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Title: A THEORETICAL APPROACH TO ASSESSING ANNUAL ENERGY BALANCE IN GRAY WHALES (ESCHRICHTIUS ROBUSTUS).
Creator: Greenwald, Nathalie, Worthy, Graham, University of Central Florida
Abstract / Description: While direct measurements of energetic demands are nearly impossible to collect on large cetaceans, comprehensive bioenergetic models can give insights on such parameters by combining physiological and ecological knowledge. This model was developed to estimate necessary food intake of gray whales, Eschrichtius robustus, of the Eastern North Pacific stock. Field Metabolic Rates (FMR) for gray whales were first estimated based on various assumptions (e.g. volumetric representation of gray...
Show moreWhile direct measurements of energetic demands are nearly impossible to collect on large cetaceans, comprehensive bioenergetic models can give insights on such parameters by combining physiological and ecological knowledge. This model was developed to estimate necessary food intake of gray whales, Eschrichtius robustus, of the Eastern North Pacific stock. Field Metabolic Rates (FMR) for gray whales were first estimated based on various assumptions (e.g. volumetric representation of gray whales, extent of their feeding season, and blubber depth distribution) using morphometric data, energetic costs, and food assimilation according to age and gender specific requirements. Food intake rates for gray whales of varying maturity and gender were then estimated based on FMR and caloric value of prey and compared to food intake rates of previous studies. Monte Carlo simulations and sensitivity analysis were performed to assess the model's predictions compared to observed field data from previous studies. Predicted average food intakes for adult male, pregnant/ lactating female, and immature whales were 475 ± 300, 525 ± 300 and 600 ± 300 kg d-1. Estimated blubber depths resulting from these food intakes were comparable to field data obtained from whaling data. Sensitivity analysis indicated food intake, from all parameters, as having the highest impact on the percent change in ending mass from a simulation. These food intake estimates are similar to those found in a previous study and fall within the range of food intake per body mass observed in other species of cetaceans. Though thermoregulation can be a factor in some cetaceans, it appears not to be an additional cost for gray whales as the present model's predicted lower critical temperatures for the whales (TLC) were below ambient temperatures. With temperatures increasing in the Bering Sea, the main prey of gray whales, ampeliscid amphipods, could be adversely affected, possibly resulting in increased food shortages leading to a surge in gray whale strandings.
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Date Issued: 2005
Identifier: CFE0000443, ucf:46375
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000443

Title: STABLE ISOTOPE TURNOVER RATES AND DIET-TISSUE DISCRIMINATION IN THE SKIN OF WEST INDIAN MANATEES: IMPLICATIONS FOR EVALUATING THEIR FEEDING ECOLOGY AND HABITAT USE.
Creator: Alves, Christy, Worthy, Graham, University of Central Florida
Abstract / Description: The West Indian manatee (Trichechus manatus) is an herbivorous marine mammal that occupies freshwater, estuarine, and marine habitats. Despite being considered endangered, relatively little is known about the feeding ecology of either of the two recognized subspecies, the Florida manatee (T.m. latirostris) and Caribbean or Antillean manatee (T.m. manatus). A better understanding of their respective feeding preferences and habitat use is essential to establish criteria on which conservation...
Show moreThe West Indian manatee (Trichechus manatus) is an herbivorous marine mammal that occupies freshwater, estuarine, and marine habitats. Despite being considered endangered, relatively little is known about the feeding ecology of either of the two recognized subspecies, the Florida manatee (T.m. latirostris) and Caribbean or Antillean manatee (T.m. manatus). A better understanding of their respective feeding preferences and habitat use is essential to establish criteria on which conservation plans can be based. The present study expands on previous work on manatee feeding ecology by both assessing the application of stable isotope analysis to manatee tissue and providing critical baseline parameters for accurate isotopic data interpretation. The present study was the first to calculate stable isotope turnover rate in the skin of any marine mammal. Stable carbon and nitrogen isotope ratios were examined over a period of more than one year in the epidermis of rescued Florida manatees that were transitioning from a diet of aquatic forage to terrestrial forage (lettuce) in captivity. Mean half-life for 13C turnover in manatee epidermis was 55 days and mean half-life for 15N turnover was 42 days. Due to these slow turnover rates, carbon and nitrogen stable isotope analysis in manatee epidermis is useful in summarizing average dietary intake over a long period of time rather than assessing recent diet. In addition to turnover rate, a diet-tissue discrimination value of 2.8‰ for 13C was calculated for long-term captive manatees on a lettuce diet. Turnover and diet-tissue discrimination results were subsequently used to interpret carbon and nitrogen stable isotope data in epidermis samples collected from free-ranging manatees in Florida, Belize, and Puerto Rico. This study was the first application of stable isotope analysis to Antillean manatees. Regional differences in stable isotope ratios in manatee skin were consistent with ratios in plant samples collected in those regions. Signatures in the skin of manatees sampled in Belize and Puerto Rico indicated a diet composed mainly of seagrasses, whereas those of Florida manatees exhibited greater variation. Mixing model results indicated manatees sampled from Crystal River and Homosassa Springs had an overall average intake of primarily freshwater vegetation whereas manatees sampled from Big Bend Power Plant, Ten Thousand Islands, and Warm Mineral Springs fed primarily on seagrasses. Possible diet-tissue discrimination values for 15N ranged from 1.0 to 1.5‰. Stable isotope analysis can be successfully applied to interpret manatee feeding behavior over a long period of time, specifically the use of freshwater vegetation vs. seagrasses, and can aid in improving conservation efforts.
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Date Issued: 2007
Identifier: CFE0001599, ucf:47161
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001599

