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  • Ecology
  • Industrial Chemistry
  • 1980-1984  (15)
  • 1935-1939
  • 1983  (7)
  • 1982  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 131 (1982), S. 107-111 
    ISSN: 1432-072X
    Keywords: Cyanophyta ; Cyanobacteria ; Oscillatoria rubescens ; Photosynthetic pathways ; Photosynthetic enzymes ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Short term14C labelling experiments and enzymatic activities related to primary pathways of photosynthesis have been studied in the cyanophytaOscillatoria rubescens D.C. from axenic cyclostat cultures. Responses of samples from cultures with different amounts of nitrogen are presented and compared. Variations in photosynthetic pigments are used to quantify the degree of nitrogen starvation at different levels. PEPcarboxylase activity remains low and is not affected by nitrogen starvation. RuBPcarboxylase activity is lowered to nearly two thirds of its normal metabolic rate by starvation but PEPcarboxykinase and aspartate aminotransferase activities are significantly higher in this case. Malate dehydrogenase is slightly altered and malic enzyme is never active. Starved algae replaced in fresh complete media fix rapidly14C in nitrogen compounds such as amino acids. Results are discussed in regard to both physiological and ecological characteristics ofO. rubescens. PEPcarboxykinase can play a role in making efficient use of HCO 3 - .
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical biology 18 (1983), S. 255-280 
    ISSN: 1432-1416
    Keywords: Population dyamics ; Ecology ; Periodic solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A model of the competition of n species for a single essential periodically fluctuating nutrient is considered. Instead of the familiar Michaelis-Menten kinetics for nutrient uptake, we assume only that the uptake rate functions are positive, increasing and bounded above. Sufficient conditions for extinction are given. The existence of a nutrient threshold under which the Principle of Competitive Exclusion holds, is proven. For two species systems the following very general result is proven: All solutions of a τ-periodic, dissipative, competitive system are either τ-periodic or approach a τ-periodic solution. A complete description of the geometry of the Poincaré operator of the two species system is given.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant ecology 48 (1982), S. 123-131 
    ISSN: 1573-5052
    Keywords: Ecology ; Fringe communities ; Numerical classification ; Ostrya carpinifolia woods ; Phytogeographic elements ; Phytosociology ; Southern Alps (N-Italy) ; Vegetation dynamics ; Wood edge communities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forest regeneration in the vegetation complex of the submontane belt in the Southern Alps involves the active participation ofOstrya carpinifolia woods and their wood edge communities. The corresponding syndynamical processes are described by employing phytosociological, phytogeographical and ecological methods. It is concluded that: (i) The communities of the grassland-wood transition are of major importance in the successional developments in this man-made vegetation complex. (ii) Many species occurring in the region of the deciduous forests of Eurasia find their refuge in such transitional communities and are supposed to play an important part in the succession. (iii) Ostrya carpinifolia is considered as an early successional tree species.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 69 (1982), S. 293-297 
    ISSN: 1573-5036
    Keywords: Ecology ; Frankia ; Nitrogen fixation ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth responses of Frankia isolates to decreasing water potential were monitored in systems where potentials were controlled by KCl, NaCl and Polyethylene glycol. The highest potential tested was −2 bar (basal medium). The general pattern emerging was that isolates fromAlnus glutinosa, A. viridis andComptonia peregrina showed declining growth at potentials below −2 to −5 bar. AMyrica gale isolate showed declining growth with decreasing potential. All isolates were more sensitive to decreases in potential in a matric controlled than an osmotic controlled system. They all showed approximately 50 percent growth reduction at −5 to −8 bar, and meagre growth at −16 bar after 35 days. The Comptonia isolate was the most vigorous at low potentials. Nitrogen fixation ability was monitored for two isolates. Highest specific activities were observed between −3 and −5 bar for the Myrica isolate and between −5 and −7.5 bar for theA. glutinosa isolate.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5036
    Keywords: Actinorhizas ; (Actinomycetes) ; Ecology ; Hippophaë ; (Mystiflora: Elaeagnaceae) ; Longidorus ; (Nematoda: Longidoridae) ; Nodulation ; Soil ; sterization ; Vegetational succession ; Tylenchorhynchus (Nematoda: Tylenchrohynchidae)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Hippophaë rhamnoides seedlings were grown in sterilized and unsterilized soil from a decliningH. rhamnoides scrub, to which different numbers ofLongidorus sp. andTylenchorhynchus microphasmis were added. In sterilized and unsterilized soil, retardation of growth, content of dry matter in the shoots, and incidence of deformed short lateral roots of test plants were positively correlated with counts of both nematode species. Nitrogen content in the shoots, nodulation on the roots of test plants and increase increase in nematodes were negatively correlated with the initial number of both nematode species in sterilized soil. In unsterilized soil, an unknown biotic factor was present that reduces growth ofH. rhamnoides, nodulation and multiplication of the nematodes. This factor seems to interact with the nematodes in reducing growth ofH. rhamnoides.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5036
