Bibliography: p. 281-301. / The successful management of the fishery for galjoen Dichistius capensis depends on an understanding of its spatial and temporal dynamics. This thesis investigates the movement of galjoen and its fishery parameters, and evaluates the role of marine protected areas (MPAs) and alternative assessment strategies. A review of the literature shows that there are examples of resident behaviour, territoriality, nomadism and migration among fish. Combinations of the above may exist within a stock. Fish movement behaviour may be plastic, but never random. Planktonic stages are capable of influencing their destination and settlement.

Includes bibliographical references. / The larks are a group of dull coloured birds that are conservative in plumage coloration and pattern due to the requirements for camouflage in open habitats. Because many species inhabit structurally similar habitats the group is also characterised by a great deal of morphological convergence. Variation in plumage and morphology is frequently as great within species as it is between species, leading to many inconsistent and controversial taxonomic treatments and classifications at an intra- and inter-generic level, and when defining specific and sub-specific boundaries. The advent of genetic techniques and success at applying these to species complexes in southern Africa suggested that a molecular phylogeny of the family would elucidate relationships that could not be determined via traditional taxonomic practices. In this study 2009 nucleotides of two mitochondrial DNA genes, cytochrome b and 16S rRNA (Chapter 2), and 2872 nucleotides of the nuclear exon RAG-l (Chapter 3) were used to generate a robust phylogeny of the family Alaudidae. The former analysis included 55 species and the latter 25. These data were also combined to construct a combined evidence phylogeny (Chapter 7). Within the family, several genera recognised by more traditional taxonomies are polyphyletic, including Ammomanes, Eremalauda .and Certhilauda. Two other genera, Calandrella and Mirafra, are best treated as multiple genera (Chapter 2). The sampled Alaudidae can be divided into three main radiations, the ammomanid larks, mirafrid larks and alaudid larks (Chapter 3). Within the ammomanid larks, there is strong support for: (1) a southern African' radiation comprising Chersomanes, the Long-billed Lark complex (Certhilauda) and Ammomanes (Ammomanopsis) grayi ,with Alaemon allied to this radiation; and (2) a .Saharo-Sindian radiation comprising Ramphocoris c1otbey, Ammomanes cinc(urus, and A. deserti sister to the Afro-Sindian sparrowlark Eremopterix clade. The Madagascan endemic Mirafra hova was a surprise basal member of Eremopterix.

Bibliography: leaves 165-184. / The threat of harmful algal blooms with their attendant problems, exists throughout the Benguela region. In the southern Benguela upwelling system, water discolorations, referred to as 'red tides', are common and usually attributed to dinoflagellate species. The first aim of the thesis was to investigate the taxonomy of gymnodinioid species in the southern Benguela current. In order to investigate the morphology of the southern Benguela isolates, a simple and rapid scanning electron microscope preparative technique was developed. In the course of these studies, a new genus and new species were identified and described.

Bibliography: leaves 201-218. / The biology of six non-mammalian cynodont genera, from basal to more derived forms was examined using bone cross-sectional geometry and histology, as well as isotope analyses. The bone histology of multiple postcrania revealed distinct variations in growth pattern between the genera studied. The bone histology of the basal Procynosuchus indicates that this animal had a slow, cyclical growth strategy and was probably sensitive to enviromental fluctuations. In contrast, the initial growth of more derived Thrinaxodon was rapid and only shows a marked decrease in growth rate with the onset of sexual maturity. The bone histology of the derived Cynognathus indicates rapid, sustained growth, whereas the bones of the contemporary Diademodon reveal a cyclical growth strategy that alternated between rapid growth during the favourable season and slow or arrests of growth during the unfavourable season.

