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Notes on the comparative ecology of Cottus bairdi and Cottus girardi in Naked Creek, VirginiaMatheson, Richard Edmond 01 January 1979 (has links)
No description available.
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Seasonal changes in the growth and structure of the diatom Asterionella formosa Hassall in Lake Matoaka, VirginiaLundgren, Kathy Joyce 01 January 1980 (has links)
No description available.
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Palatability of Freshwater Surface Hemiptera to Potential Fish Predators (Lepomis macrochirus and Gambusia affinis)Mounts, Julie Heyward 01 January 1989 (has links)
No description available.
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Distribution of Freshwater Amphipoda in the Lake Matoaka/College Woods Area, Williamsburg, VirginiaMahon, Susan Alexandra 01 January 1997 (has links)
No description available.
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Calcium as a Limiting Factor in the Distribution of the Amphipod Gammarus pseudolimnaeusZehmer, John Kinsley 01 January 1998 (has links)
No description available.
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Basins at risk : conflict and cooperation over international freshwater resources /Yoffe, Shira. January 2001 (has links)
Thesis (Ph. D.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 126-133). Also available via the World Wide Web.
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The marketing and distribution system for fresh fish in South West England : modelling the effects of supply variationSlaymaker, John Edward January 1988 (has links)
The distribution system in the fishing industry has attracted little attention from academics in comparison to the catching sector. This realisation came in the early 1980's with questions being raised about system efficiency and the identification of problems. A lack of understanding of the distribution system led to various calls for an investigation. This research builds on existing understanding by identifying the distribution system in Devon and Cornwall and develops a modelling framework with forecasting properties within which distribution system problems can be analysed. A review of the marketing and distribution literature reveals that system efficiency and the impacts of changes in external conditions are important areas for study. The literature also reveals that few attempts have been made to develop analytical and conceptual modelling frameworks that enable the study of these phenomena in existing distribution systems. Attempts that have been made suffer from conceptual and data problems. The research identities the major features of the fresh fish distribution system, especially the structural determinants including lack of standardisation and variability of supply. Studies of the system in the United Kingdom and overseas are found to be descriptive, concentrating upon trends and past problems. Few modelling approaches have been used or developed. The system in Devon and Cornwall is identified through interview techniques and presented in quantitative terms. From an identification of the system, it is determined that a model should focus on the port merchant sector and have the ability to explain and forecast the effects of supply variation. Econometric methods are used to develop a model with exogenous supply and seasonality characteristics which when combined with sample data on costs and pricing provides a method of analysis and forecasting. The research discusses the wide range of applications possible with the model developed.
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Differentiating freshwater contributions and their variability to the surface and halocline layers of the Arctic and subarctic seas /Alkire, Matthew Buckley. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 141-151). Also available on the World Wide Web.
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Influences of Habitat Conditions on Submerged Aquatic Vegetation Development in the Chickahominy River and Other Virginia Tributaries of the Chesapeake BayShields, Erin C. 01 January 2008 (has links)
Recently, there has been an expansion of submerged aquatic vegetation (SAV) in the tidal fresh and oligohaline portions of lower Chesapeake Bay tributaries. Much like the resurgence seen in the Potomac in the 1980’s, this spread of SAV in Virginia systems such as the Mattaponi, Pamunkey and Chickahominy seems to have been initiated by the introduction and spread of the invasive species Hydrilla verticillata, and appears to have been rapid. However the resurgence in the Piankatank has occurred in the absence of the introduction of this species. The factors that are influencing the growth of SAV in these tributary environments, including water quality and habitat conditions as well as the potential for interspecific competition between H. verticillata and the other SAV species in these regions are not well known. Annual aerial mapping surveys of the Chickahominy River were used alongside historical water quality data to investigate the patterns and rates of SAV bed development, and the relationships between this development and water quality conditions. Field investigations were performed in order to better understand the seasonal community dynamics relative to water quality conditions and interspecific competition. Historical analysis, field monitoring and field experimentation all showed salinity and turbidity to be the main factors controlling SAV abundance and species distribution along the Chickahominy River. Historical analysis of the Chickahominy River revealed a decline in SAV abundance in 2002, which corresponded with seasonal mean salinities of 4.1 psu. SAV abundance from 1998-2007 showed a significant correlation with vegetation emergence period secchi depth, in which secchi depths of 0.3 meters, the lowest of the time period, occurred during the 2002 SAV decline. Field data showed species zonation, in which H. verticillata was the overall dominant species, but was limited to the upper portion of the river where salinity intrusion remained below 2 psu throughout the growing season. Najas minor was dominant in the lower portion of the river where salinities reached over 4 psu in October. Salinity was the best predictor for H. verticillata’s biomass difference between the upper and lower river. SAV in the Chickahominy was able to grow in a wide range of conditions, with total suspended solids and chlorophyll a concentrations at times greater than 20 mg l-1 and 40 μg l-1, respectively, and sediment organic content ranging from less than 1% to greater than 25%. Comparisons with the Mattaponi and Piankatank rivers revealed ideal habitat for H. verticillata growth in the Mattaponi, where salinities along the vegetated reach of the upper river did not extend above 1 psu. On the other hand, this species was not found growing in the Piankatank, where salinities in the very upper portion of the river reached 3.5 psu. Finally, a field species removal experiment demonstrated that environmental conditions rather than interspecific competition were most important in determining plant performance, as both H. verticillata and N. minor exhibited poor growth in the lower river site, which had higher salinity and turbidity levels than the upper river site.
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Distribution of Chrysaora quinquecirrha in the York RiverCones, Harold Nelson 01 January 1968 (has links)
No description available.
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