Showing papers by "Helmholtz Centre for Environmental Research - UFZ published in 2002"

Assessing the suitability of central European landscapes for the reintroduction of Eurasian lynx

Abstract: Summary 1 After an absence of almost 100 years, the Eurasian lynx Lynx lynx is slowly recovering in Germany along the German–Czech border. Additionally, many reintroduction schemes have been discussed, albeit controversially, for various locations. We present a habitat suitability model for lynx in Germany as a basis for further management and conservation efforts aimed at recolonization and population development. 2 We developed a statistical habitat model using logistic regression to quantify the factors that describe lynx home ranges in a fragmented landscape. As no data were available for lynx distribution in Germany, we used data from the Swiss Jura Mountains for model development and validated the habitat model with telemetry data from the Czech Republic and Slovenia. We derived several variables describing land use and fragmentation, also introducing variables that described the connectivity of forested and non-forested semi-natural areas on a larger scale than the map resolution. 3 We obtained a model with only one significant variable that described the connectivity of forested and non-forested semi-natural areas on a scale of about 80 km2. This result is biologically meaningful, reflecting the absence of intensive human land use on the scale of an average female lynx home range. Model testing at a cut-off level of P > 0·5 correctly classified more than 80% of the Czech and Slovenian telemetry location data of resident lynx. Application of the model to Germany showed that the most suitable habitats for lynx were large-forested low mountain ranges and the large forests in east Germany. 4 Our approach illustrates how information on habitat fragmentation on a large scale can be linked with local data to the potential benefit of lynx conservation in central Europe. Spatially explicit models like ours can form the basis for further assessing the population viability of species of conservation concern in suitable patches.

Rule-based assessment of suitable habitat and patch connectivity for the eurasian lynx

Abstract: Conservation biologists often must make management decisions based on little empirical information. In Germany, biologists are concerned that the recovery and reintroduction of Eurasian lynx (Lynx lynx) may fail because the remaining suitable habitat may be insufficient to sustain a viable population. However, no comprehensive study ad- dressing this concern has been made that not only considers distribution of suitable habitat, but also connectivity to other populations. The aims of this study were (1) to quantify the amount and location of potentially suitable lynx habitat in Germany, (2) to estimate the connectivity between patches of suitable habitat, and (3) to evaluate lynx conservation programs. Habitat preferences of lynx were described in a rule-based model based on the availability of forest cover (defined by patch size) and the spatial structure of the habitat. Rules were implemented in a geographic information system to predict locations of suitable habitat. Optimal connections among patches were modeled using a cost-path analysis based on habitat-specific probabilities of lynx crossing patches. Results indicated wide variation in the size of patches of suitable habitat, with 10 areas each sufficiently large to sustain .20 resident lynxes. Overall, a total of 380 lynxes could be sustained by the 10 areas. Uncertainty analyses of model parameters and assumptions revealed little variation in pre- dicted habitat, primarily because results were constrained by the actual distribution of forest habitat. Our analyses suggest that lynx reintroduction programs should emphasize large, connected areas and consider broad-scale habitat connectivity in the landscape. Our ap- proach also demonstrates how biologically plausible rules can be applied in conservation to identify areas in which success is most likely, even when few empirical data are available.

Spatial organization, group living and ecological correlates in low‐density populations of Eurasian badgers, Meles meles

