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AN ASSESSMENT OF THE POTENTIAL IMPACT OF ALIEN INVASIVE VEGETATION ON THE GEOMORPHOLOGY OF RIVER CHANNELS IN SOUTH AFRICA 外来入侵植被对南非河道地貌的潜在影响评估
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631311
K. Rowntree
{"title":"AN ASSESSMENT OF THE POTENTIAL IMPACT OF ALIEN INVASIVE VEGETATION ON THE GEOMORPHOLOGY OF RIVER CHANNELS IN SOUTH AFRICA","authors":"K. Rowntree","doi":"10.1080/10183469.1991.9631311","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631311","url":null,"abstract":"Summary Invasion of the riparian zone by alien vegetation is recognised as a serious problem in many areas of South Africa. Vegetation is a dynamic component of river channels. It is an important control variable affecting channel form whereas the flow and sediment regime influences vegetation growth. Wherever alien vegetation invades the riparian zone it can be expected that there will be some impact on the physical structure of the riparian habitat. This paper reviews the effect of riparian vegetation on channel processes and channel form and discusses the implications of the invasion of riparian zones by alien vegetation. Woody species in particular are seen as having a significant potential for inducing channel modification, whilst their removal could lead to significant channel instability and mobilisation of sediment. The need for further research into the impact of alien vegetation on the geomorphology of South African river channels is stressed.","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123140635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 57
THE BENTHIC MACROINVERTEBRATE FAUNA OF A SOUTH AFRICAN MOUNTAIN STREAM AND ITS RESPONSE TO FIRE 南非山间溪流的底栖大型无脊椎动物群及其对火灾的反应
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631313
D. L. Britton
{"title":"THE BENTHIC MACROINVERTEBRATE FAUNA OF A SOUTH AFRICAN MOUNTAIN STREAM AND ITS RESPONSE TO FIRE","authors":"D. L. Britton","doi":"10.1080/10183469.1991.9631313","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631313","url":null,"abstract":"Summary The effects of a late-summer prescribed burn on the temperature and benthic macroinvertebrate fauna of a south-western Cape mountain stream were investigated over a period of 12 months. Temperature and discharge regimes appear well-defined and relatively predictable from year to year. As in other mediterranean-type ecosystems, seasonal changes in the structure of the invertebrate community and the relative abundance of different feeding groups appear to be associated primarily with changes in the physical environment. Distinctive summer and winter communities were identified, with chironomids dominating the fauna in summer and simuliids dominant in winter. Although the riparian vegetation was only slightly damaged by the fire, a heavy, aseasonal leaf-fall occurred shortly afterwards. The canopy remained sparse for approximately four months. Stream temperature in the post-burn year was not demonstrably affected by increased exposure to solar radiation, however, probably because the canopy remained ...","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121511091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 15
GEOGRAPHICAL TRENDS IN THE WATER CHEMISTRY OF WETLANDS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA 南非西南开普省湿地水化学的地理趋势
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631315
M. Silberbauer, J. King
{"title":"GEOGRAPHICAL TRENDS IN THE WATER CHEMISTRY OF WETLANDS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA","authors":"M. Silberbauer, J. King","doi":"10.1080/10183469.1991.9631315","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631315","url":null,"abstract":"Summary Although it is becoming increasingly important for the aquatic chemistry of wetlands to be understood, little chemical information is available for the wetlands of South Africa. During a project aimed at beginning to redress this gap in our knowledge, conductivity and pH measurements were made at 73 wetlands in the south-western Cape Province. The concentrations of the major cations and anions were determined in samples from 42 of these wetlands. Total dissolved salts (TDS) concentrations ranged from below 20 mg l−1 to more than 200 000 mg l−1, and pH values as low as 4 and greater than 10 were recorded in some wetlands. Despite these extremes, the ionic ratios showed regional trends: Na+ and Cl are the dominant ions in wetlands near the coast, and HCO3 is the dominant anion in inland wetlands. Since the biological components of wetlands are dependent on the water chemistry, it is essential that the side-effects of any developments in a wetland or its catchment be carefully considered in the light...","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"242 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131775353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 25
CIRCULATION IN HIGHLY STRATIFIED SOUTHERN AFRICAN ESTUARIES 高度分层的南部非洲河口的环流
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631317
J. Largier, J. Slinger
