshwater prawn Macrobrachium rosenbergii was injected with an inoculum containing LD, 96 hr dose of 10' Pseudomonas aeruginosa (MTCC 1688) to determine the histopathological effects in vivo. The comparison of tissues of both the control and the bacterial endotoxin treated prawns after 96 hr revealed significant degenerative changes in treated prawns. Both light microscopic and electron microscopic observations revealed the infiltration of the tissues of Pseudomonas sp in the muscular and hepatopancreatic tissues of prawn. The muscular tissue changes in the myofibrillar arrangement with blockage at the gap junctions and necrotic lesions were observed. The hepatopancreatic cells were vacuolated with hypertrophied nucleus. Atrophy of hepatopancreatic tubules was conspicuous. The pathogenicity of Pseudomonas aeruginosa is attributed to its infiltration and multiplication inside the tissues and the consequent release of extra-cellular enzymes for its metabolism. The degeneration of host tissues is also attributed to the latter. PMID:18380087

Ramalingam, K; Ramarani, S

2007-07-01

326

Atmospheric mercury concentrations in the basin of the amazon, Brazil.  

PubMed

A wide regional mercury pollution in Amazon, Brazil is closely associated with goldmining that has been carried out in the basin of tributaries of the Amazon since the eighteenth century. Possible involvement has been discussed on atmospheric circulation in distributing the volatile pollutant. We developed a portable air sampler for the collection of mercury compounds and determined atmospheric mercury concentrations at several sites in Brazil including the basin of the Amazon tributaries. The mean concentration of total mercury was between 9.1 and 14.0 ng/m(3) in the basin of the Uatumã River located in the tropical rain forest far from goldmining sites and from urbanized area. These mercury levels exceeded the background level previously reported in rural area and, furthermore, were higher than concentrations observed in Rio de Janeiro and in Manaus that were compatible with the reference values for urban area. Mercury concentrations were also determined in gold refineries in the basin of the Tapajos River, and detected at a significant but not a health deteriorating level. Although only preliminary data were available, the present observations were in favor of the hypothesis that mercury is distributed widely by long distant transport by the atmospheric circulation after released at gold mining sites. PMID:21432539

Hachiya, N; Takizawa, Y; Hisamatsu, S; Abe, T; Abe, Y; Motohashi, Y

1998-01-01

327

Violence against Amazon women.  

PubMed

This quantitative and exploratory study analyzed violence against Amazon women presented in print media according to type and severity, and whether aggressors fell under the Maria da Penha law. A total of 181 issues of a regional newspaper were consulted. Based on content analysis, 164 items addressing violence against women were selected and 46 were included in the corpus of analysis. Results were gathered in three thematic groups: women killed with cruelty, sexual violence against women regardless of age, and violence against women and the limitations of the Maria da Penha law. Violence against these women varied in terms of form and severity, including up to homicide. Women are submitted to sexual violence from childhood through adulthood. The enforcement of this law shows the community it has a means to cope with this social phenomenon. PMID:20126938

Lima, Vera Lúcia de Azevedo; Souza, Maria de Lourdes de; Monticelli, Marisa; Oliveira, Marília de Fátima Vieira de; Souza, Carlos Benedito Marinho de; Costa, Carlos Alberto Leal da; Brüggemann, Odaléa Maria

328

Isolation and characterization of a female-specific DNA marker in the giant freshwater prawn Macrobrachium rosenbergii  

PubMed Central

In this study, a female-specific DNA marker in the freshwater prawn Macrobrachium rosenbergii was identified through amplified fragment length polymorphism (AFLP). The AFLP-derived sequence-characterized amplified region (SCAR) marker was tested in over 200 individuals, giving reproducible sex identification. Further molecular characterization of the sex-marker's genomic region (?3?kb long) revealed the presence of tandem and inverted repeats. The ?3-kb sequence was identified both in male and female prawns, but with subtle differences: a deletion of 3?bp (present in female prawn but absent in male prawn) identified upstream of the SCAR marker sequence and two female-specific single-nucleotide polymorphisms, both indicating that male prawns are homozygous, whereas female prawns are heterozygous in this locus. Fluorescent in situ hybridization showed the ?3-kb sequence to be unique: to the best of our knowledge, this is the first report of a unique sex-specific sequence observed in situ in crustaceans. The sex-specific marker identified in M. rosenbergii may have considerable applied merit for crustacean culture in that it will enable the determination of genetic sex at early developmental stages when phenotypic differences are not identifiable.

Ventura, T; Aflalo, E D; Weil, S; Kashkush, K; Sagi, A

2011-01-01

329

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

330

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

331

Tidal and Current Prediction for the Amazon's North Channel Using a Hydrodynamical-Numerical Model.  

National Technical Information Service (NTIS)

The hydrodynamical-numerical prediction model developed by W. Hansen is applied to the North Channel of the Amazon River for computation of tides and currents; the results are compared with tidal prediction obtained by the harmonic method and to actual cu...

L. A. Carvalho Ferraz

1975-01-01

332

Bilingual Education and Language Use among the Shipibo of the Peruvian Amazon.  

ERIC Educational Resources Information Center

|Investigates how language choice for education contributes to changes in the way a society views and uses language in the context of the Peruvian Amazon. Oral surveys were administered to Shipibo people in 13 communities along the Ucayali River of eastern Peru where a transition type bilingual education program was introduced several decades ago.…

Tacelosky, Kathleen

2001-01-01

333

Trophic Structure and Bioaccumulation of Mercury in Fish of Three Natural Lakes of the Brazilian Amazon  

Microsoft Academic Search

The bioaccumulation of mercury by fish was studied in three natural lakes lining the Tapajós River, Brazilian Amazon. The Hg content variations are also reported between the rainy and the rising water seasons. Position of fish in the food chain and the source of carbon at the base of the food chain were determined using nitrogen and carbon stable isotopes

D. Sampaio Da Silva; M. Lucotte; M. Roulet; H. Poirier; D. Mergler; E. Oliveira Santos; M. Crossa

2005-01-01

334

CTD Observations on the North Brazil Shelf During A Multidisciplinary AMazon Shelf SEDiment Study (AMASSEDS).  

National Technical Information Service (NTIS)

Hydrographic (CTD) and acoustic Doppler current profiler (ADCP) observations were made on the North Brazil shelf adjacent to the mouth of the Amazon River. These observations were obtained during a large-scale survey on Leg 3 in support of geological and ...

R. Limeburner I. D. Soares J. Candela R. C. Beardsley

1992-01-01

335

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

336

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

337

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

338

Feasibility of using hydrothermal resources in Malaysian prawn aquaculture. Final report  

SciTech Connect

The potential application of geothermal resources in South Carolina for freshwater prawn aquaculture was examined. In coastal S.C. 23 existing geothermal well sites were identified which encompassed an area which ranged from Georgetown to Beaufort. Depth averaged approx. 615 m while temperature averaged approx. 37/sup 0/C. Artesian flow rates varied from 190 to 2650 1/min. Detailed water quality analyses were conducted at 12 sites. In general, major differences from surface waters were in chlorides, fluorides, dissolved solids, ph, alkalinity, and ammonia levels. A detailed replicated laboratory study was conducted to examine the effect of geothermal water on growth and survival of prawns. After 42 days very poor survival was recorded from the various 100% geothermal water treatments. However, 50:50 mixture of shallow well water and geothermal water resulted in a survival rate of 83%, which was similar to the control treatments. Growth was also similar to that observed among the control animals.

Smith, T.I.J.; Rhodes, R.J.; Wannamaker, A.W.

1982-08-01

339

Isolation and characterization of polymorphic microsatellite loci in the ridgetail white prawn Exopalaemon carinicauda.  

PubMed

The ridgetail white prawn Exopalaemon carinicauda is one of the major economic shrimp species cultured in China. In this study, 30 microsatellite loci were isolated and characterized for the ridgetail white prawn E. carinicauda using a microsatellite-enriched library. Polymorphisms were tested in 30 individuals from a single wild population. The number of alleles at each locus ranged from 2 to 14. The observed and expected heterozygosities varied from 0.1000 to 0.8000 and from 0.2299 to 0.9228, respectively. The PIC value ranged from 0.2002 to 0.8939. These new loci will be useful in the study of population genetic structure and genetic diversity in this species. PMID:24065637

Jia, S W; Liu, P; Li, J; Li, J T; Pan, L Q

2013-08-08

340

A study on pathogens of Chinese prawn ( Penaeus Chinensis) virus diseases  

NASA Astrophysics Data System (ADS)

This pathogenic study shows that the viral diseases of Chinese prawns ( Penaeus chinensis, O'sbeck) is due to three kinds of viruses: epithelium envelope baculovirus of Penaeus chinensis (EEBV-PC, detected by the authors in 1993), infections hypodermal and hematopoietic necrosis virus, and hepatopancreatic parvo-like virus, and that the first two viruses seem to be the main pathogens of the epidemic in the northern regions in 1993.

Sun, Xiu-Qin; Zhang, Jin-Xing

1995-09-01

341

Population dynamic of green tiger prawn, Penaeus semisulcatus (De Haan) in Bushehr coastal waters, Persian Gulf  

Microsoft Academic Search

Monthly carapace length frequency data of green tiger prawn, Penaeus semisulcatus were collected from the coastal waters of Bushehr, Persian Gulf, from January 2002 to March 2003. ELEFAN in the software package FiSAT was used to analyse of their length frequency data. The L? and K for males were estimated at 38mm CL and 1.6 year?1, respectively and for the

Nassir Niamaimandi; Aziz Bin Arshad; Siti Khalijah Daud; Ross Cheroos Saed; Bahram Kiabi

2007-01-01

342

Selection of marine yeasts for the generation of single cell protein from prawn-shell waste  

Microsoft Academic Search

Marine yeasts (33 strains) were isolated from the coastal and offshore waters off Cochin. The isolates were identified and then characterized for the utilization of starch, gelatin, lipid, cellulose, urea, pectin, lignin, chitin and prawn-shell waste. Most of the isolates were Candida species. Based on the biochemical characterization, four potential strains were selected and their optimum pH and NaCl concentration

R. Rhishipal; Rosamma Philip

1998-01-01

343

Dietary vitaminE modulates antioxidant defence system in giant freshwater prawn, Macrobrachium rosenbergii  

Microsoft Academic Search

The objectives of the present study were to determine the effect of supplementary vitamin-E (200, 400 and 600 mg\\/kg feed) on lipid peroxidation (LPX) and antioxidant defence system in gills and hepatopancreas of the freshwater prawn, Macrobrachium rosenbergii. Results indicated that vitamin-E inhibited LPX in the hepatopancreas in a comparatively lower dose than gills. Superoxide dismutase (SOD) activity was decreased

Jagneshwar Dandapat; Gagan B. N. Chainy; K. Janardhana Rao

2000-01-01

344

Trophic Value of the Unicellular Diatom Phaeodactylum tricornutum for Larvae of Kuruma Prawn, Penaeus japonicus  

