| Water category: | River |
| Pressure categories | Nutrients |
| Pressure detail | Assessment as part of the Urban Wastewater Treatment Directive, between upstream and downstream wastewater discharges |
| WFD Indicators- R | Phytoplancton Macrophytes and phytobenthos Composition Abundance |
| Specific Index | Mean Trophic Rank (MTR) |
| Brief text description | Macrophyte index based on the nutrient characteristics of indicator species |
| Long text description | The Mean Trophic Rank has been developed for England and Wales to implement the EC Urban Waste Water Directive: it is used to assess the impact of point sources on the river. It is based on the combination of species at a site and, for each species, its indicator value and its abundance (Holmes et al., 1998, Holmes et al., 1999). 128 species have been identified for this in-dex. They can be split in 4 broad groups and in 10 River Community Types (Holmes et al., 1998). These River Community Types are physically described and the mean MTR value for each of these groups can be used as a reference for physically similar sites. The MTR has been adapted to several countries, including Poland (Szoszkiewicz et al., 2002). MTR = Sum(CVS) / Sum(SCV)*10 where CVS = SCV x STR and where SCV = Species Cover Value (cover class per taxon, on an increasing scale 1-9) STR = Species Trophic Indicator (score assigned to species on a scale 1-10: the higher the score, the lower the tolerance to nutrient enrichment) MTR score Interpretation MTR > 65 Unlikely to be eutrophic * 25 - 65 Site likely to be either eutrophic or at risk of becoming eutrophic ** MTR < 25 Site badly damaged by eutrophication, organic pollution, toxicity or is physi-cally damaged * If the score is less than might be expected for a site of this physical type, the site may be at risk of becoming eutrophic. ** If the score is less than might be expected for a site of this physical type, the site is eutrophic or at risk of becoming eutrophic. |
| History of development | |
| References | "Zelinka, M. and P. Marvan (1961). ""Zur Präzisierung der biologischen Klassifikation des Rheinheit Fliessender Gewässer."" Archiv fur Hydrobiologie 57: 389-407 Holmes, N. T. H., J. R. Newman, et al. (1999). Mean Trophic Rank: A User's manual, Environment Agency: 129. Szoszkiewicz, K., K. Karolewicz, et al. (2002). ""An assessment of the MTR aquatic plant bioindication system for determining the trophic status of Polish rivers."" Polish Journal of Environmental Studies 11(4): 421-427. Holmes, N. T. H., P. J. Boon, et al. (1998). ""A revised classification system for British rivers based on their aquatic plant communities."" Aquatic Conservation: Marine and Freshwater Ecosystems 8(4): 555-578." |
| Geographical region (GIG) - R | RNO Northern RCE - Central+Baltic |
| Ecoregion - LR | 18. Great Britain |
| Country | D Germany B Belgium DK Denmark NL Netherlands P Portugal FIN Finland S Sweden UK United Kingdom BG Bulgaria CY Cyprus CZ Czech Republic EE Estonia HU Hungary LV Latvia LT Lithuania MT Malta PL Poland RO Romania SK Slovakia SI Slovenia TR Turkey NO Norway XX Other country |
| Geographical location of source data | National |
| Reference conditions | Considered |
| Development | Existing |
| Uncertainty | Unknown |
| Link to document store | No |
| BMW Toolbox | No |
| Entry status | Unvalidated |