Carlos Alonso

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.

European Turtle Dove Streptopelia turtur diet composition in Southern Spain: the role of wild seeds in Mediterranean forest areas

ABSTRACT Capsule: The diet of European Turtle Doves Streptopelia turtur in Mediterranean forest contained a large volume of wild plant seed but from a small number of key species. Aims: To determine which seed species are consumed by Turtle Doves in Mediterranean forest areas. Methods: Digestive tract contents were identified and evaluated for 222 Turtle Doves shot by hunters during three consecutive years. Results: Thirty seed species were identified in the diet, but only a few species represented most of the volume and frequency. Wild plant seeds appeared in 65.8% of digestive tracts and showed significant variation between years. Although the main wild seed species consumed each year varied annually, certain species were found in the diet every year in high volume and frequency. Adults showed a more diverse and numerous consumption of wild seeds than did juveniles. Plastic granules were also found in 3.8% of individuals. Conclusion: A greater number of wild seed species was found in the diet in contrast to previous studies performed in farmland. Echium plantagineum and Amaranthus deflexus could be important seed sources for Turtle Doves in Mediterranean forest. Additionally, the herbaceous species found in the diet whose seeds ripen earlier in the season might play an important role in Turtle Dove reproductive performance, since they are frequently the only available food in the first half of the breeding season.

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.

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.

Support Vector Machines of Interval-based Features for Time Series Classification

In previous works, a time series classification system has been presented. It is based on boosting very simple classifiers, formed only by one literal. The used literals are based on temporal intervals.

The Environmental Costs of Water Flow Regulation: an Innovative Approach Based on the ‘Polluter Pays’ Principle

The EU Water Framework Directive (WFD) explicitly requires the full cost recovery of water services, including the environmental costs incurred from the damage that water uses inflict on the environment. Although flow regulation by river damming is one of the most prominent human impact on fresh water ecosystems its environmental costs are not properly included in water pricing. This paper presents a novel approach to assessing the environmental costs of flow regulation based on the polluter-pays principle. The methodology includes three steps: (i) assessing the admissible range of regulated flow variability, derived from the natural flow regime variability, (ii) estimating the daily environmental impact of regulated flows according to deviations from the admissible range of flow variability, and (iii) calculating the environmental costs of flow regulation. The procedure is applied to four river case studies in Spain, UK and Norway. The advantages over other water cost valuation methods are discussed. The methodology enlarges the current recognition of environmental costs of water use and represents a practical management tool within the WFD context, encouraging transparency and stakeholder communication.