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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 100 (1978), S. 1872-1875 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied the effects of grazing by two species of sea urchins on two species of kelp (Macrocystis pyrifera and Pterygophora californica) in the San Onofre kelp bed in southern California from 1978 through 1981. Both red sea urchins, Strongylocentrotus franciscanus, and white sea urchins, Lytechinus anamesus, were abundant and lived in aggregations. The purple sea urchin (S. purpuratus) was rare at the study site and was not studied. The aggregations of red urchins were either relatively small and stationary (for over 3 yr) or relatively large and motile (advancing at about 2 m mo−1). Both stationary and moving aggregations were observed at the same time, and within 100 m of one another. Stationary aggregations of red urchins probably subsisted mainly on drift kelp and had no effect on kelp recruitment or on adult kelp abundance. In contrast, red sea urchins in large, motile aggregations or “fronts” ate almost all the macroalgae in their path. The condition of their gonalds indicated that red urchins in fronts were starved relative to red urchins in the small, stationary aggregations. Large, motile aggregations developed after 2 yr of declining kelp abundance (probably due largely to storms). We propose that a scarcity of drift algae for food results in a change in the behavior pattern of the red urchins and thus leads to the formation of large, motile aggregations. The aggregations of white urchins, which occurred along the offshore margin of the kelp bed, were large, but relatively stationary. The white urchins rarely ate adult kelps, but grazed extensively on early developmental stages of kelps and evidently prevented seaward expansion of the bed. The spatial distribution of both types of red urchin aggregations appeared to be unrelated to predation pressure from fishes or lobsters.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 83 (1984), S. 301-311 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Instantaneous relative growth rates, μ (d-1), were measured for juveniles of the giant kelp Macrocystis pyrifera transplanted to study sites in Southern California kelp forests between 1978 and 1982. Growth rates ranged from negative values (indicating loss of tissue) to 0.03 (doubling of total frond length every 19 d). Multiple regression analysis of growth versus irradiation, temperature, nitrogen concentration and amount of fouling revealed that all these factors had significant effects, together accounting for about 50% of the total variance. Elevated irradiation and nitrogen levels had strongly stimulatory effects (tissue nitrogen may have been more critical than ambient nitrogen for growth), while high temperature and fouling had strongly inhibitory effects. Irradiation was the most important factor influencing growth in 6 of the 8 transplant experiments. During these 6 experiments, the compensating irradiation level (below which there was no growth) was between 0.4 and 0.7 E m-2 d-1, and saturating irradiation was between 2 and 3 E m-2 d-1. During two of the experiments, growth was apparently limited by extremely high temperatures or low nitrogen levels. Quantum irradiation levels in the kelp forest were generally between the compensation and saturation levels. However, irradiation levels occasionally dropped below the compensation point for several months. Irradiation was occasionally low enough to limit the distribution of juvenile kelp by inhibiting growth, especially in the deeper portions of the kelp forest and under dense canopies formed by adult plants.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 93 (1986), S. 17-20 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Laboratory experiments were conducted in 1984 to test for an interaction between irradiance and temperature in controlling sporophyte production in the giant kelp Macrocystis pyrifera. Gametophytes from plants in the San Onofre kelp forest were cultured under a combination of seven irradiance (2.9 to 30 μE m-2 s-1) and ten temperature (11° to 20°C) levels. The minimum daily quantum dose for fertility of female gametophytes during the 42 d culture-period was 0.25 E m-2 d-1. The saturation quantum dose was approximately 0.60 E m-2 d-1. Temperatures between 11° and 20°C had little effect on the fertilityirradiance relationship, except at irradiations near the threshold and saturation levels. Cultures at 0.60 E m-2 d-1 had significantly lower fertility after 6 wk at 20°C than at the lower temperatures and there was a trend toward lower fertility at temperatures greater than 15°C in cultures at 0.25 E m-2 d-1. These differences were also reflected in the development time for female gametophytes. The 11°C cultures reached 50% fertility slightly faster and the 20°C cultures slower than cultures at intermediate temperatures.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 19 (1983), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: A conceptual framework and the systematic collection of reliable information for application within the framework are the cornerstones of effective water planning. The ideal of strengthening these cornerstones was a driving force behind formation of the Water Resources Council and Council efforts, during its life, to develop the Principles and Standards and to complete two National Water Assessments. The Assessments contained voluminous data but never really became an integral component of the national water planning process. Before being disbanded in 1982, the Council solicited several appraisals of its assessment process. This paper reports one made by the university community in which experiences and opinions were obtained from 108 water research administrators and water policy experts.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 21 (1985), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: During the 1976–77 drought, three principal mechanisms were used to reduce water use in Utah communities: price increases, maximum monthly use restrictions, and restrictions on outdoor watering times. A regression model was developed to explain observed changes in water use, with price, type of restriction, household size, and summer rainfall as independent variables. For an average system, a 1 percent increase in price would reduce water use by 0.07 to 0.09 percent. A 1 percent increase in outdoor watering time restriction reduces use by 0.064 to 0.075 percent. A 1 percent increase in quantity restrictions leads to a reduction in water use of 0.014 to 0.054 percent. The effectiveness of rationing policies is influenced by system characteristics. For example, outdoor watering time restrictions were less effective in systems with above average household size and below average monthly use.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Nuclear Physics B (Proceedings Supplements) 23 (1991), S. 227-238 
    ISSN: 0920-5632
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 47 (1982), S. 2679-2681 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 33 (1994), S. 3209-3216 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 32 (1993), S. 273-278 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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