Abundance and Distribution of Afrosteles distans an Indicator of Food Availability for the Kihansi Spray Toad (Nectophrynoides asperginis) in the Kihansi Gorge

Survivorship of the Kihansi Spray Toad in the wild depends on various factors such as environment, habitat, food availability, diseases and predation. This study assessed the abundance of Afrosteles distans Linnavuori 1959 as an indicator of food availability for the Kihansi Spray Toad. Samples were collected from sprinkled (A, B, C, D, E and F) and non-sprinkled (G and H) plots in the upper spray wetland in the Kihansi gorge during the dry period in 2007, 2008, 2015, 2016 and 2018. There was a significantly higher abundance of A. distans in sprinkled than non-sprinkled plots. ANOVA showed significant differences in the abundance of A. distans among plots in each year. ANOSIM (Global R = 0.756, p = 0.001) showed a significant difference between plots with an increasing trend (E, F and D) and plots with a decreasing trend (A, B and C). Cluster analysis resulted in 62% similarity of plots A, B and C and 68% similarity of plots E, F and D. Favourable conditions for the A. distans were not homogenous among the sprinkled plots and continued to vary over time. Abundance levels of A. distans and occurrence of other invertebrates indicated that food for the KST was sufficiently available in the gorge. Keywords: Afrosteles distans; Abundance; Kihansi Spray Toad; KST; Kihansi gorge

Study on the Water Quality Parameters in Semi-Intensive Coastal Shrimp Culture System in Mafia Island, Tanzania

This study was conducted to understand the effect of coastal shrimp farming on water quality properties in the surrounding area of a semi-intensive culture system in Mafia Island, Tanzania. Monthly water samples were collected from six stations located within culture ponds, inlet creek and outlet/effluent creek, from June, 2008 to May, 2009, and November, 2009 to March, 2010. The samples were used for the analysis of the selected water quality parameters following the standard procedures. The data obtained was analyzed using one way ANOVA and significant differences accepted at p ? 0.05. Post Hoc Turkeys’ test was used to determine the specific stations which were sources of differences. Correlation co-efficient (r) was performed to establish the relation between independent and dependent parameters. Results showed that DO, salinity, NH4-N, NO2-N and PO4-P were significantly (p<0.05) higher in sampling stations inside culture ponds. NO3-N had significantly (p<0.05) higher mean values at the stations along the effluent creek. No significant differences (p>0.05) were recorded between the stations in terms of temperature, EC and chlorophyll-a. High positive correlations (r = 0.646–0.927) between EC and dissolved nutrients is an indication of common origin of these parameters that is, mineralization of organic materials. In general, concentrations of all analysed parameters were within the desirable and acceptable limits for marine ecosystems. To sustain the present conditions it is being recommended to adopt better farm husbandry as well as treating effluent materials before discharging them to the marine water medium. The study would provide essential information on which further studies can be carried out to evaluate the environmental impacts of marine aquaculture and, supports protection and decision making for sustainable development in the coastal areas. Keywords: Semi-intensive shrimp culture, Water quality, inorganic nutrients, environmental impacts, Mafia Island

Assessment of pond and integrated aquaculture (IAA) systems in six districts of Tanzania

Integrated agriculture and aquaculture systems (IAA) are well known for their ability to improve the overall farm productivity and profitability. This is through recycling of on-farm resources, such as nutrient rich fish pond water and agriculture remains that would otherwise be considered as wastes. The present study explores the existing and potential IAA systems in Tanzania. It also examines management strategies and their influence on fish yield and the economic returns between IAA and non-IAA fish farming. The study assesses farmer’s socio-demographic characteristics and their perception towards fish farming. The study was conducted through an on-site survey of 129 fish ponds owned by 89 farmers in six districts in Tanzania, involving 65 and 64 IAA and non-IAA ponds respectively. Results indicate that tilapia-vegetables is the most common type of IAA practiced by fish famers. Despite higher fish feed use and stocking density in non-IAA ponds, IAA ponds had an average fish yield of 2.46 t ha-1, which was significantly (p0.05) higher than the fish yield of 1.54 t ha-1 found for non-IAA ponds. IAA ponds had also 1.6 and 2.9 times higher (p 0.05) revenue and net profit, respectively, than non-IAA ponds. Additionally, the net return from IAA ponds in an integrated system was significantly (p0.05) higher than when practiced as stand-alone activities. IAA famers were more positive towards fish farming compared to non-IAA farmers. Thus, IAA systems should be promoted among small-scale farmers to cover for an increased fish demand and to improve food security

