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Sample records for amazon river prawn

  1. Amazon River

    Atmospheric Science Data Center

    2013-04-17

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

  2. 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...

  3. The Amazon, measuring a mighty river

    USGS Publications Warehouse

    U.S. Geological Survey

    1967-01-01

    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.

  4. Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host

    PubMed Central

    Sokolow, Susanne H.; Huttinger, Elizabeth; Jouanard, Nicolas; Hsieh, Michael H.; Lafferty, Kevin D.; Kuris, Armand M.; Riveau, Gilles; Senghor, Simon; Thiam, Cheikh; N’Diaye, Alassane; Faye, Djibril Sarr; De Leo, Giulio A.

    2015-01-01

    Eliminating human parasitic disease often requires interrupting complex transmission pathways. Even when drugs to treat people are available, disease control can be difficult if the parasite can persist in nonhuman hosts. Here, we show that restoration of a natural predator of a parasite’s intermediate hosts may enhance drug-based schistosomiasis control. Our study site was the Senegal River Basin, where villagers suffered a massive outbreak and persistent epidemic after the 1986 completion of the Diama Dam. The dam blocked the annual migration of native river prawns (Macrobrachium vollenhoveni) that are voracious predators of the snail intermediate hosts for schistosomiasis. We tested schistosomiasis control by reintroduced river prawns in a before-after-control-impact field experiment that tracked parasitism in snails and people at two matched villages after prawns were stocked at one village’s river access point. The abundance of infected snails was 80% lower at that village, presumably because prawn predation reduced the abundance and average life span of latently infected snails. As expected from a reduction in infected snails, human schistosomiasis prevalence was 18 ± 5% lower and egg burden was 50 ± 8% lower at the prawn-stocking village compared with the control village. In a mathematical model of the system, stocking prawns, coupled with infrequent mass drug treatment, eliminates schistosomiasis from high-transmission sites. We conclude that restoring river prawns could be a novel contribution to controlling, or eliminating, schistosomiasis. PMID:26195752

  5. Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host

    USGS Publications Warehouse

    Sokolow, Susanne H.; Huttinger, Elizabeth; Jouanard, Nicolas; Hsieh, Michael H.; Lafferty, Kevin D.; Kuris, Armand M.; Riveau, Gilles; Senghor, Simon; Thiam, Cheikh; D'Diaye, Alassane; Faye, Djibril Sarr; De Leo, Giulio A.

    2015-01-01

    Eliminating human parasitic disease often requires interrupting complex transmission pathways. Even when drugs to treat people are available, disease control can be difficult if the parasite can persist in nonhuman hosts. Here, we show that restoration of a natural predator of a parasite’s intermediate hosts may enhance drug-based schistosomiasis control. Our study site was the Senegal River Basin, where villagers suffered a massive outbreak and persistent epidemic after the 1986 completion of the Diama Dam. The dam blocked the annual migration of native river prawns (Macrobrachium vollenhoveni) that are voracious predators of the snail intermediate hosts for schistosomiasis. We tested schistosomiasis control by reintroduced river prawns in a before-after-control-impact field experiment that tracked parasitism in snails and people at two matched villages after prawns were stocked at one village’s river access point. The abundance of infected snails was 80% lower at that village, presumably because prawn predation reduced the abundance and average life span of latently infected snails. As expected from a reduction in infected snails, human schistosomiasis prevalence was 18 ± 5% lower and egg burden was 50 ± 8% lower at the prawn-stocking village compared with the control village. In a mathematical model of the system, stocking prawns, coupled with infrequent mass drug treatment, eliminates schistosomiasis from high-transmission sites. We conclude that restoring river prawns could be a novel contribution to controlling, or eliminating, schistosomiasis.                            

  6. Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host.

    PubMed

    Sokolow, Susanne H; Huttinger, Elizabeth; Jouanard, Nicolas; Hsieh, Michael H; Lafferty, Kevin D; Kuris, Armand M; Riveau, Gilles; Senghor, Simon; Thiam, Cheikh; N'Diaye, Alassane; Faye, Djibril Sarr; De Leo, Giulio A

    2015-08-01

    Eliminating human parasitic disease often requires interrupting complex transmission pathways. Even when drugs to treat people are available, disease control can be difficult if the parasite can persist in nonhuman hosts. Here, we show that restoration of a natural predator of a parasite's intermediate hosts may enhance drug-based schistosomiasis control. Our study site was the Senegal River Basin, where villagers suffered a massive outbreak and persistent epidemic after the 1986 completion of the Diama Dam. The dam blocked the annual migration of native river prawns (Macrobrachium vollenhoveni) that are voracious predators of the snail intermediate hosts for schistosomiasis. We tested schistosomiasis control by reintroduced river prawns in a before-after-control-impact field experiment that tracked parasitism in snails and people at two matched villages after prawns were stocked at one village's river access point. The abundance of infected snails was 80% lower at that village, presumably because prawn predation reduced the abundance and average life span of latently infected snails. As expected from a reduction in infected snails, human schistosomiasis prevalence was 18 ± 5% lower and egg burden was 50 ± 8% lower at the prawn-stocking village compared with the control village. In a mathematical model of the system, stocking prawns, coupled with infrequent mass drug treatment, eliminates schistosomiasis from high-transmission sites. We conclude that restoring river prawns could be a novel contribution to controlling, or eliminating, schistosomiasis. PMID:26195752

  7. Confluence of the Amazon and Topajos Rivers, Brazil, South America

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view shows the confluence of the Amazon and the Topajos Rivers at Santarem, Brazil (2.0S, 55.0W). The Am,azon flows from lower left to upper right of the photo. Below the river juncture of the Amazon and Tapajos, there is considerable deforestation activity along the Trans-Amazon Highway.

  8. Growth and antioxidant status of oriental river prawn Macrobrachium nipponense fed with diets containing vitamin E

    NASA Astrophysics Data System (ADS)

    Zhao, Weihong; Wang, Zisheng; Yu, Yebing; Qi, Zhitao; Lü, Linlan; Zhang, Yuxia; Lü, Fu

    2016-05-01

    A feeding trial was carried out to investigate the dietary vitamin E requirement of the oriental river prawn Macrobrachium nipponense (weight of 0.3-0.4 g) and its effect role on antioxidant activity. Prawns were fed with seven levels of vitamin E (0, 25, 50, 75, 100, 200, and 400 mg/kg diet) for 60 days. The results show that dietary vitamin E supplementation could significantly increased the prawn weight ( P < 0.05). The activity of superoxide dismutase (SOD) in the hepatopancreas was significantly higher in prawns fed with diets supplemented with ≤75 mg/kg vitamin E than in those fed with diets supplemented with 100-400 mg/kg vitamin E ( P < 0.05). The activity of catalase (CAT) in the hepatopancreas decreased significantly as dietary vitamin E supplementation increased ( P < 0.05), and no significant difference was detected in glutathione peroxidase (GSH-Px) activity between different dietary groups ( P >0.05). The contents of vitamin E in the hepatopancreas and in the muscle increased with increasing dietary vitamin E. There was a linear correlation between the vitamin E level in diet and that in muscle, and between the vitamin E level in diet and that in the hepatopancreas. All the above results indicated that dietary vitamin E can be stored in the hepatopancreas and muscle and lower both the activities of SOD and CAT in the hepatopancreas, suggesting that it is a potential antioxidant in M. nipponense. Broken line analysis conducted on the weight gains of prawns in each diet group showed that the dietary vitamin E requirement for maximum growth is 94.10 mg/kg.

  9. Growth and antioxidant status of oriental river prawn Macrobrachium nipponense fed with diets containing vitamin E

    NASA Astrophysics Data System (ADS)

    Zhao, Weihong; Wang, Zisheng; Yu, Yebing; Qi, Zhitao; Lü, Linlan; Zhang, Yuxia; Lü, Fu

    2015-11-01

    A feeding trial was carried out to investigate the dietary vitamin E requirement of the oriental river prawn Macrobrachium nipponense (weight of 0.3-0.4 g) and its effect role on antioxidant activity. Prawns were fed with seven levels of vitamin E (0, 25, 50, 75, 100, 200, and 400 mg/kg diet) for 60 days. The results show that dietary vitamin E supplementation could significantly increased the prawn weight (P<0.05). The activity of superoxide dismutase (SOD) in the hepatopancreas was significantly higher in prawns fed with diets supplemented with ≤75 mg/kg vitamin E than in those fed with diets supplemented with 100-400 mg/kg vitamin E (P<0.05). The activity of catalase (CAT) in the hepatopancreas decreased significantly as dietary vitamin E supplementation increased (P<0.05), and no significant difference was detected in glutathione peroxidase (GSH-Px) activity between different dietary groups (P>0.05). The contents of vitamin E in the hepatopancreas and in the muscle increased with increasing dietary vitamin E. There was a linear correlation between the vitamin E level in diet and that in muscle, and between the vitamin E level in diet and that in the hepatopancreas. All the above results indicated that dietary vitamin E can be stored in the hepatopancreas and muscle and lower both the activities of SOD and CAT in the hepatopancreas, suggesting that it is a potential antioxidant in M. nipponense. Broken line analysis conducted on the weight gains of prawns in each diet group showed that the dietary vitamin E requirement for maximum growth is 94.10 mg/kg.

  10. Population Structure and Historical Demography of the Oriental River Prawn (Macrobrachium nipponense) in Taiwan

    PubMed Central

    Chu, Ta-Jen; Wang, Daryi; Lee, Ying-Chou; Tzeng, Tzong-Der

    2015-01-01

    The oriental river prawn (Macrobrachium nipponense) is a non-obligatory amphidromous prawn, and it has a wide distribution covering almost the entire Taiwan. Mitochondrial DNA fragment sequences of the cytochrome oxidase subunit I (COI) and 16S rRNA were combined and used to elucidate the population structure and historical demography of oriental river prawn in Taiwan. A total of 202 individuals from six reservoirs and three estuaries were separately collected. Nucleotide diversity (π) of all populations was 0.01217, with values ranging from 0.00188 (Shihmen Reservoir, SMR, northern Taiwan) to 0.01425 (Mingte Reservoir, MTR, west-central Taiwan). All 76 haplotypes were divided into 2 lineages: lineage A included individuals from all sampling areas except SMR, and lineage B included specimens from all sampling locations except Chengching Lake Reservoir (CLR) and Liyu Lake Reservoir (LLR). All FST values among nine populations were significantly different except the one between Jhonggang River Estuary (JGE, west-central Taiwan) and Kaoping River Estuary (KPE, southern Taiwan). UPGMA tree of nine populations showed two main groups: the first group included the SMR and Tamsui River Estuary (TSE) (both located northern Taiwan), and the second one included the other seven populations (west-central, southern and eastern Taiwan). Demographic analyses implied a population expansion occurred during the recent history of the species. The dispersal route of this species might be from China to west-central and west-southern Taiwan, and then the part individuals belonging to lineage A and B dispersed southerly and northerly, respectively. And then part individuals in west-central Taiwan fell back to and stay at estuaries as the sea level rose about 18,000 years ago. PMID:26716687

  11. Population Structure and Historical Demography of the Oriental River Prawn (Macrobrachium nipponense) in Taiwan.

    PubMed

    Chen, Po-Cheng; Shih, Chun-Han; Chu, Ta-Jen; Wang, Daryi; Lee, Ying-Chou; Tzeng, Tzong-Der

    2015-01-01

    The oriental river prawn (Macrobrachium nipponense) is a non-obligatory amphidromous prawn, and it has a wide distribution covering almost the entire Taiwan. Mitochondrial DNA fragment sequences of the cytochrome oxidase subunit I (COI) and 16S rRNA were combined and used to elucidate the population structure and historical demography of oriental river prawn in Taiwan. A total of 202 individuals from six reservoirs and three estuaries were separately collected. Nucleotide diversity (π) of all populations was 0.01217, with values ranging from 0.00188 (Shihmen Reservoir, SMR, northern Taiwan) to 0.01425 (Mingte Reservoir, MTR, west-central Taiwan). All 76 haplotypes were divided into 2 lineages: lineage A included individuals from all sampling areas except SMR, and lineage B included specimens from all sampling locations except Chengching Lake Reservoir (CLR) and Liyu Lake Reservoir (LLR). All FST values among nine populations were significantly different except the one between Jhonggang River Estuary (JGE, west-central Taiwan) and Kaoping River Estuary (KPE, southern Taiwan). UPGMA tree of nine populations showed two main groups: the first group included the SMR and Tamsui River Estuary (TSE) (both located northern Taiwan), and the second one included the other seven populations (west-central, southern and eastern Taiwan). Demographic analyses implied a population expansion occurred during the recent history of the species. The dispersal route of this species might be from China to west-central and west-southern Taiwan, and then the part individuals belonging to lineage A and B dispersed southerly and northerly, respectively. And then part individuals in west-central Taiwan fell back to and stay at estuaries as the sea level rose about 18,000 years ago. PMID:26716687

  12. Size distribution of Amazon River bed sediment

    USGS Publications Warehouse

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

    1980-01-01

    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.

  13. Effects of Host Phylogeny and Habitats on Gut Microbiomes of Oriental River Prawn (Macrobrachium nipponense).

    PubMed

    Tzeng, Tzong-Der; Pao, Yueh-Yang; Chen, Po-Cheng; Weng, Francis Cheng-Hsuan; Jean, Wen Dar; Wang, Daryi

    2015-01-01

    The gut microbial community is one of the richest and most complex ecosystems on earth, and the intestinal microbes play an important role in host development and health. Next generation sequencing approaches, which rapidly produce millions of short reads that enable the investigation on a culture independent basis, are now popular for exploring microbial community. Currently, the gut microbiome in fresh water shrimp is unexplored. To explore gut microbiomes of the oriental river prawn (Macrobrachium nipponense) and investigate the effects of host genetics and habitats on the microbial composition, 454 pyrosequencing based on the 16S rRNA gene were performed. We collected six groups of samples, including M. nipponense shrimp from two populations, rivers and lakes, and one sister species (M. asperulum) as an out group. We found that Proteobacteria is the major phylum in oriental river prawn, followed by Firmicutes and Actinobacteria. Compositional analysis showed microbial divergence between the two shrimp species is higher than that between the two populations of one shrimp species collected from river and lake. Hierarchical clustering also showed that host genetics had a greater impact on the divergence of gut microbiome than host habitats. This finding was also congruent with the functional prediction from the metagenomic data implying that the two shrimp species still shared the same type of biological functions, reflecting a similar metabolic profile in their gut environments. In conclusion, this study provides the first investigation of the gut microbiome of fresh water shrimp, and supports the hypothesis of host species-specific signatures of bacterial community composition. PMID:26168244

  14. Effects of Host Phylogeny and Habitats on Gut Microbiomes of Oriental River Prawn (Macrobrachium nipponense)

    PubMed Central

    Chen, Po-Cheng; Weng, Francis Cheng-Hsuan; Jean, Wen Dar; Wang, Daryi

    2015-01-01

    The gut microbial community is one of the richest and most complex ecosystems on earth, and the intestinal microbes play an important role in host development and health. Next generation sequencing approaches, which rapidly produce millions of short reads that enable the investigation on a culture independent basis, are now popular for exploring microbial community. Currently, the gut microbiome in fresh water shrimp is unexplored. To explore gut microbiomes of the oriental river prawn (Macrobrachium nipponense) and investigate the effects of host genetics and habitats on the microbial composition, 454 pyrosequencing based on the 16S rRNA gene were performed. We collected six groups of samples, including M. nipponense shrimp from two populations, rivers and lakes, and one sister species (M. asperulum) as an out group. We found that Proteobacteria is the major phylum in oriental river prawn, followed by Firmicutes and Actinobacteria. Compositional analysis showed microbial divergence between the two shrimp species is higher than that between the two populations of one shrimp species collected from river and lake. Hierarchical clustering also showed that host genetics had a greater impact on the divergence of gut microbiome than host habitats. This finding was also congruent with the functional prediction from the metagenomic data implying that the two shrimp species still shared the same type of biological functions, reflecting a similar metabolic profile in their gut environments. In conclusion, this study provides the first investigation of the gut microbiome of fresh water shrimp, and supports the hypothesis of host species-specific signatures of bacterial community composition. PMID:26168244

  15. Amazon River investigations, reconnaissance measurements of July 1963

    USGS Publications Warehouse

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

    1964-01-01

    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.

  16. Radium and barium in the Amazon River system

    SciTech Connect

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

    1984-03-20

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

  17. Molecular characterization of a novel ovary-specific gene fem-1 homolog from the oriental river prawn, Macrobrachium nipponense.

    PubMed

    Ma, Ke-Yi; Liu, Zhi-Qiang; Lin, Jing-Yun; Li, Jia-Le; Qiu, Gao-Feng

    2016-01-10

    The feminization-1 (fem-1) gene is characterized by one of the most common protein-protein interaction motifs, ankyrin repeat motifs, displays many expression patterns in vertebrates and invertebrates, and plays an essential role in the sex-determination/differentiation pathway in Caenorhabditis elegans. In this study, a fem-1 homolog, designated as Mnfem-1, was first cloned from the oriental river prawn Macrobrachium nipponense. The prawn Mnfem-1 gene consists of six exons and five introns. The full-length cDNA (2603bp) of Mnfem-1 contains an open reading frame (ORF) encoding a protein of 622 amino acids. The Mnfem-1 RNA and protein are exclusively expressed in the ovary in adult prawns as revealed by RT-PCR and immunofluorescence analysis, respectively. In situ hybridization results showed that strong positive signals were concentrated at the edge of the previtellogenic and vitellogenic oocyte. During embryogenesis, Mnfem-1 is highly expressed in both unfertilized eggs and embryos at cleavage stage and thereafter dropped to a low level from blastula to zoea, indicating that the Mnfem-1 in early embryos is maternal. After hatching, the Mnfem-1 expression significantly increased in the larvae at length of 2cm, an important stage of sex differentiation. Yeast two hybridization results showed that the Mnfem-1 protein can be potentially interactive with cathepsin L and proteins containing the domains of insulinase, ankyrin or ubiquitin. Our results suggested that Mnfem-1 could have roles in prawn ovarian development and sex determination/differentiation. PMID:26367327

  18. Backwater effects in the Amazon River basin of Brazil

    USGS Publications Warehouse

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

    1991-01-01

    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.

  19. Mouth of the Amazon River as seen from STS-58

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A near-nadir view of the mouth of the Amazon River, that shows all signs of being a relatively healthy system, breathing and exhaling. The well-developed cumulus field over the forested areas on both the north and south sides of the river (the view is slightly to the west) shows that good evapotranspiration is underway.

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

    PubMed Central

    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

    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

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

    PubMed

    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

    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

  2. Complete larval development of the Monkey River Prawn Macrobrachium lar (Palaemonidae) using a novel greenwater technique.

    PubMed

    Lal, Monal M; Seeto, Johnson; Pickering, Timothy D

    2014-01-01

    This study documents the complete larval development of the Monkey River Prawn Macrobrachium lar using a new greenwater rearing technique. Approximately 6,000 larvae were reared for 110 days at an initial stocking density of 1 ind./6 L. Salinity at hatch was 10 ± 2 ppt and progressively increased to 30 ± 2 ppt until decapodids had metamorphosed. Temperature was maintained at 28 ± 0.5°C, pH at 7.8 ± 0.2, DO2 > 6.5 mg/L and NH(4+) and NH3 ≤ 1.5 and ≤0.1 ppm respectively throughout the culture period. Larval development was extended and occurred through 13 zoeal stages, with the first decapodid measuring 6.2 ± 0.63 mm in total length observed after 77 days. 5 decapodids in total were produced, and overall survival to this stage was 0.08%. Overall, the pattern of larval growth shares similarities with those of other Macrobrachium spp. that have a prolonged/normal type of development, and it is likely that larvae underwent mark time moulting which contributed to the lengthened development duration. While this study represents a significant breakthrough in efforts to domesticate M. lar, improvement of larval survival rates and decreased time till metamorphosis are required before it can become fully viable for commercial scale aquaculture. PMID:25332868

  3. Molecular and functional characterization of the vitellogenin receptor in oriental river prawn, Macrobrachium nipponense.

    PubMed

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

    2016-04-01

    A complementary DNA (cDNA) that encodes the vitellogenin receptor (VgR) in the oriental river prawn, Macrobrachium nipponense, was cloned using expressed sequence tag analysis and a rapid amplification of cDNA ends approach. The coding region consists of 5920 base pairs (bp) that encode a 1902 amino acid protein, with a predicted molecular mass of 209kDa. The coding region is flanked by a 45bp 5'-untranslated region (UTR) and a 166bp 3'-UTR. The deduced amino acid sequence of the M. nipponense VgR cDNA had typically conserved domains, such as an extracellular, lipoprotein-binding domain, epidermal growth factor-like and O-glycosylation domains, a transmembrane domain and a short C-terminal, cytosolic tail. Quantitative real-time PCR (qPCR) indicated that Mn-VgR is highly expressed in the female ovary. Expression analysis by qPCR demonstrated the larval and ovarian developmental stage-specific expression pattern. As the ovaries developed, the expression level of Mn-VgR gradually increased during the reproductive cycle (stage I), to reach a peak in stage III. Levels then dropped as a new development cycle was entered after reproduction molting. Eyestalk ablation led to a significant increase in the expression of Mn-VgR during the ovarian development stages (P<0.05), when compared with the eyestalk-intact group. The investigation revealed that eyestalk ablation initially affected Mn-VgR expression and then influenced vitellogenesis. In adult females, VgR RNA interference (RNAi) dramatically delayed the maturation of the ovary, in accordance with the gonad somatic index. In addition, Mn-VgR RNAi led to vitellin depletion in the oocytes and the accumulation of vitellin in the hepatopancreas. PMID:26773480

  4. Suspended sediment dynamics in the Amazon River of Peru

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  5. Artisanal fisheries of the Xingu River basin in Brazilian Amazon.

    PubMed

    Isaac, V J; Almeida, M C; Cruz, R E A; Nunes, L G

    2015-08-01

    The present study characterises the commercial fisheries of the basin of the Xingu River, a major tributary of the Amazon River, between the towns of Gurupá (at the mouth of the Amazon) and São Félix do Xingu. Between April, 2012, and March, 2014, a total of 23,939 fishing trips were recorded, yielding a total production of 1,484 tons of fish, harvested by almost three thousand fishers. The analysis of the catches emphasizes the small-scale and artisanal nature of the region's fisheries, with emphasis on the contribution of the motorised canoes powered by "long-tail" outboard motors. Larger motorboats operate only at the mouth of the Xingu and on the Amazon. Peacock bass (Cichla spp.), croakers (Plagioscion spp.), pacu (a group containing numerous serrasalmid species), aracu (various anostomids), and curimatã (Prochilodus nigricans) together contributed more than 60% of the total catch. Mean catch per unit effort was 18 kg/fisher-1.day-1, which varied among fishing methods (type of vessel and fishing equipment used), river sections, and time of the year. In most cases, yields varied little between years (2012 and 2013). The technical database provided by this study constitutes an important resource for the regulation of the region's fisheries, as well as for the evaluation of future changes resulting from the construction of the Belo Monte dam on the Xingu River. PMID:26691085

  6. Seasonal variations in methane emission from Amazon River and tributaries

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  7. Suspended sediments of the modern Amazon and Orinoco rivers

    USGS Publications Warehouse

    Meade, R.H.

    1994-01-01

    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.

  8. An extensive reef system at the Amazon River mouth.

    PubMed

    Moura, Rodrigo L; Amado-Filho, Gilberto M; Moraes, Fernando C; Brasileiro, Poliana S; Salomon, Paulo S; Mahiques, Michel M; Bastos, Alex C; Almeida, Marcelo G; Silva, Jomar M; Araujo, Beatriz F; Brito, Frederico P; Rangel, Thiago P; Oliveira, Braulio C V; Bahia, Ricardo G; Paranhos, Rodolfo P; Dias, Rodolfo J S; Siegle, Eduardo; Figueiredo, Alberto G; Pereira, Renato C; Leal, Camille V; Hajdu, Eduardo; Asp, Nils E; Gregoracci, Gustavo B; Neumann-Leitão, Sigrid; Yager, Patricia L; Francini-Filho, Ronaldo B; Fróes, Adriana; Campeão, Mariana; Silva, Bruno S; Moreira, Ana P B; Oliveira, Louisi; Soares, Ana C; Araujo, Lais; Oliveira, Nara L; Teixeira, João B; Valle, Rogerio A B; Thompson, Cristiane C; Rezende, Carlos E; Thompson, Fabiano L

    2016-04-01

    Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 10(6)-km(2) plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (~9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes. PMID:27152336

  9. Climatic variability between SST and river discharge at Amazon region

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  10. Prawn Park - Taupo, New Zealand

    SciTech Connect

    Lund, J.W.; Klein, R.

    1995-10-01

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

  11. Identification of five anti-lipopolysaccharide factors in oriental river prawn, Macrobrachium nipponense.

    PubMed

    Wang, Yili; Tang, Ting; Gu, Jihai; Li, Xiang; Yang, Xue; Gao, Xiaobin; Liu, Fengsong; Wang, Jianhui

    2015-10-01

    Anti-lipopolysaccharide factors (ALFs) are a group of antimicrobial peptides (AMPs) with broad-spectrum antimicrobial activities and antiviral activities mainly found in crustaceans and horseshoe crabs. In the present study, we identified 5 ALF expression sequence tags (ESTs) through analysis of the established M. nipponense transcriptome, and cloned their full-length cDNA sequences using rapid amplification of cDNA ends (RACE) method. The 5 ALFs were designated as MnALF1-5, and all of them showed high similarity with their Macrobrachium rosenbergii homologs in the phylogenetic analyses, especially in LPS binding domains. In healthy adult prawns, we found the highest expression of MnALF2 and MnALF4 in haemocytes, and the highest expression of MnALF4 and MnALF3 in intestine. Some isoforms of MnALF were down-regulated but the majority was up-regulated in different prawn tissues upon Aeromonas hydrophila challenge. To conform the expected antimicrobial activities harbored in MnALFs' LPS binding domains, we used a synthesized peptide cMnALF24 that corresponds to the LPS binding domain of MnALF2 as a representative molecule for the antibacterial activity test, and found that cMnALF24 possessed strong and broad-spectrum antibacterial activity against Gram positive and Gram negative bacteria, but no inhibition activity against fungi; Meanwhile, in the hemolytic test, cMnALF24 showed weak hemolysis activities (around 10%) to the rabbit red blood cells at concentrations of 0.67-33.50 μM. This study provides insights into understanding the antibacterial function of ALFs in the innate immunity of freshwater prawn, and reports a peptide that can be a potential drug candidate with good efficacy against bacterial infection and low toxicity to host cells. PMID:26159095

  12. Iron cycling in the Amazon River Basin: the isotopic perspective

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 δ57Fe 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 δ57Fe 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.

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

    PubMed Central

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

    2012-01-01

    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

  14. Amazon River carbon dioxide outgassing fuelled by wetlands

    NASA Astrophysics Data System (ADS)

    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

    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.

  15. Amazon River carbon dioxide outgassing fuelled by wetlands.

    PubMed

    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

    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

  16. An extensive reef system at the Amazon River mouth

    PubMed Central

    Moura, Rodrigo L.; Amado-Filho, Gilberto M.; Moraes, Fernando C.; Brasileiro, Poliana S.; Salomon, Paulo S.; Mahiques, Michel M.; Bastos, Alex C.; Almeida, Marcelo G.; Silva, Jomar M.; Araujo, Beatriz F.; Brito, Frederico P.; Rangel, Thiago P.; Oliveira, Braulio C. V.; Bahia, Ricardo G.; Paranhos, Rodolfo P.; Dias, Rodolfo J. S.; Siegle, Eduardo; Figueiredo, Alberto G.; Pereira, Renato C.; Leal, Camille V.; Hajdu, Eduardo; Asp, Nils E.; Gregoracci, Gustavo B.; Neumann-Leitão, Sigrid; Yager, Patricia L.; Francini-Filho, Ronaldo B.; Fróes, Adriana; Campeão, Mariana; Silva, Bruno S.; Moreira, Ana P. B.; Oliveira, Louisi; Soares, Ana C.; Araujo, Lais; Oliveira, Nara L.; Teixeira, João B.; Valle, Rogerio A. B.; Thompson, Cristiane C.; Rezende, Carlos E.; Thompson, Fabiano L.

    2016-01-01

    Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 106–km2 plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume’s eastward retroflection, conditions the existence of this extensive (~9500 km2) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth–ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes. PMID:27152336

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

    USGS Publications Warehouse

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

    2000-01-01

    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.

  18. Watershed Metabolism Expression in Rivers of the Amazon

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  19. Seasonal variation and environmental influences on juvenile banana prawn ( Penaeus merguiensis) abundance in a subtropical estuary (Logan River) of eastern Australia

    NASA Astrophysics Data System (ADS)

    Meager, J. J.; Vance, D. J.; Loneragan, N. R.; Williamson, I.

    2003-07-01

    Although the life history-environment relationship for juvenile Penaeus merguiensis in tropical regions has been well documented, little is known about the species towards the subtropical limits of its range. Seasonal patterns of abundances of juvenile and postlarval P. merguiensis were studied in the Logan River, a subtropical estuary in eastern Australia from January 1998 to July 2000. Prawns were sampled using a small beam trawl at fortnightly intervals when they were abundant and monthly intervals at other times. The prawns ranged in size from 1.8 to 22 mm in carapace length (CL), with a mean size (±1 SE) of 6.7±0.1 mm CL and were caught at densities of up to 14.2±3.3 prawns m -2. Postlarvae were caught from January to July, with peaks in April and May; and juveniles were abundant from December to June, although this varied between years. The numbers of postlarvae, temperature and rainfall explained 23% of the overall variation in juvenile catches. Temperature and rainfall also explained some of the variation in postlarval catches (9.9%). Recruitment varied considerably between years, and was the highest in years when rainfall was low (1998 and 2000). In general, both the seasonal patterns of catches of postlarval and juvenile P. merguiensis, and environmental processes affecting their abundance were similar to tropical areas. However, one notable difference was that recruitment occurred over a more restricted time period in the Logan River than in tropical regions.

  20. The Amazon River reversal explained by tectonic and surface processes

    NASA Astrophysics Data System (ADS)

    Sacek, V.

    2014-12-01

    The drainage pattern in Amazonia was expressively modified during the mountain building of central and northern Andes. In Early Miocene, the fluvial systems in western Amazonia flowed to the foreland basins and northward to the Caribbean. By Late Miocene the drainage reversal occurred and formed the transcontinental Amazon River, connecting the Andes and the equatorial Atlantic margin. This event is recorded in the stratigraphic evolution of the Foz do Amazonas Basin by the onset of Andean-derived sedimentation. Additionally, an abrupt increase in sedimentation rate after the reversal occurred in the Foz do Amazonas Basin. Based on three-dimensional numerical models that couple surface processes, flexural isostasy and crustal thickening due to orogeny, I concluded that the Miocene drainage reversal can be explained by the flexural and surface processes response to the Andes formation with no need to invoke dynamic topography induced by mantle convection, as previously proposed. I observed that the instant of drainage reversal is directly linked to the rate of crustal thickening in the orogeny, the rate of erosion and, mainly, the efficiency of sediment transport. Moreover, the 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 the Late Miocene-Pliocene sedimentary record. However, the present numerical model fails to fully reproduce the evolution of the Pebas system, a megawetland in western Amazonia that preceded the drainage reversal. Therefore, further investigation is necessary to evaluate the mechanisms that generated and sustained the Pebas system.

  1. Microspatial gene expression patterns in the Amazon River Plume

    PubMed Central

    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

    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

  2. Degradation of terrestrially derived macromolecules in the Amazon River

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed Central

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

    2015-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    1998-06-01

    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, resulting in large differences in the communities of tropical inshore waters. The stomach contents of 2059 predatory fish from the Norman River estuary were analysed over four sampling trips in the wet and dry seasons. The stomachs of 61% (1255 fish) of 54 species contained a total of 6762 g (dry weight) of food, while 39% (804 fish) were empty. Teleosts were the main component of the diet (by dry weight) of 13 of the 22 species analysed, followed by annelids for two species. Five species had only teleosts in their stomachs. Most predator species ate benthic or bentho-pelagic prey, while three species Rhizoprionodon taylori, Scomberoides commersonianusand Leptobrama mulleriate mainly pelagic prey. Although 19 species ate some penaeids, only Polydactylus sheridaniate little else. This species, Lates calcariferand Eleutheronema tetradactylumate 945% of all the penaeid prey and 979% of all the commercially important penaeid prey recorded in the study. Penaeid predation indices (calculated from gillnet catch rates, proportion of penaeids in the diet and a consumption rate of 3% body weight per day) were 023 g of penaeid per net-metre per day for P. sheridani, 015 for L. calcariferand 003 for E. tetradactylum. Commercially important penaeid predation indices were 011, 013 and 001, respectively. These values are intermediate between those previously recorded for the main penaeid predators in other inshore areas of the Gulf of Carpentaria (Embley River estuary and Groote Eylandt).

  5. Molecular cloning and expression analysis of female sterile homeotic gene (fsh) in the oriental river prawn Macrobrachium nipponense.

    PubMed

    Zhang, W Y; Jiang, S F; Xiong, Y W; Fu, H T; Qiao, H; Sun, S M; Gong, Y S; Jin, S B

    2015-01-01

    The gene female sterile homeotic (fsh) plays crucial roles in molecular function, including protein kinase activity and DNA binding, which are involved in biological processes such as terminal region determination and negative regulation of DNA-dependent transcription. Although fsh has been found in Drosophila melanogaster, little is known regarding its expression in crustaceans. In this study, a fsh gene homologue, designated as Mnfsh, was cloned and characterized from the testis of the oriental river prawn, Macrobrachium nipponense, by using EST analysis and the RACE approach for the first time. The full-length cDNA of Mnfsh was 2029 bp, consisting of a 5' UTR of 361 bp, a 3' UTR of 216 bp, and an ORF of 1452 bp encoding 484 amino acids. qRT-PCR analysis showed that the Mnfsh gene was expressed in the testis, ovary, muscle, heart, eyestalk, and abdominal ganglion, with the highest level of expression in the ovary and the lowest in the heart. qRT-PCR analyses showed that the expression levels of Mnfsh mRNA both significantly increased in the zoea stage, the VII larvae, and 1st day post-larvae after metamorphosis. In conclusion, the results of the present study indicate that Mnfsh is an arthropod fsh homologue and probably also plays important roles in embryogenesis, organogenesis, and morphological differentiation of M. nipponense. PMID:25966204

  6. Characterization of the male-specific lethal 3 gene in the oriental river prawn, Macrobrachium nipponense.

    PubMed

    Zhang, Y P; Sun, S M; Fu, H T; Ge, X P; Qiao, H; Zhang, W Y; Xiong, Y W; Jiang, S F; Gong, Y S; Jin, S B

    2015-01-01

    In this study, male-specific lethal 3 homolog (Mnmsl3) was cloned and characterized from the freshwater prawn Macrobrachium nipponense (Crustacea: Decapoda: Palaemonidae) by rapid amplification of cDNA ends. The deduced amino acid sequences of Mnmsl3 showed high-sequence homology to the insect Msl3 and contained a conserved chromatin organization modifier domain and an MORF4-related gene domain. Real-time quantitative reverse transcription-polymerase chain reaction showed that the Mnmsl3 gene was expressed in all the investigated tissues, with the highest level of expression in the testis. The expression level of Mnmsl3 between males and females was different in the gonad (testis or ovary), abdominal ganglion, and heart. The results revealed that the Mnmsl3 gene might play roles in regulating chromatin and in dosage compensation of M. nipponense. Real-time quantitative reverse transcription-polymerase chain reaction also revealed that Mnmsl3 mRNA expression was significantly increased in both 5 and 20 days post-larvae after metamorphosis, suggesting that Mnmsl3 plays complex and important roles in the early embryonic development and sex differentiation of M. nipponense. PMID:25966075

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Riverborne iron is a notable source for this biogeochemically key element to the oceans. Recent investigations have shown that its isotopic composition may vary significantly in oceanic waters. Hence, a proper understanding of the Fe cycle at the surface of the Earth requires a good characterization of the isotopic composition of its various reservoirs. However, as the database growths, it appears that the isotope composition of the riverborne Fe delivered to the oceans may be more varied than initially thought, in agreement with inferences from soil studies from different climatic contexts. It is therefore important to compare major rivers from different latitudes. We focused our attention on the Amazon River and its tributaries that represent ca. 20% of the freshwater delivered to the oceans by world rivers. Preliminary experiments suggest that water filtration may induce biases in stable Fe isotope composition. Therefore, we worked first on bulk waters, sampled during multidisciplinary field campaigns on the Amazon River and its tributaries, including the Solimoes, Negro, Madeira and Tapajos Rivers. Besides a complete sample physical-chemical characterization, Fe isotope determinations were conduced after water sample mineralization, iron purification and MC-ICP-MS analysis. Our first results reveal that most bulk water samples cluster close to the continental crust value (0.1% δ57FeIRMM-14) with an overall range of 0.2%. This is consistent with the restricted range found in lateritic soils elsewhere that represent 80% of the Amazon basin surface. Only black water rivers flowing over the podzols of the northern portion of the Amazon basin tend to show lighter isotopic compositions, down to -0.18%. However, sediment analyses suggest that this light Fe isotopic is lost through sedimentation on the river bed, thereby leading the waters to have Fe isotope compositions remaining close to that of the continental crust. This constant isotopic signature holds whatever the relative proportion of dissolved Fe in the bulk waters budget, that ranges from 5 to 50% in these waters, whatever the sample depth and whenever the samples were taken in the river cycle. Hence, given that several studies have shown that Fe loss through flocculation in estuaries does not affect Fe isotope signatures, we conclude that the bulk waters from the Amazon River delivered to the ocean should have an isotopic composition close to that of the continental crust.

  9. 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 (...

  10. 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 (...

  11. Sediment supply as a driver of river evolution in the Amazon Basin

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The Amazon represents the only large river basin in the world where there is a sufficient range of sediment supplies and a lack of engineering controls to assess how sediment supply drives the evolution of meandering rivers. Despite recent analytical advances (Asahi et al., 2013; Pittaluga and Seminara, 2011), modern theory does not yet identify or explain the effects of externally imposed sediment supplies, a fundamental river characteristic, on meandering river evolution. These sediment supplies would be radically reduced by the construction of large dams proposed for the Amazon Basin (Finer and Jenkins, 2012). Here, we demonstrate that the sediment loads imposed by their respective drainage basins determine planform changes in lowland rivers across the Amazon. Our analysis, based on Landsat image sequences, indicates that rivers with high sediment loads draining the Andes and associated foreland basin experience annual migration rates that are on average four times faster than rivers with lower sediment loads draining the Central Amazon Trough and shields. Incidents of meander cutoff also occur more frequently along the rivers of the Andes and foreland basin, where the number of oxbows in the floodplains is more than twice that observed in the floodplains of the Central Amazon Trough and shields. Our results, which cannot be explained by differences in channel slope or hydrology, highlight the importance of sediment supply in modulating the ability of meandering alluvial rivers to reshape the floodplain environment through river migration. Asahi, K., Shimizu, Y., Nelson, J., Parker, G., 2013. Numerical simulation of river meandering with self-evolving banks. Journal of Geophysical Research: Earth Surface, 118(4), 2013JF002752. Finer, M., Jenkins, C.N., 2012. Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes-Amazon connectivity. PLOS One, 7(4), e35126. Pittaluga, M.B., Seminara, G., 2011. Nonlinearity and unsteadiness in river meandering: a review of progress in theory and modelling. Earth Surface Processes and Landforms, 36(1), 20-38.

  12. Constructing and random sequencing analysis of normalized cDNA library of testis tissue from oriental river prawn (Macrobrachium nipponense).

    PubMed

    Qiao, Hui; Fu, Hongtuo; Jin, Shubo; Wu, Yan; Jiang, Sufei; Gong, Yongsheng; Xiong, Yiwei

    2012-09-01

    The oriental river prawn, Macrobrachium nipponense, is an important aquaculture species in China. Sexual precocity is a serious problem because of genetic retrogression, which has negative effects on product quality and dramatically affects price. Culture of all-male populations of this species would be economically advantageous, as the males grow faster and reach a much larger size than females. Developing such a culture scheme will require discovery of sex- or reproduction-related genes that affect sexual maturity and sex determination. In this study, a high-quality normalized testis cDNA library was constructed to identify novel transcripts. Of the 5280 successful sequencing reaction yields, 5202 expressed tagged sequences (ESTs) with an average length of 954 bp. Ultimately, 3677 unique sequences, including 891 contigs and 2786 singletons, were identified based on cluster and assembly analyses. Sixteen hundred (43.5%) genes were novel based on the NCBI protein database, thus these unidentified genes may improve basic molecular knowledge about M. nipponense. Of the novel unigenes, 34.4% (715/2077) were homologous to insects, such as Tribolium castaneum, Drosophila spp. and Apis mellifera. Fifty-two genes were identified as sex- or reproduction-related based on Gene Ontology classification and sequence comparison with data from other publications. These genes can be classified into groups based on different functions, including 10 sex-determination related genes, 8 male-reproductive genes, 5 cathepsin-related genes, 20 ubiquitin-related genes, 5 ferritin-related genes, and 4 LRR genes. The results of this study provide new sequence information about M. nipponense, which will be the basis for further genetic studies of this species and other decapods crustaceans. PMID:22632994

  13. Molecular cloning, characterization, and expression analysis of two different types of lectins from the oriental river prawn, Macrobrachium nipponense.

    PubMed

    Xiu, Yunji; Wang, Yinghui; Jing, Yunting; Qi, Yakun; Ding, Zhengfeng; Meng, Qingguo; Wang, Wen

    2015-08-01

    Lectins, which are widely expressed in invertebrates, play important roles in many biological processes, including protein trafficking, cell signaling, pathogen recognition, as effector molecules, and so on (Wang and Wang, 2013). This study identified one novel M-type lectin and one L-Type lectin, designated as MnMTL1 and MnLTL1, from the oriental river prawn Macrobrachium nipponense. The full-length cDNA of MnMTL1 was 2064 bp with a 1761 bp ORF encoding a putative protein of 586 deduced amino acids. The full-length cDNA of MnLTL1 was 1744 bp with a 972 bp ORF encoding a 323-amino acid peptide. The deduced MnMTL1 protein contained a putative type II transmembrane region and a 440-aa Glycoside hydrolase family 47 (GH47) domain. One luminal carbohydrate recognition domain and a 23-aa type I transmembrane region were identified from the MnLTL1. MnMTL1 shared 78% identity with Marsupenaeus japonicus M-type lectin and MnLTL1 shared 83% similarity with M. japonicus L-type lectin. RT-PCR analysis showed that MnMTL1 and MnLTL1 were expressed in all tested tissues. Quantitative real-time PCR analysis revealed that MnMTL1 and MnLTL1 are substantially fluctuant during Aeromonas hydrophila and Aeromonas veronii infections. Based on immune responses and previous literature, we assumed that MnMTL1 and MnLTL1 might be functioned as pattern recognition receptors and play important roles in the immune response of M. nipponense. PMID:25929240

  14. Isolation and characterization of two novel C-type lectins from the oriental river prawn, Macrobrachium nipponense.

    PubMed

    Xiu, Yunji; Hou, Libo; Liu, Xiaoqian; Wang, Yinghui; Gu, Wei; Meng, Qingguo; Wang, Wen

    2015-10-01

    C-type lectins are a family of calcium-dependent carbohydrate-binding proteins which are believed to play important roles in the innate immunity of invertebrates. This study identified two novel C-type lectins, designated as MnCTLDcp2 and MnCTLDcp3, from the oriental river prawn Macrobrachium nipponense. The full-length cDNA of MnCTLDcp2 was of 1582 bp with an open reading frame (ORF) of 972 bp encoding a polypeptide of 323 amino acids. The complete nucleotide sequence of MnCTLDcp3 cDNA was 583 bp, containing a 555 bp ORF encoding a putative protein of 184 deduced amino acids. The deduced MnCTLDcp2 and MnCTLDcp3 proteins both contained a single C-type lectin-like domain (CTLD). Besides, MnCTLDcp2 contains a signal peptide and an low-density lipoprotein receptor class A (LDLa) domain. Reverse transcription PCR showed that MnCTLDcp2 was expressed in the heart, gill, nerve hepatopancreas and intestine; MnCTLDcp3 was expressed in the hepatopancreas, heart, nerve, gill and muscle. Their expression in the heart tissue was regulated following challenge with bacteria. The microbial agglutination assay showed that both MnCTLDcp2 and MnCTLDcp3 could agglutinated bacteria in the presence of calcium. All these results suggested that MnCTLDcp2 and MnCTLDcp3 functioned as pattern recognition receptors in the immune system of M. nipponense. PMID:26208755

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

    NASA Astrophysics Data System (ADS)

    Smith, Walker O.; Demaster, David J.

