Effects of hydropeaking and refuge configurations on the behaviour of cyprinids in experimental flume conditions

Doutoramento em Restauro e Gestão Fluviais (FLUVIO) - Instituto Superior de Agronomia / Faculdade de Arquitetura / Instituto Superior TécnicoFlow regime regulates the ecological integrity of river ecosystems, shaping the structure and function of fish communities. The discharge fluctuations in hydropower plants in response to peak electricity demand (i.e. hydropeaking) result in rapid flow changes in tailwaters. The continued hydropower operations produced morphological, hydraulic and water quality alterations, affecting downstream fish. Fish responses to hydropeaking range from organism to life-cycle event changes. It is challenging to establish a cause-effect relationship between flow variability and a fish response, and to propose adequate mitigation measures. In the first part of this research, a literature review was conducted to find evidence for that relationship. The review showed that flow variability can represent a stressor for fish. However, it remained unclear if the responses were maladaptive. In the second part, the effects of hydropeaking and refuges were assessed for L. bocagei in an indoor flume. A multidisciplinary approach was adopted, where fish responses were combined with a hydraulic characterization. Peak events were tested by manipulating magnitude, peak frequency and duration. The refuges were lateral (meandering and one-sided deflectors) and instream (triangular pyramids and v-shaped) structures, tested along three experimental campaigns. Glucose and lactate (secondary responses), and movement behaviour (whole-animal responses) were assessed. The flow field and fluid-body interactions were characterized by using acoustic Doppler velocimetry and an artificial lateral line probe respectively. The movement patterns of L. bocagei were diverse and not always proportional to the severity of the flow event. Lateral deflectors and v-shaped structures provided low velocity areas. However, the created flow complexity represented an additional constraint for fish, reducing their ability to find them. Flow thresholds that represented the resting state of L. bocagei were identified, and specific movement patterns were related with hydrodynamic changes. Practical recommendations for operational schemes and for the implementation of mitigation measures to hydropeaking were proposedN/

Impact of climate change on fish in regulated rivers: A review with a case study of the River Vuoksi

A literature review of climate change on salmonid fish species was made with a special interest on regulated rivers. As a case study, the effect of expected climate change on fish in the River Vuoksi was assessed. The overall impact of climate change on salmonids in the River Vuoksi was considered negative. Being a lowland river, maximum water temperatures in summer may already exceed critical limits for brown trout and landlocked salmon parr, and grayling at all life-stages. Expected increase in winter and early spring discharge of the River Vuoksi in the following decades was considered harmful especially for brown trout and landlocked salmon juveniles. Expected decrease in summertime discharge accompanied with low water velocities will aggravate the loss of riffle habitat preferred by Salmo spp. young especially in these restored riffle areas. In contrast to salmonids, several warm-water species (e.g., pikeperch and many cyprinids) dwelling mostly outside the few remaining rapids and riffles in the River Vuoksi are anticipated to benefit from the climate change. The River Vuoksi was considered to carry a special risk of a self-sustaining rainbow trout establishment in warming climate because of its southern location, expected changes in yearly discharge, relatively high and stable pH and large size of the river. Even without establishing a self-sustaining population, the widely detected spawning behavior of introduced rainbow trout with redd construction may be harmful to the reproduction of brown trout and landlocked salmon. Hence, stocking of put-and-take rainbow trout to the River Vuoksi was considered as a risk. As mitigation measures for the adverse effect of climate chance on the salmonid species can be suggested restoration of the existing riffles, increased connectivity and new reproduction areas by construction of bypass channels for the fish to pass dams, shadowing tree canopy to possible bypass channels, dampening of hydropeaking, and more effective control of the fishermen in obeying the fishing restrictions especially in the lower reaches of the River Vuoksi

Mitigating the impacts of river flow regulation and barriers to fish spawning migrations

