Thesis (Ph. D.)--University of California, San Diego, 1997. / Vita. Includes bibliographical references.

Proefschrift - Utrecht. / Errata slip attached to p. [vii]. "Stellingen": 2 leaves laid in. "Litteratuur": p. [297]-302.

In this study, I consider the comparative and functional anatomy of cerebrally related retial systems in the two constituent species (Monodon monoceros and Delphinapterus leucas) of the family Monodontidae (order Cetacea). The internal carotid arteries, the "classical" vessels of cerebral supply in vertebrates, are completely non-functional as cerebral supply vessels in the Monodontidae. Moreover, there are no other channels that contribute directly to intracranial supply. Rather, the brain, or more precisely, the entire central nervous system, is vascularized indirectly via an extensive arterial plexus or rete mirabile. This plexus is found in the thorax, lumbar region, neural canal and cranium. Vessels that contribute to retial formation are numerous and include those which in other mammals contribute directly to supply of the central nervous system and/or its membranes. Efferent retial vessels are few and include two pairs of subdural intracranial trunks that supply the brain, and numerous small segmental vessels that penetrate the spinal dura and vascularize the spinal cord. Subdural arterial circulation in the Monodontidae is modified after the basic mammalian pattern. Within the cranium, it is characterized by: (1) an incomplete circle of Willis (due to (a) independence of the anterior cerebral arteries and (b) the lack of anastomoses between the two pairs of trunks which take origin from the rete), (2) extensive cortical supply by the anterior choroid arteries, and (3) absence of a vertebral basilar system. Subdural arteries coursing to the spinal cord do so mainly between successive ventral spinal roots. An A. radicularis magna is not evident, nor are anterior or posterior spinal arteries. Hence, there are differences between the subdural circulatory patterns in the Monodontidae and those in other mammals, however the major site of vascular modification is epidural with formation of the rete mirabile. Though gross retial anatomy is the same in Monodon monoceros and Delphinapterus leucas, and is generally similar to that described for other odontocetes, there are two related characteristics that appear species specific: thoracic retial size and the number of intercostal spaces supplied by the supreme intercostal arteries. Both are larger in Monodon monoceros, as are hematological values (hematocrit and hemoglobin concentration) which, in this study, are used as indices of diving ability. These data are consistent with the hypothesis that cerebral related retia in the Cetacea are related to the diving habit. Microscopically, the rete generally consists of small muscular arteries embedded in fatty connective tissue interlaced with a few nerve trunks and veins. Arterial walls are characterized by a distinct internal elastic lamella, a tunica media of 12-14 layers of vascular smooth muscle, and an adventitia of alternating layers of collagen and elastin. Retial arteries are at best poorly innervated. The substructure of retial arteries resembles that of other mammalian arteries except for the presence of large deposits of glycogen (alpha particles) in vascular smooth muscle and endothelial cells. On the basis of this observation, and theoretical considerations, I generate the hypothesis that the rete may contribute to blood glucose levels during a dive. This hypothesis could not be tested directly, hence I chose an indirect approach involving biochemical and ultrastructural analyses. I conclude that free glucose release is not a major function of the rete since: (1) G-6-phosphatase activities are low, (2) LDH electrophoretic profiles suggest that most stored glycogen is used intrinsically, and (3) I could not demonstate glycogen deposits in retial vessels of other species. All proposed retial functions are evaluated, and I conclude that the system probably functions in a mechanical way (pressure reservoir) and that it does so passively. / Science, Faculty of / Zoology, Department of / Graduate

Whale-watching tourism depends upon the continued presence of cetacean species within a specific area. However, current evidence suggests that the distribution and/or abundance of cetaceans may alter in response to continued changes in sea surface temperature with global climate change (GCC). This thesis develops and applies a framework for evaluating the resilience of whale-watching tourism to these potential temperature-induced shifts in cetacean distribution. The framework identifies three key components that are likely to affect the vulnerability of an operator to climate change impacts on cetacean occurrence (and tourist numbers). These are the likelihood of observing a cetacean, the type of whale-watching trip, and the type of tourist. Together with an examination of an operator's adaptive capacity, these data provide the type of information required to make an assessment of resilience. Using Western Scotland as a case study, framework components were populated using species distribution modeling, a motivation-based segmentation of whale-watchers, an examination of tourist's attitudes to scenarios of a changing environment and a segmentation of trip activity. Finally, data on potential vulnerability were combined with investigation of an operator's adaptive capacity (using semi-structured interviews) to make an evaluation of resilience to climate change. Our results highlight four key findings: (1) operators have high inherent resilience to a variable environment in which uncertainty is accepted, (2) vulnerability to climate change is influenced by the type and number of trips offered by whale-watch operators, (3) adaptive capacity can be improved through enhanced perceptions of risk, and (4) vulnerability to climate change is not independent from vulnerability to other factors. Future research should focus on those areas where whale-watching is less diverse, more specialised and where, currently, the climate is less variable, as it is in these regions that vulnerability may be highest and, most likely, capacity to develop resilience at its lowest.

