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  • Mkuranga Governance Baseline

    Torell, Elin; Mmochi, Aviti (Coastal Resources Center, University of Rhode Island, 2006)
    Mkuranga district is one of the six districts that form the Pwani Region (Figure 1). It was established in 1995, when the eastern part and coastal area of the Kisarawe district was cut off to form the district of Mkuranga. It is a relatively small district, covering 2,432 square kilometers, which is about a quarter of the size of Bagamoyo and about the size of the Zanzibar Islands. The district has about 90 kilometers of coastline, extending from the Temeke to the Rufiji districts. Like much of coastal Tanzania, the district is endowed with coral reefs, mangrove forests, and coastal fisheries. Remote unpopulated islands host endangered species such as the red colobus monkey and attractive birds. In Mkuranga, there are seven coastal villages: Shungubweni, Mpafu, Kerekese, Kisiju Pwani, Mdimni, Magawa, and Kifumangao and several near-shore islands, hosting the Boza, Kuruti, Kwale, and Koma villages (Mkuranga District Council 2002). Most of these villages are remote and naccessible, despite the relative proximity to Dar es Salaam.
  • Menai Governance Baseline

    Torell, Elin; Mmochi, Aviti; Palmigiano, Karen (Coastal Resources Center, University of Rhode Island, 2006)
    Menai Bay Conservation Area (MBCA) is situated in the southwest of Unguja, the main island of the Zanzibar Archipelago, and covers an area of 467 km² including 6 islets, with a seaward boundary close to 61 km offshore. It is the largest marine conservation area in Zanzibar, managed locally by the community and government officials with technical assistance by the World Wild Fund (WWF). The area is extensively covered with coral reefs, sea grass beds, and mangrove forest. The average water depth is 10 meters at high tide. The area had remained relatively undisturbed until the mid-1990s, when uncontrolled fishing pressures combined with destructive fishing techniques became a serious environmental concern
  • Bagamoyo governance baseline

    Torell, Elin; Mmochi, Aviti; Spiering, Penny (Coastal Resources Centre - University of Rhode Island, 2006)
  • Coral reefs and their management in Tanzania

    Wagner, G.M. (Western Indian Ocean Marine Science Association, 2004-12-30)
    Western Indian Ocean Journal of marine Science
    Coral reefs are very important in Tanzania, both ecologically and socio-economically, as major fishing grounds and tourist attractions. Numerous fringing and patch reefs are located along about two-thirds of Tanzania’s coastline. These reefs have been partially to severely degraded by human (primarily destructive fishing practices) and natural (particularly coral bleaching) causes. These immediate human causes have been brought about by various socioeconomic root causes, particularly poverty and lack of proper management. After decades of human and natural impacts there has been only limited reef recovery. This paper presents a region-by-region analysis of trends in the condition of coral reefs in Tanzania in relation to the causes of damage. While earlier approaches to management were aimed at non-use of coral reefs in marine protected areas (seldom achieved), recent approaches have aimed at integrated coastal management (ICM) (whether in programs or conservation areas), where zonation into core protected areas and multiple-use areas is based on participatory decision-making involving fishing communities and other stakeholders. Some management initiatives also involve communities in reef monitoring, restoration and ecotourism. This paper examines the management approaches and strategies implemented by various ICM programs, conservation areas and marine parks in Tanzania. It also provides recommendations for further research and coral reef management strategies.
  • Absolute migration and the evolution of the Rodriguez Triple Junction since 75 Ma

