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1

Toxicity of rotenone to giant river freshwater prawn Macrobrachium rosenbergii  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aquaculturists have often suffered predation losses in the production of freshwater giant river prawn Macrobrachium rosenbergii due to the presence of wild fish species in culture ponds. The piscicide rotenone is widely used to remove undesirable fish species from ponds. Although evidence in the t...

2

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

3

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

4

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. PMID:21359189

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

2011-01-01

5

Backwater effects in the Amazon River basin of Brazil  

Microsoft Academic Search

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

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

1991-01-01

6

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

7

Dietary Studies on the Predatory Fishes of the Norman River Estuary, with Particular Reference to Penaeid Prawns  

Microsoft Academic Search

The predatory fish community and their prey in the Norman Rivere estuary, Gulf of Carpentaria Australia, are compared with the communities of other tropical inshore areas, to investigate patterns of predation in tropical inshore areas particularly in relation to penaeid prawns. Abiotic factors (turbidity, freshwater input) and diversity of habitat types affect the composition of both prey and predator communities,

J. P. Salini; D. T. Brewer; S. J. M. Blaber

1998-01-01

8

Radium and barium in the Amazon River system  

Microsoft Academic Search

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

Willard S. Moore; John M. Edmond

1984-01-01

9

River dynamics and the diversity of Amazon lowland forest  

Microsoft Academic Search

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

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

1986-01-01

10

Backwater effects in the Amazon River basin of Brazil  

NASA Astrophysics Data System (ADS)

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

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

1991-09-01

11

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

12

Hydrodynamic modelling of the Amazon River: Factors of uncertainty  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

13

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

Microsoft Academic Search

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

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

2003-01-01

14

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

PubMed Central

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

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

2014-01-01

15

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

PubMed

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

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

2014-08-01

16

Suspended sediment dynamics in the Amazon River of Peru  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

17

Palaeoreconstruction of the Amazon River freshwater and sediment discharge using sediments recovered at Site 942 on the Amazon Fan  

Microsoft Academic Search

A continuous reconstruction of palaeoclimate has been generated for the last 12 000 14C yr BP, from ODP site 942 (5°45N, 49°6W at a water depth of 3346 m), drilled to the west of the Amazon Fan. Records from the site suggest that during the Younger Dryas, the Amazon Basin was extremely dry, and Amazon River discharge was low. This

M. A. Maslin; E. Durham; S. J. Burns; E. Platzman; P. Grootes; S. E. J. Greig; M.-J. Nadeau; Markus Schleicher; U. Pflaumann; B. Lomax; N. Rimington

2000-01-01

18

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

19

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

20

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

Microsoft Academic Search

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

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

2011-01-01

21

Seasonal variations in methane emission from Amazon River and tributaries  

NASA Astrophysics Data System (ADS)

Inland waters are known as important sources of methane to atmosphere. Methane is produced in anaerobic environments usually found in lake and floodplain bottom sediments, which is the main reason why most of the information regarding methane fluxes come from this environments. However, while floodplains dry during low water season, reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present results of CH4 flux measurements from 4 large tropical rivers within the Amazon basin obtained with floating chambers in 10 sampling sites during low water (between September and November of 2011) and high water seasons (May, 2012). Sampling sites were located in three main tributaries of Amazon Rivers, Madeira, Xingu and Tapajós, and in the Amazon River mainstem. In the Madeira River high water fluxes ranged from 2.85 to 30.99 mmol m-2 yr-1 while during low water from 77.47 to 183.31 mmol m-2 yr-1. Fluxes for the Amazon and Tapajós were, respectively, 110.99 and 80.01 mmol m-2 yr-1 for the high water season and 169.71 and 193.18 mmol m-2 yr-1 for low water. In the Xingu River two sites had higher fluxes during low water, 314.90 and 571.49 mmol m-2 yr-1 (91.93 and 51.11 mmol m-2 yr-1 in the high water respectively). The two other sites had an opposite pattern with 296.56 and 60.80 mmol m-2 yr-1 in the low water and 846.95 and 360.93 mmol m-2 yr-1 during high water; one site showed equal fluxes for both seasons. Most of the fluxes were higher during low water, with the exception of the three sites at the Xingu River, where fluxes during high water were higher or equal than in low water. These results show a different pattern than described before for these riverine systems, in which higher methane fluxes during high water were expected due to inputs from surrounding anoxic floodplain environments. Instead, our data shows that methane in rivers can be produced within river channels. Lower fluxes during high water could be related to deeper water columns exerting higher pressures and also to increased methane oxidation in the water column.

Sawakuchi, H. O.; Krusche, A. V.; Ballester, M. V.; Sawakuchi, A. O.; Richey, J. E.

2012-12-01

22

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

23

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

24

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

PubMed Central

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

2014-01-01

25

Feeding and larval growth of an exotic freshwater prawn Macrobrachium equidens (Decapoda: Palaemonidae), from Northeastern Pará, Amazon Region.  

PubMed

In the present study, we carried out experiments on the diet of the freshwater prawn Macrobrachium equidens. We tested which type of food and which density of food is suitable for larval development. For the experiment on the type of food, eight treatments were carried out: (I) starvation, (AL) microalgae, (RO) rotifers, (AN) Artemia, (RO + AN) rotifers + Artemia, (AL + RO) microalgae + rotifers, (AL + AN) microalgae + Artemia, (AL + RO + AN) microalgae + rotifers + Artemia. For the experiment on the density of food, we used the type of food, which had resulted in a high survival rate in the previous experiment. Three treatments were carried out: 4, 8 and 16 Artemia nauplii /mL. The rate of feeding during larval development was observed. The survival, weight and percentage of juveniles of each feeding experiment were determined. We found that larvae are carnivores; however, they have requirements with respect to the type of food, because larvae completed their cycle from the zoeal to the juvenile stage only when Artemia nauplii were available. We also verified that the larvae feed mainly during the day-time, and are opportunistic with respect to the density of food offered. PMID:25119734

Gomes, Jean N; Abrunhosa, Fernando A; Costa, Anne K; Maciel, Cristiana R

2014-09-01

26

Iron cycling in the Amazon River Basin: the isotopic perspective  

NASA Astrophysics Data System (ADS)

With the global climate change and increasing anthropic pressure on nature, it is important to find new indicators of the response of complex systems like the Amazon River Basin. In particular, new tracers like iron isotopes may tell us much on processes such as the chemical exchanges between rivers, soils and the biosphere. Pioneering studies revealed that for some river waters, large ?57Fe fractionations are observed between the suspended and dissolved load (Bergquist and Boyle, 2006), and isotopic variations were also recognized on the suspended matter along the hydrological cycle (Ingri et al., 2006). On land, soil studies from various locations have shown that ?57Fe signatures depend mostly on the weathering regime (Fantle and DePaolo, 2004; Emmanuel et al., 2005; Wiederhold et al., 2007; Poitrasson et al., 2008). It thus seems that Fe isotopes could become an interesting new tracer of the exchanges between soils, rivers and the biosphere. We therefore conducted Fe isotope surveys through multidisciplinary field missions on rivers from the Amazon Basin. It was confirmed that acidic, organic-rich black waters show strong Fe isotope fractionation between particulate and dissolved loads. Furthermore, this isotopic fractionation varies along the hydrological cycle, like previously uncovered in boreal waters suspended matter. In contrast, unfiltered waters show very little variation with time. It was also found that Fe isotopes remain a conservative tracer even in the case of massive iron loss during the mixing of chemically contrasted waters such as the Negro and Solimões tributaries of the Amazon River. Given that >95% of the Fe from the Amazon River is carried as detrital materials, our results lead to the conclusion that the Fe isotope signature delivered to the Atlantic Ocean is undistinguishable from the continental crust value, in contrast to previous inferences. The results indicate that Fe isotopes in rivers represent a promising indicator of the interaction between organic matter and iron in rivers, and ultimately the nature of their source in soils. As such, they may become a powerfull tracer of changes occurring on the continents in response to both weathering context and human activities. References: Bergquist, B.A., Boyle, E.A., 2006. Iron isotopes in the Amazon River system: Weathering and transport signatures. Earth and Planetary Science Letters, 248: 54-68. Emmanuel, S., Erel, Y., Matthews, A., Teutsch, N., 2005. A preliminary mixing model for Fe isotopes in soils. Chemical Geology, 222: 23-34. Fantle, M.S., DePaolo, D.J., 2004. Iron isotopic fractionation during continental weathering. Earth and Planetary Science Letters, 228: 547-562. Ingri, J., Malinovsky, D., Rodushkin, I., Baxter, D.C., Widerlund, A., Andersson, P., Gustafsson, O., Forsling, W., Ohlander, B., 2006. Iron isotope fractionation in river colloidal matter. Earth and Planetary Science Letters, 245: 792-798. Poitrasson, F., Viers, J., Martin, F., Braun, J.J., 2008. Limited iron isotope variations in recent lateritic soils from Nsimi, Cameroon: Implications for the global Fe geochemical cycle. Chemical Geology, 253: 54-63. Wiederhold, J.G., Teutsch, N., Kraemer, S.M., Halliday, A.N., Kretzchmar, R., 2007. Iron isotope fractionation in oxic soils by mineral weathering and podzolization. Geochimica et Cosmochimica Acta, 71: 5821-5833.

Poitrasson, Franck; Vieira, Lucieth; Mulholland, Daniel; Seyler, Patrick; Sondag, Francis; Allard, Thierry

2014-05-01

27

Daily water level by ENVISAT altimetry of the Amazon River  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

28

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

E-print Network

% of the discharge and sediment planet contribution from the continents to the oceans, according to the world values and Meade, 1983). Most of the sediment discharged (95%) to the Atlantic Ocean by the Amazon River comes from1 Sediment budget of the Napo River, Amazon basin, Ecuador and Peru A., Laraque1 , C., Bernal2 , J

Paris-Sud XI, Université de

29

Amazon River carbon dioxide outgassing fuelled by wetlands  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

30

Amazon River carbon dioxide outgassing fuelled by wetlands.  

PubMed

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

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

2014-01-16

31

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

32

Viruses and bacteria in floodplain lakes along a major Amazon tributary respond to distance to the Amazon River  

PubMed Central

In response to the massive volume of water along the Amazon River, the Amazon tributaries have their water backed up by 100s of kilometers upstream their mouth. This backwater effect is part of the complex hydrodynamics of Amazonian surface waters, which in turn drives the variation in concentrations of organic matter and nutrients, and also regulates planktonic communities such as viruses and bacteria. Viruses and bacteria are commonly tightly coupled to each other, and their ecological role in aquatic food webs has been increasingly recognized. Here, we surveyed viral and bacterial abundances (BAs) in 26 floodplain lakes along the Trombetas River, the largest clear-water tributary of the Amazon River’s north margin. We correlated viral and BAs with temperature, pH, dissolved inorganic carbon, dissolved organic carbon (DOC), phosphorus, nitrogen, turbidity, water transparency, partial pressure of carbon dioxide (pCO2), phytoplankton abundance, and distance from the lake mouth until the confluence of the Trombetas with the Amazon River. We hypothesized that both bacterial and viral abundances (VAs) would change along a latitudinal gradient, as the backwater effect becomes more intense with increased proximity to the Amazon River; different flood duration and intensity among lakes and waters with contrasting sources would cause spatial variation. Our measurements were performed during the low water period, when floodplain lakes are in their most lake-like conditions. Viral and BAs, DOC, pCO2, and water transparency increased as distance to the Amazon River increased. Most viruses were bacteriophages, as viruses were strongly linked to bacteria, but not to phytoplankton. We suggest that BAs increase in response to DOC quantity and possibly quality, consequently leading to increased VAs. Our results highlight that hydrodynamics plays a key role in the regulation of planktonic viral and bacterial communities in Amazonian floodplain lakes. PMID:25788895

Almeida, Rafael M.; Roland, Fábio; Cardoso, Simone J.; Farjalla, Vinícius F.; Bozelli, Reinaldo L.; Barros, Nathan O.

2015-01-01

33

Effect of thermal acclimation on organ mass, tissue respiration, and allometry in Leichhardtian river prawns Macrobrachium tolmerum (Riek, 1951).  

PubMed

Changes to an animal's abiotic environment-and consequent changes in the allometry of metabolic rate in the whole animal and its constituent parts-has considerable potential to reveal important patterns in both intraspecific and interindividual variation of metabolic rates. This study demonstrates that, after 6 wk of thermal acclimation at replicate treatments of 16°, 21°, and 25°C, standard metabolic rate (SMR) scales allometrically in Leichhardtian river prawns Macrobrachium tolmerum ([Formula: see text]) and that the scaling exponent and normalization constant of the relationship between SMR and body mass is not significantly different among acclimation treatments when measured at 21°C. There is, however, significant variation among individuals in whole-animal metabolic rate. We hypothesized that these observations may arise because of changes in the metabolic rate and allometry of metabolic rate or mass of organ tissues within the animal. To investigate this hypothesis, rates of oxygen consumption in a range of tissues (gills, gonads, hepatopancreas, chelae muscle, tail muscle) were measured at 21°C and related to the body mass (M) and whole-animal SMR of individual prawns. We demonstrate that thermal acclimation had no effect on organ and tissue mass, that most organ and tissue (gills, gonads, hepatopancreas) respiration rates do not change with acclimation temperature, and that residual variation in the allometry of M. tolmerum SMR is not explained by differences in organ and tissue mass and respiration rates. These results suggest that body size and ambient temperature may independently affect metabolic rate in this species. Both chelae and tail muscle, however, exhibited a reduction in respiration rate in animals acclimated to 25° relative to those acclimated to 16° and 21°C. This reduction in respiration rates of muscle at higher temperatures is evidence of a tissue-specific acclimation response that was not detectable at the whole-animal level. PMID:23799841

Crispin, Taryn S; White, Craig R

2013-01-01

34

Transcriptome Analysis of the Oriental River Prawn, Macrobrachium nipponense Using 454 Pyrosequencing for Discovery of Genes and Markers  

PubMed Central

Background The oriental river prawn, Macrobrachium nipponense, is an economically and nutritionally important species of the Palaemonidae family of decapod crustaceans. To date, the sequencing of its whole genome is unavailable as a non-model organism. Transcriptomic information is also scarce for this species. In this study, we performed de novo transcriptome sequencing to produce the first comprehensive expressed sequence tag (EST) dataset for M. nipponense using high-throughput sequencing technologies. Methodology and Principal Findings Total RNA was isolated from eyestalk, gill, heart, ovary, testis, hepatopancreas, muscle, and embryos at the cleavage, gastrula, nauplius and zoea stages. Equal quantities of RNA from each tissue and stage were pooled to construct a cDNA library. Using 454 pyrosequencing technology, we generated a total of 984,204 high quality reads (338.59Mb) with an average length of 344 bp. Clustering and assembly of these reads produced a non-redundant set of 81,411 unique sequences, comprising 42,551 contigs and 38,860 singletons. All of the unique sequences were involved in the molecular function (30,425), cellular component (44,112) and biological process (67,679) categories by GO analysis. Potential genes and their functions were predicted by KEGG pathway mapping and COG analysis. Based on our sequence analysis and published literature, many putative genes involved in sex determination, including DMRT1, FTZ-F1, FOXL2, FEM1 and other potentially important candidate genes, were identified for the first time in this prawn. Furthermore, 6,689 SSRs and 18,107 high-confidence SNPs were identified in this EST dataset. Conclusions The transcriptome provides an invaluable new data for a functional genomics resource and future biological research in M. nipponense. The molecular markers identified in this study will provide a material basis for future genetic linkage and quantitative trait loci analyses, and will be essential for accelerating aquaculture breeding programs with this species. PMID:22745820

Ma, Keyi; Qiu, Gaofeng; Feng, Jianbin; Li, Jiale

2012-01-01

35

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

PubMed

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

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

2014-06-01

36

Viruses and bacteria in floodplain lakes along a major Amazon tributary respond to distance to the Amazon River.  

PubMed

In response to the massive volume of water along the Amazon River, the Amazon tributaries have their water backed up by 100s of kilometers upstream their mouth. This backwater effect is part of the complex hydrodynamics of Amazonian surface waters, which in turn drives the variation in concentrations of organic matter and nutrients, and also regulates planktonic communities such as viruses and bacteria. Viruses and bacteria are commonly tightly coupled to each other, and their ecological role in aquatic food webs has been increasingly recognized. Here, we surveyed viral and bacterial abundances (BAs) in 26 floodplain lakes along the Trombetas River, the largest clear-water tributary of the Amazon River's north margin. We correlated viral and BAs with temperature, pH, dissolved inorganic carbon, dissolved organic carbon (DOC), phosphorus, nitrogen, turbidity, water transparency, partial pressure of carbon dioxide (pCO2), phytoplankton abundance, and distance from the lake mouth until the confluence of the Trombetas with the Amazon River. We hypothesized that both bacterial and viral abundances (VAs) would change along a latitudinal gradient, as the backwater effect becomes more intense with increased proximity to the Amazon River; different flood duration and intensity among lakes and waters with contrasting sources would cause spatial variation. Our measurements were performed during the low water period, when floodplain lakes are in their most lake-like conditions. Viral and BAs, DOC, pCO2, and water transparency increased as distance to the Amazon River increased. Most viruses were bacteriophages, as viruses were strongly linked to bacteria, but not to phytoplankton. We suggest that BAs increase in response to DOC quantity and possibly quality, consequently leading to increased VAs. Our results highlight that hydrodynamics plays a key role in the regulation of planktonic viral and bacterial communities in Amazonian floodplain lakes. PMID:25788895

Almeida, Rafael M; Roland, Fábio; Cardoso, Simone J; Farjalla, Vinícius F; Bozelli, Reinaldo L; Barros, Nathan O

2015-01-01

37

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

38

Microspatial gene expression patterns in the Amazon River Plume  

PubMed Central

We investigated expression of genes mediating elemental cycling at the microspatial scale in the ocean’s largest river plume using, to our knowledge, the first fully quantitative inventory of genes and transcripts. The bacterial and archaeal communities associated with a phytoplankton bloom in Amazon River Plume waters at the outer continental shelf in June 2010 harbored ?1.0 × 1013 genes and 4.7 × 1011 transcripts per liter that mapped to several thousand microbial genomes. Genomes from free-living cells were more abundant than those from particle-associated cells, and they generated more transcripts per liter for carbon fixation, heterotrophy, nitrogen and phosphorus uptake, and iron acquisition, although they had lower expression ratios (transcripts?gene?1) overall. Genomes from particle-associated cells contributed more transcripts for sulfur cycling, aromatic compound degradation, and the synthesis of biologically essential vitamins, with an overall twofold up-regulation of expression compared with free-living cells. Quantitatively, gene regulation differences were more important than genome abundance differences in explaining why microenvironment transcriptomes differed. Taxa contributing genomes to both free-living and particle-associated communities had up to 65% of their expressed genes regulated differently between the two, quantifying the extent of transcriptional plasticity in marine microbes in situ. In response to patchiness in carbon, nutrients, and light at the micrometer scale, Amazon Plume microbes regulated the expression of genes relevant to biogeochemical processes at the ecosystem scale. PMID:25024226

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

2014-01-01

39

Microspatial gene expression patterns in the Amazon River Plume.  

PubMed

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

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

2014-07-29

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

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

42

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

USGS Publications Warehouse

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

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

2000-01-01

43

Biogeochemistry of the Amazon River Basin: the role of aquatic ecosystems in the Amazon functioning  

NASA Astrophysics Data System (ADS)

In this study we present the results of an integrated analysis of physical and anthropogenic controls of river biogeochemistry in Amazônia. At the meso-scale level, our results show that both soil properties and land use are the main drivers of river biogeochemistry and metabolism, with pasture cover and soil exchange cation capacity explaining 99% (p < 0.01) of the variability observed in surface water ions and nutrients concentrations. In small rivers, forest clearing can increase cations, P and C inputs. P and light are the main PPL limiting factors in forested streams, while in pasture streams N becomes limiting. P export to streams may increase or remain nearly undetectable after forest-to-pasture conversion, depending on soil type. Pasture streams on Oxisols have very low P export, while on Ultisols P export is increased. Conversions of forest to pasture leads to extensive growth of in channel Paspalum resulting in higher DOC concentrations and respiration rates. Pasture streams have higher DOC fluxes when compared to the forest ones. In pasture areas the soil are compacted, there is less infiltration and higher surface run off, leaching soil superficial layers and caring more DOC to the streams. In forest areas infiltration is deeper into the soils and canopy interaction is higher. Mineralogy and soil properties are key factors determining exports of nutrients to streams. Therefore, land use change effects on nutrient export from terrestrial to aquatic ecosystems and the atmosphere must be understood within the context of varying soil properties across the Amazon Basin.

Victoria, R. L.; Ballester, V. R.; Krushe, A. V.; Richey, J. E.; Aufdenkampe, A. K.; Kavaguishi, N. L.; Gomes, B. M.; Victoria, D. D.; Montebello, A. A.; Niell, C.; Deegan, L.

2004-12-01

44

Estimating Water Slope in Amazon River Tributaries Using the Shuttle Radar Topography Mission Digital Elevation Model  

Microsoft Academic Search

Extracting river height from the Shuttle Radar Topography Mission digital elevation model (SRTM DEM) for four Amazon River tributaries found water surface elevation standard deviations of 6.16 m for the Madeira River, 7.47 m for the Purus River, 5.28 m for the Negro River, and 5.35 m for the Branco River. Standard deviations and slopes were found for the Madeira,

J. Hamski; G. Lefavour; D. Alsdorf; T. Pavelsky

2006-01-01

45

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 (...

46

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 (...

47

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

48

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

PubMed

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

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

2011-12-29

49

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

50

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

Microsoft Academic Search

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

Laura Lorenzoni

2012-01-01

51

Freshwater fishes of the Amazon River basin: their biodiversity, fisheries, and habitats  

Microsoft Academic Search

Stretching more than seven million square kilometers, the Amazon River basin is the largest river basin in the world and discharges about one-sixth of all freshwater from the continents to the oceans of the world. The age of this ecosystem, its position near the equator and the enormous diversity of its aquatic habitats, have produced the most diverse fish fauna

Wolfgang J. Junk; Maria Gercilia Mota Soares; Peter B. Bayley

2007-01-01

52

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

Microsoft Academic Search

We compare the compositions of dissolved, fine and coarse particulate organic matter fractions (DOM, FPOM and CPOM respectively) from 31 river sites in Bolivia and Peru with 18 sites along the Amazon mainstem. The diversity of sites - ranging from wet and dry Andean headwater environments, to depositional foreland reaches, to major lowland rivers - allows us to assess the

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

2005-01-01

53

Molecular cytogenetic characterization of the Amazon River dolphin Inia geoffrensis.  

