Institute of Marine Sciences

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Abundance, distribution and reproductive biology of two selected penaeid prawns in Tanzanian waters
(University of Dar es Salaam, 2016) Mwakosya, Catherine Adam
Tanzania is one of the tropical countries, which practises both industrial and artisanal prawn fisheries targeting the shallow water penaeid prawns. Industrial prawn fishery takes place in three designated fishing grounds along the coast of Tanzania, namely zone 1, zone 2 and zone 3 of which in this study were considered the main sampling locations during the ship surveys conducted. On the other hand artisanal fishery is concentrated in the Ruvu estuary and along Rufiji Delta. The prawn fishery in Tanzania for the past decade has indicated serious unsustainable exploitation levels and a decline in production trends despite the reduction in fishing effort. The shallow water prawn species composition, abundance and distribution by site, zones, depth and season were assessed. Seasonal size frequency distribution, length-weight relationships, sex ratio, size at first sexual maturity, and gonad histology and growth parameters of the two prawn species (Fenneropenaeus indicus and Metapenaeus monoceros) were also studied. It was not known whether the prawn populations existing in the study area are genetically connected or distinct. To test the hypothesis that a single population exists, the mitochondrial DNA (mtDNA) sequence data were used to study the populations. From the findings of this study, it is concluded that the populations existing in the three prawn fishing grounds are not different. The study observed high exploitation levels at the two land-based sites (Bagamoyo and Nyamisati) with a slight improvement in the catch rates, which is an indicator of slow recovery of the stock. Consequently, a management strategy of extending the closed season to include the artisanal fishers’ grounds is recommended.
Acclimatization, survival and growth. Rates of Pangani tilapia (oreochromis pangani) in different salinities.
(University of Dar es Salaam, 2011) Hassan, Aziza
Coastal communities depend on fisheries activities as their main source of income. With the fast rising coastal population and technological advancement, pressure on the wild marine resources is increasing leading to overexploitation. Aquaculture sees as a possible livelihood alternative that will provide the coastal people with an alternative source of income. Some species of tilapia are known to survive and grow in estuarine and marine environment. The aim of this study is to determine the Acclimatization survival and growth of Oreacbromis pangani in four different salinities. Pangani species was collected from Pangani River and acclimatized for 17 days by raising the salinity by 2 PPt /day. The fingerlings weighing between 1 .3g-3 1 .4g were cultured at 0, 15, 25 and 35 ppt in 1 m 3 concrete ponds. Environmental parameters in the ponds were monitored once a day. Water exchange was done at 15% per day throughout the experiment while fecal matter, feeds remains were removed weekly by flushing. The mean growth rates per week were 2.25 ± 2.0 g, 2.77 ± 1.55 g, 2.34 ±1.38 g, and 1.86 g ± 0.16 at salinity level of 0, 15, 25, 35 ppt respectively. The growth rates were not statistically different among salinity levels (1- ANOVA, F =1.129, DF = 55, P > 0.05). Also from one way ANOVA results shows that, there was no significance difference in growth rates between treatments ponds and control ponds for 0, 15 and 25 ppt. However, at 35 ppt stress had impact on growth rate (t, 8.85, P= 0.006). Nevertheless, the results of the study have shown O. pangani to grow better on salinity level of 15. The overall survival rate was 96.46% and that of the different salinities were 100,95,95 and 90 for O, 15, 25 and 35 ppt respectively.
Analysis of local governance in conservation of mangrove forests of Geza and Mtimbwani coastal communities in Tanga, Tanzania
(University of Dar es Salaam, 2015) Tarimo, Barnabas Alphonce
Analysis of local governance mechanisms that would be supportive of sustainable conservation of mangrove forests, particularly for development and promotion of carbon markets was conducted in Geza and Mtimbwani communities along the northeastern coast of Tanzania. Primary datawere collected through focus group discussions, key informant interviews and household questionnaires. Secondary data were collected through a review of policy and legislative documents, institutional plans and reports. Content analyses, descriptiveand inferential statistics were used to analyze data. The study found that local governance mechanisms are facedwith a number of barriers and limited opportunitiesto support the designing of carbon markets. The main barriers identified include inadequate financial resources, complication in forestland tenure, poor knowledge ofmangrove ecosystems, lack of benefit sharing arrangements and insufficient human and material resources. Whereas the opportunities identified include the presence of Village Natural Resources Committees, Non-Governmental Organizations and conservation experience left by Tanga Coastal Zone Conservation and Development Programme and Mangrove Management Project. It was also learnt that the communities were supportive of mangrove conservation arrangements through carbon credits, although clarity of rules and regulations, traditional rights and access to information was a concern. These findings highlight the need toimprove local governance frameworks to ensure effective law enforcement, awareness rising to local communities on conservation behavior, and equipenvironmental teamswith training and financial support as part of promotion of carbon market schemes.