    Keywords: Catalase ; Ecology ; Fertilizers ; H2O2∶H2O2 oxidoreductase ; Rhizosphere effects ; Soil enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Catalase activity of a loamy sand under a 3-year crop rotation in the southeastern U.S.A. was monitored. Corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] were the summer crops in the rotation. Winter wheat (Triticum aestivum L.) was planted after corn, and soybean was followed by a winter fallow period. Cotton was followed by a mixture of common vetch (Vicia sativa L.) and crimson clover (Trifolium incarnatum Gibelli & Belli) which was eventually plow-incorporated as a green manure. Highest mean catalase activities were recorded in soil under the wheat, soybean, and winter legume crops; lowest activities were found in soil bearing corn and cotton, and during the winter fallow period. The fertilization regime influenced soil catalase activity independently of the crop. Soil deficient in any of the major elements showed low enzyme activity. Highest activity was found in soil fertilized with P and K, and with N supplied by a winter legume crop. Addition of supplementary mineral nitrogen to this regime reduced catalase activity. Elimination of the winter legume crop from an otherwise complete fertilization regime resulted in a drastic reduction in enzyme activity. In soil receiving a complete fertilization regime there was a close correlation between soil catalase and xylanase activities. A similar correlation between these two enzymes was not found in soil receiving incomplete fertilization.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5036
    Keywords: Chitin ; Chitinase ; Chitinglycanohydrolase ; E. C. 3.2.1.14 ; Ecology ; Fertilizers ; Rhizosphere effects ; Soil enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Chitinase activity was determined by incubating a mixture of toluene-treated soil with 1% (w/w) colloidal chitin suspension for 18 h at 37°C and then, after dilution, assaying the amount of N-acetyl-glucosamine released. Maximal chitinase activity was observed at 45°C and optimal pH for enzymatic reaction was 5.0–5.5. Soil chitinase activity decreased with increasing soil depth and was significantly affected by crop cover and fertilization regime. Chitin added to soil stimulated chitinase activity. Enzyme activity was correlated with the soil fungal population but not with numbers of actinomycetes or bacteria. A specialized mycoflora was associated with chitin decomposition.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 7 (1982), S. 177-180 
    ISSN: 1573-5133
    Keywords: Temperature ; Behavior ; Ecology ; Fisheries ; Fish ; Marine juveniles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Sixteen yearling winter flounder, tested individually for 3-day periods in electronic shuttleboxes, voluntarily occupied an 8–27°C range of temperature, with a modal final thermal preferendum of 18.5°C (mean 18.7°C, median 19°C, midpoint 17.5°C, s.d. 1.9°C, S k + 0.33). The locomotor activity pattern of the yearling fish in the laboratory was markedly nocturnal, with mean hourly nocturnal activity exceeding mean hourly diurnal activity by a factor of 3.4. Maximum activity occurred at 0300 EST, minimum activity at 1400 EST. While activity generally increased with temperature, a local activity minimum occurred at 18.7°C, coinciding with the 24-hour mean final thermal preferendum. Comparison of these laboratory data with previously published field data suggest that behavioral responses to temperature and light play significant roles in determining age- and size-specific differences in seasonal depth stratification and onshore-offshore distributions in this species.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 7 (1982), S. 121-136 
    ISSN: 1573-5133
    Keywords: Seasonality ; Predator-prey ; Predator interference ; Turnoverrate ; Diversity ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Development of the fish community on a submerged 16 m barge and variation in fish abundance on nearby transects were surveyed twice monthly for twenty months. A steady increase in abundance was observed for certain fishes on the barge, whereas a few species exhibited distinct seasonal variation on both the barge and transects. Most of the seasonal species settled between March and May. Some seasonal species appeared to be site selective in their settlement and consequently settled juveniles were clumped in their distribution. An abundance of preferred topographical features may be why settlement was relatively high at the study site and indirectly why predators became significantly (r3 = 7.67***, N = 37) more abundant at the study area during the months of maximum prey settlement. Concurrent settlement of several species during the same few months may be important because juveniles become an abundant food source to predators during those few months only. Periodic swamping of predators by abundant juvenile prey may improve the chances for individuals of rarer prey species to be overlooked and therefore be succesfully recruited.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 9 (1983), S. 41-53 
    ISSN: 1573-5133
    Keywords: Artificial reefs ; Competition ; Intermediate disturbance ; Ecology ; Mortality ; Predation ; Recruitment ; Stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis In January 1977, a record breaking cold spell caused fish kills at Big Pine Key, Florida. Census data collected before and after the cold spell from a series of model reefs constructed in 1975 showed a significant drop in mean number of reef fish species and individuals. Following this disturbance, high recruitment of juveniles occurred, presumably due to reduced competition, predation, or a combination of these. Model and natural patch reef communities examined the summer following the cold spell (1977) were significantly different from those examined the summer before (1976) and the second summer following the cold spell (1978). During the summer of 1977, a significantly smaller mean fish size and a significantly greater mean number of species and individuals were observed. Increased species richness following the cold spell is consistent with the intermediate disturbance hypothesis. Contrary to some theoretical predictions, results suggest reef fish communities are highly resilient to some regional disturbance.
