Current Practices on the Water Frame Directive implementation in Spain: Problems and Perspectives

River typologies and methods for selecting reference sites and reference conditions are being discussed in Spain, starting from a single-scale, taxonomic classification of rivers and a relative experience on the use of biotic indexes for water quality monitoring. The present reductionistic tendency of using the biotic indexes for defining biological reference conditions is discussed, attending to the loosing of basic biological information and precision that occurs when the species composition list and abundance structure are expressed in single numbers. Ideas for alternative methods are presented, including a hierarchical, multiple-scale river classification scheme, from which selection of reference sites can be made, according to the status of hydromorphological and water quality elements. The importance of achieving the finest taxonomic resolution of the biological data for defining the reference conditions is remarked, in order to establish a solid, scientifically based pool of data from which the ecological status of rivers can be precisely estimated, preserving the peculiarities of each river type

Fish communities as indicators of biological conditions of rivers: methods for reference conditions

Fish communities are a key element in fluvial ecosystems Their position in the top of the food chain and their sensitivity to a whole range of impacts make them a clear objective for ecosystem conservation and a sound indicator of biological integrity. The UE Water Framework Directive includes fish community composition, abundance and structure as relevant elements for the evaluation os biological condition. Several approaches have been proposed for the evaluation of the condition of fish communities, from the bio-indicator concept to the IBI (Index of biotic integrity) proposals. However, the complexity of fish communities and their ecological responses make this evaluation difficult, and we must avoid both oversimplified and extreme analytical procedures. In this work we present a new proposal to define reference conditions in fish communities, discussing them from an ecological viewpoint. This method is a synthetic approach called SYNTHETIC OPEN METHODOLOGICAL FRAMEWORK (SOMF) that has been applied to the rivers of Navarra. As a result, it is recommended the integration of all the available information from spatial, modelling, historical and expert sources, providing the better approach to fish reference conditions, keeping the highest level of information and meeting the legal requirements of the WFD

Brown trout redd superimposition in relation to spawning habitat availability

The relationship between redd superimposition and spawning habitat availability was investigated in the brown trout (Salmo trutta L.) population inhabiting the river Castril (Granada, Spain). Redd surveys were conducted in 24 river sections to estimate the rate of redd superimposition. Used and available microhabitat was evaluated to compute the suitable spawning habitat (SSH) for brown trout. After analysing the microhabitat characteristics positively selected by females, SSH was defined as an area that met all the following five requirements: water depth between 10 and 50 cm, mean water velocity between 30 and 60 cm s)1, bottom water velocity between 15 and 60 cm s)1, substrate size between 4 and 30 mm and no embeddedness. Simple regression analyses showed that redd superimposition was not correlated with redd numbers, SSH or redd density. A simulation-based analysis was performed to estimate the superimposition rate if redds were randomly placed inside the SSH. This analysis revealed that the observed superimposition rate was higher than expected in 23 of 24 instances, this difference being significant (P menor que 0.05) in eight instances and right at the limit of statistical significance (P = 0.05) in another eight instances. Redd superimposition was high in sections with high redd density. High superimposition however was not exclusive to sections with high redd density and was found in moderate- and low-redd-density sections. This suggests that factors other than habitat availability are also responsible for redd superimposition. We argue that female preference for spawning over previously excavated redds may be the most likely explanation for high superimposition at lower densities

Caracterización y clasificación de los regimenes de caudales de la cuenca del Ebro en función de su fluctuación intranual

Las pautas naturales de fluctuación intranual de los caudales varían de unos ríos a otros condicionando, tanto de forma directa como de forma indirecta mediante su efecto dinamizador de las características físicas que subyacen las comunidades biológicas, la distribución de las especies, su capacidad adaptativa, su capacidad de supervivencia, de dispersión, de reproducción,… y en definitiva la biodiversidad, producción y sostenibilidad de cada ecosistema fluvial

Large Scale dynamics of Brown trout populations across Navarra Rivers (North Spain)