Microsoft Academic Search

The trophic value of the unicellular and silica-less diatom, Phaeodactylum tricornutum for the larvae of kuruma prawn, Penaeus japonicus, was evaluated in uni-algal culture, nutritive analyses and larval rearing in this experiment. The algal strain of Ph. tricornutum used in this experiment had been selected by more than 100 repeat colony screenings using an agar medium under 30°and light conditions

Masanori Okauchi; Masaharu Tokuda

345

Inhibitory kinetics of bromacetic acid on ?- N-acetyl- d-glucosaminidase from prawn ( Penaeus vannamei)  

Microsoft Academic Search

?-N-Acetyl-d-glucosaminidase (NAGase, EC.3.2.1.52), a composition of chitinases, cooperates with endo-chitinase and exo-chitinase to disintegrate chitin into N-acetylglucosamine (NAG). NAGase from prawn (Penaeus vannamei) is involved in digestion and molting processes. The investigation of enzymatic properties, functional groups and catalytic mechanism is an essential mission to its commercial application. Bromacetic acid (BrAc) is a specific modifier for the histidine residue in

Xiao-Lan Xie; Juan Du; Qiang-Sheng Huang; Yan Shi; Qing-Xi Chen

2007-01-01

346

The effect of poly ?-hydroxybutyrate on larviculture of the giant freshwater prawn Macrobrachium rosenbergii  

Microsoft Academic Search

In this study, we investigated the effect of poly ?-hydroxybutyrate (PHB) on the culture performance of larvae of the giant freshwater prawn Macrobrachium rosenbergii and on the bacterial levels inside the larval gut. Instar II Artemia nauplii were cultured with or without PHB (5gl?1) and\\/or a lipid emulsion rich in highly unsaturated fatty acids (HUFA) for 24h. The effect of

Dinh The Nhan; Mathieu Wille; Peter De Schryver; Tom Defoirdt; Peter Bossier; Patrick Sorgeloos

2010-01-01

347

Miocene ostracod (Crustacea) biostratigraphy of the upper Amazon Basin and evolution of the genus Cyprideis  

NASA Astrophysics Data System (ADS)

The Ostracoda in this study come from an area in the Western Amazon river region shared by Peru, Colombia, and Brazil. Fauna was recovered from 125 samples collected at 26 outcrop localities of the Pebas Formation. Five ostracod zones are proposed and referred mainly to the Middle Miocene. The zonation is based on the stratigraphical distribution of 21 endemic species of the euryhaline genus Cyprideis, probably the largest brackish-water ostracod evolutionary radiation of the American Neogene. This study illustrates that Ostracoda can constitute a useful biostratigraphical tool in such environments as those obtained in the Neogene of the upper Amazon Basin.

Muñoz-Torres, F. A.; Whatley, R. C.; Harten, D. Van

2006-03-01

348

Potential groundwater contribution to Amazon evapotranspiration  

NASA Astrophysics Data System (ADS)

Climate and land ecosystem models simulate a dry-season vegetation stress in the Amazon forest, but observations do not support these results, indicating adequate water supply. Proposed mechanisms include larger soil water store and deeper roots in nature and the ability of roots to move water up and down (hydraulic redistribution), both absent in the models. Here we provide a first-order assessment of the potential importance of the upward soil water flux from the groundwater driven by capillarity. We present a map of equilibrium water table depth from available observations and a groundwater model simulation constrained by these observations. We then present a map of maximum capillary flux these water table depths, combined with the fine-textured soils in the Amazon, can potentially support. The maps show that the water table beneath the Amazon can be shallow in lowlands and river valleys (<5 m in 36% and <10 m in 60% of Amazonia). These water table depths can potentially accommodate a maximum capillary flux of 2.1 mm day-1 to the land surface averaged over Amazonia, but varies from 0.6 to 3.7 mm day-1 across nine study sites. We note that the results presented here are based on limited observations and simple equilibrium model calculations, and as such, have important limitations and must be interpreted accordingly. The potential capillary fluxes are not indicative of their contribution to the actual evapotranspiration, and they are only an assessment of the possible rate at which this flux can occur, to illustrate the power of soil capillary force acting on a shallow water table in fine textured soils. They may over-estimate the actual flux where the surface soils remain moist. Their contribution to the actual evapotranspiration can only be assessed through fully coupled model simulation of the dynamic feedbacks between soil water and groundwater with sub-daily climate forcing. The equilibrium water table obtained here serves as the initial state for the dynamic simulation, and together with the equilibrium potential capillary flux, will serve as a baseline to evaluate the diurnal, event, seasonal and inter-annual dynamics.

Fan, Y.; Miguez-Macho, G.

2010-10-01

349

Volume localized shift selective ¹³C spectroscopy using pulsed rotating frame transfer sequences with windows (PRAWN).  

PubMed

Some novel techniques for volume localized, chemical shift selective (13) C spectroscopy are described in this work. These techniques are based on rotating frame J cross polarization and are reported for both direct and indirect modes of (13) C detection. The performance of two selective mixing sequences, viz., pulsed rotating frame transfer sequences with windows (PRAWN) and PRAWN-? has been studied systematically with different liquid and gel phantoms. Two different front-end modules are used for volume localization, viz., point resolved spectroscopy (PRESS) and localized distortionless enhancement by polarization transfer (LODEPT). It is shown experimentally that both the selective J cross polarization sequences can operate efficiently with very low radiofrequency duty cycle; further, they have considerable tolerance to Hartmann-Hahn mismatch. A simple theoretical analysis is also presented to understand J cross-polarization dynamics at low RF field amplitudes. Finally, the performance of LODEPT-PRAWN-? is demonstrated for the selective detection of saturated fat in pigeon egg in indirect detection mode. PMID:21469189

Banerjee, Abhishek; Chandrakumar, N

2011-04-05

350

A vasa-like gene in the giant freshwater prawn, Macrobrachium rosenbergii.  

PubMed

A molecular marker for germ cells of the giant freshwater prawn, Macrobrachium rosenbergii, was studied. A vasa-like gene, Mrvlg, from the ovary was isolated and characterized by a reverse transcriptase-polymerase chain reaction (RT-PCR) method. A full-length sequence was obtained by the rapid amplification of cDNA end (RACE) method. Analysis of the nucleotide sequence revealed that Mrvlg comprises 2,686 bps with an open reading frame of 2,130 bps encoding 710 amino acids. The deduced amino acid sequence contains four arginine-glycine-glycine motifs and eight conserved motifs belonging to the DEAD-box protein family. The MrVLG sequence shows high similarity to Vasa homologue of zebrafish (73%). In the adult tissues, the Mrvlg transcripts were specifically detected in the germ cells. In situ hybridization analysis showed that Mrvlg RNA was detected in the cytoplasm of oogonia, previtellogenic, and vitellogenic oocytes and was also detected in the nucleoplasm of mature oocytes. In the testis, the Mrvlg transcript was detected in the cytoplasm of spermatogonia and primary spermatocytes but was detected in the nuclei of secondary spermatocytes and sperm. Sequence similarity and specific localization in the germ cells suggest that Mrvlg is the prawn vasa homologue of the Drosophila gene and can be used as a molecular marker for prawn germ cells. PMID:17186538

Nakkrasae, La-Iad; Damrongphol, Praneet

2007-07-01

351

hydrochemistry of the Andeans and sub-andeans Amazon basins - Weathering and CO2 consumption rates.  

NASA Astrophysics Data System (ADS)

Measuring mountain weathering rates, estimating their role on C cycle and identifying the parameters which control them are key to better constrain the knowledge of the continental-ocean-atmosphere interactions over geological timescale. The Andes, in contrast to the Himalaya, have received poor attention in terms of chemical weathering. Several authors have worked on the Amazon river basin, but it is difficult to assess the role of the Andes (10% of the surface area of the Amazon river basin) by only sampling the Amazon at mouth or sampling its largest tributaries. As shown by earlier works, the Upper-Amazon basins are the main matter source of the Amazon basin. The studied area participates at more than 70% of the Amazon weathering rates while it contributes to the total discharge on 30% for 27% of the total area. The studied area is comprised between latitude 0°47'N and 20°28'S and between longitude 79°36'W and 58°45'W and can be divided in three major hydrosystems (the Napo river at North, the Maranon-Ucayali rivers on the central part and the upper Madeira at south) which can be separated on Andes and sub-Andes parts. This work presents the results of the HYBAM research program (present-day hydro-geodynamics of the Amazon Basin) on the upper Amazon basin. The concentration of major elements was analyzed on a monthly basis, sampling at 26 gauging stations which include the Andean basins of the Amazon River and a part of the downstream catchment domain. The objectives of this work are i) calculate the major elements fluxes and their spatial distribution, ii) estimate the present-day rate of rock weathering, as well as the flux of atmospheric/soil CO2 consumption from total rock and silicate weathering, and iii) constrain the major environmental factor which controls the dissolved matter production using unique high temporal and spatial resolution data sampling. The main difficulty of studying large river geochemistry is to separate the main sources of the dissolved matter. Studying the temporal dynamic exportation of each element and their main associations helps to better constrain the main matter origin per sub basins and to identify the main processes of production. Variability of runoff rates and lithology between the 3 hydrosystems mainly explain the intersystem weathering rates variability. o The convergence of high runoff rates and main volcanic lithology on Napo basin implies a high weathering rate compared to other basins of the studied area and the main world basins. o Due to the high presence of evaporites and carbonates rocks, the Maranon and Ucayali hydrosystems controls more than 60% of the Amazon hydrochemistry. o Sandstone lithology and low runoff rates on Upper Madeira basins imply a poor contribution of this basin on Amazon dissolved load. Sub-andean plains basins can take place a major role on weathering balance. On the carbonates basins of Maranon Ucayali the subandes catchments contributes to more than 40% to the dissolved load of the hydrosystem. It can reflect the importance of the weathering of sediments exported from Andes or/and the importance of the upper plain weathering rate. The role of environmental parameters, which control those processes, can be partly constrained over the studied area and are compared to other world results. Those results give new keys to better understand the role of major orogenese zones on global weathering processes and its effect on C cycle.

Moquet, Jean-Sébastien; Crave, Alain; Viers, Jérome; Guyot, Jean-Loup; Lagane, Christelle; Sven Lavado Casimiro, Waldo; Pombosa, Rodrigo; Noriega, Luis; Chavary, Eduardo

2010-05-01

352

Gas-charged sediments in the Amazon submarine delta  

NASA Astrophysics Data System (ADS)

Seismic profiling with 3.5-kHz and GeoPulse in the Amazon submarine delta indicates that gas-charged sediments cover an area greater than 31,000 km2. Gas appears on seismic profiles as gas-brightening reflectors near the river mouth, where mud and sand are well stratified. In fine sediments of the distal portion of the system, gas turbidity zones predominate. Biogenic gas is generated during degradation of terrestrial and marine organic matter by bacteria. The depth of gas in sediment below the seabed depends in part on anaerobic methane oxidation and the base of the sulfate reduction zone and on stratigraphic traps.

