Collisions with human-made structures are responsible for billions of bird deaths each year, resulting in ecological damage as well as regulatory and financial burdens to many industries. Acoustic warning signals can alert birds to obstacles in their flight paths in order to mitigate collisions, but these signals should be tailored to the sensory ecology of birds in flight. The effectiveness of various acoustic warning signals likely depends on the influence of background noise and the relative ability of various sound types to propagate within a landscape. I evaluated the ability of four sound signals to elicit collision-avoidant flight behaviors from birds released into a flight corridor containing a physical obstacle. I selected signals to test two frequency ranges (4-6 kHz or 6-8 kHz) and two temporal modulation patterns (broadband or frequency-modulated oscillating) to determine whether any particular combination of sound attributes elicited the strongest collision avoidance behaviors. I found that, relative to control flights, all sound treatments caused birds to maintain a greater distance from hazards and to adjust their flight trajectories before coming close to obstacles. There were no statistical differences among different sound treatments, but consistent trends within the data could suggest that the 4-6 kHz frequency-modulated oscillating signal elicited the strongest avoidance behaviors, followed by the 6-8 kHz broadband signal. I conclude that acoustic warning signals could be an effective avian collision deterrent in several contexts, and that the particular sound used in a warning signal may impact the detectability of the signal as well as the type of flight behaviors used to evade a collision. These findings can be used to design more effective warning signals and demonstrate the value of using behavioral data to assess collision risk.

Pacific halibut (Hippoglossus stenolepis) is a prohibited species for the U.S. West Coast Bottom Trawl Fishery and in the last decade, there has been a concentrated interest in the use of artificial illumination serving as a potential bycatch reduction device. Previous studies conducted off the coast of Oregon have found that the addition of green light-emitting diodes to the bridles of low-rise, cutback trawls greatly reduced the number of Pacific halibut caught. However, recent regulation changes now permit high-rise trawls, a gear configuration that fishes a very different volume of water than the previously permissible gear profile, in areas where they were once prohibited. No study to date has investigated the efficacy of artificial illumination to reduce Pacific halibut bycatch for this configuration. Field trials for this study were conducted off the Oregon Coast during August of 2022 and were designed to test a high-rise bottom trawl fitted with artificial illumination as a means to potentially reduce Pacific halibut bycatch. Length-dependent catch comparison and catch ratio analyses for trawls with and without illumination were conducted to determine if catches of Pacific halibut and three commercially important groundfish species differ between trawl treatments. Somatic fat content of Pacific halibut and physiological indicators of stress were also assessed via blood plasma samples to determine if there was a difference in physiological condition between Pacific halibut captured in either illuminated or non-illuminated tows. Additionally, an ethogram was constructed to quantify Pacific halibut behavior in response to an approaching high-rise trawl. Analyses were based on a simulated dataset based on previous flatfish behavioral studies and qualitative evidence from video and sonar recordings collected during field trials. While illuminated trawls caught fewer individuals than the non-illuminated trawls for all species in this study, the difference in catch was not statistically significant. Total catch size was found to have a significantly positive effect on glucose and lactate levels for Pacific halibut; however, no statistically significant differences between illuminated and non-illuminated tows were exhibited across all of the physiological parameters assessed in this study. I hypothesize that this lack of difference between treatment groups may have resulted from the change in gear configuration as Pacific halibut are more likely to rise off of the seafloor when responding to an approaching net. The higher headrope orientation used in a high-rise trawl configuration may be presenting too much of a challenge for halibut seeking to avoid the path of the trawl. It is also possible that the location of the lights was insufficient in triggering a change in avoidance behaviors. These findings are contrary to prior evidence and could have potential implications for the industry. Further investigation into Pacific halibut behavior is implored.

