Dissertations / Theses on the topic 'Juvenile survival'
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1
Smith, Cyndi. "Survival and recruitment of juvenile Harlequin Ducks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0023/MQ51472.pdf.
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Anderson, Elizabeth Marie. "Survival and behaviour of juvenile red squirrels, Tamiasciurus hudsonicus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ47002.pdf.
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Rash, Jacob Michael. "Comparative Ecology of Juvenile Striped Bass and Juvenile Hybrid Striped Bass in Claytor Lake, Virginia." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9850.
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Since the introduction of hybrid striped bass M. chrysops x M. saxatilis to Claytor Lake, Virginia in 1993, relative abundance of striped bass Morone saxatilis has dropped disproportionately to stocking density. Potentially deleterious interactions between the two fishes that may limit recruitment to age 1 were considered in terms of trophic relationships, physiological indices of health, overwinter survival, and post-stocking predation.
Both fishes preferred habitat types characterized by structure-free sand or gravel substrates, but striped bass and hybrid striped bass did not exhibit significant diet overlap during the growing season. At a total length of approximately 120 mm, the juvenile moronids shifted from a mixed diet of zooplankton and invertebrates to a diet comprised primarily of age-0 fishes. However, after becoming piscivorous striped bass preyed primarily upon age-0 alewife Alosa pseudoharengus, while hybrid striped bass consumed age-0 sunfishes.
Striped bass achieved mean total lengths of 229 and 173 mm by the end of the growing season in 2001 and 2002, respectively. Stocked into the reservoir three months later than striped bass, mean hybrid striped bass total lengths reached 133 mm at the end of the 2002 growing season. Condition factor, relative weight, and lipid index values were low, but nearly equivalent for both striped bass and hybrid striped bass throughout this study. Overwinter starvation of smaller (< 150 mm total length) striped bass was observed for the 2001-2002 sampling season. Predation upon stocked fingerlings was not considered significant in limiting juvenile survival; only three fingerling moronids were found in the examination of stomach contents of 200 potential predators captured near stocking sites.
It does not appear that resource competition with hybrid striped bass during the growing season resulted in increased overwinter mortality of juvenile striped bass. Delayed stocking of hybrid striped bass lessens the potential for trophic competition between striped bass and hybrid striped bass at this early life-stage.Master of Science
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Schulman, Jessica L. "Habitat Complexity as a Determinant of Juvenile Blue Crab Survival." W&M ScholarWorks, 1996. https://scholarworks.wm.edu/etd/1539617703.
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Hovel, Kevin. "The effect of seagrass habitat fragmentation on juvenile blue crab survival." W&M ScholarWorks, 1999. https://scholarworks.wm.edu/etd/1539616700.
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Habitat fragmentation leads to small, isolated habitat patches in which ecological processes may differ substantially from those in larger, continuous habitats. Seagrass is a structurally complex but fragmented subtidal habitat that serves as a refuge from predation for juveniles of the blue crab, Callinectes sapidus Rathbun. I compared the effects of eelgrass ( Zostera marina L.) patch size and shoot density on juvenile blue crab survival both before (June) and after (September) shoot defoliation and cownose ray disturbance changed eelgrass habitat, and used artificial seagrass to determine the influence of eelgrass patch size on juvenile blue crab survival in the absence of covarying shoot density. Under natural conditions, eelgrass patch size, eelgrass shoot density and density-dependent cannibalism all influenced juvenile blue crab survival, but crab survival varied temporally. Crab survival was inversely correlated with eelgrass patch size in the absence of covarying shoot density, in contrast to patterns typically observed in fragmented terrestrial landscapes; this was likely due to low predator abundance in small patches. I tested the hypothesis that crab survival is maximized at an intermediate level of seagrass fragmentation due to the inverse relationship between crab survival and patch size by modeling the joint effects of patch size and proportional cover on juvenile blue crab survival. When I assumed predation on crabs to be independent of crab density, maximal crab survival (ca. 34%) occurred at intermediate values of seagrass fragmentation. Approximately 18% of crabs survived irrespective of the proportion of the landscape covered by seagrass when crab survival was assumed to be density-dependent. My findings indicate that (i) effects of habitat fragmentation on survival may differ between seagrass and terrestrial landscapes, (ii) seagrass habitat fragmentation has a significant but not overriding influence on faunal survival, and (iii) seagrass patch size, seagrass complexity, and blue crab density all influence juvenile blue crab survival, but their effects vary temporally. Habitat fragmentation studies should incorporate multiple scales of space and time, as well as potentially confounding environmental variables.
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Hylton, Rebecca A. "Survival, movement patterns, and habitat use of juvenile wood storks, Mycteria americana." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007007.
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Parker, Michael W. "Impact of adventure interventions on traditional counseling interventions /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1992.
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Kerr, Tricia D. "Direct and indirect energetic influences on juvenile red squirrel survival, recruitment, and reproduction." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99189.
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This thesis evaluates how developmental conditions influence settlement, survival, and yearling primiparity in juvenile red squirrels. This was accomplished by comparing the fates of offspring from food supplemented versus non-supplemented mothers, and by using logistic regression to evaluate the effects of body mass, resource availability, and reproductive parameters on juvenile success. Maternal nutrition, previous and present year's cone production, and body mass contributed significantly to settlement and survival during all juvenile life history stages (emergence, settlement, and overwinter survival). Heavier than average juveniles were also more likely to reproduce as yearlings. Nevertheless, natal body mass was not a predictor of recruitment, indicating persistent influence of early developmental conditions on life history fates above and beyond mass effects. A greater impact of resource availability than body size on fitness among red squirrels may reflect this species' reliance on hoarded food rather than body fat for energy reserves.
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Semones, John David. "Consequences of nesting date on nesting success and juvenile survival in white ibis." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000784.
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Fenton, Jenny. "Post-Release Survival and Habitat Utilization of Juvenile Swordfish in the Florida Straits." NSUWorks, 2012. http://nsuworks.nova.edu/occ_stuetd/191.
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The use of pop-up satellite archival tags (PSATs) eliminates many of the limitations associated with acoustic and conventional tags by using fishery-independent data collection and retrieval. Previous research techniques have provided information on longer-term movements, migrations, and behavior patterns, but there is still a need for additional tagging studies using tags with depth and light data and increased memory that will further define the short-duration activity patterns and habitat utilization of juvenile swordfish in the western North Atlantic. PSATs have been successfully used on other large pelagic fishes, but have yet to be used on juvenile swordfish. This study investigated two main topics: a) the post-release survival rates of juvenile swordfish after being released from the recreational rod-and-reel fishery and commercial swordfish buoy gear fishery in the Florida Straits, and b) the habitat utilization of juvenile swordfish following release. High-resolution PSAT technology was used to estimate the post-release survival of 16 individual juvenile swordfish captured with standard recreational or buoy fishing gear and techniques in the southeast Florida swordfish fishery. Analysis of release mortality estimates was done using the “Release Mortality” Program. Five of the fourteen reporting tags showed a mortality within 48 hours, for a release mortality rate of 35.7%. However, no common thread could be found among the five mortalities. Results of the Release Mortality program indicated that if the true mortality rate was 35.7%, approximately 1800 tags would have to be deployed to increase the precision of the mortality estimates to +/- 5% of the true value. The nine surviving fish varied in straight-line distance traveled and in direction, and could withstand a wide range of temperatures. A deterministic, periodic model was developed to fit to the data and describe the fishes’ habitat utilization. This model identified both diurnal and lunar signals in the data, confirming that juveniles do move vertically based on the daily cycle of the sun and the lunar cycle of the moon and that their diurnal movements are much greater than their lunar movements. The results of this study can be valuable to management practices in future stock assessments and decisions regarding mandatory release of undersized fish.
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O'Donoghue, Mark. "Reproduction, juvenile survival and movements of snowshoe hares at a cyclic population peak." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30244.
