Preliminary gut content and dentition analysis reveal subtle resource partitioning and feeding adaptations within a haplochromine cichlid community of Lake Victoria satellite lake

The trophic relationships between six haplochromine cichlids of Lake Kanyaboli, a satellite lake of Lake Victoria that has not been infested by the Nile perch (Lates niloticus), were studied as a first step towards understanding the cichlid community structure in this threatened wetland ecosystem. Coefficient of similarity analysis of diet revealed subtle trophic resource partitioning within this haplochromine community. Trophic specializations are further revealed by differences in dentition structures. Of the six haplochromine species examined, Astatotilapia nubila and Astatoreochromis alluadi had the highest coefficient of similarity (0.5256±0.300), indicating highest diet overlap, while Astatotilapia ‘big eye’ and Xistichromis phytophagus were the most ecologically separated (0.0210±0.019). Resource partitioning is further enhanced by a diurnal spatial distribution of the six species within the lake. Overall, the haplochromine cichlid community of Lake Kanyaboli is characterized by a relatively high trophic diversity compared to Lake Victoria. Small water bodies (SWBs) thus present opportunities for conservation of trophic diversity threatened by introduction of exotics in the Lake Victoria basin.Key words: Community structure, haplochromines, resource partitioning, satellite lakes, trophic ecology

An alternative management strategy for Lake Victoria (Kenya)

In Kenya, fisheries resource management has been based on the top-down centralized approach since the colonial days. Stakeholders have never been consulted concerning management decisions. The 4-beaches Study was undertaken to investigate the potential for an alternative management system for Lake Victoria

Marketing study

The findings are presented of a marketing survey conducted in the lake Victoria region. The research concentrated on consumers, trader /processors serving local markets, industrial processors serving mainly international markets, and fishers. The market for fish from Lake Victoria is traced from the consumer to the producer, including as many components of the chain as possible. The components are dealt with in individual sections which comprise a profile of a typical consumer/trader-processor/industrial processor /fisher, a list of survey sites, a map showing locations, a note on potential biases within the individual survey, a list of hypotheses or study topics for all surveys except for that of industrial processors, detailed analyses and also the pertinent questionnaire

The survey of Lake Victoria's fishers

The findings are presented of a survey conducted regarding the fishers of Lake Victoria, which examined the relationships affecting supply flows of raw material on to the market, and also the characteristics of fishing activities and their effects on fish quality and distribution. Fish marketing plays a vital role in the lives of much of the lake basin's population, both in terms of employment and nutrition. The results of the survey comprise, in part, a base-line data set which will facilitate further research, analysis and management decision-making in relation to stakeholders of the lake's resources. Data collection, methods and research difficulties encountered are described and details given of a profile of a boat owner/renter and aslo of a profile of a crew member. The survey shows that Lake Victoria's fishery is one of very limited diversity. The fishers recount that they consistently target one or more of the 3 most common species within the lake (Nile perch, tilapia and dagaa) and very rarely consider any other species type. The largest proportion of fishers on the lake are Nile perch fishers; there is considerable demand for this species, and hence fishers have little incentive to either target alternative fish species, not to try and establish firm marketing outlets through the creation of arrangements with their principal buyers. In Kenyan waters, however, the number of Nile perch fishers is equaled by the number of dagaa fishers; this fish now commands a considerable portion of the market for fish from Lake Victoria through its availability as well as its relatively low prices. The tilapia fishery is in decline, and all 3 riparian states would not appear to be attracting investment almost certainly as a result of declining catches. For many of those working in Lake Victoria's fishery, the problems faced appear most often to be associated with the vagaries of an unstable market which may rise or fall depending on the state of the international market or the state of access roads to fish landings. (PDF contains 42 pages

List of institutions of managerial relevance to the fisheries of Lake Victoria

The list provides addresses of institutions in Kenya, Tanzania and Uganda which are of managerial relevance to the fisheries of Lake Victoria, indicating the relevant area covere

Empowering Seafarers as Agents of Their Mental Health: The Role of Information and Communication Technology in Seafarers’ Well-Being

The academic literature seldom views information and communication technology (ICT) as a means to empower merchant seafarers in terms of their active and positive contributions to their mental health (MH) and overall well-being. Seafarers are often viewed as recipients and not the sources of health interventions. Using mixed methods, this paper examines how seafarers’ MH has not been the top priority among seafarers themselves, and how ICT and formal education might empower seafarers in health promotion. The pervasive culture of “ship first” in the maritime industry is palpable in the findings of this study, where seafarers do not prioritize their MH because the ship’s safe operations take precedence over everything else. Data shows that seafarers perceive MH interventions provided by companies as more useful when these have direct implications or effects on their families. In effect, seafarers may not see a priorities the physical and mental health support directly impacting their well-being. Nevertheless, there are some fundamental changes in the maritime industry in using technology to improve the MH of seafarers and their overall well-being, such as the development of MH applications (“apps”), helplines, or websites, coupled with the growing comfort of seafarers to use ICT. </jats:p

