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1
Mikša, Ovidijus. "Epigėjinių vabalų (Insecta: Coleoptera) bendrijos skirtingo reljefo sklypo vietose." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130621_144225-67217.
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Tyrimo objektas. Epigėjinių vabalų bendrijos Kamšos botaniniame-zoologiniame draustinyje, 458 kvartale, 5 sklype. Norėdami nustatyti ekspozicijos vietų reljefo įtaką epigėjinių vabalų individų ir rūšių gausai, pasirinkome 5 tyrimų barelius, esančius lygioje miško vietoje ir šiauriniame, pietiniame, rytiniame bei vakariniame šlaituose.
Tikslas - nustatyti epigėjinių vabalų bendrijų struktūrą ir jos pokyčius vegetacijos eigoje bei priklausomai nuo ekspozicijos vietų reljefo.
Darbo metodai. Tyrimui buvo naudojama Barberio žemės gaudyklės. Gaudyklę sudaro plastikiniai 0,5 l talpos ir 6,5 cm skersmens indeliai, įkasti į žemę sulig paklotės paviršiumi. 1/3 gaudyklės buvo pripilama 10% formalino tirpalo. Tai apsaugojo epigėjinius vabalus nuo puvimo ir vabzdžialesių paukščių. Kiekviename barelyje buvo įrengta po 5 gaudykles, iš viso 25 gaudyklės. Atstumas tarp gaudyklių buvo 5 metrai. Surinkti epigėjiniai vabalai buvo džiovinami ir identifikuojami ASU laboratorijose.
Darbo rezultatai. 2012 m. gegužės – rugpjūčio mėnesiais buvo atlikta 10 apskaitų, iš viso surinkta 1627 vnt. epigėjinių vabalų. Indenfikuotos 4 rūšys: Carabidae, Silphidae, Curculionidae, Staphylinidae ir 15 rūšių. Gausiausia iš sugautų rūšių buvo Phosphuga atrata – 312 vabalų. Lyginant sugautų vabalų skaičių skirtingo reljefo sklypo vietose, nustatyta, kad daugiausia epigėjinių vabalų sugauta lygioje miško vietoje įrengtomis gaudyklėmis. Antroje vietoje - vakariniam šlaite... [toliau žr. visą tekstą]Study object. The research of ground beetles Insecta: Coleoptera was made in Kamša botanical-zoological reserve, 458-th section, 5-th plot. We have chosen 5 parts of the plot for investigation: in a plane surface of the forest, on the North, the South the East and the West slopes in order to detect influence of the exposition place relief to abundance of caught ground beetles individuals and species. The aim of investigation was to determine structure of ground beetle communities, its temporal changes and dependence on the relief of exposition place. Methods of investigation. The Barberis ground traps were used in the research, 5 units in the each chosen part, 25 in total. The distances between the ground traps were 5 m. The trap is made from a 0,5 l volume and 6,5 cm diameter plastic cruet. The traps were digged in to ground to the top of the trap. 1/3 of the trap was filled with a 10% formalin soak. In that case the insects were saved from decomposing and birds. The collected beetles were dried and identified in the labs of Aleksandras Stulginskis University. Results. The total amount of collected ground beetles in 10 records, made since May to August 2012, was 1627. A variety of 15 species in 4 families Carabidae, Silphidae, Curculionidae, Staphylinidae were identified. The most abundant species collected was Phosphuga atrata – 312 ground beetles. The maximum quantity of ground beetles were caught in the plane surface of the forest, the... [to full text]
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Peterson, Cassidy. "Patterns of Abundance and Community Dynamics in Atlantic Coastal Sharks." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1539617961.
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Koba, Keisuke. "Nitrogen dynamics in forested ecosystems elucidated by 15N natural abundance method." Kyoto University, 2000. http://hdl.handle.net/2433/157140.
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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・論文博士
博士(農学)
乙第10321号
論農博第2281号
新制||農||796(附属図書館)
学位論文||H12||N3356(農学部図書室)
UT51-2000-C88
(主査)教授 武田 博清, 教授 谷 誠, 教授 小﨑 隆
学位規則第4条第2項該当
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Whu, Alyssa. "Boundary Dynamics Across Habitat Edges: Effects on Beneficial Insect Species Abundance and Richness." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1346122386.
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Cárdenas-Alayza, Susana. "Prey abundance and population dynamics of South American fur seals (Arctocephalus australis) in Peru." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42356.
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South American fur seals (Arctocephalus australis) continue to survive in Peru in spite of commercial harvesting, periodic disappearance of prey (i.e., El Niño), and competition with the Peruvian anchoveta fishery. I investigated the ability of the Peruvian population of fur seals to recover from catastrophic declines at two temporal and spatial scales. The first analysis determined intrinsic rate of growth (r) and the potential carrying capacity (K*—the number of fur seals that could be supported in Peru in the absence of sealing and El Niño) from 1880–2010, and the second used pup counts from 1984–2010 to determine the relationship between prey abundance and the timing of pupping at an important fur seal breeding site in southern Peru. Model results indicated that South American fur seals in Peru have an intrinsic growth rate r of 0.20 and a potential carrying capacity K* of 115,000 seals. Recent counts (2007) show that current population is at 33% of the estimated mean numbers of fur seals alive from 1880-1925. Analysis of 25 years of counts of pups and adult females at the breeding site showed a correlation between anchoveta biomass and mean birth dates (r² = 0.59, P<0.01) and with the ratio of pups to females (r² = 0.66, P<0.01) in the upcoming breeding seasons. It also revealed a 2-week shift in the mean birth date that may reflect a change in the age structure of the population. Numbers of pups born tended to be lower in years with low anchoveta biomass, as did recruitment of young females. Monitoring daily numbers of pups born and adult females appears to be a useful means to assess the feeding conditions encountered by South American fur seals in Peru. My study also suggests that South American fur seals are adapted to survive in extremely disturbed environments and have the potential to rapidly recover following population declines. Whether or not they ever again achieve their potential carrying capacity will depend upon protection of breeding rookeries, a continued harvest ban, reduced bycatch, incidental captures and illegal poaching, regulation of anchoveta fishing quotas and good environmental conditions.
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Dique, David S. "The distribution, abundance and dynamics of a regional koala population in south-east Queensland /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17880.pdf.
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Klenner, Walt. "The effect of food abundance and territorial behaviour on population dynamics of the red squirrel." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30698.
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The effects of food abundance on the population dynamics and territorial behaviour of red squirrels were examined during a four year study in south-central British Columbia, Canada. I used a short-term, ad libitum addition of supplemental food in Douglas fir (low squirrel population density) and white spruce (high squirrel population density) forest habitats to examine changes in demography and spacing behaviour. Removal experiments in spring and autumn assessed the effect of residents on breeding density and juvenile recruitment and the influence of settlement patterns on recolonization density.
If food is a limiting resource, I expected population density, recruitment, body weight, growth rates and reproduction to increase on the food supplemented areas. Population density in spruce control habitat was consistently twice as high as in Douglas fir control habitat (26 vs. 15) from 1985 to 1988. The addition of supplemental food resulted in a four-fold increase in population density in Douglas fir habitat and a two-fold increase in spruce habitat, indicating that populations in both habitats were food limited, but more strongly in Douglas fir habitat. The increase in density was the result of a strong increase in the recruitment of immigrants, primarily juveniles of unknown origin. Both recruitment to the food-supplemented grids and the decline in density following the removal of food were density-dependent.
Stable population density may be the result of an inflexible territory size despite large changes in food abundance. To test this hypothesis, I monitored changes in territory size, home range size, the number of territories, intruder pressure, movement patterns and activity budgets in response to supplemental food. Supplemental food significantly decreased territory size and resulted in a five-fold increase in the number of territories in Douglas fir habitat. Territory size did not decrease in white spruce habitat, but there was a two-fold increase in the number of territories. In both habitats, immigrants established territories in previously unoccupied areas and in Douglas fir
habitat, some immigrants established small territories on areas formerly used by residents who had defended large territories. There was an increase in the intensity that red squirrels travelled over their territories, a decrease in the proportion of time spent away from their territories and an increase in the proportion of time spent defending their territories. These behavioural changes appeared to offset the increased competitor density on the enriched territories, enabling red squirrels to defend territories larger than necessary for their current food requirements. This limited flexibility in territory size may reduce the amplitude of fluctuations in population density despite large changes in food abundance.
Territorial behaviour can limit breeding density and juvenile recruitment. When territorial residents were removed from Douglas fir habitat in spring, red squirrel populations returned to a density similar to the control or pre-removal density in five of six removal trials. In autumn, population density returned to control or pre-removal densities in four of six trials. In white spruce habitat, population density returned to control or pre-removal levels in three of four trials in both spring and autumn. In both Douglas fir and spruce habitat, immigrants of unknown origin repopulated the removal areas. After removals in spring, females in breeding condition immigrated to the removal areas in five of six trials in Douglas fir habitat and in all four trials in spruce habitat. Settlement patterns did not appear to influence either territory size or recolonization density.Science, Faculty of
Zoology, Department of
Graduate
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Okay, Atiye Zeynep. "Spatial pattern and temporal dynamics of northern bobwhite abundance and agricultural landuse, and potential casual factors." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3355.
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There was a long-term decline in northern bobwhite (Colinus virginianus, NBW)
abundance since the 1920s, based on the Christmas Bird Count (CBC) data, but with
substantial spatial and temporal variations across its range. There were four
recognizable periods in the spatial and temporal dynamics of NBW abundance between
1920 and 1990. Severe weather conditions and habitat loss due to land use change
appeared to be the most important factors influencing the long-term trends and spatial
patterns in NBW abundance.
A spatial database of agricultural land use was developed based on the Census of
Agriculture to evaluate the spatial patterns of land use variables over NBW range from
1920 to 1997. The results showed dramatic changes in land use over the period and the
influence of socio-economic events, natural disasters and federal agricultural policies on
the dynamics of land use pattern, and potential implications to NBW abundance were
identified. Replacement of less intensive agriculture with intensive monoculture
production and mechanization coincided with World War I, and the post-war collapse in
agriculture and the economy, partly associated with the Dust Bowl, enhanced this trend.
Monoculture production and clean farming practices were further intensified during
World War II and the years following the war. These land use changes had overall
negative effects on NBW habitat.
Analysis of the changes in spatial pattern of NBW abundance in the Great Plains
region during the severe drought of the 1950s showed a significant decline in NBW
abundance during the drought and a contraction of the NBW range at its western edge.
The post-drought recovery exhibited spatial patterns significantly different from the predrought
ones. These findings suggested that severe drought caused short-term changes
in regional distribution of NBW and range contraction, as well as long-lasting, largescale
changes in spatial distribution of NBW abundance.
This study provides scientific basis for landscape planning and management.
Evaluating the spatial pattern and temporal dynamics of certain wildlife species at large
scales over long-term periods, and identifying potential causal factors are key strategies
for implementing innovative and sustainable approaches to planning and policy. Such
strategies will have a significant impact on future landscape and wildlife species.
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Regelin, Beke. "Purple sandpipers (Calidris maritima) feeding in an Arctic estuary: tidal cycle and seasonal dynamics in abundance." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-168047.
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The purple sandpipers (Calidris maritima) are the most common waders in the high arctic archipelago of Svalbard, Norway. There they have to cope with a very short summer season and high metabolic costs of migrating far north and breeding in an arctic environment. The food on land is usually scarce, whereas there are rich feeding grounds in the littoral zone, such as in the intertidal zone of river flats. These feeding grounds are though only available to the purple sandpipers during low tide and as long as the estuary is not covered by sea ice. One of these intertidal flats was used as the fieldwork area in this study. To study when the birds are coming to this intertidal flat for feeding, a count study was performed during the entire stay of the purple sandpipers in Svalbard in summer 2010. Point counts were performed at low tide during 118 different days. Additionally, point counts were performed at twenty days during the six hours of the entire low tide period, to study when during the tidal cycle most sandpipers were feeding at the estuary. Most sandpipers were counted at the intertidal flat at the beginning of June with the highest number, 921 individuals, on 8th June. When the tundra was free of snow and the birds could start breeding, numbers where rapidly declining with very few sandpipers left in the estuary in July and the first part of August. From the end of August numbers were increasing again with a second but lower peak in the end of September and beginning of October. By the end of October all sandpipers had left the estuary. The study on the appearance of purple sandpipers at the estuary at the different periods of low tide showed that there were significantly more sandpipers between low tide and half an hour later than at the rest of the low tide period. This might be due to better access to their prey at that time. This knowledge could be used in future studies aiming at recording the maximum numbers. The result of the phenologic study could be included in a long term monitoring to see if the numbers and the timing of purple sandpipers are stable in this area or not: Are the peak numbers differing significantly? Is the timing of the arrival, the stay on the tundra and the timing of leaving the archipelago in the fall changing? Long-term monitoring would be especially interesting in the view of possible influences of the climate change on the purple sandpipers. Rising sea level as a result of the climate change would change the morphology of the estuaries and thereby influence the food resources available for sandpipers.
