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  • 1
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Simulation of climate change (summer drought) stimulated autotrophy in a stream draining a Welsh peatland. Biofilm autotrophic biomass (chlorophyll) increased by 145% and was correlated with an increased overall metabolic activity (r = 0.75, P〈0.05). Bacterial population densities were not significantly affected.2. The increased autotrophy was probably related to a decrease in the organic:inorganic ratio of nutrients released from the wetland to the stream.3. Bacterial reserves of poly-β-hydroxyalkanoate (PHA) fell by 51%. Increased nitrate concentrations were inversely correlated with autotrophic diversity (r=−0.88, P 〈 0.001).4. The increased autotrophic biomass represents an increased nutrient supply for the higher trophic levels which could promote higher productivity within the stream ecosystem as a whole.5. The simulation also caused a cooler (11%, P〈0.01) streamflow from the drought-impacted wetland, which could mitigate against any adverse temperature-dependent effects of future climatic change.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Microbial ecology 40 (2000), S. 16-24 
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Relationships between biofilm structural components (algal and bacterial biomass) and the activities of some extracellular enzymes that contribute to the ability to degrade organic matter) were explored for six Atlantic and three Mediterranean streams and rivers. The biofilms in these fluvial systems accounted for a wide range of bacterial and algal biomass and colonized the most common benthic habitats. Ratio of bacteria/algae biomass was lower in Atlantic than in Mediterranean streams, but enzymatic activities (β-glucosidase, β-xylosidase, phosphatase) were in general greater in the Mediterranean stream biofilms. Climatic characteristics (especially temperature) may explain the differences in enzymatic activities between biofilms of similar structure but different flow regime. The ratio β-xylosidase: β-glucosidase was similar (around 0.5) for all streams and substrata considered, showing that there is a general higher utilization of cellobiosic than xylobiosic molecules in fluvial systems. In general, highly heterotrophic biofilms showed lower extracellular enzymatic activities than more autotrophic biofilms. Maximum enzymatic activity is achieved when the algal biomass is two- to threefold higher than the bacterial biomass. The relevance of algal biomass on the heterotrophic ability of biofilms may be related to the physical proximity between the two, but also to the high proportion of polymeric carbohydrates included in algal exudates and lysis products, whose use is enzyme-mediated.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 37 (1999), S. 19-28 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Effects of metal pollution from a zinc factory on microbenthic algal communities were assessed in three neighboring streams on the Dutch-Belgian border. Diatom species composition was experimentally related to water quality by transferring racks with colonized glass discs from a polluted stream to a reference stream and vice versa. The succession of species and the changes in biomass and metal accumulation were measured during experiments in spring, autumn, and winter. Metal concentrations and dry weight in translocated biofilms tended to conform with those in local biofilms within an incubation time of 14 to 18 days. Bray-Curtis similarity values from the different communities indicated that diatom communities responded more completely to the metal-polluted conditions than to the reference water quality. Cymbella minuta, Diatoma vulgare var. ehrenbergii, Navicula sp., and Melosira varians had a lower percentage in assemblages placed in the metal-polluted streams. In contrast, Pinnularia sp. and Neidium ampliatum decreased in assemblages from the polluted streams that were transferred to the reference stream. Achnanthes minutissima and Navicula seminulum (N. atomus) proliferated on any translocation, possibly reflecting an opportunistic strategy and a high tolerance for Zn and Cd. The behavior of the species in relation to metal pollution generally accorded with observations in the literature. However, it seems that metal tolerance is not the only selective factor, and other ecological variables may also influence the composition of microphytobenthic communities.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5176
    Keywords: diatoms ; Bacillariophyta ; periphyton ; monitoring ; sampling ; rivers ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Many methods for using diatoms for routine monitoring of water quality have been developed in Europe and, in some countries, these are being used to enforce environmental legislation. In order to facilitate their wider use, particularly with respect to European Union legislation, steps are being taken to harmonize methodology. In this paper, the principles and practice of sampling are described in relation to the main habitat types encountered in Europe. Although details of methods and sampling programmes have to be tailored to particular circumstances and the overall objectives of the monitoring, a number of generalizations can be made. Where available, rocks and other hard surfaces are the preferred substrates and methods for sampling these are described. If such substrata are not available, then introduced ('artificial') substrata have many applications. Various types of introduced substrata can be used successfully, so long as some basic precautions are described. Other types of substrata such as macrophytes and macroalgae may also be useful under certain circumstances, although there is less consensus in the literature on the most appropriate methods, and of the validity of comparisons between indices computed from epiphytic and epilithic communities. When designing surveys, it is recommended that as far as possible, extremes of non-water quality factors (e.g. shade, current speed, etc) are avoided, unless these are characteristic of the system under investigation. Detailed guidelines for sampling epilithon are described. Along with the recommendations for sampling other substrata, it is hoped that these provide a framework that can be adapted to most river types in Europe.
