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  • Digitale Medien  (12)
  • 1985-1989  (10)
  • 1975-1979  (1)
  • 1930-1934  (1)
  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Experimental and applied acarology 5 (1988), S. 151-162 
    ISSN: 1572-9702
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The influence of maternal age on primary sex ratio was determined forTetranychus urticae, T. pacificus andT. turkestani (Acari:Tetranychidae). All females were allowed to mate once.Tetranychus urticae had the highest production of daughters and the lowest production of sons. The sex ratio ofT. urticae was nearly 2∶1 (daughters∶sons), whereas for the other species it was 0.6∶1. Net sex ratios were all shifted in favor of daughters, suggesting that most son-production occurs late in life. Demographic techniques are applied to tetranychid populations, including the concepts of reproductive concentration curves and expectation of future reproduction based on age and previous offspring.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Environmental monitoring and assessment 11 (1988), S. 147-169 
    ISSN: 1573-2959
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract In earlier work, we found that leeches from an industrially polluted creek bioaccumulated chlorophenols to much higher concentrations than other resident benthic invertebrates and fish. We suggested that leeches may have significant potential as biomonitors for these and other organic contaminants in the environment. In this study, we compared the bioaccumulation and depuration of 16 organic compounds, including eight chlorophenols (CPs), lindane, DDT and four derivatives, benzothiazole (BT) and 2-(Methylthio)benzothiazole (MMBT) for three species of leeches. Dina dubia had the highest bioaccumulation capacity for most contaminants, but residues persisted longest in Erpobdella punctata. Helobdella stagnalis appeared capable of degrading some compounds. Half lives of CPs, DDT and DDT derivatives were generally longer than one month. In contrast, half lives were only 1 day for lindane, 1–2.5 days for MMBT and 7 days for BT despite very high initial tissue concentrations of the latter two compounds. Bioconcentration factors for contaminants in leeches were higher than those reported for other aquatic organisms. Half lives for lindane, DDT and DDT derivatives were consistent with the literature for other organisms, but half lives for CPs were much longer. The results suggest that leeches would be excellent biomonitors of both continuous and intermittent contamination of a waterway with CPs and DDT, as they retain these compounds for long periods after exposure. Their usefulness as a screening tool for lindane and benzothiazoles would be limited to chronically contaminated environments.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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