PubMed

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

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

2012-09-01

54

Water resources, salinity and salt yields of the rivers of the Bolivian Amazon  

NASA Astrophysics Data System (ADS)

This is the first time that the water resources, the salinity and the yields of the upper basins of the Madera River have been reported. Formed by the confluence of the Beni and Mamore, the Madera is one of the world's largest rivers: 17,000 m 3s -1, approximately half the discharge of the Congo River. It has a dissolved discharge close to that of the Congo River: 1 ts -1 of ions. Likewise, the Beni and the Mamore Rivers, are also classified as large rivers, greater than the Volga River, the largest in Europe, and the Niger River, the second largest in Africa. The amounts of water involved are considerable. The average dissolved content of these rivers, 57-61 mg l -1 respectively, is relatively low to medium. Many types of water, classified according to their ionic compositions, have been characterized in the Andes, the Amazon Plain, and in the main drainage axis. The slightly mineralized black water of the plain seems the most unique type. Recycling of water vapor in the Amazon Basin is confirmed by the low chloride and sodium contents of the water in the plain. Thus the importance of this phenomenon in the genesis of rainfall throughout the basin is emphasized. The contribution of the Upper Madera River to the Amazon River is 9.7% of the water and 10.9% of ionic load.

Roche, Michel-Alain; Jauregui, Carlos Fernandez

1988-06-01

55

Variations of Amazon River channel flow observed by satellite gravity data  

NASA Astrophysics Data System (ADS)

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

Eom, J.; Seo, K.

2013-12-01

56

Sediment supply as a driver of river meandering and floodplain evolution in the Amazon Basin  

NASA Astrophysics Data System (ADS)

The role of externally imposed sediment supplies on the evolution of meandering rivers and their floodplains is poorly understood, despite analytical advances in our physical understanding of river meandering. The Amazon river basin hosts tributaries that are largely unaffected by engineering controls and hold a range of sediment loads, allowing us to explore the influence that sediment supply has on river evolution. Here we calculate average annual rates of meander migration within 20 reaches in the Amazon Basin from Landsat imagery spanning 1985-2013. We find that rivers with high sediment loads experience annual migration rates that are higher than those of rivers with lower sediment loads. Meander cutoff also occurs more frequently along rivers with higher sediment loads. Differences in meander migration and cutoff rates between the study reaches are not explained by differences in channel slope or river discharge. Because faster meander migration and higher cutoff rates lead to increased sediment-storage space in the resulting oxbows, we suggest that sediment supply modulates the reshaping of floodplain environments by meandering rivers. We conclude that imposed sediment loads influence planform changes in lowland rivers across the Amazon.

Constantine, José Antonio; Dunne, Thomas; Ahmed, Joshua; Legleiter, Carl; Lazarus, Eli D.

2014-12-01

57

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

58

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

59

Sediment budget in the Ucayali River basin, an Andean tributary of the Amazon River  

NASA Astrophysics Data System (ADS)

Formation of mountain ranges results from complex coupling between lithospheric deformation, mechanisms linked to subduction and surface processes: weathering, erosion, and climate. Today, erosion of the eastern Andean cordillera and sub-Andean foothills supplies over 99% of the sediment load passing through the Amazon Basin. Denudation rates in the upper Ucayali basin are rapid, favoured by a marked seasonality in this region and extreme precipitation cells above sedimentary strata, uplifted during Neogene times by a still active sub-Andean tectonic thrust. Around 40% of those sediments are trapped in the Ucayali retro-foreland basin system. Recent advances in remote sensing for Amazonian large rivers now allow us to complete the ground hydrological data. In this work, we propose a first estimation of the erosion and sedimentation budget of the Ucayali River catchment, based on spatial and conventional HYBAM Observatory network.

Santini, W.; Martinez, J.-M.; Espinoza-Villar, R.; Cochonneau, G.; Vauchel, P.; Moquet, J.-S.; Baby, P.; Espinoza, J.-C.; Lavado, W.; Carranza, J.; Guyot, J.-L.

2015-03-01

60

Dynamics of Dissolved Organic Matter in Amazon Basin: Insights into Negro River Contribution  

NASA Astrophysics Data System (ADS)

The study of global carbon cycle requires a precise knowledge of spatial and temporal distributions and exportation from continents to oceans. Organic carbon fluxes represent approximately half of the total carbon budget carried by rivers. Tropical rivers transport two third of the total organic carbon discharged into the world oceans but important gaps still exist in the knowledge of the tropical river carbon biochemistry. The Amazon River is responsible for 10% of the annual amount of organic carbon transported from rivers to oceans. The most important portion of total organic matter transported in the Amazon Basin is the dissolved fraction (between 80% and 95%). Amazonian annual flux of dissolved organic matter is directly related to hydrological variations. All rivers in the Amazon basin are characterized by monomodal hydrograms, with a low water period in october/november and a high water period in may/june. Temporal variations in Amazon dissolved organic carbon (3.0 to 9.1 mg l^{- 1}) are mainly controled by Negro River inputs. DOC and DON contributions from the Negro River can vary between 120 kgC s-1 and 520 kg C s-1, and between 5 kgN s--1 and 15 kgN s-1, during low and high water period, respectivelly. In the Negro River, during high water stages, while DOC concentrations are stable from the upstream stations to the downstream ones (about 11 mg l-1), discharge increases from 16000 to 46000 m3 s-1 and NOD can quintuple from upstream (0.071 mg l-1) to downstream (0.341 mg l-1). Then the nature of dissolved organic matter is variable (C/N ratio varied from 33 to 120 from upstream to downstream). During low water stages DOC concentrations are lower (mean DOC of 8.1 mg l-1) while DON is in the same range, discharge is about 10000 m3 s-1 at downstream stations of Negro River and the C/N ratio is lower and steadier along the River. Finaly, despite a low basin surface (12%) compared with the two other main Amazon tributaries, Solimões and Madeira Rivers, and a mean annual water input to Amazonas of 15%, the Negro River contributes with about 38% of the total organic dissolved carbon transported by the Amazon River.

Moreira-Turcq, P.; Perez, M. P.; Benedetti, M.; Oliveira, M. A.; Lagane, C.; Seyler, P.; Oliveira, E.

2006-12-01

61

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

62

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

63

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

64

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

65

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

66

Molecular identification of evolutionarily significant units in the Amazon River dolphin Inia sp. (Cetacea: Iniidae).  

PubMed

The Amazon river dolphin, genus Inia, is endemic to the major river basins of northern South America. No previous studies have focused on the genetic structure of this genus. In this work, 96 DNA samples from specimens of this genus were collected in the Orinoco basin (four rivers), the Putumayo River, a tributary of the Colombian Amazon and the Mamoré, and the Tijamuchí and Ipurupuru rivers in theBolivian Amazon. These samples were used to amplify a fragment of 400 bp of the mitochondrial DNA (mtDNA) control region. In addition, 38 of these samples were also used to sequence 600 bp of the mitochondrial cytochrome b gene. The analysis of the population structure subdivision with an analysis of molecular variance (AMOVA) revealed important aspects about the genetic structure of Inia groups fromthese three geographically separate regions. By comparing the control region DNA and cytochrome b sequences, distinct types of nonshared haplotypes were observed. The net genetic divergence of control region sequences was 6.53% between the Orinoco and Bolivian rivers, 5.32% between the Putumayo and Bolivian rivers, and 2.50% between the Orinoco and Putumayo rivers. For the cytochrome b gene, these values were 2.48%, 2.98%, and 0.06%, respectively. The nucleotide sequences were analyzed phylogenetically using several genetic distance matrices and applying neighbor-joining, maximum likelihood, and maximum parsimony procedures. The results support the proposal to subdivide the Inia genus into at least two evolutionarily significant units: one confined to the Bolivian river basin and the other widely distributed across the Amazon and Orinoco basins. PMID:12547919

Banguera-Hinestroza, E; Cárdenas, H; Ruiz-García, M; Marmontel, M; Gaitán, E; Vázquez, R; García-Vallejo, F

2002-01-01

67

Mercury accumulation in sediment and fish from rivers affected by alluvial gold mining in the Brazilian Madeira River basin, Amazon  

Microsoft Academic Search

The degree and distribution of mercury (Hg) accumulation in sediment and fish from a tributary affected by alluvial small-scale gold mining in the Madeira River\\/Amazon is studied, in relation to a reference site. The results obtained so far agree well with previous studies and confirm that a tremendous contamination of main food web compartments occurs in these highly exposed, but

Rudolf Reuther

1994-01-01

68

Increase in suspended sediment discharge of the Amazon River assessed by monitoring network and satellite data  

Microsoft Academic Search

This study addresses the quantification of the Amazon River sediment budget which has been assessed by looking at data from a suspended sediment discharge monitoring network and remote sensing estimates derived from MODIS spaceborne sensor. Surface suspended sediment concentration has been sampled every 10 days since 1995 (390 samples available) by the international HYBAM program at the Óbidos station which happens

J. M. Martinez; J. L. Guyot; N. Filizola; F. Sondag

2009-01-01

69

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

Microsoft Academic Search

An equal-width-increment procedure was developed to measure water discharge and the suspended sediment load of the Amazon River and its principal tributaries. A variable speed hydraulic winch deploys an instrument array of a sounding weight, Price current meter, and collapsible bag sampler by lowering it from the surface to the bottom and back at a constant velocity. Eighteen verticals are

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

1986-01-01

70

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

Microsoft Academic Search

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

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

2008-01-01

71

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

72

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

73

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

74

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

E-print Network

reserved. Keywords: Amazon; Mercury; Cycling; Soil; Water 1. Introduction Mercury contamination. Mercury contamination in remote areas has already been reported in the literature. In most cases, it has 2000 00 00 z /Is the Negro River Basin Amazon impacted by naturally occurring mercury? P.S. Fadinia

Jardim, Wilson de Figueiredo

75

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

Microsoft Academic Search

The purpose of this paper is to forecast the role of riverine wetlands in the transfer of trace elements. One of the largest riverine wetlands in the world is the floodplain (várzea) of the Amazon River and its tributaries (Junk and Piedade, 1997). The central Amazon wetlands are constituted by a complex network of lakes and floodplains, named várzeas, that

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

2005-01-01

76

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

E-print Network

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

McClain, Michael

77

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

79

Amazon River water in the northeastern Caribbean Sea and its effect on larval reef fish assemblages during April 2009  

E-print Network

Amazon River water in the northeastern Caribbean Sea and its effect on larval reef fish assemblages.S.A. ABSTRACT During April to June 2009, a large bolus of Amazon River water impacted the northeastern Caribbean.90 � 0.06 mL L�1 ) in a 20- to 30-m thick surface layer in the riverine plume. The water was ~1°C war

80

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

NASA Astrophysics Data System (ADS)

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 (March 1990), maximum (May 1990), falling (August 1989), and minimum (November 1991) discharge show the Amazon Plume is typically 3 to 10 m thick and 80 to over 200 km wide. Northwest of the river mouth, the plume is often characterized by a wedge of low-salinity water adjacent to the coast and a separate tongue of low-salinity water extending offshore over the middle to outer shelf. A bottom front separating the low-salinity plume water from oceanic water is consistently located between the 10- and 20-m isobaths. A moored array deployed about 300 km northwest of the river mouth from February to June 1990 included inner and midshelf moorings in 18 and 65 m of water on which temperature-conductivity measurements were made. The moored observations reveal salinity variations within the Amazon Plume of over 10 psu on timescales of days to weeks. This variability includes intermittent events in which plume water pools up in the vicinity of the river mouth and the plume width can exceed 200 km. These accumulation events are apparently due to wind events with a southeastward component which impede or block the normally northwestward freshwater transport. The resulting bulges in the plume are then released northwestward when the wind reverses. Volume budgets indicate the Amazon Plume entrains roughly twice the river discharge between the river mouth at the equator and 3°N. Estimates of gradient Richardson numbers from the moorings suggest entrainment, due to the strong semidiurnal tidal currents, occurs where the plume intersects the bottom and over the outer portion of the plume, where salinities approach oceanic values.

Lentz, Steven J.; Limeburner, Richard

1995-02-01

81

Biogeochemistry of the Amazon River Basin: the role of aquatic ecosystems in the Amazon functioning  

Microsoft Academic Search

In this study we present the results of an integrated analysis of physical and anthropogenic controls of river biogeochemistry in Amazônia. At the meso-scale level, our results show that both soil properties and land use are the main drivers of river biogeochemistry and metabolism, with pasture cover and soil exchange cation capacity explaining 99% (p < 0.01) of the variability

R. L. Victoria; V. R. Ballester; A. V. Krushe; J. E. Richey; A. K. Aufdenkampe; N. L. Kavaguishi; B. M. Gomes; D. D. Victoria; A. A. Montebello; C. Niell; L. Deegan

2004-01-01

82

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

NASA Astrophysics Data System (ADS)

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

Sacek, Victor

2014-09-01

83

Rivers in the sea - Can we quantify pigments in the Amazon and the Orinoco River plumes from space?  

NASA Technical Reports Server (NTRS)

Coastal Zone Color Scanner (CZCS) images of the western tropical Atlantic (1979-1982) were combined into monthly mean surface pigment fields. These suggest that Amazon River water flows along northeastern South America directly toward the Caribbean sea early in the year. After June, however, the North Brazil Current is shunted eastward, carrying a large fraction of Amazon water into the North Equatorial Countercurrent (NECC). This eastward flow causes diminished flow through the Caribbean, which permits northwestward dispersal of Orinoco River water due to local Ekman forcing. The Orinoco plume crosses the Caribbean, leading to seasonal variation in surface salinity near Puerto Rico. At least 50 percent of the pigment concentration estimated in these plumes seems due to viable phytoplankton.

Muller-Karger, Frank E.; Walsh, John J.; Carder, Kendall L.; Zika, Rod G.

1989-01-01

84

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

85

Selenium and mercury concentrations in some fish species of the Madeira River, Amazon Basin, Brazil  

Microsoft Academic Search

Samples of 7 species of piscivorous, omnivorous, and herbivorous fish caught at 12 different sites on the Madeira River, Amazon\\u000a Basin, were analyzed for selenium and mercury. Selenium was determined by anodic stripping voltammetry and mercury by cold\\u000a vapor atomic absorption spectrophotometry. The means for selenium concentrations ranged from 0.49 to 3.11 nmol\\/g and for mercury\\u000a from 0.41 to 6.66

Jose G. Dorea; Marilene B. Moreira; Gaston East; Antonio C. Barbosa

1998-01-01

86

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

NASA Technical Reports Server (NTRS)

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 1700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 mg CH4/sq m per day and were significantly lower than similar emissions determined previously for the high-water period, 184 mg CH4/sq m per day (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 emission from eight lakes located in the central Amazon basis showed similar results. 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, which indicates the importance of the area in global atmospheric chemistry.

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

1990-01-01

87

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

NASA Astrophysics Data System (ADS)

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 1700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 mg CH4/sq m per day and were significantly lower than similar emissions determined previously for the high-water period, 184 mg CH4/sq m per day (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 emission from eight lakes located in the central Amazon basis showed similar results. 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, which indicates the importance of the area in global atmospheric chemistry.

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

1990-09-01

88

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

NASA Astrophysics Data System (ADS)

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

Sacek, Victor

2014-05-01

89

Provenance fidelity: an example from the Amazon River  

NASA Astrophysics Data System (ADS)

Many techniques exist for establishing sediment source links, estimating relative transport distances, and understanding syn-sedimentation weathering conditions. Provenance studies generally fall into three categories: petrographic, geochemical, and isotopic, and depending on study goals and sediment grain-size, analysis can be carried out on bulk-sediment, sample separates, or single-mineral grains. Because of the wide variety of techniques employed, and the response of each indicator element or mineral to weathering and transport, provenance results can vary widely within the same sediment. New bulk-sand Nd-isotopic and detrital zircon data from the same samples and a compilation of published data for active sediment collected across the Amazon Basin highlight the discrepancies in provenance data derived from different proxies. Additionally, data suggest that a more holistic understanding of drainage basin architecture is possible when several techniques are used to explore sediment parentage. The Amazon is an excellent modern laboratory to evaluate provenance techniques. In the headwaters, the high-relief Andes are the dominant sediment source contributing uniquely young, isotopically primitive volcanic arc sediment to the system. Downstream, the low-relief Amazon craton contributes old, isotopically evolved sediment from highly weathered crystalline sources. The 6,500 km+ length of the system allows for mixing and for weathering and transport processes to impart their signals on sediment. In general, suspended sediment mineralogy, single grain ages for K-bearing sand sized minerals, and bulk- sediment isotopic ratios independent of grain size, best identify the dominant sediment contributing area of the basin. Bulk-sediment major and trace element geochemistry and detrital zircon grain ages best describe the geologic diversity of the basin although results cannot be used to estimate source proportions or relief relations. Major element geochemical indices for fine-grained sediments (CIA and ICV) and SiO2 content for sands, best describe the dominantly chemical weathering regime of the drainage. Finally, results gathered using silt and clay-sized sediments tend to best describe source rocks and weathering conditions whereas results collected from sand-sized sediment better describe basin-wide weathering conditions.

Mapes, R. W.; Coleman, D. S.; Nagy, L. A.

2008-12-01

90

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

91

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

92

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

PubMed Central

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

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

2012-01-01

93

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

PubMed

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

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

2012-01-01

94

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

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

E-print Network

basins (figure 2). Wallace astutely linked the sediment load of white-water tributaries to erosion at the transport of volcanic pumice in the main-stem Ama- zon River and correctly assigned its origin to volcanic source of sediments and solutes to the lower reaches of the Amazon River.The most visible characteristics

McClain, Michael

97

Spatial and Temporal Patterns of Diversity and Distribution of the Upper Juruá River Fish Community (Brazilian Amazon)  

Microsoft Academic Search

We studied spatial and temporal patterns in fish species composition and diversity at the upper Juruá River located in the west Brazilian Amazon. We collected with gillnet 822 fishes belonging to 90 species in the main Juruá River, its tributaries and the floodplain lakes during wet and dry seasons. Fish abundance and species richness were greater in the dry season.

Renato A. M. Silvano; Benedito D. do Amaral; Osvaldo T. Oyakawa

2000-01-01

98

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

99

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

Microsoft Academic Search

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

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

2008-01-01

100

Dynamics of sediment transport in large tropical tidal rivers via observations in the Mekong and Amazon  

NASA Astrophysics Data System (ADS)

Of the ten largest-discharge river systems worldwide, freshwater delivery to the ocean from tropical rivers comprises approximately 72% of the total. Tropical-river suspended-sediment loads make up about 45% of the total among the same ten largest rivers. In this context, flow and sediment dynamics of tropical river systems are crucial to a comprehensive understanding of global river budgets. The processes by which sediment is eroded, transported, trapped, and ultimately exported from tidal rivers--where tides propagate but oceanic salinity is absent or only ephemerally present--are poorly understood, even though previous research suggests up to one-third of riverine sediment loads may be trapped within tidal rivers. In an effort to better understand these processes, we present and contrast results from several campaigns along two large tropical tidal rivers: the Mekong and Amazon. Under conditions of high and low seasonal discharge, three cross-sections within the Mekong tidal river were each occupied for a 25-hour tidal cycle, during which ADCP and CTD transects were completed every 15-30 minutes. In this transitional environment between fluvial and estuarine conditions, flow reversed throughout the water column during both low and high flow at all locations, and a strongly sheared flow was present during lesser flood tides. Salinity was spatially variable over seasons: during low flow, salinity in excess of 10 PSU was observed 30 km upstream during maximum flood, while at the same location during high flow, salinity was less than 0.5 PSU at all times. Conditions were partially stratified during low flow. When present, stratification was in the form of a salt wedge during high flow. Suspended sediment was well mixed or exhibited a Rouse-like profile in fresh regions; suspended-sediment concentration within the salt wedge was generally less, except during periods of strong near-bottom flow within the salt-wedge water mass. During both seasons and at all locations, distinct, preferential pathways of water and sediment within the cross-sections were present through the tidal cycles, which may foster development of the rapidly prograding islands within the tidal river. Data collected from seasonal cruises along the geographically vast Amazon tidal river provide context for more spatially constrained studies on the Mekong tidal river and highlight the contrasts between these two large tropical river systems. Ongoing work in these two systems provides a basis for improved understanding of sediment-transport processes within the tidal reach and ultimate quantity, timing, and character of sediment delivered to the ocean.

Nowacki, D. J.; Ogston, A. S.; Nittrouer, C. A.; Fricke, A. T.; Van, P.; Souza Filho, P. W.; Silva, M. S.

2013-12-01

101

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

Microsoft Academic Search

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

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

2009-01-01

102

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

103

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

104

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

NASA Astrophysics Data System (ADS)

Methane flux data obtained during a period of high and falling water level in the course of the dry season of 1985 (the Amazon Boundary Layer Experiment, ABLE 2A) and a period of moderate and rising water during the wet season of 1987 (ABLE 2B) were used to characterize the influence of seasonal variations in the vegetation, water column depth, and chemistry, as well as atmospheric dynamics, on the methane flux from the Amazon River floodplain. It was found that the annual estimate of methane from wetlands is identical to the annual estimate made by Matthews and Fung (1987) (both at 111 Tg). However, it was found that peatlands between 50 and 70 N contribute 39 Tg, with the large areas of forested and nonforested bogs making up 37 Tg of this figure, while the figures of Matthews and Fung were 63 and 62 Tg, respectively.

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

1990-09-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

106

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

107

Estimating Water Slope in Amazon River Tributaries Using the Shuttle Radar Topography Mission Digital Elevation Model  

NASA Astrophysics Data System (ADS)

Extracting river height from the Shuttle Radar Topography Mission digital elevation model (SRTM DEM) for four Amazon River tributaries found water surface elevation standard deviations of 6.16 m for the Madeira River, 7.47 m for the Purus River, 5.28 m for the Negro River, and 5.35 m for the Branco River. Standard deviations and slopes were found for the Madeira, Purus, and Branco rivers by fitting a simple, straight line to the SRTM heights with ~1000 km of flow distance. A second order polynomial was used for the Negro River. Resulting water surface slopes are 3.63 cm/km for the Madeira, 2.83 cm/km for the Purus, and 6.95 cm/km for the Branco whereas a range in slope from 7.00 to 2.10 cm/km was found for the Negro. Using a conservative, annual minimum water slope estimate of 2 cm/km for each tributary leads to reach length requirements of 616 km for the Madiera, 747 km for the Purus, 528 km for the Negro, and 535 km for the Branco to clearly delineate slope. The Global Rain Forest Mapping project's synthetic aperture radar mosaics (GRFM SAR) provide river width. Channel width is computed at each GRFM SAR pixel along a center line obtained by thresholding the Laplacian of an image containing the distance from each channel pixel to the nearest bank pixel. For the Purus River a depth estimate of 15 m and a Manning's n of 0.03 are assumed in calculating river flow velocities using Manning's equation. Using the estimated velocity of 1.04 m/s, the calculated Purus River discharge is 8500 m3/s. state.edu/water/

Hamski, J.; Lefavour, G.; Alsdorf, D.; Pavelsky, T.

2006-12-01

108

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

PubMed

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

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

2013-05-01

109

Molecular cloning of two tropomyosin family genes and expression analysis during development in oriental river prawn, Macrobrachium nipponense.  

