Zinc, among a ?cocktail? of metal pollutants, is responsible for the absence of the terrestrial isopod Porcellio scaber from the vicinity of a primary smelting works

Abstract

: Porcellio scaber Latreille (Crustacea: Isopoda) of one month in age were reared for a year on leaf litter of field maple (Acer campestre) contaminated in the laboratory with a range of concentrations of cadmium, copper, lead or zinc. The metals were applied topically to the leaves as nitrates. Growth and survival, numbers of live offspring produced by females that matured, and concentrations of metals in adult isopods at the end of the experiment were measured.'Critical concentrations' of metals in food at which all the isopods died before producing offspring were 100 μg Cd g(-1), 100 μg Cu g(-1), 2000 μg Pb g(-1) and 1000 μg Zn g(-1) (on a dry weight basis). The relative toxicities of the four metals in the laboratory were compared with concentrations of cadmium, copper, lead and zinc in surface leaf litter in the vicinity of a primary smelting works at Avonmouth, South West England. The results support the hypothesis that the absence of Porcellio scaber from sites in the immediate vicinity of the factory is due to zinc poisoning. Although cadmium is approximately ten times more toxic to isopods than zinc in the laboratory, zinc is most likely to be killing isopods in the field because its concentration is always at least 30 times higher than cadmium in Avonmouth leaf litter, and more than 100 times higher at most sites.Populations of Porcellio scaber survive in field sites where surface leaf litter contains up to 5000 μg Zn g(-1). This is at least five times higher than the 'critical concentration' in laboratory experiments. Thus, the methodology for assessing metal toxicity described in this paper, exaggerates the potential effects of metals to isopods in the field. Such differences between laboratory and field toxicities of metals should be taken into account when environmental protection levels for metals are being proposed for soil invertebrates based on ecotoxicological tests conducted in the laboratory.

White Oak Creek Watershed: Melton Valley Area Remedial Investigation Report, Oak Ridge National Laboratory, Oak Ridge, Tennessee: Volume 3 Appendix C

“…Differences among groups of nematodes in sensitivity to Cu is shown by Parmalee et al (1993). The application of soluble form of Cu to food material by Hopkin and Hames (1994) and Marigomez et al (1986) show very distinct sensitivities of woodlice and slugs to Cu. The lowest toxic concentration reported in these two studies (72 ppm Cu) is higher than the benchmarks for earthworms (50 ppm) and microbes (30 ppm) ( Table 4).…”

Toxicological benchmarks for screening potential contaminants of concern for effects on soil and litter invertebrates and heterotrophic process

“…Differences among groups of nematodes in sensitivity to Cu is shown by Parmalee et al (1993). The application of soluble form of Cu to food material by Hopkin and Hames (1994) and Marigomez et al (1986) show very distinct sensitivities of woodlice and slugs to Cu.…”

“…Adult mites (P. peltifer) fed the same diet for 84 days experienced a 23% reduction in population growth rate at a concentration of 9 ppm Cd, while 3 ppm had no effect. Hopkin and Hames (1994) investigated the effects of Cd (as CdNO ) in food on survival and 3 reproduction of the terrestrial isopod Porcellio scaber. Leaves of field maple (Acer campestre) were sprayed with solutions containing Cd and placed in plastic containers with juvenile woodlice.…”

“…Copper was extracted from the top 10 cm of soil with 0.43 M nitric acid; thus, total concentrations of the metal may be higher than those reported. Hopkin and Hames (1994) investigated the effects of Cu (as CuNO ) in food on survival and 3 reproduction of the terrestrial isopod Porcellio scaber. The experimental design used by the authors is described in the discussion of the effects of Cd on this animal.…”

“…Hopkin and Hames (1994) investigated the effects of Zn (as ZnNO ) in food on survival and 3 reproduction of the terrestrial isopod Porcellio scaber. The experimental design used by the authors is described in the discussion of the effects of Cd on this animal.…”