Potash mining is significantly increasing the salt concentration of rivers and streams due to lixiviates coming from the mine tailings. In the present study, we have focused on the middle Llobregat basin (northeast Spain), where an important potash mining activity exists from the beginning of the XX century. Up to 50 million tonnes of saline waste have been disposed in the area, mainly composed of sodium chloride. We assessed the ecological status of streams adjacent to the mines by studying different physicochemical and hydromorphological variables, as well as aquatic macroinvertebrates. We found extraordinary high values of salinity in the studied streams, reaching conductivities up to 132.4 mS/cm. Salt-polluted streams were characterized by a deterioration of the riparian vegetation and the fluvial habitat. Both macroinvertebrate richness and abundance decreased with increasing salinity. In the most polluted stream only two families of macroinvertebrates were found: Ephydridae and Ceratopogonidae. According to the biotic indices IBMWP and IMMi-T, none of the sites met the requirements of the Water Framework Directive (WFD; i.e., good ecological status). Overall, we can conclude that potash-mining activities have the potential to cause severe ecological damage to their surrounding streams. This is mainly related to an inadequate management of the mine tailings, leading to highly saline runoff and percolates entering surface waters. Thus, we urge water managers and policy makers to take action to prevent, detect and remediate salt pollution of rivers and streams in potash mining areas.

This study aims to contribute to the understanding of the impact of Didymosphenia geminata massive growths upon river ecosystem communities’ composition and functioning. This is the first study to jointly consider the taxonomic composition and functional structure of diatom and macroinvertebrate assemblages in order to determine changes in community structure, and the food web alterations associated with this invasive alga. This study was carried out in the Lumbreras River (Ebro Basin, La Rioja, Northern Spain), which has been affected by a considerable massive growth of D. geminata since 2011. The study shows a profound alteration in both the river community composition and in the food web structure at the sites affected by the massive growth, which is primarily due to the alteration of the environmental conditions, thus demonstrating that D. geminata has an important role as an ecosystem engineer in the river. Thick filamentous mats impede the movement of large invertebrates—especially those that move and feed up on it—and favor small, opportunistic, herbivorous organisms, mainly chironomids, that are capable of moving between filaments and are aided by the absence of large trophic competitors and predators -prey release effect-. Only small predators, such as hydra, are capable of surviving in the new environment, as they are favored by the increase in chironomids, a source of food, and by the reduction in both their own predators and other midge predators -mesopredator release-. This change in the top-down control affects the diatom community, since chironomids may feed on large diatoms, increasing the proportion of small diatoms in the substrate. The survival of small and fast-growing pioneer diatoms is also favored by the mesh of filaments, which offers them a new habitat for colonization. Simultaneously, D. geminata causes a significant reduction in the number of diatoms with similar ecological requirements (those attached to the substrate). Overall, D. geminata creates a community dominated by small organisms that is clearly different from the existing communities in the same stream where there is an absence of massive growths.

The objective of this paper is to determine the alteration of the taxonomic composition and functional structure of macroinvertebrate community associated with a massive growth of the invasive algae Didymosphenia geminata downstream of a mountain reservoir (Pajares Reservoir, La Rioja, Northern Spain). As the massive growth of the alga disappears a few kilometres downstream of the reservoir associated with the input of nutrients from a nearby village sewage, we may compare the community composition between nine stations in three different conditions: three stations heavily affected by the presence of D. geminata, three further downstream stations without the algal massive growth but affected by river regulation and three control stations (unregulated and without the algae). Results show a significant disturbance of the composition and structure of macroinvertebrate community in sites affected by the stream flow regulation downstream of the dam compared with unregulated streams, but the alterations are more dramatic in the area where the growth of D. geminata is massive because of the total substrate occupation by the algal filaments. Scrapers and others invertebrates living on the coarse substrate are especially affected at such sites. Moreover, an important increase in the relative abundance of chironomids is associated with the algal massive growth, especially in case of Eukiefferiella devonica and Cricotopus spp., reducing the assemblage diversity and leading to the taxonomic and functional homogenization of the community. Changes in the reservoir management (such as releasing the water from surface rather than from the hypolimnion) may be useful to control the massive growth of D. geminata and thus reducing the effects of river regulation on macroinvertebrate assemblage composition. Copyright © 2014 John Wiley & Sons, Ltd.

