Bibliography: pages 65-75. / This study aims to quantify both the individual and population energy budgets of the large edible gastropod Haliotis midae, and is divided into three major sections. Section 1 deals with diet and section 2 the consumption rate, absorption efficiency, respiration rate and rate of ammonia excretion, each of which were measured as functions of wet body mass. Each aspect was studied using animals from two sites subject to different temperature regimes. One of these was on the western Cape coast, off Marcus Island (at 14° C) and the other on the south western Cape, Cape Hangklip (at 19°C) Fig.l. Together with the existing knowledge on growth rate and fecundity of H. midae (Newman, 1967 and 1968), the third section is used to convert the above parameters to energy equivalents and to compile energy budgets for the individual animals as well as for the populations in the different study sites.

Includes bibliographical references (leaves 77-90). / Populations of species adapt to the environment in which they live. This study investigated local adaptation in Rhinolophus clivosus (Chiroptera: Rhinolophidae) by comparing its phenotype with that of a co-occurring endemic species. R. capensis, in the Cape Floristic Region of South Africa. If R. clivosus has become locally adapted, its phenotype would be predicted to have diverged from R. clivosus populations elsewhere in the country while converging upon R. capensis. Evidence for local adaptation was found in R. c/imslls at De Hoop Nature Reserve. The population has undergone a reduction in body size with correlated allometric responses in flight morphology. The wing shape of R. clivosus at De Hoop has not changed, resulting in a reduction in wing loading with a consequent increase in manoeuvrability. Thus R. clivosus at De Hoop is simply a scaled-down version of R. clivosus elsewhere and a scaled-up version of R. capensis. Factors such as competition and gene flow may have mitigated against local adaptation, however. Furthermore. whether phenotypic plasticity rather than natural selection may have been responsible for the apparent convergence between R. capensis and R. clivosus requires future research and advances in the study of evolutionary development and population genetics.

Includes abstract. / Includes bibliographical references. / Much of what is known about penguin movements and life history traits, including their population dynamics, and particularly the rehabilitation success after oil spills results from information derived from marking birds with flipper bands. However, flipper bands may negatively impact the welfare of penguins. While studies on the impact of banding have been undertaken for several penguin species, no such study has investigated the exclusive effect of banding on African Penguins Spheniscus demersus. I do so by comparing the difference in yearly return rates as well as foraging trip durations of 100 individuals injected with a subcutaneous transponder only, and 100 that have both transponders and a stainless steel flipper band.

Bibliography: leaves 122-159. / Three fish species, anchovy Engraulis encrasicolus, sardine Sardinops sagax and round herring Etrumeus whiteheadi, co-exist over the western Agulhas Bank (W AB) in the southern Benguela upwelling ecosystem. To date, data on high-resolution distributions in ichthyoplankton in the region is lacking. To address this need, coarse and high-resolution ichthyoplankton data were collected using a California vertical egg tow (CalVET) net and a continuous, underway fish egg sampler (CUFES) for horizontal data, respectively, and plankton pump and a closing WP II net for vertical data. Simultaneous measurements of temperature were recorded during the CalVET net hauls. Eggs from vertically stratified samples were grouped into three categories based on their developmental stage using established protocols. Volumetric estimates of egg density (eggs.m-3) from on-station CUFES samples were significantly correlated with normalized areal (eggs.m-2) estimates of egg density from CalVET net samples at these stations for sardine (r 0.91), round herring (r=0.80) and anchovy (r = 0.73), demonstrating the validity of the CUFES sampling technique. Underway sample collection reduced the survey coefficient of variation for sardine and round herring eggs but not for anchovy eggs. Horizontal egg distribution patterns for anchovy showed that high egg densities were centered at two specific regions: midshelf (east of Cape Point) and offshore in the southern region of the study area, whereas those of sardines and round herring were more continuously distributed above and beyond the 200m isobath. Egg abundances for all species generally increased from inshore towards offshore. The mean egg densities for all three species were found to be spatially associated, whereas the station by station distribution patterns of anchovy eggs were spatially distinct from sardine and round herring. Eggs of all three species were concentrated near the surface (0-20 m), although proportions varied among species. All developmental stages of anchovy egg were confined close to the surface indicating that this species spawns near the surface. Sardine and round herring vertical egg profiles varied ontogenetically, even though all developmental stages were concentrated near the surface. A significant (> 50%) proportion of early egg stages were widely distributed between 0-60 and 0-80 m for sardine and round herring, respectively. These results therefore show that the spawning depths of these three c1upeiforms overlap to a large extent, but the intensity of spawning varied at depth for each species. In general the vertical thermal structure seemed to affect only how deeply the eggs are distributed rather than the mean egg abundance. The differences in vertical egg profiles among and within (with respect to ontogenetic variation) species were found to be statistically significant (Chi-squared test, P < 0.05). Investigations of spawning patterns in relation to temperature, longitude and latitude were used to compare the spawning habitats of the three species. Quotient rule analysis was used to distinguish the preferred temperature ranges of all three species. Round herring spawn over a wider temperature range (16.5-18.1°C) than anchovy (17.4-17.8° C and sardine (17-18.1 °C). Two spawning peaks were apparent for round herring (main peak at 17.2°C and secondary peak at 17.8°C), whereas only one peak at 18.0°C was apparent for anchovy and sardine. Anchovy spawning showed a domed-shape relationship with geographic location and the relationship was viewed to be more informative (r2 = 0.13 longitude, ~ = 0.11 latitude) compared to sardine (r2 = 0.08 longitude, r2 = 0.07 latitude) and round herring (r2 = 0.04 longitude, r2 = 0.06 latitude). These results indicate that anchovy were more specific in their selection of spawning habitat than sardine and round herring. Generally, these results suggest that the overall spawning habitats of anchovy, sardine and round herring on the W AB overlap to a large extent, but their exact locations of the point of spawning are spatially distinct.

