Two new miniature translucent catfish species of the rare genus Tridens (Siluriformes: Trichomycteridae) from the Madeira River basin, northern Brazil.

Two new miniature species of the trichomycterid genus Tridens are described from the Madeira River drainage, Acre and Rondônia States, Brazil. Until this work, Tridens was a monotypic genus composed solely of Tridens melanops, from the Putumayo/Içá River drainage, upper Amazonas River basin. Tridens vitreus sp.n. is known from upper and middle Madeira River drainage and differs from all other congeners by the lack of pelvic fins and girdle and by vertebra and dorsal-fin ray counts. Tridens chicomendesi sp.n. is known from Abunã River, middle Madeira River drainage and is distinguished from all other congeners by the number of vertebrae, dorsal-fin ray count and anal-fin base colouration pattern. Tr. chicomendesi sp.n. is further distinguished from T. vitreus by a combination of character states regarding the position of urogenital opening, dorsal-fin position, anal-fin position, maxillary barbel length, number of premaxillary teeth, number of dorsal-fin rays, number of anal-fin rays, number of lateral-line system pores, frontal bone anatomy, degree of ossification of maxilla, anatomy of quadrate-hyomandibular joint, size of posterodorsal process of hyomandibula, length of opercular patch of odontodes, number of interopercular odontodes, proportion of upper hypural plate cartilage relative to its area ; by the absence of a proximal, distal and ventral cartilages on ventral hypohyal; by the absence of a lateral process on basibranchial 4; by the presence of a cartilage block on the lateral process of autopalatine, the presence of a well-developed ossification on proximal margin of ventral hypohyal, the presence of hypobranchial foramen; and by the presence of an anterior cartilaginous joint between quadrate and base of posterodorsal process of hyomandibula. This work represents the first species description for the subfamily Tridentinae in more than 30 years and for the genus Tridens since its original description in 1889.

Brazil's Amazon Oxygen Crisis: How Lives and Health Were Sacrificed During the Peak of COVID-19 to Promote an Agenda with Long-Term Consequences for the Environment, Indigenous Peoples, and Health.

In January 2021, oxygen supplies in the Amazon region's largest city were allowed to run out at the peak of the second wave of the COVID-19 epidemic, shocking the world as hospital patients expired for lack of this basic medical resource in Manaus, which during the first COVID-19 wave had become the world's first city to bury its dead in mass graves. Brazil's authorities used this tragedy to further a political agenda that implies enormous environmental and human-rights consequences. Transport of oxygen was used to promote building a road that, together with its planned side roads, would give deforesters access to much of what remains of Brazil's Amazon Forest. Here, we demonstrate that the logistical strategy adopted by the Jair Bolsonaro administration's Ministries of Health and Infrastructure to bring oxygen to Manaus was the worst possible choice, and the foreseeable delay in the arrival of oxygen cost hundreds of lives. Rather than sending trucks to carry oxygen on the nearly impassible Highway BR-319 during the rainy season, the most appropriate transport option was barges on the Madeira River. As oxygen supplies dwindled in Manaus, the families of wealthier COVID-19 victims scrambled to buy the few remaining cylinders at prices out of reach for those in poorer (and often ethnically distinct) economic strata. Ethnic health disparities are aggravated by both the direct consequences of the oxygen crisis and, on the longer term, by the consequences of the highway project that political use of the crisis materially advanced.

A new species of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), from the Madeira River basin, with a discussion of historical biogeography of western Amazonas and Paraguay River basins.

A new loricariin species of Sturisoma is described from the Cautário, Guaporé, Mamoré, Machado and Soteiro rivers, Madeira River basin, in Bolivia and Brazil. The new species is distinguished from its congeners by the presence of a middorsal longitudinal, thin dark brown stripe on the caudal peduncle, extending from two or three plates posterior to the dorsal-fin base, reaching the origin of the caudal fin, or one or two plates anterior to the origin of the caudal fin; small squarish anteriormost abdominal plates; and a middorsal longitudinal dark-brown stripe from first predorsal plate to near the dorsal-fin origin. Furthermore, the new species is diagnosed from congeners by plate morphology, counts on the median series, coalescent plates and ventrolateral thoracic plates, in addition to measurements related to body and head structures. An analysis of genetic distances using cytochrome C oxidase subunit 1 gene marker of the mitochondrial genome between the new species and several congeners is presented, in addition to a likelihood analysis to illustrate the position of the new taxon within Sturisoma. An identification key for species of the genus currently recorded at the upper Amazonas River basin is provided.

Nature-based solutions for improving navigation reliability on the Madeira River, Brazil.

