Regions to streams : spatial and temporal variation in stream occupancy patterns of coho salmon (Oncorhynchus kisutch) on the Oregon coast

Aquatic ecological investigation is expanding to encompass considerations of multiple scales across large landscapes. Much of the analysis included in this work focuses specifically on coho salmon (Oncorhynchus kisutch) in multiple subbasins on the Oregon coast. Coho salmon were chosen for an investigation of spatial scales, network connections, and life history stages due to their broad distribution on the Oregon coast, and abundant data describing their distribution, habitat needs, behavior, and survival. Chapter 2 introduces dynamic network topology (DNT) as a framework for analysis and interpretation of aquatic obligate species. DNT is based on the premise that in-stream habitats change in form and organization over time, and native aquatic species are adapted to those changes through movement and life history diversity. Chapter 3 analyzes juvenile coho salmon density and stream network occupancy at three spatial scales (site, patch, and subbasin). The site scale analysis indicated that combining network and traditional in-stream habitat metrics (i.e., substrate and habitat juxtaposition variables) are most effective at describing juvenile coho salmon density. Patch sizes of juvenile coho salmon were defined using variograms. Variogram shape indicated that a nested spatial structure may be present in larger subbasins, indicating overlapping patterns of juvenile stream use. At the subbasin scale, stream network occupancy by juvenile coho salmon was shown to vary over time within subbasins, and appeared to increase or decrease similarly to the size of the adult spawning run. In chapter 3, two-tier Bayesian hierarchical models were applied to adult (subbasin and basin scales) and juvenile (site and subbasin scales) coho salmon in an attempt to combine spatial scales that might be influential at each life history stage. The best fitting adult model included the percent of large trees in the riparian zone at the subbasin scale with mean annual precipitation at the basin scale. The best fitting juvenile model included three variables, percent sand, stream order, and network distance to spawning habitat which mirrors the result of modeling efforts in Chapter 3. Multiple spatial scales and the framework of a stream network were informative at detecting patterns and interactions among scales and life history stages of coho salmon

The impact of land management decisions on dune processes on the Clatsop Plains: a case study of Camp Rilea, Oregon

This project explores the impact of land use decisions on dune processes at the Oregon National Guard's Camp Rilea. located on the north coast of Oregon. It used a combined analysis of historical and modern data sources to assess the impact of land use practices. Historical sources including the journals of Lewis and Clark and local newspaper articles were used to determine dune condition during the nineteenth century. Aerial photographs were used to track the changes in vegetation occurring during the twentieth century. This study indicates that the dune area was stabilized by native grass during the early 1800's and was disrupted during the latter half of the century by cattle grazing and construction of the Columbia River jetties. Activated dunes moved into developed areas burying homes, roads and buildings. In response to the moving sand, a massive biostabilization project was completed during the 1930's to halt dune movement. The resulting landscape is characterized by a new geomorphology and floristic distribution that reflect the impact of the introduction of high densities of plants for the biostabilization project. The final component of this project was the determination of alternate land management options for Camp Rilea that could enhance alternate land management goals including: minimization of exotic plant species, maximizing threatened and endangered species. maximum military training diversity and no action

Wildfire may increase habitat quality for spring Chinook salmon in the Wenatchee River subbasin, WA, USA

Pacific Northwest salmonids are adapted to natural disturbance regimes that create dynamic habitat patterns over space and through time. However, human land use, particularly long-term fire suppression, has altered the intensity and frequency of wildfire in forested upland and riparian areas. To examine the potential impacts of wildfire on aquatic systems, we developed stream-reach-scale models of freshwater habitat for three life stages (adult, egg/fry, and juvenile) of spring Chinook salmon (Oncorhynchus tshawytscha) in the Wenatchee River subbasin, Washington. We used variables representing pre- and post-fire habitat conditions and employed novel techniques to capture changes in in-stream fine sediment, wood, and water temperature. Watershed-scale comparisons of high-quality habitat for each life stage of spring Chinook salmon habitat suggested that there are smaller quantities of high-quality juvenile overwinter habitat as compared to habitat for other life stages. We found that wildfire has the potential to increase quality of adult and overwintering juvenile habitat through increased delivery of wood, while decreasing the quality of egg and fry habitat due to the introduction of fine sediments. Model results showed the largest effect of fire on habitat quality associated with the juvenile life stage, resulting in increases in high-quality habitat in all watersheds. Due to the limited availability of pre-fire high-quality juvenile habitat, and increased habitat quality for this life stage post-fire, occurrence of characteristic wildfires would likely create a positive effect on spring Chinook salmon habitat in the Wenatchee River subbasin. We also compared pre- and post-fire model results of freshwater habitat for each life stage, and for the geometric mean of habitat quality across all life stages, using current compared to the historic distribution of spring Chinook salmon. We found that spring Chinook salmon are currently distributed in stream channels in which in-stream habitat for most life stages has a consistently positive response to fire. This compares to the historic distribution of spring Chinook, in which in-stream habitat exhibited a variable response to fire, including decreases in habitat quality overall or for specific life stages. This suggests that as the distribution of spring Chinook has decreased, they now occupy those areas with the most positive potential response to fire. Our work shows the potentially positive link between wildfire and aquatic habitat that supports forest managers in setting broader goals for fire management, perhaps leading to less fire suppression in some situations