Abstract: Summary 1 Territoriality and group living are described in a low-density population of Eurasian badgers, Meles meles L., by studying the patterns of spatial grouping and territory marking, as well as the differences between individuals in some of their characteristics (body condition and dispersal) and in their space use (seasonally, periods of activity and interaction between pairs of individuals) under strong seasonal fluctuations in the availability of the key resource (young rabbits, Oryctolagus cuniculus L.). Finally, the role of the spatial distribution of the main prey (young rabbits) in the development of sociality was also studied in order to test some of the assumptions and predictions of the resource dispersion hypothesis (RDH). 2 Badgers were territorial, showing a flexible system of territory marking, which includes the marking of the most used areas (sett-latrines at the centres of activity) and additionally, at the smaller territories, a system of border-latrines in the areas of contact between territories. The maximum use of border-latrines was associated with the reproductive season, and that of sett-latrines with the season of food scarcity. 3 In the study area where badgers had rabbits as main prey, territories were occupied by small groups of animals, formed by one adult female who reproduced, one adult male who also showed signs of reproductive activity, the cubs of the year (if there was reproduction) and some animals born during previous years, which remained in their natal territory until their dispersal (normally during the mating season of their third or fourth year of life). This system was not strictly fixed as males, given the opportunity, expanded their territories to encompass additional females. Territories in another study site were occupied by one adult female (marked), plus the cubs of the year and another adult individual (unmarked). 4 In winter and spring dominant females and subordinates used only a small fraction of their territories, moved short distances, at a low speed and covering small areas per night. These seasons corresponded with the reproduction of rabbits (highest food availability). Dominant females were the only individuals using all the territory available in the summer (lowest food availability), when badgers had the worst body condition. Food availability increased again in autumn, as did body condition, while range sizes were again reduced. Dominant males used the same proportion of their territories over all seasons. However, in winter (reproductive season) they moved faster, over longer distances, and covered larger areas per period of activity. These results indicate that use of space by dominant males was affected by different factors from that of dominant females and subordinates. 5 RDH does not seem to explain group living in our populations because: (a) territoriality in each pair of primary animals was driven by different factors (trophic resources for females and females for males); (b) dominant males acted as expansionists; and (c) territory size was related to its richness and not to patch dispersion. 6 We propose an integrative hypothesis to explain not only group formation but also interpopulation variability in the social organization of badgers within ecological, demographic and behavioural constraints and in the light of current theory on delayed dispersal.

Biological and chemical determination of dioxin-like compounds in sediments by means of a sediment triad approach in the catchment area of the river Neckar.

Abstract: To evaluate the sediment quality of selected sites in the catchment area of the River Neckar, an integrative assessment approach was used to assess the ecological hazard potential of dioxin-like sediment compounds. The approach is based on 7-ethoxyresorufin-O -deethylase (EROD) induction in embryonic chicken liver culture and comprehensive chemical analyses of polycyclic aromatic hydrocarbons (priority PAHs according to the US Environmental Protection Agency). The majority of the sediment extracts exhibited high potencies as EROD-inducers. In one sediment sample, which was influenced by a sewage treatment plant, a very high concentration of 930 ng bioassay 2,3,7,8-tetrachlorodibenzo-p -dioxin (TCDD) equivalents (bio-TEQs )/g organic carbon could be determined. However, in none of the samples, more than 6% of the EROD-inducing potency could be explained by the PAHs analyzed chemically. Thus, non-analyzed compounds with EROD-inducing potency were present in the extracts. A fractionation of sediment samples according to pH allowed to localize the major part of EROD-inducing compounds in the neutral fractions. However, a significant portion of the EROD induction could also be explained by the acidic fractions. Following the concept of the Sediment Quality Triad according to Chapman, in situ alterations of macrozoobenthos were examined. A comparison of the results predicted by the EROD assay and chemical analyses with alterations in situ , as measured by means of the saprobic index and the ecotoxicological index according to Carmargo, revealed a high ecological relevance of the results of bioassays and chemical analyses for major sites.

A Formula for the Mean Lifetime of Metapopulations in Heterogeneous Landscapes

Abstract: We present a formula for the mean lifetime of metapopulations in heterogeneous landscapes. This formula provides new insights into the effect of the spatial structure of habitat networks on metapopulation survival, with consequences for modeling, landscape evaluation, and metapopulation management. In the whole study, the spatially realistic metapopulation model of Frank and Wissel is taken as a basis. First, as a key result on the way toward the desired formula, it is shown that a simple nonspatial (Levins-type) model is able to reproduce the behavior of the complex spatial model considered regarding the mean lifetime, provided its parameters appropriately summarize all the relevant details of spatial heterogeneity. Second, the formula presented reveals how data from species and landscape have to be combined to estimate the survival chance of a metapopulation without having to run any simulation or to solve numerically any model equation. Third, by taking the formula as a basis, landscape measures are derived that allow dissimilar habitat networks to be evaluated, compared, and ranked in terms of their effect on metapopulation survival. Fourth, a combination of analytical, nonlinear regression as well as aggregation techniques was used to deduce the formula presented. The potential of these techniques for simplifying (meta)population models that are complex due to spatial heterogeneity is discussed.

