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Maternal effects and phenotypic mismatch in hatchery-reared Atlantic salmonStringwell, Rebecca January 2015 (has links)
Phenotypic variation was previously thought to be the result of complex interactions between an individual's genotype and the environment in which it exists. It is, however, now evident that an individual's phenotype may also be shaped by the environmental variation experienced by the mother, i.e. maternal effects. Environmental maternal effects have the potential to generate rapid phenotypic change in a population and so may be particularly important for evolution at ecological time-scales. The general aim of this thesis was to examine how maternal effects may influence offspring fitness and life history traits in Atlantic salmon (Salmo salar L.1758). For this species, the early juvenile period is the most critical due to their complex life cycle. Offspring rely on maternal provisioning during the early stages of development for growth and survival. Several studies on Atlantic salmon have emphasised the benefits of developing from larger eggs, yet it is unclear how the effects of rearing environment influence early life development. The thesis therefore investigated the effects of variation in maternal provisioning and female rearing environment on the development and physiology of embryos, the behaviour of newly emerged fry and the survival of fry released into the wild. Also assessed were the phenotypic changes among juvenile salmon released into the wild compared to those retained in the hatchery. For this maternal provisioning was manipulated by varying the length of time mothers from the same genetic background were maintained in captivity (2 months, 14 months and 26 months). The results of this thesis demonstrate that both maternal provisioning and female rearing environment alter the development and behaviour of salmon fry, opercular beat rate (a proxy for metabolic rate) and yolk sac absorption, and ultimately survival in the wild. Hatchery-reared fry were found to be maladapted to the natural environment for a number of phenotypic traits which are known to impact survival and the longer fry are retained in the hatchery prior to release the more phenotypically mismatched to the natural environment they become. However, increased egg size brought about my retaining females in captivity improved survival.
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The role of osmoregulation and nutrition as determinants of buoyancy and short-term mortality of marine fish larvae /Sclafani, Matthew. January 2000 (has links)
No description available.
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Some aspects of the occurrence and biology of Trichodesmium (Cyanophyta) in the western tropical Atlantic near Barbados, West IndiesBorstad, Gary A. January 1978 (has links)
No description available.
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Molecular studies on Sphaerospora truttae and other freshwater myxozoansHolzer, Astrid Sibylle January 2001 (has links)
This study investigates the life cycle of Sphaerospora truttae, a myxozoan parasite of the Atlantic salmon, using molecular methods based on the 185 rONA. DNA sequencing showed that the 185 rONA of S. truttae differs substantially from the sequence obtained from its proposed alternate actinosporean life cycle stage, Echinactinomyxon type 5. With more than 90% sequence identity Echinactinomyxon type 5 is closely related to Myxobolus portucalensis whereas S. truttae with an extraordinary long 185 sequence (2541 bp), with inserts in the variable regions of the gene, does not relate closely to any myxozoans. On the basis of the obtained sequence for S. truttae, a single round nested peR assay was developed which allows low-level detection and specific identification of S. truttae in all life cycle stages. Furthermore, two of the primers from the peR assay were successfully used on tissue sections in an optimised in situ hybridisation (ISH) protocol. ISH experimentally identified the gills as the predominant entry locus of S. trottse into the fish host and it detected the spatiotemporal migration of the parasite via the vascular system into the target organ, the kidney. The ISH protocol and the peR assay were also used to screen oligochaetes and other co-occurring invertebrates for S. truttae infection but an alternate host for S. truttse could not be identified. However, 12 actinosporean stages were found and they were characterized on the basis of their 185 rONA, together with 9 further myxosporean species from wild fish in the same riverine habitat. Three actinosporeans were found to be genetically identical with three myxosporeans (Myxidium truttae, Chloromyxum truttse and Chloromyxum sp.) and thus represent alternate life cycle stages of these species. Phlyogenetic analysis of the myxozoans identified a very basal position of S. truttae and S. elegans, as a sister group to the marine species. All other species were nested in the freshwater clades and clustered according to host tissue localization, but independent from host species or myxozoan spore taxonomy.