Figueiredo, Alberto G.; Nittrouer, Charles A.; de Alencar Costa, Elen

1996-03-01

353

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

354

Effect of background colour on the distribution of astaxanthin in black tiger prawn ( Penaeus monodon): Effective method for improvement of cooked colour  

Microsoft Academic Search

The colouration of prawns is dependent upon the presence of carotenoid pigments (predominantly astaxanthin) and has a significant impact on their market value. In this study we observed that visual appearance of colour in black tiger prawns (Penaeus monodon), when assessed using a subjective commercial grading scale, did not always correlate well with total carotenoid content. We also observed that

R. K. Tume; A. L. Sikes; S. Tabrett; D. M. Smith

2009-01-01

355

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

356

SRTM C and X Band Measurements of Water Elevations in Ohio and the Amazon  

NASA Astrophysics Data System (ADS)

Hydrologists, water resource managers, and engineers recognize the potential of remote sensing for acquiring hydraulic measurements necessary for estimating discharge and storage changes globally, and thus have formed a community proposing the Water Elevation Recovery satellite mission (WatER). The WatER technological heritage is directly based on the highly successful Shuttle Radar Topography Mission (SRTM) and its C-band and X-band digital elevation models (DEMs). SRTM is not only a technological heritage for WatER but also a baseline measurement by which we can assess the potential of remote sensing to collect measurements of h, dh/dx and dh/dt. Water surface elevations are abundant in both the C-band and X-band SRTM DEMs. Elevations from three Ohio reservoirs and several Amazon floodplain lakes have standard deviations, interpreted as errors, that are smaller in C-band compared to X-band and are smaller in Ohio than in the Amazon. These trends are also evident when comparing water surface elevations from the Muskingum River in Ohio with those of the Amazon River. Differences are attributed to increased averaging in C-band compared to X-band, greater sensitivity to surface water motion in X-band, and generally larger off-nadir look angles in X-band. Absolute water surface elevations are greater in the C-band DEM for much of the two study areas and yield expected slope values on the Amazon River. However, X-band DEM values for the Amazon River are below sea level downstream of Sao Jose do Amatari (~600 km upstream of Obidos) and have some slope values that are greater than expected. These absolute height and slope differences are attributed to the usage of differing vertical datums.

Kiel, B.; Alsdorf, D.; Lefavour, G.

2005-12-01

357

Effects of ?-irradiation and cooking on vitamins B6 and B12 in grass prawns (Penaeus monodon)  

NASA Astrophysics Data System (ADS)

The effects of irradiation doses, irradiation temperature and a combined treatment of irradiation and cooking on the vitamin B6 and B12 contents of grass prawns have been studied. Grass prawns were irradiated at refrigerated (4°C) or frozen (-20°C) temperatures with different doses. A domestic cooking procedure was followed after irradiation. The changes in vitamins B6 and B12 of both raw and cooked grass prawns were evaluated. Results showed no significant changes of vitamin B6 and B12 in grass prawns with a radiation dose up to 7 kGy at either 4°C or -20°C. Irradiation at 4°C caused more destruction of vitamin B12 but not vitamin B6 than did irradiation at -20°C in grass prawns. There was significant destruction of both vitamins B6 and B12 in unirradiated samples during cooking. The introduction of the irradiation process before cooking had no effect on either vitamin. These results indicate that the loss of vitamins B6 and B12 in the combined treatments was caused mainly by thermal destruction.

Hau, L.-B.; Liew, M.-S.

1993-07-01

358

Act No. 24994 of 19 January 1989. Basic Law on the Rural Development of the Peruvian Amazon Region.  

PubMed

This Act sets forth the government's policy on rural development of the Peruvian Amazon region. Major objectives of the Act include the promotion of new rural settlements in the Amazon region, the promotion of migration from the Andes to the Amazon region, and the stimulation of agriculture, livestock, and forestry activities in the Amazon region. The following are the means that the government will use, among others, to attain these goals: 1) the development of Population Displacement Programmes, which will give individual persons and families economic and logistic support in moving; 2) the establishment of Civic Colonizing Services, temporary mobile units, which will offer settlers health services, education services, technical assistance with respect to agriculture and livestock, and promotional credits; 3) the creation of the Council for Amazon River Transport to coordinate and recommend activities to improve river transport; 4) the granting to settlers of land, free education for their children, medical care, technical training and assistance with respect to agriculture, and a supply of seeds; 5) the exemption of certain investors from payment of income taxes; and 6) the granting of a wide range of incentives for agricultural production. The Act also creates a Council for Planning and Development in the Amazon Region to draw up and approve a Plan for the Development of the Amazon Region. It calls for the rational use of the natural resources of the Amazon Region in the framework of preserving the ecosystem and preventing its ruin and delegates to the regional governments the authority to enter into contracts on the use of forest materials and to undertake reforestation programs. Finally, the Act provides various guarantees for the native population, including guarantees with respect to land and preservation of ethnic and social identity. PMID:12344257

1989-01-01

359

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

1985-01-01

360

Finding Food in the Amazon  

NSDL National Science Digital Library

In this activity, the students will investigate a variety of plants and animals common to the Amazon through research. They will determine the plant or animal characteristics that make them edible or useful for the trip and learn to categorize them by comparing similarities and/or differences.

Adventure Engineering

361

Hydroclimate Scenarios of Amazon Deforestation  

NASA Astrophysics Data System (ADS)

The regional and global implications of the replacement of natural forest by degraded vegetation in the Amazon on the regional and global hydroclimate have yet to be fully understood and quantified. In this study, regional and global climate models are used in conjunction with scenarios of land-cover change resulting from socio-economic and ecological analyses for the coming decades, to estimate potential hydroclimate changes in and outside of the Amazon basin. Four ensembles of six realizations, twelve years each, are produced with the NASA-GISS GCM II: (1) a "control" ensemble that simulates the land cover in the Amazon basin before massive deforestation started; (2) a "current land cover" ensemble; (3) a "scenario for 2030" ensemble; and (4) a "scenario for 2050" ensemble. In addition, The Regional Atmospheric Modeling System (RAMS) is used at a high resolution (20 km grid size) over the Amazon Basin and using the same four land-cover scenarios but with the NCEP reanalysis for three different years (wet, dry, and typical) forcing its lateral boundaries. The combination of these different simulations reveals significant impact of deforestation on the regional and global hydroclimate.

Avissar, R.; Ramos da Silva, R.; Werth, D.

2004-12-01

362

Intensification of the Amazon hydrological cycle over the last two decades  

NASA Astrophysics Data System (ADS)

The Amazon basin hosts half the planet's remaining moist tropical forests, but they may be threatened in a warming world. Nevertheless, climate model predictions vary from rapid drying to modest wetting. Here we report that the catchment of the world's largest river is experiencing a substantial wetting trend since approximately 1990. This intensification of the hydrological cycle is concentrated overwhelmingly in the wet season driving progressively greater differences in Amazon peak and minimum flows. The onset of the trend coincides with the onset of an upward trend in tropical Atlantic sea surface temperatures (SST). This positive longer-term correlation contrasts with the short-term, negative response of basin-wide precipitation to positive anomalies in tropical North Atlantic SST, which are driven by temporary shifts in the intertropical convergence zone position. We propose that the Amazon precipitation changes since 1990 are instead related to increasing atmospheric water vapor import from the warming tropical Atlantic.

Gloor, M.; Brienen, R. J. W.; Galbraith, D.; Feldpausch, T. R.; SchöNgart, J.; Guyot, J.-L.; Espinoza, J. C.; Lloyd, J.; Phillips, O. L.

2013-05-01

363

Diagnosing water variations within the Amazon basin using satellite data  

NASA Astrophysics Data System (ADS)

The components of the Amazon water budget and their spatiotemporal variability are diagnosed using monthly averaged remote sensing-based data products for the period September 2002-December 2006. The large Amazon basin is divided into 14 smaller watersheds, and for each of these sub-basins, fresh water discharge is estimated from the water balance equation using satellite data products. The purpose of this study is to learn how to apply satellite data with global coverage over the large tropical regions; therefore several combinations of remote sensing estimates including total water storage changes, precipitation and evapotranspiration. The results are compared to gauge-based measurements and the best spatiotemporal agreement between estimated and observed runoff is within 1 mm/d for the combination of precipitation from the GPCP and the Montana evapotranspiration product. Mean annual precipitation, evapotranspiration and runoff for the whole basin are estimated to be 6.3, 2.27 and 3.02 mm/d respectively but also show large spatial and temporal variations at sub-basin scale. Using the most consistent data combination, the seasonal dynamics of the water budget within the Amazon system are examined. Agreement between satellite based and in situ runoff is improved when lag-times between sub-basins are included (RMSE from 0.98 to 0.61 mm/d). We estimate these lag times based on satellite-inferred inundation extents. The results reveal not only variations of the basin forcing but also the complex response of the inter-connected sub-basin (SB) water budgets. Inter-annual and inter-SB variation of the water components are investigated and show large anomalies in northwestern and eastern downstream SBs; aggregate behavior of the whole Amazon is more complex than can be represented by a simple integral of the forcing over the whole river system.

Azarderakhsh, Marzieh; Rossow, William B.; Papa, Fabrice; Norouzi, Hamidreza; Khanbilvardi, Reza

2011-12-01

364

Extreme climatic events in the Amazon basin. Climatological and hydrological context of recent floods  

NASA Astrophysics Data System (ADS)

During 2009 the Amazon basin was hit by a heavy flooding with a magnitude and duration few times observed in several decades. Torrential rain in northern and eastern Amazonia during the austral summer of 2008-2009 swelled the Amazon River and its tributaries. By July 2009, water levels of the Rio Negro, a major Amazon tributary, reached at Manaus harbor a new record, the highest mark of the last 107 years. During the 2008-2009 hydrological year, the rainy season on northern and northwestern Amazonia started prematurely, and was followed by a longer-than-normal rainy season. An anomalously southward migration of the ITCZ during May-June 2009, due to the warmer than normal surface waters in the tropical South Atlantic, was responsible for abundant rainfall in large regions of eastern Amazonia and Northeast Brazil from May to July 2009. We also compared the flood of 2009 with other major events recorded in 1989 and 1999. The hydrological consequences of this pattern were earlier than normal floods in Amazon northern tributaries, which peak discharges at their confluences with the main stem almost coincided with the peaks of southern tributaries. Since the time displacement of the contribution to the main stem of northern and southern Amazon tributaries is fundamental for damping flood waves in the main stem, the simultaneous combinations of peak discharges of tributaries resulted in an extreme flood.

Marengo, Jose Antonio; Tomasella, Javier; Soares, Wagner R.; Alves, Lincoln M.; Nobre, Carlos A.

