John M. Nestler

Is fish passage technology saving fish resources in the lower La Plata River basin

Over 450 dams have been constructed in the upper Parana River basin in Brazil during the past 40 years. River regulation by these dams is considered a primary factor in the reduction of fish diversity and depletion of migratory species. In contrast to the upper Parana Basin, only two large dams (both with upstream fish passage) have been constructed in the lower La Plata River basin. Fishery managers in the lower basin are concerned that existing and planned dams will further deplete populations of migratory fish species that constitute important recreational and commercial fisheries as has occurred in the upper basin. We assessed the sustainability of fisheries in the lower basin in the face of increased river regulation by using literature information to describe the efficiency of the fish passage systems used to mitigate river regulation impacts on fisheries. Our analysis shows that fish passage systems at both lower basin dams, Yacyreta and Salto Grande, fail to transfer sufficient numbers of upstream migrants to sustain populations of migratory species. Fish passage efficiency of target species in the fish elevators at Yacyreta is less than 2%. Fish diversity in the fish elevators is low because about 85% of the fish belong to only three non-migratory species (Pimelodus maculatus, Oxydoras kneri and Rhinodoras dorbignyi). Large migratory species targeted for passage rarely comprise even 5 % of the fish number in the passage system. The two Borland locks at Salto Grande Dam cannot dependably pass large numbers of migratory species because passage efficiency is dependent upon interactions of powerhouse and spillway operation with tailrace elevations. Most species in the Borland system were either a small catfish (Parapimelodus valenciennis) or a engraulid (Lycengraulis grossidens). Again, the targeted migratory species were not abundant in the passage system. We conclude that existing fish passage technology in the lower basin is inadequate and that improved fish passage designs are required to conserve migratory species. These designs must be based on integrated information from geomorphology (habitat), natural fish behavior, fish swimming capabilities, and detailed population studies.

River stage response to alteration of Upper Mississippi River channels, floodplains, and watersheds

The Upper Mississippi River System (UMRS) is a large and diverse river system that changes character along its 1,200 mile network of rivers and canals and 2.6 million acres of floodplain. It supports more than 30 million people in its watershed, a significant commercial waterway, more than a million acres of “floodplain” agriculture and about one-half million acres of river-floodplain managed for fish, wildlife, and recreation. Large-scale geomorphology and climate patterns largely determine the hydrologic characteristics of a nested hierarchy of UMRS river reaches. The human impacts above are also important drivers determining hydrologic characteristics within the hierarchy. Understanding the relationship among physical and chemical processes and ecological responses is critical to implement an adaptive management framework for UMRS ecosystem sustainability. Historic or contemporary data from 42 locations were used to examine changes in UMRS hydrology and to demonstrate the utility of a multiple reference condition analysis for river restoration. A multivariate mathematical framework was used to show how river stage hydrology can be characterized by the variability, predictability, seasonality, and rate of change. Large-scale “geomorphic reaches” have distinct hydrologic characteristics and response to development throughout the UMRS region, but within navigation pool hydrology is similar among all impounded reaches regardless of geomorphic reach. Reaches with hydrologic characteristics similar to historic reference conditions should be examined to determine whether those characteristics support desired management objectives. Water levels can be managed, within limits to support navigation and agriculture, to more closely resemble natural hydrology for the benefit of a variety of species, habitats, and ecological processes.

Fish navigation of large dams emerges from their modulation of flow field experience.

