UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item Fish Bioacoustics: From Basic Science to Policy(2024) Colbert, Benjamin; Bailey, Helen R; Popper, Arthur N; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Sound is critically important to fishes. Sound is used to communicate with conspecifics, to detect predators and prey, or to otherwise understand the world around them. Within this dissertation, I used a variety of methods to investigate multiple aspects of fish bioacoustics, including hearing, hearing in noise, the effects of anthropogenic sound, and the morphology of peripheral auditory structures.In Chapter 2, I reviewed international policy on the regulation of underwater sound and the effects of underwater sound on marine and aquatic habitats. I found that while there are increasing efforts to regulate underwater noise, the policy efforts are hampered by a lack of quantifiable metrics associated with impacts of anthropogenic sound in aquatic habitats and species. In Chapter 3, I measured auditory sensitivity of cyprinids using physiological methods. Auditory evoked potentials, a physiological measure of auditory sensitivity, have been used in previous studies to measure hearing sensitivity. However, while physiological methods have their place, they are measuring the sensitivity of the ear rather than the entirety of the auditory pathway. Therefore, I further measured hearing sensitivity of goldfish using behavioral methods that encompass the full auditory pathway. I found that physiological methods tend to underestimate actual hearing sensitivity at frequencies less than 1000 Hz. In Chapter 4, I investigated cyprinid hearing in noise, using both physiological and behavioral measures. Critical ratios were measured for four species of carp and goldfish using auditory evoked potentials. Behavioral methods were also used to measure critical ratios for goldfish. These data represent the first measurements of critical ratios for carp and the first comparative analysis between critical ratios measured using both physiology and behavior. I found that critical ratios for carp increase by as much as 25 dB between 300 Hz and 1500 Hz. I also found that physiological methods likely overestimate actual critical ratios for fish. In Chapter 5, I used micro-computed tomography (micro-CT) and three dimensional geometric morphometrics to compare the peripheral auditory structures of three species of carp. Three dimensional models of the tripus ossicle, the posterior most Weberian ossicle, and the sagitta otolith were created and the shape of these structures for silver carp (Hypophthalmichthys molitrix), bighead carp (H. noblis), and grass carp (Ctenopharyngodon idella) quantified and contrasted. I found that the shape of the tripus differed between the Hypophthalmichthys genus (i.e., silver and bighead carp) and Ctenopharyngodon (grass carp), demonstrating a possible phylogenetic signal in the shape of the Weberian ossicles. In Chapter 6, I studied the response of wild oyster toadfish (Opsanus tau) to underwater radiated noise from boats. I used passive acoustic monitoring to record toadfish vocalizations and vessel passages in the Chesapeake Bay, U.S.A. The effect of acute vessel passage was determined by comparing the number of calls after a vessel had passed to a control period. The effect of both aggregate vessel passage over an hour and environmental variables were investigated using generalized additive mixed models. I found that there was no significant effect on toadfish call rates from acute vessel passage but when vessel generated sound was higher over an hour long period (i.e., aggregate effect), call rate declined.Item Motion Reconstruction of Animal Groups: From Schooling Fish to Swarming Mosquitoes(2012) Butail, Sachit; Paley, Derek A; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The long-term goal of this research is to provide kinematic data for the design and validation of spatial models of collective behavior in animal groups. The specific research objective of this dissertation is to apply methods from nonlinear estimation and computer vision to construct multi-target tracking systems that process multi-view calibrated video to reconstruct the three-dimensional movement of animals in a group. We adapt the tracking systems for the study of two animal species: Danio aequipinnatus, a common species of schooling fish, and Anopheles gambiae, the most important vector of malaria in sub-Saharan Africa. Together these tracking systems span variability in target size on image, density, and movement. For tracking fish, we automatically initialize, predict, and reconstruct shape trajectories of multiple fish through occlusions. For mosquitoes, which appear appear as faded streaks on in-field footage, we provide methods to extract velocity information from the streaks, adaptively seek missing measurements, and resolve occlusions within a multi-hypothesis framework. In each case the research has yielded an unprecedented volume of trajectory data for subsequent analysis. We present kinematic data of fast-start response in fish schools and first-ever trajectories of wild mosquito swarming and mating events. The broader impact of this work is to advance the understanding of animal groups for the design of bio-inspired robotic systems, where, similar to the animal groups we study, the collective is able to perform