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In recent decades, naturally growing mosses have been used successfully as biomonitors of atmospheric deposition of heavy metals and nitrogen. Since 1990, the European moss survey has been repeated at five-yearly intervals. In 2010, the lowest concentrations of metals and nitrogen in mosses were generally found in northern Europe, whereas the highest concentrations were observed in (south-)eastern Europe for metals and the central belt for nitrogen. Averaged across Europe, since 1990, the median concentration in mosses has declined the most for lead (77%), followed by vanadium (55%), cadmium (51%), chromium (43%), zinc (34%), nickel (33%), iron (27%), arsenic (21%, since 1995), mercury (14%, since 1995) and copper (11%). Between 2005 and 2010, the decline ranged from 6% for copper to 36% for lead; for nitrogen the decline was 5%. Despite the Europe-wide decline, no changes or increases have been observed between 2005 and 2010 in some (regions of) countries.

Previous analyses at the European scale have shown that cadmium and lead concentrations in mosses are primarily determined by the total deposition of these metals. Further analyses in the current study show that Spearman rank correlations between the concentration in mosses and the deposition modelled by the European Monitoring and Evaluation Programme (EMEP) are country and metal-specific. Significant positive correlations were found for about two thirds or more of the participating countries in 1990, 1995, 2000 and 2005 (except for Cd in 1990). Correlations were often not significant and sometimes negative in countries where mosses were only sampled in a relatively small number of EMEP grids. Correlations frequently improved when only data for EMEP grids with at least three moss sampling sites per grid were included. It was concluded that spatial patterns and temporal trends agree reasonably well between lead and cadmium concentrations in mosses and modelled atmospheric deposition.

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations (>1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km x 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r2 = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured sitespecific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution.

The usefulness of information gained from investigations of single species for predicting adverse effects of chemical contamination on aquatic ecosystems is discussed in this contribution. The frame for prediction efforts is thereby provided by the type and number of chemicals considered, the time and spatial scale of pollution and the criteria for an assessment. Further, any attempt to predict ecotoxicological effects on the basis of single species observation requires instrumentalisation of current understanding of ecosystems and biological action of compounds for a specific assessment task.Various methods and tools that link chemical and biological types of information specifically to establish a functional relationship between exposure concentration and effect, model biological responses of long-term exposure, identify components of ecotoxicological concern in complex contaminated samples, calculate expected combined effects for mixtures of pollutants, understand modes of ecotoxic action, and predict biological activities from compounds structural properties are reviewed. The methodologies introduced all have their specific drawbacks concerning the scope to assess and predict ecosystem responses. Various approaches addressing extrapolation problems like in situ-toxicity testing, species sensitivity distributions, comparative studies using laboratory assays and micro- and mesocosm studies are additionall considered.It is concluded from the review of current literature that all evidence so far shows, that single species data on the toxicity of pollutants can be used to predict the potential of adverse effects in ecosystems. There is no evidence that complex model ecosystems are systematically more or less sensitive to toxicants than single species tests. Principal limitations for extrapolation emerge when longer time scales are of concern or when structures or processes above the level of populations are affected. Additionally, ecological issues considered from a