Paulo Branco

Associate Laboratory TERRA · Forest Research Centre

Freshwater systems are severely impacted by connectivity reduction due to the construction of dams and weirs. The breach of this longitudinal connectivity imperils freshwater fish species world‐wide. There is thus an increasing need for numerical tools that help decision‐makers correctly allocate resources to prioritize restoration actions. This st...

Loss of natural river network connectivity is presumed to be one of the more generalized and important human-induced alterations in natural environments and is frequently perceived as one of the main causes of the decline of freshwater fish species.The purpose of the present study was to ascertain the impact of barriers on the distribution of fresh...

Fish are particularly sensitive to connectivity loss as their ability to reach spawning grounds is seriously affected. The most common way to circumvent a barrier to longitudinal connectivity, and to mitigate its impacts, is to implement a fish passage device. However, these structures are often non-effective for species with different morphologica...

River artificial fragmentation is arguably the most imperilling threat for freshwater- dependent fish species. Fish need to be able to freely move along river networks as not only spawning grounds but also refuge and feeding areas may be spatially and temporally separated. This incapacity of free displacement may result in genetic depletion of some...

River ecosystems are exposed to a multitude of stressors, including increasing pesticide runoff driven by precipitation and irrigation. Pyrethroids are the fourth major group of insecticides in use worldwide and have extremely negative effects on aquatic fauna. In this study, we aimed to assess the effects of an acute 2 h sub-lethal exposure to dif...

Globally, freshwater habitats are home to 9.5% of all animal species, being disproportionally relevant when considering the earth’s surface occupied. These ecosystems have also been crucial for human societal development since prehistoric times, which translates into being impacted by a multitude of anthropogenic pressures and effects throughout ti...

In Europe, rivers and wetlands are heavily impacted, thus it is critical to work towards restoration. The MERLIN project aims to “identify landscapes with high potential and priority for transformative restoration, particularly focusing on essential ecosystem services, biodiversity targets, and climate change mitigation”. To support this, river uni...

Fish represent a quarter of all vertebrates and 40% of those are freshwater-related species, the second most threatened animal group. These species are, at least for a significant part of their life cycle, limited to occur in rivers, i.e., hierarchic and dendritic networks where flow imposes a directionality. Data collected from the International U...

This study aims at understanding how observed inconsistencies in the response of biotic indicators to multiple stressors may result from different stressor gradient lengths being represented at different areas or temporal windows, either as the result of intrinsic natural causes or as the result of sampling bias. We simulated a pool of sites showin...

Despite the growing literature on the topic of freshwater fish invasion, few studies employed a comprehensive analysis of the stages characterizing the invasion process (i.e. invasion pathway), thereby demanding a deeper knowledge to avoid incomplete and unbiased conclusions and give support to adequate management strategies. The aim of the present...

Rivers have always been closely related with society development wich has resulted in a a high degree of human induced impacts forced upon freshwaters. Among all the pressures, river network fragmentation by artificial barriers is considered one of the most damaging, especially for freshwater fish species that see their longitudinal movements impar...

River systems represent ca. 1% of the Earth’s surface, and are disproportionally important for biodiversity maintenance, as they maintain a high number of species. Furthermore, these systems provide a multitude of ecosystem services on which society is dependent. Because of this dependence, rivers have long been affected by anthropogenic pressures,...

Freshwater fish species are the second most threatened animal group while the richest among European vertebrates. The International Union for Conservation of Nature (IUCN) Red List contains information on species’ populations, distribution, ecology and threats, setting the foundation for a comprehensive evaluation of species extinction risk. Using...

Dammed Fish is a research project that aims to evaluate and propose solutions and tools to inform river network connectivity management to improve fish biodiversity and to enhance biotic quality of European rivers. For this purpose, river network connectivity management needs guidance to choose the best available solutions within a frame of ongoing...

Environmental, ecosystem functioning and human activities must be considered at multiple river scales for an effective research, conservation and management of freshwater ecosystems. The ability to integrate, at multiple scales, an ever-growing plethora of information of this nature into a hierarchical dendritic and directional network, such as riv...

Longitudinal connectivity of freshwater systems can be disrupted by natural or artificial barriers. In addition to limiting fish migration, barriers can also affect habitat quality by creating changes in flow regime, sediment and nutrient transport, and water temperature. Most of the research on river network fragmentation lacks the distinction bet...

Freshwater fish species comprise 40% of all fish diversity and provide multiple ecosystem ser-vices. Recently, several populations of this faunal group have faced declines and range contrac-tions due to several threats. The Red List of Threatened Species, established by the International Union for Conservation of Nature (IUCN), is the most comprehe...

Historical information on diadromous fish species is commonly incomplete or truncated across species distribution range and spatial scales. However, historical insights have proven to be very relevant for river management and conservation. The iPODfish is a new methodological framework that enables the inference of a more thorough representation of...

