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  • 1
    Electronic Resource
    Electronic Resource
    A simple generalized model of attack by predators and parasites (1986)
    Springer
    Ecological research 1 (1986), S. 141-156 
    Details
    ISSN: 1440-1703
    Keywords: Functional response curve ; Instantaneous rate of attack ; Parasitism ; Predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A generalized descriptive equation for the effect of prey density on the instantaneous rate of attack was proposed; $$A(N_0 ) = \frac{{T_t }}{{t_h + 1/\left[ {a'N_0 \exp (cN_0 )} \right]}}$$ whereA(N o ) is the number of attacks per predator during timeT t ,N o is the prey density,T t is the total time the prey was exposed,T h is the handling time per prey,a′ is the rate of successful search, andc is the facilitation coefficient. The proposed equation can describe all types of the functional response curves; withc=a′ t h (pseudo Type I), withc=0 (Type II), withc〉a′ t h (Type III), and withc〈0 (Type IV). The applicability of the equation was tested against the results of a simulation model and available laboratory and field data on predation. The equation described these data very well and in many cases yielded biologically interesting insights, although the equation was proposed primarily for descriptive purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02347017
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on the biology of Chaoborus flavicans (Meigen) (Diptera: Chaoboridae) in a fish-free eutrophic pond, Japan (1998)
    Springer
    Hydrobiologia 368 (1998), S. 83-90 
    Details
    ISSN: 1573-5117
    Keywords: Chaoborus flavicans ; population dynamics ; planktonic and benthic ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Population dynamics of Chaoborus flavicans larvae of various instars was studied from November 1986 to December 1987 in a eutrophic, fish-free pond, Japan. First and 2nd instar larvae were observed from late April to late October, indicating a reproductive period of about half a year. C. flavicans overwintered in the 4th instar larvae. In water column samples, total density of all instars was 680–23680 m-2, and pupal density 0–2600 m-2; larvae of the 1st, 2nd, and 3rd instars showed 5–6 density peaks in 1987, suggesting that 5–6 generations occur during a year (peaks of the 4th instar larvae were not clear, probably due to their longer development than those of younger instars). In sediment samples, no 1st and 2nd instar larvae were found, 3rd instar larvae were found occasionally but density of the 4th instar larvae was 280–18600 m-2, and pupal density varied between 0–502 m-2. Fouth instar larvae accumulated in sediment in the cold season and in the water column in the warm season; high temperature and low oxygen concentration were the most important factors limiting the distribution of larvae in the sediment in summer in the NIES pond. The dry weight of total C. flavicans larvae was 0.08–4.2 g m-2 in sediment samples and 24–599 µg l-1 (0.10–2.40 g m-2) in water column samples. Comparisons of maximum densities in the NIES pond in different years and in waters of different trophic status show that density is generally higher in eutrophic than in oligotrophic habitats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003217325236
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    Paper (German National Licenses)
    Fulltext
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