Assessment of ecological differences between conserved and unconserved mangrove forests of Zanzibar, Tanzania
(University of Dar es Salaam, 2011) Monga, Elinasi
While exploitation pressure is mounting in mangrove forests in Zanzibar, the ecological consequences are not well understood. This study, aimed to establish whether there are ecological differences between the conserved mangrove forest of Jozani and unconserved mangrove forest of Pete in Zanzibar, Tanzania. Ecological parameters of mangrove tree density, basal area, above ground biomass (AGB) and crab diversity and abundance were assessed and compared. The ABG (kg/ha) were found to decrease from the lower to the upper zones in both forests with higher values recorded in Jozani forest. Tree density was higher in Jozani than Pete, with the density decreasing from the upper zone to the lower zone in Jozani while at Pete it was even across the zones. Similarly, Jozani forest had higher seedlings density than Pete forest, with a decreasing trend from the lower to upper zone while an increasing trend was observed in the Pete forest. For saplings, Pete forest had higher density than Jozani forest, with an even distribution across the three zones in both forests. The number of cut stumps increased across the zones from lower to upper with higher densities recorded in Pete forest. Crab densitiesdecreased from the lower zone to the upper zone in both forests with highest densities recorded in Pete forest. The physical observation in Pete was that almost all mature treeswere cleared and the stand comprised of new successional regeneration. These results indicate promising ecological returns of conservation for Jozani, and it calls for strictforest conservation measures particularly that of Pete. Public education and capacity building to forest guards are proposed for restoration and sustainability of the ecosystem.
Assessment of growth performance and feed utilization of the nile Tilapia (Oreochromis niloticus) fingerlings to pumpkin (Cucubrita Maxima) seeds meal as possible altenative fish feed to fish meal in Tanzania
(University of Dar es Salaam, 2017) Kanyandenge, Zakaria Michael
This study was designed to determine the effects on growth performance of feeding pumpkin seeds meal as a source of protein to Oreochromis niloticus. Triplicate tanks containing twenty specimens of Oreochromis niloticus of initial average weight of 0.37 ± 0.14 g to 0.43 ± 0.18 g were stocked per concrete tanks for 15 weeks. Three experimental diets each with 40 % crude protein and 1O % crude lipid were formulated and named as fish meal diet (FMD), mixture meal diet (MMD) and pumpkin seed meal (PSM) whereby diet named fish meal diet acted as a control diet without inclusion of pumpkin seeds. Fish were fed two times at rate of 10 % of their body weight per day. Data were analyzed by using one-way ANOVA. There was a significant difference in growth performance and feed utilization efficiency among experimental diets at significance level of 0.05 %. Fish fed fish meal diet (FMD) showed significantly higher average daily weight gain (0.16 ± 0.03 g), final body weight (5.68 ± 0.77 g) and specific growth rate (2.40 ± 0.77 g) followed by mixture meal diet with average daily weight gain (0.14 ± 0.02 g), specific growth rate (2.13 ± 0.63) and final body weight (4.64 ± 0.67 g). Low average daily gain of 0.13 ± 0.25 g and specific growth rate of 1.88 ± 0.44 were realized in pumpkin seed meal. The higher protein efficiency ratio (PER) of 2.59 ± 0.03 was obtained in fish meal diet followed by mixture meal diet (2.49 ± 0.03) and pumpkin seed meal diet (2.34 ± 0.04). Higher feed conversion ratio of 1.89 ± 0.05 was found in fish fed with pumpkin seed meal followed by mixture meal diet and fish meal diet with 1.77 each and survival rate was (SR) 77.87 %. Water quality parameter was within acceptable optimal level for fish growth and survival. The mean observed was water temperature (26.95 ± 0.44 °C), dissolved oxygen (6.8 ± 1.5 mg/L to 9.5 ± 0.3 mg/L) and water pH (7.84 ± 0.18). The result of total replacement of fish meal by using pumpkin seeds meal as dietary plant protein source in Oreochromis niloticus meals was negative.
