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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

The Associations of Little Blue Heron Prey and Vegetation Communities in Two Subtropical Coastal Ecosystems

Unknown Date (has links)
Shallow water availability coupled with anthropogenic degradation of seagrass beds limits wading bird food resources in dynamic coastal ecosystems. Identifying prey species critical to wading bird reproductive success and the environmental drivers of key prey species abundance is important for understanding how environmental stressors influence prey and change the quality of foraging patches. Little Blue Herons (Egretta caerulea) are reportedly generalists eating insects, crustaceans, and fish; however, the proportions of prey items in the diet may shift spatially and temporally from freshwater to marine systems during breeding and non-breeding periods. I investigated prey selection by Little Blue Herons in Florida at the Great White Heron National Wildlife Refuge and the western Florida Bay, during 2016 and 2017 breeding seasons by investigating prey availability at low-tide locations along mudflats compared to stomach regurgitate samples collected from Little Blue Heron chicks 1 to 4 weeks old. Little Blue Herons selected Gulf toadfish (Opsanus beta) and prawns (Farfantepenaeus spp.) from the estuarine environment, but also consumed terrestrial prey (e.g. tree crabs) suggesting Little Blue Heron foraging habitat is not restricted to tidal flats. Additionally, these results support the characterization of Little Blue Herons as a generalist. After identifying important prey species, I modeled the associations of selected prey species with submerged aquatic vegetation density and abiotic variables to better understand habitat preferences and important habitat characteristics that drive prey density. Models support total seagrass density and algal density as having the greatest effect on prey selected by Little Blue Herons. Prawn density has a strong positive association with seagrass density. Gulf toadfish (Opsanus beta) and prawns (Farfantepenaeus spp.) had strong positive association with algae while pipefish (Syngnathidae) had a strong negative association with algae suggesting algae density in seagrass meadows should be considered when assessing the quality of seagrass meadows for Little Blue Heron prey and habitat suitability. My results varied from previous studies where prawns and gulf toadfish were associated with specific seagrass species. Therefore, some Little Blue Heron prey species in south Florida may not be affected by changes in submerged aquatic vegetation community composition if submerged aquatic vegetation densities remain constant. Studies are needed that clarify the complex interactions between prey and specific habitat metrics to validate the strength of landscape scale drivers of wading bird prey densities in dynamic coastal ecosystems and to determine how these communities will respond to anthropogenic environmental change. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection
22

Početnost, reprodukce a pohnízdní disperze kvakoše nočního (\kur{Nycticorax nycticorax}) v Českobudějovické pánvi

HRALOVÁ, Nela January 2016 (has links)
The study deals with first telemetry observations of Black-Crowned Night Herons (Nycticorax nycticorax) in the Czech Republic. The main aim was to describe post-fledging dispersal abilities and evaluate influence of chosen factors to dispersion of young birds. The study also deals with population trends, variability of reproductive parameters and factors affecting these traits.
23

Aves aquáticas como indicadores de contaminação por metais em áreas úmidas no sul do Brasil

