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  • 1.
    Abreu, Fernanda
    et al.
    Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
    Leão, Pedro
    Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
    Vargas, Gabriele
    Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
    Cypriano, Jefferson
    Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
    Figueiredo, Viviane
    Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
    Bazylinski, Dennis A.
    University of Nevada at Las Vegas, Las Vegas, NV, USA.
    Lins, Ulysses
    Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
    Culture-independent characterization of a novel magnetotactic member affiliated to the Beta class of the Proteobacteria phylum from an acidic lagoon2018In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 20, no 7, p. 2615-2624Article in journal (Refereed)
    Abstract [en]

    Summary Magnetotactic bacteria (MTB) comprise a group of motile microorganisms common in most mesothermal aquatic habitats with pH values around neutrality. However, during the last two decades, a number of MTB from extreme environments have been characterized including: cultured alkaliphilic strains belonging to the Deltaproteobacteria class of the Proteobacteria phylum; uncultured moderately thermophilic strains belonging to the Nitrospirae phylum; cultured and uncultured moderately halophilic or strongly halotolerant bacteria affiliated with the Deltaproteobacteria and Gammaproteobacteria classes and an uncultured psychrophilic species belonging to the Alphaproteobacteria class. Here, we used culture-independent techniques to characterize MTB from an acidic freshwater lagoon in Brazil (pH ? 4.4). MTB morphotypes found in this acidic lagoon included cocci, rods, spirilla and vibrioid cells. Magnetite (Fe3O4) was the only mineral identified in magnetosomes of these MTB while magnetite magnetosome crystal morphologies within the different MTB cells included cuboctahedral (present in spirilla), elongated prismatic (present in cocci and vibrios) and bullet-shaped (present in rod-shaped cells). Intracellular pH measurements using fluorescent dyes showed that the cytoplasmic pH was close to neutral in most MTB cells and acidic in some intracellular granules. Based on 16S rRNA gene phylogenetic analyses, some of the retrieved gene sequences belonged to the genus Herbaspirillum within the Betaproteobacteria class of the Proteobacteria phylum. Fluorescent in situ hybridization using a Herbaspirillum-specific probe hybridized with vibrioid MTB in magnetically-enriched samples. Transmission electron microscopy of the Herbaspirillum-like MTB revealed the presence of many intracellular granules and a single chain of elongated prismatic magnetite magnetosomes. Diverse populations of MTB have not seemed to have been described in detail in an acid environment. In addition, this is the first report of an MTB phylogenetically affiliated with Betaproteobacteria class.

  • 2.
    Bento, Luiz
    et al.
    University of Federal Rio de Janeiro, Brazil.
    Shizue Moriga Masuda, Laura
    University of Federal Rio de Janeiro, Brazil.
    Bittencourt Peixoto, Roberta
    University of Federal Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil; University of Federal Rio de Janeiro, Brazil.
    Regulation in the Metabolism and Community Structure of a Tropical Salt Flat after Rainfall2017In: Journal of Coastal Research, ISSN 0749-0208, E-ISSN 1551-5036, Vol. 33, no 2, p. 304-308Article in journal (Refereed)
    Abstract [en]

    Tropical salt flats typically lack a water column for most of the year, which means that rainfall is probably one of the major factors that regulate benthic microalgae and metabolism in areas subjected to periodic drought. Therefore, the goal of this study was to evaluate the effects of rainfall on the ecological function and community structure of a tropical mangrove salt flat area. This study showed that the highest primary production and respiration fluxes were recorded on the last day of sampling when it rained (-7.6 and 4.7 mmol C-CO2 m(-2) h(-1), respectively). Net primary production increased significantly compared with the dry period that preceded the rain event. The results also suggested that community structure was regulated by rainfall. After the rain event, abundance increased by one order of magnitude, but the diversity and evenness indices decreased. These results demonstrate that rain does have strong regulatory effects on the ecological function and structure of tropical salt flats.

  • 3.
    Call, Mitchell
    et al.
    National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Coffs Harbour, New South Wales, Australia; Southern Cross Geoscience, Southern Cross University, Lismore, New South Wales, Australia.
    Sanders, Christian J.
    National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Coffs Harbour, New South Wales, Australia;.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Department of Botany, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Ecosystems and Global Change Laboratory (LEMGUFF)/ International Laboratory of Global Change (LINCGlobal), Biomass and Water Management Research Center (NABUFF), Graduate Program in Geosciences (Environmental Geochemistry), Universidade Federal Fluminense (UFF), Niteroi, Rio de Janeiro, Brazil.
    Sanders, Luciana
    Southern Cross Geoscience, Southern Cross University, Lismore, New South Wales, Australia.
    Marotta, Humberto
    Universidade Federal Fluminense (UFF), Niteroi, Rio de Janeiro, Brazil; .
    Santos, Isaac R.
    National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Coffs Harbour, New South Wales, Australia;.
    Maher, Damien T.
    National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Coffs Harbour, New South Wales, Australia; Southern Cross Geoscience, Southern Cross University, Lismore, New South Wales, Australia.
    Radon-traced pore-water as a potential source of CO2 and CH4 to receding black and clear water environments in the Amazon Basin2018In: Limnology and Oceanography Letters, ISSN 2378-2242Article in journal (Refereed)
    Abstract [en]

    Abstract Groundwater is a primary source of dissolved CO2 and CH4 in Amazonian headwaters, yet in higher order rivers, a groundwater/pore-water source is difficult to constrain due to the high spatial and temporal heterogeneity of pore-water exchange. Here, we report coupled, high resolution measurements of pCO2, CH4, and 222Rn (a natural pore-water and groundwater tracer) during receding waters in the three major water types of the Central Amazon Basin: black (Negro River); clear (Tapajós River); white (Madeira River). Considerable spatial heterogeneity was observed in pCO2, CH4, and 222Rn concentrations ranging from 460 ?atm to 8030 ?atm, 7 nM to 281 nM, and 713 dpm m?3 to 8516 dpm m?3, respectively. The significant correlations between pCO2 and CH4 to 222Rn in the black and clear waters suggests that pore-water further enhanced CO2 supersaturation by 18?47% and is a driver of CH4 dynamics in these waters.

  • 4.
    Enrich Prast, Alex
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Laboratório de Biogeoquímica, Departamento de Ecologia, Instituto de Biologia Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
    Figueiredo, V.
    Laboratório de Biogeoquímica, Departamento de Ecologia, Instituto de Biologia Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Departamento de Geoquímica, Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil.
    De, Esteves F.A.
    Laboratório de Limnologia, Departamento de Ecologia, Instituto de Biologia Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Núcleo de Pesquisas em Ecologia E Desenvolvimento Sócio-ambiental de Macaé, Universidade Federal do Rio de Janeiro, Macaé, Rio de Janeiro, Brazil.
    Nielsen, L.P.
    Department of Biology, University of of Aarhus, Aarhus, Denmark.
    Controls of sediment nitrogen dynamics in tropical coastal lagoons2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 5, article id e0155586Article in journal (Refereed)
    Abstract [en]

