Salt pollution of the middle and lower sections of the river Werra (Germany) and its impact on benthic macroinvertebrates

Abstract

a b s t r a c tIn two survey phases (2003 and 2008) organic, nutrient and salt contamination parameters have been investigated in the lower Werra in order to estimate the importance of these different kinds of pollution for the quality component of macroinvertebrates according to the European Water Framework Directive. The chemical and biological investigations have been carried out comparing a "reference" section without salt contamination with the salt contaminated section due to the potash mining industry from Vacha to Hannoversch Münden close to the mouth of the Werra. The results show that the drastic differences between the macroinvertebrate assemblages of the Werra upstream and downstream the salt contaminated sections are clearly caused by the salt load. The other kinds of chemical impacts are not responsible for the observed fundamental change within the composition of the benthic invertebrate assemblage. General degradation of stream morphology, indicated by macroinvertebrates, shows a good ecological status for the non-salt-contaminated part of the river and a bad status for the salt contaminated sites of the lower Werra.

Impact of potash mining in streams: the Llobregat basin (northeast Spain) as a case study

“…These findings align with those of previous studies, which reported that biological quality of salt polluted streams can be affected by conductivities as low as 1.5 mS cm -1 (Dunlop et al, 2005;Hart et al, 1991;Horrigan et al, 2005;Kefford et al, 2011), or even lower (Cormier et al, 2013;Kefford et al, 2011). Anyhow, the damage to the aquatic invertebrate community can be expected to increase with increasing conductivity (Berezina, 2003;Böhme, 2011;Braukmann and Böhme, 2011;Cañedo-Argüelles et al, 2012;Hart et al, 1991;Horrigan et al, 2005;Pinder et al, 2005;Piscart, 2005;Williams et al, 1999). It is important to notice the reduction in EPT taxa at sites P3 and P4, and IMMi-L, Iberian Mediterranean Multimetric Index, using qualitative data (Munné and Prat, 2009); IMMi-T, Iberian Mediterranean Multimetric Index, using quantitative data (Munné and Prat, 2009).…”

“…Salt pollution also had clear effects on the aquatic macroinvertebrate communities, as had been previously reported for streams affected by potash mining in the Werra River basin (Bäthe and Coring, 2011;Braukmann and Böhme, 2011) and for the Llobregat River (Prat et al, 1983;Prat and Rieradevall, 2006). Taxa richness strongly responded to salinization, with only 7 taxa being registered in site P4 (conductivity=11.0 mS cm -1…”

“…The conductivities registered in these streams are even higher than those reported in other potash mining areas. For example, in the Werra River (Germany) conductivities in salt polluted areas ranged from 0.46 to 7.24 mS cm -1 (Braukmann and Böhme, 2011). Additionally, according to Spanish law (ORDEN ARM/2656, the conductivity values registered in all the studied streams (except for P1) exceed the limit established for good water quality (1.5 mS cm -1…”

“…Secondary salinization has many different causes, with agriculture and mining being the most important (Cañedo-Argüelles et al, 2013). One of the mining activities directly related to freshwater salinization is potash mining, which has been especially intense in some European regions as the Werra Basin in Germany (Bäthe and Coring, 2011;Braukmann and Böhme, 2011) or the Llobregat Basin in Spain (Gorostiza, 2014). Here we focus on the latter to assess the potential impact of potash mining on the biological quality of rivers and streams.…”

Effects of salinity gradients on benthic invertebrate and diatom communities in a German lowland river

“…Beside an increased osmotic stress directly determining the viability of populations, stress induced responses of aquatic organisms include shifts in feeding type composition (Kefford et al, 2012), the impediment of growth (Roller and Stickle, 1985), as well as the impairment of different stages within the insect live cycle such as oviposition, pupation and emergence (Piscart et al, 2006). Moreover, salinization was found to enhance the establishment of exotic invasive species (Piscart et al, 2005b;Braukmann and Böhme, 2011), with brackish water species (i.e. osmoregulators) colonizing freshwater ecosystems.…”