PubMed

This paper reports that Slow-tonic S2 tropomyosin (Sst) and Slow tropomyosin isoform (Sti) was highly expressed in androgenic gland transcriptome of Macrobrachium nipponense, which may play crucial roles in sexual differentiation to maleness. In this study, two Sst and Sti gene homologues designated as Mnsst and Mnsti were cloned and characterized from a freshwater prawn M. nipponense. The full-length cDNA of Mnsst and Mnsti consists of 997 bp and 1926 bp, respectively, with an ORF of 852 bp encoding 284 amino acids, and the similarity in ORF reached to 95.82%. The deduced amino acid sequences of Mnsst and Mnsti shared the highest identity with Slow-tonic S2 tropomyosin and Slow tropomyosin isoform of Homarus americanus. Real-time quantitative RT-PCR showed that the Mnsst and Mnsti genes were expressed in different tissues with the highest level of expression in the androgenic gland, implying that these two genes may be related to sex-determination in M. nipponense. Real-time quantitative RT-PCR revealed that in addition, Mnsst and Mnsti were speculated to be related with embryonic organogenesis of M. nipponense, especially for the formation of complete mouthpart and digestive organ and stimulating larval changes of morphology and initiate metamorphosis, the results of present study implied that the two genes may play complex and important roles in sex differentiation of M. nipponense. Thus, we isolated two candidate genes that may advance the studies of sex-determination mechanism in M. nipponense and even the whole crustacean species, as well as promoting the all-male population culture of M. nipponense. PMID:24809964

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

2014-08-10

110

Modern Environmental Changes on Amapa Coastal Plain under Amazon River Influence  

NASA Astrophysics Data System (ADS)

The Amazonian coastal environment is very dynamic compared to other coasts. It is situated at the edge of the Earth's largest forest, and is segmented by fluvial systems, with the biggest being the Amazon River. The rivers are particularly influenced by the Intertropical Convergence Zone (ITCZ), which controls the water and particle discharge, and the flooding regime. Moderate and strong El Nino conditions correlate with low-precipitation periods, and La Nina events cause precipitation to increase. These variables and others related to the Amazon dispersal system create an interesting area for the study of global and regional environmental changes. The Araguari River floodplain on the Amapa coast is influenced by natural processes of global scale such as ENSO events and ITCZ, and by local processes such as Amazon River discharge, tides and tidal bore (pororoca). Anthropogenic processes such as extensive water-buffalo farming also promote environmental changes. Time- series analyses of remote sensing images and suspended sediment have shown that the maximum turbidity zone inside Araguari River is related to the pororoca phenomenon. The pororoca remobilizes sediment from the river bottom and margins, developing sediment suspension >15 g/l as it passes - creating fluid muds. The pororoca also introduces Amazon- and shelf-derived sediment into the Araguari estuary. Measurements during eight spring-tide cycles indicate erosion of 3 cm of consolidated mud and deposition of 1 cm. The pororoca also influences the remobilization and cycling of nutrients and consequently affects the distribution of benthic organisms, including benthonic foraminifera and thecamoebians. For more than a century, the coastal plain has had water-buffalo farming (>42,000 animals today), which modifies the drainage system and affects sedimentary processes. Areas with more buffalo trails have higher suspended-sediment concentration (SSC) during the dry season and lower SSC during the rainy season. This relationship is reversed in drainages without the influence of the herd. The development of small channels, one meter deep by one meter wide, induced by the buffalos can evolve into a large drainage network in a short period of time. The Santana Creek started as a buffalo trail and in three decades it evolved into a network with a main channel 200 m wide and 6 km long. Despite the Amazon River having the largest influence in the region, the Araguari River also has a considerable water discharge of 2.4x103 m3/s and particulate discharge of 7x105 tons/y, and is able to impose changes to the Amapa coastal environments and inner shelf. The natural closure of the Araguari north arm during middle of the 19th century has induced the development of a wide coastal plain in the Cape Norte region, and decreased fresh water to the Carapaporis channel. On the other hand, deforestation for farm development and buffalo farming has influenced the hydrologic regime, sediment and nutrient balance.

Santos, V. F.; Figueiredo, A. G.; Silveira, O. M.; Polidori, L.

2007-05-01

111

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

PubMed

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 aimed to compare mercury concentrations in these environmental samples with those reported by other authors during the gold rush of the Madeira River Basin. Today, in the Madeira River the releases of mercury register a sudden reduction due the gold price fall in the international trade. However, about 100 t of Hg were released to the atmosphere and to aquatic systems in the region during the gold rush. The present survey shows that notwithstanding the reduction of Hg emissions to the Madeira River Basin from gold mining proper, concentrations in fish and humans are similar to those measured during the gold rush. Reduction in Hg concentrations is restricted to areas close to old point sources and only for abiotic compartments (air and sediments). Remobilization of Hg from bottom sediments plus re-emission from soils due to land use changes are probably responsible for keeping high Hg concentrations in biological samples. PMID:16242177

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

2006-09-01

112

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

113

Molecular characterization and developmental expression of vitellogenin in the oriental river prawn Macrobrachium nipponense and the effects of RNA interference and eyestalk ablation on ovarian maturation.  

PubMed

Vitellogenin (Vg) is the precursor of yolk protein, which functions as a nutritive resource that is important for embryonic growth and gonad development. In this study, the cDNA encoding the Vg gene from the oriental river prawn Macrobrachium nipponense was cloned using expressed sequence tag (EST) analysis and the rapid amplification of cDNA ends (RACE) approach. The transcript encoded 2536 amino acids with an estimated molecular mass of 286.810kDa. Quantitative real-time PCR indicated high expression of Mn-Vg in the female ovary, hemocytes, and hepatopancreas. As ovaries developed, the expression level of Mn-Vg increased in both the hepatopancreas and ovary. In the hepatopancreas, the expression level rose more slowly at the early stage of vitellogenesis and reached the peak more rapidly compared to the expression pattern in ovary. The observed changes in Mn-Vg expression level at different development stages suggest the role of nutrient source in embryonic and larval development. Eyestalk ablation caused the Mn-Vg expression level to increase significantly compared to eyestalk-intact groups during the ovary development stages. Ablation accelerated ovary maturation by removing hormone inhibition of Mn-Vg in the hepatopancreas and ovary. In adult females, Mn-Vg dsRNA injection resulted in decreased expression of Mn-Vg in both the hepatopancreas and ovary, and two injection treatment dramatically delayed ovary maturation. Vg RNA interference down-regulated the vitellogenin receptor (VgR) expression level in the ovary, which illustrates the close relationship between Vg and VgR in the process of vitellogenesis. PMID:25499697

Bai, Hongkun; Qiao, Hui; Li, Fajun; Fu, Hongtuo; Sun, Shengming; Zhang, Wenyi; Jin, Shubo; Gong, Yongsheng; Jiang, Sufei; Xiong, Yiwei

2015-05-10

114

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

115

OSL dating of sediments from Negro and Solimões rivers - Amazon, Brazil  

NASA Astrophysics Data System (ADS)

In this work, the OSL dating results of Quaternary fluvial deposits from the confluence of Negro and Solimões rivers were studied. The equivalent doses (De) of sediments were obtained using a Single Aliquot Regeneration (SAR) protocol. Statistic studies were made using frequency histogram, weighted histogram and Radial plot in order to analyze the De fluctuations. Ages from 74.5 to 205 thousand of years (Pleistocene) were recorded. The gamma-ray spectroscopy was used to evaluate the natural radioisotopes concentrations of the samples and low concentrations were found with values between 0.64 and 3.71 ppm for 235U and 238U; 2.01-9.77 ppm for 232Th; already, for 40K, the concentration was negligible. The OSL dating of sediments has contributed to a better understanding of the evolution of Negro and Solimões rivers, in Amazon, Brazil.

Fiore, M.; Soares, E. A. A.; Mittani, J. C. R.; Yee, M.; Tatumi, S. H.

2014-02-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

117

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

PubMed

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

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

2011-01-01

118

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

NASA Astrophysics Data System (ADS)

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

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

2000-12-01

119

Role of CO2 outgas from small rivers in local and regional net carbon emission in the southwestern Amazon River Basin  

NASA Astrophysics Data System (ADS)

A recent estimate of CO2 outgassing from Amazonian wetlands suggests that an order of magnitude more CO2 leaves rivers through gas exchange than is exported to the ocean as organic or inorganic carbon. However, the contribution of smaller rivers, is still poorly understood, mainly due to limitations in mapping their exact extent. Considering that the largest portion of the Amazon River network is composed of small rivers, our objective was to elucidate their role in air-water CO2 exchange, combining estimated CO2 and a GIS-based methodology to calculate the surface area covered by rivers with channels less than 100 meters wide in the Ji- Paraná River Basin, Western Amazon. The estimated CO2 outgas was the main carbon export pathway for this river basin, totalizing 316 Gg C yr-1, about 2.8 times the amount of carbon exported as dissolved inorganic carbon (113 Gg C yr-1 and 1.8 times dissolved organic carbon (176 Gg C yr-1. The relationships established here between drainage area and channel width provide a new model for determining surface area of these rivers, thus making it possible to perform regional extrapolations of air-water gas exchange. Extrapolated CO2 outgas from Ji-Paraná rivers lower than 100 meters wide from small rivers to the entire Amazon basin, totalizes124.8 ± 42 Tg C yr-1, about 71 Tg yr-1 higher than previous results. These ecosystems are playing an important role in the regional carbon balance, contributing with 17% (low water) to 38% (high water) of the total Amazon basin CO2 outgassing.

Ballester, V. M.; Rasera, M. F.; Krusche, A. V.; Salimon, C. I.; Montebelo, L. A.; Alin, S.; Victoria, R. L.; Richey, J. E.

2006-12-01

120

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

121

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

122

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

123

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

PubMed Central

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

Lafferty, Kevin D.; Kuris, Armand M.

2014-01-01

124

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

PubMed

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

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

2014-04-01

125

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

PubMed

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

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

2005-03-01

126

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

127

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

128

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

129

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

130

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

131

Multisensor observations of the Amazon-Orinoco river plume interactions with hurricanes  

NASA Astrophysics Data System (ADS)

An analysis is presented for the spatial and intensity distributions of North Atlantic extreme atmospheric events crossing the buoyant Amazon-Orinoco freshwater plume. The sea surface cooling amplitude in the wake of an ensemble of storm tracks traveling in that region is estimated from satellite products for the period 1998-2012. For the most intense storms, cooling is systematically reduced by ˜50% over the plume area compared to surroundings open-ocean waters. Historical salinity and temperature observations from in situ profiles indicate that salt-driven vertical stratification, enhanced oceanic heat content, and barrier-layer presence within the plume waters are likely key oceanic factors to explain these results. Satellite SMOS surface salinity data combined with in situ observations are further used to detail the oceanic response to category 4 hurricane Igor in 2010. Argo and satellite measurements confirm the haline stratification impact on the cooling inhibition as the hurricane crossed the river plume. Over this region, the SSS mapping capability is further tested and demonstrated to monitor the horizontal distribution of the vertical stratification parameter. SMOS SSS data can thus be used to consistently anticipate the cooling inhibition in the wake of TCs traveling over the Amazon-Orinoco plume region.

Reul, Nicolas; Quilfen, Yves; Chapron, Bertrand; Fournier, Severine; Kudryavtsev, Vladimir; Sabia, Roberto

2014-12-01

132

[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

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

2013-08-01

133

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

PubMed Central

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

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

2013-01-01

134

Revealing forms of iron in river-borne material from major tropical rivers of the Amazon Basin (Brazil)  

NASA Astrophysics Data System (ADS)

The present study deals with the direct determination of colloidal forms of iron in river-borne solids from main rivers of the Amazon Basin. The contribution of different forms of colloidal iron have been assessed using ultrafiltration associated with various techniques including electron paramagnetic resonance spectroscopy (EPR), high resolution transmission electron microscopy (HRTEM), and micro proton-induced X ray emission analysis (?PIXE). EPR shows the presence of Fe 3+ bound to organic matter (Fe 3+-OM) and colloidal iron oxides. Quantitative estimate of Fe 3+-OM content in colloidal matter ranges from 0.1 to 1.6 weight % of dried solids and decreases as the pH of the river increases in the range 4 to 6.8. The modeling of the field data with the Equilibrium Calculation of Speciation and Transport (ECOSAT) code demonstrates that this trend is indicative of a geochemical control resulting from the solubility equilibrium of Fe oxyhydroxide phase and Fe binding to organic matter. Combining EPR and ?PIXE data quantitatively confirms the presence of colloidal iron phase (min. 35 to 65% of iron content), assuming no divalent Fe is present. In the Rio Negro, HRTEM specifies the nature of colloidal iron phase mainly as ferrihydrite particles of circa 20 to 50 Å associated with organic matter. The geochemical forms of colloidal iron differentiate the pedoclimatic regions drained by the different rivers, corresponding to different major weathering/erosion processes. Modeling allows the calculation of the speciation of iron as mineral, organic and dissolved phases in the studied rivers.

Allard, T.; Menguy, N.; Salomon, J.; Calligaro, T.; Weber, T.; Calas, G.; Benedetti, M. F.

2004-07-01

135

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

136

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

137

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

138

Seasonal and provenance controls on Nd–Sr isotopic compositions of Amazon rivers suspended sediments and implications for Nd and Sr fluxes exported to the Atlantic Ocean  

Microsoft Academic Search

This study reports daily water discharge and suspended sediment load concentrations and Sm–Nd and Rb–Sr isotopic systematics and major and trace elements concentrations of twelve monthly sampled suspended load sediments of the Solimões and Madeira rivers, the two major Andean tributaries of the Amazon, during the year 2004.As observed in other long-term monitoring studies of Amazon Rivers, the maximum of

Jérôme Viers; Martin Roddaz; Naziano Filizola; Jean-Loup Guyot; Francis Sondag; Pierre Brunet; Cyril Zouiten; Carole Boucayrand; François Martin; Géraldo Resende Boaventura

2008-01-01

139

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

E-print Network

and the Madeira Rivers (from in situ and MODIS Satellite Data) Mangiarotti a,* S., Martinez b,c J.-M., Bonnet b are considered during the period 2000­2008 in a region including the full Amazon River from the confluence of the Negro River to Santarém, the end part of the Solimões River, and the lower part of the Madeira River

140

Seasonal variability in concentration, composition, age, and fluxes of particulate organic carbon exchanged between the floodplain and Amazon River  

NASA Astrophysics Data System (ADS)

The composition, sources, and age of particulate organic matter were determined in an Amazonian river-floodplain system during rising, high, falling, and low water periods over 7 yr (1999-2006), and a mass balance for total organic carbon (dissolved and particulate) was estimated. The Curuai floodplain, composed of several temporally interconnected lakes, is permanently connected to the Amazon River via channels. Organic matter (OM) is imported to the floodplain from the Amazon River mainly during the rising water period and produced in the floodplain and exported to the river during high and falling water periods. No significant exchanges occurred during low water periods. The OM produced in the floodplain is characterized by low C/N ratios and by high chlorophyll a concentrations (Chl-a). The ?13C signature has a seasonal trend, with more negative ?13C values during the high water period than other periods. ?14C results indicate that the bulk OM present in floodplain lakes is predominantly post-bomb (i.e., post-1950). Particulate organic carbon (POC) and dissolved organic carbon (DOC) fluxes exported by the Curuai floodplain represent 1.3% and 0.1%, respectively, of the POC and DOC annual fluxes in the mainstem Amazon River at Óbidos but may reach up to 3.3% and 0.8% during falling water. Based on ?14C, ?13C, Chl-a, and elemental analysis of the particulate organic matter, we demonstrate that floodplain lakes have intense phytoplankton and macrophyte primary production, which is partly exported to the main river channel. Floodplains are thus a significant source of modern and labile organic carbon to the river mainstem, where it can be rapidly degraded and recycled back to the atmosphere.

Moreira-Turcq, Patricia; Bonnet, Marie-Paule; Amorim, Marcelo; Bernardes, Marcelo; Lagane, Christelle; Maurice, Laurence; Perez, Marcela; Seyler, Patrick

2013-01-01

141

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

142

Selenium and mercury concentrations in some fish species of the Madeira River, Amazon Basin, Brazil.  

PubMed

Samples of 7 species of piscivorous, omnivorous, and herbivorous fish caught at 12 different sites on the Madeira River, Amazon Basin, were analyzed for selenium and mercury. Selenium was determined by anodic stripping voltammetry and mercury by cold vapor atomic absorption spectrophotometry. The means for selenium concentrations ranged from 0.49 to 3.11 nmol/g and for mercury from 0.41 to 6.66 nmol/g depending on the fish species. The molar ratios of Hg:Se increased according to the fish trophic level. Piscivorous species had the highest mean ratio (4.0) and herbivorous species the lowest (0.9). There was a positive and statistically significant correlation between selenium and mercury concentrations for the herbivorous species (r = 0.716; p = 0.0088) not seen for omnivororus and piscivorous species (r = -0.2032; p = 0.3407). These findings are significant for the fish-eating population of the Madeira River because the ingestion of mercury would always be in excess of selenium. PMID:9892494

Dorea, J G; Moreira, M B; East, G; Barbosa, A C

1998-12-01

143

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

144

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

Microsoft Academic Search

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

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

2010-01-01

145

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

146

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

147

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

Microsoft Academic Search

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

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

1987-01-01

148

Using JERS-1 L-band SAR to estimate methane emissions from the Jau´ river floodplain (Amazon\\/Brazil)  

Microsoft Academic Search

Demonstrates how multi-temporal JERS-1 LHH band SAR data can be used to derive detailed spatial and temporal information about wetland distributions and improve estimates of methane fluxes from these environments. Within the framework of the NASDA-led Global Rain Forest Mapping (GRFM) project, a part of the Jau´ river in the central part of the Amazon basin, was monitored during two

A. Rosenqvist; B. R. Forsberg; T. Pimentel; J. E. Richey

1998-01-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

150

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

PubMed

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

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

2011-01-01

151

Morphology and mitochondrial phylogenetics reveal that the Amazon River separates two eastern squirrel monkey species: Saimiri sciureus and S. collinsi.  

PubMed

Saimiri has a complicated taxonomic history, and there is continuing disagreement about the number of valid taxa. Despite these controversies, one point of consensus among morphologists has been that the eastern Amazonian populations of squirrel monkeys form a single terminal taxon, Saimiri sciureus sciureus (Linnaeus, 1758). This group is distributed to both the north and south of the middle to lower Amazon River and in the Marajó Archipelago. However, a recent molecular study by Lavergne and colleagues suggested that the Saimiri sciureus complex (comprised of S. s. sciureus sensu lato, S. s. albigena, S. s. macrodon, and S. s. cassiquiarensis) was paraphyletic. The discordance between morphological and molecular studies prompted us to conduct a new multidisciplinary analysis, employing a combination of morphological, morphometric, and molecular markers. Our results suggest the currently recognized taxon S. s. sciureus contains two distinct species, recognized by the Phylogenetic Species Concept: Saimiri sciureus (Linnaeus, 1758) and Saimiri collinsi Osgood, 1916. East Amazonian squirrel monkeys north of the Amazon have a gray crown (S. sciureus), and south of the Amazon, the crown is yellow (S. collinsi). Morphometric measurements also clearly distinguish between the two species, with the most important contributing factors including width across upper canines for both sexes. For males, the mean zygomatic breadth was significantly wider in S. sciureus compared to S. collinsi, and for females, the width across the upper molars was wider in S. sciureus compared to S. collinsi. Mitochondrial phylogenetic analyses support this separation of the eastern Amazonian squirrel monkeys into two distinct taxa, recovering one clade (S. sciureus) distributed to the north of the Amazon River, from the Negro River and Branco River to the Guiana coast and the Brazilian state of Amapá, and another clade (S. collinsi) south of the Amazon River, from the region of the Tapajós River to the state of Maranhão, as well as within the Marajó Archipelago. The revalidation of the species S. collinsi was corroborated by all of the methods in the study, as the clades recovered in our molecular study are congruent with the pattern of morphological variation. We confirm both the paraphyly of the Saimiri sciureus complex and the paraphyly of the subspecies S. s. sciureus as defined in the current literature. PMID:25451802

Mercês, Michelle P; Lynch Alfaro, Jessica W; Ferreira, Wallax A S; Harada, Maria L; Silva Júnior, José S

2015-01-01

152

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

2008-08-01

153

DDT AND ITS METABOLITES IN BREAST MILK FROM THE MADEIRA RIVER BASIN IN THE AMAZON, BRAZIL  

PubMed Central

Until the 1990’s the 1,1,1-trichloro-bis-2,2?-(4chlorophenyl) ethane (DDT) was sprayed in the walls of the house in the along the Madeira River basin, Brazilian Amazon, a region well known by its large number of malaria cases. In the 1910, the relate of Oswaldo Cruz about health conditions in Madeira River region describes the presence of malaria in rates ranging until 100% of infected people in some localities. Data available in the literature points to the DDT contamination in fishes captured in Madeira River region. Fish is the major source of dietary protein to this people. DDT tends to accumulate in lipid rich tissues being eliminated by different events, including lactation. Considering the importance of the breast milk to the children feeding, 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 sample 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, was higher than the Acceptable Daily Intake proposed by the WHO. Key words: DDT, breast milk, children, organochlorine pesticide, fish. 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

2008-01-01

154

Characterization of confluences in free meandering rivers of the Amazon basin  

NASA Astrophysics Data System (ADS)

Past studies on river confluence dynamics are mostly based on a limited number of experimental and field data that mainly represent the morphodynamic, hydrodynamic, and sedimentary processes of alluvial river channels with limited planform activity and concentrated solely around the confluence region. The present contribution is novel and focuses on the study of the planimetric configuration of confluences in tropical free meandering rivers located in the upper Amazon catchment. Confluences are environmental controls that impose convective instabilities in all the associated channels, namely the main stretch channel upstream of the confluence (M), the tributary (T), and the main post-confluent channel (MT). By performing a wavelet analysis on channels' curvature, we quantify the extent of the transitional region. Our results indicate that the strength of these transitional instabilities are in some degree dependent on the confluence width ratio (?); such that for ? > 0.45, marked instabilities are developed. These instabilities induce the following general changes and in the planimetric configurations of the aforementioned channels: [i] the arc-wavelength in the confluent (M and T) and post-confluence channels increase in the transitional region, and [ii] the peaks on the curvature of MT channel decrease with respect to the M channel, thus resembling a constructive effect in the superposition of the meander trains. Although most of the confluence angles are acute, regardless the width-ratio, some instances of obtuse angles of confluence are observed. They are associated with ? ? 0.80, where possibly the confluence is forced to become accordant. Our results show that no evident cause-effect relationship is found between the angle of confluence and the length of the transitional region; however, some degree of dependence is seen between the confluence angle and the arc-wavelength of the post-confluence channel (i.e., higher values of the arc-wavelength corresponds to normal confluence angles).

Gutierrez, Ronald R.; Abad, Jorge D.; Choi, Marianne; Montoro, Hugo

2014-09-01

155

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

156

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

157

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

158

Mercury accumulation in sediment and fish from rivers affected by alluvial gold mining in the Brazilian Madeira River basin, Amazon.  