2012-01-01

365

Population dynamics of Niger River prawn (Macrobrachium felicinum) in Lower Taylor Creek, Niger Delta, Nigeria  

Microsoft Academic Search

The population dynamics of Macrobrachium felicinum (Holthuis, 1949) in Lower Taylor Creek, Niger Delta, Nigeria, was analysed using monthly length-frequency data (June 2008 – May 2010). This study was aimed at determining the status of fishery and establishing the levels of exploitation that will give sustainable yields. The FAO-ICLARM stock assessment tool (FISAT II) software was used to estimate population

T onbarapagha Kingdom; Aduabobo Ibitoruh Hart

2012-01-01

366

AmazonViz: visualizing Amazon.com purchase orders  

Microsoft Academic Search

This article describes a technique to visualize query results, representing purchase orders placed on Amazon.com, along a traditional 2-D scatter plot and a space-filling spiral. We integrate 3-D objects that vary their spatial placement, color, and texture properties into a visualization algorithm. This algorithm represents important aspects of a purchase order based on experimental results from human vision, computer graphics,

Amit Prakash Sawant; Christopher G. Healey; Dongfeng Chen; Rada Chirkova

2009-01-01

367

Metallothionein-Like Proteins and Energy Reserve Levels after Ni and Pb Exposure in the Pacific White Prawn Penaeus vannamei  

PubMed Central

This study analyzed the changes in metallothionein-like proteins (MTLPs) and Energy Reserves (ERs) in hepatopancreas and abdominal muscle of the white prawn Penaeus vannamei. Realistic metal concentration exposure for 10 days to Ni and Pb in solution revealed that juvenile prawns partially induce MTLP in hepatopancreas after Pb exposure. Ni was distributed equally between soluble and insoluble fractions, while Pb was present only in the insoluble fraction, suggesting different detoxification strategy. No changes in lipids and glycogen concentration were detected under these experimental conditions in both tissues analyzed. MTLP could not be considered as a suitable indicator for lead exposure in hepatopancreas.

Nunez-Nogueira, Gabriel; Mouneyrac, Catherine; Muntz, Alice; Fernandez-Bringas, Laura

2010-01-01

368

Diatoms from the Colombian and Peruvian Amazon: the Genera Encyonema, Encyonopsis and Gomphonema (Cymbellales: Bacillariophyceae).  

PubMed

The diatom flora of the Colombian and Peruvian Amazon is far less studied than the flora of the Brazilian sector of the basin. Here we present results related to the genera Encyonema, Encyonopsis and Gomphonema. Plankton and periphyton samples were collected in lotic and lentic waterbodies from the Amazonian-Andean region, the Amazon River, Japurá River and Porvenir River basins during 1993, 1994, 2001 and 2003. At each sampling station pH, temperature, water transparency and conductivity were registered. Samples were analyzed with phase contrast microscope (LM) and scanning electron microscope (SEM). Ten taxa are new records for the area; Encyonema for the Peruvian and Colombian Amazon and Encyonopsis for the Colombian Sector. Encyonema neogracile var. tenuipunctatum, E. vulgare, Encyonopsis frequentis, Gomphonema augur var. sphaerophorum and G. contraturris are recorded for the first time in Colombia; Encyonema venezolanum and G. neoapiculatum in Colombia and Peru and the latter also for Amazonia. E. angustecapitatum was mentioned in Colombia before at a pond located at 3000 m asl. We describe a new species from Porvenir River, Amazonas, Colombia: Encyonema amazonianum. PMID:20411706

Vouilloud, Amelia A; Sala, Silvia E; Avellaneda, Marcela Núñez; Duque, Santiago R

2010-03-01

369

Manaus city Flow Warning system and extreme events monitoring in the Amazon Basin  

NASA Astrophysics Data System (ADS)

The Amazon basin is the biggest watershed in the world, in the center of this basin, there is a city called Manaus, with population next to 2 million habitants. Manaus city is bounded by Negro River; one of the main rivers in Amazon, this river has its level checked by Fluvial Station in the Manaus harbor, which has a range of 100 years of hydrological data records. The hydrological cycle in the region next to Manaus has certain regularity, its common variety is considered of 7 months of rising river, in other words, the fluvial quotes rising and 5 months of falling (ebb). Although, the water level variation in Manaus Harbor, from its draft to flow can achieve the variation up to 16 meters of water level height, this difference can affect all the Amazon region, happening impacts such as the interference of regional agriculture and fluvial transportation, besides the economic activities in the harbor and local population welfare, arising from extreme events. Considering the relevance of prediction and accompanying of flows and drafts, the Geologic Survey of Brazil implemented, since 1989, a warning system to these extreme events. This paper focused to demonstrate the a warning system implemented from equations based on the Manaus Harbor quotes, since Negro River has a regular hydrological cycle, thus, it is possible to predict the highest quotes in the hydrological year, in advance till 75 days with accurate prediction, in a gap of 45 to 15 days before the flow. This paper presents, also, the biggest events occurred in a hundred years of records collected by Manaus Harbor, as example, the draft happened in December 2010 and the flow in June 2009, as well demonstrating the values and impacts in the Amazon region.

Santos, A. L. M. R.; Oliveira, D.; Oliveira, M. A.; Moreira, D.; Maciel, J. S. C.

2012-04-01

370

Human Exposure to Mercury and the Accumulation of Methylmercury that is Associated with Gold Mining in the Amazon Basin, Brazil  

Microsoft Academic Search

In order to evaluate the extent of human exposure to mercury in the Amazon, in particular, in the Tapajos River basin, which is a site of extensive alluvial gold mining, we analyzed samples of human hair, blood and urine, as well as fish, collected from different areas for total levels of mercury and methylmercury. In fishing villages, the inhab- itants

Hirokatsu Akagi; Akira Naganumab

371

Sediment transport and sedimentation along the Amazon floodplain  

SciTech Connect

As the Amazon River leaves the Andean foothills and crosses the structural trough in its Brazilian segment, it receives a large increment of discharge, but a small increase in sediment load from the bounding cratons. The gradient of the river declines gradually from Iquitos, Peru, downstream to Coari, Brazil, before increasing downstream to the vicinity of Manaus as the river crosses a structural arch. Between Manaus and Obidos, the river slope declines sharply. The interplay of the variable gradient and increasing discharge creates a pattern of boundary shear stress and sediment transport which the authors have defined by measurement and calculation. The downstream divergence of suspended and bed load transport is responsible for the patterns of aggradation, channel behavior and floodplain morphology. Aggradation has been computed on the basis of three years of sediment transport measurements; floodplain morphology was documented from radar photography and navigation charts; and channel migration from these charts and from aerial and satellite photography. In the reach between the Peruvian border and Coari, the river deposits sand bars within and alongside the channel and shifts laterally at a relatively rapid rate, forming a scroll-bar floodplain topography with long, narrow lakes. In the middle, steeper reach no net aggradation was measured, sand-bar development and channel shifting are limited. Below Manaus, the rapid decline in gradient and the large influx of Andean sediment from the Rio Madeira result in deposition of almost the entire sand load and a portion of the silt.

Dunne, T.; Mertes, A.K.L.; Meade, R.H.

1985-01-01

372

Bacterial flora associated with larval rearing of the giant freshwater prawn, Macrobrachium rosenbergii  

Microsoft Academic Search

Quantitative and qualitative analyses of bacterial flora associated with larval rearing of the giant freshwater prawn, Macrobrachium rosenbergii, along with important water quality parameters, were carried out over a larval cycle. Total viable counts (TVC) varied between 1.1±0.6×104 and 9.8±1.5×106 colony forming units (cfu) ml?1 in water, 2.4±0.4×105 and 8.6±1.6×106 cfu g?1 in eggs and 2.5±1.4×104 and 1.6±1.0×108 cfu g?1

P. V. Phatarpekar; V. D. Kenkre; R. A. Sreepada; U. M. Desai; C. T. Achuthankutty

2002-01-01

373

Spatial clustering and longitudinal variation of Anopheles darlingi (Diptera: Culicidae) larvae in a river of the Amazon: the importance of the forest fringe and of obstructions to flow in frontier malaria.  

PubMed

Deforestation has been linked to a rise in malaria prevalence. In this paper, we studied longitudinally 20 spots, including forested and deforested portions of a temporary river in a malarigenous frontier zone. Larval habitat parameters influencing distribution of Anopheles darlingi (Diptera: Culicidae) larvae were studied. We observed that larvae were clustered in forested-deforested transitions. For the first time in the literature, it was verified that parameters determining larval distribution varied from deforested to forested areas. The proximity to human dwellings was also a significant factor determining distribution, but larvae was most importantly associated with a previously undescribed parameter, the presence of small obstructions to river flow, such as tree trunks within the river channel, which caused pooling of water during the dry season ('microdams'). In deforested areas, the most important factor determining distribution of larvae was shade (reduced luminance). Larvae were absent in the entire studied area during the wet season and present in most sites during the dry season. During the wet-dry transition, larvae were found sooner in areas with microdams, than in other areas, suggesting that flow obstruction prolongs the breeding season of An. darlingi. Adult mosquito densities and malaria incidence were higher during the dry season. Our data correlate well with the published literature, including the distribution of malaria cases near the forest fringes, and has permitted the creation of a model of An. darlingi breeding, where preference for sites with reduced luminance, human presence and microdams would interact to determine larval distribution. PMID:21729392

Barros, F S M; Arruda, M E; Gurgel, H C; Honório, N A

2011-07-01

374

Forecasting terrestrial water storage changes in the Amazon Basin using Atlantic and Pacific sea surface temperatures  

NASA Astrophysics Data System (ADS)

Floods and droughts frequently affect the Amazon River basin, impacting transportation, river navigation, agriculture, and ecosystem processes within several South American countries. Here we examined how sea surface temperatures (SSTs) influence interannual variability of terrestrial water storage anomalies (TWSAs) in different regions within the Amazon basin and propose a modeling framework for inter-seasonal flood and drought forecasting. Three simple statistical models forced by a linear combination of lagged spatial averages of central Pacific (Niño 4 index) and tropical North Atlantic (TNAI index) SSTs were calibrated against a decade-long record of 3°, monthly TWSAs observed by the Gravity Recovery And Climate Experiment (GRACE) satellite mission. Niño 4 was the primary external forcing in the northeastern region of the Amazon basin whereas TNAI was dominant in central and western regions. A combined model using the two indices improved the fit significantly (p < 0.05) for at least 64% of the grid cells within the basin, compared to models forced solely with Niño 4 or TNAI. The combined model explained 66% of the observed variance in the northeastern region, 39% in the central and western regions, and 43% for the Amazon basin as a whole with a 3 month lead time between the SST indices and TWSAs. Model performance varied seasonally: it was higher than average during the rainfall wet season in the northeastern Amazon and during the dry season in the central and western regions. The predictive capability of the combined model was degraded with increasing lead times. Degradation was smaller in the northeastern Amazon (where 49% of the variance was explained using an 8 month lead time vs. 69% for a 1 month lead time) compared to the central and western Amazon (where 22% of the variance was explained at 8 months vs. 43% at 1 month). These relationships may enable the development of an early warning system for flood and drought risk. This work also strengthens our understanding of the mechanisms regulating interannual variability in Amazon fires, as water storage deficits may subsequently lead to decreases in transpiration and atmospheric water vapor that cause more severe fire weather.

de Linage, C.; Famiglietti, J. S.; Randerson, J. T.

