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91.
Copepod nauplii are important in plankton food web dynamics, but limited information is available about their ecology due to methodological challenges. Reported here is a new molecular method that was developed, optimized, and tested in laboratory and field samples that uses quantitative PCR (qPCR) to identify and estimate the abundance of nauplii of the planktonic copepod, Parvocalanus crassirostris. The overall approach included collection of bulk zooplankton samples in the field, size fractionation to create artificial cohorts of relatively few developmental stages, obtaining DNA copy number for each size fraction by qPCR amplification of a target gene region, and estimation of the number of animals in each fraction through application of known DNA copy number across developmental stage. Method validation studies found that our qPCR-based approach has comparable accuracy to microscope-based counts of early developmental stages. Naupliar abundance estimates obtained using the two methods on cultured populations were similar; the regression of qPCR estimates on microscope-based counts resulted in a nearly 1:1 ratio (slope = 1.09). The qPCR-based method is superior to traditional identification and quantification methods for nauplii due to its higher taxonomic resolution, sensitive detection over a range of DNA quantities, and relatively high throughput sample processing. 相似文献
92.
Different bioassays with higher plants were approved for use in a bioassay procedure for testing of xenobiotics according
to the German Chemicals Act. Selected environmental pollutants (atrazine, cadmium chloride, 2,6-dichlorobenzonitrile, pentachlorophenol,
potassium dichromate, thiourea), all from a list of reference chemicals, were tested with these methods. Dose-response curves
for growth of oats and turnips were evaluated in soil and vermiculite (nonsorptive substrate), and availability to plants
was calculated by comparing the EC50 values for one chemical in both substrates. The most active chemical was atrazine, followed by 2,6-dichlorobenzonitrile,
pentachlorophenol, potassium dichromate, cadmium chloride, and thiourea. The least available compound to plants was pentachlorophenol,
tested with turnips (Brassica rapa var.rapa). The strongest inhibition of germination, demonstrated in an in vitro assay with garden cress (Lepidium sativum), was found with 2,6-dichlorobenzonitrile, the lowest with atrazine. The effect of an extended exposure of the plants to
the chemicals was evaluated in a long-term bioassay with oats (Avena sativa) in hydroponic culture. Several dose-response curves during the growing period were derived. It was found that the EC50 values for atrazine and thiourea decreased markedly during the first four weeks; thereafter the changes were much smaller.
As an overall conclusion, a bioassay procedure is proposed that can be included in the graduated plan recommended by the German
Chemicals Act. 相似文献
93.
Müfit Bahadir Ralf Bock Tina Dettmer Oliver Falk Jürgen Hesselbach Petra Jopke Birthe Matthies Roland Meyer-Pittroff Christiane Schmidt-Nädler Hubertus Wichmann 《Environmental Sciences Europe》2004,16(1):19-28
Aims and Scope
German rendering plants produce 300,000 tons of animal fat per year. Until recently, these raw products have been in wide use as nutritional additive for cattle and other animals fodder but now they have been banned due to their assumed role in BSE infection. Therefore, alternative fields of usage are required. In this context the Deutsche Bundesstiftung Umwelt (DBU) is sponsoring a joint research project which deals with the production and testing of cooling lubricants based on animal fat esters.Methods
In a first step, characteristics and quality of the animal fat were analyzed and monitored for a whole year in order to identify e.g. seasonal variations. The investigations covered the following fat specific and trace analytical parameters: total contamination, sulfates ash, water content, peroxide number, iodine value, kinematical viscosity, neutralisation number (free fatty acids), fatty acid spectra, elements / heavy metals (Al, B, Ca, Cd, Cr, Cu, Fe, K, Mo, Mn, Na, Ni, P, Pb, S, Sn, V, W and Zn), polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans.Results
Valuable hints on the design of the technical process of fatty acid methylesters production were gained by regarding the fat specific parameters. For example, filtration and dewatering of the fats proved necessary. Small variations of iodine value, viscosity and fatty acid spectrum pointed at a quite constant composition of the raw material in the course of the year. Clues to the degree of hydrolysis and decay of the fat were given by the share of free fatty acids. The saturated fatty acids, most interesting for the production of the cooling lubricants, were present in the fatty acid spectra in the rage of 36.4% to 54.6%. Trace analytical investigations concerning inorganic and organic pollutants proved a low basic contamination of the technical animal fats.Outlook
Next step will be to present the pilot plant for the production of the cooling lubricants and further analytical results in context with the production process. 相似文献94.