Effect-directed fractionation and identification of cytochrome p4501A-inducing halogenated aromatic hydrocarbons in a contaminated sediment.

Abstract: On the basis of a new fractionation method combined with in vitro ethoxyresorufin-O-deethylase (EROD) induction in a rainbow trout liver cell line (RTL-W1) and chemical analysis, halogenated aromatic hydrocarbons with dioxin-like activity were identified in a sediment extract from Bitterfeld, Germany. The fractionation method allowed a separation of different nonplanar and coplanar polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) with different degrees of chlorination. The dioxin-like activity at the investigated site could be quantitatively assigned to PCDD/Fs. Both PCBs and PCNs could be excluded as the cause of the measured effects on the basis of the fractionation procedure and bioanalytical results. Thus, the method allowed the chemical analysis to focus on PCDD/Fs, with significant reduction of the analytical expense. The EROD-induction potency of sediment-extract fractions was quantified, and toxicants were confirmed by the application of induction equivalent quantities on the basis of fixed-effect-level concentrations that exhibit 15% of the maximum induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin. This approach was designed to minimize methodological limitations due to superimposing inhibitory effects.

A spatial model of coexistence among three Banksia species along a topographic gradient in fire-prone shrublands

Abstract: 1. A spatially explicit, rule-based model for three co-occurring Banksia species was developed to investigate coexistence mediating processes in a fire-prone shrubland in western Australia. Fecundity, recruitment, mortality and other biological data for two non-sprouting (B. hookeriana, B. prionotes) and one resprouting (B. attenuata) species were available from 15 years of empirical field studies. 2. Without interspecific competition, each species could persist for a wide range of fire intervals (10 to > 20 years). The resprouting species performed better under shorter fire intervals (10-13 years), while both non-sprouting species were favoured by longer (15 to > 20 years) fire intervals. These results conform with those obtained from single-species, non-spatial population models. 3. When interspecific competition for space was included in the model, all three species exhibited optima at shorter fire intervals and with a narrower range than in isolation. The three species did not co-occur under any fire regime. At intermediate fire frequencies (11-13 years), B. hookeriana excluded the other species, while for longer intervals between fires B. prionotes became dominant. 4. The introduction of temporal (stochastic) variability in fire intervals (drawn from a normal distribution) failed to produce coexistence, unless spatial variability as a spatial ignition gradient was also included. The spatial arrangement of the non-sprouters observed in the field was then reproduced. 5. Observed patterns of coexistence and spatial distributions of all species occurred when a spatial establishment gradient for the resprouter species was included in the model (individuals of B. attenuata are known to produce more seeds in swales than on dune crests and recruit seedlings here more frequently). 6. Coexistence appears to be highly dependent upon the mean interfire period in combination with subtle gradients associated with fire propagation and recruitment conditions. Variation around the mean fire interval is less critical. When the system is modelled over a long time period (1500 years) coexistence is most strongly favoured for a narrow window of mean fire intervals (12-14 years).

Individual variability and population regulation: a model of the significance of within-generation density dependence.

Abstract: Most models of theoretical population ecology consider population density as a state variable and thus ignore the fact that populations are composed not of identical average individuals but of individuals which are usually different. However, this individual variability may be important for population regulation. We therefore analysed an individual-based population model which explicitly describes within-generation processes, i.e. individual growth, starvation, and resource dynamics. The results show that if population dynamics are dominated by slow changes in resource level, the population size in the model undergoes wide oscillation, often leading to extinction. If, on the other hand, fast within-generation processes predominate, such as starvation and sudden drops in resource levels, the population fluctuates to a limited extent around an average. Within-generation density dependence may thus be an important mechanism which is largely ignored in classic time-discrete state-variable models. We conclude that the individual-based approach provides important insights into the hierarchical organization of population dynamics, i.e. the relationship between fast processes at the individual level and slower processes at the population level.