Biofiltration performance of doum palm, hyphaene compressa (h. windl, 1878) fronds and effective micro organisms’ technology in a semi-intensive mariculture system
(University of Dar es Salaam, 2015) Ndaro, Mukama Chigula Kweba
Biofiltration performances of native microorganisms concentrated on East African Doum Palm Fronds (EADPF), Hyphaene compressa (H. Windl. 1878) and Effective Microorganisms (EM) consortium were assessed. Triplicate polyculture tanks (1 m3) with Orechromis urolepis urolepis (Norman, 1922) and Mugil cephalus (Linnaeus, 1758) were used. Seawater treated EADPF (EADPF-F), untreated EADPF (EADPF-U), EM on Polyvinyl Chloride sheets (PVC-EM), EM consortium without media (EM) and Polyvinyl Chloride without EM (PVC) were used except in the control (CONTROL) tanks. PVC-EM, PVC, EADPF-F and EM systems had better ammonia biofiltration efficiency of 83.7 ± 3.13%, 80.9 ± 3.13%, 73.2 ± 5.36% and 66.7 ± 3.23% respectively while EADPF-U had the least (38.4 ± 7.09%). Total suspended solids levels were relatively little in PVC-EM, PVC and EM but high in EADPF-F and EADPF-U systems. Of the two finfish, O. urolepis urolepis had relatively higher specific growth rate (SGR) and survival rate (SR), with EM and EADPF-F systems providing the best SGR (3.41%) and SR (55.6 ± 9.0%) while the CONTROL and EADPF-U provided the least SGR (2.45±0.03%) and SR (27.9 ± 14.7%), respectively. The results showed that EM, PVC-EM and PVC were effective in enhancing both, the effluents biofiltration and growth of O. urolepis urolepis. Higher values in EM and PVC-EM were attributed to both the regenerative characteristics of EM consortium and ability to fix ammonia while excess heterotrophic activities explained the low values in EADPF-U. The EADPF-F, providing the best SR and run-up SGR of 3.17±06 similar to PVC-EM (3.17±04) was revealed as a potential biofilter media and enhancer of periphyton or bioflocs in mariculture system.
Comparative study of genetic diversity and distribution of symbiodinium harboured by reef building corals common to Tanzania and Mauritius
(University of Dar es Salaam, 2011) Chumun, Pramod Kumar
The symbiosis of dinoflagellate micro-algae, zooxanthellae (genus Symbiodinium) with corals is vital for the survival and ecology of reef-building corals. Nevertheless, extremes of climate change induced factors e.g. temperature and irradiance may crumble the association if intolerant zooxanthellac clades are involved. This research aims at establishing the genetic diversity of Symbiodinium in coral species found in selected sites in Mauritius and Zanzibar that experience differing factors such as biogeography, temperature and irradiance levels throughout the year with the view to understand the possible environments such corals are exposed to. Molecular work was performed on five coral species named Galaxea fascicularis (n=51), Acropora muricata (n=49), Pocillopra damicornis (n=30) Porites cylindrical (n=44) and Pocillopora verrucusa (n=31)) in order to classify their different Symbiodinium genetic clades. The 18S- ribosomal DNA of the endosymbiont, which is a highly conserved region, was amplified using zooxanthellae specific primers and the clades were classified by RFLP method. Taq 1 and Hha 1 restriction enzyme were used for the digestion of the PCR product. It was found that zooxanthellae clades A, C and D were present among the studied coral species in both countries but in different proportions. In Zanzibar, clade D was dominant among A. muricata (8 1%) and G. fascicularis (88%) but higher proportion (76% and 68%) of clade C was found in respective Mauritian coral species. P. verrucusa associated more with clade A in Zanzibar (80%) compared to Mauritius (29%) This difference in proportion may be due to varying environmental factors like temperature and light prevailing in the two studied regions or due to stress from climatic changes resulting in coral bleaching. Results obtained can peeve the way for a better understanding of zooxanthellae clade dominance among coral species in the Western Indian Ocean (WIO) region and thus contribute in the long-term management of coral reefs.
Distribution and abundance of diseases on reef corals in Tanzania
(University of Dar es Salaam, 2016) Mohammed, Mohammed Suleiman
Diseases affecting reef corals are on the rise in the world oceans. Warming of the seas, deteriorating water quality and increased human activities in the nearshore waters are considered to play a major role in the prevalence of coral diseases. The goal of this study was therefore to characterize and investigate the abundance of coral diseases and its environmental drivers in reefs off Zanzibar and the main coast of Tanzania. To achieve these, 20 sites were selected along the whole coast of Tanzania and nearby islands. Rapid assessment surveys, line intercept transects and belt transects were used to monitor the selected study sites. In addition, the effect of temperature and nutrients on white syndrome (WS) disease on table Acropora and bleaching on Porites australiencis was assessed through sets of experiments done both in laboratory and in the field. The study has revealed seven coral diseases with significant difference between localities (p < 0.001). The mean prevalence was relatively low ranging from 2.24±1.6% in Pemba to 0.09± 0.3% in Zanzibar Stone town reefs. Prevalence of WS on table Acroporids was significantly higher during warm season 5.63±3.7 than cool season 3.55±2.2% (p<0.05). The progression rate was higher (p<0.05) during cool period where 80.42±15.42 cm2/day was recorded compared to 16.14±8.79 cm2/day recorded during warm period. These results show that there is no relationship between temperature and WS prevalence but the virulence of WS is more pronounced during cool season. When temperature and nutrients were manipulated over bleached Porites australiensis to check the progression rate of bleaching over time scale, the bleached corals did not show any significant difference between the treatments. Similarly, the treatments could not result in bleaching on healthy corals. These results show that temperature and nutrients at the levels used in this study may not have direct impact on corals but may delay coral recovery from any unforeseen impact. Disease prevalence in Tanzania water is low compared to other regions in the world. Low prevalence may be due to low levels of anthropogenic influence as compared to the areas with higher disease prevalence. Coral bleaching is the major threat to coral reefs as when it occur it cover large geographical area and involves many coral species.