Horsák M Hájek M Hájková P Cameron R Cernohorsky N Apostolova I 《Die Naturwissenschaften》2011,98(8):671-681
Mollusc communities of previously unexplored Bulgarian fens were studied in order to determine and generalise the patterns
of species richness and composition along the mineral richness gradient. The aim was also to compare predictive values of
the environment, vegetation and spatial structure. Altogether, 44 mollusc species were recorded at 40 treeless fen sites.
Species richness varied from 0 to 18 species per site, and it was positively associated with the mineral gradient and negatively
with altitude. However, the best predictor was obtained using plant species composition. All explanatory variables had higher
effect on land snails than on the entire mollusc assemblage (including aquatic species). Species richness and abundance were
significantly and positively correlated with the species composition turnover; the communities were highly nested, with poor
sites having subsets of the fauna found in the richest. The main direction of mollusc species turnover was highly associated
with that observed for vegetation, and the main gradient of plant species composition was able to explain nearly 20% of total
variation in mollusc data. We found that spatial structure explained by far the highest proportion of independent variation,
which reflected the high level of geographical isolation of Bulgarian fens and regional differences independent of any environmental
variation. Our results demonstrate (1) the general role of mineral richness gradient for structuring mollusc communities in
fens, (2) the pivotal indicator role of plant species composition in predicting species composition of mollusc communities,
despite being trophically independent and (3) the effect of isolation and origins of the habitat on species composition: most
species have wide geographical distributions within the habitat type, and geographical patterns within Bulgaria may have a
stochastic element. 相似文献
95.
A 700-year paleoecological record of boreal ecosystem responses to climatic variation from Alaska 总被引:1,自引:0,他引:1
Tinner W Bigler C Gedye S Gregory-Eaves I Jones RT Kaltenrieder P Krähenbühl U Hu FS 《Ecology》2008,89(3):729-743
Recent observations and model simulations have highlighted the sensitivity of the forest-tundra ecotone to climatic forcing. In contrast, paleoecological studies have not provided evidence of tree-line fluctuations in response to Holocene climatic changes in Alaska, suggesting that the forest-tundra boundary in certain areas may be relatively stable at multicentennial to millennial time scales. We conducted a multiproxy study of sediment cores from an Alaskan lake near the altitudinal limits of key boreal-forest species. Paleoecological data were compared with independent climatic reconstructions to assess ecosystem responses of the forest tundra boundary to Little Ice Age (LIA) climatic fluctuations. Pollen, diatom, charcoal, macrofossil, and magnetic analyses provide the first continuous record of vegetation fire-climate interactions at decadal to centennial time scales during the past 700 years from southern Alaska. Boreal-forest diebacks characterized by declines of Picea mariana, P. glauca, and tree Betula occurred during the LIA (AD 1500-1800), whereas shrubs (Alnus viridis, Betula glandulosa/nana) and herbaceous taxa (Epilobium, Aconitum) expanded. Marked increases in charcoal abundance and changes in magnetic properties suggest increases in fire importance and soil erosion during the same period. In addition, the conspicuous reduction or disappearance of certain aquatic (e.g., Isoetes, Nuphar, Pediastrum) and wetland (Sphagnum) plants and major shifts in diatom assemblages suggest pronounced lake-level fluctuations and rapid ecosystem reorganization in response to LIA climatic deterioration. Our results imply that temperature shifts of 1-2 degrees C, when accompanied by major changes in moisture balance, can greatly alter high-altitudinal terrestrial, wetland, and aquatic ecosystems, including conversion between boreal-forest tree line and tundra. The climatic and ecosystem variations in our study area appear to be coherent with changes in solar irradiance, suggesting that changes in solar activity contributed to the environmental instability of the past 700 years. 相似文献
96.
