Geology topics

Jeffrey J. Duda

Publications and source records attributed to Jeffrey J. Duda.

At least 19 recordsLinked to original sources

USGS2026

DRIFteRS: A dataset of drift invertebrate densities in streams and rivers across western North America, 1997–2024

Prey availability is among the most influential and highly variable determinants of fish growth and freshwater habitat carrying capacity, yet it remains understudied compared to physical habitat variables (Ouellet et al., 2025; Rosenfeld et al., 2014; Weber et al., 2017). We often lack a clear understanding of how much food is available to fishes, how it varies spatially and temporally, and how it influences responses to restoration (Ouellet et al., 2025; Rossi et al., 2024; Wipfli et al., 2010). Drift invertebrates—the primary food source for juvenile salmonids and other drift-foraging fishes—play a pivotal role in these dynamics. To better understand the spatiotemporal variability of drift invertebrate abundance and biomass across the freshwater range of drift-feeding salmonids in western North America, we compiled the DRift Invertebrates For salmonids in River Systems (DRIFteRS) dataset. The dataset encompasses 6125 samples of drift invertebrates, and, for a subset of drift samples, associated benthic invertebrate density data, collected from 1360 reaches on 459 unique rivers and streams spanning 55 river basins considered hydrologically independent (i.e., not nested within the same larger watershed) across British Columbia, Canada, and the U.S. states of Alaska, Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. Sample sites represent a diverse array of river and stream habitats (e.g., headwater, mainstem, side channel), in watersheds with diverse land uses (e.g., urban, wilderness, agricultural), and disturbance histories (e.g., fire, restoration). Collected between 1997 and 2024, the data span the full calendar year and capture daily and seasonal patterns in drift abundance and biomass densities. When paired with water quality and quantity data as well as remotely sensed environmental landscape data, such as land use/land cover, climate, and disturbance history, channel morphology, and riparian vegetation composition, the DRIFteRS dataset can aid in identifying key drivers of drift invertebrate densities and mean body size and support predictive modeling in unsampled locations and times. The dataset may also be used to analyze aquatic-terrestrial resource flows, derive prey-encounter rates and profitability (mean prey size), and inform broader investigations of sit-and-wait foraging ecology, especially when paired with data on drift-foraging predators. For salmonid-focused applications, the dataset can be integrated into habitat evaluation models, including bioenergetic (e.g., Naman et al., 2019) and life cycle models (e.g., Beechie et al., 2023), to improve estimates of habitat capacity and population dynamics for river- and stream-rearing salmonids. Understanding prey availability dynamics is increasingly important, because rising water temperatures increase salmonid metabolic demands (Crozier et al., 2010). Flow regime transitions (i.e., snow or glacier dominated to rain dominated; Beechie et al., 2013), wildfire frequency and intensity (Hessburg et al., 2021), as well as plant community and phenology shifts (Cleland et al., 2007; Franklin et al., 2016) are all predicted to change with rising temperatures and are potential drivers of terrestrial and aquatic invertebrate prey quality and availability in lotic systems. These insights can ultimately inform restoration prioritization and design, helping managers consider food resource implications when evaluating restoration priorities and match habitat improvement to food supply. The data are released under the Creative Commons Attribution 4.0 International license and may be reused with attribution.

Alaska, Arizona, British Columbia, California, Col↗

USGS2026

Fisheries sustainability: Perceptions from the ninth World Fisheries Congress

The World Fisheries Congress (WFC) is one of the largest global gatherings of fisheries professionals and scientists. It is held every 4 years with the purpose of sharing ideas and perspectives about new research, emerging issues, scientific breakthroughs, and governance related to fisheries science, industry, conservation, and management. The ninth WFC, held in Seattle (USA) in 2024, focused on fish and fisheries at the food–water–energy nexus and understanding fisheries sustainability from diverse perspectives. Fisheries sustainability is a goal shared globally that faces challenges across spatial scales from the implementation of good governance and accelerating anthropogenic pressures. Leveraging the unique opportunity to gain insights from WFC delegates, this study assesses perceptions of fisheries sustainability from diverse representation across career stage, geographic region, and professional and cultural backgrounds. Survey results show that respondents (i.e., WFC delegates who chose to take the survey) perceived limited progress towards fisheries sustainability, often with a variable and unclear definition of what sustainability entails. Fish were primarily valued from a provisioning resource perspective, with environmental aspects of fisheries management and conservation seen as the area with the most progress and the greatest needs, rather than economic or social dimensions of fisheries.