    Sediment denitrification rates seem to be lower in tropical environments than in temperate environments. Using the isotope pairing technique, we measured actual denitrification rates in the sediment of tropical coastal lagoons. To explain the low denitrification rates observed at all study sites (amp;lt;5 μmol N2 m-2 h-1 ), we also evaluated potential oxygen (O2 ) consumption, potential nitrification, potential denitrification, potential anammox, and estimated dissimilatory nitrate NO3 ) reduction to ammonium (NH4 + ; DNRA) in the sediment.15NO3 and 15NH4 + conversion was measured in oxic and anoxic slurries from the sediment surface. Sediment potential O2 consumption was used as a proxy for overall mineralization activity. Actual denitrification rates and different potential nitrogen (N) oxidation and reduction processes were significantly correlated with potential O2 consumption. The contribution of potential nitrification to total O2 consumption decreased from contributing 9% at sites with the lowest sediment mineralization rates to less than 0.1% at sites with the highest rates. -3 reduction switched completely from potential denitrification to estimated DNRA. Ammonium oxidation and nitrite NO2 ) reduction by potential anammox contributed up to 3% in sediments with the lowest sediment mineralization rates. The majority of these patterns could be explained by variations in the microbial environments from stable and largely oxic conditions at low sediment mineralization sites to more variable conditions and the prevalences of anaerobic microorganisms at high sediment mineralization sites. Furthermore, the presence of algal and microbial mats on the sediment had a significant effect on all studied processes. We propose a theoretical model based on low and high sediment mineralization rates to explain the growth, activity, and distribution of microorganisms carrying out denitrification and DNRA in sediments that can explain the dominance or coexistence of DNRA and denitrification processes. The results presented here show that the potential activity of anaerobic nitrate-reducing organisms is not dependent on the availability of environmental NO3. © 2016 Enrich-Prast et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

  • 5.
    Enrich Prast, Alex
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Departamento de Botânica,Instituto de Biologia, Laboratorio Internacional en Cambio Global (LINCGlobal), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.
    Gaxiola, Aurora
    Departamento de Ecología, Laboratorio Internacional en Cambio Global (LINCGlobal), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Instituto de Ecología y Biodiversidad (IEB), Chile.
    Santoro, Ana Lucia
    Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.
    Duran, Jorge
    Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Coimbra, Portugal.
    Rodrigues, Alexandra
    Center for Functional Ecology (CFE), Science for People & the Planet, Coimbra, Portugal.
    Marotta, Humberto
    Laboratório de Ecosistemas e Mudanças Globais (LEMG/UFF), Instituto de Geociências, Laboratorio Internacional en Cambio Global (LINCGlobal), Universidade Federal Fluminense (UFF), Brasil.
    Cambios Globales e ciclos biogeoquimicos2018In: Cambio Global: una mirada desde iberoamerica / [ed] Pablo Marquet, Fernando Valladares, Sandra Magro, Aurora Gaxiola, Alex Enrich-Prast, Madrid: Departamento de Publicaciones, Consejo Superior de Investigaciones Científicas (CSIC), 2018, p. 111-125Chapter in book (Other (popular science, discussion, etc.))
  • 6.
    Enrich Prast, Alex
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Lucia Santoro, Ana
    University of Federal Rio de Janeiro, Brazil.
    Coutinho, Rodrigo S.
    University of Federal Rio de Janeiro, Brazil.
    Peter Nielsen, Lars
    University of Aarhus, Denmark.
    Esteves, Francisco A.
    University of Federal Rio de Janeiro, Brazil.
    Sediment Denitrification in Two Contrasting Tropical Shallow Lagoons2016In: Estuaries and Coasts, ISSN 1559-2723, E-ISSN 1559-2731, Vol. 39, no 3, p. 657-663Article in journal (Refereed)
    Abstract [en]

    Sediment denitrification was monthly evaluated in two tropical coastal lagoons with different trophic states using the N-15 isotope pairing technique. Denitrification rates were very low in both environments, always < 5.0 mu mol N-2 m(-2) h(-1) and were not significantly different between them. Oxygen consumption varied from 426 to 4248 mu mol O-2 m(-2) h(-1) and was generally three times higher in the meso-eutrophic than the oligotrophic lagoon. The low denitrification activity was ascribed to both low water NO3- concentrations (< 2.0 mu M) and little nitrate supply from nitrification. There was no correlation of denitrification with nitrate or ammonium fluxes. Sediments in temperate environments with similar oxygen consumption rates usually presented a higher proportion of nitrification-denitrification rates. Sediment oxygen consumption was a good predictor of sediment denitrification in both studied lagoons.

  • 7.
    Feiz, Roozbeh
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center. Biogas Research Center.
    Ammenberg, Jonas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Yufang, Guo
    School of Environmental Science and Engineering, Guangzhou University, Guangzhou, China.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Liu, Yonghui
    School of Environmental Science and Engineering, Guangzhou University, Guangzhou, China.
    Liu, Yuxian
    Linköping University. Guangzhou University Research Center on Urban Sustainable Development, Guangzhou University, Guangzhou, China.
    Masuda, Laura Shizue Moriga
    Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
    Enrich-Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Rohracher, Harald
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Trygg, Kristina
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Zhang, Fagen
    School of Environmental Science and Engineering, Guangzhou University, Guangzhou, China.
    Biogas Potential for Improved Sustainability in Guangzhou, China: A Study Focusing on Food Waste on Xiaoguwei Island2019In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 11, no 6Article in journal (Refereed)
    Abstract [en]

    As a result of rapid development in China and the growth of megacities, large amounts of organic wastes are generated within relatively small areas. Part of these wastes can be used to produce biogas, not only to reduce waste-related problems, but also to provide renewable energy, recycle nutrients, and lower greenhouse gases and air polluting emissions. This article is focused on the conditions for biogas solutions in Guangzhou. It is based on a transdisciplinary project that integrates several approaches, for example, literature studies and lab analysis of food waste to estimate the food waste potential, interviews to learn about the socio-technical context and conditions, and life-cycle assessment to investigate the performance of different waste management scenarios involving biogas production. Xiaoguwei Island, with a population of about 250,000 people, was chosen as the area of study. The results show that there are significant food waste potentials on the island, and that all studied scenarios could contribute to a net reduction of greenhouse gas emissions. Several socio-technical barriers were identified, but it is expected that the forthcoming regulatory changes help to overcome some of them.

  • 8.
    Figueiredo, V.
    et al.
    University of Federal Fluminense, Brazil; University of Federal Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Ruetting, T.
    University of Gothenburg, Sweden.
    Soil organic matter content controls gross nitrogen dynamics and N2O production in riparian and upland boreal soil2016In: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 67, no 6, p. 782-791Article in journal (Refereed)
    Abstract [en]

    We investigated the pathways of gross soil nitrogen (N) transformations and nitrous oxide (N2O) production with N-15 enrichment techniques in a boreal forest landscape by comparing organic (riparian) and mineral (upland) soil within two catchments in northern Sweden. The values of all soil properties evaluated for the riparin and upland zones were statistically different (Pamp;lt;0.05). The rates of gross N transformation were larger in the riparian than in the upland soil (Pamp;lt;0.05), which can be explained by the larger soil organic matter (SOM) content that provides energy and mineral N as a substrate for other processes. The riparian soil at one site shows a decoupling of nitrification from mineralization; the largest gross mineralization occurred in the soil at this site, but gross nitrification was relatively small. This was probably because of the low pH (2.70.1), which inhibits the activity of autotrophic nitrifiers. Oxidation of organic N was the main source of N2O in the soil at all sites, probably because of low soil pH and large organic carbon content, which favours heterotrophic nitrification. The results of our study confirm that organic matter is the main regulating factor for gross N mineralization and nitrification; the latter are markedly different in the organic-rich riparian soil and the upland soil in the boreal forest landscape.