Significance Whereas adult salmon swimming upstream through a ladder visibly illustrates the challenge a dam presents to fish returning home to spawn, the downstream passage of juveniles swimming toward the ocean is often a greater, although more unseen, challenge to their survival. Decades of work have identified many factors that affect fish behavior near dams, but why downstream passage structures may work well at one dam but not at another is poorly understood. We use a computer model to show that observed downstream passage patterns could result from a generic strategy that fish may use to navigate flow field obstacles. Our findings identify environmental and biological factors warranting further evaluation for sustaining native species amid economic development. Navigating obstacles is innate to fish in rivers, but fragmentation of the world’s rivers by more than 50,000 large dams threatens many of the fish migrations these waterways support. One limitation to mitigating the impacts of dams on fish is that we have a poor understanding of why some fish enter routes engineered for their safe travel around the dam but others pass through more dangerous routes. To understand fish movement through hydropower dam environments, we combine a computational fluid dynamics model of the flow field at a dam and a behavioral model in which simulated fish adjust swim orientation and speed to modulate their experience to water acceleration and pressure (depth). We fit the model to data on the passage of juvenile Pacific salmonids (Oncorhynchus spp.) at seven dams in the Columbia/Snake River system. Our findings from reproducing observed fish movement and passage patterns across 47 flow field conditions sampled over 14 y emphasize the role of experience and perception in the decision making of animals that can inform opportunities and limitations in living resources management and engineering design.

Simulating Movement Patterns of Blueback Herring in a Stratified Southern Impoundment

Abstract J. Strom Thurmond Lake (Georgia-South Carolina) strongly stratifies during the summer, producing a temperature-dissolved oxygen “squeeze” for landlocked blueback herring Alosa aestivalis. A coupled Eulerian-Lagrangian hybrid (CEL hybrid) model was developed to improve understanding of and better predict the in-reservoir movements of blueback herring in response to these limiting conditions. An existing application of CE-QUAL-W2, a two-dimensional, laterally averaged water quality and hydrodynamic model, was used to simulate the spatial and temporal dynamics of summer water temperature, dissolved oxygen, and hydraulics. The biological module was parameterized by using mobile hydroacoustic survey data supplemented with species composition data from gill-net surveys. The simulation accurately described the longitudinal (r 2 = 0.67) and vertical (r 2 = 0.93) distributions observed for blueback herring. The model results suggest that the longitudinal distribution of blueback herring in summer is best ...

Describing scales of features in river channels using fractal geometry concepts

Quantitative description of spatial patterns is often at the heart of ecological research in aquatic systems, particularly for investigations of how biota respond to physical habitat. A common first step for approximating a river channel is tessellation, or the discretization of the channel into cells of approximately uniform size, and assigning each cell a representative value for velocity or other characteristics. More innovative methods may use the fractal dimension to characterize patterns of features in spatially complex geological structures, such as channel bed forms. Unfortunately, these methods lose information because they either force continuous data into a grid framework or assume that complexity is constant over a range of scales. The current understanding of aquatic processes would improve if information about the scale of channel features could be preserved throughout the analysis instead of being discarded in the first step because simplifying assumptions were used. New methods are presented that characterize complex spatial data sets with minimal use of assumptions or simplifying approximations. The new methods identify dominant features in a set of coordinate data, locate the positions of such features in the cross section, describe how kinetic energy is distributed in these features, and quantify how features of different scales relate to one another. The effectiveness of this technique on mathematical constructs having known characteristics is demonstrated. The methods are then used to describe a Missouri River cross section before and after river regulation to illustrate how the methods can be used to quantify changes in physical habitat patterns that may not be apparent using other methods. Improved description of complex shapes in aquatic environments may lead to increased understanding of aquatic processes in general, and in particular, the way aquatic organisms relate to physical habitat. Copyright