Fisheries↗

USGS2026

Unveiling a legacy of fish introductions to mountain lakes using historical records and eDNA surveys in a National Park

Across the western United States, introductions of non-native fish into historically fishless mountain lakes have impacted native biota. Understanding the impacts of fish introductions is essential for conservation in Olympic National Park, a Biosphere Reserve. We reconstructed fish plantings using records dating back to 1930, followed by environmental DNA (eDNA) surveys to estimate the current distribution of fish and amphibians in 117 remote mountain lakes. We used Bayesian multiscale occupancy models to determine how lake attributes and planting history related to fish and amphibian occupancy. The most frequently detected species were Brook Trout, Rainbow Trout, Cascades Frog, and Northwestern Salamander. eDNA sampling revealed 52 lakes with amphibians only, 45 with fish and amphibians, 14 with fish only, and 6 unoccupied. Of the 53 lakes with planting records, 38 had fish eDNA detected. Fish eDNA was also detected in 21 lakes lacking planting records, which could reflect incomplete records, unauthorized plantings, and false positive detections. Of the three species planted, Cutthroat Trout had the highest failure rate and did not become established in 23 of 28 historically planted lakes. In a subset of 9 lakes sampled for up to 7 years, those with known fish and amphibian presence showed consistent eDNA detections over time. The number of times a lake was stocked was the best predictor of occupancy for Brook and Rainbow trout, while higher occupancy for Brook Trout was also associated with lower elevations, lower solar radiation, and larger lake area. We did not observe widespread negative associations between amphibian occupancy and fish presence, although there was a negative relationship between fish presence and Rough-skinned Newt and Long-toed Salamander occupancy. Cascades Frog occupancy showed no relationship to fish presence or lake traits. Our results suggest mechanisms of fish persistence over time and highlight areas where native amphibians are impacted by introduced fish. These results can guide management options like targeted fish removals that benefit native fauna while still supporting recreational fishing. More broadly, our work demonstrates the value of combining historical records with contemporary surveys and the utility of eDNA for broad-scale surveys of species distribution in remote wilderness areas.

Washington↗

USGS2025

A molecular specimen bank for contemporary and future study captures landscape-scale biodiversity baselines before Klamath River dam removal

Global restoration and conservation of freshwater biodiversity are represented in practice by works such as the Klamath River Renewal Project (KRRP), the largest dam removal and river restoration in the United States, which has reconnected 640 river kilometers. With dam removals, many biological outcomes remain understudied due to a lack of pre-impact data and complex ecosystem recovery timeframes. To avoid this, we created the KRRP molecular library, an environmental specimen bank, for long-term curation of environmental nucleic acids collected from the restoration project. We used these initial samples, environmental DNA metabarcoding, and generalized linear mixed-effects models to evaluate patterns of pre-dam removal fish richness and diversity. Demonstrating the suitability to resolve biological differences, the baseline shows that tributary and mainstem streams had greater native fish diversity and 2.3–10.7 times greater native fish species richness than reservoirs. These and future sampling efforts should, at a minimum, allow tracking of fish community response to ecosystem restoration. Anticipating the acceleration of omics innovation, we preserved samples for long-term storage and identified requisite phases for sustained function and adaptation of the molecular library: securing a physical storage facility for genetic material, establishing a governance structure, and confirming support for archive management.

California, Oregon↗

USGS2024

Large-scale dam removal and ecosystem restoration

Rivers underpin vital ecosystems that support aquatic and terrestrial biodiversity and many ecosystem services, including food, water, culture, and recreation ( Dudgeon et al. 2006 ). After centuries of building dams on rivers across the world, river restoration via dam removal is receiving increased public attention, financial investment, and scientific study because of various issues of regarding dam infrastructure, such as obsolescence, sedimentation, and ecosystem degradation ( Duda and Bellmore, 2022 ; East and Grant, 2023 ). Most dam removal projects to date have focused on smaller structures, but larger structures > 10 m tall have also started to be removed in increasing numbers. Recent estimates suggest that only a small fraction of all dam removals have been scientifically studied, with most focused on small dams and short time scales ( Bellmore et al., 2016 ). Understanding the outcomes of large dam removal, where case studies are much more limited, depends on sustained research and monitoring efforts aimed at understanding restoration processes over large spatial and temporal scales ( Figure 1 ). The ecological and socio-ecological study of large dam removal represents a new frontier in dam removal research: projects are larger, more recent, and provide an opportunity to understand the complex ecological changes and impacts to humans that occur with these transformative restoration projects.