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The behaviour of carbonyl sulphide in the ocean : field and modelling studiesHobe, Marc von January 2000 (has links)
No description available.
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Energetics and maturation : tracking physiological changes through the maturation cycle of Atlantic herring (Clupea harengus L.)McPherson, Lindsay Rhona January 2010 (has links)
This thesis focuses on the link between condition, defined as the magnitude of fat reserves, and maturation in two sub-populations of Atlantic herring (Clupea harengus L.). Histological, fatty acid (FA), univariate and multivariate analyses were used in a multi-scale approach to elucidate the relationship between body fat and maturity. Furthermore, the accuracy of commonly used proxies of condition and maturity was tested. No evidence was found to support the hypothesis that a threshold of fat must be exceeded for first maturation to occur; however, a size threshold was observed. During maturation, herring may be capable of both selectively incorporating certain FA into the ovary and also of synthesising FA within the ovary itself. Mesenteric fat was highly dynamic during maturation and likely plays a role in gonad development. Commonly used morphometric condition indices were not related to mesenteric fat and the relationship between morphometric indices and other more direct indices was dependent on maturity stage. Macroscopic maturity staging was unreliable and errors led to an under-estimation of the herring spawning stock biomass of up to 26%. A gonadosomatic index was validated which was able to discern between immature, mature and recovering fish more accurately than macroscopic staging. Few differences were found between North Sea autumn-spawning (NSAS) and Norwegian spring-spawning (NSS) herring in this study. The FA profiles of both sub-populations were similar over the maturity cycle and the effects of length and maturity stage on mesenteric fat were analogous for both populations. A photoperiod cue of first maturation was found for Atlantic herring. However, this cue differed between the subpopulations, with NSAS herring maturation being triggered by the spring equinox and NSS herring maturation being triggered later. A multi-scale approach was successfully employed to demonstrate that there is an intrinsic link between fat reserves and maturity in herring.
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The Relationship Between Sense of Belonging and Instructor Self-Efficacy Among Online Adjunct Faculty in Higher EducationUnknown Date (has links)
Given the increased reliance on adjunct faculty and the increased demand for
online courses, the online adjunct faculty member is an important figure to know and
understand. Unfortunately, there is a dearth of research on this population, particularly in
terms of how their feelings of connection to their colleagues, administration, and their
institution affects their beliefs about their online teaching abilities. This non-experimental
correlational study investigated the relationship between sense of belonging and
instructor self-efficacy among online adjunct faculty in higher education. Additionally,
this study sought to determine if there is a predictive element between these two
variables.
This study utilized the Organizational Sense of Belonging (OSB) subscale and the
Sense of Efficacy for Online Teaching Scale (SEOTS) as well as demographic questions
in order to collect data on the study variables. Questionnaires were distributed to online
adjunct faculty members from six higher education institutions within the states of Florida, Virginia, and Nevada. A total of 122 online adjunct faculty members completed
the questionnaire. Data were analyzed using descriptive analyses, ANOVA, Pearson’s
Correlation Coefficient, and regression analysis.
Results indicated that sense of belonging and instructor self-efficacy share a
significant linear relationship. Additionally, a stronger sense of belonging and a higher
instructional self-efficacy were found among participants who participate in universitysponsored
faculty development opportunities, who participate in non-academic university
events, and who communicate with other online adjunct faculty members through social
media. Furthermore, sense of belonging was found to be a significant predictor of selfefficacy,
both when controlling for significant variables and when not controlling for
variables. Further research is needed to determine causality between sense of belonging
and instructor self-efficacy. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
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On Mutual Fund Family Diversification, Performance, Persistence and FlowsUnknown Date (has links)
The first essay introduces a portfolio theory motivated approach to measuring
mutual fund family-level diversification and hedging strategies. Diversification of
idiosyncratic risk (systematic risk) is measured by the average cross-fund correlation in
idiosyncratic returns (predicted returns from the multifactor model). Using new
methodology, I find evidence of cross-sectional variation in family-level diversification
and examine several fund families’ characteristics as the determinants of this crosssectional
variation. On average, fund families that offer more objectives are more
diversified in terms of both idiosyncratic and systematic risks; however, in the subsample
of larger fund families, greater number of objectives is associated with increase
(decrease) in idiosyncratic (systematic) risk diversification. Families that concentrate in
the retail sector are more diversified. I also find that less diversification of idiosyncratic
risk on the family level is associated with better risk-adjusted performance, while greater diversification of systematic risk is associated with greater performance during an
economic downturn.