With species increasingly becoming imperiled due to anthropogenic activities, conservation practitioners are tasked with determining conservation priorities in order to make the best use of limited resources. The United States’ Endangered Species Act (ESA) has two listing statuses into which imperiled species are placed to receive protections: Threatened or Endangered. In the first chapter, our objective was to identify differences between Threatened and Endangered species beyond what is outlined in their ESA definitions. To our knowledge, this is the first study to compare listing status for species protected by the ESA on the basis of types and number of threats they face. For six broad-scale threats (habitat modification, overutilization, pollution, species-species interactions, environmental stochasticity, and demographic stochasticity), we investigated whether there is a difference in the number and types of threats which impact Threatened and Endangered species at the time of their listing. We found that Threatened (X̄ = 2.9, SD = 1.4) and Endangered (X̄ = 3.0, SD = 1.1) species were faced by a similar number of threats at their time of their listing. The only broad-scale threat that disproportionately impacted Endangered species more than Threatened species was demographic stochasticity; Endangered species were 1.9 times (95% CI = 1.4 -2.7) more likely to have this threat than Threatened species. We found four finer-scale demographic stochasticity threats (few individuals in one population, few individuals in multiple populations, lack of reproduction, and genetic loss) to be strong predictors of Endangered status. The similarities in the number and types of broad-scale threats faced by Threatened and Endangered species suggest that changes recently made to the ESA may be detrimental to the recovery efforts of future Threatened species. In the second chapter, our objective was to identify temporal trends in threats facing the four major phyla protected by the United States Endangered Species Act: angiosperms, arthropods, mollusks, and vertebrates. For 24 threat types, we created models to determine whether there was a linear, quadratic, or pseudo-threshold association between year and the probability that a phylum was listed with a given threat. We were able to identify temporal trends for 79% of the 96 possible threat-phylum combinations. We found that angiosperms had the highest peak probability of being listed with the greatest number of threats (N = 10), followed by mollusks (N = 8) and more distantly by arthropods (N = 4) and vertebrates (N = 2). We found that vertebrates had the greatest number of threats (N = 16) for which the year with their greatest probability of their being listed with a threat was their most recent year of listing. The other three phyla were similar to each other for this metric, mollusks having 12 and angiosperms and arthropods each having 11 threats peak in their most recent year of listing. We only identified one threat/phylum combination for which the maximum probability of their being listed with a threat was in their first year of listing (i.e., the threat has been consistently decreasing): authorized take impacting angiosperms. Overall, we believe our findings can be used to assist conservation efforts by identifying which threats have been decreasing or stable over time and which have been increasing that are in need of more attention.

Apalachicola Bay, an estuary located in northwest Florida, is likely to experience an increase in climate change and human-induced stressors, such as sea level rise and changes in freshwater inflow, in the future. A coupled hydrodynamic and food web modeling approach was used to simulate future scenarios of low and high river flow and sea level rise in Apalachicola Bay from 2020 to 2049 and demonstrate the range of temporal and spatial changes in water temperature, salinity, fisheries species populations and the broader food web. Concurrent with model development, a survey of Apalachicola Bay stakeholders was conducted to assess stakeholder knowledge and concerns regarding species and environmental changes within the system. Model results indicated an increase in annual average biomass for white shrimp and blue crab under low river flow scenarios and decrease in Gulf flounder and red drum biomass. High river flow scenarios resulted in an increase in annual average biomass for blue crab and red drum and decrease for white shrimp and Gulf flounder. For all modeled simulations, the largest differences in future environmental variables and species biomasses were between scenarios of low and high river flow, rather than low and high sea level rise. Stakeholders anticipated a future reduction in river flow and increase in sea level rise as both having some negative impacts to the Franklin County economy and stakeholders' personal interaction with the Apalachicola Bay ecosystem. The use of the ensemble modeling approach combined with the stakeholder survey highlights the use of multiple knowledge types to better understand abiotic and biotic changes in the estuarine system. Results provide insight on the synergistic effects of climate change and human-induced stressors on both the estuarine food web and human community of Apalachicola Bay.

Climate change has caused gradual changes within marine environments within the last couple decades and is expected to continue to impact these ecosystems. Changes to these ecosystems are anticipated to emerge as adverse effects reach the lowest and highest levels within trophic food webs. For example, these environmental changes may change the abundance and distribution of species within their current geographic range. In extreme cases, climate change has already resulted in range shifts of terrestrial and marine species. A need for bioindicator species has emerged, so that they may be used to indicate when climate change may impact marine communities and whether these communities are at risk. Bioindicators are useful in that they can be early indicators for adverse effects and be used to indicate to decision-makers that intervention is needed before adverse effects can spread to the rest of a particular ecosystem. Bioindicators that are responsive to environmental changes are ideal for use. Mytilus edulis (blue mussels) and Donax variabilis (coquina clams) are two species that could potentially have use as bioindicators for climate change. However, it is not known how responsive the physiological condition of these species is to environmental changes. Our thesis objectives were to determine whether differences in the physiological condition and recruitment rate of blue mussels and coquina clams on the Eastern Shore are connected to seasonal water quality changes in the northern hemisphere Spring-Summer months and (2) to determine whether there have been long-term (9 years) changes in mussel and clam physiology and interpret these changes in the context of climate change. We found some evidence for a connection between blue mussel and coquina clam physiology and recruitment and seasonal changes in water quality on the Eastern Shore. We also found that blue mussel and coquina clam physiology did exhibit long-term spatiotemporal changes through time on Virginia’s Barrier Islands. Blue mussels showed an early indication of a possible range shift to come. On southern barrier islands, blue mussels either had lower physiological condition and recruit counts or had higher rates of decline in these metrics. Coquina clams on the other hand, only showed evidence of declines in their physiological condition at Hog Island. This could be an early sign of the sublethal impacts stemming from gradual environmental changes and may signal that blue mussels and coquina clams will continue to decline in quality and quantity in these areas of Virginia’s Eastern Shore. Declines in blue mussel quality and quantity could be worrisome as they not only provide several economic and ecological services that benefit humans, but also are an important food source for the migrating shorebird species that use Virginia Barrier Islands as a refueling station. While worrisome, this response in blue mussels does indicate that this species may be responsive to environmental changes. With additional targeted, experimental research, a framework could be established that uses blue mussel physiology to further indicate impacts of specific environmental conditions on Virginia’s Eastern Shore ecosystems.