  • 9.
    Figueiredo, Viviane
    et al.
    Univ Fed Rio de Janeiro, Brazil; Univ Fed Fluminense, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Fed Rio de Janeiro, Brazil; Univ Fed Fluminense, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Rutting, Tobias
    Univ Gothenburg, Sweden.
    Evolution of nitrogen cycling in regrowing Amazonian rainforest2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 8538Article in journal (Refereed)
    Abstract [en]

    Extensive regions of tropical forests are subjected to high rates of deforestation and forest regrowth and both are strongly affect soil nutrient cycling. Nitrogen (N) dynamics changes during forest regrowth and the recovery of forests and functioning similar to pristine conditions depends on sufficient N availability. We show that, in a chronosequence of Amazonian forests, gross nitrification and, as a result, nitrate-to-ammonium (NO3- : NH4+) ratio were lower in all stages of regrowing forests (10 to 40 years) compared to pristine forest. This indicates the evolution of a more conservative and closed N cycle with reduced risk for N leaking out of the ecosystem in regrowing forests. Furthermore, our results indicate that mineralization and nitrification are decoupled in young regrowing forests (10 years), such as that high gross mineralization is accompanied by low gross nitrification, demonstrating a closed N cycle that at the same time maintains N supply for forest regrowth. We conclude that the status of gross nitrification in disturbed soil is a key process to understand the mechanisms of and time needed for tropical forest recovery.

  • 10.
    Gonsior, Michael
    et al.
    University of Maryland, MD 20688 USA.
    Valle, Juliana
    University of Federal Rio de Janeiro, Brazil; Helmholtz Zentrum Munchen, Germany.
    Schmitt-Kopplin, Philippe
    Helmholtz Zentrum Munchen, Germany; Technical University of Munich, Germany.
    Hertkorn, Norbert
    Helmholtz Zentrum Munchen, Germany.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Luek, Jenna
    University of Maryland, MD 20688 USA.
    Harir, Mourad
    Helmholtz Zentrum Munchen, Germany.
    Bastos, Wanderley
    University of Federal Rondonia, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Chemodiversity of dissolved organic matter in the Amazon Basin2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 14, p. 4279-4290Article in journal (Refereed)
    Abstract [en]

    Regions in the Amazon Basin have been associated with specific biogeochemical processes, but a detailed chemical classification of the abundant and ubiquitous dissolved organic matter (DOM), beyond specific indicator compounds and bulk measurements, has not yet been established. We sampled water from different locations in the Negro, Madeira/Jamari and Tapajos River areas to characterize the molecular DOM composition and distribution. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) revealed a large proportion of ubiquitous DOM but also unique area-specific molecular signatures. Unique to the DOM of the Rio Negro area was the large abundance of high molecular weight, diverse hydrogen-deficient and highly oxidized molecular ions deviating from known lignin or tannin compositions, indicating substantial oxidative processing of these ultimately plant-derived polyphenols indicative of these black waters. In contrast, unique signatures in the Madeira/Jamari area were defined by presumably labile sulfur-and nitrogen-containing molecules in this white water river system. Waters from the Tapajos main stem did not show any substantial unique molecular signatures relative to those present in the Rio Madeira and Rio Negro, which implied a lower organic molecular complexity in this clear water tributary, even after mixing with the main stem of the Amazon River. Beside ubiquitous DOM at average H / C and O / C elemental ratios, a distinct and significant unique DOM pool prevailed in the black, white and clear water areas that were also highly correlated with EEM-PARAFAC components and define the frameworks for primary production and other aspects of aquatic life.

  • 11.
    Hernandez, Marcela
    et al.
    Max Planck Inst Terr Microbiol, Germany.
    Klose, Melanie
    Max Planck Inst Terr Microbiol, Germany.
    Claus, Peter
    Max Planck Inst Terr Microbiol, Germany.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Marotta, Humberto
    Univ Fed Fluminense, Brazil; Univ Fed Fluminense, Brazil.
    Figueiredo, Viviane
    Univ Fed Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Fed Fluminense, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Conrad, Ralf
    Max Planck Inst Terr Microbiol, Germany.
    Structure, function and resilience to desiccation of methanogenic microbial communities in temporarily inundated soils of the Amazon rainforest (Cunia Reserve, Rondonia)2019In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 21, no 5, p. 1702-1717Article in journal (Refereed)
    Abstract [en]

    The floodplain of the Amazon River is a large source for the greenhouse gas methane, but the soil microbial communities and processes involved are little known. We studied the structure and function of the methanogenic microbial communities in soils across different inundation regimes in the Cunia Reserve, encompassing nonflooded forest soil (dry forest), occasionally flooded Igapo soils (dry Igapo), long time flooded Igapo soils (wet Igapo) and sediments from Igarape streams (Igarape). We also investigated a Transect (four sites) from the water shoreline into the dry forest. The potential and resilience of the CH4 production process were studied in the original soil samples upon anaerobic incubation and again after artificial desiccation and rewetting. Bacterial and archaeal 16S rRNA genes and methanogenic mcrA were always present in the soils, except in dry forest soils where mcrA increased only upon anaerobic incubation. NMDS analysis showed a clear effect of desiccation and rewetting treatments on both bacterial and archaeal communities. However, the effects of the different sites were less pronounced, with the exception of Igarape. After anaerobic incubation, methanogenic taxa became more abundant among the Archaea, while there was only little change among the Bacteria. Contribution of hydrogenotrophic methanogenesis was usually around 40%. After desiccation and rewetting, we found that Firmicutes, Methanocellales and Methanosarcinaceae became the dominant taxa, but rates and pathways of CH4 production stayed similar. Such change was also observed in soils from the Transects. The results indicate that microbial community structures of Amazonian soils will in general be strongly affected by flooding and drainage events, while differences between specific field sites will be comparatively minor.

    The full text will be freely available from 2020-01-24 12:37
  • 12.
    Ji, Yang
    et al.
    Max Planck Institute Terr Microbiol, Germany; University of Vienna, Austria.
    Angel, Roey
    University of Federal Rio de Janeiro, Brazil.
    Klose, Melanie
    University of Vienna, Austria.
    Claus, Peter
    University of Vienna, Austria.
    Marotta, Humberto
    University of Federal Fluminense, Brazil.
    Pinho, Luana
    University of Estado Rio De Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Conrad, Ralf
    University of Vienna, Austria.
    Structure and function of methanogenic microbial communities in sediments of Amazonian lakes with different water types2016In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 18, no 12, p. 5082-5100Article in journal (Refereed)
    Abstract [en]

    Tropical lake sediments are a significant source for the greenhouse gas methane. We studied function (pathway, rate) and structure (abundance, taxonomic composition) of the microbial communities (Bacteria, Archaea) leading to methane formation together with the main physicochemical characteristics in the sediments of four clear water, six white water and three black water lakes of the Amazon River system. Concentrations of sulfate and ferric iron, pH and delta C-13 of organic carbon were usually higher, while concentrations of carbon, nitrogen and rates of CH4 production were generally lower in white water versus clear water or black water sediments. Copy numbers of bacterial and especially archaeal ribosomal RNA genes also tended to be relatively lower in white water sediments. Hydrogenotrophic methanogenesis contributed 58+/-16% to total CH4 production in all systems. Network analysis identified six communities, of which four were comprised mostly of bacteria found in all sediment types, while two were mostly in clear water sediment. Terminal restriction fragment length polymorphism (T-RFLP) and pyrosequencing showed that the compositions of the communities differed between the different sediment systems, statistically related to the particular physicochemical conditions and to CH4 production rates. Among the archaea, clear water, white water, and black water sediments contained relatively more Methanomicrobiales, Methanosarcinaceae and Methanocellales, respectively, while Methanosaetaceae were common in all systems. Proteobacteria, Deltaproteobacteria (Myxococcales, Syntrophobacterales, sulfate reducers) in particular, Acidobacteria and Firmicutes were the most abundant bacterial phyla in all sediment systems. Among the other important bacterial phyla, clear water sediments contained relatively more Alphaproteobacteria and Planctomycetes, whereas white water sediments contained relatively more Betaproteobacteria, Firmicutes, Actinobacteria, and Chloroflexi than the respective other sediment systems. The data showed communities of bacteria common to all sediment types, but also revealed microbial groups that were significantly different between the sediment types, which also differed in physicochemical conditions. Our study showed that function of the microbial communities may be understood on the basis of their structures, which in turn are determined by environmental heterogeneity.