    Masalu, D.C.P. (2002)
    Tanzania Journal of Science
    The Rodriguez Triple Junction (RTJ) is a junction connecting three mid-ocean ridges in the Indian Ocean: the Southwest Indian Ridge (SWIR), the Central Indian Ridge (CIR) and the Southeast Indian Ridge (SEIR). The evolution of the RTJ has been studied extensively for the past 10 Ma and the triple junction is believed to be largely a ridge-ridge-ridge (RRR) triple junction. However, due to the scarcity of data its configuration prior to that period is poorly understood. The migration of the RTJ in the hotspot reference frame, for the past 75 million years has been mapped, by reconstructing its traces on the three plates (African, Antarctic and Indian) to their former positions. The results show that the RTJ has migrated northeasterly at velocities varying from 10cm/yr at 70 Ma to 2.6cm/yr at 43 Ma and thereafter 3.6–3.8cm/yr, in a fairly straight-line trajectory, suggesting a stable configuration of the RTJ since its formation. Because the RRR triple junction is the most stable configuration that is possible, it is suggested that the configuration of the RTJ has been largely RRR triple junction since its formation.
  • Mobility and immobility of mid-ocean ridges and their implications to mantle dynamics

    Masalu, D.C.P. (2002)
    Tanzanian Journal of Science
    In the past two decades, the mobility of mid-ocean ridges relative to the mantle (absolute migration) has been correlated with major observable features, such as spreading asymmetry and asymmetry in the abundance of seamounts. The mobility of mid-ocean ridges is also thought to be an important factor that influences the diversity of ridge-crest basalts. However, this mobility has not yet been defined and mapped. The absolute migration of global mid-ocean ridges since 85 Ma has been computed and mapped. Global mid-ocean ridges have migrated extensively at varying velocities during that period. Presently, the fast-migrating ridges are the Pacific- Antarctic, Central Indian Ridge, Southeast Indian Ridge, Juan de Fuca, Pacific-Nazca, Antarctic-Nazca, and the Australia-Antarctic ridges, migrating at velocities of between 3.3 and 5.5 cm/yr. The slow-migrating ridges are the Mid-Atlantic and the Southwest Indian ridges, migrating at velocities between 0.3 and 2.0 cm/yr. Comparison of these results with mantle tomography results show that the slow-migrating ridges have deeper depth of origin than the fast-migrating ones, suggesting a correlation between the absolute migration velocity and the depth of origin of ridges. Furthermore, the Southwest Indian ridge appears to be tapping the same portion of mantle as did the Central Indian ridge. These results have important thermo-chemical implications, such as variations in the extent of melting and mineralogical composition of the mantle beneath different ridges, which may influence mantle dynamics.
  • Shore Morphology and Sediment Characteristics South of Pangani River, Coastal Tanzania

    Shaghude, Y.W. (2004)
    The shore morphology and nearshore sediments between the Pangani and Kipumbwi rivers were investigated to describe the shore and the reef platform sediments characteristics and also to update information on recent shoreline changes along the Tanzania mainland coast. The information gathered during this study comes from field observations, sediment sampling of the area and interviews with Pangani residents. The investigated area is a patch reef coast with narrow or no beaches and fossil reef terrace islands offshore, Pangani bay and estuary are among the most prominent shore features. Historical information indicates that, both the bay, and the estuary have undergone significant changes during the last 60 years. While the growth of the estuary has mainly been influenced by the reduced fresh water discharges, the bay has been mainly influenced by shore erosion induced by the high wave activity. The distribution of sediments on the sea bottom is mainly controlled by bathymetry, with sand (medium to coarse) dominating water depths less than 10 m and silt dominating depth greater than 15 m. Sediments in water between 10 and 15 m depth are dominated by fine sand/silt. The carbonate production in the investigated area is limited by the high influx of siliciclastic sediments from the Pangani, Kipumbwi and Ushongo Mabaoni depo-centres. While previous studies attribute the disappearance of Maziwi island to sea level rise, the present study considers the anthropogenic influence to be the major causative factor. Sea level is also considered to be one of the potential threats to the preservation of small islands such as the Maziwi, However, the present study believes that if indeed the vegetation on the island has been cleared as is reported, this action has hastened its disappearance.
  • Land Based Activities and Sources of Pollution to the Marine, Coastal and Associated Fresh Water Ecosystems in the Western Indian Ocean Region