Most studies on the population dynamics of stream-living salmonids have attempted to elucidate the causes of variation in demographic traits or population abundance by analyzing population time series vis-á-vis environmental data. In order to express the results on a scale compatible with fishery management strategies, most studies have been done at the scale of a stream reach, a stream or a river basin with few studies focused on the population dynamics at larger geographic scales. Our goal is to determine the extent to which the effects of both, exogenous and endogenous factors actually describe the variations in abundance of brown trout populations inhabiting separated river basins across a large and environmentally heterogeneous territory. We tested whether the trout abundance across a large territory involving distinct populations could be described by determining the extent to which exogenous and endogenous drivers underlie the per capita population growth rate estimated from long-term time series in a way similar to that previously assessed at smaller geographical scales. We have developed a simple multivariate linear model that synthetically combines an index of large-scale climate variation with mean population abundance. This model has been built on the basis of a data set encompassing 18-year quantifications of abundance at 68 sampling stations. The results of our simulation model predict mean trout abundance with less than 10% error

Determinación del hábitat potencialmente utilizable por la especie Salmo trutta en un tramo del río Lozoya, España

En el presente trabajo se efectua la estimacion del habitat potencialrnente utilizable (HPU) y del caudal que lo maximiza para los estadios de vida adulto, juvenil, alevin y freza de la especie Salmo trutta (trucha comun), especie muy apreciada en la pesca deportiva y para el consumo humane Para tal fin, de acuerdo con la Metodologia IFIM (Instream Flow Incremental Methodology), se efectuo la simulacion del habitat fisico fluvial de un tramo de 609 m del rio Lozoya (Madrid, Espana) utilizando un modelo bidimensional de la hidrodinamica, un modelo para la simulacion del habitat y los modelos de preferencia de habitat de la especie antes mencionada. Los modelos fueron alimentados con informacion hidraulica, geomorfologica, biologica y de caracteristicas especificas del habitat obtenidas en campo. Los valores del habitat potencialrnente utilizable (HPU) obtenidos para los cuatro estadios de desarrollo de la especie Salmo trutta permitieron determinar que el caudal de 1.97 m3/s maximiza el HPU para sus estadios de vida adulto, juvenil y freza, y que el caudal de 1.08 m3/s maximiza el habitat potencialrnente utilizable para su estadio de desarrollo alevin. Las curvas caudal-habitat potencialrnente utilizable obtenidas en el presente trabajo constituyen informacion valiosa para los usuarios y los gestores de los recursos fluviales del rio Lozoya, con miras a establecer un regimen de caudales ecologicos que permita conservar el ecosistema correspondiente y, en caso necesario, evaluar los impactos relacionados con posibles modificaciones del regimen de caudales

Integrated methodology for assessing the effects of geomorphological river restoration on fish habitat and riparian vegetation

Changes in the geomorphology of rivers have serious repercussions, causing losses in the dynamics and naturalness of their forms, going in many cases, from a type of meandering channel, with constant erosion and sedimentation processes, to a channelized narrow river with rigid and stable margins, where the only possibility of movement occurs in the vertical, causing the only changes in channel geometry occur in the river bed. On the other hand, these changes seriously affect the naturalness of the banks, preventing the development of riparian vegetation and reducing the cross connectivity of the riparian corridor. Common canalizations and disconnections of meanders increase the slope, and therefore speed, resulting in processes of regressive erosion, effect increased as a result of the narrowing of the channel and the concentration of flows. This process of incision may turn the flood plain to be "hung", being completely disconnected from the water table, with important consequences for vegetation. As an example of the effects of these changes, it has been chosen the case of the Arga River The Arga river has been channelized and rectified, as it passes along the meander RamalHondo and Soto Gil (Funes, Navarra). The effects on fish habitat and riparian vegetation by remeandering the Arga River are presented. and Ttwo very contrasting situationsrestoration hypothesis, in terms of geomorphology concerns, have been established to assess the effects these changes have on the habitat of one of the major fish species in the area (Luciobabus graellsii) and on the riparian vegetation. To accomplish this goal, it has been necessary to used the a digital elevation model provided by LIDAR flight, bathymetric data, flow data, as inputs, and a hydraulic simulation model 2D (Infoworks RS). The results obtained not only helped to evaluate the effects of the past alterations of geomorphologic characteristics, but also to predict fish and vegetation habitat responses to this type of changes

Dam function rules based on brown trout flow requirements: design of environmental flow regimes in regulated streams