Dynamics in Shirati Bay, Lake Victoria Tanzania With Special Zooplankton Emphasis on the Copepods
(University of Dar es Salaam, 2008) Waya, Revania Kiduduye
The population of dynamics of zooplankton with emphasis on the copepods were studied Shirati Bay, Lake Victoria, between March 2005 and March 2006. The study revealed spatio-temporal variations in zooplankton distribution and the factors influencing their distribution, abundance and composition. Factors affecting zooplankton density, biomass and distribution in Shirat Bay were found to include food condition, predation, temperature, wind, light and transparency. There was significant correlation between zooplankton abundance and the bacillariophytes (r = 0.9454,n=13,p<0.0001),Rotifera biomass and cyanophytes (r=08264, n =13,p<0.0001)there was a significant association between abundance of fish and zooplankton (Matel test: Standard normal Variate g(1,1000)=7.0834, p=0.009,r=0405, and abundance of haplochromines and zooplankton (g 1,1000) = 6.348, p=0.001,r = 0.888). also the linear correlation analysis revealed significant correlation between temperature and number of ovigerous female copepod (r= -05585, n=13, p=0.0473). three groups of zooplankton were recorded namely, Copepoda, Rotifera, and Cladocera. A total of 44 species were recorded, Rotifera showed highest diversity index (H’) of 2.321. Copepoda was the most important group in terms of abundance and biomass among them cyclopoid copepod dominated the zooplankton community throughout the study period. Nauplius and Cyclpopoid Copepodites in Shirati Bay During March 2005 –March2006 0 MAR-05 APR 05 MAY 05 JUN 05 JUL 05 AUG 05 SEP 05 0CT 05 N0V 05 MAR O5 0.000 0.741 0.647 0.816 0.789 0.800 0.989 0.929 APR 05 2.770 0.000 1.000 1.000 1.000 1.000 1.000 1.000 MAY 05 3.010 0.240 0.000 1.000 1.000 1.000 0.997 1.000 JUN 05 2.558 0.212 0.451 0.000 1.000 1.000 1.000 1.000 JUL 05 2.639 0.131 0.371 0.081 0.000 1.000 1.000 1.000 AUG05 2.606 0.164 0.404 0.048 0.033 0.000 1.000 1.000 SEP 05 1.624 1.146 1.386 0.935 1.015 0.983 0.000 1.000 OCT 05 2.139 0.631 0.871 0.419 0.500 0.467 0.515 0.000 NOV 05 1.324 1.446 1.686 1.234 1.315 1.282 0300 0.815 DEC O5 2.807 0.037 0.203 0.249 0.168 0.201 1.183 0.668 JSN 05 0.220 2.550 2.790 2.339 2.419 2.386 1.404 1.919 FEB 06 3.755 6.525 6.765 6.313 6.394 6.361 5.378 5.894 MAR 06 1.754 4.524 4.764 4.312 4.393 4.360 3.378 3.893 Values in bold indicate significant differences among months.
