Nematode diversity and food web condition in heavy metal polluted soils in a river basin in southern Spain

Effects of heavy metal pollution on the nematode community and the soil food web were assessed (June 2000 to February 2002) by using nematode community composition, functional guild abundances and diversity, maturity and soil food web indices in polluted soils in a river basin in southern Spain. Soil content of Pb, Ni, Cu and Zn, soil pH and soil texture were measured in both polluted and non-polluted areas. The composition of the nematode community and diversity indices was strongly affected by heavy metal soil content (especially by Pb, Cu and Zn). Comparing polluted and non-polluted areas, taxonomic diversity was more different between areas than functional indices. While diversity indices were negatively correlated with metal soil pollution until the last sampling date, by the end of the survey (46 months after the pollution incident), as indicated by maturity and food web indices, the functional status of the soil community was nearly recovered. Of the three kinds of indices used (diversity, maturity and soil food web descriptors), the structure index, Margalef's diversity index and the maturity index were detected as the most appropriate indicators of the effect of soil pollution on the nematode community. The usefulness of using different descriptors assessing pollutant effects on soil communities is discussed.