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, in fulfillment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015 / Cetaceans show an unusual form of mammalian sleep, with unihemispheric slow waves (USWS), suppressed REM sleep and continuous bodily movement, however the mechanism by which USWS occurs is unclear. This thesis describes the detailed anatomy of the neural systems systems involved in the control and regulation of sleep in the basal forebrain, diencephalon, midbrain and pons in three Cetartiodactyla species namely the Harbour porpoise, Northern minke whale and the Hippopotamus, as well as a broader study of the orexinergic system in Cetartiodactyls by means of immunohistochemistry and stereological analysis. All the neural elements involved in sleep regulation and control found in bihemispheric sleeping mammals were present in the harbour porpoise, minke whale and hippopotamus with no specific nuclei being absent, and the only novel nuclei being identified was the parvocellular orexinergic cluster in the hypothalamus- a feature seen in cetartiodactyla and the Africa elephant. This qualitative similarity of nuclear organization relates to the cholinergic, noradrenergic, serotonergic and orexinergic systems and is extended to the GABAergic elements involved with these nuclei. Quantitative analysis of the cholinergic and noradrenergic nuclei of the pontine region and the orexinergic nuclei of the hypothalamus revealed that in comparison to other mammals, the numbers of pontine cholinergic, noradrenergic and orexinergic neurons are markedly higher in the harbour porpoise and minke whale than in other large-brained bihemispheric sleeping mammals previously examined. Furthermore, the diminutive telencephalic commissures (anterior commissure, corpus callosum and hippocampal commissure) along with an enlarged posterior commissure and supernumerary pontine cholinergic and noradrenergic neurons in cetaceans indicate that the control of unihemispheric slow wave sleep is likely to be a function of interpontine competition, facilitated through the posterior commissure, in response to unilateral telencephalic input related to the drive for sleep. In addition, an expanded peripheral division of the dorsal raphe nuclear complex appears likely to play a role in the suppression of REM sleep in cetaceans. Thus, this thesis provides several clues to the understanding of the neural control of the unusual sleep phenomenology present in cetaceans

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 157-172).

Thesis (Ph. D.)--Department of Music, Stanford University, 2006. / Includes bibliographical references (leaves 188-215).

Thesis (M. Sc.)--University of Hong Kong, 2006. / Also available in print.

Thesis (M. Sc.)--University of Hong Kong, 2006.

As human impact on marine ecosystems continues to grow, so too does the need for sound conservation and management strategies that are informed by science. Cetaceans, the whales, dolphins and porpoises, epitomise this challenge, because they are hard to study, they have been heavily exploited in the past, and because some of their habitats, behaviours and life-history strategies make them acutely vulnerable to human activities. Unfortunately, research on free-ranging cetaceans in remote areas is costly, and financial resources are limited. The approach used in this thesis to acquire inexpensive quantitative information on cetacean populations and behaviour was to seek out platforms of opportunity. Tourism and environmental education projects provided access to remote areas of importance to cetaceans. The topic was explored in two main areas. First, studies were conducted to investigate the use of ships of opportunity in estimating distribution and abundance, namely of Antarctic baleen whales. The second area of interest was the effect of boats on killer whales in the northeast Pacific. Platforms of opportunity proved valuable for collecting data to model the role of measurement error on abundance estimation. Measurement error was found to be a potential source of bias in four distance estimation experiments. Platforms of opportunity could be used to train observers on protocols, and to learn to use range- finding photogrammetric equipment well before conducting dedicated surveys, which would eliminate this source of bias, as well as estimating abundance in some cases. Abundance and distribution of three whale species were modelled using data collected aboard Antarctic tourist ships. Spatial modelling techniques were used to model distribution of minke, fin and humpback whales using line-transect data collected from a survey that could not be randomised. Strong gradients in animal density were predicted, which could be used to inform future surveys. In the meantime, rough estimates of abundance were obtained, and this approach shows promise for other areas where lack of resources makes systematic surveys prohibitively expensive. A government-funded environmental education project provided logistical support for two studies that dealt with effects of boats on killer whale behaviour. One quantified the extent to which a particular style of whalewatching was disruptive to whale behaviour, and commercial whalewatchers agreed to halt this activity. The other found that a protected area conferred benefit to killer whales, even though it protects only a fraction of the whales' habitat for a fraction of the year. The thesis contains four case studies that illustrate how inexpensive methods may be used to obtain practical quantitative information to aid decision-making about conservation and management of wild cetaceans that interact with (i.e., whalewatching), compete with (i.e., fishing) or are exploited by (i.e., whaling) humans.