2013-10-01

375

Hydrology and climate in the southwestern Amazon basin (Bolivia)  

NASA Astrophysics Data System (ADS)

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 Pacific and in the Tropical Atlantic oceans. The hydrological variability is studied using daily river discharge data of 3 tributaries: the Rio Beni in Rurrenabaque, the Rio Ichilo in Puerto Villaroel and the Mamoré River in Puerto Varador, respectively representative of the Andes, the Andean Piedmont and the lowlands. This information has been collected and criticized in the mark of successive Bolivian - French conventions. The hydrological response of the Andean river is out of phase with that of the piedmont and plain rivers. The Rio Beni in Rurrenabaque experiments high runoff during La Niña events and during cool (warm) events in the northern (southern) tropical Atlantic. On the contrary, the Ichilo and Mamoré Rivers and inundation data show that high runoff are more frequent during El Niño events and when the southern tropical Atlantic Ocean is cooler than normally. 30% of the Beni R. discharge variability is explained by the ENSO events and 25% by the SSTAs in the tropical Atlantic. In the Andean piedmont and in the lowlands, the ENSO explains 45% of the discharges, but differences in series lengths may also contribute to this better result. On the contrary, the relationship with the southern tropical Atlantic is only a tendency and is not statistically significant. To conclude, the SSTAs in the tropical oceans do not allow a prediction of the discharge variability of the Bolivian tributaries of the Madeira River but they contribute to their comprehension. The present results, different for Andean and Piedmont or lowlands tributaries, are consistent with those relative to the ENSO and tropical Atlantic related rainfall anomalies in both regions of Bolivia.

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

2003-04-01

376

Follow-up of mercury levels in fish, human hair and urine in the Madeira and Tapajós basins, Amazon, Brazil  

Microsoft Academic Search

Informal economy of gold mining has contaminated some important river basins in Amazon. Follow-up studies on critical compartments\\u000a showed some areas with high Hg levels in fish as well as in human hair samples. Average Hg in piscivorous fish in the Madeira\\u000a river itself was 846 ppb (N=284) with a maximum of 3921 ppb. Mercury in fish from non polluted

O. Malm; J. R. D. Guimarães; M. B. Castro; W. R. Bastos; J. P. Viana; F. J. P. Branches; E. G. Silveira; W. C. Pfeiffer

1997-01-01

377

Controls over the strontium isotope composition of river water  

Microsoft Academic Search

Strontium concentrations and isotope ratios have been measured in river and ground waters from the Granges, Orinoco, and Amazon river basins. When compared with major element concentrations, the data set has allowed a detailed examination of the controls over the strontium isotope systematics of riverine input to the oceans in the following environments: (1) typical drainage basins containing limestones, evaporites,

M. R. Palmer; J. M. Edmond

1992-01-01

378

Evolution of river dolphins.  

PubMed

The world's river dolphins (Inia, Pontoporia, Lipotes and Platanista) are among the least known and most endangered of all cetaceans. The four extant genera inhabit geographically disjunct river systems and exhibit highly modified morphologies, leading many cetologists to regard river dolphins as an unnatural group. Numerous arrangements have been proposed for their phylogenetic relationships to one another and to other odontocete cetaceans. These alternative views strongly affect the biogeographical and evolutionary implications raised by the important, although limited, fossil record of river dolphins. We present a hypothesis of river dolphin relationships based on phylogenetic analysis of three mitochondrial genes for 29 cetacean species, concluding that the four genera represent three separate, ancient branches in odontocete evolution. Our molecular phylogeny corresponds well with the first fossil appearances of the primary lineages of modern odontocetes. Integrating relevant events in Tertiary palaeoceanography, we develop a scenario for river dolphin evolution during the globally high sea levels of the Middle Miocene. We suggest that ancestors of the four extant river dolphin lineages colonized the shallow epicontintental seas that inundated the Amazon, Paraná, Yangtze and Indo-Gangetic river basins, subsequently remaining in these extensive waterways during their transition to freshwater with the Late Neogene trend of sea-level lowering. PMID:11296868

Hamilton, H; Caballero, S; Collins, A G; Brownell, R L

2001-03-01

379

Evolution of river dolphins.  

PubMed Central

The world's river dolphins (Inia, Pontoporia, Lipotes and Platanista) are among the least known and most endangered of all cetaceans. The four extant genera inhabit geographically disjunct river systems and exhibit highly modified morphologies, leading many cetologists to regard river dolphins as an unnatural group. Numerous arrangements have been proposed for their phylogenetic relationships to one another and to other odontocete cetaceans. These alternative views strongly affect the biogeographical and evolutionary implications raised by the important, although limited, fossil record of river dolphins. We present a hypothesis of river dolphin relationships based on phylogenetic analysis of three mitochondrial genes for 29 cetacean species, concluding that the four genera represent three separate, ancient branches in odontocete evolution. Our molecular phylogeny corresponds well with the first fossil appearances of the primary lineages of modern odontocetes. Integrating relevant events in Tertiary palaeoceanography, we develop a scenario for river dolphin evolution during the globally high sea levels of the Middle Miocene. We suggest that ancestors of the four extant river dolphin lineages colonized the shallow epicontintental seas that inundated the Amazon, Paraná, Yangtze and Indo-Gangetic river basins, subsequently remaining in these extensive waterways during their transition to freshwater with the Late Neogene trend of sea-level lowering.

Hamilton, H; Caballero, S; Collins, A G; Brownell, R L

2001-01-01

380

Modelling conservation in the Amazon basin  

Microsoft Academic Search

Expansion of the cattle and soy industries in the Amazon basin has increased deforestation rates and will soon push all-weather highways into the region's core. In the face of this growing pressure, a comprehensive conservation strategy for the Amazon basin should protect its watersheds, the full range of species and ecosystem diversity, and the stability of regional climates. Here we

Britaldo Silveira Soares-Filho; Daniel Curtis Nepstad; Lisa M. Curran; Gustavo Coutinho Cerqueira; Ricardo Alexandrino Garcia; Claudia Azevedo Ramos; Eliane Voll; Alice McDonald; Paul Lefebvre; Peter Schlesinger

2006-01-01

381

Tourism in the Amazon: conclusions and solutions  

Microsoft Academic Search

Purpose – The paper aims to present answers to the strategic question: “Does sustainable tourism offer solutions for the protection of the Amazon rainforest?” It also aims to capture the essence of conclusions of eight papers written by 11 tourism experts to the Worldwide Hospitality and Tourism Themes (WHATT) issue on tourism in the Amazon, South America. Design\\/methodology\\/approach – The

Donald Sinclair

2010-01-01

382

ENSO and the natural variability in the flow of tropical rivers  

Microsoft Academic Search

This paper examines the relationship between the annual discharges of the Amazon, Congo, Paran á, and Nile rivers and the sea surface temperature (SST) anomalies of the eastern and central equatorial Pacific Ocean, an index of El Niño-Southern Oscillation (ENSO). Since river systems are comprehensive integrators of rainfall over large areas, accurate characterization of the flow regimes in major rivers

Kishan N. Amarasekera; Robert F. Lee; Earle R. Williams; Elfatih A. B. Eltahir

1997-01-01

383

Traditional Devices and Gear for Collecting Fry of 'Sugpo' Giant Tiger Prawn, 'Penaeus monodon' in the Philippines.  

National Technical Information Service (NTIS)

Eight typical devices and gears for catching the wild fry of the giant tiger prawn, Penaeus monodon, locally called sugpo are described and illustrated. There are three stationary ones viz. fry lure, fry filter net and set fry trap, and five mobile ones v...

H. Motoh

1980-01-01

384

The Effect of Partial Replacement of Dietary Fishmeal with Fermented Prawn Waste Liquor on Juvenile Sea Bass Growth  

Microsoft Academic Search

A feeding trial was conducted for 49 days to evaluate the effect of partially substituting fishmeal with fermented prawn waste liquor (FPWL) in juvenile sea bass diets at 10%, 20%, and 30% of the total diet. Growth performance of sea bass from 16 g up to 40 g fed with FPWL-supplemented diet was not significantly different from the all fishmeal

N. M. Nor; Z. Zakaria; M. S. A. Manaf; M. M. Salleh

2011-01-01

385

Effect of feeding Bacillus sp. as probiotic bacteria on growth of giant freshwater prawn (Macrobrachium rosenbergii de Man).  

PubMed

The effects of feeding two Bacillus spp. isolated from the intestine of the giant freshwater prawn on the growth of Giant Freshwater Prawns (Macrobrachium rosenbergii de Man) was examined. The isolated Bacillus KKU02 and Bacillus KKU03 (approximately 10(7) CFU mL(-1)) were mixed into commercial prawn feed (200 mL kg(-1)). After rearing shrimp with the bacteria in four feed treatments, (Bacillus KKU03, Bacillus KKU02, mixed culture and control groups) for 120 days, body length and weight of the prawns in mixed culture tanks were significantly higher (p = 0.05) than in the control tanks (7.48 cm and 3.32 g, vs 6.6 cm and 2.1 g, respectively). Both isolates were found to produce amylase and protease. The stabilities of the single Bacillus sp., mixed culture and commercial probiotic in the feeds were examined during storage at 4 degrees C and room temperature. The percentage viability of Bacillus KKU02, Bacillus KKU03 and mixed culture stored at room temperature declined dramatically to 2.54, 21.88 and 10.92% within 2 weeks, respectively. At 4 degrees C however, the percentage viability of the tested probiotics reduced slowly. The survival of the commercial probiotics was the same at both temperatures about 50% after 70 days' storage. PMID:19069961

Deeseenthum, Sirirat; Leelavatcharamas, Vichai; Brookes, John D

2007-05-01

386

Identification and isolation of a spiroplasma pathogen from diseased freshwater prawns, Macrobrachium rosenbergii, in China: A new freshwater crustacean host  

Microsoft Academic Search

Disease epizootics in freshwater cultured crustaceans, including freshwater prawns (Macrobrachium rosenbergii), gained high attention recently in Jiangsu, China due to intensive development of freshwater aquaculture and their susceptibility to massive mortalities. Morphological observation indicated that the pathogen in diseased M. rosenbergii had a helical morphology and lacked a cell wall. The agent could infect hemocytes and all the connective tissues

Tingming Liang; Xinlun Li; Jie Du; Wei Yao; Guiyao Sun; Xuehong Dong; Zhiguo Liu; Jiangtao Ou; Qingguo Meng; Wei Gu; Wen Wang

2011-01-01

387

Shoal and prey patch choice by co-occurring fishes and prawns: inter-taxa use of socially transmitted cues  

PubMed Central

Animals can use socially transmitted information to learn about the distribution and quality of resources without incurring the costs associated with having to search for and sample them first hand. Recently, it has been shown that the use of chemical social information specific to patterns of diet and habitat use is an important mechanism underpinning recognition and social organization in shoaling fishes. In this study we revealed that the use of resource-specific chemical information is not limited to conspecifics, or even members of the same taxon. In a series of laboratory experiments, we showed that threespine sticklebacks (Gasterosteus aculeatus) could recognize similar patterns of habitat use in common prawns (Leander serratus), preferentially orientating towards groups of prawns exposed to the same habitats as themselves, and even selecting foraging patches located close to them. Prawns were seen to use habitat-specific cues generated by conspecifics, but not by sticklebacks, suggesting that the benefits of forming these heterospecific social association patterns may be unequal for prawns and fishes. Our findings suggest that some species might use co-occurring, unrelated species as information centres in order to orient and locate resources within their surroundings.

