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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 22 (1986), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The introduction of genetically altered microorganisms into natural ecosystems presents fundamentally new problems in risk assessment and ecological effect evaluation. Novel microorganisms, produced by any of several new methods, have the ability to survive and reproduce in the environment. Since most of these organisms are bacteria, they have the potential to interfere with natural processes, displace natural populations, infect new hosts, move between ecosystems, and cause far-reaching ecological disturbanes. This paper reviews currently available methods in ecological research that might be used in evaluating the ecological effects of releasing genetically altered microorganisms. Both structural and functional evaluations are critically reviewed. Microcosm, mesocosm, and field tests should provide valuable predictions concerning the potential ecological impact of genetically altered organisms. Ecosystem assessments will also be useful in post-release studies such as those currently used to evaluate toxic impacts. The present problem does not require the development of new testing methods but rather the creation of adequate predictive models (both conceptual and systems-based) to predict the potential for adverse effect of genetically altered organisms.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 33 (1986), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . The purpose of this research was to examine the roles of physico-chemical parameters in structuring protist communities that colonize artificial substrates. Polyurethane foam (PF) substrates were placed in five lentic systems in northern lower Michigan during summer 1983. These lentic habitats represented a range of trophic states and included three lakes, a bog, and a marsh. Triplicate PF substrates were sampled after 1, 3, 7, 14, 21, and 42 days of exposure. During this study, 90 living protist samples were examined for the number and kinds of species. Water samples were analyzed for pH, conductivity, alkalinity, chloride, silica, temperature, dissolved oxygen, ammonia, and total and ortho-phosphate concurrent with artificial substrate collections. A total of 546 protist species was recorded. Only seven species were found in over 50% of the samples and 121 species were found in only one sample. The 96 most common species were examined in relation to environmental parameters using several multivariate statistical procedures. Factor analysis (principal components with varimax rotation) performed on the total environmental data set showed that three composite factors explained 85% of the variability of the data set. A reciprocal averaging ordination (RAO) was used to reduce species presence/absence data and to separate samples graphically by their species composition. Significant correlations, with RAO-generated axes from all five systems, were found for pH, oxygen, and a nutrient factor to axis 1. Factor analysis on the physico-chemical parameters of the three lakes showed that three factors explained 71% of the environmental data set variability. The RAO-generated axis (axis 1) was correlated with silica, ortho-phosphate, and Factor 2, which was primarily comprised of loadings from ortho-phosphate. These techniques support the hypothesis that a limited number of environmental parameters strongly affect protist community composition.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Long-term patterns of noninteractive and interactive protozoan colonization of polyurethane foam (PF) artificial substrates in Douglas Lake, Michigan, were examined for a 14-yr period. Species-time data were fitted to the Mac Arthur-Wilson equilibrium model, S =Šeq(1 - eGt), and examined through time from 1969-1982. Comparisons were made to historical water chemistry measurements. No long-term changes in water chemistry were evident. Similarly, equilibrium species number (Šeq) and colonization rate (G) oscillated about a mean through time. Protozoan colonization of PF substrates appeared stable for extended periods and showed modest variation from year to year. Examination of 7-yr-old substrates in 1982 revealed little difference from young (〈 50 days) substrates. Previous reports of senescence of artificial substrate communities may have been due to habitat loss within the substrates. No evidence existed for chemical or biological degradation of the lake.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Feeding habits of freshwater protozoa were used to group species into functional, trophic groups. Community structure in differing ecosystems was examined in relation to the number of species occurring in the functional group categories. Six wetland ecosystems and a large river ecosystem were studied. Changes in community structure during the colonization of artificial substrates were also examined. Changes during colonization were studied in a mesotrophic lake, in low-order streams, and in laboratory microecosystems. In the latter case, the response of colonizing communities to a heavy metal toxicant was studied. All communities studied were dominated by bactivorous-detritivorous species and, to a lesser extent, by photosynthetic species. The chief functional role of substrate-associated protozoans appears to be the processing of dead organic matter and its associated bacterial flora. Functional groups utilizing resources other than detrital or mineral nutrients (saprotrophs, algivores, omnivores, and predators) were always minor community components. Colonizing communities were often dominated by photosynthetic species during early colonization stages but were again dominated by bactivorous-detritivorous species at species equilibrium. Low levels of toxicant (Cd) reduced numbers of both photosynthetic and bactivorous-detritivorous species. Higher toxicant levels virtually eliminated photosynthetic species and reduced bacterial detritivores by over one-half. Roles of protozoan species in ecosystems are closely tied to the processing of detritus and the recycling of mineral nutrients. Enumeration of individuals in functional categories is proposed as a simplified method for studying the abundance and activity of protozoa in ecosystems. Examination of changes in functional group composition and the relationship of functional group abundances to rates of carbon processing are suggested for studies of the importance of protozoa to the flow of energy and materials in ecosystems.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 3 (1995), S. 0 
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 33 (1986), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . This study compared the response of protozoan communities colonizing artificial substrates to complex effluents in laboratory microecosystems and validated laboratory predictions using similar sampling methods in the field. Sampling stations were established on a small stream receiving heavy metal and sewage treatment plant effluents. Water from each station was used as a test medium to test the colonization of polyurethane foam artificial substrates in laboratory microecosystems. The heterotrophic index (HI), the ratio of total community biomass to chlorophyll biomass, was also measured. Field colonization trials and HI determinations were carried out at each sampling station. There was a strong negative relationship between the number of species colonizing artificial substrates and the total metal concentration of the water at each station; protozoan colonization was severely depressed at the highest metal concentrations (〉400 μg/liter) and recovered at downstream stations where dilution had taken place. The HI differentiated stations receiving high heavy metal concentrations in the field from those recovering from heavy metal influences. Effect concentrations based on laboratory experiments predicted that the concentration of total heavy metal that would produce a 5% decrease in species number (EC5) was 18 μg/liter, approximately the background concentration found in the stream studied. These experiments demonstrated that laboratory microecosystems or microcosms can be used to predict effects in the field accurately.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Pea plants (Pisum sativum L. cv. Feltham First) exposed to a heat stress of 37°C for 6 h accumulated two low molecular weight (LMW) heat shock proteins (HSPs) of molecular mass 22 kDa. The two LMW HSPs were associated with purified mitochondria. N-terminal amino acid sequencing analysis indicates that the more basic of these proteins is a novel protein. The response of other cultivars of P. sativum to heat shock revealed that up to three 22-kDa HSPs were expressed in a cultivar-specific manner. Evidence presented suggests that the different 22-kDa HSPs arise as a result of there being multiple 22-kDa HSP genes. The expression of the most basic novel HSP was studied in the Feltham First cultivar using two dimensional SDS-PAGE. Treatment of intact plants with chloramphenicol and cycloheximide prior to heat stress treatment indicated that the LMW HSPs were nuclear encoded and de novo synthesised. The response to heat shock was rapid with protein expression detected within 45 min and the protein remained in excess of 6 days following removal of the stress. The protein accumulated to very high levels with maximal expression being 2% of the total mitochondrial protein. The results are discussed in relation to the likely role of LMW HSPs in thermotolerance.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 19 (1990), S. 62-71 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The predictive validity of a multispecies-microcosm toxicity test was evaluated. Predictions of biological response to a complex effluent were made from dose-response curves in laboratory tests and compared to observed effects in the receiving system. No effects on protozoan or macroinvertebrate communities were observed at the field site with effluent concentrations less than the chronic value of 1.7% effluent determined in laboratory tests. In addition, the microcosm test accurately predicted the magnitude of decreases in species richness in protozoan and macroinvertebrate communities in the receiving system at the first downstream site. Predictions of environmental effects for stations farther downstream were generally less accurate and too high, perhaps due to lack of persistence in the toxicity of the effluent. Stimulation of total biomass and algal growth were observed in both laboratory and field tests, but laboratory tests greatly overestimated the magnitude of enrichment responses in the receiving system.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of aquatic ecosystem stress and recovery 1 (1992), S. 59-68 
    ISSN: 1573-5141
    Keywords: global change ; ecosystem restoration ; human population growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Human population growth and the improving condition of human populations in developing countries affect ecological health and integrity. Agricultural development co-opts increasing amounts of global primary production, degrading lands, and reducing species richness. The development of human populations and associated increasing demands for energy assures disposal for increasing amounts of waste, further damaging local ecosystems. Global climate change resulting from diffuse pollutants will affect even the most pristine ecosystems. The human challenge is to maintain ecological integrity and restore ecosystems in the face of accelerating development. The present level of ecosystem protection in not sufficient. Only integrated means of assessing recovery potential and acting to restore ecological productivity can assure continued availability of ecosystem services ranging from free production of food and fiber by plants and animals to final waste assimilation. Restoring ecosystems presumes that species sources are available and that adequate management is in place to monitor and manage recovery. Today, even in the most advanced societies, management is fragmented by non-integrative thinking and the failure to realize that the human scale of political decision-making and management is inappropriate to assure ecosystem restoration. Only by adopting radically new ideas integrating management and ecosystem science can ecological integrity be maintained.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Environmental monitoring and assessment 6 (1986), S. 207-220 
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Difficulties in making accurate, ecosystem-level predictions of environmental effects of chemicals, mixtures, and effluents based solely on the results of tests on single species have necessitated the development of more environmentally realistic, predictive testing methods. This paper describes a multispecies, community-level toxicity test based on the colonization of artificial substrates by microbial species. Tests examined the colonization of initially barren polyurethane foam artificial substrates by Protozoa from a species source colonized in a natural system. Differences in colonization were examined in microecosystems amended with low levels of cadmium, a very toxic heavy metal, and TFM, an organic biocide used against larval sea lamprey. Tests examined differences in colonization over 28 days. For cadmium, effect levels were estimated to be near 1 μg 1−1, in the low range of effect levels determined from chronic single species tests. For TFM, effect levels were estimated to be between 1 and 10 ppm, overlapping the concentrations used in environmental applications. The colonization response, which depends on naked microbial cells reproducing and migrating through toxicant amended water to new substrates, is very sensitive. Tests based on colonization can be adapted to use species from a target receiving system or can use species from a designated natural source. Field validation of these tests can employ nearly identical methods to those used in laboratory studies to assess the accuracy of predictions based on test system data.
    Type of Medium: Electronic Resource
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