Browsing by Author "Jiddawi, Narriman S."

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    Community based aquaculture in the western Indian Ocean: challenges and opportunities for developing sustainable coastal livelihoods
    (Resilience Alliance, 2018) Ateweberhan, Mebrahtu; Hudson, Joanna; Rougier, Antoine; Jiddawi, Narriman S.; Msuya, Flower E.; Stead, Selina M.; Harris, Alasdair
    The small-fisheries social-ecological system in the western Indian Ocean (WIO) represents a typical social-ecological trap setting where very poor natural resources dependent coastal communities face local and global threats and engage in unsustainable practices of exploiting limited resources. Community-based aquaculture (CBA) has been implemented as an important alternative or supplementary income generating activity for minimizing the overdependence on marine natural resources and promoting biodiversity conservation. Despite its proliferation throughout the WIO region in recent decades, little is known about the degree to which CBA activities have contributed to achieving the objectives of breaking the cycle of poverty and environmental degradation and promoting community development and biodiversity conservation. In order to improve understanding of common challenges and to generate recommendations for best practice, we assessed the most common CBA activities practiced in the region through literature review and workshop discussion involving practitioners and key stakeholders. Findings indicated that despite favorable environmental conditions for various CBA practices, the sector remains underdeveloped, with few activities delivering the intended benefits for coastal livelihoods or conservation. Constraints included a shortage of seed and feed supplies, low investment, limited technical capacity and skills, insufficient political support, and lack of a clear strategy for aquaculture development. These are compounded by a lack of engagement of local stakeholders, with decision making often dominated by donors, development agencies, and private sector partners. Many of the region’s CBA projects are designed along unrealistically short time frames, driven by donors rather than entrepreneurs, and so are unable to achieve financial sustainability, which limits the opportunity for capacity building and longer-term development. There is little or no monitoring on ecological and socioeconomic impacts. Except for a few isolated cases, links between CBA and marine conservation outcomes have rarely been demonstrated. Realizing the potential of CBA in contributing toward food security in the WIO will necessitate concerted investment and capacity strengthening to overcome these systemic challenges in the sector. Lessons herein offer managers, scientists, and policy advisors guidance on addressing the challenges faced in building strategic development initiatives around aquaculture in developing countries.
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    Coral bleaching and habitat effects on colonisation of reef fish assemblages: An experimental study
    (Elsevier, 2011) Yahya, Saleh A.S.; Gullström, Martin; Öhman, Marcus C.; Jiddawi, Narriman S.; Andersson, Mathias H.; Mgaya, Yunus D.; Lindahl, Ulf
    Degradation and mortality of corals is increasing worldwide and is expected to have significant effects on coral reef fish; hence studies on these effects are essential. In the present study, a field experiment was set up within Mafia Island Marine Park in Tanzania (East Africa) to examine the effects of bleaching and habitat structure on colonisation of coral reef fish assemblages. Live and bleached staghorn coral Acropora formosa was transplanted onto plots in a site dominated by sand and rubble, and the experimental design comprised of three treatments: live coral, bleached coral and eroded coral rubble. There was an immediate increase (within 24 h) in fish abundance and diversity in the two treatments with standing corals. Overall, live and bleached coral plots showed similar effects, but differed from the eroded coral plots which had a much lower abundance and diversity of fish. In general, fish species diversity changed with time over the study period while fish abundance did not. Multivariate analyses showed that while there were differences in fish assemblage structure between standing corals and the eroded coral treatment, there was neither a difference between live and bleached coral treatments nor any temporal effects on fish assemblage structure. Our findings suggest that physical structure and complexity of habitat have stronger effects on colonisation of reef fish assemblages than changes in coral health (such as bleaching) which do not affect coral structure. This may have important implications for appropriate coral reef management.
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    Feeding Ecology of the Indo-Pacific Bottlenose Dolphin (Tursiops Aduncus) Incidentally Caught in the Gillnet Fisheries Off Zanzibar, Tanzania
    (Elsevier, 2005) Amir, Omar A.; Berggren, Per; Ndaro, Simon G. M.; Jiddawi, Narriman S.
    The stomach contents of 26 Indo-Pacific bottlenose dolphins (Tursiops aduncus) incidentally caught in gillnet fisheries around Unguja Island (Zanzibar) between February 2000 and August 2002 were examined. The relative importance of each prey species was assessed through indices of relative importance. In total, 1403 prey items comprising 50 species of bony fish and three species of squid were identified from food remains. Five species of fish, Uroconger lepturus, Synaphobranchus kaupii, Apogon apogonides, Lethrinus crocineus, Lutjanus fulvus, and three species of squid, Sepioteuthis lessoniana, Sepia latimanus and Loligo duvauceli, were the most important prey species. Based on an index that included frequency of occurrence, percentage by number and by weight, Uroconger lepturus proved to be the most important prey species of mature dolphins whereas Apogon apogonides was the preferred prey of immature dolphins. These results indicate that Indo-Pacific bottlenose dolphins off the coast of Zanzibar forage on a relatively large number of prey species, but that only a few small- and medium-sized neritic fish and cephalopods contribute substantially to the diet. Further, the ecology and behavior of the preferred fish prey species indicate that the dolphins forage over reef or soft bottom substrata and near the shore.