The Madeira River Navigation and Improvement Project provides a unique opportunity to incorporate nature-based solutions (NbS) into the built environment to promote sustainable communities and water resources infrastructure. The Madeira River has no major physical interventions (river training structures, navigation locks and dams, etc.) to improve navigation, and so is one of the world's last remaining undeveloped megarivers that exhibits natural morphological processes. The objective of this study is to create a safe, reliable, and sustainable navigation channel in the Madeira River. This is being accomplished by designing navigation improvement measures that leverage natural geomorphic processes of the river while minimizing conventional engineering practices that alter the river's morphology. To meet this objective, fluvial geomorphology analysis and hydrodynamic modeling studies have been performed to improve understanding of the morphological behavior of the system. Measures that incorporate beneficial reuse of dredged sediment within the system are being prioritized and incorporated into the study's design. Natural processes are being leveraged through the implementation of an adaptive management process to shape the navigation channel by incorporating the use of dynamic structures using natural local materials (e.g., large woody debris already in the system), a direct application of NbS in practice. This process includes extensive stakeholder collaboration and utilizing nature's energy to balance navigation, ecological, and social benefits along the Madeira River. This project demonstrates that nature-based approaches not only provide navigation benefits but can also provide ecological and social benefits in ways that are sustainable in the long term, consistent with United Nations Sustainable Development Goals (SDGs) and the International Union for the Conservation of Nature's global standard for NbS. Integr Environ Assess Manag 2022;18:115-122. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Evaluation of Mansonia spp. Infestation on Aquatic Plants in Lentic and Lotic Environments of the Madeira River Basin in Porto Velho, Rondônia, Brazil.

The females of Mansonia are voraciously hematophagous. The spiracular apparatus of the immature, larval, and pupal forms is adapted to perforate submerged aquatic vegetation, from whose aeriferous aerenchyma they obtain the oxygen necessary for breathing. The proliferation of aquatic plants, in some cases linked to anthropic modifications that reduce water flow and/or increase organic matter content, may therefore contribute to the spread of these mosquitoes. This study aims to assess the presence of immature individuals of Mansonia in different aquatic plants of the Madeira River basin in 10 lentic and lotic environments and correlate their population density with abiotic factors such as water pH, dissolved O2, conductivity, and temperature. The sampling lasted from February 2016 to June 2018, a 29-month period during which 31,287 specimens belonging to the genus Mansonia were captured. Of the 12 species of macrophytes inspected, Eichhornia crassipes made up 70.1% of the samples. Lentic environments accounted for 58.9% of the samples and lotic environments for 41.1%. Immature individuals were most commonly found on Eichhornia crassipes, with this plant accounting for an average of 96.2% of all individuals, with a percentage ranging between 58.2% and 77.1% in different breeding areas. Only at the Foz do Igarapé Jirau site was a different distribution observed, with the number of aquatic plants more nearly equal: 83.3% of the larvae were found in Eichhornia crassipes, 9.2% in Ceratopteris pteridoides, 3.6% in E. azurea, 2.0% in Salvinia sp., and 1.9% in Pistia sp. The greatest richness was found in Iguapé do Raul. Concerning the larval/plant relationship, although less frequent, E. azurea had a higher larval density of Mansonia spp. It is important to emphasize that this finding may indicate a possible selection for this plant. Egg deposition by Mansonia spp. was more abundant in sample areas with Eichhornia crassipes and Pistia sp. The number of specimens collected was positively correlated with temperature, pH, and conductivity. These correlations showed a marked increase in the rainy season. Therefore, we were able to establish preliminary parameters of how environmental changes influence the ecology of this important genus of mosquitoes, the species of which are critical disease vectors.

Factors determining the structure of fish assemblages in Tarumã River, Jaru Biological Reserve, Machado River drainage, northern Brazil

ABSTRACT Few studies on fish assemblages and relations with environmental factors in aquatic systems in southeastern Amazonia have been carried out when compared to other areas in the Amazon. Therefore, which are the main environmental variables and processes responsible for structuring them remains unknown. We hypothesized that fish assemblages respond the variation in the physical-chemistry variables between seasons of the hydrological cycle in a pristine river in the Amazon. The study was performed on fish assemblages of the Tarumã River, Jaru Biological Reserve, Rondônia. Samplings were carried out in five sites along the river in March and September, 2015, which included fish collection and environmental data measurements. Principal component analysis was performed to ordinate the sites in high water and low water seasons, according to environmental variables. We used a similarity analysis in order to identify the individual contribution of species in hydrological period and a partial redundancy analysis for quantify the relative importance of environmental variables in the species composition. As predicted by our hypothesis, the species composition was influenced by dissolved oxygen and temperature. Myloplus rubripinnis, Serrasalmus compressus, and S. rhombeus were the most abundant during high water, while S. rhombeus, Myloplus lobatus, Prochilodus nigricans, and Hydrolycus armatus were the dominant species during the low water.

