Assessing multi slot versus single slot pool-type fishways suitability for potamodromous cyprinids: An experimental approach using numerical modelling and fish

Developing new fishway designs that provide suitable hydrodynamic conditions for multiple native freshwater fish species is paramount to mitigate the negative effects of anthropogenic barriers in rivers. This poses an increased challenge in Mediterranean regions, where water availability is limited and issue of conflicting demands. Vertical slot fishways (VSF) are considered one of the best types of technical fishways for potamodromous fish species. However, they generally require a greater amount of water to operate relatively to other type of facilities. The present study used 3D numerical modelling to compare the hydrodynamics and assess the hydraulic suitability for multiple fish species, of a widely used VSF and of two multi slot fishway (MSF) configurations. The MSF configuration requires a lower discharge to operate (\u3e 20% less discharge) than the VSF, while keeping similar flow depths. With the reduction in discharge, the velocity, turbulent kinetic energy and Reynolds shear stress values for MSF are also much lower than the values for VSF (c. 20 – 40% less). Hence, besides requiring smaller discharges than similar VSF design, the MSF seems to be less selective for fish species, particularly smaller-sized individuals, and individuals with weaker swimming capacities. Passage performance of the Iberian barbel, Luciobarbus bocagei (Steindachner, 1864) was subsequently assessed when negotiating a VSF and a MSF in an indoor full scale experimental model. Results showed that the Iberian barbel performed a significantly higher number of movements in the MSF when compared to the VSF. On the other hand, no differences were found in the entrance time, entry efficiency and overall fish performance between configurations. This study shows that numerical modelling complemented with laboratory fish experiments can be an important tool to develop cost-effective fishways

Session D7: Is CFD an Efficient Tool ao Develop Pool Type Fishways?

Abstract: Rivers longitudinal connectivity is compromised by man-made obstacles, such as dams and weirs, which affect fish movements, leading to populations decrease and genetic deterioration. Properly designed fishways re-establish connectivity, allowing for fish migration. The aim of our work is to contribute to a more fast and efficient development of pool-type fishways using hydrodynamic modelling, based on fish behaviour experiments. Modelling free surface flows in hydraulic structures with complex geometry, like pooltype fishways, with aerated and complex flow patterns, represents a significant research challenge. Knowledge already acquired in an experimental full scale indoor pool-type fishway in previous studies is used. A 1:2.5 scaled fishway of this facility was built and used to characterize velocity and turbulence in a pool-type fishway with cross-walls equipped with bottom orifices. An offset orifice configuration was used with consecutive orifices positioned on opposite sides of the cross-walls, creating a sinusoidal flow path. The measurements of velocity fields were made using Particle Image Velocimetry (PIV) and Acoustic Doppler Velocimetry (ADV). Velocity maps were obtained at several positions, for planes parallel to the bottom and parallel to the sidewalls. Parameters that influence fishways efficiency like velocity fields, turbulent kinetic energy and Reynolds shear stresses were determined. A 3D computational fluid dynamics (CFD) model of the fishway was developed using a commercial software FLOW-3D. Velocity fields, turbulent kinetic energy and Reynolds shear stresses were compared with the ones determined from PIV measurements and ADV measurements and results deviations between experimental and numerical data were analyzed. The use of FLOW 3D to simulate mean velocity patterns and flow turbulence in pooltype fishways and its use as design tool for new fishway geometries are discussed

Using CASIMIR-Vegetation model in the context of modeling riparian woods and fish species to support a holistic approach for environmental flows to be used on river management and conservation

The CASiMiR-vegetation model is a software that recreates the physical processes influencing the survival and recruitment of riparian vegetation, based on the relationship between ecologically relevant flow regime components and riparian vegetation metrics that reflect the vegetation’s responses to flow regime change. Working at a flow response guild level, this tool outperforms equivalent models by overriding various restrictions of the conventional modeling approaches. The potential of the CASiMiR-vegetation model is revealed in its application to different case studies during the development of a holistic approach to determine environmental flows in lowland Mediterranean rivers, based on woody riparian vegetation and fish species. Various modeling circumstances are described where CASiMiR-vegetation model was used with the purpose of sustaining the research addressing the thesis objectives. The main findings already accomplished in this research are highlighted to illustrate the outcomes that can be attained from the use of such a model

