Bibliography: p. 177-205. / The Kruger National Park (KNP) in the Eastern Transvaal provides a classic example of the potential conflict of interests between the industrial, agricultural and domestic sectors and conservation. The KNP is situated on the north-eastern border of South Africa and receives the flow of six rivers (Figure 0.1), all •of which originate outside the jurisdiction of the Park authorities. Thus, there are demands for water outside the boundaries of the KNP from other sectors of South Africa, as well as several self-governing states that have been set up as political entities within South Africa (see Chunnett, Fourie & Partners 1987, 1990). Due to human development •of catchments there has been regulation of these rivers, which are rapidly changing in terms of their flow regimes. (O'Keeffe. & Davies 1991). For example, the Letaba and the Luvhuvhu rivers have both changed from perennial to annual flow regimes (O'Keeffe & Davies 1991), a condition which is detrimental to the maintenance of river ecosystem functioning, while the Crocodile River has been regulated to an almost unvarying flow of ca 5m3 s•1 (O'Keeffe & Davies 1991). Recognising the need to address the problem of water allocation to the KNP, the Department of Water Affairs (DW A) convened a workshop on minimum flow needs for the environment in 1987 (Bruwer in press). Although tentative values were suggested for minimum flows, the value of the workshop was its recognition of the need for more research into the problem. Such research is currently being undertaken under the auspices of the multi-disciplinary KNP Rivers Research Programme. The goal of the programme is to " ... develop the means to predict the impact on the KNP river systems of changing flow regimes and water quality as the basis of a protocol for managing the• allocation of water for ecological purposes" (Kruger National Park Rivers Research Programme 1990). One of the studies initiated within this programme was a pre-impoundment study of the Sabie River, including its main tributary, the Sand River, which together are referred to as the Sabie-Sand River system.

Includes bibliographical references. / There have been several expeditions to Marion and Prince Edward Islands (MPE) which have sampled the marine fauna and flora, including those of the British ships Challenger (1873-1876) and Discovery (1935), and subsequent surveys by the French ship Marion-Dufresne (Arnaud and Hureae, 1979). South African research began with land-based surveys that concentrated on the intertidal and shallow-water benthos and included work by Fuller (1967), Van Zinderen Bakker et al 1971 ), De Villiers (1976) and Blankley & Grindley (1985). More recently this research was extended offshore by the University of Cape Town, with dredging being undertaken from the SA Agulhas over the period 1984-1989 (GM Branch, Attwood, Gianakouras and ML Branch, 1993) and a quantitative SCUBA survey at depths of 5, 10 and 15m at Bullards Bay, Transvaal Cove and Trypot Point (Beckley and Branch, 1992). The identification of benthic species posed a major problem during each of the recent surveys, despite the fact that the material from earlier expeditions has been referred to international taxonomic authorities. Reference specimens are not available or are housed in European collections. The number of species from the area has also increased considerably. Previous work in the subantarctic has been undertaken by scientists from a large number of countries and over a protracted period of time. Isolated detailed monographs reviewing particular groups have appeared, but these remain largely inaccessible to the more generalist worker. Furthermore many are now out-of-date in terms of the nomenclature employed. This situation prompted the compilation of the present series of identification guides, which are intended to synthesise information on the benthic invertebrate fauna of Marion and Prince Edward Islands and to present it in a manner that will allow relatively easy identification by the non-specialist.

Includes bibliographical references. / There are at least 500 species of sharks inhabiting the world's oceans and very little is known about the reproductive biology of most of these species. By observing Scyliorhinids, which exhibit oviparous reproductive behaviour, we can further understand the nature of elasmobranch reproductive behaviour, including embryo growth and development. Two Scyliorhinid species endemic to South African waters are investigated here, Poroderma pantherinum, commonly known as the Leopard catshark and Haploblepharus pictus the Dark shyshark. Observations were made both in the field and in the laboratory to ascertain differences in reproductive behaviour. In the field P. pantherinum laid their eggs at an average depth of 15.7 m - ? 28.8 and their preferred choice of substratum, onto which their eggs were singly attached, were seafans. H. pictus, on the other hand, laid their eggs at an average depth of 3.9 m - ? 15.9 and their preferred choice of substratum, onto which they attach their eggs predominantly in pairs, was the seaweed Bifurcariopis capensis.