Petra Quillfeldt Leandro Bugoni Rona A. R. McGill Juan F. Masello Robert W. Furness 《Marine Biology》2008,155(6):593-598
Stable isotopes of growing feathers and blood both represent assimilated diet, and both tissues are used to study the diet
and foraging distribution of marine and terrestrial birds. Although most studies have assumed that both tissues represent
a difference of one trophic level to diet, the enrichment factors of blood and feathers may differ, especially where endogenous
reserves are used as precursors during feather synthesis. In this study, we compare carbon and nitrogen stable isotopes of
blood and simultaneously growing feathers of five species of Procellariiformes, representing five genera, different geographical
regions and different life stages (chicks and adults). In all species, feathers were enriched in 15N and 13C compared with blood. Isotopic values of carbon and nitrogen were correlated in different tissues growing simultaneously
for most species analyzed, suggesting that mathematical corrections could be used to compare different tissues. Our results
imply that more care needs to be taken when comparing stable isotope signatures across studies assuming different tissues
are equivalent indicators of trophic ecology. 相似文献
97.
P. Lasch M. Lindner B. Ebert M. Flechsig F.-W. Gerstengarbe F. Suckow P.C. Werner 《Environmental Modeling and Assessment》1999,4(4):273-286
A methodology for regional application of forest simulation models has been developed as part of an assessment of possible climate change impacts in the Federal state of Brandenburg (Germany). Here we report on the application of a forest gap model to analyse the impacts of climate change on species composition and productivity of natural and managed forests in Brandenburg using a statistical method for the development of climate scenarios. The forest model was linked to a GIS that includes soil and groundwater table maps, as well as gridded climate data with a resolution of 10 × 10 km and simulated a steady-state species composition which was classified into forest types based on the biomass distribution between species. Different climate scenarios were used to assess the sensitivity of species composition to climate change. The simulated forest distribution patterns for current climate were compared with a map of Potential Natural Vegetation (PNV) of Brandenburg.In order to analyse the possible consequences of climate change on forest management, we used forest inventory data to initialize the model with representative forest stands. Simulation experiments with two different management strategies indicated how forest management could respond to the projected impacts of climate change. The combination of regional analysis of natural forest dynamics under climate change with simulation experiments for managed forests outlines possible trends for the forest resources. The implications of the results are discussed, emphasizing the regional differences in environmental risks and the adaptation potentials of forestry in Brandenburg. 相似文献
98.
Doris Vetterlein Dirk Wesenberg Petra Nathan Anja Brutigam Angelika Schierhorn Jürgen Mattusch Reinhold Jahn 《Environmental pollution (Barking, Essex : 1987)》2009,157(11):3016-3024
Pteris vittata is known to hyperaccumulate As but the mechanism is poorly understood. We found an increase of As concentration with increasing soil solution As concentrations, but P application had no impact, although plant P concentrations responded to different rates of P supply. As in fronds was dominantly (82–89%) present in the form of AsIII. In roots we detected 45% as AsIII which is higher than reported in previous studies and supports substantial As-reduction to take place in roots. We detected PC2/3GS–AsIII, PC2–GS–AsIII and (PC2)2–AsIII in increasing amounts with application of As. The total amount of PC was in the range reported previously and far too small to assign a significant role in As detoxification to PCs. The close correlation between S and As in fronds and the lack of data on sulphur uptake and metabolism indicates the need for a detailed investigation on sulphur nutritional status and As metabolism in P. vittata. 相似文献
99.
Christopher Reyer Johann Bachinger Ralf Bloch Fred F. Hattermann Pierre L. Ibisch Stefan Kreft Petra Lasch Wolfgang Lucht Christoph Nowicki Peter Spathelf Manfred Stock Martin Welp 《Regional Environmental Change》2012,12(3):523-542
Located in a relatively dry region and characterized by mainly sandy soils, the German Federal State of Brandenburg (surrounding the capital city of Berlin) is especially vulnerable to climate change impacts (e.g., summer droughts) and cascading effects on ecological systems (e.g., decreasing ground water tables, water stress, fire risk, productivity losses) with socioeconomic implications. Furthermore, a complex interplay of unemployment, rural exodus, and an aging population challenges this structurally weak region. We discuss adaptation measures that are either implemented or planned, as well as research into adaptation strategies to climate change for the sectors forestry, agriculture, and water management as well as in nature conservation in light of socioeconomic and ecological challenges and benefits. In doing so, we adopt a systemic view of Brandenburg where the sectors discussed are seen as subsystems embedded in a larger regional system. This at least partially holarchical approach enables the identification of conflicts between adaptation measures, but also of synergies among the sectors that pertain to successful adaptation to climate change. The insights gained ultimately highlight the need for cross-sectoral, adaptive management practices that jointly target a sustainable regional development. 相似文献
100.