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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

New England’s Underutilized Seafood Species: Defining And Exploring Marketplace Potential In A Changing Climate

Davis, Amanda 18 December 2020 (has links)
New England’s seafood industry has been searching for opportunities to diversify their landings and build resilience as it faces socio-economic challenges from a changing climate. Developing markets for underutilized species is one way the New England community could help their seafood industry build resilience. This thesis identified New England’s underutilized fish species and explored their marketplace potential by examining their availability in a changing climate, current availability to consumers, and consumers’ responses. In Chapter I, I account how New England’s seafood preferences have changed over time. In Chapter II, I identify New England’s seven underutilized seafood species: 1) Acadian redfish (Sebastes fasciatus), 2) Atlantic pollock (Pollachius virens), 3) butterfish (Peprilus triacanthus), 4) the Georges Bank and Georges Bank East stocks of haddock (Melanogrammus aeglefinus), 5) scup (Stenotomus chrysops 6) the northern stock of silver hake (Mercluccius bilinearis), and 7) white hake (Urophycis tenuis). In the same chapter, I show that climate change will likely affect the availability of these species differently and that the broader ecological and socio-economic responses from shifting distributions and phenology are largely unknown. In Chapter III, I demonstrate that besides haddock, underutilized species were rarely accessible to consumers in restaurants. In the same chapter, I show how resources would likely help consumers and restaurants connect with their underutilized species since popular seafood suggestion guides either overlook or provide inconsistent recommendations for all underutilized species. In Chapter IV, I suggest that younger generations (Millennials and Generation Z) are interested in engaging with underutilized species. These younger consumers responded positively to hake, haddock, and Atlantic pollock in sensory assessments. Finally, in Chapter V, I suggest how New England’s seafood supply chain can use results from this research to make more informed policy, marketing, and purchasing decisions that align with their sustainability goals. These insights into availability, access, and consumer response may help New England’s seafood industry strategize approaches that will connect younger consumers to their local seafood options and build new adaptive markets in a changing climate.
22

The Effects of Species Biology, Riverine Architecture and Flow Regime upon Patterns of Genetic Diversity and Gene Flow in Three Species of Northern Australian Freshwater Fish

Huey, Joel Anthony, na January 2008 (has links)
Understanding patterns of dispersal, the movement of individuals or propagules, among populations of riverine species is imperative to their management and conservation. However, directly estimating dispersal can often be difficult. Therefore, estimates of gene flow, the movement of genes, are often used to infer dispersal among natural populations. In riverine species, gene flow is determined by species biology, riverine architecture and flow regime. While many studies investigate the role of species dispersive strategies by comparing patterns of genetic structure in different species across the same geographic range, few also attempt to investigate the role of the non-biotic influences on gene flow in a comparative manner. Instead, studies regarding landscape processes (river architecture and hydrology) are based upon observations in a single riverine environment and not compared to other catchments that may differ in riverine architecture or hydrology. This study attempts to investigate all three factors influencing gene flow and genetic diversity using a comparative approach. This is done by contrasting two species of freshwater fish in two riverine systems that differ in their hydrological and structural makeup. By comparing patterns of genetic structure for each fish species, the role of species biology (behavioural and physical adaptations) can be explored. Then, by comparing patterns of genetic structure for each species, between riverine systems that differ in their landscape processes, the role of hydrology and riverine architecture in determining genetic structure can be explored. This study employed three different genetic markers to elucidate patterns of genetic structure and genetic diversity. These were, direct sequencing and screening of the control region of the mitochondrial DNA genome, microsatellite loci and allozymes...
23

Diversidade Ictiofaun?stica e Ecologia reprodutiva de uma esp?cie nativa de peixe da Bacia Piranhas-Assu, RN