Webster, M.M; Ward, A.J.W; Hart, P.J.B

2007-01-01

388

Purification and characterization of the female-specific protein (vitellogenin) in mature female hemolymph of the prawn, Penaeus monodon  

Microsoft Academic Search

Purifying and characterizing the female-specific protein (vitellogenin) from the hemolymph of mature female prawn, Penaeus monodon, were the objectives of this study. Hemolymph was stained with Sudan Black B and fractionated by an ultracentrifuge. A specific protein (vitellogenin) appeared in the fourth fraction of the female hemolymph based on the Western blotting and polyacrylamide gel electrophoresis (PAGE). The fourth fraction

CHING-FONG CHANG; FANG-YI LEE; YUNG-SEN HUANG; TSAI-HSIA HONG

1994-01-01

389

Cyanobacteria and prawn farming in northern New South Wales, Australia—a case study on cyanobacteria diversity and hepatotoxin bioaccumulation  

Microsoft Academic Search

Harmful cyanobacteria pose a hazard to aquatic ecosystems due to toxins (hepatotoxic microcystins, nodularins, and cylindrospermopsin) they produce. The microcystins and nodularins are potent toxins, which are also tumor promoters. The microcystins and nodularins may accumulate into aquatic organisms and be transferred to higher trophic levels, and eventually affect vector animals and consumers. Prawn farming is a rapidly growing industry

Harri T. Kankaanpaeae; Jon Holliday; Helge Schroeder; Timothy J. Goddard; Richard von Fister; Wayne W. Carmichael

2005-01-01

390

Can high-frequency sound affect gas-bubble dynamics? A study in the intact prawn Palaemon elegans.  

PubMed

Underwater sound beacons (pingers) are employed in professional and scientific diving for location and navigation. Previous studies have demonstrated that exposure to acoustic fields may lead to the emergence of bubbles and cavities in tissues by rectified diffusion. However, this issue was studied mainly in vitro in various gels and isolated tissues. In the present study, we used the intact prawn Palaemon elegans, whose transparent shell makes it possible to conduct continuous microscopic observation of gas-bubble dynamics in the intact living prawn, to study the effect of high-frequency sound. In a crossover designed experiment, prawns were exposed to hyperbaric pressure of 203 kPa for 10 min, followed by decompression at 40 m/min (control). This procedure was carried out in the study group during transmission of a 37-kHz, 0.25-W, 10-ms pulse width, 1 pulse/s pulse interval. A significant increase was found in the mean volume of bubbles present for a longer period of time, in a higher percentage of the high-frequency sound-exposed prawns. We suggest that this sound exposure causes more gaseous micronuclei to grow into bubbles, and more of the dissolved gas to shift into the gas phase. PMID:11179625

Arieli, Y; Arieli, R; Shupak, A

2000-11-01

391

Immunomodulatory effect of Withania somnifera supplementation diet in the giant freshwater prawn Macrobrachium rosenbergii (de Man) against Aeromonas hydrophila.  

PubMed

The effect of Withania somnifera extract supplementation diets on innate immune response in giant freshwater prawn Macrobrachium rosenbergii (de Man) against Aeromonas hydrophila was investigated. The bacterial clearance efficiency significantly increased in prawn fed with 0.1% and 1.0% doses of W. somnifera supplementation diet against pathogen from weeks 1-4 as compared to the control. The innate immune parameters such as, phenoloxidase activity, superoxide anion level, superoxide dismutase activity, nitrate, and nitrite concentrations were significantly enhanced in prawn fed with 0.1% and 1.0% doses of W. somnifera supplementation diet from weeks 1-4 against pathogen. The total hemocyte counts (THC) significantly increased in prawn fed with 0.1% and 1.0% doses diet from weeks 1-4 against pathogen as compared to the control. These results strongly suggested that administration of W. somnifera through supplementation diet positively enhances the innate immune system and enhanced survival rate in M. rosenbergii against A. hydrophila infection. PMID:22118967

Harikrishnan, Ramasamy; Balasundaram, Chellam; Jawahar, Sundaram; Heo, Moon-Soo

2011-11-17

392

The relationship between soil variables and leafcutter ant ( Atta sexdens ) nest distribution in the Colombian Amazon  

Microsoft Academic Search

We determined the relationships between several soil variables and the distribution of leafcutter ant (Atta sexdens) nests on the Colombian shore of the Amazon River. Seven habitats were identified in which nests were consistently present\\u000a or absent. Soil samples for physiochemical analysis were taken near nest sites in three habitats where nests were present\\u000a and from randomly selected sites in

H. A. J. A. van Gils; A. Gaigl; L. E. Gómez

2010-01-01

393

Methylmercury in a predatory fish ( Cichla spp.) inhabiting the Brazilian Amazon  

Microsoft Academic Search

This research tested whether limnological conditions, biological characteristics of fish and anthropogenic impacts influenced the assimilation of methylmercury into the muscle of a sedentary piscivorous fish, Cichla spp., from three rivers (Negro, Madeira, Tapajós) and two hydroelectric reservoirs (Balbina, Tucuruí) within the Brazilian Amazon. Methylmercury in this fish ranged from 0.04 to 1.43?gg?1 w.w. across sites. No significant differences were

Helena do A. Kehrig; Bruce M. Howard; Olaf Malm

2008-01-01

394

Factors Controlling Respiration Rates and Respired Carbon Dioxide Signatures in Riverine Ecosystems of the Amazon Basin  

Microsoft Academic Search

This study examined the processes controlling respiration rates observed in streams and rivers throughout the Amazon basin during the dry season by substituting spatial coverage for experimental manipulation. Throughout the Brazilian states of Amazonas and Acre, respiration rates ranged from 0.066 to 1.45 muM\\/hr of O2 consumed. In situ respiration was positively correlated with pH (r2=0.60), with pH values ranging

E. E. Ellis; J. E. Richey; A. K. Aufdenkampe; P. D. Quay; A. V. Krusche; S. R. Alin

2006-01-01

395

Seasonal variations in the Amazon plume-related atmospheric carbon sink  

Microsoft Academic Search

The Amazon River plume is a highly seasonal feature that can reach more than 3000 km across the tropical Atlantic Ocean, and cover ?2 million km2. Ship observations show that its seasonal presence significantly reduces sea surface salinity and inorganic carbon. In the western tropical North Atlantic during April–May 2003, plume-influenced stations exhibited surface DIC concentrations lowered by as much

S. R. Cooley; V. J. Coles; A. Subramaniam; P. L. Yager

2007-01-01

396

Alkaline serine protease is an exotoxin of Vibrio alginolyticus in kuruma prawn, Penaeus japonicus.  

PubMed

An extracellular lethal toxin produced by Vibrio alginolyticus strain Swy originally isolated from diseased kuruma prawn(Penaeus japonicus) was partially purified by Fast Protein Liquid Chromatography with hydrophobic interaction (Phenyl Sepharose Hig hPerformance) chromatography and gel filtration columns. The toxin is an alkaline serine protease, inhibited by phenyl-methylsulfonyl fluoride (PMSF),and showed maximal activity at pH 10, having a molecular weight of about 33kDa estimated by SDS-PAGE and gel filtration chromatography. In addition, the toxin was also completely inhibited by FeCl2 but partially inhibited by CaCl2, CuCl2, CoCl2,MnCl2, and ZnCl2, and not inhibited by ethylenediaminetetraacetic acid (EDTA), ethylene glycol-bis(beta-amino-ethyl ether)N,N,N',N'-tetraacetic acid (EGTA), iodoacetamide, pepstatin A, sodium dodecylsulfate (SDS), and N-tosyl-l-phenyl-alanine chloromethyl ketone (TPCK). Both the crude extracellular products (ECP) and the partially purified toxin are lethal for kuruma prawn at LD50 values of 0.30 and 0.27 microg protein/g body weight, respectively. The addition of PMSF completely inhibited the lethal toxicity of both the ECP and the partially purified toxin, indicating that this serine protease is a lethal factor produced by the bacterium. The 33-kDa protease is, therefore, suggested to be a new toxic protease produced by V. alginolyticus strain Swy. PMID:9003588

Lee, K K; Yu, S R; Liu, P C

1997-02-01

397

Impact of TBT on the vitellogenesis and sex hormones in freshwater prawn Macrobrachium rosenbergii (De Man, 1879)  

PubMed Central

Background Tributyltin (TBT) is a ubiquitous persistent xenobiotic that can be found in freshwater, estuarine and marine ecosystem. TBT is a strong endocrine disrupting compound (EDC) that can cause toxic threat to aquatic organisms. Imposex, sexual deformities and endocrine dysfunctions are the causes of TBT to most of the aquatic organisms. Effect of TBT on the vitellogenesis and sex hormonal changes in Macrobrachium rosenbergii has never been reported. Hence, the present investigation was undertaken to find out the impact of TBT on histological changes in the different reproductive tissues, sex hormonal alterations and level of biomarkers like vitellogenin and vitellin in M. rosenbergii. Results The present investigation documents the possible impact of tributyltin (TBT) on the vitellogenesis in freshwater female prawn M. rosenbergii. TBT at 10 ng/l, 100 ng/l and 1000 ng/l concentrations were exposed individually to prawns for a period of three months. At higher concentration of 1000 ng/l, the ovarian development was arrested and ovary remained at spent stage. At lower concentration of TBT (10 ng/l), the development proceeded up to early vitellogenic stage. At intermediate concentration of 100 ng/l TBT, the ovary remained at pre vitellogenic stage and thereafter no development was noticed. Histological results indicated the normal ovarian development with vitellogenic oocytes, filled with yolk globules in control prawn. On the other hand, the TBT treated groups showed reduction in yolk globules, fusion of developing oocytes and abundance of immature oocytes. Immunofluorescence staining denoted the remarkable reduction in vitellin content in ovary of TBT treated prawn. Hence, TBT had conspicuously inhibited the vitellogenesis by causing hormonal imbalance in M. rosenbergii. Conclusion TBT had notably inhibited the vitellogenesis due to hormonal imbalance. This endocrine dysfunction ultimately impaired the oogenesis in the freshwater female prawn M. rosenbergii.

