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Uslar, Germany

Coring E.,EcoRing | Bathe J.,EcoRing
Limnologica | Year: 2011

The reduction and equalization of the salt concentrations in the River Werra have resulted in a gradual recovery of the aquatic flora. Spatial high-resolution macrophyte mappings document the spread of the aquatic vascular plants in the middle and lower River Werra. Simultaneously, the plankton blooms have declined. Changes in the composition of the algal communities including diatoms also indicated lower salinity. In addition to the salinity, high nutrient concentrations, waste water discharges and structural degradation are important stressors in the River Werra as shown by e.g. low species richness of vascular plants and the common occurrence of pollution tolerant diatoms. From the existing data it is clear that an encompassing improvement of the ecological conditions in the River Werra can only be achieved by further restoration measures considering all stressors. © 2010 Elsevier. Source

The reduction and the smoothened amplitudes of the chloride concentrations since 2000 have resulted in a gradual positive development of the aquatic fauna in the River Werra. In the salinized section of the river increasing species numbers have been determined along the salinity gradient, which shows maximum chloride concentrations of about 2500. mg/l, maximum potash concentrations at approximately 200. mg/l, and magnesia concentrations peaked at 320. mg/l. As an immediate consequence of the reduction in salt concentration the immigration of various caddis fly species into the lower River Werra was observed. The Number of taxa per sample rose from 5 to more than 30 in the lower Werra region. Changes in species-richness could be seen more frequently in river sections where chloride concentrations fluctuated around 1500. mg/l. © 2010 Elsevier. Source

Szocs E.,University of Koblenz-Landau | Coring E.,EcoRing | Bathe J.,EcoRing | Schafer R.B.,University of Koblenz-Landau
Science of the Total Environment | Year: 2013

Salinization of rivers resulting from industrial discharge or road-deicing can adversely affect macroinvertebrates. Trait-based approaches are a promising tool in ecological monitoring and may perform better than taxonomy-based approaches. However only little is known how and which biological traits are affected by salinization. We investigated the effects of anthropogenic salinization on macroinvertebrate communities and biological traits in the Werra River, Germany and compared the taxonomic and trait response.We found a change in macroinvertebrate community and trait composition. Communities at saline sites were characterized by the three exotic species Gammarus tigrinus, Apocorophium lacustre and Potamopyrgus antipodarum. The frequencies of trait modalities long life cycle duration, respiration by gill, ovoviviparity, shredder and multivoltinism were statistically significantly increased at saline sites.The trait-based ordination resulted in a higher explained variance than the taxonomy-based ordination, indicating a better performance of the trait-based approach, resulting in a better discrimination between saline and non-saline sites. Our results are in general agreement with other studies from Europe, indicating a trait convergence for saline streams, being dominated by the traits ovoviviparity and multivoltinism. Three further traits (respiration by gill, life cycle duration and shredders) responded strongly to salinization, but this may primarily be attributed to the dominance of a single invasive species, G. tigrinus, at the saline sites in the Werra River. © 2013 Elsevier B.V. Source

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