The Effects of Wetland Loss and Restoration on the Foraging Performance and Growth Potential of Juvenile Chinook Salmon in Pacific Northwest Estuaries PDF Download
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Author: Aaron David Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 105
Book Description
During the transition of juveniles from fresh water to estuarine and coastal environments, the survival of Pacific salmon (Oncorhynchus spp.) can be strongly size-selective and cohort abundance is partly determined. Because the quantity and quality of food consumed influence juvenile salmon growth, high rates of prey and energy acquisition during estuarine residence are important for survival. Human activities may have affected the foraging performance of juvenile salmon in estuaries by reducing the area of wetlands and by altering the abundance of conspecifics. To improve our understanding of the effects of wetland loss and conspecific density on juvenile salmon foraging performance and diet composition in estuaries, I assembled Chinook salmon (O. tshawytscha) diet and density data from nine U.S. Pacific Northwest estuaries across a gradient of wetland loss. We evaluated the influence of wetland loss and conspecific density on juvenile Chinook salmon instantaneous ration and energy ration, two measures of foraging performance, and whether the effect of density varied among estuaries with different levels of wetland loss. We also assessed the influence of wetland loss and three other covariates on salmon diet composition. There was no evidence of a direct effect of wetland loss on juvenile salmon foraging performance, but wetland loss mediated the effect of conspecific density on salmon foraging performance and altered salmon diet composition. These results suggest that habitat loss can interact with conspecific density to constrain the foraging performance of juvenile fishes, and ultimately their growth, during a life-history stage when survival is positively correlated with growth and size. I also evaluated whether restoring tidal flow to previously diked estuarine wetlands also restores foraging and growth opportunities for juvenile Chinook salmon. Several studies have assessed the value of restored tidal wetlands for juvenile salmon, but few have used integrative measures of salmon physiological performance, such as habitat-specific growth potential, to evaluate restoration. Our study took place in the Nisqually River delta, where recent dike removals restored tidal flow to 364 ha of marsh, the largest tidal marsh restoration in the Pacific Northwest. To compare Chinook salmon foraging performance and growth potential in two restored and two reference marshes over three years post-restoration, we sampled fish assemblages, water temperatures, and juvenile Chinook salmon diet composition and consumption rates, and used these data as inputs to a bioenergetics model. We found that juvenile Chinook salmon foraging performance and growth potential were similar between the restored and reference marshes. However, densities of Chinook salmon were significantly lower in the restored marshes and growth potential was more variable in the restored marshes due to their more variable and warmer (2?? C) water temperatures compared to the reference marshes. These results indicate that some but not all ecosystem attributes that are important to juvenile salmon rapidly recover following large-scale tidal marsh restoration.
Author: Aaron David Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 105
Book Description
During the transition of juveniles from fresh water to estuarine and coastal environments, the survival of Pacific salmon (Oncorhynchus spp.) can be strongly size-selective and cohort abundance is partly determined. Because the quantity and quality of food consumed influence juvenile salmon growth, high rates of prey and energy acquisition during estuarine residence are important for survival. Human activities may have affected the foraging performance of juvenile salmon in estuaries by reducing the area of wetlands and by altering the abundance of conspecifics. To improve our understanding of the effects of wetland loss and conspecific density on juvenile salmon foraging performance and diet composition in estuaries, I assembled Chinook salmon (O. tshawytscha) diet and density data from nine U.S. Pacific Northwest estuaries across a gradient of wetland loss. We evaluated the influence of wetland loss and conspecific density on juvenile Chinook salmon instantaneous ration and energy ration, two measures of foraging performance, and whether the effect of density varied among estuaries with different levels of wetland loss. We also assessed the influence of wetland loss and three other covariates on salmon diet composition. There was no evidence of a direct effect of wetland loss on juvenile salmon foraging performance, but wetland loss mediated the effect of conspecific density on salmon foraging performance and altered salmon diet composition. These results suggest that habitat loss can interact with conspecific density to constrain the foraging performance of juvenile fishes, and ultimately their growth, during a life-history stage when survival is positively correlated with growth and size. I also evaluated whether restoring tidal flow to previously diked estuarine wetlands also restores foraging and growth opportunities for juvenile Chinook salmon. Several studies have assessed the value of restored tidal wetlands for juvenile salmon, but few have used integrative measures of salmon physiological performance, such as habitat-specific growth potential, to evaluate restoration. Our study took place in the Nisqually River delta, where recent dike removals restored tidal flow to 364 ha of marsh, the largest tidal marsh restoration in the Pacific Northwest. To compare Chinook salmon foraging performance and growth potential in two restored and two reference marshes over three years post-restoration, we sampled fish assemblages, water temperatures, and juvenile Chinook salmon diet composition and consumption rates, and used these data as inputs to a bioenergetics model. We found that juvenile Chinook salmon foraging performance and growth potential were similar between the restored and reference marshes. However, densities of Chinook salmon were significantly lower in the restored marshes and growth potential was more variable in the restored marshes due to their more variable and warmer (2?? C) water temperatures compared to the reference marshes. These results indicate that some but not all ecosystem attributes that are important to juvenile salmon rapidly recover following large-scale tidal marsh restoration.