    Francis, J.; Mmochi, A.J. (2003)
    The lack of infrastructure and treatment facilities for the large quantities of domestic sewage generated by expanding coastal urban populations, and an increasing number of visiting tourists, represents the greatest threat to public health, coastal habitats and economic development in each state of the region. Other priorities requiring action include the effects of siltation related to agricultural activity and the dumping of solid domestic waste in the coastal areas leading to the degradation of coastal habitats, with implications for fish stocks and catches. Furthermore, laws and policies regardinng waste disposal and quality of effluents need to be enacted and reinforced Although eutrophication and algal blooms associated with agricultural, industrial or domestic sewage pollution have been identified as a threat to coastal habitats, further scientific research is required to link the causes and effects. Monitoring programmes need to be initiated in the region in order to mitigate pollution. Agriculture is the backbone of the economy of most countries in the region. In 1982, 90% of the population in the region depended on agriculture. With the exception of Mauritius, the physical effects of siltation resulting from agricultural activities are currently of greater concern throughout the region than agrochemical pollution. There is insufficient evidence to indicate whether pesticide pollution in the more intensively farmed coastal areas of the region poses a significant threat to potable water supplies, or to coastal habitats receiving elevated nutrients loads in agricultural run-off. The trend in increased use of both fertilisers and pesticides in intensive agricultural production is likely to lead to elevated concentrations of chemicals in agricultural runoff and ground waters. Overall, industrial development in the region remains relatively low. Industrial activities are focused at the ports and harbours of both the mainland and island states. The number and type of manufacturing industries have changed considerably since 1982. Few industries in the region have waste treatment plants and/or recycling facilities. Many industries empty effluents directly into creeks and rivers leading to the sea or directly to coastal waters. Furthermore, toxic wastes have recently started appearing among wastes disposed. There is a direct relationship between population growth and waste generation. In the case of most large urban centres the solid waste and sewerage facilities have remained the same while the population has increased leading to decline in percentage population served by the facilities. Only a small proportion of dwellings throughout many of the large urban centres of the mainland states are connected to a sewage system. Even then the sewage collected is often pumped directly into coastal waters without any treatment. Rapid urban population growth in the coastal towns have lead to rapid changes in land use patterns. Natural ecosystems are being disturbed or replaced by agricultural crops. The large coastal population is also putting pressure on the marine and coastal resources. Lack of infrastructure and treatment facilities for the large quantities of domestic sewage generated by expanding coastal urban populations, and an increasing number of visiting tourists, represent a great threat to public health, coastal habitats and economic development in the region. Although monitoring data are not available, there is a perceived link between domestic sewage and the occurrence of water borne diseases in most of the coastal townships in the region. There is an urgent need for monitoring of microbial contamination of ground waters in coastal areas of all states of the region. This paper provides an inventory of land-based activities and sources of marine pollution to the marine coastal and associated fresh water environment. It further oversees future developments and suggests priorities for action to mitigate the problems.
  • Sharing experinces on mariculture development with stakeholders

    Jiddawi, N.S.; Mmochi, A.J. (Zanzibar: WIOMSA, 2004)
    WIOMSA News Brief
  • Remote Sensing for Studying Nearshore Bottom Morphology and Shoreline Changes

    Shaghude, Y.W. (Maputo : Direcção Nacional de Geologia, 2004)
    Boletim Direcção Nacional de Geologia, Moćambique
    The major objective of the present study is to demonstrate how remote sensing approach can be used for studying nearshore bottom morphology and shoreline changes in coastal Tanzania. Two study sites were used. In the first site, remote sensing satellite Landsat Thematic Mapper data was evaluated against known water depths from conventional echo sounding measurement taken on the eastern side of the channel. The correlation between the remote sensing data and the echo sounding mesurement was rather satisfactory, suggesting that the approach can roughly be used to investigate sea bottom morphology in the nearshore areas. In the second study site, remote sensing satellite data from Landsat Thematic Mapper and Enhanced Thematic Mapper were used to investigate shoreline changes along the western side of the channel. The results of the study show that the delta and the shoreline north of the delta is currently accreting, where significant accretion has occurred between 1986 and 2000 than before 1986.
  • Coastal Impacts of Water Abstraction and Impoundment in Africa: the Case of Rufiji River