Integration of Nile tilapia (Oreochromis niloticus) and vegetables (Amaranthus hybridus and Brassica rapa pekinensis) for improved production, water use efficiency and nutrient recycling

Sustainable agriculture intensification is an urgent challenge in developing countries including Tanzania. One potential solution is to adopt farming systems that increase farm production by optimizing resource use efficiency, and integrated aquaculture system, which involves farming of fish and crops, is an example of such systems. This study investigated the impact of Integrated agriculture and aquaculture (IAA) farming on water use efficiency, fish and vegetable production and overall system profitability, and how these parameters are affected by fish stocking densities. Oreochromis niloticus (2.5 g average initial weight) were cultured at low stocking density (five fish m−3, LSD), medium stocking density (eight fish m−3, MSD), and high stocking density (12 fish m−3, HSD) for 205 days. Brassica rapa pekinensis and Amaranthus hybridus cultivated adjacent to the fish tanks were irrigated with; (i) fish tank water, without any fertilizer inputs; (ii) fish tank water, partially fertilized; (iii) tap water, fully fertilized (farmers’ practice); and (iv) tap water without any fertilizer inputs. Although the use of tank water from the high fish stocking density resulted in significantly higher vegetable yield, high fish stocking resulted in lower fish growth, profitability and water use efficiency compared to the other fish stocking densities, probably because of low survival rates (28%) at high stocking densities. The integration of fish at a medium stocking density with vegetables resulted in significantly higher net income than when fish and vegetables were grown separately

Rural aquaculture: Assessment of its contribution to household income and farmers' perception in selected districts, Tanzania

Rural fish farming is being promoted as a good source of protein and income diversification to fight poverty and inequality. However, its actual contribution to these rural households and local community at large is little known. Through interviews with 89 farmers' and 6 key informants, we examined the contribution of rural fish farming to local farmers' household income and investigate farmers' perceptions, opportunities, and constraints towards fish farming in six districts of Tanzania. Results indicated that fish farming contributed on average 13% to household incomes and that it explained 5% of the variation of the household income while 84% of the variation was due to non-fish sources. The majority (79%) of the farmers wanted to continue with fish farming, 9% planned to quit, and 12% had not decided whether to continue or not. Conclusively, much higher aquaculture contribution towards rural development could be obtained if appropriate measures are taken

Investigating the influence of habitat structure and hydraulics on tropical macroinvertebrate communities