Author: Peter B. Moyle Publisher: Univ of California Press ISBN: 0520276086 Category : Nature Languages : en Pages : 252
Book Description
One of California's most remarkable wetlands, Suisun Marsh is the largest tidal marsh on the West Coast and a major feature of the San Francisco Estuary. This productive and unique habitat supports endemic species, is a nursery for native fishes, and is a vital link for migratory waterfowl. The 6,000-year-old marsh has been affected by human activity, and humans will continue to have significant impacts on the marsh as the sea level rises and cultural values shift in the century ahead. This study includes in-depth information about the ecological and human history of Suisun Marsh, its abiotic and biotic characteristics, agents of ecological change, and alternative futures facing this ecosystem.
Author: Melanie Jeanne Davis Publisher: ISBN: Category : Languages : en Pages : 228
Book Description
A complex mosaic of estuarine habitats is postulated to bolster the growth and survival of juvenile Chinook salmon by diversifying the availability and configuration of prey and refugia. Consequently, efforts are underway along the North American Pacific Coast to return modified coastal ecosystems to historical or near-historical conditions, but restoring habitats are often more sensitive to anthropogenic or climate-mediated disturbance than relict (unaltered) habitats. Estuaries are expected to experience longer inundation durations as sea-levels rise, leading to reductions in intertidal emergent marshes, mudflats, and eelgrass beds. Furthermore, rising ocean temperatures may have metabolic consequences for fall-run populations of Chinook salmon, which tend to out-migrate during the spring and summer. Extensive monitoring programs have allowed managers to assess the initial benefits of management efforts (including restoration) for juvenile salmon at local and regional scales, but at present they have limited options for predicting and responding to the concurrent effects of climate change in restoring and relict coastal ecosystems. For my dissertation I addressed this gap in knowledge using a comprehensive monitoring dataset from the restoring Nisqually River Delta in southern Puget Sound, Washington. I focused on the following questions: 1) How do juvenile Chinook salmon prey consumption and dietary energy density vary throughout a mosaic of estuarine habitats, and is this variation related to differences in physiological condition? 2) How do among-habitat differences in thermal regime and prey consumption affect the bioenergetic growth potential of juvenile Chinook salmon? 3) How will shifts in the estuarine habitat mosaic vary under different sea-level rise and management scenarios? and 4) How will these climate- and management-mediated shifts in the estuarine habitat mosaic impact habitat quality for juvenile Chinook salmon? To address the first question, I used stomach content and stable isotope analyses to analyze the diets of wild and hatchery Chinook salmon captured in different estuarine habitats during the out-migration season (March-July of 2014 and 2015). I also linked measures of stomach fullness and dietary energy density to body condition. To address the second question, I used a bioenergetics model to determine how among-habitat differences in water temperature and diet might affect juvenile Chinook salmon growth. To address the third question, I designed and calibrated a marsh accretion model and decision support tool using post-restoration monitoring data sets and spatial coverages. Finally, to address the fourth question, I combined output from the marsh accretion model, a hydrological model, and measurements of prey availability into a spatially explicit version of the bioenergetics model to assess the habitat quality and growth rate potential of the entire estuarine habitat mosaic under different sea-level rise and management scenarios. When considered in tandem, these chapters represent a novel approach to habitat management. Assessments of juvenile salmon diet and physiology, marsh accretion models, and bioenergetics models have been independently implemented along the Pacific Coast, but the amalgamation of all three approaches into a single, spatially explicit analysis represents a novel and significant contribution to the scientific literature. In conducting these analyses for the Nisqually River Delta, some major themes emerged regarding the importance and vulnerability of specific habitats. An integrative diet analysis using stomach contents and stable isotopes found distinct dietary niches between wild and hatchery Chinook salmon. Wild fish were more likely to utilize the freshwater tidal forested and transitional brackish marsh habitats along the main stem river, where energy-rich insect drift made up most of their dietary biomass. The availability and consumption of insect prey resulted in distinct benefits to body condition and growth, as determined by direct physiological measurements and output from the habitat-specific bioenergetics model. These findings highlight the importance of freshwater and brackish emergent marsh habitats with overhanging vegetation, which can regulate water temperatures and supply insect drift. Unfortunately, freshwater tidal forests, brackish marshes, and low and high elevation emergent salt marshes are highly vulnerable to sea-level rise, especially when geological and anthropogenic features limit sediment accretion or lateral expansion. When spatial layers from the marsh accretion model were incorporated into the spatially explicit version of the bioenergetics model, output indicated that loss of low and high salt marsh reduced the amount of prey available for juvenile salmon, thus decreasing modeled growth rate potential. In all, these findings highlight the importance of preserving the estuarine habitat mosaic for out-migrating juvenile salmon, especially as tidal regimes and ocean temperatures continue to shift through time.