2013-01-01

398

Impact of TBT on the vitellogenesis and sex hormones in freshwater prawn Macrobrachium rosenbergii (De Man, 1879).  

PubMed

BACKGROUND: Tributyltin (TBT) is a ubiquitous persistent xenobiotic that can be found in freshwater, estuarine and marine ecosystem. TBT is a strong endocrine disrupting compound (EDC) that can cause toxic threat to aquatic organisms. Imposex, sexual deformities and endocrine dysfunctions are the causes of TBT to most of the aquatic organisms. Effect of TBT on the vitellogenesis and sex hormonal changes in Macrobrachium rosenbergii has never been reported. Hence, the present investigation was undertaken to find out the impact of TBT on histological changes in the different reproductive tissues, sex hormonal alterations and level of biomarkers like vitellogenin and vitellin in M. rosenbergii. RESULTS: The present investigation documents the possible impact of tributyltin (TBT) on the vitellogenesis in freshwater female prawn M. rosenbergii. TBT at 10 ng/l, 100 ng/l and 1000 ng/l concentrations were exposed individually to prawns for a period of three months. At higher concentration of 1000 ng/l, the ovarian development was arrested and ovary remained at spent stage. At lower concentration of TBT (10 ng/l), the development proceeded up to early vitellogenic stage. At intermediate concentration of 100 ng/l TBT, the ovary remained at pre vitellogenic stage and thereafter no development was noticed. Histological results indicated the normal ovarian development with vitellogenic oocytes, filled with yolk globules in control prawn. On the other hand, the TBT treated groups showed reduction in yolk globules, fusion of developing oocytes and abundance of immature oocytes. Immunofluorescence staining denoted the remarkable reduction in vitellin content in ovary of TBT treated prawn. Hence, TBT had conspicuously inhibited the vitellogenesis by causing hormonal imbalance in M. rosenbergii. CONCLUSION: TBT had notably inhibited the vitellogenesis due to hormonal imbalance. This endocrine dysfunction ultimately impaired the oogenesis in the freshwater female prawn M. rosenbergii. PMID:23634699

Peranandam, Revathi; Palanisamy, Iyapparaj; Lourduraj, Arockia Vasanthi; Natesan, Munuswamy; Muthukalingan, Krishnan

2013-05-01

399

Assessing the Amazon Basin Circulation with Stable Water Isotopes  

NASA Astrophysics Data System (ADS)

The isotopic abundances of Oxygen-18 (? 18O) and Deuterium (? 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 regional to global-scale atmospheric moisture budgets. Based on data in the Global Network on Isotopes in Precipitation (GNIP) database, we analyse the simulation of the land surface hydrology and water cycling. Temporal changes between 1965 and 2000 in stable water isotopic signatures in the Amazon have been used to evaluate global climate model (GCM) predictions revealing notable anomalies. For example, the differences in the wet season deuterium excess between Belem and Manaus are consistent with recent GCM simulations only if there has been a relative increase in evaporation from non-fractionating water sources over this period. Despite earlier predictions that land-use change signals would be found, late twentieth century data reveal no significant change in dry season isotopic characteristics. On the other hand, more recent isotopic data do show trends at stations in the Andes, where as much as 88% of the rainfall is thought to be derived from recycled moisture. At Izobamba the wet season depletions are enhanced (greater depletion) and the dry season ones decreased (less depletion). At Bogota only the wet months show statistically significant changes - also an enhancement. More depletion in the wet months is consistent with reductions in non-fractioning recycling such as through transpiration and in full re-evaporation of canopy-intercepted rainfall. These data might be linked to deforestation impacts. Results of GCM and simpler model simulations of the Amazon suggest that the recent stable isotope record is consistent with the predicted effects of forest removal, perhaps combined with greenhouse warming. At a minimum, large-scale simulations of South American climate ought to be tested against these isotopic data in any validation effort. Specific caveats our conclusions include: (i)monthly isotope data only are available in GNIP and hence analysed; (ii) the statistically significant seasonal changes reported might be related to, or even exaggerated by, El Niño-Southern Oscillation (ENSO) events or other climatic variations that modify the Walker circulation and Inter-Tropical Convergence Zone (ITCZ) position and hence affect the moisture climatology of the Amazon; (iii)no information on fluxes from simulated open water as a surface type in the Amazon GCM experiments has been considered; (iv)the selected models are failing to correctly simulate the relative components of transpiration and re-evaporated canopy interception in the Amazon dry season; and (v) no isotope tracking in the Amazon deforestation simulations was reviewed, because none is yet available. These shortcomings deserve further work.

McGuffie, K.; Henderson-Sellers, A.

2004-05-01

400

Arsenic, cadmium, chromium, lead, mercury, and selenium levels in blood of four species of turtles from the Amazon in Brazil.  

PubMed

Using blood as a method of assessing metal levels in turtles may be useful for populations that are threatened or endangered or are decreasing. In this study the levels of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and selenium (Se) in blood of four species of turtles from the tributaries of the Rio Negro in the Amazon of Brazil were examined. The turtles included the six-tubercled Amazon (river) turtle (Podocnemis sextuberculata), red-headed Amazon (river) turtle (Podocnemis erythrocephala), big-headed Amazon (river) turtle (Peltocephalus dumerilianus), and matamata turtle (Chelus fimbriatus). Blood samples were taken from the vein in the left hind leg of each turtle. There were significant interspecific differences in the sizes of the turtles from the Rio Negro, and in concentrations of Pb, Hg, and Se; the smallest species (red-headed turtles) had the highest levels of Pb in their blood, while Se levels were highest in big-headed turtles and lowest in red-headed turtles. Hg in blood was highest in matamata, intermediate in big-headed, and lowest in the other two turtles. Even though females were significantly larger than males, there were no significant differences in metal levels as a function of gender, and the only relationship of metals to size was for Cd. Variations in metal levels among species suggest that blood may be a useful bioindicator. Metal levels were not high enough to pose a health risk to the turtles or to consumers, such as humans. PMID:19953418

Burger, Joanna; Jeitner, Christian; Schneider, Larissa; Vogt, Richard; Gochfeld, Michael

2010-01-01

401

Attenuation coefficients and absorbed gamma radiation energy of different varieties of potato, mango and prawn at different storage time and physiological condition.  

PubMed

Attenuation coefficients of different varieties of gamma irradiated potato (Kufri Chandramukhi, Kufri Jyoti, and Kufri Sindhuri), mango (Himsagar, Langra, Dashehri and Fazli) and prawn (Tiger prawn and Fresh water prawn) of different storage time and physiological stages were determined. After six months storage attenuation coefficient of Kufri Chandramukhi was decreased by 30.8% with decrease of density and moisture content. Decreasing trend of attenuation coefficient during storage was more prominent (almost 50%) in other two varieties of potato. On the other hand in all four varieties, unripe mango consisted of significantly less (p?0.05) attenuation coefficient (around 11-14%) than the ripe one due to changes in physiological properties and density. Different varieties of prawn had different attenuation coefficients due to subtle differences in their proximate composition. Due to having different attenuation coefficients, different food components, even different varieties of same food component absorbed different gamma radiation energy though exposed to same radiation dose. PMID:24128533

Ghosh, Sayanti; Das, M K

2013-09-04

402

Direct Use of Low Temperature Geothermal Water by Aquafarms International, Inc. For Freshwater Aquaculture (Prawns and Associated Species). An Operations and Maintenance Manual.  

National Technical Information Service (NTIS)

In connection with an ongoing commercial aquaculture project in the Coachella Valley, California; a twelve month prawn growout demonstration project was conducted. This project began in August, 1979 and involved the use of low temperature (85 exp 0 F) geo...

R. Broughton M. Price V. Price D. Grajcer

1984-01-01

403

Amazon deforestation and climate change  

SciTech Connect

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 length of the dry season also increased; such an increase could make reestablishment of the tropical forests after massive deforestation particularly difficult. 31 refs., 3 figs., 2 tabs.

Shukla, J.; Nobre, C.; Sellers, P. (Univ. of Maryland, College Park (USA))

1990-03-16

404

Population Structure of the Sword Prawn (Parapenaeopsis hardwickii) (Decapoda: Penaeidae) in the East China Sea and Waters Adjacent to Taiwan Inferred from the Mitochondrial Control Region  

Microsoft Academic Search

Tzong-Der Tzeng (2007) Population structure of the sword prawn (Parapenaeopsis hardwickii) (Decapoda: Penaeidae) in the East China Sea and waters adjacent to Taiwan inferred from the mitochondrial control region. Zoological Studies 46(5): 561-568. Sequence analyses on the complete mitochondrial control region (1048 bp in length) were conducted to elucidate the population genetic structure of the sword prawn (Parapenaeopsis hardwickii) (Decapoda:

Tzong-Der Tzeng

2007-01-01

405

9 Evaluating the effects of a turtle excluder device (TED) and square mesh codend bycatch reduction device (BRD) in Queensland's deepwater eastern king prawn (Penaeus plebejus) trawl fishery  

Microsoft Academic Search

9.1 ABSTRACT This chapter described the bycatch and quantified the effects of a turtle excluder device (TED) and square mesh codend bycatch reduction device (BRD) on the catch rates of bycatch and targeted prawns in the deepwater eastern king prawn fishery off the south-east Queensland coast, based on a 10-day research charter. A total of 227 taxa were recoded in

A. J. Courtney; M. J. Campbell; M. L. Tonks; D. P. Roy; S. W. Gaddes; P. M. Kyne; K. E. Chilcott

406

Ultrastructural changes during spermatogenesis, biochemical and hormonal evidences of testicular toxicity caused by TBT in freshwater prawn macrobrachium rosenbergii (De Man, 1879).  