Fish habitat availability simulations using different morphological variables

Fish habitat modelling results are strongly influenced by velocity and depth patterns as well as by morphological parameters of the riverbed (i.e., substrate and refuge cover). Studies regarding the use of substrate in habitat modelling are well represented in the literature, whereas the use of cover in such models is commonly neglected because it is difficult to quantify the refuges or the instream areas where fish can hide from predators. However, there is clear evidence that fish habitat use and preferences are associated with refuge cover. Ignoring this variable can lead to incorrect restoration and flow management decisions based on misleading results. To avoid this, river restoration goals should only be set with reference to habitat conditions found at undisturbed sites rather than with the aim of improving habitat heterogeneity. The aim of this study is to compare the habitat availability for two cyprinid fishes, the Southwestern arched-mouth nase (Iberochondrostoma almacai) and the Arade chub (Squalius aradensis), at undisturbed (i.e., near-natural state) and disturbed sites (i.e., sites impacted by agricultural activities that have led to nutrient enrichment, destruction of riparian woodlands, straightening of the river channel and water abstraction). This is done by alternately considering substrate or refuge cover in a weighted usable area (WUA) determination to understand the interactive effects of these morphological variables as well as their influence on habitat availability. Different outcomes were generated by the use of refuge cover and substrate in habitat simulation. The results underline the importance of considering refuge cover in habitat models and also point to the need to take into account minimally disturbed or undisturbed sites within the same river upon developing future management actions.Los resultados de la modelación de hábitats piscícolas están fuertemente influenciados por la velocidad y los patrones de profundidad, así como por los parámetros morfológicos (i.e. substrato y cobertura de refugio) del lecho del río. Estudios sobre el uso de sustrato en la modelización del hábitat están bien descritos en la literatura, mientras que el uso de la cobertura es frecuentemente omitida, ya que es difícil de cuantificar el refugio o las zonas donde los peces se pueden abrigar y ocultar de los predadores. Sin embargo, hay pruebas claras de que el uso y las preferencias de los peces también están asociados con la cobertura de refugio. Ignorando esta variable puede conducir a decisiones de restauración fluvial y de gesti'on de los recursos hídricos apoyados en resultados engañosos. Para evitar eso, los objetivos de la restauración fluvial se debían establecer con referencia a las condiciones de habitat que se pueden encontrar en trechos de río no alterados, en lugar de mejorar la heterogeneidad del hábitat. El objetivo de este estudio es comparar la disponibilidad de hábitat para dos peces ciprínido, el boga del Sudoeste (Iberochondrostoma almacai) y el cacho del Arade (Squalius aradensis) en trechos de río no perturbados (i.e. próximo del natural) y perturbados (i.e. perturbados por actividades agricolas que llevan a un enriquecimiento de nutrientes, destrucción de la mata riparia, enderezamiento del cauce y abstracción de agua). Esto es hecho considerando alternativamente o sustrato o la cobertura de refugio en la determinación del weighted usable area (WUA) a fin de dar a conocer los efectos interactivos de las variables morfológicas, así como su influencia en la disponibilidad de hábitat. Diferentes respuestas fueran encontradas con el uso posterior de la cobertura de refugio y el sustrato en la simulación del hábitat. Los resultados exponen la importancia de considerar la cobertura de refugio en los modelos de hábitat y adem'as apuntan la necesidad de tener en cuenta sitios mínimamente alterados o no perturbados de un mismo río para el desarrollo de futuras acciones de gestión fluvial