A Framework to Evaluate Vulnerability of Upriver Migrants to Existing Hydroelectric Infrastructure and Climate Change

River systems have been extensively modified by anthropogenic development of uplands and alterations in flow regimes. These changes reduce the capacity of river floodplains to absorb natural geophysical and environmental changes and directly affect life history adaptations that have developed over the millennia for native species. For example, in western North America changes in upslope processes (i.e. fire regimes, forest harvest and associated managements) work in concert with alterations in natural flow and thermal regimes through dams, levees, and floodplain development to change recovery trajectories of river systems. However, existing phenotypic adaptation by native fishes to environmental conditions may not be compatible with alterations to flow and thermal regimes. Climate change may compound this issue by further reducing variability in environmental conditions, both directly and indirectly, thereby inhibiting the full expression of life history diversity present in current populations. We explored expressed behavioral variability in upriver migration and passage for adult Coho Salmon (Oncorhynchus kisutch), an endangered salmon in Washington and Oregon, USA. We combined long-term records of river flow, water temperature, and upstream fish passage in a single visualization, providing strong empirical foundations for understanding upstream behavioral movement and tolerances of this native salmon. We compared current behavioral variability of Coho Salmon to scenarios representing possible future hydrologic conditions associated with a changing climate. We found that in some locations, the range of environmental conditions in the future is not outside the behavioral variability currently expressed by upstream migrating adult Coho Salmon. However, in some locations, predicted changes in streamflow and temperature occur during times of peak migration and may affect survival of upstream migrants. We discuss management implications and recommendations for action that may expand the capacity of riverscapes to absorb perturbations, thereby allowing for enhanced resilience of native fish populations

Status of the European Green Crab, Carcinus maenas, (aka 5-spine crab) in Oregon Estuaries. Report for 2022

The European green crab (Carcinus maenas) has persisted in Oregon and Washington coastal estuaries since the late 1990s. A strong year class arrived during the 1998 El Niño, but numbers decreased and remained below 1 per trap per day until the arrival of the 2015-2016 El Niño. Since then, numbers have increased to an average of around 4-6 crabs per trap per day for intertidal sites and ~ 9 per trap per day in the shallow subtidal. Measurable ecological impact is predicted to occur at around 10-20 per trap per day (Grosholz et al. 2011). Between the two major El Niños, recruitment of young green crabs has been sporadic, with many years of recruitment failures. But after the 2015-2016 El Niño recruitment has been good every year. The Davidson Current transporting larvae from California during the winter no longer appears to be the only source of larvae for our coastal estuaries (Behrens Yamada, Fisher and Kosro 2021). Now that the populations in Oregon, Washington and British Columbia have built up, we have evidence for local larval production and seeding from a genetically distinct population on Vancouver Island (Alan Shanks and Carolyn Tepolt, pers. com.). This report is a compilation of trapping data for Carcinus maenas from various sources and estuaries. These include the following: 1) Catches of adult crabs in Yaquina Bay using Fukui traps set in the intertidal and in the shallow subtidal. The latter were set at 22 sites along a salinity gradient from South Beach Marina to the Port of Toledo by Mitch Vance of Oregon Department of Fish and Wildlife. 2) Catches of adult crabs at 3 sites in the Salmon estuary using Fukui traps set in intertidal areas by volunteers and by Rebecca Flitcroft from the United Stated Department of Agriculture. 3) Summary of catches of crabs trapped in Coos Bay by Shon Schooler, interns and technicians of South Slough National Estuarine Research Reserve. For detailed data on various sites in Coos Bay see Schooler et al. (2022). 4) Catches of adult crabs in Siuslaw and Umpqua estuaries by Shon Schooler and interns. 5) Average catches of Young-Of-The-Year (YOTY, or Age-0) crabs at the end of their first growing season, from 4 Oregon estuaries and Willapa Bay, Washington. This 25-year data set allows us to compare catches of YOTY crabs between years and between estuaries (Figure 3)

Climate change and vulnerability of bull trout (Salvelinus confluentus) in a fire-prone landscape

Linked atmospheric and wildfire changes will complicate future management of native coldwater fishes in fire-prone landscapes, and new approaches to management that incorporate uncertainty are needed to address this challenge. We used a Bayesian network (BN) approach to evaluate population vulnerability of bull trout (Salvelinus confluentus) in the Wenatchee River basin, Washington, USA, under current and future climate and fire scenarios. The BN was based on modeled estimates of wildfire, water temperature, and physical habitat prior to, and following, simulated fires throughout the basin. We found that bull trout population vulnerability depended on the extent to which climate effects can be at least partially offset by managing factors such as habitat connectivity and fire size. Moreover, our analysis showed that local management can significantly reduce the vulnerability of bull trout to climate change given appropriate management actions. Tools such as our BN that explicitly integrate the linked nature of climate and wildfire, and incorporate uncertainty in both input data and vulnerability estimates, will be vital in effective future management to conserve native coldwater fishes