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Snowshoe hare (Lepus americanus) populations were provided with supplemental food on two study grids in the southwest Yukon to examine the effects of food on reproduction and juvenile growth. Timing of parturition, pregnancy rates, litter sizes, male breeding condition, and juvenile growth rates were measured on the food grids and on two control grids during two summers at a cyclic peak in hare numbers. The main effects of food addition were to increase hare densities 2.1- to 2.7-fold, to advance the timing of breeding by about a week in one year, and to increase the mean size of third litter 30% in one year relative to the controls. There were no significant differences in pregnancy rates, litter sizes in five of six litter groups, length of male breeding season, or juvenile growth rates between hare populations on the food and control grids. Third litter stillborn rates were higher, and third litter juveniles grew slightly more slowly on food grids relative to those on controls, possibly because of higher densities. This study suggests that food is not a proximate factor limiting hare reproduction and early juvenile growth at the observed peak hare densities.
Juvenile snowshoe hares were radio-tagged at birth on one food addition grid and one control grid, to determine early juvenile survival rates, the effects of the food addition on these rates, and the proximate causes of mortality. Indices of survival were estimated by live-trapping on these grids, and on one additional set of grids. Thirty-day survival rates were 0.46, 0.15, and 0.43 for the first, second and third litters of the year, respectively. There were no differences between early juvenile survival on the food addition and control grids in any of the litter groups. The main proximate cause of juvenile mortality was predation by small mammalian predators, the most important being red squirrels and arctic ground squirrels. Seventy percent of early juvenile mortality occurred during the first 5 days after birth. Survival of littermates was not independent; Utters tended to all live or die as a unit more often than expected by chance. Fifty-one percent of litters had no known survivors after 14 days of age. Individual survival rates were negatively related to litter size, positively related to body size at birth, and litter size was negatively correlated with body size, suggesting trade-offs as predicted by life history theory. The number of recruits per litter, and the probability of total litter failure, did not differ significantly over the observed range of litter sizes.
The radio-tagged juveniles were also followed to examine pre-dispersal movements, maternal-juvenile interactions, and timing of natal dispersal. Hare Utters stayed at their nest sites for an average of 2.7 days, after which each individual hare usually found a separate hiding place from its littermates. Juvenile hares ranged progressively farther from their nest sites as they grew, up to the age of 20 days. From 20 to 35 days of age, leverets stayed approximately 75 m from their nest sites, after which time their movements again increased. Observations at nest sites suggested that adult female hares nursed their litters only once per day, shortly after twilight. Some females aggressively defended their newborn litters before the juveniles left the nests. Natal dispersal of juvenile hares began shortly after weaning at 24-28 days of age. Many third litter juveniles were nursed for a longer period of at least 29-40 days. Juvenile males may disperse sooner and travel farther than females from their natal ranges.Science, Faculty of
Zoology, Department of
Graduate
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Mintz, Jonathon Daniel. "Survival and Abundance of Juvenile Caribbean Spiny Lobster: Effects of Shelter Size and Geographic Location." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539617652.
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Bromilow, Amanda Marie. "Juvenile Blue Crab Survival in Nursery Habitats: Predator Identification and Predation Impacts in Chesapeake Bay." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639467.
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Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. to reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the role of habitat, body size, finfish predation, and cannibalism on the survival of one of the most ecologically and economically important species in Chesapeake Bay: the blue crab Callinectes sapidus. In field tethering experiments, survival probability of juvenile blue crabs in York River nursery habitats (i.e. seagrass beds, sand flats) increased significantly and additively with crab size and SAV cover. Images of predation events during tethering experiments revealed cannibalism by adult blue crabs to be a major source of juvenile mortality. Gut content analyses from three field studies identified seven predators of juvenile blue crabs in lower Chesapeake Bay nursery habitats: adult blue crabs, striped bass Morone saxatilis, red drum Sciaenops ocellatus, silver perch Bairdiella chrysoura, weakfish Cynoscion regalis, Atlantic croaker Micropogonias undulatus, and oyster toadfish Opsanus tau. Using frequency of consumption and diet proportion metrics, I determined striped bass, red drum, and silver perch to be the most impactful finfish predators on juvenile mortality, in addition to cannibalism. Atlantic croaker and oyster toadfish play minor roles in juvenile mortality in Chesapeake Bay nursery habitats. The probability of juvenile crabs being present in a predator’s gut was also significantly higher in seagrass beds than in unvegetated sand flats. Food web dynamics are an important aspect of ecosystem-based fisheries management. Understanding the ecological interactions between populations, and their environment, can provide insight into natural population fluctuations of valuable fishery species such as the blue crab. This thesis demonstrated the positive effects of body size and SAV cover on juvenile crab survival, indicating the importance of seagrass nursery habitat for blue crab population dynamics in Chesapeake Bay. However, despite the predator refuge offered by SAV, high densities of predators and prey in seagrass beds resulted in greater consumption of juveniles in those habitats. Key predators of juvenile blue crabs were also identified and their relative impacts were estimated. The predator-prey relationships revealed in this thesis were integrated into a revised food web for blue crabs in Chesapeake Bay, in the hopes of informing future ecosystem-based management efforts.
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McGinnis, Todd Milton. "Hopelessness Depression as a Predictive Risk Factor for Recidivism and Survival Time Among Juvenile Offenders." ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/4464.
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In the United States, there is a high incidence of recidivism among juvenile offenders with mental health disorders. This is a critical social issue facing the public and the Department of Juvenile Justice Administration today. However, research is not clear on the role of psychological factors in recidivism frequency and survival time. The purpose of this study was to examine whether hopelessness depression, as measured by suicidal-ideation, depression-anxiety, anger-irritation, and alcohol-drug use, and offense type, were predictors of recidivism frequency and survival time when controlling for age, gender, and race. The total sample consisted of archival data from 404 juvenile offenders between the ages 13 and 19, who were detainees in the Juvenile Detention facility between January 1, 2009, and December 31, 2012. Data consisted of scores from the Massachusetts Youth Screening Instrument, which is part of the standard intake screening at time of booking. A hierarchical regression analysis indicated a collective significant predictive relationship between age, gender, race, suicidal-ideation, depression-anxiety, anger-irritation, alcohol-drug-use, and recidivism frequency and survival time. Posthoc analyses of variance indicated statistically significant differences in alcohol-drug-use and anger-irritation levels between races. However, the multiple linear regression indicated that suicidal-ideation and depression-anxiety did not significantly predict either recidivism frequency or survival time. Results could enable juvenile justice staff to detect hopelessness depression among juvenile reoffenders at an earlier stage and offer better treatment aimed at reducing future occurrences of youth recidivism, thereby benefitting individuals as well as society.
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Wilkins, Keiko W. "The Importance of Dissolved Organic Matter Source on the Survival and Growth of Juvenile Daphnia." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1578699709430677.
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O'Hara, Patricia Jeanne. "A preliminary investigation into the survival of reintroduced captive bred juvenile northern brown bandicoots, Isoodon macrourus /." St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17964.pdf.
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Hanni, Krista Deanne. "Assessment of baseline health, juvenile survival, and a rehabilitation program for southern sea otters (Enhydra lutris nereis) /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Falls, Justin A. "The Survival Benefit of Benthic Macroalgae Gracilaria vermiculophylla as an Alternative Nursery Habitat for Juvenile Blue Crabs." W&M ScholarWorks, 2008. http://web.vims.edu/library/Theses/Falls08.pdf.
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Marshall, Livingston Sinclair Jr. "Survival of juvenile queen conch, Strombus gigas, in natural habitats: Impact of prey, predator and habitat features." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539616765.
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In this dissertation, I experimentally examine predation-induced mortality upon juvenile queen conch, Strombus gigas, and assess the importance of select habitat predator and conch characteristics affecting predation intensity. Experiments were conducted during the summer and early fall of 1987, 1988, 1990 and 1991 in seagrass beds and adjacent sand flats near Lee Stocking Island, Exuma Cays, Bahamas. These experiments indicate that various factors act interactively to produce habitat-specific mortality rates in queen conch due to predation. These include (1) habitat type, whereby seagrass beds offer some protection; (2) local population dynamics, such that populated seagrass beds appear to enhance conch survival; (3) population density in some seagrass beds, such that mortality is inversely density-dependent; (4) conch size, such that larger conch have higher survival rates, depending on the specific type of habitat; and (5) predation intensity and predator guilds, which likely differ across habitats, producing habitat-specific mortality rates. When integrated with complementary studies of queen conch trophodynamics, these results provide critical information regarding key ecological factors affecting conch survival. In particular, results from the hatchery-reared experiments demonstrate the potential use of hatchery-reared stocks in natural habitats, and hence a valuable option for enhancement of fishery stocks throughout the Caribbean. In general, the integration of results obtained in this dissertation, with complementary studies of queen conch trophodynamics, should provide valuable suggestions of queen conch habitats, densities and scales of patchiness producing highest survivorship and growth rates in nature.
