Francisco Martínez-Capel

Patterns of presence and concentration of pesticides in fish and waters of the Júcar River (Eastern Spain).

The Júcar River, in a typical Mediterranean Basin, is expected to suffer a decline in water quality and quantity as a consequence of the climate change. This study is focused on the presence and distribution of pesticides in water and fish, using the first extensive optimization and application of the QuEChERS method to determine pesticides in freshwater fish. Majority pesticides in water - in terms of presence and concentration - were dichlofenthion, chlorfenvinphos, imazalil, pyriproxyfen and prochloraz (associated with a frequent use in farming activities), as well as buprofezin, chlorpyriphos and hexythiazox. In fish, the main compounds were azinphos-ethyl, chlorpyriphos, diazinon, dimethoate and ethion. The analysis of bio-concentration in fish indicated differences by species. The maximum average concentration was detected in European eel (a critically endangered fish species). The wide presence of pesticides in water and fish suggests potential severe effects on fish populations and other biota in future scenarios of climate change, in a river basin with several endemic and endangered fish species. The potential effects of pesticides in combination with multiple stressors require further research to prioritize the management of specific chemicals and suggest effective restoration actions at the basin scale.

Assessment of brown trout habitat suitability in the Jucar River Basin (SPAIN): Comparison of data-driven approaches with fuzzy-logic models and univariate suitability curves

The implementation of the Water Framework Directive implies the determination of an environmental flow (E-flow) in each running water body. In Spain, many of the minimum flow assessments were determined with the physical habitat simulation system based on univariate habitat suitability curves. Multivariate habitat suitability models, widely applied in habitat assessment, are potentially more accurate than univariate suitability models. This article analyses the microhabitat selection by medium-sized (10-20 cm) brown trout (Salmo trutta fario) in three streams of the Jucar River Basin District (eastern Iberian Peninsula). The data were collected with an equal effort sampling approach. Univariate habitat suitability curves were built with a data-driven process for depth, mean velocity and substrate classes; three types of data-driven fuzzy models were generated with the FISH software: two models of presence-absence and a model of abundance. FISH applies a hill-climbing algorithm to optimize the fuzzy rules. A hydraulic model was calibrated with the tool River-2D in a segment of the Cabriel River (Jucar River Basin). The fuzzy-logic models and three methods to produce a suitability index from the three univariate curves were applied to evaluate the river habitat in the tool CASiMiR©. The comparison of results was based on the spatial arrangement of habitat suitability and the curves of weighted usable area versus discharge. The differences were relevant in different aspects, e.g. in the estimated minimum environmental flow according to the Spanish legal norm for hydrological planning. This work demonstrates the impact of the models selection on the habitat suitability modelling and the assessment of environmental flows, based on an objective data-driven procedure; the conclusions are important for the water management in the Jucar River Basin and other river systems in Europe, where the environmental flows are a keystone for the achievement of the goals established in the European Water Framework Directive.

Potential impacts of climate change on flow regime and fish habitat in mountain rivers of the south-western Balkans

The climate change in the Mediterranean area is expected to have significant impacts on the aquatic ecosystems and particular in the mountain rivers and streams that often host important species such as the Salmo farioides, Karaman 1938. These impacts will most possibly affect the habitat availability for various aquatic species resulting to an essential alteration of the water requirements, either for dams or other water abstractions, in order to maintain the essential levels of ecological flow for the rivers. The main scope of this study was to assess potential climate change impacts on the hydrological patterns and typical biota for a south-western Balkan mountain river, the Acheloos. The altered flow regimes under different emission scenarios of the Intergovernmental Panel on Climate Change (IPCC) were estimated using a hydrological model and based on regional climate simulations over the study area. The Indicators of Hydrologic Alteration (IHA) methodology was then used to assess the potential streamflow alterations in the studied river due to predicted climate change conditions. A fish habitat simulation method integrating univariate habitat suitability curves and hydraulic modeling techniques were used to assess the impacts on the relationships between the aquatic biota and hydrological status utilizing a sentinel species, the West Balkan trout. The most prominent effects of the climate change scenarios depict severe flow reductions that are likely to occur especially during the summer flows, changing the duration and depressing the magnitude of the natural low flow conditions. Weighted Usable Area-flow curves indicated the limitation of suitable habitat for the native trout. Finally, this preliminary application highlighted the potential of science-based hydrological and habitat simulation approaches that are relevant to both biological quality elements (fish) and current EU Water policy to serve as efficient tools for the estimation of possible climate change impacts on the south-western Balkan river ecosystems.