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Mashiri, Fadzayi Elizabeth. "Long-Term Dynamics in Plant Abundance and Spatial Variation in Response to Grazing Systems, Precipitation and Mesquite Cover." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/193979.
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Higher stocking density under seasonal-rotation grazing is expected to increase plant abundance because expanded animal distribution and reduced selective grazing on forage species will reduce the spatial variation and competitive advantage of non-forage species compared to yearlong grazing. Rangeland scientists struggle with how long rangeland experiments must continue in order to detect grazing treatment effects, particularly in semi-arid ecosystems with slow responses and high spatio-temporal variability. My first study investigated grazing system effects on plant abundance (cover and density) over the short-term (12yrs) or long-term (22 or 34yrs) after accounting for covariates (mesquite and precipitation gradients). My second study assessed how grazing systems affected spatial variation in grass abundance over 22 or 34 years after accounting for precipitation gradient. The first study was a course resolution approach, looking at grazing impacts on plant abundance. The second study was a finer resolution assessment of the underlying assumption that rotational grazing systems reduce selective grazing. Using split-plot analysis of variance, with year as the split, changes in mean plant abundance and variance in grass abundance were compared between two grazing systems (yearlong vs. seasonal rotation), after accounting for covariate(s). Variance of grass abundance among sample locations within an experimental pasture was the measure of spatial variability and was expected to increase with selective grazing. Grazing systems did not influence plant abundance or spatial variation of grasses. The absence of grazing effect may be due to overriding influences of grazing intensity, large pasture sizes, temporal variation in precipitation, and few replicates. Specific to spatial variation, the absence of grazing system effect may be due to discrepancies in transect representation across ecological sites and spatial variation of grasses occurring at scales different than the 30-m transect size. Like earlier research, my studies failed to substantiate the fundamental premise for implementing rotational grazing systems. This exposes challenges that confront rangeland scientists when implementing grazing studies in spatio-temporally heterogeneous ecosystems. I recommend that research shift from comparing rigid schedule-driven grazing systems to more adaptive management approach where there are comparisons between different levels or different designs of flexible systems.
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Kruger, Marlene. "Seasonal abundance and diversity of sorghum panicle-feeding Hemiptera in South Africa / M. Kruger." Thesis, North-West University, 2006. http://hdl.handle.net/10394/3687.
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During the past two decades, panicle-feeding Hemiptera have become pests of sorghum in West and Central Africa, and particularly in Mali, where this is a staple food crop. Of the more than 100 sorghum insect pests reported in Africa, 42 species were found to be panicle-feeding pests. Prior to this study, no research had been done on the paniclefeeding Hemiptera in South Africa. The objectives of the study were to determine the abundance and diversity of panicle-feeding Hemiptera on sorghum. A check list was compiled and the temporal distribution of different Hemiptera species determined during the different panicle stages of development. In addition, the effect of insecticide
application on Hemiptera numbers was evaluated and the correlation between grain
mould severity and Hemiptera feeding damage was investigated. To determine the abundance and diversity of Hemiptera on sorghum panicles, surveys were conducted
between November 2004 and June 2006 at 26 sites in four provinces of South Africa.
Two methods of collection were used viz. the plastic bag and D-Vac methods. The total
number of the adults and nymphs collected during this study was 23 798. Forty-three
different herbivorous Hemiptera species were collected. The most abundant family was
the Miridae (41 %), followed by the Lygaeidae (17 %). Eurystylus spp., Calidea dregii, Campylomma sp., Creontiades pallidus, Nysius natalensis and Nezara viridula were the most abundant species and also occurred widely in the sorghum production area. Infestation levels of these species were low compared to that in other parts of Africa and it cannot be concluded that they have pest status in South Africa. There was no clear distinction between the stages during which panicles were infested by different species.
The general tendency was that nearly all species were present from the flowering stage onwards and that numbers declined when grain hardened. In general, Campylomma sp. and C. pallidus numbers peaked during the flowering stage and Eurystylus spp. and N. natalensis during the milk stage. Hemiptera feeding damage resulted in an increase in incidence of seeds with discoloured germ, therefore contributing significantly to reduction in grain quality.Thesis (M. Environmental Science (Plant Protection))--North-West University, Potchefstroom Campus, 2007.
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Uzhegov, Sergey. "Capital concentration and petroleum abundance in economies of Eurasia - Russia, Kazakhstan, and Azerbaijan : microeconomic performance and macroeconomic dynamics." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC182/document.
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Cette recherche explore l’impact de l’apparition des milliardaires et de l’abondance pétrolière sur la trajectoire du développement de la Russie, du Kazakhstan, et de l’Azerbaïdjan. L’accumulation très contentieuse de patrimoines extraordinaires se déroule en parallèle avec la récession économique et la transformation des anciens propriétaires des biens d’état en main-d’œuvre mal payée, avec des milliers de manifestants dans les rues de la Russie en 2017, qui 100 ans après la Révolution de 1917, posent les mêmes questions : ‘qui est propriétaire de quoi ?’ et ‘quel est le niveau d’efficacité ?’. Afin d’apporter des ‘données concrètes’ au débat, l’étude : premièrement, analyse le processus de l’émergence des milliardaires, avec concentration sur la légitimité et l’équité sociale ; et deuxièmement, évalue leur performance comparative. En analysant la période de 9 ans de 2007 à 2015, il considère 300 entités juridiques, composées de 3 groupes d’entreprises : 100 de milliardaires, 100 du gouvernement, et 100 d’entrepreneurs. Afin de recueillir les différences de performance, l’étude utilise 25 mesures financières, dans 2 catégories - 5 paramètres de comptabilité et 20 ratios financiers. Simultanément, le paradoxe de sous-performance économique de ces 3 pays pétroliers du Continent Eurasiatique est examiné. Dans le but de surmonter les difficultés de la route axée sur les ressources naturelles, l’étude suggère : 1. un nouveau cadre analytique : un algorithme diagnostic et un modèle de processus ; 2. le modèle de croissance, incluant le pétrole et les institutions ; 3. le modèle empirique, exposant les liens des éléments d’analyse avec la dynamique macroéconomiquePresent research is an inquiry into implications of emergence of billionaires and petroleum-abundance on development trajectory of Russia, Kazakhstan, and Azerbaijan. Highly-controversial accumulation of massive fortunes is going in parallel with economic downturn and transformation of collective owners of state assets into low-paid labor-force, with thousands of street-protesters in Russia in 2017, who 100 years after 1917 Revolution raise the same questions: ‘who owns what?’ and ‘how efficiently?’ In order to contribute ‘hard data’ to debate, current investigation: first, explores a process of formation of billionaires, focusing on legitimacy and social fairness; and second, evaluates their comparative performance. Analyzing 9-year 2007-15 timespan, it considers 300 legal entities, comprised by 3 groups of companies: 100 of billionaires, 100 of government, and 100 of entrepreneurs. To elicit performance differences this study refers to 25 financial metrics, composed by 2 categories – 5 core accounting parameters and 20 financial ratios. Alongside, a paradox of economic underperformance of these 3 petronations of Eurasian Continent is explored. To overcome adversities of resource-based path, the study suggests: 1. novel analytical framework: diagnosis algorithm and process model; 2. growth model’s setup, embracing petronational and institutional dimensions; and 3. empirical model, exposing links of analysis’ elements with macroeconomic dynamics
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Fink, Dennis [Verfasser], Nicole [Akademischer Betreuer] Dubilier, and Ulrich [Akademischer Betreuer] Fischer. "Dynamics of Symbiont Abundance in Bathymodiolin Deep-sea Symbioses / Dennis Fink. Gutachter: Nicole Dubilier ; Ulrich Fischer. Betreuer: Nicole Dubilier." Bremen : Staats- und Universitätsbibliothek Bremen, 2011. http://d-nb.info/1071898256/34.
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Wanniarachchi, Sudas Dayamurthi. "The effects of tillage and cropping on the dynamics of soil organic matter as determined by ¹³C natural abundance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0029/NQ27471.pdf.
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Wilson, Michael Turner. "The seasonal movements and abundance dynamics of the Pacific harbor seal (Phoca vitulina richardsi) along the southern Oregon coast." Thesis, Thesis (M.S.)--University of Oregon, 1993, 1993. http://hdl.handle.net/1794/9999.
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Wang, Yujia. "Assessing Bald Cypress (Taxodium distichum) Tree Dynamic Change in USF Forest Preserve Area Using Mixture-Tuned Matched Filtering and Multitemporal Satellite Imagery." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7375.
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Wetlands are the most important and valuable ecosystems on Earth. They are called “kidneys of the Earth”. Vegetation change detection is necessary to understand the condition of a wetland and to support ecosystem sustainable management and utilization. It has been a great challenge to estimate vegetation (including bald cypress trees) coverage of the wetland because it is difficult to access directly. Satellite remote sensing technology can be one important feasible method to map and monitor changes of wetland forest vegetation and land cover over large areas. Remote sensing mapping techniques have been applied to detect and map vegetation changes in wetlands. To address spectral mixture issues associated with moderate resolution remote sensing images, many spectral mixture methods have been developed and applied to unmix the mixed pixels in order to accurately map endmembers (e.g., different land cover types and different materials within pixels) fractions or abundance. Of them, Mixture Tuned Matched Filtering (MTMF) is an advanced spectral unmixing method that has attracted many researchers to test it for mapping land cover types including mapping tree species with medium or coarse remote sensing image data. MTMF is a partial unmixing method that suppresses background noise and estimates the subpixel abundance of a single target material. In this study, to understand impacts of anthropogenic (e.g., urbanization) and natural forces/climate change on the bald cypress tree dynamic change, the bald cypress trees cover change in University of South Florida Forest Preserve Area was mapped and analysed by using MTMF tool and multitemporal Landsat imagery over 30 years from 1984 to 2015. To evaluate the MTMF’s performance, a tradition spectral unmixing method, Linear Spectral Unmixing (LSU), was also tested. The experimental results indicate that (1) the bald cypress tree cover percentage in the study area has generally increased during the 30 years from 1984 to 2015, but over the time period from 1994 to 2005, the bald cypress tree cover percentage reduced; (2) MTMF tool outperformed the LSU method in mapping the change of the bald cypress trees over the 30 years to demonstrate its powerful capability; and (3) there potentially exists an impact of human activities on the change of the bald cypress trees although a further quantitative analysis is needed in the future research.
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Spencer, Meghin E., Mario Mateo, Matthew G. Walker, and Edward W. Olszewski. "A Multi-epoch Kinematic Study of the Remote Dwarf Spheroidal Galaxy Leo II." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623237.
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We conducted a large spectroscopic survey of 336 red giants in the direction of the Leo II dwarf galaxy using Hectochelle on the Multiple Mirror Telescope, and we conclude that 175 of them are members based on their radial velocities and surface gravities. Of this set, 40 stars have never before been observed spectroscopically. The systemic velocity of the dwarf is 78.3 +/- 0.6 km s(-1) with a velocity dispersion of 7.4 +/- 0.4 km s(-1). We identify one star beyond the tidal radius of Leo II but find no signatures of uniform rotation, kinematic asymmetries, or streams. The stars show a strong metallicity gradient of -1.53 +/- 0.10 dex kpc(-1) and have a mean metallicity of -1.70 +/- 0.02 dex. There is also evidence of two different chemodynamic populations, but the signal is weak. A larger sample of stars would be necessary to verify this feature.
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Sucre, Eric Brandon. "Soil resource heterogeneity and site quality in Southern Appalachian hardwood forests: Impact of decomposing stumps, geology and salamander abundance." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29470.
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The Southern Appalachian hardwood forests contain a wide diversity of flora and fauna. Understanding processes that affect nutrient availability in these forests is essential for sound forest management. Three interconnected research projects regarding soil resource heterogeneity were designed to increase our understanding of this ecosystem. The objective of these projects were as follows: 1) to examine and quantify the role of decaying stumps in regards to total carbon (C) and nitrogen (N) pools and fine-root dynamics, 2) compare and contrast the use of ground-penetrating radar (GPR) vs. a soil auger for estimating soil depth and site quality and 3) to evaluate how eastern red-backed salamanders (Plethodon cinereus) affect N-availability.