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Muller, Liezl. "Effects of illumination, shading and temperature on the settlement, survival and growth of juvenile abalone (Haliotis midae)." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/6973.
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In aquaculture, a thorough knowledge of the specific environmental requirements of a species is needed in order to maximize growth and survival rates. Several studies have helped develop the technology necessary for the intensive commercial culture of Haliotis midae. However, a considerable amount of research is still required to develop the most appropriate and optimal method for the cultivation of this species. In particular there remains a lack information on the feeding habits of the early life stages and as a result the survival rates of spat are still low and variable. This prompted the design of three experiments to determine the best illuminance and water temperature conditions to maximize the settlement, growth and survival of H midae post-larvae. These experiments also investigated what effect different illumination and water temperatures would have on the growth of diatom colonies as substrate for the abalone post-larvae during and after settlement.
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Johnston, Gavin. "Effect of feeding regimen, temperature and stocking density on growth and survival of juvenile clownfish (Amphiprion percula)." Thesis, Rhodes University, 2001. http://hdl.handle.net/10962/d1005118.
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In aquaculture, a thorough knowledge of the specific environmental requirements of a species is needed in order to maximize growth rate and survival. There is a paucity of data regarding the fundamental environmental requirements for the ongrowing phase of clownfish juveniles. This prompted the design of three experiments to determine the best feeding regimen, temperature and stocking density that maximize growth and survival of Amphiprion percula. Ration size and feeding frequency are important factors for optimizing fish growth during the juvenile grow-out phase. A factorial growth trial was conducted to determine the effect of feeding frequency and ration size on the growth of juvenile clownfish (Amphiprion percula).Three feeding frequencies (1, 2 and 3 times daily) and six rations (2,4,6,8, 10 and 12 % body weight per day (BW.day⁻¹)) were used to test the growth response over a twelve week period. Non-linear regression analysis on the effect of ration, independent of feeding frequency, on growth resulted in a significant (n = 36; r² = 68.7) parabolic model: In y = -0.0302x² + 0.5159x + -4.4377. Maximum growth corresponded to a ration of 8.5% BW.day⁻¹. Survival as a function of ration was significantly lower at 2% BW.day⁻¹. Data were further examined with Analysis of CoVariance (ANCOVA) to determine the effect of ration on growth at each feeding frequency. The combination revealed a maximum growth rate when the fish were fed a ration of 10% BW.day⁻¹ divided into two equal meals. The required ration per meal to maintain maximum growth was also found to decrease as feeding frequency increased. The determination of the best temperature for growth is of great importance due to the direct relationship between fish metabolism and temperature. The thermal preferendum of A. percula has already been estimated at 26 ± 0.7°C but it is not known whether this closely approximates the temperature for maximum growth. Sixteen tanks were set to different temperatures ranging between 21.5 and 30.2 °C. Ten juvenile A. percula were placed in each tank and growth was measured fortnightly over the course of the 10 week experiment. Non-linear regression analysis resulted in significant models for fish length (y = -0.0005x² + 0.00267x - 0.0338; r² = 56.7, n = 11) and weight (y= -0.00016x² + 0.0084x - 0.1073; r² = 61.6, n = 11). These models predict that maximum growth would be at 27.7 and 27.1 °C for length and weight, respectively. Temperature, over the range tested, had no apparent effect on survival. There was no significant difference between the temperatures for maximum growth and the preferred temperature. The effect of stocking densities ranging from 0.2 fish.L¹ to 4.0 fish.L⁻¹ on growth were used in the third experiment. The fish were fed to satiation twice daily and growth was measured fortnightly throughout the 8 week experiment. No effects on growth, survival or coefficient of variation were found within the range of stocking densities tested.
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Harper, Leah M. "Variation in Coral Recruitment and Juvenile Distribution Along the Southeast Florida Reef Tract." Thesis, NSUWorks, 2017. https://nsuworks.nova.edu/occ_stuetd/458.
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Coral recruitment in Southeast Florida is being outpaced by mortality, resulting in population declines in many species. Identifying the coral species most likely to recruit and survive on Southeast Florida reefs and evaluating spatial variation in recruitment and survivorship is crucial for managing decreasing coral populations. This study focuses on 12 sites in Broward and Miami-Dade counties that have served as long-term stations for monitoring adult coral cover and demographics. At each site, thirty-two 225cm2 grooved terracotta settlement tiles were attached to the substrate in winter of 2015 and retrieved in winter of 2016 to evaluate scleractinian and octocoral recruitment rates. Thirty-two corresponding 0.25 m2 quadrats were surveyed in situ for coralsconditions, such as Poritidae, Siderastreidae, and Octocorallia, exhibit signs of recruitment success and/or juvenile survivorship. Scleractinian recruitment was not variable spatially, but juvenile densities varied on site-level spatial scales, suggesting that differential survivorship structures adult scleractinian communities. This study will inform reef management and restoration efforts within Southeast Florida by identifying sites and species with potential to recover from disturbance through natural recruitment processes.
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Beaty, Braven B. "Development of juvenile culture techniques and testing of potential biomarkers of environmental stress in freshwater mussels (Bivalvia: Unionidae)." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/39679.
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The freshwater mussel fauna of the Clinch River in Southwest Virginia has declined in recent decades, principally due to habitat degradation from poor land-use patterns and pollutants. A study was undertaken to determine the feasibility of using river water in a flow-through culture system to rear juvenile freshwater mussels. The culture method placed juvenile mussels, confined in small dishes, into oval troughs supplied with untreated river water. Two of three years produced acceptable survival rates of 27% and 19% to an age of 90 days or greater. The third year yielded very low survival rates of less than 3%, demonstrating that failures in culture production can occur. Growth rates of juveniles in the culture system using river water were almost double those in laboratory culture systems, provided that juveniles were placed in the oval troughs during June. Otherwise, growth was comparable to that attained in laboratory culture systems.Ph. D.
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Rechisky, Erin Leanne. "Migration and survival of juvenile spring Chinook salmon and sockeye salmon determined by a large-scale telemetry array." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23349.
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This thesis documents the use a large-scale acoustic telemetry array to track hatchery-reared salmon smolts during their seaward migration, presents estimates of early marine survival, and describes migration behaviour in the ocean of two species of Pacific salmon from the Columbia and Fraser River basins.
In the Columbia River basin, it is hypothesized that seaward migrating Snake River spring Chinook salmon suffer from “delayed mortality” due to passage through eight hydropower dams or “differential delayed mortality” from transportation via barge around the dams. I tested these hypotheses by comparing survival of in-river migrating smolts from the Snake River basin to 1) a Yakima River population that migrated past only four dams and 2) a Snake River group that was transported around all dams. Early marine survival estimates of non-transported Snake and Yakima smolts from the mouth of the Columbia River to Vancouver Island (a 485 km, one month journey) was equal in both 2006 and 2008 (2007 estimates were not available), which contradicts the delayed mortality theory. Early marine survival for the transported groups was slightly higher than for the in-river migrants, again contradicting the differential delayed mortality theory. These measurements form the first direct experimental test of key theories concerning juvenile fish survival in the coastal ocean.
Cultus Lake sockeye salmon are a genetically unique population from the Fraser River basin and are now endangered due to the very low return of adults in recent years. Mean survivorship of smolts (2004-7) from release to the northern Strait of Georgia ranged from 10-50%, while survivorship to the final sub-array in Queen Charlotte Strait ranged from 7-28%. Cultus Lake smolts displayed four migratory behaviours: northward migration to enter the Pacific Ocean via Queen Charlotte Strait; westward migration through the Strait of Juan de Fuca; migration into Howe Sound before continued the migration north; and migration upstream into Cultus Lake. These are the first direct observations of movement and survival for Fraser River sockeye salmon smolts. The availability of early marine survival data fills key knowledge gaps and as well as permitting direct testing of important salmon conservation hypotheses and rapid scientific advance.