Frontiers in Ecology and Evolution↗

USGS2024

Challenges of implementing a multi-agency monitoring and adaptive management strategy for federally threatened Chinook salmon and steelhead trout during and after dam removal in the Elwha River

Adaptive management, a process of planning, implementing, and evaluating management strategies, is often recommended for monitoring ecological systems. However, few examples of successful implementation and retrospective case studies exist. We provide a case study of adaptively managing hatchery-assisted protection and recovery for Chinook salmon ( Oncorhynchus tshawytscha ) and winter steelhead trout ( O. mykiss ) during and after the removal of two large mainstem dams in the Elwha River, WA. We summarize key aspects of the monitoring and adaptive management plan over the last decade and highlight successes, challenges, and complications during the plan’s implementation. The Elwha Monitoring and Adaptive Management Guidelines included a trigger-based system for moving through four phases of recovery that included preservation, recolonization, local adaptation, and viable natural population, each with differing levels of hatchery production as the management actions. The monitoring component of the plan has been very successful, providing critical data to guide management actions that otherwise may not have occurred and, opportunistically, provided data for other native species in the Elwha River. Implementing adaptive management provided mixed results and was at times hindered by divergent management goals among project partners, the inflexibility of the Endangered Species Act regulatory requirements as implemented for this project, and conflicting information among guidance documents. We learned that some metrics and triggers in the plan were ill-defined or too difficult to measure in the field. In some cases, the performance indicators and/or triggers were successfully modified to incorporate what was learned; however, in other cases, we were unable to revise the values due to differing opinions among partners. The ability to reach consensus on revised triggers appeared to be influenced by the recovery trajectory of the species involved. The implemented adaptive management strategy resulted in substantial collaboration and learning, which resulted in revised management strategies, but was imperfect. Sufficient long-term funding is necessary to implement a well-designed monitoring program and could benefit from including a defined leadership position to shepherd and facilitate a multi-stakeholder adaptive management program. Additionally, incorporating adaptive management into legally binding conditions under the Endangered Species Act is feasible, but requires substantial pre-planning in close coordination with regulatory agencies.

Washington↗

USGS2024

Prey supply and predation as potential limitations to feasibility of anadromous salmonid introductions in a reservoir

Introducing anadromous fish upstream of migration barriers has frequently been proposed as a conservation strategy, but existing conditions and future changes to the ecosystems above barriers such as invasive species, climate change, and varying water operations influence the capacity to support such introductions. In the Upper Skagit River, Washington, USA, introduction of anadromous salmonids above three high-head dams was proposed; however, the proliferation of invasive redside shiner Richardsonius balteatus fundamentally altered reservoir food web interactions, presenting potential challenges for the growth and production of introduced anadromous salmonids. By combining empirical measurements of zooplankton availability and temporal patterns in thermal structure of the reservoir with bioenergetics model simulations to quantify the rearing capacity of Ross Lake, we estimated the lake could support millions of sockeye salmon fry entering in spring after accounting for temporal consumption demand by the existing planktivore community dominated by redside shiner. The initial fry estimates varied according to the expected fry-to-smolt survival rate, and whether salmonids would be thermally restricted from prey in the epilimnion. This translated to estimates of 189,000 to 285,000 smolts leaving the following spring, and 7700 to 11,700 returning adults, using mean fry-to-smolt and smolt-to-adult survival rates from a nearby sockeye salmon population. We also estimated that predation potential could pose substantial mortality for lake-rearing sockeye or Chinook salmon, although it is expected to play a lesser role in limiting survival of species that only migrate through the reservoir. These results provide a case study and framework for examining bottom-up and top-down food web processes that influence growth and survival of introduced anadromous salmonids in reservoir habitats, thus guiding the direction of future feasibility studies in Ross Lake and other regulated rivers where introduction programs are considered.