For the stump study, results show that decomposing stumps occupy approximately 1.2% of the total soil volume and constitute 4% and 10% of total soil N and C pools. Significant differences in N (p = 0.0114), C (p = 0.0172), microbial biomass C (p = 0.0004), potentially mineralizable N (p = 0.0042), and extractable NH4+ (p = 0.0312) concentrations were observed when compared to mineral soil horizons. In particular, potentially mineralizable N was 2.5 times greater in stump soil than the A-horizon (103 vs. 39 mg kg-1), 2.7 times greater for extractable NH4+ (16 vs. 6 mg kg-1) and almost 4 times greater for MBC (1528 vs. 397 mg kg-1). These measured properties suggest higher N-availability, organic matter turnover and N uptake in stump soil versus the bulk soil. 19% of the total fine root length and 14% of fine root surface area also occurred in the stump soil. The increased fine root length suggests higher concentrations of labile nutrient in the stumps since roots often proliferate in areas with higher nutrient availability. Significant differences occurred in N and C concentrations between all four decay classes and the A-horizon, which validated the use of this system and the need to calculate weighted averages based on the frequency and soil volume influenced by each decay class.
In the GPR Study, depth estimations were shallower using a soil auger compared to estimates obtained using GPR across all plots (p = 0.0002; Figure 3.4). On a soil volume basis, this was equivalent to about 3500 m3 of soil per hectare unaccounted for using traditional methods. In regards to using soil depth as a predictor for site quality, no significant relationships were observed with soil depth estimations obtained from the auger (Table 3.3). On the other hand, depth measurements from GPR explained significant amounts of variation across all sites and by physiographic region. Across all sites, soil depth estimates from GPR explained 45.5% of the residual variation (p = 0.001; Table 3.3). When the data were stratified by physiographic region, a higher amount of variation was explained by the regression equations; 85% for the Cumberland Plateau (p = 0.009), 86.7% for the Allegheny Plateau (0.007) and 66.7% for the Ridge and Valley (p = 0.013), respectively (Table 4.2). Results from this study demonstrate how inaccurate current methods can be for estimating soil depth rocky forests soils. Furthermore, depth estimations from GPR can be used to increase the accuracy of site quality in the southern Appalachians.
In the salamander study, no significant salamander density treatment or treatment by time effects were observed over the entire study period (p < 0.05). However, when the data were separated by individual sampling periods a few significant treatment by time interactions occurred: 1) during August 2006 for available NH4+ under the forest floor (i.e. horizontal cation membranes; p = 0.001), 2) August and 3) September 2006 for available NH4+ in the A-horizon (p = 0.026), and 4) May 2007 for available NO3- under the forest floor (p = 0.011). As a result of these trends, an index of cumulative N-availability (i.e. NH4+ and NO3-) under the forest floor and in the A-horizon was examined through the entire study period. Cumulative N-availability under the forest floor was consistently higher in the low- and medium-density salamander treatments compared to the high-density treatment. For cumulative N-availability in the A-horizon, a gradient of high to low N-availability existed as salamander density increased. Factors such as a prolonged drought in 2007 may have affected our ability to accurately assess the effects of salamanders on N-availability. We concluded that higher salamander densities do not increase N-availability.
Implementing methodologies that accurately account for soil nutrient pools such as stump soil, physical properties such as depth and fauna such as salamanders, increase our understanding of factors that regulate site productivity in these ecosystems. As a result, landscape-level and stand-level management decisions can be conducted more effectively.Ph. D.
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Pope, Shealagh E. Carleton University Dissertation Biology. "The relative roles of landscape complementation and metapopulation dynamics in the distribution and abundance of leopard frogs (Rana pipiens) in Ottawa-Carleton." Ottawa, 1996.
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de, la Hoz Franco Ernesto A. "Assessing the Effects of Myxobolus cerebralis and Other Environmental Factors on the Dynamics, Abundance, and Distribution of Trout Populations in the Logan River, Utah." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/4433.
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The presence of nonnative trout and the recent introduction of Myxobolus cerebralis in the Logan River drainage pose a threat to the native Bonneville cutthroat trout population (Oncorhynchus clarki Utah). The variability in the response of susceptible trout populations to M. cerebralis, causing agent of whirling disease, suggests that environmental factors may influence the effects of the parasite in infected environments. I investigated the relationship between temperature, discharge, substrate size, nutrient concentration (nitrogen and phosphorus), periphyton (chlorophyll a), and the relative abundance of Tubifex tubifex to the distribution, and prevalence of M. cerebralis in wild salmonid populations and sentinel fish in the mainstem of the Logan River and two of its tributaries. In addition, I investigated the potential influence of biotic (e.g., food availability, M. cerebralis prevalence) and abiotic factors (e.g., temperature) on the distribution abundance, and condition of salmonid fishes.
Differences in mean temperature and discharge across sites explained most (>70%) of the variability in prevalence of M. cerebralis observed along the Logan River. However, the prevalence of the parasite was not related to other factors that can influence its life cycle, such as productivity and substrate composition. The results also indicate that the fish fauna presents a longitudinal change reflected in a zonation pattern. Cutthroat trout dominates the headwaters and high-elevation reaches, while reaches at lower elevations of the mainstem and tributaries were dominated by brown trout. The transition between these species was consistent with changes in environmental characteristics. Cutthroat trout dominates the fish community in mainstream reaches with the lowest average minimum temperature and highest diel temperatures, and where small boulders and small cobbles are the predominant substrate.
This study provides insights of the abiotic and biotic factors that affect the distribution, abundance, and condition of salmonid populations along the Logan River. Identifying these factors is crucial to effectively manage this and other trout streams, where ensuring the conservation of native cutthroat trout populations is a priority. Further, I present baseline information of the potential linkages between environmental factors and M. cerebralis distribution and prevelance, which could be used to develop plans to minimize the potential negative effects of this parasite on wild salmonid populations.
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Young, Alexander L., and Alexander L. Young. "Three Essays on Complex Systems: Self-Sorting in a One-Dimensional Gas, Collective Motion in a Two-Dimensional Ensemble of Disks, and Environment-Driven Seasonality of Mosquito Abundance." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624567.
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Complex systems offer broad, unique research challenges due to their inability to be understood through a classic reductionist perspective, as they exhibit emergent phenomena that arise through the interactions of their components. In this thesis, we briefly review some characteristics of complex systems and the interplay of mathematical and computational methods to study them. We then discuss these approaches, how they are implemented, and how they support one another in three settings. First, we present a study that connects weather data to seasonal population-abundance of mosquitoes, using a microscopic model. Secondly, we consider the collective motions that arise in ensembles of disks interacting through non-elastic collisions and investigate how such behaviors affect macroscopic transport properties. Finally, we consider a 'self-sorting' one-dimensional collection of point-particles. In all of these cases, agent-based models and simulations are used to guide analysis, and in the final example, we explain how the simulations led to new theorems. Articles and molecular dynamics computer codes are provided as appendices.
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Simard, Peter. "Dolphin Sound Production and Distribution on the West Florida Shelf." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4402.
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This dissertation is an investigation of dolphin sound production and distribution off west central Florida. Although a wealth of information exists on the production of common sounds (whistles, echolocation) made by captive, trained dolphins, far less is known about free-ranging dolphin sound production and of unusual sounds. In addition, while inshore dolphin populations or communities are the subjects of research projects in many locations, dolphins in offshore waters are less commonly studied. The objectives of this dissertation were to contribute information on free-ranging dolphin sounds and continental shelf dolphin distribution.
While echolocation has been rigorously studied in captive, trained dolphins, there is far less known about how free-ranging dolphins use their echolocation. In order to investigate the use of echolocation by free-ranging dolphins, echolocation recordings from 14 groups of common bottlenose dolphins (Tursiops truncatus) were obtained during towed hydrophone cruises on the West Florida Shelf (WFS) and in Tampa Bay. The mean echolocation pulse rate was inversely related to water depth, suggesting echolocation pulse rate was a function of the two-way travel time of echolocation pulses, which was related to depth. Pulse rate modes were related to potential target distances, and indicated dolphins were commonly echolocating on targets up to at least 91.8 m away. The results of this study indicate that free-ranging bottlenose dolphins are using their echolocation in a manner similar to that found in studies with captive, trained dolphins.
Unusual low frequency sounds from bottlenose dolphins were found in the towed hydrophone recordings in Tampa Bay, and the acoustic properties and behavioral contexts of these sounds were investigated. Additional recordings were obtained from Sarasota Bay and Mississippi Sound. These low frequency narrow-band (LFN) sounds were tonal, had peak frequencies between 500 Hz and 1000 Hz, and were produced in trains. Inter-LFN intervals (the time duration between sequential LFN sounds) were significantly longer in recordings from Mississippi Sound. Sounds were correlated with social behavior, and were common during socio-sexual behavior. These sounds were found below optimal hearing range of bottlenose dolphins, and are prone to masking by boats.
A combination of autonomous acoustic recorders and visual surveys were used to determine the distribution and sound production patterns on the WFS. Visual surveys supported the results of previous studies indicating that bottlenose dolphins were more common in coastal areas and off of Tampa Bay, while Atlantic spotted dolphins (Stenella frontalis) were more common beyond the 20 m isobath. A single group of rough-toothed dolphins (Steno bredanensis) was observed. Overall, dolphin numbers decreased from inshore to offshore. Acoustic detections mirrored this distribution pattern, however acoustic detections were not as high in coastal regions as expected from the visual survey results, which suggests low sound production rates by coastal dolphins. Atlantic spotted dolphin numbers increased in more northern and inshore waters in spring, suggesting a seasonal migration pattern. Peaks in dolphin sounds in the coastal regions were commonly observed in daylight and evening hours, while in offshore areas sound production peaked at night. This pattern likely reflects foraging activity, and the diel activity cycles of common prey species. Coastal dolphins made proportionately more echolocation than whistles, while the opposite was true for deeper water dolphins.
In inshore waters (< 25 m depth), dolphin sound production was generally positively correlated to water temperature (bottom temperature and sea surface temperature) and negatively correlated with chlorophyll, while the opposite pattern tends to occur in deeper waters (> 35 m). This delineation roughly coincides with the distribution patterns of oceanographic properties, prey species distribution, and the distribution of Atlantic spotted dolphins and bottlenose dolphin ecotypes. These results suggest a shift from a benthic based ecosystem to a phytoplankton based ecosystem with increasing depth on the WFS.
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Majewski, Steven R., Ricardo P. Schiavon, Peter M. Frinchaboy, Carlos Allende Prieto, Robert Barkhouser, Dmitry Bizyaev, Basil Blank, et al. "The Apache Point Observatory Galactic Evolution Experiment (APOGEE)." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625493.
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The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in the Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations of the Milky Way. After a three-year observing campaign on the Sloan 2.5 m Telescope, APOGEE has collected a half million high-resolution (R similar to 22,500), high signal-to-noise ratio (>100), infrared (1.51-1.70 mu m) spectra for 146,000 stars, with time series information via repeat visits to most of these stars. This paper describes the motivations for the survey and its overall design-hardware, field placement, target selection, operations-and gives an overview of these aspects as well as the data reduction, analysis, and products. An index is also given to the complement of technical papers that describe various critical survey components in detail. Finally, we discuss the achieved survey performance and illustrate the variety of potential uses of the data products by way of a number of science demonstrations, which span from time series analysis of stellar spectral variations and radial velocity variations from stellar companions, to spatial maps of kinematics, metallicity, and abundance patterns across the Galaxy and as a function of age, to new views of the interstellar medium, the chemistry of star clusters, and the discovery of rare stellar species. As part of SDSS-III Data Release 12 and later releases, all of the APOGEE data products are publicly available.
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Waag, Austin G. "A Novel Approach to Assessing Abundance and Behavior in Summer Populations of Little Brown Myotis in Yellowstone National Park." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1543850035971551.
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Metz, Tasha Lynn. "Factors influencing Kemp's ridley sea turtle (Lepidochelys kempii) distribution in nearshore waters and implications for management." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1247.
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Post-pelagic juvenile and subadult Kemp's ridley sea turtles (Lepidochelys kempii) (20-40 cm straight carapace length) utilize nearshore waters of the northwestern Gulf of Mexico as nursery or developmental feeding grounds. This study utilizes 10 years of entanglement netting data to characterize long-term abundance and distribution of Kemp's ridley sea turtles at index habitats in this region. Netting surveys were conducted during April-October 1993-2002, primarily at Sabine Pass, Texas and Calcasieu Pass, Louisiana. Additionally, this study takes an ecosystem-based approach to understanding factors influencing Kemp's ridley in-water abundance and distribution via the development of a conceptual model incorporating data on nesting dynamics, environmental conditions, prey availability, and predation pressure.