Longitudinal connectivity of freshwater systems allows upstream/downstream movements of aquatic migratory species. Multiple obstacles, partially or totally blocking upstream movements, promote cumulative non-additive impacts on freshwater fish. There are at least 1.2 million instream barriers in 36 European countries. It is important to assess the...

Effective research, conservation and management of freshwater ecosystems must take into con-sideration the environment, ecosystem functioning and human activities at multiple river scales. The river Network toolkit (RivTool) is a user-friendly and freely available software of universal applicability that enables the integration of these multiple in...

Special Session: Ecohydraulics 2021: Novel methods to investigate flow-biota interactions numerically, in the lab and in the field Abstract Rivers are affected by a vast number of artificial barriers that block fish movements within river networks, preventing several freshwater dependent fish species from completing their life cycle. Fish need to b...

Available information on diadromous fish species historical occurrences is generally biased and incomplete across species distribution range and spatial scales. This work aims to establish a new methodological framework (iPODfish – Inferring Past Occurrences of Diadromous Fish) to obtain a more complete representation of the historical occurrences...

South American hydrological network files for RivTool created based on the HydroAtlas layers.

Rivers are experiencing increasing anthropogenic pressures and salinity has shown to affect freshwater fish behaviour, potentially disrupting ecological processes. In this study, the aim was to determine the sub-lethal effects of salinization on freshwater fish behaviour, using a widespread native cyprinid species, the Iberian barbel (Luciobarbus b...

Citation: Segurado, P.; Ferreira, T.; Branco, P. Assessing the Effects of Multiple Stressors on Aquatic Systems across Temporal and Spatial Scales: From Measurement to Management. Water 2021, 13, 3549.

In Europe, freshwater fish are the richest group amongst European vertebrates and the second most threatened animal group, surpassed only by freshwater molluscs. The identification of threats is a major benefit for conservation efforts, as it allows actions to be bespoke to specific threats imperilling fish communities in sensitive areas. In this w...

Landscape perspectives in riverine ecology have been undertaken increasingly in the last 30 years, leading aquatic ecologists to develop a diverse set of approaches for conceptualizing, mapping and understanding ‘riverscapes’. Spatiotemporally explicit perspectives of rivers and their biota nested within the socio-ecological landscape now provide g...

The systematic literature review discusses several approaches that have been developed to improve the identification of barriers for connectivity enhancement.

Longitudinal connectivity in rivers is very important for freshwater fish, especially considering Diadromous species since it is determinant for life cycle completion. Large dams impose a serious fragmentation on river networks and affect diadromous species occurrence. This work aims to assess the structural and functional longitudinal connectivity...

Comprising 25% of vertebrates and 40% of all fish diversity, freshwater fish species are among the most threatened animal groups. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species is the most comprehensive system for evaluating species risk of extinction and provides information on the species’ populations, di...

Freshwater ecosystems are disproportionally important for biodiversity conservation, as they support more than 9% of known animal species while representing less than 1% of the Earth’s surface. However, the vast majority of the threats (99%, or 826 out of 837) identified by the International Union for Conservation of Nature Red List of Threatened S...

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment area...

Diversos estudos têm reportado sérias alterações nas comunidades piscícolas fortemente relacionadas com a presença de barreiras transversais ao longo dos cursos de água. Comparativamente com o conhecimento sobre os impactes nas populações piscícolas dos grandes empreendimentos hidráulicos, como as barragens, os pequenos açudes (< 5 m de altura) têm...

River longitudinal connectivity is crucial for diadromous fish species to reproduce and grow, its fragmentation by large dams may prevent these species to complete their life cycle. This work aims to evaluate the impact of large dams on the structural longitudinal connectivity at the European scale, from a Diadromous fish species perspective, since...

Requalification of low-head ramped weirs through the addition of substrates (retrofitting) has attracted attention in recent years. However, few studies are available on how this measure affects the negotiation of ramped weirs by fish. This study aimed to assess the performance of an experimental ramped weir (3.00 m long with 10% slope; 0.30 m head...

Pool-type fishways have been increasingly tested to improve fish passage performance and minimize migration delays. Designing cost-effective fishways is essential for a trade-off between water uses and successful longitudinal connectivity restoration. The multislot fishway (MSF) concept, which operates with 30–50% lower discharge than a vertical sl...

A participatory monitoring programme of an exceptional modification of urban soundscapes during Covid-19 containment.

This study describes an integrated modelling approach to better understand the trophic status of the Montargil reservoir (southern Portugal) under climate change scenarios. The SWAT and CE-QUAL-W2 models were applied to the basin and reservoir, respectively, for simulating water and nutrient dynamics while considering one climatic scenario and two...

Climate and land-use change drive a suite of stressors that shape ecosystems and interact to yield complex ecological responses, i.e. additive, antagonistic and synergistic effects. Currently we know little about the spatial scale relevant for the outcome of such interactions and about effect sizes. This knowledge gap needs to be filled to underpin...

