Abstract
Field and laboratory research has repeatedly shown that free-living
soil nematodes differ in their sensitivity to soil pollution. In
this paper, we analyze whether nematode genera proved sensitive or
tolerant toward heavy metals and organic pollutants in six long-term
field experiments. We discuss overlaps between nematode physiological
responses to heavy metals and to organic pollutants, which may explain
why nematodes can exhibit co-tolerance toward several contaminants.
We propose a simple method for separating direct effects of soil
contamination on nematode populations from indirect effects mediated
through the food chain. Finally, we analyze the extent to which nematodes
exhibited consistent responses across the experiments analyzed. Our
results show that (a) indirect effects of pollution were generally
strong; (b) fewer nematode genera were tolerant than sensitive; (c)
many genera, including practically all Adenophorea, exhibited a common
response pattern to contaminants; and (d) several genera of the Secernentea
exhibited differential tolerance toward particular pollutants. We
conclude that bioindication of soil contamination should preferentially
be based on tolerant, and less on sensitive, nematodes. We provide
a list of nematode genera that may potentially serve as differential
bioindicators for specific soil contaminants.
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