Overall monthly mean ridley catch-per-unit-effort (CPUE) peaked in the beginning of summer (April-June), probably in response to rising water temperatures and seasonal occurrence of blue crab prey. Annual mean ridley CPUE across all study areas peaked in 1994, 1997, 1999 and 2002, suggesting a 2-3 year cycle in abundance that may be related to patterns in clutch size or hatch success at the Rancho Nuevo, Mexico nesting beach. However, ridley CPUE in nearshore waters remained relatively constant or decreased slightly even as number of hatchlings released from Rancho Nuevo increased exponentially. Annual declines in Texas strandings since 1994 and subsequent increases in Florida counterparts since 1995 suggest a shift in ridley distribution from the western to eastern Gulf in recent years.
Significant declines in ridley CPUE at Sabine Pass since 1997 coincided with a concurrent reduction in blue crab size, but a similar trend was not detected at Calcasieu Pass. Kemp's ridley occurrence at study sites was not significantly related to shrimping activity/by-catch. There also were no biologically significant relationships between Kemp's ridley CPUE and abiotic factors, nor were ridleys deterred from utilizing areas frequented by bull sharks. Overall, nesting dynamics and prey availability were conceptual model components appearing to have the greatest influence on nearshore ridley occurrence.
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Kheir, Beik Louay. "Dynamics of soil organic matter amino acids : a carbon isotope approach." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0098.
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Cette thèse aborde un point clé du couplage entre ces cycles: la dynamique des molécules azotées (AAs) des matières organiques du sol (MOS). Par des expériences d'incubation, nous avons estimé que les flux de biosynthèse des AAs par les micro-organismes du sol lors du processus de décomposition sont de l'ordre de 25% de la biomasse nouvellement formée. Le profil des AAs individuels biosynthétisés de novo est plus dépendant du type de sol que de la nature du substrat. Dans chaque sol, il est très similaire à celui des AAs des MOS. La biodégradation de matériaux végétaux marqués en 13C a révélé la transformation rapide des protéines végétales en matériaux microbiens. Ces résultats montrent que les AAs des MOS sont d'origine microbienne. Nous avons mesuré le renouvellement du C des AAs à long terme dans les horizons de surface de neuf sites présentant des végétations, climats et types de sol variés, en utilisant la technique de traçage par les abondances naturelles en 13C. L'âge moyen du carbone des AAs varie de 50 à 200 ans. Un modèle simple permet de discuter les hypothèses du recyclage des AAs des MOS par les micro-organismes. Les rapports isotopiques stables des AAs individuels ont été mesurés par chromatographie en phase gazeuse couplée à la spectrométrie de masse isotopique. À cette fin, nous avons développé une méthode d'étalonnage générique pour la détermination du rapport isotopique des composés spécifiques, par analyse de cultures microbiennes uniformément marquées. Au-delà des résultats présentés, l'étude apporte un large ensemble de données des AAs et examine les variations de l'abondance naturelle en 13C entre les AAs individuelsWe analyzed the coupled dynamics of C and N in Soil Organic Matter (SOM) through the dynamics of N-containing soil organic compounds (amino acids (AAs)) by tracing their carbon atoms. Stable isotope ratios of individual amino acids were measured by gas chromatography coupled with isotope ratio mass spectrometry. For this purpose, we developed a generic calibration method for compound-specific stable isotope ratio analysis, based on the analysis of uniformly labelled microbial cultures. We quantified the biosynthesis of AAs associated with the biodegradation process in four contrasted topsoils through short-term incubation experiments of 13C-labelled substrates. Amino acids-C accounts for ca. 25% of the newly-formed microbial biomass-C. The composition of the de novo biosynthesized individual amino acids was dependent on the soil type, and in each soil was similar to that of SOM amino acids. Biodegradation of 13C-labelled plant materials revealed the rapid conversion of plant proteins into microbial materials. These results together demonstrate that SOM amino acids are of microbial origin. We measured the dynamics of amino acids-C on the long term (decades to centuries) in nine sites using the natural 13C-labelling technique. On average, the age of AAs was equal or slightly inferior to that of bulk soil organic carbon, with mean ages ranging from 50 to 200 years. We built a conceptual model of AAs dynamics to discuss various hypotheses of AAs stabilization. Beyond these perspectives on C and N coupling in soil processes, the overall study brings a broad dataset of amino acids, as well as discuses variations of 13C natural abundance (δ13C) in-between individual amino acids
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Lim, Kar-Yong. ""The sufferings of Christ are abundant in us" (2 Cor 1:5) : a narrative dynamics investigation of Paul's sufferings in 2 Corinthians." Thesis, University of Wales Trinity Saint David, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683346.
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Rodgers, Erin V. "Scales of Resilience: Community Stability, Population Dynamics, and Molecular Ecology of Brook Trout in a Riverscape after a Large Flood." Antioch University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=antioch1422195420.
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Thorstenson, Candice [Verfasser], Matthias [Akademischer Betreuer] Ullrich, Matthias [Gutachter] Ullrich, Frank Oliver [Gutachter] Gloeckner, and Mathias [Gutachter] Wegner. "The Impact of Environmental Changes on the Microbial Community Dynamics and Abundance of Pathogenic Vibrio species in Coastal Ecosystems / Candice Thorstenson ; Gutachter: Matthias Ullrich, Frank Oliver Gloeckner, Mathias Wegner ; Betreuer: Matthias Ullrich." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2021. http://d-nb.info/1232075205/34.
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Banks, Aaron M. "The seasonal movements and dynamics of migrating humpback whales off the east coast of Africa." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4109.
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Data collected during boat-based and aerial surveys were used to describe population structure, movements, temporal patterns of migration and skin condition of humpback whales in breeding sub-stock C1-S off southern Africa. Results confirmed that the migration route along the south coast of South Africa is linked to the winter ground off Mozambique. A lack of exchange between breeding sub-stocks C1-N and C1-S was found, suggesting that these are independent of each other. Molecular analysis revealed unexpected levels of population structure between the migration route and the winter ground of C1-S, as well as the possibility that this migration route is also utilised by some individuals from breeding sub-stock C3. A skin condition of unknown aetiology that primarily affects humpback whale mother-calf pairs was identified. The first assessment of its prevalence and severity was made, providing a baseline for future monitoring. Humpback whale abundance in an inshore region of Bazaruto Archipelago, Mozambique was estimated and attempts were also made to use the limited information off Plettenberg Bay/Knysna, South Africa. In addition to improving our understanding of humpback whales from Breeding Stock C, knowledge about another baleen whale species utilising the southwest Indian Ocean was extended. The first evidence of southern right whale presence off the coast of Mozambique since the cessation of whaling was documented. It remains unknown whether this is a remnant sub-stock or the recovering South African sub-stock reoccupying its historical range.
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Stevens, Heike [Verfasser], and Meinhard [Akademischer Betreuer] Simon. "Heterotrophe Bakteriengemeinschaften des Deutschen Wattenmeeres : Diversität, Dynamik und Abundanz = Communities of heterothropic bacteria in the German Wadden Sea / Heike Stevens. Betreuer: Meinhard Simon." Oldenburg : IBIT - Universitätsbibliothek, 2004. http://d-nb.info/1016980728/34.
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Muñoz, Camarillo Gloria. "La colonización del mejillón cebra, Drcissena polymorpha (Bivalvia: Dreisscnidae) en el tramo final del río Ebro: factores que controlan su distribución y abundancia." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/111332.
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El mejillón cebra, Dreissena polymorpha (Pallas, 1771), es conocido por ser una de las especies invasoras de agua dulce más dañinas, tanto desde el punto de vista ecológico como económico, a nivel mundial. Este exitoso bivalvo invasor es originario de la región Ponto-Cáspica y ha sido introducido en gran parte de Europa y Norte América. En el año 2001 fue descubierto en aguas de la Península Ibérica, concretamente en el bajo Ebro. Desde entonces las poblaciones de mejillón cebra se han extendido a gran parte de dicha cuenca e incluso a otras cuencas de la Península.
Los importantes impactos tanto ecológicos como económicos producidos por el mejillón cebra en las masas de agua que ha colonizado han fomentado el estudio de dicha especie. En el caso de la cuenca del Ebro los trabajos realizados aún son escasos. La presente tesis se centra en el estudio de las poblaciones de mejillón cebra del tramo bajo del Ebro, entre la cola del embalse de Mequinenza (Zaragoza) y el límite superior de la zona estuarina (Tarragona).
A lo largo del presente trabajo se obtuvo información sobre la estructura, los patrones de distribución y la dinámica de las poblaciones de mejillón cebra presentes en los embalses de Mequinenza, Ribarroja y Flix durante un año completo. Se estudiaron los estadios larvarios planctónicos y sésiles, y se analizó la relación de cada uno de los estadios poblacionales con las variables ambientales de los embalses. Los resultados permitieron establecer que las poblaciones de los embalses de Mequinenza y Ribarroja no se encuentran sincronizadas entre sí. La densidad de larvas en los embalses fue mayor en el embalse de Mequinenza, seguido del de Ribarroja y por último de Flix.
La mayor parte de los estudios realizados sobre el mejillón cebra se centran en sistemas lénticos, como lagos o embalses. Sin embargo, las preferencias de hábitat de la especie en sistemas lóticos son poco conocidas. Por ello también se evaluó la relación existente entre las variables ambientales y las poblacionales en el tramo fluvial del bajo Ebro desde la presa de Flix hasta el comienzo de la cuña salina. Los trabajos realizados pusieron de manifiesto que el tramo fluvial estudiado se ve fuertemente afectado por la presencia aguas arriba del sistema de embalses.
Además, se calculó la tasa de filtración de la especie en este tramo del río por ser un parámetro de importancia tanto para la regulación de las poblaciones como por el efecto que pueden tener sobre la ecología de las masas de agua. Por último se realizó un modelo de dinámica poblacional capaz de simular la densidad de la especie a lo largo del tiempo. Dicho modelo se desarrolló con datos bibliográficos y con datos generados durante los trabajos realizados en la presente tesis. La construcción del modelo permitió determinar que la dinámica poblacional interanual del mejillón cebra en los embalses del bajo Ebro se ajusta a un modelo de carácter cíclico y denso-dependiente.The zebra mussel, Dreissena polymorpha (Pallas, 1771), is known to be one of the worst freshwater invasive species worldwide. This successful invasive bivalve is native to the Ponto-Caspian region and has been introduced throughout Europe and North America. It was first discovered in the Iberian Peninsula in the lower Ebro River in 2001. Since its invasion the zebra mussel has spread throughout most of the Ebro river basin and other catchments of the Iberian Peninsula. The high ecological and economical impacts caused by the zebra mussel have promoted the study of this specie. In the case of the Ebro river basin studies are still scarce. The present PhD thesis focuses on the study of zebra mussel populations established in the lower Ebro River, between the Mequinenza reservoir (Zaragoza) and the beginning of the estuarine area (Tarragona). Throughout the present study information on the structure, distribution patterns and population dynamics of the zebra mussel present in the Mequinenza, Ribarroja and Flix reservoirs, was obtained for a full year. Planktonic and sessile larval stages were studied, and their relationship with reservoirs’ environmental variables were analyzed. Most studies on the zebra mussel are focused on lentic systems, such as reservoirs or lakes, where populations reach higher densities. However, the habitat preferences of this species in lotic systems are poorly known. Therefore, in this PhD thesis the relationship between environmental and water physicochemical parameters and the abundance and distribution of the zebra mussel in the lower Ebro River, from the Flix reservoir to the limit of the salt wedge was assessed. Moreover, the filtration rate of the zebra mussel inhabiting this river stretch was calculated. This parameter was determined because of its importance in both the zebra mussel populations’ auto regulation and the potential effects on colonized water bodies. Finally, a population dynamics model to simulate the zebra mussel abundance over time was developed. The construction of this model was performed with both bibliographic information and own data generated in the present PhD thesis.
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Ogonowski, Martin. "Studies on Baltic Sea mysids." Doctoral thesis, Stockholms universitet, Systemekologiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-75236.
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Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish. Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements.At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Accepted; Paper 3: Submitted; Paper 4: Accepted
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Ballaud, Flore. "Dynamique spatio-temporelle des communautés virales et microbiennes des tourbières à Sphagnum." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S166/document.
