Author: Gwangseok Yoon
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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The environment during early life history strongly impacts phenotypic development in all organisms, which further influences developmental trajectory and ecological fitness later in life. Depending on the developmental stage and magnitude of change in the environment, phenotypes may become irreversible and thus have a long-lasting effect later in life. This thesis was designed to better understand how changes in the environment may influence plasticity and variation of metabolic phenotypes of Lake Sturgeon (Acipenser fulvescens) within the first year of life. Broadly speaking, the thesis tested two hypotheses that 1) all measured phenotypes would be plastic; and 2) durations of environmental effects on phenotypic development would be correlated with distinct developmental windows. Studies were developed to examine 1) short-term effects of temperature or diet on metabolic phenotypes such as metabolic rate, energy density, fatty acid profiles, and growth (Chapters 2 and 3) and 2) longer-term effects of temperature or diet during early life on these metabolic phenotypes (Chapters 4, 5 and 6). The first experimental chapter (Chapter 2) examined ontogenetic development of metabolic rate and demonstrated that dietary shifts between Artemia to bloodworm resulted in cessation of growth with elevated routine metabolic rate. Chapter 3 examined how fatty acid profiles and plasma cortisol concentration were influenced by environmental temperature and showed that decreasing temperature led to increases in mono- and polyunsaturated fatty acids in both phospholipids and triglycerides, and food deprivation resulted in lack of difference between baseline and peak cortisol concentrations. Chapter 4 examined how temperature during early life influenced plasticity of growth and showed that temperature post-dietary transition resulted in a transient effect on growth and energy metabolism without long-term effects post-winter. Chapter 5 examined how temperature during early life could influence growth and fatty acid metabolism when fish were exposed to colder temperatures later in life and demonstrated that elevated temperatures resulted in a longer-term effect on growth but lack of transcriptional responses of desaturating fatty acids when exposed to a cold temperature (3.5°C) later in life. The final experimental chapter, Chapter 6 examined longer-term effects of diet at the onset of exogenous feeding on metabolism and growth and demonstrated that an enriched diet resulted in prolonged effects on growth, digestive enzyme activity and survival prior to a simulated overwintering. This doctoral thesis research revealed that all measured metabolic phenotypes were plastic, but subtle changes in temperature and diet during early life history resulted in transient or prolonged effects on growth and metabolism in age-0 lake sturgeon. Results will aid our understanding of cohort and population dynamics as well as contribute to the development of conservation strategies for lake sturgeon, a species at risk or endangered across its natural range.
Author: Gwangseok Yoon
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Environment-phenotype interactions are significant particularly during early life history as they often dictate physiological performance, growth and ultimately ecological fitness of individuals. Temperature, dissolved oxygen and substrate are all important factors for developing metabolic phenotypes in fish. In this thesis, effects of temperature, dissolved oxygen (DO) and substrate on standard metabolic rate (SMR), forced maximum metabolic rate (FMR), metabolic scope (MS), energy density (ED), enzyme activity associated with ATP regeneration (pyruvate kinase, lactate dehydrogenase and cytochrome c oxidase), condition factor (K), hepatosomatic index (HSI) and critical thermal maxima (CTmax) of developing age-0 Lake Sturgeon, Acipenser fulvescens, including a simulated overwintering event, were examined. This research revealed that temperature, dissolved oxygen and substrate all significantly influenced development of metabolic phenotypes in Lake Sturgeon. While reduced temperature significantly increased SMR, increased temperature substantially decreased the survival rate. Lower DO (80%) did not impact FMR and MS in the short term, however, prolonged exposure to mild hypoxia, particularly during the stressful condition of overwintering, significantly reduced FMR and MS. Inclusion of substrate was found to significantly enhance K and SMR, and it was suggested that substrate be used at the early yolk-sac stage to enhance growth and survival. Further, a strong linear relationship between dry to wet mass ratio and ED was found, which can be used practically to estimate energetic status of Lake Sturgeon. This research provides information regarding environment-phenotype interaction during the first year of life in Lake Sturgeon. This information will contribute to a better understanding of critical factors influencing the successful recruitment of populations that are endangered throughout most of their natural range.
Author: Ryan Brogan Mayfield
Publisher:
ISBN:
Category :
Languages : en
Pages : 92
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Author: Kevin E. Wehrly
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ISBN:
Category : Lake sturgeon
Languages : en
Pages : 29
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Author: Catherine Brandt
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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In fishes, differences in egg incubation, water temperature, and substrate can have a significant impact on phenotypic development. This is particularly relevant during the first year of life when growth rate peaks and influences an individual's life history trajectory. In the present study, Lake Sturgeon, Acipenser fulvescens, were reared in different environments for approximately one year. In the first year, sturgeon were reared in 3 temperature regimes (with or without substrate) that mimicked hatchery conditions or river temperature profiles. In the second year, embryos were incubated in MacDonald jars or adhered to substrate and newly hatched larvae were reared in different thermal environments (16, 18 and 20°C) for two weeks during the first month post-hatch. All treatments were then transferred to a common garden set-up where tanks were fed by river water at ambient temperature and natural light cycles. Fish were deprived of food when water temperature reached 1.5°C, then food was re-introduced when water temperature exceeded 2°C, approximately 4.5 months later. Yolksac volumes, body length and mass were assessed during both years. In the first year, there were differences in yolk sac absorption between substrate treatments in the first two weeks post-hatch, and differences in larval length between temperature treatments following the overwintering. In the second year, red muscle fibre area and myonuclear counts were assessed and volitional downward swimming and forced escape responses were tested. Growth rate in the first three months of life was highest in the 20°C group of fish but converged in all treatments during winter. Growth rate in fish raised in warmer waters during early life once again exceeded cooler water treatments post-winter, suggesting growth phenotype was fixed in early life, showing little phenotypic plasticity, and was temperature dependent. Thus, increased growing temperature during early life history results in development of a fast-growing phenotype post the first winter. Overall, there was an absence of significant differences between results for muscle fibre area and myonuclear counts between incubation and temperature treatments and the presence of significant differences between time points indicating a strong evolutionary pressure to maintain plasticity in muscle structure and swimming performance.
