Physical habitat assessment in the Tajuna river (Spain) by means of the MesoHABSIM approach

Physical habitat was assessed in the Tajuña river (Tagus basin, Spain) by means of the MesoHABSIM approach. Long reaches of the Tajuña river are altered by agricultural use of the riverside. The main impacts are river rectification (straightening), channel entrenchment and incision, and degradation of riparian vegetation, along with important flow depletion and regulation. To our knowledge, this is the first application in Spain of MesoHABSIM, which is a physical habitat model based on the identification of habitat attributes - depth, water velocity, substrate, types of hydromorphologic units (HMU), and types of cover - on the mesohabitat scale. The river was stratified into 16 segments with similar habitat characteristics. Mesohabitats were mapped in one representative site (1-2 km long) within each segment to provide a hydromorphologic model of the river. Biological models were developed for fry, juvenile, and adult brown trout. To do this, preliminary models were generated based on literature about trout habitat requirements, and then they were calibrated with electrofishing data. These models were applied to the hydromorphologic model of the river to quantify the available habitat for brown trout in the current conditions. Finally, restoration action was designed to decrease channel entrenchment, increase river sinuosity, and recover its riparian vegetation. The physical changes after restoration were estimated by expert opinion, and the quantification of the available habitat was done with MesoHABSIM at each site. These results can be used to select the segments that are the best candidates for restoration.Se ha evaluado el hábitat físico en el río Tajuña (cuenca del Tajo, España) mediante la metodología MesoHABSIM. Una parte importante del río Tajuña está alterada por los usos agrícolas de las riberas. Los principales impactos son la rectificación, el encajonamiento e incisión del cauce, y la degradación de la vegetación riparia, junto con una importante extracción y regulación del caudal. Hasta donde conocemos, ésta es la primera aplicación de MesoHABSIM en España. Se trata de un modelo de hábitat físico, basado en la identificación de los atributos del h'abitat -profundidad, velocidad del agua, sustrato, tipo de unidad hidromorfológica (HMU) y tipo de cobertura o refugio- en la escala del mesohábitat. Se estratificó el río en 16 segmentos con características similares de hábitat. En cada segmento se muestrearon los mesohábitats en un tramo representativo de 1-2 km de largo, construyendo así un modelo hidromorfológico del río. Se generaron modelos biológicos para alevines, juveniles y adultos de trucha común. Para ello, se construyeron unos modelos preliminares a partir de bibliografía acerca de los requerimientos de hábitat de la trucha, y después se calibraron con datos obtenidos mediante pesca eléctrica. Estos modelos fueron aplicados al modelo hidromorfológico para cuantificar el hábitat disponible para la trucha común en las condiciones actuales. Finalmente se diseño una acción de restauración con el objetivo de disminuir el encajonamiento del cauce, aumentar su sinuosidad y recuperar su vegetación riparia. Los cambios tras la restauración se estimaron por opinión de experto, y la evaluación del hábitat resultante se realizó mediante MesoHABSIM. Estos resultados pueden emplearse para elegir los segmentos más apropiados para realizar la restauración propuesta

River-Wide Habitat Availability for Fish Habitat Guilds: Implications for In-Stream Flow Protection

The variation in river discharge alters habitat heterogeneity with implications for the distribution of fish species with different habitat requirements. Assessments of habitat availability following changes in river discharge are difficult to apply at broad spatial scales and with relevance to multiple species. We used a MesoHABSIM modeling approach to quantify river-wide changes in habitat availability for five fish habitat guilds under three river discharge levels along the Niobrara River, NE, USA.We used a time-series of river discharge (1958–2010) to create uniform continuous under-threshold habitat duration curves that identified habitat conditions that may result in periods of stress for fish communities along the Niobrara River. Habitat availability for each fish habitat guild was dependent on river discharge and location along the river. Habitat availability for fish habitat guilds ranged from 5% to 49% of the total channel area suggesting habitat availability may, at times, be limited. We provide river discharge guidelines for bioperiods that limit the frequency and duration of stressful habitat conditions. Understanding interactions between river discharge and habitat availability through time and at river-wide scales may aid in managing for ecological integrity by including protection of river discharge variability to support multiple fish habitat guilds

Criteria for identifying free-flowing river stretches for the EU Biodiversity Strategy for 2030

The EU Biodiversity Strategy includes the target that at least 25000 km of rivers should be restored into free-flowing rivers by 2030 through the removal of primarily obsolete barriers and the restoration of floodplains and wetlands. This document proposes criteria for identifying free-flowing rivers, taking into account longitudinal, lateral, and vertical connectivity at local and catchment scales. The aim is to provide a tool that can be used by authorities to determine the length of free-flowing rivers in their catchments. In addition, the tool can be used to predict the increase in free-flowing river length resulting from barrier removal and other restoration measures. This will help prioritising measures that can contribute to the 25,000 km target. Key elements of the method are (1) segmentation of the river into homogeneous reaches; (2) criteria for longitudinal, lateral, and vertical connectivity within a homogeneous reach; (3) a large-scale assessment taking into account sediment connectivity and migration barriers for target fish species; and (4) minimum length criteria to ensure hydromorphological processes and ecological functioning.JRC.D.2 - Ocean and Wate