Washington↗

USGS2024

Dam removal cost databases and drivers

The United States (U.S.) has over 90,000 dams listed in the National Inventory of Dams that provide vital infrastructure to support water management for municipal and industrial uses including irrigation, hydropower, flood control, navigation, recreation, and habitat, among other uses (NID 2023). The Bureau of Reclamation (Reclamation) and U.S. Army Corps of Engineers (USACE) operate and maintain approximately 489 and 740 dams, respectively, as well as associated structures which provide flood risk management, navigation, water supply, hydropower, environmental stewardship, fish and wildlife conservation, and recreation benefits. As dams age, structural and operational maintenance investments increase until a time when decisions on whether to rehabilitate, replace, or decommission the dam need to be made. While most dams continue to provide important value even with maintenance requirements, at least 2,000 dams have been removed in the U.S. during the past 110 years, with an upward trend in the last few decades (American Rivers 2023). Decommissioning a dam may be considered when the purpose of the dam is no longer needed or other factors such as dam safety, fish passage, recreation safety, or river restoration goals take higher priority and are more economically feasible for the dam owner long-term. Dam safety programs, river restoration programs, and asset class management programs need cost estimating methods to consider dam decommissioning when appropriate. Traditional cost estimating approaches in planning stages focus mainly on dam removal construction and may leave out or have uncertainty on important complexities that can have substantial effects on total costs and be critical for project success. As the numbers of dam removal case studies increase, a growing set of cost data has become available (Duda et al. 2023a; Tullos and Bountry 2023; American Rivers 2022). However, total costs vary over five orders of magnitude for similar size dams, and it was unclear why. We evaluated three sets of cost data that had varying level of details regarding elements contributing to dam removal costs reported by project managers working on the dam removal studies and construction means and methods. We created planning-level cost estimating tools to assist with projects needing to consider the dam removal alternative: (1) new databases of case studies (Duda et al. 2023a; Tullos and Bountry 2023); (2) scoping questions to help determine if complexity cost drivers will be present; (3) machine learning based regression trees to estimate a potential cost range; and (4) a Computation Guide for Cost Estimating that can be used to inform discussions on potential dam removal cost items, quantities, and unit costs (appendix A). The collected data showed that dam height is important but is not a reliable predictor of the removal cost without considering other elements. However, knowing some basic characteristics about the average annual flow and geographic location of the dam site, in addition to dam size, can improve the ability to use past case studies for planning-level cost estimating. By additionally incorporating scoping questions related to sediment removal, mitigation, or other infrastructure, the likelihood of complexity cost drivers and the initial uncertainty of a cost estimate can be further reduced especially for small dams. Applying the Computation Guide for Cost Estimating requires more robust information but helps users reduce cost uncertainty. This step further refines the dam removal objective, removal approach (partial or full; phased or instantaneous), engineering design, construction means and methods, quantities, and unit costs, and results in a quantitative cost estimate.

Final Report↗

USGS2023

Applying intrinsic potential models to evaluate salmon (Oncorhynchus spp.) introduction into main-stem and tributary habitats upstream from the Skagit River Hydroelectric Project, northern Washington