Barreto, Cindy Tavares January 2013 (has links)
Submitted by dayse paz (daysepaz@hotmail.com) on 2016-04-06T18:14:47Z No. of bitstreams: 1 Disserta_o_de_Mestrado_de_Cindy_Tavares_Barreto.pdf: 1526539 bytes, checksum: 1df2010b2061af8f93607669b374dccd (MD5) / Approved for entry into archive by cleuza maria medina dos santos (cleuzamai@yahoo.com.br) on 2016-04-18T20:17:10Z (GMT) No. of bitstreams: 1 Disserta_o_de_Mestrado_de_Cindy_Tavares_Barreto.pdf: 1526539 bytes, checksum: 1df2010b2061af8f93607669b374dccd (MD5) / Made available in DSpace on 2016-04-18T20:17:10Z (GMT). No. of bitstreams: 1 Disserta_o_de_Mestrado_de_Cindy_Tavares_Barreto.pdf: 1526539 bytes, checksum: 1df2010b2061af8f93607669b374dccd (MD5) Previous issue date: 2013 / Os Pelecaniformes são aves associadas aos ambientes aquáticos, estando em contato constante com contaminantes de origem antrópica. Neste contexto, o presente estudo quantificou concentrações de chumbo (Pb) e cádmio (Cd), metais não essenciais e tóxicos, relacionando-as com as características de dois habitats, técnicas de forrageamento e níveis tróficos da garçabranca-grande (Ardea alba) e do colhereiro (Platalea ajaja), no sul do Brasil. Amostras de sangue, penas e ovos (separados em casca e conteúdo) foram coletadas para as duas espécies em dois ninhais, um de ambiente exclusivamente límnico e outro predominantemente estuarino. A concentração de Pb no sangue foi diferente entre os locais de amostragem, sendo maior nas amostras coletadas no ambiente estuarino. Já a concentração na casca do ovo foi maior nas amostras do ambiente límnico. Quanto ao Cd, a concentração sanguínea foi maior na garça do que no colhereiro. Na pena e na casca do ovo, as concentrações foram maiores nas amostras coletadas no ambiente límnico. Os resultados mostraram uma correlação positiva entre as concentrações de Pb e Cd na casca e no conteúdo dos ovos, além de um alto índice de correlação entre as concentrações dos metais na casca do ovo. Embora as concentrações destes metais no sangue e penas das espécies estudadas sejam inferiores àquelas relatadas na literatura, as concentrações dos metais nos ovos foram até 605 vezes maiores que aquelas relatadas para espécies semelhantes amostras em outros ambientes aquáticos. Os ovos mostraram-se como bioindicadores mais sensíveis que os demais tecidos analisados, permitindo a constatação de contaminação por Pb e Cd nos ambientes úmidos na região sul do Brasil. Desta forma, foi verificado que as aves aquáticas analisadas no presente estudo podem ser consideradas como indicadoras/sentinelas quanto à contaminação ambiental por Pb e Cd. / Pelecaniformes are birds associated with wetlands, in close contact with contaminants of anthropogenic origin. The current study quantified lead (Pb) and cadmium (Cd) concentrations, both non-essential and toxic metals, in tissues of great egrets (Ardea alba) and roseate spoonbills (Platalea ajaja), comparing with foraging techniques, trophic levels and estuarine vs. limnetic habitats. Blood, feathers, egg content and eggshells were sampled in two colonies, the first one limnetic and the second one estuarine. Pb concentration in blood differed between places, higher in the estuarine colony, while concentrations in eggshell were higher in the limnetic colony. Cd concentrations in blood were higher in egrets than spoonbills. In feathers and eggshells, Cd concentrations were higher in samples from the limnetic site. Positive correlations between concentration of each metal in eggshell and egg content were found, as well as a high correlation among both metals in eggshell. Despite concentrations of both metals found in blood and feathers were below those reported in other studies, concentrations in eggs were up to 605 times higher than in other similar species studied elsewhere. In general, eggs seem to be more sensitive bioindicators of contamination by metals in comparison with other tissues analyzed, indicating Pb and Cd contamination in wetlands in southern Brazil. Therefore, waterbirds investigated in the current study could be regarded as suitable indicators/sentinels of environmental contamination by Pb and Cd.
24

Problemas de otimização na Geometria: uma abordagem para o Ensino Médio

Fonseca, Ricardo Santos 04 August 2016 (has links)
Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-01T19:31:46Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Ricardo Santos Fonseca.pdf: 3884170 bytes, checksum: c7f03d9fc12e685aabc06b6b6794a61b (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-01T19:32:02Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Ricardo Santos Fonseca.pdf: 3884170 bytes, checksum: c7f03d9fc12e685aabc06b6b6794a61b (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-01T19:32:17Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Ricardo Santos Fonseca.pdf: 3884170 bytes, checksum: c7f03d9fc12e685aabc06b6b6794a61b (MD5) / Made available in DSpace on 2017-02-01T19:32:17Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Ricardo Santos Fonseca.pdf: 3884170 bytes, checksum: c7f03d9fc12e685aabc06b6b6794a61b (MD5) Previous issue date: 2016-08-04 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work, lectures on Optimization Problems Applied Geometry. It presents initially a little history of some classic optimization problems in Euclidean Geometry Plana, as the Isoperimétrico Problem, the Heron Problem an the Steiner Problem. From there, he used that knowledge to build definitions, theorems and propositions regarding the Optimization of Geometry which provided grandiose tools for problem solving that can be applied in high school or in Mathematics Olympics. / Neste trabalho, disserta-se sobre Problemas de Otimização Aplicados à Geometria. Apresentase inicialmente um pouco da história de alguns problemas clássicos de otimização em Geometria Euclidiana Plana, como, o Problema Isoperimétrico, o Problema de Heron e o Problema de Steiner. A partir daí, usou-se esse conhecimento para construir definições, teoremas e proposições a respeito da Otimização em Geometria o que proporcionou grandiosas ferramentas para a resolução de problemas que podem ser aplicados no Ensino Médio ou em Olimpíadas de Matemática.
25