Ecology of the intertidal zone of selected sandy/muddy shores in the Dar es salaam area
(University of Dar es Salaam, 2000) Mlay, Angela Peter
An ecological study was conducted on four shores in the Dar es Salaam area, Kunduchi, Ocean Road, Mjimwema/Kendwa, and Mtoni. The following were determined monthly for a period of one year: particle size, organic matter content, and percent pore water of the substrate; depth of the hydrogen sulphide layer; temperature; salinity; dissolved oxygen concentration in tidal pool water; and density, biomass, and species diversity of benthic macrofauna. In a comparison of the four shores, there was a very significant difference in density (randomized block analysis of variance, F = 22.751, p = 3.609 x 10"8), and biomass (Friedman’s test, Chi-square = 23.900, p = 2.576 x 105). Kunduchi and Ocean Road were similar in all the abiotic factors measured. Both shores had moderate species diversity, but low density and biomass of macrofauna. Besides being under environmental stress due to desiccation, these shores have been exposed to anthropogenic impacts due to excessive movement of boats and people, destructive fishing methods and pollution. In comparison with Kunduchi and Ocean Road, Mjimwema/Kendwa had higher percent pore water, lower organic matter content, thinner hydrogen sulphide layer, but approximately the same dissolved oxygen and salinity levels. Due to the physical contours of the surrounding area, this shore never completely drains and there are relatively few anthropogenic effects. Compared to the other three shores, Mjimwema/Kendwa had the highest biomass and species diversity of macrofauna. It also had high density. At Mtoni, the substrate was determined to be very fine silt, poorly sorted, with very low percent pore water, a high build up of organic matter, and a thick hydrogen suphide layer. Since it is in an estuary, salinity was lower than on the other shores and showed the greatest drop during the rainy season. Compared to the other three shores, Mtoni had the lowest species diversity, lowest biomass, yet highest density. This was due to the high density of two species of very small organisms that seem to be adapted to that stressful environment, i.e., Arcuatula arcuatula and Modiolus sp Mtoni had greater biomass of bivalves, crabs, and polychaetes than on the other shores. Gastropods were found in the greatest biomass at Mjimwema and were not observed at all at Mtoni. Total macrofauna, bivalve, and polychaete biomass were highest during the principal and secondary rainy seasons at Mjimwema/Kendwa. Crabs had greater biomass during the principal rainy season at both Ocean Road and Mjimwema/Kendwa. Kunduchi and Ocean Road showed the greatest biomass on the lower part of the shore, while Mjimwema and Mtoni showed the greatest biomass in the middle of the shore. All shores showed the lowest biomass on the upper part of the shore, which was dominated by crabs. In this zone, Dotilla fenestrata was dominant on all shores along with either Ocypode spp. (Kunduchi, Ocean Road and Mjimwema) or Uca spp. (Mtoni). At Kunduchi and Ocean Road, midshore was dominated by a variety of polychaetes, sipunculids, bivalves and crabs, while holothurians dominated the lower shore. At Mjimwema/Kendwa, midshore was dominated by a variety of gastropods, bivalves, sponges, holothurians, sea urchins, and brittle stars.
Ecophysiology of mangrove seedlings: Responses to Waterlogging, Salinity, Light and Nutrient Enrichment
(University of Dar es Salaam,, 2012) Mangora, Mwita Marwa
Although flooding and salinity variations occur commonly in mangrove systems, their frequency and severity have, however, been increasing with increased global warming (GW) to an extent that GW induced phenomenon such as heavy rainfall and subsequent floods, increased terrestrial runoff, and sea level rise are frequently associated with massive mangrove mortality and/or failure to regenerate. Manipulative mesocosm experiments were therefore set to assess the interactive stress effects of mimicked waterlogging/submergence, salinity, light and nutrient enrichment on growth and photosynthesis of seedlings of the mangroves Avicennia marina (Forssk.) Vierh., Bruguiera gymnorrhiza (L.) Lamarck and Heritiera littoralis Dryand. Three main experiments were conducted: (i) interactive effect of waterlogging, salinity and light, (ii) interactive effect of waterlogging, salinity and nutrient enrichment and (iii) underwater photosynthesis in varied salinities. Growth was assessed through structural and biomass traits, and photosynthesis through assessment of photosynthetic yield and leaf chlorophyll content. It was found that H. littoralis growth was drastically suppressed and its photosynthetic yield significantly declined during prolonged waterlogging and submergence, increased salinity, and when shifted from shade to light. Comparably, B. gymnorrhiza seedlings maintained high tolerance across the variably interactive stresses than A marina and H. littoralis. Nutrient enrichment did not provide enhancing effect to override the stressful conditions of waterlogging and elevated salinities. The varying ability of B. gymnorrhiza and A. marina to acclimatisation and the inability of H. littoralis to withstand the stresses suggest possible disruptions in mangrove forests regeneration in conditions of prolonged inundations due to flooding or sea-level rise. Results of the present study demonstrated that climate change driven environmental conditions may influence the performance of seedlings. They are useful in explaining the phenomenon of retarded natural regeneration in mangrove stands in major river estuaries of the region following flooding events, like that of 1997/98 El Nino. They are also useful in guiding management decisions on mitigation and adaptive mangrove restoration and management especially where reforestation and afforestation may be necessary.