{"title":"CIRCULATION IN HIGHLY STRATIFIED SOUTHERN AFRICAN ESTUARIES","authors":"J. Largier, J. Slinger","doi":"10.1080/10183469.1991.9631317","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631317","url":null,"abstract":"Summary The nature of estuarine circulation under highly stratified conditions is reviewed in the context of southern African estuaries that are small and have a constricted connection to the ocean. While the focus is on the generic hydrodynamic processes and features, attention is given to field observations from a particular estuary as a way of illustrating these processes and features. Notable features are the tidal intrusion front, the bottom density current and the long-residence deep water in the upper estuary. The important hydrodynamic processes, which account for these features, are internal hydraulic control of exchange through the mouth, buoyancy-driven landward intrusion of sea water, upward shear-driven entrainment and ebb tidal outflow. The context in which these processes and features are expected to occur is addressed through a discussion of seasonal variations in the prototype and through a discussion of these features observed in other southern African estuaries. A distinction is made be...","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133714332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 14
FISH CONSERVATION IN SOUTH AFRICAN ESTUARIES: PRESSURES, PROBLEMS AND PROSPECTS 南非河口鱼类保护:压力、问题和前景
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631310
D. Cyrus
{"title":"FISH CONSERVATION IN SOUTH AFRICAN ESTUARIES: PRESSURES, PROBLEMS AND PROSPECTS","authors":"D. Cyrus","doi":"10.1080/10183469.1991.9631310","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631310","url":null,"abstract":"Summary A review of the conservation status of fish in the estuarine environment around the South African coastline reveals that some species face serious problems associated either with habitat destruction, and its associated biological, physical and chemical components or exploitation. The 65 species considered fall into three categories; truly estuarine species, which are dependent on estuaries for their entire life; marine species dependent on estuaries during the juvenile phase of their life cycle; and marine species whose juveniles occur mainly in estuaries but are also found at sea. Included in the first two categories are 14 species of fish which are on the South African Red Data list. These comprise one species which is endangered, five which are vulnerable and eight which are rare. All groups are considered in relation to factors in estuaries which are affecting their populations. A conservation strategy is suggested for certain estuarine types or for specific estuaries which could ensure the su...","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"03 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127192509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 25
THE DISTRIBUTION OF WETLANDS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA 南非西南开普省湿地的分布
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631314
M. Silberbauer, J. King
{"title":"THE DISTRIBUTION OF WETLANDS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA","authors":"M. Silberbauer, J. King","doi":"10.1080/10183469.1991.9631314","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631314","url":null,"abstract":"Summary The hydrological and habitat value of wetlands is beginning to be recognised in South Africa, but only in parts of Natal Province has an effort been made to map wetlands and to record their status over large areas. While the most accurate method of mapping wetlands is a combination of photogrammetry and field surveys, this is time-consuming and expensive. An alternative “desktop” method was therefore used to draw up a preliminary distribution of wetlands in the south-western Cape Province, and this approach consisted of summarising the information contained on 1:50 000 topographical survey maps. The summary shows that shallow, vegetated wetlands (vleis) occur mainly in the wetter south and south-west of the region, while the non-perennial wetlands (pans) predominate inland, where the land is dryer and flatter. There are many estuarine wetlands along the coast, resulting from the tendency of river mouths to be blocked by sand-bars. Farming requirements and suitable topography account for the many s...","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128887226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 17
ENVIRONMENTAL CORRELATES OF PLANT SPECIES DISTRIBUTION ON THE NYL RIVER FLOODPLAIN 尼龙河漫滩植物种类分布的环境相关因素
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631312
M. Coetzee, K. Rogers
