Diego García de Jalón

River restoration in Spain: theoretical and practical approach in the context of the European water framework directive.

River restoration is becoming a priority in many countries because of increasing the awareness of environmental degradation. In Europe, the EU Water Framework Directive (WFD) has significantly reinforced river restoration, encouraging the improvement of ecological status for water bodies. To fulfill the WFD requirements, the Spanish Ministry of the Environment developed in 2006 a National Strategy for River Restoration whose design and implementation are described in this paper. At the same time many restoration projects have been conducted, and sixty of them have been evaluated in terms of stated objectives and pressures and implemented restoration measures. Riparian vegetation enhancement, weir removal and fish passes were the most frequently implemented restoration measures, although the greatest pressures came from hydrologic alteration caused by flow regulation for irrigation purposes. Water deficits in quantity and quality associated with uncontrolled water demands seriously affect Mediterranean rivers and represent the main constraint to achieving good ecological status of Spanish rivers, most of them intensively regulated. Proper environmental allocation of in-stream flows would need deep restrictions in agricultural water use which seem to be of very difficult social acceptance. This situation highlights the need to integrate land-use and rural development policies with water resources and river management, and identifies additional difficulties in achieving the WFD objectives and good ecological status of rivers in Mediterranean countries.

Descriptions of four larvae of Rhyacophila (Pararhyacophila) from the Lozoya river, central Spain, and key to the species of the Iberian peninsula (Trichoptera: Rhyacophilidae)

Abstract The full‐grown larvae of Rh. (Pararhyacophila) lusitanica, munda, pulchra and terpsichore are described and illustrated. According to the results, the authors consider that the use of larval morphological characters would require some corrections to Schmids vulgaris group phylogenetic tree. The paper finishes with a key to the larvae of the species of Pararhyacophila so far known from the Iberian peninsula.

Fuzzy cognitive mapping for predicting hydromorphological responses to multiple pressures in rivers.

Summary 1. Different pressures often co-occur in rivers and act simultaneously on important processes and variables. This complicates the diagnosis of hydromorphological alterations and hampers the design of effective restoration measures. 2. Here, we present a conceptual meta-analysis that aims at identifying the most relevant hydromorphological processes and variables controlling ecological degradation and restoration. For that purpose, we used fuzzy cognitive mapping based on conceptual schemes that were created according to 675 scientific peer-reviewed river hydromorphology studies. 3. A model generated from this approach predicts responses that are consistent with common understanding of the direct interactions between hydromorphological pressures, processes and variables. However, it also leads to new knowledge beyond traditional hydromorphological models by dealing with the complex interactions of hydromorphology, vegetation, water chemistry and thermal regime. 4. Water flow dynamics appeared as the most important of all hydromorphological processes affected by simultaneously interacting pressures. Relevant processes such as vegetation encroachment and sediment entrainment are closely linked to water flow. 5. Synthesis and applications. Our results demonstrate the relevance of natural flow regime rehabilitation for river management. Hence, we suggest focusing primarily on rehabilitating the natural flow regime before carrying out extensive habitat restoration works. This challenging target in river rehabilitation could strongly increase the success of additional habitat restoration.

Assessing the influence of altitude and temperature on biological monitoring of freshwater quality: A preliminary investigation

The effect of altitude and water temperature on biomonitoring of freshwater quality was examined along an unpolluted area (36 km in length) of the upper Río Tajo (central Spain). The macrobenthic and fish communities were studied, and the Biological Monitoring Water Quality (BMWQ) method was applied. As expected, values of altitude and temperature respectively decreased and increased with increasing distance from the river source; these two physical parameters exhibited a negative and significant (P<0.05) correlation coefficient between them. However, despite evident changes in the functional structure of both aquatic communities along the study area, BMWQ scores were similar at all sampling sites. Pearson correlation coefficients between physical and biological parameters were not significant (P>0.05). The BMWQ index only exhibited significant (positive) correlation coefficients with macrobenthic and fish biomasses, indicating that freshwater quality could affect the biological production of fluvial ecosystems. It is concluded that biomonitoring of freshwater quality may be independent of the influence of altitude and water temperature at local spatial scales. Nonetheless, further investigations would be needed to clearly differentiate between the effects of anthropogenic and natural causes on biological monitoring at larger spatial scales.

New Ephemerellidae from Spain (Ephemeroptera)

Abstract The nymphal descriptions of four species of Ephemerellidae from Spain are given. The genera Serratella Edmunds and Drunella Needham are cited for the first time in the Paleartic Region. The paper includes a key to the Iberian Ephemerellidae species.