Title: EFFECTS OF FOOD DEPRIVATION ON BLOOD LIPID CONCENTRATION AND COMPOSITON IN STELLER SEA LIONS (EUMETOPIAS JUBATUS).
Creator: Berman, Michelle, Worthy, Graham, University of Central Florida
Abstract / Description: Steller sea lions, the largest Otariid, fast during their breeding season; during this time they refrain from ingesting food for a period of 12-43 days. Fasting, while undertaking an extremely energetically demanding activity (breeding and pupping), requires specific physiological adaptations. This study examined the physiological response to fasting of two age classes, juveniles and sub-adults, during the breeding and non-breeding seasons to determine how these animals utilize lipids and the...
Show moreSteller sea lions, the largest Otariid, fast during their breeding season; during this time they refrain from ingesting food for a period of 12-43 days. Fasting, while undertaking an extremely energetically demanding activity (breeding and pupping), requires specific physiological adaptations. This study examined the physiological response to fasting of two age classes, juveniles and sub-adults, during the breeding and non-breeding seasons to determine how these animals utilize lipids and the pattern of fatty acid mobilization from lipid stores during fasting. Four juveniles and 5 sub-adults were fasted for one and two weeks, respectively, and blood samples were collected approximately every 3 days for lipid analysis. The concentrations of plasma non-esterified fatty acids (NEFA) were analyzed spectrophotometrically. Serum fatty acid composition was analyzed using gas chromatography (GC) and their individual weight percent (wt %) were correlated with their peak retention time and calculated using the area under each peak. Sixty-nine fatty acids were quantified from each sample. However, only those with concentrations above 0.2 wt. % were included in the analysis. Sub-adult samples were grouped on a percent mass loss basis (0%, 7-8% and 15% mass loss) to facilitate comparison with the juveniles. These data represent the total lipid fatty acid composition of each blood sample. Relative lipid concentration was calculated by multiplying the total lipid fatty acid compositional analysis (wt %) by the NEFA concentrations measured in that respective blood sample. Plasma NEFA concentrations in juvenile Steller sea lions ranged from 1.2 ¡Ó 0.51 mM to 3.7 „b 0.69 during fasting and was within the range of fasting phocids. Concentrations of NEFAs in the sub-adult Steller sea lions ranged from 1.00 mM up to 9.70 mM and were generally higher than fasting phocids. The wt % of only one fatty acid (20:0) was significantly different between the breeding and non-breeding season in fasting juveniles. However, the wt % of seven fatty acids changed significantly during fasting in the juveniles and five of these were most significant in separating the beginning and end of the fasts using principal components analysis. In contrast, the wt % of 10 fatty acids were significantly different during the breeding and non-breeding season fasts of the sub-adults. Additionally, the wt % of 10 fatty acids changed significantly during fasting in the sub-adults and four of these (16:1n-7, 18:2n-6, 20:0, and 20:1n-9) were most significant in separating the beginning and end of the fasts using principal components analysis. These trends reveal the physiological differences between the juvenile and sub-adult Steller sea lions and suggest that the sub-adults may be better physiologically and metabolically adapted to fast than the juveniles in this study.
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Date Issued: 2005
Identifier: CFE0000621, ucf:46526
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000621

Title: A THEORETICAL APPROACH TO ASSESSING ANNUAL ENERGY BALANCE IN GRAY WHALES (ESCHRICHTIUS ROBUSTUS).
Creator: Greenwald, Nathalie, Worthy, Graham, University of Central Florida
Abstract / Description: While direct measurements of energetic demands are nearly impossible to collect on large cetaceans, comprehensive bioenergetic models can give insights on such parameters by combining physiological and ecological knowledge. This model was developed to estimate necessary food intake of gray whales, Eschrichtius robustus, of the Eastern North Pacific stock. Field Metabolic Rates (FMR) for gray whales were first estimated based on various assumptions (e.g. volumetric representation of gray...
Show moreWhile direct measurements of energetic demands are nearly impossible to collect on large cetaceans, comprehensive bioenergetic models can give insights on such parameters by combining physiological and ecological knowledge. This model was developed to estimate necessary food intake of gray whales, Eschrichtius robustus, of the Eastern North Pacific stock. Field Metabolic Rates (FMR) for gray whales were first estimated based on various assumptions (e.g. volumetric representation of gray whales, extent of their feeding season, and blubber depth distribution) using morphometric data, energetic costs, and food assimilation according to age and gender specific requirements. Food intake rates for gray whales of varying maturity and gender were then estimated based on FMR and caloric value of prey and compared to food intake rates of previous studies. Monte Carlo simulations and sensitivity analysis were performed to assess the model's predictions compared to observed field data from previous studies. Predicted average food intakes for adult male, pregnant/ lactating female, and immature whales were 475 ± 300, 525 ± 300 and 600 ± 300 kg d-1, respectively. Estimated blubber depths resulting from these food intakes were comparable to field data obtained from whaling data. Sensitivity analysis indicated food intake, from all parameters, as having the highest impact on the percent change in ending mass from a simulation. These food intake estimates are similar to those found in a previous study and fall within the range of food intake per body mass observed in other species of cetaceans. Though thermoregulation can be a factor in some cetaceans, it appears not to be an additional cost for gray whales as the present model's predicted lower critical temperatures for the whales (TLC) were below ambient temperatures. With temperatures increasing in the Bering Sea, the main prey of gray whales, ampeliscid amphipods, could be adversely affected, possibly resulting in increased food shortages leading to a surge in gray whale strandings.
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Date Issued: 2005
Identifier: CFE0000560, ucf:46442
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000560