We assessed habitat suitability for salmonids across selected tributaries upstream from three hydroelectric dams on the upper Skagit River in Whatcom County, northern Washington. We used NetMap, a commercial toolset within the ArcMap geographic information system (GIS), to analyze stream attributes based upon a synthetic stream channel network derived from digital elevation models. The GIS-derived stream attributes—including gradient, bankfull width, valley width index, elevation, and stream flow—allowed us to examine the spatial distribution and relative quality of spawning and rearing habitat for salmonids based on existing intrinsic potential (IP) models. As a first step, we created maps of potential anadromous fish distribution by identifying potential migration barriers within the synthetic stream network. Next, we applied a suite of existing IP models for steelhead, coho, and Chinook salmon ( Oncorhynchus mykiss , O. kisutch , and O. tshawytscha , respectively) to estimate low, medium, and high IP habitat for each species. Three different IP models were used for each species, based on species preference curves from populations from coastal Oregon, northern California, Alaska, and western Washington. We found that at least 25 tributaries that were greater than third order and contained habitat with the potential for anadromous fish, totaling about 470 river kilometers in 4,453 synthetic stream reaches averaging about 100 meters (m) in length. The IP of each of these reaches was calculated and placed into low, medium, and high IP categories. For Chinook salmon, the only stream with significantly (in other words, greater than 1 kilometer [km]) high IP reaches was the upper Skagit River upstream from Ross Lake reservoir in Canada, upstream from the third dam in the hydroelectric system. There were differences among the three models evaluated, with the model derived for the lower Skagit River showing more high and medium IP habitat than the other two models that were designed for the Columbia River Basin. For coho salmon, all three models showed similar results favoring medium IP over low and high IP habitat. Of the 3 species examined with existing IP models, steelhead had the most habitat rated as high IP with 19 targeted tributaries showing greater than 1 km of high intrinsic potential habitat.

Washington↗

USGS2023

Leaf litter decomposition and detrital communities following the removal of two large dams on the Elwha River (Washington, USA)

Large-scale dam removals provide opportunities to restore river function in the long-term and are massive disturbances to riverine ecosystems in the short-term. The removal of two dams on the Elwha River (WA, USA) between 2011 and 2014 was the largest dam removal project to be completed by that time and has since resulted in major changes to channel dynamics, river substrates, in-stream communities, and the size and shape of the river delta. To assess ecosystem function across the restored Elwha watershed, we compared leaf litter decomposition at twenty sites: 1) four tributary sites not influenced by restoration activities; 2) four river sites downstream of the upper dam (Glines Canyon Dam); 3) four river sites within the footprint of the former Aldwell Reservoir upstream of the lower dam (Elwha Dam); 4) four river sites downstream of the lower dam; and 5) four lentic sites in the newly developing Elwha delta. Three major findings emerged: 1) decomposition rates differed among sections of the Elwha watershed, with slowest decomposition rates at the delta sites and fastest decomposition rates just downstream of the upper dam; 2) aquatic macroinvertebrate communities establishing in leaf litterbags differed significantly among sections of the Elwha watershed; and 3) aquatic fungal communities growing on leaf litter differed significantly among sections. Aquatic macroinvertebrate and fungal diversity were sensitive to differences in canopy cover, water chemistry, and river bottom sediments across sites, with a stronger relationship to elevation for aquatic macroinvertebrates. As the Elwha River undergoes recovery following the massive sediment flows associated with dam removal, we expect to see changes in leaf litter processing dynamics and shifts in litter-dependent decomposer communities (both fungal and invertebrate) involved in this key ecosystem process.

Washington↗

USGS2023

Growth performance of Rainbow Trout in reservoir tributaries and implications for steelhead growth potential above Skagit River dams

Objective In the Pacific Northwest (USA), Pacific salmon Oncorhynchus spp. populations have been declining significantly for decades, prompting stakeholders to respond with a variety of conservation and restoration measures. One such measure being considered in the Skagit River basin (Washington, USA) is the introduction of steelhead Oncorhynchus mykiss (anadromous Rainbow Trout) above the impassable Gorge, Diablo, and Ross dams to bolster their populations. Because freshwater growth is key to survival at subsequent life stages, we evaluated current trends in size and growth of Rainbow Trout among key tributaries to Gorge, Diablo, and Ross reservoirs using empirical data collection and bioenergetics modeling. Methods For nine candidate streams, a bioenergetics model was used to assess how temperature and prey consumption affected growth performance of Rainbow Trout between annuli 1 and 2, and 2 and 3. Thermal scenarios were created to evaluate how fish growth responded to temperature variability while total annual consumption was constrained within empirical growth estimates. We then compared these results to back-calculated size thresholds established by size-at-age observed in wild steelhead adults that returned to the Skagit River below the dams. Result Of the streams proposed for introductions, there was one instance (McMillan Creek) in the nominal simulations where growth met or exceeded the size at annulus 2 or 3 of a returning adult steelhead (24.9 g at annulus 2 and 50.3 g at annulus 3). Modeled growth under different thermal scenarios showed that colder temperatures (0.1–10.7°C, Canyon Creek) produced higher growth than under the nominal or warm scenarios (2.0–15.3°C, Canyon Creek), as well as one additional tributary where size at annulus 2 or 3 (±2 SE) was comparable to the threshold established by adult steelhead below the dams (Big Beaver Creek, annulus 3). Conclusion These results suggest Rainbow Trout growth is most limited by prey availability in the examined upper Skagit tributaries.