    Shaghude, Y.W. (2005-02-24)
    Construction of large dams with reservoir type storage impound water behind them for seasonal annual, and in some cases for multi-annual storage and regulation of a river. Similarly, tubewells abstract surface and ground water bodies from their natural flow. The impoundment of water by damming and its abstraction through tubewells are common practices in the world and even within the Africa region (WCD, 2000). Globally, the number of large dams has grown at a tremendous pace during the last 50 years (Fig. 1.1) The fast growth in dam construction is driven by an increasing demand of water from urban and rural communities for reliable freshwater supply, agricultural irrigation and hydro-electric power. As these practices become more widespread, they are leading to significant reductions in the fluxes of water and river-borne sediment that are discharged through catchment to coastal sea systems. These flux reductions are contributing to changes in the state of the coastal environment and these changes are in turn impacting coastal communities through issues including coastal erosion, estuarine salinisation and the depletion of nutrients in the coastal sea.
  • The Assessment of Water Quality and Pollution in Tanzania

    Mohammed, S.M. (2000)
    The coastal area of Tanzania (Fig. 1) encompasses a number of habitats that include coral reefs, mangroves, seagrass beds, sand banks, wetlands and beaches, among others. In addition to being essential linkages in the overall functioning of the coastal area, these coastal habitats support various resources both living and non-living. In addition, for generations the coastal area has provided life support to coastal communities where such activities as fisheries and related activities have played an important role in the social and economic development of local communities. In recent years, coastal tourism and mariculture have immerged as being potentially among most important economic activities nationally. The well being of these habitats and resources and the various activities taking place within or near coastal waters depend, to a large extent, on good water quality. However, expanding coastal populations and emerging industrial a
  • Sediment Distribution and Composition on the Shallow Water Carbonate Basin of the Zanzibar Channel

    Shaghude, Y.W. (Dar es Salaam: University of Dar es Salaam, Faculty of Science, 2003)
    Tanzania Journal of Science
    The sediments of the shallow water carbonate basin of the Zanzibar channel were investigated to describe their general characteristics in terms of composition and grain size distribution. The surface sediment composition was dominated by carbonate sands (with CaCO3 > 30%), except in the area adjacent to the mainland coastline and a thin lobe which projects from Ruvu River to the middle of the channel. The mean grain size distribution closely resembled that of the carbonate content, where the Tidally Dominated Reef Platform Sediments (TDRPS) located east of the Zanzibar channel were characterised by medium to coarse sands and the siliciclastic sediments adjacent to the mainland are characterised by fine sand. The TDRPS were the most poorly sorted sediments with sorting values between 1.2 and 1.6 phi. The present study highlights the major differences between the eastern and western side of the channel. The sediments on the eastern side of the channel, which were predominantly biogenic, are characterized by grain size frequency curves without any prominent mode. The sediments on the western side of the channel were composed of both biogenic and terrigenous material. The grain size frequency curves of these sediments have a fine mode and usually a coarse tail. 1
  • Water Quality Country Report: Zanzibar, Tanzania

    Mmochi, A.J.; Khatib, A.; Mpatane, A.; Maalim, K.M. (2004)
  • The Study of Sediment Characteristics and Nearshore Sediment Dynamicsin Coastal Tanzania