[EN] The influences of habitat structure and hydraulics on tropical macroinvertebrate communities were investigated in two foothill rivers of the Udzungwa Mountains (United Republic of Tanzania) to assist future Environmental Flow Assessments (EFAs). Macroinvertebrate samples, hydraulic variables and habitat structure were collected at the microhabitat scale (n = 90). Macroinvertebrate communities were first delineated (i.e. clustered) through Poisson and negative binomial mixture models for count data in a semi-supervised mode by taking into account the sampled river. Then, genetically optimised Multi-Layer Perceptrons (MLPs) were used to identify the relationship of the most relevant variables with the delineated communities. Between the three delineated communities exclusively one community was shared between both rivers. The first and third communities presented similar values of richness (i.e. number of families) and diversity but the first was characterised by high abundance and was dominated by Baetidae (43.2%) while Hydropsychidae (36.3%) dominated the third community. The second community was dominated by Baetidae (33.4%), but it involved low abundance, richness and diversity samples and encompassed the microhabitats where no-macroinvertebrates were found. The performance of the MLP acknowledged the quality of the delineation and it indicated that the first community shows a clear affinity for microhabitats with aquatic vegetation and woody debris and the third for unshaded, fast flowing and shallow microhabitats on intermediate-sized substrate. Conversely, the second community occurred in deep and shaded microhabitats with low flow velocity and coarse substrate. We demonstrated that habitat structure and hydraulics are able to properly discriminate the macroinvertebrate communities, which, in turn, underlines their importance as drivers of community composition and abundance. Aquatic vegetation, woody debris, velocity and substrate index, followed by depth and shade, emerged as the most discriminant variables to understand macroinvertebrate communities in these tropical running waters. These results should enhance the implementation of ongoing and future EFA studies. (C) 2018 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.This study was financed by the United States Agency for International Development (USAID) as part of the Technical Assistance to Support the Development of Irrigation and Rural Roads Infrastructure Project (IRRIP2), implemented by CDM International Inc. J. Sanchez-Hernandez was supported by a postdoctoral grant from the Galician Plan for Research, Innovation, and Growth (Plan I2C, Xunta de Galicia).Muñoz Mas, R.; Sánchez-Hernández, J.; Mcclain, M.; Tamatamah, R.; Mukama, SC.; Martinez-Capel, F. (2019). Investigating the influence of habitat structure and hydraulics on tropical macroinvertebrate communities. Ecohydrology & Hydrobiology. 19(3):339-350. https://doi.org/10.1016/j.ecohyd.2018.07.005S33935019

Microhabitat preferences of fish assemblages in the Udzungwa Mountains (Eastern Africa)

[EN] Environmental flow assessment (EFA) involving microhabitat preference models is a common approach to set ecologically friendly flow regimes in territories with ongoing or planned projects to develop river basins, such as many rivers of Eastern Africa. However, habitat requirements of many African fish species are poorly studied, which may impair EFAs. This study investigated habitat preferences of fish assemblages, based on species presence-absence data from 300 microhabitats collected in two tributaries of the Kilombero River (Tanzania), aiming to disentangle differences in habitat preferences of African species at two levels: assemblage (i.e. between tributaries) and species (i.e. species-specific habitat preferences). Overall, flow velocity, which implies coarser substrates and shallower microhabitats, emerged as the most important driver responsible of the changes in stream-dwelling assemblages at the microhabitat scale. At the assemblage level, we identified two important groups of species according to habitat preferences: (a) cover-orientated and limnophilic species, including Barbus spp., Mormyridae and Chiloglanis deckenii, and (b) rheophilic species, including Labeo cylindricus, Amphilius uranoscopus and Parakneria spekii. Rheophilic species preferred boulders, fast flow velocity and deeper microhabitats. At the species level, we identified species-specific habitat preferences. For instance, Barbus spp. preferred low flow velocity shallow depth and fine-to-medium substratum, whereas L. cylindricus and P. spekii mainly selected shallow microhabitats with coarse substrata. Knowledge of habitat preferences of these assemblages and species should enhance the implementation of ongoing and future EFA studies of the region.We thank C. Alexander and an anonymous referee for constructive comments on the submitted manuscript. This study was financed by the United States Agency for International Development (USAID) as part of the Technical Assistance to Support the Development of Irrigation and Rural Roads Infrastructure Project (IRRIP2), implemented by CDM International Inc. We are particularly grateful to the local people who helped us during the data collection. We also gratefully acknowledge individuals from organisations that collaborated in this research and especially the scientific committee that shared their knowledge of the Kilombero River basin. These individuals include the following: J.J. Kashaigili (SUA), K.N. Njau (NM. AIST), P.M. Ndomba (UDSM), F. Mombo (SUA), S. Graas (UNESCO- IHE), C.M. Mengo (RUFIJI BASIN), J.H. O'keeffe (Rhodes Univ.), S.M. Andrew (SUA), P. Paron (UNESCO-IHE), W. Kasanga (CDM Smith), and R. Tharme (RIVER FUTURES). R. Muñoz-Mas benefitted from a postdoctoral Juan de la Cierva fellowship from the Spanish Ministry of Science, Innovation and Universities (ref. FJCI-2016-30829) and J. Sánchez-Hernández was supported by a postdoctoral grant from the Galician Plan for Research, Innovation and Growth (Plan I2C, Xunta de Galicia). Additional funding was provided by the Ministry of Science, Innovation and Universities (projects CGL2016-80820-R and PCIN-2016-168) and the Government of Catalonia (ref. 2017 SGR 548).Muñoz-Mas, R.; Sánchez-Hernández, J.; Martinez-Capel, F.; Tamatamah, R.; Mohamedi, S.; Massinde, R.; Mcclain, ME. (2019). Microhabitat preferences of fish assemblages in the Udzungwa Mountains (Eastern Africa). Ecology Of Freshwater Fish. 28(3):473-484. https://doi.org/10.1111/eff.12469S473484283Akbaripasand, A., & Closs, G. P. (2017). Effects of food supply and stream physical characteristics on habitat use of a stream-dwelling fish. Ecology of Freshwater Fish, 27(1), 270-279. doi:10.1111/eff.12345Alexander, C., Poulsen, F., Robinson, D. C. E., Ma, B. O., … Luster, R. A. (2018). 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Whole genome resequencing data enables a targeted SNP panel for conservation and aquaculture of Oreochromis cichlid fishes

