Nutrient dynamics of decomposing leaves from Amazonian floodplain forest species in water

Decomposition experiments were performed in freshwater tanks using fresh leaves of four Amazonian tree species from blackwater and whitewater floodplain forests. Weight loss, loss of the major elements, Na, K, Mg, Ca, N and P from the leaves, and release of these elements into the water were studied during a four month period. Based on the nutrient contents of fresh multispecies leaf litter and data on the shedding of this litter, nutrient inputs from leaves into bodies of blackwater and whitewater in the forests during flood period were calculated. The input of dissolved inorganic N, P and K may be as great or even greater than input from river water, indicating the importance of the floodplain forest as nutrient pump from sediments into the water

Seasonal variation in the major cation (Na, K, Mg, and Ca) content of the water of Lago Camaleão, an Amazonian floodplain- lake near Manaus, Brazil

Changes in the major cation content (Na, K, Mg and Ca) of the Lago Camaleão, one of the várzea lakes on an island in the Rio Solimões/Amazonas near Manaus were followed during one year. Comparative changes were also followed in the Rio Solimões. Changes in the electrolyte content of the lake water, presented as total maior cation content, are extremely great during the period of investigation. Nov. 1980 to Nov. 1981, and show a pronounced annual periodicity. During the low water period (Oct. 1981) the ion concentration reached its maximum and was more than 15 times higher than in the river at the same time. With rising water level, in flow of comparatively electrolyte poor water from the river and simultaneously increasing rain fall dilute the water in the lake. In the following months there is a relatively sudden reduction of the electrolyte content of the lake water. By the time of high water the levels have fallen almost to those of the river. With falling water level concentrations of major cations at first increase very slowly followed by an abrupt change within one month, from approx. 20 mg major cations/l to approx. 230 mg/l. Investigation of different lake sections showed that the electrolyte content is not uniform throughout the lake. Concentrations rise from the lake entrance to the inner part of the lake, so that the lake sections distant from the river are up to fifteen times as rich in electrolytes as the river itself. The changes in total ion content are accompanied by marked changes in the chemical composition of the lake water during the year, i. e. in the relative proportions of each of the four elements (Na, K, Mg and Ca). Greatest changes are shown by the element K. The deeper water of the lake during the high water period is richer in K probably due to the release of elements from the decomposition of K-rich terrestrial and aquatic macrophytes. The uptake of large quantities of nutrients from the system for the growth of macrophytic vegetation, the accumulation of nutrients in macrophytes and sediment, and the release of these nutrients during decomposition and resuspension are among the most important factors contributing to the electrolyte budget in the Lago Camaleão

Mapping and characterization of vegetation units by means of Landsat imagery and management recommendations for the Pantanal of Mato Grosso (Brazil), north of Poconé

In the present study, remote sensing in the northern region of Poconé-MT was used to identify vegetation categories, which were then mapped and characterized. The goal in generating the map was to provide information needed to support sustainable use and to formulate conservation policies. Vegetation units were identified and classified using digital images that were taken in 1990 by the Landsat Thematic Mapperc Satellite and then processed using ERDAS software. First, the vegetation classes were systematically defined. In a preliminary interpretation of the image data, Landsat-TM bands that allowed the best visual differentiation of these classes were selected and the image was georeferenced. Routes for trips to the study area to collect truth data (training samples) for further supervised classification were then determined. These data were subsequently classified according to The System of Classification of Brazilian Vegetation (VELLOSO et al. 1991), which has been used in other physiognomic maps of the Pantanal, in order to make our results comparable to those from other mappings. In addition, some modifications of this system were made due to the particular characteristics of the Pantanal and the scale used for this map. Six classes and 16 subclasses were defined for part I of the vegetation map of Pantanal, Mato Grosso, Brazil, specifically, the area north of Poconé. A distinction was made between the vegetation units of the Paraguayan Depression and those of the Pantanal due to the different characteristics of the vegetation from these two regions, and particularly the role played by inundation. The phytoecological region savanna (cerrado) covers a large part of the total area (53.05%) and consists of five sub-classes. Two forest classeswere identified: seasonal semideciduous forest and seasonal deciduous forest. These two phytoecological classes occupied 16.21 % of the total mapped area; 14.45% of the area has been strongly modified by humans (agriculture, pasture, gold mine, and construction); 0.80% is covered during the dry season by perennial water bodies. Based upon ground truth data and regional field experience, ten eco-zones are proposed and suggestions for sustainable management and conservation measures are discussed