Globally, migratory fish are threatened by anthropogenic modification to rivers. These create barriers that prevent fish accessing spawning grounds required for completion of life cycles. In order to make informed decsions, for mitigating the associated negative impacts, an understanding migratory behaviour when reaching barriers during the spawning migration is required. That said, there is a lack of information about the response of migratory fish to operational regimes in regulated rivers and the areas occupied, delays caused and routes taken around infrastructures. This study investigated the behaviour of three migratory fish species under operational regimes of three different infrastructures during each species’ respective spawning season. The efficiency of a bypass channel that utilised the relationship between migratory behaviour and flow was also investigated for a further species.The literature was reviewed to identify the different types of migratory life histories of fish, the impact of different riverine modification on the respective spawning migrations and how this can be mitigated. Fish have evolved in direct response to the natural flow regime and connectivity of riverine habitats, but barriers to migration exist from source to sea. This regulates or disrupts the flow regime and connectivity that fish depend upon, which has had considerable detriment to many migratory fish species globally. The main conclusion of the review was that knowledge gaps exist for the target species, and understanding the behaviour of the study species during the spawning migration is essential to improve access to spawning grounds in regulated rivers and ultimately conserve populations.The effects of timing, magnitude and duration of eleven artificial flow (freshet) releases from two impounding reservoirs on river-resident brown trout (Salmo trutta L.), a species known to undertake spawning migrations, was investigated using radio telemetry in a regulated upland river in northern England. Most did not perform movements characteristic of spawning migrations; all were located within 10 m of the location occupied before freshets, and fish in a control reach behaved comparably. The largest unidirectional movements mostly occurred during elevated river level due to rainfall and reservoir overtopping events; other varied length movements occurred during natural peaks or low flow, indicating artificial freshets were not directly responsible, and may not be suitable to stimulate migration in river-resident fish in regulated rivers.An acoustic telemetry study was conducted to determine the impact of a high- head hydropower station, associated diversion weir and spillway on downstream migrating shortfin eel (Anguilla australis) in the regulated Wairua catchment, Northland, New Zealand. Despite the diversion weir providing an alternative route, 88% (n = 21) of tagged eels that were detected here entered the power station forebay; of these, 52% were impinged onto intake screens, always when turbines were operating at greater than 3.04 MW/day. The rest (48%) passed the spillway and continued their migration, sometimes after long delays and having spent time immediately upstream of the intake where fitness could have been reduced due to high flows. Based on findings, the most effective mitigation here and at similar power schemes is considered to be operational or physical changes at the diversion weir to minimise entry of downstream migrating eels into the power canal during the migration period. Also discussed as potential solutions are turbine shutdowns, ensuring the spillway is available and provision of a bypass channel in the forebay.At a pumping station in the Anglian region, UK, where the upstream river level is maintained primarily by a co-located gravity sluice door, route choice and behaviour of downstream migrating European eel (Anguilla anguilla) (n = 7) immediately upstream of both routes was investigated using acoustic telemetry. During the study, three eels passed through pumps despite only operating for 8% of the time the gravity sluice was open, and only two passed through the gravity sluice after arriving when it was closed; the remaining two retreated upstream. No eels were detected within 15 m of the gravity sluice when it was open and eel behaviour was indicative of reluctance to pass through pumps. Findings are discussed in terms of water resource management to implement operational changes, to make the gravity sluice an attractive downstream passage route for migrating eels and thus reduce passage through hazardous pumps.The efficacy of two bypasses in attracting and passing downstream migrating American eels (Anguilla rostrata), designed to utilise the relationship between eel migratory behaviour and flow through two methods of flow creation, i.e. an airlift and a siphon, was tested in a simulated forebay environment, as a potential remediation measure at infrastructures requiring eel passage. Under entrance velocity of 1.2 m/s in eight test runs, both bypasses performed comparably and eels tested in each readily located, entered and passed. Test findings are discussed in relation to real-world application at sites with different characteristics, and the suitability of each design in successfully providing a safe route for downstream migrating eels

Novel Developments for Sustainable Hydropower

This open access book presents (selected) new and innovative developments for sustainable and fish-friendly hydropower. It offers unique insights into the challenges, practices and policies of hydropower developments across 8 European countries, providing examples from on-site studies and European-wide analyses. The case studies throughout the book are practical “real-world” examples, which are intended to serve as inspiration for anyone who would like to know more about how solutions for more sustainable hydropower production can be designed and implemented. Hydropower is an important renewable energy source, which, however, can also impact aquatic ecosystems, fish populations and hydro-morphology. EU and national water, environmental and energy legislation strive for sustainable energy and water resource management as well as the protection of important habitats and species. These have an effect on the requirements and decision making processes for hydropower planning, commissioning and operation. With a high variety of measures existing and site-specific conditions as well as national and EU level legal requirements to consider, it can be difficult to determine, what issues to address and which measures to implement