RESUMO Poucos estudos sobre assembleias de peixes de sistemas aquáticos do sudeste da Amazônia foram realizados quando comparado a outras áreas na Amazônia. As principais variáveis ambientais e processos responsáveis por sua estruturação permanecem desconhecidas. Nossa hipótese é que as assembleias de peixes respondem as variações das variáveis físico-químicas entre as estações do ciclo hidrológico em um rio preservado na Amazônia. O estudo analisou as assembleias de peixes do rio Tarumã, na Reserva Biológica do Jaru, Rondônia. As amostragens foram realizadas em cinco pontos amostrais ao longo do rio, em março e setembro de 2015, que incluiu coleta de peixes e medições de dados ambientais. A Análise de Componentes Principais ordenou os pontos amostrais nos períodos de cheia e seca, de acordo com as variáveis ambientais. Utilizamos uma análise de similaridade afim de identificar a contribuição individual de cada espécie em cada período hidrológico e uma análise de redundância parcial com o objetivo de quantificar a importância relativa das variáveis ambientais na composição das espécies. Conforme previsto por nossa hipótese, a composição de espécies do rio Tarumã é influenciada pelo oxigênio dissolvido e temperatura. Myloplus rubripinnis, Serrasalmus compressus e S. rhombeus foram mais abundantes durante o período de cheia, enquanto S. rhombeus, Myloplus lobatus, Prochilodus nigricans e Hydrolycus armatus foram as espécies dominantes no período de seca.

Taxonomic and functional turnover of Amazonian stream fish assemblages is determined by deforestation history and environmental variables at multiple scales

High rates of deforestation, either in the past or the present, affect many of the ecological processes in streams. Integrating deforestation history and the current landscape structure enhances the evaluation of ecological effects of land-use change. This is especially true when contemporary landscape conditions are similar but the temporal path to those conditions differs. One approach that has shown promise for evaluating biodiversity responses over time and space is the β-diversity partitioning, which combines taxonomic and functional trait-based approaches. We tested hypotheses related to stream fish assemblages' turnover in watersheds with different environmental conditions and deforestation histories. We sampled fish from 75 watersheds in the Machado River basin, Brazil, and environmental factors were quantified at multiple scales. Taxonomic turnover was higher than expected by chance, whereas functional turnover was lower than expected by the observed taxonomic turnover, indicating that deterministic processes are structuring these assemblages. The turnover, and the environmental factors differed among watersheds with different deforestation histories. Besides being scale-dependent, turnover patterns are also likely dependent on land use dynamics and involve time-lags.(AU)

Altas taxas de desmatamento, seja no passado ou no presente, afetam muitos processos ecológicos em riachos. Integrar o histórico do desmatamento à estrutura atual da paisagem melhora a avaliação dos efeitos ecológicos da mudança do uso do solo. Isto é especialmente verdadeiro quando as condições da paisagem contemporânea são semelhantes, mas seguiram trajetórias distintas. Uma abordagem promissora para avaliar as respostas da biodiversidade ao longo do tempo e espaço é a partição da diversidade-β, que combina abordagens taxonômica e funcional. Testamos hipóteses relacionadas à substituição das assembleias de peixes de riachos em microbacias com diferentes condições ambientais e histórias de desmatamento. Amostramos 75 microbacias na bacia do rio Machado, fatores ambientais foram quantificados em múltiplas escalas. A substituição taxonômica foi maior do que esperada pelo acaso, enquanto a substituição funcional foi menor do que o esperado pela substituição taxonômica, indicando que as assembleias são estruturadas por processos determinísticos. As substituições e fatores ambientais diferiram entre microbacias com históricos de desmatamento distintos. Além de serem escala-dependentes, os padrões de substituição provavelmente são dependentes da dinâmica do uso do solo, envolvendo defasagem temporal.(AU)

A new species of Dendropsophus (Anura, Hylidae) from southwestern Amazonia with a green bilobate vocal sac.

Recent studies have shown that species diversity of the South American frog genus Dendropsophus is significantly underestimated, especially in Amazonia. Herein, through integrative taxonomy a new species of Dendropsophus from the east bank of the upper Madeira River, Brazil is described. Based on molecular phylogenetic and morphological analyses, the new species is referred to the D. microcephalus species group, where it is differentiated from its congeners mainly by having a green bilobate vocal sac and an advertisement call comprising 1-4 monophasic notes emitted with a dominant frequency of 8,979-9,606 Hz. Based on intensive sampling conducted in the study area over the last ten years, the new species is restricted to the east bank of the upper Madeira River, although its geographic range is expected to include Bolivian forests close to the type locality.

