Browsing by Subject "Ecosystems"

Now showing 1 - 7 of 7
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    Eel River Steelhead Study [2007]
    (2024-06-13) Power, Mary; mepower@berkeley.edu; Power, Mary; National Center for Earth-Surface Dynamics (NCED)
    Throughout the world, historically large populations of native anadromous salmonids are in severe decline or extinct. In the United States alone, twenty-six Evolutionarily Significant Units of Pacific salmonid are currently threatened or endangered. These declines are most commonly attributed to degradation of spawning and rearing habitat resulting from increased loading of fine sediments. Although excessive loading of fine sediments into rivers is well known to degrade salmonid spawning habitat, its effects on the demographically critical rearing juveniles have been unclear. We experimentally manipulated fine bed sediment in a northern California river and examined responses of a juvenile salmonid. Increasing concentrations of deposited fine sediment decreased growth and survival of juvenile steelhead trout. These declines resulted from a shift in invertebrates toward burrowing taxa unavailable as prey and from increased steelhead activity and injury at higher levels of fine sediment. The relationship between deposited fine sediment and juvenile steelhead growth is linear. This suggests that there is no threshold below which exacerbation of fine sediment delivery and storage in gravel bedded rivers will be harmless, but also that any reduction will produce immediate benefits for salmonid restoration.
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    Effects of external and internal nutrient supplies on decomposition of wild rice, Zizania palustris.
    (2011-02) Hildebrandt, Lauren R.
    How external and internal nutrient supplies affects wild rice shoot and root litter decomposition and the nitrogen (N) and phosphorus (P) dynamics in decaying litter were examined in two experiments. In a site quality experiment, wild rice shoot and root litterbags were decayed in mesocosms in the field with added N or P or a control as ambient conditions, over 115 days. In the second litter quality experiment, wild rice plants were grown with N, P, both, or none, to produce litter of different qualities and then decayed for 168 days under controlled temperature in the laboratory. The impacts of both site and litter quality was greater on shoot litter than root litter. In the site quality experiment, P addition significantly increased wild rice shoot decay more than N addition and reduced P mineralization over time compared to the control. Neither adding N nor P influenced root decay, but adding P increased root P immobilization compared to the control, and the effect was much greater in root litter compared to shoot litter. In the litter quality experiment, P enrichment increased litter quality by increasing P concentrations and water-soluble compound concentrations in shoot litter and decreasing lignin concentrations in root litter, thereby increasing decay rates of both shoot and roots, although, the impact was much greater on shoot decay. N enrichment increased plant growth but reduced shoot litter quality and decay likely because these larger plants had greater lignin concentrations for structural support and lower phosphorus concentrations and lower N:P ratios. Increased lignin likely overrides a concomitant increase in nitrogen concentration in shoot litter and appears to control wild rice decomposition. Initial lignin:P,C:P, lignin+asid-solubles:P and the N:P ratios of shoot litter were correlated to the final mass remaining. Lignin and phosphorus appear to play a key role in driving wild rice decay through the opposite effects that each have on litter quality.
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    Effects of Water Level Fluctuations and Regulation on Upper Great Lakes Nearshore Ecosystems: An Annotated Bibliography
    (University of Minnesota Duluth, 2009-07) Brady, Valerie; Ruzycki, Elaine
    This is an annotated bibliography of literature relating to the effects of water level fluctuations on ecosystems and biota of the Laurentian Great Lakes. This report was created in support of investigations into the potential ecosystem effects of altering the water level regulation of Lake Superior at the St. Marys River lock and dam system. Because such a change would most affect lakes Superior, Michigan, and Huron, we tried to concentrate on these lakes. However, we have included quite a bit of literature from lakes Erie and Ontario, where there has been more investigation of water level fluctuations (or lack thereof) and water level regulation. We have also included pertinent literature from around the world on effects of water level fluctuations in large lake and reservoir systems, primarily because of the paucity of pertinent literature for the upper Great Lakes.
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    How law matters to ecosystem restoration.