A new species of planaria in the genus Phagocata was found in several springs and spring-fed streams in Logan Canyon, Cache County, Utah. This species was named Phagocata crenophila because it greatly prefers to live in springs and it seems to be adapted behaviorally to this type of habitat. Serial sections and whole mounts were made by standard methods in order to study the anatomical features which are necessary for identification of planarians. The distinguishing features of this species are the following: testes ventral and extending from near the brain to near the posterior end, ejaculatory duct opening ventrally from the penis, penis short and rounded with a prominent finger-like lobe at the tip, two eyes situated far back on the truncated head, and color usually dark gray. Comparisons to similar species are made, and a new key to the species and subspecies of the genus Phagocata is proposed. Several experiments were performed on cultured lab animals in order to determine their reactions to temperature and to current. Most animals which were kept in a refrigerator at l6°C. survived for a month or more. Several short experiments were performed using an artificial current created in 1000 mL. beakers by an electric magnetic stirrer. These tests indicate a fairly great tolerance of relatively high temperatures (16°C.), but a greater ability of P. crenophila to orient into a current and to resist being swept away by a strong current than Polycelis coronata with which it lives naturally. The ecology of each spring or stream in which the new species is found is discussed briefly. Observations throughout the year indicate that P. crenophila prefers cold, fast flowing head waters of streams with substrates composed of rocks and moss. P. crenophila may be able to better survive the strong current or the winter dry periods at Ricks Spring than P. coronata, thus resulting in a greater proportion of the former species in this spring. In other springs, populations of P. crenophila appear to be limited, at least partially, by the large populations of P. coronata.

The most destructive animals in the world are rats (Rattus sp.). The annual destruction caused by rats in the United States is not known. but it has been estimated to be $189,000,000, according to Silver (1942) of the United States Fish and Wildlife Service. Silver states that our nation’s farmers lose approximately $6,000,000 annually. Rats not only eat vast amounts of food meant for human and livestock consumption, but they contaminate and waste as much or more than they eat. Rats are able to gnaw into buildings, grain bins, and other places were food and shelter are available to them. Other feeding habits may be more destructive, such as the killing of baby chicks, baby pigs, lambs, and at times, full-grown hens and ducks. Several hundred baby chicks have been known to be killed in a single night. With today' s need for increased human and livestock food throughout the world, we cannot afford to feed millions or rats.

Abstract not available

Bibliography : pages 178-202. / Combined laboratory and field studies were employed to examine the feeding ecology of sardine Sardinops sagax in order to evaluate conflicting hypotheses regarding the trophic position of clupeoids in upwelling ecosystems, and to compare the trophodynamics of sardine with those of the co-occurring anchovy Engraulis capensis. Carbon and nitrogen budget models constructed using data from these studies were used to quantify the effect of particular food environments upon sardine growth. Sardinops sagax is primarily a filter-feeder, with food particles <1230μm total length eliciting a filtering response while larger particles elicit particulate-feeding at low concentrations and filter-feeding at high concentrations. This species is able to retain cells as small as 13μm, feeds at near-maximum efficiency when filterfeeding, and displays size-selectivity during particulate-feeding. Significant linear relationships between respiration rate and swimming speed obtained for sardine demonstrate that filter-feeding is the most energetically cheap feeding mode. Although omnivorous, sardine absorbs carbon and nitrogen more efficiently from zooplankton than from phytoplankton. Gastric evacuation follows an exponential pattern in sardine, and is influenced by food type; phytoplankton is evacuated faster than zooplankton. Feeding periodicity in sardine is size dependent; small fish show a feeding peak at, or around, sunset whereas larger fish appear to feed continuously. Estimates of daily ration range between 0.99 to 7.58% wet body mass.d-¹, depending on fish size and food type. Sardine stomach contents are numerically dominated by small particles, principally dinoflagellate phytoplankton, but the majority of the sardine's dietary carbon is derived from zooplankton, principally small calanoid and cyclopoid copepods. The budget models indicate that sardine is capable of positive growth under most of the trophic conditions it is likely to encounter in the southern Benguela upwelling system. The classical hypothesis that the high abundance of clupeoids in upwelling ecosystems results from their phytophagy is rejected; like anchovy, sardine are primarily zoophagous. However, these two species are trophodynamically distinct and show resource partitioning on the basis of prey size; sardine consume small zooplankton whilst anchovy consume large zooplankton. This difference is likely to contribute to regime shifts observed between these two species.

No description available.

No description available.