Thesis (M. Sc.)--University of Hong Kong, 1998. / Includes bibliographical references (leaf 292-301).

Prepared by the Arid Lands Information Center, Office of Arid Lands Studies, University of Arizona ; Mark Speece, compiler.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2014. / This thesis describes research that was conducted to investigate the causes of problems associated with the conservation of biodiversity in the Rwenzori Mountains National Park. The Rwenzori Mountains National Park faces conservation problems such as illegal harvesting of park resources, encroachment on the park boundary, and poor relationships between the local people and the managers of the park. These problems triggered this study because despite attempts such as intensifying park rules and regulations, implementing community-based conservation initiatives, and providing environmental education to local people to address the problems, they have persisted. This study was conducted on the premise that before a solution to these problems can be found, their nature and extent, and possible cause, need to be understood. The study involved: a) an extensive review of the relevant literature to identify factors that affect successful conservation of biodiversity in national parks in Africa, b) a critical analysis of the role of traditional ecological knowledge in the conservation of biodiversity in national parks in Africa, c) the development of a theoretical framework that could guide an investigation into problems associated with the conservation of biodiversity in national parks using the case study of the Rwenzori Mountains National Park, d) field investigations on how local people in the Rwenzori Mountains depended on the park, and what factors influence their dependence on the park, e) investigations into the environmental education provided to influence people to support conservation of the Rwenzori Mountains National park, f) the development of a generalisable scheme of factors that influence local people to illegally access and use the Rwenzori Mountains National Park, and g) preparation of a model that could serve as a framework for developing holistic community-based biodiversity conservation plans in a rural African context. The review of the literature was done through meta-data analysis of publications systematically selected from various web search engines on the internet. This was followed by field investigations. In order to have an in-depth and holistic understanding of the issues investigated, a mixed-methods approach to data collection was used. Semi-structured individual interviews were conducted with 163 randomly selected respondents from households in villages within 5 km of the Rwenzori Mountains National Park boundary. The study also involved content analysis of the formal environmental education syllabus documents, and documents on the Rwenzori Region Environmental Education Strategy and its implementation. It was found that factors responsible for both the success and failure of conserving biodiversity in national parks were socio-cultural and economic in nature. Although there was an increasing number of studies in the literature advocating for the consideration of traditional ecological knowledge in the conservation and management of national parks in Africa, most of those studies are theoretical, based on logical accounts and contestable historical reviews. In the Rwenzori Mountains, the local community illegally accessed the park to harvest 87 plant species, hunt 46 species of animals, and to conduct various activities. Illegal access to the park was influenced by a range of factors which interacted in myriad ways. Some of the factors (such as traditional beliefs) were situated inside mindsets of individuals and others (such as unpredicted weather conditions, lack of alternative means of livelihood and survival, commercial benefits, and bureaucratic procedures for legally accessing resources) were external to the individual. Previous attempts by the park staff to address illegal access to the park, and the associated resource harvesting problems, were judged to have been unsuccessful because the interventions did not target the underlying factors. This thesis argues for the use of holistic frameworks in investigating and addressing problems associated with the conservation of biodiversity in the Rwenzori Mountains National Park and has demonstrated how such frameworks could be developed. An adaptable model which could enhance more effective community-based biodiversity conservation has been proposed and recommended for future interventions in the management of national parks in a rural African context.

No description available.

Thesis (MA)--University of Montana, 2009. / Contents viewed on November 29, 2009. Title from author supplied metadata. Includes bibliographical references.