    Type of Medium: Electronic Resource
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  • 5
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    In:  http://aquaticcommons.org/id/eprint/5335 | 3949 | 2011-09-29 15:04:14 | 5335 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: River structure and functioning are governed naturally by geography and climate but are vulnerable to natural and human-related disturbances, ranging from channel engineering to pollution and biological invasions. Biological communities in river ecosystems are able to respond to disturbances faster than those in most other aquatic systems. However, some extremely strong or lasting disturbances constrain the responses of river organisms and jeopardise their extraordinary resilience. Among these, the artificial alteration of river drainage structure and the intense use of water resources by humans may irreversibly influence these systems. The increased canalisation and damming of river courses interferes with sediment transport, alters biogeochemical cycles and leads to a decrease in biodiversity, both at local and global scales. Furthermore, water abstraction can especially affect the functioning of arid and semi-arid rivers. In particular, interception and assimilation of inorganic nutrients can be detrimental under hydrologically abnormal conditions. Among other effects, abstraction and increased nutrient loading might cause a shift from heterotrophy to autotrophy, through direct effects on primary producers and indirect effects through food webs, even in low-light river systems. The simultaneous desires to conserve and to provide ecosystem services present several challenges, both in research and management.
    Keywords: Atmospheric Sciences ; Earth Sciences ; Environment ; Biogeochemical cycle ; Canals ; Conservation ; Ecosystem disturbance ; Man-induced effects ; Nutrients (mineral) ; Rivers ; Sediment transport ; Species diversity
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 75-88
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  • 6
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    In:  http://aquaticcommons.org/id/eprint/17918 | 12051 | 2015-09-23 08:11:39 | 17918 | Indian Fisheries Association
    Publication Date: 2021-07-02
    Description: Present paper attempts to analyze consumption pattern and consumer preferences towards value-added fish and fish products in north zone of India. Results reveal that socio economic variables affect consumption of value-added fish and fish products. A total of 49 percent respondents were of middle age group (35 to 50 years). All were literates except 7% from the rural area. All were purchasing fish at least once in 15 days. A total of 90% respondents in rural, 11% in semi urban and 50% in urban area were unaware of value-added fish and fish products. About 10% of respondents had consumed it, out of which most were from urban area. Demand analysis by Cobb Douglas (CD) Demand function revealed that when price of fish, price of the substitutes, income of family and family size were used as independent variables, variation in demand of fish explained by CD Demand function was about 39% in urban area, 24% in semi urban area and 22% in rural area. From Garette ranking technique major problems in fish consumption found were irregular supply, lack of fresh fish, high price and presence of bones in fish. While lack of awareness, unavailability, no preference and unacceptable taste were major problems for consumption of value-added fish and fish products.
    Keywords: Fisheries ; consumption ; consumer preferences ; value-added fish products ; economic development ; Haryana ; Punjab ; Delhi ; India
    Repository Name: AquaDocs
    Type: article
    Format: application/pdf
    Format: application/pdf
    Format: 19-27
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  • 7
    Publication Date: 2003-01-01
    Print ISSN: 0047-2425
    Electronic ISSN: 1537-2537
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 8
    Publication Date: 1990-02-01
    Print ISSN: 0043-1354
    Electronic ISSN: 1879-2448
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Elsevier
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  • 9
  • 10
    Publication Date: 2016-09-09
    Description: The ecological impacts of emerging pollutants such as pharmaceuticals are not well understood. The lack of experimental approaches for the identification of pollutant effects in realistic settings (that is, low doses, complex mixtures, and variable environmental conditions) supports the widespread perception that these effects are often unpredictable. To address this, we developed a novel screening method (GSA-QHTS) that couples the computational power of global sensitivity analysis (GSA) with the experimental efficiency of quantitative high-throughput screening (QHTS). We present a case study where GSA-QHTS allowed for the identification of the main pharmaceutical pollutants (and their interactions), driving biological effects of low-dose complex mixtures at the microbial population level. The QHTS experiments involved the integrated analysis of nearly 2700 observations from an array of 180 unique low-dose mixtures, representing the most complex and data-rich experimental mixture effect assessment of main pharmaceutical pollutants to date. An ecological scaling-up experiment confirmed that this subset of pollutants also affects typical freshwater microbial community assemblages. Contrary to our expectations and challenging established scientific opinion, the bioactivity of the mixtures was not predicted by the null mixture models, and the main drivers that were identified by GSA-QHTS were overlooked by the current effect assessment scheme. Our results suggest that current chemical effect assessment methods overlook a substantial number of ecologically dangerous chemical pollutants and introduce a new operational framework for their systematic identification.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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