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Les tourbières couvrent 3 % des surfaces continentales et jouent un rôle important dans le cycle du carbone en stockant le tiers du carbone des sols. L'accumulation de tourbe est liée au déséquilibre production primaire/décomposition du à une activité microbienne limitée par les conditions environnementales. L'infection et la lyse virale ont un impact sur la diversité et l'activité des communautés microbiennes, et influent sur le cycle du carbone. Cependant, le fonctionnement de ce compartiment viral n'avait jamais été pris en compte dans les études de fonctionnement des tourbières. Le but de ce travail de thèse était d'analyser et comprendre la dynamique spatiale et temporelle de l'abondance et de la diversité virale des tourbières à Sphagnum. L'analyse de l'abondance virale et procaryote et de 12 metaviromes en lien avec la physico-chimie d'une tourbière tempérée en France montre une forte variation saisonnière des communautés virales. Cette variation semble très liée aux conditions environnementales générées par la fluctuation de la nappe d'eau. Dans cette même tourbière, l'analyse de la diversité taxonomique et fonctionnelle des communautés de microorganismes présents (métagénomes) et métaboliquement actifs (métatranscriptomes) indique que la structure taxonomique est différente entre les des deux principaux stades, le fen et le bog, mais que ces communautés présentent une diversité fonctionnelle similaire, dont l'expression est liée aux changements des conditions environnementales avec la profondeur. L'abondance des particules virales étudiées dans 5 tourbières à Sphagnum réparties en Finlande, au Canada, en France, et sur l'île subantarctique d'Amsterdam varie fortement avec les sites. L'analyse de la diversité virale de la matrice et de l'eau de tourbe du Canada et de Finlande montre que la diversité virale est structurée par le site, puis le stade dynamique, puis la profondeur, avec un rôle important de la saturation en eau au niveau du site. Ces résultats valident le fonctionnement proposé du compartiment viral et de la communauté d'hôtes procaryotes. Ces connaissances ont été utilisées pour analyser le fonctionnement du compartiment microbien de tourbières à Sphagnum soumises à des perturbations d'origine anthropique. Les 31 métaviromes produits pour cette thèse constituent l'une des plus grandes bases de données sur la diversité virale des écosystèmes alors que la diversité virale des sols n'avait presque jamais été étudiée auparavantPeatlands cover 3 % of the continental surfaces but represent up to a third of the soil carbon stock. Peat accumulation results from the imbalance between primary production and decomposition due to the limitation of the prokaryote activity caused by the environmental conditions. Viral infection and lysis impact the diversity and the activity of the microbial communities and influence the carbon cycle. However, the functioning of the viral compartment had never been taken into account in peatlands. The aim of this thesis was to gain knowledge about the spatio-temporal dynamic of viral abundance and diversity in Sphagnum-dominated peatlands. Spatio-temporal analysis of viral and prokaryote abundance and of 12 metaviromes (viral diversity) in relation to the physico-chemical features in a temperate Sphagnum-dominated peatland in France revealed the high seasonal variability of the viral communities. This dynamic appeared mainly related to the environmental conditions shaped by the fluctuation of the water-table level. In the same peatland the taxonomic diversity of the present microorganisms (metagenomes) differed between the fen and the bog, but these communities present a similar functional diversity, which expression in selected in the same way in the two dynamic stages, in relation to depth-related environmental conditions. Viral abundance analyzed in 5 Sphagnum-dominated peatlands from Finland, Canada, France and subantarctic Amsterdam Isle presented a high geographical variability. Investigation of the diversity of the viral communities from the peat matrix and the pore-water in Finland and Canada emphasized the structuration of the viral communities by the site, then the dynamic stage, and finally depth. These results confirm the first hypotheses about the functioning of the viral compartment depending on environmental conditions and prokaryote activity. Effects of human-derived disturbances on viral ecology in peatlands were investigated based on this knowledge. While soil viral diversity was poorly documented at the start of this thesis, the collection of 31 metaviromes from Sphagnum-dominated peatlands produced for this project represents the second largest dataset representing the viral diversity from environmental samples
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Brun, Mélanie. "Aide à la décision pour la conservation des populations de saumon atlantique (Salmo salar L.)." Thesis, Pau, 2011. http://www.theses.fr/2011PAUU3015/document.
Full textAbstract:
La gestion durable des ressources naturelles vivantes est un problème majeur dans un contexte de raréfaction, dû à l'impact de l'homme et à une incertitude omniprésente. Améliorer les outils existant et en développer de nouveaux pour conseiller les gestionnaires sur l'évolution potentielle des ressources naturelles vivantes, selon divers scénarios environnementaux et de gestion, est nécessaire. Cette thèse a pour but de contribuer au développement d'une méthodologie pour l'aide à la décision pour la gestion des ressources naturelles vivantes, tout en prenant en compte les sources d'incertitude majeures. Ce travail est appliqué au cas de la population de saumon atlantique (Salmo salar L.) de la Nivelle (France). Cette population fait l'objet d'un programme de suivi à long terme et cette espèce a été largement étudiée. Cette dernière est menacée mais elle est toujours ciblée par la pêche commerciale et récréative. Elle illustre la dualité entre conservation et exploitation, qui est au coeur de la gestion des ressources naturelles vivantes. Pour gérer une population, il est nécessaire de comprendre sa dynamique et de prédire son évolution sous divers scénarios environnementaux et de gestion. L'approche Bayésienne fournit un cadre cohérent pour quantifier l'incertitude sous ses différentes formes. Les modèles hiérarchiques permettent l'assimilation de sources de données multiples et de faire des inférences et des prédictions sur des grandeurs spatio-temporelles inconnues. Un modèle stochastique d'état Bayésien, i.e. un modèle hiérarchique Bayésien dynamique, est construit pour étudier la dynamique de la population d'intérêt et pour prédire son évolution. La théorie de la décision en univers incertain fournit un cadre pour aider un individu dans ses choix, mais son application reste difficile. En théorie, une fonction d'utilité qui dépend des conséquences des alternatives de gestion reflète les préférences d'un individu unique impliqué dans un problème décisionnel. En pratique, sa construction est malaisée. Premièrement, il estdifficile de définir une valeur pour chaque conséquence. Deuxièmement, il y a généralement plus d'un individu impliqué dans le problème décisionnel. Par conséquent, on obtient une classe de fonctions d'utilité. De par les différents intérêts, souvent conflictuels, que les gestionnaires ont à prendre en compte, la fonction d'utilité est multi variée. Dans cette thèse, une classe de fonctions d'utilité bi-variées est construite. Elle prend en compte l'incertitude concernant la fonction, les variations de préférence entre les acteurs et la dualité d'intérêts exploitation vs conservation. Ensuite, une analyse de la robustesse est réalisée pour étudier si la décision optimale, i.e. l'utilité espérée maximale, varie lorsque la fonction d'utilité varie.La méthodologie développée dans cette thèse s'est avérée possible et fructueuse. Elle fournit un cadre cohérent pour organiser les interactions entre scientifiques, acteurs et gestionnaires pour atteindre une compréhension commune des problèmes de décision dans la gestion des ressources naturelles vivantes. En reconnaissant explicitement la diversité des acteurs, elle permet d'identifier des conflits potentiels et de guider les gestionnaires vers des compromis acceptables. Cependant, elle demande un haut niveau de formation et d'expertise en modélisation et en calcul. Elle implique également un temps d'analyse important. Comment rendre ces exigences compatibles avec le niveau actuel d'expertise et les agendas à court terme des structures de gestion est un challenge principal pour le futurThe sustainable management of natural living resources is a major issue in a context of increasing scarcity due to human impact and of pervasive uncertainty. Improving existing tools and developing new ones to advise decision makers on the potential evolution of natural living resources, according to various management and environmental scenarios, is requested. This PhD aims at contributing to the development of a methodology for decision making for natural living resources management, while taking into account major sources of uncertainty. This is achieved through the study case of the Atlantic salmon (Salmo salar L.) population ofthe Nivelle River (France). This population is subjected to a long term monitoring program and the species has been extensively studied. Atlantic salmon is a threatened species but still targeted by commercial and recreational fisheries. It illustrates the duality between conservation and exploitation which is at the heart of natural living resource management. To manage a population, it is necessary to understand its dynamics and to predict its evolution under various management and environmental scenarios. The Bayesian approach provides a coherent framework to quantify uncertainty in its different forms. Hierarchical models allow the assimilation of multiple sources of data and to make spatio-temporal inferences and predictions. A Bayesian state space model, i.e. a Bayesian dynamic hierarchical model, is constructed to study the dynamics of the population of interest and topredict its evolution. The decision theory under uncertainty provides a framework to help an individual in its choices, but its application still raises difficulties. In theory, a utility function depending on the consequences of alternative actions reflects the preferences of a single individual involved in a decision problem. In practice, its construction is challenging. Firstly, it is difficult to assign a value for each consequence. Secondly, there is usually more than one individual involved in the decision problem. Consequently, we obtain a set of utility functions. Due to the various and often conflicting interests the decision maker has to take into account, the utility function is multivariate. In this PhD, a set of bivariate utility functions is constructed. It accounts for the uncertainty about the function, the variation of preferences among stakeholders and the dual interests of exploitation vs conservation. Next, a robustness analysis is performed to study if the optimal decision, i.e. associated to the maximum expected utility, varies when the utility function varies. The methodology developed in this PhD proved practicable and fruitful. It provides a coherent framework for organizing the interactions between scientists, stakeholders and decision makers for reaching a common understanding of decision problems in the management of natural living resources. By acknowledging explicitly the diversity among stakeholders, it allows to identify potential conflict and it helps guiding decision makers towards acceptable trade-off actions. However, it requires a high level of training and expertise in modelling and computation. It involves also thoughtful and time consuming analyses. How to render these requirements compatible with the current level of expertise and the short term agendas of management bodies is a main challenge for the near future
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Dekhil, Myriam. "RMN cristallographique : mesure de distances internucléaires sur des échantillons de poudre par RMN du solide." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4734.
Full textAbstract:
La mesure de couplage dipolaire permet d’accéder à la structure tridimensionnelle d’un composé solide. Cependant, en présence d’une forte densité de spins couplés, le phénomène de troncature dipolaire rend difficile l’obtention de ces informations par RMN du solide. Ce problème peut être affranchi par l’étude de spins rares en abondance naturelle. En effet, avec une abondance naturelle de 1.1 %, la probabilité que trois 13C soient couplés, et avec elle la troncature dipolaire, devient négligeable. Une méthodologie basée sur la séquence de recouplage dipolaire POST-C7 permet d’accéder à des informations structurales d’échantillons en abondance naturelle sensibles à la fois à la conformation moléculaire et à l’empilement cristallin par mesure de couplages dipolaires 13C-13C. La sensibilité de détection des signaux RMN 13C est augmentée à l’aide la polarisation dynamique nucléaire ce qui permet de réduire considérablement les temps d’expériences. De plus, la séquence de recouplage R20_9_2 aidée de supercycles s’est montrée être plus robustes que POST-C7 face à de fortes anisotropies de déplacement chimique ou de forts couplages hétéronucléaires 1H-13C. La seconde problématique abordée concerne l’attribution de signaux 13C. En effet, il existe seulement quelques exemples de détermination de connectivités 13C -13C en abondance naturelle. Nous montrons ici que des spectres de corrélations dipolaires 13C-13C peuvent être obtenus en quelques jours à l’aide de la séquence de recouplage R20_9_2. Contrairement aux méthodologies basées sur le couplage J, notre séquence requiert un temps d’excitation DQ plus court ce qui la rend adaptée à l’étude de solides désordonnésMeasurment of dipolar coupling provides 3D structural information of powder samples. However, in practice, the high density of spins in organic compounds prevents the measurements of long-range dipolar couplings in solid-state NMR by the so-called dipolar truncation effect. The study of rare spins on natural abundance allows to overcome this problem. In fact, with a natural abundance of 1.1 %, the probability for three 13C to be coupled is negligible. We developed a methodology based either on the dipolar recoupling NMR pulse sequence POST-C7 or on the dramatic increase in sensitivity provided by dynamic nuclear polarization. We demonstrated that its methodology provides a measure of 13C-13C dipolar couplings in natural abundance powder samples and that the so-obtained distance information is sensitive to both molecular conformation and crystal packing of powder samples. Moreover, we show that the recoupling pulse sequence R20_9_2 is more robust to strong chemical shift anisotropy and also to strong 1H-13C heteronuclear dipolar couplings than POST-C7. The second challenge involves 13C signal assignment for natural abundance. In fact, there are only a few examples of 13C-13C correlation spectra obtained for natural abundance samples. Here, we show that 13C-13C correlation spectra sequence based on the reintroduction of 13C−13C dipolar couplings can be obtained with standard MAS probe and within few days using R20_9_2 pulse sequence. Contrary to pulse sequences based on 13C-13C J coupling, our pulse sequence requires shorter DQ excitation time and hence, is more suitable for samples having short T2 relaxation times such as amorphous solids
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Dias, Bruno Moreira de Souza. "Formation and evolution of globular clusters in the Galaxy and Magellanic Clouds." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/14/14131/tde-26082014-090039/.