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Friesen, Trevor. "Effects of food abundance and temperature on growth, survival, development and abundance of larval and juvenile smallmouth bass." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ33299.pdf.
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Galarno, Ashton J. "Coral vs. Macroalgae: Relative Susceptibility to Sedimentation and Ocean Warming." NSUWorks, 2017. http://nsuworks.nova.edu/occ_stuetd/450.
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Sedimentation and ocean warming are two major anthropogenic stressors that directly affect coral recruitment and recovery. Many coral-dominated reefs have undergone phase shifts becoming macroalgae-dominated because of the coral population’s inability to tolerate these increasing stressors. Predicting these phase shifts requires a determination of the relative susceptibility of coral and macroalgae to these stressors. The objective of this study was to quantitatively assess the synergistic effects of sedimentation and elevated temperature on the survival and growth of Montastraea cavernosa newly settled coral juveniles, and fragments of the macroalgae, Dictyota ciliolata. A crossed experimental design tested the two temperatures and four sedimentation levels. After 12 weeks, a 2°C increase in temperature did not significantly affect survival of the M. cavernosa juveniles or fragments of D. ciliolata. Montastraea cavernosa juvenile survival was negatively affected by a decrease in sediment. Dictyota ciliolata survival was highly sensitive to the increase in sedimentation. The survival and growth of both species appeared to be susceptible to an increase in sedimentation, but in opposite ways. This study demonstrates that both M. cavernosa juveniles and D. ciliolata fragments may be more vulnerable to light caused by changes in turbidity rather than temperature.
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Pate, Jessica Hope. "A comparison of body proportions in juvenile sea turtles| How shape may optimize survival in a vulnerable life stage." Thesis, Florida Atlantic University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1527083.
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Gibbs, David A. "Distance-dependent survival and distribution of juvenile corals: Janzen-Connell effects do not operate on two brooding Indo-Pacific corals." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52231.
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The Janzen-Connell hypothesis proposes that species-specific enemies promote species coexistence through distance- and density-dependent survival of offspring near conspecific adults. I tested this hypothesis experimentally by transplanting juvenile-sized fragments of two species of brooding corals varying distances from conspecific adults, and observationally by assessing the spatial distribution of those two species in the field. Small fragments (as proxies for ?6 month old juveniles) of Pocillopora damicornis and Seriatopora hystrix were transplanted 3, 12, 24 and 182 cm upstream and downstream (relative to the prevailing current) of conspecific adults and their survivorship and condition (bitten off, overgrown by algae, or bleached) checked every 1-2 d. I also characterized the spatial distribution of P. damicornis and S. hystrix within replicated plots on three Fijian reef flats and measured densities of small colonies within 2 m of larger colonies of each species.
Contrary to the Janzen-Connell hypothesis, juvenile-sized transplants exhibited no differences in survivorship as a function of distance from adult P. damicornis or S. hystrix and P. damicornis and S. hystrix were aggregated rather than overdispersed on natural reefs. Survival unaffected by distance from focal colonies as well as certain recruitment processes could generate the observed aggregation. I did observe predation of P. damicornis that was spatially patchy and temporally persistent due to feeding by the territorial triggerfish Balistapus undulatus. This patchy predation did not occur for S. hystrix. Thus, I found no support for the Janzen-Connell hypothesis, but did document hot-spots of species-specific corallivory that could create variable selective regimes on an otherwise more uniform environment, and help maintain the high diversity of corals typical of Indo-Pacific reefs.
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Robbins, Jena. "Effects of ocean warming, sedimentation, and parental genotype on the post-settlement survival and growth of Acropora cervicornis recruits." Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/483.
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Ocean warming and increased sedimentation from coastal activities are major threats to coral persistence. This study assessed the effects of increased temperature and sedimentation on the survival and growth of Acropora cervicornisrecruits. The potential for adults from different regions and genotypes to confer their offspring with higher or lower tolerance to heat and/or sediment was also determined. Gametes were collected and brought to the laboratory for cross fertilization of different genotypes within the regions collected. Larval rearing and settlement were then performed in the laboratory. Newly settled recruits were reared at 29 and 31°C (current summer temperature for August 2017 and +2°C as predicted for 2050) and 4 deposited sediment levels and turbidity (0, 30, 60, and 120mg cm-2, corresponding to 0, 4.52-5.35, 8.16-9.7, and 18.53-19.4 NTU). Recruit survival and growth were measured weekly for 3 months. Increased temperature reduced survival, suggesting faster usage of energy reserves. Regardless of temperature, survival was maximized under 30mg cm-2sediment; the highest sediment level drastically reduced survival. Increasing temperature by 2°C was as deleterious as doubling the natural level of deposited anthropogenic sediment, suggesting that eliminating local stressors may allow recruits to better sustain ocean warming. Growth was not affected by temperature nor sedimentation. Recruits produced by parents from the Florida Keys had a lower initial size but higher growth rate than those from Broward County. None of the parental genotypes conferred their offspring with higher or lower tolerance to warming and/or sedimentation. Reducing turbidity to 4.52-5.35 NTU or less during coastal construction may facilitate the persistence of this species by reducing recruit mortality the first 3 months post-settlement.
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Rankin, Tauna Leigh. "The Effects of Early Life History on Recruitment and Early Juvenile Survival of a Coral Reef Fish in the Florida Keys." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/405.
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Processes that influence the early life stages of fishes can significantly impact population dynamics, yet they continue to be poorly understood. This dissertation examined relationships between the environment, early life history traits (ELHTs), behavior, and post-settlement survival for a coral reef fish, Stegastes partitus, in the upper Florida Keys, to elucidate how they influence juvenile demography. Otolith analysis of settlers and recruits coupled with environmental data revealed that S. partitus surviving the early juvenile period settled at larger sizes and grew slower post-settlement. Water temperature also influenced the ranges of these and other ELHTs as well as the intensity and direction of selective mortality processes acting on some of these traits (i.e., pelagic larval duration, mean larval growth). Otolith analysis was paired with behavioral observations of newly settled juvenile S. partitus in the field to reveal that the relationship between size-at-settlement, early juvenile growth and survival is behaviorally-mediated. Individuals that were larger at settlement were more active (i.e., spent less time sheltered, swam farther from shelters) and grew more slowly post-settlement. Likewise, slower juvenile growth was associated with greater activity, more conspecific aggression, and faster escape swimming speeds. A six-year time series of recruitment densities revealed substantial temporal (interannual, seasonal, lunar) and spatial (by microhabitat, conspecific density) variability in recruitment which influenced the composition of recruits. For instance, larvae settling during the darkest phases of the moon were larger at settlement, but selective mortality processes during brighter periods removed more of the smallest settlers, resulting in juveniles with similar sizes-at-settlement regardless of when they arrived to the reef. Because recruitment strength and composition varied temporally, genetic markers (6 microsatellite and 1 mitochondrial loci) were used to determine if the genetic composition of monthly cohorts of settling larvae and juveniles also varies interannually, monthly, or across life stages. A lack of genetic structure suggested that S. partitus has a large effective population size and variation in ELHTs is not likely the result of successful spawning of a disproportionately small group of adults. As a whole, these results reveal processes associated with larval supply and post-settlement life that collectively shape juvenile demography.
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Ragheb, Erin Lorraine Hewett. "Intrabrood Dominance Hierarchies in Juvenile Red-Cockaded Woodpeckers: The Role of Early Social Environment On Post-Fledging Survival and Natal Dispersal." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77209.
