Comparison of microbial and meiofaunal community analyses for determining impact of heavy metal contamination

The impact of long-term heavy metal contamination on soil communities was a ssessed by a number of methods. These included plate counts of culturable b acteria, community level physiological profiling (CLPP) by analysis of the utilization of multiple carbon sources in BIOLOG plates, community fatty ac id methyl ester (C-FAME) profiling and dehydrogenase enzyme activity measur ements. These approaches were complemented with microscopic assessments of the diversity of the nematode community. Samples from two sites with differ ent histories of heavy-metal input were assessed. Major differences in micr obial and meiofaunal parameters were observed both between and within the s ites. There was a large degree of congruence between each of the microbiolo gical approaches. In particular, one sample appeared to be distinguished by a reduction in culturable bacteria (especially pseudomonads), limited resp onse to carbon sources in CLPP, and major differences in extracted fatty ac id profiles, The use of multivariate analysis to examine the relationship b etween microbial and physicochemical measurements revealed that CLPP and pl ate counts were useful for determining the gross effect of metals on soil m icrobial communities, whereas proportions of metal-resistant bacteria and d ehydrogenase activity differentiated between the two sites. Copper and zinc concentrations and pH ah showed significant correlation with the microbial parameters. Nematode community structure was affected to a greater extent by soil pH than by metal content, but the within-site rankings were the sam e as those achieved for microbiological analyses. The use of these methods for field evaluation of the impact of industrial pollution may be possible provided care is taken when interpreting the data. (C) 2001 Elsevier Scienc e B.V. All rights reserved.