bluuebunny/crossref_metadata_2025 huggingface dataset:
Limnology of a Warm Hypertrophic Wastewater Reservoir in Israel I. The Physical Environment
Authors: Juanico Marcelo
Published: February 2007

This paper deals with stratification in a small reservoir (50 000 m3volume, 5.5 m depth) receiving wastewater with a BOD of 80 mg/1 during the winter in order to irrigate agricultural areas during the dry summer. The reservoir goes through three partially overlapping annual cycles: solar radiation, water temperature and reservoir operation. It presents both permanent (deep) and ephemeral (shallow) stratification during the summer in spite of the strong breeze, due to both thermal and biogenic chemical gradients. There are stratified and non‐stratified wastewater reservoirs in Israel. Stratification in hypertrophic impoundments seems to depend also on parameters derived from the chemical composition of hypertrophic waters. (e. g., turbidity, biogenic gradients, wind/water friction coefficient, viscosity).
Colonization, Succession and Environmental Conditions of the Macrozoobenthos in a Regulated, Polyhumic Reservoir, Western Finland
Authors: Koskenniemi Esa
Published: February 2007

The colonization and succession of the macrozoobenthos in a polyhumic, winter‐regulated reservoir, Lake Kyrkösjärvi in Western Finland (62° 45′N, 22°48′E, A = 6.4 km2at summer HW, zmean= 2.5 m and zmax= 7 m) was studied from its filling in 1981 until 1989 (in 1981–83, 1986 and 1989). The zoobenthos was sampled over the whole reservoir bottom using qualitative and quantitative methods during three open‐water seasons and winter samples were taken in the regulated and submerged areas during the maximum draw down (2 m) in March‐April.

Colonization during the first summer revealed two phases. The first phase featured dominance of actively swimming and adult‐dispersing taxa. The second phase was characterized by a mass occurence (high abundance and biomass) of chironomids (Chironomus, Glyptotendipes) and the isopodAsellus aquaticus. Asellusoriginated in a small bog pond in the northern outlet basin, and it was the dominant zoobenthic species during the study period. The species ofChironomus, most of them pool inhabitants of natural waters, succeeded each other.

In the later study years, when the zoobenthos at the sites was determined more by habitat (spatially) than by the succession (temporally), the reservoir bottom could be divided into three areas: a) deep areas, ≧3 m, with an increasing occurrence of lacustrine species (eutrophic or dystrophic), b) shallower organic bottoms, ≦ 2 m, with many pool‐inhabiting and eurytopic species, and c) some eroded areas in the shallow littoral, ≦ 0.5 m, where lacustrine species became common.

Water‐level regulation in winter killed only a small proportion of the fauna in the organic‐rich peatland and forest bottom areas representing the majority of the regulated zone. Hence, the regulated areas had almost everywhere high abundance and biomass values throughout the year, deviating from the results found by other authors in strongly regulated lakes, which have maximum values just below the draw down limit.
The Influence of Pack Size and Position, Leaf Type, and Shredder Access on the Processing Rate of Atherosperma moschatum Leaves in an Australian Cool Temperate Rainforest Stream
Authors: Campbell Ian C. , Enierga Gina M. , Fuchshuber Lilian
Published: February 2007

Factors affecting the processing rate of packs of southern sassafras (Atherosperma moschatum) leaves were investigated in an Australian cool temperate rainforest stream pool. Processing rate was strongly influenced by pack weight fitting a linear inverse relationship. Processing was not significantly (p>0.05) affected by whether the packs were placed on bricks or free on the stream bed. Free packs, but not packs on bricks, were processed more rapidly near the bank than in midstream (p = 0.050). Packs placed in 300 μm mesh bags, with one side unsealed were processed at the same rate as packs attached to bricks or free on the stream bed, but packs in sealed 300 μm mesh bags were processed significantly more slowly (p<10−4). Abscissed leaves were processed significantly more slowly than fresh leaves (p<10−5) and at a rate not significantly different to leaves sealed in mesh bags (p = 0.197). There was no consistent pattern of difference between processing rates in summer and winter. The results indicate that the size of litter packs may be a more important factor in influencing processing rate estimates than the method of attachment of the packs. The slow rate of processing of abscissed leaves compared with fresh leaves indicates that they were at most, slightly influenced by stream shredders. The absence of a consistent pattern of difference between summer and winter processing rates is consistent with the results of previous litter processing studies from southeastern Australia although no clear causal factor can be identified.
Comparison of Community Structure of Soft‐Bottom Macrobenthos of the Newport Submarine Canyon, California and the Adjoining Shelf
Authors: Maurer Don , Robertson George , Gerlinger Thomas
Published: February 2007