In a recent article, Malaquias et al. (2016) use molecular tools to test the conspecificity of the aglajid sea slug Chelidonura fulvipunctata Baba, 1938 populations from two sites in the Mediterranean (Cyprus, Italy) and the Indo-West Pacific (Mozambique, Lizard Island, Australia, and Marshall Islands). The authors then postulate that the species has entered the Red Sea from the Mediterranean Sea through the Suez Canal, the latter acting as a "revolving door" that can allow species of Indo-Pacific origin to enter the Mediterranean, and species established in the Mediterranean to move into the Red Sea. In this response evidence is offered that questions, if not refutes, the authors' premises. The veracity and accuracy of the geographic origin and the pathways of introduction are of major importance for management of bioinvasions. For appropriate management measures to be prioritized, devised, and implemented, care should be taken to provide scientists, regulators and stakeholders with as accurate information as possible.

36Agricultural intensification during the last century has produced river degradation 37 across Europe. From the wide range of pressures derived from agricultural activities that 38 impact rivers, diffuse agricultural pollution has received most of the attention from 39 managers and scientists. The aim of this study was to determine the main pressures 40 exerted by intensive agriculture around Nitrate Vulnerable Zones (NVZs), which are 41 areas of land that drain into waters polluted by nitrates according to the European 42 Nitrate Directive (91/676/EEC). The study area was located in the NW of La Rioja 43 (Northern Spain), which has the highest levels of nitrate concentrations within the Ebro 44 basin. The relationships between forty environmental variables and the taxonomic and 45 functional characteristics of macroinvertebrate assemblages (which are good indicators 46 of water quality) were analyzed in 11 stream reaches differentially affected by upstream 47 agricultural activity. The streams affected by a high percentage of agricultural area had 48 significantly greater nitrate concentrations and distinct macroinvertebrate assemblages 49 dominated by pollution tolerant taxa. Hydromorphological alteration (i.e. channel 50 simplification, riparian forest degradation and sediment inputs), which is closely linked 51 to agricultural practices, was the main factor affecting macroinvertebrate assemblages. 52 Good agricultural practices should be implemented in streams affected by NVZs to 53 reverse stream degradation, in consonance with the European Water Framework 54 Directive (WFD). Management actions in these areas should not focus exclusively on 55 nitrate reduction, but also on restoring riparian and aquatic habitats.56 Introduction 60 Agriculture is the most widespread form of land-use change [1,2], and it has been 61 identified as the main driver of global biodiversity decline [3] and one of the most 62 important stressors affecting freshwater ecosystems in Europe [4] and around the world 63 [2]. Water quality is strongly affected by agrochemicals, pesticides and nutrients 64 intensively used in productive agriculture [5]. Among them, nitrate is one of the most 65 abundant agrochemical pollutants in waters of rural areas [6], since it is intensively used 66 for plant growth and development [7]. Intensive agriculture not only needs 67 agrochemicals but also important water quantities to increase productivity. This need for 68 water has led to strong river and stream regulation in the last century that has reduced 69 and altered (e.g., inversed) flow [8-10]. Finally, agriculture degrades the fluvial habitat 70 through riparian forest removal, channel incision and rectification, reduction of bank 71 stability and sediment deposition [11]. 72 There is a broad bibliography on the impact of agricultural activity on rivers based on 73 macroinvertebrate assemblage [e.g. 11-17], with different studies specifically assessing 74 the impact of nitrate on macroinvertebrates [see 18,19]. Nitrate impact in rivers 75 comm...