Title: THE USE OF STABLE ISOTOPES TO ASSESS POTENTIAL EFFECTS OF ALGAL BLOOMS ON SEAGRASS AND MACROALGAE COMMUNITIES IN THE INDIAN RIVER LAGOON, FLORIDA.
Creator: Azcona, Alexandra, Worthy, Graham, University of Central Florida
Abstract / Description: Algal blooms have caused significant losses in seagrass and macroalgae in the Indian River Lagoon, FL. To gain an understanding of these effects, samples of Gracilaria sp., Halodule wrightii, pinfish, and white mullet were taken throughout October and November of 2013. Samples from 2001 of Gracilaria sp., Halodule wrightii, Syringodium filiforme, Thalassia testudinum, pinfish, spotted seatrout, and white mullet were also obtained. Stable isotope data were obtained from these samples and...
Show moreAlgal blooms have caused significant losses in seagrass and macroalgae in the Indian River Lagoon, FL. To gain an understanding of these effects, samples of Gracilaria sp., Halodule wrightii, pinfish, and white mullet were taken throughout October and November of 2013. Samples from 2001 of Gracilaria sp., Halodule wrightii, Syringodium filiforme, Thalassia testudinum, pinfish, spotted seatrout, and white mullet were also obtained. Stable isotope data were obtained from these samples and compared by year and species. Halodule wrightii and pinfish had a significantly larger 2013 delta C13 values. Halodule wrightii also displayed lower total %C and total %N averages for 2013 when compared to 2001 data. These results may indicate a link between Halodule wrightii and pinfish, with pinfish consuming organisms that use Halodule wrightii as their source of nutrients. The location of collections also seemed to play a role in stable isotope values, as indicated by samples of Halodule wrightii.
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Date Issued: 2014
Identifier: CFH0004552, ucf:45200
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004552

Title: USING STABLE ISOTOPES TO ASSESS THE POPULATION STRUCTURE AND FEEDING ECOLOGY OF NORTH PACIFIC HUMPBACK WHALES (MEGAPTERA NOVAEANGLIAE).
Creator: Witteveen, Briana, Worthy, Graham, University of Central Florida
Abstract / Description: The North Pacific humpback whale (Megaptera novaeangliae) is a wide-ranging baleen whale species with a complex life history and population structure. As seasonal migrants, humpback whales are known to inhabit cooler, high-latitude waters when foraging and low-latitudes for mating and calving. Beyond this general migratory pattern, a number of demographic characteristics including, abundance, distribution, seasonal occurrence, and prey preferences remain unknown or poorly described. A...
Show moreThe North Pacific humpback whale (Megaptera novaeangliae) is a wide-ranging baleen whale species with a complex life history and population structure. As seasonal migrants, humpback whales are known to inhabit cooler, high-latitude waters when foraging and low-latitudes for mating and calving. Beyond this general migratory pattern, a number of demographic characteristics including, abundance, distribution, seasonal occurrence, and prey preferences remain unknown or poorly described. A complete understanding of humpback whale ecology is therefore lacking. Many methods used to explore these aspects of cetacean ecology are either prohibitively expensive or limited in the scope of what can be learned from their use. Fortunately, in recent years, the analysis of stable isotope ratios of animal tissues has proved a valuable and relatively inexpensive technique for providing information on trophic position, diet, and feeding origins of migratory populations. This study employed techniques in stable isotope ecology to increase knowledge of the population structure, migration routes, and foraging ecology of North Pacific humpback whales. Skin samples were collected from free-ranging humpback whales throughout all known feeding and breeding grounds and were analyzed for stable carbon (13C) and nitrogen (15N) isotope ratios. The population structure of humpback whales was first explored through geographic differences in stable isotope ratios. Stable isotope ratios varied significantly with location of sample collection. Based on this analysis, foraging animals were separated into six feeding groups. Classification tree analysis was then used to determine which isotopic variables could be used to predict group membership. Probable migratory linkages were then described by applying results of classification trees to 13C and 15N of animals sampled on breeding grounds. Strong migratory connections between the eastern-most foraging and breeding areas and the western-most areas were reflected in similarities of stable isotope ratios. Foraging ecology was then examined through calculation and comparison of the relative trophic levels of the six feeding groups. Isotopic values suggest some feeding groups are piscivorous, while others feed on a more mixed diet. These results can be used to determine if differences in diet composition between groups result in differences in accrued nutritional benefits, negatively impacting reproductive success and survival relative to fish eating groups. Finally, to gain insight into specific foraging habits, the diet of one group of humpback whales was modeled using an isotope mixing model. The 13C and 15N of Kodiak Island, Alaska humpback whales and several species of potential prey indicate that these animals likely rely heavily on euphausiids (Thysanoessa spinifera), Pacific sandlance (Ammodytes hexapterus), and capelin (Mallotus villosus). This study represents the first application of stable isotope ecology to an entire population of marine mammals. Stable isotope analysis was successfully applied to describe and improve understanding of the demographics of North Pacific humpback whales.
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Date Issued: 2008
Identifier: CFE0002386, ucf:47774
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002386

