Solimoes River Research Articles

Abundancia y diversidad de peces predadores en lagos de Várzea de la Amazonia Central.

La diversidad de peces en los lagos de várzea de la Amazonia es favorecida por la alta heterogeneidad espacial y por la interconectividad entre estos lagos y el canal principal del rio, regulada por el ciclo hidrológico. La depredación se tiene como un factor determinante en la estructuración de las asambleas de peces de la región neotropical. El objetivo de esta investigación fue estimar la abundancia y diversidad de peces predadores que habitan lagos de várzea en la región del medio río Solimoes, Amazonia Central de Brasil. Las colectas fueron realizadas en los meses de mayo y agosto de 2011, correspondientes a ños períodos hidrológicos de llenado y vaciado, en tres lagos de várzea en río Solimoes: lago Padre (S03°19’66,1/W59°93’14,8), Camaleão (S 03°66’43,23; W60°90’98,16) y lago Cacauzinho (S 03°66’86,14; W60°87’11,98). Para La captura se utilizaron redes agalladeras, dispuestas en las áreas de agua abierta y bosque inundado. El tiempo de muestreo fue de 48 horas en cada lago. Se colectaron 1.813 especímenes de peces predadores, distribuidos en 26 especies, 11 familias y 5 órdenes. Characiformes fue el orden más abundante con un número mayor de representantes en la familia Characidae. Las especies más abundantes fueron Pygocentrus nattereri (963 individuos) y Serrasalmus rhombeus (301 individuos). Las estimativas de diversidad, equitatividad y dominancia presentaron baja variación entre los períodos hidrológicos y hábitats. Apenas la riqueza de especies fue diferente entre las fases de llenado y vaciado de l ciclo hidrológico.

Screening e dose-resposta de herbicidas à malva e juta

A produção de fibra de malva (Urena lobata) e de juta (Corchorus capsularis) é demandada pela indústria como matéria prima na produção de telas, cordas, capas de livro entre outras aplicações. O ciclo de produção desta fibra é uma atividade sustentável, pois usa recursos renováveis das várzeas do Rio Solimões no Amazonas. O manejo da cultura aliado ao controle de plantas daninhas são condições para as espécies expressarem o máximo potencial produtivo. O uso de herbicidas seletivos se constitui numa alternativa eficiente e economicamente viável a esta finalidade. O objetivo desta pesquisa foi avaliar a seletividade de herbicidas por meio de screening e a dose-resposta destes as duas espécies produtoras de fibras naturais. Dois experimentos foram conduzidos em casa de vegetação: o primeiro na forma de screening para avaliar herbicidas aplicados em pós-emergência como bentazon, clethodim, fluazifop-p-butil, fomesafen, linuron, oxyfluorfen e sulfentrazone nas doses recomendadas para outras culturas; e o segundo, os herbicidas clethodim e fluazifop-p-butil, que foram seletivos à juta e à malva, em 7 doses. Os herbicidas bentazon, linuron, fomesafen, oxyfluorfen e sulfentrazone causaram morte de todas as plantas, enquanto o clethodim e fluazifop-p-butil foram moderadamente fitotóxicos. As duas espécies foram mais tolerantes ao fluazifop-p-butil que ao clethodim.

Energy at the Junction of the Rivers Negro and Solimões, Contributors of the Amazon River, in the Brazilian Amazon.

The Negro and Solimoes rivers join in front of the Brazilian city of Manaus to form the Amazon River. This “meeting of the waters” is a natural phenomenon of great aesthetic beauty that has been the focus of attention of researchers all over the world in various scientific fields. The waters of the Negro are darker and warmer, while the waters of the Solimoes are lighter and cooler. These waters have very different characteristics and remain without mixing, flowing side by side for several miles. Some reports indicate a temperature gradient between the waters of the order of 6°C, which can be used in conjunction with very high flow rates delivered by the two rivers, with a heat engine operating on a thermodynamic cycle to provide electricity. This review paper identifies this energy resource and presents a preliminary assessment of the potential for power generation. A realistic assessment of the potential points to an available power of about 1 GW. It is clear that further studies are needed to accurately assess the available thermal gradient and its variation over time, to move forward in the design of the power converter, and to establish an appropriate location for a power plant.

NA MARGEM E À MARGEM: ARQUEOLOGIA AMAZÔNICA EM TERRITÓRIOS TRADICIONALMENTE OCUPADOS

Este artigo descreve o levantamento de sítios arqueológicos em territórios tradicionalmente ocupados na Amazônia. O que é imprescindível para o nosso acesso aos locais é o conhecimento territorial dos ocupantes. Ao relatar o processo de desenvolvimento de pesquisas arqueológicas nas margens de três dos principais rios da Amazônia (Tapajós, Madeira e Solimões), pretendemos explorar as variadas relações existentes entre as comunidades tradicionais e os recursos arqueológicos existentes em seus territórios, desafiando conceitos estanques do significado de patrimônio. Propomos que arqueólogos busquem ser parceiros das comunidades tradicionais, as quais têm contribuições inestimáveis para a geração do conhecimento. Palavras-chave: Arqueologia na Amazônia, prospecção arqueológica, comunidades tradicionais, rios Tapajós, Madeira e Solimões, Lago Tefé.

Source area and seasonal87Sr/86Sr variations in rivers of the Amazon basin

We report the results of a detailed study of dissolved Sr isotopes in the Solimoes and Beni-Madeira Rivers of the Amazon basin. This study developed data collected over 8 years indicating large spatial and temporal variations in dissolved Sr isotopes among the rivers of the Amazon basin. The large 87Sr/86Sr variations were found to be correlated with the geology of the source areas of the suspended sediments. The Beni-Madeira River displays a high average 87Sr/86Sr ratio and large 87Sr/86Sr fluctuations during the hydrological cycle. This large average value and fluctuations were related to the presence of Precambrian rocks and Ordovician sediments in the source area of the suspended sediment of the river. In contrast, the Solimoes River displays a narrow range of Sr isotope ratio variations and an average value close to 0.709. This river drains mostly Phanerozoic rocks of northern Peru and Ecuador that are characterized by low Sr isotope ratios. The isotopic fluctuations in the Beni-Madeira River were observed to propagate downstream at least as far as Obidos. This signal is characterized by an inverse relationship between the concentration of elemental Sr and its isotopic ratios. We further demonstrate that the Sr isotopic composition and content in the Beni-Madeira River is controlled by suspended sediments derived from the Andes. Despite draining areas underlain by Precambrian rocks and having high 87Sr/86Sr ratios, such rivers as the Negro and Tapajos play a minor role in the total Sr budget of the Amazon basin. Copyright © 2013 John Wiley & Sons, Ltd.

INFLUENCE OF THE HYDROLOGICAL CYCLE ON PHYSICAL AND CHEMICAL VARIABLES OF WATER BODIES IN THE VÁRZEA AREAS OF THE MIDDLE SOLIMÕES RIVER REGION (AMAZONAS, BRAZIL)

The variation in water level in the Amazon varzea promotes cyclical isolation or union of various bodies of water. Among these, lakes and channels are the most relevant. Due to their cyclical geographic isolation, and even due to the often distinct origin of their waters, these environments showed limnological features which also vary from those bodies of water located outside the varzea setting. The objective of this study is to demonstrate the differentiation of the types of water bodies present in the Middle Solimoes area, inside and outside of the floodplain areas, by segregating their main physical and chemical parameters. It also aims to evaluate the influence of the flood pulse on these parameters in these types of bodies of water. In order to do this, expeditions were conducted monthly from 2004 to 2011, at twelve sampling stations located in different types of water bodies, including canals and lakes within the Mamiraua Sustainable Development Reserve, the Solimoes River and the mouth of the Tefe River. The parameters monitored were electrical conductivity, temperature, dissolved oxygen, oxygen saturation, pH and transparency. To analyze the data obtained from this monitoring, descriptive statistics and clustering were used. The temperature of the bodies of water in the Mamiraua RDS showed mean values ranging between 27.1 and 30.8 ° C. Dissolved oxygen concentrations resulted in average concentrations of from 0.3 to 0.6 mg.L-1, with a high standard deviation. Transparency was between 0.4 and 1.6 m. Electrical conductivity ranged between 87 and 204 μS.cm-1 in white waters and 10 - 21 μS.cm-1 in black/mixed waters of the mouth of the Tefe River. From the groupings obtained, it was possible to state that the lakes behave like independent bodies of water in the daught season, and during the season of high water they form a large grouping, suggesting a greater homogenization. An analysis of principal components with the parameters confirmed their relevance in the structuring of groups or types of bodies of water identified in the region. The pH distinguished itself as the main differentiating factor between white and black waters, followed by water transparency. Electrical conductivity was the main parameter responsible for the differentiation of water in different periods of the hydrological cycle, followed by water transparency. The variation in water level during the hydrological cycles evaluated over seven years of monitoring influenced the water quality in the lakes and canals of Mamiraua Sustainable Development Reserve and the Solimoes and Tefe Rivers. The parameters transparency, dissolved oxygen, and conductivity varied more markedly between the periods of draught and high water.