Checklist of the fishes from Jamari River basin, in areas under influence of dams, Rondônia, Brazil / Lista das espécies de peixes da bacia do rio Jamari, em áreas sob influência de reservatórios, Rondônia, Brasil

Abstract: The Madeira River is the most extensive tributary of the Amazon River and has the largest diversity of fishes in the world. On its right bank, the Madeira River receives the Jamari River, in which the first hydroelectric power plant (HPP) in State of Rondônia, Samuel HPP, was built. Besides this, other dams were built in the Jamari River and its tributaries, however, the available information in the scientific literature about the ichthyofaunistic diversity of this basin is rare. This work aims to provide an ichthyofaunistic inventory in a region of the Jamari river basin, in the State of Rondônia, where three small hydropower plants (SHPs) were implemented. The ichthyofauna was sampled in 16 expeditions between August 2015 and December 2018. Gill nets and seine nets were used with different meshes, as well as longlines and cast nets at different times of the day. Additionally, 81 INPA lots of species from the Samuel HPP area of influence were reanalyzed. Fish were identified according to the specialized literature, as well as in consultations with experts of various taxonomic groups. Voucher specimens of the species were cataloged and deposited in the ichthyological collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (Nupélia) of the Universidade Estadual de Maringá. A total of 230 species were recorded, of which 22 were putative new species, 117 were added to the Jamari River basin and 28 to the Madeira River basin. The continuation of the studies in this section of the Jamari river basin is fundamental for analysis of local impact due to the presence of dams. Moreover, the addition of putative new species to the Madeira River basin indicates gaps in the knowledge of Neotropical ichthyofauna.

Resumo: O rio Madeira é o mais extenso afluente do rio Amazonas e possui a maior biodiversidade de peixes do mundo. Em sua margem direita, o rio Madeira recebe o rio Jamari, no qual foi construída a primeira usina hidrelétrica (UHE) do estado de Rondônia, a UHE Samuel. Além desta, outros barramentos foram construídos no rio Jamari e em seus afluentes, contudo são raras as informações disponíveis na literatura científica sobre a diversidade ictiofaunística desta bacia. O objetivo deste trabalho foi providenciar um inventário ictiofaunístico na região da bacia do rio Jamari, no estado de Rondônia, onde foram implantadas três pequenas centrais hidrelétricas (PCHs). A ictiofauna foi amostrada em 16 expedições entre os meses de agosto de 2015 e dezembro de 2018. Foram utilizadas redes de espera e arrasto com malhas de diversos tamanhos, além de espinhéis e tarrafas em diferentes períodos do dia. Adicionalmente, 81 lotes de espécies do INPA da área de influência da UHE Samuel foram reanalisados. Os peixes foram identificados de acordo com a literatura especializada, bem como em consultas com especialistas de diversos grupos taxonômicos. Exemplares testemunho das espécies foram catalogados e depositados na coleção ictiológica do Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura da Universidade Estadual de Maringá. Foram registradas 230 espécies, destas, 22 são possíveis espécies novas, 117 são acrescentadas à bacia do rio Jamari e 28 à bacia do rio Madeira. A continuação dos estudos neste trecho da bacia do rio Jamari é fundamental para análises de impacto local devido à presença de barramentos. Além disso, a adição de possíveis novas espécies à bacia do rio Madeira aponta lacunas no conhecimento da ictiofauna Neotropical.

Detecting population structure of Paleosuchus trigonatus (Alligatoridae: Caimaninae) through microsatellites markers developed by next generation sequencing.

We isolated and characterized 10 new microsatellites loci for Paleosuchus trigonatus using ION TORRENT Sequencing Technology. We tested the transferability of these loci to three related species of the subfamily Caimaninae, and used these bi-parental markers to test population structure and genetic diversity of two populations of P. trigonatus impacted by hydroelectric dam construction on the Madeira (N = 16) and Xingu (N = 16) rivers. We also investigated the transferability of these markers to three related species: Paleosuchus palpebrosus (N = 5), Caiman crocodilus (N = 6) and Melanosuchus niger (N = 6). The genetic diversity of P. trigonatus was low in both the Madeira (He: 0.535 ± 0.148) and Xingu (He: 0.381 ± 0.222) populations, but the loci were sufficiently polymorphic to be used in system of mating and kinship studies in P. trigonatus. DAPC analysis with our set of microsatellites loci was able to separate the four species of Caimaninae studied and to detect a shallow genetic structure between Madeira and Xingu populations of P. trigonatus. AMOVA and STRUCTURE analyses using locprior model corroborate this shallow genetic structure. These novel molecular markers will be also useful in conservation genetics and phylogeographic studies of P. trigonatus, since they improve our ability to monitor the putative effects of dams on the loss of genetic diversity and allow us to investigate population dynamics and microevolutionary processes that occurred in the species.