  • 13.
    Lauerwald, R.
    et al.
    Université Libre de Bruxelles, Bruxelles, Belgium.
    Regnier, P.
    Université Libre de Bruxelles, Bruxelles, Belgium.
    Figueiredo, V
    University Federal of Rio de Janeiro, Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University Federal of Rio de Janeiro, Rio de Janeiro, Brazil.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Lehner, B.
    McGill University, Montreal, Canada.
    Maavara, T.
    Lawrence Berkeley National Laboratory, Berkeley, USA.
    Raymond, P.
    Yale School of Forestry and Environmental Studies, New Haven, USA.
    Natural lakes are a minor global source of N2O to the atmosphere2019In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224Article in journal (Refereed)
    Abstract [en]

    Natural lakes and reservoirs are important, yet not well constrained sources of greenhouse gasses to the atmosphere. In particular for N2O emissions, a huge variability is observed in the few, observation‐driven flux estimates that have been published so far. Recently, a process‐based, spatially explicit model has been used to estimate global N2O emissions from more than 6,000 reservoirs based on nitrogen (N) and phosphorous inflows and water residence time. Here, we extend the model to a dataset of 1.4 million standing water bodies comprising natural lakes and reservoirs. For validation, we normalized the simulated N2O emissions by the surface area of each water body and compared them against regional averages of N2O emission rates taken from the literature or estimated based on observed N2O concentrations. We estimate that natural lakes and reservoirs together emit 4.5±2.9 Gmol N2O‐N yr‐1 globally. Our global scale estimate falls in the far lower end of existing, observation‐driven estimates. Natural lakes contribute only about half of this flux, although they contribute 91% of the total surface area of standing water bodies. Hence, the mean N2O emission rates per surface area are substantially lower for natural lakes than for reservoirs with 0.8±0.5 mmol N m‐2yr‐1 vs. 9.6±6.0 mmol N m‐2yr‐1, respectively. This finding can be explained by on average lower external N inputs to natural lakes. We conclude that upscaling based estimates, which do not distinguish natural lakes from reservoirs, are prone to important biases.

  • 14.
    Marotta, H.
    et al.
    University of Federal Fluminense, Brazil; University of Federal Fluminense, Brazil; University of Federal Fluminense, Brazil.
    Enrich Prast, Alex
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Catastrophic shifts in the aquatic primary production revealed by a small low-flow section of tropical downstream after dredging2015In: Brazilian Journal of Biology, ISSN 1519-6984, E-ISSN 1678-4375, Vol. 75, no 4, p. 804-811Article in journal (Refereed)
    Abstract [en]

    Dredging is a catastrophic disturbance that directly affects key biological processes in aquatic ecosystems, especially in those small and shallow. In the tropics, metabolic responses could still be enhanced by the high temperatures and solar incidence. Here, we assessed changes in the aquatic primary production along a small section of low-flow tropical downstream (Imboassica Stream, Brazil) after dredging. Our results suggested that these ecosystems may show catastrophic shifts between net heterotrophy and autotrophy in waters based on three short-term stages following the dredging: (I) a strongly heterotrophic net primary production -NPP- coupled to an intense respiration -R- likely supported by high resuspended organic sediments and nutrients from the bottom; (II) a strongly autotrophic NPP coupled to an intense gross primary production -GPP- favored by the high nutrient levels and low solar light attenuation from suspended solids or aquatic macrophytes; and (III) a NPP near to the equilibrium coupled to low GPP and R rates following, respectively, the shading by aquatic macrophytes and high particulate sedimentation. In conclusion, changes in aquatic primary production could be an important threshold for controlling drastic shifts in the organic matter cycling and the subsequent silting up of small tropical streams after dredging events.

  • 15.
    Marotta, H.
    et al.
    University of Federal Fluminense, Brazil University of Federal Rio de Janeiro, Brazil.
    Pinho, L.
    University of Federal Rio de Janeiro, Brazil .
    Gudasz, C.
    Uppsala University, Sweden; Princeton University, NJ USA.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Tranvik, L.J.
    Uppsala University, Sweden .
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Greenhouse gas production in low-latitude lake sediments responds strongly to warming2014In: Nature Climate Change, ISSN 1758-678X, E-ISSN 1758-6798, Vol. 4, no 6, p. 467-470Article in journal (Refereed)
    Abstract [en]

    Inland water sediments receive large quantities of terrestrial organic matter(1-5) and are globally important sites for organic carbon preservation(5,6). Sediment organic matter mineralization is positively related to temperature across a wide range of high-latitude ecosystems(6-10), but the situation in the tropics remains unclear. Here we assessed temperature effects on the biological production of CO2 and CH4 in anaerobic sediments of tropical lakes in the Amazon and boreal lakes in Sweden. On the basis of conservative regional warming projections until 2100 (ref. 11), we estimate that sediment CO2 and CH4 production will increase 9-61% above present rates. Combining the CO2 and CH4 as CO2 equivalents (CO(2)eq; ref. 11), the predicted increase is 2.4-4.5 times higher in tropical than boreal sediments. Although the estimated lake area in low latitudes is 3.2 times smaller than that of the boreal zone, we estimate that the increase in gas production from tropical lake sediments would be on average 2.4 times higher for CO2 and 2.8 times higher for CH4. The exponential temperature response of organic matter mineralization, coupled with higher increases in the proportion of CH4 relative to CO2 on warming, suggests that the production of greenhouse gases in tropical sediments will increase substantially. This represents a potential large-scale positive feedback to climate change.

  • 16.
    Marotta, Humberto
    et al.
    Laboratório de Ecosistemas e Mudanças Globais (LEMG/UFF), Instituto de Geociências, Laboratorio Internacional en Cambio Global (LINCGlobal), Universidade Federal Fluminense (UFF), Brasil.
    Rodrigues, Alexandra
    Center for Functional Ecology (CFE),Science for People & the Planet, Coimbra, Portugal.
    Durán, Jorge
    Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Coimbra, Portugal.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Departamento de Botânica, Instituto de Biologia, Laboratorio Internacional en Cambio Global (LINCGlobal), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.
    Pinho, Luana
    Departamento de Ocenografía Química, Universidad del Estado de Rio de Janeiro, Maracanã–RJ, Brasil.
    Biogeoquímica aplicada: estudios de casosobre la interacción entre los elementosesenciales para la vida y el cambio global2018In: Cambio Global: una mirada desde Iberoamerica / [ed] Pablo Marquet, Fernando Valladares, Sandra Magro, Aurora Gaxiola, Alex Enrich-Prast, Madrid: Departamento de Publicaciones, Consejo Superior de Investigaciones Científicas (CSIC), 2018, p. 153-161Chapter in book (Other (popular science, discussion, etc.))
  • 17.
    Marquet, Pablo A.
    et al.
    Departamento de Ecología, Laboratorio Internacional en Cambio Global (LINCGlobal), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile / Instituto de Ecología y Biodiversida (IEB),Chile / The Santa Fe Institute, Santa Fe, NM 87501, USA.
    Valladares, FernandoMuseo Nacional de Ciencias Naturales, Laboratorio Internacional en Cambio Global (LINCGlobal), CSIC, Madrid, España.Magro Ruiz, SandraMuseo Nacional de Ciencias Naturales, CSIC, Madrid, España.Gaxiola, AuroraDepartamento de Ecología, Laboratorio Internacional en Cambio Global (LINCGlobal), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Instituto de Ecología y Biodiversidad (IEB), Chile.Enrich Prast, AlexLinköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Departamento de Botânica, Instituto de Biologia, Laboratorio Internacional en Cambio Global (LINCGlobal), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.
    Cambio global, una mirada desde Iberoamérica2018Collection (editor) (Other (popular science, discussion, etc.))
    Abstract [es]

    Han transcurrido ya 10 años desde la fundación del proyecto “Laboratorio Internacional en Cambio Globlal” (LINCGlobal), una iniciativa pionera de integración y colaboración científica de largo plazo en ciencias de cambio global entre investigadores de la Península Ibérica y Latinoamérica.