800 anos de ocupação da Tradição Polícroma da Amazônia: um panorama histórico no Baixo Rio Solimões

Este artigo apresenta dados sobre o processo de ocupação de sítios com depósitos associados à cerâmica Guarita, da Tradição Polícroma da Amazônia, na região do Baixo Rio Solimões, no Amazonas. Essas ocupações estão relacionadas aos últimos grupos ceramistas que se estabeleceram na região desde o século VIII d.C. até o século XVI d.C. Por meio do exame do contexto arqueológico de sete sítios pré-coloniais e da análise tecnomorfológica da cerâmica, foi possível identificar semelhanças e diferenças entre duas áreas do Baixo Rio Solimões. A partir disso, propõe-se uma hipótese para a história de ocupação dos grupos ceramistas vinculados à Tradição Polícroma da Amazônia.

Local Networks of knowledge, production, and circulation of handcrafted objects made by artisans in the Amanã Reserve

This paper refers to the knowhow and skills involved in the production of artisanal objects in three communities located in the Amana Sustainable Development Reserve (RDSA) in the middle Solimoes river: Belo Monte, Sao Jose do Urini and Sitio Cachimbo. When analyzing techniques and the traditional knowledge associated to handcrafting, we have identified that the process of production and circulation of objects is carried out using productive strategies that involve different social agents related by kin and compadrio bonds. Ethnographic studies focus on qualitative methodologies, emphasizing participatory observation. The aim of this article is to describe and analyze networks related to production and circulation of artisanal objects, their productive strategies and the context of the social transmission of knowledge. An informal work contract of mutual help (trabalho de meia) is one of the pillars of handcrafting. This productive arrangement enables access to natural resources used as raw materials in the making of handicrafts for domestic use and sale. Teaching and learning processes are fundamental components for the reproduction of knowledge between generations.

Atividade Larvicida de <i>Bacillus sphaericus</i> 2362 contra <i>Anopheles</i> sp. (Diptera, Culicidae) em rios do Amazonas, Brasil

Studies addressing vector control are important due to the high incidence of malaria in Amazonia. The present study aims to analyze the larvicidal activity of Bacillus sphaericus 2362 against anophelines in Amazonia. Laboratory assays testing B. sphaericus 2362 as lyophilised in waters collected from anopheline breeding sites in the Solimoes and Negro Rivers, were carried out on Anopheles nuneztovari larvae. A field test using a Bacillus sphaericus 2362 formulation, named Spherico, was applied on Anopheles species in the natural breeding sites in the Solimoes and Negro Rivers. Laboratory bioassay showed that, the B. sphaericus tested dosage are not efficient in the control of A. nuneztovari larvae in black water, with CL50= 0.563ppm, compared to the larvicide dosage found in white water presenting CL50= 0,859 ppm, in the 24 h reading, with a significance of p>0.05. Regression straight lines point out that in the highest B. sphaericus 2362 dosages (1 ppm, 0.5ppm), there was higher mortality rate against this target species in black water, than that found in white water. In the field assays the Anopheles predominant species, both in black and white water breeding sites, were A. triannulatus (74%) and A. albitarsis (22%). The present study showed a decrease in the man hour larval index (MHLI) values following the larvicide application, both, in Solimoes and Negro River breeding sites, as compared to that found prior to the treatment. The Solimoes River breeding site, presented a value of MHLI equal to 72% wherever the highest Spherico formulation (0.2mL/m2) was applied, and MHLI of 18% where the lowest larvicide dosage was applied (0.025mL/m2), both values were found in the 48 h evaluation. In the Negro River, the MHLI was 53 and, 11%, for the highest and lowest Spherico tested dosage. The activity of the B. sphaericus 2362 and Spherico formulation on anopheline larvae differed significantly between the two water types tested (Solimoes and Negro Rivers).