Title: Seascape genetics and rehabilitation efficiency in the Florida manatee.
Creator: Hall, Madison, Worthy, Graham, Weishampel, John, Hoffman, Eric, Dyer, Rodney, University of Central Florida
Abstract / Description: The Florida manatee (Trichechus manatus latirostris) was recently downlisted federally from (")endangered(") to (")threatened(") despite acknowledgments of remaining threats to long term population persistence. Challenges to future manatee conservation include, but are not limited to, increases in frequency of harmful algal blooms, intensifying anthropogenic disturbance, and loss of warm-water habitat. The goals of this dissertation were 1) to assess threats to the manatee via a comprehensive...
Show moreThe Florida manatee (Trichechus manatus latirostris) was recently downlisted federally from (")endangered(") to (")threatened(") despite acknowledgments of remaining threats to long term population persistence. Challenges to future manatee conservation include, but are not limited to, increases in frequency of harmful algal blooms, intensifying anthropogenic disturbance, and loss of warm-water habitat. The goals of this dissertation were 1) to assess threats to the manatee via a comprehensive, long-term (1973-2016), retrospective analysis of the manatee rescue and rehabilitation partnership (MRRP) and 2) to use seascape genetics analysis to examine whether abiotic, biotic, or anthropogenic seascape variables could significantly describe genetic distance patterns in space for this genetically depauperate population. Results from the MRRP analysis revealed that anthropogenic threats were the most significant reason for manatees to be rescued and rehabilitated. Manatees rescued due to watercraft injuries spent long periods in recovery before succumbing or being released resulting in significant expense to the rehabilitation system. Additionally, the seascape genetics analysis indicated that watercraft activity best explained spatial genetic patterns in the manatee population. It is established that anthropogenic use of watercraft negative affects manatees through the mechanisms of sub-lethal injury and mortality, and these results suggest there may be further negative impacts via the disruption of population genetic connectivity. Future management practices should seriously consider manatee/vessel interactions as watercraft strikes are costly for management, place pressure on the manatee population, and could disrupt population gene flow with potentially dire consequences. Mitigating anthropogenic impacts on the Florida manatee population is critical for future conservation and should be a primary focus.
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Date Issued: 2019
Identifier: CFE0007647, ucf:52465
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007647

Title: Fine-scale geographic variation of stable isotope and fatty acid signatures of three fish species in the Indian River Lagoon, FL.
Creator: Odom, Jennifer, Worthy, Graham, Jenkins, David, Paperno, Richard, University of Central Florida
Abstract / Description: The Indian River Lagoon, Florida, is a unique closed (")bar built(") estuary system that has little interchange with the Atlantic Ocean and which is home to many resident species. Three fish species were investigated to see if their isotopic and fatty acid signatures differed based on geographic location. The goal was to assess the degree of resolution of spatial variation that is possible when using stable isotope and fatty acid signature analysis to interpret feeding habits and potential...
Show moreThe Indian River Lagoon, Florida, is a unique closed (")bar built(") estuary system that has little interchange with the Atlantic Ocean and which is home to many resident species. Three fish species were investigated to see if their isotopic and fatty acid signatures differed based on geographic location. The goal was to assess the degree of resolution of spatial variation that is possible when using stable isotope and fatty acid signature analysis to interpret feeding habits and potential linkages between feeding habits and health status. Spotted seatrout (n=40), pinfish (n=60) and white mullet (n=60) were collected over a 4 week period at sites 30 km apart in two distinct biogeographic regions of the IRL. Fish were analyzed for stable isotope (?13C and ?15N) and fatty acid composition. All three species were significantly different from each other in both isotopic and fatty acid signatures. In the North Indian River segment, spotted seatrout, white mullet and pinfish had mean values ((&)#177; SE) for ?13C of -18.00 (&)#177; 0.08, -14.59 (&)#177; 0.07 and -16.88 (&)#177; 0.04 respectively and for ?15N, mean values were 14.43 (&)#177; 0.05, 8.30 (&)#177; 0.04 and 10.43 (&)#177; 0.03 respectively. For the North-Central Indian River segment, spotted seatrout, white mullet and pinfish had mean values for ?13C of -18.98 (&)#177; 0.02, -16.25 (&)#177;0.06 and -16.94 (&)#177; 0.04 respectively and for ?15N, mean values were 14.21 (&)#177; 0.02, 8.07 (&)#177; 0.03 and 10.64 (&)#177;0.03 respectively. When species and location interactions were examined using ANCOVA, a post-hoc Tukey's HSD test showed that ?13C was significantly affected by sampling segment only for spotted seatrout and that there was no significant effect of location on ?15N values. Spotted seatrout was the only species that differed between segments for ?13C. Classification and Regression Tree (CART) analysis was then performed on the (")extended dietary fatty acids(") for each individual species and collection location. In this analysis, all three species were correctly identified to segment (white mullet - MR 2/53 p~ 0.03; spotted seatrout (MR 0/40), and pinfish (MR 0/56) indicating that individual species were exhibiting significant differences in their fatty acid signature over distances of 30 km. The ability to discern fine-scale differences in potential prey allows for the possibility of better resolution of dolphin feeding habits and hence a better understanding of both habitat utilization and health impacts. Due to limited exchange of clean salt water, contaminants can theoretically become a problem and there are indications that the health of the resident population of bottlenose dolphins (Tursiops truncatus) has been declining over recent years.
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Date Issued: 2012
Identifier: CFE0004329, ucf:49434
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004329