    1996-03-01

    Phytoplankton biomass and primary productivity were assessed on the continental shelf in the plume of the Amazon River during a series of cruises conducted within periods of minimum, maximum, rising and falling river discharge. Chlorophyll concentrations were greatest (up to 25.5 μg l -1) in a zone located outside the turbid, high nutrient, low salinity riverine waters but shoreward of the clear, high salinity, low nutrient waters. Vertical distributions of chlorophyll further delineated the influences of these environmental regimes, with maximum chlorophyll concentrations occurring in the upper 5 m of water columns characterized by reduced salinities and elevated nutrients at the surface and low nutrient, high salinity water below. Fluorescence was elevated in the transition zone as a result of the phytoplankton standing stocks, and was also elevated in low-salinity waters influenced by the Amazon outflow. The residual fluorescence was coupled to salinity but not to chlorophyll, which suggested that it was related to dissolved organic matter which originated in the Amazon. Primary productivity on the continental shelf was greatest in the transition zone and occasionally exceeded 8 g C m -2 d -1. Productivity in the turbid, nutrient-rich waters and the clear, offshore regions averaged 2.18 and 0.81 g C m -1 d -1, respectively. Phytoplankton photosynthesis in waters influenced by the Amazon River appeared to be limited by low levels of available irradiance inshore, whereas offshore it was nutrient-limited. The narrow zone of high production was supported by the riverine input of nutrients and the dynamics of sediment flocculation. Removal of the inorganic sediment load was necessary to allow for adequate irradiance penetration to support photosynthesis.

  16. Sediment dynamics within the intertidal floodplain of the lower Amazon River

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Tidal influence extends ~800 kilometers upstream of the Amazon River mouth, producing semidiurnal oscillations in water elevation and slowing or reversing the flow of the world's largest river. This tidally influenced reach, known as the tidal river, is flanked by an expansive intertidal floodplain, and includes confluences with two large tributaries, the Xingu and Tapajós. The relative magnitude of the seasonal and tidal signals changes along the length of the tidal river, yielding diverse floodplain environments that span a range of seasonal and tidal influence. Near the upstream limit of tides, natural levees isolate the river from the floodplain during low to moderate flows, while in the lower tidal river, natural levees are absent and river-floodplain exchange is dominated by the tides rather than seasonal variation in river stage. This difference between fluvial and tidal systems strongly affects the nature of sediment exchange between the channel and floodplain, including frequency, duration, and depth of inundation. Here we present data on the impact of this fluvial-tidal continuum on sedimentary processes in the floodplain and resultant depositional signatures. Changes in levee prominence, grain size, and sediment accumulation combine to produce the distinct morphologies of floodplain lakes, intertidal backswamps, and intertidal flats. In addition to sediment accumulation on the periodically exposed floodplain, Amazon River sediment accumulates within the drowned tributary confluences of the Xingu and Tapajós Rivers. Here seasonal and tidal changes in water temperature, discharge, and suspended-sediment concentration drive barotropic and baroclinic flows that transport Amazon River sediment into tributary basins. These findings help to constrain the fate of sediment within the ungauged Amazon tidal river, and will help in understanding the response of the lower Amazon River to changes in accommodation space associated with rising sea level, and changes in sediment load due to deforestation and damming.

  17. Identification and comparative analysis of the oriental river prawn (Macrobrachium nipponense) microRNA expression profile during hypoxia using a deep sequencing approach.

    PubMed

    Sun, Shengming; Fu, Hongtuo; Ge, Xianping; Zhu, Jian; Gu, Zhimin; Xuan, Fujun

    2016-03-01

    Hypoxia refers to a state of oxygen deficiency, which is observed frequently in aquaculture ponds. MicroRNAs (miRNAs) are small non-coding RNAs that are important effectors in regulating gene expression through posttranscriptional mechanisms. They are key elements in the response to hypoxia. The oriental river prawn (Macrobrachium nipponense) is an important commercial aquaculture species, and is sensitive to hypoxia. To date, there are no reports describing M. nipponense miRNAs. In this study, Solexa deep sequencing technology was used for high-throughput analysis of miRNAs in a small RNA library isolated from four M. nipponense tissues (gill, hepatopancreas, muscle and hemocytes). In total, 9,227,356 reads were obtained, 4,293,155 of which were related to 267 unique miRNAs, including 203 conserved and 64 prawn-specific miRNAs. Furthermore, miRNA features including length distribution and end variations were characterized. Annotation of targets revealed a broad range of biological processes and signal transduction pathways regulated by M. nipponense miRNAs. In addition, 880 co-expressed and 39 specific (25 normoxia-specific and 14 hypoxia-specific) miRNAs that may be involved in the response to hypoxia were confirmed using miRNA microarray analysis from the four prawn tissues combined. Real-time quantitative PCR (qPCR) analysis of eight miRNAs in the normoxia and hypoxia groups showed good concordance between the sequencing and qPCR data. This study provides the first large-scale identification and characterization of M. nipponense miRNAs and their potential targets, and represents a foundation for further characterization of their roles in the regulation of the diversity of hypoxia processes. PMID:26829004

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

    NASA Astrophysics Data System (ADS)

    Roche, Michel-Alain; Jauregui, Carlos Fernandez

    1988-06-01

    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.

  19. Macrobrachium indianum (Decapoda: Palaemonidae), a new species of hill stream prawn from Pambar River, Kerala, India.

    PubMed

    Pillai, P M; Unnikrishnan, V; Prasannan, K

    2015-01-01

    Macrobrachium indianum new species is described from the Pambar River, Kerala, S. India. The species shares certain characters with M. gurudeve Jayachandran & Raji, 2004, M. bombayense Almelker & Sankolli, 2006 and M. kulkarnii Almelker & Sankolli, 2006, while it differs remarkably from these three species in distinctive diagnostic characters: rostral formula 7-8/3-4 with 1 postorbital teeth, one tooth above orbit; carapace smooth with distal end of rostrum directed downwards; cephalothorax longer than rostrum; in second chelate leg, proximal cutting edge of movable finger with two weak denticles, one weak denticle in immovable finger, carpus longer than merus, merus shorter than propodus and longer than ischium; dactylus the shortest podomere. Five thick and a few thin reddish brown bands of chromatophores are seen on carapace. Pigmentation is found mid and ventro-laterally on abdominal segments, pereiopods have chromatophores at the distal part of podomeres. PMID:25947453

  20. The Birthplace of the Amazon River, the Confluence of the Maranon and Ucayali Rivers

    NASA Astrophysics Data System (ADS)

    Abad, J. D.; Ortals, C.; Paredes, J.; Vizcarra, J.

    2014-12-01

    The Amazon River starts at the confluence between the Maranon and Ucayali Rivers near Nauta City. The Maranon River is an anabranching channel while the Ucayali River near the confluence is transitioning from purely meandering to anabranching channel. The interaction of water and sediment between these two large rivers is important for the Pacaya-Samiria Peruvian Reserve, a region with one of highest biodiversity in the planet. Past studies related to flow, sediment and morphology at confluences have been performed for single threat channels. Herein a detailed mapping, sediment sampling and hydrodynamics are carried for a confluence between anabranching and meandering channels. Furthermore, remote sensing analysis have been performed to understand that the confluence point has been changing at the geologcal time scale increasing the morphological structures around the Ucamara depression, where the Pacaya-Samiria reserve is located. Results of the field studies indicate complex mixing processes downstream of the confluence, where secondary flows are observed driven the sediment mixing. The dynamic of the confluence point is governed by the evolution of the Ucayali River and the local geology. These findings will help us to relate mixing processes in one of the largest wetlands in the world.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  3. River discharge and flood inundation over the Amazon based on IPCC AR5 scenarios

    NASA Astrophysics Data System (ADS)

    Paiva, Rodrigo; Sorribas, Mino; Jones, Charles; Carvalho, Leila; Melack, John; Bravo, Juan Martin; Beighley, Edward

    2015-04-01

    Climate change and related effects over the hydrologic regime of the Amazon River basin could have major impacts over human and ecological communities, including issues with transportation, flood vulnerability, fisheries and hydropower generation. We examined future changes in discharge and floodplain inundation within the Amazon River basin. We used the hydrological model MGB-IPH (Modelo de Grandes Bacias - Instituto de Pesquisas Hidráulicas) coupled with a 1D river hydrodynamic model simulating water storage over the floodplains. The model was forced using satellite based precipitation from the TRMM 3B42 dataset, and it had a good performance when validated against discharge and stage measurements as well as remotely sensed data, including radar altimetry-based water levels, gravity anomaly-based terrestrial water storage and flood inundation extent. Future scenarios of precipitation and other relevant climatic variables for the 2070 to 2100 time period were taken from five coupled atmosphere-ocean general circulation models (AOGCMs) from IPCC's Fifth Assessment Report (AR5) Coupled Model Intercomparison Project Phase 5 (CMIP5). The climate models were chosen based on their ability to represent the main aspects of recent (1970 to 2000) Amazon climate. A quantile-quantile bias removal procedure was applied to climate model precipitation to mitigate unreliable predictions. The hydrologic model was then forced using past observed climate data altered by delta change factors based on the past and future climate models aiming to estimate projected discharge and floodplain inundation in climate change scenario at several control points in the basin. The climate projections present large uncertainty, especially the precipitation rate, and predictions using different climate models do not agree on the sign of changes on total Amazon flood extent or discharge along the main stem of the Amazon River. However, analyses of results at different regions indicate an increase on flood inundation and discharge over the upper Amazon basin (west Amazon) and decreased discharges over the southeastern tributaries.

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    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.

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

    USGS Publications Warehouse

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

    1985-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  7. Insight on the Peruvian Amazon River: A Planform Metric Characterization of its Morphodynamics

    NASA Astrophysics Data System (ADS)

    Garcia, A. M. P.; Ortals, C.; Frias, C. E.; Abad, J. D.; Vizcarra, J.

    2014-12-01

    Starting in Peru, the Amazon River flows through Colombia and Brazil; additionally, tributaries from Bolivia, Venezuela, and Ecuador contribute to the massive river and its unique geomorphic features. Accordingly, the Amazon Basin has become an important aspect of South America; it is an area of extraordinary biodiversity, rich resources, and unique cultures. However, due to the sheer magnitude and exceptionality of the Amazon River, research regarding the morphodynamic processes that shape and define the river has been difficult. Consequently, current research has not completely understood the planform dynamics of some portions of this river that present a main channel and secondary channels known as "anabranching structures". The purpose of this research was to gain an understanding of the geomorphology of the upper Amazon, the Peruvian section, by obtaining migration rates and planform metrics, including channel count, length, width, and sinuosity, as well as island count, area, and shape. With this data, the morphodynamics of the Peruvian Amazon, especially the relationship between the main channel and its secondary channels in each "anabranching structure" along the river, could be analyzed according to correlations found between various metrics. This analysis was carried out for 5-year time spans over a period of 25 years. Preliminary results showed that the average migration rate versus channel bend radius envelope peak is lower for the secondary channels than for the main channel. However, the maximum migration rate was not always found in the main channel; for several structures, the most dynamic channels were the secondary ones. This implies a certain periodicity to the river's migratory patterns that could be related to the valley boundaries, the local channel sinuosity or geological formations in the study area.

  8. Organic matter transport from the Peruvian Andes to the Amazon River

    NASA Astrophysics Data System (ADS)

    Townsend-Small, A.; Noguera, J. L.; McClain, M. E.; Brandes, J. A.

    2005-12-01

    The Andes are a major source of sediments, dissolved minerals, and water to the Amazon River. The current study seeks to determine the extent to which the Andes are a source for organic carbon and nitrogen to the Amazon River proper. We have employed a variety of isotopic (stable and radiocarbon) and elemental tracers of carbon and nitrogen cycling. Our results suggest that the organic carbon content of Andean rivers is highly variable with altitude and hence terrestrial ecosystem type and geomorphology. The data indicate that suspended and dissolved organic matter is derived from altered soil pools, with evidence of sorption of N-rich fractions onto fine sediment fractions. Erosion, and therefore age and degree of alteration from plant sources, of terrestrial soils into Andean rivers is tightly coupled to rainfall events ("hot moments"). As noted elsewhere and supported by our data, Andean riverine carbon is quite young and suggests that such exports are unusually susceptible to changes in climate.

  9. Fate of the Amazon River dissolved organic matter in the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Medeiros, Patricia M.; Seidel, Michael; Ward, Nicholas D.; Carpenter, Edward J.; Gomes, Helga R.; Niggemann, Jutta; Krusche, Alex V.; Richey, Jeffrey E.; Yager, Patricia L.; Dittmar, Thorsten

    2015-05-01

    Constraining the fate of dissolved organic matter (DOM) delivered by rivers is a key to understand the global carbon cycle, since DOM mineralization directly influences air-sea CO2 exchange and multiple biogeochemical processes. The Amazon River exports large amounts of DOM, and yet the fate of this material in the ocean remains unclear. Here we investigate the molecular composition and transformations of DOM in the Amazon River-ocean continuum using ultrahigh resolution mass spectrometry and geochemical and biological tracers. We show that there is a strong gradient in source and composition of DOM along the continuum, and that dilution of riverine DOM in the ocean is the dominant pattern of variability in the system. Alterations in DOM composition are observed in the plume associated with the addition of new organic compounds by phytoplankton and with bacterial and photochemical transformations. The relative importance of each of these drivers varies spatially and is modulated by seasonal variations in river discharge and ocean circulation. We further show that a large fraction (50-76%) of the Amazon River DOM is surprisingly stable in the coastal ocean. This results in a globally significant river plume with a strong terrigenous signature and in substantial export of terrestrially derived organic carbon from the continental margin, where it can be entrained in the large-scale circulation and potentially contribute to the long-term storage of terrigenous production and to the recalcitrant carbon pool found in the deep ocean.

  10. The geochemistry of rare earth elements in the Amazon River estuary

    SciTech Connect

    Shokovitz, E.R. )

    1993-05-01

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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  12. Vocalizations of Amazon river dolphins (Inia geoffrensis): Characterization, effect of physical environment and differences between populations.

    PubMed

    Amorim, Thiago Orion Simões; Andriolo, Artur; Reis, Sarah S; Dos Santos, Manuel E

    2016-03-01

    The vocal repertoire of the Amazon river dolphin and its geographic variations are still poorly known, especially in relation to ecological variables. Here the acoustic characteristics of low frequency pulsed vocalizations, with single or multiple pulses, recorded in two protected areas of the Amazon were described and differences in acoustic emissions related to water properties were analyzed. Both frequency and time parameters differ relative to abiotic condition of water turbidity. Changes in the animals' acoustic behavior might be due to differences in sound propagation between rich-sediment water and clear water. Geographic variation was found in frequency and time parameters, requiring further investigation. PMID:27036265

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    Results are presented of measurements of the CO2 concentrations and C-13/C-12 ratios in CO2 in air samples collected from within the Amazonian rain forest and over the Amazon river between 1982 and 1987. Results indicate the presence of a diurnal cycle in the CO2 concentration and the C-13/C-12 ratio. It was found that the CO2 input to air in the forest was derived from the soil respiration, and the CO2 input to air over the Amazon river was derived from the degassing of CO2 from the river. It was also found that plants growing at heights lower than 7 m assimilate soil-derived CO2 with a low C-13/C-12 ratio.

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

    SciTech Connect

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

    1985-07-20

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

  16. Barbados Corals as Recorders of Amazon River Salinity Anomalies

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Sacek, Victor

    2014-09-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    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.

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

    SciTech Connect

    Devol, A.H.; Richey, J.E. ); Forsberg, B.R. ); Martinelli, L.A. )

    1990-09-20

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

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

    NASA Astrophysics Data System (ADS)

    Sacek, Victor

    2014-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  3. Identification of androgenic gland microRNA and their target genes to discover sex-related microRNA in the oriental river prawn, Macrobrachium nipponense.

    PubMed

    Jin, S B; Fu, H T; Jiang, S F; Xiong, Y W; Qiao, H; Zhang, W Y; Gong, Y S; Wu, Y

    2015-01-01

    The oriental river prawn, Macrobrachium nipponense, is an important aquaculture species in China. The androgenic gland produces hormones that play crucial roles in the differentiation of crustaceans to the male sex. MicroRNA (miRNA) post-transcriptionally regulates many protein-coding genes, influencing important biological and metabolic processes. However, currently, there is no published data identifying miRNA in M. nipponense. In this study, we identified novel miRNA in the androgenic gland of M. nipponense. Using the high-throughput Illumina Solexa system, 1077 miRNA were identified from small RNA libraries by aligning with the de novo androgenic gland transcriptome of M. nipponense (obtained from RNA-Seq) and the sequences in the miRBase21 database. A total of 8,248, 76,011, and 78,307 target genes were predicted in the EST and SRA sequences provided in the NCBI database, and the androgenic gland transcriptome of M. nipponense, respectively. Some potential sex-related miRNA were identified based on the function of the predicted target genes. The results of our study provide new information regarding the miRNA expression in M. nipponense, which could be the basis for further genetic studies on decapod crustaceans. PMID:26782487

  4. Molecular cloning, characterization, and expression analysis of a Broad-Complex homolog during development in the oriental river prawn Macrobrachium nipponense.

    PubMed

    Jiang, S F; Zhang, Y P; Sun, S M; Gong, Y S; Xiong, Y W; Qiao, H; Zhang, W Y; Jin, S B; Fu, H T

    2015-01-01

    Broad-Complex (BR-C) is an early ecdysone-responsive gene encoding a family of zinc-finger transcription factors. In this study, we isolated the full-length cDNA of a BR-C homolog from the testes of the oriental river prawn (Macrobrachium nipponense), according to established expressed sequence tag information, using the rapid amplification of cDNA ends technique. The homolog was designated as MnBR-C. The full-length cDNA of MnBR-C contained a 1095-bp open reading frame encoding a precursor protein of 365 amino acid residues. Comparative and bioinformatic analyses revealed that MnBR-C exhibited a high degree of homology with BR-C proteins, and contained the BTB and Zf-H2C2-2 domains. Real-time quantitative polymerase chain reaction (qPCR) analysis revealed that the MnBR-C expression level varied significantly in the developing embryo, postembryonic larva, and adult tissue. Real-time qPCR showed that the MnBR-C gene was expressed in all of the tissues investigated, with the highest level of expression in the brain. In addition, MnBR-C was more abundantly expressed in the testes than in the ovaries. PMID:26125707

  5. Simulating hydrologic and hydraulic processes throughout the Amazon River Basin

    USGS Publications Warehouse

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed

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

    2012-01-01

    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 (18:2ω6 and 18:3ω3) and cyanobacteria (16:1ω7), 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

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

    PubMed Central

    Mortillaro, Jean-Michel; Rigal, Franois; Rybarczyk, Herv; Bernardes, Marcelo; Abril, Gwenal; Meziane, Tarik

    2012-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

    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.

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

    SciTech Connect

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

    1993-03-01

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

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

    PubMed

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

    2012-03-01

    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

  12. Evidence of a decadal solar signal in the Amazon River: 1903 to 2013

    NASA Astrophysics Data System (ADS)

    Antico, Andrés.; Torres, María. E.

    2015-12-01

    It has been shown that tropical climates can be notably influenced by the decadal solar cycle; however, the relationship between this solar forcing and the tropical Amazon River has been overlooked in previous research. In this study, we reveal evidence of such a link by analyzing a 1903-2013 record of Amazon discharge. We identify a decadal flow cycle that is anticorrelated with the solar activity measured by the decadal sunspot cycle. This relationship persists through time and appears to result from a solar influence on the tropical Atlantic Ocean. The amplitude of the decadal solar signal in flow is apparently modulated by the interdecadal North Atlantic variability. Because Amazonia is an important element of the planetary water cycle, our findings have implications for studies on global change.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  14. Potential negative effects of groundwater dynamics on dry season convection in the Amazon River basin

    NASA Astrophysics Data System (ADS)

    Lin, Yen-Heng; Lo, Min-Hui; Chou, Chia

    2016-02-01

    Adding a groundwater component to land surface models affects modeled precipitation. The additional water supply from the subsurface contributes to increased water vapor in the atmosphere, resulting in modifications of atmospheric convection. This study focuses on how groundwater dynamics affect atmospheric convection in the Amazon River basin (ARB) during July, typically the driest month. Coupled groundwater-land-atmosphere model simulations show that groundwater storage increases evapotranspiration rates (latent heat fluxes) and lowers surface temperatures, which increases the surface pressure gradient and thus, anomalous surface divergence. Therefore, the convection over the Southern Hemispheric ARB during the dry season becomes weaker when groundwater dynamics are included in the model. Additionally, the changes in atmospheric vertical water vapor advection are associated with decreases in precipitation that results from downwelling transport anomalies. The results of this study highlight the importance of subsurface hydrological processes in the Amazon climate system, with implications for precipitation changes during the dry season, observed in most current climate models.

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

    NASA Astrophysics Data System (ADS)

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

    1990-09-01

    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.

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

    USGS Publications Warehouse

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

    1998-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  19. 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

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

    2015-05-10

    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 286.810 kDa. 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

  20. Characterization, expression, and function analysis of gonad-inhibiting hormone in Oriental River prawn, Macrobrachium nipponense and its induced expression by temperature.

    PubMed

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

    2015-07-01

    Gonad-inhibiting hormone (GIH) is a member of crustacean hyperglycemic hormone family and plays a major role in regulating reproduction in crustaceans. In this study, a full-length cDNA of GIH of Oriental River prawn, Macrobrachium nipponense (Mn-GIH) was cloned from the eyestalk. A 1350 bp full-length Mn-GIH cDNA harbored 336 bp of an open reading frame encoding signal peptide of 112 amino acid residues. Sequence analysis revealed that the overall cDNA sequence and specific functional sites of Mn-GIH were highly conserved with those in other crustacean species. Expression analysis by quantitative real-time PCR demonstrated its tissue-specific, larval developmental stage-specific, and ovary developmental stage-specific expression pattern, respectively. The RNAi by GIH-ds-RNA in vivo injection was effective in this study and resulted a 50% (day 1), 83% (day 5) and 63% (day 9) down-regulation compared to control. The obvious changes of gonad somatic index (GSI) rate also provided strong evidence to the inhibition effects of GIH on ovary maturation and spawning. Four temperature gradients (12 °C ± 1 °C, 17 °C ± 1 °C, 22 °C ± 1 °C, 27 °C ± 1 °C) were set to imitate the temperature in breeding and non-breeding seasons. The observed expression profiles suggest that Mn-GIH did not display a high level expression as supposed to maintain an immature ovary state under low temperature (12 °C). The results indicated that GIH was probably activated to concentrating and working by a proper temperature before reaching to breeding season. PMID:25770669

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

    SciTech Connect

    Rao, Ji Long; Berner, R.A. . Dept. of Geology and Geophysics)

    1992-01-01

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

  2. Modern Environmental Changes on Amapa Coastal Plain under Amazon River Influence

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    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.

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

    PubMed

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

    2013-05-01

    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

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

    PubMed Central

    Lafferty, Kevin D.; Kuris, Armand M.

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    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

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  7. Insights into iron sources and pathways in the Amazon River provided by isotopic and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Mulholland, Daniel Santos; Poitrasson, Franck; Boaventura, Geraldo Resende; Allard, Thierry; Vieira, Lucieth Cruz; Santos, Roberto Ventura; Mancini, Luiz; Seyler, Patrick

    2015-02-01

    The present study investigated the weathering and transport mechanisms of Fe in the Amazon River. A particular emphasis was placed on Fe partitioning, speciation, and isotopic fractionation in the contrasting waters of the Solimões and Negro rivers and their mixing zone at the beginning of the Amazon River. Samples collected in the end-member rivers and thirteen sites distributed throughout the mixing zone were processed through frontal vacuum filtration and tangential-flow ultrafiltration to separate the different suspended solid fractions, i.e., particulate (P > 0.45 μm and P > 0.22 μm), colloidal (0.22 μm > C > 5 kDa) and truly dissolved elements (TD < 5 kDa). The Fe isotopic composition and electron paramagnetic resonance (EPR) species were measured on these different pore-sized fractions. The acidic and organo-Fe-rich waters of the Negro River displayed dissolved and colloidal fractions enriched in heavy isotopes (∼1.2‰, in δ57Fe values relative to IRMM-14), while the particulate fractions yielded light isotopic compositions of -0.344‰ for P > 0.22 μm and -0.104‰ for P > 0.45 μm fractions). The mineral particulate-rich waters of the Solimões River had dissolved and colloidal fractions with light isotopic composition (-0.532‰ and -0.176‰, respectively), whereas the particulate fractions yielded δ57Fe values close to those of the continental crust (i.e., -0.029‰ for P > 0.22 μm and 0.028‰ for P > 0.45 μm). Ten kilometers downstream from the Negro and Solimões junction, the concentrations of colloidal and dissolved Fe species deviate markedly from conservative mixing. A maximum Fe loss of 43 μg/L (i.e., 50% of the dissolved and colloidal Fe) is observed 110 km downstream from the rivers junction. The contrasting Negro and Solimões Rivers isotopic compositions along the pore-sized water fractions is attributable to the biogeochemical processes involving different types of upland soils and parental materials. For instance, the isotopic composition of colloidal and dissolved Fe from the Negro River are consistent with Fe oxidation and complexation mechanisms at the interface between waterlogged podzols and river networks, as supported by strong organo-Fe complexes signals observed by EPR. Conversely, the particulate and colloidal fractions from the Solimões River have δ57Fe consistent with strong mechanical erosion in the Andean Cordillera and upland soils, as evidenced by high concentrations of Fe3+-oxides sensu lato measured by EPR. The massive dissolved and colloidal Fe removal is associated with the evolution of the physical and chemical composition of the waters (i.e., ionic strength) during mixing, which influences organo-Fe3+ and Fe3+-oxyhydroxides stability. Several models are discussed to explain Fe non-conservative behavior, including dissociation of organo-Fe complexes and the subsequent formation of solid Fe3+-oxyhydroxides and semiquinone free radicals, as evidenced by EPR spectra demonstrating that organo-Fe signals decrease as Fe3+-oxyhydroxides and free radicals signals increase. As in estuarine regions, the mechanisms involving Fe transfer and loss in the mixing zone has a negligible effect on the bulk water Fe isotopic composition. This result suggests that a tropical basin similar to the Amazon River Basin delivers to the ocean waters with an Fe isotopic composition similar to that of the Earth's continental crust.

  8. Swath-altimetry measurements of the main stem Amazon River: measurement errors and hydraulic implications

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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) characterise 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 ~260 km reach of the central Amazon (Solimões) 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-dimensional height error spectrum derived from the SWOT design requirements. We thereby obtained water-surface elevation measurements for the Amazon main stem 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 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-sectional 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. We extend the results to other rivers worldwide and infer that SWOT-derived discharge estimates may be more accurate for rivers with larger channel widths (permitting a greater level of cross-sectional averaging and the use of shorter reach lengths) and higher water-surface slopes (reducing the proportional impact of slope errors on discharge calculation).

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

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

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

    PubMed Central

    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

    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

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

    PubMed Central

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

    2013-01-01

    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

  13. Flow Estimate of Carbon Dioxide in a Amazon River Hydrological Station

    NASA Astrophysics Data System (ADS)

    Moura, J. M. S.; Ferreira, R. B., Jr.; Tapajós, R. P.

    2014-12-01

    Recent measurements in the Amazon suggest that the flow of CO2 in surface waters may reach the order of 1GT per year and isotopic analyzes suggest that this carbon is a direct result of organic matter degradation (OMD) in rivers and the measured concentration exceeds the value expected for there to be equilibrium with the atmosphere (Richey et al, 2002). This study aimed to measure and check the seasonal variability of CO2 fluxes in a range of six months (September 2013-February 2014) in the Strait Óbidos hydrological station located geographically in the coordinates 55 ° 1 '4 "S and 55 ° 31' 4" W. In addiction, it is intended to correlate the data with physical-chemical water parameters pH, dissolved oxygen (DO), and temperature and humidity. The method used for the measurement of CO2 concentration in the atmosphere-water interface is the floating chamber liked with an infrared gas analyzer (IRGA- Infrared Gas Analyzer). The physical-chemical parameters of water were measured using a multiparameter probe YSI Professional Plus model. The preliminary results shows values average CO2 flux was approximately 15.65 1,01ppm / m2s-1 for the months of September and October and between the months of November, 2013 and February 2014 the CO2 flux average was 4.40 + 1.94 ppm / m2s-1. In addiction to the high temperature in dry season, in the water column there is sufficient convection for the existence of gases transport from water to atmosphere, resulting in increase of exchange. Thus, the decreased amount of radiation and consequently the low temperatures in the humid period (on average 27.2 ° C) should affect the OMD in the river, responsible for the production of dissolved CO2. Keywords: CO2 flux, seasonal variability, amazon river

  14. Molecular characterization of insulin-like androgenic gland hormone-binding protein gene from the oriental river prawn Macrobrachium nipponense and investigation of its transcriptional relationship with the insulin-like androgenic gland hormone gene.

    PubMed

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

    2015-05-15

    Insulin-like androgenic gland hormone-binding protein (IAGBP) has been investigated in crustaceans in vitro. However, the relationship between IAGBP and its putative binding protein partner insulin-like androgenic gland hormone (IAG) has not been studied at the transcriptional level in vivo. In the current study, we cloned the full-length cDNA of IAGBP from the oriental river prawn Macrobrachium nipponense (Mn-IAGBP) and investigated the transcriptional patterns of Mn-IAGBP and the M. nipponense IAG gene (Mn-IAG) at different developmental stages and in different tissues. Mn-IAGBP mRNA was detected in all examined tissues from adult male prawns, with the highest transcriptional levels in the testis. Mn-IAG mRNA was detected in the androgenic gland and hepatopancreas. The genomic sequences of Mn-IAGBP and Mn-IAG were isolated by genome walking and two gene copies were found in both Mn-IAGBP and Mn-IAG. The relationship between Mn-IAGBP and Mn-IAG at the transcriptional level was studied by RNA interference. Injection of Mn-IAGBP double-stranded RNA (dsRNA) significantly reduced the transcription of Mn-IAG, while injection of Mn-IAG dsRNA significantly reduced the transcription of Mn-IAGBP in testis, muscle, androgenic gland, and hepatopancreas. These results demonstrate the involvement of the IAGBP gene in IAG signaling in M. nipponense. PMID:25558010

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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 μatm. 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 μatm; DDAs seemed to dominate waters within the narrow range of 350-400 μatm CO2; and the diazotroph Trichodesmium spp. grew in a wide range of pCO2 conditions, but with higher cell counts at upwards of 500 μatm. 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

  16. DDT concentration in fish from the Tapajós River in the Amazon region, Brazil.

    PubMed

    Mendes, Rosivaldo de Alcântara; da Costa Lopes, Anna Sylmara; de Souza, Larissa Costa; de Oliveira Lima, Marcelo; Santos, Lourivaldo da Silva

    2016-06-01

    DDT and metabolites were measured in six species of fish collected from the Tapajós River in the village of Barreiras, near the town of Itaituba in the Brazilian Amazon region. The selected fish were the most consumed and economically important to the local people. DDT was used frequently in this region for malaria control. Fish samples were analyzed after extraction by microwave-assisted extraction in hexane/acetone (8:2, v/v) by gas chromatography with electron capture detector. Residues of op'-DDT and pp'-DDT and metabolites were detected, including pp'-DDE, pp'-DDD, op'-DDT, and op'-DDE, in 98% of the samples, with a greater abundance of pp'-DDT. Total DDT levels were 7.1-249.5 ng g(-1) wet weight (w.w). The DDE/DDT ratio was low, indicating recent exposure to DDT. The study area that may be related to generated waste used in public health campaigns to combat mosquitos (Anopheles spp.), still present in the Amazon environment, that transmit malaria. DDT levels and metabolites found in fish species do not present risks to human health because they are below acceptable limits for consumption. PMID:27027561

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  18. Spectroscopic and Structural Study of the Protonation of Aquatic Natural Organic Matter from the Amazon river tributaries

    NASA Astrophysics Data System (ADS)

    Benedetti, M. F.; Korshin, G. V.; Claret, F.; Gallard, H.; Croue, J.; Fabbricino, M.; Schafer, T.

    2008-12-01

    The Amazon River basin contributes up to 20 percent of the total global flux of terrestrial dissolved organic carbon to the oceans. Because of this, elucidation of the properties on NOM generated in it is essential for understanding global and local cycles of organic carbon. Previous studies have examined the role Amazonian NOM in the speciation and transport of major cationic constituents and trace metals and other issues but, given the global role of the Amazon basin, more information is needed to further ascertain the chemistry and variability of Amazonian NOM. This study demonstrates that the deprotonation of NOM originating from small creeks feeding the Jau River a tributary the Rio Negro in the Amazon basin can be quantified based on measurements of pH effects on its absorbance and fluorescence spectra. NEXAFS, SEC and pyrolysis GC/MS. Differential absorbance (DA) spectra of these fractions contain bands with maxima located at ca. 240, 280, 315 and below 350 nm. The emergence of these features is associated with the engagement of phenolic, carboxylic and other functionalities. The results indicate the existence of structural and compositional differences between the colloidal and hydrophobic fractions that constitute an overwhelmingly important part of the NOM of the small and large black rivers of the Amazon basin. These differences will affect the fate of the mineral colloids and trace elements traveling in the basin together with the organic matter.

  19. Amazon River

    Atmospheric Science Data Center

    2013-04-17

    article title:  A Merging of Pale and Dark     View Larger Image ... results from its origin in the Peruvian Andes mountains. The dark color of the Rio Negro is characteristic of clear waters that originate in ...

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

    PubMed

    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

    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

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

    USGS Publications Warehouse

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

    1998-01-01

    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.

  2. Riverine Li isotope fractionation in the Amazon River basin controlled by the weathering regimes

    NASA Astrophysics Data System (ADS)

    Dellinger, Mathieu; Gaillardet, Jerome; Bouchez, Julien; Calmels, Damien; Louvat, Pascale; Dosseto, Anthony; Gorge, Caroline; Alanoca, Lucia; Maurice, Laurence

    2015-09-01

    We report Li isotope composition (δ7Li) of river-borne dissolved and solid material in the largest River system on Earth, the Amazon River basin, to characterize Li isotope fractionation at a continental scale. The δ7Li in the dissolved load (+1.2‰ to +32‰) is fractionated toward heavy values compared to the inferred bedrock (-1‰ to 5‰) and the suspended sediments (-6.8‰ to -0.5‰) as a result of the preferential incorporation of 6Li into secondary minerals during weathering. Despite having very contrasted weathering and erosion regimes, both Andean headwaters and lowland rivers share similar ranges of dissolved δ7Li (+1.2‰ to +18‰). Correlations between dissolved δ7Li and Li/Na and Li/Mg ratios suggest that the proportion of Li incorporated in secondary minerals during weathering act as the main control on the δ7Lidiss across the entire Amazon basin. A "batch" steady-state fractionation model for Andean and lowland rivers satisfactorily reproduces these variations, with a fractionation factor between weathering products and dissolved load (αsec-dis) of 0.983 ± 0.002. Two types of supply-limited weathering regimes can be identified for the lowlands: "clearwaters" with dominant incorporation of Li in secondary minerals, and "black waters" (e.g., Rio Negro) where dissolution of secondary minerals enhanced by organic matter produces low δ7Li. Apart from the black waters, the δ7Li of Andean and lowland rivers is negatively correlated to the denudation rates with the lowest δ7Li corresponding to the rivers having the highest denudation rates. In contrast, the main tributaries draining both the Andes and the lowlands have higher δ7Li compared to other rivers. We propose that part of the dissolved Li derived from weathering in the Andes is re-incorporated in sediments during transfer of water and sediments in floodplains and that this results in an increase of the dissolved δ7Li along the course of these rivers. Unlike other rivers, the dissolved δ7Li in the main tributaries is best described by a Rayleigh fractionation model with a fractionation factor αsec-dis of 0.991. Altogether, the control imposed by residence time in the weathering zone and floodplain processes results in (i) a non-linear correlation between dissolved δ7Li and the weathering intensity (defined as W/D) and (ii) a positive relationship between the dissolved Li flux and the denudation rate. These results have important implications for the understanding of past ocean δ7Li and its use as a paleo weathering proxy.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.)

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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 δ57Fe 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 (δ57FeIRMM-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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    USGS Publications Warehouse

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

    1977-01-01

    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.

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

    USGS Publications Warehouse

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

    1979-01-01

    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)

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    PubMed

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

    2015-01-01

    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

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

    PubMed Central

    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

    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

  12. Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar.

    PubMed

    Ladegaard, Michael; Jensen, Frants Havmand; de Freitas, Mafalda; Ferreira da Silva, Vera Maria; Madsen, Peter Teglberg

    2015-10-01

    Toothed whales produce echolocation clicks with source parameters related to body size; however, it may be equally important to consider the influence of habitat, as suggested by studies on echolocating bats. A few toothed whale species have fully adapted to river systems, where sonar operation is likely to result in higher clutter and reverberation levels than those experienced by most toothed whales at sea because of the shallow water and dense vegetation. To test the hypothesis that habitat shapes the evolution of toothed whale biosonar parameters by promoting simpler auditory scenes to interpret in acoustically complex habitats, echolocation clicks of wild Amazon river dolphins were recorded using a vertical seven-hydrophone array. We identified 404 on-axis biosonar clicks having a mean SLpp of 190.3 ± 6.1 dB re. 1 µPa, mean SLEFD of 132.1 ± 6.0 dB re. 1 µPa(2)s, mean Fc of 101.2 ± 10.5 kHz, mean BWRMS of 29.3 ± 4.3 kHz and mean ICI of 35.1 ± 17.9 ms. Piston fit modelling resulted in an estimated half-power beamwidth of 10.2 deg (95% CI: 9.6-10.5 deg) and directivity index of 25.2 dB (95% CI: 24.9-25.7 dB). These results support the hypothesis that river-dwelling toothed whales operate their biosonars at lower amplitude and higher sampling rates than similar-sized marine species without sacrificing high directivity, in order to provide high update rates in acoustically complex habitats and simplify auditory scenes through reduced clutter and reverberation levels. We conclude that habitat, along with body size, is an important evolutionary driver of source parameters in toothed whale biosonars. PMID:26447198

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

    PubMed

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

    2009-11-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

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

    USGS Publications Warehouse

    Oltman, Roy Edwin

    1968-01-01

    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.

  16. Planform evolution of two anabranching structures in the Upper Peruvian Amazon River

    NASA Astrophysics Data System (ADS)

    Frias, C. E.; Abad, J. D.; Mendoza, A.; Paredes, J.; Ortals, C.; Montoro, H.

    2015-04-01

    We present a study to relate the sinuosity of the main channel and its effect on the dynamics of the secondary channels of anabranching structures. For this purpose, two locations of the Peruvian Amazon River were selected: (1) a site with a medium to high-sinuosity main channel (MS site: Muyuy, Peru) and (2) a site with a low-sinuosity main channel (LS site: at the triple boundary between Brazil, Colombia, and Peru). The main channels for both the MS and LS anabranching structures have freedom to migrate in the lateral direction, while at least one of their secondary channels is adjacent to the geological valley. For MS and LS sites, temporal analysis of planform evolution was carried out using 30 years of satellite imagery from which metrics such as width, sinuosity, and annual maximum migration rates of main and secondary channels were calculated. Additionally, detailed hydrodynamic and bed morphology field measurements were carried out, and a two-dimensional shallow water numerical model was developed. For a medium to high-sinuosity main channel anabranching structure, the secondary channels present a dominant mechanism for reworking the floodplain, while for the low-sinuosity anabranching structure, the main channel planform dynamics is dominant. Flow velocities along the main and secondary channels for low, transition, and high-flow discharges describe that for MS (LS) site, the velocities are much higher along the secondary (main) channels.

  17. Structure of the parasites communities in two Erythrinidae fish from Amazon river system (Brazil).

    PubMed

    Alcântara, Natália Milhomem; Tavares-Dias, Marcos

    2015-01-01

    This study compared the parasite communities of Hoplias malabaricus and Hoplerythrinus unitaeniatus from Amazon river system. Hoplias malabaricus were infected by Ichthyophthirius multifiliis, Piscinoodinium pillulare, Tetrahymena sp., Urocleidoides eremitus, Braga patagonica, metacercariae of Clinostomum marginatum, Procamallanus (Spirocamallanus) inopinatus, larvae of Contracaecum sp. and larvae of Nomimoscolex matogrossensis. Hoplerythrinus unitaeniatus were also infected by these same species of protozoans, nematodes, digeneans and cestodes, except for Tetrahymena sp. and B. patagonica, which were replaced by Argulus pestifer, Urocleidoides sp., Whittingtonocotyle caetei, Whittingtonocotyle jeju and Gorytocephalus spectabilis. For both hosts, I. multifiliis and P. pillulare were the predominant parasites. Most of the parasites presented an overdispersion. Parasite species richness, Brillouin diversity, evenness and Berger-Parker dominance were similar for the two hosts. The length and weight of H. malabaricus showed a positive correlation with the abundance of U. eremitus and Contracaecum sp., while the weight of H. unitaeniatus showed a positive correlation with the abundance of I. multifiliis. The diversity of ectoparasites seemed to be influenced by the behavior of these two hosts. This was shown by the similar parasite communities and was characterized by low species diversity, low evenness and low richness, and by a high prevalence of ectoparasites. PMID:26083690

  18. Flow in prawn burrows

    NASA Astrophysics Data System (ADS)

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

    1992-09-01

    The hydrodynamic properties of U-tubes, simulating the burrows of thalassinid prawn, Upogebia africana Ortmann were examined. Flow was induced through the U-tube as a result of a reduced pressure gradient set up by the external stream as it passed over a cone-shaped elevation, the Bernoulli effect, and was proportional to tube Reynolds number and its aspect ratio. Animals within their artificial burrows showed a significant orientation ( P<0·05) towards an induced current, and a significant reduction ( P<0·05) in the time spent actively pumping water through their burrows. These results suggest that the currents induced through the natural burrows from the tidal flow overhead play an important role in the feeding and respiratory behaviour of these animals.

  19. Mercury in fish of the Madeira river (temporal and spatial assessment), Brazilian Amazon.

    PubMed

    Bastos, Wanderley R; Dórea, José G; Bernardi, José Vicente E; Lauthartte, Leidiane C; Mussy, Marilia H; Lacerda, Luiz D; Malm, Olaf

    2015-07-01

    The Madeira River is the largest tributary of the Amazon River Basin and one of the most impacted by artisanal gold-mining activities, deforestation for agricultural projects, and recent hydroelectric reservoirs. Total Hg (and methylmercury-MeHg) concentrations was determined in 3182 fish samples of 84 species from different trophic levels as a function of standard size. Species at the top of the trophic level (Piscivorous, Carnivorous) showed the highest mean total Hg concentrations (51-1242 µg/kg), Planctivorous and Omnivorous species showed intermediate total Hg concentrations (26-494 µg/kg), while Detritivorous and Herbivorous species showed the lowest range of mean total Hg concentrations (9-275 µg/kg). Significant correlations between fish size (standard length) and total Hg concentrations were seen for Planctivorous (r=0.474, p=0.0001), Piscivorous (r=0.459, p=0.0001), Detritivorous (r=0.227, p=0.0001), Carnivorous (r=0.212, p=0.0001), and Herbivorous (r=0.156, p=0.01), but not for the Omnivorous species (r=-0.064, p=0.0685). Moreover, fish trophic levels influenced the ratio of MeHg to total Hg (ranged from 70% to 92%). When adjusted for standard body length, significant increases in Hg concentrations in the last 10 years were species specific. Spatial differences, albeit significant for some species, were not consistent with time trends for environmental contamination from past alluvial gold mining activities. Fish-Hg bioaccumulation is species specific but fish feeding strategies are the predominant influence in the fish-Hg bioaccumulation pattern. PMID:25863592

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

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Chern, Jiun-Dar

    2005-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

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

    SciTech Connect

    Hedges, J.I. ); Hatcher, P.G. ); Ertel, J.R. ); Meyers-Schulte, K.J. )

    1992-04-01

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

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

    PubMed Central

    2014-01-01

    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

  4. Suspended sediments and organic matter in mountain headwaters of the Amazon River: Results from a 1-year time series study in the central Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Townsend-Small, Amy; McClain, Michael E.; Hall, Bonnie; Noguera, Jorge L.; Llerena, Carlos A.; Brandes, Jay A.