Carbon Dioxide Fluxes to the Atmosphere From Waters Within Flooded Forests in the Amazon Basin

Inundated tropical forests are underrepresented in analyses of the global carbon cycle and constitute 80% of the surface area of aquatic environments in the lowland Amazon basin. Diel variations in CO2 concentrations and exchanges with the atmosphere were investigated from August 2014 to September 2016 in two flooded forests sites with different wind exposure within the central Amazon floodplain (3°23′S, 60°18′W). CO2 profiles and estimates of air–water gas exchange were combined with ancillary environmental measurements. Surface CO2 concentrations ranged from 19 to 329 μM, CO2 fluxes ranged from −0.8 to 55 mmol m−2 hr−1 and gas transfer velocities ranged from 0.2 to 17 cm hr−1. CO2 concentrations and fluxes were highest during the high water period. CO2 fluxes were three times higher at a site with more wind exposure (WE) compared to one with less exposure (WP). Emissions were higher at the WP site during the day, whereas they were higher at night at the WE site due to vertical mixing. CO2 concentrations and fluxes were lower at the W P site following an extended period of exceptionally low water. The CO2 flux from the water in the flooded forest was about half of the net primary production of the forest estimated from the literature. Mean daily fluxes measured in our study (182 ± 247 mmol m−2d−1) are higher than or similar to the few other measurements in waters within tropical and subtropical flooded forests and highlight the importance of flooded forests in carbon budgets

Fish Structure in Channel Networks of a Large Anabranching Floodplain: Effect of Isolation/Connection Processes

Channel networks of floodplain rivers are the main routes for water, sediment, organic matter, and aquatic organisms between main channels and lakes, playing a substantial role in floodplain dynamics. Despite their importance most investigations in large floodplain rivers focus on main channels and lentic water bodies. This research deals with fish assemblage variations in different lotic sites (scour holes and straight reaches) of one of the many channels which shape the wide anabranching floodplain of the middle reach of the Paraná River. We considered the influence of environmental factors, such as hydro-geomorphological features and water quality of the channel, connections with surrounding lentic water bodies, seasonality, and interannual flow variations. The results showed two main ecological patterns closely related to floodplain connectivity. In-channel habitat heterogeneity has low influence on fish assemblages when minor channels are connected to significant flooded areas (sampling period 2013–2016). Spatial or temporal predictions of fish structure during these stages are not easy due to the interaction of several environmental factors. However, during very low water levels (winter of 2018) most lentic areas become isolated from the nearby channel network, and floodplain fish are forced to move into the numerous scour holes of the floodplain channels where water conditions resemble those in lentic habitats. Our work highlights the importance of in-channel characteristics of floodplain river networks and their crucial role for fish conservation, particularly during very low water stages.Fil: Abrial, Elie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Espínola, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Amsler, Mario Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Rabuffetti, Ana Pia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Latosinski, Francisco Guillermo. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas. Departamento de Hidráulica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Szupiany, Ricardo Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas. Departamento de Hidráulica; ArgentinaFil: Eurich, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Blettler, Martin Cesar Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

Population characteristics of Shovelnose Sturgeon during low- and high-water conditions in the lower Platte River, Nebraska

Cycles of low- and high-water periods (i.e., years) in river systems are natural occurrences, but understanding how cyclical climatological patterns affect fishes, especially long-lived species, is unclear. We assessed Shovelnose Sturgeon population dynamics between a period of low- (2001-2004) and high- (2009-2012) water years in the lower Platte River, Nebraska. Low-flow periods in the lower Platte River can cause disconnection(s) between upstream and downstream reaches resulting in isolated pools and elevated water temperatures leading to stressful situations for aquatic life and possible mortality. Our data show no measurable differences between key population indices between flow condition periods which is consistent with current paradigms for long-lived fish species. Shovelnose Sturgeon relative weights were generally \u3e 80 during both low- and high-water periods and the size structure did not differ between the two periods. Shovelnose Sturgeon abundances, however, were greater during high-water conditions compared to low-water conditions (Kruskal-Wallis: χ2 = 6.15, d.f. = 1, P = 0.01). Shovelnose Sturgeon may have migrated to more suitable habitats during low-water periods to seek refuge allowing these individuals to return during more suitable conditions. Shovelnose Sturgeon and other riverine fish have evolved in a variable environment and have been able to endure relatively minor anthropogenic changes within the lower Platte River. Rivers like the lower Platte River that have retained much of their original physical features and flow regimes are likely key components for the resistance and resilience of riverine species. However, as alterations to landscapes continue and uncertainty exists surrounding future climate predictions, it is unknown how these riverine species will be able to adapt to future changes. The reduction in anthropogenic changes that disrupt flow regimes and increasing connectivity among river systems could provide more fish refuge during stressful conditions helping to protect these riverine species