    El LINCGlobal, inicialmente impulsado y financiado por el Consejo Superior de Investigaciones Científicas (CSIC), España y por la Universidad Católica de Chile, con una incorporación más reciente de la Universidad Federal de Rio de Janeiro, Brasil, actualmente reúne a más de una treintena de investigadores de muy alto nivel científico en temas de cambio global.

    Los fundadores tuvimos en mente la visión de establecer grupos iberoamericanos multidisciplinares y líneas conjuntas de investigación conducentes a la realización y publicación de investigaciones en temas de cambios globales relevantes en diversos ámbitos de los ecosistemas marinos y terrestres; usando para ello aproximaciones tanto experimentales, correlacionales como de modelización y de macroecología.

    No menor fue la visión relacionada con impulsar y fortalecer el intercambio iberoamericano en la formación conjunta de investigadores jóvenes a nivel de doctorado y postdoctorado, la generación de nuevas fórmulas de gobernanza y sobretodo la necesaria y urgente diseminación a la sociedad de la información generada, con un nivel de comprensión adecuado. En esta década los objetivos generales de la visón y los más específicos de los distinto grupos se han cumplido más que a cabalidad y así lo demuestran los cientos de publicaciones realizadas por los investigadores del Laboratorio y las Memorias del proyecto.

    Hoy, al finalizar la primera década de nuestra aventura iberoamericana en cambio global, como uno de los Directores fundadores del LINCGlobal, me es muy grato realizar el Prólogo del libro “Cambio Global una mirada desde Iberoamérica”. El condensa muchos de los avances en investigación realizados en la década no solo por los investigadores de plantilla del proyecto, sino que además por numerosos alumnos de doctorado, postdoctorado y colaboradores. El libro, editado por los Profesores Pablo Marquet, Fernando Valladares, Sandra Magro, Aurora Gaxiola y Alex Enrich-Prast contiene 14 capítulos en que están involucrados 50 autores iberoamericanos ligados al LINCGlobal. Los diferentes capítulos presentan una amplia cobertura de las líneas de investigación abordadas por los miembros del Laboratorio Internacional, desde contextualización de cambios globales en el pasado, la población humana, uso de los recursos y redes comerciales, hasta el papel regulador de los océanos en el sistema terrestre, la radiación ultravioleta y las pesquerías marinas. Los cambios globales en relación con los ciclos biogeoquímicos, la disponibilidad de agua, la biodiversidad y los impactos sobre las redes de interacción ecológica y la distribución de las especies son abordados y discutidos en profundidad. Finalmente se muestra un caso de estudio para los cambios globales en un lago de Chile central durante el último milenio. El esfuerzo de síntesis de los autores es loable, del mismo modo que la inclusión de infografías que permiten aprehender con facilidad los tipos de cambios globales y sus consecuencias en los ecosistemas terrestres y oceánicos.

    Solo al considerar los contenidos de este libro visualizo para los integrantes del LINCGlobal al menos dos desafíos. Primero ser consecuente con la visión iberoamericana del Laboratorio y traducir el libro al portugués, para así hacer más accesible la información a estudiantes y público en general de habla portuguesa. Segundo, y mucho más desafiante, bajar y socializar la información científica contenida en él a niveles de público general y en especial para estudiantes de educación primaria y secundaria en Latinoamérica. Ello requiere, ciertamente, un esfuerzo extra significativo. Sin embargo, por ejemplo, el trabajo ya realizado en el libro con las infografías y el uso de excelentes fotografías facilitará ese camino. En ello el uso de las redes sociales no debería descartarse.

    A mis amigos del Laboratorio Internacional y a los lectores y usuarios del libro: bienvenidos a la era de la ciencia post-normal, donde tanto la construcción del conocimiento y su publicación, como su diseminación y democratización hacia la sociedad, en forma simple y didáctica, representa un desafío mayor.

    Santiago de Chile, septiembre 2018

    Juan Carlos Castilla

    Pontificia Universidad Católica de Chile

  • 18.
    Masuda, L. S. M.
    et al.
    University of Federal Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Benthic microalgae community response to flooding in a tropical salt flat2016In: Brazilian Journal of Biology, ISSN 1519-6984, E-ISSN 1678-4375, Vol. 76, no 3, p. 577-582Article in journal (Refereed)
    Abstract [en]

    This research evaluated the effect of flooding on the microphytobenthos community structure in a microbial mat from a tropical salt flat. Field samples were collected during four consecutive days: on the first three days the salt flat was dry, on the fourth day it was flooded by rain. In order to evaluate the community maintained in flood conditions, samples from this area were collected and kept in the laboratory for 10 days with sea water. The results of total abundance of microphytobenthos varied from 4.2 x 10(8) to 2.9 x 10(9) organisms L-1, total density increased one order of magnitude under the effect of water for both situations of precipitation in the salt flat and in experimental conditions, an increase due to the high abundance of Microcoleus spp. Shannon index (H) was higher during the desiccation period. Our data suggest that changes in the abundance of organisms were due to the effect of water. The dominance of the most abundant taxa remained the same under conditions of desiccation and influence of water, and there is probably a consortium of microorganisms in the microbial mat that helps to maintain these dominances.

  • 19.
    Pangala, Sunitha R.
    et al.
    Open University, England; University of Lancaster, England.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Basso, Luana S.
    IPEN, Brazil.
    Bittencourt Peixoto, Roberta
    University of Federal Rio de Janeiro, Brazil.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Hornibrook, Edward R. C.
    University of Bristol, England; University of British Columbia, Canada.
    Gatti, Luciana V.
    IPEN, Brazil; National Institute Space Research INPE, Brazil.
    Marotta, Humberto
    University of Federal Fluminense, Brazil.
    Silva Braucks Calazans, Luana
    University of Federal Rio de Janeiro, Brazil.
    Monica Sakuragui, Cassia
    University of Federal Rio de Janeiro, Brazil.
    Rodrigues Bastos, Wanderley
    Federal University of Rondonia, Brazil.
    Malm, Olaf
    University of Federal Rio de Janeiro, Brazil.
    Gloor, Emanuel
    University of Leeds, England.
    Bharat Miller, John
    NOAA, CO 80305 USA.
    Gauci, Vincent
    Open University, England.
    Large emissions from floodplain trees close the Amazon methane budget2017In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 552, no 7684, p. 230-+Article in journal (Refereed)
    Abstract [en]

    Wetlands are the largest global source of atmospheric methane (CH4)(1), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain(2,3), the largest natural geographic source of CH4 in the tropics, consistently underestimate the atmospheric burden of CH4 determined via remote sensing and inversion modelling(4,5), pointing to a major gap in our understanding of the contribution of these ecosystems to CH4 emissions. Here we report CH4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests(6) and tropical peat swamp forests(7), representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (delta C-13) of -66.2 +/- 6.4 per mil, consistent with a soil biogenic origin. We estimate that floodplain trees emit 15.1 +/- 1.8 to 21.2 +/- 2.5 teragrams of CH4 a year, in addition to the 20.5 +/- 5.3 teragrams a year emitted regionally from other sources. Furthermore, we provide a topdown regional estimate of CH4 emissions of 42.7 +/- 5.6 teragrams of CH4 a year for the Amazon basin, based on regular vertical lower-troposphere CH4 profiles covering the period 2010-2013. We find close agreement between our top-down and combined bottom-up estimates, indicating that large CH4 emissions from trees adapted to permanent or seasonal inundation can account for the emission source that is required to close the Amazon CH4 budget. Our findings demonstrate the importance of tree stem surfaces in mediating approximately half of all wetland CH4 emissions in the Amazon floodplain, a region that represents up to one-third of the global wetland CH4 source when trees are combined with other emission sources.