Community structure of soft‐bottom macrobenthos from Newport Submarine Canyon, California, was compared to that on the adjoining shelf. Four hypotheses involving sediment characteristics, community structure, benthic feeding types and seasonal population fluctuations were posed. Results indicated that there were statistically significant differences between the canyon and adjoining shelf. Although there were differences in sediment geochemistry between the canyon and shelf, sediment type played the major role influencing differences in community structure and feeding. Operation of a shelf outfall has not demonstrably changed the canyon soft‐bottom macrobenthos for at least 16 years and probably closer to 27 years.
A Review on Effect‐Dose‐Sensitivity Models for Aquatic Ecosystems.
Authors: Håkanson Lars
Published: February 2007

Effect‐dose‐sensitivity (EDS) models for entire ecosystems, like lakes and defined coastal areas, ought to play a paramount role for environmental sciences and management. The aim of EDS‐models is to provide quantitative predictions relating operationally defined ecological effect parameters to compatible dose and sensitivity parameters. Empirically validated EDS‐models provide a tool to simulate ecosystem effects of practically feasible remedial measures. The main objective of this paper is to give a compilation of existing EDS‐models for aquatic ecosystems. The aim is not to repeat derivations and equations but to present some basic components of EDS‐models, their presuppositions and applicability. Since, at present, there exist EDS‐models for mercury, radiocesium and phosphorus in lakes and nutrients (N and P) in coastal areas, this compilation can be rather short. To the best of the authors knowledge, there exist no EDS‐models (that meet the criteria given in this work) for other types of ecosystems (like forests, agricultural land, urban areas, etc.) or for other types of contaminants (like metals, acidifying substances, halogenated toxins, etc.). Another aim is to clarify the difference between traditional mass‐balance models (i.e., dynamic models) and ecometric (i.e., statistical/empirical models) EDS‐models, and to give examples of EDS‐models based on both these modelling approaches, and techniques (dimensionless moderators) to link these two ways of modelling. The paper also gives examples of the practical use of EDS‐models. A new ecometric EDS‐model for nutrients in coastal areas, where the oxygen concentration of the bottom water is used as an effect parameter, is presented. The idea with this part is also to give the steps in the ecometric derivation of EDS‐models.
Mathematical Model of the Heat and Mass Transfer Processes in a Stratified Reservoir
Authors: Puklakov V.
Published: February 2007

The box‐model of the heat and mass transfer processes in the reservoir and the analysis of the model verification results on the basis of Mozhaliskoye Reservoir field observations data during 3 years are presented.
The Stratification of Pools in the Alluvium of the River Lužnice
Authors: Pithart David , Pechar Libor
Published: February 2007

The stratification of two shallow and small pools, situated in a floodplain ecosystem, was investigated.

A new methodological approach was applied. The parameter called summarized chemical and biological stratification (SCB), was derived from basic limnological parameters in order to evaluate the global intensity of chemical and biological stratification and to compare it with a thermal one.

Three situations were described when the seasonal courses of thermal and SCB stratification were compared: 1. Both SCB and thermal stratification are present. 2. The water column is homogeneous — there is no stratification in the pool. 3. SCB stratification is present, but the water is homoiothermic. The thermal stratification is very unstable because of the small volume of the pools and frequent floods. The SCB stratification is of higher stability and it may persist in a homoiothermic water column. In comparison with temperate deep lakes, the thermal stratification does not play such an important role in initiating the chemical and biological stratification. The surface/volume ratio and the depth in the pools are lower, which cause the “bottom‐initiated” quick renovation of stratification even in homoiothermic water.

The differences in oxygen regime, volume and localization of both investigated pools cause the differences in stratification patterns. Frequent oxygen depletions in one of the pools increase the intensity of stratification and influence its character. The anaerobic conditions lead to steeper gradients of basic nutrients, pH, alkalinity and water color.