Washington↗

USGS2023

Patterns, drivers, and a predictive model of dam removal cost in the United States

Given the burgeoning dam removal movement and the large number of dams approaching obsolescence in the United States, cost estimating data and tools are needed for dam removal prioritization, planning, and execution. We used the list of removed dams compiled by American Rivers to search for publicly available reported costs for dam removal projects. Total cost information could include component costs related to project planning, dam deconstruction, monitoring, and several categories of mitigation activities. We compiled reported costs from 455 unique sources for 668 dams removed in the United States from 1965 to 2020. The dam removals occurred within 571 unique projects involving 1–18 dams. When adjusted for inflation into 2020 USD, cost of these projects totaled \$1.522 billion, with per-dam costs ranging from $1 thousand (k) to \$268.8 million (M). The median cost for dam removals was \$157k, \$823k, and \$6.2M for dams that were< 5 m, between 5–10 m, and > 10 m in height, respectively. Geographic differences in total costs showed that northern states in general, and the Pacific Northwest in particular, spent the most on dam removal. The Midwest and the Northeast spent proportionally more on removal of dams less than 5 m in height, whereas the Northwest and Southwest spent the most on larger dam removals > 10 m tall. We used stochastic gradient boosting with quantile regression to model dam removal cost against potential predictor variables including dam characteristics (dam height and material), hydrography (average annual discharge and drainage area), project complexity (inferred from construction and sediment management, mitigation, and post-removal cost drivers), and geographic region. Dam height, annual average discharge at the dam site, and project complexity were the predominant drivers of removal cost. The final model had an R 2 of 57% and when applied to a test dataset model predictions had a root mean squared error of $5.09M and a mean absolute error of \$1.45M, indicating its potential utility to predict estimated costs of dam removal. We developed a R shiny application for estimating dam removal costs using customized model inputs for exploratory analyses and potential dam removal planning.

Frontiers in Ecology and Evolution↗

USGS2023

Toward a national eDNA strategy for the United States

Environmental DNA (eDNA) data make it possible to measure and monitor biodiversity at unprecedented resolution and scale. As use-cases multiply and scientific consensus grows regarding the value of eDNA analysis, public agencies have an opportunity to decide how and where eDNA data fit into their mandates. Within the United States, many federal and state agencies are individually using eDNA data in various applications and developing relevant scientific expertise. A national strategy for eDNA implementation would capitalize on recent scientific developments, providing a common set of next-generation tools for natural resource management and public health protection. Such a strategy would avoid patchwork and possibly inconsistent guidelines in different agencies, smoothing the way for efficient uptake of eDNA data in management. Because eDNA analysis is already in widespread use in both ocean and freshwater settings, we focus here on applications in these environments. However, we foresee the broad adoption of eDNA analysis to meet many resource management issues across the nation because the same tools have immediate terrestrial and aerial applications.

Environmental DNA↗

USGS2023

A decision-support framework for dam removal planning and its application in northern California

Dam removals are occurring more frequently with the rising cost of maintaining aging infrastructure, public safety concerns, and growing interest in river restoration. So far, most dam-removals have been unsystematic in their approach. Given the several thousand dam removals expected over the coming decades, a systematic approach to plan future dam removals holds potential for aligning and delivering multiple benefits. Despite multi-sector factors driving decision-making, most existing prioritization frameworks tend to operate within single or related disciplines. Here we present a hierarchical, multi-disciplinary decision-support framework to prioritize dam removals based on opportunistic factors (Tier 1), hydro-ecological variables (Tier 2), and socio-cultural considerations (Tier 3). This framework integrates multiple decision criteria under data availability constraints, incorporates value-driven weights, and can be applied to a portfolio of dams at various spatial scales. The final output facilitates the identification of dam removal projects that align opportunistic, environmental, and social benefits. We recommend the application of this framework as a critical first step to identifying high-priority candidates for removal, recognizing that removal decisions will ultimately require detailed feasibility studies and stakeholder engagement. To illustrate its utility, we apply this framework to California's North Coast region and identify a small number of “good” candidates to be considered for removal. We conclude with recommendations for filling critical knowledge gaps and advancing systematic dam removal planning in the United States and beyond.