Effect of different dietary protein sources on growth performance of rufiji tilapia, oreochromis urolepis urolepis (Norman, 1922)
(University of Dar es Salaam, 2015) John, Maria
One of the challenges facing intensive tilapia aquaculture development in developing countries is finding suitable alternatives to fishmeal (FM) from easily available and cheap local dietary protein sources. A 56 days experiment was therefore conducted in 80-liter plastic containers to investigate the suitability of blood meal (BM), sunflower meal (SFM) and Azola meal (AM) as alternative dietary protein sources on growth performance and feed utilization of the Rufiji tilapia, Oreochromis urolepis urolepis Norman (1922). Dry pelleted BM, SFM and AM containing 35% crude protein and 10% lipid were used as a protein sources and FM was used as a control in feeding two sets each containing 10 fingerlings with an average weight of 0.92±0.They were fed twice a day at a daily ration of 5% of the body weight. Water parameters monitored during the study were pH, temperature, salinity and dissolved oxygen concentration. No significant differences (P > 0.05) were found in growth performance and feed utilization in terms of weight gain, protein efficiency ratio, feed conversion ratio, feed intake and specific growth rate in all the three diets used. From the results of the present study fish meal can be replaced up to 15%, 45% and 60% with Azolla, sunflower and blood meals respectively without affecting the general growth performance of the experimental fish. Cost analysis showed that fish feeding on BM was most cost effective followed by AM then SFM.
The effects of exploitation on habitat, reproductive potential and assessment of knowledge for management of sea cucumbers (echinodermata: holothuria scabra and h. nobilis) in Tanzania
(University of Dar es Salaam, 2017) Mmbaga, Twalibu Kithakeni
While the impacts of high exploitation on fish populations and aquatic ecosystems are well documented for commercial and small-scale fishing particularly in the marine environment, such impacts on the fishery of sea cucumbers have not received as much attention. The current thesis examines the impacts of exploitation on sea cucumbers’ basic ecological, biological, fishery, and knowledge of management aspects by focusing on Holothuria scabra and H. nobilis. The study sites selected are associated with different exploitation intensities and pronounced selective exploitation along the coast of Tanzania. The impacts range from effects on the habitats (diminished natural ecological parameters, habitat modifications, and habitat disturbance), exploited population (size, structure, and reproductive potential), changes in fishery characteristics (gear, and fishing methods), to lack of biological knowledge for management. The main findings of the study are that, fishers of sea cucumbers fall under four categories, namely collectors, processors, middlemen and exporters. Middlemen are either fishers of sea cucumbers or rich non-fishers/dealers. Sea cucumbers fishing, associated activities and mismatch between stakeholders and knowledge have led to a decline in habitat quality, species abundance, and reproductive potential. The study further showed that fishery characteristics and knowledge for management of fishers are affected. In conclusion, management options (closed areas, closed season) for sustainable sea cucumber fisheries and areas for future research are outlined, with an emphasis on co-operation from all stakeholders in terms of knowledge, experience and actions (indigenous knowledge and experience, scientists and government help) to ensure livelihood success. It is recommended that stakeholders in the management processes should include government, exporters, marine and fishery researchers, grant/funding agents, leaders and fisheries extension officers.
Feeding ecology energetics of two sympatric jackal species in the Ngorongoro crater, Tanzania
(University of Dar es Salaam, 2016) Temu, Steven Elisamehe
It is energetically costly for a carnivore to travel long distances or spend a lot of time searching for food without securing enough nutrition for survival and reproduction. Feeding ecology energetics of two sympatric jackal species (golden jackal, Canisaureus and silver-backed jackal, Canismesomelas) was studied by both direct observation of focal animals and indirectly by scat analysis of known individuals. The research was done in the Ngorongoro crater between July 2014 and May 2015, a period that covered both dry and wet seasons. The results revealed that diets of both jackal species were broadly similar in the dry season and included carrion, insects, rodents and plant material while in the wet season the two species also consumed Thomson’s gazelle fawns. Furthermore, the golden jackal also fed on wildebeest placental and hunted for Abdim’s stork during the wet season. This seasonal variation in diets reflects seasonal availability of food items in jackal’s home ranges confirming the opportunistic feeding habit of the two jackal species. There was no significant difference in distance travelled per unit time of foraging between the two species in the dry season and in wet season. However, in the wet season, golden jackals secured significantly higher amount of food (per distance and time of foraging) than the silver-backed jackals (Mann- Whitney U test, p<0.05, U=1035.4, n1=35, n2=44). Effecicient foraging is very important especially in breeding seasons as more food is needed for survival of pups. It is recommended that future studies be conducted outside the crater within Ngorongoro Conservation Area where the jackals are also known to occur. NCAA should consider allowing the night data collection in future studies to enable both day and night sampling of the jackals in order to have better information on the sympatric jackals at night since the animals are known to be active at night too. Key words: Canisaureus, Canismesomelas, efficient foraging, Ngorongoro crater, opportunistic feeding, sympatric