Caracterização e classificação de gleissolos da várzea do rio Solimões (Manacapuru e Iranduba), Amazonas, Brasil

As várzeas do rio Solimões são áreas inundáveis com predomínio de Gleissolos, onde se estabeleceu grande parte da população rural do Estado do Amazonas. Os objetivos deste trabalho foram caracterizar e classificar cinco perfis de Gleissolos, distribuídos em três áreas da bacia do Médio Amazonas, localizados nas várzeas dos municípios de Manacapuru e Iranduba. Após a descrição morfológica dos solos, coletaram-se amostras dos seus horizontes para caracterização física, química e mineralógica. Similarmente, todos os perfis apresentaram expressiva gleização na matriz do solo, com cores cinzenta a cinzenta-esverdeada, nos horizontes mais superficiais, e cinzenta-clara a cinzenta-escura, nos subsuperficiais, denotando a redução do ferro. Os teores mais elevados da fração areia em horizontes de subsuperfície indicaram presença de diferentes camadas de deposição fluvial, enquanto os elevados teores de silte evidenciaram a natureza sedimentar recente e o baixo grau de desenvolvimento pedogenético desses solos. Os cátions predominantes nos solos foram Ca2+ e Mg2+, que apresentaram porcentagens de sódio trocável (PST), com amplitude de variação entre 0,70 e 2,09. Os valores de carbono orgânico encontrados foram menores de 80 g kg-1, apresentando a natureza mineral dos sedimentos recém-depositados. A composição mineralógica da fração argila revelou presença significativa de argilominerais 2:1, mas sem grande variabilidade entre os perfis. Esses resultados refletiram-se em elevada soma e saturação por bases, caracterizando solos eutróficos e com argila de atividade alta.

Diagnóstico por Teledermatologia em paciente do Alto Rio Solimões: um caso de escabiose crostosa

Teledermatology uses telecommunication technology and informatics on dermatologic practice without the presence of a specialist. This paper describes the diagnostic process of a Crusted Scabies (Norwegian Scabies) case in an elderly patient from the Alto Solimoes River region using teledermatology resources. Moreover, the authors discuss the progress of these technologies, which allow healthcare assistance for those living in remote indigenous and riverine communities, particularly in isolated areas of the Legal Amazon where many diseases are neglected or underdiagnosed.

Community-Based Freswater Turtle Conservation In Middle Solimões River, AM, Brazil.

In middle Solimoes River the longest-running initiative of turtle community-based protection ( Podocnemis sextuberculata, P. unifilis and P. expansa ) occurs in the Mamiraua Reserve. This study aimed to compile and analyze existing information on the community-based conservation of turtles in this region and discuss the effectiveness of this strategy for generation of scientific data and conservation purposes. We analyzed available information and compared it with data obtained through participant observation. In the last years turtle conservation expanded from beaches into lakes. Despite this improvement, data collected from 2009 to 2011 indicate a reduction in the number of P. sextuberculata nests, which could be related to overestimation of the number of nests in previous years; decrease in the nesting population; or natural phenomena. On the other hand, data show a gradual increase in the number of P. expansa nests. Our analysis suggest that data generated by a participatory monitoring system is limited to general reproductive data and more specific data collection must be accompanied by a technical team. Community-based conservation, despite its limitations, is a valid strategy for turtle conservation, as all nests would likely be preyed upon by humans, if nesting areas were not protected and guarded by local inhabitants.

An initial assessment of drought sensitivity in Amazonian fish communities

The Amazon River Basin encompasses the world’s largest remaining tropical rainforest, and the largest freshwater system with the highest fish species diversity on earth, but global climate change is predicted to cause the loss of 7–12% of fish species by 2070. The severe drought anomaly of 2005, caused by warming of Atlantic surface waters, provided a unique opportunity to examine the impact of a major climatic disturbance on a tropical fish assemblage. We monitored fish species diversity in six Brazilian floodplain lakes along the Solimoes River from 2004 to 2007 (before, during, and after drought). Statistical analysis revealed changes in species composition of these lakes following the drought, with both positive and negative responses observed. The response to drought was not uniform among species with regard to trophic guild or migratory behavior. SIMPER analysis showed that planktivores on the average increased in abundance in the years following the drought, carnivores and omnivores decreased, and herbivores and detritivores increased. Some of these changes were transitory, others persisted through monitoring. Migratory species disproportionately increased in abundance post-drought compared to non-migratory species. Interlake (β) diversity of fish declined during the drought year, indicating that lakes were becoming less heterogeneous in species composition, but showed a trend toward recovery of pre-drought level in the following years. According to both global climate change models and recent experience, the intensity and frequency of droughts in this region of the world is increasing. Given the sensitivity of resident fish species to the single, short-term, perturbation reported here, assessment of how tropical freshwater fish populations respond to drought will be crucial to understanding the consequences of this kind of perturbation to these communities and to the human inhabitants who depend upon this important protein source.