Random forests to evaluate biotic interactions in fish distribution models

Previous research indicated that high predictive performance in species distribution modelling can be obtained by combining both biotic and abiotic habitat variables. However, models developed for fish often only address physical habitat characteristics, thus omitting potentially important biotic factors. Therefore, we assessed the impact of biotic variables on fish habitat preferences in four selected stretches of the upper Cabriel River (E Spain). The occurrence of Squalius pyrenaicus and Luciobarbus guiraonis was related to environmental variables describing biotic interactions (inferred by relationships among fish abundances) and channel hydro-morphological characteristics. Random Forests (RF) models were trained and then validated using independent datasets. To build RF models, the conditional variable importance was used together with the model improvement ratio technique. The procedure showed effectiveness in identifying a parsimonious set of not correlated variables, which minimize noise and improve model performance in both training and validation phases. Water depth, channel width, fine substrate and water-surface gradient were selected as most important habitat variables for both fish. Results showed clear habitat overlapping between fish species and suggest that competition is not a strong factor in the study area. We modeled fish distribution at the mesohabitat scale using Random Forests (RF).We evaluated the effect of interspecific interactions on fish habitat use.RF models are validated using an independent dataset and showed high performance.Results showed a clear habitat overlapping between fish species.Fish interspecific competition seems to be a negligible factor for habitat use.

Application of Probabilistic Neural Networks to microhabitat suitability modelling for adult brown trout (Salmo trutta L.) in Iberian rivers

Probabilistic Neural Networks (PNN) have been tested for the first time in microhabitat suitability modelling for adult brown trout (Salmo trutta L.). The impact of data prevalence on PNN was studied. The PNN were evaluated in an independent river and the applicability of PNN to assess the environmental flow was analysed. Prevalence did not affect significantly the results. However PNN presented some limitations regarding the output range. Our results agreed previous studies because trout preferred deep microhabitats with medium-to-coarse substrate whereas velocity showed a wider suitable range. The 0.5 prevalence PNN showed similar classificatory capability than the 0.06 prevalence counterpart and the outputs covered the whole feasible range (from 0 to 1), but the 0.06 prevalence PNN showed higher generalisation because it performed better in the evaluation and it allowed a better modulation of the environmental flow. PNN has demonstrated to be a tool to be into consideration.

Modelling native fish richness to evaluate the effects of hydromorphological changes and river restoration (Júcar River Basin, Spain)

The richness of native fish is considered to be an indicator of aquatic ecosystem health, and improving richness is a key goal in the management of river ecosystems. An artificial neural network (ANN) model based on field data from 90 sample sites distributed throughout the Júcar River Basin District was developed to predict the native fish species richness (NFSR). The Levenberg-Marquardt learning algorithm was used for model training. When constructing the model, we tried different numbers of neurons (hidden layers), compared different transfer functions, and tried different k values (from 3 to 10) in the k-fold cross-validation method. This process and the final selection of key variables with relevant ecological meaning support the reliability and robustness of the final ANN model. The partial derivatives method was applied to determine the relative importance of input environmental variables. The final ANN model combined variables describing riparian quality, water quality, and physical habitat and helped identify the primary drivers of the NFSR patterns in Mediterranean rivers. In the second part of the study, the model was used to evaluate the effectiveness of two restoration actions in the Júcar River: the removal of two abandoned weirs and the progressive increase in the proportion of riffles. The model indicated that the combination of these actions produced a rise in NFSR, which ultimately reached the maximum values observed in the reference site of that river ecotype (sensu the European Water Framework Directive). The results demonstrate the importance of longitudinal connectivity and riffle proportion for improving NFSR and the power of ANNs to help decisions in the management and ecological restoration of Mediterranean rivers. Furthermore, this model at the basin scale is the first step for further research on the effects of water scarcity and global change on Mediterranean fish communities.

Integrating water management, habitat modelling and water quality at the basin scale and environmental flow assessment: case study of the Tormes River, Spain

Abstract Multidisciplinary models are useful for integrating different disciplines when addressing water planning and management problems. We combine water resources management, water quality and habitat analysis tools that were developed with the decision support system AQUATOOL at the basin scale. The water management model solves the allocation problem through network flow optimization and considers the environmental flows in some river stretches. Once volumes and flows are estimated, the water quality model is applied. Furthermore, the flows are evaluated from an ecological perspective using time series of aquatic species habitat indicators. This approach was applied in the Tormes River Water System, where agricultural demands jeopardize the environmental needs of the river ecosystem. Additionally, water quality problems in the lower part of the river result from wastewater loading and agricultural pollution. Our methodological framework can be used to define water management rules that maintain water supply, aquatic ecosystem and legal standards of water quality. The integration of ecological and water management criteria in a software platform with objective criteria and heuristic optimization procedures allows realistic assessment and application of environmental flows to be made. Here, we improve the general methodological framework by assessing the hydrological alteration of selected environmental flow regime scenarios. Editor D. Koutsoyiannis; Guest editor M. Acreman Citation Paredes-Arquiola, J., Solera, A., Martinez-Capel, F., Momblanch, A., and Andreu, J., 2014. Integrating water management, habitat modelling and water quality at the basin scale and environmental flow assessment: case study of the Tormes River, Spain. Hydrological Sciences Journal, 59 (3–4), 878–889.