Full textAbstract:
Globular clusters are tracers of the formation and evolution of their host galaxies. Kinematics, chemical abundances, age and position of the clusters allows tracing interactions between Milky Way and surrounding galaxies and outlines their chemical enrichment history. In this thesis we analyse mid-resolution spectra of about 800 red giant stars in 51 Galactic globular clusters. It is the first time that [Fe/H] and [Mg/Fe] derived in a consistent way are published for such a huge sample of globular clusters, almost 1/3 of the total number of catalogued clusters. Our metallicities are showed to be more precise than previous works based on mid-resolution spectroscopy. A turnover at [Fe/H] ~ -1.0 is found in the plot [Fe/H] vs. [Mg/Fe] for bulge and halo, although bulge seems to have a more metal-rich turnover, i.e, bulge has more efficient formation than the halo. Comparing the abundances with age the timescale for SNIa to start to become important is 1Gyr. [Fe/H] vs. age corroborates the different star formation efficiency of bulge and halo while [Mg/Fe] does not follow that. Halo was formed in mini halos or dwarf galaxies, and two multiple population clusters had their origin analysed to check it. M 22 seems to have been formed in the Milky Way while NGC 5824 possibly was originated in a dwarf galaxy, although our results are inconclusive for NGC 5824. The Galactic bulge seems to have been formed fast i.e., probably the oldest globular cluster is there. In fact HP 1 has a bluer horizontal branch than expected for its metallicity and we interpret that as an age effect. We determine its distance using light curves of variable stars in order to constrain future age determinations via colour-magnitude diagram. Finally, we investigate interaction between Milky Way and its neighbour galaxy SMC. We find that some star clusters are being stripped out of the SMC main body, which is consistent with tidal stripping scenario for the interaction between the galaxies, instead of ram pressure that would only affect gas.Aglomerados globulares são traçadores da formação e evolução de suas galáxias. Cinemática, abundâncias químicas, idades e posições dos aglomerados permitem traçar interações entre Via Láctea e galáxias vizinhas e suas histórias de enriquecimento químico. Nesta tese analisamos espectros de média resolução de mais de 800 estrelas gigantes vermelhas em 51 aglomerados globulares Galácticos. É a primeira vez que [Fe/H] and [Mg/Fe] determinados de modo consistente são publicados para uma amostra desse porte, ~1/3 dos objetos catalogados. Nossas metalicidades são mais precisas que trabalhos anteriores similares. Uma quebra em [Fe/H] ~ -1.0 é encontrada no gráfico [Fe/H] vs. [Mg/Fe] para o bojo e halo, embora bojo parece ter uma quebra em [Fe/H] maior, i.e, bojo tem formaçãao mais eficiente que o halo. Comparando abundâncias com idade, a escala de tempo para SNIa ficar importante é 1Gano. [Fe/H] vs. idade corrobora diferentes eficiências de formação do bojo e halo, mas [Mg/Fe] vs. idade não mostra isso. O halo foi formado em mini halos ou galáxias anãs, e dois aglomerados com dispersão em [Fe/H] tiveram suas origens analisadas. M 22 parece ter sido formado na Via Láctea e NGC 5824 possivelmente foi originado em uma galáxia anã, embora os resultados são inconclusivos para NGC 5824. O bojo parece ter sido formado rapidamente e deve possuir o aglomerado mais velho. De fato, HP 1 tem um ramo horizontal mais azul que o esperado para sua metalicidade e vemos isso como um efeito da idade. Determinamos sua distância usando curvas de luz de RR Lyrae de maneira a restringir futuras determinações de idade via diagrama cor-magnitude. Finalmente, investigamos a interação entre Via Láctea e sua galáxia vizinha SMC. Encontramos aglomerados sendo removidos do corpo central da SMC, consistente com cenário de remoção por força de maré para a interação entre as galáxias, em vez de ``ram pressure\'\' que afeta só gás.
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Newlands, Nathaniel K. "Shoaling dynamics and abundance estimation : Atlantic bluefin tuna (Thunnus thynnus)." Thesis, 2002. http://hdl.handle.net/2429/13501.
Full textAbstract:
The Atlantic bluefin tuna (Thunnus thynnus) is a long-lived, highly migratory species
that attains sizes of 2.20 m, and weights of 300 kg or more. Adults undertake cyclic
migrations between coastal feeding zones, offshore wintering areas and spawning grounds.
During June through October, bluefin tuna are common off the eastern United States
and Canada, entering the Gulf of Maine, a semi-enclosed continental shelf area. The
population is currently believed to have plummeted to 20% of 1970's levels, yet there is
significant uncertainty in their population status and size.
This thesis investigates bluefin tuna movement, aggregation and distribution, size and
structure of bluefin shoals, and examines how these factors can affect the measurement
bias and estimation uncertainty of population abundance. Data analysis methods applied
include: interpolation of movement data, Lomb spectral analysis, statistical bootstrap
simulation, Kalman filtering, and geostatistics. An automated digital image analysis
system (SAIA) is developed for the three-dimensional analysis of fish shoal structure. A
theoretical model is also formulated to describe the movement and behaviour of shoaling
tuna leading to changes in shoal aggregation, distribution and abundance. The precision
in abundance estimation of random, systematic, stratified, and spotter-search aerial
survey sampling schemes are simulated under changes in the size, distribution and aggregation
of shoals.
Correlated and biased random walk models can predict lower and upper limits on
displacement and spatial movement range over time. Bluefin tuna move by responding
to changes in temperature gradients and to the local abundance of prey, preferring
to be situated in the warmest water available, while also showing a weak response to
flow and bathymetric gradients. The effect of aggregation on the distribution of shoals
considerably reduces precision of population estimates under random transect sampling.
Stratified sampling is shown to increase precision to within 5%, with adaptive stratification
leading to further increases. Movement and shoal aggregation introduce relatively
equal levels of bias and uncertainty in estimating abundance. Results indicate that reliable
estimates of abundance can be attained under systematic and stratified survey
schemes. However, further reductions in uncertainties associated with the shoal aggregation
process are necessary to achieve acceptable precision in abundance estimation.
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Reyna, Kelly Shane. "The Texas Quail Index: Evaluating Predictors of Quail Abundance Using Citizen Science." 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3090.
Full textAbstract:
Annual abundance of northern bobwhite (Colinus virginianus) and scaled quail
(Callipepla squamata) fluctuates drastically in Texas, which complicates a quail
manager’s ability to forecast quail abundance for the ensuing hunting season. The Texas
Quail Index (TQI) was a 5-year citizen-science project that evaluated several indices of
quail abundance and habitat parameters as predictors of quail abundance during the
ensuing fall. I found that spring cock-call counts explained 41% of the variation in fall
covey-call counts for all study sites in year 1–4, and 89% of the variation in year 5.
Further investigation revealed that year 5 was a drought year and had a significantly
lower percentage of juveniles in the hunter’s bag. These results suggest that during
drought years, fall quail abundance is more predictable than during non-drought years
and that low breeding success may be the reason. If these data are correct, quail
managers should have a better ability to predict the declines of their fall quail abundance
in the dry years.
The TQI relied on citizen scientists (cooperators) to collect data. Since most
(66.1%) cooperators dropped out of the program, and <8% of all data sets were complete, I surveyed the cooperators by mail to determine the rate and cause of
cooperator decline and to identify characteristics of a reliable cooperator (i.e., one that
did not drop out of the study). I found that cooperator participation declined earlier each
year for year 1–4, and that year 5 demonstrated a steady trend with the least amount of
cooperators. Most respondents who dropped out (61.5%) reported their motive for
leaving was that it was too time consuming. I found no difference in mean cooperator
demographics, satisfaction, or landownership goals between those respondents who
dropped out and those that did not. However, 38% of those who dropped out were not
completely satisfied with communication from TQI coordinators compared to only 15%
of those who did not drop out, indicating that communication, or perhaps overall
volunteer management, might have been improved. Future studies should maintain
better communication with participants, require less time, and provide an incentive for
retention.
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Sun, Mengmeng. "Regional Climate Effect on Population Abundance of Major Duck Species in Interior Plains of Canada." Thesis, 2013. http://hdl.handle.net/1969.1/149518.
Full textAbstract:
Population dynamics of ducks is a complex process influenced by both biotic and abiotic factors, and good understanding about the mechanisms behind this process is needed not only for the management of duck harvest but also for the conservation of wetland, which is under threat in the face of land change and climate warming. Basic time series analysis techniques, such as correlogram, partial correlogram and periodogram, cluster analysis and partial least squares regression (PLSR) are applied to the long-term breeding population data gathered by Waterfowl Breeding Population and Habitat Survey and monthly weather data from Environment Canada in order to explore the pattern in the duck abundance data and the effect of local weather on population dynamics of ducks.
Results of above analysis show that the duck abundance of previous years has short but strong correlation with the duck abundance of following years suggesting a large part of variability in duck abundance is explained by the abundance of previous years, especially that of last year. There is also clear periodic pattern in the duck abundance data, but the length of the cycle varies both for duck species and ecozones suggesting separating duck species and ecozones for analysis is necessary. The effects of weather on duck populations appear weak or absent in most PLSR models; this is consistent with previous studies. More detailed information, such as age structure of the duck populations and interspecific interactions, will be needed for future modeling. Among the small number of PLSR models exhibiting the weather effect, results suggest potential mechanisms, such as the impact of weather on recharge and discharge of wetland basins and nest failure caused by flooding.
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Chen, Szu-Hung. "Abundance and Distribution of Africanized Honey Bees in an Urban Environments." Thesis, 2013. http://hdl.handle.net/1969.1/149251.
Full textAbstract:
Africanized honey bees (AHB) are a hybrid between African and European honey bees (EHB). Compared to the EHB, AHB exhibit more intense, defensive behaviors but nevertheless provide the same important ecosystem service--pollination. AHB have been found in Tucson, AZ. since 1993. It is important to understand the population ecology of AHB for several reasons. Most directly, the behavioral traits retained from African bees present public safety and health risk. AHB are easily agitated; even slight disturbances (e.g., human movements) can provoke attacks. Several hybridized bee traits (e.g., higher colony growth rates, reproduction at a smaller colony size, nesting in a wider range of cavity materials, etc.) also make them more adapted to urban landscapes. The overlap of habitats and resource-using of AHB with human significantly raise the risk of stinging incidents, especially in the areas of bee aggregation. Although the presence of AHB in urban environments may present a public safety and health risk, they do contribute to urban ecosystems substantially through pollination. The fact that AHB is a part of the urban ecosystem suggests a need for a better understanding of the relationship among climate factors, urban landscape characteristics, and AHB population dynamics.
The goal of my dissertation was to understand population dynamics of AHB in urban environments using removal records of AHB colonies in water meter boxes. I have demonstrated useful methods and repeatable procedures to process, extract, and synthesize water meter box data which were not collected or sampled specifically for any ecological research. I also examined the spatio-temporal distributions of AHB colony removals in water meter boxes, and evaluated the effects of variations of temperature and precipitation on observed patterns. Then, I investigated the linkage between spatial patterns of AHB colonies and urban landscape characteristics by evaluating densities of water meter boxes, AHB colony abundance, and colony occupancy among different land cover/land use types. Lastly, a conceptual model and quantitative models were developed to illustrate AHB population dynamics, particularly and the interactions among water meter boxes, alternative cavities, and honey bee colonies.
Overall, the probabilities of AHB colonies selecting nesting sites can be influenced by: (1) the ratio of water meter boxes and alternative cavities; (2) the difference of vegetative attributes among locations associated with the preference of AHB in selecting new nesting sites. Seasonal variations of precipitation and temperature can affect the development and productivity of AHB population.
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Jian, Yun. "Prediction of Mosquito Abundance in Temperate Regions, Using Ecological, Hydrological and Remote Sensing Models." Diss., 2014. http://hdl.handle.net/10161/9436.
