Fernando Neves Pinto

Exploring the diversity of bacterial communities in sediments of urban mangrove forests

Municipal sewage, urban runoff and accidental oil spills are common sources of pollutants in urban mangrove forests and may have drastic effects on the microbial communities inhabiting the sediment. However, studies on microbial communities in the sediment of urban mangroves are largely lacking. In this study, we explored the diversity of bacterial communities in the sediment of three urban mangroves located in Guanabara Bay (Rio de Janeiro, Brazil). Analysis of sediment samples by means of denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments suggested that the overall bacterial diversity was not significantly affected by the different levels of hydrocarbon pollution at each sampling site. However, DGGE and sequence analyses provided evidences that each mangrove sediment displayed a specific structure bacterial community. Although primer sets for Pseudomonas, alphaproteobacterial and actinobacterial groups also amplified ribotypes belonging to taxa not intended to be enriched, sequence analyses of dominant DGGE bands revealed ribotypes related to Alteromonadales, Burkholderiales, Pseudomonadales, Rhodobacterales and Rhodocyclales. Members of these groups were often shown to be involved in aerobic or anaerobic degradation of hydrocarbon pollutants. Many of these sequences were only detected in the sampling sites with high levels of anthropogenic inputs of hydrocarbons. Many dominant DGGE ribotypes showed low levels of sequence identity to known sequences, indicating a large untapped bacterial diversity in mangrove ecosystems.

Taking root: enduring effect of rhizosphere bacterial colonization in mangroves.

Background Mangrove forests are of global ecological and economic importance, but are also one of the worlds most threatened ecosystems. Here we present a case study examining the influence of the rhizosphere on the structural composition and diversity of mangrove bacterial communities and the implications for mangrove reforestation approaches using nursery-raised plants. Methodology/Principal Findings A barcoded pyrosequencing approach was used to assess bacterial diversity in the rhizosphere of plants in a nursery setting, nursery-raised transplants and native (non-transplanted) plants in the same mangrove habitat. In addition to this, we also assessed bacterial composition in the bulk sediment in order to ascertain if the roots of mangrove plants affect sediment bacterial composition. We found that mangrove roots appear to influence bacterial abundance and composition in the rhizosphere. Due to the sheer abundance of roots in mangrove habitat, such an effect can have an important impact on the maintenance of bacterial guilds involved in nutrient cycling and other key ecosystem functions. Surprisingly, we also noted a marked impact of initial nursery conditions on the rhizosphere bacterial composition of replanted mangrove trees. This result is intriguing because mangroves are periodically inundated with seawater and represent a highly dynamic environment compared to the more controlled nursery environment. Conclusions/Significance In as far as microbial diversity and composition influences plant growth and health, this study indicates that nursery conditions and early microbial colonization patterns of the replants are key factors that should be considered during reforestation projects. In addition to this, our results provide information on the role of the mangrove rhizosphere as a habitat for bacteria from estuarine sediments.

Fish mercury concentration in the Alto Pantanal, Brazil: influence of season and water parameters

The tropical flood plain Pantanal is one of the worlds largest wetlands and a wildlife sanctuary. Mercury (Hg) emissions from some upstream gold mining areas and recent findings of high natural Hg levels in tropical oxisols motivated studies on the Hg cycle in the Pantanal. A survey was made on total Hg in the most consumed piscivorous fish species from rivers and floodplain lakes in the north (Cáceres and Barão de Melgaço) and in the south part of Alto Pantanal (around the confluence of the Cuiabá and Paraguai rivers). Samples were collected in both the rainy and dry seasons (March and August 1998) and included piranha (Serrasalmus spp.), and catfish (Pseudoplatystoma coruscans, pintado, and Pseudoplatystoma fasciatum, cachara or surubim). There was only a small spatial variation in Hg concentration of the 185 analyzed fish samples from the 200 x 200 km large investigation area, and 90% contained total Hg concentration below the safety limit for regular fish consumption (500 ng g(-1)). Concentration above this limit was found in both Pseudoplatystoma and Serrasalmus samples from the Baia Siá Mariana, the only acid soft-water lake included in this study, during both the rainy and dry seasons. Concentration above this limit was also found in fish outside Baia Siá Mariana during the dry season, especially in Rio Cuiabá in the region of Barão de Melgaço. The seasonal effect may be connected with decreasing water volumes and changing habitat during the dry season. The results indicate that fertile women should restrict their consumption of piscivorous fishes from the Rio Cuiabá basin during the dry season. Measures should be implanted to avoid a further deterioration of fish Hg levels.