Go with the flow: managing rivers for migratory fish facing fragmentation and climate change

Doutoramento FLUVIO - River Restoration and Management / Instituto Superior de Agronomia / Instituto Superior Técnico / Faculdade de Arquitetura. Universidade de LisboaABSTRACT - Rivers harbour approximately 1100 migratory fish species, facing barriers to free movement, whether they are physical (dams and weirs) or determined by unfavourable habitat conditions. The main goal of this thesis was to evaluate the effect of flow and thermal changes in rivers caused by flow regulation, while also considering the ongoing climate change, to fish passability and swimming behaviour. This thesis is structured in a total of six chapters, with an introduction to the theme (Chapter 1) and four original works, including: (1) two case studies where fish passability through barriers equipped with a fishway was evaluated, in relation to different flows and other environmental variables (Chapter 2) and assuming different discharges under distinct climate change predictions (Chapter 3); and (2) two experimental studies, where swimming behaviour and activity were assessed in response to previous exposure to an experimental heatwave (Chapter 4) and rapid flow fluctuations as a consequence of hydropower generation (hydropeaking), coupled with abrupt thermal variations – cold thermopeaking (Chapter 5). Results from the first two chapters suggest that fishway efficacy is strongly dependant not just on a suitable flow regime (minimum ecological flows may be insufficient under drought scenarios), but also on other favourable habitat conditions such as water temperature, triggering upstream migration. In the experimental designs that were conducted, activity and boldness in juvenile barbel Luciobarbus bocagei were lower after exposure to a heatwave under laboratory conditions; for the other experimental study, the drift of nase Chondrostoma nasus larvae increased with cold thermopeaking. These results highlight the importance of ensuring suitable thermal regimes in rivers, namely by protecting sites that can act as thermal refugia for the most vulnerable life stages of migratory fish, and by monitoring and adjusting flow releases in dams to ensure that water temperature downstream does not change significantlyRESUMO - Os rios albergam cerca de 1100 espécies de peixes migradores a nível global, que enfrentam barreiras ao movimento, sendo estas físicas (barragens e açudes) ou determinadas por condições ambientais desfavoráveis. Esta tese teve como principal objetivo avaliar o efeito de flutuações de caudal e temperatura, causadas pela regularização de caudais, na transponibilidade de barreiras e comportamento natatório de peixes migradores nativos, considerando ainda o impacto que as alterações climáticas poderão ter nos ecossistemas ribeirinhos. A tese é constituída por um capítulo introdutório (Capítulo 1) e quatro trabalhos, incluindo: (1) dois casos de estudo, nos quais é determinada a transponibilidade de barreiras para várias espécies nativas em função de diferentes regimes de caudais e variáveis ambientais (Capítulo 2) e em cenários climáticos distintos (Capítulo 3); e ainda (2) dois ensaios experimentais, em que é avaliado o comportamento natatório dos peixes em resposta a ondas de calor (Capítulo 4) e rápidas flutuações de caudal resultantes da produção de energia hidroelétrica (hydropeaking) com descidas abruptas de temperatura – cold thermopeaking (Capítulo 5). Os primeiros dois capítulos sugerem que a eficácia das passagens para peixes está fortemente dependente não apenas de um regime de caudais adequado (podendo os caudais ecológicos mínimos ser insuficientes em contexto de seca), mas também de condições ambientais favoráveis, nomeadamente a temperatura dos rios. Nos ensaios realizados, a atividade e ousadia de juvenis de Luciobarbus bocagei foram menores após exposição a uma onda de calor; já a deriva de larvas de Chondrostoma nasus aumentou com o cold thermopeaking. Os resultados obtidos realçam a importância de manter regimes térmicos adequados nos rios, passando pela proteção de habitats ripícolas que atuem como refúgios térmicos para as fases mais vulneráveis dos peixes migradores, e pela monitorização das libertações de caudal nas barragens, por forma a não afetarem significativamente a temperatura dos rios a jusanteN/

