ISSN:0035-919X    

DOI:10.1080/00359199809520369

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Three South African beaches, King's Beach, Joorst Park and Sardinia Bay, with different levels of development, were selected to study the recreational use patterns over a holiday cycle by means of aerial photography and questionnaire surveys. King's Beach was classified as developed, Joorst Park as semi-developed and Sardinia Bay as undeveloped on the basis of the number of facilities present. Differences in popularity, use patterns, size and age composition of visitor groups, times of peak visitor abundance, types of accommodation and transport used, distance travelled and time spent on the beach were observed. The most developed beach consistently received the most visitors (of higher socio-economic level) as determined by visitor abundance at 11:00, except on New Year's Day, when the semi-developed Joorst Park received the highest numbers of visitors (6 500). This beach, frequented mainly on public holidays by visitors of a low socio-economic level from the nearby township, remained relatively unused during the rest of the holiday season. The other beaches, in contrast, were more continually used by visitors with private cars. Visitor group size was largest at the semi-developed Joorst Park. Visitors older than 50 years were more abundant at the undeveloped Sardinia Bay than at the other beaches, seeking the peace and quiet that this beach provides. Camping was most prevalent amongst the visitors to Joorst Park due to lack of other cheap accommodation there. Also, visitors to Joorst Park stayed on the beach for longer periods and a higher percentage of the respondents travelled long distances to the beach than on the other beaches. Although recreation patterns were linked to the level of beach development, other factors not related to beach development, such as cultural/ethnic background, political/historical influences, socio-economic level of beach users and distance of the beach from the visitor's home also played an important role. Environmental education emerges as one of the most urgent needs to properly manage dune and beach use in South Africa.

ISSN:0035-919X    

DOI:10.1080/00359199809520355

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The coastal river systems on the west coast of South Africa from the Orange River to the Groot Berg were surveyed during the period September to October 1993. The ichthyofaunal and physicochemical characteristics of each system are discussed in relation to their suitability as estuarine nursery areas. Of the fifteen systems sampled, only three appeared to exhibit any estuarine characteristics in terms of their fish fauna. Of the remainder, one system was a coastal lake system which had been severely altered and eleven were either dry river beds or semi-permanent waterbodies which are normally isolated from the sea and appear to be of little value as habitat for either resident or estuarine-dependent marine fishes. The systems on this arid coast are, however, very important habitats for migratory and resident waterbirds.

ISSN:0035-919X    

DOI:10.1080/00359199809520356

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The coastal river systems on the south-west coast of South Africa from Cape Columbine to Cape Point were surveyed during October and November 1993. The ichthyofaunal and physico-chemical characteristics of each system are presented and their suitability as estuarine nursery areas is discussed. Of the 16 coastal systems sampled along this coast, eight are seasonal streams which, due to their ephemeral nature, offer little permanent habitat for fishes. One system is severely altered; it has been canalised and receives both domestic and industrial effluents. Six systems have permanent water but their fish fauna appears to be restricted and they probably have a limited estuarine nursery potential. Only one system appears to serve a viable estuarine nursery function for fishes.

ISSN:0035-919X    

DOI:10.1080/00359199809520357

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Lake Hartbeespoort is subject to an unusual combination of physical conditions, in that it lies in a summer rainfall zone where the weather and climate vary dramatically over time-scales stretching from hours to millennia, the land morphometry is irregular and scum affects radiation absorption in the lake.

ISSN:0035-919X    

DOI:10.1080/00359199809520358

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effects of food supplementation on aMastomys natalensispopulation were experimentally studied in a grassland habitat in Swaziland. Food was added bi-weekly to two 1 ha grids, while a single 1 ha grid served as the control. Mice were trapped monthly over a twelve month period. Food supplemented grids supported more than twice the number of mice than the control grid. This increase was a consequence of high rates of immigration onto the supplemented grids. Food supplementation also extended the breeding season of the females by at least two months, but not of the males. Late in the dry season (August—October) the mean mass of mice was higher on the supplemented grids. Monthly residency rates were higher on the supplemented grids immediately after supplementation (July—August), and during mid-summer (December—February). The presence of extra food, however, did not prevent the spring (October—November) decline.

ISSN:0035-919X    

DOI:10.1080/00359199809520359

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Since the late 1970s, El Niño episodes have been unusually recurrent, while the frequency of strong La Niño events has been low. With the long El Niño sequence of 1991–1995, concern has been expressed about the possibility of climatic change in the equatorial Pacific. However, changes in the frequency of El Niño-Southern Oscillation events and earlier persistent El Niño and La Niño sequences can he detected in the historical and palaeoclimatic records. The recurrent warm event conditions of the first half of the 1990s are the result of the persistence of an anomalously warm pool near the date line which shifted the main centre of convection over Indonesia toward the centre of the equatorial Pacific Ocean. The eastward shift of the convection centre has allowed the penetration of westerly wind anomalies, associated with Madden-Julian wave activity, further into the western and central Pacific, thus initiating sequences of downwelling Kelvin waves. It has been suggested that the warm pool near the date-line may be a result of an abrupt warming trend in sea-surface temperatures throughout the tropical Indian and Pacific oceans. The abrupt warming has been attributed to the enhanced-greenhouse effect, but may equally be indicative of inter-decadal variability. The recent changes in El Niño events are therefore not necessarily an indication of climatic change. Although the generally dry conditions over parts of southern Africa over the last 15–20 years may he attributed in part to the relatively high ratio of warm to cold events, no long term change in the mean annual rainfall of the subcontinent can be implied at this stage.

ISSN:0035-919X    

DOI:10.1080/00359199809520360

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this article fixation and embedding procedures compatible with preparation of animal tissues for immunocytochemistry are reviewed. A number of methods is available for light microscopic immunocytochemistry: these include cryostat, freeze-dried and wax sections of tissue fixed with either vapour or immersion fixatives. Use of the microwave oven to fix tissues for immunocytochemistry is also discussed. Fixation methods for immuno-electron microscopy have centred largely around modification of routine procedures. New fixatives and quick-freeze/freeze-dry methods, which are making an important contribution to immuno-electron microscopy, are also dealt with. Embedding media include waxes and resins: the former are touched on, resins receive fuller treatment. The importance of expoxy and acrylic resin embedding for light microscopic immunocytochemistry is highlighted, as is the use of low-freezing-point resins for immuno-electron microscopy. The review covers antigen retrieval procedures—both enzyme and microwave methods—and the application of etching, bleaching and detergents to the pre-treatment of sections for immunocytochemistry.

ISSN:0035-919X    

DOI:10.1080/00359199809520361

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359199809520362

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359199809520363

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor