Bibliography: pages 67-82. / Little has been documented on the biology of Neltumius arizonensis Schaeffer. This bruchid is native to the south-western United States of America and is a prospective biological control agent of Prosopis spp. in South Africa. The primary objective of this study was to examine and quantify the oviposition behaviour of N. arizonensis females under different conditions to determine whether eggs of conspecifics or of another bruchid species, Algarobius prosopis (LeConte), affected oviposition. Diet, the number of mates, the duration of access to mates, and the variety of Prosopis pod provided for oviposition all affected the fecundity of N. arizonensis. Optimal conditions for N. arizonensis oviposition included: a diet of pollen pellets in solution, constant access to a limited number of mates, and mature, undamaged Prosopis pods of the 'mottled-purple' variety. The physical structure of the surface of Prosopis pods, observed by scanning electron micrography, did not reveal trends in characteristics among pod varieties that could be linked to the oviposition preferences of N. arizonensis. The rate of oviposition in N. arizonensis peaked between the third and eighth day after emergence from pods and was highest during the first hour when females that had been deprived of pods for at least three days, were provided with pods. Each N. arizonensis female laid an average of about 80 eggs during her lifetime, which was about 3 5 days on average. An event-recording computer programme was developed to quantify the oviposition behaviour of N. arizonensis when females were provided with one of four types of Prosopis pods for one hour: (a) pristine pods, (b) pods with conspecific eggs, (c) pods with A. prosopis eggs deposited within slits, and (d) pods with egg-free slits. Analyses of time budgets indicated that pod type had no significant effect on behaviour, although some activities differed significantly with the type of pod provided, but probably only as a result of the greater number of eggs laid on some pod types. Certain activities i.e. inspection of the pod surface, remaining stationary, and scraping of the ovipositor across the surface prior to egg deposition, occupied significantly more time on pods than other activities. Pod type did not affect the total time females spent on pods, nor the frequency of visits to pods. The availability of clean seeds did not affect the quantity of eggs deposited and the rate of oviposition did not differ significantly on pods of different types.

Bibliography: pages 169-178. / Two independent investigations into aspects of marine fouling were conducted in Simonsbay and Table Bay during 1979 to 1981. The development of macrofouling communities on six test materials was examined at 10m and 20m depths in Simonsbay for periods ranging from one month to one year. Community development was similar on inert non-reactive materials, aluminium, stainless steel, fibre glass and polyvinylchloride, but was reduced on non-wettable silicon rubber and corrodible mild steel. Macrofouling was characterized by seasonal succession with minimum colonization rates during winter, when adverse weather and low temperature conditions prevailed. The nature of fouling differed with depth. At 10m depth, mussel and barnacle-dominated communities developed rapidly, while at 20m depth, ascidian and barnacle-dominated communities developed more slowly. The role of primary film formation in the colonization of substrata by invertebrates was investigated in short-term studies conducted in Simonsbay and Table Bay. Surface-bound antibiotics, streptomycin and penicillin, were used to inhibit bacterial proliferation, while a herbicide, diuron, was employed to prevent diatom growth. The colonization by invertebrates was monitored on these surfaces and compared to surfaces where primary film development was normal, or where it was advanced by pre-culturing in laboratory seawater. It was found that invertebrates attached soon after panel exposure and that differences in the degree of primary film development were of little consequence to their settlement. The apparent discrepancy of these observations with previous findings is discussed, with special reference to the location of test sites in relation to mature communities.

Bibliography: leaves 149-155. / Since there has been no comprehensive nationwide economic study on the expanding wildlife market in South Africa, the present study ventures into a relatively unexplored economic terrain in the hope that more studies will be stimulated in that direction. The study focuses, firstly, on presenting an economic overview of the current trends within the wildlife market of South Africa, attempting inter alia to demonstrate how the sustainable utilisation of wildlife can contribute to both conservation and the economy. Secondly, it is endeavoured to describe the demand for wildlife species at game auctions across South Africa, using a range of econometric modelling techniques.

Bibliography: leaves 74-82. / This study quantifies the breeding and wintering ranges, habitat occupancy, diet and foraging mode of each migrant taxon on each of the three flyways. It aims to compare how patterns of migration between the temperate and tropical latitudes vary spatially in response to a) the geography of the land masses, b) relative availability of different habitat types, c) dietary preferences and d) foraging mode.

Includes bibliographical references. / Four troops of chacma baboons Papio ursinus, comprising approximately 150 individuals, have home-ranges largely in the Cape of Good Hope Nature Reserve. One hundred and twenty-one days of observation was made of one of these troops, 0 troop, between March 1975 and February 1976. 0 troop occupies a home-range of roughly 4000 ha, using nine different sleeping cliffs. Troop members were observed most frequently throughout the year in a 45 ha core area containing one sleeping cliff. The troop showed no clear habitat preferences, but occupied alien Acacia thickets and Upland Mixed Fynbos more frequently than expected from the spatial distribution of these vegetation types in the home-range. Frequency of baboon occupation for each of five vegetation types varied seasonally, and appeared to be a reflection of the availability of plant food.