    Shaghude, Y.W. (2004)
    The nearshore morphological features, its sediment dynamics and characteristics of the Tanzania Mainland coastal stretch between the rivers Pangani and Wami were investigated. The study is a continuation of other similar studies (e.g Shaghude 2001) which provides a detail account on the nearshore sediment dynamics and its characteristics, in the Tanzania mainland coastal stretch between the rivers Ruvu and Wami, south of the present investigated area. The study is inline with the guidelines on the studies of shoreline changes in the Eastern African region, as well the study of the Eastern African database of coastal resources. The former has recommended detailed studies of shore morphological features, with updating of old information, while the later has recommended establishment and updating databases of coastal resources for the purpose of sustainable management of the existing resources. The investigated coastal stretch between the rivers Pangani and Wami broadly exhibit major north-south variation. The northern coastal stretch between river Pangani and Mkwaja is dominantly a patch reef coast, with or without cliff, with offshore fossil reefs and islands and sometimes with sand spit shores, with few rivers, high water depths, low quartz (20-50% by volume) and feldspar (10-15% by volume) content in the lithogenic dominated sand sediments and high wave activity. From shore to offshore the sediment changes from siliciclastic dominated facie to carbonate dominated facie. The southern coastal section between Mkwaja and Wami river is dominantly a low-lying sandy coast, with relatively large number of rivers, low depths, high quartz (60-75% by volume) and feldspar (20-25% by volume) content in the lithogenic dominated sand sediments and low wave activity. The carbonate facie is generally missing and the sediments are dominated by siliciclastic facie. Mineralogical analyses of the sediments show that most of the lithogenic components, particularly the quartz and feldspar are of angular to sub-angular shape, suggesting that the sediments are texturally immature. Occurrence of hornblende in the sediments is another evidence of immaturity of the sediments. The siliciclastic sediments are therefore inferred to have been transported for a short distance before deposition. Most of the quartz minerals are also highly fractured , occasionally showing undulatory extinction suggesting that most of the lithogenic sediments are derived from a highly metamorphosed rocks. Two of the rivers, namely, the Pangani and Wami which drain through the crystalline metamorphic rocks of the Mozambican belt located on the hinterland of the coastal plateau are therefore considered to be the major contributors of the siliciclastic sediments. All the remaining rivers in the investigated area drain through the coastal plateau or coastal plain, consisting of younger sedimentary formations. The problem of shoreline changes, particularly coastal erosion is very serious in the Pangani river mouth and the former island of Maziwi, reported to have recently disappeared. The estimated rate of erosion at the Pangani river mouth is about 7 to 20 metres per year and the observed erosion is attributed to the high wave activity which is exacerbated by anthropogenic activities related with the upstream damming, mainly, the Nyumba ya Mungu. The recent disappearance of the Maziwi island has been attributed to the clearance of vegitation on the island during the 1970’s which has been exacerbated by the wave erosion. Significant salinity intrusion has been observed in the Pangani estuary, and this again has been related with the increased water abstraction, mainly due to irrigation along the Pangani catchment.
  • Towards Integrated Management and Sustainable Development of Zanzibar's Coast.

    Institute of Marine Science (2002)
    The purpose of this document is to begin a dialogue in Zanzibar about how government, in partnership with local communities and the private sector, can carry out integrated planning and management for coastal resources and regions. It is meant to serve two purposes: To provide a starting point f or addressing the urgent coastal issues facing the Chwaka Bay-Paje Area. It is hoped that the strategy outlined in this document developed through an open, participatory process will provide a basis for avoiding and resolving problems at the site. To enrich and inform the discussion on ho w to address increasingly urgent coastal management problems nation wide. It is hoped that the Chwaka Bay-Paje Area can serve as a model for other areas and help us move forward on a national approach to coastal management. This document has been developed by an Interagency Planning Team led by the Department of Environment and consisting of individuals from the Tanzanian Subcommissions of Fisheries and Forestry, Commission of Lands and the Environment, and Institute of Marine Sciences. The planning team began work in September, 1994 and has been engaged in reviewing information and holding consultation with village residents, hoteliers, and local and national agencies to clearly identify pertinent issues, reach consensus on management objectives, and begin to develop strategies to address the issues.
  • The Incidental Catch of Dolphins in Gillnet Fisheries in Zanzibar, Tanzania