PubMed

The degree and distribution of mercury (Hg) accumulation in sediment and fish from a tributary affected by alluvial small-scale gold mining in the Madeira River/Amazon is studied, in relation to a reference site. The results obtained so far agree well with previous studies and confirm that a tremendous contamination of main food web compartments occurs in these highly exposed, but vulnerable tropical waters. An essential part of the released metallic Hg may still exist as macroscopic liquid Hg drops in the sediment. Both global (0.4 mg/kg of Hg) and local (0.1 mg/kg of Hg) background sediment values as well as safety levels for fish (0.5 mg/kg of Hg) are considerably exceeded by a factor of up to 25, 100, and 4, respectively, and give rise to serious concern, not least with regard to the formation of the very toxic monomethyl-Hg. It is further discussed that atmospheric transport and deposition of Hg in water reservoirs built for hydroelectric power generation may act as critical pathways for longterm Hg accumulation, even in unexposed riverine systems. PMID:24214137

Reuther, R

1994-09-01

159

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

160

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

161

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

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

162

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

NASA Technical Reports Server (NTRS)

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

Bosilovich, Michael G.; Chern, Jiun-Dar

2005-01-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

164

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

PubMed

The Upper Solimões river region, western Amazon, is the homeland of indigenous populations and contains small-scale agricultural systems that are important for biodiversity conservation. Although traditional slash-and-burn agriculture is being practiced over many years, deforestation there is relatively small compared to other Amazon regions. Pastures are restricted to the vicinity of cities and do not spread to the small communities along the river. Inceptisols are the main soil order (>90%) in the area and have unique attributes including high Al content and high cation exchange capacity (CEC) due to the enrichment of the clay fraction with 2:1 secondary aluminosilicates. Despite its importance, few studies have focussed on this soil order when considering land use effects on the fertility of Amazon soils. Thus, the objective of this study was to evaluate changes in soil fertility of representative land use systems (LUSs) in the Upper Solimões region, namely: primary rainforest, old secondary forest, young secondary forest, agroforestry, pasture and agriculture. LUSs were significantly differentiated by the chemical attributes of their topsoil (0-20 cm). Secondary forests presented soil chemical attributes more similar to primary rainforest areas, while pastures exhibited the highest dissimilarity from all the other LUSs. As a whole, soil chemical changes among Inceptisols dominated LUSs showed patterns that were distinct from those reported from other Amazon soils like Oxisols and Ultisols. This is probably related to the presence of high-activity clays enriched in exchangeable aluminum that heavily influenced the soil chemical reactions over the expected importance of organic matter found in most studies conducted over Oxisol and Ultisol. PMID:19853281

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

2009-12-20

165

Provenance of sands from the confluence of the Amazon and Madeira rivers based on detrital heavy minerals and luminescence of quartz and feldspar  

NASA Astrophysics Data System (ADS)

Source-to-sink systems are poorly known in tropical rivers. For the Amazonian rivers, the majority of the provenance studies remain focused on the suspended load, implying a poor understanding of the processes governing production and distribution of sands. In this study, we perform heavy mineral and optically stimulated luminescence (OSL) analysis to cover the entire spectrum (heavy and light minerals fraction) of 29 sand samples of the Lower Madeira river region (Amazon and Madeira rivers), of which the main goal was to find provenance indicators specific to these rivers. Despite the tropical humid climate, the sands of the Amazon and Lower Madeira rivers are rich in unstable heavy minerals as augite, hypersthene, green hornblende and andalusite. The Madeira river is highlighted by its higher content of andalusite, with source attributed to the Amazon Craton (medium-to-high grade metamorphic rocks), while the Amazon river, upstream of the Madeira river mouth, has a signature of augite and hypersthene, that suggests an Andean provenance (volcanic rocks). Sands from the Madeira river can be tracked in the Amazon river by the increasing concentration in andalusite. OSL analysis of the light minerals fraction was used as an index of feldspar concentration and sedimentary history of quartz grains. Lower feldspar concentration and quartz grains with longer sedimentary history (higher OSL sensitivity) also point to a major contribution of cratonic sources for the sands in the Madeira river. While the sands from the Lower Madeira would be mainly supplied by cratonic rocks, previous work recognised that suspended sediments (silt and clay) are derived from Andean rocks. Therefore, we interpret a decoupling between the sources of sand and mud (silt and clay) under transport in the Madeira river. Andean sands (rich in augite and hypersthene) would be trapped in the foreland zones of the Beni and Mamoré tributaries. In the Amazon river sands, the low OSL sensitivity of the quartz, higher content of feldspar and unstable heavy mineral assemblage dominated by augite and hypersthene suggest both a fast transport from Andean sources with fine sediment bypass over foreland areas.

do Nascimento, Daniel R.; Sawakuchi, André O.; Guedes, Carlos C. F.; Giannini, Paulo C. F.; Grohmann, Carlos H.; Ferreira, Manuela P.

2015-03-01

166

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

PubMed Central

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

2014-01-01

167

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

PubMed

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

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

2013-01-01

168

Potamotrygon limai, sp. nov., a new species of freshwater stingray from the upper Madeira River system, Amazon basin (Chondrichthyes: Potamotrygonidae).  

PubMed

Potamotrygon limai, sp. nov., is described from the Jamari River, upper Madeira River system (Amazon basin), state of Rondônia, Brazil. This new species differs from congeners by presenting unique polygonal or concentric patterns formed by small whitish spots better defined over the posterior disc and tail-base regions. Potamotrygon limai, sp. nov., can be further distinguished from congeners in the same basin by other characters in combination, such as two to three rows of midtail spines converging to a single irregular row at level of caudal sting origin, proportions of head, tail and disc, patterns of dermal denticles on rostral, cranial and tail regions, among other features discussed herein. Potamotrygon limai, sp. nov., is most similar to, and occurs sympatrically with, P. scobina, and is distinguished from it by lacking ocellated spots on disc, by its characteristic polygonal pattern on posterior disc, a comparatively much shorter and broader tail, greater intensity of denticles on disc, more midtail spine rows at tail-base, and other features including size at maturity and meristic characters. Potamotrygon limai, sp. nov., is also distinguished from other species of Potamotrygon occurring in the Amazon region, except P. scobina, by presenting three angular cartilages (vs. two or one). This new species was discovered during a detailed taxonomic and morphological revision of the closely related species P. scobina, and highlights the necessity for thorough and all-embracing taxonomic studies, particularly in groups with pronounced endemism and morphological variability. PMID:24870898

Fontenelle, João Pedro; Da Silva, João Paulo C B; De Carvalho, Marcelo R

2014-01-01

169

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

170

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

171

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

PubMed

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

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

2013-01-01

172

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

PubMed Central

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

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

2013-01-01

173

Linear Regression Models of Methyl Mercury Exposure during Prenatal and Early Postnatal Life among Riverside People along the Upper Madeira River, Amazon  

Microsoft Academic Search

This research is focused on prenatal and early postnatal mercury (Hg) exposure among the riverside people along the Upper Madeira river in the Amazon. Linear regression models were developed to predict the hair Hg concentration in infants. The independent variables included in the model of Group 1 (87 pairs of mothers and their infants) were the average maternal hair Hg

Ana Amelia Peixoto Boischio; Diane S. Henshel

2000-01-01

174

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

175

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

PubMed

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

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

2014-08-01

176

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.

Stuart Snodgrass

2002-03-14

177

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

178

The Influence of Historical and Potential Future Deforestation on the Stream Flow of the Amazon River -- Land Surface Processes and Atmospheric Feedbacks  

NASA Astrophysics Data System (ADS)

Global economic and regional population and development pressures have resulted in high rates of deforestation in the Amazon River basin, mostly in the eastern and southern portion of the basin. Recent deforestation rates reflect the global demand for Brazilian free-range beef and soybeans with about 22,000 km2 deforested each year between 2000 and 2004 and 7000 km2 deforested in the final months of 2007. Land cover and land use changes influence the quantity of surface water resources by changing how incoming precipitation and radiation are partitioned among sensible and latent heat fluxes, runoff, and river discharge and altering regional and continental scale precipitation patterns. Results from coupled land surface and global climate model simulations clarify a few important points about the impact of deforestation on the Amazon River: 1) The local evapotranspiration decrease and subsequent discharge increase can be a significant fraction of the water balance when greater than 50% of a watershed is deforested. 2) The atmospheric feedbacks from large-scale deforestation may be of the same order of magnitude as the changes to local land surface processes, but of opposite sign and are not limited to those basins where deforestation has occurred. 3) Changes to discharge and aquatic environments with future deforestation of the Amazon will likely be a complex function of how much vegetation has been removed from a particular watershed and how much has been removed from the entire Amazon Basin.

Coe, M. T.; Costa, M. H.; Soares-Filho, B.

2008-12-01

179

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

PubMed

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

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

2011-01-01

180

Vertical Accretion of the Rain Forest Floodplains and Levees: the Formation of Rias from Interaction of Black and White River Types in the Amazon River System.  

NASA Astrophysics Data System (ADS)

The Amazon river system is dominated by the presence of rias, that is plaeovalleys paretially filled by sediment and harbouring almost standing bodies of water. Since the seminal work of Harald Sioli, it has been clear the paleovalleys have been formed in rivers (black type) poor in sediment and rich in organic matter during low stand periods of the sea level. Subsequently, the rivers rich in sediment (white type) damming of their mouths by the vertical accretion of the rivers rich in sediments (white type). This pattern is present in other rain forest fluvial systems and a good example is the Murray Lake in Papua New Guinea. These relations show that of the flood plain in tropical rain forest systems is strongly dominated by vertical accretion. This fact is also confirmed by the ubiquitous presence of levees inside channels (e.g. Rio Trombettas). Levees accrete vertically by the addition of single layers of sediment mostly entrapped by vegetation. The formation of permanent crevasse splays is also contributing to the levee accretion. Secondary channels are perched over the floodplain interface and totally bounded by levees. Consequently, the floodplain is dominated by lakes, permanent crevasse splays and levees assembled in vertical stacked bodies. The geological record shows examples of rain forest floodplains with similar facies and stratigraphic patterns..

Ori, G.; Franzinelli, E.

2006-12-01

181

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

182

Elevated mercury concentrations in soils, sediments, water, and fish of the Madeira River basin, Brazilian Amazon: a function of natural enrichments?  

PubMed

Previous site-specific investigations have found that mercury concentrations in water, sediments, and biota of the Brazilian Amazon are elevated above global averages, and that these concentrations are a direct result of widespread mercury amalgamation mining operations conducted by non-organized prospectors. In order to assess the regional impacts of Hg contamination from these non-organized gold mining activities, water, sediments, and fish were systematically collected in 1997 along a 900-km reach of the Madeira River. The sampling program extended from the Amazon River upstream to Porto Velho, the site of historic and ongoing mercury amalgamation mining. Mercury concentrations were found to be elevated above global averages in all sampled media. However, the geochemical data suggest that the high mercury levels are due largely to natural sources and natural biogeochemical processes, and that the impacts of anthropogenically released mercury from mine sites is relatively localized. PMID:11032118

Lechler, P J; Miller, J R; Lacerda, L D; Vinson, D; Bonzongo, J C; Lyons, W B; Warwick, J J

2000-10-01

183

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

184

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

PubMed

Malaria in Brazil is virtually restricted to the Amazon Region, where it has a heterogeneous geographic distribution. We reviewed secondary data in order to describe the regional and temporal distribution of 8018 malaria cases seen between 2003 and 2007 in Santa Isabel do Rio Negro, a municipality in the northwest Brazilian Amazon. A significant rise in malaria incidence, mainly in the Yanomami Indian reservation, was observed during this time. Anopheline breeding sites were also mapped and entomological data were obtained through the capture of larval and adult mosquitoes. Thirty-three potential breeding sites were identified in the urban and periurban areas, 28 of which were positive for anopheline larvae. Anopheles darlingi specimens were captured in both intra- and peridomicile locations in the urban areas. Demographic data were also assessed via a sectional survey, revealing that the majority of dwellings were vulnerable to mosquitoes. This study suggests that urban and periurban areas of this municipality are highly susceptible to epidemic malaria, which is endemic in the Yanomami Indian reservation near the city. In addition, transmission can be perpetuated autochthonously in the urban area, drawing attention to the continuous need for preventative measures such as controlling adult and aquatic stages of mosquitoes and improving housing. PMID:20462621

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

2010-08-01

185

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

186

Dynamics of Dissolved Organic Matter in Amazon Basin: Insights into Negro River Contribution  

Microsoft Academic Search

The study of global carbon cycle requires a precise knowledge of spatial and temporal distributions and exportation from continents to oceans. Organic carbon fluxes represent approximately half of the total carbon budget carried by rivers. Tropical rivers transport two third of the total organic carbon discharged into the world oceans but important gaps still exist in the knowledge of the

P. Moreira-Turcq; M. P. Perez; M. Benedetti; M. A. Oliveira; C. Lagane; P. Seyler; E. Oliveira

2006-01-01

187

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

188

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

PubMed

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

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

2012-06-01

189

Monitoring mercury exposure in reproductive aged women inhabiting the Tapajós river basin, Amazon.  

PubMed

Among Amazonian communities, exposure to methylmercury is associated mainly with fish consumption that may affect fetal development in pregnant women. Therefore a temporal assessment was performed to assess the exposure of reproductive aged women to mercury who reside in the riparian communities of São Luís do Tapajós and Barreiras located in the Tapajós basin of the Brazilian Amazon from 1999 to 2012. The total mercury concentration in the 519 hair samples was assessed by cold vapor atomic absorption spectrometry. Data analysis showed that the average total mercury concentration decreased from 1.066 to 0.743 ?g/g in those years. In 1999 the proportion of volunteers with mercury levels ? 10 ?g/g was approximately 68 %. In general, exposure to mercury decreased among women of reproductive age, but the potential risks to reproduction and human health is still an issue as 22 % of the woman continued showing high mercury levels (? 10 ?g/g) in 2012. PMID:24789525

de Oliveira Corvelo, Tereza Cristina; Oliveira, Érika Abdon Fiquene; de Parijós, Amanda Magno; de Oliveira, Claudia Simone Baltazar; do Socorro Pompeu de Loiola, Rosane; de Araújo, Amélia A; da Costa, Carlos Araújo; de Lima Silveira, Luiz Carlos; da Conceição Nascimento Pinheiro, Maria

2014-07-01

190

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

PubMed

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

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

2012-09-01

191

Dissolved carbon in an urban area of a river in the Brazilian Amazon  

Microsoft Academic Search

The main objective of this study was to evaluate dissolved organic and inorganic carbon dynamics along upstream and downstream\\u000a reaches of the Acre River draining the city of Rio Branco, in the state of Acre, Brazil. Dissolved organic carbon (DOC) concentrations\\u000a in the Acre River were significantly higher during the wet season, ranging from 385 ± 160 to 430 ± 131 ?M among the stations,

Eliete dos Santos Sousa; Cleber Ibraim Salimon; Ricardo de Oliveira Figueiredo; Alex Vladimir Krusche

192

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

193

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

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

194

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

195

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

196

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

197

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

Microsoft Academic Search

This interdisciplinary study investigates a three-step process that could represent a major carbon sink in Amazonian foreland basins. Stated as hypotheses, we propose: 1) extensive Andean hillslope failure and lowland channel migration during large La Nina-associated storms mobilizes vast quantities of sediment with low organic carbon (OC) content and vast quantities of fresh organic matter; 2) within the river, mineral

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

2006-01-01

198

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

199

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

200

Seasonal and provenance controls on Nd Sr isotopic compositions of Amazon rivers suspended sediments and implications for Nd and Sr fluxes exported to the Atlantic Ocean  

NASA Astrophysics Data System (ADS)

This study reports daily water discharge and suspended sediment load concentrations and Sm-Nd and Rb-Sr isotopic systematics and major and trace elements concentrations of twelve monthly sampled suspended load sediments of the Solimões and Madeira rivers, the two major Andean tributaries of the Amazon, during the year 2004. As observed in other long-term monitoring studies of Amazon Rivers, the maximum of suspended sediment load occurs before or during the rising water period (i.e. during the rainy season). In 2004, the Solimões River exported ˜ 289 × 10 6 tonnes of suspended sediments and the Madeira River 294 × 10 6 tonnes which correspond to erosion rates of 129 and 214 T/km 2/yr for the Solimoes and Madeira rivers basins, respectively. Both the Solimoes and Madeira suspended sediments are enriched in LREE over HREE and exhibit similar MREE enrichment; the difference being that the Madeira sediments are more fractionated than the Solimoes ones. When plotted in Al 2O 3-CaO + Na 2O-K 2O diagram, the suspended sediments of the Solimoes and Madeira rivers exhibit two different weathering trends which suggests that these sediments evolved along two different trends starting from felsic rocks with different chemical compositions. The Nd isotopic compositions (?Nd) of the Solimoes sediments (- 8.9 to 9.9) are slightly more radiogenic than the corresponding values of the Madeira sediments (- 10.8 to - 12.1). The 87Sr/ 86Sr isotopic compositions of the Madeira sediments (0.728 to 0.740) are significantly more radiogenic than those of the Solimoes (0.713 to 0.717). Together with other major elements and REE evidences, these isotopic compositions suggest that the Solimoes sediments are more influenced by Andean volcanic arc detritus than the Madeira sediments that might be due to input of young basaltic products owing to strong volcanic activity in Ecuador. Mineralogical compositions as well as Nd isotopic compositions do not vary seasonally. Based on our data set and on previous published studies, we have calculated that the Nd suspended sediment flux dominates the Nd total flux (i.e., dissolved + suspended sediment) exported to the Atlantic Ocean by the Amazon River representing ˜ 98% of the Nd total flux and having a global ?Nd isotopic composition of - 10.3. Contrary to Nd isotopic compositions, Sr isotopic compositions vary seasonally in both rivers. The explanation for this variation remains unclear. We suspect increasing physical weathering during the rainy season to be the main cause of this seasonal control in favouring landslides and river bank erosion that might induce input of more radiogenic sediments not easily mobilized during low water level. We calculated that the Sr isotopic composition of the dissolved load exported by the Amazon River to the Atlantic Ocean is not seasonally dependent and remain fairly constant (0.715-0.716) By contrast, the Sr isotopic composition of the suspended load is strongly affected by the seasonal variation varying from 0.714 in the dry season to 0.730 in the rainy season. Consequently the total Sr isotopic composition (dissolved + suspended sediment) is also seasonally controlled varying from 0.716 to 0.722. We finally suggest that large seasonally controlled Sr isotopic variations of great river is a phenomenon that has been underestimated in previous paleo-climatic and paleo-oceanic studies and should be taken into account in further studies.

Viers, Jérôme; Roddaz, Martin; Filizola, Naziano; Guyot, Jean-Loup; Sondag, Francis; Brunet, Pierre; Zouiten, Cyril; Boucayrand, Carole; Martin, François; Boaventura, Géraldo Resende

2008-10-01

201

Pseudoparasitism by Calodium hepaticum (syn. Capillaria hepatica; Hepaticola hepatica) in the Negro River, Brazilian Amazon.  

PubMed

We report the finding of eggs of Calodium spp. (syn. Capillaria spp.; Hepaticola spp.) in a fecal sample from an old woman living in a riverine community in the Negro River Basin and describe the associated epidemiological investigation. The case probably does not represent true parasitism; the eggs, which were compatible with the species Calodium hepaticum, were most likely ingested upon consumption of infected tapir (Tapirus terrestris) liver, subsequently passing through the gut and being eliminated. The evolution of these eggs to infective stages in the environment, given the poor sanitation background, could provide the risk of occurrence of hepatic disease in humans. PMID:19477475

Carvalho-Costa, Filipe A; Silva, Adriano Gomes; de Souza, Alberto H; Moreira, Carlos J de C; de Souza, Daniela L; Valverde, Joanna G; Jaeger, Lauren H; Martins, Patrícia P; de Meneses, Viviane F; Araújo, Adauto; Bóia, Márcio N

2009-10-01

202

Dams in the Amazon: Belo Monte and Brazil's hydroelectric development of the Xingu River Basin.  

PubMed

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. PMID:16738820

Fearnside, Phillip M

2006-07-01

203

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

204

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

205

Investigation of Deforestation of Environmental Protection Areas of Madeira River Permanent Preservation Areas in Rondônia Amazon, Brazil  

Microsoft Academic Search

The deforestation of the Amazon protected areas involves a series of deleterious environmental factors, such as social conflicts, loss of biodiversity, soil degradation, deterioration of watersheds, and environmental services offered, that still are not considered in studies of environmental impacts and when studied, are not valued economically or end up being undersized, resulting in loss of economic opportunities associated to

Marcelo Rodrigues dos Anjos; Marla Schulz

2011-01-01

206

Wood-fuel biomass from the Madeira River: A sustainable option for electricity production in the Amazon region  

Microsoft Academic Search

The universal provision of electricity remains far from achieved in the Brazilian Amazon, given the geographical obstacles, the dispersion of its inhabitants, the indistinctness of appropriate technologies, and the economic obstacles. Governmental action was taken in 2003 with the creation of the Light for All Program (PLpT), with the goal of bringing electricity to all rural consumers by 2010. In

Atlas Augusto Bacellar; Brígida R. P. Rocha

2010-01-01

207

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

Microsoft Academic Search

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

Jonathan Hoekenga; Cynthia J. Berlin

208

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

PubMed Central

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

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

2011-01-01

209

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

210

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

PubMed

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

Nery, José Reinaldo Cardoso; Bonotto, Daniel Marcos

2011-04-01

211

The Influence of Changes in Lifestyle and Mercury Exposure in Riverine Populations of the Madeira River (Amazon Basin) near a Hydroelectric Project  

PubMed Central

In the Amazon Basin, naturally occurring methylmercury bioaccumulates in fish, which is a key source of protein consumed by riverine populations. The hydroelectric power-plant project at Santo Antônio Falls allows us to compare the Hg exposure of riverine populations sparsely distributed on both sides of the Madeira river before the area is to be flooded. From 2009 to 2011, we concluded a population survey of the area (N = 2,008; representing circa 80% of community residents) that estimated fish consumption and mercury exposure of riverine populations with different degrees of lifestyle related to fish consumption. Fish samples from the Madeira river (N = 1,615) and 110 species were analyzed for Hg. Hair-Hg was significantly lower (p < 0.001) in less isolated communities near to the capital of Porto Velho (median 2.32 ppm) than in subsistence communities in the Cuniã Lake, 180 km from Porto Velho city (median 6.3 ppm). Fish Hg concentrations ranged from 0.01 to 6.06 µg/g, depending on fish size and feeding behavior. Currently available fish in the Madeira river show a wide variability in Hg concentrations. Despite cultural similarities, riparians showed hair-Hg distribution patterns that reflect changes in fish-eating habits driven by subsistence characteristics. PMID:24577285

Hacon, Sandra S.; Dórea, José G.; Fonseca, Márlon de F.; Oliveira, Beatriz A.; Mourão, Dennys S.; Ruiz, Claudia M. V.; Gonçalves, Rodrigo A.; Mariani, Carolina F.; Bastos, Wanderley R.

2014-01-01

212

The influence of changes in lifestyle and mercury exposure in riverine populations of the Madeira River (Amazon Basin) near a hydroelectric project.  