Survey of fish species from the Lower Roosevelt River, Southwestern Amazon basin / Levantamento de espécies de peixes do Baixo Rio Roosevelt, Sudoeste da Bacia Amazônica

Abstract: This study presents an inventory of the ichthyofauna of the lower Roosevelt River sub-basin and its associated tributaries. Fish sampling with fishing nets and measurements of environmental parameters of water occurred in November/2012 (rising water), February/2013 (flooding), May/2013 (falling water) and August/2013 (drought). Depth mean was 8.86 m, water transparency was 0.6 m, conductivity was 22.7 µS.cm-1, pH was 6.59, dissolved oxygen was 7.63 mg.l-1 and temperature was 28°C. The total estimated capture area was 68,829.6 m2 during 2,880 hours. The catch per unit Effort (CPUE) was 0.37 individuals m-2.day-1. Species were spatially aggregated in all sampling points and river water levels. A total of 5,183 individuals distributed in 7 orders, 29 families, 104 genders and 188 species were sampled in this survey. The diversity index was 4.121 and equitability index was 0.789. The Characiforms order was the most abundant with 106 species, followed by Siluriforms with 63 species and Cichliforms with 23 species. The most abundant species was Serrasalmus rhombeus (Linnaeus, 1766) with 327 individuals (5.9%), followed by Chalceus epakros (Cope, 1870) with 309 individuals (5.6%) and Acestrorhynchus microlepis (Schomburgk, 1841) with 250 individuals (4.5%). Trophicity was characterized by omnivorous (28.6%), piscivorous (14.3%), carnivorous (13.8%) and detritivorous (12.8%). According to IBAMA's regulation, 29.25% of captured species presents ornamental potential.

Resumo: Este estudo apresenta um inventário da ictiofauna da sub-bacia do baixo Rio Roosevelt e seus tributários associados. As coletas de peixes com malhadeiras e as medições de parâmetros ambientais da água ocorreram em Novembro/2012 (enchente), Fevereiro/2013 (cheia), Maio/2013 (vazante) e Agosto/2013 (seca). A média da profundidade foi 8,86 m, da transparência da água foi 0,6 m, da condutividade foi 22,7 µS.cm-1, do pH foi 6,59, do oxigênio dissolvido foi 7,63 mg.l-1 e da temperatura da água foi 28°C. A área total de captura estimada foi 68.829,6 m2 durante 2880 horas. A captura por unidade de esforço (CPUE) foi 0,37 indivíduos m-2.dia-1. As espécies foram espacialmente agregadas em todos os pontos de coleta e períodos de coleta. Um total de 5183 peixes em 7 ordens, 29 famílias, 104 gêneros e 188 espécies foram coletados. O índice de diversidade foi 4,121 e o índice de equidade foi 0,789. As ordens Characiforme, Siluriforme e Cichliforme foram as mais abundantes. As espécies Serrasalmus rhombeus Linnaeus 1766 com 327 indivíduos (5,9%), Chalceus epakros (Cope 1870) com 309 indivíduos (5,6%) e Acestrorhynchus microlepis Schomburgk 1841 com 250 indivíduos (4,5%) foram as mais abundantes. Os onívoros (28,6%), piscívoros (14,3%), carnívoros (13,8%) e detritívoros (12,8%) foram os indivíduos mais abundantes. De acordo com o IBAMA, 29,25% das espécies capturadas tem potencial ornamental.

Selenium Levels in the Whole Blood of Children and Teenagers from Two Riparian Communities at the Madeira River Basin in the Western Brazilian Amazon.

Selenium (Se) is an essential micronutrient that exerts multiple functions in the organism, and both its deficiency and excess can cause health impairments. Thus, it is important to monitor its levels in the population, especially in vulnerable groups, such as children from the Brazilian Amazon region, where there is a lack of information in this regard. The aim of this research was to study Se levels in the whole blood of children and teenagers (5-16 years old) from two riparian communities at the Madeira River (Cuniã RESEX and Belmont). Se level variations related to the communities' location, seasonality, diet, and body mass index (BMI) were assessed. Blood samples were collected in both communities for Se determinations, using ICP-MS and hemogram analyses, during May and September of 2011. Food frequency questionnaires were applied to assess consumption rates of specific food items. Non-parametric tests and linear multiple regressions were applied in the data analyses. Median Se levels were significantly higher during May (Cuniã RESEX 149 µg L-1; Belmont 85 µg L-1) compared to September (Cuniã RESEX 79 µg L-1; Belmont 53 µg L-1). No significant differences were found between the communities regarding BMI measurements and anemia prevalence. However, Se blood levels were significantly higher at the Cuniã RESEX compared to Belmont. In addition, the former showed higher fish and Brazil nut intakes, which may be the main Se sources for this community. These results contribute to a better understanding of Se reference levels for children and teenagers of Western Amazon riparian communities.

