bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Biogeochemistry of Sediments from the Madeira Abyssal Plain — Preliminary Results
Authors: Wolff George A. , Boardman Danny , Horsfall Ian , Sutton Ian , Davis Natalie , Chester Roy , Ripley Mark , Lewis C. Antony , Rowland Steven J. , Patching John , Ferrero Tim , Lambshead P. John D. , Rice Anthony L. 
Published: February 2007

AbstractThe organic biogeochemistry of surface sediments from the Madeira Abyssal Plain has been investigated. Total organic carbon contents, organic carbon to nitrogen ratios, concentrations of hydrolysable amino acids, hydrolysable carbohydrates and lipids have been determined. In one case, the detailed lipid compositions were also investigated.The sedimentary geochemistry appears to have been strongly influenced by the recent (ca. 1000 yrs.) deposition of a turbidite. Normally labile lipids are present in high concentrations through the turbidite and the numbers of the most abundant metazoan meiofauna (nematodes) closely correlates with the concentrations of the former. Concentrations of hydrolysable amino acids and carbohydrates, relative to total organic carbon, also decrease through the turbidite layer, but in the case of the carbohydrates tend to be higher in the underlying pelagic sediments. Deeper sediments are more oxidised than those at the surface. The concentration profile for manganese in one of the examined cores suggests that this anomaly arises through the action of manganese‐reducing bacteria that are present in pelagic sediments underlying the turbidite.
Limnology of a Warm Hypertrophic Wastewater Reservoir in Israel. II. Changes in Water Quality
Authors: Juanico Marcelo 
Published: February 2007

AbstractFactor analysis was used to identify the processes responsible for the changes in water quality in a stratified wastewater reservoir. These reservoirs are well suited to study hypertrophic conditions. In the epilimnion, the main source of variablility was the external loading due to variations in wastewater inputs and water level (volume) of the reservoir. The second source was the seasonal climatic changes affecting photosynthesis. The third source was differences between night and day processes affecting REDOX potential. In the hypolimnion, the main source of variability was organic loading but due to both external loading (wastewater inputs) and internal loading (compounds released from the sediments). The second source was related to the input of chlorophyll into the hypolimnion, which were external (entry of chlorophyll rich inflow from a waste stabilization pond) and/or internal (input of chlorophyll from upper layers due to water column mixing).
Horizontal and Vertical Distribution of the Zebra Mussel (Dreissena polymorpha, Pallas) Larvae in the Modrac Reservoir, Bosnia and Herzegovina
Authors: Erben Radovan , Lajtner Jasna , Leiner Srećko , Bjelić Sabrija 
Published: February 2007

AbstractIn the Modrac Reservoir, loaded with coal separation suspended material, rapid development of the zebra mussel (Dreissena polymorpha) took place from at least 1987. It is probably the first distinguished “infection” for this part of Balkan Peninsula, caused by this organism. Horizontal and vertical distribution of this mussel, at 15 different reservoir profiles, had been investigated.
Influence du substrat sur la répartition des Crustacés stygobies interstitiels du Haut‐Atlas occidental
Authors: de Bovee F. , Yacoubi‐Khebiza M. , Coineau N. , Boutin C. 
Published: February 2007

AbstractThe interstitial stygobiont distributions of two rivers in the western High Atlas is analyzed in relation with sediment granulometry. Sixteen stations were sampled along the rivers N'Fis and Zat and their tributaries. Granulometry analyses were performed. Three grain size sediment types constitute the subterranean biotopes and reflect the local hydrodynamical conditions. The main rivers stations, which undergo frequent natural or human disturbances, are characterized by a high content of fine sediment; in contrast, tributaries stations show coarse and well‐classified sediments due to more stable biotopes and more regular hydrological conditions. The 92 taxa group 28 stygobiontic species with 11 crustaceans species. PCA. based on 16 stations, three faunistic richness indexes and three granulometric factors display a high correlation between coarse grain‐size content and the richness of stygobiontic taxa. A high silt content both limits the interstitial taxa and excludes crustaceans that occur only in coarse gravels. The granulometric preferenda in the species of the amphipod genus Metacrangonyx and isopods Microcerberus. Microcharon and Typhlocirolana are shown on Shepard triangular diagrams. Cohabitation of several species of the same genus could be explained by the occupancy of different ecological niches resulting from the grain‐size proportion.
Picoplankton in Lake Maggiore, Italy
Authors: Callieri Cristiana , Pinolim Maria Luisa 
Published: February 2007