Full textAbstract:
New and old mosquito-borne diseases have emerged and re-emerged in temperate regions over the recent past, but an understanding of mosquito population dynamics, a fundamental step toward disease control, remains elusive. In particular, we are still lacking reliable predictive models of mosquito abundance in temperate areas due to the subtle links between the fluctuation of mosquito population and highly heterogeneous environmental drivers. Hence, this doctoral dissertation presents an interdisciplinary approach towards an improved understanding and prediction of the fluctuations in mosquito abundance in temperate regions. In the first part of this dissertation a hierarchical Gompertz-based model is used to assess the relative importance of endogenous (density dependence) and exogenous (environmental forcings) controls and their interactions in regulating the dynamics of a West Nile Virus vector (Culex pipiens) in the Po River delta in Italy. The results clearly detect the effects of density-dependence in the observed population dynamics for the mosquito species analyzed and highlight the controls exerted by environmental forcings and habitat conditions. Subsequently, the characteristic scales of temporal variability in mosquito populations, and the representativeness of observations at different sampling resolutions, are investigated using a 10 year daily mosquito sample from Brunswick County, North Carolina. The species present in the sample (among which Aedes vexans and Culiseta melanura are addressed in greater detail, as vectors of East Equine Encephalitis and West Nile Virus) are investigated using a combination of time series analysis, individual based simulations, and density-dependent modeling approaches. Significant population fluctuations with characteristic periodicity between 2 days and several years are found in response to different regulation mechanisms. In particular, the observed fast fluctuations are importantly determined by a varying mosquito activity, rather than by reproduction/mortality processes, driven by rapid changes in meteorological conditions. Finally, in the third part of this study, a state space reconstruction (SSR) approach is used to understand how the predictability of mosquito abundance varies with aggregation time scale and with the prediction horizon, and how much can the prediction of mosquito abundance be improved by using daily observations compared to the commonly used once-per-week samples. The results show that the predictability of mosquito abundance decreases as the time scale of the models increases from one week to one month, while the predictability of per capita growth rate increases together with the modeling scale. It is also shown that the prediction of mosquito per capita growth rate can be improved using daily abundance observations. Furthermore, many mosquito models compare the observed and predicted abundance as a measure of model performance. However, my results suggest that short term forecasts of mosquito abundance may appear to have a significant capability due to the positive autocorrelation between abundance in subsequent time steps, even when the model's ability to predict the abundance change is low. Model capability should thus be evaluated comparing observed and modelled per capita rates of change.
Dissertation
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JAGGARD, ERIN. "Soil Carbon Dynamics Following Switchgrass Establishment for Bioenergy Production in Southeastern Ontario." Thesis, 2012. http://hdl.handle.net/1974/7005.
Full textAbstract:
Switchgrass (Panicum virgatum), a perennial C4 grass species, has the capacity to not only improve the quality of the soil in which it grows but also promote soil carbon storage to offset rising atmospheric CO2. This research investigated soil organic carbon (SOC) dynamics beneath switchgrass using natural abundance 13C and soil carbon fractionation following the establishment of this crop in a native and predominantly C3 plant region in southeastern Ontario. I investigated SOC dynamics by sampling adjacent commercial switchgrass fields and appropriate paired control fields at sites where the time since switchgrass establishment varied from 4-11 years. SOC and natural 13C abundance were measured in paired fields to assess management-induced changes in the quantity, source, and turnover time of soil carbon. To better elucidate carbon cycling dynamics over a relatively short time since switchgrass establishment, multiple soil fractionation techniques were applied to better understand carbon dynamics of soil organic matter with various mean residence times. Establishment of switchgrass results in marginal increases in SOC, primarily at sites where intensive soil management (i.e. tillage) practices preceded switchgrass establishment. Changes were observed in some of the more labile SOC pools, as well as in the δ13C values of the bulk soil and soil carbon fractions, indicating that growing switchgrass was causing the incorporation of switchgrass-derived carbon into the soil. Even resistant SOC pools, with turnover times of over 100 years, incorporated significant quantities of switchgrass carbon in 11 years. Annual increases in SOC, however, were less than values reported elsewhere. The potential for soil carbon storage exists, likely due to longer mean residence times of the carbon in soils beneath switchgrass compared with other cultivation systems. Changes in SOC following switchgrass establishment related strongly to the amount of root biomass, time since establishment and prior soil management practices. The decomposition rates derived in this research should be integrated into soil carbon modeling applications intended to support the emergence of switchgrass in southeastern Ontario. The results of my research can advance soil carbon models and be used to make regional assessment of the potential impact of growing switchgrass for bioenergy in southeastern Ontario.Thesis (Master, Geography) -- Queen's University, 2012-01-30 13:56:06.269
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Gaivão, Maria Rocha Peixoto Azevedo. "Mathematical modelling of co-colonization and within-host abundance ratios in multi-type pathogen dynamics." Master's thesis, 2015. http://hdl.handle.net/10451/20039.
Full textAbstract:
Tese de mestrado, Bioinformática e Biologia computacional (Biologia computacional),Universidade de Lisboa, Faculdade de Ciências, 2015In recent years our understanding of infectious-disease epidemiology has been greatly increased through mathematical modelling. The major goal of any mathematical study in epidemiology is to develop understanding of the interplay between the variables that determine the course of infection within an individual, and the variables that control the pattern of infections within communities of people. The epidemiology of multi-type pathogen systems, such as dengue, malaria and pneumococcus are notoriously challenging. Direct and indirect interactions between multiple strains shape pathogen population processes, both at the level of a single host and at the population level. Quantifying these interactions is crucial, and the new technologies that are now available to detect multiple infections with different pathogen types are opening new avenues in this endeavour. In this thesis, motivated by the pneumococcus system, we study the colonization dynamics by a multi-type pathogen and focus particularly on co-colonization phenomena, which reflects the simultaneous colonization/infection (terms used in this thesis interchangeably) by two antigenic types of the same pathogen. We pretend to introduce strain ratios, first quantified by Brugger et al. (2010), when modelling the co-colonization phenomena. Therefore, a mathematical epidemiological model is constructed using ordinary differential equations to examine the prevalence and distribution of the co-colonization in the population. Interestingly, we find one scenario where the infection can still persist despite the basic reproduction number R0 being below 1. The phenomena of backward bifurcation is also observed. Moreover, the proportion of each double infected class, at equilibrium, is independent of the size of susceptible or single infected class. Based on a static epidemiological point of view, we also develop an within-host model to study the distribution of co-colonization in an average host. Both models show a clear equal abundance ratio (1:1) prevalence and this seems to be robust despite varying the parameters.
A Epidemiologia é uma ciência que estuda quantitativamente a distribuição dos fenómenos de saúde/doença, e seus factores condicionantes e determinantes, nas populações humanas. Esta permite ainda avaliar a eficácia das intervenções realizadas no âmbito da saúde pública. O fundador da teoria epidemiológica moderna é Ronald Ross cujo estudo no ciclo de vida da malária concedeu-lhe o Nobel em 1902. Este utilizou a modelação matemática para investigar a eficácia das intervenções na prevenção desta doença. No entanto, foi só no final do século XX que a modelação matemática se tornou mais popular. Nos últimos anos o nosso conhecimento relativo à epidemiologia das doenças infecciosas desenvolveu-se bastante devido à modelação matemática. O principal objectivo de qualquer estudo matemático em epidemiologia é melhorar o nosso entendimento relativo às relações das variáveis que determinam o curso de uma infecção quer ao nível do indivíduo como ao nível das comunidades. No entanto, devemos ter sempre em conta que os modelos são sempre abstracções/simplificações dos fenómenos em estudo e os resultados obtidos aproximações do sistema real. A modelação têm sido aplicada para o estudo de diversas doenças infecciosas tal como a sarampo, HIV ou a dengue. Estes modelos revelam-se ferramentas essenciais para compreender a dinâmica das doenças infecciosas e auxiliar no planeamento e controlo das mesmas. Nesta tese, estou interessada em estudar as dinâmicas das doenças infecciosas, mas mais precisamente, explorar através da modelação matemática o fenómeno de co-colonização ou também designado por múltipla colonização. Esta significa a colonização simultânea do hospedeiro por vários microorganismos (da mesma espécie ou diferente). É sabido desde há décadas que a co-colonização é um fenómeno comum na natureza e com importantes consequências para o hospedeiro e parasita. Para o hospedeiro, representa um desafio extra para o seu sistema imunitário. Para o parasita, conduz a interacções directas e indirectas entre as diversas estirpes alterando a sua dinâmica e transmissão. Geralmente este fenómeno agrava o estado de saúde do individuo em comparação com as infecções simples, ou seja, quando o individuo é unicamente colonizado por um parasita. Quantificar a interacção entre as diversas estirpes envolvidas revela-se por isso fundamental, e as novas tecnologias que estão hoje em dia disponíveis para detectar os diferentes patogénios envolvidos, estão a abrir caminho nesta área. Recentemente, Brugger et al. (2010) revelou com os seus estudos na bactéria Streptococcus pneumoniae, também conhecida por pneumoccocus, que a co-colonização tem uma prevalência de 7:9%. Aparentemente, é também mais comum para o hospedeiro apresentar sensivelmente a mesma proporção, usualmente designada por 1:1, entre as duas estirpes da bactéria. Esta prevalência foi também observada independentemente por Valente et al. (2012), mas desta vez em indivíduos saudáveis. Este padrão parece ser, por isso, independente do estado de saúde do indivíduo. O pneumococcus é uma bactéria gram-positiva que normalmente vive assimptomáticamente na nasofaringe e cuja prevalência está aumentada nos primeiros cinco anos de vida de um indivíduo. Ocasionalmente, esta pode migrar para outras regiões do corpo e potencialmente causar uma série de doenças, desde infecções respiratórias ligeiras (otites, etc.) até doenças mais invasivas (pneumonia, septicémia, meningite, etc.). O fenómeno da co-colonização parece também ser um importante factor para a evolução desta espécie, uma vez que representa uma oportunidade para a transferência horizontal de genes. Incorporar esta informação sobre os rácios nos modelos é relevante, uma vez que pode auxiliar na compreensão da sua dinâmica de transmissão e potencialmente prever o impacto de políticas de intervenção, tal como a vacinação. Para um organismo tão diverso como o penumococcus, com mais de 90 estirpes diferentes identificadas, a compreensão da sua biologia está longe de estar completa, e formular modelos reais ainda representa um desafio. Nesta tese foi feito um estudo detalhado acerca do padrão de cocolonização na nasofaringe por múltiplas estirpes do pneumococcus. Mais precisamente, pretendo compreender os factores que justificam a sua prevalência na população e a distribuição dos rácios de cocolonização no caso do hospedeiro apresentar duas estirpes. O principal objectivo deste estudo foi desenhar um modelo matemático que representasse adequadamente a infecção pelo pneumococcus para que o seu output fosse suficientemente preciso para explicar as características da distribuição das estirpes no hospedeiro. Nesse sentido, usei duas abordagens diferentes (mas complementares) para modelar a co-colonização. Em primeiro lugar, usando equações diferenciais ordinárias, construí um modelo epidemiológico determinístico com estrutura nos tipos de co-colonização. Esta abordagem parte da dinâmica de uma população com vista a estudar a distribuição num único indivíduo. Portanto caracteriza-se como uma abordagem topdown. Numa segunda abordagem, criei um modelo probabilístico que a partir da dinâmica da infecção no indivíduo, permite observar a distribuição das estirpes na população. Esta abordagem caracteriza-se como bottom-up. Em ambos os modelos, os resultados que obtive evidenciaram os mecanismos imunitários e estocásticos responsáveis pela distribuição dos rácios de co-colonização. Foi observada uma clara predominância dos rácios 1:1 e este resultado parece ser robusto quando se variam os parâmetros dos modelos. Foram identificados os equilibrios do sistema (trivial e endémico) e avaliada a sua estabilidade. Curiosamente, no modelo epidemiológico, encontrei um cenário em que a infecção pode persistir apesar do número básico de reprodução R0 ser inferior a 1. Este fenómeno tem o nome de backward bifurcation e consiste numa alteração estrutural da estabilidade dos equilíbrios, que deve-se essencialmente ao facto do modelo desenvolvido estruturar os hospedeiros co-colonizados em classes. Estas em média apresentam um número básico de reprodução superior aos hospedeiros colonizados por uma única estirpe. Assim, contribuem em média para uma maior transmissão da infecção na população. Também a proporção de cada classe de hospedeiros duplamente infectados relativamente ao total de hospedeiros infectados, no equilíbrio, é independente da magnitude da classe dos susceptíveis ou dos infectados apenas por uma estirpe. Isto significa que quando o hospedeiro é infectado por uma segunda estirpe tem uma probabilidade fixa de apresentar um determinado rácio. Neste modelo epidemiológico foi também possível verificar, que o mecanismo responsável por desviar a distribuição em torno do rácio 1:1 baseia-se no pressuposto que cada classe de cocolonizados ter taxas de recuperação diferentes, onde umas classes recuperam mais rapidamente que outras. Este rácio traduz como os diferentes patogénios, como um "todo", estão expostos ao sistema imunitário do hospedeiro. Todas as simulações numéricas foram realizadas usando a linguagem de programação Python e o software cientifico Mathematica. Construir modelos epidemiológicos que reflictam o fenómeno de cocolonização é fundamental para melhor compreender determinadas doenças, mas também apresenta muitos desafios técnicos. Nomeadamente, quanto mais factores biológicos forem tidos em conta na modelação, no sentido de os tornar mais realistas, mais parâmetros serão introduzidos e mais complexa será a sua análise. No entanto, seria interessante no futuro incorporar factores como: a identidade das estirpes, a heterogeneidade dos hospedeiros e as variações na sua resposta imunitária. Para além disso, poderíamos ter ainda em conta o fenómeno de co-transmissão, ou seja, a infecção do hospedeiro por mais de um parasita durante o mesmo evento de transmissão. Com isto poderíamos, potencialmente, contribuir para o estudo da evolução da virulência destes patogénios. No entanto, é fundamental que hajam mais resultados experimentais para se fazer uma comparação e validação dos resultados teóricos com vista à criação de modelos biológicos mais representativos da realidade.
