Physico-chemical conditions and macroinvertebrate fauna in the River Nile from Aswan to Cairo

This paper examines the distribution of benthic macroinvertebrates in relation to physico-chemical conditions along 1 035km of the River Nile from Aswan High Dam to Al Kanater Barrage, Cairo. Total Dissolved Salts and several individual chemical variables showed positive linear regression with distance from Aswan. The creation of the Aswan High Dam has reduced the ionic concentrations discharged to the Nile, but there is a gradual increase as the river flows though Egypt. Benthic macroinvertebrates show overall low taxon richness with taxa typical of a lowland riverine region. Changes in taxon richness appear to be influenced by either pollution and/or sedimentation. Sites downstream of the Kema Factory and downstream of organic discharge from Etsa Drain from Minia city show severe pollution. A Bray-Curtis Diversity Index shows these sites to be biodiversity outliers consistent with the negative impact of pollution. Examination of 95% outlying chemical values confirms gross pollution from these sites and the data as a whole suggest other sites that may also be affected by pollution. A contributor to high macroinvertebrate taxon richness appeared to be increased sedimentation, particularly in midstream samples. It is concluded that the low ionic concentrations resulting from the Aswan High Dam construction, localised pollution, and the occurrence of sediment are the main factors governing macroinvertebrate taxon richness. These factors will require careful monitoring, assessment and management if the biodiversity of the Nile is to be conserved.     

Bryophytes from some travertine-depositing sites in France and the U.K.: relationships with climate and water chemistry

Abstract

The bryophyte florash of 14 travertine-depositing sites in the French Alps and Britain were investigated and consisted of 34 taxa (26 mosses and eight hepatics), with the commonest species, Eucladium verticillatum and Palustriella (Cratoneuron) commutata, occurring in both countries. Species richness ranged from 3-15 and was related mainly to site size and heterogeneity with respect to water flow. Bryophytes grew within or close to Ca-bicarbonate waters with base concentrations (HCO₃ ) ranging from 1.42 to 7.58 mM at pH 6.9-8.3. P. commutata sensu lato was found to extend to more northerly sites in Europe than E. verticillatum, although the two species were frequently present at the same site. Principal component analysis suggested that the distribution of P. commutata var. commutata was influenced more by temperature than water chemistry.     

The impact of land use on water quality of the Lwiro River,Democratic Republic of Congo,Central Africa

The water quality of the Lwiro River, Democratic Republic of Congo (DRC), Central Africa, was investigated on a monthly basis from December 1999–October 2000, at six stations along a hydraulic gradient from source to mouth, to evaluate the impact of land use on temperature, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD₅), alkalinity and suspended solids. Upstream, where forests are conserved, minimal changes of physico-chemical parameters of water were observed. Downstream, DO was reduced, due to the increased organic matter content which increased the decomposition rate. BOD₅ and suspended solids increased downstream. Greater changes were found near agricultural areas and villages. Wetlands appear to mitigate BOD₅ and DO impacts.     

Four Cases of Syncarpy or ‘Double-Capsules’ in a Population of Bryum atropurpureum W. & M.

Abstract

Four cases of syncarpy are described from a single population of Bryum atropurpureum W. & M. A short discussion follows concerning the way in which this type of abnormality may arise, and it is suggested that an early cleavage in the young sporophyte affords the most reasonable explanation. The cases described are briefly compared with others that have been reported in the literature. Several species, belonging to unrelated genera, are instanced in this connexion.     

Domestic Water Use in Rural Semiarid Africa: A Case Study of Katarko Village in Northeastern Nigeria

Katarko village in the Sahel region of northeastern Nigeria relies entirely on natural sources of water such as rainfall and ground water. Thelatter is potentially the only constant source of water. This study is based on primary data collected in Katarko during a period of 8 months in 1996. Analysis indicates that per capita daily water consumption is higher (44.9 l) in the rainy season than in the dry season (26.1 l). The proportion of households who useless than 150 l per day, the minimum daily requirement recommended by the World Health Organization (Dieterich & Henderson, 1963) increases from 29% during the rainy season to 67% during the dry season. Most households prefer to use water of poor quality that is to be found closer to their homes to traveling long distances to or spending extra time at the water sources to obtain good quality water. Poor water quality, appalling sanitation, and unhygienic water-handling practices, particularly during the dry season, contribute to the high incidence of diarrhea in the village.     

Physico-chemical and macrobenthic faunal characteristics of Kuramo Water,Lagos, southern Nigeria

A five-month study in 2001 of an enclosed lagoon, Kuramo Water in southern Nigeria, exposed to urban perturbation describes its physical, chemical and macrobenthic invertebrate characteristics. Of the 16 physical and chemical conditions studied at four sites within the bank-root biotope, only BOD and TDS content were significantly different between sites. The elevated level of these perturbation indicators could be related to the raw and treated domestic sewage released directly into Kuramo Water from point and non-point sources. A total of 16 taxa and 691 macrobenthic individuals belonging to 11 families were recognised at the study sites. A naidid and a chironomid species were the most abundant, occurring in high numbers throughout. Other invertebrate groups occurred in low numbers. The diversity indices calculated supported this trend. The generally low diversity further supports the observation that Kuramo Water is a disturbed environment. The absence of molluscs in the benthic invertebrate samples of this study, compared to their dominance in earlier studies of Kuramo Water, reflects a modification in the habitat resulting from a change in the salinity from brackish to freshwater.     