Genetic Diversity in <i>Cichla monoculus</i> (Spix and Agassiz, 1931) Populations: Implications for Management and Conservation

Problem statement: The object of this study was to examine the genetic structure and gene flow in Cichla monoculus populations in seven varzea lakes of the Solimoes River using Randomly Amplified Polymorphic DNA (RAPD) markers, to monitor the region where petroleum is transported in the Amazon basin. Approach: The loss of genetic diversity is one of the main factors leading to reduced evolutionary potential in species of fish. In this context, this paper seeks to understand how the influence of the stretch of pipeline in the Solimoes River between the cities of Manaus-Coari influences the genetic structure of C. monoculus. For this we measured the level of genetic diversity and structure of the species in the studied stretch. Results: Proportions of polymorphic loci varied from 8.7-39.7% in analyzed populations. Low heterozygosis levels were detected (He = 0.1652) and highly structured populations in the seven lakes with low gene flow (Nm = 0.7025) among all fish studied. Unexpected differentiation was found between fishes among the lakes. Fish populations from lakes closest to Manaus (human population of ∼2 million) are different from those occurring in lakes closest to the Coari region (close proximity to petroleum barge transfer terminals). Conclusion/Recommendations: Differentiation can be explained by natural causes. This study identifies antropogenic activities influencing this species overall. Since industrial fishing is prevalent due to the high economic value of C. monoculus. Also, this species posses behavioral characteristics that are desirable in sports fishing. Management and conservation of this species will be necessary in the near future to recover genetic variability levels in each lake and allow gene flow among them. Further studies are needed to better understand the differentiation among populations.

Isolation of microsatellite loci in the Amazon sailfin catfish Pterygoplichlhys pardalis (Castelneau, 1855) (Teleostei: Loricariidae)

Pterygoplichlhys pardalis is an important freshwater ornamental fish in the Amazon Basin. Studies involving populations of P. pardalis are of great importance for the conservation and management of this species. We developed nine microsatellite loci and applied them to investigate the genetic variation of 20 wild individuals from floodplain lakes of the Solimoes river. The number of alleles per locus ranged from 2 to 12, with an average of 6.6. The observed and expected heterozygosity values ranged from 0.400 to 0.923 (average 0.706) and from 0.358 to 0.895 (average 0.692), respectively. The value of f ranged from −0.532 to 0.467 (average 0.032). One locus (Pp07) significantly deviated from Hardy–Weinberg equilibrium after Bonferroni correction (P: (5 %) < 0.006). No significant linkage disequilibrium was detected. These microsatellite loci will contribute towards studies of genetic diversity and conservation of P. pardalis.

Cerâmicas da Tradição Borda Incisa/Barrancóide na Amazônia Central

A sequência crono-estilística ligada à variabilidade cerâmica na Amazônia central tem sido foco de debates há tempos. Algumas hipóteses clássicas sobre a ocupação humana na área são agora reavaliadas através de uma ampla gama de dados empíricos aliada a um novo corpus teórico-analítico. Este artigo apresenta parte dos resultados das análises cerâmicas levadas a cabo por uma pesquisa de doutorado no âmbito do Projeto Amazônia Central (MAEUSP). Os dados aqui apresentados apontam maneiras de se reacessar o uso de conceitos caros à arqueologia brasileira, como as fases e tradições, sob uma perspectiva diferenciada. Na área de confluência dos rios Negro e Solimões, tais conceitos permitiram a construção de uma cronologia de ocupação baseada no entendimento das relações existentes entre as fases Açutuba, Manacapuru e Paredão, relacionadas à Tradição Borda Incisa/Barrancóide da Amazônia.

Reply to the Comment made by C. Gualtieri on “Turbulent mixing in the Amazon River: The isotopic memory of confluences”, by J. Bouchez, E. Lajeunesse, J. Gaillardet, C. France-Lanord, P. Dutra-Maia and L. Maurice

C. Gualtieri raises three interesting points as a follow-up on our contribution reporting significant chemical and isotopic heterogeneities in a cross-section of the Solimoes River. These points are (1) the potential additional interpretations for the derived value of transverse turbulent diffusivity, (2) the validity of both flow depth and width as characteristic length scales for the transverse turbulent diffusivity coefficient and (3) amore “parametric” evaluation for the characteristic distance of lateral mixing downstream from a confluence in a large river. While we acknowledge the relevance of C. Gualtieri's comments, here we would also like to emphasize the current lack of a proper theoretical description of turbulentflows in rivers (and of the related properties, e.g. transverse diffusion). Therefore, a reliable description of processes such as lateral mixing, as well as a precise and quantitative prediction of the corresponding metrics, is still hampered by this gap of knowledge. In more details, regarding the three items discussed by C. Gualtieri:

HELMINTOS PARÁSITOS DE SEMAPROCHILODUS INSIGNIS JARDINE, 1841 (OSTEICHTHYES: PROCHILODONTIDAE) DEL CENTRO DE LA AMAZONÍA (BRASIL), Y SU RELACIÓN CON EL HOSPEDERO

Este estudio describe la fauna de parásitos y la relación hospedero-parásito en Semaprochilodus insignis Jardine, 1841, encontrados en el Lago Coari, tributario en el centro del Rio Solimões (estado del Amazonas, Brasil) en la Amazonia central. De 56 peces examinados, el 23,2% tenía las branquiasparasitadas por Gyrodactylus gemini Ferraz, Shinn y Sommerville 1994 (Monogenoidea: Gyrodactylidae) y el intestino por Procamallanus inopinatus Travassos, Artigas y Pereira, 1928 (Nematoda: Camallanidae). La tasa más alta de infección fue causada por G. gemini. El factor de condición relativa (Kn) no se vio afectado por el parasitismo, pero había una correlación positiva entre la intensidad de los helmintos y Kn, y la longitud total de los hospederos. Este es el primer registro de la fauna de parásitos de S. insignis con la ocurrencia de G. gemini y P. inopinatus para este hospedero Neotropical de la Amazonía.

STANDARD OF MEASUREMENT AMONG LOCAL INHABITANTS IN THE MIDDLE SOLIMÕES, OCCIDENTAL AMAZONIA, AND ITS USE IN MORPHOMETRICS OF AMAZONIAN MANATEE (&lt;i&gt;Trichechus inunguis&lt;i/&gt; NATTERER, 1883)

This study analyzed measurements of Amazonian manatees taken by local people on the middle Solimoes river, converting the length of the inch of local people to the metric system, and verifying the existence of a difference between the value of local men´s inch in metric scale and the international metric standards for the measurement. Field trips were taken to the Mamiraua and Amana reserves, in Central Amazonia, to confirm the use of the inch as a measurement unit. Interviews were applied and the inches of 508 adult males resident in the town of Tefe and in the Mamiraua and Amana reserves were measured. The sample consisted of persons whose experience with manatee capture ranged from three to 43 years. The average value for the local inhabitant inch was 21.71 cm. A Student’s t-test applied to the result demonstrated a highly significant difference in relation to the value of the inch described in the literature. The use of morphometric data contributed by local people, in growth studies of Amazonian manatees must weigh the value of 21.71 cm in the conversion of the local´s inch to the metric scale, considering an error of 0.05 cm for each converted inch measure.

Influência do hábitat na estrutura da comunidade de macroinvertebrados aquáticos associados às raízes de Eichhornia crassipes na região do Lago Catalão, Amazonas, Brasil

Por possuírem ciclos de vida curtos, os macroinvertebrados aquáticos podem responder rapidamente às modificações ambientais, alterando a estrutura das suas populações e comunidades. O objetivo deste estudo foi determinar se há relação entre a composição de macroinvertebrados aquáticos associados a bancos de Eichhornia crassipes o gradiente de condutividade elétrica da água e a biomassa das raízes destes bancos. No pico da cheia de 2005, 21 bancos de macrófitas aquáticas flutuantes dominados por E. crassipes foram amostrados no rio Negro (baixa condutividade &lt; 30 µS cm-1), na confluência entre os rios Negro e Solimões (média condutividade &gt; 30 µS cm-1 e &lt; 50 µS cm-1), e no rio Solimões (alta condutividade &gt; 50 µS cm-1). Foram encontrados 1707 macroinvertebrados aquáticos, distribuídos em 14 ordens e 35 famílias. A abundância de invertebrados aquáticos foi maior em bancos na confluência das águas. O aumento da biomassa das raízes de E. crassipes levou a um aumento da abundância e da riqueza de famílias de macroinvertebrados. A abundância dos coletores-catadores, coletores-filtradores e raspadores variou com o tipo de água, e apenas a abundância dos coletores-catadores e coletores-filtradores variou em função da biomassa das raízes. A riqueza de famílias dos raspadores variou em função do tipo de água. A organização da comunidade depende do gradiente de biomassa de raízes, indicando a importância da estrutura do hábitat para o estabelecimento dos macroinvertebrados.