Sex-related mercury bioaccumulation in fish from the Madeira River, Amazon.

UNLABELLED: Sex plays an important role in the kinetics and dynamics of methylmercury in some animals. Although fish is the main source of mercury exposure to consumers, the role of sex in fish-Hg bioaccumulation is less known. We studied total Hg (THg) concentrations in 2538 samples (males=1052, females=1486) of fish from different trophic levels (herbivorous, planctivorous, detritivorous, omnivorous, carnivorous, piscivorous); for each species we made a post hoc estimation of the minimum number of samples required to detect variance-based differences between sexes. Only five of the 41 studied species showed significant difference between sexes; but, no consistent dominant pattern of THg concentrations favored either sex. When grouped by trophic levels, overall mean difference in THg concentrations between males and females were not statistically significant. Correlation analysis showed sex-dependent THg bio-accumulation as a function of condition factor was statistically significant and negative for all trophic levels (detritivorous, herviborous, omnivorous, planctivorous, carnivorous, and piscivorous). CONCLUSIONS: Sex is not the main driver of Hg bioaccumulation in most Amazonian fish species; however, studies have to consider the minimum number of samples required to ascertain sex effects on THg bioaccumulation. Therefore, neither the surveillance of environmental pollution nor the current food advisories based on muscle THg need to change because of fish sex.

Genetic structure and historical diversification of catfish Brachyplatystoma platynemum (Siluriformes: Pimelodidae) in the Amazon basin with implications for its conservation.

Brachyplatystoma platynemum is a catfish species widely distributed in the Amazon basin. Despite being considered of little commercial interest, the decline in other fish populations has contributed to the increase in the catches of this species. The structure, population genetic variability, and evolutionary process that have driven the diversification of this species are presently unknown. Considering that, in order to better understand the genetic structure of this species, we analyzed individuals from seven locations of the Amazon basin using eight molecular markers: control region and cytochrome b mtDNA sequences, and a set of six nuclear microsatellite loci. The results show high levels of haplotype diversity and point to the occurrence of two structured populations (Amazon River and the Madeira River) with high values for F ST. Divergence time estimates based on mtDNA indicated that these populations diverged about 1.0 Mya (0.2-2.5 Mya 95% HPD) using cytochrome b and 1.4 Mya (0.2-2.7 Mya 95% HPD) using control region. During that time, the influence of climate changes and hydrological events such as sea level oscillations and drainage isolation as a result of geological processes in the Pleistocene may have contributed to the current structure of B. platynemum populations, as well as of differences in water chemistry in Madeira River. The strong genetic structure and the time of genetic divergence estimated for the groups may indicate the existence of strong structure populations of B. platynemum in the Amazon basin.

Fish collection of the Universidade Federal de Rondônia: its importance to the knowledge of Amazonian fish diversity / A coleção ictiológica da Universidade Federal de Rondônia: sua importância para o conhecimento da diversidade de peixes da Amazônia

Biological collections preserve the biodiversity of a nation. The fish collection of the Universidade Federal de Rondônia, recently established, contains about 41% of freshwater fish species known to occur in Brazil, and 24% of South America. The biological material is distributed into 1,067 species, 21,963 lots and 149,192 specimens, gathered during five years of work. From this collection, 99% of the lots have georeferenced location, and 94% of the species were sampled in the Madeira River basin, the largest tributary in flow, drainage area and sediment discharge of the Amazonas River basin. Among the 1,008 species collected in the Madeira River basin, 80% were reviewed by Brazilian, North American and French experts, and represents the highest richness among tributaries of the Amazonas River and other rivers worldwide. Fish collection from the Madeira River basin deposited in the ichthyological collection of the Universidade Federal de Rondônia accounts for about 75% of the lots and specimens of fish from that basin available for study in collections worldwide.

Coleções biológicas preservam a biodiversidade de uma nação. A coleção ictiológica da Universidade Federal de Rondônia, recentemente estabelecida, contém cerca de 41% das espécies de peixes de água doce conhecidas para o Brasil e 24% da América do Sul. O material biológico encontra-se distribuído em 1.067 espécies, 21.963 lotes e 149.192 exemplares, organizados durante 5 anos de trabalho. Desse acervo, 99% dos lotes possuem localidade georreferenciada e 94% das espécies foram coletadas na bacia do rio Madeira, o maior afluente em vazão, área de drenagem e descarga de sedimentos da bacia Amazônica. Do total de 1.008 espécies coletadas na bacia do rio Madeira, 80% foram revisadas por especialistas brasileiros, norte-americanos e franceses, e constitui a maior riqueza de espécies conhecida para um afluente do rio Amazonas e entre outros rios do mundo. O acervo de peixes da bacia do rio Madeira depositado na Coleção de peixes da Universidade Federal de Rondônia representa cerca de 75% dos lotes e de exemplares de peixes dessa bacia disponíveis para estudos em coleções ictiológicas do mundo.