PubMed

In the Amazon Basin, naturally occurring methylmercury bioaccumulates in fish, which is a key source of protein consumed by riverine populations. The hydroelectric power-plant project at Santo Antônio Falls allows us to compare the Hg exposure of riverine populations sparsely distributed on both sides of the Madeira river before the area is to be flooded. From 2009 to 2011, we concluded a population survey of the area (N = 2,008; representing circa 80% of community residents) that estimated fish consumption and mercury exposure of riverine populations with different degrees of lifestyle related to fish consumption. Fish samples from the Madeira river (N = 1,615) and 110 species were analyzed for Hg. Hair-Hg was significantly lower (p < 0.001) in less isolated communities near to the capital of Porto Velho (median 2.32 ppm) than in subsistence communities in the Cuniã Lake, 180 km from Porto Velho city (median 6.3 ppm). Fish Hg concentrations ranged from 0.01 to 6.06 µg/g, depending on fish size and feeding behavior. Currently available fish in the Madeira river show a wide variability in Hg concentrations. Despite cultural similarities, riparians showed hair-Hg distribution patterns that reflect changes in fish-eating habits driven by subsistence characteristics. PMID:24577285

Hacon, Sandra S; Dórea, José G; Fonseca, Márlon de F; Oliveira, Beatriz A; Mourão, Dennys S; Ruiz, Claudia M V; Gonçalves, Rodrigo A; Mariani, Carolina F; Bastos, Wanderley R

2014-03-01

213

Hysterothylacium larvae (Nematoda, Anisakidae) in the freshwater mussel Diplodon suavidicus (Lea, 1856) (Mollusca, Unioniformes, Hyriidae) in Aripuanã River, Amazon, Brazil.  

PubMed

Larvae of Hysterothylacium use various invertebrates as intermediate hosts. Definite hosts include fish, birds, reptiles or marine mammals. This study describes the occurrence of Hysterothylacium (Nematoda, Anisakidae) larvae parasitizing the pericardic cavity of Diplodon suavidicus (Unioniformes, Hyriidae) specimens collected in the Amazon basin, Brazil. This is the first record of this nematode parasitizing freshwater bivalves in South America. The high prevalence, medium intensity and medium abundance suggest that D. suavidicus acts as intermediate host for Hysterothylacium species in that environment. PMID:21145894

Lopes, Luiza P C; Pimpão, Daniel M; Takemoto, Ricardo M; Malta, José C O; Varella, Angela M B

2011-03-01

214

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

215

Rare earth elements in the Amazon basin  

Microsoft Academic Search

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

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

2003-01-01

216

Traditionally configured prawn trawls contain small diamond-  

E-print Network

434 Traditionally configured prawn trawls contain small diamond- shaped meshes in the codend, and small diamond-mesh sections. A strategically located panel of 85-mm netting was inserted on the bar with a conventional diamond-mesh codend (control) showed that both square-mesh designs significantly re- duced

217

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

NASA Astrophysics Data System (ADS)

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

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

1999-06-01

218

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

219

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

220

Morphobiological aspects of Rhodnius brethesi Matta, 1919 (Hemiptera:Reduviidae) from the Upper and Middle Negro River, Amazon region of Brazil: I - scanning electron microscopy.  

PubMed

The occurrence of autochthonous cases of Chagas disease in the Amazon region of Brazil over recent decades has motivated an intensification of studies in this area. Different species of triatomines have been identified, and ten of these have be proven to be carriers of the parasite Trypanosoma cruzi or " cruzi-like " parasites. Studies conducted in the municipalities of Santa Isabel do Rio Negro and Barcelos, located on the Upper and Middle of the Negro River, microregion of Negro River, state of Amazonas have confirmed not only that Rhodnius brethesi is present in the palm tree Leopoldinia piassaba, but also that this insect was recognized by palm fiber collectors. A morphological study of eyes, inter-ocular and inter-ocellar regions, antennae, buccula, labrum, rostrum, stridulatory sulcus and feet, including the apex of the tibia, spongy fossette and ctenidium was conducted by scanning electron microscopy. The buccula and the stridulatory sulcus presented notable differences in specimens of different genera and also of different species. These data make it possible to suggest that the details presented in these structures can be included as diagnostic characteristics to be used in new dichotomous keys, thereby contributing towards studies of taxonomy and systematics and furnishing backing for comparative analysis of specimens collected from different localities. PMID:16444425

Dos Santos-Mallet, Jacenir Reis; Junqueira, Angela Cristina Verissimo; Moreira, Carlos José de Carvalho; Andrade, Zelia; Coura, José Rodrigues; Gonçalves, Teresa Cristina Monte

2005-12-01

221

Mouth of the Amazon  

NASA Technical Reports Server (NTRS)

Flowing over 6450 kilometers eastward across Brazil, the Amazon River originates in the Peruvian Andes as tiny mountain streams that eventually combine to form one of the world's mightiest rivers. This image of the Amazon's mouth was captured by MISR's vertical-viewing (nadir) camera on September 8, 2000 during Terra orbit 3862. The image is approximately 380 kilometers in width.

While the Amazon is surpassed in length by the Nile, it carries the largest volume of freshwater in the world, accounting for nearly 20 percent of the Earth's discharge into the oceans. Millions of cubic feet of water empty into the Atlantic every second, and the effluent is transported to very large distances from shore.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

2001-01-01

222

Ranching in the Brazilian Amazon in a national context: Economics, policy, and practice  

Microsoft Academic Search

The ranching sector is dynamic in the Brazilian Amazon and the approaches and environments used to raise cattle are diverse. Ranching occurs in natural grasslands at the mouth of the Amazon River, floodplains along the Amazon River, and interfluvial (nonflooded) lands where forest has been cut and replaced by pasture. We found that traditional extensive style approaches to ranching are

Eugenio Yatsuda Arima; Christopher Uhl

1997-01-01

223

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

224

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

225

Production of dissolved organic carbon enriched in deoxy sugars representing an additional sink for biological C drawdown in the Amazon River plume  

NASA Astrophysics Data System (ADS)

In North Atlantic waters impacted by discharges from the Amazon and Orinoco Rivers, where planktonic diatom-diazotroph associations (DDA) were active, we observed that an average (± standard deviation) of 61 ± 12% of the biological drawdown of dissolved inorganic carbon (DIC) was partitioned into the accumulating total organic carbon pool, representing a flux of up to 9 ± 4 Tg C yr-1. This drawdown corresponded with chemical alteration of ultrafiltered dissolved organic matter (UDOM), including increases in stable C isotopic composition (?13C) and C:N. The dissolved carbohydrate component of UDOM also increased with biological DIC drawdown and diatom-associated diazotroph (i.e., Richelia) abundance. New carbohydrates could be distinguished by distinctively high relative abundances of deoxy sugars (up to 55% of monosaccharides), which may promote aggregate formation and enhance vertical carbon export. The identified production of non-Redfieldian, C-enriched UDOM thus suggests a mechanism to explain enhanced C sequestration associated with DDA N2 fixation, which may be widespread in mesohaline environments.

Meador, Travis B.; Aluwihare, Lihini I.

2014-10-01

226

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

227

Morphology and phylogeny of Thelohanellus marginatus n. sp. (Myxozoa: Myxosporea), a parasite infecting the gills of the fish Hypophthalmus marginatus (Teleostei: Pimelodidae) in the Amazon River.  

PubMed

Thelohanellus marginatus n. sp., a new myxosporean parasite infecting the primary gill filaments of the teleost fish Hypophthalmus marginatus (Pimelodidae) in the Amazon River, is described on the basis of microscopic and molecular procedures. The parasite forms whitish and ellipsoidal cysts up to 250 ?m in diam. Myxospores ellipsoidal with a slightly more pointed anterior end, measuring 17.1 ± 0.6 ?m in length, 6.9 ± 0.4 ?m in width, and 5.1 ± 0.5 ?m in thickness. A single pyriform polar capsule, 9.0 ± 0.3 ?m long and 6.1 ± 0.4 ?m wide, positioned slightly right to the medial plane in valvular view, contains a polar filament arranged in 4-5 coils. Molecular analysis of the SSU rRNA gene by Maximum Parsimony, Neighbor-Joining, and Maximum Likelihood revealed the parasite clustering among other myxobolids, namely Henneguya and Myxobolus. Host affinity is supported as an important evolutionary signal for the phylogeny of myxobolids. The parasite here described represents the first record of the genus Thelohanellus Kudo, 1933 from the South American fauna. PMID:25039988

Rocha, Sónia; Casal, Graça; Velasco, Michele; Alves, Angela; Matos, Edilson; Al-Quraishy, Saleh; Azevedo, Carlos

2014-01-01

228

The Amazon basin in transition.  

PubMed

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

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

2012-01-19

229

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

2013-11-01

230

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

231

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

Microsoft Academic Search

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

A. K. Aufdenkampe; R. Aalto; L. Maurice-Brougoin

2006-01-01

232

River Boats Contribute to the Regional Spread of the Dengue Vector Aedes aegypti in the Peruvian Amazon  

PubMed Central

Background and Objectives The dramatic range expansion of the dengue vector Aedes aegypti is associated with various anthropogenic transport activities, but little is known about the underlying mechanisms driving this geographic expansion. We longitudinally characterized infestation of different vehicle types (cars, boats, etc.) to estimate the frequency and intensity of mosquito introductions into novel locations (propagule pressure). Methods Exhaustive adult and immature Ae. aegypti collections were performed on six different vehicle types at five ports and two bus/ taxi departure points in the Amazonian city of Iquitos, Peru during 2013. Aquatic vehicles included 32 large and 33 medium-sized barges, 53 water taxis, and 41 speed boats. Terrestrial vehicles sampled included 40 buses and 30 taxis traveling on the only highway in the region. Ae. aegypti adult infestation rates and immature indices were analyzed by vehicle type, location within vehicles, and sampling date. Results Large barges (71.9% infested) and medium barges (39.4% infested) accounted for most of the infestations. Notably, buses had an overall infestation rate of 12.5%. On large barges, the greatest number of Ae. aegypti adults were found in October, whereas most immatures were found in February followed by October. The vast majority of larvae (85.9%) and pupae (76.7%) collected in large barges were produced in puddles formed in cargo holds. Conclusions Because larges barges provide suitable mosquito habitats (due to dark, damp cargo storage spaces and ample oviposition sites), we conclude that they likely serve as significant contributors to mosquitoes’ propagule pressure across long distances throughout the Peruvian Amazon. This information can help anticipate vector population mixing and future range expansions of dengue and other viruses transmitted by Ae. aegypti. PMID:25860352

Guagliardo, Sarah Anne; Morrison, Amy C.; Barboza, Jose Luis; Requena, Edwin; Astete, Helvio; Vazquez-Prokopec, Gonzalo; Kitron, Uriel

2015-01-01

233

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

PubMed

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

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

2014-01-01

234

Linear regression models of methyl mercury exposure during prenatal and early postnatal life among riverside people along the upper Madeira river, Amazon.  

PubMed

This research is focused on prenatal and early postnatal mercury (Hg) exposure among the riverside people along the Upper Madeira river in the Amazon. Linear regression models were developed to predict the hair Hg concentration in infants. The independent variables included in the model of Group 1 (87 pairs of mothers and their infants) were the average maternal hair Hg concentration and maternal age. Group 2 (31 pairs) included maternal segmental hair Hg concentrations. For the segmental hair Hg analysis over time, it was assumed that hair grows at a rate of 11 cm per month. Thus, information on the timing of the dates of pregnancy and breast feeding from the birth history was used to cut the hair strands into segments, making them correspond to the mother's reproductive stage of life (31 pairs of mothers and their infants). Breast milk Hg concentration results were included with segmental and average maternal hair Hg concentration values (22 and 44 pairs of mothers and their infants, respectively). The models including the breast milk Hg concentration indicated that 61 and 55% of the variability of the infant hair Hg concentrations were due to the independent variables: segmental maternal hair Hg with breast milk Hg and average maternal hair Hg with breast milk Hg, respectively. The regression coefficients were in the range of 0.19 to 0.90, and P values were in the range of 0.0001 to 0.1490. Further recommendations include fish advisories to prevent critical Hg exposures during reproductive life and investigation of neurobehavioral performance of this study population. PMID:10856188

Boischio, A A; Henshel, D S

2000-06-01

235

Mosquito abundance and behavior in the influence area of the hydroelectric complex on the Madeira River, Western Amazon, Brazil.  

PubMed

Malaria is currently highly prevalent and restricted to the north of Brazil, and its dynamics are severely affected by human environmental changes, such as the large dam construction recently approved by the Brazilian Government in Rondônia. We studied the mosquito fauna and behavior before hydroelectric construction. Mosquitoes were captured by human landing catches on the riversides of the Madeira River in Porto Velho, Rondônia. A total of 3121 mosquitoes from eight different genera were collected; only Mansonia and Anopheles darlingi were found in all 21 collection sites throughout the night. These results suggest that the riverines of the study area are exposed to malaria. PMID:18952248

Cruz, Rafael Mesquita Bastos; Gil, Luiz Herman Soares; de Almeida e Silva, Alexandre; da Silva Araújo, Maisa; Katsuragawa, Tony Hiroshi

2009-11-01

236

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

PubMed

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

Claramunt, Santiago

2014-09-01

237

Buy at Amazon Buy at Amazon  

E-print Network

, Mr. Darwin Farewell to selfish gene Prague 2008 Charles University in Prague, Faculty of Science Buy at Amazon #12;Flegr Jaroslav Frozen Evolution. Or, that's not the way it is, Mr. Darwin ­ FarewellBuy at Amazon #12;Buy at Amazon #12;Jaroslav Flegr Frozen Evolution Or, that's not the way it is

Flegr, Jaroslav

238

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

239

Hydrochemical state of intermediate culture pond for Chinese prawn juveniles  

NASA Astrophysics Data System (ADS)

This study deals with the hydrochemical state and management measures for the intermediate culture pond for Chinese prawn ( Penaeus orientalis) juveniles. The test result showed that the intermediate culture of Chinese prawn juvenile can be advanced to around March 20 in the Shanghai area if they are cultured in ponds in simple greenhouses of plastic knitting cloth. The density of juveniles introduced was about 35 million per hectare, survival was up to 55%.

Zang, Wei-Ling; Zhang, Jian-Da; Dai, Xi-Lin; Zhu, Zheng-Guo; Xu, Gui-Rong; Song, Lin-Hua; Li, Shi-Hua

1996-03-01

240

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

241

Mercury levels assessment in hair of riverside inhabitants of the Tapajós River, Pará State, Amazon, Brazil: Fish consumption as a possible route of exposure.  

PubMed

The study present evaluated the levels of mercury (Hg) and methylmercury (MeHg) in hair samples of people from Barreiras community, riverside inhabitants of the Tapajós River (Pará, Brazil), an area impacted by clandestine gold mining, as well as we analyzed the levels of Hg and Se (selenium) in nine fish species (carnivores and non-carnivorous) from the Tapajós River, which stand out as the main species consumed by riverside inhabitants, to evaluate a relationship between frequency of fish consumption and Hg concentration, and also to evaluate possible mechanisms of fish protection (or non-protection) to Hg exposure by Se. Furthermore we analyze the water quality to evaluate the environmental trophic state, fact responsible by creating conditions that can potentiate the effects of toxic mercury. Concentrations of Hg and MeHg were analyzed in hair samples of 141 volunteers in different age band. Of those, 84.40% of samples present values above the threshold for biological tolerance, which is 6.00?gg(-1) of total Hg in hair. Total Hg, in men there was a variation of 2.07-24.93?gg(-1), while for women the variation was 4.84-27.02?gg(-1). Consequently, the level of MeHg in men presented a variation of 1.49-19.57?gg(-1), with an average of 11.68?gg(-1), while with women the variation was from 3.73 to 22.35?gg(-1), with an average of 10.38?gg(-1). In fish species, Hg concentrations in carnivorous species had an average of 0.66?gg(-1), higher than that permitted by current legislation, ranging from 0.30 to 0.98?gg(-1), while the non-carnivorous species have values below the recommended by the legislation averaging 0.09?gg(-1), ranging between 0.02 and 0.44?gg(-1). For Se in fish, show that among carnivores, the contents of Se ranged between 0.18 and 0.54?gg(-1) with a mean of 0.34?gg(-1), while for non-carnivores these values were of the order of 0.16-0.56?gg(-1), with an average of 0.32?gg(-1). In surface water quality variables at the sampling points all showed values in accordance with the range established by current legislation. In this regard, the results provided by this study, while not conclusive, are strong indicators that despite not having been shown the relationship between the concentration of mercury in hair and feeding habits along the Tapajós River basin communities showed that a plausible correlation exists between levels of mercury and selenium in fish. This fact may serve as a subsidy to research human health, because in the Amazon, there is still a lot to examine with regards to the full understanding of the Se cycle. PMID:25467850

Faial, Kleber; Deus, Ricardo; Deus, Simonny; Neves, Ramiro; Jesus, Iracina; Santos, Elisabeth; Alves, Cláudio Nahum; Brasil, Davi

2015-04-01

242

Expression of biotransformation and oxidative stress genes in the giant freshwater prawn Macrobrachium rosenbergii exposed to chlordecone.  

PubMed

Chlordecone is a persistent organochlorine pesticide widely used between 1972 and 1993 in the French West Indies to control the root borer in banana fields. Chlordecone use resulted in long-term pollution of soils, contamination of waters, of aquatic organisms, and of fields. Chlordecone is known to be neurotoxic, to increase prostate cancer, and to have negative effects on cognitive and motor development during infancy. In Guadeloupe, most of the freshwater species living in contaminated rivers exceed the French legal limit of 20 ?g·kg(-1) wet weight. In the present study, we chose a transcriptomic approach to study the cellular effects of chlordecone in the giant freshwater prawn Macrobrachium rosenbergii, an important economical species in Guadeloupe. Quantitative PCR revealed an induction of genes involved in defense mechanism against oxidative stress (catalase and selenium-dependent glutathione peroxidase) in prawns exposed to low environmental concentrations of chlordecone after 12 and 24 h of exposure. In prawns reared in a contaminated farm, transcription of genes involved in the biotransformation process (cytochrome P450 and glutathione-S-transferase (GST)) were induced after 8 days of exposure. Our results provide information on the mechanims of defense induced by chlordecone in aquatic crustacean species. This gene expression study of selected genes should be further strengthened by proteomic analyses and enzymatic activity assays to confirm the response of these biomarkers of stress in crustaceans and to give new insights into the mechanism of toxicity by chlordecone. PMID:24920261

Gaume, Béatrice; Dodet, Nathalie; Thomé, Jean-Pierre; Lemoine, Soazig

2014-06-13

243

Effects of Handling Methods on Quality Changes of Giant Freshwater Prawns (Macrobrachium rosenbergii)  

Microsoft Academic Search

Prawns (Macrobrachium rosenbergii) were subjected to conditions, which simulated domestic and export handling practices. Prawns were mixed with crushed ice to maintain the prawn samples temperature at 0°C and were stored at room temperature (25 ±2°C) for 48 hr for the domestic handling trial, while for export handling, the samples were kept in a cold room at (0 ±1°C) for

Punchira Vongsawasdi; Athapol Noomhorm

2000-01-01

244

Relation between water temperature, water exchange amount, feed and prawn disease  

NASA Astrophysics Data System (ADS)

High temperature is an important factor inducing bacterial disease of the prawn ( Penaeus orientalis). Water temperature over 35°C apparently stopped tested baculovirus from multiplying. High contents of ammonia-nitrogen and nitrite-nitrogen poison the prawn’s body, weaken its physique and may induce and worsen the disease.

Zang, Wei-Ling; Dai, Xi-Lin; Jiang, Min; Zhang, Jian-Da; Huang, Jian-Hua; Sun, Shao-Yong; Xu, Gui-Rong; Li, Shi-Hua

1997-09-01

245

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...

246

Radium isotopes in coastal waters on the Amazon shelf  

Microsoft Academic Search

Radium isotope distributions on the continental shelf adjacent to the Amazon River are a complex function of salinity. The river and seawater endmembers for each radium isotope are low. Data from intermediate salinities plot as a highly scattered region above the conservative mixing line connecting the river and ocean endmembers. Spatial and temporal variability in sediment mixing and water residence

Willard S. Moore; Heather Astwood; Candice Lindstrom

1995-01-01

247

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

248

Geochemistry of Amazon Basin supported by the ADCP measurements  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

249

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

Microsoft Academic Search

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

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

1997-01-01

250

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

251

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

252

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

SciTech Connect

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

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

1995-06-01

253

Meander Migration in the Amazon Basin  

NSDL National Science Digital Library

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

Les Hasbargen

254

Elevated mercury concentrations in soils, sediments, water, and fish of the Madeira River basin, Brazilian Amazon: a function of natural enrichments?  

Microsoft Academic Search

Previous site-specific investigations have found that mercury concentrations in water, sediments, and biota of the Brazilian Amazon are elevated above global averages, and that these concentrations are a direct result of widespread mercury amalgamation mining operations conducted by non-organized prospectors. In order to assess the regional impacts of Hg contamination from these non-organized gold mining activities, water, sediments, and fish

P. j. Lechler; J. r. Miller; L. d. Lacerda; D. Vinson; J.-C Bonzongo; W. b. Lyons; J. j. Warwick

2000-01-01

255

Research Article Evaluation of changes in the Kuwaiti prawn fishery  

E-print Network

ecosystem and fish- eries resources in Kuwait's coastal waters were severely damaged. More than 10 years the war. This study suggests that there has been large reduction in recruitment in Kuwait's prawn fishery. Introduction Iraq invaded Kuwait in 1990. The Iraqis released 6­8 million barrels of crude oil into the Arabian

Chen, Yong

256

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

257

The Giant Myelinated Nerve Fibres of the Prawn  

Microsoft Academic Search

Evidence is given that the median and lateral longitudinal giant myelinated fibres in the central nervous system of the prawn Leander serratus are syncitial structures, each formed by the fusion of the processes of many segmental nerve cells. Septa are found at intervals in the axoplasm of the median fibres, but they never completely transect it. They are probably relics

William Holmes

1942-01-01

258

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

259

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.

260

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

261

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

262

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

PubMed

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

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

2015-03-01

263

Nouveautés sur les débits monstrueux de l'Amazone  

Microsoft Academic Search

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

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

264

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

265

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

266

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

267

Causes and impacts of the 2005 Amazon drought  

Microsoft Academic Search

A rare drought in the Amazon culminated in 2005, leading to near record-low streamflows, small Amazon river plume, and greatly enhanced fire frequency. This episode was caused by the combination of 2002-03 El Nino and a dry spell in 2005 attributable to a warm subtropical North Atlantic Ocean. Analysis for 1979-2005 reveals that the Atlantic influence is comparable to the

268

Seasonal water storage on the Amazon floodplain measured from satellites  

Microsoft Academic Search

The amount of water stored and moving through the Amazon floodplain is not known, yet is necessary for understanding the role of the wetland in the regional carbon balance and the sediment and nutrient exchanged with the main river channel. Here, we separate the Amazon floodplain into six 330km×330km areas and use gravimetric and imaging satellite methods (i.e., GRACE, SRTM,

Douglas Alsdorf; Shin-Chan Han; Paul Bates; John Melack

2010-01-01

269

A Comparative Cytogenetic Study of Five Piranha Species ( Serrasalmus , Serrasalminae) from the Amazon Basin  

Microsoft Academic Search

Cytogenetic studies were conducted on five piranha species belonging to the genus Serrasalmus, subfamily Serrasalminae (Serrasalmus altispinis, S. compressus, S. elongatus, S. manuelli, and S. spilopleura). All the species were collected in the Amazon basin: confluence of Negro and Solimõoes Rivers (CatalãoLake), Solimões River (Marchantaria Island – Camaleão Lake), Uatumã River (Hydroelectric Power Station of Balbina), and Pitinga River (Hydroelectric

Celeste Mutuko Nakayama; Jorge Ivan Rebelo Porto; Eliana Feldberg

2002-01-01

270

Rapid prediction of moisture content of dehydrated prawns using online hyperspectral imaging system.  