{"title":"ENVIRONMENTAL CORRELATES OF PLANT SPECIES DISTRIBUTION ON THE NYL RIVER FLOODPLAIN","authors":"M. Coetzee, K. Rogers","doi":"10.1080/10183469.1991.9631312","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631312","url":null,"abstract":"Summary The envisaged construction of a dam on a major tributary of the Nyl River will alter the hydrological regime with consequent effects on the structure and functioning of the downstream floodplain ecosystem (Nylsvley). Attempts to minimise this impact will be facilitated by knowledge of relationships between vegetation structure and key environmental variables. Historically flooding regime, and its co-variables, have been assumed to be the most important environmental factors controlling the distribution of floodplain plant species. Canonical correspondence analysis of selected soil characteristics (soil texture, electrical conductivity, pH and bulk density), elevation and plant abundance was carried out on the Nylsvley Floodplain in order to critically examine the assumption that flooding regime, measured as elevation, is the primary correlate of floodplain plant species distribution. Results indicate that, although flooding regime is the primary correlate of plant species distribution, other edaph...","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127637868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
CONSERVATION IN THE MARINE ENVIRONMENT: SOME PROBLEMS WITH THE MANAGEMENT OF SHORE-ANGLING IN THE SOUTHWESTERN CAPE 海洋环境保护:西南角岸线垂钓管理的若干问题
Southern African Journal of Aquatic Sciences Pub Date : 1991-06-01 DOI: 10.1080/10183469.1991.9631309
B. Bennett
{"title":"CONSERVATION IN THE MARINE ENVIRONMENT: SOME PROBLEMS WITH THE MANAGEMENT OF SHORE-ANGLING IN THE SOUTHWESTERN CAPE","authors":"B. Bennett","doi":"10.1080/10183469.1991.9631309","DOIUrl":"https://doi.org/10.1080/10183469.1991.9631309","url":null,"abstract":"Summary Recreational shore angling is a very important sector of South Africa's diverse marine fisheries. The number of anglers participating in this sport is increasing at 6% per annum and currently stands at approximately 380 000. This number is expected to exceed one million within 20 years. The catch rates of many species caught from the shore have declined markedly for at least 50 years and the species composition of the catch has changed. This indicates that stocks of many species are overexploited and that effort increases cannot be sustained. Measures introduced to conserve these stocks appear to have been largely unsuccessful because they do not have the support of many anglers and they are ineffectively policed. It is concluded that, in order to sustain this fishery, current legislation needs to be improved and that a licensing system for anglers should be introduced through which an education campaign can be channelled.","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"896 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132347970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 14
Evaluation of a Computer Model for the Selection of Candidate Species for Aquaculture 水产养殖候选物种选择的计算机模型评价
Southern African Journal of Aquatic Sciences Pub Date : 1990-06-01 DOI: 10.1080/10183469.1990.10557369
P. Cook, R. Walmsley
{"title":"Evaluation of a Computer Model for the Selection of Candidate Species for Aquaculture","authors":"P. Cook, R. Walmsley","doi":"10.1080/10183469.1990.10557369","DOIUrl":"https://doi.org/10.1080/10183469.1990.10557369","url":null,"abstract":"Summary The use of a computer-based “Expert Choice” system, incorporating the Analytical Hierarchy Process, in the selection of candidate species for aquaculture is described. The system is considered to be particularly useful in developing countries or areas where the aquaculture industry is poorly developed. As an example, a model was developed to assess the potential of species for marine aquaculture in South Africa. Limitations of the system and precautionary considerations are discussed.","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125451688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Pitfalls in the Presentation of Chemical Data 化学数据表示中的陷阱
Southern African Journal of Aquatic Sciences Pub Date : 1990-06-01 DOI: 10.1080/10183469.1990.10557364
J. Day
{"title":"Pitfalls in the Presentation of Chemical Data","authors":"J. Day","doi":"10.1080/10183469.1990.10557364","DOIUrl":"https://doi.org/10.1080/10183469.1990.10557364","url":null,"abstract":"Summary Biologists in the aquatic sciences are often guilty of numerous errors in the presentation of their chemical data. This paper reviews the use of units in the representation of the inorganic constituents of aquatic solutions for their benefit. It explains the relationship between salinity, total dissolved solids and conductivity, and between the amount of substance and concentration, and specifies conditions in which each can be used. Methods for the mathematical verification of analytical results are briefly discussed. Tables of recommended units, conversion factors and molar conductivities are provided. It is concluded that chemical data can easily be reported correctly and that both authors and referees have a duty to ensure that this is done.","PeriodicalId":161337,"journal":{"name":"Southern African Journal of Aquatic Sciences","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131477604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 9
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