Importance of considering riparian vegetation requirements for the long-term efficiency of environmental flows in aquatic microhabitats

Environmental flows remain biased toward the traditional biological group of fish species. Consequently, these flows ignore the inter-annual flow variability that rules species with longer lifecycles and therefore disregard the long-term perspective of the riverine ecosystem. We analyzed the importance of considering riparian requirements for the long-term efficiency of environmental flows. For that analysis, we modeled the riparian vegetation development for a decade facing different environmental flows in two case studies. Next, we assessed the corresponding fish habitat availability of three common fish species in each of the resulting riparian landscape scenarios. Modeling results demonstrated that the environmental flows disregarding riparian vegetation requirements promoted riparian degradation, particularly vegetation encroachment. Such circumstance altered the hydraulic characteristics of the river channel where flow depths and velocities underwent local changes of up to 10 cm and 40 cm s1, respectively. Accordingly, after a decade of this flow regime, the available habitat area for the considered fish species experienced modifications of up to 110% when compared to the natural habitat. In turn, environmental flows regarding riparian vegetation requirements were able to maintain riparian vegetation near natural standards, thereby preserving the hydraulic characteristics of the river channel and sustaining the fish habitat close to the natural condition. As a result, fish habitat availability never changed more than 17% from the natural habitatinfo:eu-repo/semantics/publishedVersio

Complex fluid flow in microchannels and heat pipes with enhanced surfaces for advanced heat conversion and recovery systems

This paper addresses a multiscale approach for heat recovery systems, used in two distinct applications. In both applications, a microscale approach is used (microchannel heat sinks and heat pipes) for macroscale applications (cooling of a photovoltaic—PV cell), and the thermal energy of exhaust gases of an internal combustion engine is used for thermoelectric generators with variable conductance heat pipes. Several experimental techniques are combined such as visualization, thermography with high spatial and temporal resolution, and the characterization of the flow hydrodynamics, such as the friction losses. The analysis performed evidences the relevance of looking at the physics of the observed phenomena to optimize the heat sink geometry. For instance, the results based on the dissipated heat flux and the convective heat transfer coefficients obtained in the tests of the microchannel-based heat sinks for cooling applications in PV cells show an improvement in the dissipated power at the expense of controlled pumping power, for the best performing geometries. Simple geometries based on these results were then used as inputs in a genetic algorithm to produce the optimized geometries. In both applications, the analysis performed evidences the potential of using two-phase flows. However, instabilities at the microscale must be accurately addressed to take advantage of liquid phase change. In this context, the use of enhanced interfaces may significantly contribute to the resolution of the instability issues as they are able to control bubble dynamics. Such an approach is also addressed here.Authors acknowledge to Fundação para a Ciência e a Tecnologia¸ FCT and PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund, for partially financing this project through projects PTDC/EME-TED/7801/2020, JICAM/0003/2017, UIDB/00481/2020, UIDP/00481/2020, and CENTRO-01-0145-FEDER-022083 (Centro2020) and for funding the scholarship of Pedro Pontes, ref. SFRH/BD/149286/2019

Sustained remission from depressive-like behavior depends on hippocampal neurogenesis

Impairment of hippocampal neurogenesis has been associated with the expression of depressive-like symptoms and some studies have suggested neurogenesis as a critical factor in the normalization of behavior by antidepressant (AD) drugs. This study provides robust evidence that ongoing neurogenesis is essential for the maintenance of behavioral homeostasis and that its pharmacological arrest precipitates symptoms commonly found in depressed patients. Further, the incorporation of newly born neurons and astrocytes into the preexisting hippocampal neurocircuitry is shown to be necessary for the spontaneous recovery from the adverse effects of stress and for long-term benefits of AD treatments.We thank M Carneiro and L Martins for technical assistance. AM-P, LP, MM and SM received fellowships from the Portuguese Foundation for Science and Technology (FCT). This work was supported by FCT (PTDC/SAU-NEU/105180/2008) and the ICVS