California↗

USGS2023

Using eDNA metabarcoding to establish targets for freshwater fish composition following river restoration

Establishing realistic targets for fish community composition is needed to assess the effectiveness of river restoration projects. We used environmental DNA (eDNA) metabarcoding with MiFish primers to obtain estimates of fish community composition across 17 sites upstream, downstream and within a restoration mitigation project area (Kaihotsu–Kasumi) located in the Shigenobu River system, Ehime Prefecture, Japan. We evaluate the benefits of using eDNA to quickly, sensitively, and extensively gather data to establish existing fish community composition in the restoration area, as well as potential future short-term, medium-term, and long-term targets of species assemblages that could realistically emerge following dispersal into the project area from upstream and downstream populations. We compare results from eDNA metabarcoding with species lists obtained from contemporaneous capture surveys and historical information. Nonmetric multidimensional scaling plots of community composition obtained from eDNA surveys showed that the Kaihotsu–Kasumi restoration area and surrounding river reaches were divided into three clusters: upper reaches, middle and lower reaches, and estuarine reaches. The Kaihotsu–Kasumi restoration area sites were included in the group containing the middle and lower reaches of the inflow and outflow rivers that were near the restoration area. We detected a total of twenty-six species in this group, twenty-one native species and five non-native species. Therefore, these native species were considered suitable as short-term target species with high potential for dispersal into Kaihotsu–Kasumi restoration area. By comparison, only 14 species would have been selected as target species based on capture surveys and historical literature. One factor increasing the resolution of our eDNA surveys was our ability to identify the presence of intraspecific lineages of Misgurnus anguillicaudatus (Clades A and B), which were missed by the capture surveys. These results indicate that the eDNA metabarcoding method can provide more comprehensive and realistic short-term target species estimates than capture surveys, as well as provide higher resolution monitoring through intraspecific lineage detection.

Global Ecology and Conservation↗

USGS2023

Community and citizen science on the Elwha River: Past, present, and future

This report reflects on the past, present, and potential future of community and citizen science (CCS) in the Elwha River watershed, with particular focus on the years before and after a major restoration event: the removal of two dams that had impacted the river system for a century. We ask: how does CCS feature in the Elwha story and how could it feature? We use the term CCS to reference the broad range of ways in which members of the public might participate in authentic science and monitoring processes, including students and both paid and unpaid interns: participants are individuals contributing to scientific projects without prior formal training in the topic. Removal of the Elwha dams was a large-scale, complex project, and communities had an important role to play: the Lower Elwha Klallam Tribe (LEKT) and other local groups were a large part of the original drive to remove the dams. Some funding and policy requirements for monitoring are ending, but there is still much to learn from the changes happening in the Elwha, requiring ongoing research and monitoring. In 2022, the Elwha scientific community came together in a multifaceted effort called the “Elwha ScienceScape” to mark the ten-year anniversary of dam removal and to plan for future monitoring. One of ScienceScape’s priorities is expanding CCS efforts, and because the Elwha dam removal is a powerful international symbol of large-scale watershed restoration, ScienceScape is well-positioned to inform and emphasize the potential role of CCS in dam removal worldwide. This report presents insights about Elwha CCS from an academic literature review and discussions with scientists and many others that have been working in the Elwha. We found that the history of CCS on the Elwha is important but understated, with few scientific papers acknowledging support by volunteers of various kinds. Recent and ongoing CCS projects on the Elwha tend to be focused on biological phenomena, and most are associated with educational opportunities (across many types of institutions) and paid internships. We also noted that most Elwha CCS projects required volunteers with particular pre-existing skill sets (e.g., botanical knowledge) or time to impart specialized training (e.g. boat use), leading many projects towards engagement with a smaller number of volunteers. Partners working in the Elwha are considering a wide range of potential new CCS projects, and these ideas are in varying stages of development. Many new projects would broaden public involvement in terms of the opportunities available and increase the variety of focal topics for research and monitoring. This increased breadth is promising: there are indications that the local community’s interests also range widely, from fish recovery after dam removal to dam removal impacts on humans. Elwha CCS projects have encountered some challenges and barriers, including the administrative burden of coordinating volunteers and managing liability concerns. But Elwha ScienceScape scientists are committed to the value that CCS brings both to the research itself as well as to those who participate in these projects. CCS can be a way to increase equity in science and engage people who would not otherwise participate in research, and in many cases the research simply wouldn’t be possible without their help. Support with project administration, volunteer management, and data management could help in expanding CCS efforts and broadening their inclusivity. More systematic tracking of CCS projects to assess how they contribute to research and to community and participant benefit could be helpful in establishing and maintaining a long-term CCS strategy in the Elwha.