PubMed

Because the shape of prawn is not round, spectroscopy instruments cannot measure the spectra of the whole prawn without containing background information. In this study, an online hyperspectral imaging system in the spectral region of 380-1100 nm was developed to determine the moisture content of prawns at different dehydrated levels. Hyperspectral images of prawns were acquired at different dehydration periods. The spectra of prawns then were extracted from hyperspectral images based on 'Manual Prawn Mask' and 'Automatic Prawn Mask', respectively. Spectral data were analyzed using partial least squares regression (PLSR) and least-squares support vector machines (LS-SVM) to establish the calibration models, respectively. Successive projections algorithm (SPA) was first applied for the optimal wavelength selection in the hyperspectral image analysis. Out of 482 wavelengths, only twelve wavelengths (428, 445, 544, 569, 629, 672, 697, 760, 827, 917, 958, and 999 nm) were selected by SPA as the optimum wavelengths for moisture prediction. Based on these optimum wavelengths, a multiple linear regression (MLR) calibration model was established and used to obtain the moisture distribution of each prawn. The overall results of this study revealed the potentiality of hyperspectral imaging as an objective and non-destructive method to obtain the content and distribution of moisture of prawns whose shapes are not round. PMID:22541014

Wu, Di; Shi, Hui; Wang, Songjing; He, Yong; Bao, Yidan; Liu, Kangsheng

2012-05-13

271

Heavy metals in Ras Beirut prawns and sea urchin eggs.  

PubMed

Whole samples of Palaemon elegans Rathke, 1837 and eggs of Paracentrotus lividus Lamarck, 1816 were collected on the coast of Ras Beirut, Lebanon in the summer and fall of 1977 and the spring of 1978. All were analysed for lead, cadmium, copper and other heavy metals. Lead concentrations in both the prawns and sea urchin eggs appeared to be highest in the summer and lowest in the spring, whereas cadmium was low in all seasons with only a few elevated readings. The strongest tendency towards seasonal variation was seen in the copper levels of the prawns, which were high in summer, much lower in fall, and then high again in spring. Results of the analyses for nickel, iron, zinc and chromium are also discussed. Of the various possible sources of heavy metals in the Ras Beirut coastal area, untreated sewage, pesticide residues, and automobile exhaust are the most important. PMID:429762

Shiber, J G

1979-01-01

272

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

273

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

Microsoft Academic Search

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

F. E. S. Januário; G. A. Dykes

2005-01-01

274

DOI: 10.1002/adem.201180027 Battle in the Amazon: Arapaima versus Piranha**  

E-print Network

DOI: 10.1002/adem.201180027 Battle in the Amazon: Arapaima versus Piranha** By M. A. Meyers,* Y. S in the Amazon basin, populated by over 30 species of piranhas (family: Characidae; sub-family: serrasalminae). Among these, the most predatorial is the red piranha (Pygocentrus natteri). As the waters of the rivers

Meyers, Marc A.

275

Management strategies for short lived species: The case of Australia's Northern Prawn Fishery  

Microsoft Academic Search

Management strategies for tiger prawns, Penaeus semisulcatus and P. esculentus, in Australia's Northern Prawn Fishery (NPF), are evaluated in terms of conservation- and economic-related performance measures. A two-stage process is used to determine the factors to which these performance measures are most sensitive. The first stage involves identifying the possible factors and their interactions, constructing a partial factorial design to

Catherine M. Dichmont; André E. Punt; William Venables; Malcolm Haddon

2006-01-01

276

Prawns and piranhas: The political economy of a Tanzanian private sector marketing chain  

Microsoft Academic Search

The article presents the findings of recent research on three principal areas of prawn fishing in Tanzania: trawler and ‘artisanal’ fishing off and in the Rufiji Delta respectively, and costal ‘artisanal’ fishing from Bagamoyo. Adapting a filière?type approach, it analyses the organisation of production, collection, processing and marketing\\/distribution in the various prawn commodity chains, in terms of their social and

Peter Gibbon

1997-01-01

277

The "Prawn-in-the-Tube" Procedure in the Cuttlefish: Habituation or Passive Avoidance Learning?  

ERIC Educational Resources Information Center

This study examines whether or not habituation contributes to the regulation of the inhibition of predatory behavior observed during the "prawn-in-the-tube" training procedure. When presented with prawns that are visible behind glass but untouchable, cuttlefish promptly learn to inhibit their capture attempts. The first three experiments…

Dickel, Ludovic; Chichery, Marie-Paule; Agin, Veronique; Chichery, Raymond

2006-01-01

278

Factors influencing the structure and spatial distribution of fishes in the headwater streams of the Jaú River in the Brazilian Amazon.  

PubMed

The aim of this study was to investigate the influence of spatial variation in river channels and habitats on the distribution of fish communities in the headwater streams of the Jaú River System, a blackwater tributary of the Negro River. Collections and measurements were made in 34 headwater streams during the period of November- December, 1998. Fish were captured with fish traps and hand nets along standard reaches of two meanders. Data on benthic habitat structure, stream depth and width were collected along lateral transects in each sample reach. A total of 66 fish species from 24 families were collected and classified into seven trophic guilds: allocthonous insectivore, autochthonous insectivore, general insectivore, piscivore, detritivorous planktivore, detritivorous insectivore and insectivorous piscivore. Variations in the distribution and diversity of bottom substrates were important factors influencing fish community structures in these systems. Also, variation in stream size explained the observed variability in fish communities. PMID:25627363

Kemenes, A; Forsberg, B R

2014-08-01

279

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

280

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

PubMed

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

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

2011-06-15

281

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

282

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

PubMed

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

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

2014-01-01

283

Toxic effects of linear alkylbenzene sulfonate on the tiger prawn, Penaeus monodon.  

PubMed

The toxic effects of linear alkybenzene sulfonate (LAS) on the larvae and juveniles of tiger prawn Penaeus monodon were tested. The 24-hr LC50 values of LAS were 0.06, 0.10, and 3.11 ppm for the zoea 2nd substage, mysis 2nd substage (M2), and postlarva 12th substage (PL12) of the tiger prawn, respectively. The 48-hr LC50 values of LAS were 0.07, 1.03, and 4.36 ppm for M2, PL12, and postlarva 15th substage of the tiger prawn, respectively. The hepatopancreatic glutathione (GSH) in juvenile tiger prawn was obviously depleted when LAS concentration was over 1.0 ppm. The hepatopancreatic GSH content of tiger prawn exposed to solutions of greater than 1.0 ppm LAS was difficult to raise to normal levels, even after the tiger prawns were switched to an LAS-free solution. The activity of malate dehydrogenase in the serum of juvenile tiger prawns exposed to 10.0 ppm LAS solution was significantly increased. PMID:7507819

Hwang, D F; Chen, M Y; Yoshida, T; Jeng, S S

1993-12-01

284

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

285

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

286

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

287

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

PubMed

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

Finer, Matt; Jenkins, Clinton N

2012-01-01

288

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. PMID:22529979

Finer, Matt; Jenkins, Clinton N.

2012-01-01

289

Treatment efficiency of effluent prawn culture by wetland with floating aquatic macrophytes arranged in series.  

PubMed

The efficiency of a series of wetland colonized with Eichhornia crassipes and Salvinia molesta to treat the effluent of a giant river prawn (Macrobrachium rosenbergii) broodstock pond was evaluated in this study. The experimental design was completely randomized and was performed in 9 rectangular tanks (1.6 m3) with three treatments (constructed wetlands) and three replicates. The treatment types included: a wetland colonized with E. crassipes and S. molesta (EcSm) arranged sequentially, a wetland with E. crassipes only (Ec) and a wetland with S. molesta only (Sm). The means of suspended particulate material (SPM), total inorganic nitrogen (TIN), total Kjeldahl nitrogen (TKN), P-orthophosphate (PO4-P) and total phosphorus (TP) of the treated effluents were compared using ANOVA followed by Tukey's test (P<0.05). The effluent treated in Ec and EcSm wetlands exhibited lower SPM concentrations. The Ec wetland reduced TIN, TKN, PO4-P and TP by 46.0, 43.7, 44.4 and 43.6%, respectively. In the EcSm wetland, the reduction of TIN (23.0%), TKN (33.7%) and PO4-P (26.7%) was similar to the Sm wetland (19.8% TIN, 30.9% TKN and 23.8% PO4-P). The Ec wetland was more efficient in treating pond effluent due likely to the higher root surface of E. crassipes, which forms an extensive area favorable to retention and adsorption of debris and absorption of nutrients. PMID:25627602

Henares, M N P; Camargo, A F M

2014-11-01

290

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

PubMed

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

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

2012-04-01

291

Rivers  

NSDL National Science Digital Library

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

Idaho PTV

2011-09-04

292

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

293

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

294

Lost in the Amazon  

NSDL National Science Digital Library

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

Adventure Engineering,

295

The Amazon and climate  

NASA Technical Reports Server (NTRS)

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

Nobre, C. A.

1984-01-01

296

Fishing for Prawn Larvae in Bangladesh: An Important Coastal Livelihood Causing Negative Effects on the Environment  

Microsoft Academic Search

Freshwater prawn (Macrobrachium rosenbergii) farming in Bangladesh has, to a large extent, been dependent on the supply of wild larvae. Although there are 81 freshwater\\u000a prawn hatcheries in the country, a lack of technical knowledge, inadequate skilled manpower, and an insufficient supply of\\u000a wild broods have limited hatchery production. Many thousands of coastal poor people, including women, are engaged in

Nesar Ahmed; Max Troell

2010-01-01

297

Gut microflora of two saltmarsh detritivore thalassinid prawns, Upogebia africana and Callianassa kraussi  

Microsoft Academic Search

The presence and digestive capabilities of bacteria associated with the digestive systems and habitats of two saltmarsh-burrowing\\u000a detritivore thalassinid prawns (Upogebia africana andCallianassa kraussi) was examined.U. africana is a filter-feeding prawn inhabiting muddy deposits, whereasC. kraussi, a deposit feeder, inhabits coarser more sandy deposits. Scanning electron microscopy was used to examine the gut lining\\u000a and associated microflora and the nature

Jean M. Harris; Lindsay J. Seiderer; Michael I. Lucas

1991-01-01

298

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

Microsoft Academic Search

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

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

2010-01-01

299

Reconciling geography and genealogy: phylogeography of giant freshwater prawns from the Lake Carpentaria region.  

PubMed

There is convincing geological evidence for the historical existence of an ancient lake on the Australian-New Guinea continental shelf during the late Pleistocene. Lake Carpentaria was a vast fresh- to brackishwater lake that would presumably have provided habitat for, and facilitated gene flow among, aquatic taxa that tolerate low to moderate salinities in this region. Moreover, it has been argued that the outflow of Papua New Guinea's Fly River was diverted westward into Lake Carpentaria during this period, although this hypothesis is controversial. We predicted that these events, if a true history, would have promoted gene flow and population growth via range-expansion events in the giant freshwater prawn (Macrobrachium rosenbergii) and restricted gene flow subsequently by way of a vicariant event as sea levels rose during the late Pleistocene, and a marine environment replaced Lake Carpentaria. We tested these hypotheses using phylogeographical and phylogenetic analyses of mitochondrial DNA variation in M. rosenbergii populations sampled from the Lake Carpentaria region. Our results support the hypothesis that Lake Carpentaria facilitated gene flow among populations of M. rosenbergii that are today isolated, but contest claims of a westward diversion of the Fly River. We inferred the timing of initial expansion in the 'Lake Carpentaria lineage' and found the timing of this event to be broadly concordant with geological dating of the formation of Lake Carpentaria. Reconciling geological and molecular data, as presented here, provides a powerful framework for investigating the influence of historical earth history events on the distribution of biological (i.e. molecular) diversity. PMID:15488008

de Bruyn, Mark; Wilson, John C; Mather, Peter B

2004-11-01

300

Predation and control of laboratory populations of the snail Biomphalaria glabrata by the freshwater prawn Macrobrachium rosenbergii.  

PubMed

Laboratory experiments were conducted on predation by the giant freshwater prawn, Macrobrachium rosenbergii, on Biomphalaria glabrata, a snail intermediate host of human schistosomiasis. Prawns greater than 22 mm carapace length could consume snails of any size. Smaller prawns exhibited a size-specific upper limit on the size of snail they could kill. Below the maximum size of prey consumed, little selectivity for prey size was demonstrated. All prawns heavier than 2.5 g killed the largest size of snail offered (16 mm diameter). Consumption, in terms of the numbers of snails killed, and the snails' wet weight and percentage of prawn body weight eaten per day, increased with prawn size. Large prawns consumed snails at a high rate (39% of body weight per day). Population experiments demonstrated that a prawn of 25 mm carapace length could eliminate 95% of a population of 80 snails in a 20-1 aquarium within 20 days and all snails by day 40. A prawn of 15 mm carapace length could not eliminate all snails. Large snails (24% of the initial population) had some protection from predation because of their size. Although the snails bred continuously, no snails were able to recruit to these populations in the presence of small prawns. In contrast, snail populations in control aquaria without prawns expanded to a mean of 919 snails by the end of the experiment (day 70). Since M. rosenbergii are voracious predators on B. glabrata, exhibit considerable habitat overlap with the snail prey, and are likely to treat snails as highly preferred food, further experimentation on these prawns in the context of biological control of schistosomiasis is warranted. The ready availability of prawns through established prawn hatcheries and the synergistic use of these prawns in aquaculture may ensure the reliability of stocking procedures and meet the standards of availability and cost-effectiveness required of a biological control agent. Polyculture of Macrobrachium with fin fish (Tilapia) indicates that these prawns may be a particularly useful control agent in aquacultural environments. PMID:2260905

Roberts, J K; Kuris, A M

1990-08-01

301

Changes in optical properties caused by UV-irradiation of aquatic humic substances from the amazon river basin: seasonal variability evaluation.  

PubMed

Aquatic humic substances (AHS) isolated from two characteristic seasons of the Negro river, winter and summer corresponding to floody and dry periods, were structurally characterized by 13C nuclear magnetic ressonance. Subsequently, AHS aqueous solutions were irradiated with a polychromatic lamp (290-475 nm) and monitored by its total organic carbon (TOC) content, ultraviolet-visible (UV-vis) absorbance, fluorescence, and Fourier transformed infrared spectroscopy (FTIR). As a result, a photobleaching up to 80% after irradiation of 48 h was observed. Conformational rearrangements and formation of low molecular complexity structures were formed during the irradiation, as deduced from the pH decrement and the fluorescence shifting to lower wavelengths. Additionally a significant mineralization with the formation of CO2, CO, and inorganic carbon compounds was registered, as assumed by TOC losses of up to 70%. The differences in photodegradation between samples expressed by photobleaching efficiency were enhanced in the summer sample and related to its elevated aromatic content. Aromatic structures are assumed to have high autosensitization capacity effects mediated by the free radical generation from quinone and phenolic moieties. PMID:18409619

Rodríguez-Zúñiga, Ursula Fabiola; Milori, Débora Marcondes Bastos Pereira; da Silva, Wilson Tadeu Lopes; Martin-Neto, Ladislau; Oliveira, Luciana Camargo; Rocha, Julio Cesar

2008-03-15

302

Amazon Observation Platform  

USGS Multimedia Gallery

Observation tower at the Amazon forest study site near Santarém, Brazil. A USGS instrument installed at the top of the 148-foot (45-meter) tower monitors changes in atmospheric conditions and the solar radiation available for photosynthesis. Data from the system are being used by USGS Geograp...

303

Amazon Deforestation Model  

NSDL National Science Digital Library

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

Joycelyn Thomson

1994-03-13

304

Monitoring the spreading of the Amazon freshwater plume by MODIS, SMOS, Aquarius, and TOPAZ  

NASA Astrophysics Data System (ADS)

synergistic tool for studying the Amazon River plume dynamics based on a novel algorithm for deriving sea surface salinity (SSS) from MODIS reflectance data together with SSS data from the SMOS and Aquarius satellites and the TOPAZ data assimilation system is proposed. The new algorithm is based on a neural network to relate spectral remote sensing reflectance measured by MODIS with SSS measured by SMOS in the Amazon River plume. The algorithm is validated against independent in situ data and is found to be valid in the range of SSS from 29 to 35 psu, for the period of highest rates of Amazon River discharge with RMSE = 0.79 psu and r2 = 0.84. Monthly SSS fields were reconstructed from the MODIS data for late summers from 2002 to 2012 at a 10 km resolution and compared to surface currents and SSS derived from the TOPAZ reanalysis system. The two data sets reveal striking agreement, suggesting that the TOPAZ system could be used for a detailed study of the Amazon River plume dynamics. Both the position and speed of the North Brazilian Current as well as the spreading of the Amazon River plume are monitored. In particular, a recurrent mechanism was observed for the spreading of the rivers plumes, notably that the fresh water is usually advected toward the Caribbean Sea by the North Brazilian Current but get diverted into the tropical Atlantic when North Brazilian Current Rings are shed.

Korosov, Anton; Counillon, François; Johannessen, Johnny A.

2015-01-01

305

Carbon dioxide in the atmosphere over the Amazon Basin  

NASA Technical Reports Server (NTRS)

As a part of the NASA's Amazon Boundary Layer Experiment 2A mission, the cycle of atmospheric CO2 over the Amazon Basin was examined using measured vertical profiles of CO2 concentrations in the canopy and aloft, and direct measurements of CO2 emissions from soils. The results provide a detailed picture of daily exchanges of air between the tropical forest (0-30) and the atmospheric boundary layer (30-2000 m). A comparison of atmospheric CO2 distributions over forests, wetlands, and rivers shows that the lower atmosphere over forests functions separately from that over rivers or wetlands during the night and to some extent during the day; the basic diurnal cycle of CO2 over wetlands is much weaker than over forests, and the cycle is almost absent over rivers. This result is consistent with expectations based on the biogeochemistry of organic carbon in these systems.

Wofsy, Steven C.; Kaplan, Warren A.; Harriss, Robert C.

1988-01-01

306

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 â??stealthâ? 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

307

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. PMID:23734171

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

2013-01-01

308

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

309

Consequences of riverine flooding for seston and theperiphyton of floating meadows in an Amazon floodplain lake  

Microsoft Academic Search

Algal biomass and the chemical composition of seston and floating meadow periphyton were measured in an Amazon floodplain lake during a period of channelized river inflow and a period of overbank flow. During both periods, sedimentation of riverine particulates and loss of dissolved nutrients created strong spatial chemical gradients from the river onto the floodplain which were stable for months

DIANA L. ENGLE; JOHN M. MELACK

1993-01-01

310

77 FR 20358 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Final Results of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2012-04-04

311

75 FR 75965 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Final Results of the...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-12-07

312

75 FR 37757 - Frozen Warmwater Shrimp From Vietnam: Initiation and Preliminary Results of Changed-Circumstances...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-06-30

313

75 FR 61122 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Amended Final Results of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (Penaeus vannemei), banana prawn (Penaeus merguiensis), fleshy prawn (Penaeus chinensis), giant river prawn (Macrobrachium rosenbergii), giant tiger prawn (Penaeus monodon), redspotted [[Page 61123

2010-10-04

314

78 FR 33346 - Certain Frozen Warmwater Shrimp From the People's Republic of China: Preliminary Countervailing...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-06-04

315

78 FR 33344 - Certain Frozen Warmwater Shrimp From India: Preliminary Countervailing Duty Determination  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-06-04

316

75 FR 47546 - Certain Frozen Warmwater Shrimp from the Socialist Republic of Vietnam: Preliminary Results of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-08-06

317

77 FR 23222 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Final Results of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2012-04-18

318

75 FR 3446 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Preliminary Intent To...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-01-21

319

78 FR 33347 - Certain Frozen Warmwater Shrimp From Ecuador: Preliminary Negative Countervailing Duty Determination  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-06-04

320

78 FR 33349 - Certain Frozen Warmwater Shrimp From Indonesia: Negative Preliminary Countervailing Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-06-04

321

78 FR 35643 - Frozen Warmwater Shrimp from China, Ecuador, India, Indonesia, Malaysia, Thailand, and Vietnam...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-06-13

322

75 FR 74684 - Notice of Final Results of Antidumping Duty Changed Circumstances Review: Certain Frozen...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-12-01

323

75 FR 52718 - Certain Frozen Warmwater Shrimp From India: Final Results of Antidumping Duty Changed...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-08-27

324

75 FR 54847 - Certain Frozen Warmwater Shrimp from Thailand: Final Results and Partial Rescission of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-09-09

325

78 FR 33342 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Preliminary...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-06-04

326

78 FR 50379 - Certain Frozen Warmwater Shrimp From Thailand: Final Negative Countervailing Duty Determination  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-08-19

327

78 FR 33350 - Certain Frozen Warmwater Shrimp From Thailand: Preliminary Countervailing Duty Determination  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2013-06-04

328

76 FR 64307 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Amended Final Results and...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2011-10-18

329

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

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-04-01

330

76 FR 12033 - Certain Frozen Warmwater Shrimp From Thailand: Preliminary Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2011-03-04

331

77 FR 64953 - Notice of Initiation and Preliminary Results of Antidumping Duty Changed Circumstances Review...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2012-10-24

332

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

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2012-07-10

333

75 FR 51756 - Certain Frozen Warmwater Shrimp From India: Notice of Rescission of Antidumping Duty Changed...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-08-23

334

75 FR 36635 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Rescission of New Shipper...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-06-28

335

75 FR 49889 - Notice of Final Results of Antidumping Duty Changed-Circumstances Review: Frozen Warmwater Shrimp...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-08-16

336

75 FR 13492 - Certain Frozen Warmwater Shrimp From India: Initiation of Antidumping Duty Changed-Circumstances...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-03-22

337

76 FR 40881 - Certain Frozen Warmwater Shrimp From Thailand: Final Results of Antidumping Duty Administrative...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2011-07-12

338

75 FR 61702 - Notice of Initiation and Preliminary Results of Antidumping Duty Changed Circumstances Review...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-10-06

339

77 FR 73619 - Final Results of Antidumping Duty Changed Circumstances Review: Certain Frozen Warmwater Shrimp...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2012-12-11

340

77 FR 13082 - Certain Frozen Warmwater Shrimp From Thailand: Preliminary Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2012-03-05

341

76 FR 30648 - Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Final Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2011-05-26

342

75 FR 44229 - Certain Frozen Warmwater Shrimp from India: Preliminary Results of Antidumping Duty Changed...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2010-07-28

343

76 FR 45775 - Fourth New Shipper Review of Certain Frozen Warmwater Shrimp From the Socialist Republic of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...shrimp (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 brown...