Can north american fish passage tools work for South american migratory fishes

Na America do Norte, o Numerical Fish Surrogate (NFS) e utilizado no projeto de sistemas de transposicao de juvenis de salmao em seus deslocamentos dos habitats de desova e desenvolvimento inicial para o de adultos, no oceano. O NFS e estruturado em tres modulos interconectados: 1) um modelo computacional de dinâmica de fluidos (CFD) que descreve o complexo escoamento acima da barragem em uma escala suficientemente apropriada para analisar, entender e prever os movimentos dos peixes, 2) um modelo de rastreamento de particulas que interpola informacoes hidraulicas dos nos da malha do modelo computacional para localizacoes multiplas relevantes ao peixe em migracao, 3) um modelo comportamental que simula o conhecimento e o comportamento de cada peixe em resposta a dinâmica do escoamento predita pelo modelo computacional. Esses tres modulos juntos criam uma realidade virtual onde peixes virtuais exibem um comportamento realistico de aproximacao da barragem e podem ser contados de uma forma similar a do mundo real. Uma vez calibrado e validado com medicoes do movimento dos peixes e dados de passagem, o NFS pode predizer acuradamente a proporcao de passagem de peixes, com suficiente precisao para permitir que engenheiros selecionem uma alternativa otima dentre as varias opcoes estruturais e operacionais. Embora as especies de peixes Sul Americanas sejam diferentes das especies da America do Norte, e provavel que a arquitetura computacional basica e os metodos numericos do NFS possam ser usados para a conservacao de peixes na America do Sul. Consequentemente, o grande investimento feito na criacao do NFS nao precisa ser repetido na America do Sul. Contudo, seu uso na America do Sul exigira que a resposta comportamental dessa fauna aos sinais hidrodinâmicos seja descrita, codificada e testada antes que o NFS possa ser usado na conservacao de peixes pelo seu emprego na projecao de sistemas de transposicao eficientes. Nesse contexto, o presente trabalho identifica estudos que poderiam ser utilizados para descrever o comportamento migratorio de peixes da America do Sul com um nivel de detalhamento suficiente para que possa ser utilizado no desenvolvimento, calibracao e validacao de uma versao sul-americana do NFS.

Quantitative methods to direct exploration based on hydrogeologic information

L. J. Weber (corresponding author) IIHR Hydroscience & Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242-1585, USA Tel:+1 319 335 5597; E-mail: larry-weber@uiowa.edu R. A. Goodwin Research Environmental Engineer, Environmental Laboratory, US Army Engineer Research & Development Center, CENWP-EC-HD, 333 SW 1st Ave, PO Box 2946, Portland, OR 97208, USA Tel:+1 503 808 4872; E-mail: rag12@cornell.edu S. Li IIHR Hydroscience & Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242-1585, USA Tel:+1 319 335 6061; E-mail: songheng-li@uiowa.edu J. M. Nestler Environmental Modeling & System-Wide Assessment Center (CEERD-IV-Z), US Army Engineer Research & Development Center, 3909 Halls Ferry Rd, Vicksburg, MS 39180-6199, USA Tel:+1 601 634 2720; E-mail: john.m.nestler@erdc.usace.army.mil J. J. Anderson School of Aquatic & Fishery Sciences, University of Washington, 1325 4th Ave., Suite 1820, Seattle, WA 98101, USA Tel:+1 206 543 4772; E-mail: jim@cbr.washington.edu The Eulerian–Lagrangian–Agent method (ELAM) couples three modelling approaches into a single, integrated simulation environment: (i) Eulerian descriptions, (ii) Lagrangian formulations, and (iii) agent reference frameworks. ELAMS are particularly effective at decoding and simulating the motion dynamics of individual aquatic organisms, using the output of high fidelity computational fluid dynamics (CFD) models to represent complex flow fields. Here we describe the application of an ELAM to design a juvenile fish passage facility at Wanapum Dam on the Columbia River in the United States. This application is composed of three parts: (1) an agent-based model, that simulates the movement decisions made by individual fish, (2) an Eulerian CFD model that solves the 3D Reynolds-averaged Navier–Stokes (RANS) equations with a standard k–1 turbulence model with wall functions using a multi-block structured mesh, and (3) a Lagrangian particle-tracker used to interpolate information from the Eulerian mesh to point locations needed by the agent model and to track the trajectory of each virtual fish in three dimensions. We discuss aspects of the computational mesh topology and other CFD modeling topics important to this and future applications of the ELAM model for juvenille salmon, the Numerical Fish Surrogate. The good match between forecasted (virtual) and measured (observed) fish passage proportions demonstrates the value-added benefit of using agent-based models (i.e. the Numerical Fish Surrogate model) as part of common engineering practice for fish passage design and, more fundamentally, to simulate complex ecological processes.