Title: Using Biomarkers to Assess the Migratory Ecology and Reproduction of the Florida Green Turtle (Chelonia mydas).
Creator: Chabot, Ryan, Mansfield, Kate, Worthy, Graham, Seminoff, Jeffrey, University of Central Florida
Abstract / Description: Migratory connectivity between breeding and foraging areas is a vital component of the ecology of a diverse collection of marine vertebrates. Habitat quality, composition, and resource availability at these locations have direct ramifications for individual fitness. The green turtle (Chelonia mydas) is a long-lived, highly migratory species of conservation concern. Important green turtle nesting habitat in Florida is protected, but more information is needed to identify foraging habitats and...
Show moreMigratory connectivity between breeding and foraging areas is a vital component of the ecology of a diverse collection of marine vertebrates. Habitat quality, composition, and resource availability at these locations have direct ramifications for individual fitness. The green turtle (Chelonia mydas) is a long-lived, highly migratory species of conservation concern. Important green turtle nesting habitat in Florida is protected, but more information is needed to identify foraging habitats and the influence these habitats have on reproduction. Here, I used stable isotope analysis of ?13C, ?15N, and ?34S and satellite telemetry validation to determine the number of putative foraging areas used by the breeding aggregation at the Archie Carr National Wildlife Refuge (ACNWR), and the relative contribution of each foraging area. I evaluated the influence of foraging area and other variables on egg size, clutch size, hatching success, and emerging success using model selection frameworks. Isotopic values of skin and eggs were used to build conversion equations between the two tissue types. Results suggest strong migratory connectivity between the ACNWR and the Florida Keys/Florida Bay complex. I found that the influences of foraging area are likely to be more detectable when evaluating female-centric fitness metrics like clutch size and egg size; these influences are more muted in hatching and emerging success, which are strongly influenced by nest incubation conditions. These are the first green turtle-specific tissue conversion equations for ?13C and ?15N, and the first ?34S equation for any marine turtle species. These will allow researchers to have a (")common currency(") between frequently collected samples to better compare results.
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Date Issued: 2017
Identifier: CFE0006574, ucf:51314
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006574

Title: Habitat Use and Feeding Ecology of Delphinids Inferred from Stable Isotopes and Fatty Acid Signatures.
Creator: Browning, Nicole, Worthy, Graham, Jenkins, David, Hinkle, Charles, Cockcroft, Victor, University of Central Florida
Abstract / Description: Prey availability, directly or indirectly, affects all aspects of a predator's life history and is a primary factor influencing habitat selection and movements. This is especially true for delphinid species where it has been documented that the behaviors and movements of dolphins are strongly influenced by food availability. Unfortunately, the feeding ecology and habitat use patterns of many of these species are poorly understood. Many methodologies that have been employed to explore these...
Show morePrey availability, directly or indirectly, affects all aspects of a predator's life history and is a primary factor influencing habitat selection and movements. This is especially true for delphinid species where it has been documented that the behaviors and movements of dolphins are strongly influenced by food availability. Unfortunately, the feeding ecology and habitat use patterns of many of these species are poorly understood. Many methodologies that have been employed to explore these facets of dolphin ecology have limitations and constraints or are logistically infeasible. Stable isotope and fatty acid signature analyses have been used extensively on a wide variety of species and have been shown to be methodologies that overcome some of these limitations. These approaches can provide information on feeding habits and the geographic origin of the prey thereby giving tremendous insight into habitat usage patterns. The present study applied stable isotope and fatty acid signature methodologies to gain insight into the feeding ecology and habitat usage of various dolphin species to improve upon our understanding of these important facets of their life histories.The application of stable isotope analysis in ecological studies relies on both species and tissue specific measurements of parameters such as diet-tissue discrimination factors, the difference in stable isotope ratio between a consumer and its prey, and turnover rates, the change in tissue isotopic composition attributable to growth and tissue replacement. Initially, controlled studies were conducted and animals were switched from one isotopically distinct diet to another which allowed for the calculation of these values in bottlenose dolphin skin. Diet-tissue discrimination factors for dolphin skin averaged 2.20° for nitrogen and 0.82° for carbon. Average turnover rates (expressed in half-lives) in dolphin skin were 17 days for nitrogen and 16.5 days for carbon. The present study represents the first reported diet-tissue discrimination factors and turnover rates for carbon and nitrogen in the skin of any cetacean.Next, skin samples were collected from net-entangled and free-ranging dolphin species off the coast of South Africa and analyzed for stable carbon (?13C) and nitrogen (?15N) isotope ratios. The Indo-Pacific bottlenose dolphin (Tursiops aduncus), the common dolphin (Delphinus capensis), the striped dolphin (Stenella coeruleoalba), and the humpback dolphin (Sousa chinensis) all occur off the southeastern coast of South Africa with overlapping distributions. Isotopic signatures revealed resource partitioning among these four species of dolphins with differences in diets, as well as differences in the use of habitat. Mean values for ? 15N ranged from 11.92 (&)#177; 0.11° (n=3) for striped dolphins to 14.95 (&)#177; 0.19° (n=27) for humpback dolphins, indicating that these species are feeding at different trophic levels. Striped dolphin carbon isotope signatures were consistent with evidence that they typically forage further offshore (-17.94 (&)#177; 0.14°) and the carbon isotope values of the humpback dolphins reflected their use of inshore habitats by comparison (-15.16 (&)#177; 0.12°). Common and bottlenose dolphins for nitrogen (13.66 (&)#177; 0.08°, 14.35 (&)#177; 0.07° respectively) and carbon (-15.48 (&)#177; 0.07°, -15.76 (&)#177; 0.06° respectively) fell in between these two extremes. Analyses also revealed that males and females have differences in their diets. On average, males were enriched in ?15N by 0.74° compared to females suggesting some dietary differences in prey composition. Isotopic niche width has been compared to traditional measures of niches used by ecologists and was measured for these South African dolphins. Humpback and bottlenose dolphins had the largest standard elliptical area (SEA), striped dolphins had the smallest SEA, and the SEA for common dolphins was intermediate. Larger SEA values reflect a broader trophic diversity, while smaller SEA values reflect a narrower trophic diversity or a more specialized niche. Finally, a resident group of bottlenose dolphins (Tursiops truncatus) in the Indian River Lagoon (IRL) in east central Florida were sampled and explored for differences in isotopic signatures based on sex, age category, season, and location within the IRL. In addition to stable isotope analysis, fatty acid analysis was also used to compare and contrast the findings between the two techniques. Comparison of stable isotopic signatures revealed differences among age categories and among locations. Fatty acid analysis was able to discern further and found differences in the signatures between male and female dolphins. The combination of both techniques allowed for an extensive examination into the feeding ecology and habitat utilization of these resident dolphins. The Bayesian mixing model (Stable Isotope Analysis in R- SIAR) was validated using controlled study data and was found to be accurate when inputting isotopically distinct prey items (sources). The mixing model was then used to estimate the proportions of prey items that make up the diet of Indian River Lagoon bottlenose dolphins. Two models were run in which dolphins were grouped together (model 1) and dolphins were separated by year (model 2). Results of the model reaffirm stomach content analysis results previously obtained.Stable isotope techniques were applied to various dolphin species to gain better understanding of their feeding ecology and habitat utilization. Resource partitioning was suggested for four South African dolphin species which gives crucial insight into the ecology of both at-risk and data-deficient species. These discernments will provide much needed data to conservationists and managers and contributes to our general understanding of these species. This is the first study of its kind to undertake controlled diet studies with bottlenose dolphins which determined diet-tissue discrimination values and turnover rates for carbon and nitrogen isotopes in the skin of any cetacean. The current study is also the first of its kind to attempt to model bottlenose dolphin diet in the Indian River using stable isotopes. Food, being a primary driver for many species, can lend explanation of things like movement patterns, habitat usage, competition, reproductive success, survival, and the spread of diseases, which has been an issue in Indian River dolphins in recent years. Dietary information modeled in this study provided new data for the relative contribution of a suite of potential prey to an apex predator in the Indian River. Data produced through the current study contributes towards a large, unprecedented step forward in understanding dolphin ecology and the roll of cetacean stable isotope ecology.
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Date Issued: 2013
Identifier: CFE0004823, ucf:49733
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004823