  • 20.
    Pedroni Barreto, Davi
    et al.
    University of Federal Rio de Janeiro, Brazil.
    Conrad, Ralf
    Max Planck Institute Terr Microbiol, Germany.
    Klose, Melanie
    Max Planck Institute Terr Microbiol, Germany.
    Claus, Peter
    Max Planck Institute Terr Microbiol, Germany.
    Enrich Prast, Alex
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Distance-Decay and Taxa-Area Relationships for Bacteria, Archaea and Methanogenic Archaea in a Tropical Lake Sediment2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 10, p. e110128-Article in journal (Refereed)
    Abstract [en]

    The study of of the distribution of microorganisms through space (and time) allows evaluation of biogeographic patterns, like the species-area index (z). Due to their high dispersal ability, high reproduction rates and low rates of extinction microorganisms tend to be widely distributed, and they are thought to be virtually cosmopolitan and selected primarily by environmental factors. Recent studies have shown that, despite these characteristics, microorganisms may behave like larger organisms and exhibit geographical distribution. In this study, we searched patterns of spatial diversity distribution of bacteria and archaea in a contiguous environment. We collected 26 samples of a lake sediment, distributed in a nested grid, with distances between samples ranging from 0.01 m to 1000 m. The samples were analyzed using T-RFLP (Terminal restriction fragment length polymorphism) targeting mcrA (coding for a subunit of methyl-coenzyme M reductase) and the genes of Archaeal and Bacterial 16S rRNA. From the qualitative and quantitative results (relative abundance of operational taxonomic units) we calculated the similarity index for each pair to evaluate the taxa-area and distance decay relationship slopes by linear regression. All results were significant, with mcrA genes showing the highest slope, followed by Archaeal and Bacterial 16S rRNA genes. We showed that the microorganisms of a methanogenic community, that is active in a contiguous environment, display spatial distribution and a taxa-area relationship.

  • 21.
    Peixoto, R. B.
    et al.
    University of Federal Rio de Janeiro, Brazil.
    Marotta, H.
    University of Federal Fluminense, Brazil.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Floating Aquatic Macrophytes Can Substantially Offset Open Water CO2 Emissions from Tropical Floodplain Lake Ecosystems2016In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, no 4, p. 724-736Article in journal (Refereed)
    Abstract [en]

    Tropical floodplain lake ecosystems are recognized as important sources of carbon (C) from the water to the atmosphere. They receive large amounts of organic matter and nutrients from the watershed, leading to intense net heterotrophy and carbon dioxide (CO2) emission from open waters. However, the role of extensive stands of floating macrophytes colonizing floodplains areas is still neglected in assessments of net ecosystem exchange of CO2 (NEE). We assessed rates of air-lake CO2 flux using static chambers in both open waters and waters covered by the widespread floating aquatic macrophyte (water hyacinth; Eichornia sp.) in two tropical floodplain lakes in Pantanal, Brazil during different hydrological seasons. In both lakes, areas colonized by floating macrophytes were a net CO2 sink during all seasons. In contrast, open waters emitted CO2, with higher emissions during the rising and high water periods. Our results indicate that the lake NEE can be substantially overestimated (fivefold or more in the studied lakes) if the carbon fixation by macrophytes is not considered. The contribution of these plants can lead to neutral or negative NEE (that is, net uptake of CO2) on a yearly basis. This highlights the importance of floating aquatic macrophytes for the C balance in shallow lakes and extensive floodplain areas.

  • 22.
    Peixoto, Roberta B.
    et al.
    University of Federal Rio de Janeiro, Brazil.
    Machado-Silva, Fausto
    University of Federal Rio de Janeiro, Brazil.
    Marotta, Humberto
    University of Federal Fluminense, Brazil.
    Enrich Prast, Alex
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Bastviken, David
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Spatial versus Day-To-Day Within-Lake Variability in Tropical Floodplain Lake CH4 Emissions - Developing Optimized Approaches to Representative Flux Measurements2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 4, p. e0123319-Article in journal (Refereed)
    Abstract [en]

    Inland waters (lakes, rivers and reservoirs) are now understood to contribute large amounts of methane (CH4) to the atmosphere. However, fluxes are poorly constrained and there is a need for improved knowledge on spatiotemporal variability and on ways of optimizing sampling efforts to yield representative emission estimates for different types of aquatic ecosystems. Low-latitude floodplain lakes and wetlands are among the most high-emitting environments, and here we provide a detailed investigation of spatial and day-to-day variability in a shallow floodplain lake in the Pantanal in Brazil over a five-day period. CH4 flux was dominated by frequent and ubiquitous ebullition. A strong but predictable spatial variability (decreasing flux with increasing distance to the shore or to littoral vegetation) was found, and this pattern can be addressed by sampling along transects from the shore to the center. Although no distinct day-to-day variability were found, a significant increase in flux was identified from measurement day 1 to measurement day 5, which was likely attributable to a simultaneous increase in temperature. Our study demonstrates that representative emission assessments requires consideration of spatial variability, but also that spatial variability patterns are predictable for lakes of this type and may therefore be addressed through limited sampling efforts if designed properly (e.g., fewer chambers may be used if organized along transects). Such optimized assessments of spatial variability are beneficial by allowing more of the available sampling resources to focus on assessing temporal variability, thereby improving overall flux assessments.

  • 23.
    Peruzzi Oliveira, Vinicius
    et al.
    Universidade Federal do Rio de Janeiro (UFRJ), Departamento de Biologia Marinha, Brazil.
    Ignacio, Barbara Lage
    Universidade Federal de São Paulo (UNIFESP), Departamento de Ciências do Mar, Brazil.
    Martins, Nuno Tavares
    Universidade de São Paulo (USP), Instituto de Biociências, Brazil.
    Dobler, Leticia
    Universidade Federal do Rio de Janeiro (UFRJ), Instituto de Química, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Universidade Federal do Rio de Janeiro (UFRJ), Departamento de Botânica, Brazil.
    The Ulva spp. Conundrum: What Does the Ecophysiology of Southern Atlantic Specimens Tell Us?2019In: Journal of Marine Biology, ISSN 1687-9481, E-ISSN 1687-949X, Journal of Marine Biology, ISSN 1687-9481, article id 5653464Article in journal (Refereed)
    Abstract [en]

    Species of the genus Ulva are common in anthropogenically disturbed areas and have been reported as the cause of green tides in many areas of the world. In addition, they rank among the main marine groups used in a wide range of commercial applications. By displaying few distinctive morphological characters, some taxonomical identifications are difficult and the genus is under a conundrum. Our aims were to provide ecophysiological information about three Ulva species in response to abiotic factors and to evaluate the proposal of ecophysiological information and the chlorophyll-a fluorescence technique as auxiliary tool to resolve the long-standing taxonomic confusion. We hypothesize that three cooccurring specimens (U. fasciata Delile, U. lactuca Linnaeus, and U. rigida C. Agardh) have different ecophysiological responses (as measured by the effective quantum yield of photosystem II by pulse amplitude modulated fluorometers) under manipulated conditions of temperature and nutrient concentration. Ulva lactuca and U. rigida showed different photosynthetic efficiencies related to temperature, whereas no difference was recorded for U. fasciata individuals. These results provide a reasonable explanation for the variability in spatial and temporal abundance of these species of Ulva on rocky shores. We proposed the use of ecophysiological information by chlorophyll-a fluorescence as an auxiliary tool to corroborate the taxonomic distinction of Ulva species. We reinforce the statement of U. fasciata and U. lactuca as distinct valid species.