Cyclic dynamics in simulated plant populations

Abstract: Despite the general interest in nonlinear dynamics in animal populations, plant populations are supposed to show a stable equilibrium that is attributed to fundamental differences compared with animals. Some studies find more complex dynamics, but empirical studies usually are too short and most modelling studies ignore important spatial aspects of local competition and establishment. Therefore, we used a spatially explicit individual-based model of a hypothetical, non-clonal perennial to explore which mechanisms might generate complex dynamics, i.e. cycles. The model is based on the field-of-neighbourhood approach that describes local competition and establishment in a phenomenological manner. We found cyclic population dynamics for a wide spectrum of model variants, provided that mortality is determined by local competition and recruitment is virtually completely suppressed within the zone of influence of established plants. This destabilizing effect of local processes within plant populations might have wide-ranging implications for the understanding of plant community dynamics and coexistence.

Novel integrative passive samplers for the long-term monitoring of semivolatile organic air pollutants

Abstract: Two types of passive sampler were developed for the long-term monitoring of semivolatile organic compounds (SOCs) in air. They consist of poly(dimethylsiloxane) (PDMS)-coated stir bars (type A) or silicone tubing (type B), acting as a solid receiving medium, enclosed in a heat-sealed low-density polyethylene (LDPE) membrane. These samplers combine the advantages of integrative passive sampling with those of analysing accumulated analytes by thermodesorption-GC-MS, whilst avoiding the use of solvents and expensive sample preparation and cleanup steps. The performance of these samplers was investigated for the integrative sampling of SOCs, including α- and γ-hexachlorocyclohexanes, hexachlorobenzene, 2,4,4′-trichlorobiphenyl, 2,2′,5,5′-tetrachlorobiphenyl and fluoranthene, in laboratory exposure experiments under controlled conditions. For both types of sampler, the uptake of all the analytes investigated was linear over an exposure period of 15 days. The sampling rates calculated ranged from 70 to 320 ml h−1 (sampler A) and 630 to 4300 ml h−1 (sampler B). The passive samplers are able to detect low time-weighted average air concentrations in the pg m−3 range. The small, robust and inexpensive sampling devices were tested successfully for the long-term air monitoring of semivolatile organic pollutants in a polluted area over an exposure period of up to 28 days.

Two Pilot Plant Reactors Designed for the In Situ Bioremediation of Chlorobenzene-contaminated Ground Water: Hydrogeological and Chemical Characteristics and Bacterial Consortia

Abstract: The SAFIRA in situ pilot plant in Bitterfeld, Saxonia-Anhalt, Germany, currently serves as the test site for eight different in situ approaches to remediate anoxic chlorobenzene (CB)-contaminated ground water Two reactors, both filled with originallignite-containing aquifer material, are designed for themicrobiological in situ remediation of the ground water bythe indigenous microbial consortia In this study, thehydrogeological, chemical and microbiological conditions of theinflowing ground water and reactor filling material are presented,in order to establish the scientific basis for the start of thebioremediation process itself The reactors were put intooperation in June 1999 In the following, inflow CB concentrationsin the ground water varied between 22 and 33 mg L-1; achemical steady state for CB in both reactors was reachedafter 210 till 260 days operation time The sediments werecolonized by high numbers of aerobic, iron-reducing anddenitrifying bacteria, as determined after 244 and 285 days ofoperation time Furthermore, aerobic CB-degrading bacteria weredetected in all reactor zones Comparative sequence analysis of16S rDNA gene clone libraries suggest the dominance of Proteobacteria (Comamonadaceae, Alcaligenaceae, Gallionella group, Acidithiobacillus) and members of theclass of low G+C gram-positive bacteria in the reactorsediments In the inflowing ground water, sequences withphylogenetic affiliation to sulfate-reducing bacteria andsequences not affiliated with the known phyla of Bacteria, were found

Yeasts as Producers of Polyhydroxyalkanoates: Genetic Engineering of Saccharomyces cerevisiae