Small-scale movement and migration cues of Australian bass (Percalates novemaculeata) in an urbanised river

Urban river catchments are often severely affected by human activities but may still retain significant biodiversity. Surprisingly little is known about the behaviour of urban fishes, even those popular with anglers. Key environmental variables that trigger fish behaviour, such as river flow, are highly affected by instream structures including weirs and changes in the natural flow regime. Here, we used acoustic telemetry to examine the movements of Australian bass in a river located in suburban Sydney, Australia. We found that fish tended to be nocturnally active, however, small-scale movements were highly idiosyncratic and less associated with river flow than other factors. Larger-scale movements associated with spawning migrations were strongly correlated with winter floods. Half of the tagged fish migrated to the confluence of the river with Sydney Harbour to breed. Their return migration was hampered by a weir, but the provision of a new fish way facilitated successful return to freshwater at high tide. Despite occupying a highly affected, urban catchment fish behaviour showed similarity to those occupying more natural drainages. Our results highlight the importance of maintaining natural river flows in urban catchments and sustaining fish movement and migration capabilities through the installation of appropriate fish passage devices

Riverine Ecosystem Management: Science for Governing Towards a Sustainable Future

This open access book surveys the frontier of scientific river research and provides examples to guide management towards a sustainable future of riverine ecosystems. Principal structures and functions of the biogeosphere of rivers are explained; key threats are identified, and effective solutions for restoration and mitigation are provided. Rivers are among the most threatened ecosystems of the world. They increasingly suffer from pollution, water abstraction, river channelisation and damming. Fundamental knowledge of ecosystem structure and function is necessary to understand how human acitivities interfere with natural processes and which interventions are feasible to rectify this. Modern water legislation strives for sustainable water resource management and protection of important habitats and species. However, decision makers would benefit from more profound understanding of ecosystem degradation processes and of innovative methodologies and tools for efficient mitigation and restoration. The book provides best-practice examples of sustainable river management from on-site studies, European-wide analyses and case studies from other parts of the world. This book will be of interest to researchers in the field of aquatic ecology, river system functioning, conservation and restoration, to postgraduate students, to institutions involved in water management, and to water related industries

Environmentally-sensitive river management : assessment and mitigation of impacts on urban rivers

Includes bibliographies.Urban development and engineering works have resulted in the majority of rivers that drain urban areas being severely degraded, both ecologically and in terms of their potential amenity value. This dissertation explores the reasons for this "spiral of degradation" and it describes the ecological and social impacts on rivers caused by urban development, channelisation and canalisation. It then suggests possible measures to mitigate the impacts at the levels of the catchment, floodplain and river channel. The present cycle of degradation of urban rivers in the Cape Metropolitan Area (and elsewhere) can be halted. In addition, where degradation has already occurred, mitigation and rehabilitation are possible and could restore some of the lost conservation and ecological values, as well as the potential amenity, recreation and education functions. Early colonisation of Cape Town by Europeans inflicted severe impacts on the rivers surrounding and passing through the city. These included: catchment degradation, water abstraction, the disposal of unpurified sewage and industrial effluents, removal of riparian forests, clearing of instream vegetation and the draining of wetlands. During the 20111 century, many urban rivers have been "improved" by straightening or confining within rectangular concrete-lined canals in order to protect urban development in flood-prone areas. The unquestioning faith in technology during this period and the attitude that human ingenuity could "improve nature" are now regarded by the scientific community, together with some local and regional authorities and informed members of the public, as mistakes that resulted in ecological and environmental degradation. These technical solutions merely treated the symptoms of the problem without recognising, let alone attempting to treat, the causes, that is poor catchment and floodplain management. However, there is still a public demand for canalisation of the remaining "natural" rivers in the greater Cape Town area and beyond. At the same time, there has been an increase in environmental awareness, as well as a growing appreciation of the value of holistic and multi-objective planning in the engineering and planning professions. This dissertation aims to assess the impacts of urbanisation, channelisation and canalisation on the aquatic ecosystem and socio-economic environment of urban rivers, and to develop possible measures to mitigate these impacts