Author: J. Alan Yeakley Publisher: Springer Science & Business Media ISBN: 1461488184 Category : Science Languages : en Pages : 270
Book Description
Wild salmon, trout, char, grayling, and whitefish (collectively salmonids) have been a significant local food and cultural resource for Pacific Northwest peoples for millennia. The location, size, and distribution of urban areas along streams, rivers, estuaries, and coasts directly and indirectly alter and degrade wild salmonid populations and their habitats. Although urban and exurban areas typically cover a smaller fraction of the landscape than other land uses combined, they have profound consequences for local ecosystems, aquatic and terrestrial populations, and water quality and quantity.
Author: Rachael Klopfenstein Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 126
Book Description
As highlighted in this study, shallow-water habitats and the prey they provide are important for juvenile salmon in the Columbia River estuary, but the spread of invasive species and large-scale changes to the estuary influence how these habitats are utilized. Reed canarygrass (Phalaris arundinacea) (“PHAR” hereafter) is a highly invasive aquatic plant species that affects a number of emergent wetland habitats in the upper Columbia River estuary, and is of concern to those trying to restore important shallow-water habitats for juvenile salmon. The presence of PHAR undoubtedly reduces plant diversity, but this study seeked to elucidate how PHAR affects juvenile Chinook Salmon rearing success relative to natural emergent vegetation. The study further evaluated the importance of wetland-deriver prey to juveniles found in shallow-water habitats along a habitat gradient (i.e., back-water channel, confluence, and main stem). We conducted research at a floodplain wetland restoration site in the tidal-fluvial portion of the estuary, where a water control structure is used to manage water levels and the spread of PHAR. The goal of the research was to compare two microhabitats within the floodplain: areas dominated by PHAR and areas dominated by natural emergent vegetation. Using hatchery-raised juvenile Chinook salmon, we designed a series of feeding experiments in artificial enclosures to determine whether invasive PHAR and natural emergent vegetation provide similar foraging and growth opportunities for juvenile salmon. We further identified differences in physical and biological parameters of each habitat (e.g., temperature, dissolved oxygen, and invertebrate community) and examined feeding characteristics (e.g., diet composition and modeled growth rates) for juveniles through a stomach content analysis. Additionally, we conducted beach seining and diet analysis for fish collected along a habitat gradient and compared the diet composition and modeled growth rates between the sample areas. In the floodplain wetland, invertebrate prey compositions from the 2015-2016 (March- June) fallout and emergence traps were similar, but prey abundances and diversity varied seasonally. Across both years, for emergence traps, the average total density (per m2) of invertebrates in the natural vegetation and in PHAR was 154±18 m2 and 225±34 m2, respectively, and for the fallout traps was 664±95 m2 and 662±64 m2, respectively. Salmon diets were mostly similar, and a large proportion of diets in both habitats were made up of Copepoda/Cladocera (60-98% composition by biomass). Growth during the net pen experiment differed significantly between the two vegetation types (Kruskal-Wallis: p
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The listing of 13 salmon and steelhead stocks in the Columbia River basin (hereafter collectively referred to as?salmon?) under the Endangered Species Act of 1973, as amended, has stimulated tidal wetland restoration in the lower 235 kilometers of the Columbia River and estuary for juvenile salmon habitat functions. The purpose of the research reported herein was to evaluate the effect on listed salmon of the restoration effort currently being conducted under the auspices of the federal Columbia Estuary Ecosystem Restoration Program (CEERP). Linking changes in the quality and landscape pattern of tidal wetlands in the lower Columbia River and estuary (LCRE) to salmon recovery is a complex problem because of the characteristics of the ecosystem, the salmon, the restoration actions, and available sampling technologies. Therefore, we designed an evidence-based approach to develop, synthesize, and evaluate information to determine early-stage (1̃0 years) outcomes of the CEERP. We developed an ecosystem conceptual model and from that, a primary hypothesis that habitat restoration activities in the LCRE have a cumulative beneficial effect on juvenile salmon. There are two necessary conditions of the hypothesis: - habitat-based indicators of ecosystem controlling factors, processes, and structures show positive effects from restoration actions, and - fish-based indicators of ecosystem processes