Abstract: The genes of the poly(β-hydroxybutyrate) (PHB) synthesis pathway in Ralstonia eutropha and Methylobacterium extorquens were successfully established in the yeast Saccharomyces cerevisiae. Expression of just the polyhydroxyalkanoate (PHA) synthase gene in some experiments, and all three PHB genes (i.e., the genes encoding β-ketothiolase, acetoacetyl-CoA reductase, and PHA synthase) in others, were detected in S. cerevisiae. Thus, it can be used as a cell factory for the production of PHB. The maximum amount of polyester accumulated was 6.7% (wt./ wt.) when all three genes were expressed. The amount of polymer accumulated in the transgenic yeast harboring just the PHA synthase gene was similar (5.2%), but slightly lower, indicating the necessity of expressing all three genes foprhich PHB contents in, the cells. For viable production f the polymer in yeasts, more needs to be learned about the netabolism of the yeast, especially about the pathways and intermediates competing with formation of the biopolymer. Another host probably needs to be chosen.

Hydrogeological basis for biotechnological remediation of the acidic mining lake 'rl 111', lusatia (germany)

Abstract: The drainage basin of the acidic mining lake ‘RL 111’ was characterized by hydrogeological and geochemical models to assess its influence on a planned biotechnological remediation of the lake water and lake sediment. Ground, seepage and lake water, as well as the surrounding sediments, were examined to model the hydrodynamic processes and the geochemical developmentof the lake. The geochemical conditions seem to behave in a stable manner (steady state conditions). A reduction of the high sulphate andacid input has not been observed since the beginning of our investigations. The biotechnological remediation of the whole lake should consider a treatment of the dump sediments to improvethe quality of the inflowing groundwater, as well as to reduce erosion.

Evaluation of measurement uncertainty for analytical procedures using a linear calibration function

Abstract: In the EURACHEM/CITAC draft “Quantifying uncertainty in analytical measurement” estimations of measurement uncertainty in analytical results for linear calibration are given. In this work these estimations are compared, i.e. the uncertainty deduced from repeated observations of the sample vs. the uncertainty deduced from the standard residual deviation of the regression. As a result of this study it is shown that an uncertainty estimation based on repeated observations can give more realistic values if the condition of variance homogeneity is not correctly fulfilled in the calibration range. The complete calculation of measurement uncertainty including assessment of trueness is represented by an example concerning the determination of zinc in sediment samples using ICP-atomic emission spectrometry.

Conditioning of Heavy Metal-Polluted River Sediment by Cannabis sativa L.

Abstract: We are currently developing a process for the remediation of heavy metal-polluted sediment by solid-bed bioleaching. Unfortunately, freshly dredged sediment is impermeable to water, unsuitable for solid-bed leaching, and therefore needs preliminary conditioning to improve its structure. A pilot-scale conditioning plant consisting of several basins (each with a base of 6 m2 and a depth of 0.7 m) was filled with freshly dredged, slightly predewatered sediment from the Weisse Elster River. Hemp (Cannabis sativa L.) was chosen for conditioning because it develops quickly from seeds, produces large amounts of biomass, and forms commercially useful fibers. Irrespective of the plant cover, the sediment dried out, was oxidized and turned acidic. However, its structure and permeability only improved when the sediment was covered with plants and not when all the vegetation appearing was removed regularly. Although hemp germinated completely regularly on sediment, 1 week after seeding the leaves became part...

Evaluation of the Sulfate Dynamics in Groundwater by Means of Environmental Isotopes

Abstract: Elevated sulfate concentrations and their heterogeneous distribution in the drinking water catchment area Torgau-Mockritz (Germany) were investigated by means of multiple isotope signatures such as δ34S, δ18O-H2O, δD, tritium, and 85Kr. δ34S values of the groundwater sulfate vary between -19…+ 37‰ CDT. No simple correlation exists between sulfate concentrations and δ34S. Superimposition of different sulfur sources and mobilization processes combined with a complicated groundwater movement create a complex distribution pattern. The oxidation of reduced sedimentary sulfur has to be regarded as a main source of dissolved sulfate at least regionally. Tritium and 14C data revealed that old groundwater can be excluded as source for high sulfate contents. Correlated temporal variations in the concentrations of tritium and sulfate are observed in deeper sampling positions. Highly variable δ18O and δD, as detected in parts of the catchment area, indicate local influences of surface water infiltration into...

