Bioindicators and Biomarkers in the Assessment of Soil Toxicity - Soil Contamination - page 149

(Schultz, 1982). Terrestrial isopods have already been used in toxicity tests of soil and the
main parameters of evaluation were abundance of individuals (Faulkner & Lochmiller,
2000), reproduction rates (Niemeyer et al., 2009) and survival (Stanek et al., 2006).
Metals are the main toxic agents evaluated using Isopoda, since these invertebrates
bioaccumulate these elements. In this sense, researchers have carried out studies on
bioaccumulation (Blanusa et al., 2002; Hopkin et al., 1993), the cytotoxic effect of metals
(Köhler et al., 1996a; Odendaal & Reinecke, 2003) and the detoxification mechanisms (Hopkin,
1990; Köhler & Triebskorn, 1998) and the terrestrial isopod Porcellio scaber is the most studied.
The importance of diplopods in the recycling of nutrients, aeration and fertilization of soil is
frequently mentioned in the literature (Dangerfield & Telford, 1989). Due to the habits of the
diplopods, colonizers of various soil layers, these animals can be greatly influenced by the
deposition of metals, organic compounds and complex substances in the soil.
Most studies in the literature using diplopods as bioindicators of the soil are related to
metals. However, the effect of organic pollutants and complex mixtures on these
invertebrates is relatively little known (Souza & Fontanetti, 2011). In this context, the first
study carried out with diplopods, as possible bioindicators, was conducted by Hopkin et al.
(1985), involving the assimilation of metals by the species Glomeris marginata . In this study, it
was verified a higher uptake of copper, zinc and cadmium by the animals collected in soils
contaminated when compared to those animals collected in non-contaminated
environments. The authors comment that ultrastructural studies of different organs would
be necessary to understand the “metals path”, particularly in the gut of these invertebrates.
Later, Triebskorn et al. (1991) exposed several invertebrates such as mites, insects and
diplopods to different toxic substances and used the ultrastructural analysis in order to
demonstrate the applicability of using such animals in biomonitoring. In the study carried
out by Köhler et al. (1992), it was analyzed the impact of lead on the efficiency of
assimilation in diplpods, submitted to different environmental conditions. The researchers
used different species of diplopods and found that only Glomeris conspersa increased the
ingestion of food containing lead when compared to a non-contaminated diet.
Recently, the toxicity assessment of complex substances was performed with the Brazilian
species Rhinocricus padbergi (figure 2) exposed to different concentrations of sewage sludge
(Godoy & Fontanetti, 2010; Nogarol & Fontanetti, 2010, 2011; Perez & Fontanetti, 2011a) and
landfarming (Souza & Fontanetti, 2011; Souza et al., 2011). The histological and
histochemical analysis, as well as the ultrastructural analysis, showed that such substances
are toxic to the diplopod studied, since different tissular and cellular alterations were
observed in the midgut and perivisceral fat body of these invertebrates.
Fig. 2. Diplopod Rhinocricus padbergi . (Photo: Larissa Rosa Nogarol and Raphael Bastão de
Souza)