Sectoral Impacts of Invasive Species in the United States and Approaches to Management

Invasive species have a major effect on many sectors of the U.S. economy and on the well-being of its citizens. Their presence impacts animal and human health, military readiness, urban vegetation and infrastructure, water, energy and transportations systems, and indigenous peoples in the United States (Table 9.1). They alter bio-physical systems and cultural practices and require significant public and private expenditure for control. This chapter provides examples of the impacts to human systems and explains mechanisms of invasive species’ establishment and spread within sectors of the U.S. economy. The chapter is not intended to be comprehensive but rather to provide insight into the range and severity of impacts. Examples provide context for ongoing Federal programs and initiatives and support State and private efforts to prevent the introduction and spread of invasive species and eradicate and control established invasive species

A possible role for river restoration enhancing biodiversity through interaction with wildfire

BackgroundHistorically, wildfire regimes produced important landscape-scale disturbances in many regions globally. The “pyrodiversity begets biodiversity” hypothesis suggests that wildfires that generate temporally and spatially heterogeneous mosaics of wildfire severity and post-burn recovery enhance biodiversity at landscape scales. However, river management has often led to channel incision that disconnects rivers from their floodplains, desiccating floodplain habitats and depleting groundwater. In conjunction with predicted increases in frequency, intensity and extent of wildfires under climate change, this increases the likelihood of deep, uniform burns that reduce biodiversity.Predicted synergy of river restoration and biodiversity increaseRecent focus on floodplain re-wetting and restoration of successional floodplain habitat mosaics, developed for river management and flood prevention, could reduce wildfire intensity in restored floodplains and make the burns less uniform, increasing climate-change resilience; an important synergy. According to theory, this would also enhance biodiversity. However, this possibility is yet to be tested empirically. We suggest potential research avenues.Illustration and future directionsWe illustrate the interaction between wildfire and river restoration using a restoration project in Oregon, USA. A project to reconnect the South Fork McKenzie River and its floodplain suffered a major burn (“Holiday Farm” wildfire, 2020), offering a rare opportunity to study the interaction between this type of river restoration and wildfire; specifically, the predicted increases in pyrodiversity and biodiversity. Given the importance of river and wetland ecosystems for biodiversity globally, a research priority should be to increase our understanding of potential mechanisms for a “triple win” of flood reduction, wildfire alleviation and biodiversity promotion

Habitat overlap among native and introduced cold-water fishes in the Himalayas

Abstract Fish invasions threaten native freshwater ecosystems worldwide, yet methods to map biodiversity in data-deficient regions are scarce. Rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta fario) have been introduced to the Himalayan ecoregion where they are sympatric with vulnerable native snow trout Schizothorax plagiostomus and Schizothorax richardsonii. We aim to evaluate potential habitat overlap among snow trout and non-native trout in the Indus and Ganges River basins, Himalayan ecoregion. We transferred maximum entropy (MaxEnt) models developed with spatially continuous freshwater-specific environmental variables to map the distribution of potentially suitable habitats for rainbow and brown trout in the Himalayas. We adopted a similar procedure to map suitable habitats for snow trout species. There were substantial habitat overlaps (up to 96%) among snow trout and non-native trout. Yet, the physiography of receiving basins could play a role minimizing the impacts of each non-native trout on native snow trout. We generate high-resolution classified stream suitability maps as decision support tools to help managers in habitat allocation and policy formation to balance recreational fisheries with conservation of snow trout. Our workflow can be transferred to other basins and species for mapping freshwater biodiversity patterns in species-rich yet data-poor regions of the world

Patterns of riparian policy standards in riverscapes of the Oregon Coast Range

A riverscape perspective considers the ecological and social landscape of the river and its valley. In this context, we examined the spatial arrangement of protective policies for river networks. Riparian land-management standards are policy efforts that explicitly restrict certain management actions, e.g., timber harvest or land clearing, in stream-adjacent lands in order to protect water quality and aquatic habitat. In western Oregon, USA, management standards for riparian lands vary across federal, state, and private landownerships and land uses, projecting a patchwork of protective efforts across the landscape. The resulting variability in protection can complicate coordinated recovery efforts for threatened and endangered aquatic organisms, including migratory coho salmon (Oncorhynchus kisutch), that rely on stream habitats throughout the river network. Using a geographic information system, we quantified the spatial distribution of riparian management standards at multiple spatial extents: across the entire Oregon Coast Range, within the region's 84 HUC-10 watersheds, and in stream segments with high intrinsic potential to support coho salmon habitat. We found that the proportion of streams falling under protective efforts varied across watersheds in the region. In particular, watersheds containing streams of high intrinsic potential to support coho salmon habitat were associated with gaps in protective standards. By comparing the policy landscape to the biophysical landscape, our approach provides a novel framework for examining the spatial overlay of social and ecological concerns, and has direct relevance to assessments of population-scale restoration and recovery efforts