Title: Movements, fishery interactions, and unusual mortalities of bottlenose dolphins.
Creator: Shippee, Steven, Worthy, Graham, Walters, Linda, Weishampel, John, Wells, Randall, University of Central Florida
Abstract / Description: Bottlenose dolphins inhabiting coastlines and estuaries in Florida have been impacted in the past decade by development, algal blooms, catastrophic pollution, and fishery interactions (FI). Dolphins react to disturbance and environmental stressors by modifying their movements and habitat use, which may put them in jeopardy of conflict with humans. FI plays an increasing role in contributing to dolphin mortalities. I investigated dolphin movements, habitat use, residency patterns, and...
Show moreBottlenose dolphins inhabiting coastlines and estuaries in Florida have been impacted in the past decade by development, algal blooms, catastrophic pollution, and fishery interactions (FI). Dolphins react to disturbance and environmental stressors by modifying their movements and habitat use, which may put them in jeopardy of conflict with humans. FI plays an increasing role in contributing to dolphin mortalities. I investigated dolphin movements, habitat use, residency patterns, and frequency of FI with sport fishing. Tagging studies with short-term data tags and bolt on radio-transmitters were done in several locations in Florida and the east coast providing fine-scale measurements of swimming, daily travels, and foraging activity. Transit speeds agreed with the predicted mean cost of transport as dolphins spent much of their day and night travelling and resting while swimming. Increased foraging was detected by stomach temperature changes revealing dolphins fed at night with a peak starting just after sunset. Dolphin abundance, site fidelity, ranging, stranding mortality, and community structure was characterized at Choctawhatchee and Pensacola Bays in the Florida Panhandle via surveying and photo-identification. Results showed they made frequent inshore movements, maintained site fidelity to specific areas, and comprised several distinct communities. FI was assessed at offshore reefs and coastal fishing piers near Destin, FL and Orange Beach, AL, showing that some dolphins demonstrate affinity to this activity. Harmful interactions with dolphins on reefs and at fishing piers negatively affect their resident communities. Mitigation of FI is suggested by use of avoidance strategies, gear modifications, and improved fish release practices.
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Date Issued: 2014
Identifier: CFE0005550, ucf:50273
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005550