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Dail, David (David Andrew). "Conditioning of unobserved period-specific abundances to improve estimation of dynamic populations." Thesis, 2012. http://hdl.handle.net/1957/28224.
Full textAbstract:
Obtaining accurate estimates of animal abundance is made difficult by the fact that most
animal species are detected imperfectly. Early attempts at building likelihood models that
account for unknown detection probability impose a simplifying assumption unrealistic for
many populations, however: no births, deaths, migration or emigration can occur in the
population throughout the study (i.e., population closure). In this dissertation, I develop
likelihood models that account for unknown detection and do not require assuming population closure. In fact, the proposed models yield a statistical test for population closure.
The basic idea utilizes a procedure in three steps: (1) condition the probability of the observed data on the (unobserved) period- specific abundances; (2) multiply this conditional
probability by the (prior) likelihood for the period abundances; and (3) remove (via summation) the period- specific abundances from the joint likelihood, leaving the marginal
likelihood of the observed data. The utility of this procedure is two-fold: step (1) allows
detection probability to be more accurately estimated, and step (2) allows population
dynamics such as entering migration rate and survival probability to be modeled. The
main difficulty of this procedure arises in the summation in step (3), although it is greatly
simplified by assuming abundances in one period depend only the most previous period (i.e., abundances have the Markov property). I apply this procedure to form abundance
and site occupancy rate estimators for both the setting where observed point counts are
available and the setting where only the presence or absence of an animal species is ob-
served. Although the two settings yield very different likelihood models and estimators,
the basic procedure forming these estimators is constant in both.Graduation date: 2012
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"Long-term weed dynamics and crop yields under organic and conventional cropping systems in the Canadian prairies." Thesis, 2016. http://hdl.handle.net/10388/ETD-2016-04-2510.
Full textAbstract:
Differences in cropping practices, including tillage, inputs and crop rotations are the driving factors affecting weed dynamics (weed abundance, composition and crop-weed competition), which can ultimately affect crop yields. Several experiments were carried out to assess the impact of long-term organic and conventional cropping systems on weed abundance, weed community composition, crop yield and yield loss using a long-term (18 year) alternative cropping systems study (ACS) at Scott, Saskatchewan, Canada. The ACS study consisted of three input systems, namely high (conventional tillage), reduced (no-till conventional) and organic input systems and three crop rotation diversities (low diversity, diversified annual grains and diversified annual-perennials).
A statistical analysis of the 18-year rotation revealed that the organic rotations have four and seven times higher weed density and 32% and 35% lower crop yields than the reduced and the high input systems respectively. Weed community composition was consistently different in organic rotations compared to the two conventional rotations throughout the years, but year to year random variations were more profound. All cropping systems showed an increase in weed density, weed biomass and crop yields over time, probably due to an increase in rainfall over time. Increasing the crop rotation diversity with annual and perennial crops did not reduce weeds, but decreased crop yields in all systems. A two-year micro-plot experiment with four additional weed competition treatments on the ACS study revealed that the wheat yields were lower in the organic rotations even in the absence of weeds, implying that lower crop yields were due to soil fertility related factors. A greenhouse pot experiment from soils obtained from both organic and reduced rotations revealed that wheat yields were still lower in organic compared to the reduced input systems, even after excess mineral N and P were added. Furthermore, no differences in crop yield loss due to weed competition among cropping systems were identified. Overall, this study revealed that eliminating tillage and reducing inputs are possible without long-term changes in weed abundance, weed community composition or affecting crop yields. However, eliminating synthetic inputs as was done in the form of organic crop rotations resulted in increased weed abundance, changed community composition and decreased crop yields.
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Yueh, Lan Chiu, and 藍秋月. "Spatial and temporal dynamics in abundance and productivity of intertidal seagrasses and the ecological niche in Kenting." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/09711153091447172790.
Full textAbstract:
碩士國立中興大學
生命科學系
91
Seasonal and spatial variation in the abundance and leaf productivity of tropical seagrass Thalassia hemprichii was studied in the Kenting National Park. T. hemprichii growing on intertidal reef flats was monitored quarterly from February 2001 to April 2003. Because the height of seagrass bed may influence the abundance and productivity, the habitats were divided into three types based on the exposure time: high bed, low bed, and pool. The aims of this study were to explore difference of T. hemprichii among different habitats, to monitor the seasonal changes, and to find out the most important environmental factor influencing T. hemprichii. Results show that there were significance seasonal and spatial variation in the abundance and leaf productivity of T. hemprichii. They appears to be dependent on the length of exposure time. Where exposure time was longer, shoot coverage, density, below ground biomass, the R/S ratio were greater, but leaf became shorter and growth rate was slower. Among the four seasons growth rate and above-ground biomass were the lowest in winter. Speraman correlations between biotic and environmental parameters indicate that the biotic variable of seagrass correlated negatively with wind speed, salinity, silt/clay content, sorting coefficient, water DIN and DIP, and correlated positively with water temperature, sediment depth, and water DIN and DIP. Canonical correlation analyses indicate that water temperature and water DIN were the most important environmental factors influencing growth rate and above-ground biomass, while secondarily sorting coefficient and grain size were the most important environment factors influencing coverage.
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Starheim, Colette Christiane Angela. "Regional scale tree-ring reconstructions of hydroclimate dynamics and Pacific salmon abundance in west central British Columbia." Thesis, 2011. http://hdl.handle.net/1828/3362.
Full textAbstract:
Long-duration records are necessary to understand and assess the long-term dynamics of natural systems. The purpose of this research was to use dendrochronologic modelling to construct proxy histories of hydroclimatic conditions and Pacific salmon abundance in west central British Columbia. A multi-species regional network of tree ring-width and ring-density measurements was established from new and archived tree-ring chronologies. These chronologies were then used in multivariate linear regression models to construct proxy records of nival river discharge, summer temperature, end-of-winter snow-water equivalent (SWE), the winter Pacific North America pattern (PNA) and Pacific salmon abundance.
All proxy hydroclimate records provide information back to 1660 AD. Reconstructions of July-August mean runoff for the Skeena and Atnarko rivers describe below average conditions during the early- to mid-1700s and parts of the early-, mid- and late-1900s. Models describe intervals of above average river discharge during the late-1600s, the early-1700s and 1800s, and parts of the early- and mid-1900s. Fluctuations in proxy reconstructions of July-August mean temperature for Wistaria and Tatlayoko Lake, May 1 SWE at Mount Cronin and Tatlayoko Lake and October-February PNA occurred in near synchrony with the shifts described in runoff records. Episodes of above average runoff were typically associated with periods of enhanced end-of-winter SWE, below average summer temperature and positive winter PNA.
A history of Pacific salmon abundance was reconstructed for four species of salmon (chinook, sockeye, chum and pink) that migrate to coastal watersheds of west central British Columbia. Proxy records vary in length and extend from 1400 AD, 1536 AD and 1638 AD to present. Salmon abundance reconstructions varied throughout the past six centuries and described significant collapse in population levels during the early-1400s, the late-1500s, the mid-1600s, the early-1700s, the early-1800s and parts of the 1900s.
Wavelet analyses of reconstructed hydroclimate and salmon population records revealed low- and high-frequency cycles in the data. Correlation analyses related reconstructions to atmospheric teleconnection indices describing variability in North Pacific sea surface temperatures and the Aleutian Low pressure centre. To a lesser degree, relationships were also established between reconstructions and the El Niño-Southern Oscillation. Results thus confirm the long-term influence of large-scale ocean and atmospheric circulation patterns on hydroclimate and Pacific salmon abundance in west central British Columbia.
The reconstructions introduced in this thesis provide insights about the long-term dynamics of the west central British Columbia environment. Several reconstructions presented in this thesis provide novel contributions to dendrohydroclimatic and paleoecologic research in Pacific North America. Proxy runoff records for the Skeena and Atnarko rivers are the first to be constructed for nival-regime basins in British Columbia. The models of Skeena River runoff and Mount Cronin SWE are additionally the first reconstructions of runoff and snowpack in Pacific North America based on a ring-density chronology, demonstrating the significant contribution that wood density measurements can make to dendrohydroclimate research. The models of Pacific salmon stocks are the first to utilize climate-sensitive tree-ring records to construct a history of regional salmon abundance and thus represent a significant advancement to paleoecological modelling.Graduate
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Chao, Chien-Fu, and 趙健復. "Dynamics of ciliate cysts and diel variation of ciliate abundance in the coastal region of northeastern Taiwan." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/91885573006076470786.
Full textAbstract:
博士國立臺灣海洋大學
環境生物與漁業科學學系
103
ABSTRACT This study investigated the seasonal dynamics of planktonic ciliates, including their cyst production, in a eutrophic coastal ecosystem in the subtropical western Pacific from March 2008 to July 2009. The abundance of planktonic ciliates ranged from 0.2 to 13 x 102 cells L-1 and cyst production ranged from 0 to 3 x 104 cysts m-2 d-1during the study period. The dominant cyst types in this study were Type I and Type II which are similar to Strombidium conicum and Strombidium capitatum, respectively. Cyst abundance changed with inter-day variations in salinity during the warm season ( > 24℃), leading us to conclude that environmental change in the form of freshwater input contributed greatly to the encystment of ciliate populations and might be the primary factor controlling encystment production. We designed three culture experiments to observe if ciliate is stimulated to form cyst in low salinity circumstance by added in different volume of distilled water. We observed that a large number of cysts appeared in low salinity. On the other hand, it seems that ciliate adapted the low salinity in the last culture stage and started to grow when salinity decline slowly. We observed in situ or culture experiments a significantly diel dynamics in ciliate, abundance and growth rate greater at night then daytime. The growth rate negative grow in daytime and reach a high level of 0.25 h-1(6 d-1) at night. The significance diel difference in the growth phase indicates the need to consider the diel dynamics when conducting growth rate measurements in ciliates.
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Hsieh, Yi-ru, and 謝佾儒. "Dynamic Phase-Acquisition Technique and Low-Abundance Biomolecule Detection of a Surface-Plasmon-Resonance System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24700149286352522873.
Full textAbstract:
碩士國立中央大學
光電科學研究所
99
In this thesis, a dynamic phase-detection technique was developed to improve the refractive-index resolution of a surface-plasmon-resonance system previously built in the research group. After examining the system stability, biological molecule measurements were performed. The phase-detection stability was 0.5859 degree in 2000-second period, and the corresponding refractive-index resolution was 1.3×10-5 RIU (Refraction Index Unit). This system was applied to antibody-antigen binding experiments of fetal fibronectin. With antigen concentrations of 50 ng/ml, 2.5 ng/ml, and 1.25 ng/ml, the phase changes were 3.0154, 1.0613 and 9.729 degrees, respectively. Considering a four-layer Kretschmann configuration, the equivalent thickness and the equivalent refractive index of the antibody-antigen binding layer were found by numerical fitting. For the concentration of 50 ng/ml, the equivalent refractive index was 1.33318 RIU and the equivalent thickness was 10.81 nm. For the concentration of 2.5 ng/ml, the equivalent refractive index was 1.33297 RIU and the equivalent thickness was 10.43 nm. For the concentration of 1.25 ng/ml, the equivalent refractive index was 1.33227 RIU and the equivalent thickness was 9.84 nm. As the phase signal, the equivalent refractive index and the equivalent thickness vary with the antigen concentrations, it is possible to obtain their relation curves through calibrations and then apply the system to determinations of the antigen concentration.