An Optimization Workflow for Energy Portfolio in Integrated Energy Systems

Jia Zhou (10716429) 29 April 2021 (has links)
<div>This dissertation develops an exclusive workflow driven by data analytics algorithms, to support the optimization of the economic performance of an Integrated Energy System (IES). The objective of this research is to determine the optimum mix of capacities from a set of different energy producers (e.g., nuclear, coal, gas, wind, and solar). The main contribution of this dissertation addresses several major challenges in current optimization methods of the energy portfolios in IES. First, the feasibility of generating the synthetic time series of the periodic peak data. </div><div>Second, the computational burden of conventional stochastic optimization of the energy portfolio, associated with the need for repeated executions of system models.</div><div>Third, the inadequacies of previous studies about the comparisons of the impact of the economic parameters.</div><div><br></div><div>Several algorithmic developments are proposed to tackle these challenges. A stochastic-based optimizer, which employs Gaussian Process modeling, is developed. The optimizer requires a large number of samples for its training, with each sample consisting of a time series describing the electricity demand or other operational and economic profiles for multiple types of energy producers. These samples are synthetically generated using a reduced order modeling algorithm that reads limited set of historical data, such as demand and weather data from past years. To construct the Reduced Order Models (ROMs), several data analysis methods are used, such as the Auto Regressive Moving Average (ARMA), the Fourier series decomposition, the peak detection algorithm, etc. The purpose of using these algorithms is to detrend the data and extract features that can be used to produce synthetic time histories that maintain the statistical characteristics of the original limited historical data. The optimization cost function is based on an economic model that assesses the effective cost of energy based on two figures of merit (FOM), the specific cash flow stream for each energy producer and the total Net Present Value (NPV). The Screening Curve Method (SCM) is employed to get the initial estimate of the optimal capacity. Results obtained from a model-based optimization of the Gaussian Process are evaluated using an exhaustive Monte Carlo search. </div><div><br></div><div>The workflow has been implemented inside the Idaho National Laboratory’s Risk Analysis and Virtual Environment (RAVEN) framework. The proposed workflow can provide a comprehensive, efficient, and scientifically dependable strategy to support the decision-making in the electricity market and to help energy distributors develop a better understanding of the performance of IES.</div><div><br></div>
26

Filling gaps in the full annual cycle of the Black-crowned Night-Heron <i>(Nycticorax nycticorax)</i>

Stein, Kristie Anne 11 December 2018 (has links)
No description available.
27

Caleidoscópio: percurso intelectual e a estréia de Heron de Alencar como crítico literário no jornal A Tarde (1947-1952)

Santana, Carla Patricia Bispo de January 2003 (has links)
Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-05-17T11:46:31Z No. of bitstreams: 3 Dissertação Carla de Santana3.pdf: 3667529 bytes, checksum: 9edaa397d3ff65bda03b6c32f5240449 (MD5) Dissertação Carla de Santana2.pdf: 5582666 bytes, checksum: 1fcacc36565fb65ac72ef646f4c0890a (MD5) Dissertação Carla de Santana1.pdf: 1983879 bytes, checksum: 6683b57489d1945fef4ca6c81e2ac1d9 (MD5) / Approved for entry into archive by Alda Lima da Silva(sivalda@ufba.br) on 2013-05-23T18:50:19Z (GMT) No. of bitstreams: 3 Dissertação Carla de Santana3.pdf: 3667529 bytes, checksum: 9edaa397d3ff65bda03b6c32f5240449 (MD5) Dissertação Carla de Santana2.pdf: 5582666 bytes, checksum: 1fcacc36565fb65ac72ef646f4c0890a (MD5) Dissertação Carla de Santana1.pdf: 1983879 bytes, checksum: 6683b57489d1945fef4ca6c81e2ac1d9 (MD5) / Made available in DSpace on 2013-05-23T18:50:19Z (GMT). No. of bitstreams: 3 Dissertação Carla de Santana3.pdf: 3667529 bytes, checksum: 9edaa397d3ff65bda03b6c32f5240449 (MD5) Dissertação Carla de Santana2.pdf: 5582666 bytes, checksum: 1fcacc36565fb65ac72ef646f4c0890a (MD5) Dissertação Carla de Santana1.pdf: 1983879 bytes, checksum: 6683b57489d1945fef4ca6c81e2ac1d9 (MD5) Previous issue date: 2003 / Esta dissertação ocupou-se, como objetivo principal, do resgate da atuação intelectual de Heron de Alencar (1921-1972), dando ênfase à sua vida na Bahia e à sua estréia como crítico literário. Portanto, centrou-se no seu trabalho no jornal A Tarde, no período que compreende os anos de 1947 a 1952, no qual foi redator da página Literária e manteve uma coluna de divulgação e crítica literária. Estabeleceu-se uma metodologia fundada na pesquisa de fontes primárias. Realizaram-se, entre outras atividades, transcrições e resumos de textos de sua autoria no referido jornal, entrevistas, e consulta a documentos (currículo, fotografias, manuscritos e outros) cedidos por familiares do crítico em questão. Como resultado reconstituiu-se parte significativa do seu percurso intelectual em diferentes lugares do País e do exterior, até o ano do seu falecimento evidenciando sua participação em projetos e iniciativas no campo da cultura. Também se mostrou, através do comentário e análise de seus textos, como operava a leitura de livros na sua coluna, situando o tipo de trabalho que realizava nas discussões sobre a crítica literária do período. Assim, foi possível fornecer um perfil crítico e ideológico desse intelectual que desempenhou um papel significativo na cena literária da Bahia de sua época. / Salvador
28