tasks far beyond the capabilities of a single inexpensive robot.Item Hepatic Phase I and II Biotransformation Kinetics in Fishes: A Comparative Study(2006-12-04) Gonzalez, Jaime Fernando; Kane, Andrew S; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Eight finfish species were selected to test the similarities and dissimilarities on their phase I and II biotransformation capabilities using microsomal and cytosolic fractions of the liver. This research had three main objectives: 1) a comparison among the kinetics of the 8 species using model substrates, 2) farm-raised and laboratory-acclimated specimens of channel catfish, rainbow trout and tilapia were compared to determine similarities and differences in the biotransformation reactions, and 3) the same latter three species were tested to compare in vitro hepatic metabolism of albendazole, a drug that undergoes metabolic biotransformation mainly through hepatic phase I reactions. The comparison among the 8 finfish species showed that some of them had higher biotransformation capabilities than others. For most of the seven phase I- II reactions that were tested; rainbow trout, tilapia, channel catfish and Atlantic salmon had higher enzymatic efficiencies than those showed by of striped bass, hybrid striped bass and bluegill. Largemouth bass shared some enzymatic capabilities with one group or the other. The comparison between lab-acclimated and farm-raised specimens of tilapia, channel catfish and rainbow trout did not show biologically significant differences among the two groups of fish for the 3 species. All the values found for the kinetics of the reactions were within the ranges of the constitutive expression that has been reported for them and far below those found in other works when inducers (e.g. pollutants) of enzymatic reactions have been used. The phase I-mediated hepatic sulfoxidation of albendazole in tilapia, channel catfish and rainbow trout showed significant differences in Vmax and Km values among the three species. However, the catalytic efficacies of the reaction (Vmax/Km) in the 3 species transforming the parent compound were similar. In addition, albendazole induced EROD activity (2.6 fold) in in vivo dosed channel catfish. The results found in the present study showed that the catalytic efficiency of hepatic phase I-II enzymatic reactions varied among finfish species. Some of them may be categorized as "more efficient metabolizers" than others. This may have important implications in drug metabolism and residue depletion patterns.Item Relationship between fish intake, omega-3 fatty acids, mercury, and risk markers of coronary heart disease (NHANES 1999-2002)(2006-07-24) Smith, Kimberly Michele; Sahyoun, Nadine; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Item HARMFUL ALGAL BLOOM STRESSORS ALTER BEHAVIOR AND BRAIN ACTIVITY IN THE KILLIFISH, FUNDULUS HETEROCLITUS.(2005-04-15) Salierno, James D; Kane, Andrew S; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Harmful algal bloom (HAB) events are increasing in severity and frequency worldwide, and are known to severely impact fish populations. Impacts of HABs on fish, as well as other organisms, occur through toxic and physical stress. Behavioral and central nervous system (CNS) alterations can have direct consequences to the fitness and survival of individuals and populations. This study investigated and characterized alterations in social and swimming behaviors and brain activity in mummichog (Fundulus heteroclitus) exposed to HAB stressors. The mummichog is an ecologically important estuarine fish species exposed to a variety of HAB events in the wild. A behavioral analysis system was developed to study swimming and social behavior of fish and an immunohistochemistry technique was used to investigate alterations in neuronal activity as evidenced by c-Fos protein expression. HAB stressors included excitatory (domoic acid, brevetoxin) and inhibitory (saxitoxin) neurotoxic agents as well as direct exposures to the dinoflagellate Pfiesteria shumwayae and the diatom Chaetoceros concavicornis. P. shumwayae and C. concavicornis are HAB species that are known to induce mortality through physical trauma to fish. Brevetoxin exposure increased swimming and social behaviors whereas saxitoxin decreased these behaviors. The effects of saxitoxin on swimming and social behaviors were consistent with exposure to a fish anesthetic, MS-222. Similarly, it was found, through c-Fos expression, that the excitatory HAB neurotoxins brevetoxin and domoic acid, increased neuronal activity while saxitoxin decreased activity. Exposure to P. shumwayae and C. concavicornis, resulted in significant dose related increases in neuronal activity. Stressor-specific neuronal activity was greatest in the optic lobe, but was also found in the telencephalon with physical stressors increasing activity greater than chemical stressors. Results demonstrate that sublethal exposures to HAB neurotoxins can alter swimming and social behavior in mummichog and exposures to both neurotoxins and algae can alter neuronal activity. Alterations in brain activity, and knowledge of specific regions within the brain activated during stress, can provide insights into the control of fish behavior. Ultimately, HAB exposure related changes in neuronal signaling may alter behaviors, resulting in individual and population level alterations during HAB events.