    2008-02-01

    Few studies have examined the dynamics of sediments and suspended organic matter and their export from headwater basins in the Andes Mountains to the Amazon River, despite the fact that the Andes are the primary source of sediments to the lower Amazon basin. We measured river discharge as well as the concentration, δ 15N, δ 13C, %N, and %OC of coarse and fine suspended sediments (CSS and FSS) in the Chorobamba River, located in the central Andean Amazon of Peru. Samples were taken at least weekly over an entire year (July 2004-July 2005), with additional sampling during storms. Concentrations of particulate organic matter (POM) were generally low in the study river, with concentrations increasing by up to several orders of magnitude during episodic rain events. Because both overall flow volumes and POM concentrations increased under stormflow conditions, the export of POM was enhanced multiplicatively during these events. We estimated that a minimum of 80% of annual suspended sediment transfer occurred during only about 10 days of the year, also accounting for 74% of particulate organic carbon and 64% of particulate organic nitrogen transport. Significant differences occurred between seasons (wet and dry) for δ 13C of coarse and fine POM in the Chorobamba River, reflecting seasonal changes in organic matter sources. The time series data indicate that this Andean river exports approximately equal amounts of fine and coarse POM to the lower Amazon. The observation that the vast majority of sediments and associated OM exported from Andean rivers is mobilized during short, infrequent storm events and landslides has important implications for our understanding of Amazon geochemistry, especially in the face of incipient global change.

  5. Change of flooding patterns in the upper Amazon as a consequence of river regime change, a case study of Iquitos city

    NASA Astrophysics Data System (ADS)

    Simon, C. A.; Mendoza, A.; Abad, J. D.; Langendoen, E. J.

    2014-12-01

    Since the 1980s the Amazon basin has experience an intensification of hydrological extreme events, which particularly affects the Andean Rivers. Particularly, the precipitation in the Peruvian Amazon area where Iquitos city is located shows the largest precipitation increment since the 1990s. Rain patterns show larger periods of droughts with more intense rains during the wet season. Recently, this region of the Peruvian Amazonian has experiment the most extreme flooding event since 1970, as a consequence of the change of regime in the rivers, where the extremes have become more pronounced. The extreme flood event that occurred in April 2012 inundated a considerable area of the city, setting a new water surface elevation record of the Amazon River in the zone. To study the impact in the floodplains and nearby Iquitos city, caused by the change of regime in the upper Amazon River, we analysed and simulated the past events to find patterns of inundation during floods. Data utilized for doing so, is based on the compilation and correlation of geological, and hydrological information related to flooding in Iquitos city. River overbank flow is a complex phenomenon that requires a correct representation of the physics. Actual approaches use algorithms that couple horizontally 1D model for the rivers and 2D models for the flood plains. They use over-simplifications for the interaction between flood plain and main channel and are unable to model the transversal momentum above the main channel. For that reason, we developed an algorithm that couples vertically the in-channel and overbank flows. This new model was validated against experimental results. The numerical results show an accurate approximation to the historical inundations of the city. The analysis and modelling shows that the flooding patterns have an substantial change due to the new regime observed in the upper Amazon River.

  6. Transport, distribution and speciation of mercury in the Amazon River at the confluence of black and white waters of the Negro and Solimões Rivers

    NASA Astrophysics Data System (ADS)

    Maurice-Bourgoin, Laurence; Quemerais, Bernadette; Moreira-Turcq, Patricia; Seyler, Patrick

    2003-05-01

    This study describes the transport and speciation of mercury (Hg) and the associated role of organic matter in these processes at the confluence of the Negro (black waters) and Solimões (white waters) Rivers, which form the Amazon River. The Negro has the highest total Hg content (11·6 to 18·2 ng l-1) due to the extreme particulate Hg concentrations (2074 ng g-1 at the surface), 10 to 20 times higher than those measured in other Amazon tributaries. The total organic carbon (TOC) consists primarily of dissolved organic carbon, which corresponds to 89% and 66% of the TOC in the Negro and Solimões Rivers respectively, and is mainly composed of humic substances, carriers for most of the metal ions transported in rivers. At the confluence of the Negro and Solimões Rivers, the total Hg concentrations decrease markedly. An isotopic mass balance showed that the complete mixing of the two rivers was achieved 25 km downstream of the confluence. At 60 km downstream of the confluence, the flux of Hg decreases to 73 kg day-1, which represents a net losses of 5 kg day-1 and 15 kg day-1 of dissolved Hg and particulate Hg respectively, assuming that the discharge was constant during the sampling survey and without significant lateral input. Moreover, the Hg losses are correlated with the total suspended matter concentrations, which vary throughout the mixing zone, and also with the particulate and dissolved organic carbon distribution. We suggest that the dissolved loss occurs during the flocculation of organic matter within the zone of rapidly changing physical and chemical conditions downstream of the confluence, and that the particulate loss is by the deposition of particles along the mixing zone favoured by decreasing stream velocities during the sampling survey. Adsorption processes of Hg on dissolved organic matter seem to be responsible for the decrease of dissolved Hg concentrations in the mixing zone.

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

    SciTech Connect

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

    1987-01-01

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

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

    PubMed

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

    2014-01-01

    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

  9. Mercury Pollution in Soils from the Yacuambi River (Ecuadorian Amazon) as a Result of Gold Placer Mining.

    PubMed

    López-Blanco, Charo; Collahuazo, Luis; Torres, Sandra; Chinchay, Luis; Ayala, Diana; Benítez, Paulina

    2015-09-01

    Gold mining is known to generate important economic products but also to produce several types of contamination/pollution. We report here the first data about Hg concentrations in the soils of the Yacuambi River in the Ecuadorian Amazon. We analyzed soil samples to assess the extent of contamination caused by gold placer mining in this area. Hg concentrations in soils exceeded the local background concentrations. High concentrations of Mn, As, Pb, Cr, Cu, Fe and Zn in some soil samples were probably derived from the geology of the site, which is rich in polysulfides and metamorphic rocks. Placer mining may accelerate the natural release of these elements to the environment by the exposure of the bedrock to the atmosphere. Accumulation of Hg in the river soils may be a potential source of toxicity for aquatic life and a risk to human health in the future. PMID:26183387

  10. 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

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  12. Boat-Based Eddy Covariance Measurements of CO2 and H2O Exchange Over Amazon and Tapajos Rivers and Lakes

    NASA Astrophysics Data System (ADS)

    Miller, S.; Freitas, H.; Read, E.; Goulden, M.; Rocha, H.; Doughty, C.

    2004-12-01

    Recent reports suggest that gas evasion of carbon dioxide from the Amazon river and its tributaries to the atmosphere may play an important role in the regional carbon budget. These gas transfer rates were estimated using air-water concentration gradients and gas transfer coefficients (piston velocities) derived from floating chamber measurements. Chamber techniques have inherent uncertainties due to their effect on the near-surface air turbulence. The micrometeorological technique of eddy covariance is attractive since it is a direct measurement of gas exchange and samples over a much larger area. In August 2004, we mounted equipment on a small riverboat to measure CO2 and H2O fluxes from the rivers and lakes near Santarem, Para. The motion of the boat was recorded using an inertial measurement package combined with a GPS receiver, and subtracted from the measured winds. We experimented with both thin-wall Teflon tubing and headspace equilibrators to measure the concentration of CO2 in the water continuously. Our sampling strategy included both "under-way" measurements and stationary (moored) 24-hour measurements on the Amazon and Tapajos rivers, and lakes connected to these rivers. CO2 concentration in the Amazon river and a connected lake was 3000-5000 ppm, much higher than the Tapajos river and a connected lake (range 400-1200 ppm). The "signal-to-noise" ratio was therefore greater for fluxes measured above the Amazon. Preliminary calculations indicate fluxes of order 1-2 micromoles/m2/s over the Amazon and 0.6-1 micromoles/m2/s over the Tapajos, and the calculated gas transfer velocity agrees with existing ocean-based parameterizations.

  13. 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)

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

    2013-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Aller, Josephine Y.; Aller, Robert C.

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

  15. Changes in the land cover and land use of the Itacaiunas River watershed, arc of deforestation, Carajas, southeastern Amazon

    NASA Astrophysics Data System (ADS)

    Souza-Filho, P. W. M.; Nascimento, W. R., Jr.; Versiani de Mendonca, B. R.; Silva, R. O., Jr.; Guimaraes, J. T. F.; Dall'Agnol, R.; Siqueira, J. O.

    2015-04-01

    Human actions are changing the Amazon's landscape by clearing tropical forest and replacing it mainly by pasturelands. The focus of this work is to assess the changes in the Itacaiunas River watershed; an area located in the southeastern Amazon region, near Carajas, one of the largest mining provinces of the World. We used a Landsat imagery dataset to map and detect land covers (forest and montane savanna) and land use (pasturelands, mining and urban) changes from 1984 to 2013. We employed standard image processing techniques in conjunction with visual interpretation and geographic object-based classification. Land covers and land use (LCLU) "from-to" change detection approach was carried out to recognize the trajectories of LCLU classes based on object change detection analysis. We observed that ~47% (~1.9 million ha) of forest kept unchanged; almost 41% (~1.7 million ha) of changes was associated to conversion from forest to pasture, while 8% (~333,000 ha) remained unchanged pasture. The conversion of forest and montane savannah to mining area represents only 0.24% (~9,000 ha). We can conclude that synergy of visual interpretation to discriminate fine level objects with low contrast associated to urban, mining and savanna classes; and automatic classification of coarse level objects related to forest and pastureland classes is most successfully than use these methods individually. In essence, this approach combines the advantages of the human quality interpretation and quantitative computing capacity.

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

    PubMed

    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

    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

  17. Spatial variability of soil carbon stock in the Urucu river basin, Central Amazon-Brazil.

    PubMed

    Ceddia, Marcos Bacis; Villela, André Luis Oliveira; Pinheiro, Érika Flávia Machado; Wendroth, Ole

    2015-09-01

    The Amazon Forest plays a major role in C sequestration and release. However, few regional estimates of soil organic carbon (SOC) stock in this ecoregion exist. One of the barriers to improve SOC estimates is the lack of recent soil data at high spatial resolution, which hampers the application of new methods for mapping SOC stock. The aims of this work were: (i) to quantify SOC stock under undisturbed vegetation for the 0-30 and the 0-100 cm under Amazon Forest; (ii) to correlate the SOC stock with soil mapping units and relief attributes and (iii) to evaluate three geostatistical techniques to generate maps of SOC stock (ordinary, isotopic and heterotopic cokriging). The study site is located in the Central region of Amazon State, Brazil. The soil survey covered the study site that has an area of 80 km(2) and resulted in a 1:10,000 soil map. It consisted of 315 field observations (96 complete soil profiles and 219 boreholes). SOC stock was calculated by summing C stocks by horizon, determined as a product of BD, SOC and the horizon thickness. For each one of the 315 soil observations, relief attributes were derived from a topographic map to understand SOC dynamics. The SOC stocks across 30 and 100 cm soil depth were 3.28 and 7.32 kg C m(-2), respectively, which is, 34 and 16%, lower than other studies. The SOC stock is higher in soils developed in relief forms exhibiting well-drained soils, which are covered by Upland Dense Tropical Rainforest. Only SOC stock in the upper 100 cm exhibited spatial dependence allowing the generation of spatial variability maps based on spatial (co)-regionalization. The CTI was inversely correlated with SOC stock and was the only auxiliary variable feasible to be used in cokriging interpolation. The heterotopic cokriging presented the best performance for mapping SOC stock. PMID:25918893

  18. Surface water types and sediment distribution patterns at the confluence of mega rivers: The Solimões-Amazon and Negro Rivers junction

    NASA Astrophysics Data System (ADS)

    Park, Edward; Latrubesse, Edgardo M.

    2015-08-01

    Large river channel confluences are recognized as critical fluvial features because both intensive and extensive hydrophysical and geoecological processes take place at this interface. However, identifications of suspended sediment routing patterns through channel junctions and the roles of tributaries on downstream sediment transport in large rivers are still poorly explored. In this paper, we propose a remote sensing-based approach to characterize the spatiotemporal patterns of the postconfluence suspended sediment transport by mapping the surface water distribution in the ultimate example of large river confluence on Earth where distinct water types meet: The Solimões-Amazon (white water) and Negro (black water) rivers. The surface water types distribution was modeled for three different years: average hydrological condition (2007) and 2 years when extreme events occurred (drought-2005 and flood-2009). Amazonian surface water domination along the main channel is highest during the water discharge rising season. Surface water mixing along the main channel depends on the hydrological seasons with the highest mixed-homogenized area observed during water discharge peak season and the lowest during discharge rising season. Water mixture also depends on the yearly hydrological regime with the highest rates of water mixing in 2009, followed by 2005 and 2007. We conclude that the dominant mixing patterns observed in this study have been persistent over a decadal scale and the anabranching patterns contribute to avoid a faster mixing in a shorter distance. Our proposed approach can be applied to a variety of morphodynamic and environmental analyses in confluences of large rivers around the world.

  19. Interannual variability patterns of the world's total column water content: Amazon River basin

    NASA Astrophysics Data System (ADS)

    Bordi, Isabella; De Bonis, Roberto; Fraedrich, Klaus; Sutera, Alfonso

    2015-11-01

    Global trend patterns of yearly mean total column water (TCW) from the European Centre for Medium Range Weather Forecasts (ECMWF) 20th century atmosphere model ERA-20CM (1900-2009) and the currently state-of-the-art reanalysis ERA-Interim (1979-2012) show common features of statistically significant upward trends. Of particular interest appears a pronounced regional dipole pattern of interannual climate variability over the South American continent particularly evident in ERA-Interim data. The trend dipole affects two distinct areas: the Andean Amazon basin and the Northeast Brazil. The target regions are characterized by rising and decreasing water content associated with water vapor convergence (divergence) and upward (downward) mass fluxes, respectively. As expected, local water vapor feedback due to local surface temperature change does to not fully explain this TCW trend dipole; other mechanisms may play a role in establishing the observed feature such as moisture transports and monsoon variability in the last decade. The observed trends of the normalized difference vegetation index (NDVI) during the period 1982-2005 show an increasing greenness that coincides with the moistening of the atmospheric column in the Amazon basin. These results are substantiated by two single-station ground-based GPS measurements of TCW vapor (TCWV) from the two target regions.

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

    USGS Publications Warehouse

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

    2004-01-01

    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.

  1. 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)

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

    2014-05-01

    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.

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

    PubMed

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

    2012-09-01

    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 μg g(-1) for non piscivores; 0.088 μg g(-1) for piscivores), intermediate values (average of 0.05 and 0.104 μg g(-1)) in unperturbed white water river, whereas the highest values (average of 0.062 and 0.194 μg 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

  3. 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)

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

    2013-05-01

    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 Kosipata 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.

  4. Cytogenetic variation of repetitive DNA elements in Hoplias malabaricus (Characiformes - Erythrinidae) from white, black and clear water rivers of the Amazon basin.

    PubMed

    Santos, Fabíola Araújo Dos; Marques, Diego Ferreira; Terencio, Maria Leandra; Feldberg, Eliana; Rodrigues, Luís Reginaldo R

    2016-03-01

    Hoplias malabaricus is a common fish species occurring in white, black and clear water rivers of the Amazon basin. Its large distribution across distinct aquatic environments can pose stressful conditions for dispersal and creates possibilities for the emergence of local adaptive profiles. We investigated the chromosomal localization of repetitive DNA markers (constitutive heterochromatin, rDNA and the transposable element REX-3) in populations from the Amazonas river (white water), the Negro river (black water) and the Tapajós river (clear water), in order to address the variation/association of cytogenomic features and environmental conditions. We found a conserved karyotypic macrostructure with a diploid number of 40 chromosomes (20 metacentrics + 20 submetacentrics) in all the samples. Heteromorphism in pair 14 was detected as evidence for the initial differentiation of an XX/XY system. Minor differences detected in the amount of repetitive DNA markers are interpreted as possible signatures of local adaptations to distinct aquatic environments. PMID:27007897

  5. Cytogenetic variation of repetitive DNA elements in Hoplias malabaricus (Characiformes - Erythrinidae) from white, black and clear water rivers of the Amazon basin

    PubMed Central

    dos Santos, Fabíola Araújo; Marques, Diego Ferreira; Terencio, Maria Leandra; Feldberg, Eliana; Rodrigues, Luís Reginaldo R.

    2016-01-01

    Abstract Hoplias malabaricus is a common fish species occurring in white, black and clear water rivers of the Amazon basin. Its large distribution across distinct aquatic environments can pose stressful conditions for dispersal and creates possibilities for the emergence of local adaptive profiles. We investigated the chromosomal localization of repetitive DNA markers (constitutive heterochromatin, rDNA and the transposable element REX-3) in populations from the Amazonas river (white water), the Negro river (black water) and the Tapajós river (clear water), in order to address the variation/association of cytogenomic features and environmental conditions. We found a conserved karyotypic macrostructure with a diploid number of 40 chromosomes (20 metacentrics + 20 submetacentrics) in all the samples. Heteromorphism in pair 14 was detected as evidence for the initial differentiation of an XX/XY system. Minor differences detected in the amount of repetitive DNA markers are interpreted as possible signatures of local adaptations to distinct aquatic environments. PMID:27007897

  6. The optical properties of river and floodplain waters in the Amazon River Basin: Implications for satellite-based measurements of suspended particulate matter

    NASA Astrophysics Data System (ADS)

    Martinez, Jean-Michel; Espinoza-Villar, Raul; Armijos, Elisa; Silva Moreira, Luciane

    2015-07-01

    Satellite images can now be used to assess river sediment discharge, and systematic studies over rivers and lakes are required to support such applications and document the variability of inland water optical properties at the watershed scale. The optical properties of the Amazon Basin waters were analyzed from in situ measurements of the remote sensing reflectance (Rrs) at 279 stations and downwelling diffuse attenuation coefficients (Kd) at 133 stations. Measurements of the apparent optical properties, suspended particulate matter (SPM) contents, and characteristics and colored dissolved organic matter (CDOM) absorption spectra were performed during 16 cruises along the main Amazonian Rivers draining the Andes and for some tributaries. Surface-suspended sediment granulometry and mineralogy showed a stable distribution at the catchment scale, even over large distances and between tributaries. The particle number-size distribution was best described using a segmented distribution with a slope of 2.2 for the fine range (1-15 µm), and the CDOM absorption coefficient at 440 nm varied from 1.8 to 7.9 m-1. Overall, both Rrs and Kd were strongly correlated with SPM, although strong CDOM absorption limited the use of the blue spectrum. Reflectance saturation from blue to red was observed at approximately 100 g m-3, whereas the near-infrared (NIR) wavelength enabled the monitoring of the full SPM range (5-620 g m-3). In contrast, Kd showed no saturation for SPM from green to NIR, and a linear model was calculated. The use of the reflectance ratio was investigated and shown to improve the suspended sediment concentration retrieval performance.

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  8. Estimating population structure under nonequilibrium conditions in a conservation context: continent-wide population genetics of the giant Amazon river turtle, Podocnemis expansa (Chelonia; Podocnemididae).

    PubMed

    Pearse, Devon E; Arndt, Allan D; Valenzuela, Nicole; Miller, Becky A; Cantarelli, Vitor; Sites, Jack W

    2006-04-01

    Giant Amazon river turtles, Podocnemis expansa, are indigenous to the Amazon, Orinoco, and Essequibo River basins, and are distributed across nearly the entire width of the South American continent. Although once common, their large size, high fecundity, and gregarious nesting, made P. expansa especially vulnerable to over-harvesting for eggs and meat. Populations have been severely reduced or extirpated in many areas throughout its range, and the species is now regulated under Appendix II of the Convention on International Trade in Endangered Species. Here, we analyse data from mitochondrial DNA sequence and multiple nuclear microsatellite markers with an array of complementary analytical methods. Results show that concordance from multiple data sets and analyses can provide a strong signal of population genetic structure that can be used to guide management. The general lack of phylogeographic structure but large differences in allele and haplotype frequencies among river basins is consistent with fragmented populations and female natal-river homing. Overall, the DNA data show that P. expansa populations lack a long history of genetic differentiation, but that each major tributary currently forms a semi-isolated reproductive population and should be managed accordingly. PMID:16599962

  9. A checklist for the zooplankton of the Middle Xingu - an Amazon River system.

    PubMed

    Brito, S A C; Camargo, M; Melo, N F A C; Estupiñan, R A

    2015-08-01

    A zooplankton checklist is presented for the Middle Xingu River, based on surveys conducted at four sites in the main channel and two fluvial lakes. A total of 175 taxa are listed, including 141 rotifers, 20 cladocerans, and five copepods. Rapids presented the greatest species richness, with up to 124 taxa, while Ilha Grande lake had 70 taxa, the lowest number. Non-planktonic benthic larvae were recorded frequently in the samples. PMID:26691076

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

    USGS Publications Warehouse

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

    2008-01-01

    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.

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

    PubMed

    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

    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

  12. Population and biological parameters of selected fish species from the middle Xingu River, Amazon Basin.

    PubMed

    Camargo, M; Giarrizzo, T; Isaac, V J

    2015-08-01

    This study estimates the main biological parameters, including growth rates, asymptotic length, mortality, consumption by biomass, biological yield, and biomass, for the most abundant fish species found on the middle Xingu River, prior to the construction of the Belo Monte Dam. The specimens collected in experimental catches were analysed with empirical equations and length-based FISAT methods. For the 63 fish species studied, high growth rates (K) and high natural mortality (M) were related to early sexual maturation and low longevity. The predominance of species with short life cycles and a reduced number of age classes, determines high rates of stock turnover, which indicates high productivity for fisheries, and a low risk of overfishing. PMID:26691084

  13. Resource availability and diet in Harpy Eagle breeding territories on the Xingu River, Brazilian Amazon.

    PubMed

    Aguiar-Silva, F H; Junqueira, T G; Sanaiotti, T M; Guimarães, V Y; Mathias, P V C; Mendonça, C V

    2015-08-01

    In the Tapajos-Xingu interfluve, one of the largest birds of prey, the Harpy Eagle, is under intense anthropogenic pressure due to historical and recent reductions in forest cover. We studied prey availability and use by Harpy Eagle on six breeding territories on the low- and mid-Xingu River, between 2013 and 2015. We evaluated food resource availability using the environmental-surveys database from two methods: terrestrial surveys (RAPELD method) and fauna rescue/flushing before vegetation suppression for the Belo Monte Hydroelectric Complex construction. Harpy Eagle diet was identified by prey remains sampled around six nest trees. Eighteen species of mammals, birds and reptiles comprised the prey items. Most prey species were sloths, primates and porcupines, which have arboreal habits and are found in forested areas, but two species, hoatzin and iguana, are usually associated with riverine habitats. The proportion of prey from each species predated on the nest best studied was different from estimated availability (χ2 = 54.23; df = 16; p < 0.001), however there was a positive correlation (rs = 0.7; p < 0.01) between prey species consumed and abundance available, where the predation was more on species more abundant. Continuous monitoring of the Harpy Eagle diet at these nests could evidence changes in the assemblage of prey species available for Harpy Eagles, due to changes in the seasonal flood pulse of the Xingu River to be caused by the operation of the hydroelectric dam, and changes in habitat features by forest reduction around breeding territories. We believe that it is important to consider the protection of remnants of forested areas in the landscape matrix surrounding the breeding territories to maintain the food resource availability and allow all pairs to successfully reproduce. PMID:26691092

  14. Evaluation of monotonic trends for streamflow in austral Amazon, Brazil: a case study for the Xingu and Tapajós rivers

    NASA Astrophysics Data System (ADS)

    Moura, L. Z.

    2015-06-01

    This paper has the goal of evaluating monotonic trends in the Xingu and Tapajós river basins in the Austral Amazon region, Brazil. Non-parametric statistical tests such as Mann-Kendall, Bootstrap Mann-Kendall, Sen and Bootstrap Sen are applied on streamflow gauging stations data, to determine the significance and magnitude of possible trends. Data in these river basins is relatively scarce, with time series ranging from twenty to forty years, having many gaps. Former studies indicate a decreasing trend for both annual average and minimum streamflow values in the Tapajós river basin, with 99% confidence level, and a decrease in maximum values in the Xingu river basin, with 90% confidence level. However, past analyses have only used one station near the basin outlet. This study uses data from 7 gauging stations in the Xingu basin and 14 stations in the Tapajós basin. Results indicate opposite trends at the 95% confidence level for different regions in the basins, and for different flow regimes. For the Xingu river basin, trends in the minimum flow for different sub-basins even out at the Altamira station, near its outlet. For the Tapajós river, the southeastern part of the basin has increasing trends, while the southwestern part decreases. At the Itaituba station, they also balance out.

  15. Post-confluence surface water and sediment distribution patterns of the Solimões-Amazon and Negro Rivers: a remote sensing-based geomorphic study of surface patterns at the large rivers confluences

    NASA Astrophysics Data System (ADS)

    Park, Edward; Latrubesse, Edgardo

    2015-04-01

    River channel confluences are recognized as critical features of the fluvial system, because both intensive and extensive hydro-physical and geo-ecological processes take place within this momentous interface. Despite the relevant findings on confluences as listed above, only a few cases concentrated on field measurements in large rivers. Along with improvements in hydrographic and geochemical surveying techniques, trials have been occasionally made to improve understanding of larger rivers confluences and their downstream hydro-morphodynamics, such as in some reaches of the Amazon, Brahmaputra, Jamuna, and Paraná Rivers. However, finite collections of point-based and cross-sectional measurements obtained from field using acoustic Doppler current profiler (ADCP), multi-beam echo sounder, global positioning system (GPS) or other geochemical applications (e.g. isotope tracing) around river confluences provide limited information of post-confluence hydro-geomorphologic behaviors. The identification of sediment routing through channel junctions and the role of confluence on downstream sediment transport is still poorly understood. Into this context, satellite remote sensing is the most relevant and efficient mean to regularly monitor the river sediment discharge over the large (regional to continental) scale. In this paper, we aim to characterize the spatiotemporal patterns of post-confluence sediment transport by mapping the surface water distribution using the ultimate example of large river confluence on Earth, where distinct water types drain: The Solimões-Amazon (muddy-white water) versus Negro (black water) Rivers, exploring the seasonal and inter-annual variations of water types and the spatial distribution patterns of surface waters through the branches of the main stem.

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

    PubMed

    Fearnside, Phillip M

    2006-07-01

    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

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

    NASA Astrophysics Data System (ADS)

    Fearnside, Phillip M.

    2006-07-01

    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.

  18. 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)

    Carmona, A. M.; Poveda, G.

    2011-12-01

    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.

  19. Scorched mussels (Brachidontes spp., Bivalvia: Mytilidae) from the tropical and warm-temperate southwestern Atlantic: the role of the Amazon River in their speciation.

    PubMed

    Trovant, Berenice; Basso, Néstor G; Orensanz, José María; Lessa, Enrique P; Dincao, Fernando; Ruzzante, Daniel E

    2016-03-01

    Antitropicality is a distribution pattern where closely related taxa are separated by an intertropical latitudinal gap. Two potential examples include Brachidontes darwinianus (south eastern Brazil to Uruguay), considered by some authors as a synonym of B. exustus (Gulf of Mexico and the Caribbean), and B. solisianus, distributed along the Brazilian coast with dubious records north of the intertropical zone. Using two nuclear (18S and 28S rDNA) and one mitochondrial gene (mtDNA COI), we aimed to elucidate the phylogeographic and phylogenetic relationships among the scorched mussels present in the warm-temperate region of the southwest Atlantic. We evaluated a divergence process mediated by the tropical zone over alternative phylogeographic hypotheses. Brachidontes solisianus was closely related to B. exustus I, a species with which it exhibits an antitropical distribution. Their divergence time was approximately 2.6 Ma, consistent with the intensification of Amazon River flow. Brachidontes darwinianus, an estuarine species is shown here not to be related to this B. exustus complex. We suspect ancestral forms may have dispersed from the Caribbean to the Atlantic coast via the Trans-Amazonian seaway (Miocene). The third species, B rodriguezii is presumed to have a long history in the region with related fossil forms going back to the Miocene. Although scorched mussels are very similar in appearance, their evolutionary histories are very different, involving major historical contingencies as the formation of the Amazon River, the Panama Isthmus, and the last marine transgression. PMID:26929816

  20. Delimiting Evolutionarily Significant Units of the Fish, Piaractus brachypomus (Characiformes: Serrasalmidae), from the Orinoco and Amazon River Basins with Insight on Routes of Historical Connectivity.

    PubMed

    Escobar, Maria Doris; Andrade-López, Juana; Farias, Izeni P; Hrbek, Tomas

    2015-01-01

    The freshwater fish Piaractus brachypomus is an economically important for human consumption both in commercial fisheries and aquaculture in all South American countries where it occurs. In recent years the species has decreased in abundance due to heavy fishing pressure. The species occurs in the Amazon and Orinoco basins, but lack of meristic differences between fishes from the 2 basins, and extensive migration associated with reproduction, have resulted in P. brachypomus being considered a single panmictic species. Analysis of 7 nuclear microsatellites, mitochondrial DNA sequences (D-loop and COI), and body shape variables demonstrated that each river basin is populated by a distinct evolutionarily significant unit (ESU); the 2 groups had an average COI divergence of 3.5% and differed in body depth and relative head length. Historical connection between the 2 basins most probably occurred via the Rupununi portal rather than via the Casiquiare canal. The 2 ESUs will require independent fishery management, and translocation of fisheries stocks between basins should be avoided to prevent loss of local adaptations or extinction associated with outbreeding depression. Introductions of fishes from the Orinoco basin into the Putumayo River basin, an Amazon basin drainage, and evidence of hybridization between the 2 ESUs have already been detected. PMID:26245778

  1. Mixing in the Amazon estuary

    NASA Astrophysics Data System (ADS)

    Bezerra, M. O.

    2010-05-01

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

  2. How livestock and flooding mediate the ecological integrity of working forests in Amazon River floodplains.

    PubMed

    Lucas, Christine M; Sheikh, Pervaze; Gagnon, Paul R; Mcgrath, David G

    2016-01-01

    The contribution of working forests to tropical conservation and development depends upon the maintenance of ecological integrity under ongoing land use. Assessment of ecological integrity requires an understanding of the structure, composition, and function and major drivers that govern their variability. Working forests in tropical river floodplains provide many goods and services, yet the data on the ecological processes that sustain these services is scant. In flooded forests of riverside Amazonian communities, we established 46 0.1-ha plots varying in flood duration, use by cattle and water buffalo, and time since agricultural abandonment (30-90 yr). We monitored three aspects of ecological integrity (stand structure, species composition, and dynamics of trees and seedlings) to evaluate the impacts of different trajectories of livestock activity (alleviation, stasis, and intensification) over nine years. Negative effects of livestock intensification were solely evident in the forest understory, and plots alleviated from past heavy disturbance increased in seedling density but had higher abundance of thorny species than plots maintaining low activity. Stand structure, dynamics, and tree species composition were strongly influenced by the natural pulse of seasonal floods, such that the defining characteristics of integrity were dependent upon flood duration (3-200 d). Forests with prolonged floods ≥ 140 d had not only lower species richness but also lower rates of recruitment and species turnover relative to forests with short floods <70 d. Overall, the combined effects of livestock intensification and prolonged flooding hindered forest regeneration, but overall forest integrity was largely related to the hydrological regime and age. Given this disjunction between factors mediating canopy and understory integrity, we present a subset of metrics for regeneration and recruitment to distinguish forest condition by livestock trajectory. Although our study design includes confounded factors that preclude a definitive assessment of the major drivers of ecological change, we provide much-needed data on the regrowth of a critical but poorly studied ecosystem. In addition to its emphasis on the dynamics of tropical wetland forests undergoing anthropogenic and environmental change, our case study is an important example for how to assess of ecological integrity in working forests of tropical ecosystems. PMID:27039519

  3. Seasonal and interannual variability of sea-air CO2 fluxes in the tropical Atlantic affected by the Amazon River plume

    NASA Astrophysics Data System (ADS)

    Ibánhez, J. Severino P.; Diverrès, Denis; Araujo, Moacyr; Lefèvre, Nathalie

    2015-10-01

    CO2 fugacities obtained from a merchant ship sailing from France to French Guyana were used to explore the seasonal and interannual variability of the sea-air CO2 exchange in the western tropical North Atlantic (TNA; 5-14°N, 41-52°W). Two distinct oceanic water masses were identified in the area associated to the main surface currents, i.e., the North Brazil Current (NBC) and the North Equatorial Current (NEC). The NBC was characterized by permanent CO2 oversaturation throughout the studied period, contrasting with the seasonal pattern identified in the NEC. The NBC retroflection was the main contributor to the North Equatorial Counter Current (NECC), thus spreading into the central TNA, the Amazon River plume, and the CO2-rich waters probably originated from the equatorial upwelling. Strong CO2 undersaturation was associated to the Amazon River plume. Total inorganic carbon drawdown due to biological activity was estimated to be 154 µmol kg-1 within the river plume. As a consequence, the studied area acted as a net sink of atmospheric CO2 (from -72.2 ± 10.2 mmol m-2 month-1 in February to 14.3 ± 4.5 mmol m-2 month-1 in May). This contrasted with the net CO2 efflux estimated by the main global sea-air CO2 flux climatologies. Interannual sea surface temperature changes in the TNA caused by large-scale climatic events could determine the direction and intensity of the sea-air CO2 fluxes in the NEC. Positive temperature anomalies observed in the TNA led to an almost permanent CO2 outgassing in the NEC in 2010.

  4. Southern oscillation and the northern australian prawn catch

    NASA Astrophysics Data System (ADS)

    Catchpole, A.; Auliciems, A.

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

  5. A scaling approach to Budyko's framework and the complementary relationship of evapotranspiration in humid environments: case study of the Amazon River basin

    NASA Astrophysics Data System (ADS)

    Carmona, A. M.; Poveda, G.; Sivapalan, M.; Vallejo-Bernal, S. M.; Bustamante, E.

    2016-02-01

    This paper studies a 3-D state space representation of Budyko's framework designed to capture the mutual interdependence among long-term mean actual evapotranspiration (E), potential evapotranspiration (Ep) and precipitation (P). For this purpose we use three dimensionless and dependent quantities: Ψ = E ⁄ P, Φ = Ep ⁄ P and Ω = E ⁄ Ep. This 3-D space and its 2-D projections provide an interesting setting to test the physical soundness of Budyko's hypothesis. We demonstrate analytically that Budyko-type equations are unable to capture the physical limit of the relation between Ω and Φ in humid environments, owing to the unfeasibility of Ep ⁄ P = 0 when E ⁄ Ep → 1. Using data from 146 sub-catchments in the Amazon River basin we overcome this inconsistency by proposing a physically consistent power law: Ψ = kΦe, with k = 0.66, and e = 0.83 (R2 = 0.93). This power law is compared with two other Budyko-type equations. Taking into account the goodness of fits and the ability to comply with the physical limits of the 3-D space, our results show that the power law is better suited to model the coupled water and energy balances within the Amazon River basin. Moreover, k is found to be related to the partitioning of energy via evapotranspiration in terms of Ω. This suggests that our power law implicitly incorporates the complementary relationship of evapotranspiration into the Budyko curve, which is a consequence of the dependent nature of the studied variables within our 3-D space. This scaling approach is also consistent with the asymmetrical nature of the complementary relationship of evapotranspiration. Looking for a physical explanation for the parameters k and e, the inter-annual variability of individual catchments is studied. Evidence of space-time symmetry in Amazonia emerges, since both between-catchment and between-year variability follow the same Budyko curves. Finally, signs of co-evolution of catchments are explored by linking spatial patterns of the power law parameters with fundamental characteristics of the Amazon River basin. In general, k and e are found to be related to vegetation, topography and water in soils.

  6. A scaling approach to Budyko's framework and the complementary relationship of evapotranspiration in humid environments: case study of the Amazon River basin

    NASA Astrophysics Data System (ADS)

    Carmona, A. M.; Poveda, G.; Sivapalan, M.; Vallejo-Bernal, S. M.; Bustamante, E.

    2015-10-01

    This paper studies a 3-D generalization of Budyko's framework designed to capture the mutual interdependence among long-term mean actual evapotranspiration (E), potential evapotranspiration (Ep) and precipitation (P). For this purpose we use three dimensionless and dependent quantities: Ψ = E/P, Φ = Ep/P and Ω = E/Ep. This 3-D space and its 2-D projections provide an interesting setting to test the physical soundness of Budyko's hypothesis. We demonstrate analytically that Budyko-type equations are unable to capture the physical limit of the relation between Ω and Φ in humid environments, owing to the unfeasibility of Ep/P → 0 at E/Ep = 1. Using data from 146 sub-catchments in the Amazon River basin we overcome this inconsistency by proposing a physically consistent power law: Ψ = k Φe, with k = 0.66, and e = 0.83 (R2 = 0.93). This power law is compared with two other Budyko-type equations. Taking into account the goodness of fits and the ability to comply with the physical limits of the 3-D space, our results show that the power law is better suited to model the coupled water and energy balances within the Amazon River basin. Moreover, k is found to be related to the partitioning of energy via evapotranspiration in terms of Ω. This suggests that our power law implicitly incorporates the complementary relationship of evapotranspiration into the Budyko curve, which is a consequence of the dependent nature of the studied variables within our 3-D space. This scaling approach is also consistent with the asymmetrical nature of the complementary relationship of evapotranspiration. Looking for a physical explanation for the parameters k and e, the inter-annual variability of individual catchments is studied. Evidence of space-time symmetry in Amazonia emerges, since both between-catchment and between-year variability follow the same Budyko curves. Finally, signs of co-evolution of catchments are explored by linking spatial patterns of the power law parameters with fundamental characteristics of the Amazon River basin. In general, k and e are found to be related to vegetation, topography and water in soils.

  7. 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)

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

    1999-06-01

    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.

  8. Acoustic characteristics of biosonar sounds of free-ranging botos (Inia geoffrensis) and tucuxis (Sotalia fluviatilis) in the Negro River, Amazon, Brazil.

    PubMed

    Yamamoto, Yukiko; Akamatsu, Tomonari; da Silva, Vera M F; Yoshida, Yayoi; Kohshima, Shiro

    2015-08-01

    Odontoceti emit broadband high-frequency clicks on echolocation for orientation or prey detection. In the Amazon Basin, two odontoceti species, boto (Amazon River dolphin, Inia geoffrensis) and tucuxi (Sotalia fluviatilis), live sympatrically. The acoustic characteristics of the echolocation clicks of free-ranging botos and tucuxis were measured with a hydrophone array consisting of a full-band and an acoustic event recorder (A-tag). The clicks of the two species were short-duration broadband signals. The apparent source level was 201 dB 1 μPa peak-to-peak at 1 m in the botos and 181 dB 1 μPa peak-to-peak at 1 m in the tucuxis, and the centroid frequency was 82.3 kHz in the botos and 93.1 kHz in the tucuxis. The high apparent source level and low centroid frequency are possibly due to the difference in body size or sound production organs, especially the nasal structure, the sound source of clicks in odontoceti. PMID:26328686

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

    PubMed

    Santana, I F; Freitas, C E C

    2013-02-01

    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

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

    PubMed

    Nery, José Reinaldo Cardoso; Bonotto, Daniel Marcos

    2011-04-01

    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

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

    PubMed

    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

    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

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

    PubMed Central

    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

    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

  13. The importance of estuarine gravitational circulation in the early life of the Bohai Penaeid Prawn

    NASA Astrophysics Data System (ADS)

    Dong, Lixian; Su, Jilan; Deng, Jingyao; Chen, Qi

    2007-09-01

    Estuaries along the southern shore of the Bohai Sea are the major habitat of the Bohai Penaeid Prawn ( Penaeus chinensis). Since the 80's, however, many of the rivers have been dammed. Field observations, as well as laterally integrated 2-D numerical experiments, were conducted to understand both the role of estuarine gravitational circulation and the impact of the damming of the rivers on the early life of the Bohai Penaeid Prawn. For a river with runoff, especially for small discharge, the gravitational circulation tends to transport the planktonic larvae in their metamorphosis phase near the river mouth where condition is favorable for survival. The gravitational circulation inside the estuary tends to transport the mysis phase larvae towards the upstream end of the estuary when the most part of the larvae suspended in the bottom layer, and it transports the post larvae to the low salinity near upstream side of the estuary when the larvae become benthic, if the larvae enter the estuary. Damming causes long periods of zero runoff in the river, resulting in the alteration of the estuarine circulation and in the change of the estuarine environment. In addition, excess evaporation may prematurely transport the planktonic larvae into the estuary. On the other hand, sudden release of a large volume of freshwater from behind the dam may exert undesirable stress on the larvae.

  14. Assimilating in situ and radar altimetry data into a large-scale hydrologic-hydrodynamic model for streamflow forecast in the Amazon River basin

    NASA Astrophysics Data System (ADS)

    Paiva, R. C.; Collischonn, W.; Bonnet, M.; Goncalves, L.; Getirana, A.; Calmant, S.

    2012-12-01

    Large-scale hydrological models and forecast systems may be important tools to reduce the vulnerability of local population in places such as the Amazon River basin, where extreme hydrological events have occurred in the past few years. Due to the size of the basin and the slow speed of movement of its floods, uncertainty on model initial conditions (ICs) may play an important role for discharge forecasts using large scale hydrological models, even for relatively large lead times (~ 1 to 3 months). Data assimilation (DA) methods may provide an interesting way of merging both in situ and newly remotely sensed observations with models to estimate optimal ICs. We present the development and evaluation of a data assimilation framework for both gauged and radar altimetry based discharge and water levels into a large scale hydrological-hydrodynamic model of the Amazon River basin. We also explore the usefulness of such system to provide streamflow forecasts when forced by past climate and based mostly on model initial conditions. This work is in the context of recent developments of techniques for integrating information from models and remotely sensed data, and also of regional/global hydrological forecast systems including poorly gauged basins. We use the conceptual and physically based MGB-IPH model. The model uses the Penman Monteith for evapotranspiration and the Moore and Clarke model for soil water storage. River dynamics is simulated using full Saint-Venant equations and a simple floodplain storage model. The model was forced using satellite-derived daily rainfall (TRMM 3B42). We implemented a DA scheme based on the Ensemble Kalman Filter (EnKF) capable of assimilating three types of data: (1) discharge observations; (2) water levels provided by the ENVISAT radar altimeter; and (3) discharge estimated from radar altimetry. All state variables of the hydrological model were updated at each analyses time step. Model state variables errors were generated by perturbing the precipitation forcing field from the original value, using log-normally distributed, time and spatially correlated error fields. Streamflow forecasts were generated using an ensemble streamflow prediction approach, where the model starts with initial conditions obtained from the data assimilation step and where the model is forced by an ensemble of observed precipitation time series resampled from past years. First experiments show that an EnKF based assimilation of discharge observations and remotely sensed water levels improve estimates of the large scale hydrologic-hydrodynamic model in the Amazon River basin. Results improve mostly in large tributaries and in some cases errors increase at smaller rivers. Assimilation of water levels can also improve discharge estimates at gauges located near ENVISAT altimetry stations. We show the evaluation of the DA scheme using different configurations and kinds of observations. Finally, we evaluate the accuracy of streamflow forecasts at different spatial scales and lead times.

  15. Food sources and carbon dudget of chinese prawn Penaeus chinensis

    NASA Astrophysics Data System (ADS)

    Dong, Shuang-Lin; Zhang, Shuo; Wang, Fang

    2002-03-01

    This study deals with contribution of artificial food pellet and natural food to Chinese prawn ( Penaeus orientalis) growth in a semi-intensive culture pond. The prawn carbon consumption, budget, and the effects of some factors on the budget were investigated. The results showed that 26.2% of P. orientalis growth carbon came from formulated feed at the initial culture stage (when the prawns were 0.06±0.01 g in wet weight), and was 62.5% when the prawns were 9.56±1.04 g. The remaining part of the growth carbon was derived from organic fertilizer and natural food. The highest growth rate occurred at 20×10-3 salinity. Suitable salinity for culturing Chinese prawn was (20 28)×10-3.

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

    PubMed

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

    2009-05-01

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

  17. Four decades of land-cover, land-use and hydroclimatology changes in the Itacaiúnas River watershed, southeastern Amazon.