    Amir, O.A.; Berggren, P.; Jiddawi, N.S. (Western Indian Ocean Marine Science Association (WIOMSA), 2002)
    Western Indian Ocean J. Marine Science
    The level of incidental catches of dolphins in artisanal gillnet fisheries was investigated in a questionnaire survey of 101 gillnet vessel operators from 10 villages in Unguja island of Zanzibar, representing half of all the gillnet fishing fleet in 1999. A total of 96 dolphins were reported to have been incidentally caught between 1995 and 1999; 43 Indo-Pacific bottlenose dolphins (Tursiops aduncus), 29 spinner dolphins (Stenella longirostris), 5 lndo-Pacific humpback dolphins (Sousa chinensis) and 19 unidentified dolphins. Most of these incidental catches (46) were reported in 1999. We extrapolate that 93 animals may have been incidentally caught by the entire fishing fleet (201 vessels) during 1999. This estimate represents a serious cause for concern, suggesting that the incidental capture of dolphins in Zanzibar's artisanal gillnet fisheries may be high enough as to have a significant negative impact on local populations. Further studies to accurately estimate the total bycatch, as well as the abundance of dolphin populations in the area are essential to assessing the biological significance of these incidental catches. However, management efforts should be implemented immediately to reduce the number of dolphins killed in these fisheries.
  • Biogenic Assemblage and Hydrodynamic Settings of the Tidally Dominated Reef Platform Sediments of the Zanzibar Channel

    Shaghude, Y.W.; Wannas, K.O.; Mahongo, S.B. (Western Indian Ocean Marine Science Association (WIOMSA), 2002)
    Western Indian Ocean J. Marine Science
    The biogenic assemblage and hydrodynamic settings of the tidally dominated reef platform sediments (TDRPS) east of the Zanzibar channel were investigated in order to characterise the carbonate sediments. Benthic foraminifera were found to be the most important group both in terms of average abundance (> 60 % by weight) and also in terms of spatial distribution with ommon occurrence in all sediments samples. Pelecypods with an average abundance of 8 % were slightly less widely distributed. The remaining groups occurred at lower average abundance and less frequently in the sediments. Current measurements indicated that the maximum current speed is higher during spring than during neap tides. The direction is phase-dependent with flood tidal current flowing from the northern and southern tips of the island towards Zanzibar town. The ebb current flows in the opposite direction. The geomorphological setting of the carbonate platforms together with the present investigation of the currents and biogenic assemblage of the clastic sediments permits us to subdivide the reef platform area in the Zanzibar Channel into two sub-provinces: the northern and the southern. The northern sub-province contains significantly higher proportion of lithogenic particles. Pelecypods, gastropod and ostracods than the southern sub-province. Some samples from the southern sub-province had significantly higher proportion of corals, than those from northern sub-province.
  • Water, Salt and Stoichiometrically linked nutrient budget for Chwaka Bay, Tanzania

    Ngusaru, A.S.; Mohammed, M.S. (Western Indian Ocean Marine Science Association (WIOMSA), 2002)
    Western Indian Ocean J. Marine Science
    The water and salt balance at Chwaka Bay in Zanzibar, Tanzania suggests that in order to balance the inflow and outflow of water, there must be a net flux of water from the bay to the open ocean during both the dry and wet seasons. The corresponding salt residual fluxes indicate advective salt export. However, exchange between the bay water with the open ocean replaces this exported salt via mixing. The freshwater residence times at Chwaka Bay are 24 days for dry and 37 days for wet season. The budgets for non-conservative materials indicate a net dissolved inorganic phosphorous (DIP) and dissolved inorganic nitrogen (DIN) flux from the bay to the ocean during wet season. The calculated DIPsyst and DINsyst suggest that the bay acts as a DIP and DIN source during the wet season. Stoichiometry calculations suggest that (p-r) is negative, indicating that Chwaka Bay is net heterotrophic during wet season. The inner bay seems to have net denitrification, but the outer bay seems to be fixing nitrogen at a slower rate. However, the entire bay appears to balance nitrogen fixing and denitrification.

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