AbstractIn 1992 we examined the morphological characteristics and space‐time distribution of picoplankton cells in Lake Maggiore, a subalpine lake in which oligotrophication is in progress. We measured by image analyser the biovolume of autotrophic (APP), eukaryotic and prokaryotic. and heterotrophic (HPP) picoplankton. Among the APP < 2μm the yellow fluoresceing are the dominating cells in the euphoric zone. The red cells, mainly eukaryotic, on average are only 11% of the total abundance of cells < 5μm. The APP cell numbers range from 9.5 × 103 cells ml−1 to 1.3 × 105 cells ml−1 (average: 5 × 104 cells ml−1). Their mean biovolume shows a minimum value of 7.8mm3 m−3 in March and a maximum of 186.3mm3 m‐3 in September. The contribution of biovolume of yellow cells to total phytoplankton biovolume varies between 0.3% and 27%. suggesting that picocyanobacteria, at this stage of lake recovery, are not yet a dominant component. The HPP cell density is two order of magnitude higher than the APP with a mean value of 2.6 × 106 cells ml−1. APP mean cell size fluctuates from a minimum of 0.5 μm to a maximum of 1.4urn (0.26–1.69μm3 volume), while HPP range from 0.4 to 0.7 um (0.07–0.57 μm3 volume), making it easier to distinguish them on a dimensional basis for most of the year. During the period of thermal stratification, a peak in abundance was noted in the central part of the metalimnion at depths receiving less than 10% of surface irradiance. The total picoplanktonic carbon fraction (APP and HPP) varied from 38 to 384 μgC 1−1 with a mean value of 133μgC 1−1 which represents 42% of POC collected on GF/C filters. Most of the picoplankton carbon is made up of HPP cells (34% of the total POC).
Manipulation of Whole‐Lake Ecosystems and Long‐Term Limnological Observations in the Brandenburg — Mecklenburg Lake District, Germany
Authors: Koschel Rainer 
Published: February 2007

AbstractAn accompanying technical use of ecological effects from pelagic food‐web interactions (biofiltration) or from sediment (nutrient remobilization) can speed up recovery of lake ecosystems and can make restoration programs more effective after external load reductions. At present the comprehensive use of multiple ecotechnological controls for water quality is limited because our knowledge of the many complex interactions, indirect effects and above all the long‐term effects of such operations is insufficient. Beginning in the 1960s we started long‐term limnological analyses of the trophic interactions between community structure and the flow of matter under “manipulated” conditions in whole‐lake experiments at Lake Stechlin (manipulated water circulation and waste heat), Lake Haussee (biomanipulation) and Lake Fuchskuhle (lake‐dividing). This paper summarises changes in abiotic and biotic structures and functions of the manipulated lake ecosystems and discusses the possibilities and limitations of “whole‐lake” experiments.
Possibilities and Limits for Controlling Eutrophication by Biomanipulation
Authors: Benndorf Jürgen 
Published: February 2007