Cichlid fish of the genus Oreochromis form the basis of the global tilapia aquaculture and fisheries industries. Broodstocks for aquaculture are often collected from wild populations, which in Africa may be from locations containing multiple Oreochromis species. However, many species are difficult to distinguish morphologically, hampering efforts to maintain good quality farmed strains. Additionally, non-native farmed tilapia populations are known to be widely distributed across Africa and to hybridize with native Oreochromis species, which themselves are important for capture fisheries. The morphological identification of these hybrids is particularly unreliable. Here, we describe the development of a single nucleotide polymorphism (SNP) genotyping panel from whole-genome resequencing data that enables targeted species identification in Tanzania. We demonstrate that an optimized panel of 96 genome-wide SNPs based on FST outliers performs comparably to whole genome resequencing in distinguishing species and identifying hybrids. We also show this panel outperforms microsatellite-based and phenotype-based classification methods. Case studies indicate several locations where introduced aquaculture species have become established in the wild, threatening native Oreochromis species. The novel SNP markers identified here represent an important resource for assessing broodstock purity in hatcheries and helping to conserve unique endemic biodiversity

Widespread colonisation of Tanzanian catchments by introduced Oreochromis tilapia fishes: the legacy from decades of deliberate introduction

From the 1950s onwards, programmes to promote aquaculture and improve capture fisheries in East Africa have relied heavily on the promise held by introduced species. In Tanzania these introductions have been poorly documented. Here we report the findings of surveys of inland water bodies across Tanzania between 2011 and 2017 that clarify distributions of tilapiine cichlids of the genus Oreochromis. We identified Oreochromis from 123 sampling locations, including 14 taxa restricted to their native range and three species that have established populations beyond their native range. Of these three species, the only exotic species found was blue-spotted tilapia (Oreochromis leucostictus), while Nile tilapia (Oreochromis niloticus) and Singida tilapia (Oreochromis esculentus), which are both naturally found within the country of Tanzania, have been translocated beyond their native range. Using our records, we developed models of suitable habitat for the introduced species based on recent (1960–1990) and projected (2050, 2070) East African climate. These models indicated that presence of suitable habitat for these introduced species will persist and potentially expand across the region. The clarification of distributions provided here can help inform the monitoring and management of biodiversity, and inform policy related to the future role of introduced species in fisheries and aquaculture

Growth perfomance of Tilapia sparmanni fed on formulated chicken feeds

Growth performance of 120 fi sh fi ngerlings of Tilapia sparmanni stocked in three rectangular tanks was evaluated after feeding on three different formulated chicken feeds for eight weeks. Fish wet weights and lengths were measured after every two weeks, they indicated considerable increase.</p