PubMed

The present investigation documents the impact of tributyltin (TBT) on the ultrastructural variation of spermatogenesis in freshwater prawn Macrobrachium rosenbergii. The environmentally realistic concentration of TBT can cause damages to the endocrine and reproductive physiology of crustaceans. In this context, three concentrations viz. 10, 100, and 1000 ng/L were selected and exposed to prawns for 90 days. The TBT exposed prawn exhibited decrease the reproductive activity as evidenced by sperm count and sperm length compared to control. Histopathological results revealed the retarded testicular development, abnormal structure of seminiferous tubule, decrease in the concentration of spermatozoa, diminution of seminiferous tubule membrane, abundance of spermatocytes and vacuolation in testis of treated prawns. Ultrastructural study also confirmed the impairment of spermatogenesis in treated prawns. Furthermore, radioimmunoassay (RIA) clearly documented the reduction of testosterone level in TBT exposed groups. Thus, TBT substantially reduced the level of male sex hormone as well as biochemical constituents which ultimately led to impairment of spermatogenesis in the freshwater male prawn M.rosenbergii. © 2013 Wiley Periodicals, Inc. Environ Toxicol, 2013. PMID:23362226

Revathi, Peranandam; Iyapparaj, Palanisamy; Vasanthi, Lourduraj Arockia; Munuswamy, Natesan; Krishnan, Muthukalingan

2013-01-30

407

River of Venom  

NSDL National Science Digital Library

You, the reader, show up to help study Africanized bees in the Amazon - only to discover the project's director unconscious on the floor. What's going on? Was it an accident or skullduggery? "River of Venom" has three parts. The story begins with Episode One, continues in Episode Two, and wraps up in the Conclusion. Episode One emphasis is medical science and human health. Episode Two requires deductive reasoning. Both episodes present clues and culminate in a mystery question that the reader tries to answer correctly. Facts about the science subjects are integrated into the clue-finding activity for each Episode.

Ken Eklund (Writerguy REV)

1997-02-01

408

Rainfall trends in the Brazilian Amazon Basin in the past eight decades  

NASA Astrophysics Data System (ADS)

Rainfall series at 18 stations along the major rivers of the Brazilian Amazon Basin, having data since 1920s or 1930s, are analyzed to verify if there are appreciable long-term trends. Annual, rainy-season, and dry-season rainfalls are individually analyzed for each station and for the region as a whole. Some stations showed positive trends and some negative trends. The trends in the annual rainfall are significant at only six stations, five of which reporting increasing trends (Barcelos, Belem, Manaus, Rio Branco, and Soure stations) and just one (Itaituba station) reporting decreasing trend. The climatological values of rainfall before and after 1970 show significant differences at six stations (Barcelos, Belem, Benjamin Constant, Iaurete, Itaituba, and Soure). The region as a whole shows an insignificant and weak downward trend; therefore, we cannot affirm that the rainfall in the Brazilian Amazon basin is experiencing a significant change, except at a few individual stations. Subregions with upward and downward trends are interspersed in space from the far eastern Amazon to western Amazon. Most of the seasonal trends follow the annual trends, thus, indicating a certain consistency in the datasets and analysis.

Satyamurty, Prakki; de Castro, Aline Anderson; Tota, Julio; da Silva Gularte, Lucia Eliane; Manzi, Antonio Ocimar

2010-01-01

409

Interpretation of seismic stratigraphy on the Amazon continental shelf  

SciTech Connect

The stratigraphy of the Amazon subaqueous delta has been examined using high-resolution reflection profiles. 15 piston cores from the Amazon Shelf were used to interpret the significance of the reflectors evident in the seismic profiles. Acoustic reflectors correlate with changes in grain size within cores, and generally represent coarser layers within the muddy deposits of the delta. Measurement of compressional-wave seismic velocity and saturated bulk density demonstrate that the correlation results from changes in acoustic impedance, caused by the grain-size variations. The reflectors reveal two predominant types of seismic stratigraphy: depositional and erosional. The depositional stratigraphy contains reflectors formed by relatively subtle change in grain size. Gently dipping topset and steeply dipping foreset demonstrate upward and seaward progradation of the subaqueous delta. This stratigraphy is truncated by erosional reflectors, which are significantly coarser layers. The erosional reflectors divide the depositional stratigraphy into distinct sets. The prevalence of erosional reflectors is greatest in the topset region near the river mouth, suggesting that sediment in this region, which is rapidly accumulating on 100-year time scales, has been eroded over longer time scales within the Holocene.

Alexander, C.R. Jr.; Nittrouer, C.A.; Demaster, D.J.

1985-01-01

410

Interferometric radar measurements of water level changes on the Amazon flood plain  

NASA Astrophysics Data System (ADS)

Measurements of water levels in the main channels of rivers, upland tributaries and floodplain lakes are necessary for understanding flooding hazards, methane production, sediment transport and nutrient exchange. But most remote river basins have only a few gauging stations and these tend to be restricted to large river channels. Although radar remote sensing techniques using interferometric phase measurements have the potential to greatly improve spatial sampling, the phase is temporally incoherent over open water and has therefore not been used to determine water levels. Here we use interferometric synthetic aperture radar (SAR) data, acquired over the central Amazon by the Space Shuttle imaging radar mission, to measure subtle water level changes in an area of flooded vegetation on the Amazon flood plain. The technique makes use of the fact that flooded forests and floodplain lakes with emergent shrubs permit radar double-bounce returns from water and vegetation surfaces, thus allowing coherence to be maintained. Our interferometric phase observations show decreases in water levels of 7-11 cm per day for tributaries and lakes within ~20 km of a main channel and 2-5 cm per day at distances of ~80 km. Proximal floodplain observations are in close agreement with main-channel gauge records, indicating a rapid response of the flood plain to decreases in river stage. With additional data from future satellite missions, the technique described here should provide direct observations important for understanding flood dynamics and hydrologic exchange between rivers and flood plains.

Alsdorf, Douglas E.; Melack, John M.; Dunne, Thomas; Mertes, Leal A. K.; Hess, Laura L.; Smith, Laurence C.

2000-03-01

411

Interferometric radar measurements of water level changes on the Amazon flood plain  

PubMed

Measurements of water levels in the main channels of rivers, upland tributaries and floodplain lakes are necessary for understanding flooding hazards, methane production, sediment transport and nutrient exchange. But most remote river basins have only a few gauging stations and these tend to be restricted to large river channels. Although radar remote sensing techniques using interferometric phase measurements have the potential to greatly improve spatial sampling, the phase is temporally incoherent over open water and has therefore not been used to determine water levels. Here we use interferometric synthetic aperture radar (SAR) data, acquired over the central Amazon by the Space Shuttle imaging radar mission, to measure subtle water level changes in an area of flooded vegetation on the Amazon flood plain. The technique makes use of the fact that flooded forests and floodplain lakes with emergent shrubs permit radar double-bounce returns from water and vegetation surfaces, thus allowing coherence to be maintained. Our interferometric phase observations show decreases in water levels of 7-11 cm per day for tributaries and lakes within approximately 20 km of a main channel and 2-5 cm per day at distances of approximately 80 km. Proximal floodplain observations are in close agreement with main-channel gauge records, indicating a rapid response of the flood plain to decreases in river stage. With additional data from future satellite missions, the technique described here should provide direct observations important for understanding flood dynamics and hydrologic exchange between rivers and flood plains. PMID:10724167

Alsdorf; Melack; Dunne; Mertes; Hess; Smith

2000-03-01

412

Climate Conditions Determine Amazon Fire Risk  

NASA Website

Using an innovative satellite technique, NASA scientists have determined that a previously unmapped type of wildfire in the Amazon rainforest is responsible for destroying several times more forest than has been lost through deforestation in recent years.

413

Use of ethanol production by-products for producing microalgae, tilapia, and freshwater prawns  

SciTech Connect

By-products from fermentation of grains to alcohol are highly valued as feed supplements for beef and dairy cattle, swine, and poultry. The quantity of wet distillers by-products (stillage) from fuel alcohol production is expected to increase greatly. Unlike dried distillers by-products, wet distillers by-products have generally been abandoned as feed supplements for livestock because of high water content, cost of handling, and storage problems. Using wet distillers by-products as a fertilizer or feed supplement in aquatic production systems appears promising. Two experiments were conducted to determine relationships between stillage application rates and production of microalgae and yields of tilapia (fish) and freshwater prawns (shrimp). Dissolved oxygen concentrations and several other water quality parameters were also monitored. 19 refs., 3 figs., 17 tabs.

Behrends, L.L.; Kingsley, J.B.; Price, A.H. III

1983-01-01

414

Saharan dust in the Amazon Basin  

Microsoft Academic Search

Saharan dust is shown to enter the Central Amazon Basin (CAB) in bursts which accompany major wet season rain systems. Low-level horizontal convergence feeding these rain systems draws dust from plumes which have crossed the tropical Atlantic under the large-scale circulation fields. Mass exchange of air between the surface and 4km over the eastern Amazon basin is calculated using rawinsonde

R. Swap; M. Garstang; S. Greco; R. Talbot; P. Kållberg

1992-01-01

415

Post-Embryonic Transcriptomes of the Prawn Macrobrachium rosenbergii: Multigenic Succession through Metamorphosis  

PubMed Central

Like many metazoans, the freshwater prawn Macrobrachium rosenbergii begins its post-embryonic life with a set of morphologically distinct planktonic larval stages, followed by a benthic post-larval stage during which the maturing organism differs from the larvae both ecologically and physiologically. Understanding of the molecular basis underlying morphogenesis in crustaceans is limited to the observation that methyl farnesoate, the non-epoxidated form of the insect juvenile hormone, acts as the active crustacean juvenoid. Molt steroids were also linked to morphogenesis and several other molecular pathways, such as Hedgehog and Wnt, are known to underlie morphogenesis in all metazoans examined and, as such, are thought to do the same in crustaceans. Using next generation sequencing, we deep-sequenced the transcriptomes of several larval and post-larval stages. De novo assembly, followed by bioinformatics analysis, revealed that many novel transcripts are over-expressed in either larvae- or post-larvae-stage prawn, shedding light on the molecular basis underlying M. rosenbergii metamorphosis. Fast larval molting rates and periodic morphological changes were reflected in over-expression of transcripts annotated to the cell cycle, DNA replication and morphogenic pathways (i.e., Hedgehog and Wnt). Further characterization of transcripts assigned to morphogenic pathways by real-time RT-PCR reconfirmed their over-expression in larvae, albeit with a more complex expression pattern when examined in the individual developmental stages. The expression level of an orthologue of cytochrome P450, 15A1, known to epoxidize methyl farnesoate in insects, was increased in the late larval and early post-larval stages, in accordance with the role of methyl farnesoate in crustacean metamorphosis. This study exemplifies the applicability of a high-throughput sequencing approach for studying complex traits, including metamorphosis, providing new insight into this unexplored area of crustacean research.

Ventura, Tomer; Manor, Rivka; Aflalo, Eliahu D.; Chalifa-Caspi, Vered; Weil, Simy; Sharabi, Omri; Sagi, Amir

2013-01-01

416

Fishing Effort and Catch Composition of Urban Market and Rural Villages in Brazilian Amazon  

NASA Astrophysics Data System (ADS)

The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions.

Hallwass, Gustavo; Lopes, Priscila Fabiana; Juras, Anastacio Afonso; Silvano, Renato Azevedo Matias

2011-02-01

417

Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing  

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 methane 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 -87) for the mainstem Amazon floodplain in Brazil, the Llanos de Moxos (Beni and Mamore rivers