Wshington↗

USGS2021

Reconnecting the Elwha River: Spatial patterns of fish response to dam removal

The removal of two large dams on the Elwha River was completed in 2014 with a goal of restoring anadromous salmonid populations. Using observations from ongoing field studies, we compiled a timeline of migratory fish passage upstream of each dam. We also used spatially continuous snorkeling surveys in consecutive years before (2007, 2008) and after (2018, 2019) dam removal during summer baseflow to assess changes in fish distribution and density over 65 km of the mainstem Elwha River. Before dam removal, anadromous fishes were limited to the 7.9 km section of river downstream of Elwha Dam, potamodromous species could not migrate throughout the river system, and resident trout were the most abundant species. After dam removal, there was rapid passage into areas upstream of Elwha Dam, with 8 anadromous species (Chinook, Coho, Sockeye, Pink, Chum, Winter Steelhead, Summer Steelhead, Pacific Lamprey, and Bull Trout) observed within 2.5 years. All of these runs except Chum Salmon were also observed in upper Elwha upstream of Glines Canyon Dam within 5 years. The spatial extent of fish passage by adult Chinook Salmon and Summer Steelhead increased by 50 km and 60 km, respectively, after dam removal. Adult Chinook Salmon densities in some previously inaccessible reaches in the middle section of the river exceeded the highest densities observed in the lower section of the river prior to dam removal. The large number (>100) of adult Summer Steelhead in the upper river after dam removal was notable because it was among the rarest anadromous species in the Elwha River prior to dam removal. The spatial extent of trout and Bull Trout remained unchanged after dam removal, but their total abundance increased and their highest densities shifted from the lower 25 km of the river to the upper 40 km. Our results show that reconnecting the Elwha River through dam removal provided fish access to portions of the watershed that had been blocked for nearly a century.

Washington↗

USGS2021

Riverscape approaches in practice: Perspectives and applications

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 guiding principles and approaches in inland fisheries and watershed management. During the last two decades, scientific literature on riverscapes has increased rapidly, indicating that the term and associated approaches are serving an important purpose in freshwater science and management. We trace the origins and theoretical foundations of riverscape perspectives and approaches and examine trends in the published literature to assess the state of the science and demonstrate how they are being applied to address recent challenges in the management of riverine ecosystems. We focus on approaches for studying and visualizing rivers and streams with remote sensing, modelling and sampling designs that enable pattern detection as seen from above (e.g. river channel, floodplain, and riparian areas) but also into the water itself (e.g. aquatic organisms and the aqueous environment). Key concepts from landscape ecology that are central to riverscape approaches are heterogeneity, scale (resolution, extent and scope) and connectivity (structural and functional), which underpin spatial and temporal aspects of study design, data collection and analysis. Mapping of physical and biological characteristics of rivers and floodplains with high-resolution, spatially intensive techniques improves understanding of the causes and ecological consequences of spatial patterns at multiple scales. This information is crucial for managing river ecosystems, especially for the successful implementation of conservation, restoration and monitoring programs. Recent advances in remote sensing, field-sampling approaches and geospatial technology are making it increasingly feasible to collect high-resolution data over larger scales in space and time. We highlight challenges and opportunities and discuss future avenues of research with emerging tools that can potentially help to overcome obstacles to collecting, analysing and displaying these data. This synthesis is intended to help researchers and resource managers understand and apply these concepts and approaches to address real-world problems in freshwater management.

Biological Reviews↗