    PubMed

    Souza-Filho, Pedro Walfir M; de Souza, Everaldo B; Silva Júnior, Renato O; Nascimento, Wilson R; Versiani de Mendonça, Breno R; Guimarães, José Tasso F; Dall'Agnol, Roberto; Siqueira, José Oswaldo

    2016-02-01

    Long-term human-induced impacts have significantly changed the Amazonian landscape. The most dramatic land cover and land use (LCLU) changes began in the early 1970s with the establishment of the Trans-Amazon Highway and large government projects associated with the expansion of agricultural settlement and cattle ranching, which cleared significant tropical forest cover in the areas of new and accelerated human development. Taking the changes in the LCLU over the past four decades as a basis, this study aims to determine the consequences of land cover (forest and savanna) and land use (pasturelands, mining and urban) changes on the hydroclimatology of the Itacaiúnas River watershed area of the located in the southeastern Amazon region. We analyzed a multi-decadal Landsat dataset from 1973, 1984, 1994, 2004 and 2013 and a 40-yr time series of water discharge from the Itacaiúnas River, as well as air temperature and relative humidity data over this drainage area for the same period. We employed standard Landsat image processing techniques in conjunction with a geographic object-based image analysis and multi-resolution classification approach. With the goal of detecting possible long-term trends, non-parametric Mann-Kendall test was applied, based on a Sen slope estimator on a 40-yr annual PREC, TMED and RH time series, considering the spatial average of the entire watershed. In the 1970s, the region was entirely covered by forest (99%) and savanna (∼0.3%). Four decades later, only ∼48% of the tropical forest remains, while pasturelands occupy approximately 50% of the watershed area. Moreover, in protected areas, nearly 97% of the tropical forest remains conserved, while the forest cover of non-protected areas is quite fragmented and, consequently, unevenly distributed, covering an area of only 30%. Based on observational data analysis, there is evidence that the conversion of forest cover to extensive and homogeneous pasturelands was accompanied by systematic modifications to the hydroclimatology cycle of the Itacaiúnas watershed, thus highlighting drier environmental conditions due to a rise in the region's air temperature, a decrease in the relative humidity, and an increase in river discharge. PMID:26686070

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  19. 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)

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

    2013-07-01

    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.

  20. Combining precipitation data from observed and numerical models to forecast precipitation characteristics in sparsely-gauged watersheds: an application to the Amazon River basin.

    NASA Astrophysics Data System (ADS)

    Dwelle, M. C.; Ivanov, V. Y.; Berrocal, V.

    2014-12-01

    Forecasting rainfall in areas with sparse monitoring efforts is critical to making inferences about the health of ecosystems and built environments. Recent advances in scientific computing have allowed forecasting and climate models to increase their spatial and temporal resolution. Combined with observed point precipitation from monitoring stations, these models can be used to inform dynamic spatial statistical models for precipitation using methods from geostatistics and machine learning. To prove the feasibility, process, and capabilities of these statistical models, we present a case study of two statistical models of precipitation for the Amazon River basin from 2003-2010 that can infer a spatial process at a point using areal data from numerical model output. We investigate the seasonality and accumulation of rainfall, and the occurrence of no-rainfall and large-rainfall events. These parameters are used since they provide valuable information on possible model biases when using climate models for forecasts of the future process of precipitation in the Amazon basin. This information can be vital for ecosystem, agriculture, and water-resource management. We use observed precipitation data from weather stations, three areal datasets derived from observed precipitation (CFSR, CMORPH-CRT, GPCC) and three climate model precipitation datasets from CMIP5 (MIROC4h, HadGEM2-CC, and GISS-E2H) to construct the models. The observational data in the model domain is sparse, with 195 stations in the approximate 7×106 square kilometers of the Amazon basin, and therefore requires the areal data to create a more robust model. The first model uses the method of Bayesian melding to combine and make inferences from the included data sets, and the second uses a regression model with spatially and temporally-varying coefficients. The models of precipitation are fitted using the areal products and a subset of the point data, while another subset of point data is held out for verification. The statistical models are evaluated based on the predictive performance using metrics such as mean absolute errors and coverage of predictive intervals. Precipitation estimates from the climate models are also evaluated on the basis of their performance in analyzing the accumulation, seasonality, and occurrence of rainfall.

  1. The Amazon basin in transition.

    PubMed

    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

    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

  2. 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 Central

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

    2013-01-01

    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

  3. 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)

    Meador, Travis B.; Aluwihare, Lihini I.

    2014-10-01

    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 (δ13C) 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.

  4. Research on oxygen-releasing agent for prawn culture

    NASA Astrophysics Data System (ADS)

    Liu, Keqiang; Jiang, Yuxiang; Yu, Kuijie

    1991-03-01

    A solid powder oxygen-releasing agent was developed and tested in prawn culture. Dissolved oxygen (DO) is a basic necessity for aquatic life and is affected by water temperature, climate, plankton, etc. DO variation in culture ponds strongly and consequently affects prawn growth and production output. In summer, when air temperature is high, pond water is polluted (by prawn feed leftovers) and cannot be changed fully and as frequently as necessary; especially at night, when there is no sunlight for photosynthesis with oxygen as a by-product, the DO in pond water can decrease rapidly. Under the above circumstances, the prawns experience serious lack of oxygen before dawn and die in large number. To solve this problem, we developed an oxygen-releasing agent with excellent performance.

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

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

  7. Somatosensory Psychophysical Losses in Inhabitants of Riverside Communities of the Tapajós River Basin, Amazon, Brazil: Exposure to Methylmercury Is Possibly Involved

    PubMed Central

    Khoury, Eliana Dirce Torres; Souza, Givago da Silva; da Costa, Carlos Araújo; de Araújo, Amélia Ayako Kamogari; de Oliveira, Cláudia Simone Baltazar; Silveira, Luiz Carlos de Lima; Pinheiro, Maria da Conceição Nascimento

    2015-01-01

    The purpose of this work was to evaluate the somatosensory system of methylmercury-exposed inhabitants living in the communities of the Tapajós river basin by using psychophysical tests and to compare with measurements performed in inhabitants of the Tocantins river basin. We studied 108 subjects from Barreiras and São Luiz do Tapajós, two communities of the Tapajós river basin, State of Pará, Amazon, Brazil, aged 13–53 years old. Mercury analysis was performed in head hair samples weighting 0.1–0.2 g by using atomic absorption spectrometry. Three somatosensory psychophysical tests were performed: tactile sensation threshold, vibration sensation duration, and two-point discrimination. Semmes-Weinstein 20 monofilaments with different diameters were used to test the tactile sensation in the lower lip, right and left breasts, right and left index fingers, and right and left hallux. The threshold was the thinner monofilament perceived by the subject. Vibration sensation was investigated using a 128 Hz diapason applied to the sternum, right and left radial sides of the wrist, and right and left outer malleoli. Two trials were performed at each place. A stopwatch recorded the vibration sensation duration. The two-point discrimination test was performed using a two-point discriminator. Head hair mercury concentration was significantly higher in mercury-exposed inhabitants of Tapajós than in non-exposed inhabitants of Tocantins (p < 0.01). When all subjects were divided in two groups independently of age—mercury-exposed and non-exposed—the following results were found: tactile sensation thresholds in mercury-exposed subjects were higher than in non-exposed subjects at all body parts, except at the left chest; vibration sensation durations were shorter in mercury-exposed than in non-exposed subjects, at all locations except in the upper sternum; two-point discrimination thresholds were higher in mercury-exposed than in non-exposed subjects at all body parts. There was a weak linear correlation between tactile sensation threshold and mercury concentration in the head hair samples. No correlation was found for the other two measurements. Mercury-exposed subjects had impaired somatosensory function compared with non-exposed control subjects. Long-term mercury exposure of riverside communities in the Tapajós river basin is a possible but not a definitely proven cause for psychophysical somatosensory losses observed in their population. Additionally, the relatively simple psychophysical measures used in this work should be followed by more rigorous measures of the same population. PMID:26658153

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

    PubMed

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

    2013-11-01

    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

  9. Geothermal aquaculture: a guide to freshwater prawn culture

    SciTech Connect

    Hayes, A.; Johnson, W.C.

    1980-05-01

    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)

  10. The microbiology of cooked prawns and shrimps on retail sale.

    PubMed Central

    Greenwood, M. H.; Coetzee, E. F.; Ford, B. M.; Gill, P.; Hooper, W. L.; Matthews, S. C.; Patrick, S.

    1985-01-01

    In an inter-laboratory survey, 148 samples of cooked prawns and shrimps were obtained at the point of sale to the consumer. Salmonellae and Vibrio parahaemolyticus were not detected. Yersinia enterocolitica was isolated from three samples. Results for total viable count and presence of Escherichia coli and Staphylococcus aureus complied well with available guidelines for imported cooked prawns, suggesting that the risk of food poisoning from retail samples of these foods in the South of England is minimal. PMID:3891850

  11. Hydrochemical state of intermediate culture pond for Chinese prawn juveniles

    NASA Astrophysics Data System (ADS)

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

    1996-03-01

    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%.

  12. Effect of seasonal flooding cycle on litterfall production in alluvial rainforest on the middle Xingu River (Amazon basin, Brazil).

    PubMed

    Camargo, M; Giarrizzo, T; Jesus, A J S

    2015-08-01

    The assumption for this study was that litterfall in floodplain environments of the middle Xingu river follows a pattern of seasonal variation. According to this view, litterfall production (total and fractions) was estimated in four alluvial rainforest sites on the middle Xingu River over an annual cycle, and examined the effect of seasonal flooding cycle. The sites included two marginal flooded forests of insular lakes (Ilha Grande and Pimentel) and two flooded forests on the banks of the Xingu itself (Boa Esperança and Arroz Cru). Total litterfall correlated with rainfall and river levels, but whereas the leaf and fruit fractions followed this general pattern, the flower fraction presented an inverse pattern, peaking in the dry season. The litterfall patterns recorded in the present study were consistent with those recorded at other Amazonian sites, and in some other tropical ecosystems. PMID:26691098

  13. Seasonal and inter-annual dynamics of suspended sediment at the mouth of the Amazon river: The role of continental and oceanic forcing, and implications for coastal geomorphology and mud bank formation

    NASA Astrophysics Data System (ADS)

    Gensac, Erwan; Martinez, Jean-Michel; Vantrepotte, Vincent; Anthony, Edward J.

    2016-04-01

    Fine-grained sediments supplied to the Ocean by the Amazon River and their transport under the influence of continental and oceanic forcing drives the geomorphic change along the 1500 km-long coast northward to the Orinoco River delta. The aim of this study is to give an encompassing view of the sediment dynamics in the shallow coastal waters from the Amazon River mouth to the Capes region (northern part of the Amapa region of Brazil and eastern part of French Guiana), where large mud banks are formed. Mud banks are the overarching features in the dynamics of the Amazon-Orinoco coast. They start migrating northward in the Capes region. Suspended Particulate Matter (SPM) concentrations were calculated from satellite products (MODIS Aqua and Terra) acquired over the period 2000-2013. The Census-X11 decomposition method used to discriminate short-term, seasonal and long-term time components of the SPM variability has rendered possible a robust analysis of the impact of continental and oceanic forcing. Continental forcing agents considered are the Amazon River water discharge, SPM concentration and sediment discharge. Oceanic forcing comprises modelled data of wind speed and direction, wave height and direction, and currents. A 150 km-long area of accretion is detected at Cabo Norte that may be linked with a reported increase in the river's sediment discharge concurrent with the satellite data study period. We also assess the rate of mud bank migration north of Cabo Norte, and highlight its variability. Although we confirm a 2 km y-1 migration rate, in agreement with other authors, we show that this velocity may be up to 5 km y-1 along the Cabo Orange region, and we highlight the effect of water discharge by major rivers debouching on this coastal mud belt in modulating such rates. Finally, we propose a refined sediment transport pattern map of the region based on our results and of previous studies in the area such as the AMASSEDS programme, and discuss the relationship between sediment transport and accumulation patterns and the coastal geomorphology of this region.

  14. The source and fate of sediment and mercury in the Tapajós River, Pará, Brazilian Amazon: Ground- and space-based evidence.

    PubMed

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

    2006-10-01

    We present results of mercury (Hg) in surface waters and soils and an analysis of satellite imagery from the Tapajós River basin, Brazilian Amazon, and the Reserva Garimpeira do Tapajós, the legal gold mining district of the basin. Hg bound to suspended sediment was roughly 600 and 200 times the concentration of dissolved Hg per litre of water, in impacted and pristine areas, respectively. Suspended sediments thus represent the major pathway of river-borne Hg. Median concentrations of Hg in suspended load from both impacted and pristine waters were 134 ppb, and 80% of samples were below 300ppb-in the range of naturally occurring surficial materials in the tropics. Regionally, riverine Hg fluxes were proportional to the concentration of total suspended solids. This shows that the dominant source of Hg is the sediment itself rather than anthropogenic mercury discharge from the small-scale mines. To independently test this conclusion, a mass balance was performed. A conservative calculation of the annual export of mercury (Hg) from the Creporí River (a minimum) was 1.6 tonnes for the year 1998-it could be significantly larger. This amount of Hg is difficult to account for by anthropogenic discharge alone, confirming that enhanced physical erosion caused by sluicing and dredging operations is the dominant source of Hg. We therefore conclude that gold mining operations are primarily responsible for elevated Hg concentrations. The dominant source of contamination is not, however, the loss of Hg in the gold amalgamation process. Rather, the disturbance and mobilization of large quantities of Hg-rich sediment and floodplain soil into the water column during mining operations is the source of contamination. These findings shift the focus of remediation and prevention efforts away from Hg control toward soil and sediment erosion control. The minimization or elimination of Hg losses in the mining process remains important for the health of local peoples and environments, but keeping basin soils and sediments in place would be a much more effective means of minimizing Hg fluxes to the region's rivers. To gain a spatial and historical perspective on the source and extent of emissions, satellite imagery was used. We were able to reconstruct historical mining activity, locate impacted areas, and estimate historical Hg fluxes with the imagery. To do so, the spectral characteristics of satellite images were calibrated to the concentration of suspended sediment in the rivers, which, in turn, is proportional to the Hg concentration. This analysis shows that mining-induced sediment plumes have been a dominant source of sediment to the Tapajós River system for decades. As well, the intensity and location of these emissions has varied through time. For example, sediment discharge from the Creporí River was greater in 1985 than in 1998; and the tributaries on the west bank of the Tapajós were actively being mined in 1985 but had been abandoned in 1998. This type of information should greatly assist in understanding original and ongoing sources of emissions, and in managing prevention and remediation efforts. PMID:16824670

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

    PubMed Central

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

    2015-01-01

    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

  16. The reactivity of plant-derived organic matter in the Amazon River and implications on aquatic carbon fluxes to the atmosphere and ocean

    NASA Astrophysics Data System (ADS)

    Ward, N. D.; Sawakuchi, H. O.; Keil, R. G.; da Silva, R.; Brito, D. C.; Cunha, A. C.; Gagne-Maynard, W.; de Matos, A.; Neu, V.; Bianchi, T. S.; Krusche, A. V.; Richey, J. E.

    2014-12-01

    The remineralization of terrestrially-derived organic carbon (OC), along with direct CO2 inputs from autochthonous plant respiration in floodplains, results in an evasive CO2 gas flux from inland waters that is an order of magnitude greater than the flux of OC to the ocean. This phenomenon is enhanced in tropical systems as a result of elevated temperatures and productivity relative to temperate and high-latitude counterparts. Likewise, this balance is suspected to be influenced by increasing global temperatures and alterations to hydrologic and land use regimes. Here, we assess the reactivity of terrestrial and aquatic plant-derived OM near the mouth of the Amazon River. The stable isotopic signature of CO2 (δ13CO2) was monitored in real-time during incubation experiments performed in a closed system gas phase equilibration chamber connected to a Picarro Cavity Ring-Down Spectrometer. Incubations were performed under natural conditions and with the injection of isotopically labeled terrestrial macromolecules (e.g. lignin) and algal fatty acids. Under natural conditions, δ13CO2 became more depleted, shifting from roughly -23‰ to -27‰ on average, suggesting that C3 terrestrial vegetation was the primary fuel for CO2 production. Upon separate injections of 13C-labeled lignin and algal fatty acids, δ13CO2 increased near instantaneously and peaked in under 12 hours. Roughly 75% of the labeled lignin was converted to CO2 at the peak in δ13CO2, whereas less than 20% of the algal fatty acids were converted to CO2 (preliminary data subject to change). The rate of labeled-OC remineralization was enhanced by the addition of a highly labile substrate (e.g. ethyl acetate). Likewise, constant measurements of O2/pCO2 along the lower river revealed anomalously high CO2 and low O2 levels near the confluence of the mainstem and large tributaries with high algal productivity. These collective results suggest that the remineralization of complex terrestrial macromolecules is a significant source of CO2 to tropical rivers, whereas algal-derived OC is primarily incorporated into the microbial loop/higher trophic levels and enhances the breakdown of more complex terrestrially-derived molecules (e.g. the "priming effect").

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

    PubMed

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

    2014-01-01

    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

  18. Toxic effects of Zn2+, Cu2+, Cd2+ and NH3 on Chinese prawn

    NASA Astrophysics Data System (ADS)

    Zang, Weiling; Xu, Xuancheng; Dai, Xilin; Zhu, Zhengguo; Xu, Guirong; Xu, Renguo

    1993-09-01

    This study deals with the toxic effects of Zn2+, Cu2+, Cd2+ and NH3 on Chinese prawn ( Penaeus orientalis). The median lethal concentrations of the toxic matters on Chinese prawn were determined. Cd2+>Cu2+>Zn2+>NH3-Nm is the toxic order of these chemicals to Chinese prawn. The toxic order of concentrated Zn2+ and Cd2+ in tissues and organs of Chinese prawn is in the order. gill>shell+appendage>viscera>muscle.

  19. 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...

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

    PubMed

    Boischio, A A; Henshel, D S

    2000-06-01

    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

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

    PubMed

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

    2013-08-01

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

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

    PubMed

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

    2009-11-01

    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

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

    PubMed

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

    2015-06-01

    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 μg·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

  4. Detection of antibacterial agents in warm water prawns.

    PubMed

    Willis, C; Booth, H; Westacott, S; Hawtin, P

    1999-09-01

    Samples of cooked and raw prawns intended for human consumption were collected by officers at Southampton Port Health Authority, and tested for the presence of antimicrobial agents. Antimicrobial activity was detected in 23 out of 98 cooked prawn samples but in none of the 20 raw samples collected. Samples that showed antimicrobial activity were analysed using high performance liquid chromatography and immunoassay, resulting in the presumptive identification of trimethoprim in 15 samples, and low levels of gentamicin in three samples. Prawns in which trimethoprim was putatively detected contained bacteria with significantly greater resistance to this antibiotic than samples in which no trimethoprim was found. This suggests that the presence of antibiotics in prawn samples may be correlated with increased resistance to these drugs in the associated microflora. There are currently no guidelines regarding acceptable levels of antibiotics in seafood products. These results indicate that the use of these drugs by prawn farmers may be widespread, and may be an issue that requires further attention in the future. PMID:10491879

  5. 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)

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

    2014-05-01

    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.

  6. Solar aquaculture: A wintering technique for parent prawns

    SciTech Connect

    Cao Jin Long

    1994-09-01

    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.

  7. Mercury levels assessment in hair of riverside inhabitants of the Tapajs River, Par State, Amazon, Brazil: fish consumption as a possible route of exposure.

    PubMed

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

    2015-04-01

    The study present evaluated the levels of mercury (Hg) and methylmercury (MeHg) in hair samples of people from Barreiras community, riverside inhabitants of the Tapajs River (Par, 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 Tapajs 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 Tapajs 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

  8. Heavy metal concentrations in the banana prawn, Penaeus merguiensis, and leader prawn, P. monodon, in the Townsville Region of Australia

    SciTech Connect

    Darmono, D.; Denton, G.R.W. )

    1990-03-01

    Trace amounts of heavy metals are normal in marine organisms and some, such as copper, iron, zinc and manganese, are essential for normal growth and development. Other metals such as cadmium and mercury have no known use in physiological processes. In the following study a baseline survey was undertaken to establish the range of metal levels in field populations of juvenile banana prawns Penaeus merguiensis and farmed stocked of juvenile leader prawns, P. monodon. Concentrations of ten trace elements (viz. Cu, Zn, Fe, Mn, Cd, Ag, Mg, Pb, Ni, Co and Hg) were determined in wild and farmed prawn stocks and a preliminary assessment of inter-element relationships within tissues was also made.

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

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  10. Salmonella and Vibrio cholerae in brackishwater cultured tropical prawns.

    PubMed

    Reilly, P J; Twiddy, D R

    1992-08-01

    The occurrence of Salmonella and Vibrio cholerae in brackishwater ponds was monitored over a 2-year period in one of the major prawn exporting countries in Southeast Asia. The principal production areas were identified and regular samples taken for Salmonella and V. cholerae analysis. Results demonstrated that brackishwater ponds and cultured prawns were inherently contaminated with both bacterial pathogens. Salmonella spp. were present in 16.0% of prawns and 22.1% of mud/water samples from ponds; and V. cholerae present in 1.5% of prawns and 3.1% of mud/water samples. Culturing by intensive methods tended to favour contamination by these pathogens, which is most likely due to the accumulation of waste and increase in the volume of sediments in ponds. Typical environmental factors such as water temperature, pH, and salinity were all favourable for growth of microorganisms. The incidence of the pathogens increased during the wet season and was marginally higher when ponds were located close to urban areas. S. weltevreden was identified as the principal serotype found in ponds, and to a lesser extent S. anatum (11%) S. wandsworth (8%) and S. potsdam (8%). The V. cholerae belonged to the non-O1 serogroup. PMID:1457289

  11. PRAWN: Mixing Sequences for Selective Heteronuclear J Cross Polarization

    NASA Astrophysics Data System (ADS)

    Chandrakumar, N.; Kimmich, R.

    1999-03-01

    In this work, we present a family of pulse sequences for selective heteronuclearJcross-polarization (JCP), which we have developed especially for indirect13C imaging usingJCP, for example in the CYCLCROP environment. The sequences are straightforward to implement and operate reliably. Results of an average Hamiltonian analysis are given for the basic sequence, which we term PRAWN (pulsed rotating frame transfer sequence with windows). It is shown experimentally that the pulse sequence, which operates efficiently with low RF duty cycles down to a few percent, has a useful tolerance range to absolute Hartmann-Hahn mismatch and generates coherence transfer spectra in close correspondence with theJCP average Hamiltonian. Computer simulation of the performance of the basic sequence on a heteronuclear spin-{1}/{2} AX system is also presented. The mismatch compensation of PRAWN may be markedly enhanced further by issuing a π pulse to each spin halfway through the basic PRAWN train and in phase quadrature to it. A simple analysis of this modified sequence, PRAWN-π, is given under conditions of mismatch and off-resonance irradiation.

  12. Volatile components associated with bacterial spoilage of tropical prawns.

    PubMed

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

    1998-06-30

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

  13. 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

    Quay, P.D.; Wilbur, D.O.; Richey, J.E.

    1995-06-01

    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.

  14. [Application of electron spin resonance spectroscopy for the detection of irradiated crustaceans (prawn, shrimp, and crabs)].

    PubMed

    Kameya, Hiromi; Takatsuki, Satoshi; Matsuda, Rieko; Tsutsumi, Tomoaki; Todoriki, Setsuko

    2014-01-01

    Prawn, shrimp and crabs sold in Japan are mostly imported from overseas. Detection of irradiated crustaceans is very important for quality assurance. In this study, we used ESR to detect radiation-induced radicals after irradiation of prawn, shrimp and crabs of major species. No radiation-induced radicals were detected in prawn (black tiger prawn) or shrimp (white leg shrimp). Radiation-induced radicals due to hydroxyapatite were detected in the claws of snow crab, red king crab, and swimming crab. Our results indicate that ESR measurement on the claw parts of these three species of crab can be used to determine their irradiation history. PMID:25743382

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

    ERIC Educational Resources Information Center

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

    2006-01-01

    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

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

    ERIC Educational Resources Information Center

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

    2006-01-01

    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…

  17. Infection with schistosome parasites in snails leads to increased predation by prawns: implications for human schistosomiasis control.

    PubMed

    Swartz, Scott J; De Leo, Giulio A; Wood, Chelsea L; Sokolow, Susanne H

    2015-12-01

    Schistosomiasis - a parasitic disease that affects over 200 million people across the globe - is primarily transmitted between human definitive hosts and snail intermediate hosts. To reduce schistosomiasis transmission, some have advocated disrupting the schistosome life cycle through biological control of snails, achieved by boosting the abundance of snails' natural predators. But little is known about the effect of parasitic infection on predator-prey interactions, especially in the case of schistosomiasis. Here, we present the results of laboratory experiments performed on Bulinus truncatus and Biomphalaria glabrata snails to investigate: (i) rates of predation on schistosome-infected versus uninfected snails by a sympatric native river prawn, Macrobrachium vollenhovenii, and (ii) differences in snail behavior (including movement, refuge-seeking and anti-predator behavior) between infected and uninfected snails. In predation trials, prawns showed a preference for consuming snails infected with schistosome larvae. In behavioral trials, infected snails moved less quickly and less often than uninfected snails, and were less likely to avoid predation by exiting the water or hiding under substrate. Although the mechanism by which the parasite alters snail behavior remains unknown, these results provide insight into the effects of parasitic infection on predator-prey dynamics and suggest that boosting natural rates of predation on snails may be a useful strategy for reducing transmission in schistosomiasis hotspots. PMID:26677260

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

    NASA Astrophysics Data System (ADS)

    Xiao, Yongshun; Liu, Ruiyu; Cui, Yuheng

    1988-12-01

    Postlarval Penaeus orientalis kishinouye were simultaneously sampled at three fixed stations near the mouth of the Dagu River estuary in northwestern Jiaozhou Bay, China, at hourly intervals over a 49-h period in mid-June, 1984. The purpose of this sampling was to investigate the prawn’s recruitment into estuaries from coastal areas. The abundance of the postlarvae varied considerably between stations and time, but they tended to concentrate at the surface. Maximum entropy spectral analysis was first applied in the study of prawn recruitment and it revealed that variations in abundance involved a pronounced 12.4 hr cycle. It was concluded that natural tidal cycles had a strong influence on the changes of postlarval abundance, in contrast with the minor effects of diet and other environmental cycles. A tidally varying cross-river gradient of postlarval density was found. During flood tides the postlarvae were more abundant in the axis of the channel than over the banks. The opposite held true during ebb tides. Mechanisms of the postlarval recruitment are discussed in terms of alternating movements of the postlarvae between the banks and the channels in response to tidal cycles.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    PubMed

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

    2014-01-01

    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

  1. Fortified versus incurred residues: extraction of furazolidinone metabolite from prawn.

    PubMed

    Johnston, Lesley; Croft, Meg; Murby, John

    2015-06-01

    Most methods reported in the literature for determination of nitrofuran metabolites use the same extraction and derivatisation conditions to hydrolyse and extract the protein-bound residues from animal tissue. While undertaking certification of reference materials for nitrofuran metabolites in freeze-dried prawn, it was found that these conditions are satisfactory for recovery of spiked residues; however, extraction efficiencies of incurred furazolidinone could be substantially increased by further optimisation of the extraction conditions. The availability of a suitable certified reference material allows laboratories to ensure that their method is optimised for incurred residues. PMID:25862475

  2. Geochemistry of Amazon Basin supported by the ADCP measurements

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    PubMed

    Henares, M N P; Camargo, A F M

    2014-11-01

    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

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

    PubMed

    Kemenes, A; Forsberg, B R

    2014-08-01

    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

  5. The effect of copper nanoparticles supplementation on freshwater prawn Macrobrachium rosenbergii post larvae.

    PubMed

    Muralisankar, Thirunavukkarasu; Saravana Bhavan, Periyakali; Radhakrishnan, Subramanian; Seenivasan, Chandirasekar; Srinivasan, Veeran

    2016-03-01

    The present study was performed to assess the effects of dietary supplementation of copper nanoparticles (Cu-NPs) on growth, biochemical constituents, digestive enzyme activities, antioxidant, metabolic enzyme levels, and non specific immune response of the freshwater prawn, Macrobrachium rosenbergii post larvae (PL). The Cu-NPs (200nm) were synthesized by facile and environmental friendly hydrothermal method. Cu-NPs were supplemented at 0, 10, 20, 40, 60, and 80mgkg(-1) with the basal diets. These Cu-NPs supplemented diets were fed to M. rosenbergii PL for 90 days. Results showed significant (P<0.05) improvements were observed in survival, growth, digestive enzyme activities, concentrations of biochemical constituents and total and differential haemocytes count of prawns fed with 20mgCu-NPskg(-1) supplemented feed. Prawns fed with 40-80mgCu-NPskg(-1) supplemented feed showed negative performance. Activity of antioxidants and metabolic enzymes in the muscle and hepatopancreas of prawns showed no significant alterations (P>0.05) prawns fed with up to 20mgCu-NPskg(-1) supplemented feeds. Whereas, prawns fed with 40-80mgCu-NPskg(-1) supplemented feed showed significant (P<0.05) elevations in antioxidant and metabolic enzymes activities. Hence, 40-80mgCu-NPskg(-1) diets may have toxic effect to M. rosenbergii. Hence, present study suggests that 20mgCu-NPskg(-1) can be supplemented for regulating better survival, growth and immune response of M. rosenbergii PL. PMID:26854244

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

    PubMed

    Finer, Matt; Jenkins, Clinton N

    2012-01-01

    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

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

    PubMed Central

    Finer, Matt; Jenkins, Clinton N.

    2012-01-01

    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

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

    PubMed

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

    2006-05-01

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

  9. The riverine silicon isotope composition of the Amazon Basin

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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 δ30Si 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 (δ30Si = +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.

  10. In-Depth Tanscriptomic Analysis on Giant Freshwater Prawns

    PubMed Central

    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

    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

  11. Recent and subrecent changes in the dispersal of amazon mud

    NASA Astrophysics Data System (ADS)

    Eisma, D.; Augustinus, P. G. E. F.; Alexander, C.

    The dispersal of Amazon mud reaches from the mouth of the Amazon river to the Orinoco delta and to the eastern Caribbean, a distance of more than 1500 km. The present dispersal system has been in existence for at least 10 3 years, but the deposition of mud from this system has not been constant during that period. A change from net erosion to net deposition along the Suriname coast between 1947 and 1981 was found to coincide with a shift of the trade winds from a dominantly NE to a more ENE direction from 1959 onward, accompanied by an increase in mean wind velocity. The change to net-deposition can be explained by enhanced longshore transport of suspended matter with simulataneous reduction of erosion by reduction of the onshore wave energy component. The sequence of a recent mud deposit 100-200 years old off the Amazon river mouth separated by a period of non-deposition from an older mud deposit less than 1000 years old, agrees well with indications for a wetter period in the Amazon basin and in the Colombian Andes since about 200 years BP and a wetter period between 500 and 900 y BP. This implies that during wetter periods the suspended-sediment supply from the Amazon (and the Orinoco) was (is) higher.

  12. The Amazon and climate

    NASA Technical Reports Server (NTRS)

    Nobre, C. A.

    1984-01-01

    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.

  13. Effect of waterfalls and the flood pulse on the structure of fish assemblages of the middle Xingu River in the eastern Amazon basin.

    PubMed

    Barbosa, T A P; Benone, N L; Begot, T O R; Gonçalves, A; Sousa, L; Giarrizzo, T; Juen, L; Montag, L F A

    2015-08-01

    The structure of fish assemblages in Neotropical rivers is influenced by a series of environmental, spatial and/or temporal factors, given that different species will occupy the habitats that present the most favourable conditions to their survival. The present study aims to identify the principal factors responsible for the structuring of the fish assemblages found in the middle Xingu River, examining the influence of environmental, spatial, and temporal factors, in addition to the presence of natural barriers (waterfalls). For this, data were collected every three months between July 2012 and April 2013, using gillnets of different sizes and meshes. In addition to biotic data, 17 environmental variables were measured. A total of 8,485 fish specimens were collected during the study, representing 188 species. Total dissolved solids, conductivity, total suspended matter, and dissolved oxygen concentrations were the variables that had the greatest influence on the characteristics of the fish fauna of the middle Xingu. Only the barriers and hydrological periods played a significant deterministic role, resulting in both longitudinal and lateral gradients. This emphasizes the role of the connectivity of the different habitats found within the study area in the structuring of its fish assemblages. PMID:26691079

  14. 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, So Francisco and the Paran River basins

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    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 (4-6C) 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 So Francisco Basin, making these regions susceptible to drier conditions and droughts in the future.

  15. Amazon Observation Platform

    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...

  16. 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...

  17. Acute effects of deltamethrin on swimming velocity and biomarkers of the common prawn Palaemon serratus.

    PubMed

    Oliveira, Cristiana; Almeida, Joana; Guilhermino, Lúcia; Soares, Amadeu M V M; Gravato, Carlos

    2012-11-15

    The main purpose of the present study was to investigate the effects of deltamethrin on biomarkers and behavior of Palaemon serratus (common prawn), since this attempt to link different levels of biological organization will allow determining which biomarkers might be ecologically relevant and will be useful to complement the information about the effects of pesticides by using behavioral parameters. Therefore, parameters of liver antioxidant status, energy metabolism and neurotransmission were determined in different tissues of the common prawn and used to assess the effects at sub-individual level, whereas swimming velocity was used to assess the effects at the individual level. It was also investigated if the swimming velocity can be used as an endpoint in ecotoxicology bioassays and if it can be as sensitive as biomarker endpoints. Swimming velocity was significantly reduced in prawns exposed to deltamethrin, showing a lowest observed effect (LOEC) of 0.6 ng L(-1). Eye acetylcholinesterase (AChE) activity was significantly increased in prawns exposed to 0.6, 1.2 and 2.4 ng L(-1) deltamethrin, whereas muscle cholinesterase (ChE) activity was significantly increased in prawns exposed to 19 and 39 ng L(-1). On the other hand, lactate dehydrogenase (LDH) activity was significantly increased in muscle of prawns exposed to 0.6, 1.2, 2.4, 4.9 ng L(-1) deltamethrin, showing that organisms were requiring additional energy, but probably using it for detoxification processes rather than locomotion, since swimming velocity was inhibited. Glutathione S-transferase (GST) activity was significantly increased in the digestive gland of common prawn exposed to 19 and 39 ng L(-1) deltamethrin. Catalase (CAT) activity was significantly increased in digestive gland of prawn exposed to 19 ng L(-1) deltamethrin. However, CAT activity decreased in digestive gland of prawn exposed to 39 ng L(-1), suggesting an antioxidant defense system failure concomitant with high levels of lipid peroxidation. Thus, global results showed that decreased swimming velocity was not associated with cholinesterase inhibition. In fact, the impairment of swimming velocity may be due to allocation of energy for detoxification and antioxidant protection instead of swimming activity. The present study showed that swimming velocity could be used as an ecologically relevant tool and a sensitive endpoint to assess and complement the study of pesticide effects on marine organisms. PMID:22967730

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

    PubMed

    Ahmed, Nesar; Troell, Max

    2010-02-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed Central

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

    2014-01-01

    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

  1. Analysis of Hydrologic Droughts in Amazon Watersheds

    NASA Astrophysics Data System (ADS)

    Lopes, A. V.; Thompson, S. E.; Dracup, J. A.

    2014-12-01

    The Amazon river basin is vulnerable to severe seasonal droughts that cause significant ecological and economic impacts, as happened in 2005 and 2010. Although drought analysis tools have been largely developed and applied in arid and semi-arid environments, challenges remain in characterizing droughts and related hydrologic mechanisms in tropical regions with large storage capacity and densely forested, such as in the Amazon. In this study, we analyze the hydrologic behavior of the unsaturated zone of typical Amazon watersheds during droughts using a coupled soil-vegetation model. That model uses a one-dimensional, multiple wetting front representation of a 12 meters-deep unsaturated zone, and was calibrated with existing field data such as soil moisture and evaporation from flux towers. That model was forced with rainfall and potential evaporation synthetic time series generated with a stochastic model developed to represent different climate patterns. Such stochastic simulation of the soil-vegetation system produces the probability distributions of water balance components and allows for the analysis of the sensitivity of the hydrologic fluxes to varying rainfall properties. The results show a contrasting behavior of hydrologic components: as rainfall is reduced, interception decreases but transpiration increases due to less cloudiness. The increase in transpiration seems to be supported by larger changes in soil water storages. Moreover, periods of reduced rainfall are also followed by enhanced deep percolation underneath the deep root zones. Thus, dry periods are associated with higher rates of soil water loss to transpiration and deep percolation. Those results advance the existing knowledge of the response of tropical, forested environments to droughts and can potentially contribute to better prediction of impacts of hydrologic droughts in the Amazon.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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/Solimes 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.

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

    SciTech Connect

    Vijayram, K.; Geraldine, P.

    1996-02-01

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

  5. 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

    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

    We investigated modulation by ATP, Mg²⁺, Na⁺, K⁺ and NH₄⁺ 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⁺ (K₀.₅ = 0.91 ± 0.04 mmol L⁻¹) in decapodid III than in other stages; NH₄⁺ had no modulatory effect. The affinity for Na⁺ (K₀.₅ = 13.2 ± 0.6 mmol L⁻¹) of zoea I (Na⁺,K⁺)-ATPase was fourfold less than other stages. Modulation by Na⁺, Mg²⁺ and NH₄⁺ 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 NH₄⁺-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

  6. The Amazon and climate

    NASA Technical Reports Server (NTRS)

    Nobre, C. A.

    1984-01-01

    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.

  7. Qualitative mathematical models to support ecosystem-based management of Australia's Northern Prawn Fishery.

    PubMed

    Dambacher, Jeffrey M; Rothlisberg, Peter C; Loneragan, Neil R

    2015-01-01

    A major decline in the catch of the banana prawn [shrimp], Penaeus (Fenneropenaeus) merguiensis, occurred over a six-year period in the Weipa region of the northeastern Gulf of Carpentaria, Australia. Three main hypotheses have been developed to explain this decline: (1) prawn recruitment collapsed due to overfishing; (2) recruitment collapsed due to a change in the prawn's environment; and (3) adult banana prawns were still present, but fishers could no longer effectively find or catch them. Qualitative mathematical models were used to link population biology, environmental factors, and fishery dynamics to evaluate the alternative hypotheses. This modeling approach provides the means to rapidly integrate knowledge across disciplines and consider alternative hypotheses about how the structure and function of an ecosystem affects its dynamics. Alternative models were constructed to address the different hypotheses and also to encompass a diversity of opinion about the underlying dynamics of the system. Key findings from these analyses are that: instability in the system can arise when discarded fishery bycatch supports relatively high predation pressure; system stability can be enhanced by management of fishing effort or stock catchability; catch per unit effort is not necessarily a reliable indicator of stock abundance; a change in early-season rainfall should affect all stages in the banana prawn's life cycle; and a reduced catch in the Weipa region can create and reinforce a shift in fishing effort away from Weipa. Results from the models informed an approach to test the hypotheses (i.e., an experimental fishing program), and promoted understanding of the system among researchers, management agencies, and industry. The analytical tools developed in this work to address stages of a prawn life cycle and fishery dynamics are generally applicable to any exploited natural. resource. PMID:26255373

  8. Characterization of chromatophorotropic neuropeptides from the kuruma prawn Penaeus japonicus.

    PubMed

    Yang, W J; Aida, K; Nagasawa, H

    1999-06-01

    Three chromatophorotropic neuropeptide hormones were purified from an aqueous extract of the sinus glands of the kuruma prawn Penaeus japonicus by two steps of reverse-phase HPLC and their amino acid sequences determined. One of them was found to show pigment concentrating activity and to have an amino acid sequence identical with that of the known red pigment concentrating hormone (RPCH), and therefore it was named Pej-RPCH. The other two peptides showed pigment dispersing hormone (PDH) activity and were named Pej-PDH-I and -II. They both consisted of 18 amino acid residues with a free amino-terminus and an amidated carboxyl-terminus, the sequences of Pej-PDH-I and -II being NSELINSLLGIPKVMTDAamide and NSELINSLLGLPKFMIDAamide, respectively. Three amino acid residues at positions 11, 14, and 16 differed between the two PDHs. Pej-PDH-II was about 5-, 7-, and 10-fold more potent than Pej-PDH-I for erythrophores, xanthophores, and melanophores, respectively. The major reason for the difference in potency between the two PDHs was attributed to differences in residues at position 16. In addition, they were found to be produced by a single individual. The order of sensitivity of the four types of chromatophores to Pej-RPCH and both PDHs was found to be erythrophores = xanthophores > melanophores > leukophores. PMID:10336829

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

    NASA Astrophysics Data System (ADS)

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

    1996-12-01

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

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

    SciTech Connect

    McKee, B.A.; DeMaster, D.J.; Nittrouer, C.A. )

    1987-10-01

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

  11. Molecular Characterisation of Colour Formation in the Prawn Fenneropenaeus merguiensis

    PubMed Central

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

    2013-01-01

    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

  12. The changing Amazon forest.

    PubMed

    Phillips, Oliver L; Lewis, Simon L; Baker, Timothy R; Chao, Kuo-Jung; Higuchi, Niro

    2008-05-27

    Long-term monitoring of distributed, multiple plots is the key to quantify macroecological patterns and changes. Here we examine the evidence for concerted changes in the structure, dynamics and composition of old-growth Amazonian forests in the late twentieth century. In the 1980s and 1990s, mature forests gained biomass and underwent accelerated growth and dynamics, all consistent with a widespread, long-acting stimulation of growth. Because growth on average exceeded mortality, intact Amazonian forests have been a carbon sink. In the late twentieth century, biomass of trees of more than 10cm diameter increased by 0.62+/-0.23tCha-1yr-1 averaged across the basin. This implies a carbon sink in Neotropical old-growth forest of at least 0.49+/-0.18PgCyr-1. If other biomass and necromass components are also increased proportionally, then the old-growth forest sink here has been 0.79+/-0.29PgCyr-1, even before allowing for any gains in soil carbon stocks. This is approximately equal to the carbon emissions to the atmosphere by Amazon deforestation. There is also evidence for recent changes in Amazon biodiversity. In the future, the growth response of remaining old-growth mature Amazon forests will saturate, and these ecosystems may switch from sink to source driven by higher respiration (temperature), higher mortality (as outputs equilibrate to the growth inputs and periodic drought) or compositional change (disturbances). Any switch from carbon sink to source would have profound implications for global climate, biodiversity and human welfare, while the documented acceleration of tree growth and mortality may already be affecting the interactions among millions of species. PMID:18267900

  13. Methane emissions to the troposphere from the Amazon floodplain

    NASA Technical Reports Server (NTRS)

    Devol, Allen H.; Richey, Jeffrey E.; Clark, Wayne A.; King, Stagg L.; Martinelli, Luiz A.

    1988-01-01

    The magnitudes of CH4 emissions to the troposphere from the Amazon River floodplain and the mechanism of these emissions were investigated using the data of 94 individual flux measurements made along a 1700-km stretch of the river during July/August 1985. The overall average rate of CH4 emission from wetlands was found to be 390 mg CH4/sq m per day, with the highest emissions (590 mg CH4/sq m per day) attributed to the water surfaces covered by aquatic macrophytes. Ebullition was the dominant mechanism of emission, accounting for 85 percent of the total. Surface-water CH4 concentrations were highly supersaturated, averaging 6.4 micromolar. The annual emission of CH4 from the Amazon Basin to the troposphere, estimated from the area and the known emission rate, is about 10 CH4 Tg/yr, indicating the importance of the area in the global atmospheric CH4 cycle.