  • 24.
    Pinho, L.
    et al.
    University of Federal Rio de Janeiro, Brazil; IMEDEA CSIC UIB, Spain; University of Estado Rio De Janeiro, Brazil.
    Duarte, C. M.
    IMEDEA CSIC UIB, Spain; KAUST, Saudi Arabia.
    Marotta, H.
    University of Federal Fluminense, Brazil; University of Federal Fluminense, Brazil.
    Enrich Prast, Alex
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Temperature dependence of the relationship between pCO(2) and dissolved organic carbon in lakes2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 3, p. 865-871Article in journal (Refereed)
    Abstract [en]

    The relationship between the partial pressure of carbon dioxide (pCO(2)) and dissolved organic carbon (DOC) concentration in Brazilian lakes, encompassing 225 samples across a wide latitudinal range in the tropics, was tested. Unlike the positive relationship reported for lake waters, which was largely based on temperate lakes, we found no significant relationship for low-latitude lakes (< 33 degrees), despite very broad ranges in both pCO(2) and DOC levels. These results suggest substantial differences in the carbon cycling of low-latitude lakes, which must be considered when upscaling limnetic carbon cycling to global scales.

  • 25.
    Sanders, Luciana M.
    et al.
    Southern Cross University, Australia.
    Taffs, Kathryn H.
    Southern Cross University, Australia.
    Stokes, Debra
    Southern Cross University, Australia.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Sanders, Christian J.
    Southern Cross University, Australia.
    Pu240+239 DEPOSITIONAL SIGNATURES AS A VIABLE GEOCHRONOLOGICAL TOOL IN THE AMAZON BASIN2017In: Geochronometria, ISSN 1733-8387, E-ISSN 1897-1695, Vol. 44, no 1, p. 142-149Article in journal (Refereed)
    Abstract [en]

    Anthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20th century. The Pu-240 + Pu-239 (Pu240+239) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year(-1)), Tapajos (10.2 and 2.4 mm year(-1)) and Madeira (3.4, 4.2 and 6.2 mm year(-1)). The results from this study show that Pu240+239 fallout activities, and the well documented (Pu-240/Pu-239) atomic ratios of the above ground nuclear tests which began in the 1950s, are sufficient and well preserved in Amazon flood-plain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the Pu240+239 and Pb-210 methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20th century. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous similar to 60 years) along the Amazon Basin.

  • 26.
    Sanders, Luciana M.
    et al.
    Southern Cross Univ, Australia.
    Taffs, Kathryn
    Southern Cross Univ, Australia.
    Stokes, Debra
    Southern Cross Univ, Australia.
    Sanders, Christian J.
    Southern Cross Univ, Australia.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Amora, Leonardo Nogueira
    Univ Fed Fluminense, Brazil.
    Marotta, Humberto
    Univ Fed Fluminense, Brazil.
    Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarem, Brazil2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 2, p. 447-455Article in journal (Refereed)
    Abstract [en]

    Forests along the Amazon Basin produce significant quantities of organic material, a portion of which is deposited in floodplain lakes. Deforestation in the watershed may then have potentially important effects on the carbon fluxes. In this study, a sediment core was extracted from an Amazon floodplain lake to examine the relationship between carbon burial and changing land cover and land use. Historical records from the 1930s and satellite data from the 1970s were used to calculate deforestation rates between 1930 to 1970 and 1970 to 2010 in four zones with different distances from the margins of the lake and its tributaries (100, 500, 1000 and 6000m buffers). A sediment accumulation rate of similar to 4 mmyr(-1) for the previous similar to 120 years was determined from the Pu240+239 signatures and the excess Pb-210 method. The carbon burial rates ranged between 85 and 298 gCm(-2) yr(-1), with pulses of high carbon burial in the 1950s, originating from the forest vegetation as indicated by delta C-13 and delta N-15 signatures. Our results revealed a potentially important spatial dependence of the organic carbon (OC) burial in Amazon lacustrine sediments in relation to deforestation rates in the catchment. These deforestation rates were more intense in the riparian vegetation (100m buffer) during the period 1930 to 1970 and the larger open water areas (500, 1000 and 6000m buffer) during 1970 to 2010. The continued removal of vegetation from the interior of the forest was not related to the peak of OC burial in the lake, but only the riparian deforestation which peaked during the 1950s. Therefore, this supports the conservation priority of riparian forests as an important management practice for Amazon flooded areas. Our findings suggest the importance of abrupt and temporary events in which some of the biomass released by deforestation, especially restricted to areas along open water edges, might reach the depositional environments in the floodplain of the Amazon Basin.

  • 27.
    Signori, Camila N.
    et al.
    Univ Sao Paulo, Brazil.
    Pellizari, Vivian H.
    Univ Sao Paulo, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Fed Rio De Janeiro UFRJ, Brazil.
    Sievert, Stefan M.
    WHOI, MA 02543 USA.
    Spatiotemporal dynamics of marine bacterial and archaeal communities in surface waters off the northern Antarctic Peninsula2018In: Deep-sea research. Part II, Topical studies in oceanography, ISSN 0967-0645, E-ISSN 1879-0100, Vol. 149, p. 150-160Article in journal (Refereed)
    Abstract [en]

    Seasonal changes in taxonomic and functional diversity of microbial communities in polar regions are commonly observed, requiring strategies of microbes to adapt to the corresponding changes in environmental conditions. These natural fluctuations form the backdrop for changes induced by anthropogenic impacts. The main goal of this study was to assess the seasonal and temporal changes in bacterial and archaeal diversity and community structure off the northern Antarctic Peninsula over several seasons (spring, summer, autumn) from 2013 to 2015. Ten monitoring stations were selected across the Gerlache and Bransfield Straits and nearby Elephant Island, and archaeal and bacterial communities examined by amplicon sequencing of 16S rRNA genes. Alpha-diversity indices were higher in spring and correlated significantly with temperature. Spring was characterized by the presence of SAR11, and microbial communities remaining from winter, including representatives of Thaumarchaeota (Nimosopurnilus), Euryarchaeota, members of Oceanospirillales, SAR324. Summer and autumn were characterized by a high prevalence of Flavobacteria (NS5 marine group and Polaribacter), Alphaproizobacteria (Rhodobacterales and SAR11 Glade) and Gammaproteobacteria (Oceanospirillales/Balneatrix and Celivibrionales), generally known to be associated with organic matter degradation. Relatively higher abundance of phytoplankton groups occurred in spring, mainly characterized by the presence of the haptophyte Phaeocystis and the diatom Corethron, influencing the succession of heterotrophic bacterial communities. Microbial diversity and community structure varied significantly over time, but not over space, i.e., were similar between monitoring stations for the same time. In addition, the observed interannual variability in microbial community structure might be related to an increase in sea surface temperature. Environmental conditions related to seasonal variation, including temperature and most likely phytoplankton derived organic matter, appear to have triggered the observed shifts in microbial communities in the waters off the northern Antarctic Peninsula.