Includes bibliographical references. / Seabreams are an important family of fishes in the southern African recreational and commercial linefisheries. This family is known for its extreme longevity, slow growth and wide variety of reproductive styles. Red stumpnose are one of the most iconic species within this family, yet biological information is lacking on this species. Six hundred and seventy-eight specimens were collected from 1986 to 2012, ranging in size from 165 to 600 mm fork length. All specimens were dissected and morphological measurements taken. Gonads, stomachs and otoliths were removed from 237 individuals and presented. Otoliths were sectioned and independently aged by three readers, age agreement was reached on 183 fish.

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No description available.

Includes bibliographical references. / Generally aquaculture continues to suffer from pollution and this has resulted in the decline of production. The effect of pollution can be directly on the organisations cultured causing immediate death or retarding their growth and making them vulnerable to a variety of diseases, or indirectly by reducing their reproductive capacity. This study was carried out to investigate the effect of zinc and lead on the hatched eggs, and zinc and copper on spawing and hatching of eggs from mature female Penaeus indicus. The experiment for each heavy metal was conducted separately. In the post-spawning experiment, hatched eggs were counted and exposed to 0.0, 0.1, 10., 10.0 and 100 ppm of zinc and lead to see the effect of the heavy metals on hatching of the eggs and survival of the hatched eggs. Concentrations of 0.0, 0.1 and 1.0 ppm of zinc and lead did not show signicant difference of hatch rate among each other but 10.0 and 100.0 ppm of zinc and lead gave significantly lower hatch rate as compared with the lower concentrations. Hatch rate completely failed at 100.0 ppm of both heavy metals.

Bibliography: leaves 76-87. / Infestations of sabellid polychaetes were found in South African farmed abalone in 1994. Growth experiments confirmed that infested abalone had reduced growth rates. Surveys of both the intertidal and subtidal region at various locations around the South African coastline revealed that the sabellid was endemic to the region. It occurred in a range of mollusc species, but some species were more susceptible than others. The fact that some molluscan species became infested with worms only when exposed to them in the laboratory suggests that environmental factors may play a role in controlling natural levels of infestation. Different host selection on the East Coast of South Africa suggests that there may be more than one species of worm. Larvae disperse by crawling and settle at the growing edge of the shell underneath the mantle. Although the larvae are benthic, there is limited transfer of larvae through the water column, which can result in export of larvae from infested tanks. The risks of dispersal are discussed in a farm management context. Abalone kept in more hygienic laboratory conditions tended to grow faster than in farm tanks and had lower levels of infestation by sabellid larvae. This was attributed to the sabellids being less fecund under these conditions. This was probably caused by lack of food as evidenced in a separate starvation experiment. Based on experimental observations and farm experience it was possible to make management recommendations to limit the effect of the sabellid Quantitative measurement taols to assess the impact and productivity of sabellid infestations were developed Management of infestations on a farm requires a combination of inhibiting transfer and productivity of the worm and also promoting growth of the abalone. However, the constant risk of exposure to natural populations of sabellids necessitates the development oJ a treatment to eradicate sabellid infestations. The use of microcapsules as a drug delivery mechanism was explored and holds promise. Gelatin microcapsules, oil immulsions and liposomes were experimented with. All formulations were successfully produced in the desired size range of 2-30 μm. In all cases the sabellid'l readily ingested the capsules. Various toxins were successfully added to the formulations, but none of the treatments were able to harm the sabellids. The problem appeared to be the short passage time within the guts and the inability of the sabellids to digest the outer encapsulating layers to expose the toxins. More research is required to find the correct combination of toxin and delivery mechanism.

Includes bibliographical references. / Subordinate, female naked mole-rats (Heterocephalus g/aber) are anovulatory as a result of extremely low luteinising hormone (LH) levels. Evidence suggests that aggression from the dominant female naked mole-rat directed towards subordinates could produce these lowered levels of LH. This study examined two potential hormonal pathways of reproductive suppression in this species: endogenous opioid peptides and cortisol.