2011-08-01

344

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

345

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

346

The Amazon and climate  

NASA Technical Reports Server (NTRS)

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

Nobre, C. A.

1984-01-01

347

Diets of piscivorous fishes in a tropical Australian estuary, with special reference to predation on penaeid prawns  

Microsoft Academic Search

The diets of fish from the tropical Embley Estuary in the eastern Gulf of Carpentaria, Australia, were analysed with particular reference to piscivory and predation on juveniles of commercially important penaeid prawns from October 1986 until July 1988. Of the 77 species caught, 52 were piscivorous, and of these 37 ate penaeid prawns. The most numerous piscivores wereScomberoides commersonianus, Arius

J. P. Salini; S. J. M. Blaber; D. T. Brewer

1990-01-01

348

Genetic diversity of cultured and wild populations of the freshwater prawn Macrobrachium rosenbergii based on microsatellite analysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Freshwater prawn Macrobrachium rosenbergii culture in the Western Hemisphere is primarily, if not entirely, based on thirty-six individual prawn introduced to Hawaii from Malaysia in 1965 and 1966. Little information is available regarding the genetic background or current population status of cult...

349

Mapping the Amazon: The Mouth of the Amazon  

NSDL National Science Digital Library

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

Stuart Snodgrass

2002-03-14

350

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

PubMed Central

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

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

2014-01-01

351

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

PubMed

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

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

2014-01-01

352

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

353

Uranium and thorium isotopes in the rivers of the Amazonian basin: hydrology and weathering processes  

Microsoft Academic Search

Two expeditions (October 1989 and May 1992) were carried out to two points of the main Amazon River channel and four tributaries. The Solimões and Madeira rivers, taking their origin in the Andes, are whitewater rivers. The Negro River is a typical acid, blackwater river. The Trombetas River flows through bauxite-rich areas, and is characterized by low concentrations of dissolved

Aguinaldo N. Marques Jr.; Iyad Al-Gharib; Michel Bernat; François Fernex

2003-01-01

354

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.

Rich Pavlovsky

355

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

2009-08-01

356

Coupling between sedimentary dynamics, early diagenetic processes, and biogeochemical cycling in the Amazon–Guianas mobile mud belt: coastal French Guiana  

Microsoft Academic Search

Coastal French Guiana lies within the vast mobile mudbelt that characterizes much of the S. American inner shelf downdrift of the Amazon River. Approximately ?15–20% of the Amazon sediment outfall moves NW along the Guianas, in part as a series of 20–25 coastal mud waves. Seasonal studies of a representative migrating mudwave located between Kourou and Sinnamary, French Guiana demonstrate

Robert C Aller; Christina Heilbrun; Caterina Panzeca; Zhongbin Zhu; Frédéric Baltzer

2004-01-01

357

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.

358

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

359

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

360

Molecular Characterisation of Colour Formation in the Prawn Fenneropenaeus merguiensis  

PubMed Central

Introduction Body colouration in animals can have a range of functions, with predator protection an important aspect of colour in crustaceans. Colour determination is associated with the carotenoid astaxanthin, which is taken up through the diet and stabilised in the tissues by the protein crustacyanin. As a variety of genes are found to play a role in colour formation in other systems, a holistic approach was employed in this study to determine the factors involved in Fenneropenaeus merguiensis colouration. Results Full length F. merguiensis crustacyanin subunit A and C sequences were isolated. Crustacyanin subunit A and C were found in the F. merguiensis transcriptomes of the muscle/cuticle tissue, hepatopancreas, eye stalk and nervous system, using 454 next generation sequencing technology. Custom microarray analysis of albino, light and dark F. merguiensis cuticle tissue showed genes encoding actin, sarcoplasmic calcium-binding protein and arginine kinase to be 4-fold or greater differentially expressed (p<0.05) and down-regulated in albinos when compared to light and dark samples. QPCR expression analysis of crustacyanin and total astaxanthin pigment extraction revealed significantly (p<0.05) lower crustacyanin subunit A and C gene transcript copy numbers and total astaxanthin levels in albinos than in the light and dark samples. Additionally, crustacyanin subunit A and C expression levels correlated positively with each other. Conclusions This study identified gene products putatively involved in crustacean colouration, such as crustacyanin, sarcoplasmic calcium-binding protein and forms of actin, and investigated differences in gene expression and astaxanthin levels between albino, light and dark coloured prawns. These genes open a path to enhance our understanding of the biology and regulation of colour formation. PMID:23441225

Ertl, Nicole G.; Elizur, Abigail; Brooks, Peter; Kuballa, Anna V.; Anderson, Trevor A.; Knibb, Wayne R.

2013-01-01

361

An assessment of Bycatch Reduction Devices in a tropical Australian prawn trawl fishery  

Microsoft Academic Search

Our study assessed 16 different Bycatch Reduction Devices (BRDs) for use in Australia's Northern Prawn Fishery (NPF), during three cruises in the Gulf of Carpentaria. The study was a response to pressure from conservation and community groups to make harvesting of the sea more selective and less damaging to the non-target communities. The approach was to incrementally improve the performance

David Brewer; Nicholas Rawlinson; Steve Eayrs; Charis Burridge

1998-01-01

362

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

363

Severn & Wye Smoked Salmon Salad with Wasabi Cream Spiced Crayfish and Prawn Verrine with Crme Fraiche  

E-print Network

Christmas Pudding with Brandy Sauce Mulled Wine Poached Pears with Cinnamon Ice Cream Chocolate Ganache, Honey Foam and Coffee Granita Spiced Orange Pudding with Christmas Pudding Ice Cream Crème Brulee TartChristmas Starters Severn & Wye Smoked Salmon Salad with Wasabi Cream Spiced Crayfish and Prawn

Lasenby, Joan

364

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.

365

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

366

Effect of salt treatments on survival and consumer acceptance of freshwater prawn, Macrobrachium rosenbergii  

Technology Transfer Automated Retrieval System (TEKTRAN)

Post harvest acclimation of live freshwater prawns to a mixture of water and marine salt increases the consumer acceptability of the finished product. However, the high cost of marine salts prohibits their use in commercial practice. Therefore, the identification of successful, cost effective salt a...

367

Mapping the Amazon: Mosaic pan  

NSDL National Science Digital Library

Pan across Amazon rainforest mosaic showing low water season (blue) and high water season (yellow). Together, these snapshots reveal conditions on the ground. Scientists listed worked as a team on Mosaicking Software and Mosaic Production.

Stuart Snodgrass

2002-03-14

368

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

369

Influence of short term exposure of TBT on the male reproductive activity in freshwater prawn Macrobrachium rosenbergii (De Man).  

PubMed

In the present study, the effect of tributyltin (TBT) on the histopathological and hormonal changes during spermatogenesis in freshwater prawn Macrobrachium rosenbergii was documented. Three experimental concentrations such as 10, 100 and 1,000 ng/L were selected and exposed to prawns for 45 days. After TBT exposure, the reproductive activities like sperm count and sperm length were decreased when compared with control. Further, abnormal structure of the seminiferous tubule, decrease in spermatozoa concentration, diminution of the seminiferous tubule membrane and the abundance of spermatocytes in the testis were noticed in treated prawns. Interestingly, radioimmunoassay clearly revealed the reduction of testosterone level in TBT exposed groups. Thus, TBT has considerably reduced the level of testosterone and caused the impairment of spermatogenesis in the freshwater male prawn M. rosenbergii. PMID:25016935

Revathi, Peranandam; Iyapparaj, Palanisamy; Vasanthi, Lourduraj Arockia; Munuswamy, Natesan; Prasanna, Vimalanathan Arun; Pandiyarajan, Jayaraj; Krishnan, Muthukalingan

2014-10-01

370

Deforestation, floodplain dynamics, and carbon biogeochemistry in the Amazon Basin  

NASA Technical Reports Server (NTRS)

Three aspects of the physical geographic environment of the Amazon Basin are considered: (1) deforestation and reforestation, (2) floodplain dynamics, and (3) fluvial geomorphology. Three independent projects are coupled in this experiment to improve the in-place research and to ensure that the Shuttle Imaging Radar-B (SIR-B) experiment stands on a secure base of ongoing work. Major benefits to be obtained center on: (1) areal and locational information, (2) data from various depression angles, and (3) digital radar signatures. Analysis will be conducted for selected sites to define how well SIR-B data can be used for: (1) definition of extent and location of deforestation in a tropical moist forest, (2) definition and quantification of the nature of the vegetation and edaphic conditions on the (floodplain) of the Amazon River, and (3) quantification of the accuracy with which the geometry and channel shifting of the Amazon River may be mapped using SIR-B imagery in conjunction with other remote sensing data.

Bryan, M. L.; Dunne, T.; Richey, J.; Melack, J.; Simonett, D. S.; Woodwell, G.

1984-01-01

371

Ballast water: a threat to the Amazon Basin.  

PubMed

Ballast water exchange (BWE) is the most efficient measure to control the invasion of exotic species from ships. This procedure is being used for merchant ships in national and international voyages. The ballast water (BW) salinity is the main parameter to evaluate the efficacy of the mid-ocean ballast water exchange. The vessels must report to the Port State Control (PSC), via ballast water report (BWR), where and how the mid-ocean BWE was performed. This measure allows the PSC to analyze this information before the ship arrives at the port, and to decide whether or not it should berth. Ship BW reporting forms were collected from the Captaincy of Santana and some ships were visited near the Port of Santana, located in Macapá (Amazon River), to evaluate the BW quality onboard. We evaluated data submitted in these BWR forms and concluded that the BWE efficacy might be compromised, because data contained in these BWR indicate that some ships did not change their BW. We found mistakes in filling the BWR forms and lack of information. Moreover, these ships had discharged BW with high level of salinity, Escherichia coli and total coliforms into the Amazon River. We concluded that the authorities of the Amazon Region need to develop more efficient proceedings to evaluate the ballast water reporting forms and BW quality, as there is potential risk of future invasion of exotic species in Brazilian ports. PMID:24928458

Pereira, Newton Narciso; Botter, Rui Carlos; Folena, Rafael Dompieri; Pereira, José Pinheiro Fragoso Neto; da Cunha, Alan Cavalcanti

2014-07-15

372

Deforestation, floodplain dynamics, and carbon biogeochemistry in the Amazon Basin  

NASA Astrophysics Data System (ADS)

Three aspects of the physical geographic environment of the Amazon Basin are considered: (1) deforestation and reforestation, (2) floodplain dynamics, and (3) fluvial geomorphology. Three independent projects are coupled in this experiment to improve the in-place research and to ensure that the Shuttle Imaging Radar-B (SIR-B) experiment stands on a secure base of ongoing work. Major benefits to be obtained center on: (1) areal and locational information, (2) data from various depression angles, and (3) digital radar signatures. Analysis will be conducted for selected sites to define how well SIR-B data can be used for: (1) definition of extent and location of deforestation in a tropical moist forest, (2) definition and quantification of the nature of the vegetation and edaphic conditions on the (floodplain) of the Amazon River, and (3) quantification of the accuracy with which the geometry and channel shifting of the Amazon River may be mapped using SIR-B imagery in conjunction with other remote sensing data.

Bryan, M. L.; Dunne, T.; Richey, J.; Melack, J.; Simonett, D. S.; Woodwell, G.

1984-07-01

373

Changes in the Carbon Cycle of Amazon Ecosystems During the 2010 Drought  

NASA Technical Reports Server (NTRS)

Satellite remote sensing was combined with the NASA-CASA carbon cycle simulation model to evaluate the impact of the 2010 drought (July through September) throughout tropical South America. Results indicated that net primary production (NPP) in Amazon forest areas declined by an average of 7% in 2010 compared to 2008. This represented a loss of vegetation CO2 uptake and potential Amazon rainforest growth of nearly 0.5 Pg C in 2010. The largest overall decline in ecosystem carbon gains by land cover type was predicted for closed broadleaf forest areas of the Amazon River basin, including a large fraction of regularly flooded forest areas. Model results support the hypothesis that soil and dead wood carbon decomposition fluxes of CO2 to the atmosphere were elevated during the drought period of 2010 in periodically flooded forest areas, compared to forests outside the main river floodplains.

Potter, Christophera; Klooster, Steven; Hiatt, Cyrus; Genovese, Vanessa; Castilla-Rubino, Juan Carlos

2011-01-01

374

Low-water maps of the groundwater table in the central Amazon by satellite altimetry  

NASA Astrophysics Data System (ADS)

Groundwater plays a fundamental role in rainforest environments, as it is connected with rivers, lakes, and wetlands, and helps to support wildlife habitat during dry periods. Groundwater reservoirs are however excessively difficult to monitor, especially in large and remote areas. Using concepts from groundwater-surface water interactions and ENVISAT altimetry data, we evaluated the topography of the groundwater table during low-water periods in the alluvial plain of the central Amazon. The water levels are monitored using an unprecedented coverage of 491 altimetric stations over surface waters in the central Amazon. The groundwater table maps interpolated at spatial resolutions ranging from 50 to 100 km are consistent with groundwater wells data. They provide evidence of significant spatiotemporal organization at regional scale: heterogeneous flow from the hillslope toward the main rivers is observed, as well as strong memory effects and contrasted hydrological behaviors between the North and the South of the Amazon.

Pfeffer, Julia; Seyler, Frédérique; Bonnet, Marie-Paule; Calmant, Stéphane; Frappart, Frédéric; Papa, Fabrice; Paiva, Rodrigo C. D.; Satgé, Frédéric; Silva, Joecila Santos Da

2014-03-01

375

The structure and function of a gene encoding a basic peptide from prawn white spot syndrome virus  

Microsoft Academic Search

Prawn white spot syndrome virus (WSSV) is the major pathogen responsible for the high mortality of cultured prawns. A gene (termed as p6.8) encoding a basic peptide was found by screening the cDNA and DNA libraries of WSSV. The peptide was highly homologous with proteins rich in arginine and lysine. A fusion protein containing the p6.8 and green fluorescent protein

Xiaobo Zhang; Xun Xu; Choy Leong Hew

2001-01-01

376

Dopamine depresses the immune ability and increases susceptibility to Lactococcus garvieae in the freshwater giant prawn, Macrobrachium rosenbergii  

Microsoft Academic Search

The total haemocyte count (THC), phenoloxidase activity, respiratory burst (release of superoxide anion), superoxide dismutase activity, and phagocytic activity and clearance efficiency to the pathogen Lactococcus garvieae were measured when freshwater giant prawns Macrobrachium rosenbergii (16.2±2.1 g) were individually injected with saline, or dopamine at 0.5, 5.0, or 50.0 pmol prawn?1. The results show that a transient period of immunosuppression

Jian-Tong Li; Pai-Po Lee; Ou-Chuan Chen; Winton Cheng; Ching-Ming Kuo

2005-01-01

377

New sediment budget calculations for the submarine Amazon Delta indicates enhanced modern sediment fluxes of the Amazon system  

NASA Astrophysics Data System (ADS)

The submarine Amazon Delta is one major sink in the Amazon source-to-sink system. It is estimated, that the Amazon transports around 1200 Mt/yr. Around 50% of this river sediment load, namely 400 - 800 Mt/yr, is stored on the submarine delta, leading to sedimentation rates of decimeters per year (Nittrouer et al., 1995). The majority of the remaining sediments is deposited on the lower delta plain of the Amazon, but another significant portion is accumulated at the Amapa shoreline or is bypassed further northwestwards. These sediment budget calculations are mainly based on radioisotopic profiles measured at sediment cores in the frame of the AmasSeds project, which was carried out in the 1980ties and 1990ties (Nittrouer et al., 1995). Here we present another approach for calculating mass fluxes in the Amazon system. Within the Project AMADEUS, a cooperation between the MARUM, Bremen, Germany and the University Sao Paulo, Brazil, high-resolution seismic multichannel seismic data and sediment echosounder data (PARASOUND) were collected during Cruise MSM20/3 in February/March 2012. Main emphases of the surveying were set to the forset and bottomset of the delta, where most of the accretion occurs. A special outcome of the new data is the comparison with PARASOUND data collected in 1996 during Cruise M34/4. Due to several crossing points of both data sets it is now possible to carry out direct measurements of the accumulation during these 16 years. Another time horizon is a prominent unconformity spreading over the submarine delta, since the sedimentation on top of this unconformity had been dated to start roughly 100 yrs ago (Sommerfield et al., 1995). Mapping of this unconformity as well as the reflector representing the seafloor of 1996 gives the opportunity to calculate volumes and mass of the sediment stored within the survey area for two different time spans. First calculations show, that the sediment accumulation on the submarine delta since 1996 is significantly enhanced compared to the 100 years before. Also the comparison of the accumulation from 1996 to 2012 with results from the AmasSeds project suggests that the storage of sediments notably increased within the last decades. Even the main survey area of MSM 20/3 comprises just <20% of the area of the entire submarine delta, the mass of sediments accumulated there is in the same order of magnitude as calculated for the complete submarine delta by Nittrouer et al. (1995). Additionally, a notable deposition between 1996 and 2012 is observed outside of the main survey area. These results indicate a considerable increase of the sediment delivery by the Amazon River in recent times instead of just a reorganization of the sediment distribution, which finally may suggest amplified erosion in the Amazon Basin. However, this new calculation gives a valuable contribution to understand the modern Amazon source-to-sink system. References: C. A. Nittrouer, S. A. Kuehl, R. W. Sternberg, A. G. Figueiredo Jr., L. E.C. Faria, 1995, An introduction to the geological significance of sediment transport and accumulation on the Amazon continental shelf, Marine Geology, 125, p. 177-192. C. K. Sommerfield, C. A. Nittrouer, A. G. Figueiredo, Stratigraphic evidence of changes in Amazon shelf sedimentation during the late Holocene, 1995, Marine Geology, 125, p. 351-371.

Schwenk, T.; Haberkern, J.; Mulitza, S.; Chiessi, C. M.

2013-12-01

378

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. PMID:21522169

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

2011-01-01

379

Cytogenetic damage related to low levels of methyl mercury contamination in the Brazilian Amazon  

Microsoft Academic Search

The mercury rejected in the water system, from mining operations and lixiviation of soils after deforesta- tion, is considered to be the main contributors to the contamination of the ecosystem in the Amazon Basin. The objectives of the present study were to examine cytogenetic functions in peripheral lymphocytes within a population living on the banks of the Tapajós River with

MARÚCIA I. M. AMORIM; DONNA MERGLER; MARCELO O. BAHIA; HÉLÈNE DUBEAU; DANIELA MIRANDA; JEAN LEBEL; ROMMEL R. BURBANO; MARC LUCOTTE

2000-01-01

380

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

381

RIVERINE ORGANIC MATTER COMPOSITION AS A FUNCTION OF LAND USE CHANGES, SOUTHWEST AMAZON  

Microsoft Academic Search

We investigated the forms and composition of dissolved and particulate or- ganic matter in rivers of the Ji-ParanaBasin, which is situated at the southern limit of the Amazon lowlands and has experienced extensive deforestation in the last three decades (;35 000 km 2 ). Our objective was to investigate how extensive land-use changes, from forest to cattle pasture, have affected

Marcelo C. Bernardes; Luiz A. Martinelli; Alex V. Krusche; Jack Gudeman; Marcelo Moreira; Reynaldo L. Victoria; Jean P. H. B. Ometto; Maria V. R. Ballester; Anthony K. Aufdenkampe; Jeffrey E. Richey; John I. Hedges

2004-01-01

382

Sorptive fractionation of dissolved organic nitrogen and amino acids onto fine sediments within the Amazon Basin  

Microsoft Academic Search

A consistent observation of river waters in the Amazon Basin and elsewhere is that suspended fine particulate organic matter (FPOM) is compositionally distinct from coexisting dissolved organic matter (DOM). The present article presents experimental results that show that at least some of these compositional patterns are the outcome of selective partitioning of nitrogen-rich DOM components onto mineral surfaces. Nine laboratory

Anthony K. Aufdenkampe; John I. Hedges; Jeffery E. Richey; Alex V. Krusche; Carlos A. Llerena

2001-01-01

383

Numerical study of circulation on the inner Amazon Shelf  

NASA Astrophysics Data System (ADS)

We studied the circulation on the coastal domain of the Amazon Shelf by applying the hydrodynamic module of the estuarine and coastal ocean model and sediment transport. The first barotropic experiment aimed to explain the major bathymetric effects on tides and those generated by anisotropy in sediment distribution. We analyzed the continental shelf response of barotropic tides under realistic bottom stress parametrization ( C d ), considering sediment granulometry obtained from a faciologic map, where river mud deposits and reworked sediments areas are well distinguished, among others classes of sediments. Very low C d values were set in the fluid mud regions off the Amapá coast (1.0 10 - 4), in contrast to values around 3.5 10 - 3 for coarser sediment regions off the Pará coast. Three-dimensional experiments represented the Amazon River discharge and trade winds, combined to barotropic tide influences and induced vertical mixing. The quasiresonant response of the Amazon Shelf to the M2 tide acts on the local hydrodynamics by increasing tidal admittance, along with tidal forcing at the shelf break and extensive fluid mud regions. Harmonic analysis of modeled currents agreed well with the analysis of the AMASSEDS observational data set. Tidal-induced vertical shear provided strong homogenization of threshold waters, which are subject to a kind of hydraulic control due to the topographic steepness. Ahead of the hydraulic jump, the low-salinity plume is disconnected from the bottom and acquires negative vorticity, turning southeastward. Tides act as a generator mechanism and topography, via hydraulic control, acts as a maintainer mechanism for the low-salinity frontal zone positioning. Tidally induced southeastward plume fate is overwhelmed by northwestward trade winds so that they, along with background circulation, probably play the most important role on the plume fate and variability over the Amazon Shelf.

Fontes, Roberto Fioravanti Carelli; Castro, Belmiro Mendes; Beardsley, Robert C.

2008-11-01

384

GPS measurements applied to the leveling of hydrological stations in the Amazon basin  

NASA Astrophysics Data System (ADS)

A common reference altitude for hydrological stations is needed for hydrological and hydrodynamic studies. This is also essential to evaluate the quality of hydrological data derived by the techniques of satellite altimetry. However, defining and maintaining such reference at the scale of the Amazon basin with a centimeter level accuracy is tricky because : - of the difficulty in accessing the hydrological stations and getting GPS data - the network is wide, sparse and far from permanent GPS stations - some of the sites are affected by more than 10 centimeters vertical displacement variations caused by hydrological loading. This poster proposes a method of leveling the hydrological stations of the Amazon basin using GPS data, for that we selected 7 permanent GPS stations in the Amazon basin, 6 stations from RBMC-Brazilian Permanent GPS Network and one water level station equipped with permanent receiver installed by CPRM/IRD on Madeira river where the GRACE results show the peak of vertical displacements in Amazon basin . Their coordinates were estimated weekly using a global network of 32 IGS reference stations and processing double-difference ionospheric-free phase observations. The seasonal hydrological loading signal on each of these GPS station has been derived from the series of coordinates. These sites were then used for: - altitude referencing of the closest hydrological stations - kinematic GPS profile adjustments over rivers of the Amazon Basin - water level comparison to satellite altimetry results GPS data were processed using the GINS scientific software developed by CNES/GRGS.