Θεωρητικό υπόβαθρο στο έργο «Πνευματικά» του Ήρωνα του Αλεξανδρινού

Αργυράκης, Βάιος 01 October 2012 (has links)
Τα Πνευματικά του Ήρωνα (1ος αιώνας μ.Χ.), προϊόν μακράς παράδοσης. Στην εισαγωγή του έργου εκτίθεται το θεωρητικό υπόβαθρο που υποστηρίζει τη λειτουργία των διατάξεων που παρουσιάζονται στη συνέχεια, αλλά και υποστηρίζεται πειραματικά από ορισμένες. Η δομή του έργου ακολουθεί τη δομή του ολοκληρωμένου μαθηματικού λόγου της κλασικής αρχαιότητας, προσαρμοσμένο κατάλληλα. Θέματα που αναδεικνύουμε είναι: Η ολοκλήρωση της αρχής των συγκοινωνούντων δοχείων με την αυστηρή απόδειξη του αντίστροφου της πρότασης του Αρχιμήδη για τη σφαιρικότητα της επιφάνειας του ηρεμούντος υγρού. Η πειραματική απόδειξη της υλικότητας του αέρα. Διαδικασία που εναρμονίζει το πείραμα με προϋπάρχουσα θεωρία. Η πειραματική απόδειξη της ελαστικότητας του αέρα, ο οποίος μέχρι και τον Αριστοτέλη θεωρείται ασυμπίεστος, καθώς και της ύπαρξης κενού σε μακροσκοπική κλίμακα. Θέση που υποστηρίζεται πειραματικά από τρείς διαφορετικές διατάξεις. Η εξέλιξη της θεωρίας της αναθυμίασης (δημιουργία των ανέμων), προσθέτοντας στη φωτιά την ιδιότητα (δυνατότητα) δημιουργίας κενού. Η πειραματική (με τη διάταξη Ι.23) επαλήθευση της θέσης (που ανάγεται στον 5ο π.Χ. αιώνα) ότι τα ρευστά εναλλάσσονται στον ίδιο χώρο κατά ίσους όγκους. Μέσα από τα θέματα αυτά και την ανάδειξη των διατάξεων που τα υποστηρίζουν, επισημαίνουμε την ενσυνείδητη αποκατάσταση ενότητας θεωρίας και πράξης, ενώ φέρνουμε στο φως μια όχι ιδιαίτερα προσεγμένη κατηγορία διατάξεων αυτή των πειραματικών. / Heron’s (1st century A.D.) Pneumatics is the product of a long tradition. In the introduction to the work the theoretical background which explains the functioning of the devices which are analysed later in the work is presented. At the same time it is endorsed experimentally by some of them. The structure of the work follows that of the integrated mathematical language of classical antiquity, but appropriately adapted to the task at hand. The subjects which are highlighted are the following: The completion of the proposition of communicating vessels with the rigorous proof of the inverse of Archimedes’ proposition for the sphericity of the surface of liquids in rest; the experimental demonstration of the corporeity of air, a procedure that harmonises the experiment with a pre-existing theory; the experimental demonstration of the elasticity of air, which, until Aristotle, had been considered to be incompressible, as well as the existence of the macroscopic vacuum, a position which is supported by three different experimental devices; the evolution of exhalation theory (wind creation) adding to fire the property of being able to create a vacuum; the experimental verification (by means of device I.23) of the position (dating from the 5th century BC) that liquids alternate in the same space in equal volumes. Through these issues and the examination of the devices that support them, we draw attention to the conscious unification of theory and practice, while we also bring to light a rather neglected area, that of experimental devices.
29