(210)Pb and compositional data of sediments from Rondonian lakes, Madeira River basin, Brazil.

Gold exploration has been intensive in Brazilian Amazon over the last 40 years, where the use of mercury as an amalgam has caused abnormal Hg concentrations in water bodies. Special attention has been directed to Madeira River due to fact it is a major tributary of Amazon River and that since 1986, gold exploration has been officially permitted along a 350km sector of the river. The (21)(0)Pb method has been used to date sediments taken from nine lakes situated in Madeira River basin, Rondônia State, and to verify where anthropogenic Hg might exist due to gold exploitation in Madeira River. Activity profiles of excess (21)(0)Pb determined in the sediment cores provided a means to evaluate the sedimentation rates using a Constant Flux: Constant Sedimentation (CF:CS) and Constant Rate of Supply (CRS) of unsupported/excess (21)(0)Pb models. A significant relationship was found between the CF:CS sedimentation rates and the mean values of the CRS sedimentation rates (Pearson correlation coefficient r=0.59). Chemical data were also determined in the sediments for identifying possible relationships with Hg occurring in the area. Significant values were found in statistical correlation tests realized among the Hg, major oxides and Total Organic Carbon (TOC) content in the sediments. The TOC increased in the sediment cores accompanied by a loss on ignition (LOI) increment, whereas silica decreased following a specific surface area raising associated to the TOC increase. The CRS model always provided ages within the permitted range of the (21)(0)Pb-method in the studied lakes, whereas the CF:CS model predicted two values above 140 years.

Flood pulse and spatial dynamics of mercury in sediments in Puruzinho lake, Brazilian Amazon / O pulso de inundação e a dinâmica espacial do mercúrio em sedimentos no lago Puruzinho, Amazônia Brasileira

The study was conducted in Puruzinho lake (Humaitل, AM) considering seasonal periods of rainy and dry in way to elucidate the flood pulse importance in the deposition, remobilization and distributions of mercury and organic matter in bottom sediments in the Madeira River Basin (Brazilian Amazon). Bottom sediments and soils samples were analyzed for total mercury and organic matter. Mercury concentrations obtained in bottom sediment were 32.20-146.40 ng g-1 and organic matter values were 3.5 - 18.0%. The main region for accumulation of mercury and organic matter was in the central and deepest lake area In the rainy season there was a greater distribution of Hg and organic matter, mainly controlled by means of income of the Madeira river water during flooding, while the predominant process in the dry season was the remobilization of total Hg due to the resuspension of bottom sediments.

Este estudo foi realizado no lago Puruzinho (Humaitá, AM) considerando os períodos de cheia e seca para investigar a importância do pulso de inundação na deposição, remobilização e distribuição das concentrações de mercúrio e matéria orgânica nos sedimentos de fundo no lago da bacia do rio Madeira, na Amazônia brasileira. As amostras de sedimentos e solos foram analisadas para mercúrio total e matéria orgânica. As concentrações mercúrio no sedimento de fundo variaram entre 32,20 e 146,40 ng g-1 e as porcentagens de matéria orgânica variaram de 3,5 a 18,0%. A principal região de acumulação de mercúrio e de matéria orgânica foi na área central e mais profunda do lago. Na estação chuvosa ocorreu maior distribuição de Hg e de matéria orgânica controlada principalmente pelo pulso de inundação do rio Madeira, enquanto que no período de seca predominam os processos de remobilização de mercúrio devido a resssuspensão do sedimento de fundo.

A pesca de pequena escala no rio Madeira pelos desembarques ocorridos em Manicoré (Estado do Amazonas), Brasil / Small-scale fishery at Madeira River by fish landings in Manicoré city (Amazon State), Brazil

O trabalho teve como objetivo analisar o desembarque da pesca comercial na região do Médio rio Madeira, tendo como área focal o município de Manicoré, buscando identificar as espécies explotadas, os locais de pesca e sua contribuição para o abastecimento local de pescado. O desembarque foi amostrado diariamente, utilizando questionários aplicados aos pescadores após a comercialização do pescado. Foram desembarcadas no ano de 2002 aproximadamente 225,4 toneladas de pescado. Canoas motorizadas efetuaram mais expedições de pesca, entretanto os barcos de pesca desembarcaram uma maior produção. Os valores médios de desembarque foram de 11,2; 5,4 e 2,4 toneladas por mês para barcos, canoas e compradores de pescado respectivamente, sendo as capturas compostas por 32 espécies ou grupo de espécies, sendo jaraqui (Semaprochilodus spp), pacu (Mylossoma duriventre), curimatá (Prochilodus nigricans), sardinha (Triportheus spp) e jatuarana (Brycon spp), responsáveis por 75 por cento do pescado desembarcado. Foram identificados 32 locais de pesca, sendo os mais explotados os rios Madeira e Manicoré, os lagos Acará e Boquerão e o igarapé Matupiri.