  14. A Simple "in Vitro" Culture of Freshwater Prawn Embryos for Laboratory Investigations

    ERIC Educational Resources Information Center

    Porntrai, Supaporn; Damrongphol, Praneet

    2008-01-01

    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

  15. Cypermethrin toxicity to aquatic life: bioassays for the freshwater prawn Palaemonetes argentinus.

    PubMed

    Collins, P; Cappello, S

    2006-07-01

    Cypermethrin (CY) effects were evaluated in freshwater prawn Palaemonetes argentinus, a common member of the aquatic fauna in the vegetated littoral of lotic and lentic environment of La Plata basin. LC50 was calculated, and oxygen uptakes together with ammonia-N excretion were related to biocide concentrations. Behavioral and growth changes were analyzed, and a unique application of CY was evaluated in P. argentinus micropopulations. LC50 and their 95% confidence limit were 0.0031 microg CY L(-1) (0.0023-0.0039) for 24 h and 0.0020 microg CY L(-1) (0.0014-0.0027) for 96 h. Oxygen uptake and ammonia-N excretion increased in the prawns kept in CY solutions. The behavioral effect was hyperactivity. Although prawns in biocide groups have null or negative growth, the intermolt period was 246% larger than in the control group. Moreover, the mortality in the second cycle was 100%. A unique application of pyrethoid provoked high mortality after 50 days. The low concentrations of this biocide affected the survival and altered the prawn metabolic activity, behavioral and ecdysis cycle. These results suggest that juveniles of P. argentinus are much more sensitive to CY pollution than other crustaceans, fish, and tadpoles. PMID:16418889

  16. Desperate Prawns: Drivers of Behavioural Innovation Vary across Social Contexts in Rock Pool Crustaceans.

    PubMed

    Duffield, Callum; Wilson, Alastair J; Thornton, Alex

    2015-01-01

    Innovative behaviour may allow animals to cope with changes in their environment. Innovative propensities are known to vary widely both between and within species, and a growing body of research has begun to examine the factors that drive individuals to innovate. Evidence suggests that individuals are commonly driven to innovate by necessity; for instance by hunger or because they are physically unable to outcompete others for access to resources. However, it is not known whether the factors that drive individuals to innovate are stable across contexts. We examined contextual variation in the drivers of innovation in rock pool prawns (Palaemon spp), invertebrates that face widely fluctuating environments and may, through the actions of tides and waves, find themselves isolated or in groups. Using two novel foraging tasks, we examined the effects of body size and hunger in prawns tested in solitary and group contexts. When tested alone, small prawns were significantly more likely to succeed in a spatial task, and faster to reach the food in a manipulation task, while hunger state had no effect. In contrast, size had no effect when prawns were tested in groups, but food-deprived individuals were disproportionately likely to innovate in both tasks. We suggest that contextual variation in the drivers of innovation is likely to be common in animals living in variable environments, and may best be understood by considering variation in the perception of relative risks and rewards under different conditions. PMID:26488728

  17. Desperate Prawns: Drivers of Behavioural Innovation Vary across Social Contexts in Rock Pool Crustaceans

    PubMed Central

    Duffield, Callum; Wilson, Alastair J.; Thornton, Alex

    2015-01-01

    Innovative behaviour may allow animals to cope with changes in their environment. Innovative propensities are known to vary widely both between and within species, and a growing body of research has begun to examine the factors that drive individuals to innovate. Evidence suggests that individuals are commonly driven to innovate by necessity; for instance by hunger or because they are physically unable to outcompete others for access to resources. However, it is not known whether the factors that drive individuals to innovate are stable across contexts. We examined contextual variation in the drivers of innovation in rock pool prawns (Palaemon spp), invertebrates that face widely fluctuating environments and may, through the actions of tides and waves, find themselves isolated or in groups. Using two novel foraging tasks, we examined the effects of body size and hunger in prawns tested in solitary and group contexts. When tested alone, small prawns were significantly more likely to succeed in a spatial task, and faster to reach the food in a manipulation task, while hunger state had no effect. In contrast, size had no effect when prawns were tested in groups, but food-deprived individuals were disproportionately likely to innovate in both tasks. We suggest that contextual variation in the drivers of innovation is likely to be common in animals living in variable environments, and may best be understood by considering variation in the perception of relative risks and rewards under different conditions. PMID:26488728

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

    PubMed

    Agundis, C; Pereyra, A; Zenteno, R; Brassart, C; Sierra, C; Vazquez, L; Zenteno, E

    2000-10-01

    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 kappa 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 the lectin concentration in animals at different maturation stages. The highest concentration of lectin was identified in the hemolymph from post-larval prawns and the lowest in molt stage adult animals. The hemagglutination activity of the lectin was four-fold higher in adult than in juvenile specimens, although in all cases N-acetylated sugar residues, such as N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and N-acetyl-D-neuraminic acid were inhibitors of the lectin activity, suggesting that lectin plays a role in the transport of N-acetylated sugar in juvenile prawns. Our results indicate that lectin concentration and hemagglutinating activity could be influenced by developmental conditions of the freshwater prawn. PMID:11079370

  19. A Simple "in Vitro" Culture of Freshwater Prawn Embryos for Laboratory Investigations

    ERIC Educational Resources Information Center

    Porntrai, Supaporn; Damrongphol, Praneet

    2008-01-01

    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…

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  1. 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...

  2. Current Characterization at the Amazon estuary

    NASA Astrophysics Data System (ADS)

    Bezerra, M. O.

    2009-04-01

    At the estuary there are several mechanisms that cause turbulence: influence of solid contours (estuary bottom and shores), speed vertical shearing (fluid inside), wind shearing stress (free surface) and surface and internal gravity waves. Turbulence intensity controls vertical distribution of estuary water mass property concentration. As flow into the estuary takes place during the transition or turbulent regimen, produced by small space and time scale movements, entrainment, turbulent scattering and advection are the processes responsible for fresh water mixing up with the sea and for local salinity variation, as well as for concentration of natural properties and man-made ones. According to this focus, we shall describe general circulation, conveyance and mixing characteristics of the Amazon low estuary waters. Amazon estuary shows unusual characteristics: it is of vast length and enormous outflow. It is extremely wide - 150 Km - and its discharge into the Atlantic amounts to 180,000 m3s-1 (Otman, 1968, Figueiredo et al, 1991), which means 18% of all water discharged by rivers into oceans; this is the largest punctual source of fresh water for oceans (Milliman and Meade, 1983). Maximum outflow is 2.5 x 105 m3s-1, and it happens at the end of May. Minimum outflow is 1.2 x 105 m3 s-1, and it takes place in November. At Amazon River, the Mixing Zone occurs where the Coastal Zone usually is. The reason for that is the extension of fresh water plume moves Northeast for over 1000 Km (Gibbs, 1970; Muller-Karger et al 1988). This is the most extensive estuarine plume ever found in the ocean. During low fluvial discharge (June-November) plume reaches 300 Km; however, on high discharge (November-May) plume reaches 500 Km. Plume already is 3 to 10 m thick and 80 to 300 Km wide (Lentz and Limeburner, 1995). From June to January plume moves towards Africa, from whence 70% of it goes east carried by North Brazil Current retroflection and 30% goes towards the Caribbean. From February to May, the plume goes northwest towards the Caribbean. As to classification according to salinity stratification, at the quadrature the Amazon estuary is considered as "Saline Wedge" type (highly stratified estuary), salinity at 120 Km way from river moth standing out, whereas at sysygy it can be classified as well mixed (Limeburner et al. 1991e 1992; Patchineelam, 2004). Fresh water is everywhere in the river area, salty or mixed water is located in the ocean. In this estuary 90 Km away from the mouth surface water salinity is less than 0.05 and bottom salinity at 14 m deep is about 19 at high water on quadrature at the end of the rainy season. This behavior produces marked difference in the vertical salinity profile, showing the current is moving in the opposite direction (river fresh water and salty water brought by the tide). In this scenario, speed shearing at the interface produces interfacial friction stress that, from the entrainment process carries portions of water from the sea to the upper part. Usually, therefore, in "saline wedge" (highly stratified estuary) type estuaries, when river discharge is more intensive than the tide wave, entrainment is the predominant mechanism; and the greater tide amplitude is, the greater will its influence be to produce turbulent scattering and mixing be. Probably, at Amazon estuary quadrature entrainment processes are predominant and are the ones responsible for increased salinity in surface layer, whereas turbulence scattering mixing is secondary to it. "Saline wedge" (highly stratified estuary) type estuaries are typical of large fluvial discharge and microtide regions. But although the Amazon estuary is a macrotide region, this stratification is due to the river's exceptional discharge. Due to the remarkable river plume discharge on the platform, the tide - a dominant in macrotide region estuarine circulation - now has a secondary role, albeit not a negligible one, with quadrature amplitudes varying from 2 m to 90 Km from the mouth. It is important to point out that tide-induced mixing processes determine saline front position and structure. The circulation pattern is bidirectional: at the surface layer near river mouth, medium current flows perpendicular to isobates towards the sea, turning north until it starts to flow parallel to the continent. At the lower layer near river mouth, current flows towards the continent. At the upper layer one finds more intensive tidal current (Gibbs, 1982). Flow is weak at the bottom, showing shoreward movement under the plume that moves towards the platform. Great speed shearing is compensated by high salinity stratification at the middle of the water column and by the high concentration of sediments (fluid mud) near ocean bed (Geyer e Kineke, 1995). As for the behavior of tide-produced currents, the main tide forcing mechanism is semidiurnal (a 12.4-hour period), M2 component predominating, which in its turn is influenced by Amazon Continental Platform morphology, which breaks at the 100 m isobate. This Platform width varies significantly along the coast from 125 km to 325 km, which causes tide semidiurnal components to be enlarged at some points. North Cabo Norte, platform extension is less than at the mouth; thus, M2 travels as a stationary wave due to the near-resonant character present in coastal embayments between Cabo Norte and Cabo Cassiporé. Near the mouth M2 travels as a progressive wave due to its convergent character, whose amplitude decreases and phase grows upstream. (Beardsley et al). Tide amplitude at the coast is usually about 5 m; however, it is possible to find tide channels of up to 14 m (Vinzon, S. spoken lecture). Tide wave propagation along the channel makes the wave to be laterally compressed by river shores; however, friction exceeds convergence and causes tide height to decrease along the channel, it then being classified as a hyposynchronous estuary. At maximum outflow dynamic tide travels to the neighborhood of Gurupa Island and, at minimum outflow, dynamic tide travels to Óbidos, 840 Km upstream the river mouth (Ferraz 1975; Vinzon el al, 2007). Tide current speed component condemned axles show up in the river channel and up to about 70 Km from the mouth, that is, at the Platform, having an alternative and axial character and ebb and flood, and at more than 90 Km from the mouth tide ellipse axles tend to a rotating patter, always keeping, however, a greater axle aligned to channel configuration (Gallo et al, 2007 and Pontes, 2007). Tide speed components show quite an energetic behavior, being able to reach speeds over 2 m/s. Tide currents - usually perpendicular to the coast - vary from 200 cm/s at high tides to 80 cm/s at ebb tide in mouth neighborhood. Once tides are removed, residual currents show strong shearing, with surface speeds over 100 cm/s (Geyer and Kineke, 1995). Tide shows asymmetry, taking 4-5 hours to flood and 8-9 hours to ebb. If time intervals between ebb and flood differ, it follows from the volume conservation principle that during the shorter event - such as at Amazon estuary flood tide - speed shall be greater; as a consequence, suspended sediment transportation shall be greater during flood in comparison to ebb, assuming adequate sediment/water supply at both events. This is not to say, however, that at Amazon estuary speed shall be greater during ebb, for the large river outflow is added to ebb currents. The Amazon estuary is a peculiar case: albeit flood time is less than ebb one, the estuary is dominated by ebb tide, becoming a sediment exporter (Vinzón, et al 2007). The Amazon River discharges 3 million tons a day of sediments into the Amazon Continental Platform (Nittrouer et al 1986). These sediments are deposited NW of the outfall; there then happens a concentration rate of sediments in layers ("fluid mud") about 4 m thick in contact with sea bed (Geuer and Kineke, 1995). Fluid mud concentration is 10g/l of sediment.

  3. The fish and prawn communities of a Malaysian coastal mangrove system, with comparisons to adjacent mud flats and inshore waters

    NASA Astrophysics Data System (ADS)

    Chong, V. C.; Sasekumar, A.; Leh, M. U. C.; D'Cruz, R.

    1990-11-01

    The fish and prawn communities of four coastal habitats in Selangor, Malaysia: (1) coastal mangrove swamps; (2) mud flats, including subtidal regions; (3) near inshore waters; and (4) far inshore waters, were examined with respect to species composition, abundance, diversity, similarity and sexual maturity. The number of fish species sampled for these habitats were 119, 70, 58 and 92 species respectively. For prawns, the number of species were 9, 16, 8 and 14 respectively. The mangrove community comprised 63-99% and 100% juvenile fish and prawn respectively. Despite a high species richness, it was low in fish species diversity due to the dominance (70%) of six species of fish of low economic value. In contrast, the prawn community was poor in species, and was dominated by three Penaeus spp. of high economic value. The intertidal mudflat community is largely transient and comprised mainly of species from both the mangrove and subtidal habitats. Fifty-six per cent of the fish population and 62·6% of the prawn population were juveniles. Many of the inshore fish and prawn species were also common species found in mangrove and mudflat habitats. Similarity coefficients indicate that the inshore fish and prawn communities are more similar to those of mud flats than mangroves. However, maturity studies indicate that only five species of fish are true migrants, that the majority of the fish species (juveniles and adults) are ubiquitous with a distribution that extends several nautical miles offshore. Results of this study indicate that tropical coastal mangroves function more importantly as feeding grounds than as nursery grounds for juveniles of commercially important fish species. Mangroves and mud flats are utilized during flood tides by many periodic foragers from the inshore waters. However, this study confirms that coastal mangroves and mud flats are important nursery areas for commercially important prawn species.

  4. Copepods and fishes in the Brazilian Amazon

    NASA Astrophysics Data System (ADS)

    Thatcher, Vernon E.

    1998-06-01

    The Amazon basin comprises the largest river ecosystem in the world (7 million km 2) with annual high and low water peaks and a constant temperature near 29°C. Some 2000 fish species and 40 species of free-living copepods are known to occur in Amazonia. The free-living forms serve as food for most larval fishes and some adults, but they also transmit several parasites including representatives of the nematode family Camallanidae. About three dozen species of parasitic copepods have been described from the Brazilian Amazon. Females of Amazonian parasitic copepods are found on skin, gill filaments, gill rakers or within the nasal fossae. Parasitic copepods are found on fishes that are from a few millimeters long up to those over 2 m in length and they are usually quite host specific. All have body pigmentation in different patterns and colors (frequently blues, such as cerulean, cobalt, spectrum, smalt or campanula). It is suggested that the coloration serves to attract specific host fish. Copepods have evolved adaptations for attachment and feeding, especially in the second antennae and endopods. Examples of progenesis, phoresis and commensalism are shown. Some species produce pathology such as a tourniquet effect, hyperplasia, blood loss and anemia, and can kill fishes by limiting their respiration.

  5. How Pecten Brazil drilled the Amazon basin

    SciTech Connect

    Bleakley, W.B.

    1983-09-01

    Pecten Brazil overcame numerous obstacles to drill two exploratory wells in the Amazon Basin last year. These included: The threat of low water in normally navigable rivers. Dense jungle growth at both locations. Lack of suitable roads for heavy hauling. Inconvenient distances from supply points. An unusual basalt formation responsible for unique drilling problems. Hundreds of helicopter lifts to move drilling rigs, supplies, and personnel. Pecten contracted with Petrobras, the Brazilian national oil company, to evaluate three blocks in the Amazon jungle, each about 68 miles (110 km) on a side, through seismic study and ultimate drilling. Planning for the drilling phase got started on March 17, 1981 with December 1 targeted as spud date for the first well. Actual spud date was November 25, 5 days ahead of schedule, in spite of all obstacles. Pecten has a mid-Amazonas block now under seismic investigation for possible exploratory drilling. Logistics problems in this one provide new difficulties, as the area is extremely wet. Most work is carried on by boat. The company is also looking offshore Bahia, testing the possible extension of the Renconcavo basin. Two wells have already provided good shows of a high pour point oil, with flow rates from 400 to 1,000 b/d. Another area of interest to Pecten is offshore Rio Grande do Norte.

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

    PubMed Central

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

    2011-01-01

    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

  7. Reexamining the late Cenozoic geologic evolution of the Amazon basin

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  8. Andean Altiplano, Amazon Basin burning

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view is centered over Lake Poopo, Bolivia, in the central Andean Altiplano, (20.0S, 65.0W) with a view looking northeast into the lower elevations of Bolivia and Brazil. Extensive dry seasonal burning in the Amazon Basin produces a thick haze which is trapped in the lower atmosphere by a stable air layer. The clarity difference in the scene is caused by the Andes Mountains extending above the haze into cleaner upper atmosphere air. Amazon Basin burning

  9. Analogical reasoning in amazons.

    PubMed

    Obozova, Tanya; Smirnova, Anna; Zorina, Zoya; Wasserman, Edward

    2015-11-01

    Two juvenile orange-winged amazons (Amazona amazonica) were initially trained to match visual stimuli by color, shape, and number of items, but not by size. After learning these three identity matching-to-sample tasks, the parrots transferred discriminative responding to new stimuli from the same categories that had been used in training (other colors, shapes, and numbers of items) as well as to stimuli from a different category (stimuli varying in size). In the critical testing phase, both parrots exhibited reliable relational matching-to-sample (RMTS) behavior, suggesting that they perceived and compared the relationship between objects in the sample stimulus pair to the relationship between objects in the comparison stimulus pairs, even though no physical matches were possible between items in the sample and comparison pairs. The parrots spontaneously exhibited this higher-order relational responding without having ever before been trained on RMTS tasks, therefore joining apes and crows in displaying this abstract cognitive behavior. PMID:26084679

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  11. Seasonal cycle and interannual variability in the Amazon hydrologic cycle

    NASA Astrophysics Data System (ADS)

    Zeng, Ning

    1999-04-01

    An analysis of the Amazon basin hydrologic cycle has been carried out using the NASA/Goddard Earth Observing System (GEOS-1) atmospheric reanalysis, observed rainfall of Xie and Arkin [1996], and historical Amazon River discharge. Over a seasonal cycle the precipitation is found to vary by 5 mm d-1, and the runoff is found to vary by 2 mm d-1, while the evaporation largely remains constant. On interannual timescales the hydrologic variability both in the atmosphere and at the land surface is found to be closely related to El Niño-Southern Oscillation (ENSO). The correlation between the Southern Oscillation Index and Xie and Arkin precipitation is 0.8 for the period 1985-1993 and 0.56 for the period 1979-1996. The precipitation lags behind the Southern Oscillation Index by 3-4 months while the Amazon River discharge lags behind the precipitation by another 3 months. The lagged relationship suggests interesting dynamic mechanisms. The reanalysis moisture convergence and observed discharge are used to diagnose basin average soil water storage. The year to year variation in the annual mean soil water storage is ˜200 mm, comparable to the change within a climatological seasonal cycle. In one case, the basin soil water storage increases by 462 mm from September 1987 to March 1989, suggesting the remarkable ability of the tropical rain forest environment to store and take up water.

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

    NASA Astrophysics Data System (ADS)

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

    1984-07-01

    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.

  13. Ballast water: a threat to the Amazon Basin.

    PubMed

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

    2014-07-15

    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

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

    SciTech Connect

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

    1982-08-01

    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.

  15. Impact of tributyltin on antioxidant and DNA damage response in spermatozoa of freshwater prawn Macrobrachium rosenbergii.

    PubMed

    Rani, K Umaa; Musthafa, M Saiyad; War, Mehrajuddin; Al-Sadoon, Mohammad K; Paray, Bilal Ahmad; Shareef, T H Mohamed Ahadhu; Nawas, P Mohideen Askar

    2015-12-01

    Effects of tributyltin (TBT) on antioxidant [total superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR)] and DNA damage levels in the spermatozoa were studied and reported here for the first time in the freshwater prawn Macrobrachium rosenbergii. Three groups of (n = 10 in each group) fishes were exposed to three different nominal concentrations of TBT viz., 1, 2, and 4 mg L(-1) along with control group for 90 days. Significant decrease of antioxidant and increased DNA damage levels were seen at higher doses of 2 and 4 mg L(-1). In prawn, the antioxidant level plays a vital role in sperm protection, activation, differential functions related to the physiology, and reproductive behavior. This study serves as a biomonitoring tool to assess the TBT effects on reproductive behavior of aquatic biota. PMID:26296505

  16. Recruitment and origin of penaeid prawn postlarvae in two South-east African estuaries

    NASA Astrophysics Data System (ADS)

    Forbes, A. T.; Cyrus, D. P.

    1991-09-01

    Input of postlarval stages into the penaeid prawn stocks of Natal, South Africa, was investigated by monitoring immigration into the St Lucia and Kosi estuaries. Five species, Penaeus japonicus Bate, P. indicus Milne Edwards, P. semisulcatus de Haan, P. monodon Fabricius and Metapenaeus monoceros (Fabricius) were recorded. Recruitment into the more northerly Kosi estuary, where offshore conditions are influenced by the south-flowing Agulhas Current, was totally dominated by P. japonicus. At St Lucia, at the northern end of the Tugela Bank, similar numbers of P. japonicus and P. indicus were recorded as well as smaller numbers of the other three species. The differences imply that the Tugela Bank provides the major postlarval input of commercially important species to St Lucia and suggests a greater degree of isolation of the Natal penaeid prawn populations than previously thought.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  18. Changes in the carbon cycle of Amazon ecosystems during the 2010 drought

    NASA Astrophysics Data System (ADS)

    Potter, Christopher; Klooster, Steven; Hiatt, Cyrus; Genovese, Vanessa; Castilla-Rubio, Juan Carlos

    2011-07-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  20. Cadmium accumulation and ultrastructural alterations in oogenesis of the prawn Palaemon serratus (Pennant)

    SciTech Connect

    Papathanassiou, E.

    1986-02-01

    The reproductive cycle of Palaemon serratus (Pennant), an ecologically important species, was studied previously. Recently ultrastructural studies of the oogenesis of P. serratus have been made. The present study was undertaken to determine the effects of cadmium on the process of oogenesis of the common prawn and the levels of cadmium in the the gonads after exposure to cadmium ions. This is important since it will give an indirect indication on how pollutants affect different tissues especially at the ultrastructural level.

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

    NASA Astrophysics Data System (ADS)

    Sreenivasula Reddy, P.

    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.

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

    NASA Astrophysics Data System (ADS)

    Sun, Xiu-Qin; Zhang, Jin-Xing

    1995-09-01

    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.

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

    PubMed Central

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

    2012-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  6. 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)

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

    2013-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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 μg/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.

  8. Acute toxicity of organophosphate fenitrothion on biomarkers in prawn Palaemonetes argentinus (Crustacea: Palaemonidae).

    PubMed

    Lavarías, S; García, C F

    2015-03-01

    The effect of the organophosphate fenitrothion (FS) on the non-target freshwater prawn Palaemonetes argentinus was studied. Initially, the 96-h lethal concentration (LC50) of FS was determined in adult prawns. Inhibition of cholinesterase (ChE) in the muscle and hemolymph was assessed. Then, in the hepatopancreas, the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) were analyzed. Lipid peroxidation (LPO) was also determined in the hepatopancreas. The 96-h LC50 value was 1.12 μg/L. Hemolymph ChE activity showed a significant decrease in exposed prawns to FS compared to the control group, while no significant differences in the muscle were observed between groups (p < 0.05). FS caused a significant increase in the activity of antioxidant enzymes SOD, CAT, and GST compared to the control group (p < 0.02). By contrast, LPO levels were not affected by the pesticide (p < 0.05). These results indicate that P. argentinus is very sensitive to organophosphorus which alter biochemical parameters that are related to antioxidant status. Thus, these parameters could be used as biomarkers for assessing water pollution. PMID:25647787

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

    PubMed

    Huang, Ying; Ren, Qian

    2015-03-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    A 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 datasets 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 towards the Caribbean Sea by the North Brazilian Current but get diverted into the tropical Atlantic when North Brazilian Current rings are shed. Innovative method for satellite data temporal morphing based on remotely sensed surface ocean currents allow to derive SSS at unprecedented spatial (1km) and temporal (1 day) resolution.

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

    ERIC Educational Resources Information Center

    Tacelosky, Kathleen

    2001-01-01

    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.…

  12. Recent Amazon climate as background for possible ongoing and future changes of Amazon humid forests

    NASA Astrophysics Data System (ADS)

    Gloor, M.; Barichivich, J.; Ziv, G.; Brienen, R.; Schöngart, J.; Peylin, P.; Ladvocat Cintra, B. Barcante; Feldpausch, T.; Phillips, O.; Baker, J.

    2015-09-01

    Recent analyses of Amazon runoff and gridded precipitation data suggest an intensification of the hydrological cycle over the past few decades in the following sense: wet season precipitation and peak river runoff (since ˜1980) as well as annual mean precipitation (since ˜1990) have increased, while dry season precipitation and minimum runoff have slightly decreased. There has also been an increase in the frequency of anomalously severe floods and droughts. To provide context for the special issue on Amazonia and its forests in a warming climate we expand here on these analyses. The contrasting recent changes in wet and dry season precipitation have continued and are generally consistent with changes in catchment-level peak and minimum river runoff as well as a positive trend of water vapor inflow into the basin. Consistent with the river records, the increased vapor inflow is concentrated to the wet season. Temperature has been rising by 0.7°C since 1980 with more pronounced warming during dry months. Suggestions for the cause of the observed changes of the hydrological cycle come from patterns in tropical sea surface temperatures (SSTs). Tropical and North Atlantic SSTs have increased rapidly and steadily since 1990, while Pacific SSTs have shifted during the 1990s from a positive Pacific Decadal Oscillation (PDO) phase with warm eastern Pacific temperatures to a negative phase with cold eastern Pacific temperatures. These SST conditions have been shown to be associated with an increase in precipitation over most of the Amazon except the south and southwest. If ongoing changes continue, we expect forests to continue to thrive in those regions where there is an increase in precipitation with the exception of floodplain forests. An increase in flood pulse height and duration could lead to increased mortality at higher levels of the floodplain and, over the long term, to a lateral shift of the zonally stratified floodplain forest communities. Negative effects on forests are mainly expected in the southwest and south, which have become slightly drier and hotter, consistent with tree mortality trends observed at the RAINFOR Amazon forest plot network established in the early 1980s consisting of approximately 150 regularly censused 1ha plots in intact forests located across the whole basin.

  13. Nutrient dynamics in Amazon shelf waters: results from AMASSEDS

    NASA Astrophysics Data System (ADS)

    Demaster, David J.; Pope, Robert H.

    1996-03-01

    Four hydrographic cruises were conducted on the Amazon shelf as part of the AMASSEDS field program. During each cruise, approximately 55 stations were occupied and nutrients, as well as other hydrographic parameters, were measured. The results of this time series sampling program indicate that the nutrient concentrations in the riverine end-member (silicate = 144 μmol kg -1, phosphate = 0.7 μmol kg -1, nitrate = 16 μmol kg -1, ammonium = 0.4 μmol kg -1, and urea = 0.9 μmol kg -1) remain relatively constant, despite a two-fold seasonal variation in river water discharge rate. Of the major nutrients (nitrate, phosphate, ammonium and silicate), nitrate shows the greatest seasonal change in riverine end-member concentration with a high value (23 μmol kg -1) during the March cruise (rising river discharge) and a low value (12 μmol kg -1) during the November cruise (falling river discharge). Nitrate is the dominant nutrient form of inorganic nitrogen throughout most of the river/ocean mixing zone, however, in the outershelf area, where nitrate has been depleted by biological production, this nutrient occurs at concentrations comparable to the other nitrogen species (ammonium, nitrite and urea), which are at levels < 1 μmol kg -1. Nearshore, high turbidity inhibits phytoplankton production because of light limitation, whereas on the outershelf, nitrate appears to be limiting growth more than silicate or phosphate. Nutrient uptake was observed during all four cruises, however, nearly all of this production must be regenerated in shelf bottom waters, because very little of the biogenic materials are buried in the seabed (silicate burial <4% of flux to algal blooms; ˜10% burial of biologically available inorganic nitrogen reaching the river/ocean mixing zone; and <3% burial of phosphate flux to shelf environment). Clearly the Amazon shelf is not an efficient nutrient trap. Initial estimates of primary production on the Amazon shelf suggest that algal blooms are sustained by regeneration to a large extent (up to 83%, 69% and 59% for N, P and Si, respectively) as well as by riverine and upwelled sources. Nutrient budget calculations have been used to establish the dominant external source of nutrients to the algal blooms occurring on the outer shelf. Based on flux core measurements, diffusive nutrient fluxes from Amazon shelf sediments are very low relative to riverine supply rates (silicate flux out = 1.3% of riverine flux, the nitrate plus ammonium flux is essentially zero, and the phosphate seabed flux shows removal of ˜2% of the riverine flux). Inventories of naturally occurring 210Pb were used to estimate the onshore flow of subsurface water onto the Amazon shelf. The radiochemical data indicate that the flux of water onto the shelf may be as much as five to ten times greater than the annual flow of the Amazon River. The nutrient flux from this shoreward movement of ocean water (originating at a depth of 60-100 m water depth) accounts for about 80% of the externally supplied ammonium, 52% of the externally supplied phosphate, 38% of the externally supplied nitrate, and 17% of the externally supplied silicate reaching the outer shelf, with the remainder of the nutrient fluxes coming from the river. Therefore, the outershelf algal blooms are supported to a significant extent by the shoreward flux of nutrients from offshore, subsurface waters.

  14. Penaeus orientolis prawn freshness rapid determination method based on electronic nose and non-linear stochastic resonance technique

    PubMed Central

    Wei, Liu; Yuanyuan, Han; Yanping, Cai; Jiaojiao, Jin; Guohua, Hui

    2015-01-01

    In this paper, Penaeus orientolis prawn freshness rapid determination method using electronic nose (e-nose) and non-linear data processing technique is studied. E-nose responses to prawns stored at 4°C are measured. Meanwhile, physical/chemical indexes (firmness, pH, total volatile basic nitrogen (TVB-N), total viable count (TVC), and human sensory evaluation) are examined to provide freshness references for e-nose analysis. E-nose measurement data is analyzed by principal component analysis (PCA), stochastic resonance (SR), and double-layered cascaded serial stochastic resonance (DCSSR). PCA partially discriminates prawns under different storage time. SR and DCSSR signal-to-noise ratio (SNR) spectrum eigen values discriminate prawns successfully. Multi-variables regressions (MVR) are conducted between physical/chemical indexes and SR/DCSSR output SNR minimal (SNR-Min) values. Results indicate that SNR-Min values present more significant linearity relation with physical/chemical indexes. Prawn freshness forecasting model is developed via Harris fitting regression on DCSSR SNR-Min values. Validating experiments demonstrate that forecasting accuracy of this model is 94.29%. PMID:25551520

  15. Central Amazon Floodplain Hydrodynamics

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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 vrzea floodplain to the south of a 75 km reach of the Rio Solimes, 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 Solimes 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 Solimes 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 Solimes was less significant than from the Purus at less than 1,000 m^{3}s^{-1}, under 1% of Solimes 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.

  16. Tidal fronts and their influence on prawn postlarvae immigration in Albatross Bay, the Gulf of Carpentaria, Australia

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Hua

    1995-06-01

    Studies of dynamics in Albatross Bay, the Gulf of Carpentaria, Australia, show strong tides of which M2 is the dominant constituent in the region. Tidal fronts are present and they can be modelled by a 2-D tidal model. Density currents have also been observed with seasonal variations due to the influence of wet or dry seasons. This paper reviews the effects of these dynamics on the migration of prawn postlarvae in Albatross Bay and its estuaries. It is found that through its vertical movement triggered by change of salinity the prawn postlarvae can be transported from the coast to the estuary by tides within 2.8 weeks. However, this horizontal displacement mechanism may be destroyed by the tidal front in Albatross Bay. Density currents may alter prawn postlarvae positions in Albatross Bay on a seasonal scale.

  17. Are severe droughts in western Amazon here to stay?

    NASA Astrophysics Data System (ADS)

    Fernandes, K.; Goddard, L.; Baethgen, W.; Pinedo-Vasquez, M.

    2012-12-01

    Droughts do not immediately come to mind when one thinks of climate extremes that impact western Amazon (WA), where luscious green rainforest predominates. However, droughts in recent years have made the news due to their large socio-economic impacts, such as increased occurrence of fires, respiratory problems related to smoke and reduced fisheries and fluvial transportation due to low river levels. The two most recent notorious droughts in the region were those of 2005 and 2010, both referred to as a "100-year drought". Whether the severity of recent droughts is related to low frequency natural climate variability and/or climate change is not clear. To assess the relative importance of different modes of temporal variability on WA precipitation we calculate the dry season months (JAS) Standardized Precipitation Index (SPI) from two gridded precipitation datasets over a period of 76 years and statistically decompose them into interannual, inter-decadal and trend components. The same analysis is done for the Negro River standardized minimum water level, a major Amazon tributary for which nearly 100 years of data can be obtained. As we will show, the majority of the total variance of SPI from both precipitation datasets and minimum river water level is explained by internannual variability, and the least by trend. Additionally, the dry season precipitation variability in this region is shown to respond to anomalous North Tropical Atlantic (NTA) sea surface temperature (SST), especially over the last 15 years. To explore whether the different time scales of JAS SPI show similar relationship over the longer time period available (76 yrs), the partitioned time series are correlated to averaged April through September tropical SST. We find the strongest relationship to be with the north-south tropical Atlantic SST gradient (not the NTA alone) in both interannual and inter-decadal time scales, whereas the variability of tropical Pacific SST, know to affects eastern Amazon precipitation, shows no significant relationship to WA JAS SPI variability.

  18. Morphological and histological studies on freshwater prawn Macrobrachium rosenbergii (de man) irradiated with (60)Co gamma radiation.

    PubMed

    Stalin, A; Broos, K V; Sadiq Bukhari, A; Syed Mohamed, H E; Singhal, R K; Venu-Babu, P

    2013-11-15

    This study was framed to investigate the (60)Co gamma radiation induced morphological and histological variations in freshwater prawn Macrobrachium rosenbergii. The LD50 value of (60)Co gamma irradiated M. rosenbergii observed (by probit analysis) at 30 Gy. Prawns were irradiated to four different dose levels (3 mGy, 30 mGy, 300 mGy and 3,000 mGy) using Theratron Phoenix TeleCobalt Unit [P-33] and one control group (without irradiation) maintained separately. Irradiated groups exhibited several morphological variations such as discoloration; damaged rostrum; opaque coloration in cephalothorax; black bands and dot formation in abdomen; deformed uropods and telson in tail regions when compared with control group. The Hepato Somatic Index reflected the severity of radiation on hepatopancreas. Histological variations in gills, hepatopancreas and muscles of irradiated groups were observed. In gills, structural changes such as swollen and fused lamellae, abnormal gill tips, hyperplasic, necrotic and clavate-globate lamellae were observed in gamma irradiated prawns. Accumulation of hemocytes in hemocoelic space, interstitial sinuses filled with abnormal infiltrated hemocytes, the tubular epithelium with ruptured basal laminae, abnormal and coagulated lumen, necrotic tubules, thickened basal laminae, tissue debris, necrotic hepatocytes were observed in irradiated prawn hepatopancreas. In muscle, shrinkage of muscular fiber and necrotic musculature were observed in irradiated prawns. These structural alterations of the organs it is felt could affect the vital physiological functions such as respiration, osmotic and ionic regulation in gills and muscles; absorption, storage and secretion of the hepatopancreas which in turn could adversely affect the growth and survival of freshwater prawn M. rosenbergii. PMID:24140570

  19. Palaeohydrological controls on sedimentary organic matter on Amazon floodplain lakes during the Holocene

    NASA Astrophysics Data System (ADS)

    Moreira, L. S.; Moreira-Turcq, P. F.; Cordeiro, R. C.; Turcq, B.

    2014-12-01

    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 and a predominant C3 vegetation input evidenced by the C/N ratio and d13C. 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. In this period a enhanced aquatic primary productivity was evidenced by the increased d13C values and by a C/N typical of algae, 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. %) and increasing abundance of planktonic species, like Aulacoseira sp., which reflects the expansion of water bodies. The predominance of C3-vegetation and low smectite content suggest 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.

  20. Analysis of Amazon Extreme Drought in Two Reanalysis Datasets

    NASA Astrophysics Data System (ADS)

    de Souza, D. O.; Herdies, D. L.; Berbery, E. H.

    2013-05-01

    Over the past 10 years the Amazon region experienced two major drought events, which had large impacts on vegetation and rivers, affecting directly the transport, fishing, agriculture and health. These events were characterized by large changes in precipitation patterns over the region in the dry wet season. Aiming to analyze and identify anomalies related to the 2005 and 2010 drought, as well as the effects of larger-scale disturbances such as El Niño, we used reanalysis datasets from CFSR/NCEP and MERRA/NASA. Overall the results show that the droughts don't show a very clear signal in datasets reanalyses. Only drought events related to El Niño are well identified in the data. For the 2005 event, the reanalysis move precipitation anomalies for the regions where they are not observed in observational data. The case os 2010 presents the same charateristic, with displacement of the anomalies, and underestimating the observed effects. In the general context of the results, it was observed that there is a direct relationship between the vertical motion in the Atlantic and the precipitation anomalies over the Amazon. The drop in rates of precipitation over the Amazon and the possible increase of the flow in low levels in cases of drought affected directly the precipitation over the La Plata Basin. Thus, even the drought events not being well represented in datasets of reanalysis, it was possible to observe their effects on local and remote almost all South America.

  1. Cyclic sediment deposition within Amazon deep-sea fan

    SciTech Connect

    Manley, P.L.; Flood, R.D.

    1988-08-01

    The Upper and middle Amazon Fan has grown in a cyclic fashion. An individual deposition cycle consists of (1) a widespread basal, acoustically transparent seismic unit (interpreted as debris-flow deposits) that fills and levels preexisting topographic lows, and (2) a levee complex built of overlapping channel-levee systems. Two and possibly three cycles have been identified within the Amazon Fan. The levee complex beneath one debris flow originated from a different submarine canyon than did the levee complex above the debris flow, suggesting that these levee complexes formed during different sea level lowstands. Calculations based on present sediment discharge of the Amazon River suggest that an entire levee complex can form within the time span of a single glacial stage, such as the Wisconsin; however, the levee complex probably could not have formed during the relatively short time interval when sea level rose rapidly at the end of a glacial stage. The basal seismic units (debris-flow deposits) may have been deposited at any time during sea level fluctuations. Although seismic evidence suggests that this cyclic sedimentation pattern may be related to glacio-eustatic sea level variations, cyclic fan growth may be attributed to other processes as well. For example, a bottom-simulating reflector (BSR) observed within the upper fan appears to be a gas hydrate. Migration of the hydrate phase boundary during sea level fluctuations and diapiric activity may be mechanisms for initiating widespread debris flows. 10 figs.

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

    PubMed Central

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

    2010-01-01

    This study analyzed the changes in metallothionein-like proteins (MTLPs) and Energy Reserves (ERs) in hepatopancreas and abdominal muscle of the white prawn Penaeus vannamei. Realistic metal concentration exposure for 10 days to Ni and Pb in solution revealed that juvenile prawns partially induce MTLP in hepatopancreas after Pb exposure. Ni was distributed equally between soluble and insoluble fractions, while Pb was present only in the insoluble fraction, suggesting different detoxification strategy. No changes in lipids and glycogen concentration were detected under these experimental conditions in both tissues analyzed. MTLP could not be considered as a suitable indicator for lead exposure in hepatopancreas. PMID:20862200

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  4. New observations of sinuous channels on the Amazon Fan

    NASA Astrophysics Data System (ADS)

    Flood, R. D.

    2014-12-01

    High-sinuosity submarine fan channels on the Amazon Fan were first observed using long-range (GLORIA) side-scan sonar in 1982 and mapped in greater detail using multibeam sonar in 1984. These data have provided important insights into the nature and evolution of submarine channel systems. Subsequent studies on the Amazon Fan have focused on avulsion patterns, sedimentation patterns, fan growth and the climate record contained in fan sediments, and there has been relatively little additional work on the details of sinuous channel morphology. Channels on the Amazon Fan have been imaged by multibeam sonar on several occasions since 1984 during focused studies, regional mapping and ship transit. These multibeam data are being compiled and studied to better characterize these iconic channels. One observation of particular interest is that, on the Amazon Fan, channel-wall slumps appear to be more common than previously thought. Drilling of a cut-off meander during ODP Leg 155 on the Amazon Fan showed the presence of slumped material deeper in the channel suggesting that failure of the channel wall was in part responsible for the abandonment and filling of that meander loop. The failure also apparently created a sandy debris flow with clasts of fine-grained levee material transported in a sandy matrix. This sandy debris flow may have been able to flow along the channel and deposit at the seaward end where similar sediments can be found. Disturbed zones now visible on the inner walls of channels at several other places along the channels suggest that these kinds of inner-wall slumps may play important roles in channel evolution and fan growth. Channel-blocking slumps can isolate channel loops which can then fill with sandy sediments, and avulsions are likely if this kind of slump fills the channel. The failure of channel walls can also lead to new channel segments that tend to straighten the channel. Dramatic changes to the shape of the channel can likely lead to large and sudden changes in the planform shape of meanders farther down the channel. Thus while similarities in sinuosity patterns suggest that both submarine channels and river channels are being altered by repetitive flow events, channel-wall slumping in submarine channels may affect submarine channel evolution to a greater extent than similar events in rivers.

  5. Uranium in river water

    SciTech Connect

    Palmer, M.R. ); Edmond, J.M. )

    1993-10-01

    The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains do not represent a significant source of U in river waters. In addition, the authors have determined dissolved U levels in forty rivers from around the world and coupled these data with previous measurements to obtain an estimate for the global flux of dissolved U to the oceans. The average concentration of U in river waters is 1.3 nmol/kg, but this value is biased by very high levels observed in the Ganges-Brahmaputra and Yellow rivers. When these river systems are excluded from the budget, the global average falls to 0.78 nmol/kg. The global riverine U flux lies in the range of 3-6 [times] 10[sup 7] mol/yr. The major uncertainty that restricts the accuracy of this estimate (and that of all other dissolved riverine fluxes) is the difficulty in obtaining representative samples from rivers which show large seasonal and annual variations in runoff and dissolved load.

  6. Toxicity of cryoprotectants agents in freshwater prawn embryos of Macrobrachium amazonicum.

    PubMed

    Ferreira, Arthur Vinícius Lourenço; Castro, Elias José Teles; Barbosa, Mariana Silva Alves; de Sousa, Míriam Luzia Nogueira Martins; de Araújo Neto, Manoel Paiva; Filho, Aldeney Andrade Soares; de Souza Sampaio, Celia Maria

    2015-12-01

    The process of cooling and cryopreservation of prawn embryos is a viable alternative for a continuous supply of larvae for freshwater prawn farming ponds. However, studies involving the application of those techniques as well as on toxicity of cryoprotectants in freshwater prawn embryos are scarce. Thus, this study aims to test the toxicity of methylic alcohol (MET), dimethyl sulfoxide (DMSO) and ethylene glycol (EG) on Macrobrachium amazonicum embryos. For the present experiment, pools of embryos were taken from 15 M. amazonicum females and were divided into three groups and tested in duplicate at concentrations of 10, 5, 3; 1, 0.5 or 0.1%. Toxicity tests were conducted for 24 h in Falcon® pipes to obtain the lethal concentration for 50% of the larvae (LC50). After the set period for testing, random samples of embryos were removed for morphological analysis under stereoscopic microscopes. Results were analysed using analysis of variance (ANOVA) and Tukey's test at a 5% significance level and Trimmed Spearman-Karber Analysis to determine LC50-24 h. DMSO toxicity tests revealed that 5% and 10% concentrations showed the highest toxicity and differed from the control (P ≤ 0.05), 24h-LC50 was 437.4 ± 14.4 µL. MET was less toxic among the tested cryoprotectants and concentrations did not allow the determination of its LC50-24h. For tests with EG, concentrations of 3, 5 or 10% solutions resulted in a 100% mortality to tested embryos; EG was the tested cryoprotectant with the highest toxicity, with an LC50-24h average of 81.91 ± 35.3 µl. PMID:25255785

  7. Molecular importance of prawn large heat shock proteins 60, 70 and 90.

    PubMed

    Chaurasia, Mukesh Kumar; Nizam, Faizal; Ravichandran, Gayathri; Arasu, Mariadhas Valan; Al-Dhabi, Naif Abdullah; Arshad, Aziz; Elumalai, Preetham; Arockiaraj, Jesu

    2016-01-01

    Considering the importance of heat shock proteins (HSPs) in the innate immune system of prawn, a comparative molecular approach was proposed to study the crustacean large HSPs 60, 70 and 90. Three different large HSPs were identified from freshwater prawn Macrobrachium rosenbergii (Mr) cDNA library during screening. The structural and functional characteristic features of HSPs were studied using various bioinformatics tools. Also, their gene expression and mRNA regulation upon various pathogenic infections was studied by relative quantification using 2(-ΔΔCT) method. MrHSP60 contains a long chaperonin 60 domain at 46-547 which carries a chaperonin 60 signature motif between 427 and 438, whereas MrHSP70 contains a long HSP70 domain at 21-624 and MrHSP90 carries a HSP90 domain at 188-719. The two dimensional analysis showed that MrHSP60 contains more amino acids (52%) in helices, whereas MrHSP70 (40.6%) and MrHSP90 (51.8%) carried more residues in coils. Gene expression results showed significant (P < 0.05) expression of MrHSP60, 70 and 90 in haemocyte, gill and hepatopancreas, respectively. Further, the expression level was up-regulated upon bacterial (Aeromonas hydrophilla and Vibrio harveyi) and viral [white spot syndrome virus (WSSV) and M. rosenbergii nodo virus (MrNV)] infections during various time periods. The gene expression results exhibited the potential involvement of these three HSPs in the immune system of prawn. The study indicated the potentiality of these molecules, thereby protecting cells against pathogens as well as severe cellular and environmental stresses in crustaceans. PMID:26631804

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

    SciTech Connect

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

    2005-03-15

    Harmful cyanobacteria pose a hazard to aquatic ecosystems due to toxins (hepatotoxic microcystins, nodularins, and cylindrospermopsin) they produce. The microcystins and nodularins are potent toxins, which are also tumor promoters. The microcystins and nodularins may accumulate into aquatic organisms and be transferred to higher trophic levels, and eventually affect vector animals and consumers. Prawn farming is a rapidly growing industry in Australia. Because information regarding effects of cyanobacteria at prawn farms was lacking, we examined diversity of cyanobacteria and toxin production plus bioaccumulation into black tiger prawns (Penaeus monodon) under both field (northern New South Wales, Australia, December 2001-April 2002) and laboratory conditions. Samples were analyzed for hepatotoxins using enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The maximum density of cyanobacteria (1 x 10{sup 6} to 4 x 10{sup 6} cells/l) was reached in April. Cyanobacteria encountered were Oscillatoria sp. (up to 4 x 10{sup 6} cells/l), Pseudanabaena sp. (up to 1.8 x 10{sup 6} cells/l), Microcystis sp. (up to 3.5 x 10{sup 4} cells/l), and Aphanocapsa sp. (up to 2 x 10{sup 4} cells/l). An uncommon cyanobacterium, Romeria sp. (up to 2.2 x 10{sup 6} cells/l), was also observed. Contrasting earlier indications, toxic Nodularia spumigena was absent. Despite that both Oscillatoria sp. and Microcystis sp. are potentially hepatotoxic, hepatotoxin levels in phytoplankton samples remained low (up to 0.5-1.2 mg/kg dw; ELISA) in 2001-2002. ELISA was found suitable not only for phytoplankton but prawn tissues as well. Enzymatic pretreatment improved extractability of hepatotoxin from cyanobacteria (nodularin from N. spumigena as an example), but did not generally increase toxin recovery from prawn hepatopancreas. There were slightly increasing hepatotoxin concentrations in prawn hepatopancreas (from 6-20 to 20-80 {mu}g/kg dw; ELISA) during the study. Hepatotoxin concentrations in surface sediment remained low (<5 {mu}g/kg dw; ELISA) throughout the study. Laboratory experiments indicated that prawn hepatopancreas, heart, and brain were primary organs for hepatotoxin bioaccumulation. Toxin concentration in other organs, including muscle, was less effective. Orally administered nodularin levels in hepatopancreas rapidly decreased from initial 830 to 250 {mu}g/kg dw in 96 h. Similarly, concentration of microcystin-LR injected in prawns decreased from 130 to 30 {mu}g/kg dw (hepatopancreas) in 2 h. These results demonstrate that potential risks caused by cyanobacteria in prawn farming (farmers, prawns, and consumers) were not substantial in 2001-2002. Although prawns may act as vectors for toxin transfer, they did not accumulate alerting amounts of hepatotoxins and were able to effectively detoxify them. Because bloom toxicity may vary, low-frequency toxin monitoring is recommended.