Heatwaves, which can be defined as increases of at least 5 °C in air temperature for more than five consecutive days for a specified reference period, are expected to become more frequent under the ongoing climate change, with freshwater organisms being particularly vulnerable to high temperature fluctuations. In Mediterranean-climate areas, depend...

The addition of substrates to small instream obstacles, like low-head ramped weirs, has been considered a useful management solution to retrofit those structures and enhance fish passage. Substrate dimensions and spatial arrangement, together with discharge, and consequently water depths, appear as important factors for the creation of hydrodynamic...

Os pequenos açudes rampeados constituem um dos obstáculos fluviais mais comuns aos movimentos das espécies piscícolas. A transponibilidade destas estruturas, em que a água passa sobre as mesmas, mas não gera uma queda vertical, é sobretudo afetada pelo comprimento e declive da respetiva rampa. Contudo, a contribuição relativa destes fatores raramen...

Os pequenos açudes rampeados constituem um dos obstáculos fluviais mais comuns aos movimentos das espécies piscícolas. A transponibilidade destas estruturas, em que a água passa sobre as mesmas, mas não gera uma queda vertical, é sobretudo afetada pelo comprimento e declive da respetiva rampa. Contudo, a contribuição relativa destes fatores raramen...

Rivers are organized as dendritic networks, and river flow is the ruling force driving multiple functions and components of freshwater systems, meaning that the longitudinal dimension of connectivity is the most pertinent for the ecological processes involving fish species. For diadromous fish species and their life-cycle migratory requirements, th...

Agricultural intensification is currently considered as a major driver of worldwide biodiversity loss. EU-agro-environment policies were introduced to reduce biodiversity loss by subsidizing farmers that promote agricultural practices that are beneficial for climate and environment, by committing a percentage of productive farmland to Ecological Fo...

Rivers are organized as dendritic networks, and river flow is the ruling force driving multiple functions and components of freshwater systems, meaning that the longitudinal dimension of connectivity is the most pertinent for the ecological processes involving fish species. For diadromous fish species and their life-cycle migratory requirements, th...

Freshwater ecosystems and their surroundings are not only a hotspot for biodiversity but have also been used by man since early human settlements. Thus, searching for historical information about freshwater fish species prior to most of the greatest impactful human undertakings could lead to an improvement of species ecology knowledge. For example,...

Worldwide instream river barriers are disrupting river longitudinal connectivity and thus affecting fish species. The number of barriers is still increasing, especially in countries with emerging economies like Brazil, China and India. To circumvent the impacts of barriers and enhance connectivity, dam removal has gained momentum. Although the most...

Low-head ramped weirs are one of the most common small engineered structures present in Iberian rivers. Fish passability of these obstacles, where water passes over but does not generate a waterfall, is primarily related to ramp length and slope. However, the relative contribution of these factors has seldom been investigated. This study aims to as...

Numerous anthropogenic stressors impact rivers worldwide. Hypoxia, resulting from organic waste releases and eutrophication, occurs very commonly in Mediterranean rivers. Nonetheless, little is known about the effects of deoxygenation on the behavior of Mediterranean freshwater fish. To fill this knowledge gap, we assessed the impact of three diffe...

Low-head ramped weirs are a common instream obstacle to fish movements. Fish passability of these structures, where water passes over but does not generate a waterfall, is primarily related to ramp length and slope, but their relative contribution has seldom been considered. This study aims to assess the passage performance of a potamodromous cypri...

Wildfires are a common phenomenon in Mediterranean regions that is becoming increasingly frequent and severe, causing several environmental concerns, of which ash runoff represents an important source of disturbance for aquatic organisms, in particular for fishes. Studies on the behavioural response of fishes to wildfire ash runoff are scarce and s...

New engineering solutions are required to minimise the effects of an increasing number of anthropogenic barriers on watercourses. Longitudinal connectivity must be provided through fishways to allow free passage for the whole fish community. Recently, a multislot fishway (MSF) was developed, with two consecutive vertical slots that divide the overa...

Vertical-slot fishways (VSFs) are hydraulic structures which allow fish to swim around obstacles in rivers. These structures are subject to variations in discharge of either hydrological or operational origin, which result in nonuniform water depth profiles. These profiles are manifested as differences in the water drops across the slots (ΔH) and m...

The local flows within a fishway present a wide spectrum of hydrodynamic conditions and are themselves subject to the natural variability of the river they are connected to. Investigations of fish behavior under different flow scenarios in laboratory fishways can aid in identifying the statistically significant preferences of fish. Once patterns ha...

Fish require access to multiple habitats to persist. Therefore, obstacles blocking a fish's volitional ability to move between habitats can lead to its decline. A common way of addressing this problem is the construction of fishways. The design criteria of fishways are based on steady, uniform flows with the assumption that the water levels remain...

Freshwater ecosystems are some of the most endangered environments in the world, being affected at multiple scales by the surrounding landscape and human activities therein. Effective research, conservation and management of these ecosystems requires integrating environmental and landscape data with hierarchic river networks by means of summarisati...