Diversity of ndo Genes in Mangrove Sediments Exposed to Different Sources of Polycyclic Aromatic Hydrocarbon Pollution

ABSTRACT Polycyclic aromatic hydrocarbon (PAH) pollutants originating from oil spills and wood and fuel combustion are pollutants which are among the major threats to mangrove ecosystems. In this study, the composition and relative abundance in the sediment bacterial communities of naphthalene dioxygenase (ndo) genes which are important for bacterial adaptation to environmental PAH contamination were investigated. Three urban mangrove sites which had characteristic compositions and levels of PAH compounds in the sediments were selected. The diversity and relative abundance of ndo genes in total community DNA were assessed by a newly developed ndo denaturing gradient gel electrophoresis (DGGE) approach and by PCR amplification with primers targeting ndo genes with subsequent Southern blot hybridization analyses. Bacterial populations inhabiting sediments of urban mangroves under the impact of different sources of PAH contamination harbor distinct ndo genotypes. Sequencing of cloned ndo amplicons comigrating with dominant DGGE bands revealed new ndo genotypes. PCR-Southern blot analysis and ndo DGGE showed that the frequently studied nah and phn genotypes were not detected as dominant ndo types in the mangrove sediments. However, ndo genotypes related to nagAc-like genes were detected, but only in oil-contaminated mangrove sediments. The long-term impact of PAH contamination, together with the specific environmental conditions at each site, may have affected the abundance and diversity of ndo genes in sediments of urban mangroves.

Use of epiphyte plants as biomonitors to map atmospheric mercury in a gold trade center city, Amazon, Brazil

Evaluation of Hg in urban air is a quite complex and expensive task since conventional sampling systems are fragile and need special attention if long-term sampling is needed. Tillandsia usneoides, a Bromeliacea, is an epiphyte that captures all its nutrients from the atmosphere, and concomitantly accumulates heavy metals, among them mercury. Its morphology, with millimetric dimensions of the leaves and no roots, makes it ideal for handling and preparation of transplanting systems and due to its high relation between surface area and mass, has a high efficiency for Hg accumulation. One hundred systems of two baskets each with T. usneoides were distributed through Alta Floresta city}MT and recovered after an exposure of 15 and 45 days during the dry season August)September, . . . 1995 and also repeated during the rainy season February)March, 1996 . Each compartment basket contained 5 g of plants previously collected in a clean area. Only the younger parts were selected for transplantation experiments. Systems were hung at 2)20 m height in open areas, close to and in the surroundings of the gold shops as well as in control areas. Relative occupational exposure was also evaluated with systems installed inside gold dealer shops. Concentrations of Hg in the exposed plants were remarkably high in the shops, reaching values up to 26 ppm parts . per million or 300 times higher than in the control plants. Q 1998 Elsevier Science B.V.

Sequential hair mercury in mothers and children from a traditional riverine population of the Rio Tapajós, Amazonia: Seasonal changes

Riverine populations of the Brazilian Amazon depend on fish for their principal source of protein, which changes in availability with seasonal fluctuations in the aquatic ecosystem. We report seasonal (high and low waters) and interannual changes in total mercury and methylmercury concentrations in hair of subsistence fish-eaters from a traditional riverine village on the banks of the Rio Tapajós in the Brazilian Amazonia. Retrospective exposure assessment was conducted from hair concentrations in segments representative of 2 years. A total of 32 mothers and their 51 children were studied. They reported high fish consumption (4-14 times a week). Ranges of total mercury and methylmercury concentrations in hair were 1.0-51.0 and 0.5-41.4microgg(-1), with means of 12.4 and 10.2microgg(-1), respectively. The relative mean value for methylmercury was 80%. There was a significant correlation between mothers and children for both total-Hg (r=0.4826; P=0.003) and methyl-Hg (r=0.5214; P=0.004). Mercury concentrations along hair strands of individuals showed significant variation coinciding with seasonal high and low waters. The changes in the aquatic environment impacted fish species availability, which is reflected in the total and MeHg concentrations in hair.

5 – BIOMASSA FITOPLANCTÔNICA E PRODUÇÃO PRIMÁRIA*

RESUMO A caracterizacao da variabilidade espaco-temporal da biomassa fitoplanctonica e da produtividade primaria da Bacia de Campos foi observada durante duas campanhas oceanograficas realizadas entre marco e abril (periodo chuvoso) e agosto e setembro (periodo seco) de 2009. Durante estas campanhas foram coletadas amostras na superficie e na base da camada de mistura em cinco transectos no periodo chuvoso e quatro no periodo seco, cujas estacoes variaram entre 25 e 3.000 m de profundidade. A concentracao de clorofila a total (mono- e divinil-) apresentou um gradiente decrescente do continente para a regiao oceânica, variando de 0,20 a 1,80 μg·L−1 e 0,10 a 7,83 μg·L−1 na regiao neritica e nos periodos chuvoso e seco, respectivamente. Na regiao oceânica a concentracao variou entre 0,04 e 0,33 μg·L−1 em ambos os periodos do ano. A divinil-clorofila a foi detectada em grande parte da Bacia de Campos com concentracoes variando ate 0,15 μg·L−1 e apresentou padrao de distribuicao inverso ao da clorofila a total, com gradiente longitudinal crescente ao longo da regiao oceânica, chegando a representar 40% da clorofila a total nessas regioes. A produtividade primaria foi avaliada por meio de experimentos in situ simulados para a construcao das curvas de luz-fotossintese e consequente estimativa dos parâmetros fotossinteticos, que foram utilizados para o calculo da produtividade primaria integrada na zona eufotica. Os valores de produtividade primaria variaram de 0,07 a 1,56 gC·m−2·d−1 no periodo chuvoso, e de 0,34 a 0,57 gC·m−2·d−1 no periodo seco, nao havendo diferenca significativa entre os dois periodos. Os resultados obtidos confirmam a caracteristica oligotrofica da regiao da Bacia de Campos, com excecao das regioes proximas de Cabo Frio e Cabo Sao Tome, que estao sujeitas a influencia de feicoes oceanograficas que aportam nutrientes.