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

    PubMed

    1989-01-01

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

  10. Potential hydrologic changes in the Amazon by the end of the 21st century and the groundwater buffer

    NASA Astrophysics Data System (ADS)

    Pokhrel, Yadu N.; Fan, Ying; Miguez-Macho, Gonzalo

    2014-08-01

    This study contributes to the discussions on the future of the Amazon rainforest under a projected warmer-drier climate from the perspectives of land hydrology. Using IPCC HadGEM2-ES simulations of the present and future Amazon climate to drive a land hydrology model that accounts for groundwater constraint on land drainage, we assess potential hydrologic changes in soil water, evapotranspiration (ET), water table depth, and river discharge, assuming unchanged vegetation. We ask: how will ET regimes shift at the end of the 21st century, and will the groundwater help buffer the anticipated water stress in some places-times? We conducted four 10 yr model simulations, at the end of 20th and 21st century, with and without the groundwater. Our model results suggest that, first, over the western and central Amazon, ET will increase due to increased potential evapotranspiration (PET) with warmer temperatures, despite a decrease in soil water; that is, ET will remain PET or atmospheric demand-limited. Second, in the eastern Amazon dry season, ET will decrease in response to decreasing soil water, despite increasing PET demand; that is, ET in these regions-seasons will remain or become more soil water or supply-limited. Third, the area of water-limited regions will likely expand in the eastern Amazonia, with the dry season, as indicated by soil water store, even drier and longer. Fourth, river discharge will be significantly reduced over the entire Amazon but particularly so in the southeastern Amazon. By contrasting model results with and without the groundwater, we found that the slow soil drainage constrained by shallow groundwater can buffer soil water stress, particularly in southeastern Amazon dry season. Our model suggests that, if groundwater buffering effect is accounted for, the future Amazon water stress may be less than that projected by most climate models.

  11. Potential Hydrologic Changes in the Amazon By the End of the 21st Century and the Groundwater Buffer

    NASA Astrophysics Data System (ADS)

    Pokhrel, Y. N.; Fan, Y.; Miguez-Macho, G.

    2014-12-01

    This study contributes to the discussions on the future of the Amazon rainforest under a projected warmer-drier climate from the perspectives of land hydrology. Using IPCC HadGEM2-ES simulations of the present and future Amazon climate to drive a land hydrology model that accounts for groundwater constraint on land drainage, we assess potential hydrologic changes in soil water, evapotranspiration (ET), water table depth, and river discharge, assuming unchanged vegetation. We ask: how will ET regimes shift at the end of the 21st century, and will the groundwater help buffer the anticipated water stress in some places-times? We conducted four 10yr model simulations, at the end of 20th and 21st century, with and without the groundwater. Our model results suggest that, first, over the western and central Amazon, ET will increase due to increased potential evapotranspiration (PET) with warmer temperatures, despite a decrease in soil water; that is, ET will remain atmosphere or demand-limited. Second, in the eastern Amazon dry season, ET will decrease in response to decreasing soil water, despite increasing PET demand; that is, ET in these regions-seasons will remain or become more soil water or supply-limited. Third, the area of water-limited regions will likely expand in the eastern Amazonia, with the dry season, as indicated by soil water store, even drier and longer. Fourth, river discharge will be significantly reduced over the entire Amazon but particularly so in the southeastern Amazon. By contrasting model results with and without the groundwater, we found that the slow soil drainage constrained by a shallow groundwater can buffer soil water stress, particularly in southeastern Amazon dry season. Our model suggests that, if the groundwater buffering effect is accounted for, the future Amazon water stress may be less than projected by most climate models.

  12. Intensification of the Amazon hydrological cycle over the last two decades

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  13. Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

    USGS Publications Warehouse

    Baker, P.A.; Fritz, S.C.; Silva, C.G.; Rigsby, C.A.; Absy, M.L.; Almeida, R.P.; Caputo, M.C.; Chiessi, C.M.; Cruz, F.W.; Dick, C.W.; Feakins, S.J.; Figueiredo, J.; Freeman, K.H.; Hoorn, C.; Jaramillo, C.A.; Kern, A.; Latrubesse, E.M.; Ledru, M.P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W.E.; Ramos, M.I.F.; Ribas, C.C.; Trinadade, R.; West, A.J.; Wahnfried, I.; Willard, Debra A.

    2015-01-01

    This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

  14. Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

    NASA Astrophysics Data System (ADS)

    Baker, P. A.; Fritz, S. C.; Silva, C. G.; Rigsby, C. A.; Absy, M. L.; Almeida, R. P.; Caputo, M.; Chiessi, C. M.; Cruz, F. W.; Dick, C. W.; Feakins, S. J.; Figueiredo, J.; Freeman, K. H.; Hoorn, C.; Jaramillo, C.; Kern, A. K.; Latrubesse, E. M.; Ledru, M. P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W. E.; Ramos, M. I. F.; Ribas, C. C.; Trnadade, R.; West, A. J.; Wahnfried, I.; Willard, D. A.

    2015-12-01

    This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

  15. Genetic variability in three Amazon parrot species.

    PubMed

    Lopes, I F; Del Lama, M A; Del Lama, S N

    2007-12-01

    Parrots of the genus Amazona are among the most threatened species of the Order Pscittaciformes. This work describes allozyme polymorphisms in three Amazon parrot species--the Blue-fronted Amazon (Amazona aestiva), the Orange-winged Amazon (Amazona amazonica), and the Festive Amazon (Amazona festiva) -, and provides useful data for the evaluation of their genetic variability. We electrophoretically analyzed blood samples from 68 wild-caught individuals, maintained in captivity in three Brazilian zoos. Eight of the ten studied enzyme loci exhibited polymorphism. Glucosephosphate isomerase (Gpi) proved to be a diagnostic locus for the identification of these Amazon species. The expected average heterozygosity of the Blue-fronted Amazon (0.060) differed significantly from the expected heterozygosities of the Orange-winged Amazon and the Festive Amazon (0.040 and 0.039, respectively). This result was discussed as a consequence of hybridization between two geographic A. aestiva subspecies, and alternatively as a particular trait of this species. Genetic variability of the Blue-fronted Amazon compared to birds in general is not low on a species-wide level, despite the fact that this parrot is one of the most illegally traded species. Allozyme analysis proved to be an useful tool in monitoring the genetic variation within the genus Amazona and can be applied in the management program of other threatened species of this genus. PMID:18278355

  16. First description of 'Chalky back' phenomenon in banana prawns (Fenneropenaeus merguiensis) and its possible association with Vibrio and Photobacterium species.

    PubMed

    Hatje, Eva; Minniti, Giusi; Stewart, Michael J; Neuman, Christina; Knibb, Wayne; Katouli, Mohammad

    2016-02-01

    Here we report a newly identified 'Chalky back' phenomenon in banana prawns (Fenneropenaeus merguiensis) farmed in North Queensland, Australia. This was characterized by localized white discoloured segmentation of the cervical groove, moreover, after cooking the prawns exploded, making them unfit for commercial sale. Histological examination revealed breakdown of gut and abdominal muscle tissue in some moribund specimens. We selectively isolated Vibrio spp., which are known prawn pathogens, from healthy and Chalky back specimens. Isolated bacteria were identified, typed and tested for the presence of eight virulence genes (VGs), biofilm formation, adherence and cytotoxicity to fish cells. In all, 32 isolates were recovered and identified as Vibrio harveyi, V. owensii, V. sinaloensis-like, V. campbellii, V. shilonii, Vibrio sp. and Photobacterium damselae using 16S rRNA gene sequencing. All V. harveyi carried VGs coding for haemolysin, toxR and flagella; formed biofilm; and adhered to both cell lines. This was similar to the V. sinaloensis-like strains that were only isolated from Chalky back specimens. Our data suggest that Vibrio spp. may play a role in the pathogenesis of Chalky back. This study is the first report of Chalky back phenomenon in farmed banana prawns that needs to be closely monitored by the industry. PMID:26825678

  17. Changes in the fish fauna of a tropical Australian estuary since 1990 with reference to prawn predators and environmental change

    NASA Astrophysics Data System (ADS)

    Blaber, S. J. M.; Griffiths, S. P.; Pillans, R.

    2010-03-01

    As part of a study of the reasons for declining commercial banana prawn catches in the Weipa area of the Gulf of Carpentaria, and in order to assess whether changes in predator numbers may be a factor influencing prawn numbers, the species composition, numbers and biomasses of fishes in the Embley estuary were re-examined in February 2005 for comparison with the results of a study between 1986 and 1990. The new study duplicated previous methods and used the same sampling sites and the same gear employed during February sampling periods from 1986 to 1990. Overall, the species diversity and catch rates, as well as the numbers of penaeid prawn predators had changed little over 20 years. The overall catch rate for 2005 was 37.4 g m -1 h -1, not significantly different from the overall catch rate of 32.8 g m -1 h -1 (SE 6.6) for the period from 1987 to 1989. The results are discussed in relation to environmental factors and climate change, as well as the substantial declines in prawn catches, which had fallen from over 800 tonnes per annum prior to 1998, to about 70 tonnes per annum.

  18. Extratropical Respones to Amazon Deforestation

    NASA Astrophysics Data System (ADS)

    Badger, A.; Dirmeyer, P.

    2014-12-01

    Land-use change (LUC) is known to impact local climate conditions through modifications of land-atmosphere interactions. Large-scale LUC, such as Amazon deforestation, could have a significant effect on the local and regional climates. The question remains as to what the global impact of large-scale LUC could be, as previous modeling studies have shown non-local responses due to Amazon deforestation. A common shortcoming in many previous modeling studies is the use of prescribed ocean conditions, which can act as a boundary condition to dampen the global response with respect to changes in the mean and variability. Using fully coupled modeling simulations with the Community Earth System Model version 1.2.0, the Amazon rainforest has been replaced with a distribution of representative tropical crops. Through the modifications of local land-atmosphere interactions, a significant change in the region, both at the surface and throughout the atmosphere, can be quantified. Accompanying these local changes are significant changes to the atmospheric circulation across all scales, thus modifying regional climates in other locales. Notable impacts include significant changes in precipitation, surface fluxes, basin-wide sea surface temperatures and ENSO behavior.

  19. Amino acid sequences and activities of multiple hyperglycemic hormones from the Kuruma prawn, Penaeus japonicus.

    PubMed

    Yang, W J; Aida, K; Nagasawa, H

    1997-01-01

    By means of a single-step reversed-phase HPLC, six CHH family peptides were isolated from sinus gland extracts of the kuruma prawn, Penaeus japonicus. Five of these peptides (Pej-SGP-I, -II, -III, -V, and -VI) expressed hyperglycemic activity and were considered to be the hyperglycemic hormones of this prawn. The amino acid sequences of the five peptides were determined (the amino acid sequence of Pej-SGP-III had been previously determined), revealing that all consisted of 72 amino acid residues with a free amino-terminus and an amidated carboxyl-terminus. They showed considerable sequence similarity to one another, but much less similarity to Pej-SGP-IV with molt-inhibiting activity, the sequence of which had also been determined previously. Examination of the dose-response relationship of these peptides showed that they were equally potent but had different efficacies, which were in the order of Pej-SGP-V, -VI > -III, -I > -II, corresponding well with their sequence characteristics. PMID:9210164

  20. High and low molecular weight proteolytic activities in prawn (Metapenaeus brevicornis) muscle.

    PubMed

    Karani, M N; Gore, M S; Nair, P M

    1999-08-01

    Muscle extract of prawn (Metapenaeus brevicornis) expressed high azocoll lytic activity compared to extracts of many other prawn varieties; the activity was also inhibited to a small extent by dithiothreitol. Ammonium sulphate precipitation, subsequent extraction at pH 5.6 and chromatography revealed the occurrence of two types of azocoll lytic activities: one, high molecular weight (630 kDa) and the other low molecular weight (< 30 kDa) enzyme. The former was stimulated by dithiothreitol whereas the latter was inhibited. SDS PAGE of high molecular weight preparation did not show homogeneity but the profile was similar to that of the low molecular weight fraction. Gel filtration of high molecular weight enzyme following incubation at high pH revealed the formation of low molecular weight fractions having activity towards azocoll. Chymotrypsin-like activity associated with high molecular weight enzyme was also susceptible to dissociation by high pH. Azocoll lytic activity of both enzymes was strongly inhibited by 1,10-phenanthroline. PMID:10650730

  1. Deepwater Chondrichthyan Bycatch of the Eastern King Prawn Fishery in the Southern Great Barrier Reef, Australia.

    PubMed

    Rigby, Cassandra L; White, William T; Simpfendorfer, Colin A

    2016-01-01

    The deepwater chondrichthyan fauna of the Great Barrier Reef is poorly known and life history information is required to enable their effective management as they are inherently vulnerable to exploitation. The chondrichthyan bycatch from the deepwater eastern king prawn fishery at the Swain Reefs in the southern Great Barrier Reef was examined to determine the species present and provide information on their life histories. In all, 1533 individuals were collected from 11 deepwater chondrichthyan species, with the Argus skate Dipturus polyommata, piked spurdog Squalus megalops and pale spotted catshark Asymbolus pallidus the most commonly caught. All but one species is endemic to Australia with five species restricted to waters offshore from Queensland. The extent of life history information available for each species varied but the life history traits across all species were characteristic of deep water chondrichthyans with relatively large length at maturity, small litters and low ovarian fecundity; all indicative of low biological productivity. However, variability among these traits and spatial and bathymetric distributions of the species suggests differing degrees of resilience to fishing pressure. To ensure the sustainability of these bycatch species, monitoring of their catches in the deepwater eastern king prawn fishery is recommended. PMID:27218654

  2. Optimal oxygen pressure and time for reduced bubble formation in the N2-saturated decompressed prawn.

    PubMed

    Ertracht, O; Arieli, R; Arieli, Y; Ron, R; Erlichman, Z; Adir, Y

    2005-04-01

    Bubbles that grow during decompression are believed to originate from preexisting gas micronuclei. We showed that pretreatment of prawns with 203 kPa oxygen before nitrogen loading reduced the number of bubbles that evolved on decompression, presumably owing to the alteration or elimination of gas micronuclei (Arieli Y, Arieli R, and Marx A. J Appl Physiol 92: 2596-2599, 2002). The present study examines the optimal pretreatment for this assumed crushing of gas micronuclei. Transparent prawns were subjected to various exposure times (0, 5, 10, 15, and 20 min) at an oxygen pressure of 203 kPa and to 5 min at different oxygen pressures (PO2 values of 101, 151, 203, 405, 608, and 810 kPa), before nitrogen loading at 203 kPa followed by explosive decompression. After the decompression, bubble density and total gas volume were measured with a light microscope equipped with a video camera. Five minutes at a PO2 of 405 kPa yielded maximal reduction of bubble density and total gas volume by 52 and 71%, respectively. It has been reported that 2-3 h of hyperbaric oxygen at bottom pressure was required to protect saturation divers decompressed on oxygen against decompression sickness. If there is a shorter pretreatment that is applicable to humans, this will be of great advantage in diving and escape from submarines. PMID:15579569

  3. Steroids and genes related to steroid biosynthesis in the female giant freshwater prawn, Macrobrachium rosenbergii.

    PubMed

    Thongbuakaew, Tipsuda; Siangcham, Tanapan; Suwansa-Ard, Saowaros; Elizur, Abigail; Cummins, Scott F; Sobhon, Prasert; Sretarugsa, Prapee

    2016-03-01

    The giant freshwater prawn, Macrobrachium rosenbergii, is important to many Asian countries due to its high economic value as an aquaculture product. With demand increasing, there is requirement for a better understanding of the biosynthetic components that regulate its growth and reproduction, including steroids, in order to help increase production. Vertebrate-type steroids and their receptors were identified in crustaceans and implicated in reproduction. In this study, we presented the sex steroids estradiol and progesterone by LC-MS/MS in female M. rosenbergii, and reveal steroidogenic-related genes by in silico analysis of de novo assembled transcriptomes. Comparative analysis with other species was performed to confirm their putative role, as well as tissue-specific and quantitative gene expression. We reveal 29 transcripts that encode for steroidogenic-related proteins, including steroidogenic enzymes, a nuclear steroid hormone receptors, and a steroidogenic factor. Moreover, we identified for the first time the presence of steroidogenic factor 1, StAR-related lipid transfer protein, estradiol receptor- and progesterone-like protein in M. rosenbergii. Those targeted for gene expression analysis (3 beta-hydroxysteroid dehydrogenase, 17 beta-hydroxysteroid dehydrogenase, estrogen sulfotransferase and progesterone receptor-like) showed widespread expression within many tissues, and at relatively high levels in the central nervous system (CNS) during ovarian maturation. In summary, we provide further evidence for the existence of steroidogenic pathways in crustaceans, which may be useful for advancing prawn aquaculture. PMID:26774430

  4. Isolation of AHL-degrading bacteria from micro-algal cultures and their impact on algal growth and on virulence of Vibrio campbellii to prawn larvae.

    PubMed

    Pande, Gde Sasmita Julyantoro; Natrah, Fatin Mohd Ikhsan; Flandez, Ace Vincent Bravo; Kumar, Uday; Niu, Yufeng; Bossier, Peter; Defoirdt, Tom

    2015-12-01

    Inactivation of quorum sensing (QS) signal molecules, such as acylhomoserine lactones (AHLs) of pathogenic bacteria, has been proposed as a novel method to combat bacterial diseases in aquaculture. Despite the importance of micro-algae for aquaculture, AHL degradation by bacteria associated with micro-algal cultures has thus far not been investigated. In this study, we isolated Pseudomonas sp. NFMI-T and Bacillus sp. NFMI-C from open cultures of the micro-algae Tetraselmis suecica and Chaetoceros muelleri, respectively. An AHL degradation assay showed that either monocultures or co-cultures of the isolates were able to degrade the AHL N-hexanoyl-L-homoserine lactone. In contrast, only Bacillus sp. NFMI-C was able to inactivate N-hydroxybutanoyl-L-homoserine lactone, the AHL produced by Vibrio campbellii. The isolated bacteria were able to persist for up to 3 weeks in conventionalized micro-algal cultures, indicating that they were able to establish and maintain themselves within open algal cultures. Using gnotobiotic algal cultures, we found that the isolates did not affect growth of the micro-algae from which they were isolated, whereas a mixture of both isolates increased the growth of Tetraselmis and decreased the growth of Chaetoceros. Finally, addition of Bacillus sp. NFMI-C to the rearing water of giant river prawn (Macrobrachium rosenbergii) larvae significantly improved survival of the larvae when challenged with pathogenic V. campbellii, whereas it had no effect on larval growth. PMID:26344339

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

    PubMed Central

    2013-01-01

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

  6. Projected increases in the annual flood pulse of the Western Amazon

    NASA Astrophysics Data System (ADS)

    Zulkafli, Zed; Buytaert, Wouter; Manz, Bastian; Véliz Rosas, Claudia; Willems, Patrick; Lavado-Casimiro, Waldo; Guyot, Jean-Loup; Santini, William

    2016-01-01

    The impact of a changing climate on the Amazon basin is a subject of intensive research because of its rich biodiversity and the significant role of rainforests in carbon cycling. Climate change has also a direct hydrological impact, and increasing efforts have focused on understanding the hydrological dynamics at continental and subregional scales, such as the Western Amazon. New projections from the Coupled Model Inter-comparison Project Phase 5 ensemble indicate consistent climatic warming and increasing seasonality of precipitation in the Peruvian Amazon basin. Here we use a distributed land surface model to quantify the potential impact of this change in the climate on the hydrological regime of the upper Amazon river. Using extreme value analysis, historical and future projections of the annual minimum, mean, and maximum river flows are produced for a range of return periods between 1 and 100 yr. We show that the RCP 4.5 and 8.5 scenarios of climate change project an increased severity of the wet season flood pulse (7.5% and 12% increases respectively for the 100 yr return floods). These findings agree with previously projected increases in high extremes under the Special Report on Emissions Scenarios climate projections, and are important to highlight due to the potential consequences on reproductive processes of in-stream species, swamp forest ecology, and socio-economy in the floodplain, amidst a growing literature that more strongly emphasises future droughts and their impact on the viability of the rainforest system over greater Amazonia.

  7. Assesing Hydrophysical/Enivornmenal impacts by Dams in the Amazon (fluvial) Basin

    NASA Astrophysics Data System (ADS)

    Wight, C.; Latrubesse, E. M.

    2014-12-01

    Growing demands from human activities are increasing the pressure and impacts on the Amazon River basin. Covering almost 40% of South America, the Amazon River basin's health is of global importance. With tributaries in 6 different countries, the anthropogenic impacts on this large system are complex and hard to synthesize. However to better understand large system responses to human impacts such an analysis is called for. Our objective is to organize a rigorous analysis of the potential hydro-physical impacts of dams on the major sub-basins of the Amazon. We are incorporating existing data of sediment fluxes, deforestation and land-use land-change to include the entire extent of the basin as defined by the fluvial unit. In addition, we will be analyzing the spatial distributions of dams (planned, under construction, and constructed) within each sub-basin. Our preliminary results have used statistical analysis and remote sensing to calculate the extent of deforestation on fluvial regimes of the legal Amazon and concentrated to identify the potential disruptions of sediment fluxes. Combining the spatial distributions of dam sites, and deforestation per sub-basin we will develop a system to interpret land-use and land-change per catchment. This in turn will allow us to better predict changes in the fluvial regimes and allow for comparisons of vulnerability.

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

    PubMed

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

    2010-03-01

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

  9. Acyclic Lipids in Amazon Shelf Waters

    NASA Astrophysics Data System (ADS)

    Elias, V. O.; Cardoso, J. N.; Simoneit, B. R. T.

    2000-02-01

    Acyclic lipids were analysed for dissolved (<1·2 μm) and particulate (>1·2 μm) material from surface water of the Amazon continental shelf to correlate the direct inputs with diagenetic processes of the organic matter and to assess the differences in compound distribution patterns of the samples. The dissolved samples contained n -alkanes with an unusual even-to-odd carbon number predominance Amazon River. Furthermore, the Pr/Ph ratios calculated for the dissolved samples indicate that the organic matter in the surface of the highly turbid waters passed through an anaerobic stage. The differences in the acyclic hydrocarbon profiles of the dissolved and particulate phases show that organic inputs are preserved differently in smaller and larger particles.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  11. Direct use of low temperature geothermal water by Aquafarms International, Inc. for freshwater aquaculture (prawns and associated species). An operations and maintenance manual

    SciTech Connect

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

    1984-04-01

    In connection with an ongoing commercial aquaculture project in the Coachella Valley, California; a twelve month prawn growout demonstration project was conducted. This project began in August, 1979 and involved the use of low temperature (85/sup 0/F) geothermal waters to raise freshwater prawns, Macrobrachium rosenbergii (deMan), in earthen ponds. The following publication is an operations and maintenance guide which may by useful for those interested in conducting similar enterprises.

  12. Effects of dietary administration of water hyacinth (Eichhornia crassipes) extracts on the immune responses and disease resistance of giant freshwater prawn, Macrobrachium rosenbergii.

    PubMed

    Chang, Chin-Chyuan; Tan, Hui-Ching; Cheng, Winton

    2013-07-01

    The hot-water extract of Eichhornia crassipes leaves (ECE) was produced and incorporated into the diet of the prawn, Macrobrachium rosenbergii, as an immunostimulant. Survival rates of prawn against Lactococcus garvieae, and its immune parameters including the total haemocyte count (THC), different haemocyte count (DHC), phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, transglutaminase (TG) activity, haemolymph coagulation time, and phagocytic activity and clearance efficiency against L. garvieae by M. rosenbergii were determined when prawn (23.0 ± 2.8 g) were fed ECE-containing diets at 0, 1.0, 2.0 and 3.0 g kg(-1). Prawn fed a diet containing ECE at 2.0 and 3.0 g kg(-1) for 12 days showed significantly increased THC, HC, GC, PO activity, RBs, SOD activity, GPx activity, and TG activity, and a significantly decreased coagulation time. The phagocytic activity and clearance efficiency against L. garvieae of prawn fed the ECE-containing diets at 1.0, 2.0, and 3.0 g kg(-1) were significantly higher than those of prawn fed the control diet at 3-12 days. Survival rates of M. rosenbergii fed the diet containing ECE at concentrations of 2 and 3 g kg(-1) were significantly higher than those fed the control diet after challenge with L. garvieae for 48-144 h. The relative percentage survival of prawn fed the 1.0, 2.0, and 3.0 g kg(-1) ECE-containing diets for 12 days were 17.5%, 39.1%, and 52.2%. It was concluded that the ECE can be used as an immunostimulant for prawn through dietary administration to enhance immune responses and resistance of M. rosenbergii against L. garvieae. PMID:23603238

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

    PubMed

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

    2014-10-01

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

  14. Amazon deforestation and climate change

    SciTech Connect

    Shukla, J.; Nobre, C.; Sellers, P. )

    1990-03-16

    A coupled numerical model of the global atmosphere and biosphere has been used to assess the effects of Amazon deforestation on the regional and global climate. When the tropical forests in the model were replaced by degraded grass (pasture), there was a significant increase in surface temperature and a decrease in evapotranspiration and precipitation over Amazonia. In the simulation, the length of the dry season also increased; such an increase could make reestablishment of the tropical forests after massive deforestation particularly difficult. 31 refs., 3 figs., 2 tabs.

  15. Patterns of Geographic Expansion of Aedes aegypti in the Peruvian Amazon

    PubMed Central

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

    2014-01-01

    Background and Objectives In the Peruvian Amazon, the dengue vector Aedes aegypti is abundant in large urban centers such as Iquitos. In recent years, it has also been found in a number of neighboring rural communities with similar climatic and socioeconomic conditions. To better understand Ae. aegypti spread, we compared characteristics of communities, houses, and containers in infested and uninfested communities. Methods We conducted pupal-demographic surveys and deployed ovitraps in 34 communities surrounding the city of Iquitos. Communities surveyed were located along two transects: the Amazon River and a 95km highway. We calculated entomological indices, mapped Ae. aegypti presence, and developed univariable and multivariable logistic regression models to predict Ae. aegypti presence at the community, household, or container level. Results Large communities closer to Iquitos were more likely to be infested with Ae. aegypti. Within infested communities, houses with Ae. aegypti had more passively-filled containers and were more often infested with other mosquito genera than houses without Ae. aegypti. For containers, large water tanks/drums and containers with solar exposure were more likely to be infested with Ae. aegypti. Maps of Ae. aegypti presence revealed a linear pattern of infestation along the highway, and a scattered pattern along the Amazon River. We also identified the geographical limit of Ae. aegypti expansion along the highway at 19.3 km south of Iquitos. Conclusion In the Peruvian Amazon, Ae. aegypti geographic spread is driven by human transportation networks along rivers and highways. Our results suggest that urban development and oviposition site availability drive Ae. aegypti colonization along roads. Along rivers, boat traffic is likely to drive long-distance dispersal via unintentional transport of mosquitoes on boats. PMID:25101786

  16. Assessment of Multi-Mission Radar Altimeter Performance Over the Amazon Basin

    NASA Astrophysics Data System (ADS)

    Harrison, J.; Berry, P. A. M.; Freeman, J. A.

    2006-07-01

    As an aid to assessing the performance of past and current altimeters over inland water, a web based toolkit has been developed which compares time series of river heights over the Amazon basin from over 3000 gauge stations with those obtained using satellite radar altimetry. Using this tool, an assessment is presented of the altimeter time series, derived using an expert system approach, from ERS-2, Envisat and TOPEX.

  17. The spatial extent of change in tropical forest ecosystem services in the Amazon delta

    NASA Astrophysics Data System (ADS)

    de Araujo Barbosa, C. C.; Atkinson, P.; Dearing, J.

    2014-12-01

    Deltas hold major economic potential due their strategic location, close to seas and inland waterways, thereby supporting intense economic activity. The increasing pace of human development activities in coastal deltas over the past five decades has also strained environmental resources and produced extensive economic and sociocultural impacts. The Amazon delta is located in the Amazon Basin, North Brazil, the largest river basin on Earth and also one of the least understood. A considerable segment of the population living in the Amazon delta is directly dependent on the local extraction of natural resources for their livelihood. Areas sparsely inhabited may be exploited with few negative consequences for the environment. However, increasing pressure on ecosystem services is amplified by large fluxes of immigrants from other parts of the country, especially from the semi-arid zone in Northeast Brazil to the lowland forests of the Amazon delta. Here we present partial results from a bigger research project. Therefore, the focus will be on presenting an overview of the current state, and the extent of changes on forest related ecosystem services in the Amazon delta over the last three decades. We aggregated a multitude of datasets, from a variety of sources, for example, from satellite imagery such as the Advanced Very High Resolution Radiometer (AVHRR), the Global Inventory Modelling and Mapping Studies (GIMMS), the Moderate Resolution Imaging Spectroradiometer (MODIS), and climate datasets at meteorological station level from the Brazilian National Institute of Meteorology (INMET) and social and economic statistics data from the Brazilian Institute of Geography and Statistics (IBGE) and from the Brazilian Institute of Applied Economic Research (IPEA). Through analysis of socioeconomic and satellite earth observation data we were able to produce and present spatially-explicit information with the current state and transition in forest cover and its impacts to forest ecosystem services providing units in the Amazon delta.

  18. Assessing the Amazon Basin Circulation with Stable Water Isotopes

    NASA Astrophysics Data System (ADS)

    McGuffie, K.; Henderson-Sellers, A.

    2004-05-01

    The isotopic abundances of Oxygen-18 (δ 18O) and Deuterium (δ D) over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Tracking the two stable but rare isotopes of water (1HD16O and 1H218O) makes it possible to trace Amazonian regional evaporative and condensation processes. This offers isotopic constraints on regional to global-scale atmospheric moisture budgets. Based on data in the Global Network on Isotopes in Precipitation (GNIP) database, we analyse the simulation of the land surface hydrology and water cycling. Temporal changes between 1965 and 2000 in stable water isotopic signatures in the Amazon have been used to evaluate global climate model (GCM) predictions revealing notable anomalies. For example, the differences in the wet season deuterium excess between Belem and Manaus are consistent with recent GCM simulations only if there has been a relative increase in evaporation from non-fractionating water sources over this period. Despite earlier predictions that land-use change signals would be found, late twentieth century data reveal no significant change in dry season isotopic characteristics. On the other hand, more recent isotopic data do show trends at stations in the Andes, where as much as 88% of the rainfall is thought to be derived from recycled moisture. At Izobamba the wet season depletions are enhanced (greater depletion) and the dry season ones decreased (less depletion). At Bogota only the wet months show statistically significant changes - also an enhancement. More depletion in the wet months is consistent with reductions in non-fractioning recycling such as through transpiration and in full re-evaporation of canopy-intercepted rainfall. These data might be linked to deforestation impacts. Results of GCM and simpler model simulations of the Amazon suggest that the recent stable isotope record is consistent with the predicted effects of forest removal, perhaps combined with greenhouse warming. At a minimum, large-scale simulations of South American climate ought to be tested against these isotopic data in any validation effort. Specific caveats our conclusions include: (i)monthly isotope data only are available in GNIP and hence analysed; (ii) the statistically significant seasonal changes reported might be related to, or even exaggerated by, El Niño-Southern Oscillation (ENSO) events or other climatic variations that modify the Walker circulation and Inter-Tropical Convergence Zone (ITCZ) position and hence affect the moisture climatology of the Amazon; (iii)no information on fluxes from simulated open water as a surface type in the Amazon GCM experiments has been considered; (iv)the selected models are failing to correctly simulate the relative components of transpiration and re-evaporated canopy interception in the Amazon dry season; and (v) no isotope tracking in the Amazon deforestation simulations was reviewed, because none is yet available. These shortcomings deserve further work.

  19. Adjusting SRTM in the Amazon for Improving Hydrodynamic Floodplain Simulation

    NASA Astrophysics Data System (ADS)

    Baugh, C.; Bates, P. D.; Schumann, G.; Trigg, M.

    2012-12-01

    In this paper we investigate how random noise and absolute errors in the SRTM DEM of the Amazon floodplain can be adjusted to reduce their impact when this dataset is utilised in a hydrodynamic model of floodplain inundation and water levels. Such models are highly sensitive to the accuracy of DEMs used to represent the floodplain topography. In the Amazon the SRTM DEM is the only available topographic dataset, yet it is subject to errors, both random and absolute, which degrade its accuracy. In turn this has hindered previous efforts to understand Amazon floodplain inundation dynamics using hydrodynamic models. Recent observations from remotely sensed data have estimated the magnitude of SRTM random noise errors in the Amazon as well as vegetation height which is related to the absolute SRTM error magnitude. The aim in this paper therefore, is to investigate to what extent these remote sensing observations can be used to adjust the SRTM DEM in the Amazon floodplain to improve the accuracy of a hydrodynamic model of floodplain inundation and water levels. Random noise errors were smoothed using a fixed window averaging filter and experiments were conducted using different window sizes. Absolute errors resulting from the vegetation canopy were reduced using a vegetation height map created by NASA JPL from ICESat altimeter data. These vegetation heights were first adjusted to account for a mean uniform canopy radar penetration value and then subtracted from each of the smoothed DEMs. Experiments were conducted with a range of canopy penetration values from 0-100%. A hydrodynamic simulation was performed using the LISFLOOD-FP model with each of the adjusted DEMs. The results were compared to observations of inundation extent and water levels both in the river main stem and the floodplain. Results from the smoothing process yielded only a minimal accuracy improvement in high water flood extent prediction (up to 26% from an original value of 23%) with river main stem and floodplain water level accuracy remaining unchanged. Conversely, results from the vegetation height adjusted DEMs resulted in large improvements to the prediction of high water inundation extent with over 70% accuracy achieved when 30-50% canopy penetration values were used. These adjustments also improved the accuracy of floodplain water level prediction from an average RMSE of 6.61 m to 2.16 m. Additional improvements were sought by adjusting the vegetation heights based on landcover (obtained from the GlobCover dataset) dependent canopy penetration values but no additional model performance was achieved. Combining the results from these two experiments found that adjusting the SRTM for absolute errors related to vegetation height yielded the greatest improvement in predicting high water inundation flood extent and water levels. This paper will therefore present a method of adjusting the SRTM DEM in the Amazon which yields a large improvement in hydrodynamic model performance of high water flood inundation extent and water levels. Issues remain in the model performance at low water where poor drainage could be related to the lack of topographic features, such as floodplain channels, in the SRTM. This paper will conclude by outlining the investigatory experiments into these issues and will present their preliminary results.

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

    SciTech Connect

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

    1983-01-01

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

  1. Gamma irradiation-aided chitin/chitosan extraction from prawn shells

    NASA Astrophysics Data System (ADS)

    Mahlous, M.; Tahtat, D.; Benamer, S.; Nacer Khodja, A.

    2007-12-01

    Chitin and chitosan were extracted from prawn shells. The influence of a 25 kGy irradiation dose on the deproteination process was investigated. The deproteination degree was followed by Lowry-Folin method. The demineralisation degree versus reaction time with 1 N hydrochloric acid solution was followed by atomic absorption spectrometry. Chitin and chitosan obtained were characterised by FTIR spectrometry. The influence of some parameters, such as reaction time, alkaline concentration and temperature on the deacetylation degree was also investigated. The deacetylation degree was evaluated by FTIR spectrometry using the bands at 1320 cm -1 and 1420 cm -1. It was found that the irradiation of the shells at a dose of 25 kGy reduces the time of the deproteination reaction by a factor of three, comparatively to the non-irradiated samples.

  2. The complete mitogenome of the rock pool prawn Palaemon serenus (Heller, 1862) (Crustacea: Decapoda: Palaemonidae).

    PubMed

    Gan, Huan You; Gan, Han Ming; Lee, Yin Peng; Austin, Christopher M

    2016-09-01

    The mitochondrial genome of the rock pool prawn (Palaemon serenus), is sequenced, making it the third for genera of the family Palaemonidae and the first for the genus Palaemon. The mitogenome is 15,967 base pairs in length and comprises 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs and a non-coding AT-rich region. The P. serenus mitogenome has an AT bias of 58.97% and a base composition of 29.79% for T, 24.14% for C, 29.18% for A, and 16.89% for G. The mitogenome gene order of P. serenus is identical to Exopalaemon carinicauda. PMID:25693708

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

    PubMed Central

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

    2011-01-01

    Background Giant 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 Findings A collection of 787,731 sequence reads (244.37 Mb) obtained from 454 pyrosequencing analysis of cDNA prepared from muscle, ovary and testis tissues taken from 18 adult prawns was assembled into 123,534 expressed sequence tags (ESTs). Of these, 46% of the 8,411 contigs and 19% of 115,123 singletons possessed high similarity to sequences in the GenBank non-redundant database, with most significant (E value < 1e–5) contig (80%) and singleton (84%) matches occurring with crustacean and insect sequences. KEGG analysis of the contig open reading frames identified putative members of several biological pathways potentially important for growth. The top InterProScan domains detected included RNA recognition motifs, serine/threonine-protein kinase-like domains, actin-like families, and zinc finger domains. Transcripts derived from genes such as actin, myosin heavy and light chain, tropomyosin and troponin with fundamental roles in muscle development and construction were abundant. Amongst the contigs, 834 single nucleotide polymorphisms, 1198 indels and 658 simple sequence repeats motifs were also identified. Conclusions The M. rosenbergii transcriptome data reported here should provide an invaluable resource for improving our understanding of this species' genome structure and biology. The data will also instruct future functional studies to manipulate or select for genes influencing growth that should find practical applications in aquaculture breeding programs. PMID:22174756

  4. Low-level nocturnal wind maximum over the Central Amazon Basin

    NASA Technical Reports Server (NTRS)

    Greco, Steven; Ulanski, Stanley; Garstang, Michael; Houston, Samuel

    1992-01-01

    A low-level nocturnal wind maximum is shown to exist over extensive and nearly undisturbed rainforest near the central Amazon city of Manaus. Meteorological data indicate the presence of this nocturnal wind maximum during both the wet and dry seasons of the Central Amazon Basin. Daytime wind speeds which are characteristically 3-7 m/s between 300 and 1000 m increase to 10-15 m/s shortly after sunset. The wind-speed maximum is reached in the early evening, with wind speeds remaining high until several hours after sunrise. The nocturnal wind maximum is closely linked to a strong low-level inversion formed by radiational cooling of the rainforest canopy. Surface and low-level pressure gradients between the undisturbed forest and the large Amazon river system and the city of Manaus are shown to be responsible for much of the nocturnal wind increase. The pressure gradients are interpreted as a function of the thermal differences between undisturbed forest and the river/city. The importance of both the frictional decoupling and the horizontal pressure gradient suggest that the nocturnal wind maximum does not occur uniformly over all Amazonia. Low-level winds are thought to be pervasive under clear skies and strong surface cooling and that, in many places (i.e., near rivers), local pressure gradients enhance the low-level nocturnal winds.

  5. Trophic ecology of the freshwater prawn, Pseudopalaemon bouvieri (Decapoda: Palaemonidae) in Northeastern Argentina, with remarks on population structure.

    PubMed

    Carnevali, Romina Patricia; Collins, Pablo Agustín; Poi de Neiff, Alicia S Guadalupe

    2012-03-01

    Freshwater decapod crustaceans are important components of food webs in these environments, but little is known about the diet of species that live in tropical waters. We studied the feeding ecology of the prawn Pseudopalaemon bouvieri and its population structure in two different areas with six lagoons, with a different composition and abundance of aquatic macrophytes. At each site of macrophytes banks, 18 prawns sample was collected with a hand net (1mm mesh size) from 1m2. In the laboratory, prawns cephalothorax length was measured, sex determined, and a total of 208 stomachs were examined for food items. Our results showed that the population abundance varied between 10 ind/m2 and 1 411 ind/m2. The cephalothorax length ranged between 6mm and 21mm, and the male:female ratio varied between 0.3 and 1.0, with a higher proportion of ovigerous females (21%) in area one than area two. P. bouvieri is omnivorous, and its diet was principally based on algae, plant remains, Protozoa, Rotifera, Oligochaeta, Crustacea, Insecta, detritus and other items. The analysis of the stomach content did not reveal any significant difference in the diet between juveniles and adults, and males and females of both areas consumed a similar diet (Kruskal-Wallis test p=0.8273). We concluded that the dietary items consumed by prawns and the niche breadth were similar between the two areas, although the proportion of items consumed varied between lagoons of both areas. The density of P. bouvieri was different between areas, but the size of cephalothorax (CL) was similar. PMID:22458226

  6. Habitat Type Influences the Microhabitat Preference of Juvenile Tiger Prawns ( Penaeus esculentusHaswell and Penaeus semisulcatusDe Haan)

    NASA Astrophysics Data System (ADS)

    Kenyon, R. A.; Loneragan, N. R.; Hughes, J. M.; Staples, D. J.

    1997-09-01

    The microhabitat preferences of juvenile tiger prawns (3-10 mm carapace length),Penaeus esculentusandPenaeus semisulcatus, were tested in the field at Groote Eylandt, in the western Gulf of Carpentaria, Australia. A partitioned apparatus containing live seagrass was used. Both species of prawns selected seagrass (Syringodium isoetifolium) over bare substrate. JuvenileP. esculentus, the most abundant species in this region, were also given paired choices of seagrasses with different leaf morphologies (representing a range of structural complexity) and sediments of different particle size. They selected a seagrass with broad, long leaves (Cymodocea serrulata) over one with narrow, long leaves (S. isoetifolium), which in turn was selected over the seagrasses with narrow, short leaves (Halodule uninervisand shortenedS. isoetifolium). Predation experiments have shown that juvenileP. esculentusare detected and eaten less often in broad, long-leaved seagrass than in narrow, short-leaved seagrass or bare substrate, so their preference for the former may shelter them from predators. No habitat preference was evident forP. esculentuswhen offered a choice between sediments consisting mainly of sand (71% sand particles) and silt (60% of silt and clay). The selection by both species of tiger prawn of seagrass over bare substrate, andP. esculentus's selection of seagrass with long, broad leaves, provides an explanation for the distribution of juvenile tiger prawns in the field. Thus, in the seagrass beds around Groote Eylandt,P. esculentusis more abundant in seagrass with broad, long leaves than in seagrass with short, thin leaves. In addition, its distribution in this region is relatively independent of sediment type. Leaf surface area (or habitat structural complexity) appears to be the main determinant of distribution for juvenileP. esculentus.