The second essay examines whether new measures of diversification are
additional determinants of fund family flows and flow volatility. I find that fund family
capital flows increase in systematic risk focus, as more of the fund family’s assets are
held by institutional investors. Family flow volatility decreases in diversification of
systematic risk during market downturn, increase in market uncertainty and during
recession. I further find that families with greater concentration in the retail sector
(institutional sector) exhibit less family capital flow volatility as the diversification of
systematic risk (idiosyncratic risk) increases. Fund-level volatility of focused and
concentrated funds within diversified families is greater than in less diversified families,
signaling that diversification on the family level may decrease participation costs for the
investors. Moreover, in support of participation cost hypothesis, I find that the
performance of worst performing funds within fund families increases in the family-level
diversification; thus, family-level diversification affects the convexity in the fund flowperformance
relation documented in the previous studies. On the family-level,
diversification is associated with convexity in flow-performance relation, while family
focus with more direct flow-performance relation. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
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Self-Organization of Object-Level Visual Representations via Enforcement of Structured Sparsity in Deep Neural NetworksUnknown Date (has links)
A hypothesis for the self-organization of receptive fields throughout the hierarchy
of biological vision is empirically tested using simulations of deep artificial neural
networks. Results from many fields for topographic organization of receptive fields
throughout the visual hierarchy remain disconnected. Although extensive simulation
research has been done to model topographic organization in early visual areas, little
to no research has investigated such organization in higher visual areas. We propose
that parsimonious structured sparsity principles, that permit the learning of topographic
receptive fields in simulated visual areas, are sufficient for the emergence of
a semantic topology in object-level representations of a deep neural network. These
findings suggest wide-reaching implications for the functional organization of the biological
visual system and we conjecture that such observed results in nature could
serve as the foundation for unsupervised learning of taxonomic and semantic relations
between entities in the world. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
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Optimal Energy Scheduling of a Hybrid Microgrid Considering Environmental AspectsUnknown Date (has links)
Lower costs of clean energy generation, the need for a more secure grid, and
environmental concerns are leading to create more opportunities for integration of
renewable energy resources utilization in the power systems. The recent concept of
Microgrid (MG), as a part of the development of smart grid, is required in order to
integrate the renewable sources in the utility grid. An MG is described as a small-scale
distribution grid that consists of diversified Distributed Energy Resources (DERs),
Battery Energy Storage Systems (BESSs), and local flexible loads that typically can
either be operated in islanded or grid-connected modes. The optimal utilization control of
such an MG system is a challenging task due to the complexity of coordination among
the DERs, BESSs and load management possibilities. Therefore, in this dissertation,
optimal component sizing and operation of MGs under different operational strategies is
proposed. MGs typically consist of Photovoltaic (PV) systems, wind turbines as well as
microgas turbines, fuel cells, batteries and other dispatchable generating units. Firstly, a methodology to perform the optimal component sizing for DERs in
islanded/grid-tied modes is developed. The proposed optimal algorithm aims to
determine the appropriate configuration among a set of components by taking into
consideration the system’s constraints. An Iterative optimization technique is proposed in
order to minimize the annual cost of energy and cost of emissions including CO2, SO2,
and NOx. A case study from South Florida area, given the local weather data and load
demand is investigated for the modeling verification. Using the results from optimal
component sizes, a day-ahead optimization problem for the operation of an MG under
different scenarios is introduced. Also, the objective function is formulated as a
constrained non-linear problem. The uncertainties of stochastic variables (solar radiation,
wind speed, and load) are modeled and renewable generations and load demand are
forecasted. An advanced dynamic programing procedure is proposed to assess various
operational policies. The simulation results show the efficiency of the proposed method. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
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