The occurrence of a unique phytoplankton community (Cryptophyceae) is probably closely related to the described stratification patterns.
On Paradicranophorus aculeatus ((NEISTWESTNOVA‐SHADINA, 1935) with Remarks on All Other Species of the Genus (Rotifera: Dicranophoridae)
Authors: Koste Walter , Yan Zhuge
Published: February 2007

In 1934, the rotifer Paradicranophorus aculeatus was discovered by Neistwestnova‐Shadina in the River Oka near Murom (Russia). She described it as a Dicranophorus species. In 1958, the rheophilic rotifer was rediscovered in the Polish River Grabia by Pawlowski. This paper reports a third occurence in three samples from the Yun Nan Luoxiao River in China, allowing additional studies of this rare species.
Demographic Modelling in the Analysis of Population Dynamics of Deep‐Sea Macrobenthos
Authors: Gage John D.
Published: February 2007

A flexible graphics simulation approach, combining graphics simulation with nonlinear parameter optimisation, is described for estimating likely growth and survivorship from size frequencies measured in samples of deep‐sea benthic invertebrates. Relationships between patterns in size structure, such as bimodal size distributions, are shown to result from limited combinations in values of growth and mortality parameters. Although it is possible to fit demographic models to such size data by optimising goodness‐of‐fit of model frequencies to those observed, the outcome may be dependent on assumptions of a stable age structure from year to year. Simulation studies show that populations with relatively low values of the von Bertalanffy growth‐rate constant K and of survivorship, which show year‐to‐year variability in level of recruitment, will display strongly varying adult size structure at an inter‐annual timescale. Those with high K and high adult surivorship. and which typically show a bimodal distribution of size frequencies, will be much more resilient to such changes. However, high adult survivorship in a relatively long‐lived species will result in relatively stable adult age structure even when K, and the probability for any recruitment at all, is low. The implications of these findings are discussed in terms of contrasting models developed for populations of the deep‐sea ophiuroids Ophiura ljungmani and Ophiomusium lymani, and of the deep‐sea echiniod Echinus affinis. in samples from permanent stations in the Rockall Trough, northeastern Atlantic.
Hatchling Size and Aspects of Biology in the Deep‐Sea Amphipod Genus Eurythenes (Crustacea: Amphipoda)
Authors: Thurston Michael H. , Bett Brian J.
Published: February 2007

Records attributed to Eurythenes gryllus are discussed in the light of described morphological variation, and the existence of a third species in the genus is postulated. The presence of five pairs of oostegites in E. gryllus, a character almost unique among the Amphipoda, is confirmed. Brooding females of E. gryllus and E. obesus, captured in deep midwater hauls in the eastern North Atlantic Ocean, are reported for the first time. The 120 mm E. gryllus female carried 237 hatchlings (mean length 11.13 mm) and the 48 mm E. obesus female 47 hatchlings (mean length 7.99 mm). Hatchlings showed variability in size and bodily proportion, and measurements of individual body segments could not be used to predict overall length. Despite this variability, no evidence for more than one instar was found. The hatchlings of E. gryllus are established as a hitherto unrecognized instar in this species. Egg size for E. gryllus and E. obesus is predicted. The biological consequences of the absolute and relative size of hatchling in the two species, and the depths of capture of the E. gryllus female, are discussed.
Deep‐Sea Macrobenthic Communities at Contrasting Sites off Portugal, Preliminary Results: II Spatial Dispersion
Authors: Lamont Peter A. , Gage John D. , Tyler Paul A.
Published: February 2007

Small‐scale, biogenic processes are thought to be important in creating a mosaic of microhabitats that allow co‐existence of the large numbers of rare species found in deep‐sea sediments. However, the large‐scale effects of hydrodynamic disturbance seem likely to be important in high‐energy settings on the deep‐sea bed. This is investigated by examining spatial dispersion patterns in the macrobenthic populations at two deep‐sea sites off Portugal. The widely differing conditions of sediment disturbance at the two sites are related to differences in macrobenthic species diversity and dominance.

Closely grouped, transponder‐mapped, replicate box core samples, each divided into 25 “vegematic” subcores permitted analysis of dispersion patterns at two spatial scales at each site. One site was located on the Tagus Abyssal Plain (TAP), and the other in the nearby Setubal Canyon (SC) where ripple bedforms indicate vigorous bed flow, probably with a tidal periodicity. Greater aggregation at the scale of tens of metres is indicated from the observed numbers of SC species per box core being wide underestimates of the value predicted by rarefaction of the pooled total compared to those from TAP. Variance/mean ratios for individual species of bivalves and tanaids indicated more aggregation in spatial distribution between box cores from SC than from TAP. Dispersion chi‐square analysis also indicated more non‐randomness at SC between box cores than for the TAP cores. However, low faunal abundances in the TAP samples render the results of analyses for this site somewhat inconclusive and therefore the trend indicating less aggregation at TAP compared to SC must be regarded as weak for the groups examined. Analyses of the distribution of tanaids, and bivalves at a 100 × 100 mm subcore scale showed no convincing significant departure from random expectation, but low abundances in these groups reduces the sensitivity of the tests applied. Between‐core aggregation detected at SC may reflect habitat variation resulting from the varying depth within the area of sampling, while within‐core patchiness could be influenced by the ripple bed forms on the sediment.
Nematode Biomass Spectra at Two Abyssal Sites in the NE Atlantic with a Contrasting Food Supply
Authors: Vanreusel Ann , Vincx Magda , Bett Brian J. , Rice Anthony L.
Published: February 2007

