Detection of stress on macrozoobenthos: evaluation of some methods in a costal mediterranean lagoon

The effects of taxonomic aggregation, the ABC-technique and meta-analysis approaches were tested along a known stress gradient in the Orbetello lagoon, a Mediterranean coastal brackish basin. Multivariate analyses of taxonomic aggregated data detected differences among the three sampled areas, except biomass phylum data analyses which showed a marked loss of information. ABC curves did not succeed in differentiating stress levels at various sites of the Orbetello lagoon. This was mainly due to species distribution, which did not follow the ABC criteria (a decrease in the body size with increasing stress level) in this lagoon. Phylum-level meta-analysis exhibited some, but not all, results consistent with the ordination models. Hence, new methods to achieve a reliable stress classification appear to be necessary in such habitats.