Comportamento social e territorialidade alimentar na gar?a-azul, Egretta caerulea (L) = Feeding territoriality in the little blue heron, Egretta caerulea (L)

Silva, Emmanuel Moralez da 28 March 2008 (has links)
Made available in DSpace on 2014-12-17T15:36:51Z (GMT). No. of bitstreams: 1 EmmanuelMS.pdf: 693776 bytes, checksum: 5c59a44ad86ae5501127668e2496f494 (MD5) Previous issue date: 2008-03-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The use of habitat is an important part of a species biology. One resource of great importance for the survivor and reproduction of an individual is the food resource. Thus, the social interactions an animal has during the feeding activities are of extremely importance within its behavioral aspects, which represents the part of an organism trough which it interacts with the environment, adapting to changes and variations. Herons are known to form feeding aggregations of even more than thousands of individuals, in which social components of foraging have been identified and studied for several species. More profound studies of these aspects are yet to poor for the Little Blue Heron, Egretta caerulea. Therefore, the aim of this study was to describe the social behavior (display postures, vocalizations and co-specific interactions) and the territoriality of the specie during the feeding period in an area of mud bank in the estuarine system of Canan?ia, south coast of S?o Paulo state, Brazil. The defense of a fixed and exclusive area, closest to the mangrove, trough expulsion was observed; some thing that have not yet been registered with concrete data for the specie. Higher capture and success rates, and lower investment rates (steps/min and stabs/min) were registered for individuals foraging in areas corresponding to the defended territory. This could be one of possible reasons for the establishment of territories in the area. Four display postures were registered for the specie, two of then new in the literature, which are used in the interactions between individuals; one vocalization, that apparently is important in the social context of foraging for the specie and, possibly, has a function of advertising and proclaiming the dominance position of the territorial individual within the group. A territorial individual uses three behaviors, of the ones described: expulsion, vocalization and encounter (agonistic encounter between individuals, without physical aggression). Of these, the expulsion is apparently used in the actual defense, actively; while the other two behaviors are used in a more passive way, in the maintenance of the dominance position of the individual, helping it in the defense of its territory in a less direct manner. Therefore, with the results presented in here, new components of the social utilization of the feeding resource for the Little Blue Heron were identified, incorporating aspects of the territorial behavior for a future understanding of its possible adaptive significance. And it also reinforces the importance of the social interactions of herons foraging in great aggregations, in areas ecologically important / A utiliza??o do habitat ? parte importante da biologia de uma esp?cie. Um dos recursos importantes para a sobreviv?ncia e reprodu??o de um indiv?duo ? o recurso alimentar. Desta forma, as intera??es sociais que um animal mant?m durante as atividades de forrageio s?o de suma import?ncia dentre seus aspectos comportamentais, os quais, por sua vez, representam a parte de um organismo atrav?s da qual este interage com o ambiente, adaptando-se as varia??es e mudan?as no meio. Gar?as s?o conhecidas por formar agrega??es alimentares que podem conter at? milhares de indiv?duos, nas quais componentes sociais do forrageio t?m sido identificados e estudados para v?rias esp?cies. Estudos mais aprofundados destes aspectos ainda s?o escassos para a gar?a-azul, Egretta caerulea. Desta forma, o objetivo deste estudo foi descrever o comportamento social (posturas de exibi??o, vocaliza??es e intera??es co-espec?ficas) e a territorialidade da esp?cie durante o per?odo de forrageio em uma ?rea de baixio lodoso no sistema estuarino de Canan?ia, litoral sul do estado de S?o Paulo, Brasil. Observou-se a defesa de uma ?rea fixa e exclusiva, pr?xima ao manguezal, atrav?s da expuls?o; algo que ainda n?o tinha sido registrado com dados concretos para a esp?cie. Registraram-se taxas de captura e sucesso maiores para indiv?duos forrageando na ?rea correspondente ao territ?rio defendido, assim como menores taxas de investimento no forrageio. Desta forma, esta pode ser uma das raz?es pelo estabelecimento de territ?rios pela esp?cie no local. Registraram-se quatro posturas de exibi??o para a esp?cie, das quais duas s?o novas na literatura e s?o utilizadas nas intera??es entre indiv?duos. Registrou-se uma vocaliza??o, que aparentemente ? importante no contexto social do forrageio para a esp?cie e, possivelmente, tem fun??o de advert?ncia e proclama??o da posi??o de domin?ncia ocupada pelo indiv?duo territorial dentro do grupo. Um indiv?duo territorial utiliza-se de tr?s comportamentos, dos descritos: expuls?o, vocaliza??o e encontro (encontro agon?stico entre indiv?duos, sem agress?o f?sica). Destes, aparentemente a expuls?o ? utilizada na defesa ativa; enquanto que os outros dois comportamentos s?o utilizados de uma forma mais passiva, na manuten??o da posi??o de domin?ncia do indiv?duo, ajudando-o na defesa de seu territ?rio de uma forma menos direta. Assim, com os resultados apresentados neste trabalho, identificaram-se novos componentes do comportamento social da utiliza??o do recurso alimentar pela gar?a-azul, incorporando-se aspectos do comportamento territorial para um futuro entendimento de sua poss?vel signific?ncia adaptativa. Refor?a-se tamb?m a import?ncia das intera??es sociais de gar?as que forrageiam em agregados contendo milhares de indiv?duos, em ?reas ecologicamente importantes
30