Moreira, D. M.; Calmant, S.; Perosanz, F.; Souza, A.; Melachroinos, S.; Rotunno, O.; Monteiro, A.

2009-12-01

385

Stratigraphic age, sedimentation rate and source rocks of the Amazon Fan  

NASA Astrophysics Data System (ADS)

The evolution of Amazon Fan, a large sedimentary structure at the Brazilian passive margin, is directly connected with the Andean mountains and the Amazon River development. Sr, Nd and Pb isotopes studies combined with palynological information have been conducted in Late Miocene to Pleistocene section of the Amazon submarine fan to constrain the sedimentary age, source rocks and sedimentation rate of main sedimentary sequences deposited during the period. Age of the sedimentary rocks were inferred from the palynological data and Sr isotope signature from foraminifers, integrated with seismic and drill holes data. The whole section had a very high sedimentation rate with significant increase in the last 3 Ma, from Late Pliocene to present, which it may be related to uplift of the continental margin as a result of isotastic compensation due to load of Amazon Fan sedimentary package deposited from Late Miocene to Early Pliocene and main uplift of the Northern Andes. Although the most foraminifera shells have 87Sr/86Sr ratio in the range of the expected value for the estimated age, there were samples with 87Sr/86Sr ratio lower and higher than those used for the Sr isotope curve. The increase of 87Sr/86Sr ratio is assigned to Amazon River strontium fluxes whereas lower ratios may be due to diagenetic processes or fluid percolation driven by thick sedimentary overload, as much as 10,000 m, in the Amazon submarine fan. Contribution of the Precambrian rocks of the Amazonian Craton versus Andean rocks as source of the sediments for Amazon Fan during its evolution was estimated by the Sm-Nd and Pb isotope data in the pelitic rocks. Nd and Pb isotopes in fine-grained sediments allowed to identify both signal, where contribution Precambrian basement rocks are recognized by Archean and Paleoproterozoic Nd model ages and higher radiogenic Pb signature.

Chemale Junior, Farid; Ayup, Ricardo N.; Barboza, Eduardo; Moura, Candido A. V.

2014-05-01

386

The effect of astaxanthin on resistance of juvenile prawns Macrobrachium nipponense (Decapoda: Palaemonidae) to physical and chemical stress.  

PubMed

In recent years, the use of new scientific techniques has effectively improved aquaculture production processes. Astaxanthin has various properties in aquaculture and its antioxidant benefits have been closely related to stress resistance; besides, it is an essential factor for growth in many crustaceans and fish. The objective of this study was to evaluate the resistance of prawn (Macrobrachium nipponense) fed diets containing different amounts of astaxanthin (AX) to the shock and stress of different physicochemical environments. A 70-day trial was conducted to evaluate the effect of supplementation of a source of astaxanthin (Carophyll Pink, 10% astaxanthin, w/w, Hoffman-La Roche, Switzerland) at various levels in the diet of M. nipponense juveniles. Four dry diets were prepared: AX0 without astaxanthin, AX50 with 50 mg/kg, AX100 with 100 mg/kg, and AX150 with 150 mg/kg astaxanthin. The feeding trial was conducted in a recirculation water system consisting of 12 fiberglass tanks (1000L) used for holding prawns. Three replicate aquaria were initially stocked with 36 org/m2 per tank. During the trial, prawns were maintained on a 12:12-h light:dark photoperiod with an ordinary incandescent lamp, and the water quality parameters were maintained as follows: water temperature, 25-26°C; salinity, 1 g/L; pH, 8.5-8.8; dissolved oxygen, 6.0-6.5 mg/L; and ammonia-nitrogen, 0.05 mg/L. Incorporation of AX, production output, and physiological condition were recorded after 10 weeks of feeding. At the end of the growing period, the prawns were exposed to thermal shock (0°C), ammonia (0.75 mg/L), and reduced oxygen (0.5 mg/L). The time to lethargy and the time to complete death of the prawns were recorded. The results showed that control prawns had the shortest time to lethargy and death compared with prawns subjected to the other treatments. The results of this study have shown that the amount of muscle tissue and gill carotenoids in prawn fed with an AX150 diet showed greater reduction than those exposed to other treatments. It is possible that higher levels of astaxanthin in the body under oxygen reduction stress can be beneficial for prawns. These results suggest that male prawns showed lethargy earlier than females, and the percentage of carotenoid reduction in muscle and gill tissues was higher in males. PMID:25720170

Tizkar, Babak; Seidavi, Alireza; Ponce-Palafox, Jesús Trinidad; Pourashoori, Parastoo

2014-12-01

387

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

388

Repeat-Pass Multi-Temporal Interferometric SAR Coherence Variations with Amazon Floodplain and Lake Habitats  

NASA Astrophysics Data System (ADS)

Monitoring discharge in the main channels of rivers and upland tributaries as well as storage changes in floodplain lakes is necessary for understanding flooding hazards, methane production, sediment transport, and nutrient exchange. Interferometric processing of synthetic aperture radar (SAR) data may enable hydrologists to detect environmental and ecological changes in hydrological systems over space and time. An aim of our experiments is to characterize interferometric SAR coherence variations that occur in Amazon aquatic habitats. We analyze coherence variations in JERS-1 data at three central Amazon sites; Lake Balbina, the Cabaliana floodplain, and the confluence of the Purus and Amazon rivers. Because radar pulse interactions with inundated vegetation typically follow a double-bounce travel path which returns energy to the antenna, coherence will vary with vegetation type, physical baseline, and temporal baseline. Balbina's vegetation consists mostly of forest and inundated trunks of dead, leafless trees as opposed to Cabaliana and Amazon- Purus (dominated by flooded forests), thus it serves to isolate the vegetation signal. Coherence variations with baselines were determined from 253 interferograms at Balbina, 210 at Calbaliana, and 153 at Purus. The average temporal and perpendicular baselines (mean std.) are 574 394 days and 1708 1159 m at Balbina, 637 435 days and 1381 981 m at Cabaliana, and 587 425 days and 1430 964 m at Purus. Balbina has a stronger coherence than either Cabaliana or Amazon-Purus. With results of Mann-Whitney statistical tests, Balbina has a difference between terre-firme and flooded coherence values plotted with perpendicular baseline but Cabaliana and Amazon-Purus do not show this difference. Balbina has a linearly decreasing trend in coherence plotted with temporal baseline whereas Cabaliana and Amazon-Purus have a steep drop-off, non- linear change. A strong annual periodicity is evident on power spectrums of the coherence values for Cabaliana and Amazon-Purus, but not in Balbina and is likely an indicator of the annual Amazon flood wave. Each ecological habitat is delineated in the Balbina coherence values plotted with temporal baseline, but only during high water and time-periods less than 2 years is such delineation visible in the Cabaliana and Amazon-Purus regions. Taken together, these observations suggest terre-firme does not have a seasonal variation whereas flooded areas vary with the season.

Jung, H.; Alsdorf, D.

2006-12-01

389

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

390

Influence of bilateral eyestalk ablation on gonads of fresh water prawn, Macrobrachium dayanum.  

PubMed

The study was carried out in laboratory for one month to know the effect of bilateral eyestalk ablation on gonads of Macrobrachium dayanum. Healthy specimens of Macrobrachium dayanum in the size group of (4-6 cm in length) were taken for the experiment. The eyestalk ablation was done by cutting away the eyestalks from their bases with sterilized scissor. The results here obtained indicated positive effects of eyestalk ablation on ovary and testes of Macrobrachium dayanum. The histological details of the female prawns which were ablated showed post-vitellogenic oocytes; where as unablated females prawn never developed beyond pre-vitellogenic oocytes. Similarly in males, testes showed pronounced development of different cells as compared to unablated ones. Fully developed spermatozoa were seen in ablated ones. Gonadosomatic studies also showed that ovarian and testicular cells developed better as compared to control and these findings suggest the fact that the eyestalks of M. dayanum contain ovary and testis inhibiting factors. PMID:25204053

Pervaiz, Pervaiz Ahmed; Sikdar, Malabika

2014-09-01

391

Effect of Densities and Culture Systems on Growth, Survival, Yield, and Economic Return of Freshwater Prawn, Macrobrachium rosenbergiiFarming in the Rice Field in the Mekong Delta, Vietnam  

Microsoft Academic Search

Postlarvae of Macrobrachium rosenbergii (de Man 1879) were stocked at 2, 4, and 6 postlarvae (PL)\\/m into rice fields under two culture systems, the integrated and the rotational prawn-rice system. Prawn was fed pellet feed twice daily. The growth of Macrobrachium rosenbergii decreased at higher stocking densities. Prawns in the rotational system grew faster than those in the integrated system.

Lam My Lan; Jean-Claude Micha; Duong Nhut Long; Pham Truong Yen

2006-01-01

392

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

E-print Network

~ g of 20-hydroxyecdysone were injected onto the HPLC column. Fractions were collected from 5 to 18 min. , evaporated by vacuum centrifugation, and assayed. Data from three runs are shown in Figure 10. It is clear that. both ecdysone and 20... of labeled and unlabeled ecdysone through purification. Experiment 49: Ecdysteroid titer of prawn carcasses with determination of recovery. 38 39 TABLE 5. Experiment 410: HPLC analysis of zone E from TLC separations 45 TABLE 6. Experiment iI11...

Newitt, Richard Allen

1981-01-01

393

Identification of the major allergen of Macrobrachium rosenbergii (giant freshwater prawn)  

PubMed Central

Objective To characterize the major allergens of Macrobrachium rosenbergii (giant freshwater prawn). Methods Raw and cooked extracts of the giant freshwater prawn were prepared. The IgE reactivity pattern was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting technique with the sera of 20 skin prick test (SPT) positive patients. The major allergen identified was then characterized using the proteomics approach involving a combination of two-dimensional (2-DE) electrophoresis, mass spectrometry and bioinformatics tools. Results SDS-PAGE of the raw extract showed 23 protein bands (15–250 kDa) but those ranging from 40 to 100 kDa were not found in the cooked extract. From immunoblotting experiments, raw and cooked extracts demonstrated 11 and 5 IgE-binding proteins, respectively, with a molecular mass ranging from 15 to 155 kDa. A heat-resistant 36 kDa protein was identified as the major allergen of both extracts. In addition, a 42 kDa heat-sensitive protein was shown to be a major allergen of the raw extract. The 2-DE gel fractionated the prawn proteins to more than 50 different protein spots. Of these, 10 spots showed specific IgE reactivity with patients' sera. Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis led to identification of 2 important allergens, tropomyosin and arginine kinase. Conclusions It can be concluded that the availability of such allergens would help in component-based diagnosis and therapy of prawn allergies. PMID:23569834

Yadzir, Zailatul Hani Mohamad; Misnan, Rosmilah; Abdullah, Noormalin; Bakhtiar, Faizal; Arip, Masita; Murad, Shahnaz

2012-01-01

394

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

395

Quantification of lectin in freshwater prawn ( Macrobrachium rosenbergii) hemolymph by ELISA  

Microsoft Academic Search

An enzyme-linked immunoabsorbent assay was developed to quantify the lectin present in the hemolymph of the freshwater prawn Macrobrachium rosenbergii. This method involves the use of murine monoclonal IgG1 with ? light chain (designated as 3G1) antibodies raised against the purified lectin, the assay that we developed recognized as little as 30 ng\\/ml of lectin, and was used to measure

Concepción Agundis; Ali Pereyra; Roberto Zenteno; Colette Brassart; Claudia Sierra; Lorena Vazquez; Edgar Zenteno

2000-01-01

396

Involvement of opioid peptides in the regulation of reproduction in the prawn Penaeus indicus  

NASA Astrophysics Data System (ADS)

The possible involvement of an endogenous opioid system in the regulation of ovarian development in the prawn Penaeus indicus was investigated. Injection of leucine-enkephalin significantly increased the ovarian index and oocyte diameter in a dose-dependent manner. In contrast, injection of methionine-enkephalin significantly decreased the ovarian index and oocyte diameters. These results provide evidence to support the hypothesis that an opioid system is involved in the regulation of reproduction in crustaceans.

Sreenivasula Reddy, P.

397

Transcriptomics of a Giant Freshwater Prawn (Macrobrachium rosenbergii): De Novo Assembly, Annotation and Marker Discovery  

Microsoft Academic Search

BackgroundGiant freshwater prawn (Macrobrachium rosenbergii or GFP), is the most economically important freshwater crustacean species. However, as little is known about its genome, 454 pyrosequencing of cDNA was undertaken to characterise its transcriptome and identify genes important for growth.Methodology and Principal FindingsA collection of 787,731 sequence reads (244.37 Mb) obtained from 454 pyrosequencing analysis of cDNA prepared from muscle, ovary

Hyungtaek Jung; Russell E. Lyons; Hung Dinh; David A. Hurwood; Sean McWilliam; Peter B. Mather

2011-01-01

398

Challenges in understanding the sources of bioaccumulated metals in biota inhabiting turbid river systems.  

PubMed

Bioaccumulation of As, Cd, Cu, Pb and Zn by Macrobrachium prawns was observed to occur in the Strickland River downstream of a gold mine at Porgera, Papua New Guinea. This was despite the total metal concentrations of waters and sediments indicating no difference from reference sites within tributaries. To provide information on potential sources and bioavailability of metals to prawns, an extensive range of analyses were made on waters, suspended solids, deposited sediments and plant materials within the river system. Dissolved metal concentrations were mostly sub-micrograms per liter and no major differences existed in concentrations or speciation between sites within the Strickland River or its tributaries. Similarly, no differences were detected between sites for total or dilute acid-extractable metal concentrations in bed sediments and plant materials, which may be ingested by the prawns. However, the rivers in this region are highly turbid and the dilute acid-extractable cadmium and zinc concentrations in suspended solids were greater at sites in the Strickland River than at sites in tributaries. The results indicated that mine-derived inputs increased the proportion of these forms of metals or metalloids in the Strickland River. These less strongly bound metals and metalloids would be more bioavailable to the prawns via the dietary pathway. The results highlighted many of the difficulties in using routine monitoring data without information on metal speciation to describe metal uptake and predict potential effects when concentrations are low and similar to background. The study indicated that the monitoring of contaminant concentrations in organisms that integrate the exposure from multiple exposure routes and durations may often be more effective for detecting impacts than intermittent monitoring of contaminants in waters and sediments. PMID:24014223

Cresswell, Tom; Smith, Ross E W; Simpson, Stuart L

2014-02-01

399

Central Amazon Floodplain Hydrodynamics  

NASA Astrophysics Data System (ADS)

Amazon floodplain wetlands contain high biological diversity for which the flow regime, particularly the flood-pulse, provides the driving force. Surface water flow is recognized as the key factor in the establishment and maintenance of wetland ecosystems and their functioning, exerting a strong control on channel formation and determining the spatial and temporal complexity of wetland habitats. However, the hydrodynamics of seasonally flooded wetlands in the Amazon basin remains poorly quantified through ground observations, satellite observations or modelling. In this research, fieldwork was conducted between March and August 2012 for 850 km^{2} of várzea floodplain to the south of a 75 km reach of the Rio Solimões, downstream (east) of the confluence with the Rio Purus. The primary aim of this was to collect ground-based measurements of surface water flows from mid-rising, through high-water to mid-falling flood conditions to allow a detailed picture of floodplain hydrodynamics to be constructed. Four 10-day periods of fieldwork were completed, during which measurements were taken at 42 locations along the floodplain channel network and in floodplain lakes, together with main channel measurements on the Solimões and Purus. Measurements were obtained of: (i) flow rates along floodplain channels, using an Acoustic Current Doppler Profiler (ADCP); (ii) runoff from terra firma via measurement of flows out of ria lakes at the southern edge of the floodplain; (iii) water conductivity; and (iv) suspended sediment concentrations. Overbank flow rates from the Rio Solimões and Rio Purus into the floodplain forest were also obtained using a current meter at several locations during high water. In addition, floodplain channel and lake depths were obtained using continuous recording of sonar connected to a Global Positioning System, enabling the estimation of bathymetry. Using these measurements, detailed hydrodynamic maps of the floodplain were produced from mid-rising to mid-falling flood stages. Initial results show that floodplain channels play an important role in floodplain hydrodynamics, carrying the bulk of flood water into the floodplain during rising water. Once main-channel water levels are above-bankfull, overbank flow directly into the floodplain forest becomes significant. At high-water, the flow rate out of the Purus along the major floodplain channel was 2,200 m^{3}s^{-1}, representing around 10% of the total Purus channel flow ( 23,000 m^{3}s^{-1} at Beruri). In addition, an estimated 2,000 - 4,000 m^{3}s^{-1} of overbank flow occurred from the lower Purus into the floodplain. Floodplain channel flow from the Solimões was less significant than from the Purus at less than 1,000 m^{3}s^{-1}, under 1% of Solimões channel flow ( 116,000 m^{3}s^{-1} upstream of the Purus); however overbank flow into the floodplain forest may have been as much as 10,000 m^{3}s^{-1} along the study reach. Terra firma runoff, measured at the outflows of ria lakes, contributed an insignificant amount of flow during the measurement periods. The first-order estimate of flow through the floodplain area during high water was 15,000 to 17,000 m^{3}s^{-1} (an average of 17.6 to 20.0 m^{3}s^{-1} per km^{2}), with 30-40% of the flow contributed by the Purus.

Wilson, M. D.; Vega, M. C.; Forsberg, B. R.

2012-12-01

400

Jotï ecogony, Venezuelan Amazon  

NASA Astrophysics Data System (ADS)

The current environmental crisis permeates the discourse and concerns of people all over the world. Consideration of diverse environmental ethics showing the alternative ways in which people conceptualize and relate to nature and natural resources are critical for bringing about more sustainable human behaviors. After a brief review of Western historical notions of nature, this work explores the ecogony, or causal reasons, that trigger the behavior of the Jotï, an Amerindian people of the Venezuelan Amazon, with other entities and the forest that they inhabit. The analysis presented synthesizes 15 years of transdisciplinary ethno-ecological research comprising quantitative and qualitative methods (collection of herbarium voucher specimens, floristic inventories in forest plots, structured interviews focused on plot vegetation, semi-structured interviews of life-histories, participant observation, time allocation studies, food resource accounting, focal person following observations, garden crop inventories and censuses, mapping of wild resource harvest locations, among others). Jotï pragmatic and ideological tenets generate a distinctive environmental ethics based on ecogonic nodes. Notions of interdependence, humanity and person are articulated on a daily basis through several dynamics: (1) hyper-awareness of all living things’ dependence on each other and other elements of the biophysical environment at macroscales and microscales, (2) the construction of human spiritual, conscious, physical and agentive constituents from a variety of diverse botanical and zoological species and mineral components of their homeland, and (3) an understanding of the aggregate surroundings, including a significant portion of the biotic and abiotic components, as potential subjects with awareness, creativity and moral stances. This condition of interdependence confers rights and duties on all the parts. Jotï horizontal communications with and among life-forms sustain their condition as committed actors in the configuration of the forests that they inhabit.

Zent, Egleé L.

2013-03-01

401

Acute toxicity of organochlorine insecticide endosulfan to the giant freshwater prawn Macrobrochium rosenbergii  

NASA Astrophysics Data System (ADS)

Endosulfan, an organochlorine pesticide, is highly toxic and effective at controlling pests in agriculture, horticulture, and public health programs. In this study, static bioassays were used to evaluate the toxicity of endosulfan to freshwater prawns ( Macrobrachium rosenbergii) of various lengths (1.5±0.03, 4±0.08, and 7±0.06 cm). Additionally, the activities of peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase, acetylcholinesterase (AChE), and Na+/K+-ATPase were analyzed to reflect the effects of endosulfan exposure. The 96 h LC50 of endosulfan for prawns 1.5, 4, and 7 cm long were 1.86, 4.53, and 6.09 ?g/L, respectively, improved tolerance to endosulfan with growth. The POD activities of test organisms exposed to low concentrations of endosulfan were inhibited, indicating the presence of oxygen damaged tissue. Moreover, a notable decrease in AChE activity was observed due to overstimulation of neurotransmission, which might result in abnormal behavior. The effect caused by endosulfan on phosphatase production in the hepatopancreas of prawns 1.5, 4, and 7 cm long was different because the ability of nonspecific immune regulation increased with growth. The 96 h LC50 values obtained in this study could be used in the formulation of water-quality criteria in China. Moreover, the changes in enzymes activities of M. rosenbergii under stress of endosulfan could be applied in the establishment of early warning indicators for bio-safety.

Dai, Xilin; Xiong, Zhaodi; Xie, Jian; Ding, Fujiang

2014-01-01

402

Nutrient budgets and effluent characteristics in giant freshwater prawn (Macrobrachium rosenbergii) culture ponds.  

PubMed

It is important to understand nutrient budgets of aquaculture practices for efficiency of input resources and to utilize all output nutrient sources. The aim of the present study was to develop a nutrient budget for giant freshwater prawn (Macrobrachium rosenbergii) culture ponds. The study was conducted in farmer's ponds (0.25-0.5 ha) of Odisha, India, and the results showed that feed accounted 97% total nitrogen (N), 98.7% total phosphorus (P) and 90% total organic carbon (OC), respectively. The harvested prawn accounted for recovery of 37% N, 10% P and 15% OC, respectively. The N, P and OC accumulated in sediment were 52%, 76%, and 65%, respectively. Nutrient loads in the effluents were 2.22 ± 0.66 kg inorganic N, 0.40 ± 0.15 kg P, and 21.01 ± 6.4 kg OC per ton of prawn production. The present study implicated that high nutrient values observed in both water and sediment provide important opportunities for nutrient reuse through pond sediment applications to croplands as an organic manure, as well as pond water irrigation to crops as a "liquid fertilizer". PMID:24522829

Adhikari, Subhendu; Sahu, Bharat Chandra; Mahapatra, Abhijit S; Dey, Lambodar

2014-05-01

403

Identification and function of 11 Rab GTPases in giant freshwater prawn Macrobrachium rosenbergii.  

PubMed

Rab GTPases, members of the Ras-like GTPase superfamily, are central elements in endocytic membrane trafficking. However, little is known of the Rab genes in the giant freshwater prawn Macrobrachium rosenbergii. In this study, 11 Rab genes were identified from M. rosenbergii. All MrRabs have a RAB domain. Phylogenetic analysis showed that these 11 MrRabs were divided into different groups. The MrRab genes were ubiquitously expressed in heart, hemocytes, hepatopancreas, gills, stomach, and intestines. Real-time polymerase chain reaction revealed that the MrRab genes were significantly upregulated by white spot syndrome virus (WSSV) in the prawns, indicating that MrRabs might play an important role in innate immune response against WSSV. Moreover, after challenge with Vibrio parahaemolyticus, the expression levels of all MrRabs in the hepatopancreas were also upregulated, which might indicated the involvement of MrRabs in prawns antibacterial immunity. In all, these preliminary results showed that MrRabs were involved in innate immunity of M. rosenbergii. PMID:25542378

Huang, Ying; Ren, Qian

2015-03-01