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Competition among individuals over shared resources reveals asymmetries in quality resulting in the formation of dominance hierarchies. These hierarchies act as a mechanism for social selection by partitioning resources among group-living animals. The following chapters describe my dissertation research which investigates the factors contributing to competitive asymmetries among broodmates as well as the short- and long-term consequences of the early social environment for the cooperatively breeding red-cockaded woodpecker (Picoides borealis). My research revealed that fledgling red-cockaded woodpeckers form male-biased, linear dominance hierarchies. Among fledgling males,, high relative nestling condition strongly predicted fledgling dominance, and this condition–rank relationship persisted through independence. Male nestlings are slightly larger and heavier than females; however, the sexual size dimorphism in mass is only present in mixed-sex broods, suggesting that the subtle structural size advantage gives males a competitive advantage over their sisters. Conflict rates among siblings increased with decreasing targeted feeding rates, and dominant fledglings were able to secure more food from provisioning adults through scramble competition. First-year survival favored males over females and dominant males over subordinates. Females were more dispersive overall than males, and subordinate males were more likely to disperse than dominants. The social environment prior to fledging influenced male dispersal decisions and subordinates delayed dispersal in the spring in situations where all dominants died over the winter. The probability of delayed dispersal in females was higher for females raised without brood-mates in one of two populations included in a long-term demographic data analysis. The availability of breeding vacancies may explain the differences in female dispersal behavior according to social environment between these populations. This research contributes to a greater understanding of the relative contribution of intrinsic benefits versus extrinsic constraints as an influence on delayed dispersal decisions in red-cockaded woodpeckers. Inter- and intra-sexual social rank is correlated with individual access to natal food resources and the probability of first-year survival. The intrabrood variation in dispersal strategies driven by social rank is sufficient to regularly produce both dispersal strategies among males and provides additional support that delaying natal dispersal is the preferred strategy for males in this system.Ph. D.
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Collins, Alison Laureen. "Acoustic tagging effects on juvenile sockeye salmon swimming performance, growth, post-surgical wound healing, survival, and metabolic rate in freshwater and saltwater." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/40370.
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Juvenile Pacific salmon make large-scale migrations from natal freshwater rearing grounds to the Northern Pacific Ocean. To properly manage these species an understanding of their migration patterns and survival is necessary. Acoustic telemetry is an ideal tool used to study the migratory survival and behavior of juvenile salmonids. However, the assumption that tagged individuals behave similarly to non-tagged conspecifics in the freshwater and saltwater phases of their outmigration need to be validated as part of large-scale telemetry studies.
Consequently, a laboratory-based experiment was carried out to evaluate intracoelomic tagging effects on juvenile sockeye salmon (Oncorhynchus nerka) swimming performance, growth, post-surgical wound healing and survival in both freshwater and saltwater. A sub-set of fish were tagged with three differently sized tags and the response of the fish to tagging was compared to both a sham surgery and non-tagged treatment group. Fish with tag burdens greater than 6 – 8% body weight (BW; tag weighed in water) resulted in some freshwater mortality and decreased freshwater prolonged swimming performance. Fish implanted with larger tags had decreased survival in saltwater and poorer post-surgical wound healing than fish implanted with smaller tags. To minimize the negative effects of intracoelomic tagging, this research suggests that tag burdens should not exceed 6 – 8% BW in juvenile, hatchery-reared sockeye salmon.
Oxygen consumption rates were measured during the transition from freshwater to saltwater to investigate the hypothesis that intracoelomic tagging affects metabolic rate in juvenile salmonids during this period. Respirometer experiments during periods of rest and recovery post-swimming were used to assess metabolic rate in freshwater and saltwater for both tagged and non-tagged treatment groups. There was no effect of intracoelomic tagging on recovery metabolic rate post-swimming. However, tagging and salinity had an affect on resting metabolic rate; when fish transitioned from freshwater to 9 ppt saltwater, resting metabolic rate significantly increased. Resting metabolic rate at 9 ppt was elevated in comparison to the lowest resting metabolic rate recorded in saltwater at 28 ppt. However, both non-tagged and tagged fish were able to recover metabolically after transitioning to saltwater, indicated by similar metabolic rate values in saltwater as in freshwater.
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Lowther, Alan B. "Development, expansion, and evaluation of release-recapture survival models for Snake River juvenile salmonids, with new algorithms allowing time-dependent individual covariates /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/6378.
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Liberty, Aaron Jason. "An Evaluation of the Survival and Growth of Juvenile and Adult Freshwater Mussels at the Aquatic Wildlife Conservation Center (AWCC), Marion, Virginia." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/36193.
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The decline of many freshwater mussel populations in the United States has brought about the need for facilities in which mussels can be held for purposes of relocation, research, and propagation. The Aquatic Wildlife Conservation Center (AWCC) of the Virginia Department of Game and Inland Fisheries (VDGIF) serves as a freshwater mussel conservation facility in southwest Virginia. The goals of this study were: (1) to determine whether adult freshwater mussels could maintain energy reserves at AWCC (2) to determine whether adults could produce mature gametes at AWCC and (3) to establish suitable rearing conditions for juvenile mussels at the AWCC.
In fall 2002, four species of mussels, Villosa iris, V. vanuxemensis, Amblema plicata, and Pleurobema oviforme, served as surrogates for endangered species and were relocated to the AWCC. Three energy reserves (glycogen, protein, and lipid) were measured seasonally (fall 2002 to summer 2004) from mantle tissue and compared between AWCC specimens and those from their wild source populations. The gametogenic stage of each species was also compared to determine whether gametogenesis was occurring in captivity. In summer 2003, the first of two juvenile experiments tested the effects of three rates of water flow (1 L/min, 3 L/min, and 7 L/min) on the survival and growth of V. iris and Epioblasma capsaeformis reared in flow-through troughs. In summer 2004, round flow-through tanks were used to assess the effects of three sizes of substrate (fine sediment, fine sand, and coarse sand) and sampling frequency on the survival and growth of V. iris. Gut content analyses also were conducted at the end of each experiment to determine which algal species were being consumed.
Overall survival rates were as follows: A. plicata, 100 %; V. vanuxemensis, 86 %; V. iris, 79 %; P. oviforme (2002 collection), 53 %; and P. oviforme (2003 collection), 50 %. All energy reserves varied among seasons, but every species except P. oviforme (2003 collection) had levels higher than those in source populations at the end of this experiment. Glycogen appeared to be the best indicator of condition in these species, with protein also being important in the 2003 collection of P. oviforme. Mature gametes were found in all four captive species in 2003 and 2004, with lipids appearing to fuel gametogenesis. Additionally, gametogenesis was occurring earlier in captive long-term brooders than in the wild, possibly due to warmer water temperatures at AWCC.
The first juvenile experiment resulted in 15 % overall survival, with 1 L/min having the greatest survival (18 %), and the 3 L/min having the greatest growth (656 μm). In the second experiment, dishes left unsampled had significantly greater survival (40 %) (P<0.05) of juveniles than those which were sampled (27 %). The unsampled fine sand treatment had significantly greater survival than the other two unsampled treatments (52 %) (P<0.001). Sampled juveniles in fine sediment had the greatest growth (887 μm). Also, juveniles from Experiment 1 were consuming primarily Navicula, with Coelastrum and Chlorella consumed in greatest abundance in Experiment 2.
Results indicate that most adult mussels maintained energy reserves and produced mature gametes, and that juveniles of V. iris had good survival and growth. Only P. oviforme had survival rates lower than expected and did not appear to maintain condition at AWCC. Based on results of the species tested, environmental conditions at AWCC appear suitable for the survival of most adult and juvenile freshwater mussels.Master of Science
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Palm, Daniel. "Restoration of streams used for timberfloating : egg to fry survival, fry displacement, over-wintering and population density of juvenile brown trout (Salmo trutta L.) /." Umeå : Dept. of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/2007120.pdf.
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Gruber, Natasha W. "Population Dynamics and Movements of Translocated and Resident Greater Sage-Grouse on Anthro Mountain, Utah." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1417.