    (2012-02) Enzler, Sherry Anne
    The 2005 Millennium Ecosystem Assessment reported unprecedented degradation of ecosystems and the services they provide to human well being which, if allowed to continue, could adversely affect human health, security and welfare. Our environmental legal authorities and policies, however, are not well designed to protect the health of our nation's ecosystems focusing instead on clean air, clean land and clean water as single medium, often referred to as the silo approach to environmental protection. Protecting ecosystems requires that we move away from this silo approach to a multi systems approach to environment and ecosystem management in both policy and law. How can we motivate the necessary changes in our legal constructs and political systems? This is a question posed by a number of communities and states struggling with the concept of ecosystem protection. Applying a Modified Destabilization theory this research explores whether and under what conditions the strategic use of litigation by environmental social movements can destabilize established legal constructs to protect ecosystems. Using the Mono Lake and Everglades' restoration event histories the Modified Destabilization Model is used to examine the role law played in struggles to change the political and social systems necessary to protect, restore and rehabilitate ecosystems. This analysis increases our understanding of the elements necessary to move to change the political and social structures to achieve systems approach to ecosystem management and the ability of social movements to mobilize law and litigation to accomplish the political and social change necessary to protect ecosystem.
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    Microbiological and chemical aspects of corrosion of sheet steel in the Duluth-Superior Harbor
    (2010-12) Bostrom, Jonathan Robert
    Steel structures in the Duluth-Superior harbor show unusual patterns of corrosion characterized by raised blister-like nodules called tubercles and pitted steel. This corrosion phenomenon could possibly decrease the integrity and the lifespan of the structures. Microbiological and chemical factors that may be influencing corrosion processes were examined in this study from 2007-2009. A laboratory microcosm experiment was designed to examine several microbiology and water quality parameters. Terminal-restriction fragment length polymorphism (T-RFLP) analyses showed that bacterial communities on steel were different from one another in microcosm treatments with different types of water (e.g. autoclaved Duluth-Superior harbor water vs. unaltered Duluth-Superior harbor water and Lake Superior water vs. Duluth-Superior harbor water). Coupons with different bacterial communities also showed differences in sulfate-reducing bacterial abundance and iron-oxidizing bacterial abundance. Further, coupons with higher abundances of sulfate-reducing bacteria and iron-oxidizing bacteria had higher inverse polarization resistance values. Inverse polarization resistance is frequently used to approximate the instantaneous rate of corrosion. Mass lost and pit depth were measured on steel in the microcosm, and these two measurements showed a positive correlation. Microbiological and corrosion measurements were also performed on steel in the Duluth-Superior harbor, and these measurements were compared to steel in the microcosm experiment. These experiments showed correlations among water chemistry, bacterial community, and populations of specific bacteria that are associated with corrosion in other ecosystems.
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    Tracing the flow of carbon through ecosystems using stable isotope techniques
    (2010-03) Fassbinder, Joel J.
    The stable isotope 13C has become a popular tool for tracing carbon exchange between atmospheric and terrestrial reservoirs. Stable isotope techniques have been applied in a variety of ecosystems to partition the component fluxes of net CO2 exchange (FN) and have been incorporated into several atmospheric inversion models that estimate the ter- restrial carbon sink on the regional and global scales. While the use of stable isotope theory has helped provide valuable insight into the temporal and spatial variability of car- bon exchange, there has been some concern about the theory’s dependence on several key assumptions that have gone unverified due to limiting sampling techniques. Specific concerns regard the temporal variability of the isotopic composition of ecosystem respi- ration (δR) and its potential influence on ecosystem flux partitioning. In this thesis, an automated chamber system was combined with stable isotope techniques to evaluate and apply isotopic partitioning theory both in an agricultural ecosystem and in a climate con- trolled experiment using corn and soybean plants. Further, this new automated sampling technique was combined with isotopic flux-gradient measurements to examine the main factors controlling variability in ecosystem respiration and its isotopic composition. The findings from this thesis research may benefit land surface schemes that simulate isotopic fluxes for input to atmospheric inversion models.