The respiratory and gut physiology of fish : responses to environmental change

Rogers, Nicholas John January 2015 (has links)
Many of the habitats occupied by fish are highly dynamic, naturally demonstrating substantial abiotic fluctuations over diurnal, tidal or seasonal cycles. It is also the case that throughout their 545 million year evolutionary history, fish have existed in aquatic environments very different to those of the present day. However, the past several decades have seen unprecedented rates of environmental change, at local and global scales, arising from human activities. The two major themes of the present thesis are: 1) Respiratory responses of fish to changes in environmental oxygen and temperature in the context of exploring intra- and inter-specific trait variation and its ecological implications 2) The effects of environmental factors (oxygen, carbon dioxide, temperature and seawater chemistry) on the intestinal precipitation and excretion of calcium carbonate by marine teleosts. In the first study (chapter two) a comprehensive database of fish critical PO2 (Pcrit) data compiled from the published literature is presented. The systematic review of this literature provided the opportunity to critically examine methodologies for determining Pcrit as well as its usefulness as an indicator of hypoxia tolerance in fish. The second study (chapter three) examines whether inter- and intra-specific variation in thermal and hypoxia tolerance in two reef snapper species (Lutjanus carponotatus and Lutjanus adetii) reflects their distributions across the contrasting biophysical environments of the reef flat and reef slope surrounding Heron Island on the Great Barrier Reef. L. carponotatus was clearly the most thermally and hypoxia tolerant of the two species, demonstrating a ~3.5 °C wider thermal tolerance zone (higher CTmax, lower CTmin) and ~26% lower Pcrit than L. adetii. These results suggest that the contrasting distribution of these species between flat and slope reef zones is reflected in their physiological tolerances. However, there was no evidence of intra-species variation in tolerance between flat and slope caught L. carponotatus individuals, indicating that this species does not form physiologically distinct subpopulations between these reef zones. The third study (chapter four) experimentally quantified the effect of hypercarbia (3000 μatm) and hypoxia (50% air saturation) on gut carbonate production by the European flounder (Platichthys flesus). Both hypercarbia and hypoxia resulted in a significant increase in carbonate excretion rate (1.5-fold and 2.4-fold, respectively) and acted synergistically when combined. In the final study (chapter five), gut carbonate production was measured in the European flounder undergoing conditions simulating the ‘calcite seas’ of the Cretaceous. The results of this study support the hypothesis that ocean conditions prevalent during the Cretaceous period resulted in piscine carbonate production rates substantially higher (~14-fold) than the present day. Ultimately, this thesis directly links the environmental physiology of fish at the individual level to wider scale implications (past, present and future), ranging from local ecological patterns all the way up to global carbon cycles.

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