  7. Identification and characterization of differentially expressed transcripts in the gills of freshwater prawn (Macrobrachium rosenbergii) under salt stress.

    PubMed

    Barman, Hirak Kumar; Patra, Swagat Kumar; Das, Varsha; Mohapatra, Shibani Dutta; Jayasankar, Pallipuram; Mohapatra, Chinmayee; Mohanta, Ramya; Panda, Rudra Prasanna; Rath, Surya Narayan

    2012-01-01

    The giant freshwater prawn, Macrobrachium rosenbergii, is an economically important species. It is a euryhaline shrimp, surviving in wide-range salinity conditions. A change in gene expression has been suggested as an important component for stress management. To better understand the osmoregulatory mechanisms mediated by the gill, a subtractive and suppressive hybridization (SSH) tool was used to identify expressed transcripts linked to adaptations in saline water. A total of 117 transcripts represented potentially expressed under salinity conditions. BLAST analysis identified 22% as known genes, 9% as uncharacterized showing homologous to unannotated ESTs, and 69% as unknown sequences. All the identified known genes representing broad spectrum of biological pathways were particularly linked to stress tolerance including salinity tolerance. Expression analysis of 10 known genes and 7 unknown/uncharacterized genes suggested their upregulation in the gills of prawn exposed to saline water as compared to control indicating that these are likely to be associated with salinity acclimation. Rapid amplification of cDNA ends (RACE) was used for obtaining full-length cDNA of MRSW-40 clone that was highly upregulated during salt exposure. The sequenced ESTs presented here will have potential implications for future understanding about salinity acclimation and/or tolerance of the prawn. PMID:22619594

  8. Effect of legume seed extracts on the inhibition of proteolytic activity and muscle degradation of fresh water prawn (Macrobrachiumrosenbergii).

    PubMed

    Sriket, Chodsana; Benjakul, Soottawat; Visessanguan, Wonnop; Hara, Kenji

    2011-12-01

    Trypsin inhibitors in the extracts from soybean (Glycine max), adzuki bean (Vigna angularis), bambara groundnut (Vigna subterranea) and red kidney bean (Phaseoulus vulgaris) varied in amount and molecular weight. The soybean extract had the highest level of trypsin inhibitor with molecular weight (MW) of 21kDa, followed by bambara groundnut extract possessing trypsin inhibitor with MW of 15kDa. Both extracts showed a more effective inhibition towards crude protease extract (CE) from the hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) than the extracts from adzuki and red kidney beans. Activity staining also reconfirmed the higher inhibitory activity on CE from hepatopancreas by the extracts from both soybean and bambara groundnut. The extracts from all seeds were able to inhibit the degradation of fresh water prawn meat containing CE in a concentration dependent manner. Based on inhibitor study, the extracts from soybean and bambara groundnut can be a potential aid to suppress the muscle softening of fresh water prawn, mediated by trypsin-like proteases released from hepatopancreas, during extended iced storage. PMID:25212342

  9. Identification and Characterization of Differentially Expressed Transcripts in the Gills of Freshwater Prawn (Macrobrachium rosenbergii) under Salt Stress

    PubMed Central

    Barman, Hirak Kumar; Patra, Swagat Kumar; Das, Varsha; Mohapatra, Shibani Dutta; Jayasankar, Pallipuram; Mohapatra, Chinmayee; Mohanta, Ramya; Panda, Rudra Prasanna; Rath, Surya Narayan

    2012-01-01

    The giant freshwater prawn, Macrobrachium rosenbergii, is an economically important species. It is a euryhaline shrimp, surviving in wide-range salinity conditions. A change in gene expression has been suggested as an important component for stress management. To better understand the osmoregulatory mechanisms mediated by the gill, a subtractive and suppressive hybridization (SSH) tool was used to identify expressed transcripts linked to adaptations in saline water. A total of 117 transcripts represented potentially expressed under salinity conditions. BLAST analysis identified 22% as known genes, 9% as uncharacterized showing homologous to unannotated ESTs, and 69% as unknown sequences. All the identified known genes representing broad spectrum of biological pathways were particularly linked to stress tolerance including salinity tolerance. Expression analysis of 10 known genes and 7 unknown/uncharacterized genes suggested their upregulation in the gills of prawn exposed to saline water as compared to control indicating that these are likely to be associated with salinity acclimation. Rapid amplification of cDNA ends (RACE) was used for obtaining full-length cDNA of MRSW-40 clone that was highly upregulated during salt exposure. The sequenced ESTs presented here will have potential implications for future understanding about salinity acclimation and/or tolerance of the prawn. PMID:22619594

  10. Spermatophore affects the egg-spawning and egg-carrying behavior in the female giant freshwater prawn, Macrobrachium rosenbergii.

    PubMed

    Kruangkum, Thanapong; Vanichviriyakit, Rapeepun; Chotwiwatthanakun, Charoonroj; Saetan, Jirawat; Tinikul, Yotsawan; Wanichanon, Chaitip; Cummins, Scott F; Hanna, Peter J; Sobhon, Prasert

    2015-10-01

    In crustaceans, mating occurs during the ecdysis after female molting. During this period, a male transfers its spermatophore into a female which, in some species, stores the spermatophore for a long period prior to spawning and fertilization. However, in some species including the giant freshwater prawn, Macrobrachium rosenbergii, the male deposits its spermataphore onto the external surface of the thoracic segment of the female which affects the spawning time and maternal behavior. This study investigated the spawning behavior of the M. rosenbergii females, which was divided into pre-spawning, spawning, and post-spawning phases. It was revealed that mated female prawns with attached spermatophore exhibited an earlier spawning than unmated individuals, leading to assessment of the factors that may elicit this phenomenon. Four groups of female prawns were allocated to groups including mating females with spermatophore still attached, mating females with the spermatophore removed, artificially inseminated females with spermatophores, and an unmated control. There was a significant reduction in the time of egg-spawning in the presence of spermatophores, and the mating activity was also a contributing factor. Furthermore, over 90% of the mated and artificially inseminated females in which spermatophores were deposited carried the eggs in the abdominal brood chamber until completion of embryonic development while others discarded the eggs within 2 days post-spawning. This study implies that the spermatophore may contain ovulation-inducing factors which stimulate an earlier spawning and fostering of brooding behavior. PMID:26388033

  11. A first insight into temperature stress-induced neuroendocrine and immunological changes in giant freshwater prawn, Macrobrachium rosenbergii.

    PubMed

    Chang, Chin-Chyuan; Jiang, Jia-Rong; Cheng, Winton

    2015-11-01

    Haemolymph norepinephrine (NE); total haemocyte count (THC); respiratory bursts (RBs); superoxide dismutase (SOD), phenoloxidase (PO), and phagocytic activity; and prophenoloxidase (proPO)-system-related genes (lipopolysaccharide- and β-1,3-glucan-binding protein: LGBP, proPO, peroxinectin: PE, and α2-macroglobulin: α2-M) in haemocytes of Macrobrachium rosenbergii were investigated after transferring them from 28 °C to 22 °C, 28 °C, and 34 °C respectively. The results revealed that haemolymph NE, hyaline cells (HCs), and PO activity per granulocyte increased from 30 to 120 min of exposure, and however, RBs and phagocytic activity significantly decreased from 30 to 120 min of exposure as well as granular cells (GCs), semigranular cells (SGCs), and SOD activity decreased from 60 to 120 min of exposure for the prawns subjected to temperature stress. The proPO-system-related gene expression markedly increased with 60-120 min of exposure for the prawns transferred from 28 °C to 22 °C and 34 °C, except α2M at 120 min. These results provide a first insight into the effects of temperature stress on haemolymph NE level and immune functions in prawns and suggest that temperature-stress-induced acute modulation in immunity is associated with the release of haemolymph NE in M. rosenbergii. PMID:26434711

  12. Towards a better characterization of the groundwater stocks in Central Amazon using a combination of satellite data

    NASA Astrophysics Data System (ADS)

    Pfeffer, J.; Seyler, F.; Bonnet, M.; Calmant, S.; Frappart, F.; Papa, F.; Paiva, R. C.; Satgé, F.

    2012-12-01

    With the diversification of remote sensing techniques, our ability to monitor the various component of the water balance over large river basins has been greatly improved. The Gravity Recovery And Climate Experiment (GRACE) mission provided integrated hydrological information about the entire soil column, comprising surface water, soil moisture and groundwater; altimeter on board of satellite platforms such as JASON or ENVISAT enabled to determine the water level height in rivers or lakes; and multisatellite imagery methods, using microwave, visible and infrared observations were developed to estimate monthly inundation extent at global scale. The main goal of this study is to merge multidisciplinary satellite observations to better represent the water balance across the Amazon River system. Special emphasis is placed on groundwater reserves. Changes in the water stored in the alluvial aquifer were isolated from GRACE data using a combination of satellite imagery and altimetry to determine the surface reservoir contribution and hydrological models to solve the soil water balance. Water level measurements derived from altimetry and in situ hydrological networks provided information about the water table level beneath the Amazon River, lakes and tributaries in low water periods. The combination of such in - situ and satellite observations helped to represent the groundwater table fluctuations across the Amazon River System with spatial and temporal resolutions of a few hundreds of kilometers and 1 month respectively.

  13. Dependence of hydropower energy generation on forests in the Amazon Basin at local and regional scales.

    PubMed

    Stickler, Claudia M; Coe, Michael T; Costa, Marcos H; Nepstad, Daniel C; McGrath, David G; Dias, Livia C P; Rodrigues, Hermann O; Soares-Filho, Britaldo S

    2013-06-01

    Tropical rainforest regions have large hydropower generation potential that figures prominently in many nations' energy growth strategies. Feasibility studies of hydropower plants typically ignore the effect of future deforestation or assume that deforestation will have a positive effect on river discharge and energy generation resulting from declines in evapotranspiration (ET) associated with forest conversion. Forest loss can also reduce river discharge, however, by inhibiting rainfall. We used land use, hydrological, and climate models to examine the local "direct" effects (through changes in ET within the watershed) and the potential regional "indirect" effects (through changes in rainfall) of deforestation on river discharge and energy generation potential for the Belo Monte energy complex, one of the world's largest hydropower plants that is currently under construction on the Xingu River in the eastern Amazon. In the absence of indirect effects of deforestation, simulated deforestation of 20% and 40% within the Xingu River basin increased discharge by 4-8% and 10-12%, with similar increases in energy generation. When indirect effects were considered, deforestation of the Amazon region inhibited rainfall within the Xingu Basin, counterbalancing declines in ET and decreasing discharge by 6-36%. Under business-as-usual projections of forest loss for 2050 (40%), simulated power generation declined to only 25% of maximum plant output and 60% of the industry's own projections. Like other energy sources, hydropower plants present large social and environmental costs. Their reliability as energy sources, however, must take into account their dependence on forests. PMID:23671098

  14. Impacts of trawling on benthic macro-fauna and -flora of the Spencer Gulf prawn fishing grounds

    NASA Astrophysics Data System (ADS)

    Svane, Ib; Hammett, Zoe; Lauer, Peter

    2009-05-01

    The overall effects of trawling on benthic habitats and their assemblages are dependent on the distribution and intensity of trawl effort. The benthic habitats of the Spencer Gulf prawn trawling grounds are subjected to known variable levels of trawling disturbance recorded from fisher's logbooks. These habitats have not been quantitatively investigated. The aim of the study was firstly to characterise the macro-faunal and -floral assemblages and secondly, to comparatively assess trawl impact by testing the null hypothesis of no differences between five sites exposed to different intensity of trawl effort. The distribution and abundance of benthic macro-fauna and -flora were studied at two sampling resolutions by using beam trawl sampling (˜10,000 m 2) and underwater stereophotography (˜4.5 m 2) at five sites with different levels of trawl disturbance (effort). The results showed that the Spencer Gulf prawn trawling grounds are characterised by sandy sediments with a low content of silt and clay, with the exception of one site with very fine gravel. Biomass, abundance and cover of macro-fauna and -flora were generally low throughout, but with large differences among sites. Biomass, abundance and cover were found to be negatively correlated to both trawl hours from 1994-1998 and during the period of study. ANOSIM and SIMPER analyses using biomass, abundance and percentage cover as variables showed significant differences between sites with eight species or taxonomic groups contributing more than 10% to the observed similarity within sites. The two northern sites were dominated by sponges and the bearded mussel, Trichomya hirsutus, and the southern hammer oyster, Malleus meridianus. Other species that contributed to the similarity within sites were the ascidian, Polycarpa viridis, mobile epifauna (the blue swimmer crab, Portunus pelagicus, and the western king prawn, Penaeus (Melicertus) latisulcatus) and demersal fish species (Degens leatherjacket, Thamnaconus degeni, and the Melbourne silver belly, Parequula melbournensis). Simpson's Index of Diversity (1 - λ) and species richness in the beam trawl samples were fairly even across all sites, but a significant effect of site was found in the stereophotographic transect samples. It was concluded that prawn trawling has a strong influence on the structure of the benthic habitats of the Spencer Gulf prawn fishing grounds highlighted by the magnitude of change and the strength of the gradient of effects. Confounding factors linked to the biophysical attributes of the sites are believed to be minor.

  15. Hydrological Controls on Macrophyte Productivity in the Amazon Floodplain Wetlands

    NASA Astrophysics Data System (ADS)

    Silva, T. S.; Novo, E. M.; Melack, J. M.

    2013-05-01

    The Amazon River floodplain is an important source of atmospheric CO2 and CH4, but the relative contribution of allochthonous and autochthonous sources to floodplain emissions is still uncertain. Macrophytes comprise an important carbon source, growing during both low and high water conditions, and averaging 5,000 g.m-2.yr-1 in dry weight. The controls exerted by the annual flooding on macrophyte productivity result from two opposing mechanisms: the "horizontal expansion" of plant stands during low water levels and the stem elongation ("vertical growth") promoted by rising water levels. As studies suggest more frequent and intense droughts for the Amazon, determining how these mechanisms interact to control macrophyte net primary productivity (NPP) can lead to a better understanding of the effects of extreme hydrological conditions on autochthonous carbon fixation in the Amazon floodplain. Our study combines remote sensing estimates of macrophyte cover, in situ measurements of macrophyte biomass, historical water level records, and statistical modeling and simulation to answer 1) how plant horizontal expansion and vertical growth respond to inter-annual flooding variability, 2) how these responses modulate annual NPP, and 3) how climatic changes will affect the contribution of macrophytes to the carbon budget of the Amazon floodplain. Biomass data was collected along a stretch of the Lower Amazon Floodplain, at monthly intervals in 2004, and a time series of Radarsat-1 and EOS-MODIS images was acquired for the same area for the 2003-2005 period. Daily river stage data was acquired from the Brazilian National Water Agency (ANA) for the Óbidos station, covering the 1970 - 2011 period. Macrophyte cover was estimated for each available image in the series, using a multitemporal object-based image analysis algorithm. Empirical regression models were used to model the relationship between flood levels and both plant biomass and cover area, and combined into a semi-empirical growth model. Annual NPP was then predicted from daily biomass increments, spanning the 42-year hydrological data record. Resulting macrophyte cover maps had overall accuracies between 60% and 90%, and macrophyte cover area increased fourfold between high and low water seasons. Simulated NPP had marked variability, ranging from 1.06 (0.68, 1.70) Tg C yr-1 in 1980 to 1.63 (1.03, 2.63) Tg C yr-1 in 2009 for the entire mapped area.Values between parentheses show the 95% prediciton limits. Vertical growth was sensitive to extreme floods, but not to severe droughts, while horizontal expansion was affected by both extremely low and high water levels. The simulation revealed a complex pattern of interaction between the two components, indicating that extreme floods may result in larger increases in carbon fixation than extreme droughts. However, the results also suggested that overall flooding amplitude was positively correlated with simulated NPP values (r = 0.63, p > 0.001). An increasing trend in flood amplitude was observed in the hydrological record, which led to a small increase in annual NPP , of approximately 0.0008 TgC.yr-1 for the entire study region.

  16. Use of GNSS data for Hydrology: Applications of the method PPP (Precise Point Positioning) with integer ambiguities fixing for hydrological studies in the Amazon basin

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Applications of GNSS data is constantly being used in hydrology. One of the key applications is the characterization of river's longitudinal profiles, an information 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 the present work we use the Gins-PC software developed at CNES / GRGS. We discuss the capability of the PPP kinematic with integer ambiguities fixing strategy implemented in GINS-PC in processing GPS 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/Solimes river. For this purpose, field campaings were conducted between 2005 and 2010 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. Under the proposed framework, these 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. The profiles will be also used to levelling some gauge stations in Amazon Basin and gauge data will be used to obtain a temporal variation of these profiles. However some gauges are strongly affected by charge effects, mainly caused by the hydrological cycle of the Amazon basin. These effects can produce a variation of about 10 cm in amplitude of vertical coordinates also obtained by GPS. Therefore, we use GRACE data to convert the hydrologic load into crustal displacements to remove these effects.

  17. The IgE and IgG antibody responses to aerosols of Nephrops norvegicus (prawn) antigens: the association with clinical hypersensitivity and with cigarette smoking.

    PubMed Central

    McSharry, C; Anderson, K; McKay, I C; Colloff, M J; Feyerabend, C; Wilson, R B; Wilkinson, P C

    1994-01-01

    Raised levels of serum IgE antibodies to prawn antigens were found in 15 of 26 seafood factory process workers with respiratory symptoms and in one of 26 case-matched asymptomatic controls (P < 0.001). Raised IgG antibody titres against the same antigens were found in 18 subjects in each symptom grouping, and the median titres of this antibody did not differ significantly between the groups. The prawn-specific IgE antibody response was significantly associated with atopy (IgE antibody response to common allergens) and with a history of cigarette smoking, confirmed by level of serum cotinine, a major nicotine metabolite. Non-atopic non-smokers were unlikely to become sensitized. The titre of the prawn-specific IgE antibody correlated with the duration of exposure and with the duration of symptoms. Discriminant analysis of the serological profile (anti-prawn IgE, total IgE and cotinine) was sufficient to assign individuals correctly into symptomatic or asymptomatic categories in 77% of subjects. The titres of the IgE and IgG antibody responses to prawn antigens did not correlate, and the main factor which seemed to determine the antibody isotype response to these inhaled antigens was cigarette smoking. IgE antibody was produced mainly by smokers, whereas IgG antibody was the predominant isotype produced by non-smokers. PMID:8082306

  18. Proteomic analysis of differentially expressed protein in hemocytes of wild giant freshwater prawn Macrobrachium rosenbergii infected with infectious hypodermal and hematopoietic necrosis virus (IHHNV).

    PubMed

    Alinejad, T; Bin, Kwong Q; Vejayan, J; Othman, R Y; Bhassu, S

    2015-09-01

    Epizootic diseases cause huge mortality and economical loses at post larvae stages in freshwater prawn aquaculture industry. These prawns seem less susceptible to viral diseases except for infectious hypodermal and hematopoietic necrosis virus (IHHNV). During viral infection in prawns, hemocytes are the primary organ that shows immunological response within the early stages of infection. We applied proteomic approaches to understand differential expression of the proteins in hemocytes during the viral disease outbreak. To aid the goal, we collected Macrobrachium rosenbergii broodstocks from the local grow out hatchery which reported the first incidence of IHHNV viral outbreak during larvae stage. Primarily, application of the OIE primer targeting 389 bp fragments of IHHNV virus was used in identification of the infected and non-infected samples of the prawn breeding line. Analysis of two-dimensional gel electrophoresis showed specific down-regulation of Arginine kinase and Sarcoplasmic calcium-binding protein and up/down-regulation of Prophenoloxidase1 and hemocyanin isoforms. These proteins were validated using semi quantitative RT-PCR and gene transcripts at mRNA level. These identified proteins can be used as biomarkers, providing a powerful approach to better understanding of the immunity pathway of viral disease with applications in analytic and observational epidemiology diagnosis. Proteomic profiling allows deep insight into the pathogenesis of IHHNV molecular regulation and mechanism of hemocyte in freshwater prawns. PMID:26106581

  19. Proteomic analysis of differentially expressed protein in hemocytes of wild giant freshwater prawn Macrobrachium rosenbergii infected with infectious hypodermal and hematopoietic necrosis virus (IHHNV)

    PubMed Central

    Alinejad, T.; Bin, Kwong Q.; Vejayan, J.; Othman, R.Y.; Bhassu, S.

    2015-01-01

    Epizootic diseases cause huge mortality and economical loses at post larvae stages in freshwater prawn aquaculture industry. These prawns seem less susceptible to viral diseases except for infectious hypodermal and hematopoietic necrosis virus (IHHNV). During viral infection in prawns, hemocytes are the primary organ that shows immunological response within the early stages of infection. We applied proteomic approaches to understand differential expression of the proteins in hemocytes during the viral disease outbreak. To aid the goal, we collected Macrobrachium rosenbergii broodstocks from the local grow out hatchery which reported the first incidence of IHHNV viral outbreak during larvae stage. Primarily, application of the OIE primer targeting 389 bp fragments of IHHNV virus was used in identification of the infected and non-infected samples of the prawn breeding line. Analysis of two-dimensional gel electrophoresis showed specific down-regulation of Arginine kinase and Sarcoplasmic calcium-binding protein and up/down-regulation of Prophenoloxidase1 and hemocyanin isoforms. These proteins were validated using semi quantitative RT-PCR and gene transcripts at mRNA level. These identified proteins can be used as biomarkers, providing a powerful approach to better understanding of the immunity pathway of viral disease with applications in analytic and observational epidemiology diagnosis. Proteomic profiling allows deep insight into the pathogenesis of IHHNV molecular regulation and mechanism of hemocyte in freshwater prawns. PMID:26106581

  20. Methane Emission from Tropical Rivers

    NASA Astrophysics Data System (ADS)

    Sawakuchi, H. O.; Rasera, M. F. F. L.; Krusche, A. V.; Ballester, M. V. R.

    2012-04-01

    Inland water is already known as an important source of methane to atmosphere. Methane is produced in anaerobic environments usually find in lakes and floodplain bottom sediment. It is the main reason that almost all information regarding methane flux come from this environments. However, while floodplain dries during low water season reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present preliminary results of CH4 flux measurements done in 6 large tropical rivers within the Amazon basin. We measured 17 areas using floating chamber during dry (low water) season, between September and November of 2011, in Amazon river mainstem, Araguaia, Xingu, Tapajós, Madeira, and Negro Rivers. Measured fluxes of all rivers ranged from 59.3 to 2974.4 mmol m-2 yr-1. Geomorphologic structure of channels is one important factor that contributes to this high heterogeneity due to development of low flow velocity depositional settings allowing formation of anoxic zones in rivers. Hydraulic and sediment barriers in the confluence of river channels promote the generation of natural dams which function as a trap for the suspension load favoring the deposition of organic rich muds. This kind of environment is very different from common river channels and has a stronger potential of methane emission. Average values of our flux measurements for this two river environments show that depositional areas can have much higher fluxes than the main channel, 1089.6 and 163.1 mmol m-2 yr-1, respectively. Hence, CH4 flux from these depositional zones is similar to some tropical floodplain lakes and reservoirs. Although the low flux from channel, the area covered by water is very large resulting in a significant contribution to the regional methane emission to the atmosphere. Moreover, mapping the area of these depositional river zones will give us a better idea of the magnitude of methane flux from tropical rivers.

  1. Fishing effort and catch composition of urban market and rural villages in Brazilian Amazon.

    PubMed

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

    2011-02-01

    The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions. PMID:21153639

  2. The legacy of cultural landscapes in the Brazilian Amazon: implications for biodiversity.

    PubMed

    Heckenberger, Michael J; Russell, J Christian; Toney, Joshua R; Schmidt, Morgan J

    2007-02-28

    For centuries Amazonia has held the Western scientific and popular imagination as a primordial forest, only minimally impacted by small, simple and dispersed groups that inhabit the region. Studies in historical ecology refute this view. Rather than pristine tropical forest, some areas are better viewed as constructed or 'domesticated' landscapes, dramatically altered by indigenous groups in the past. This paper reviews recent archaeological research in several areas along the Amazon River with evidence of large pre-European (ca 400-500 calendar years before the present) occupations and large-scale transformations of forest and wetland environments. Research from the southern margins of closed tropical forest, in the headwaters of the Xingu River, are highlighted as an example of constructed nature in the Amazon. In all cases, human influences dramatically altered the distribution, frequency and configurations of biological communities and ecological settings. Findings of historical change and cultural variability, including diverse small to medium-sized complex societies, have clear implications for questions of conservation and sustainability and, specifically, what constitutes 'hotspots' of bio-historical diversity in the Amazon region. PMID:17255029

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

  4. ERS-ENVISAT radar altimetry over the Amazon basin

    NASA Astrophysics Data System (ADS)

    Santos da Silva, J.; Calmant, S.; Rotunno Filho, O. C.; Seyler, F.; Mansur, W. J.; Cochonneau, G.

    2009-12-01

    Since the launch of satellite embarking radar altimeters in the late 80’s, scientists have investigated the feasibility of using these ocean-dedicated data over the continental waters. In fact, satellite radar altimetry is being recognized as a powerful tool to obtain time series of water stage consistent to those obtained by conventional in situ gauge stations. In addition, this technology has been proved to provide reliable information about the dynamics of large water bodies such as lakes and inner seas. However, the results should be deeply examined as we shift the analysis to water levels acquired during satellite crosses over rivers. Yet, hydrologists are still reluctant in using these data, as neither the neces¬sary time sampling nor accuracy is achieved, leading to endless debates in specialized workshops. Noteworthy to highlight, few published studies are dedicated to an in depth assessment of the radar altimetry over rivers, in¬cluding comparisons with water levels at fluviometric gauges. In this work, we present an extensive analysis of the quality of times series of river stages that we have constructed in the Amazon basin for a variety of water bodies such as large rivers, narrow stems, lakes and flooded areas using radar altimeters embarked on¬board ERS-2 and ENVISAT. The approach includes the sensitivity to the raw data processing methodology such as the tracking algorithm, the data selection at the crossings between satellite track and river bed (so-called virtual stations) and correction for off-nadir effects. The VALS toolbox was developed to process altimetry data at virtual stations under the framework of this study. Results of internal validation at cross-overs and external validation by comparison with in situ gauges are presented.

  5. Indications of regional scale groundwater flows in the Amazon Basins: Inferences from results of geothermal studies

    NASA Astrophysics Data System (ADS)

    Pimentel, Elizabeth T.; Hamza, Valiya M.

    2012-08-01

    The present work deals with determination groundwater flows in the Amazon region, based on analysis of geothermal data acquired in shallow and deep wells. The method employed is based on the model of simultaneous heat transfer by conduction and advection in permeable media. Analysis of temperature data acquired in water wells indicates down flows of groundwaters with velocities in excess of 10-7 m/s at depths less than 300 m in the Amazonas basin. Bottom-hole temperature (BHT) data sets have been used in determining characteristics of fluid movements at larger depths in the basins of Acre, Solimões, Amazonas, Marajó and Barreirinhas. The results of model simulations point to down flow of groundwaters with velocities of the order of 10-8 to 10-9 m/s, at depths of up to 4000 m. No evidence has been found for up flow typical of discharge zones. The general conclusion compatible with such results is that large-scale groundwater recharge systems operate at both shallow and deep levels in all sedimentary basins of the Amazon region. However, the basement rock formations of the Amazon region are relatively impermeable and hence extensive down flow systems through the sedimentary strata are possible only in the presence of generalized lateral movement of groundwater in the basal parts of the sedimentary basins. The direction of this lateral flow, inferred from the basement topography and geological characteristics of the region, is from west to east, following roughly the course of surface drainage system of the Amazon River, with eventual discharge into the Atlantic Ocean. The estimated flow rate at the continental margin is 3287 m3/s, with velocities of the order of 218 m/year. It is possible that dynamic changes in the fluvial systems in the western parts of South American continent have been responsible for triggering alterations in the groundwater recharge systems and deep seated lateral flows in the Amazon region.

  6. Relating river discharges to salinity changes

    NASA Astrophysics Data System (ADS)

    Xie, X.; Liu, W. T.

    2014-12-01

    New river discharge data are brought together with spacebased sea surface salinity measurements by Aquarius and SMOS to demonstrate the role of river discharge in salinity changes near three river mouths: the Mississippi, the Ganges, and the Amazon. The characteristics of the seasonal cycle and the year-to-year changes of the river runoff are described. Various versions of the satellite salinity data are compared. The relative roles of river discharge, surface water flux, and horizontal advection in changing surface salinity in regions near the river mouths are examined. Satellite measurements of SSS clearly track movements of the fresh water from river discharges. Besides the river discharge, E-P plays an important role in the seasonal salinity variation near the Ganges and Irrawaddy River mouths. For the Mississippi and Amazon river mouths, central and eastern ITCZ, E-P contributes very little to the salinity seasonal change. In the central and eastern ITCZ, contribution of advection to the salinity tendency is clearly identified. Both salinity and salinity tendency are dominated by semi-annual cycle in the Atlantic ITCZ between 5ºN to 9ºN, whereas annual cycle dominates at other latitudes.

  7. Business as Usual: Amazon.com and the Academic Library

    ERIC Educational Resources Information Center

    Van Ullen, Mary K.; Germain, Carol Anne

    2002-01-01

    In 1999, Steve Coffman proposed that libraries form a single interlibrary loan based entity patterned after Amazon.com. This study examined the suitability of Amazon.com's Web interface and record enhancements for academic libraries. Amazon.com could not deliver circulating monographs in the University at Albany Libraries' collection quickly…

  8. New species of Gieysztoria (Platyhelminthes, Rhabdocoela) from Peruvian Amazon floodplain with description of their stylet ultrastructure.

    PubMed

    Damborenea, Cristina; Brusa, Francisco; Noreña, Carolina

    2005-12-01

    The free-living Platyhelminthes of the Amazon basin are poorly known. Presently only four turbellarian species have been mentioned from the Amazon river, a fact that confirms the lack of information on this kind of faunas in this huge basin. Three new species of Gieysztoria from Amazonian floodplain in Peru are described herein: G. chiqchi n. sp., G. kasasapa n. sp. and G. sasa n. sp. The samples were taken in the Pacaya-Samiria National Reserve (Peru) during September 2002. Besides the usual description of the stylet based on whole mounted specimens, we provide a complementary description using SEM, which allowed differentiation of the new species within the currently yet imperfect picture of the Amazonian turbellarian fauna. Although further research is desired, current findings are suggestive of high diversity of free-living Turbellaria in the surveyed region. PMID:16462104

  9. Ecology and seasonal variation of parasites in wild Aequidens tetramerus, a Cichlidae from the Amazon.

    PubMed

    Tavares-Dias, Marcos; Oliveira, Marcos Sidney Brito; Gonçalves, Raissa Alves; Silva, Luis Maurício Abdon

    2014-03-01

    This study is the first investigation on seasonal dynamics of parasites component community of the Aequidens tetramerus from an Amazon River tributary, in Northern Brazil. A total of 239,2407 parasites were recovered from 92 hosts examined from February to October 2011. Such parasites included Ichthyophthirius multifiliis, Tripartiella tetramerii and Trichodina nobilis (Protozoa), Dolops longicauda (Argulidae), Gussevia alioides, Gussevia disparoides (Monogenoidea), Digenea metacercarie, Pseudoproleptus larvae, Anisakidae larvae (Nematoda), Proteocephalidea plerocercoid (Eucestoda) and Gorytocephalus spectabilis (Acanthocephala). Ciliates were the most dominant and abundant taxon, while cestodes were the least prevalent. The parasites showed seasonal variation in their infection dynamics associated with environmental changes during the Amazonian drainage season, except the infection with I. multifiliis. The parasites community in A. tetramerus was also characterized by higher diversity, species richness and uniformity during the drainage season when compared to Amazon flood season. With the exception of T. tetramerii, these parasite species are new records for A. tetramerus. PMID:24570063

  10. [Historical review of the distribution of Anopheles (Nyssorhynchus) darlingi (Diptera: Culicidae) in the Peruvian Amazon].

    PubMed

    Fernández, Roberto; Vera, Hubert; Calderón, Guillermo

    2014-04-01

    Anopheles (Nyssorhynchus) darlingi has been reported since 1931 in border areas of the department of Loreto, mainly along the borders with Brazil and Colombia. In 1994, during an outbreak of malaria, An. darlingi was found in neighboring towns to Iquitos. At present, its distribution has expanded considerably in Loreto. This paper reviews literature available for all possible information on the distribution of mosquitoes, particularly anopheline in the Amazon region of the country, with special emphasis on An darlingi. Entomological collections were also conducted in the departments of Madre de Dios and Ucayali in order to know and verify the distribution of An. darlingi. At present, the distribution of the species is confined to localities in southeastern Peru with Bolivia border towns, in a town near the Abujao River in the department of Ucayali, and widely in the northeastern region of the Amazon basin of Loreto in Peru. PMID:25123872

  11. Pre-Columbian Urbanism, Anthropogenic Landscapes, and the Future of the Amazon

    NASA Astrophysics Data System (ADS)

    Heckenberger, Michael J.; Russell, J. Christian; Fausto, Carlos; Toney, Joshua R.; Schmidt, Morgan J.; Pereira, Edithe; Franchetto, Bruna; Kuikuro, Afukaka

    2008-08-01

    The archaeology of pre-Columbian polities in the Amazon River basin forces a reconsideration of early urbanism and long-term change in tropical forest landscapes. We describe settlement and land-use patterns of complex societies on the eve of European contact (after 1492) in the Upper Xingu region of the Brazilian Amazon. These societies were organized in articulated clusters, representing small independent polities, within a regional peer polity. These patterns constitute a “galactic” form of prehistoric urbanism, sharing features with small-scale urban polities in other areas. Understanding long-term change in coupled human-environment systems relating to these societies has implications for conservation and sustainable development, notably to control ecological degradation and maintain regional biodiversity.

  12. Pre-Columbian urbanism, anthropogenic landscapes, and the future of the Amazon.

    PubMed

    Heckenberger, Michael J; Russell, J Christian; Fausto, Carlos; Toney, Joshua R; Schmidt, Morgan J; Pereira, Edithe; Franchetto, Bruna; Kuikuro, Afukaka

    2008-08-29

    The archaeology of pre-Columbian polities in the Amazon River basin forces a reconsideration of early urbanism and long-term change in tropical forest landscapes. We describe settlement and land-use patterns of complex societies on the eve of European contact (after 1492) in the Upper Xingu region of the Brazilian Amazon. These societies were organized in articulated clusters, representing small independent polities, within a regional peer polity. These patterns constitute a "galactic" form of prehistoric urbanism, sharing features with small-scale urban polities in other areas. Understanding long-term change in coupled human-environment systems relating to these societies has implications for conservation and sustainable development, notably to control ecological degradation and maintain regional biodiversity. PMID:18755979

  13. Streamflow data assimilation into a large scale hydrologic-hydrodynamic model in the Amazon

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Recent extreme events in the Amazon River basin and the strong dependence of local population to water resources bring the need of hydrological forecast systems in this region. Due to the size of the Amazon and its large flood wave travel times, uncertainty on model initial conditions (ICs) may play an important role for discharge forecasts using large scale hydrological models, even for large lead times (~ 1 to 3 months). In this direction, data assimilation (DA) methods may provide an interesting way of merging different types of observations with models to estimate optimal ICs. We present results from first experiments on streamflow data assimilation into a large scale hydrologic and hydrodynamic model of the Amazon River basin. We use the conceptual and physically based MGB-IPH model. It uses the Penman Monteith for evapotranspiration and the Moore and Clarke model for soil water storage. River dynamics is simulated using full Saint-Venant equations and a simple floodplain storage model. We implemented a DA scheme based on the Ensemble Kalman Filter (EnKF) to assimilate daily discharge from in situ gauge stations. All model state variables were updated at each analyses time step. Model state variables errors were generated by perturbing precipitation forcing field from original value, using log-normally distributed, time and spatially correlated errors fields. Streamflow observation errors were modelled considering spatial and temporal uncorrelated normally distributed errors. Since the hydrodynamic model is vulnerable to large corrections, which may lead to model instability, we use a combination of two approaches to avoid the divergence of the DA scheme. First, if the solution of a given ensemble member diverges we substitute it by another member sampled from the ensemble. Then, to avoid lots of ensemble members to diverge, we use what we call an inertia approach, where the final analyses solution is the weighted combination of the analyzed and forecasted state variables using a time variable weight. In this first experiment, we considered that standard deviation of stream flow errors is 2%, we used an ensemble with 200 members and simulations were conducted during the 1998 (spin-up), 1999 and 2000 years. We assimilated discharge data from 14 stations located in the main rivers and used other 104 stations for validation. Agreement between model and observations increase in main Amazon Rivers when compared with simple model simulations. For example, in a validation site at Amazon River, Nash and Suttcliffe index increases from 0.77 to 0.97 and root mean square error (RMS) decreases 67%. RMS values generally decrease at gauges located at the large Amazon tributaries and close to gauges used in the DA scheme. On the other hand, we observed an increase of errors in smaller tributaries. Finally, future improvements of this DA scheme include the investigation of the source of errors in small rivers, assimilation of remotely sensed observations such as river water levels derived from satellite altimetry data and its evaluation for streamflow forecasts.

  14. Influence of El Nino and ITCZ on Brazilian River Streamflows

    NASA Astrophysics Data System (ADS)

    Lopes, A.; Dracup, J. A.

    2010-12-01

    This study analyzes effects of climatic phenomena El Nino and ITCZ latitudinal movements on streamflow patterns in major Brazilian river basins: Amazon (north), Araguaia-Tocantins (central-north), Parana (central-south) and Sao Francisco (central-northeast). Multiple correlation between annual streamflows and the NINO 3.4 and North Tropical Atlantic SST indexes (NTA) were analyzed for each river basin using different annual periods in order to account for the delay in streamflow response. The data consists of unimpaired river discharge time series at key points (from the Brazilian National Water Agency (ANA)); normalized yearly averaged NINO3.4 index characterizing El Nino (from NOAA); and NTA index (from NOAA), as a surrogate of the latitudinal movement of the ITCZ, since it is correlated to the Atlantic SST gradient. As a result, each river basin showed a different response. At the Amazon river basin, almost all dry years occurred when NINO3.4 was above average (El Nino years). Moreover, in almost every year when NINO3.4 was below average (La Nina) the streamflows were above average. Thus, it seems that La Nina have strong effects in floods in Amazon river. Moreover, El Nino events seem to be a necessary, but not sufficient condition for low streamflows at Amazon river. A weaker relationship was found for Xingu river basin, since it is probably affected by cold fronts from the south. As the location of river basins changes towards the south, the effect of El Nino events gets weaker as for Araguaia-Tocantins and Sao Francisco river basins. At the Parana river basin, the relationship is reversed. Almost all extreme wet years occurred during El Nino years. The correlation between streamflows and the NTA indexes were very weak for all river basins except for the Amazon. When the NTA anomaly is negative, wet years occurs, since the ITCZ moves southwards and stays longer at that position, increasing rainfall over the Amazon and Northeast of Brazil. In contrast, almost all dry years occurred when the NTA index was positive. Annual streamflows were regressed on climatic indexes NINO 3.4 and NTA. At 95% level of significance, NINO3.4 and NTA indexes are significant variables in predicting streamflows at the Amazon (p=0.01% for NINO3.4 and p=0.30% for NTA) and at the Parana river basins (p=0.23% for NINO3.4 and p=1.11% for NTA). The values of R2 were significant high, 0.59 for Amazon and 0.26 for Parana, compared to very low values for Xingu (0.10), Araguaia-Tocantins (0.06) and Sao Francisco (0.04) river basins. The low correlation at central basins can be explained from the regression coefficients values. The coefficients for NTA index are all negative (except for Xingu river), indicating that negative NTA implies in greater streamflow and vice-versa. However, coefficients for NINO3.4 are negative at the Amazon and positive at Parana which means that negative anomalies (La Nina years) implies in greater streamflows at Amazon and lower streamflows at Parana and vice-versa. Opposite effects of El Nino/La Nina on north and south river basins seems to be neutralized in the central river basins so the correlation gets weaker: during El Nino (La Nina) events, the reduction (increasing) in rainfall at north is counter balanced by the enhancement (reduction) of rainfall at south associated with cold fronts.

  15. Modelling conservation in the Amazon basin.

    PubMed

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

    2006-03-23

    Expansion of the cattle and soy industries in the Amazon basin has increased deforestation rates and will soon push all-weather highways into the region's core. In the face of this growing pressure, a comprehensive conservation strategy for the Amazon basin should protect its watersheds, the full range of species and ecosystem diversity, and the stability of regional climates. Here we report that protected areas in the Amazon basin--the central feature of prevailing conservation approaches--are an important but insufficient component of this strategy, based on policy-sensitive simulations of future deforestation. By 2050, current trends in agricultural expansion will eliminate a total of 40% of Amazon forests, including at least two-thirds of the forest cover of six major watersheds and 12 ecoregions, releasing 32 +/- 8 Pg of carbon to the atmosphere. One-quarter of the 382 mammalian species examined will lose more than 40% of the forest within their Amazon ranges. Although an expanded and enforced network of protected areas could avoid as much as one-third of this projected forest loss, conservation on private lands is also essential. Expanding market pressures for sound land management and prevention of forest clearing on lands unsuitable for agriculture are critical ingredients of a strategy for comprehensive conservation. PMID:16554817

  16. Purification and characterization of chitinases from ridgetail white prawn Exopalaemon carinicauda.

    PubMed

    Wang, Jing; Zhang, Jiquan; Song, Fengge; Gui, Tianshu; Xiang, Jianhai

    2015-01-01

    In this paper, we purified two native chitinases from the hepatopancreas of the ridgetail white prawn Exopalaemon carinicauda by using ion-exchange resin chromatography (IEC) and gel filtration. These two chitinases, named EcChi1 and EcChi2, were identified by chitinolytic activity assay and LC-ESI-MS/MS. Their apparent molecular weights were 44 kDa and 65 kDa as determined by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The specific activity of EcChi1 and EcChi2 was 1305.97 U·mg-1 and 28.69 U·mg-1. The optimal temperature and pH of EcChi1 were 37 °C and pH 4.0, respectively. Co2+, Fe3+, Zn2+, Cd2+, and Cu2+ had an obvious promoting effect upon chitinase activity of EcChi1. For colloidal chitin, the Km and Vmax values of EcChi1 were 2.09 mg·mL-1 and 31.15 U·mL-1·h-1. PMID:25629456

  17. Zinc uptake and regulation by the sublittoral prawn Pandalus montagui (Crustacea: Decapoda)

    NASA Astrophysics Data System (ADS)

    Nugegoda, D.; Rainbow, P. S.

    1988-06-01

    The sublittoral decapod crustacean Pandalus montagui Leach in artificial seawater at 10°C regulates the total body zinc concentration to a constant level in dissolved zinc concentrations up to ca. 22 μg Zn l -1, beyond which there is net accumulation of body zinc. This threshold of zinc regulation breakdown is lower than that in the littoral decapods Palaemon elegans (ca. 93 μg Zn l -1) and Palaemonetes varians (ca. 190 μg Zn l -1) under the same physico-chemical conditions. Correspondingly, zinc uptake rates of the three species of decapods decrease in the order P. montagui > P. elegans > P. varians. It is concluded that regulation of total body zinc concentration is more efficient in decapods adapted to the fluctuating environments of littoral habitats, possibly as a result of changes in permeability of uptake surfaces in combination with improved zinc excretion systems. The moult cycle is important in determining the ability of an individual prawn to regulate zinc. Body zinc in Pandalus montagui consists of at least two pools of zinc exchanging at different rates which the environment. Zinc and copper are not evenly distributed in the tissues of P. montagui.

  18. Identification and occurrence of endogenous semicarbazide in prawns and crabs from zhejiang province, China.

    PubMed

    Zhang, Xiaojun; Chen, Si; Xu, Hanxiang; Zhang, Shuai; Yan, Zhongyong; Wang, Jian

    2016-02-01

    Semicarbazide (SEM) is a side-chain metabolite of the antibiotic drug nitrofurazone (NFZ) and is employed as a conclusive marker for the use of banned NFZ. Recent studies have shown that SEM in aquatic crustaceans can be derived natively or from other sources. The presence and distribution of endogenous SEM within aquatic crustaceans is examined in this paper, which finds that the SEM content varies amongst the muscle, shell, and viscera of various prawn and crab species within the range of 0.35-26.62 ng g(-1). The effects of heating and hypochlorite treatment on SEM levels were examined. The results indicate that thermal processing introduced a more significant impact, resulting in a maximum SEM value of 15.48 ng g(-1) in a sample of shell of Portunus trituberculatus crab, while SEM levels in muscle samples were not affected by the duration of heating. Though 6% active chlorine treatment led to SEM production ranging between 39.9 and 196.4 ng g(-1) in muscle samples from various crustaceans, SEM is unlikely to originate from hypochlorite or chlorine in practice where there are limits to actual chlorine in sanitation water and facilities. 5-Nitro-2-furaldehyde (NF) was proposed as a selective marker to differentiate between endogenous SEM and NFZ-derived SEM in seafood. PMID:26673043

  19. Amazon Rain Forest Classification Using J-ERS-1 SAR Data

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Kramer, C.; Alves, M.; Chapman, B.