Relating Turbulence and Fish Habitat: A New Approach for Management and Research

Understanding how fish perceive turbulence characteristics to utilize complex habitats (large wood, rock, channel bedforms, etc.) is a critical, but poorly understood component of aquatic habitat restoration. Many recent studies attempt to relate turbulence characteristics to habitat utilization, but results are inconsistent for two reasons. First, turbulence is a complex, multi-scale manifestation of fluid flow that can be characterized in different ways with different interpretations. Second, fish behavioral response to flow field features is also complex because both acclimation and learning are important. For example, some studies show that turbulence decreases swimming stability, increases energy expenditure for a given swimming speed, and alters feeding behavior, whereas others show turbulence to decrease energy needed to swim at a given speed and correlates with fish abundance. We describe a Turbulence Attraction and Avoidance (TAA) hypothesis to reconcile inconsistent, even seemingly contradictory, findings. The TAA hypothesis creates a new perspective of turbulence, habitat complexity, and fish habitat occupancy by acknowledging that fish, like all animals, perceive their environment at their own relevant scales and in a conditional manner, dependent on their prior exposure history.

Contrasting the Middle Paraná and Mississippi Rivers to develop a template for restoring large floodplain river ecosystems

Abstract Effective rehabilitation of large rivers requires a concept of normal floodplain river behavior ‐ the reference condition ‐ to understand system‐level disturbance history and to develop plans to improve river health. However, reference conditions are difficult to obtain for large rivers. Using Correspondence Analysis of a select subset of the worlds great rivers, we show that the Paraná and Mississippi Rivers are relatively similar at the watershed scale based on general geographical and physico‐chemical variables, although these rivers differ substantially in disturbance history. We believe that the less disturbed Paraná River provides reference conditions for the more disturbed Mississippi River for some processes and functions whereas the Mississippi River provides a compelling vision of the future state of the Paraná River unless sustainable development plans are developed and implemented. By integrating information between them, this pair of rivers provides a unique opportunity for scientists to develop more robust conceptual models and improved deterministic models to better guide river management and rehabilitation actions. We suggest that development of large river reference conditions may be better obtained through expanded inter‐hemispheric scientific collaboration on multiple systems than through increased focus on a single impacted system.

Ecohydraulics exemplifies the emerging “paradigm of the interdisciplines”

ABSTRACT The basic premise underlying ecohydraulics is deceptively simple: create a new discipline focused on the effects of water movement in aquatic ecosystems by melding principles of aquatic ecology (including aspects of fluvial geomorphology) and engineering hydraulics. However, advancing ecohydraulics as a synthetic, organized field of study is challenging because hydraulic engineers and ecologists (1) study processes that differ substantially in spatial and/or temporal scale; (2) have very different approaches to modelling; (3) utilize different sets of mathematical formulations, concepts, and assumptions; and (4) address problems with vastly different patterns of complexity and uncertainty. The differences between engineering and ecology must be reconciled within a set of concepts and practices applicable to ecohydraulics. This reconciliation is essential if ecohydraulics is to achieve the scientific esteem of its parent disciplines. First, we review how the competing paradigms of determinism and empiricism structure engineering and ecology, respectively. We then derive two guiding principles that facilitate the integration of ecology and hydraulics, the single reference framework and the multiple reference framework guiding principles. Third, we provide illustrative examples of these principles using a simple hydraulic fish habitat analysis based on physical habitat simulation (PHABSIM) system of the instream flow incremental methodology (IFIM) and a detailed fish movement model using Eulerian–Lagrangian–Agent methods (ELAMs). Based on these examples, we develop insights and conclusions to guide further advances in ecohydraulics and, perhaps even serve as a template to aid development of other interdisciplinary fields.