Genetic diversity and population structure of the African catfish, <i>Clarias gariepinus</i> (Burchell, 1822) in Kenya: implication for conservation and aquaculture

African catfish, Clarias gariepinus, is an important species in aquaculture and fisheries in Kenya. Mitochondrial D-loop control region was used to determine genetic variation and population structure in samples of C. gariepinus from 10 sites including five natural populations (Lakes Victoria (LVG), Kanyaboli (LKG), Turkana (LTA), Baringo (LBA) and Jipe (LJP), and five farms (Sangoro Aquaculture Center (SAN), Sagana Aquaculture Centre (SAG), University of Eldoret Fish Farm (UoE), Kibos Fish Farm (KIB), and Wakhungu Fish Farm (WKU)) in Kenya. Similarly, samples from eight localities (four natural populations: LVG/LKG, LTA, LBA, and four farmed: SAN, SAG, KIB, UoE) were genotyped using six microsatellite DNA loci. For the D-loop control region, samples from natural sites exhibited higher numbers of haplotypes and haplotype diversities compared to farmed samples, and 88.2% of haplotypes were private. All except LJP and LTA shared haplotypes, and the highest number of shared haplotypes (8) was detected in KIB. The 68 haplotypes we found in 268 individuals grouped into five phylogenetic clades: LVG/LKG, LTA, LBA, LJP and SAG. Haplotypes of farmed C. gariepinus mostly have haplotypes typical of LVG/LKG, and some shared haplotypes of the LBA population. Microsatellite analysis showed farmed samples have higher numbers of alleles than natural samples, but higher observed and expected heterozygosity levels were found in samples of natural populations. Fifteen pair-wise comparisons had significantly different FST values. All samples were in Hardy-Weinberg equilibrium. Samples from the eight localities grouped into four genetic clusters (LVG/LKG, LTA, LBA and SAG), indicating genetically distinct populations, which should be considered for aquaculture and conservation

Longitudinal trends of future climate change and oil palm growth: empirical evidence for tropical Africa

Palms are highly significant tropical plants. Oil palms produce palm oil, the basic commodity of a highly important industry. Climate change from greenhouse gasses is likely to decrease the ability of palms to survive, irrespective of them providing ecosystem services to communities. Little information about species survival in tropical regions under climate change is available and data on species migration under climate change is important. Palms are particularly significant in Africa: a palm oil industry already exists with Nigeria being the largest producer. Previous work using CLIMEX modelling indicated that Africa will have reduced suitable climate for oil palm in Africa. The current paper employs this modelling to assess how suitable climate for growing oil palm changed in Africa from current time to 2100. An increasing trend in suitable climate from west to east was observed indicating that refuges could be obtained along the African tropical belt. Most countries had reduced suitable climates but others had increased, with Uganda being particularly high. There may be a case for developing future oil palm plantations towards the east of Africa. The information may be usefully applied to other palms. However, it is crucial that any developments will fully adhere to environmental regulations. Future climate change will have severe consequences to oil palm cultivation but there may be scope for eastwards mitigation in Africa.info:eu-repo/semantics/publishedVersio

High performance computation of landscape genomic models including local indicators of spatial association

With the increasing availability of both molecular and topo-climatic data, the main challenges facing landscape genomics – that is the combination of landscape ecology with population genomics – include processing large numbers of models and distinguishing between selection and demographic processes (e.g. population structure). Several methods address the latter, either by estimating a null model of population history or by simultaneously inferring environmental and demographic effects. Here we present samβada, an approach designed to study signatures of local adaptation, with special emphasis on high performance computing of large-scale genetic and environmental data sets. samβada identifies candidate loci using genotype–environment associations while also incorporating multivariate analyses to assess the effect of many environmental predictor variables. This enables the inclusion of explanatory variables representing population structure into the models to lower the occurrences of spurious genotype–environment associations. In addition, samβada calculates local indicators of spatial association for candidate loci to provide information on whether similar genotypes tend to cluster in space, which constitutes a useful indication of the possible kinship between individuals. To test the usefulness of this approach, we carried out a simulation study and analysed a data set from Ugandan cattle to detect signatures of local adaptation with samβada, bayenv, lfmm and an FST outlier method (FDIST approach in arlequin) and compare their results. samβada – an open source software for Windows, Linux and Mac OS X available at http://lasig.epfl.ch/sambada – outperforms other approaches and better suits whole-genome sequence data processing