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Following the development of aquatic pollution monitoring techniques using metazoan meiofauna (microscopic interstitial invertebrates), the value of this group in the assessment of contaminated terrestrial sites has been investigated. Communities present in a former explosives burning ground were sampled at 30 sites using coring techniques and examined in the laboratory. Nematoda were numerically dominant at each of the sites and were the most diverse invertebrate group present (60 species). Structurally modified assemblages of these were identified and correlated significantly with elevated soil heavy metal concentrations. Assemblages associated with elevated metal concentrations exhibited increased dominance and reduced species richness. Using principal components analyses (PCA) and redundancy analyses (RA), the relationships between individual species, the metals, and the structures of the nematode communities were described. Tolerant and resistant species were also identified. It is concluded that the technique is a valuable method of assessing metal contamination status, and it is recommended that further studies be made of sites contaminated with organic materials.

From 1989–1992, at quarterly intervals, the National Rivers Authority (NRA) (Thames Region) Thames Estuary Benthic Programme sampled 28 sites within the estuary for benthic macroinvertebrates; meiofauna samples were also taken for the first year. At one subtidal site, situated off Canvey Island, over 200 invertebrate species over the survey period from a sample area of 4·4 m2 were recorded. This species richness was far higher than surrounding sites, including those further out into the North Sea. The most important groups at this site were Nematoda (77 spp.), Crustacea (46 spp.) and Polychaeta (40 spp.) and a species capture curve for macroinvertebrates continued to rise after 44 day grabs. The mean biomass of the site (248 g wet weight /m2) was 20 times that of any other site in the outer estuary. The substratum at the site was highly heterogeneous, yet comparatively stable due to its situation at the base (>20 m depth) of a man-made shipping channel, the provision of a large number of niches perhaps explaining the high biodiversity. The anthropogenic influence on a naturally low biodiversity area emphasises the importance of these ecosystems when considering the conservation of global biodiversity. Methods to determine the relative importance of ecosystems are discussed.

The effect of long-term heavy-metal contamination on soil microbial and meiofaunal communities was assessed with a view to determining whether analysis of these communities could be used for ecological assessment of contaminated sites. Thirty soil cores were taken from an industrial site formerly used for the burning of waste from an explosives factory. The predominant contaminants in the soil were a range of heavy metals, including lead, copper and zinc. The numbers of culturable bacteria (especially those grown on Pseudomonas selective media) and the microbial community response to a suite of 95 carbon sources were suppressed in samples with high heavy-metal contamination. This corresponded to a reduction in the density and evenness of the nematode communities in the samples with high metal concentrations. Conversely the bacterial counts and responses to the 95 carbon sources were greater at sites with higher and more diverse populations of nematodes. However, epifluorescence counts of bacteria and the profiles of extracted fatty acids were not consistently altered by the heavy-metal contamination. These results suggest that culturable bacteria are effective indicators of pollution in soil, and reflect the perturbations seen in other components of the soil biota. Furthermore, this is the first study to show that both meiofaunal communities and microbial communities give similar indications of the ecological impact of heavy-metal contamination in soil.

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