Author:
Publisher: Elsevier
ISBN: 0128242698
Category : Science
Languages : en
Pages : 670
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Book Description
Conservation Physiology for the Anthropocene – A Systems Approach, Volume 39B in the Fish Physiology series, is a comprehensive synthesis related to the physiology of fish in the Anthropocene. This volume helps solve knowledge gaps by considering the many ways in which different physiological systems (e.g., sensory physiology, endocrine, cardio-respiratory, bioenergetics, water and ionic balance and homeostasis, locomotion/biomechanics, gene function) and physiological diversity are relevant to the management and conservation of fish and fisheries. Chapters in this release include Using physiology for recovering imperiled species – the Delta smelt, Conservation hatcheries – the Sturgeon story, Aquatic pollutants and stressors, and more. Other sections discuss Fisheries interactions in a multi-stressor world, Environmental change in riverine systems - Amazon basin stressors, Environmental change in lakes and wetlands – East African basin stressors, Coral reef fish in a multi-stressor world, Polar fish in a multi-stressor world, Physiology informs fisheries restoration and habitat management, A physiological perspective on fish passage and entrainment, Invasive species control and management – the sea lamprey story, and On the conservation physiology of fishes for tomorrow. - Includes authoritative contributions from an international board of authors, each with extensive expertise in the conservation physiology of fish - Provides the most up-to-date information on the ways in which different physiological systems are relevant to the management and conservation of fish and fisheries - Presents the latest release in the Fish Physiology series - Identifies how anthropogenic stressors perturb physiological systems - Explores how different physiological systems can be exploited to solve conservation problems
Author: Michael Jonas Klein
Publisher:
ISBN:
Category :
Languages : en
Pages : 312
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: James Plohman
Publisher:
ISBN:
Category :
Languages : en
Pages : 332
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Author: Lydia Wassink
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 175
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Book Description
Environmental stressors experienced by wildlife can have profound impacts on behavior and physiology that may have consequences for survival. My dissertation investigates how early life stress influences physiology, behavior, and survival in lake sturgeon (Acipenser fulvescens), an ancient chondrostean fish species. Lake sturgeon are regionally threatened, and therefore exploring the mechanisms by which stressors influence fitness is important in informing conservation efforts. My dissertation examines behavioral and physiological outcomes of four potential stressors encountered by lake sturgeon larvae: high temperature, maternal-offspring environmental mismatch, captive rearing, and predator interaction. In Chapter 1, I examined effects of temperature by comparing lake sturgeon reared at 10°C (low stress) and 18°C (high stress). During the free embryo stage, individuals reared at 18C exhibited a smaller cortisol elevation in response to an acute stressor, indicating lower physiological reactivity to stress. At the larval stage, individuals reared at 18C had higher levels of swimming activity and higher survival rates when exposed to a crayfish predator. Findings suggest that physiological and behavioral phenotypes induced by early life stress may be adaptive during subsequent life stages in high-stress contexts such as exposure to predatorsIn Chapter 2, I further explored the adaptive potential of stress-related phenotypes. Since stressed females can provision eggs with elevated cortisol that potentially prepares offspring for high-stress conditions, I investigated outcomes of a match or mismatch between egg cortisol and offspring stress levels. Individuals that experienced both high egg cortisol and high stress had reduced cortisol reactivity to an acute stressor, but only in one of two families. Results suggest that family (genetic) effects may mediate the interaction of maternal and offspring stress experiences. The largest differences in swimming activity occurred between the "mismatch" treatments, indicating that the combination of egg cortisol and offspring stress is more important in determining offspring behavior than is egg cortisol or offspring stress alone. In Chapter 3, I evaluated the role of stress in conservation programs by comparing stress levels, behavior, and predation rates for hatchery-produced and wild-caught lake sturgeon larvae. Cortisol levels did not indicate that hatchery-produced individuals were more stressed, but cortisol reactivity to an acute stressor disappeared for both hatchery-produced and wild-caught larvae after 9 days in the hatchery. Predation rates increased over time for larvae from both treatments, suggesting that the hatchery environment may inhibit survival even though individuals do not exhibit high stress. Results highlight that effects of captive rearing become evident after only a short duration spent in captivity during early ontogeny. In Chapter 4, I investigated stress-related effects of encounters with aquatic insects commonly found in stream substrate during the free embryo stage. Lake sturgeon experienced stress proportional to the amount of predation risk experienced. Individuals that encountered Perlidae (obligate predators) had high mortality as well as elevated cortisol and cortisol reactivity to an acute stressor. Individuals that encountered Isonychiidae (facultative predators) had slightly elevated mortality compared to individuals that encountered no insects, and had slightly elevated cortisol levels and cortisol reactivity. Results indicate early life stress as a mechanism by which nonlethal predator interactions impact lake sturgeon, indicating the importance of community-level ecological context in predicting outcomes for species of conservation concern.