Fisheries status and management aspects of octopus in Unguja Island, Zanzibar; the case of Kizimkazi mkunguni and Uroa areas
(University of Dar es Salaam, 2020) Khamis, Amina Ussi
The study was conducted to assess the fishery status and management aspects of octopus in Unguja Zanzibar, using Kizimkazi Mkunguni as a managed site and Uroa as unmanaged site. The study used longitudinal mixed method design comprises both qualitative and quantitative approaches within longitudinal method. Data was collection over a period of 2 months from April to June 2018. Primary data were collected through questionnaires, key informant interviews, and focus group discussion. Secondary data were collected from online literature, octopus management reports and unpublished data from the Department of Fisheries Development, Zanzibar. In order to examine the catch status and management aspect of octopus fishery, information on total catches landed, fishing effort, methods and gears used, income earned by fishers and distribution of the fishing grounds along the study sites were collected. The findings of the study revealed that generally, the unmanaged (Uroa) site was found to have a larger number and larger sized octopus compared to the managed site (Kizimkazi Mkunguni). Among the factors found to influence the changes includes; fishing methods and gears used size of fishing area and management system. The numbers of foot fishers were higher compared to divers; however, divers were found to catch bigger octopus with regard to size and weight. The study also found that the octopus closure system has management benefits, as significant increase in catches of octopus was observed after opening of the closure area, although these benefits were observed to last only a few days. The study highlights the need for proper management and constant monitoring on the catch trend of octopus. It also stresses the need for effective law enforcement, awareness rising to local communities, and equips SFC with training and financial support to sustain the octopus closure system in Zanzibar
Genetic stock structure and life History of euthynnus affinis cantor (1849) and scomberomorus commerson lacepede (1800) fishes in the northern coastal waters of Tanzania
(University of Dar es Salaam, 2016) Grayson, Johnson Mshana
The population genetic structure and life history traits of Kawakawa Euthynnus affinis Cantor (1949) and Narrow barred Spanish mackerel Scomberomorus commerson Lacepede (1800) in the northern coastal waters of Tanzania, Western Indian Ocean were studied using sequence analysis of mitochondrial DNA (mtDNA) control region. A 475bp and 500bp segment of the control region was sequenced and analyzed (38 and 46 samples of Narrow barred Spanish mackerel and Kawakawa, respectively). The study revealed high levels of haplotype and nucleotide diversities. Analysis of molecular variance (AMOVAL), nearest neighboring statistic (Sm) and exact test of genetic differentiation did not show evidence for population subdivision (p>0.005); hence a null hypothesis that studied fish species constitute a single genetic stock in the northern Tanzania coastal waters could not be rejected. The Tajima’s D and Fu’s Fs models showed a significant deviation from neutral condition (p<0.005), indicative of a recent population expansion. The study revealed a single clade of individual fish species, suggestive of similar genealogical history. The genetic data were also supported by life history traits, which revealed geographical similarities in the spawning patterns, size at maturity and fish condition. In addition, number and size of eggs (µm) for females collected from Dar es Salaam was not statistically higher than those from Pangani (p>0.005). The Presence of genetic similarities for studied fish species was a result of gene flow, short geographical distance (IBD) and homogeneity in environmental distances (IBED, p>0.005). A single-stock model and regional shared management along with further similar research covering the whole Indian Ocean is therefore recommended.
Genetic stock structure and life History of euthynnus affinis cantor (1849) and scomberomorus commerson lacepede (1800) fishes in the northern coastal waters of Tanzania
(University of Dar es Salaam, 2016) Grayson, Johnson Mshana
The population genetic structure and life history traits of Kawakawa Euthynnus affinis Cantor (1949) and Narrow barred Spanish mackerel Scomberomorus commerson Lacepede (1800) in the northern coastal waters of Tanzania, Western Indian Ocean were studied using sequence analysis of mitochondrial DNA (mtDNA) control region. A 475bp and 500bp segment of the control region was sequenced and analyzed (38 and 46 samples of Narrow barred Spanish mackerel and Kawakawa, respectively). The study revealed high levels of haplotype and nucleotide diversities. Analysis of molecular variance (AMOVAL), nearest neighboring statistic (Sm) and exact test of genetic differentiation did not show evidence for population subdivision (p>0.005); hence a null hypothesis that studied fish species constitute a single genetic stock in the northern Tanzania coastal waters could not be rejected. The Tajima’s D and Fu’s Fs models showed a significant deviation from neutral condition (p<0.005), indicative of a recent population expansion. The study revealed a single clade of individual fish species, suggestive of similar genealogical history. The genetic data were also supported by life history traits, which revealed geographical similarities in the spawning patterns, size at maturity and fish condition. In addition, number and size of eggs (µm) for females collected from Dar es Salaam was not statistically higher than those from Pangani (p>0.005). The Presence of genetic similarities for studied fish species was a result of gene flow, short geographical distance (IBD) and homogeneity in environmental distances (IBED, p>0.005). A single-stock model and regional shared management along with further similar research covering the whole Indian Ocean is therefore recommended.