AbstractEcotechnology aims at the implementation of such a complex physical, chemical and/or biological ecosystem structure, which leads to a maximum capacity of the ecosystem to improve the water quality by ecosystem‐internal mechanisms. Numerous ecological control variables can be used in ecotechnology, however only mortality caused by predation, feeding or grazing on all trophic levels provides the possibility of a top‐ down control of the community structure. There are two contrasting concepts regarding the efficiency of top‐down control: (1) the “cascading trophic interactions” hypothesis (Carpenter et al., 1985), which postulates that changes at the top of the food web are transmitted down to primary producers, and (2) the “bottom‐up/top‐down” hypothesis (McQueen et al., 1986), which predicts that top‐down effects are strong at the top but weaken near the bottom of the food web. This paper describes an examination of these concepts by summarizing the effects of strong (Bautzen reservoir) and extremely strong (Lake Gräfenhain) enhancement of the stock of piscivorous fish. Both investigations refer to long‐term whole‐lake experiments. The results seem to confirm the “bottom‐up/top‐down” hypothesis. Effects at the top are strong, although sustained effects regarding dominance of Daphnia are achieved only at an “optimum” (relatively low but not zero) density of zooplanktivorous fish. Far below the optimum density an efficient invertebrate predator was able to compensate almost completely the fish predation pressure on large Daphnia. On the other hand, the optimum density can easily be exceeded during periods when high numbers of 0+ fish occur. Especially the effective control of 0+ fish of the intentionally enhanced piscivorous species is a key problem. At the bottom of the “classical” food web, the effects are restricted to a change of the phytoplankton compositions (mean biomass is not reduced).The contradiction between the latter results and other findings from lakes having lower phosphorus loadings (e. g. Stenson, 1988) can be solved only if the “bottom‐up/top‐down” hypothesis is combined with the hypothesis of a “biomanipulation efficiency threshold of the P‐loading” (Benndorf, 1987). The latter hypothesis predicts that the desired reduction of mean phytoplankton biomass as a strong top‐down effect at the bottom of the food web can be expected only below a threshold of the P‐loading. Below this threshold a set of biomanipulation‐induced indirect effects on phosphorus metabolism causes a reduction of the in‐lake P‐concentration. Consequently, sustained reduction of the phytoplankton biomass by biomanipulation can be achieved only by P‐limitation, which is an indirect bottom‐up effect induced by top‐down control of the food web. Taking into consideration the combination of the “bottom‐up/top‐down” and “P‐threshold” hypothesis, an attempt is made to predict the effects of biomanipulation regarding phytoplankton and water transparency under different conditions of lake morphology, P‐loading and light climate.
Massenentwicklungen von Algen und Wasserlinsen in der Talsperre Bleiloch (Thüringen) — gegenwärtige Situation, Ursachenanalyse und erste Ergebnisse zu deren Verringerung Algal Blooms and Duckweed Covers in the Bleiloch Reservoir (Thuringia) — Actually Situation, Causal Analysis and First Results of its Overcome
Authors: Loth P. , Herschel A. , Schröter K. , Liebert H.‐P. 
Published: February 2007

AbstractThe effects of a decreased sewage release from a cellulose mill on the hypertrophic Bleiloch reservoir were studied. The waste water treatment reduced the concentration of yellow substances in the reservoir and resulted in a more light‐coloured waterbody. It is estimated that the changes in the light attenuation in the Bleiloch reservoir after 1989 can be described as eutrophication. Selected physical, chemical, and biological parameters from 1994 show the effect of changes.Three large pelagic enclosures (diameter 10 m, length 20 m) were installed in the reservoir to assess effects of artifical mixing on phytoplankton biomass and composition. Two circulation techniques have been used in the enclosures (relase of compressed air at the bottom of the enclosure and mechanical mixing, where water was pumped from the surface downward).The investigation demonstrate that the magnitude of seasonal peaks of chlorophyll were depressed in the mixed enclosures during circulation. The results were discussed in comparison with a reference enclosure without mixing and the waterbody of the reservoir. Cryptophytes and other flagellates achieved dominance during mixing in the “air”‐enclosure, while diatoms were the most abundant species in the „pump”︁‐enclosure. The development of filamentous cyanobacteria, which are significant indicators of eutrophication, was disturbed in the enclosures. They were outcompeted by cryptophytes, movable chlorophytes and diatoms.Both mechanical pump and compressed air can be used to control excessive algal growth. Further studies on the dynamics of phytoplankton to artifical mixing are suggested. The results of further studies should design an in situ experiment in the reservoir to reduce algal growth by light limitation.Further on a dense duckweed cover spreads over the surface of the Bleiloch reservoir, which influences the light regime in the waterbody. Therefore factors influencing the duckweed growth were analysed. Special attention was focused on the influence of the pH, consequences of the mixing in the waterbody and the role of resting stages.
Langzeituntersuchungen zur Nitratbelastung des Trinkwassers aus der Talsperre Dröda Long Term Examination of Nitrate Load of Drinking Water from Reservoir Dröda
Authors: Hofmann Reiner , Hallebach Rainer 
Published: February 2007