Includes bibliographical references. / The South African Government introduced protective legislation prohibiting targeted fishing of the great white shark Carcharodon carcharias in 1991. This pre-emptive measure was intended to protect this species from increasing fishing pressure to allow researchers to gather information of this shark’s distribution, basic life history traits, breeding behaviour, and habitat use. Following this, the species conservation status was placed on CITES Appendix II and classified on the IUCN (International Union for the Conservation of Nature) Red List as Vulnerable. This thesis investigates white sharks at Gansbaai, in particular their occurrence, changes over time and the influence of environmental variables on their numbers there. The size and numbers of white sharks were recorded from an anchored cage diving vessel over a five-year period between 2007 and 2011. The study was conducted around Dyer Island and the inshore region of Gansbaai in the Western Cape of South Africa. A change in size frequency between seasons suggests that the white sharks are not resident for long periods, but that different size classes use the coastal bay at different times. There was a statistically significant change of size distribution over the five years for both male and female sharks. The trend of larger sizes recorded later in the study could infer a change in the cohorts visiting the bay or growth of the same individuals exhibiting site fidelity to the area.

This study has shown that using active rehabilitation in combination with improved management strategies (e.g. rest from grazing) may induce recovery of certain ecosystem services within practically relevant time scales. However, these benefits might not be tangible for landowners or society as of yet, due to the small-scale nature of the rehabilitation application along with the relatively high, short-term associated costs. To alleviate financial constraints on farmers and in order to socially and financially enhance local communities, the focus for now should be on sourcing funds from government and private sectors for rehabilitation implementation.

Includes bibliographical references. / The bank cormorant Phalacrocorax neglectus was listed as ‘Endangered’ in 2004, following a decrease of more than 60% in the total population from 1975-2011. It ranges from central Namibia to the Western Cape, South Africa, with most of the population occurring on offshore islands in Namibia. The main reason for this study was to determine if climate change could be identified as a factor which has influenced the decreasing numbers of bank cormorants. This involved research on the heat stress behaviour, breeding success and population trends of the bank cormorant in the Western Cape, South Africa. High environmental temperatures resulting in heat stress and storms with associated extreme environmental variables was predicted to cause breeding failures, decreasing breeding success. As a result, climate change can also affect long-term trends in the adult population of the bank cormorant, and this was examined using the population data of nine bank cormorant colonies in the Western Cape, South Africa. A link existed between ambient and operative temperature, and the latter was used for statistical analysis. Mean operative temperatures of over 30°C were experienced. Temperatures were highest at the bank cormorant colony at Robben Island when three colonies were compared (Robben Island, Jutten Island and Stony Point). Increased environmental temperatures resulted in the average bank cormorant increasing its time spent employing thermoregulatory behaviour. Bank cormorants were shown to start gular fluttering at 21°C on average and spend all their time gular fluttering when they experienced an operative temperature of 34.2°C or higher. The birds also started employing this thermoregulatory behaviour at a lower temperature when on eggs or small chicks. During the study period, the breeding success of the bank cormorant was not impacted by high temperatures at the three bank cormorant colonies studied. Wave and wind action, associated with storms, resulted in a lowered reproductive output during the breeding seasons of 2012 and 2013. Both incubation success and chick rearing success did not differ significantly between 2012 and 2013 for the three bank cormorant colonies at Robben Island, Jutten Island and Stony Point. The study of long-term trends in colony sizes of nine bank cormorant colonies in the Western Cape, South Africa revealed a decrease in the bank cormorants breeding population. The decrease could not be directly associated with climate change in the region. An increase in the mean maximum temperatures and a decrease in the annual rainfall did not affect the bank cormorant numbers, but rather the fecundity. This resulted in a lagged effect of climate change on the bank cormorant population. Climate change and extreme weather events can cause massive breeding failures.

Bibliography: pages 113-117. / Factors affecting habitat separation in Pallid Flycatchers Melaenornis pallidus and Marico Flycatchers Melaenornis mariquensis were studied from June 1980 to June 1982 at the Nylsvley Nature Reserve in the central Transvaal. The main emphasis of the study, which is divided into two sections, was to determine the effect of habitat and resource conditions on the flycatchers' foraging behaviour (Section I) and other aspects of their ecologies (Section II) with the aim of evaluating the relative importance of these effects in maintaining habitat separation between the two species.