and functions show positive effects from restoration actions and habitats undergoing restoration. Our evidence-based approach to evaluate the primary hypothesis incorporated seven lines of evidence, most of which are drawn from the LCRE. The lines of evidence are spatial and temporal synergies, cumulative net ecosystem improvement, estuary-wide meta-analysis, offsite benefits to juvenile salmon, landscape condition evaluation, and evidence-based scoring of global literature. The general methods we used to develop information for the lines of evidence included field measurements, data analyses, modeling, meta-analysis, and reanalysis of previously collected data sets. We identified a set of 12 ancillary hypotheses regarding habitat and salmon response. Each ancillary hypothesis states that the response metric will trend toward conditions at relatively undisturbed reference sites. We synthesized the evidence for and against the two necessary conditions by using eleven causal criteria: strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment, analogy, complete exposure pathway, and predictive performance. Our final evaluation included cumulative effects assessment because restoration is occurring at multiple sites and the collective effect is important to salmon recovery. We concluded that all five lines of evidence from the LCRE indicated positive habitat-based and fish-based responses to the restoration performed under the CEERP, although tide gate replacements on small sloughs were an exception. Our analyses suggested that hydrologic reconnections restore access for fish to move into a site to find prey produced there. Reconnections also restore the potential for the flux of prey from the site to the main stem river, where our data show that they are consumed by salmon. We infer that LCRE ecosystem restoration supports increased juvenile salmon growth and enhanced fitness (condition), thereby potentially improving survival rates during the early ocean stage.
Author: Ken W. Krauss Publisher: John Wiley & Sons ISBN: 111963928X Category : Science Languages : en Pages : 484
Book Description
Explores how the management of wetlands can influence carbon storage and fluxes. Wetlands are vital natural assets, including their ability to take-up atmospheric carbon and restrict subsequent carbon loss to facilitate long-term storage. They can be deliberately managed to provide a natural solution to mitigate climate change, as well as to help offset direct losses of wetlands from various land-use changes and natural drivers. Wetland Carbon and Environmental Management presents a collection of wetland research studies from around the world to demonstrate how environmental management can improve carbon sequestration while enhancing wetland health and function. Volume highlights include: Overview of carbon storage in the landscape Introduction to wetland management practices Comparisons of natural, managed, and converted wetlands Impact of wetland management on carbon storage or loss Techniques for scientific assessment of wetland carbon processes Case studies covering tropical, coastal, inland, and northern wetlands Primer for carbon offset trading programs and how wetlands might contribute The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity.Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Author: Peter A. Bisson Publisher: ISBN: Category : Atlantic salmon Languages : en Pages : 36
Book Description
This report describes the evidence for invasion of Pacific Northwest streams by Atlantic salmon (Salmo salar) that have escaped from marine salmon farms, and assesses the potential impact of farmed salmon invasion on native fishes inhabiting streams on National Forest System lands. The current risk to streams on National Forest lands in the Pacific Northwest from Atlantic salmon invasions appears to be low and is limited to a few areas in northwest Washington and southeast Alaska. However, long-term risks may be substantial if fish continue to escape from marine rearing pens or freshwater hatcheries. The two greatest threats appear to be that (1) Atlantic salmon could transmit a serious disease or parasite to native fishes, and (2) escaped salmon could eventually adapt to local conditions, leading to self-sustaining populations. If Atlantic salmon populations are eventually established, this species preference for swiftly flowing stream habitats could facilitate competition with currently at-risk species such as steelhead (Oncorhynchus mykiss). This could result in a pattern of expansion similar to that observed in other nonnative aquatic plants and animals, in which a prolonged early colonization period is followed by a rapid phase of exponential growth as breeding populations adapt to local conditions.
Author: Aaron David
Author: Aaron David
Author: Alisa J. Bieber
Author: Peter B. Moyle
Author: Melanie Jeanne Davis
Author: J. Alan Yeakley
Author: Rachael Klopfenstein
Author: 
Author: 
Author: Ken W. Krauss
Author: Peter A. Bisson