LHC sensitivity to lepton flavour violating Z boson decays

We estimate that the LHC could set bounds BR(Z -> mu^\pm e^\mp) < 4.1 * 10^{-7} and BR(Z -> tau^\pm mu^\mp)< 3.5 * 10^{-6} (at 95% C.L.) with 20 inverse fb of data at 8 TeV. A similar sensitivity can be anticipated for Z -> tau^\pm e^\mp, because we consider leptonic tau decays such that Z -> tau^+ mu^- gives e^+ \mu^- +$ invisibles. These limits can be compared to the LEP1 bounds of order 10^{-5} to 10^{-6}. Such collider searches are sensitive to a flavour-changing effective Z coupling which is energy dependent, so are complementary to bounds obtained from tau to 3mu and mu to 3e.Comment: 11 pages, 2 figures, version for publicatio

Further Evidence for the Decay K+ to pi+ neutrino-antineutrino

Additional evidence for the rare kaon decay K+ to pi+ neutrino-antineutrino has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211<P<229 MeV/c, bringing the total for the combined data set to two. Including all data taken, the backgrounds were estimated to contribute 0.15 pm 0.05 events. The branching ratio is B=1.57^{+1.75}_{-0.82} 10^{-10}.Comment: 10 pages, 2 figure

Tests of model of color reconnection and a search for glueballs using gluon jets with a rapidity gap

Gluon jets with a mean energy of 22 GeV and purity of 95% are selected from hadronic Z0 decay events produced in e+e- annihilations. A subsample of these jets is identified which exhibits a large gap in the rapidity distribution of particles within the jet. After imposing the requirement of a rapidity gap, the gluon jet purity is 86%. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We use our data to test three QCD models which include a simulation of color reconnection: one in the Ariadne Monte Carlo, one in the Herwig Monte Carlo, and the other by Rathsman in the Pythia Monte Carlo. We find the Rathsman and Ariadne color reconnection models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and that the description of inclusive Z0 data is significantly degraded in this case. We conclude that color reconnection as implemented by these two models is disfavored. The signal from the Herwig color reconnection model is less clear and we do not obtain a definite conclusion concerning this model. In a separate study, we follow recent theoretical suggestions and search for glueball-like objects in the leading part of the gluon jets. No clear evidence is observed for these objects.Comment: 42 pages, 18 figure

Scaling violations of quark and gluon jet fragmentation functions in e+e- annihilations at sqrt(s) = 91.2 and 183-209 GeV

Flavour inclusive, udsc and b fragmentation functions in unbiased jets, and flavour inclusive, udsc, b and gluon fragmentation functions in biased jets are measured in e+e- annihilations from data collected at centre-of-mass energies of 91.2, and 183-209 GeV with the OPAL detector at LEP. The unbiased jets are defined by hemispheres of inclusive hadronic events, while the biased jet measurements are based on three-jet events selected with jet algorithms. Several methods are employed to extract the fragmentation functions over a wide range of scales. Possible biases are studied in the results are obtained. The fragmentation functions are compared to results from lower energy e+e- experiments and with earlier LEP measurements and are found to be consistent. Scaling violations are observed and are found to be stronger for the fragmentation functions of gluon jets than for those of quarks. The measured fragmentation functions are compared to three recent theoretical next-to-leading order calculations and to the predictions of three Monte Carlo event generators. While the Monte Carlo models are in good agreement with the data, the theoretical predictions fail to describe the full set of results, in particular the b and gluon jet measurements.Comment: 46 pages, 17 figures, Submitted to Eur. Phys J.