Over 200,000 kilometers of free-flowing river habitat in Europe is altered due to impoundments

European rivers are disconnected by more than one million man-made barriers that physically limit aquatic species migration and contribute to modification of freshwater habitats. Here, a Conceptual Habitat Alteration Model for Ponding is developed to aid in evaluating the effects of impoundments on fish habitats. Fish communities present in rivers with low human impact and their broad environmental settings enable classification of European rivers into 15 macrohabitat types. These classifications, together with the estimated fish sensitivity to alteration of their habitat are used for assessing the impacts of six main barrier types (dams, weirs, sluices, culverts, fords, and ramps). Our results indicate that over 200,000 km or 10% of previously free-flowing river habitat has been altered due to impoundments. Although they appear less frequently, dams, weirs and sluices cause much more habitat alteration than the other types. Their impact is regionally diverse, which is a function of barrier height, type and density, as well as biogeographical location. This work allows us to foresee what potential environmental gain or loss can be expected with planned barrier management actions in rivers, and to prioritize management actions

Session A3 - Neptun: the electronic guidance system that effectively manages fish movement in a down and upstream waterway.

Dr. Piotr Parasiewicz is a civil and environmental engineer educated on the University of Agricultural Sciences in Vienna. He is an expert in instream flow models, habitat restoration and nature-like fishways. Piotr is a developer of MesoHABSIM (www.MesoHABSIM.org ), a multiscale approach for instream habitat modelling. It is currently used in instream flow management and river restoration and planning across US and in Europe. Among others, the model has been applied for determination of Protected Instream Flow Standards in the State of New Hampshire where it has been adopted as a part of State’s legal framework. Since 1999 in USA, he worked at Cornell University and University of Massachusetts, Amherst. He is currently a director of the Rushing Rivers Institute, a river research non-profit (www.RushingRivers.org) and an Adjunct Professor at the University of Nebraska Lincoln. Dr. Parasiewicz frequently offers technical advise to the government, non-profits and the industry. Most notably he was appointed by the Government of Austria as a member of Austrian Network for Environmental Research, an expert commission actively participating in development of EU environmental and research policy. In 2006 and 2007 he was appointed as an expert to the Science and Technical Workgroup on Water Flow Regulations for the State of Connecticut. Currently he serves as a technical advisor at the Sustainable Water Initiative of the State of MassachusettsThe protection of fish communities at man-made facilities and barriers has a long history of significant expenditure of scientific and monetary resources. Beyond creating fishways, considerable investment is made to protect fish by blocking their access to turbines, water intakes, and directing them to less risky areas. Nevertheless, guiding fish to the fish passages, especially in downstream direction still present a big problem. The anticipated success of electrical fish barriers and guidance structures has been limited due to current design limitations. However, a device with a fundamentally new design feature has been successfully deployed in Poland. The device is called "NEPTUN". NEPTUN is an electric-electronic 3-phase barrier, producing a smooth non-uniform pulsed electric field of low voltage. It uses arrays of positive and negative electrodes and gradually increases the intensity of the electric field between the electrodes from positive to negative. Unlike other devices NEPTUN does not stun fish, but affects their neuromuscular system at the informational level, allowing them to escape from the area of the electric field. The basic field installation consists of steel electrodes attached to the river bottom so that they can move from the vertical to an angle of + / - 90 degrees. A buoy attached at the end of the electrode keeps it in an upright position. Groups of electrodes are powered by remotely controlled generators. Specialized software controls the parameters of the electric field, creates statistically-mastered changes, and controls the switching of each group of electrodes. The system supports sensors for monitoring temperature and conductivity of the water which can be used to automatically adjust the properties of the electric field. With an average power input of 0.43 to 0.45 kWh and electricity consumption of 0.0018 kW/m2, "NEPTUN" has a low operating cost. Additionally, the system maintenance is minimal

Application of the Mesohabitat Simulation System (MesoHABSIM) for Assessing Impact of River Maintenance and Restoration Measures

Maintenance and restoration activities alter the river morphology and hydrology, and in consequence, alter fish habitats. The aim of this research was to investigate the change of habitat availability for fish guilds after carrying out maintenance works, commonly used river restoration measures and a restoration derived from fish habitat requirements. The selected study site is located at a close to natural condition section of Swider River in central Poland. The MesoHABSIM model was used to assess the area of suitable habitats in this site and predict habitat distribution at all planning scenarios. The affinity index which is a measure of similarity of two distributions showed that the likely distribution of habitats for fish resulting from simulated maintenance is 76.5% similar to that under measured conditions. The distribution of habitats caused by river restoration is also similar to that of the baseline in 73.2%. The resemblance between the restoration scenario focusing on fish habitat requirements and the reference conditions is 93.1%. It is beneficial to define the river restoration measures based on habitat availability for fish community. Modelling is a useful tool to simulate the changes and predict which guilds there is abundance of suitable habitats, and for which there are too few. It allows for more effective use of resources according to quantitative target states