Long-lived trees and excellent preservation of remnant wood allow examination of late-Holocene climate variability and its relation to woodland tree demography and populations of prehistoric agriculturalists in northeastern Utah using dendrochronological methods. Tree-ring chronologies are developed from Douglas-fir (Psuedotsuga menziesii) and Colorado pinyon (Pinus edulis) on the Tavaputs Plateau covering the last 2,300 years. The climate reconstructions fill an important temporal and spatial gap in our understanding of moisture related climate variability in the region. We investigate the relationships between climate and woodland demography by constructing a 1,500-year record of pinyon establishment and death. Twentieth-century expansion and infill of pinyon/juniper woodlands and more recent widespread die-offs in the early 21st century heighten the importance of understanding these relationships. The climate reconstruction is analyzed in light of the archaeological record of Fremont agriculturalists between approximately AD 550 and 1300, and provides the first glimpse of climate variability throughout the Fremont era in this region.Results of the hydroclimate reconstructions show that multidecadal droughts unlike any observed in the instrumental record occur regularly over the last 2,000 years. Droughts in the mid 12th century and late 13th century are synchronous those found in numerous other records across the southwestern United States. A drought in the early 6th century is especially severe. Analysis of pinyon demography indicates rates of tree establishment, release, and death are highly variable over the last 1,500 years. Broad peaks in tree establishment occur in the 7th and 8th centuries, the 12th and 13th centuries, and again in the 18th, 19th and 20th centuries. Higher tree death rates are related to dry periods, but tree establishment is only weakly associated with wetter periods. Instead, cohorts of suppressed young trees established over decades tend to synchronously experience rapid growth rate increases during wet periods following droughts. Stands appear more susceptible to population turnover as semi-dominant cohorts of trees age and decline. Two critical periods in Fremont archaeology in the region, coincide with significant changes in moisture conditions. These changes follow longer periods of stability suggesting that changes in the predictability of climate conditions may have impacted Fremont agriculturalists in the region.

Shellfish aquaculture is growing rapidly with the expanding human population, offering high-quality animal protein as well as economic benefits to producing areas. Cultivation relies on coastal and estuarine habitats, dynamic ecosystems where marine organisms including mussels are exposed to natural environmental variability, and which will be affected by climate change (e.g. ocean warming, acidification, desalination etc.). This thesis investigated the variability in blue mussel, Mytilus edulis, performances under suspended rope-culture in a stratified Scottish sea loch, Loch Leven. Environmental conditions were monitored over one year and at different culture depths and related to the mussel's product quality (meat yield, condition index), genetic composition (genotype, extent of hybridisation) and shell phenotype (shell strength and shape). Environmental conditions varied over time (seasonal cycles and short-term fluctuations) but also across depth, generating different microhabitats for mussels depending on their position on the rope. Conditions varied most at shallow culture depths, for salinity in particular, but presented warmer temperature and higher food availability compared to greater depths and promoted mussel growth and abundance. Meat yield and condition index followed a seasonal cycle, with maximum values in early summer and minimum values in winter, associated with environmental (nutritional) and reproductive cycles. The genetic composition and shell morphology of cultured mussels differed across depth. On average, every sixth mussel carried alleles of Mytilus trossulus, but the level of introgression was overall low. However, highly introgressed mussels (≥ 75 %) presented distinct shell morphology (significantly lower shell strength, elongated shell shape) and originated mainly from shallow culture depths. This phenotype distinguished them from their congeners and allowed for their identification based on shell characters. This thesis presents the variability in suspended mussel culture in a heterogeneous environment, highlighting the complex relationships between habitat conditions and the genetic and phenotypic make-up in naturally occurring mixed-species stocks. The knowledge gained offers guidance for the farm operators to optimise production (site selection, spat collection etc.) and provides better predictions for the industry on the possible effects associated with climate change on future mussel production.

No description available.

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on Dec. 20, 2007). Includes bibliographical references.

No description available.

Mussel colonization is assumed to result from factors affecting recruitment and post-recruitment survival. Despite evidence of passive migration and habitat engineering by adult mussels, the contribution to population dynamics of these processes remains unknown. This research attempts to elucidate the relative importance and scale of (1) adult movement vs. recruitment and (2) of local habitat engineering vs. habitat heterogeneity, for colonization by the blue mussel, Mytilus spp., in the St. Lawrence Estuary, Quebec. Transplants of marked mussels were used to test these ideas. Our results support the hypothesis that colonization mostly occurs through disturbance-mediated adult movement. The scale of this displacement was quantified. Colonization was accelerated by topographic heterogeneity and engineered habitat propagation. These results counter the notion that mussel population dynamics are solely regulated by recruitment and growth, and suggest that distribution patterns are also upheld by adult aggregation and movement from the local scale to landscape level.

Recently, the assumption that marine populations are demographically open due to long-distance larval dispersal has increasingly been challenged. Here we present a large-scale, multi-year survey of blue mussel ( Mytilus spp.) abundance and recruitment along the Southern shore of the St. Lawrence Estuary, Quebec. Using spatial statistical tools we detected significant positive cross-covariance between upstream adults and downstream recruitment at a 14-35 km scale. Adult abundances in subsequent surveys proved to be best explained by past patterns of recruitment, rather than growth indices, or the local supply of recruits. Fucus spp., large macroalgae with much shorter planktonic periods, displayed no evidence of dynamic coupling. Recruitment was instead correlated with growth rate, indicating that local conditions may drive rates of reproduction by Fucus spp. plants. These results provide the first direct quantification of spatio-temporal demographic coupling between adult production and recruitment using survey data, with consequences for metapopulation and marine reserve design.

Thesis (Ph.D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.

Zugl.: Göttingen, University, Diss., 2001.

Thesis (M. Sc.), Memorial University of Newfoundland, 1998. / Restricted until June 1999. Bibliography: leaves 84-95.