Title: Effects of weaning age on body composition and growth of ex situ California sea lion (Zalophus californianus) pups.
Creator: Davis, Brandon, Worthy, Graham, Hinkle, Ross, Nolan, Elizabeth, University of Central Florida
Abstract / Description: Pinnipeds exhibit a wide range of lactation strategies that vary from just a few days to nearly three years in duration. Phocids have a relatively short, intense nursing period culminating with weaning after just a few days or weeks, while dependent otariids generally take several months of consuming a combined milk and solid food diet before being completely independent. The transition to nutritional independence can be particularly challenging for newly weaned pups, which must adjust to...
Show morePinnipeds exhibit a wide range of lactation strategies that vary from just a few days to nearly three years in duration. Phocids have a relatively short, intense nursing period culminating with weaning after just a few days or weeks, while dependent otariids generally take several months of consuming a combined milk and solid food diet before being completely independent. The transition to nutritional independence can be particularly challenging for newly weaned pups, which must adjust to behavioral, physiological and nutritional changes as a milk diet is replaced with solid food. An interruption in energy resources during this formative stage could result in a prioritization away from growth, maintenance, or activity resulting in suboptimal development.Three groups of ex situ California sea lion (Zalophus californianus) pups were examined during the initial period of independence after they were weaned at approximately five, seven, and nine months of age. Absolute growth rates of pups were calculated and changes in body composition were estimated using blubber depth measurements and deuterium oxide dilution to determine if weaning age had an effect on subsequent pup development and growth. Blood urea nitrogen and blood glucose levels were observed for their response to changes in body condition, while thyroid hormone levels in the blood were examined as a possible nutritional stress indicator during the pup's transition to solid food.When compared to in situ pups, the 5 month old pups in the present study had significantly greater body mass (39.6 (&)#177; 1.6 kg, p(<) 0.01), axillary girth (85.3 (&)#177; 2.9 cm, p(<) 0.01), and axillary blubber depth (2.3 (&)#177; 0.1 cm, p(<) 0.01) compared to 5 month old in situ pups (26.6 (&)#177; 5.2 kg / 70.6 (&)#177; 5.34 cm / 1.5 (&)#177; 0.2 cm). Nine month old ex situ pups had significantly greater axillary blubber depth (3.7 (&)#177; 0.9 cm, p(<) 0.01) and total body lipid percentage (24.9 (&)#177; 4.7%, p= 0.01) than in situ pups (1.5 (&)#177; 0.2 cm / 17.1 (&)#177; 4.9%). Although all pups in the present study survived the transition to solid food, there were apparent differences in how the different age groups responded physiologically. The five month old pups began the switch to solid food with the lowest overall blubber depth (2.6 (&)#177; 0.9 cm) and experienced the greatest change in body mass (-8.5 (&)#177; 1.6 kg) and composition while taking the longest to begin physiological recovery (31.7 (&)#177; 1.2 d). In contrast, the 9 month old pups entered the transition with more energy reserves (24.9 (&)#177; 4.7% TBL), began consuming solid food sooner (16.3 (&)#177; 0.6 d), and were able to utilize reserves more efficiently to minimize loss and promote faster growth.
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Date Issued: 2014
Identifier: CFE0005598, ucf:50259
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005598

