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  • 1
    Electronic Resource
    Electronic Resource
    Ecological Restoration through Behavioral Change (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 3 (1995), S. 0 
    Details
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1526-100X.1995.tb00074.x
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  • 2
    Electronic Resource
    Electronic Resource
    Use of Protozoan Communities to Predict Environmental Effects of Pollutants (1986)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 33 (1986), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1550-7408.1986.tb05579.x
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  • 3
    Electronic Resource
    Electronic Resource
    Multivariate Analysis of Protist Communities in Lentic Systems (1986)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 33 (1986), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1550-7408.1986.tb05581.x
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  • 4
    Electronic Resource
    Electronic Resource
    Long-Term Patterns of Protozoan Colonization in Douglas Lake, Michigan (1985)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1550-7408.1985.tb03021.x
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  • 5
    Electronic Resource
    Electronic Resource
    Functional Groups in the Protozoa: Roles in Differing Ecosystems, (1985)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1550-7408.1985.tb04037.x
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  • 6
    Electronic Resource
    Electronic Resource
    Identification and characterisation of cultivar-specific 22-kDa heat shock proteins from mitochondria of Pisum sativum (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030310.x
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  • 7
    Electronic Resource
    Electronic Resource
    ECOLOGICAL CONSEQUENCE ASSESSMENT: EFFECTS OF BIOENGINEERED ORGANISMS (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 22 (1986), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1752-1688.1986.tb01873.x
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  • 8
    Electronic Resource
    Electronic Resource
    Field evaluation of predictions of environmental effects from a multispecies-microcosm toxicity test (1990)
    Springer
    Archives of environmental contamination and toxicology 19 (1990), S. 62-71 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01059813
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  • 9
    Electronic Resource
    Electronic Resource
    Export of species to islands from sources of differing maturity (1985)
    Springer
    Hydrobiologia 121 (1985), S. 103-109 
    Details
    ISSN: 1573-5117
    Keywords: protozoa ; colonization ; species exchange ; artificial substrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Export of species from sources (epicenters) of differing ages and complexities was examined using laboratory microcosms. Polyurethane foam (PF) artificial substrates were colonized by protozoans for different time periods in a small pond. Substrates were returned to the laboratory and used as epicenters for protozoan colonization of barren PF ‘islands’ in initially sterile microcosms. Islands were exposed to epicenters for either 24 h or continuously for 28 d. Islands from pairs of microcosms exposed to epicenters of identical ages were sampled on 1, 3, 7, 14, 21, 28 and 46 d after initial epicenter exposure. Colonization parameters were estimated by fitting numbers of colonizing species to the MacArthur-Wilson equilibrium model. Islands exposed continuously to epicenters were colonized by significantly more species than those exposed for only 24 h. Islands exposed to immature, species poor epicenters were colonized by a greater proportion of the source community than those exposed to more mature, species rich epicenters. All islands were depauperate compared to epicenters except those exposed to the most immature (1 d old) epicenter. Colonization continued at a reduced rate in spite of the absence of the epicenter. Results from communities with rapid species turnover and rapidly reproducing species suggest that the continuous presence of a species source is less important for colonization of a new habitat. Dispersal of potential colonists occurs rapidly in these communities. Less mature communities dominated by pioneer forms are more effective at producing colonists than more mature communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008712
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  • 10
    Electronic Resource
    Electronic Resource
    The scientific basis of bioassays (1989)
    Springer
    Hydrobiologia 188-189 (1989), S. 5-20 
    Details
    ISSN: 1573-5117
    Keywords: bioassay ; ecotoxicology ; stress ; microcosm ; mesocosm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultimate goal of ecotoxicological testing is to predict ecological effects of chemicals and other stressors. Since damage should be avoided rather than corrected after it occurs, the predictive value of such tests is crucial. A modest base of evidence shows that, in some cases, extrapolations from bioassays on one species to another species are reasonably accurate and, in other cases, misleading. Extrapolations from laboratory bioassays to response in natural systems at the population level are effective if the environmental realism of the bioassay is sufficiently high. When laboratory systems are poor simulations of natural systems, gross extrapolation errors may result. The problem of extrapolating among levels of biological organization has not been given the serious attention it deserves, and currently used methodologies have been chosen for reasons other than scientific validity. As the level of biological organization increases, new properties are added (e.g., nutrient cycling, energy transfer) that are not readily apparent at the lower levels. The measured responses (or end points) will not be the same at all levels of biological organization, making the validation of predictions difficult. Evidence indicates that responses of ecologically complex laboratory systems correspond to predicted and documented patterns in stressed ecosystems. The difficulties of improving the ecological evidence used to predict adverse effects are not insurmountable since the essence of predictive capability is the determination of effects thresholds at all levels of organization. The dilemma between basing predictive schemes on either traditional or holistic methods can only be solved by facing scientific and ethical questions regarding the adequacy of evidence used to make decisions of environmental protection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027769
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