Structural and Trophic Changes in a Riverine Macrobenthic Community Following Impoundment for Hydroelectric Power Generation

ABSTRACT Structural and trophic changes in a benthic macroinvertebrate community downriver from Valparaiso Reservoir (northwestern Spain) were compared before (1986) and after (1990–1991) the creation of that hydropower impoundment. The number of taxonomic groups, total biomass and total density significantly declined under the influence of the new flow regulation, with scrapers (as relative density) being the functional feeding group most adversely affected. The environmental impact decreased with time after the construction of the dam Taxonomic richness and diversity of predators appeared to be the most sensitive biological indicators of the progressive recovery of the macrobenthic community.

Challenges to barbel population resilience due to hydrological alteration

ABSTRACT This study aims to evaluate how the habitat of the Iberian barbel (Luciobarbus bocagei) has changed over the last nine decades in a reach of the River Duero in Toro (Zamora). The available physical habitat through different streamflows was quantified as the wetted area potentially usable by adult barbel with maximum preference (weighted usable area [WUA]). Historical time series of streamflows were used to generate a time series of habitat. Flow data were studied from 1912 to 2008, period being divided into three sub-periods. The sub-period 1912–1931 was considered as a natural regime of reference, and sub-periods 1942–1980 and 1981–2008 were altered. Data from 1931 to 1942 were missing. Uniform continuous under-threshold (UCUT) curves were developed for a set of WUA thresholds from 20% to 75% maximum WUA in the three different sub-periods. As Iberian barbels life- history traits determine that habitat conditions become limiting during summer season, we have drawn UCUT curves using the values from July to September. In order to quantify the challenges to population resilience due to changes in habitat availability, an index of population fatigue was proposed (analogous to materials fatigue), which compares altered periods to natural one. This index was defined by the difference between the area that the UCUT curves in the altered and natural periods draw for each defined threshold and it is measured in days under thresholds. The index of population fatigue is calculated as an extension of Parasiewicz et al.’s (2012) concept of habitat stress days alteration, the HSDA, into an integrated HSDA (IHSDA). The greater the index value, the greater the alteration suffered. Results showed an increasing loss of habitat availability for common events related to natural conditions: 10 days for the first altered sub-period that became more evident (up to 18 days) in the last sub-period.

Description of Athripsodes verai sp. n. (Trichoptera, Leptoceridae) from Spain

A new Spanish A thripsodes (Trichoptera), A. verai sp. n., is described and figures of the male genitalia are given.

A graphical approach to characterize sub-daily flow regimes and evaluate its alterations due to hydropeaking

Most flow regime characterizations focus on long time scale flow patterns, which are not precise enough to capture key components of short-term flow fluctuations. Recent proposed methods describing sub-daily flow fluctuations are focused on limited components of the flow regime being unable to fully represent it, or on the identification of peaking events based on subjectively defined thresholds, being unsuitable for evaluations of short-term flow regime alterations through comparisons between regulated and free-flowing rivers. This study aims to launch an innovative approach based on the visual display of quantitative information to address the challenge of the short-term hydrologic characterization and evaluation of alteration resulting from hydropeaking. We propose a graphical method to represent a discrete set of ecologically relevant indices that characterize and evaluate the alteration of sub-daily flow regimes. The frequency of occurrence of classified values of a descriptive hydrological variable is represented in a map-like graph where longitude, latitude and altitude represent the Julian day, the value of the variable and the frequency of occurrence, respectively. Subsequently, we tested the method on several rivers, both free-flowing and subjected to hydropower production. The advantages of our approach compared to other analytical methods are: (i) it displays a great amount of information without oversimplification; (ii) it takes into account changes in the intensity, timing and frequency of the sub-daily flows, without needing a priori defined thresholds to identify hydropeaking events; and (iii) it supports the Water Framework Directive goal. Specifically, results from applications of our graphical method agree with Sauterleute and Charmasson (2014) analytical method.

Longitudinal connectivity loss in a riverine network: accounting for the likelihood of upstream and downstream movement across dams

Disruption of longitudinal connectivity is a major concern in most of the world´s rivers. Approaches based on graph theory have proven to be a suitable tool for analysing functional connectivity. However, previous applications of graph-based connectivity methods to river systems have been oversimplified in that they have treated potential barriers as binary features and rivers as symmetric networks. We here apply a network analytical approach in which (a) upstream and downstream connectivity are considered so that fish passability values across dams are asymmetrical, and (b) it is possible to consider a continuous range of passability values for every dam. We build on previous and widely used connectivity metrics (Probability of Connectivity, PC), which here are generalised and adapted toward that end. We compare the results of our approach with those that would be obtained under the more simplified assumptions of symmetric movement and of barriers as binary features. We want to prove if there are substantial differences between considering or not the asymmetry in river networks. The application of symmetrical and asymmetrical PC highlights major differences between the upstream connectivity versus the downstream connectivity. We provide our methods in a free software package so that they can be used in any other application to riverscapes. We expect to provide a better graph-based approach for the prioritisation of the removal or permeabilization of artificial obstacles as well as for the preservation of target river segments for connectivity conservation and restoration.