The study aimed to analyze the landing of commercial fishing in Middle Madeira River, near Manicoré city, identifying the exploited species, fishing grounds and the contribution for the local supplying of fish. Fish landings were sampled daily, using questionnaires, given to fishermen after the fish sale. In 2002, 225.4 tons of fish were landed in Manicoré city. Motorized canoes undertook more fishing trips, but the higher fish landings were accomplished by boats. Mean values of fish landings were 11.2 tons/month, 5.4 tons/month and 2.4 tons/month for boats, motorized canoes and fish purchasers, respectively. 32 species or group of species were landed, with a predominance of jaraqui (Semaprochilodus spp), pacu (Mylossoma duriventre), curimatá (Prochilodus nigricans), sardinha (Triportheus spp) e jatuarana (Brycon spp), responsible for 75 percent of fish production. 32 fishing grounds were identified and the most exploited were the Madeira and Manicoré rivers, Acará and Boquerão lakes and the Matupiri stream.

A description of mercury in fishes from the Madeira River Basin, Amazon, Brazil / Um estudo descritivo do mercúrio em peixes da bacia do Rio Madeira, Amazônia, Brasil

Over the last 20 years several projects carried on the Madeira River basin in the Amazon produced a great amount data on total Hg concentration in different fish species. In this paper we discuss temporal trends in Hg contamination and its relation to body weight in some of those fishes, showing that even within similar groups, such as carnivorous and non-migratory fish, the interspecies variability in Hg accumulation is considerable.

Vários estudos têm sido desenvolvidos nos últimos 20 anos na bacia do Rio Madeira (Amazônia) com o objetivo de diagnosticar a presença de mercúrio em peixes e compreender o ciclo deste elemento no meio ambiente tropical. Neste artigo são discutidas tendências temporais na concentração de Hg e sua relação com a massa corporal de algumas espécies de peixes com diferentes hábitos alimentares, coletadas no Rio Madeira e no reservatório da hidroelétrica de Samuel, no Rio Jamari, Estado de Rondônia. Foi avaliada uma amostragem de peixes de 14 anos (1987 - 2000) com 86 espécies e um total de 1100 espécimes.

Desembarque e esforço de pesca da frota pesqueira comercial de Manicoré (Médio Rio Madeira), Amazonas, Brasil / Landing and fishing effort of commercial fishing fleet of Manicoré city (Medium Madeira River), Amazonas, Brazil

A adequação das estratégias do pescador à sazonalidade existente na Amazônia atesta o nível de conhecimento tradicional em relação à ecologia dos peixes e às variações da pesca nesse ambiente, como ocorre em outras regiões do Brasil. Nesse sentido, este trabalho teve como objetivo analisar a utilização dos ambientes de captura e a distribuição do esforço de pesca pela frota comercial em função do ciclo hidrológico. Foram coletados diariamente, entre junho de 2003 e maio de 2004, dados de desembarque e das expedições de pesca que ocorreram na região do Médio rio Madeira e submetidos à estatística descritiva. Os resultados mostraram que existiu uma tendência de aumento no esforço de pesca durante o período da enchente pelas embarcações da frota local, para compensar a queda na produção capturada. Os barcos de pesca e canoas motorizadas apresentaram valores médios de CPUE de 22,9 e 20,6 kg/pescador*dia, respectivamente. Ficou evidenciada também a maior utilização dos ambientes igarapés e lagos pelos pescadores de canoas motorizadas e do rio pelos pescadores dos barcos.

The adaptation of the strategies of the fisherman to the seasonality in the Amazonian attests the level of traditional ecological knowledge in relation to the fish and to the variations of the fishing in that environment, as it happens in other regions of Brazil. In that sense the present work aimed to analyze the use of the fishing grounds and the distribution of the fishing effort by the commercial fleet in relation to the hydrological cycle. Data of fishing landings and fishing expeditions of the Medium Madeira River region were collected daily, from June of 2003 until May of 2004, and submitted to the descriptive statistics. The results showed that there was a tendency towards an increase in the fishing effort during the rising water season for the vessels of the local fleet, to compensate for the decrease in the captured production. The fishing boats and motorized canoes presented medium values of CPUE 22.9 and 20.6 kg/fisherman*day, respectively. It was also shown that fishermen of motorized canoes utilized the stream and lake environments the most, where as boat fishermen relied mainly on the river environment.