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    Fish Community Composition of a Tropical Nonestuarine Embayment in Zanzibar, Tanzania
    (Wiley, 2007) Lugendo, Blandina R.; Nagelkerken, Ivan; Jiddawi, Narriman S.; Mgaya, Yunus D.; Van der Velde, Gerard
    By using a seine net, fish samples were taken from the nonestuarine Chwaka Bay (Zanzibar, Tanzania) from the mangroves, mud/sand flats and seagrass beds. Sampling was done twice per month between November 2001 and October 2002. In total, 150 fish species belonging to 55 families were identified. Diversity (H′) ranged from 1.9 in mud/sand flats to 3.4 within the Chwaka seagrass beds. Mean density of fishes was significantly higher in the mangrove creeks than in any other habitat (mean = 238.7 ind./1000 m2). Highest, but non-significantly different mean biomasses were recorded in the mangrove creeks (1.7 kg/1000 m2) and in the Marumbi seagrass beds (1.6 kg/1000 m2). The mangrove channel had the lowest biomass (0.6 kg/1000 m2). A high overlap in species composition (as high as 93.4% similarity) was found for adjoining habitats (i.e. mangrove creeks and mangrove channel), while habitats that were far apart showed low overlap (6.6% similarity for the Marumbi seagrass beds and mangrove creeks). On average, 58.4 and 63.2% in terms of abundance and biomass, respectively, of the fish assemblage of Chwaka Bay were of commercial fishery importance. Thus, Chwaka Bay appears to be an important juvenile habitat for various commercially important fish species.
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    Macroalgae as Biofilters of Dissolved Inorganic Nutrients in an Integrated Mariculture Tank System in Zanzibar
    (2001) Mwandya, Augustine W.; Mtolera, Matern S. P.; Pratap, Harish B.; Jiddawi, Narriman S.
    A laboratory experiment was conducted to determine the capacity of themacroalgae Eucheuma denticulatum, Gracilaria crassa and Ulva reticulatato remove dissolved inorganic nutrients from finfish effluents in seriallyarranged tank systems. The aim was to determine the capacity ofmacroalgae which could be used in an integrated maricultre pond systemat Makoba, Zanzibar. Seawater from the reservoir entered the finfish tanksfirst, then drained through plastic pipes into the shellfish units and finallyinto the macroalgae units before being discharged back into the sea. Thewater residence time in each tank was 4 days. The performance of each ofthe different units was assessed in terms of total ammonia-N, phosphate-P and nitrate-N produced by finfish, and then, the removal of these nutrientsby shellfish and macroalgae biofilters. The levels of dissolved inorganicnutrients were highest in the finfish units and lowest in the macroalgaeunits. Increase in stocking density of macroalgae from 1g/l to 2g/l wasrelated to their increase in daily growth rates, specific growth rates andinorganic nutrient uptake rates. However optimum stocking densities werenot reached. Of the three inorganic nutrients, ammonia-N and phosphate-P was taken up by the macroalgae much more than nitrate-N. Ammonia-N removal efficiency in the system reached a maximum of about 63% at2g/l of Ulva reticulata whereas, phosphate-P and nitrate-N maximumremoval capacity were 58 and 54% respectively. Among the three species ofmacroalgae, Ulva reticulata seems to be the most efficient biofilter. It isconcluded that locally available macroalgae are good bioregulators of waterquality, thus can be applied in small scale mariculture activities and canalso generate income.
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    Towards an Integrative Research Approach on Coastal Ecosystems – The example of Chwaka Bay
    (Western Indian Ocean Marine Science Association, 2012-11) Lyimo, Thomas J.; De la Torre-Castro, M.; Shaghude, Yohanna W.; Jiddawi, Narriman S.; Björk, Mats; Lindström, Lars
    During recent decades, the serious challenges that the planet is facing in terms of population growth, ecosystem damage and changes in flows of good and services call for novel ways to direct research so that it can be useful for promoting sustain-ability. The integration of different disciplines is much needed when tackling such challenges. At this very moment, climate change is a major concern and its effects, for example in changes in seawater temperature and weather patterns and how they in turn affect critical resources are beginning to be felt more acutely. Green solutions are needed to tackle some of the challenges, for example in considering the importance of marine plant communities such as mangroves and seagrasses as potential carbon sinks when planning for the future. Another critical aspect is the degradation of marine resources and ecosystems. These changes will definitely shape the future and composition of coastal livelihoods. How to adapt to these changes? How to ensure the continued flow of goods and services on which most of these populations rely? The capacity to cope and adapt to these changes are complex and include a variety of actors. At the very heart of the local communities, activities and social organization are after all gendered, thus knowledge about how changes will affect men and women is crucial. An integrative research approach is also much needed in addressing structural changes in global and national economies. The examples above illustrate the complexity of the challenges, their importance for human well-being and the range of spatial and temporal scales that need to be considered when conducting research that is relevant for management aimed at sustainability. Chwaka Bay lends itself perfectly for research that considers the challenges above and has been used for field experiments over the years. The Bay presents a typical tropical seascape with a profile of mangrove forests, seagrass meadows and coral reefs while at the same time it is atypical by being so well-studied. It has also served