Using Environmental Isotopes 2H and 18O for Identification of Infiltration Processes in Floodplain Ecosystems of the River Elbe

Abstract: We examined a floodplain area in the middle section of the river Elbe Valley with regard to hydrogeological and hydrological processes using isotopic methods. Over two years, river water and groundwater have been analysed for temporal and spatial chemical and isotopic (delta2H and delta18O) changes. By these methods we assessed the flow dynamics of the river-groundwater infiltration system. At low and mean river stages there is a general hydraulic gradient from the higher areas at the margin of the valley towards the floodplain. During floods river water infiltrates into the adjacent aquifer not primarily through the river banks but first through surface water inflow from north to south, via depressions and gullies from the back of the floodplain. The early stage of river water infiltration is characterized by a sharp decrease in conductivity and in concentrations of SO4(2-) and Cl- in the hydraulically connected shallow aquifer. delta2H and delta18O values show a similar tendency. We observed a significant minimum in stable isotope ratios during the flood in March 1999. Using a simple mixing equation it was calculated that the groundwater in the upper, shallow aquifer consists of around 70% river water in the transition zone (well 13) during flooding.

MOSAIK: Semi-open pasture and ley — a research project on keeping the cultural landscape open

Abstract: The “Mosaik” project studies the effects of two new management concepts, on the one hand the creation of permanent pastures with low stocking densities (< 0. 5 animals/ha) under an overall ‘semi-open pasture landscape’ approach, and on the other hand a spatial mosaic with cyclic, massive interventions in the Vegetation cover (hoeing/mechanical cultivation) under an overall ‘ley landscape’ approach. Both management approaches will lead to a semi-open landscape with scrub and a mosaic — both spatial and temporal — of habitat qualities for flora and fauna. This may pose a risk of colonization and extinction for some of the endangered species.

Behaviour of organoarsenic compounds in contact with natural zeolites

Abstract: Batch experiments were conducted on aqueous solutions containing arsenite, arsenobetaine, methylarsonic acid or phenylarsonic acid in contact with natural zeolites to examine their interaction. The concentration of the arsenic species in the liquid phase at equilibrium before and after contact was measured by means of liquid chromatography coupled with inductively coupled plasma mass spectrometry detection. Clinoptilolites completely removed arsenobetaine from the solution and the resulting amounts of dimethylarsinic acid were detected. The methylarsonic acid maximum concentration diminution was reached at a mass—to volume V value of m/V = 0.2. Phenylarsonic acid solution decreased its concentration 75% after treatment with clinoptilolites. Untreated mordenites in contact with arsenite solutions led to the formation of arsenate, whereas acid-washed mordenites practically removed arsenobetaine and were less effective for methylarsonic acid. To show the incompatibility of molecular dimensions with the zeolite windows, the molecular parameters of surface area, molecular volume, molecular length, and the width and depth of arsenite, arsenate and a series of ten organic arsenic compounds were calculated. Since sorption onto the external zeolite surface rather than a sieve process defined the interaction, an acid-catalysed reaction mechanism is proposed to explain the transformation results. Copyright © 2001 John Wiley & Sons, Ltd.

A new approach to determining the content and 15N abundance of total dissolved nitrogen in aqueous samples: TOC analyser-QMS coupling.

Abstract: The standard method for determining the 15N abundance of total dissolved nitrogen (TDN) in aqueous samples (e.g., soil leachate, sewage, urine) is currently Kjeldahl digestion followed by steam distillation or diffusion to isolate the ammonium, and then 15N measurement using IRMS. However, this technique is both time-consuming and laborious. One way of overcoming these disadvantages could be to couple a TOC analyser to determine the TDN with a sufficient quadrupole MS to determine the 15N abundance. The highTOC analyser (Elementar Analysensysteme Hanau, Germany), which catalytically oxidises the sample's total nitrogen with a high, constant yield to nitrogen monoxide (NO), appeared particularly suitable. The quadrupole-MS ESD 100 (InProcess Instruments Bremen, Germany) proved to be a suitable mass spectrometer for the 15N determination of NO. This combination of instruments was found to provide a workable method in numerous measurements of standard and actual samples. The detection limit concerni...