The operation of small hydroelectric dams built on mountain streams induce changes in stream flow regimes that are manifested not only in the intensity of flow events, but also in the variability and frequency of high- and low-flow episodes. Former studies have shown the influence of flow variability upon the dynamics of a resident brown trout population, especially that related to the stream flow regime during spawning, incubation and emerging periods. As these life-stages are known to determine the population dynamics in further ages, stream flow variability appears to be a major influence on the regulation of a wild brown trout population. Thus, mean flow discharge should not be the only parameter taken into account when establishing ecological flow regimes to support rehabilitation of degraded trout populations in mountain streams. Ecological stream flow regime characteristics are proposed as a basis for the design of environmental flow regimes in mountain reaches downstream of hydroelectric or water supply dams. Case studies were conducted in a high mountain basin in Central Spain (River Tormes) for a period of 5 years showing that relationship between duration and frequency of high and low flow episodes during egg incubation could be linked to young-of-the-year recruitment and quantified in terms of flow management units. Duration and frequency of flow discharges could be manipulated so as to create favourable hydrological conditions for restoring sustainable populations of brown trout in rivers affected by flow regulatio

National Strategy for River Restoration in Spain: A multidisciplinary approach.

A National Strategy for River Restoration is being implemented by the Spanish Ministry of Environmental Affairs, with the scientific assistance of the Universidad Politécnica of Madrid. Theoretical concepts from Fluvial Geomorphology and Ecology, together with Water Framework Directive principles and objectives, have been the basis for this Strategy, whose the main objective is to improve the ecological status of rivers, recovering their natural variability and dynamics

Simulación del habitat físico en un tramo del río Lozoya, utilizando el sistema PHABSIM

[EN] This paper presents the habitat simulation of a 609-m stretch of the Lozoya river for obtaining the availability of Weighted Usable Area (WUA) for adult, juvenile and fry life stages of Barbus bocagei (endemic species of the Iberian Peninsula); as well as for determining the flow that maximizes the WUA. For habitat simulation, the Physical Habitat Simulation System (PHABSIM) was used, which is part of the Instream Flow Incremental Methodology (IFIM). Physical habitat simulation was made using PHABSIM hydrodynamic and habitat models, as well as habitat preference models for target species. As a result, Weighted Usable Area-Flow Curves (WUA-Q) were obtained, where WUA distribution can be observed as a function of the stream flows of the Lozoya River stretch, and it can be identified that a flow of 1.45m3/s maximizes the Weighted Usable Area for the adult and juvenile life stages of Barbus bocagei. As for the fry life stage, HPU grows with flow, but it can be identified that HPU grows the most in a range between 0.2 and 1.45m3/s. WUA-Q curves provide valuable information to the manager and to the different users of fluvial resources for determining instream flow regimes in order to meet fluvial ecosystem conservation needs.[ES] En el presente trabajo se efectúa la simulación del hábitat físico de un tramo de 609 m del río Lozoya, con la finalidad de estimar la disponibilidad de hábitat potencialmente utilizable (HPU) por la especie Barbus bocagei (endémica de la península Ibérica), en sus estadios de vida adulto, juvenil y alevín; así como estimar el caudal que maximiza dicho HPU. Para tal efecto, se utilizó el sistema PHABSIM (Physical Habitat Simulation System), el cual forma parte de la metodología IFIM (Instream Flow Incremental Methodology). En el PHABSIM se realiza la simulación del hábitat fluvial utilizando modelos de simulación de la hidrodinámica, del hábitat y modelos de las preferencias de hábitat de la(s) especie(s) objetivo, obteniendo como resultado la evolución del HPU en función del caudal del río, la cual se plasma gráficamente en las curvas caudal-hábitat potencialmente utilizable (Q-HPU); en las que se identificó, para el presente trabajo, que el caudal que maximiza el HPU para los estadios de vida adulto y juvenil de la especie Barbus bocagei es del orden de 1.45m3/s. En el caso del estadio alevín, la tendencia del HPU es a crecer con el caudal, pero se identifica que en el intervalo de caudales comprendido entre 0.2 y 1.45 m3/s se da el mayor crecimiento. Las curvas Q-HPU proporcionan información valiosa al gestor, y a los diferentes usuarios de los recursos fluviales, para determinar regímenes de caudales ecológicos destinados a la conservación del ecosistema correspondiente.García-Rodríguez, E.; Martínez-Austria, P.; García De Jalón De La Lastra, D.; Martinez-Capel, F. (2008). Simulación del habitat físico en un tramo del río Lozoya, utilizando el sistema PHABSIM. Ingeniería hidráulica en México. XXIII(4):41-52. http://hdl.handle.net/10251/33326S4152XXIII