Nascimento, Wallace Silva do 18 June 2010 (has links)
Made available in DSpace on 2014-12-17T14:02:01Z (GMT). No. of bitstreams: 1 WallaceSN_DISSERT.pdf: 4760466 bytes, checksum: 02e9f4b160af4472ebf0590033624755 (MD5) Previous issue date: 2010-06-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The Caatinga biome is rich in endemic fish species fauna. The present study the results of fish faunal surveys conducted in the hydrographic basin of Piranhas-Assu of the Brazilian Caatinga biome. The fish samples collected were distributed in four orders (Characiformes, Perciformes, Siluriformes and Synbranchiformes), 11 families (Characidae, Curimatidae, Auchenipteridae, Anostomidae, Prochilodontidae, Erythrinidae, Cichlidae, Sciaenidae, Heptapteridae, Loricariidae, Synbranchidae) and 22 species, of which 17 are endemic and five have been introduced from other basins. The order Characiformes was the most representative in number of species (46,35% ) followed by Perciformes (35,38%), Siluriformes (17,44%) and Synbranchiformes (0,5%). The Nile tilapia, Oreochomis niloticus, the only exotic species, was most expressive in number of individuals (24.92%) followed by the native species piau preto, Leporinus piau (18,77 %). Considering the relative frequency of occurrence of the 22 species, 13 were constant, five were accessory and four were occasional. This study investigated the reproductive ecology of an endemic fish black piau, Leporinus piau from the Marechal Dutra reservoir, Acari, Rio Grande do Norte. Samplings were done on a monthly basis from January to December 2009, and a total of 211 specimens were captured. The environmental parameters such as rainfall, temperature, pH, electrical conductivity and dissolved oxygen of water were recorded. The sampled population showed a slight predominance of males (55%), however females were larger and heavier. Both sexes of L. piau showed positive allometric growth, indicating a higher increase of weight than length. The first sexual maturation of males occurred at smaller size, with 16.5 cm in total length than females (20.5 cm). During the reproductive period, the condition factor and gonadosomatic index (GSI) of L. piau were negatively correlated. This species has large oocytes with a high mean fecundity of 54.966 with synchronous oocyte development and total spawning / O bioma Caatinga ? rico em v?rias esp?cies end?micas da ictiofauna. O presente trabalho teve como objetivo verificar a diversidade da ictiofauna da bacia do Rio Piranhas-Assu, RN inserida no bioma Caatinga, alem de verificar os aspectos reprodutivos de uma esp?cie de peixe nativa, piau preto, Leporinus piau (Osteichthyes: Anostomidae). Foram realizadas amostragens mensais entre setembro de 2008 a dezembro de 2009. Foram capturados 602 peixes, distribu?dos em quatro ordens (Characiformes, Perciformes, Siluriformes e Synbranchiformes), 11 fam?lias (Characidae, Curimatidae, Auchenipteridae, Anostomidae, Prochilodontidae, Erythrinidae, Cichlidae, Sciaenidae, Heptapteridae, Loricariidae, Synbranchidae), e 22 esp?cies, sendo 17 end?micas, quatro introduzidas de outras bacias e uma ex?tica. A ordem Characiformes foi mais representativa em n?mero de esp?cies (46,35%) seguidas por Perciformes (35,38%), Siluriformes (17,44%) e Synbranchiformes (0,5%). A til?pia do Nilo, Oreochomis niloticus, a ?nica esp?cie ex?tica registrada foi mais expressiva em n?mero de indiv?duos (24,92%) seguida pela esp?cie nativa o piau-preto, Leporinus piau (18,77 %). Quando considerado a freq??ncia relativa de ocorr?ncia das 22 esp?cies, 13 foram constantes, cinco acess?rias e quatro raras. Medidas de gest?o ambiental devem ser tomadas para conserva??o das esp?cies end?micas da bacia do Rio Piranhas-Assu do bioma Caatinga. Para investigar os aspectos reprodutivos de peixe nativo piau preto, L. piau, foi capturado um total de 211 exemplares. Os par?metros ambientais, como pluviosidade, temperatura, pH, condutividade el?trica e oxig?nio dissolvido da ?gua foram registradas. A popula??o amostrada mostrou uma leve predomin?ncia de machos (55%) e as f?meas foram maiores em comprimento e mais pesadas. Ambos os sexos de L. piau apresentaram um crescimento alom?trico positivo, indicando um maior incremento de peso do que comprimento. A primeira matura??o sexual dos machos ocorreu mais em tamanho menor, com 16,5cm de comprimento total, do que as f?meas (20,5cm). Durante o per?odo reprodutivo, o fator de condi??o e ?ndice gonadossom?tico (IGS) de L. piau foram correlacionadas negativamente. A esp?cie apresenta ov?citos grandes com uma alta fecundidade (54,966 em m?dia), com desenvolvimento ovocit?rio sincr?nico e desova total
24

Cardiotoxic effects of polycyclic aromatic hydrocarbons and abiotic stressors in early life stage estuarine teleosts

Elizabeth B Allmon (10724124) 29 April 2021 (has links)
<div>Following the 2010 Deepwater Horizon oil spill, extensive research has been conducted on the toxicity of oil and polycyclic aromatic hydrocarbons (PAHs) in the aquatic environment. The location and timing of the Deepwater Horizon surface slick coincided with the spawning seasons of many important pelagic and estuarine fish species. As such, there has been particular emphasis placed on the effects of PAHs on sensitive life history stages in fish, such as the embryonic and larval periods. Additionally, the spill occurred throughout the spring and summer months which, in estuaries, are marked by regular fluctuations in abiotic environmental factors such as dissolved oxygen, salinity, and temperature. Until recently, there has been little work done to elucidate the combined effects that PAHs from oil spills and adverse environmental conditions (hypoxia, increased salinity, and elevated temperatures).</div><div>Work presented in this dissertation uses next generation sequencing technology (RNA Seq) to determine differential gene expression in larval estuarine teleosts following exposure to adverse environmental conditions and PAHs. Downstream canonical pathway and toxicological function analysis were then applied to the identified differentially expressed genes (DEGs) to predict cardiotoxic responses at the organismal level. To verify the predicted responses, a phenotypic anchoring study was conducted and identified a cardiotoxic phenotype (pericardial edema) and reduced cardiac output in embryos exposed to oil. Finally, the mechano-genetic interplay governing the morphological development of the teleost heart was investigated and correlations between developmental gene expression and blood flow forces within the cardiovascular system were identified.</div>

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