No description available.

No description available.

Thesis (MAppSc) -- AUT University, 2008. / Includes bibliographical references. Also held in print (108 leaves : ill. ; 30 cm.) in the Archive at the City Campus (T 594 DEW)

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Bibliography: leaves 72-74.

Thesis (Ph.D.)--University of Massachusetts Boston, 2005. / Title from PDF title page. Available through UMI ProQuest Digital Dissertations. Includes bibliographical references (p. 82-102). Also issued in print.

Purely qualitative investigations of the plankton of an area cannot provide sufficient information for the full understanding of the seasonal changes that oocur nor of the interrelation of the various planktonic plants and animals. Quantitative data must be obtained before these can be properly described. Except for the qualitative records by Scott (1906, 19(7) and Hiddell (1914) the plankton of waters off the north ooast of Wales, and of the Menai Straits in particular, has tended to be neglected. The unusual hydrographic conditions of the Menai Straits, which connect areas whose fauna and flora show considerable differences (Crisp & Knight-Jones, 1953) suggested such studies would be rewarding. In describing the various populations the policy in the present work has been to give the details of the most numerous species of both plants and animals individually and to summarize the others in various groups. This simplified the description and discussion of the dynamics of the population, which would be difficult to follow if all species were described in detail. At an early stage in the investigations it became obvious that the plankton of these coastal waters differed considerably from that of the Irish Sea in general, which has been described by Williamson (1956). In particular tho copepods Oithonina nana (Giesbrecht) and Euterpina acutifrons (Dana) were prominent species in the Menai Straits. Euterpina acutifrons was found to have several points of interest. Firstly, dimorphism occurs in the male; this has received considerable attention and has been found to be of some significonce in the biology of the species. Secondly, Euterpina is pelagic, while most other harpacticoid copepods are benthic or littoral. Investigations of its development (which was inadequately described by Tesch (1915)) in culture allowed a consideration of the adaptive modifications of Euterpina to a pelagic existence, of its rate of growth and development, and of the developmental aspects of dimorphism in the male. The latter has been a controversial subject in previous studies of copepod development (Sewell, 1912, 1929, 1940; Gurney, 1929; Coker, 1934) . Thirdly, Euterpina has a world-wide distribution, mainly centered in the warmer seas. Consideration of this led to investigations of some aspects of the relationship between the environment and the development of the species and also to a comparison of its breeding season in the waters round Anglesey with those reported in other latitudes . The present work also includes studies of the larval development of Oithonina nana, another warm water form. Despite its being a very common plankton animal, the larval. development of this species has tended to be neglected. In the work as now presented the studies of these species are given a considerable proportion of the total space, since the data provided on their development, growth and breeding illuminate the general study of the plankton which, in turn, forms a background to the detailed studies. The form of presentation of this thesis may perhaps call for some explanation. The sections into which it is divided have been prepared in the form of separate papers intended for publication. This means that figures and tables are numbered oonsecutively within each section and not continuously throughout the thesis, and also that a separate bibliography will be found at the end of each section. It is hoped that this method of presentation will cause no inconvenience to the reader.

Dwarf sperm whales, Kogia sima, are among the most commonly stranded yet least known pelagic cetaceans. I assessed seasonal and spatial variation in dwarf sperm whale group size and abundance off Great Abaco Island, the Bahamas. After correcting for survey effort and variation in sighting efficiency among sea states, I found that dwarf sperm whale group size and habitat use varied seasonally. In summer, dwarf sperm whale groups were small (median = 2.5, range = 1-8) and were found only in the two deep habitats within the study area (slope 400-900 m, deep 900-1600 in). In winter, group sizes increased (median = 4, range = 1-12) and sightings were almost six times higher in the slope habitat, where vertical relief is highest, than other habitats. My results suggest that studies of pelagic cetaceans and conservation plans must explicitly account for seasonal variation in group size and habitat use.

No description available.

Top predators serve important roles within their respective ecosystem through top-down and bottom-up effects, yet understanding how these roles vary among individuals within predator populations is still in its early stages. Such individuality can have important implications for the functional roles predators play within their respective ecosystems. Therefore, elucidating the factors that drive persistent individual differences within populations is crucial for understanding how individuals, and in turn populations, will respond to environmental changes and anthropogenic stressors, and the implications of these responses for particular ecological functions. In this dissertation I investigated the movements, residency patterns, and trophic interactions of a juvenile bull shark (Carcharhinus leucas) population in a coastal estuary that serves as a nursery. I found that bull sharks undergo ontogenetic niche shifts in their diets and habitat use, with a gradual shift from using freshwater and estuarine resources to marine resources as sharks grew. This behavioral shift appeared to be driven by age-based differences in tradeoffs between safety from predators and availability of prey. Nested within population-level trends in behavior, there was considerable, and consistent, individual variation in both movements and trophic interactions suggesting individual specialization and divergent behavioral tactics within the population. Different behavioral types likely play different roles in food web connectivity and ecosystem dynamics, thus understanding the drivers and importance of phenotypic variability among species will be crucial for improving management strategies and predicting the responses of species and ecosystems to impending changes in environmental conditions and human impacts.

Interest in the health of marine mammals has increased due, in part, to the attention given to human impact on the marine environment. Recent mass strandings of the Atlantic bottlenose dolphin (Tursiops truncatus) and rising mortalities of the endangered Florida manatee (Trichechus manatus latirostris) have raised questions on the extent to which pollution, infectious disease, "stress," and captivity influence the immune system of these animals. This study has provided the first in-depth characterization of immunocytes in the peripheral blood of dolphins (n=180) and manatees (n=56). Immunocyte morphology and baseline values were determined in clinically normal animals under free-ranging, stranded and captive living conditions as well as by age and sex. Additionally, immuocyte population dynamics were characterized in sick animals. This was accomplished with traditional cytochemical techniques and new lymphocyte phenotyping methodology which was validated in this study. Traditional cytochemical techniques demonstrated that blood immunocyte morphology and cell numbers are similar to terrestrial mammals with some notable exceptions. The manatee heterophilic granulocyte is a morphologically unique cell and probably functions similarly to the typical mammalian neutrophil. Eosinophils were rarely found in manatees but were uncommonly high in healthy and sick dolphins. Basophils were not identified. Manatees had higher total lymphocyte numbers compared to dolphins and most terrestrial mammals. Lymphocyte subsets identified in healthy animals included Th, Tes, B and NK cells. Dolphin and manatee T and B cell values were higher than those reported in man and most terrestrial mammals. The manatee has extraordinarily high absolute numbers of circulating Th cells which suggests an enhanced immunological response capability. With few exceptions, immunocyte types and absolute numbers were not significantly different between free-ranging, stranded and captive categories or between sex and age categories. The evaluation of immunocyte dynamics in various disease states demonstrated a wide variation in cellular responses which provided new insights into innate, humoral and cell-mediated immunity in these species. Additionally, this study demonstrated that lymphocyte phenotyping has diagnostic significance and could be developed into a potential indicator of immunocompetence in both free-ranging and captive dolphin and manatee populations.