    The full text will be freely available from 2019-12-20 00:01
  • 28.
    Signori, Camila N.
    et al.
    University of Federal Rio de Janeiro, Brazil; University of Federal Rio de Janeiro, Brazil; Woods Hole Oceanog Institute, MA 02543 USA.
    Thomas, Franois
    Woods Hole Oceanog Institute, MA 02543 USA.
    Enrich Pras, Alex
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Pollery, Ricardo C. G.
    University of Federal Rio de Janeiro, Brazil.
    Sievert, Stefan M.
    Woods Hole Oceanog Institute, MA 02543 USA.
    Microbial diversity and community structure across environmental gradients in Bransfield Strait Western Antarctic Peninsula2014In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 5, no 647Article in journal (Refereed)
    Abstract [en]

    The Southern Ocean is currently subject to intense investigations, mainly related to its importance for global biogeochemical cycles and its alarming rate of warming in response to climate change. Microbes play an essential role in the functioning of this ecosystem and are the main drivers of the biogeochemical cycling of elements. Yet, the diversity and abundance of microorganisms in this system remain poorly studied, in particular with regards to changes along environmental gradients. Here, we used amplicon sequencing of 16S rRNA gene tags using primers covering both Bacteria and Archaea to assess the composition and diversity of the microbial communities from four sampling depths (surface, the maximum and minimum of the oxygen concentration, and near the seafloor) at 10 oceanographic stations located in Bransfield Strait [northwest of the Antarctic Peninsula (AP)] and near the sea ice edge (north of the AP). Samples collected near the seafloor and at the oxygen minimum exhibited a higher diversity than those from the surface and oxygen maximum for both bacterial and archaeal communities. The main taxonomic groups identified below 100 m were Thaumarchaeota, Euryarchaeota and Proteobacteria (Gamma-, Delta-, Beta-, and Alphaproteobacteria), whereas in the mixed layer above 100 m Bacteroidetes and Proteobacteria (mainly Alpha- and Gammaproteobacteria) were found to be dominant. A combination of environmental factors seems to influence the microbial community composition. Our results help to understand how the dynamic seascape of the Southern Ocean shapes the microbial community composition and set a baseline for upcoming studies to evaluate the response of this ecosystem to future changes.

  • 29.
    Signori, Camila N.
    et al.
    Univ Fed Rio de Janeiro, Brazil; Univ Sao Paulo, Brazil.
    Valentin, Jean L.
    Univ Fed Rio de Janeiro, Brazil.
    Pollery, Ricardo C. G.
    Univ Fed Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Fed Rio de Janeiro, Brazil.
    Temporal Variability of Dark Carbon Fixation and Bacterial Production and Their Relation with Environmental Factors in a Tropical Estuarine System2018In: Estuaries and Coasts, ISSN 1559-2723, E-ISSN 1559-2731, Vol. 41, no 4, p. 1089-1101Article in journal (Refereed)
    Abstract [en]

    Dark carbon fixation (DCF) is considered an important energy source in aquatic environments, although it has been neglected for a long time. DCF is known to be relevant in ecosystems associated with redoxclines, shallow-water sulfide-rich habitats, deep-sea vents, cold seeps, and even in coastal waters associated with upwelling events. The aim of this study was to evaluate the relative importance of DCF in relation to heterotrophic bacterial production (BP), as well as how these rates affect each other, and how they are influenced by the environmental factors. This study was conducted monthly during 2 years in a tropical eutrophic bay (Guanabara Bay), where two stations were sampled and compared. DCF and BP were measured by C-14-bicarbonate and H-3-leucine incorporation, respectively, and incubations in the dark. Our results showed that DCF is not a quantitatively relevant process in this estuarine system, when compared to heterotrophic BP, and possibly occurred via anaplerotic reactions. Relatively higher DCF rates were associated with less oxygenated waters at the more polluted station and during the wet summer-spring, when the water column is more stratified. BP rates presented clear spatial patterns, according to pollution and depth gradients, with higher rates in more polluted areas, and also at surface waters. The hydrodynamics combined with other environmental conditions (precipitation, temperature, dissolved organic carbon, and nutrients) may control the distribution of DCF and BP over space and time. The allochthonous inputs of organic matter are more important than DCF-derived organic carbon to bacterioplankton in this polluted and eutrophic bay, where the heterotrophic metabolism prevails.

  • 30.
    Valle, Juliana
    et al.
    Helmholtz Zentrum Munich, Germany.
    Gonsior, Michael
    Univ Maryland, MD 20688 USA.
    Harir, Mourad
    Helmholtz Zentrum Munich, Germany; Tech Univ Munich, Germany.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Fed Rio de Janeiro, Brazil.
    Schmitt-Kopplin, Philippe
    Helmholtz Zentrum Munich, Germany; Technische Universität München, Freising-Weihenstephan, Germany.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Conrad, Ralf
    Max Planck Inst Terr Microbiol, Germany.
    Hertkorn, Norbert
    Helmholtz Zentrum Munich, Germany.
    Extensive processing of sediment pore water dissolved organic matter during anoxic incubation as observed by high-field mass spectrometry (FTICR-MS)2018In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 129, p. 252-263Article in journal (Refereed)
    Abstract [en]

    Dissolved organic matter (DOM) contained in lake sediments is a carbon source for many microbial degradation processes, including aerobic and anaerobic mineralization. During anaerobic degradation, DOM is partially consumed and transformed into new molecules while the greenhouse gases methane (CH4) and carbon dioxide (CO2) are produced. In this study, we used ultrahigh resolution mass spectrometry to trace differences in the composition of solid-phase extractable (PPL resin) pore water DOM (SPE-DOM) isolated from surface sediments of three boreal lakes before and after 40 days of anoxic incubation, with concomitant determination of CH4 and CO2 evolution. CH4 and CO2 production detected by gas chromatography varied considerably among replicates and accounted for fractions of similar to 2-4 x 10(-4) of sedimentary organic carbon for CO2 and similar to 0.8-2.4 x 10(-5) for CH4. In contrast, the relative changes of key bulk parameters during incubation, such as relative proportions of molecular series, elemental ratios, average mass and unsaturation, were regularly in the percent range (1-3% for compounds decreasing and 4-10% for compounds increasing), i.e. several orders of magnitude higher than mineralization alone. Computation of the average carbon oxidation state in CHO molecules of lake pore water DOM revealed rather non-selective large scale transformations of organic matter during incubation, with depletion of highly oxidized and highly reduced CHO molecules, and formation of rather non-labile fulvic acid type molecules. In general, proportions of CHO compounds slightly decreased. Nearly saturated CHO and CHOS lipid-like substances declined during incubation: these rather commonplace molecules were less specific indicators of lake sediment alteration than the particular compounds, such as certain oxygenated aromatics and carboxyl-rich alicyclic acids (CRAM) found more abundant after incubation. There was a remarkable general increase in many CHNO compounds during incubation across all lakes. Differences in DOM transformation between lakes corresponded with lake size and water residence time. While in the small lake Svarttjarn, CRAM increased during incubation, lignin-and tannin-like compounds were enriched in the large lake Bisen, suggesting selective preservation of these rather non-labile aromatic compounds rather than recent synthesis. SPE-DOM after incubation may represent freshly synthesized compounds, leftover bulk DOM which is primarily composed of intrinsically refractory molecules and/or microbial metabolites which were not consumed in our experiments. In spite of a low fraction of the total DOM being mineralized to CO2 and CH4, the more pronounced change in molecular DOM composition during the incubation indicates that diagenetic modification of organic matter can be substantial compared to complete mineralization. (C) 2017 Elsevier Ltd. All rights reserved.

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