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Declining populations of greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse) have increased stakeholder concerns regarding the management and stability of the species range-wide. Numerous conservation strategies have been identified to restoring sage-grouse population declines to include species translocations. Translocations have been used for many different wildlife species to help sustain genetic heterogeneity, reestablish, and augment declining populations. In a recent translocation study, researchers identified the protocols used to successfully translocate sage-grouse to restore declining populations in Strawberry Valley, Utah. This translocation occurred in a high elevation basin buffered by geomorphic barriers. I evaluated these protocols for use in translocating sage-grouse to augment a declining population that inhabited Anthro Mountain in northwest Utah. Anthro Mountain is a high elevation mountain dominated by sagebrush (Artemisia spp.) void of geomorphic barriers. I compared annual production, survival (i.e., vital rates), habitat use, and movements of translocated birds and their progeny to the resident population. Lastly, I described the integration of translocated birds with resident birds and the overall efficacy of the translocation effort. I radio-collared and monitored 60 translocated female sage-grouse from Parker Mountain, Utah over a 2-year period (2009 and 2010) and compared their vital rates to 19 radio-marked resident sage-grouse. Adult survival was similar for resident and translocated birds, but higher for both groups in 2010 than in 2009. However, overall survival of both resident and translocated birds was lower than range-wide survival estimates. Nest success was slightly higher for resident birds than translocated birds but positively correlated to grass height for both groups. Chick survival was also slightly higher for resident birds than for translocated birds, and higher overall in 2010 than in 2009. Chick survival was positively correlated to grass cover for both groups. Translocated birds used similar habitats and exhibited migration behaviors similar to resident birds. From a methodology perspective, the translocations protocols were successful because the translocated birds quickly acclimated to the release area, and their survival and reproductive success were similar to the resident birds. The effect of the translocation on augmenting the local population was inconclusive.
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Daniels, Carly. "Optimisation of the rearing diets for early life stages of the European lobster, Homarus gammarus, to enhance growth, survival and health using biotic dietary supplements." Thesis, University of Plymouth, 2011. http://hdl.handle.net/10026.1/551.
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The series of experiments that comprises this thesis consider the use of prebiotics and probiotics to improve success in European lobster Homarus gammarus culture. Research was conducted at the National Lobster Hatchery and The University of Plymouth, UK between April 2007 and March 2010. Great potential was revealed for the application of biotics as dietary supplements in the culture of larval and juvenile H. gammarus. Specific biotics, namely; prebiotic mannon oligosaccharide (MOS) and probiotic Sanolife® (Bacillus spp.) were revealed to increase growth and survival during the culture of early lobster life stages. Lobsters that showed enhanced development and/or survival were found to possess improved feed conversion, immune status and/or stress tolerance. Furthermore it was found that biotic fed lobsters displayed shifts in gastrointestinal (GI) microbiology and enhanced physical GI structures, which may account for improved feed conversion and consequently growth. The work presented thus demonstrates that by making positive changes in GI structure and bacterial community composition combined with influencing immune status culture success can be positively enhanced through the biotic supplementation of diets. However, it must be considered that the outcome of dietary biotic supplementation is heavily influenced by the situation in question.
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Mathias, Karin L. "Growth and survival of juvenile sockeye salmon (Oncorhynchus nerka) in three Northwestern British Columbia lakes - an evaluation of an International Stock Enhancement Program." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0002/MQ59547.pdf.
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Lisboa, Ângela Maria Patrício. "A pobreza, um livre trânsito para a delinquência juvenil?" Doctoral thesis, Instituto Superior de Economia e Gestão, 2008. http://hdl.handle.net/10400.5/757.
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Doutoramento em Sociologia Económica e das OrganizaçõesEsta Dissertação de Doutoramento tem por objectivo, aprofundar o conhecimento sociológico relativo à problemática da delinquência juvenil. Interessa-nos analisar os jovens oriundos de meios desfavorecidos, e que à data deste trabalho, se encontravam internados nos Centros Educativos de Vila Fernando e Padre António de Oliveira. Procuraremos compreender, se entre os diversos mecanismos sociais, a pobreza pode potenciar a emergência de comportamentos delinquentes entre este tipo de jovens. Iremos estudar, ainda, as suas trajectórias, expectativas, aspirações e projectos de vida. E tratando-se de jovens institucionalizados, fará todo o sentido saber em que medida o internamento num Centro Educativo contribuiu para melhorar as suas competências e modificar o seu comportamento.
This doctoral thesis aims to deepen the sociological understanding of the problematic of juvenile delinquency. It focuses on young people from underprivileged backgrounds who were, at the time of fieldwork, institutionalized in the Vila Fernando and Padre António de Oliveira Educational Centres. It investigates if, among several social mechanisms, poverty may contribute to the emergence of delinquent behaviours in these youth groups. It also studies the individual trajectories, expectations, aspirations and life projects of the young people researched. Finally, and considering this is a study of institutionalized youth, it analyzes to what extent institutionalization in an Educational Centre has contributed to increase skills and modify behaviours.
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Fourney, Francesca. "Natural vs. Anthropogenic Sedimentation: Does Reducing a Local Stressor Increase Coral Resilience to Climate Change?" NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/400.
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Corals face serious worldwide population declines due to global climate change in combination with direct anthropogenic impacts. Global climate change is difficult to manage locally, but policy makers can regulate the magnitude of local stressors affecting reefs. The objective of this experiment is to investigate if reducing sedimentation will enable reef corals to better endure global climate change. It has been shown that some coral species can handle climate change stress when provided with additional energy resources. Here I tested if the capacity of corals to cope with climate change can be improved when their ability to feed and photosynthesize was not compromised by increased sedimentation. Sedimentation can impede coral feeding and their ability to photosynthesize due to direct polyp blocking and increased turbidity, which reduces light availability. To evaluate the potential of enhancing coral ability to tolerate climate change by reducing a local stressor, I examined the survival and growth of brooding coral Porites astreoides juveniles when exposed to ambient and elevated water temperatures under differing sedimentation rates. I also assessed if sediment composition has significant impacts on these results. I used sediment from a reef and sediment from a boat basin within a port to mimic natural and anthropogenic sediment types and processes (e.g. dredging). Experiments were conducted to quantitatively assess the synergistic effects of sediment concentration and composition, along with increased temperature on the survival and growth of juvenile P. astreoides. The most detrimental effects were observed with anthropogenic sediment, when both sediment concentration and water temperatures were high. However, increased natural reef sediment was found to be beneficial to juvenile corals. More interestingly, I found that corals capacity to deal with higher temperatures is improved when anthropogenic sedimentation is maintained at minimal levels and turbidity resulting from sedimentation was low. Therefore, this information will aid managers in making decisions that regulate dredging and construction activities to minimize sedimentation, which will contribute to increase coral survival under climate change.
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Mitchell, Aimee Marie. "The effects of release techniques on the reproductive performance and post-fledging juvenile survival of captive-bred Western Burrowing Owls (Athene cunicularia hypugaea) in the Nicola Valley, British Columbia." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/893.
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Reintroduction of captive-bred Western Burrowing Owls (Athene cunicularia hypugaea) in the Nicola Valley, British Columbia, has had limited success in increasing the local breeding population. Traditionally, yearling captive-hatched Burrowing Owls that were paired and released into artificial burrows in the field, held overnight, and provided with supplemental food throughout the breeding season (hard release) have had high post-release dispersal and mortality. In 2005 and 2006, I used an alternative soft-release technique to test for an improvement upon the hard-release technique. The soft release followed the same procedure as the traditional hard release but also included enclosures around burrow entrances to contain the owls for a 2-week period in the field prior to release. I compared immediate post-release dispersal, seasonal survival, and reproductive success for 37 hard-released and 30 soft-released pairs. I radio-tagged 39 of these released owls in order to accurately monitor their activities, regardless of whether they remained at release sites or dispersed. The soft-release technique led to 20% more owls remaining at the release sites, 14% more owls surviving the breeding season, and 20% more owl pairs fledging juveniles.
In addition to investigating adult survival and reproductive success, I examined post-fledging juvenile survival, local recruitment, and habitat use, and adult prey consumption behaviour in order to assess the potential of these aspects to limit the success of the reintroduction. Survival and local recruitment rates of the juveniles of captive-bred adults released with two different techniques were similar to that of juveniles of wild adults in the same study area or in other parts of the Burrowing Owl's range. Juvenile habitat-selection analyses identified the importance of rangeland, and comparisons of prey consumption revealed the rapid development of foraging abilities by captive-bred Burrowing Owls. I concluded that these aspects of the owl's ecology were not negatively affected by a captive upbringing, and therefore not likely limiting the success of the reintroduction.
Overall, the use of an enclosure-based soft-release technique addresses major limitations to the success of releases, and shows promise for increasing the breeding population in this region. This approach can also be applied to recovery efforts throughout the Burrowing Owls' range, and provide guidelines for other species' reintroduction programs.
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Vitz, Andrew C. "Survivorship, habitat use, and movements for two species of mature forest birds." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1211988466.