Developing a protocol for managing the biophysical condition of a water management area: the Sabie catchment case study

Recent modification of the South African Water Law spells out fundamental changes for the way the country's water resources will be managed in the future. One of the most significant mandates is the establishment of Catchment Management Agencies (CMAs) and the delegation of water resource management responsibilities to these institutions. Their function will focus on the overall management of water resources on a catchment basis. Within the context of the new legal framework, there is a great need for support to CMAs, particularly in providing them with procedures for the optimal management of water resources in order to ensure a balance between sustainable use and protection of the resource. This paper describes a research project that aims to develop a protocol for the integrated management of the biophysical component of a catchment, with particular focus on river systems. This protocol will be a management tool for Catchment Management Agencies in support of more integrated and sustainable water resource management.

South Africa's Sabie-Sand catchment was selected as a case study area for several reasons. This catchment has a large number of current and historic water resource related initiatives, such as the Working for Water Programme (alien plant clearing), the River Health Programme (river quality assessment) and The Kruger National Park Rivers Research Programme (a river management programme). In addition the diversity of stakeholders and land-use issues in the catchment and the extensive collection of available information relating to water use and protection for this catchment makes the Sabie-Sand a rich learning ground.

This project aims to use information from the Sabie catchment to produce and implement a protocol which will combine and integrate the knowledge of water resource management from diverse but related fields in order to enhance catchment-based integrated water resource management. It also aims to extract and document lessons from current research initiatives, to assess the usefulness and relevance of their products for CMAs and to identify gaps in the research framework that need to be addressed in order to meet the water resource management needs of CMAs. This paper reports on the project development during its first phase, describes the next steps in the research process and provides a conceptual framework of how the research team envisages the practical implementation of the protocol.     

Water policy in southern Africa: A brief synopsis of some of the macro driving forces

The water sector reforms that are underway in many parts of southern Africa are a manifestation of a global phenomenon. This is rooted in the human response to the undesirable consequences of development, and seeks to introduce the notion of sustainability into the modern development discourse. This has given rise to an academic discipline that is known as political ecology, which seeks to understand the political construction of environmental knowledge. As it is currently formulated, political ecology is highly Eurocentric, meaning that African scholars should become engaged in its intellectual development. This political ecology discourse is relatively new in southern African academic circles, and can be helpful in explaining dynamics that are shaping the World Water Vision, Global Water Partnership, World Commission on Dams and the United Nations Framework Convention on Climate Change, all of which are relevant in the contemporary water sector.     

Fish community response to increased river flow in the Kariega Estuary,a freshwater-deprived,permanently open southern African system

The littoral and demersal ichthyofaunal community structure in the freshwater-deprived, permanently open Kariega Estuary was investigated following heavy rain in November 2006 and was compared to low-flow condition data from 1991 and 1996. All surveys took place during the spring months and allowed for a comparison of a wet and a dry spring period. The 2006 freshwater pulse generated a strong horizontal salinity gradient within the estuary. In the absence of freshwater inflow, the ichthyofaunal community in the littoral zone was numerically dominated by estuarine resident species, whilst after the freshwater pulse an increased contribution of marine migrant species was observed. Within the demersal zone, marine straggler species dominated during the dry spring period and estuarine residents during the wet spring period. Numerical analyses of the littoral and demersal fish assemblages indicated the presence of three distinct groupings — corresponding to the upper and middle reaches during separate wet and dry periods, and a community associated with the lower reaches of the estuary. It is suggested that the shift in community structure between the dry and wet spring periods could be related to altered physico-chemical and trophic conditions within the estuary, as well as the increased presence of freshwater and estuarine olfactory cues within the coastal zone, which would have resulted in the recruitment of 0+ estuary-associated marine species into the Kariega system.     

Groundwater quality monitoring around Bass Lake,Betty's Bay,South Africa

The study involves the analysis of groundwater around Bass Lake, part of a fragile black water lake system situated along a narrow coastal plain in the southern Cape, in order to establish the quality of the water and to identify the sources of pollution. The study was conducted in 1998 during the winter season in which water samples were taken from Bass Lake and from eight wellpoints surrounding the lake. The samples were analysed for traces of faecal pollution, nutrient concentrations, pH and conductivity. The results of these tests showed that the water is relatively uncontaminated during the winter season. Only slight contamination was found at one sampling site. However there was enough secondary evidence to suggest that the lake had being reasonably polluted at various times of the year. This evidence was in the form of medical reports, changes in the natural vegetation and incidences of algal blooms. It is expected that significant contamination only occurs during the summer time, when the visitor occupancy rate in the surrounding houses is high and consequently ther is an increase in the volume of waste water and sewage received by domestic sewage systems. The study suggests that water monitoring methodology used in this study should yield better results during the drier summer period when there is decrease in the rate of groundwater flow and a lower water table. Monitoring throughout the year is recommended.