Abundance and biomass sizes spectra of nematodes have been investigated at two contrasting abyssal sites in the NE Atlantic. The northern site is situated on the Porcupine Abyssal Plain where there is evidence for a high, seasonal input of organic matter derived from the overlying water column. The southern site is the oligotrophic station of the French EUMELI programme off Mauritania and is characterized by low primary productivity in the overlying water column and consequently by a lower organic input to the deep‐sea floor. Low nematode density and total biomass in the surficial centimetre of the sediment at the EUMELI site (89 ind/10 cm2, 8.52 μg wwt/10 cm2), in contrast to the PAP site (254 ind/10 cm2, 54.16 μg wwt/10 cm2), supports a presumed lower food supply to this area. Similary, mean individual nematode body weight is significantly smaller at the oligotrophic EUMELI site (0.0241 μg dwt) compared to the PAP site (0.0511 μg dwt), which supports the hypothesis that mean nematode body size is correlated with food availability. However, differences are much less obvious when comparing geometric mean biomasses and median individual body sizes. The abundance size spectra for the two localities diverge appreciably only in the upper quartile. The differences in mean individual body weights are caused by the relatively greater abundance of larger nematodes at the more eutrophic PAP site.
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

The 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

Factor 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

In 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

The 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

In 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

An 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

Ecotechnology 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

The 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

The 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

Activated 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

The 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

Pyrite 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

Theoretical 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

Unicellular 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

Five 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

Assuming 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.
Trace Metals in Mesozooplankton of the North Sea: Concentrations in Different Taxa and Preliminary Results on Bioaccumulation in Copepod Collectives (Calanus finmarchicus/C. helgolandicus)
Authors: Zauke Gerd‐Peter , Krause Michael , Weber Adolf
Published: February 2007

Trace metals (Cd, Cu, Zp, Pb, Ni) were determined in different zooplankton taxa to assess their role in the biogeochemical cycle in the North Sea. Results of semi‐static bioaccumulation experiments on board ship using collectives of Calanus finmarchicus/C. helgolandicus were in agreement with a net accumulation strategy, thus meeting an inevitable precondition for their utilization as biomonitors. Cd, Cu and Zn concentrations in field samples of zooplankton displayed a pronounced variability between taxa, with Cd ranging from 0.13 mg kg‐1 (d.w.) in fish larvae to 5I mg kg‐1 in hyperiid amphipods. Almost no information is available about metal requirements of copepods. However, most of our and worldwide reported Cu concentrations in calanoid copepods (6‐22 mg kg−1) coincided with estimates of enzymatic requirements of decapod crustaceans. Cd levels in Calanus collectives increased significantly from 0.68 mg kg‐1 in the German Bight to 11 mg kg−1 at some stations around Scotland above 59° N, in line with literature data reported for benthic decapod crustaceans.
Differential Response of Benthos to Natural and Anthropogenic Disturbances in 3 Lowland Streams
Authors: Armitage P. D. , Gunn R. J. M.
Published: February 2007

The macroinvertebrate faunal assemblages of 8 sites on three small streams in SE England were examined annually in spring between 1987 and 1993. Considerable ‘natural’ variability was observed in the sites superimposed over a background of low‐intensity anthropogenic disturbance such as farming, quarrying, and urban influences. Landscape changes and activities in the catchment (saline drainage, removal of topsoil, pipeline crossings of streams) associated with the construction of the UK terminal for the Channel Tunnel, resulted in further temporary disturbance at some of the sites.

Most changes in faunal composition were related to natural and anthropogenically induced modifications of the stream substrate. The response and recovery time of sites to disturbances was very variable and was related to the hydraulic and substrate characteristics of the stream bed, with least change and quickest recovery at sites with coarse substrates and high slope. Variations between years in the occurrence of taxa were generally more apparent with species data than with family data except where environmental change was great. Despite the observed differences in faunal composition the main elements of the fauna were fairly constant throughout the study period.