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-01-22
    Description: The larva of the blowfly Cochliomyia hominivorax, also known as the screwworm, eats the living flesh of cattle and sheep and other warm-blooded animals. A program to eradicate the screwworm in the United States was initiated in the 1950's. The program was very effective until 1968, but severe screwworm outbreaks occurred in 1972 to 1976 and in 1978. Although the program has again been effective since 1979, the possibility of outbreaks recurring in the future has highlighted the need for a broader understanding of the pest. Studies of screwworm populations in the United Stated and Mexico indicate that much of the genetic diversity of this insect is distributed among sympatric non-interbreeding populations. A new approach may be required to retain the effectiveness of the control program and to prevent a serious outbreak from threatening the economic viability of the U.S. livestock industry.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Richardson, R H -- Ellison, J R -- Averhoff, W W -- New York, N.Y. -- Science. 1982 Jan 22;215(4531):361-70.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7199204" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cattle ; Cattle Diseases/*prevention & control ; Diptera/classification/*physiology ; Ecology ; Infertility, Male ; Insect Control/methods ; Karyotyping ; Male ; Myiasis/*prevention & control ; North America ; Pest Control, Biological/*methods ; Reproduction ; Screw Worm Infection/*prevention & control
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 12
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-07-16
    Description: By the close of this century the world may have to feed as many as 2 billion additional people. Most of them will be born in developing countries, especially in marginal lands ill-suited for food production. This article focuses on efforts by the International Agricultural Research Centers to increase food production in the Third World and addresses the social and ecological issues raised by the introduction of high-yielding varieties into fertile Third World lands and describe how varieties are being tailored for introduction into marginal areas.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Plucknett, D L -- Smith, N J -- New York, N.Y. -- Science. 1982 Jul 16;217(4556):215-20.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7089555" target="_blank"〉PubMed〈/a〉
    Keywords: *Agriculture ; *Developing Countries ; Ecology ; *Food Supply ; Humans ; *Research
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 13
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1983-08-19
    Description: Ground water contamination is of increasing concern in the United States because about 50 percent of our drinking water comes from well water. The causes of contamination stem from both point sources and nonpoint sources. Since ground water moves slowly, the contaminant may affect only a small portion of an aquifer for a considerable period of time. Deleterious effects on human health have resulted from pathogenic organisms in ground water and from its toxic chemical composition. It is difficult to estimate the extent of contamination on a national basis as the frequency of instances of contamination is very variable. Remedial actions to clean up aquifers are difficult, expensive, and sometimes not feasible. Many of the laws and regulations that control ground water contamination are designed with other main objectives.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pye, V I -- Patrick, R -- New York, N.Y. -- Science. 1983 Aug 19;221(4612):713-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6879171" target="_blank"〉PubMed〈/a〉
    Keywords: Ecology ; United States ; United States Environmental Protection Agency ; Water Pollution/*analysis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 14
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1983-11-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sun, Marjorie -- New York, N.Y. -- Science. 1983 Nov 18;222(4625):823-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11644077" target="_blank"〉PubMed〈/a〉
    Keywords: *DNA, Recombinant ; Ecology ; Federal Government ; Government ; *Government Regulation ; Industry ; Legislation as Topic ; *Social Control, Formal ; *United States Environmental Protection Agency ; genetic engineering. Unlike the Recombinant DNA Advisory Committee of the ; National Institutes of Health, which oversees federally funded researchers, the ; EPA has the power to regulate industry and to concern itself with the health ; risks and environmental impact of commercial ventures. Claiming authority to ; regulate geneticaly engineered pesticides and organisms under the Federal ; Insecticide, Fungicide and Rodenticide Act, and under the Toxic Substances ; Control Act, EPA officials expect industry to contest in court the agency's ; controversial extension of its regulatory powers.
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 15
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1983-07-08
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sun, Marjorie -- New York, N.Y. -- Science. 1983 Jul 8;221(4606):136-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11644007" target="_blank"〉PubMed〈/a〉
    Keywords: *DNA, Recombinant ; Ecology ; *Federal Government ; *Government ; *Government Regulation ; Hazardous Substances ; Public Policy ; *Social Control, Formal ; the topic of a 22 June 1983 hearing held by Representatives Albert Gore and Doug ; Walgren. Scientists testified that potential hazards from the release of rDNA ; organisms into the environment are low, and that voluntary guidelines, like those ; of the National Institutes of Health's Recombinant DNA Advisory Committee, are ; sufficient to control the new technology. Some government officials concur with ; this assessment. Should increased federal oversight be decided upon, it has yet ; to be established whether the Environmental Protection Agency or the Agriculture ; Department has regulatory authority.
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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