Growth performance, survival and community perspective on sponges farmed in Jambian, Zanzibar- Tanzania
(University of Dar es Salaam, 2019) Hamad, Asma Ahmada
Sponges are important components of marine benthos worldwide. While efforts continue to develop methods for large-scale production of bath sponge, the global supply is too low to satisfy the demand. The present study explored the growth performance, survival and community perspective on sponges farmed in Jambiani, Zanzibar Tanzania. The experiment was set to investigate growth and survival of two commercial both sponges Agelas mauritiana var. oxeata and Callyspongiidae sp using off-bottom and floating raft culture methods. Water displacement method was used to determine initial and final volume of sponges to assess their growth. Household questionnaire survey, focus group discussion and key informant interviews were used collect data on community awareness and perspective towards sponge farming. Descriptive statistics of mean and percentage were used. A multiple comparison test (post hoc analysis) was used to determine variation in survival and growth of sponges between the methods used. Results revealed that, final survival of Callyspongiidae sp varied significantly between farming methods (p<0.05) compared to Agelas Mauritian var. oxeata (p>0.05) Overall, the highest species survival was observed in floating raft method. In contrast, growth of Callyspongiidae sp in floating raft was higher than Agelas mauritiana var. oxeata farmed in both methods. The results showed that a large part of community were aware of sponge farming and are supportive. However, the study suggests that, introduction of sponge farming should not be taken up lightly; there are issues of importance to be considered which include long-term research of ecological feasibility with innovative methods and in-depth social feasibility study.
Impact of climate change and variability on coastal penaeid shrimp abundance in Rufiji delta, Tanzania
(University of Dar es Salaam, 2016) Bwire, Masinde Kahitira
An improved understanding of how key environmental factors drive the abundance and, thus, influence the catch of shrimps is important to prevent a decline or even collapse and to mitigate adverse effects of environmental change including climate change through fishery management. Primary and historical data of shrimp catches, rainfall, flows of the Rufiji River and temperatures were used to assess impact of climate variability on catches of coastal panaeid shrimps in the Rufiji delta. Fishing systems and socio -economic characteristics of shrimp fishers were also examined. Generally, both catches and environmental variables showed temporal variability and strong connectivity among them. Analyses of trend patterns, timing events and intensities for seasonal and interannual variability confirmed that climatic related factors influence the observed declining trends of shrimp catches in the Rufiji delta. Catches were observed to reach maximum peak during May, whereas rainfall and flows of the Rufiji River attain their maximum peaks during April of each year. Timing (phases) events and amplitude (intensities) in rainfall and river flows showed highest positive correlation with catches of coastal panaeid shrimps. Shrimp fishers had generated and adopted their own strategies to deal with a certain degree of variations in their local climate. Some of the adaptation strategies noted include shifting to new fishing areas, diversification of target species, switching and adjusting gear types, and acquiring non-fishing small scale works. This study provided the first scientific results showing drive-response relationship between climate factors and coastal panaeid shrimp catches and lays guiding foundation for formulations of climate resilience management policies of coastal penaeid shrimp fishery in Tanzania.
Impacts of south western Indian ocean tropical cyclones and storms on the rainfall pattern and vegetation productivity over Tanzania
(University of Dar es Salaam, 2018) Kai, Kombo Hamadi
The present-day study investigated the impacts of warmed Southwestern Indian Ocean (SWIO) tropical storms (TSs) and cyclones (TCs) on rainfall pattern and vegetation productivity indices in the coast area of Tanzania using field surveys, remote sensing and statistical modeling tools. The results revealed that over the last 34 December to March (DJFM) and November to May (NM) TCs season, 74 (during DJFM) and90 (during NM) TCs and 154 (during DJFM) and 184 and90 (during NM) TCs was observed. Higher sea surface temperature (SST) anomaly (0.4 to 0.9oC) and higher area averaged SST (27.5 to 28.75oC) over SWIO occurred during September to November (SON) and December to May, while for the case study of TCs the highest SST anomaly (-0.5 to +2.5oC) was observed. Seasonal northward and southward oscillating environmental wind shear (Evws) varies between 0 to 15 ms-1 (at 0o to 15oS) while the zonal mean wind (Umst) ranging between -5 and -15 ms-1 were observed during DJFM. The contribution of TCs/TSs to DJFM rainfall was very significant, with highest rainfall influence over the hinterlands and southern parts of Tanzania compared to the northern coastal areas of Tanzania. The seasonal (DJFM) and NM) TCs/TSs statistical modeling showed strong correlation (p≤0.02) between the observed and the cross-validated TCs/TSs (0.52 0.31, respectively. Moreover, EVI and NDVI results were consistent with the patterns shown by analysis of rainfall data.

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