Analyses of the data with biotic indices, the predictive RIVPACS system and ordination analyses have all shown clearly the annual variability of faunal parameters used to measure environmental quality. The study has shown that very basic rapid assessment techniques can provide insights into faunal responses to disturbance, especially if the work is long‐term and that before authoritative statements concerning environmental impact can be made it is essential to have knowledge of the natural variation to be expected in streams of differing characteristics.
The Structure of a Macroinvertebrate Community in a Northern German Lake Outlet (Lake Belau, Schleswig‐Holstein) with Special Emphasis on Abundance, Biomass and Secondary Production
Authors: Popperl Rainer
Published: February 2007

The structure of macroinvertebrate communities was studied at I I sampling sites of the outlet of Lake Belau in the lowlands of northern Germany. To describe the structures of macrobenthic animal communities three different units were examined: abundance, biomass, and secondary production.

112 taxa were collected from the entire stream. The numbers of species ranged from 31 (fine sand) to 70 (submerged macrophytes). For the stream, average macroinvertebrate density was 18.400 ind. M−1. Density was highest at the macrophytes amounting to 35,630 individuals per m2, and lowest in the pure sand with only 3,900 ind. M−2. Average biomass (dry mass) was 194 g DM m−2 varying from 9.8 (peat) to 381 g DM m−2 (gravel with mollusk shells near the upstream lake). For the stream, average annual production was 129 g DM m−2 varying from 15 (peat) to 286 g DM m−2 (macrophytes).

The highest values for each unit were found in stream sections with gravel and submerged macrophytes. Lower values occured in sections that contained peat and sand. Usually, a single structure of the macroinvertebrate community was dominated by less than ten taxa, which varied at each sampling site depending on the units observed.
Herbaceous Wetlands of the Yucatan Peninsula: Communities at Extreme Ends of Environmental Gradients
Authors: Rejmankova Eliška , Pope Kevin O. , Post Rebecca , Maltby Edward
Published: February 2007

Distribution of wetland communities and growth characteristics of dominant macrophyte species were studied in the SE and NW parts of the Yucatan Peninsula. Plant, water and soil samples were collected from 40 marshes ranging from permanently flooded to seasonally drying. Marsh soils were identified as either peats, mark or clays with many intergrades. Water quality ranged from mesosaline (chloride or sulfate dominated) to fresh (carbonate dominated). Nutrient concentrations, specifically phoshorus, were low. The dominant species wereTypha domingensis(TD),Cladium jamaicense(CJ),Eleocharis cellulosa(EC),E. interstincta(EI), and algal mats composed mostly of blue green algae (BG). EC and BG dominate marshes with marly soils and high salinities. C3 grows well on peaty soils and is well adapted to extremely low phosphorus concentrations and occasional drying. TD dominates nutrient rich marshes with deep water and clayey soils. The species differ significantly in their growth, death and decomposition rates. All these rates are highest for TD, followed closely by EC, and slowest for CJ.
Phytoplankton and Nutrients in the River Strymon, Greece
Authors: Tryfon Eleni , Moustaka‐Gouni Maria , Nikolaidis Georgios
Published: February 2007

Phytoplankton species composition, biomass, diversity, nutrients and chlorophyll a were studied at monthly intervals from December 1991 to December 1992 in a selected area of the river Strymon. SRP ranged from 53 to 182 μg−1 l−1 and DIN from 265 to 850 μg−1 I−1. Nutrient values do not indicate strong anthropogenic effects. Chlorophyll α ranged from 1.0 to 35.3 μg−1 I−1 and followed the temporal distribution of total phytoplankton biomass. Phytoplankton biomass exhibited maxima in winter – spring and summer (6.8 g m−3 in December 1991, 4.8 g m−3 in April 1992 and 9.3 g m−3 in August 1992) composed mainly of diatoms, chlorphytes, cyanophytes and dinophytes. Nanoplankton was the most important component of phytoplankton biomass (69.5%) revealing increased values in winter and early spring. Phytoplankton diversity ranged from 0.8 to 3.2. The hydrological conditions in the river Strymon seem to be appropriate for the algae to reproduce themselves in the running water and so, to develop as a true potamoplankton. However, significant populations of phytoplankton must have been carried out from the Kerkini reservoir, situated at the north of the sampling station. The phytoplankton species composition and their periodicity in the river resemble those of typical, large, lowland and nutrient – rich rivers of Europe.