Comparing four methods for decision-tree induction: A case study on the invasive Iberian gudgeon (Gobio lozanoi; Doadrio and Madeira, 2004)

The invasion of freshwater ecosystems is a particularly alarming phenomenon in the Iberian Peninsula. Habitat suitability modelling is a proficient approach to extract knowledge about species ecology and to guide adequate management actions. Decision-trees are an interpretable modelling technique widely used in ecology, able to handle strongly nonlinear relationships with high order interactions and diverse variable types. Decision-trees recursively split the input space into two parts maximising child node homogeneity. This recursive partitioning is typically performed with axis-parallel splits in a top-down fashion. However, recent developments of the R packages oblique.tree, which allows the development of oblique split-based decision-trees, and evtree, which performs globally optimal searches with evolutionary algorithms to do so, seem to outperform the standard axis-parallel top-down algorithms; CART and C5.0. To evaluate their possible use in ecology, the two new partitioning algorithms were compared with the two well-known, standard axis-parallel algorithms. The entire process was performed in R by simultaneously tuning the decision-tree parameters and the variables subset with a genetic algorithm and modelling the presence–absence of the Iberian gudgeon (Gobio lozanoi; Doadrio and Madeira, 2004), an invasive fish species that has spread across the Iberian Peninsula. The accuracy and complexity of the trees, the modelled patterns of mesohabitat selection and the variables importance were compared. None of the new R packages, namely oblique.tree and evtree, outperformed the C5.0 algorithm. They rendered almost the same decision-trees as the CART algorithm, although they were completely interpretable – they performed from four to eight partitions – in comparison with C5.0, which resulted in a more complex structure with 17 partitions. Oblique.tree proved to be affected by prevalence and it does not include the possibility of weighting the observations, which potentially discourage its actual use. Although the use of evtree did not suggest a major improvement compared with the remaining packages, it allowed the development of regression trees which may be informative for additional modelling tasks such as abundance estimation. Looking at the resulting decision-trees, the optimal habitats for the Iberian gudgeon were large pools in lowland river segments with depositional areas and aquatic vegetation present, which typically appeared in the form of scattered macrophytes clumps. Furthermore, Iberian gudgeon seems to avoid habitats characterised by scouring phenomena and limited vegetated cover availability. Accordingly, we can assume that river regulation and artificial impoundment would have favoured the spread of the Iberian gudgeon across the entire peninsula.

Do Environmental Stream Classifications Support Flow Assessments in Mediterranean Basins

Natural flow regimes are of primary interest in designing environmental flows and therefore essential for water management and planning. The present study discriminated natural hydrologic variation using two different environmental classifications (REC-Segura and WFD-ecotypes) and tested their agreement with an a posteriori (hydrologic) classification in a Spanish Mediterranean basin (the Segura River, SE Spain). The REC-Segura was developed as a two-level hierarchical classification based on environmental variables that influence hydrology (climate and source-of-flow). The WFD-ecotypes were developed by the Spanish Ministry for the Environment to implement the Water Framework Directive (WFD) using hierarchical hydrologic, morphologic and physicochemical variables. The climate level in the REC-Segura broadly described the hydrologic pattern observed along the NW-SE aridity gradient of the basin. However, source-of-flow (defined by karstic geology) was only able to discriminate variation in flow regimes within one climatic category. The WFD-ecotypes, despite incorporating hydrologic variables, did not fully discriminate hydrologic variation in the basin. Ecotypes in tributary streams located in dry or semiarid climates embrace different flow regimes (both perennial and intermittent). There was little agreement between environmental and hydrologic classifications. Therefore, the authors advise against the use of environmental classifications for the assessment of environmental flows without first testing their ability to discriminate hydrologic patterns.

Implementation of an eco-hydrological classification in Chilean rivers

En Chile existe un aumento en la preocupacion por proteger y conservar los ecosistemas acuaticos debido al elevado estado de deterioro del habitat. Como un primer paso para desarrollar planes de conservacion, se hace necesario realizar una clasificacion de estos ecosistemas para conocer y entender los distintos tipos y su funcionamiento. Entendiendo que el caudal es el principal factor en la composicion de ecosistemas fluviales, se ha desarrollado una clasificacion Eco-Hidrologica de los rios de Chile (REC-Chile) basada en una superposicion jerarquica de factores controladores del patron hidrologico en Chile. REC-Chile es multiescalar, permitiendo segun los factores controladores seleccionados representar distintos patrones fluviales a diversas escalas espaciales. La tipologia del tramo de rio se representa como un codigo de 6 digitos, en donde la posicion del digito representa el factor controlador y el valor a la categoria de este. Esta configuracion jerarquica, asi como la asignacion geograficamente independiente de sus clases, dota a la REC-Chile de facilidad en la interpretacion hidrologica de las clases. Debido a la ductilidad y flexibilidad, entregada por la multiescalaridad y por la sencilla interpretacion de sus clases, se espera que la REC-Chile se convierta en una herramienta para desarrollar planes de conservacion de los ecosistemas acuaticos