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Kuba, Alyson. "Transgenerational Effects of Thermal Stress: Impacts On and Beyond Coral Reproduction." NSUWorks, 2016. http://nsuworks.nova.edu/occ_stuetd/429.
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Ocean warming causes stress to corals and records reveal that periods of thermal stress are increasing in frequency and severity. Previous studies show that thermal stress negatively impacts the reproductive output of corals. However, the transgenerational impacts of coral bleaching have never been quantified. As a consequence, it is unclear how ocean warming may alter population dynamics due to effects on reproduction and recruitment. This study quantified the transgenerational impacts of thermal stress in Montastraea cavernosa. To assess transgenerational effects of temperature stress during gametogenesis, colonies were exposed to elevated temperature for two weeks four months prior to spawning, and then returned to the reef. At spawning, eggs were collected to measure egg diameter and eggs from stressed females were significantly smaller than those from unstressed females. Then gametes from temperature stressed and unstressed corals were combined to create four fertilization crosses: unstressed female and male, unstressed female with stressed male, stressed female with unstressed male, and stressed female and male. Larvae and juveniles from each cross were kept at ambient (29°C) and elevated (31°C) temperatures. Larvae originating from stressed gametes overall had lower survival, but the separate effects of the male and female revealed paternal transgenerational acclimation and negative maternal effects. There were no transgenerational effects on initial size of juveniles, but elevated temperature in the larval stage decreased initial size. The transgenerational effects on juvenile survival were negative parental effects. Juvenile growth rate was only affected by adult male exposure to thermal stress. Juveniles originating from a thermally stressed male had higher growth rates. The timing of the thermal stress, which was during oogenesis and before spermatogenesis, most likely explains why negative effects were observed from the female and positive effects from the male. These results demonstrate that temperature stress has varying transgenerational effects.
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Mayfield, Stephen. "Assessment of predation by the West Coast rock lobster (Jasus lalandii) : relationships among growth rate, diet and benthic community composition, with implications for the survival of juvenile abalone (Haliotis midae)." Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/9603.
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Bibliography: leaves 195-213.This thesis focused on two aspects of predation by the West Coast rock lobster (Jasus lalandii). These were (1) the problem of slow growth currently observed in adult male rock lobsters and the putative link between growth rate and food availability, and (2) the influence of rock-lobster predation on the benthos, but more specifically on sea urchins and juvenile abalone.
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Box, Stephen J. "The dynamics of macroalgae on a Caribbean coral reef : modelling the availability of settlement space and dominant algae and evaluating the effect of macroalgal competition on the growth and survival of juvenile corals." Thesis, University of Exeter, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479412.
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Bellamy, Robyn Lyle, and robyn bellamy@flinders edu au. "LIFE HISTORY AND CHEMOSENSORY COMMUNICATION IN THE SOCIAL AUSTRALIAN LIZARD, EGERNIA WHITII." Flinders University. Biological Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20070514.163902.
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ABSTRACT
Social relationships, habitat utilisation and life history characteristics provide a framework which enables the survival of populations in fluctuating ecological conditions. An understanding of behavioural ecology is critical to the implementation of Natural Resource Management strategies if they are to succeed in their conservation efforts during the emergence of climate change. Egernia whitii from Wedge Island in the Spencer Gulf of South Australia were used as a model system to investigate the interaction of life history traits, scat piling behaviour and chemosensory communication in social lizards.
Juveniles typically took ¡Ý 3 years to reach sexual maturity and the results of skeletochronological studies suggested longevity of ¡Ý 13 years. Combined with a mean litter size of 2.2, a pregnancy rate estimated at 75% of eligible females during short-term studies, and highly stable groups, this information suggests several life history features.
Prolonged juvenile development and adult longevity may be prerequisite to the development of parental care. Parental care may, in turn, be the determining factor that facilitates the formation of small family groups. In E. whitii parental care takes the form of foetal and neonatal provisioning and tolerance of juveniles by small family or social groups within established resource areas. Presumably, resident juveniles also benefit from adult territorialism. Research on birds suggests that low adult mortality predisposes cooperative breeding or social grouping in birds, and life history traits and ecological factors appear to act together to facilitate cooperative systems.
E. whitii practice scat piling both individually and in small groups. Social benefits arising from signalling could confer both cooperative and competitive benefits. Permanent territorial markers have the potential to benefit conspecifics, congenerics and other species. The high incidence of a skink species (E. whitii) refuging with a gecko species (N. milii) on Wedge Island provides an example of interspecific cooperation. The diurnal refuge of the nocturnal gecko is a useful transient shelter for the diurnal skink. Scat piling may release a species ¡®signature¡¯ for each group that allows mutual recognition.
Scat piling also facilitates intraspecific scent marking by individual members, which has the potential to indicate relatedness, or social or sexual status within the group. The discovery of cloacal scent marking activity is new to the Egernia genus. E. Whitii differentiate between
their own scats, and conspecific and congeneric scats. They scent mark at the site of conspecific scats, and males and females differ in their response to scent cues over time. Scat piling has the potential to make information concerning the social environment available to dispersing transient and potential immigrant conspecifics, enabling settlement choices to be made.
This thesis explores some of the behavioural strategies employed by E. whitii to reduce risks to individuals within groups and between groups. Scents eliciting a range of behavioural responses relevant to the formation of adaptive social groupings, reproductive activity, and juvenile protection until maturity and dispersal are likely to be present in this species. Tests confirming chemosensory cues that differentiate sex, kin and age would be an interesting addition to current knowledge. The interaction of delayed maturity, parental care, sociality, chemosensory communication and scat piling highlights the sophistication of this species¡¯ behaviour.
An alternative method for permanently marking lizards was developed. Persistence, reliability and individual discrimination were demonstrated using photographic identification and the method was shown to be reliable for broad-scale application by researchers. Naturally occurring toe loss in the field provided a context against which to examine this alternative identification method and revealed the need to further investigate the consequences of routine toe clipping, as this practice appears to diminish survivorship.
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Bartlett, Lucy. "Dynamics and Survival of Coral and Octocoral Juveniles following Disturbance on Patch Reefs of the Florida Reef Tract." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5342.
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Over the past several decades, rapid decline in adult stony-coral (comprising the Orders Scleractinia and Anthomedusae, specifically Family Milleporidae) cover has occurred concurrent with an increase in adult octocoral (Octocorallia/gorgonian) cover along the Florida Reef Tract. In January 2010, the Florida Keys experienced extremely cold air and water temperatures, below the lethal threshold for many reef organisms including corals. Very high stony-coral mortality occurred on some patch reefs. The newly-available space created by this disturbance event provided the opportunity for recruitment and settlement of new coral larvae and other reef organisms.
The goal of this study was to examine post-disturbance recruitment and survival of juvenile stony corals and octocorals on patch reefs in the Middle and Upper Florida Reef Tract. Permanent quadrats were established at eight patch-reef sites. Stony-coral and octocoral juveniles, visible to the naked eye and having a maximum 4 cm diameter for stony corals or 4 cm height for octocorals, were identified, measured, and photographed to track each colony through spring and fall for two years. Juvenile densities increased significantly over that time; octocoral density increased with higher significance (p
Opportunistic and/or hardy organisms are re-populating patch-reef sites, whereas slower growing, massive stony-coral species are declining. When a reef environment is plagued with chronic stressors, such as terrestrial runoff, overfishing, high temperature fluctuations and turbidity, the succession process may be inhibited following acute disturbances such as cold-water events. Patch reefs of the Florida Reef Tract now appear to be caught in a perpetually disturbed state, which supports opportunistic and hardy taxa and inhibits recovery of slower-growing climax taxa that dominated until the past few decades.
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Peterson, Kylie, and n/a. "Environmental impacts on spawning and survival of fish larvae and juveniles in an upland river system of the Murray-Darling Basin." University of Canberra. Resource, Environmental & Heritage Sciences, 2003. http://erl.canberra.edu.au./public/adt-AUC20060713.121419.
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Six rivers within the upper Mumbidgee catchment were sampled for larval and juvenile
fish. The rivers represented both regulated and unregulated flow regimes and varied widely in
size. There was wide variation in the larval fish communities supported by each river, both in
terms of the species diversity and total abundance of fish sampled. The highly regulated reach
of the Mumbidgee River sampled during this study had the highest numbers of native
species and native individuals of any river sampled.