Bibliography: leaves 44-53. / 13C/12C and 15N/14N were used to indicate the trophic levels of the shallow-water Cape hake, Merluccius capensis (Castelnau) at three sites on the west coast of South Africa, and five sites on the south coast. Gut content analyses show only the very recent diet of hake, therefore stable carbon and nitrogen isotope ratios were used to show the longer-term diet, integrated over the turnover time of the muscle tissue and bone collagen analysed. 13C/12C is 1-2%₀ higher in the tissues of a consumer than its diet (DeNiro and Epstein 1978), the difference in 15N/14N between a consumer and its food being 3-4%₀ (DeNiro and Epstein 1981). Both 13C/12C and 15N/14N indicate trophic enrichment between hake muscle tissue and bone collagen, and the gut contents and prey, and show that small and large hake feed at different trophic levels, large hake tissues being slightly heavier in 13C than small hake tissues, and containing 2-4%₀ more 15N than muscle tissue and bone collagen, and the gut contents and prey, and show that small and large hake feed at different trophic levels, large hake tissues being slightly heavier in 13C than small hake tissues, and containing 2-4%₀ and more 15N than muscle tissue and bone collagen of small hake.

Includes bibliographical references (leaves 63-84). / Several intrinsic (body size) and extrinsic (foraging ecology and communication) factors are suggested to influence call frequency divergence in high duty-cycle bats. Investigating these factors within the framework of established hypotheses would contribute to understanding evolutionary changes leading to speciation in bats. Here, acoustic divergence between populations of the endemic Cape horseshoe bat, Rhinolophus capensis was investigated at both inter- and intraspecific levels. No previous study has investigated geographic variation in echolocation calls of R. capensis. Body size, wing morphology and skull parameters associated with diet and echolocation call production and reception, were compared between populations. Adult R. capensis were sampled at three sites: De Hoop situated in the centre of the species distribution in the Fynbos biome; Steenkampskraal and Table Farm were ecotone populations situated in the western and eastern limits of the distribution, respectively. Interspecific analysis revealed that the two ecotone populations deviated slightly from the allometric relationship between body size and peak frequency for the African clade. In fact, the expected inverse relationship between body size and peak frequency was not evident across populations. Ecotone populations had significantly larger mean body sizes than the population at De Hoop (10.28 ± 1.08 g; 84.60 ± 0.82 kHz). However, one population in the ecotone had the highest frequency (Table Farm: 13.88 ± 0.87 g; 85.84 ± 0.73 kHz) while the other had the lowest (Steenkampskraal: 13.15 ± 0.95 g; 80.66 ± 0.50 kHz). Several hypotheses were considered to explain the patterns of echolocation and morphological variation observed. The larger body size of the ecotone populations may be explained by James' Rule or it may be an adaptation to the intrinsic habitat heterogeneity of ecotones as it affords these bats a greater niche width and possibly larger home ranges to access spatially separated resources. On the other hand, neither climatic (humidity hypothesis), habitat (foraging habitat hypothesis) nor dietary differences (prey detection hypothesis between populations were responsible for the observed peak frequency differences between populations. Nasal chamber area was the best predictor of peak frequency and there was no relationship between the area of the nasal chamber and body size. Thus, selection may have acted directly on peak frequency altering skull parameters directly involved in echolocation independently of body size. Within each population, females were larger and used higher frequencies than males, which implies a potential social role of peak frequency for R. capensis. Observed differences in peak frequency may be because R. capensis interacts with separate rhinolophid species at either end of its distribution (Steenkampskraal: R. swinnyi; Table Farm: R. darlingi) in addition to R. clivasus, which results in the evolution of local dialects to facilitate intraspecific communication. These local dialects, possibly brought about by differences in local ambient noise characteristics (e.g. chorusing insects), could be maintained via cultural transmission. However, the role of gene flow for the evolution of these local dialects between populations cannot be discounted without adequate genetic analyses.

Bibliography: leaves 68-83. / In this thesis the use of the jackass penguin Spheniscus demersus as a sampler of the marine environment is assessed. Between February 1987 and July 1988, 638 monthly diet samples were obtained from adult jackass penguins at west - (Marcus and Jutten Islands) and southwest-coast (Dyer Island) colonies off South Africa, supplementing data collected since 1980. Penguin diet was compared over time and between colonies in order to establish the presence or absence of qualitative changes or quantified trends in the biology of pelagic schooling fish species important to the South African purseseine fishery, viz. anchovy Engraulis capensis, pilchard Sardinops ocellatus, maasbanker Trachurus trachurus and red-eye Etrumeus whiteheadii. The principal prey of jackass penguins and major contributor to commercial catches is anchovy and, consequently, the biology of this fish species was emphasized. Monthly and annual trends in prey composition and anchovy size-range were related to the availability, abundance and distribution of the penguins' prey species in the marine environment.