Bibliography: pages 104-111. / The naked mole-rat provides possibly the most extreme example of socially-induced reproductive suppression observed in any mammal. The majority of colony members remain reproductively suppressed for their entire lives, nevertheless they are not sterile, and can become reproductively active soon after removal from the colony. The breeding female controls reproductive suppression in the non-breeding animals, and both males and females are sensitive to her presence and reproductive state. The breeding female is thought to maintain reproductive suppression in the non-breeding animals by preferentially directing agonistic behaviour towards those animals that pose the greatest threat to her reproductive supremacy. Previous studies have investigated the phenomenon of reproductive suppression in the naked mole-rat, and have compared breeding and non-breeding animals selected at random from several colonies (Faulkes, 1990; Faulkes et al., 1990a; 1990b; Faulkes & Abbott, 1991), but none has looked at the individuals of entire colonies. Moreover, the time in the breeding female 's reproductive cycle when data have been collected has never been standardised. The aim of this study was to conduct the first large-scale investigation of reproductive suppression in the individuals of entire colonies of naked-mole-rats, over the reproductive cycle of the breeding female. The study was conducted on two colonies of naked mole-rats. In order to standardise the time in the breeding female's reproductive cycle during which data would be collected, the gestation period was divided into three time intervals, early (days 1-15), mid (days 30-40) and late (days 55-65) pregnancy, with the assumption that mating occurred on day 10 after parturition. During each time interval, behavioural data and blood samples were collected, and GnRH challenges were performed on all the colony members over 26 g. An in-vitro bioassay based on the production of testosterone by dispersed mouse Leydig cells was used to measure LH concentration in plasma samples collected before and 20 min after an exogenous dose of 0.1 μg GnRH. The results of this study support the findings of these previous studies, by providing conclusive evidence for reproductive suppression in non-breeding naked mole-rats, and by confirming that non-breeding females are more suppressed than non-breeding males.

Bibliography: pages 86-95. / The availability of the ribbed mussel, Aulacomya ater is thought to be the most important factor influencing the growth rate of the commercial rocklobster, Jasus lalandii on the southern African west coast. A range of growth rates represented by von Bertalanffy growth curves is estimated for both A. ater and J. lalandii. Five models of differing complexity based on the age distributions of these populations are formulated with the main purpose of investigating optimal harvesting strategies for i, lalandii. Mussel and lobster single-species models are developed with constant recruitment, as is a lobster model incorporating a linear stock-recruitment relationship. Two models in which lobster growth is influenced by mussel availability are presented, one in which there is constant recruitment and the other having a linear stock-recruitment relationship for lobsters. Data are compiled for three areas of differing J. lalandii growth rates and A. ater biomass. Two are rock-lobster fishing grounds, the Cape Peninsula and Dassen Island at which there is a small and large benthic biomass and corresponding "slow" and "overall" estimates for rock-lobster growth, respectively. The third area is a rock-lobster sanctuary, Robben Island where there is a large benthic biomass and rock-lobsters grow at a "fast" rate. The mussel, lobster and lobster-mussel models assuming constant recruitment are used to examine the effects various parameters have on population si2e composition. Growth and predation have marked effects on the si2e structure of the prey population whereas the size composition of the predator population is greatly affected by growth and harvesting. The simplest of the four lobster models, the single-species constant recruitment model produced. the most practical management information. The lobster model incorporating a stock-recruitment relationship is unstable while the lobster-mussel model with constant recruitment requires finetuning. Only simulations of the Cape Peninsula fishing ground produced valid results using the lobster-mussel model with a stock-recruitment relationship. Based on the results of the most reliable models, three main conclusions about rock-lobster harvesting strategies are made. An increase in fishing pressure is unlikely to be commercially beneficial because of the resulting decrease in catch ·per unit effort. If opened to fishing, the Robben Island sanctuary is likely to produce a sustainable yield of at least 340 tons annually with a small reduction (7 %) in the size of this population. Although results differ from area to area according to growth and harvesting rates, reducing the minimum catchable size from the present 89 mm carapace length to 70 mm or 80 mm is predicted to give a better overall harvest. The more conservative estimate of 80 mm minimum catchable size may cause the least change to the ecosystem, possibly produce a catch of more marketable si2e and may guard against "recruitment overfishing".

Word processed copy. / Includes bibliographical references (leaves 52-65). / The main objectives of this study were: (1) to develop a method of accurately and consistently counting daily increments; (2) to use the increments in otoliths counts to estimate age of the individuals; (3) to back-calculate hatch-dates to identify cohorts, and, (4) to analyze growth and mortality of sardine larvae and juveniles in the Southern Benguela region during early 2001.

Bibliography: leaves 110-124. / The relationships between the pelagic purse-seine fishery and Jackass penguins (Spheniscus demersus) were investigated at Saldanha Bay, on the south-western coast of South Africa, between December 1982 and August 1983. The distribution at sea and the foraging behaviour of Jackass Penguins were examined by running standard transects with a sail boat in waters close to the birds' breeding islands. The use of a sail boat permitted close observation of foraging penguins with minimal disturbance. Penguin numbers at sea were lowest in December, when birds were confined to the breeding islands during moulting and were high in March and July during breeding peaks. While most penguin group sizes were small (one or two birds), over 44 % of penguins occurred in groups of more than 10 birds. Three stereotypic penguin group formations occurred: 'facing-search', 'line-abreast', and 'pointed-ovoid'. Penguins also foraged in association with other sea birds and marine mammals.

Includes abstract. / Includes bibliographical references (p. 156-171). / Biogeography is defined as the study of life, in a spatial and temporal context, with respect to the analysis and explanation of patterns for a given area. The tendency for species richness and diversity to increases towards the equator, where both peak, is a much debated and tested pattern. Underlying mechanisms thought to cause this pattern are: gradients in temperature, stress, productivity, competition, predation, stability, effective evolutionary time, niche breadth, range size and area of occupancy. Evidence exists that both supports and negates most of these mechanisms. In addition to the richness gradient, a latitudinal gradient in geographical range size exists, whereby species range sizes decrease with latitude, referred to as Rapoport's Rule. This has been linked to species ability to tolerate changes in climate. The latitudinal gradient in species richness is thought to be a by-product of Rapoport's Rule and the "Rescue Effect".