    1994-01-01

    The Amazon rain forest is a region of the earth that is undergoing rapid change. Man-made disturbance, such as clear cutting for agriculture or mining, is altering the rain forest ecosystem. For many parts of the rain forest, seasonal changes from the wet to the dry season are also significant. Changes in the seasonal cycle of flooding and draining can cause significant alterations in the forest ecosystem.Because much of the Amazon basin is regularly covered by thick clouds, optical and infrared coverage from the LANDSAT and SPOT satellites is sporadic. Imaging radar offers a much better potential for regular monitoring of changes in this region. In particular, the J-ERS-1 satellite carries an L-band HH SAR system, which via an on-board tape recorder, can collect data from almost anywhere on the globe at any time of year.In this paper, we show how J-ERS-1 radar images can be used to accurately classify different forest types (i.e., forest, hill forest, flooded forest), disturbed areas such as clear cuts and urban areas, and river courses in the Amazon basin. J-ERS-1 data has also shown significant differences between the dry and wet season, indicating a strong potential for monitoring seasonal change. The algorithm used to classify J-ERS-1 data is a standard maximum-likelihood classifier, using the radar image local mean and standard deviation of texture as input. Rivers and clear cuts are detected using edge detection and region-growing algorithms. Since this classifier is intended to operate successfully on data taken over the entire Amazon, several options are available to enable the user to modify the algorithm to suit a particular image.

  20. Sources and distributions of branched and isoprenoid tetraether lipids on the Amazon shelf and fan: Implications for the use of GDGT-based proxies in marine sediments

    NASA Astrophysics Data System (ADS)

    Zell, Claudia; Kim, Jung-Hyun; Hollander, David; Lorenzoni, Laura; Baker, Paul; Silva, Cleverson Guizan; Nittrouer, Charles; Sinninghe Damsté, Jaap S.

    2014-08-01

    Branched glycerol dialkyl glycerol tetraethers (brGDGTs) in river fan sediments have been used successfully to reconstruct mean annual air temperature (MAAT) and soil pH of the Congo River drainage basin. However, in a previous study of Amazon deep-sea fan sediments the reconstructed MAATs were ca. 10 °C colder than the actual MAAT of the Amazon basin. In this study we investigated this apparent offset, by comparing the concentrations and distributions of brGDGTs in Amazon River suspended particulate matter (SPM) and sediments to those in marine SPM and surface sediments. The riverine brGDGT input was evident from the elevated brGDGT concentrations in marine SPM and surface sediments close to the river mouth. The distributions of brGDGTs in marine SPM and sediments varied widely, but generally showed a higher relative abundance of methylated and cyclic brGDGTs than those in the river. Since this difference in brGDGT distribution was also found in intact polar lipid (IPL)-derived brGDGTs, which were more recently produced, the change in the marine brGDGT distribution was most likely due to marine in situ production. Consequently, the MAATs calculated based on the methylation of branched tetraethers (MBT) and the cyclisation of branched tetraethers (CBT) were lower and the CBT-derived pH values were higher than those of the Amazon basin. However, SPM and sediments from stations close to the river mouth still showed MBT/CBT values that were similar to those of the river. Therefore, we recommend caution when applying the MBT/CBT proxy, it should only be used in sediment cores that were under high river influence. The influence of riverine derived isoprenoid GDGT (isoGDGT) on the isoGDGT-based TEX86 temperature proxy was also examined in marine SPM and sediments. An input of riverine isoGDGTs from the Amazon River was apparent, but its influence on the marine TEX86 was minor since the TEX86 of SPM in the Amazon River was similar to that in the marine SPM and sediments.

  1. Major changes in glacial and Holocene terrestrial temperatures and sources of organic carbon recorded in the Amazon fan by tetraether lipids

    NASA Astrophysics Data System (ADS)

    Bendle, James A.; Weijers, Johan W. H.; Maslin, Mark A.; Sinninghe Damsté, Jaap S.; Schouten, Stefan; Hopmans, Ellen C.; Boot, Christopher S.; Pancost, Richard D.

    2010-12-01

    The Amazon basin is a major component of the global carbon and hydrological cycles, a significant natural source of methane, and home to remarkable biodiversity and endemism. Reconstructing past climate changes in the Amazon basin is important for a better understanding of the effect of such changes on these critical functions of the basin. Using a novel biomarker proxy, based on the membrane lipids of soil bacteria with a new regional calibration, we present a reconstruction of changes in mean annual air temperatures for the Amazon catchment during the last 37 kyr B.P. Biomarkers were extracted from Ocean Drilling Program sediment core ODP942 recovered from the Amazon fan. The Amazon fan is a major depository for terrestrial sediments, with the advantage that the terrestrial material captured reflects a regional integration of the whole river catchment. The reconstructed tropical Amazonian temperatures were ˜5°C cooler at the Last Glacial Maximum (˜21°C) compared to modern values (˜26°C). This is in agreement with previous estimates of tropical continental temperatures in the tropical Amazon basin and tropical Africa during the Last Glacial Maximum. Moreover, we also illustrate how the soil bacterial membrane lipid record reveals major changes in basin dynamics and sediment provenance during the glacial-Holocene transition, impacting the biomarker reconstructions from ˜11 kyr onward.

  2. Dietary supplementation of green synthesized manganese-oxide nanoparticles and its effect on growth performance, muscle composition and digestive enzyme activities of the giant freshwater prawn Macrobrachium rosenbergii.

    PubMed

    Asaikkutti, Annamalai; Bhavan, Periyakali Saravana; Vimala, Karuppaiya; Karthik, Madhayan; Cheruparambath, Praseeja

    2016-05-01

    The green synthesized Mn3O4 nanoparticles (manganese-oxide nanoparticles) using Ananas comosus (L.) peel extract was characterized by various techniques. HR-SEM photograph showed that manganese-oxide nanoparticles (Mn-oxide NPs) were spherical in shape, with an average size of 40-50nm. The Zeta potential revealed the surface charge of Mn-oxide NPs to be negative. Further, the Mn-oxide NPs were dietary supplemented for freshwater prawn Macrobrachium rosenbergii. The experimental basal diets were supplemented with Mn-oxide NPs at the rates of 0 (control), 3.0, 6.0, 9.0, 12, 15 and 18mg/kg dry feed weight. The as-supplemented Mn-oxide NPs were fed in M. rosenbergii for a period of 90 days. The experimental study demonstrated that prawns fed with diet supplemented with 3-18mg Mn-oxide NPs/kg shows enhanced (P<0.05) growth performance, including final weight and weight gain (WG). Significant differences (P<0.05) in feed conversion ratio (FCR) were observed in prawn fed with different diets. Additionally, prawns fed with 3.0-18mg/kg Mn-oxide NPs supplemented diets achieved significant (P<0.05) improvement in growth performance, digestive enzyme activities and muscle biochemical compositions, while, the prawns fed with 16mg/kg of Mn-oxide NPs showed enhanced performance. Prawns fed on diet supplemented with 16mg/kg Mn-oxide NPs showed significantly (P<0.05) higher total protein level. The antioxidants enzymatic activity (SOD and CAT) metabolic enzymes status in muscle and hepatopancreas showed no significant (P>0.05) alterations in prawns fed with 3.0-18mg/kg of Mn-oxide NPs supplemented diets. Consequently, the present work proposed that 16mg/kg of Mn-oxide NPs could be supplemented for flexible enhanced survival, growth and production of M. rosenbergii. Therefore, the data of the present study recommend the addition of 16mg/kg of Mn-oxide NPs diet to developed prawn growth and antioxidant defense system. PMID:27049122

  3. Using remote sensing for validation of a large scale hydrologic and hydrodynamic model in the Amazon

    NASA Astrophysics Data System (ADS)

    Paiva, R. C.; Bonnet, M.; Buarque, D. C.; Collischonn, W.; Frappart, F.; Mendes, C. B.

    2011-12-01

    We present the validation of the large-scale, catchment-based hydrological MGB-IPH model in the Amazon River basin. In this model, physically-based equations are used to simulate the hydrological processes, such as the Penman Monteith method to estimate evapotranspiration, or the Moore and Clarke infiltration model. A new feature recently introduced in the model is a 1D hydrodynamic module for river routing. It uses the full Saint-Venant equations and a simple floodplain storage model. River and floodplain geometry parameters are extracted from SRTM DEM using specially developed GIS algorithms that provide catchment discretization, estimation of river cross-sections geometry and water storage volume variations in the floodplains. The model was forced using satellite-derived daily rainfall TRMM 3B42, calibrated against discharge data and first validated using daily discharges and water levels from 111 and 69 stream gauges, respectively. Then, we performed a validation against remote sensing derived hydrological products, including (i) monthly Terrestrial Water Storage (TWS) anomalies derived from GRACE, (ii) river water levels derived from ENVISAT satellite altimetry data (212 virtual stations from Santos da Silva et al., 2010) and (iii) a multi-satellite monthly global inundation extent dataset at ~25 x 25 km spatial resolution (Papa et al., 2010). Validation against river discharges shows good performance of the MGB-IPH model. For 70% of the stream gauges, the Nash and Suttcliffe efficiency index (ENS) is higher than 0.6 and at bidos, close to Amazon river outlet, ENS equals 0.9 and the model bias equals,-4.6%. Largest errors are located in drainage areas outside Brazil and we speculate that it is due to the poor quality of rainfall datasets in these areas poorly monitored and/or mountainous. Validation against water levels shows that model is performing well in the major tributaries. For 60% of virtual stations, ENS is higher than 0.6. But, similarly, largest errors are also located in drainage areas outside Brazil, mostly Japur River, and in the lower Amazon River. In the latter, correlation with observations is high but the model underestimates the amplitude of water levels. We also found a large bias between model and ENVISAT water levels, ranging from -3 to -15 m. The model provided TWS in good accordance with GRACE estimates. ENS values for TWS over the whole Amazon equals 0.93. We also analyzed results in 21 sub-regions of 4 x 4. ENS is smaller than 0.8 only in 5 areas, and these are found mostly in the northwest part of the Amazon, possibly due to same errors reported in discharge results. Flood extent validation is under development, but a previous analysis in Brazilian part of Solimes River basin suggests a good model performance. The authors are grateful for the financial and operational support from the brazilian agencies FINEP, CNPq and ANA and from the french observatories HYBAM and SOERE RBV.

  4. Radionuclide tracers of sediment-water interactions on the Amazon shelf

    NASA Astrophysics Data System (ADS)

    Moore, Willard S.; DeMaster, David J.; Smoak, Joseph M.; McKee, Brent A.; Swarzenski, Peter W.

    1996-04-01

    A comprehensive study of a variety of radionuclide tracers has been coupled with other geochemical investigations and with sedimentary and physical oceanographic measurements to elucidate processes and their characteristic time scales at the mouth of the Amazon River. This two-year field study on the Amazon continental shelf involved four cruises designed to provide information during different stages of the river hydrograph. Although the cruises were coordinated with river stage, other physical variables including spring-neap tidal stages, the flow of the North Brazil Current and trade-wind stress caused important effects on the shelf environment. Partitioning of uranium among dissolved, colloidal and particulate phases was investigated during AmasSeds. A detailed examination of uranium water-column behavior during low river discharge found that most (89%) of the uranium near the Amazon River mouth was associated with the particulate phase and that most (92%) of the riverine dissolved-phase uranium was in the colloidal size fraction (0.001-0.4 ?m). A non-conservative uranium/salinity distribution was observed for dissolved uranium, indicating large-scale uranium removal from surface waters with salinities less than 20 ppt. Colloidal uranium was non-conservative across the entire salinity regime, exhibiting removal of colloidal uranium from waters with salinities less than 12 ppt and a significant input at higher salinities. A short-lived particle-reactive tracer, 234Th, was used to evaluate the rates of particle scavenging on the shelf. Suspended-sediment concentrations respond to each turn of the tide, thus limiting the time available for equilibrium to be established between the particles and the tracers. Experiments demonstrated that on the Amazon shelf the partitioning and distribution of trace elements are governed by particle dynamics (particle residence times < sorption times). The high suspended load, including fluid muds, retards the incorporation of adsorbed 234Th into the seabed. Once scavenged, 234Th remains part of the suspended-sediment and fluid-mud inventory for periods of at least 4-8 weeks. Another particle-reactive tracer, 210Pb, was used to evaluate the potential supply of reactive metals from offshore waters to the shelf. As open-ocean waters move into the Amazon mixing zone, in response to the estuarine-like circulation, they lose 210Ph through scavenging processes associated with delta formation. This oceanic input of 210Pb dominates other inputs to the Amazon shelf system. Based on 210Pb analyses from more than 40 ? and kasten cores, the flux of water moving shoreward and depositing 210Pb in the sediments was calculated to be on the order of 6 10 161y -1 10 times the riverine flux from the Amazon. The distribution of 210Pb in the sediments suggests that if particle-reactive species (such as certain trace metals) are released in dissolved form on the shelf, they will be scavenged quickly in this turbid environment, with the largest inventories occurring in the foreset beds (although the highest concentrations occur in the bottomset beds). The large landward flow of water indicates that if particle-reactive species are released in the western equatorial Atlantic via aerosol transport or other mechanisms, there is a good chance that a sizeable portion will be buried in the Amazon delta. Fluxes of radium isotopes, 226Ra, 228Ra and 224Ra, from the bottom sediments were used to evaluate sediment resuspension across the shelf. The average flux of 226Ra from the Amazon shelf balanced the annual desorption of 226Ra from river-derived sediments; however, departures between the 226Ra flux and sediment necessary to support the flux occurred for different sampling periods. During falling and low discharge, less sediment entered the system than was required to support the sedimentary desorption 226Ra flux. During rising and high discharge, more sediment entered than was necessary to sustain the 226Ra flux. Considerable recycling of particles between the seabed and water column was required to wash away most of the desorbable 226Ra from the sediment. To support the sedimentary 228Ra flux, 3.4 10 16 g of sediment must be resuspended each year. Such mixing would resuspend the top 35 em of sediment over the entire shelf each year, or mix the surface layer (SL, the region of uniform sedimentary 210Pb depth profiles) to a depth of 90 cm annually. Such mixing would turn over the entire SL every 1-2 years. Desorption of sedimentary radium isotopes must be accompanied by the desorption of other exchangeable species including phosphate, cesium and cadmium. Correlations among phosphate and radium isotopes, infer that phosphate is being released from bottom sediments as the sediments are resuspended into the water column. As was the case for 226Ra, bottom sediment must be repeatedly suspended into the water column to release all of the exchangeable phosphate. The desorption of 224Ra from shelf sediments provides a tracer of the Amazon plume into the Atlantic. In July and September 1989, the ship crossed the Demerara retroflection 380 km from the Amazon shelf and excess 224Ra activities up to 8 dpm 100 kg -1 were measured. It was concluded that these waters were <5 days removed from the Amazon shelf. A sustained current of >80 em s -1 would be required to advect the water this distance in <5 days, an observation that agrees well with drogue releases during August 1989.

  5. Dynamics of surface water storage in the Amazon inferred from measurements of inter-satellite distance change

    NASA Astrophysics Data System (ADS)

    Han, Shin-Chan; Kim, Hyungjun; Yeo, In-Young; Yeh, Pat; Oki, Taikan; Seo, Ki-Weon; Alsdorf, Doug; Luthcke, Scott B.

    2009-05-01

    Terrestrial water storage in the Amazon basin and its surrounding areas is studied by exploring the instantaneous measurements of distance changes between two satellites from the GRACE mission. The surface water in the channels and floodplains can be significant in weighing total water storage. Its magnitude can be as large as soil moisture perturbing the motions of the satellites to a detectable amount by the on-board instrument. The river runoff routing simulations indicate the effective velocity throughout the Amazon basin over the years is about 30 cm/s with significant seasonal change. The lower velocity, during rising stages and peak water season, and the faster velocity, during falling stages, are delineated from the observations. The backwater effects may impact such seasonal change on the overall flow velocity. Direct assimilation of GRACE tracking data can contribute to land surface dynamic processes by resolving the time scale of transport in rivers and streams.

  6. The recent extreme hydrological events in the Western Amazon Basin: The role of the Pacific and Atlantic Oceans

    NASA Astrophysics Data System (ADS)

    Espinoza, J.; Ronchail, J.; Guyot, J.; Santini, W.; Lavado, W.; Ore-Hybam Observatory

    2013-05-01

    The Peruvian Amazonas River, the main western tributary of the Amazon basin, has a huge drainage (750 000 km2, 50% of which lies in the Andes) and a mean discharge estimated in 32 000 m3/s, which correspond to 15% of the Amazon discharge at the estuary. Recently, in a context of significant discharge diminution during the low-water season (1970-2012), severe hydrological events, as intense droughts and floods, have been reported in the Peruvian Amazonas River. As they have not been always observed in other regions of the Amazon basin and because they have strong impacts on vulnerable riverside residents, we shall focus on the origin and the predictability of the western Amazon extremes, providing a review of the main findings about the climate features during recent extreme hydrological events in western Amazon. While the lowest discharge value was observed in September 2010 (8 300 m3/s) at the hydrological Tamshiyacu station (near to Iquitos city), a rapid transition toward a high discharge was noticed in April 2011 (45 000 m3/s). Finally, in April 2012, during the on going high waters period, the Amazonas River is experimenting its historical highest discharge (55 000 m3/s). Our work is based on several datasets including in-situ discharge and rainfall information from ORE-HYBAM observatory. Extreme droughts (1995, 2005 and 2010) are generally associated with positive SST anomalies in the tropical North Atlantic and weak trade winds and water vapor transport toward the western Amazon, which, in association with increased subsidence over central and southern Amazon, explain the lack of rainfall and very low discharge values. But, in 1998, toward the end of the 1997-98 El Niño event, the drought has been more likely related to an anomalous divergence of water vapor in the western Amazon that is characteristic of a warm event in the Pacific. The years with a rapid transition form low waters to very high floods (e.g. September 2010 to April 2011) are characterized by negative SST anomalies in the central equatorial Pacific during austral summer, corresponding to a La Niña mode. As a consequence of atmospheric teleconnections related to La Niña, the monsoon flux is retained over the Amazon and a strong convergence of humidity occurs in the north-western Amazon basin, favouring high rainfall and discharge. These features were also observed during the 2012 austral summer, with a major advection of humidity from the Caribbean Sea. During this event, an anticipated rainfall season also played an important role on the onset of the flood. In conclusion, recent works reveal an influence of the tropical North Atlantic on extreme droughts in the western Amazon, during the austral winter and spring, and a role of SST variability in the central equatorial Pacific to modulate floods intensity during the austral summer season.

  7. Toxic impact of aldrin on acid and alkaline phosphatase activity of penaeid prawn, Metapenaeus monoceros: In vitro study

    SciTech Connect

    Reddy, M.S.; Jayaprada, P.; Rao, K.V.R. )

    1991-03-01

    The increasing contamination of the aquatic environment by the indiscriminate and widespread use of different kinds of pesticides is a serious problem for environmental biologists. Organochlorine insecticides are more hazardous since they are not only more toxic but also leave residues in nature. The deleterious effects of aldrin on several crustaceans have been studied. But studies concerning the impact of aldrin on biochemical aspects of crustaceans are very much limited. The present study is aimed at probing the in vitro effects of aldrin on the acid and alkaline phosphatase activity levels in selected tissues of penaeid prawn, Metapenaeus monoceros (Fabricius).

  8. Draft Genome Sequence of the N2-Fixing Cyanobacterium Nostoc piscinale CENA21, Isolated from the Brazilian Amazon Floodplain

    PubMed Central

    Guimarães, Pedro Ivo; de Melo, Aline Grasielle Costa; Ramos, Rommel Thiago Jucá; Leão, Pedro Nuno; Silva, Artur; Fiore, Marli Fatima; Schneider, Maria Paula Cruz

    2016-01-01

    We announce here the draft genome sequence of Nostoc piscinale CENA21, a diazotrophic heterocyst-forming cyanobacterium isolated from the Solimões River, Amazon Basin, Brazil. It consists of one circular chromosome scaffold with 11 contigs and total size of 7,094,556 bp. Secondary metabolite annotations indicate a good source for the discovery of novel natural products. PMID:27034496

  9. Draft Genome Sequence of the N2-Fixing Cyanobacterium Nostoc piscinale CENA21, Isolated from the Brazilian Amazon Floodplain.

    PubMed

    Leão, Tiago; Guimarães, Pedro Ivo; de Melo, Aline Grasielle Costa; Ramos, Rommel Thiago Jucá; Leão, Pedro Nuno; Silva, Artur; Fiore, Marli Fatima; Schneider, Maria Paula Cruz

    2016-01-01

    We announce here the draft genome sequence ofNostoc piscinaleCENA21, a diazotrophic heterocyst-forming cyanobacterium isolated from the Solimões River, Amazon Basin, Brazil. It consists of one circular chromosome scaffold with 11 contigs and total size of 7,094,556 bp. Secondary metabolite annotations indicate a good source for the discovery of novel natural products. PMID:27034496

  10. Observations of sediment transport on the Amazon subaqueous delta

    USGS Publications Warehouse

    Sternberg, R.W.; Cacchione, D.A.; Paulson, B.; Kineke, G.C.; Drake, D.E.

    1996-01-01

    A 19-day time series of fluid, flow, and suspended-sediment characteristics in the benthic boundary layer is analyzed to identify major sedimentary processes active over the prodelta region of the Amazon subaqueous delta. Measurements were made by the benthic tripod GEOPROBE placed on the seabed in 65 m depth near the base of the deltaic foreset beds from 11 February to 3 March 1990, during the time of rising water and maximum sediment discharge of the Amazon River; and the observations included: hourly measurements of velocity and suspended-sediment concentration at four levels above the seabed; waves and tides; and seabed elevation. Results of the first 14-day period of the time series record indicate that sediment resuspension occurred as a result of tidal currents (91% of the time) and surface gravity waves (46% of the time). Observations of suspended sediment indicated that particle flux in this region is 0.4-2% of the flux measured on the adjacent topset deposits and is directed to the north and landward relative to the Brazilian coast (268??T). Fortnightly variability is strong, with particle fluxes during spring tides five times greater than during neap tides. On the 15th day of the data record, a rapid sedimentation event was documented in which 44 cm of sediment was deposited at the study site over a 14-h period. Evaluation of various mechanisms of mass sediment movement suggests that this event represents downslope migration of fluid muds from the upper foreset beds that were set in motion by boundary shear stresses generated by waves and currents. This transport mechanism appears to occur episodically and may represent a major source of sediment to the lower foreset-bottomset region of the subaqueous delta.

  11. The geological record preserved by Amazon shelf sedimentation

    NASA Astrophysics Data System (ADS)

    Nittrouer, Charles A.; Kuehl, Steven A.; Figueiredo, Alberto G.; Allison, Mead A.; Sommerfield, Christopher K.; Rine, James M.; Faria, L. Ercilio C.; Silveira, Odete M.

    A recent study of the subaqueous delta and coastal plain near the mouth of the Amazon River provides insight to the geological record created there and elsewhere. A compound clinoform structure is forming across the Amazon shelf. The uppermost portion is the shoreline, whose aggradation brings the modern sedimentary deposit to sea level and produces a deposit 5-10 m thick. It contains sediments accumulating primarily in shallow subtidal areas, intertidal mudflats and mangrove forests, and progradation occurs by overlapping of northward-extending mudcapes. Through these processes, the coastal plain has been widened by 10-100 km during the Holocene. The shoreline deposits are prograding across topset strata of the modern subaqueous delta, which is the lowermost and dominant portion of the compound clinoform structure. The subaqueous delta extends to a water depth of 70 m, with a depositional break between topset and foreset strata at 30-40 m. Advective sediment input to the foreset region causes high accumulation rates, which control the geometry and progradation of the clinoform structure. On time scales of 10 2-10 3 y, physical processes (e.g. waves, currents) have changed and the upper portions of the coastal plain and subaqueous delta have been eroded. One expression of this is a widespread unconformity recorded within late Holocene strata on the inner shelf. Over longer time scales (10 3-10 4 y) sea-level changes have led to more extensive erosion and only the lower 20 m of the compound clinoform structure is preserved, overlain by a transgressive sand layer. On other continental margins with different regional characteristics (e.g. more rapid subsidence) larger fractions of the clinoform structures could be preserved.

  12. Structural factors that increase HIV/STI vulnerability among indigenous people in the Peruvian amazon.

    PubMed

    Orellana, E Roberto; Alva, Isaac E; Crcamo, Cesar P; Garca, Patricia J

    2013-09-01

    We examined structural factors-social, political, economic, and environmental-that increase vulnerability to HIV among indigenous people in the Peruvian Amazon. Indigenous adults belonging to 12 different ethnic groups were purposively recruited in four Amazonian river ports and 16 indigenous villages. Qualitative data revealed a complex set of structural factors that give rise to environments of risk where health is constantly challenged. Ferryboats that cross Amazonian rivers are settings where unprotected sex-including transactional sex between passengers and boat crew and commercial sex work-often take place. Population mobility and mixing also occurs in settings like the river docks, mining sites, and other resource extraction camps, where heavy drinking and unprotected sex work are common. Multilevel, combination prevention strategies that integrate empirically based interventions with indigenous knowledge are urgently needed, not only to reduce vulnerability to HIV transmission, but also to eliminate the structural determinants of indigenous people's health. PMID:23925407

  13. Amazon dams and waterways: Brazil's Tapajós Basin plans.

    PubMed

    Fearnside, Philip M

    2015-09-01

    Brazil plans to build 43 "large" dams (>30 MW) in the Tapajós Basin, ten of which are priorities for completion by 2022. Impacts include flooding indigenous lands and conservation units. The Tapajós River and two tributaries (the Juruena and Teles Pires Rivers) are also the focus of plans for waterways to transport soybeans from Mato Grosso to ports on the Amazon River. Dams would allow barges to pass rapids and waterfalls. The waterway plans require dams in a continuous chain, including the Chacorão Dam that would flood 18,700 ha of the Munduruku Indigenous Land. Protections in Brazil's constitution and legislation and in international conventions are easily neutralized through application of "security suspensions," as has already occurred during licensing of several dams currently under construction in the Tapajós Basin. Few are aware of "security suspensions," resulting in little impetus to change these laws. PMID:25794814

  14. Structural Factors That Increase HIV/STI Vulnerability Among Indigenous People in the Peruvian Amazon

    PubMed Central

    Orellana, E. Roberto; Alva, Isaac E.; Cárcamo, Cesar P.; García, Patricia J.

    2015-01-01

    We examined structural factors—social, political, economic, and environmental—that increase vulnerability to HIV among indigenous people in the Peruvian Amazon. Indigenous adults belonging to 12 different ethnic groups were purposively recruited in four Amazonian river ports and 16 indigenous villages. Qualitative data revealed a complex set of structural factors that give rise to environments of risk where health is constantly challenged. Ferryboats that cross Amazonian rivers are settings where unprotected sex—including transactional sex between passengers and boat crew and commercial sex work—often take place. Population mobility and mixing also occurs in settings like the river docks, mining sites, and other resource extraction camps, where heavy drinking and unprotected sex work are common. Multilevel, combination prevention strategies that integrate empirically based interventions with indigenous knowledge are urgently needed, not only to reduce vulnerability to HIV transmission, but also to eliminate the structural determinants of indigenous people’s health. PMID:23925407

  15. Methane emissions from Amazonian Rivers and their contribution to the global methane budget.

    PubMed

    Sawakuchi, Henrique O; Bastviken, David; Sawakuchi, André O; Krusche, Alex V; Ballester, Maria V R; Richey, Jeffrey E

    2014-09-01

    Methane (CH4 ) fluxes from world rivers are still poorly constrained, with measurements restricted mainly to temperate climates. Additional river flux measurements, including spatio-temporal studies, are important to refine extrapolations. Here we assess the spatio-temporal variability of CH4 fluxes from the Amazon and its main tributaries, the Negro, Solimões, Madeira, Tapajós, Xingu, and Pará Rivers, based on direct measurements using floating chambers. Sixteen of 34 sites were measured during low and high water seasons. Significant differences were observed within sites in the same river and among different rivers, types of rivers, and seasons. Ebullition contributed to more than 50% of total emissions for some rivers. Considering only river channels, our data indicate that large rivers in the Amazon Basin release between 0.40 and 0.58 Tg CH4  yr(-1) . Thus, our estimates of CH4 flux from all tropical rivers and rivers globally were, respectively, 19-51% to 31-84% higher than previous estimates, with large rivers of the Amazon accounting for 22-28% of global river CH4 emissions. PMID:24890429

  16. Effects of hot-water extract of banana (Musa acuminata) fruit's peel on the antibacterial activity, and anti-hypothermal stress, immune responses and disease resistance of the giant freshwater prawn, Macrobrachium rosenbegii.

    PubMed

    Rattanavichai, Wutti; Cheng, Winton

    2014-08-01

    The hot-extracts isolated from fruit's peel of banana, Musa acuminata, was evaluated on the antibacterial activity to pathogens from aquatic animals, and immunostimulating potential, disease resistance and anti-hypothermal stress in giant freshwater prawn, Macrobrachium rosenbergii through injection administration. The banana peel extract (BPE) showed good activity against 1 Gram-positive and 3 Gram-negative pathogens, including Lactococcus garvieae, Photobacteria damsella, Vibrio alginolyticus and Vibrio parahemolyticus especially in prawn pathogen of L. garvieae strain, which were carried out by a disk diffusion method. Prawn received BPE via injection administration at 1-6 μg (g prawn)(-1) significantly increased total haemocyte count (THC), hyaline cell (HC), granular cell (GC), phenoloxidase (PO) activity and phagocytic activity against L. garvieae from 3 to 6 days, and significantly increased clearance efficiency against L. garvieae and a significantly decreased coagulation time of prawn from 1 to 6 days. Prawn injected with BPE at 6.0 μg (g prawn)(-1) for 6 days showed significantly increased superoxide dismutase (SOD) activity, but significantly decreased respiratory bursts (RBs) of per haemocyte. Survival rates of M. rosenbergii injected with BPE at concentrations of 1, 3 and 6 μg (g prawn)(-1) were significantly higher than those injected with saline control after challenge with L. garvieae for 4-6 days, and the respective relative survival percentages of prawn were 28.6%, 38.1%, and 47.8%, respectively at 6 days. The sublethal time of prawns that had received saline and BPE at 1, 3 and 6 μg (g prawn)(-1) for 6 days and then were transferred from 28 °C to 14 °C were 69.4, 79.8, 83.6, and 90.2 h, respectively. It was concluded that the BPE can be used as the bacteriostat, and immunostimulant and physiological regulator for prawn through injection administration to enhance immunity, physiological responses, and resistance against L. garvieae. PMID:24906123

  17. Genetic Inheritance of Female and Male Morphotypes in Giant Freshwater Prawn Macrobrachium rosenbergii

    PubMed Central

    2014-01-01

    Giant freshwater prawn (GFP) Macrobrachium rosenbergii is unique with males categorized in five different morphotypes (small claw, orange claw, blue claw, old blue claw and no claw males) and females in three reproductive statuses (mature ovary, berried and spawned females). In the present study we examined genetic inheritance of female and male morphotypes, their body weights and genetic associations between morphotypes and body traits. Restricted maximum likelihood fitting a multi-trait animal model was performed on a total of 21,459 body records collected over five generations in a GFP population selected for high growth rate. The estimates of variance components showed that there were substantial differences in additive genetic variance in body weight between male morphotypes. The low and significantly different from one genetic correlations between the expressions of body weight in male morphotypes also suggest that these traits should be treated as genetically different traits in selective breeding programs. By contrast, body weights of female types are essentially the same characters as indicated by the high genetic correlations between homologous trait expressions. In addition to body weight, male morphotypes and female reproductive statuses were treated as traits in themselves and were analysed as binary observations using animal and sire linear mixed models, and logit and probit threshold models. The estimates of heritability back-transformed from the liability scale were in good agreement with those obtained from linear mixed models, ranging from 0.02 to 0.43 for male morphotypes and 0.06 to 0.10 for female types. The genetic correlations among male morphoptypes were generally favourable. Body weight showed negative genetic associations with SM (−0.96), whereas those of body weight with other male morphotypes were positive (0.25 to 0.76). Our results showed that there is existence of heritable (additive genetic) component for male morphotypes, giving prospects for genetic selection to change population structure of GFP. PMID:24587246

  18. Reproductive biology of the prawn Melicertus kerathurus (Decapoda: Penaeidae) in Thermaikos Gulf (N. Aegean Sea)

    NASA Astrophysics Data System (ADS)

    Kevrekidis, Kosmas; Thessalou-Legaki, Maria

    2013-03-01

    The reproductive biology including insemination frequency, ovarian maturation, gonadosomatic index (GSI), size at first maturity, and fecundity of Melicertus kerathurus were investigated using monthly samples from Thermaikos Gulf. Insemination was recorded by the presence of a spermatophore in the thelycum, and ovarian development was based on macroscopic ovarian staging (ST1-ST5). Inseminated females were found throughout the year with high percentages recorded from April to July. Although all ovarian stages were represented in mated females, insemination increased with size and ovarian maturation. High percentages of vitellogenic or mature ovarian stages were observed from May to July, while immature and developing ovaries were predominant mainly in winter. Spawned ovaries occurred from May to October. Carapace length at first maturity based on the presence of a spermatophore (CL50sp) was estimated at 39.20 mm, while that based on the presence of vitellogenic and mature ovaries (CL50ov) at 40.70 mm. The seasonal peak in the proportion of mature females (ST4) varied with size. Inseminated females at ST4 and GSI peaked in June-July. GSI varied in relation to insemination status and ovarian stage. In large females (>50 mm CL), the decline in mature ovaries and GSI increment with size indicates a relative reduction in the reproductive output. The number of oocytes ranged from 62,742 to 602,947 (mean ± SD: 268,000 ± 113,000). As the prawns are targeted during the spawning season, mainly by the artisanal fishery, and female size at first maturity is selected by artisanal net size, managerial measures toward artisanal fishery should be implemented.

  19. Principal Connection / Amazon and the Whole Teacher

    ERIC Educational Resources Information Center

    Hoerr, Thomas R.

    2015-01-01

    A recent controversy over Amazon's culture has strong implications for the whole child approach, and it offers powerful lessons for principals. A significant difference between the culture of so many businesses today and the culture at good schools is that in good schools, the welfare of the employees is very important. Student success is the

  20. Principal Connection / Amazon and the Whole Teacher

    ERIC Educational Resources Information Center

    Hoerr, Thomas R.

    2015-01-01

    A recent controversy over Amazon's culture has strong implications for the whole child approach, and it offers powerful lessons for principals. A significant difference between the culture of so many businesses today and the culture at good schools is that in good schools, the welfare of the employees is very important. Student success is the…

  1. Amazon Flooded Forest. Teacher Resource Guide.

    ERIC Educational Resources Information Center

    Duvall, Todd

    This teacher's resource guide was created to accompany the Amazon Flooded Forest exhibit at the Oregon Zoo. The enclosed lessons and activities are designed to extend into several aspects of daily curriculum including science, math, reading, writing, speaking, and geography. The materials are intended for use in grades 3-6 although most activities…

  2. Polycystic Echinococcosis in Pacas, Amazon Region, Peru

    PubMed Central

    Mayor, Pedro; Baquedano, Laura E.; Sanchez, Elisabeth; Aramburu, Javier; Gomez-Puerta, Luis A.; Mamani, Victor J.

    2015-01-01

    In the Peruvian Amazon, paca meat is consumed by humans. To determine human risk for polycystic echinococcosis, we examined wild pacas from 2 villages; 15 (11.7%) of 128 were infected with Echinococcus vogeli tapeworms. High E. vogeli prevalence among pacas indicates potential risk for humans living in E. vogeli–contaminated areas. PMID:25695937

  3. Amazon Flooded Forest. Teacher Resource Guide.

    ERIC Educational Resources Information Center

    Duvall, Todd

    This teacher's resource guide was created to accompany the Amazon Flooded Forest exhibit at the Oregon Zoo. The enclosed lessons and activities are designed to extend into several aspects of daily curriculum including science, math, reading, writing, speaking, and geography. The materials are intended for use in grades 3-6 although most activities

  4. The Amazon-influenced muddy coast of South America: A review of mud-bank-shoreline interactions

    NASA Astrophysics Data System (ADS)

    Anthony, Edward J.; Gardel, Antoine; Gratiot, Nicolas; Proisy, Christophe; Allison, Mead A.; Dolique, Franck; Fromard, François

    2010-12-01

    The 1500 km-long coast of South America between the Amazon and the Orinoco river mouths is the world's muddiest. This is due to the huge suspended-sediment discharge of the Amazon River (10 6 × 754 tons yr - 1 ± 9%), part of which is transported alongshore as mud banks. Mud-bank formation is controlled by the physical oceanography of the continental shelf seaward of the Amazon River mouth, an initial seafloor storage area for much of the suspended sediment discharged from the river. In this area, rapid and sustained fluid-mud concentration and trapping are associated with fresh water-salt water interaction and estuarine front activity on the shelf due to the enormous Amazon water discharge (ca. 173,000 m 3 s - 1 at Obidos, 900 km upstream of the mouth). Fluid mud is transported shoreward and then along the coasts of the Guianas by a complex interaction of wave and tidal forcing, and wind-generated coastal currents. The mud banks, which may number up to 15 or more at any time, are up to 5 m-thick, 10 to 60 km-long, and 20 to 30 km-wide, and each may contain the equivalent mass of the annual mud supply of the Amazon. As the banks migrate alongshore, their interaction with waves results in complex and markedly fluctuating shorelines that are associated with space- and time-varying depositional 'bank' phases and erosional 'inter-bank' phases. Bank zones are protected from wave attack as a result of wave-energy dampening by mud, and undergo significant, albeit temporary, coastal accretion accompanied by rapid mangrove colonization. The dampening of waves in bank areas as they propagate onshore is accompanied by the shoreward recycling of mud, commonly in the form of individual mud bars. These bars progressively undergo desiccation and consolidation, and thus constitute a major pathway for rapid and massive colonization by mangroves. Erosion by waves propagating across relatively mud-deficient shoreface zones in inter-bank areas can lead to muddy shoreline retreat rates of tens of metres to several kilometres over a few months to a few years, accompanied by massive removal of mangroves. Notwithstanding the higher incident wave energy on inter-bank shores, inter-bank shorefaces are permanently muddy due to the pervasive influence of the Amazon muddy discharge. Inter-bank and transitional bank-to-inter-bank phases are associated with both periodic sandy chenier formation and extreme forms of rotation of rare headland-bound sandy beaches. The high mud supply from the Amazon has been the overarching geological control on the Quaternary evolution of the northeastern South American coast, having led to the growth of a muddy shelf clinoform at the mouth of the Amazon and more or less important progradation throughout this coast. Net progradation reflects an imbalance in favour of deposition during each mud-bank-inter-bank cycle. The high mud supply has presumably blanketed shelf sand deposited by smaller rivers during eustatic lowstand phases. The shelf clinoform structure at the mouth of the Amazon and the muddy coastal progradation throughout the coast of the Guianas and into Venezuela provide analogues of the geological record on muddy shorefaces.

  5. Potential impact of the colored Amazon and Orinoco plume on tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

    Newinger, C.; Toumi, R.

    2015-02-01

    The Amazon and the Orinoco river plumes modulate ocean stratification and color in the tropical North Atlantic. This changes air-sea interactions and may thus be important for tropical cyclones (TCs). Using a regional ocean model, we try to separate the potential impact of river freshwater and light absorption on ocean temperatures, stability, and TC intensity. While the freshwater plume stabilizes the water column, there is no significant change in sea surface temperatures. However, increased stability and temperature inversions may reduce surface cooling feedbacks. The cooling inhibition index (CI) is +2.2 (J/m2)1/3 larger when the river freshwater plume is present. Ocean color in the river plume on the other hand, blocks the deeper ocean from sunlight, leading to moderate surface warming (+0.1°C) and substantial subsurface cooling (-0.3°C 100 m mean temperature). As a consequence cold water is more readily available to passing storms and the CI decreases by -2.1 (J/m2)1/3. Using simple, idealized relationships between expected surface cooling and TC intensity, we find that river-induced stability enhances strong TCs by up to -5 to -12 hPa, while ocean color may reduce intensity by +8 hPa to +16 hPa. The net impact of the colored plume is negligible for weak storms and a slight intensity reduction for stronger cyclones. Within the Amazon and Orinoco plume, the river freshwater effect may thus be substantially reduced or even offset by light absorbing particles.

  6. Changes in the levels, expression, and possible roles of serotonin and dopamine during embryonic development in the giant freshwater prawn, Macrobrachium rosenbergii.

    PubMed

    Tinikul, Yotsawan; Poljaroen, Jaruwan; Tinikul, Ruchanok; Sobhon, Prasert

    2016-01-01

    We investigated the changes in the levels of serotonin (5-HT) and dopamine (DA), and their possible roles during embryonic development of the freshwater prawn, Macrobrachium rosenbergii. The 5-HT and DA concentrations were quantified using high performance liquid chromatography with electrochemical detection (HPLC-ECD). The levels of 5-HT and DA gradually increased from early developing embryos to late developing embryos. The 5-HT concentrations gradually increased from the pale yellow egg to orange egg stages, and reaching a maximum at the black egg stage. DA concentrations were much lower in the early embryos than those of 5-HT (P<0.05), and gradually increased to reach the highest level at the black egg stage. Immunohistochemically, 5-HT was firstly detected in the early embryonic stages, whereas DA developed later than 5-HT. Functionally, 5-HT-treated female prawns at doses of 2.5×10(-5), 2.5×10(-6) and 2.5×10(-7)mol/prawn, produced embryos with significantly shortened lengths of early embryonic stages, whereas DA-treated prawns at all three doses, exerted its effects by significantly lengthening the period of mid-embryonic stage onwards. These results suggest significant involvement of 5-HT and DA in embryonic developmental processes of this species. PMID:26393313

  7. Evaluating the Amazon water cycle components using ED model against GRACE

    NASA Astrophysics Data System (ADS)

    Lee, E.; Han, S. C.; Yeo, I. Y.; Longo, M.; Swann, A. L. S.; Knox, R. G.; Briscoe, J.; Moorcroft, P. R.

    2014-12-01

    Changes in the water cycle components of the Amazon and its surrounding regions are a key to assessing regional impacts of climate and land-cover changes, as they may affect rain-fed agriculture and hydroelectric power generation in Brazil. A comprehensive validation of the modeled water budget, therefore, is a necessary part of understanding the region's hydroclimatology. We evaluate the water cycle components from Ecosystem Demography (ED) model both as a stand-alone model and a coupled model to the Brazilian Regional Atmospheric Modeling System (BRAMS). Model results are compared with satellite-driven observations and a flux tower measurement in central Amazon. Our results indicate that the modeled EDBRAMS precipitation over Amazonia replicates the observed patterns of the Tropical Rainfall Measuring Mission (TRMM) from 2001 to 2009. Total Water Storage Change (TWSC) anomalies from the ED model at the Paraná River basin shows a better agreement with the Gravity Recovery And Climate Experiment (GRACE) satellite observation from 2002 to 2008, as compared to the Global Land Data Assimilation System (GLDAS)/NOAH model. The Nash-Sutcliff model efficiency coefficient improved from 0.50 (GLDAS/NOAH vs. GRACE) to 0.65 (ED vs. GRACE). We also evaluate the modeled evapotranspiration (ET) against the flux tower measurement. Our study affirms the capabilities of the ED model in simulating the Amazon hydrological cycle, which helps investigate its sustainable thresholds with various land-cover and climate change scenarios.

  8. Sea-level-- and gas-hydrate-controlled catastrophic sediment failures on the Amazon Fan

    SciTech Connect

    Maslin, M.; Mikkelsen, N.; Vilela, C.; Haq, B.

    1998-12-01

    The architecture and Quaternary history of the massive and highly structured Amazon Fan has been reconstructed using sediment recovered by Ocean Drilling Program Leg 155. Huge regional mass-transport deposits make up a significant component of the Amazon Fan. These massive mass-transport deposits each cover an area over 15,000 km{sup 2} (approximately the size of Jamaica), reach a maximum thickness of 200 m, and consist of {approx}50,000 Gt of sediment. Analysis of both benthic foraminiferal fauna and the sediments indicates that the mass-transport deposits originated at a water depth of between 200 and 600 m on the continental slope, which is at least 200 km lateral to a