AbstractThe drinking water reservoir Dröda (Feilebach) is the main and the most important drinking water resource in the destrict Vogtland (Saxonia). Since the establishment of this object the water has got a high nitrate load. In a short period the limit of nitrate for drinking water was exceeded.In the first part there is given a short survey of the general quality of the water of this reservoir, later the nitrate examinations over 25 years are demonstrated. Nearly a every year rhythm and long term trends are noticeable. The yearly variations are mainly based on the seasonal differences of the import of nitrate. The long term trends are interpreted as an effect of the change in agricultural utilization. A small dependence on the yearly rainfall is recognizable. Finally, possibilities are shown to decrease the nitrate load.
Influence of the Addition of Different Metals to an Activated Sludge System on the Enhanced Biological Phosphorus Removal
Authors: Röske Isolde , Schönborn Christiane , Bauer Hans‐Dietrich 
Published: February 2007

AbstractActivated sludge systems can be operated to select bacteria which accumulate phosphorus as polyphosphate. By these means, phosphate can be removed without the addition of chemical precipitants. This contribution presents results of experiments with a bench‐scale purification plant for domestic sewage. The goal was to find the concentrations of relevant metal cations at which the biological P removal may be affected by competing chemical (precipitation) or physical (adsorption) processes. For this goal, increasing amounts of iron and calcium, respectively, were added into the pilot plant.During the addition of iron, the proportion of chemically (iron‐) bound phosphorus increased from 10 to more than 50%. The P‐release rate substantially decreased with increasing amount of added iron. An addition of small amounts of iron enhanced the long‐term stability of the P elimination as a whole.During the experimental period with addition of calcium, the proportion of Ca‐bound phosphorus increased from 1 to 2% to almost 15%. In batch experiments a measurable Ca‐phosphate precipitation took place at a pH value of at least 8.0 and a Ca‐concentration of at least 100 mg/l. The increase in hardness of the influent waste water didn't produce any positive effect on the stability of the enhanced biological phosphorus removal.The metal ions Ca2+, Mg2+ and K+ serve as counter‐ions in the polyhosphate chains. They were identified and quantified by X‐ray spectrometry in combination with scanning transmission electron microscopy. A release of Mg2+ and K+ occured simultaneously with the degration of polyphosphates (PP). The PP bound to Ca was not redox sensitive.
Limnological Features of Different Acidic Drinking Water Reservoirs in the Erzgebirge (Germany)
Authors: Horn W. , Horn H. 
Published: February 2007

AbstractThe biological and chemical investigations of three drinking water reservoirs differing in their acidic and trophic conditions (neutral/meso‐eutrophic; circumneutral/oligotrophic; acid/oligomesotrophic) and of some of their tributaries in the Erzgebirge (Germany) are presented. It is shown that the chemistry of acidic waters is very different from circumneutral ones, particularly with respect to hardness, acid neutralizing capacity, pH and aluminium. As acidity in running and stagnant waters increases, the filtrable aluminium concentration also rises. A consequence of the changed chemical and biological conditions and their direct and indirect effects on the organisms is an overall decrease in the number of species (despite the fact that also some species newly appear in the acidified waters). Furthermore, a loss of food web complexity is observed and the trophic structure changes, e.g. fish have disappeared and invertebrate predators have become more numerous. In the acidic reservoir, species well adapted to waters low in pH and hardness (e.g. Synura sphagnicola) are more abundant and commonly benthic animals (e.g. Chydorus sphaericus) are able to extend their habitat to the open waters.
Geogenically Acidified Mining Lakes — Living Conditions and Possibilities of Restoration
Authors: Klapper Helmut , Schultze Martin 
Published: February 2007

AbstractPyrite and marcasite oxidation in the consequence of lignite surface mining creates lakes with pH as low as 2 to 3, buffered by high contents of iron and aluminium. Living conditions in this extreme habitat for plants and animals are described as well as the characteristics of the pioneer settlement. The utilization of these fish‐free lakes is very limited. As possibilities for a water quality improvement special recultivation methods of overburden, chemical neutralization and biological ecotechnologies are recommended.
Analysis of Dissolved Humic Substances in Eutrophic Waters Using the Fluorescence of Natural Samples: Calculations and Experiments
Authors: Mittenzwey K.‐H. , Reuter R. , Gitelson A. 
Published: February 2007

