The Influence of Social and Environmental Factors on the Stress Response and Development in Juvenile & Larval Lake Sturgeon, Acipenser Fulvescens PDF Download
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Author: Ahmed Waheed
Publisher:
ISBN:
Category :
Languages : en
Pages : 228
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Book Description
Sturgeon -- Stress -- Microscopy -- Physiology -- Catecholamine -- Chromaffin -- Juvenile -- Larvae -- Kidney.
Author: Ahmed Waheed
Publisher:
ISBN:
Category :
Languages : en
Pages : 228
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Book Description
Sturgeon -- Stress -- Microscopy -- Physiology -- Catecholamine -- Chromaffin -- Juvenile -- Larvae -- Kidney.
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: Forrest Bjornson
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Hatchery supplementation of declining fish populations is often used as part of population enhancement and recovery programs. However, fish produced from the sterile hatchery environment often develop maladaptive behavioural phenotypes that can result in high post-release mortality. Lake Sturgeon (Acipenser fulvescens) are reared in hatcheries for conservation purposes, yet little is known of their early life behaviour. Here, I investigate the influence of body size on resource holding potential (RHP) and boldness, and the potential for predator conditioning to influence risk assessment and the physiology of juvenile Lake Sturgeon. Results indicate condition factor, rather than body size, increases RHP and bold responses in juvenile Lake Sturgeon. Additionally, conditioning did not influence risk assessment behaviour. However, foraging remained paramount, and chronic conditioning had an effect on whole body cortisol concentrations, suggesting a sensitive stress response. These results indicate the complex early life behaviour of juvenile Lake Sturgeon, both behaviourally and physiologically.
Author: Lydia Wassink
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 175
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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.
Author: Kevin E. Wehrly
Publisher:
ISBN:
Category : Lake sturgeon
Languages : en
Pages : 29
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Author: Sadaf Naeem Zubair
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Joseph Jerry Riedy
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 0
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Species are vulnerable to predation during early in life stages, especially those who provide little or no parental care. Predation risk is further elevated during periods of migration when individuals are exposed to a greater abundance and diversity of predators. Levels of predation during migration are often variable and can be heavily influenced by environmental conditions and changes in behavior. It is important to understand how these factors influence predation rates of threatened and endangered species. Lake sturgeon are an imperiled species native to the Great Lakes, Mississippi River, and Hudson Bay drainages that undergo a downstream from spawning grounds to nursery habitat at the beginning of the larval stage. This migration begins at night and larvae are exposed to several known predator species as they migrate the length of the spawning river in event. In this dissertation, I examine influences of ecological factors and behavior on levels of predation during the downstream migration. In Chapters 1 and 2, I used mesocosm experiments to determine the effects of night light level, rearing temperature, and prey abundance on survival during migration. Survival is highest during the environmental conditions present early in the season: new moon light levels, colder rearing conditions, and when prey abundance is high. In Chapters 3 and 4, I returned to the mesocosms to examine the survival implications of the behavioral responses to alarm cues during the larval stage. Lake sturgeon larvae exposed to a predator species odor and lake sturgeon alarm cue have higher survival rates when later exposed to the predator species. Additionally, lake sturgeon can use alarm cues from unrelated allopatric and sympatric species as kairomones similarly to conspecific alarm cues. In Chapter 5, I collected lake sturgeon larvae and predator diets from a natural lake sturgeon spawning stream to estimate nightly mortality rates, identify the predatory species that consumed, and determine the environmental factors that influence lake sturgeon mortality in a wild population. Survival rates varied greatly, but on average, approximately one third of lake sturgeon larvae survived the section of the river sampled. Additionally, roughly one third of all potential predator diets sampled contained lake sturgeon. Similar to previous chapters, light level and the abundance of prey had the greatest influence on the survival rates of lake sturgeon and the probability of detecting lake sturgeon in the diets of potential predators. Results indicate the timing of lake sturgeon spawning influences larval survival by determining the ecological conditions present during offspring development and downstream migration. Work presented here identifies the factors with the strongest influence on larval lake sturgeon survival. Though variation in larval lake sturgeon mortality is high, managers may begin to use these factors to forecast larval lake sturgeon survival rates in populations. It will be important to monitor changes to these ecological variables, such as fluctuations in co-distributed fish and invertebrate populations, and variation in water temperatures during development, because these factors have strong and predictable influences lake sturgeon recruitment rates.
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: Laura Henderson
Publisher:
ISBN:
Category : Gillnetting
Languages : en
Pages : 101
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The dynamics of early life stages of Lake Sturgeon ( Acipenser fulvescens) within a large impounded river were studied. Recruitment success, larval drift, and basic habitat and diet use were observed and analysed over a two-year period. As part of a separate study, larval drift monitoring, and juvenile gillnetting were conducted one year prior to the start of the current study; these results were considered preliminary work and included in the analyses. Timing, duration, and extent of larval drift varied from year to year. No correlation was found between year-class strength and water discharge or temperature. Post-drift, age-0 Lake Sturgeon were found in habitats consisting of sand substrates, in depths of greater than 6 m (maximum 24 m), and low to medium velocities (0.0- 0.4 m s-1 ). Diet was composed of Diptera, Ephemeroptera, Trichoptera and Nematoda. Age-0 Lake Sturgeon captured in Dorothy Lake only consumed Dipteran organisms. Nitrogen isotopes indicated that age-0 Lake Sturgeon captured in this lake were significantly different from those captured in other locations of the study area. Daily growth was calculated as 2.0 mm in total length and 0.20 g in weight from August through September. Findings from this study will aid in future age-0 Lake Sturgeon research and management including artificial propagation and nursery habitat remediation.
Author: James Andrew Crossman
Publisher:
ISBN:
Category : Fish stocking
Languages : en
Pages : 388
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