Soil mite communities (Acari: Mesostigmata, Oribatida) as bioindicators for environmental conditions from polluted soils

An anthropic ecosystem from Romania was investigated from acarological, vegetation and chemical point of view. The community structures of two groups of mites were studied (Acari: Mesostigmata, Oribatida) from a tailing pond, using transect method, in correlation with concentrations of heavy metals (As, Cu, Pb, Ni, Mn and Zn), with abiotic factors (altitude, aspect, soil temperature, soil humidity, soil pH) and biotic factor (vegetation coverage). Taking into account the mite communities, in total, 30 mite species were identified, with 1009 individuals and 18 immatures (10 species with 59 individuals, 5 immatures of Mesostigmata and 20 species with 950 individuals, 13 immatures of Oribatida). The investigated habitats from the tailing pond were grouped in five transects, with different degree of pollution, based on total metal loads. Taking into account of the connection between mites communities, abiotic factors and heavy metals, each transect were characterized through specific relationship. Using multivariate statistical analysis, we revealed that the occurrence of some Oribatida species was strongly correlated with vegetation coverage, soil pH and soil humidity, though concentrations of Cu, As, Mn, Ni and Zn also had an influence. Pb and Zn concentrations were shown to influence the occurrence of Mesostigmata mites. The heterogeneity of mites species richness at 2 m(2) scale was correlated with a metric related to the heterogeneity of heavy metals at the same scale.