In the two rivers selected for further study, the Murmmbidgee and Goodradigbee, there was a
high level of inter-annual consistency in the species composition within the reaches sampled,
despite considerable change in the temperature and flow regimes of both rivers. This indicates
that at least some spawning of those species sampled may occur each year, regardless of
environmental conditions. Estimates of the relative abundance of each species sampled
changed markedly between years, and it is argued, on the basis of growth information
contained in the otoliths, that differential survival of larvae and juveniles was largely
responsible for this shift in relative abundance.
Otolith microstructure provided information on the date of spawning and early growth patterns
of all species sampled in the upper Mumumbidgee catchment. In addition to determining the
age and thus 'birth-date' of an individual, the effect of a particular event or series of events has
on growth, and subsequent survival, is permanently recorded in the otolith microstructure.
This enables accurate back-calculation and correlation to management actions or natural
events. No other research tool has this ability to retrospectively assess, on a daily basis, the
impacts of management actions on condition and subsequent survival of fish larvae.
Species sampled could be separated into three groups based on spawning requirements; those
linked with flow, those linked with temperature and generalist species that appear to have river
independent cues, such as photoperiod or moon phase.
Patterns in growth rate during the early life history stages enabled quantification of the
consequences of variation in environmental conditions on the survival and recruitment of
various species. Growth was not always highly correlated with water temperature, in fact, for
mountain galaxias, high temperatures appear to negatively affect larval condition and
subsequent survival. Conversely, carp exhibited a strategy more consistent with common
perceptions, with growth and survival increasing with increasing temperature.
The study uncovered spawning and growth patterns that were unexpected. Age analysis of
western carp gudgeon demonstrated that they had undertaken a mid-winter spawning, when
the water temperature in the main channel was far lower than that at which spawning was
previously recorded for this species. Redfin perch from the unregulated Goodradigbee River
exhibited growth rates exceeding the published upper limits for this and other closely related
species. This growth could not be correlated with either temperature or flow, indicating that
there are additional factors that dominate growth rates of redfin perch in the Goodradigbee
River.
The proportion and abundance of native species alone is not necessarily indicative of a
'healthy' or pristine system; some native species may be positively affected by river
regulation, at least as juveniles. Comparison of the current larval fish community with likely
pre-European fish communities does provide an indication of change to the system. The
results of this study suggest that larval fish growth rates can be strongly influenced by
environmental conditions, thus providing a powerful tool for monitoring future change and the
factors which cause it.
This study has demonstrated the value of larval and juvenile fish age and growth information,
derived from otolith microstructure techniques, for many aspects of river management.
Current river management priorities for which these techniques provide unique information
include the determination of environmental flow regimes and the control of undesirable exotic
species such as carp.
49
Casey, Paul Charles. "Effects of photoperiod and temperature on growth and survival of young-of-the-year laboratory reared winter flounder (Pleuronectes americanus) juveniles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0027/MQ62118.pdf.
Full text
50
Besen, Kayane Pereira. "Luteína como fonte de carotenoide natural: efeito no desempenho zootécnico e pigmentação da pele de juvenis de kinguios." Universidade do Estado de Santa Catarina, 2017. http://tede.udesc.br/handle/handle/2564.
Full textAbstract:
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PROMOP
The objective of this study was evaluating the efficiency of lutein supplementation on the performance and deposition of skin carotenoids in comparison to other sources for young kinguio. There forean evaluation was made with one controlled diet and four diets enriched with a quantity of 50mg kg-1 of the following pigments: lutein, astaxanthin, canthaxanthin and a combination of lutein + canthaxanthin (25mg kg-1 of each source). The the experiment was designed in an entire casual way with five treatments nd six repetitions. Two hundred and forty young kinguios weighting 1,07±0,57 g were used, they were kept in 30 tanks of 30 liters each, in which they stayed for 84 days. The fish was fed three times a day (8:30 am, 12:30 pm and 5 pm) in a manual way until apparent satiety. At the end of the experiment, the productive performance of the fish was determined based on zootechnical parameters: final weight, weight gain, food consumption, food conversion and survival. The analysis of pigment concentration at the integument was made throught the extraction of carotenoids of skin by using solvents. The solution obtained was filtered and submitted to reading using spectrophotometer with wavelength of 474 nm. The results were run through tests in order to verify the normality of errors and homoscedasticity, and were later analyzed by Parametric Variance Analysis (ANOVA). The data o performance were submitted to Tukey test and the pigments evaluated by the Duncan test, both with a meaningfulness level of 5%. Diets enriched with different carotenoid pigments did not influence on the growth of young Kinguios. In relation to survival, the supplementation of lutein presented higher values compared to the other treatments. The diets containing astaxanthin and canthaxanthin isolated led to increase of deposition of skin carotenoids of young kinguios when compared to treatment control, The lowest indexes were observed on the controlled diet and on the combined one (astaxanthin + canthaxanthin). On the fish fed with the diet containing lutein the skin carotenoid deposition was as effective as pure treatmens (astaxanthin and canthaxanthin), but it did not differ from neither control treatment nor combined treatment (canthaxanthin + lutein). The results suggest that the inclusion of carotenoids on the diet do not influence the growth of young kinguios and that when pigments are supplied separately they are more efficient on skin deposition than in a combined way. On the other hand, the supplementation with lutein enhanced the survival and promoted skind carotenoid deposition on young kinguios similarly to astaxanthin and canthaxanthin
O objetivo do presente estudo foi avaliar a eficiência da suplementação com luteína no desempenho e deposição de carotenoides na pele em comparação com outras fontes para juvenis de kinguio. Para isto foi avaliada uma dieta controle e quatro dietas enriquecidas com a quantidade de 50 mg kg-1 de pigmento: luteína, astaxantina, cantaxantina e combinação de luteína + cantaxantina (25 mg kg-1 proveniente de cada uma das fontes). O delineamento experimental foi inteiramente casualizado com cinco tratamentos e seis repetições. Foram utilizados 240 juvenis de kinguio com peso médio de 1,07±0,57 g, mantidos em 30 aquários de 30 L, ao qual foram cultivados por 84 dias. Os peixes foram alimentados três vezes ao dia (08:30; 12:30; 17:00) de forma manual até saciedade aparente. No final do experimento o desempenho produtivo dos peixes foi determinado com base nos parâmetros zootécnicos: peso final, ganho de peso, consumo de ração, conversão alimentar e sobrevivência. A análise da concentração de pigmentos no tegumento foi realizada através da extração de carotenoides na pele com o uso de solventes. A solução obtida foi filtrada e submetida a leitura em espectrofotômetro com comprimento de onda de 474 nm. Os resultados foram submetidos a testes para verificação da normalidade dos erros e homecedasticidade, sendo analisados posteriormente por meio de Análise de Variância Paramétrica (ANOVA). Os dados de desempenho foram submetidos ao teste de Tukey e os de pigmentação avaliados pelo teste de Duncan, ambos com nível de significância de 5%. Dietas enriquecidas com pigmentos carotenoides não influenciaram no crescimento de juvenis de kinguio. Em relação a sobrevivência, a suplementação com luteína apresentou valores superiores quando comparado aos demais tratamentos. A suplementação com astaxantina e cantaxantina aumentou a deposição de carotenoides na pele de juvenis de kinguios em relação ao tratamento controle. As menores taxas de pigmentação foram observadas no tratamento controle e combinado (cantanxatina + luteína). Nos peixes alimentados com a dieta contendo luteína a deposição de carotenoides foi tão eficiente quanto os tratamentos puros (astaxantina e cantaxantina), porém não diferiu do tratamento controle e do tratamento combinado (cantaxantina + luteína). Os resultados sugerem que a inclusão de carotenoides na dieta não afeta o crescimento e eficiência alimentar de juvenis de kinguio e que quando os pigmentos são fornecidos isoladamente são mais eficientes para serem depositados na pele do que de forma combinada (luteína + cantaxantina). Por outro lado, a suplementação com a luteína melhorou a sobrevivência e promoveu deposição de carotenoides na pele de juvenis de kinguio semelhante a astaxantina e a cantaxantina