Assessment of remotely sensed chlorophyll-a concentration in Guanabara Bay, Brazil

Abstract. The Guanabara Bay (GB) is an estuarine system in the metropolitan region of Rio de Janeiro (Brazil), with a surface area of ∼346  km2 threatened by anthropogenic pressure. Remote sensing can provide frequent data for studies and monitoring of water quality parameters, such as chlorophyll-a concentration (Chl-a). Different combination of Medium Resolution Imaging Spectrometer (MERIS) remote sensing reflectance band ratios were used to estimate Chl-a. Standard algorithms such as Ocean Color 3-band, Ocean Color-4 band, fluorescence line height, and maximum chlorophyll index were also tested. The MERIS Chl-a estimates were statistically compared with a dataset of in situ Chl-a (2002 to 2012). Good correlations were obtained with the use of green, red, and near-infrared bands. The best performing algorithm was based on the red (665 nm) and green (560 nm) band ratio, named “RG3” algorithm (r2=0.71, chl-a=62,565*x1.6118). The RG3 was applied to a time series of MERIS images (2003- to 2012). The GB has a high temporal and spatial variability of Chl-a, with highest values found in the wet season (October to March) and in some of the most internal regions of the estuary. Lowest concentrations are found in the central circulation channel due to the flushing of ocean water masses promoted by pumping tide.

4 – HIDROQUÍMICA, CARBONO ORGÂNICO E NUTRIENTES DISSOLVIDOS E PARTICULADOS NA BACIA DE CAMPOS*

RESUMO Aguas oceânicas tropicais sao conhecidas por apresentar valores minimos de nutrientes dissolvidos e valores maximos de material particulado na camada eufotica, onde ha maior producao primaria (camada biogenica), ocorrendo incremento da concentracao de nutrientes dissolvidos e declinio de particulados nas massas de agua da camada afotica (biolitica). Nesta pesquisa, a hidroquimica da area de abrangencia da Bacia de Campos foi avaliada atraves de amostragens em 72 estacoes de coleta, em ate seis profundidades (superficie, segunda profundidade, e os nucleos das massas de agua mais profundas), nas estacoes chuvosa e seca de 2009. As distribuicoes verticais de nutrientes dissolvidos e de material particulado apresentam padroes de concentracao tipicos de aguas tropicais permanentemente estratificadas e, como esperado, maiores valores foram encontrados nas aguas da plataforma continental em relacao a regiao de talude. Estes resultados confirmam o papel do continente como fonte de materiais para a zona pelagica. Adicionalmente, tambem sugerem a ocorrencia de processos fisicos advectivos com sinais nas aguas de areas mais rasas da plataforma, em funcao da atividade de ondas e correntes. Finalmente, as variacoes na distribuicao espacial observadas para nitrato, ortofosfato e silicato possivelmente estao relacionadas a intrusao da Agua Central do Atlântico Sul (ACAS) na plataforma continental na regiao de Cabo Frio e a formacao de vortices na regiao do Cabo de Sao Tome, regioes onde foram encontradas as maiores concentracoes de nutrientes dissolvidos e material particulado.

Simulation of a Test Rig and Identification of Annular Gas Seals Coefficients

This paper shows some preliminary results of an ongoing test rig for coefficients identification of annular gas seals. The test rig is being built in the Laboratory of Vibrations and Acoustics (LAVI) at the Federal University of Rio de Janeiro. The main objective of the rig is to determine both the damping and stifness created by annular gas seals (honeycomb, labyrinth, hole-pattern, etc.) to a flexible rotor. The paper is divided in three parts. First, the characteristics and components of the rig are shown. Then, a rotordynamic model is proposed based on the finite elementh method, in which the rotor is divided into smaller elements and the seals are represented as punctual stiffness and damping. Some simulated results of this model is shown and analyzed. Finally, preliminary experimental results are shown and discussed.