AbstractTheoretical analyses and experiments have been performed for rapid detection of dissolved humic substances in surface waters. The fluorescence has been generated by a nitrogen laser in a laboratory. An optical model has been developed, which has been applied to eutrophic waters around Berlin. The model is based on the assumption, that humic substances and phytoplankton dominate the fluorescence behaviour of the investigated waters. To verify the results of the model, regression analyses between fluorescence data of natural samples and the chemical oxygen demand of filtrates have been conducted. When green and red fluorescence values and the green fluorescence decay time were considered, a maximum squared correlation coefficient of typically 0.85 occurred.
Fluorometric Characterization of Two Picocyanobacteria Strains from Lakes of Different Underwater Light Quality
Authors: Callieri Cristiana , Amicucci Enrica , Bertoni Roberto , Vörös Lajos 
Published: February 2007

AbstractUnicellular autofluorescent picoplankton ranging from 0.6 to 0.9 ym in diameter were isolated from Lake Maggiore and from Lake Balaton. The cyanobacterial isolates contain two accessory pigments: phycoerythrin (PE) and phycocyanin (PC) respectively. The in vivo spectral properties of the two clones were compared to identify characteristics of the pigments. In vivo fluorescence excitation and emission spectra revealed that clones with PE are composed only of phycoerythrobilin chromophores and lack phycourobilin. Glycerol treatment enhances the fluorescence yield up to 3 times and improves the detection sensitivity of PE particularly at 436 and 520 nm and of PC at 600 nm. The vertical profiles of the underwater irradiance at different wavelengths were measured in both lakes to study the light quality of the natural environment of the two strains. Growth rates of both clones growing at different light intensities and wavelengths, selected by the same filters used for vertical profiles, were estimated. The results showed a difference in growth rate of phycoerythrin and phycocyanin containing cells exposed to an equal quantum flux of preferential illumination. In particular the maximum growth rate was reached by PE cells exposed to green light and by PC cells exposed to red light.
The Genus Mesocyclops (Crustacea: Copepoda) in Uzbekistan (Central Asia)
Authors: Mirabdullayev Iskandar M. 
Published: February 2007

AbstractFive species of the genus Mesocyclops from various waterbodies of Uzbekistan are described. Some data on the variability and distribution of these species are given. The synonym of M. aequatorialis similis van de Velde and M. thermocyclopoides acutus Dussart et Fernando is proposed. A key to females of Mesocyclops species occuring in Uzbekistan is presented.
On the Theory of Photosynthesis and Growth in Phytoplankton. Part I: Light Limitation and Constant Temperature
Authors: Baumert Helmut 
Published: February 2007

AbstractAssuming constant temperature and light limitation. for reversible photoinhibition and photoadaptation in phytoplankton two new modelling approaches are presented. The first follows an idea of Jones and Kok (1966) and describes photoinhibition as a consequence of the serial structure of the Z‐scheme. The second interpretes photoadaptation as a dynamic equilibrium of the intracellular synthesis and dilution of Chlorophyll by other carbon compounds during cell growth. Together both ideas form a closed system of equations for the dynamical description of photosynthesis, photoadaptation, reversible photoinhibition and growth in phytoplankton.To determine the seven bulk parameters of the model from measured data for a given species and temperature, three quasi‐steady, fully adapted light curves are needed: the P‐1, γ‐1 and μ‐1 curves (P: specific photosynthetic rate [gC (gChl)−1s−1], γ: Chl‐carbon ratio, μ: carbon‐specific growth rate [s−1], l: light intensity). Given these curves, at compensation light intensity their initial slopes α, β, δ and the (maximum) value of γ have to be estimated; at saturation level the (minimum) value of γ is needed. The last bulk parameters of the model are the compensation light intensity and the optimum‐growth light intensity.The model performs well compared with laboratory measurements of quasi‐steady, fully adapted populations. Its dynamic transient behavior exhibits features which are known from semi‐quantitative studies in the field and in the laboratory. In particular, the striking asymmetry observed in shift‐up and shift‐down adaptation experiments is explained by the equations. In an appendix a detailed comparison between target and queuing theory is given and it is shown that the former appears to be more adequate for describing the primary reactions of photosynthesis.