Title: Physiological Constraints on Warm-Water Habitat Site Selection and Utilization by the Florida Manatee (Trichechus manatus latirostris) in East Central Florida.
Creator: Spellman, Ann, Worthy, Graham, Noss, Reed, Hinkle, Ross, DeFreese, Duane, University of Central Florida
Abstract / Description: Living at the northern limits of its geographic range, the Florida manatee is particularly susceptible to cold stress-related mortality during the winter months, with most deaths occurring in the lower two-thirds of the state. Contributing to this cold stress susceptibility is the manatee's limited physiological and behavioral responses available when thermally stressed. While capable of migrating south in response to falling water temperatures, manatees must still find warm water when...
Show moreLiving at the northern limits of its geographic range, the Florida manatee is particularly susceptible to cold stress-related mortality during the winter months, with most deaths occurring in the lower two-thirds of the state. Contributing to this cold stress susceptibility is the manatee's limited physiological and behavioral responses available when thermally stressed. While capable of migrating south in response to falling water temperatures, manatees must still find warm water when ambient river temperature drops below 20(&)deg;C for more than a few days. This is in part due to the species low metabolic rate, limited capacity for thermogenesis, and limited ability to raise its metabolic rate. Prolonged exposure to cold temperatures may result in cold stress syndrome, which involves a number of potentially life-threatening, if not fatal physiological changes. Survival during the winter months is therefore, dependent upon the manatee's ability to balance basic physiological needs, primarily the need to forage and to obtain fresh water with the need to stay warm.When identifying which animals are most susceptible and where, analyses of statewide manatee mortality records from 1996 through 2011 (n = 823) indicated that, size and location matter. Medium to large-sized calves accounted for the majority of documented death from cold stress (46.6%), while subadults and small calves were the least represented size classes (14.3 % and 9.5%, respectively). Adults slightly outnumbered subadults (15.8%). Males outnumbered females in all size classes but gender differences were not statistically significant. With regards to location, two areas of the state, the southwest and central east coasts showed the highest incidents of cold stress-related mortality. Both are regions with no primary, natural warm-water springs and whose principal warm-water refugia are power plant effluents. Brevard County on the central east coast is the area most at risk during cold weather events accounting for more than 25% of all cold stress deaths statewide. Warm-water sites within this region are few and relatively underrepresented in the literature in an area well-studied in terms of manatee abundance and distribution relative to the operational power plant. Results from cold stress data analyses emphasize the importance of identifying and characterizing the physical attributes of both known and suspected secondary warm-sites used by manatees in this region for both long and short term protection of the species, and its critical habitat.Three locations within Brevard County identified as passive thermal basins (PTBs), and classified as secondary warm-water sites, have been documented supporting in excess of 100 manatees on numerous occasions, and during winters of varying severity. Unique in physical appearance, distance to forage, hydrology including thermal profiles, and when it was used by manatees, each site challenged the accepted definitions and criteria of what constitutes an acceptable and appropriate warm-water site.Through analyses of photo-identification records, site fidelity at two of these warm-water sites, the Berkeley Canal and the Desoto Canal, was established for a minimum of 20 highly identifiable animals, 15 of which used adjacent sites within the same year, and 6 that used both sites but during different years. Observations of daily use patterns within the sites supported optimization of thermoregulation through adjustments in both vertical and horizontal movement, the latter of which seemed to follow the path of the sun. Manatees using the sites also made use of bottom sediment presumably to stay warm at all three locations. Temperature data indicated that water temperatures monitored in the sediment at secondary sites were some of the highest in the county. The predictable movements during all but the coldest weather fronts indicated that manatees utilized these sites during the early morning and afternoon hours when ambient river temperatures were coldest, gradually returning to the river to feed as ambient temperatures began to rise later in the afternoon.The availability of PTBs in proximity to primary warm-water sites within the region may provide an important component needed for manatees to successfully balance the need to forage with the need to stay warm by providing a network that allows for more efficient foraging while reducing exposure to sub-critical ambient river temperatures. The challenge of balancing the need to forage and to maintain homeostasis in the face of thermal stress is complex. This complexity was best approached and better understood through use of a manatee energetics model. The model was designed to facilitate simulation of an unlimited number of different case scenarios involving the exposure of virtually created manatees to a variety of winter conditions as might be experienced by real manatees in a natural system. Sixty-four different simulations were run using six virtual manatees of differing ages, gender, physical parameters, and knowledge of warm-water sites. Simulations were conducted using actual winter water temperature data from Brevard secondary sites and the ambient river from both a mild and a severe winter season. Outcomes, measured as changes in physical parameters indicative of body condition (i.e. mass, percent body fat, blubber depth, girths, etc.), showed that all else being equal, calves in the 2 year-old range fared poorly in all scenarios when compared to individuals of larger size. Subadults fared better than larger adults. This outcome illustrates the complex relationship between size, energy requirements and the synergistic effects of body mass, body fat and blubber thickness on SA:V ratio. Model outcomes agree closely with manatee cold stress mortality analyses predicting that medium to large-sized calves are most susceptible to CS, followed by adults, then subadults.Because all models are simplifications of complex systems, the manatee energetics model is not without its flaws and limitations. The current version of the model could not predict the point at which cold stress mortality would occur. However, a cold stress warning system incorporated into the design alerts the user if potential CSS is likely based on changing physical parameters. Another limitation was the inability of the model to account for the behavioral plasticity of individual subjects since virtual manatees respond to water temperatures based on the user defined rules. A number of additional limitations related to gaps in existing manatee data the gaps were identified and defined. Despite these gaps, the model is designed to allow for incorporation of additional interactions, feedback loops and relevant data as it becomes available and as additional physiological interactions and energy requirements are more clearly defined. Sensitivity analyses, a feature of the model that allowed for modifications in a number of physical as well as environmental parameters, provided an otherwise unlikely opportunity to see how incremental changes in input values, specifically the starting values for mass, percent body fat and blubber depth affected the model's outcome. Ultimately the goal of the model was to facilitate a better understanding of complex relationships by challenging our preconceived understanding of the manatee and its environment
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Date Issued: 2014
Identifier: CFE0005419, ucf:50428
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005419

feeding ecology (4)	+ -
BMR (2)	+ -
Eschrichtius robustus (2)	+ -
Florida manatee (2)	+ -
Indian River Lagoon (2)	+ -

energetic costs (2)	+ -
stable isotope (2)	+ -
stable isotopes (2)	+ -
BUN (1)	+ -
Bottlenose dolphin (1)	+ -
Choctawhatchee Bay (1)	+ -
North Pacific (1)	+ -
Pensacola Bay (1)	+ -
Steller sea lion (1)	+ -
Trichechus manatus (1)	+ -
Trichechus manatus latirostris (1)	+ -
Tursiops truncatus (1)	+ -
Unusual Mortality Event (1)	+ -
abundance (1)	+ -
algal blooms (1)	+ -
body composition (1)	+ -
body condition (1)	+ -
bottlenose (1)	+ -
cold stress (1)	+ -
connectivity (1)	+ -
conservation (1)	+ -
delphinidae (1)	+ -
deuterium (1)	+ -
diet-tissue discrimination (1)	+ -
discrimination (1)	+ -

ETD Collection (12)	+ -
Honors Collection (1)	+ -

University of Central Florida (13)	+ -
Worthy, Graham (13)	+ -
Greenwald, Nathalie (2)	+ -
Hinkle, Ross (2)	+ -
Jenkins, David (2)	+ -

Weishampel, John (2)	+ -
Alves, Christy (1)	+ -
Azcona, Alexandra (1)	+ -
Berman, Michelle (1)	+ -
Browning, Nicole (1)	+ -
Chabot, Ryan (1)	+ -
Cockcroft, Victor (1)	+ -
Davis, Brandon (1)	+ -
DeFreese, Duane (1)	+ -
Dyer, Rodney (1)	+ -
Hall, Madison (1)	+ -
Hinkle, Charles (1)	+ -
Hoffman, Eric (1)	+ -
Mansfield, Kate (1)	+ -
Nolan, Elizabeth (1)	+ -
Noss, Reed (1)	+ -
Odom, Jennifer (1)	+ -
Paperno, Richard (1)	+ -
Seminoff, Jeffrey (1)	+ -
Shippee, Steven (1)	+ -
Spellman, Ann (1)	+ -
Walters, Linda (1)	+ -
Wells, Randall (1)	+ -
Witteveen, Briana (1)	+ -

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