Patterns of fish community structure in protected and non-protected marine areas of mainland Tanzania

Information on the benefits of Marine Protected Areas (MPAs) for the condition of fish stocks is not well documented in Tanzania. Fish landing sites located in Tanga and Mtwara regions were surveyed to assess patterns of fish community structure; particularly fish abundance, species diversity, growth patterns, and maturity stages, based on catches landed at sites with different protection status. Fish abundance in the catch from protected areas was significantly lower than in non-protected areas (p=0.002). Species diversity was relatively higher in catches from non-protected (H=2.742) compared to protected areas (H=2.232). A high percentage of species (63.24 %) exhibiting negative allometric growth was observed in catches from non-protected areas. Further, a large number of mature fish was observed in catches from protected areas compared to non-protected areas (p<0.01). These indices are useful indicators of the performance of MPAs. The observed negative allometric growth and reduced number of mature fishes in the non-protected areas suggest that extractive pressure and disturbances from fishing gears have negative impacts on the fish stock. Continued high extraction may induce a decline in general fish size due to the constant selection for large-trait fish specimens, potentially causing evolutionally change in morphological traits. In contrast, the lower abundance and species diversity from the protected areas reflected low catch effort as a result of regulated fishing pressure in MPAs, rather than indicating the actual diversity in the fish stocks in these protected waters. Based on these findings it is recommended that more regulatory strategies are implemented in non-protected waters to allow more time for fish to attain appropriate harvest sizes and to ensure the effective protection of marine resources

Persistente organiske forbindelser og tungmetaller i fisk fra Tanzania : nivåer og relatert helse risiko for mennesker og fisk

Diet is considered as the main route of exposure to pollutants such as persistent organic pollutants (POPs) and heavy metals to humans during lifetime. POPs and heavy metals are both persistent and can bioaccumulate in the tissues of organisms and biomagnify up in food chains. POPs are lipophilic and hence they can accumulate in lipid tissues of animal food stuffs, such as fish, eggs and meat. Therefore, they can accumulate considerable amount of POPs and heavy metals. POPs and heavy metals are potentially toxic to living organisms, such as humans and fish. The main aims of this study were to identify the occurrence and levels of persistent organic pollutants (POPs) and heavy metals in farmed, wild and imported fish in Tanzania and to increase knowledge on potential health risks related to consuming fish contaminated by POPs and heavy metals in Tanzania The main findings from this study were that levels of POPs and heavy metals in farmed and wild fish from Tanzania varied widely between locations indicating exposure from various sources. The levels of DDTs and Pb were higher in wild fish compared to farmed fish in Tanzania. The ratio of p,p’-DDE to p,p’-DDT suggested both recent and historical use of DDT. The study revealed Pb levels above MLs in 100% of the studied fish from Tanzania. In the imported fish from China, significant variation in levels and patterns of POPs and heavy metals were found between the individual fish. The study also suggests that importing commodities from China may be a pathway of introducing compounds like PCB-209 and HBCDD to Tanzania. Assessment of human health risk suggested possible adverse health effect due to DL-PCB-118 and -105 and As from consumption of tilapia from China. The assessment of fish health risk in this study revealed that PBDEs and Hg may pose possible adverse health effects in fish and may pose ecological health risk and threatens biodiversity

Persistent Organic Pollutants (POPs) and heavy metals in fish from Tanzania : levels and associated health risks to humans and fish

Diet is considered as the main route of exposure to pollutants such as persistent organic pollutants (POPs) and heavy metals to humans during lifetime. POPs and heavy metals are both persistent and can bioaccumulate in the tissues of organisms and biomagnify up in food chains. POPs are lipophilic and hence they can accumulate in lipid tissues of animal food stuffs, such as fish, eggs and meat. Therefore, they can accumulate considerable amount of POPs and heavy metals. POPs and heavy metals are potentially toxic to living organisms, such as humans and fish. The main aims of this study were to identify the occurrence and levels of persistent organic pollutants (POPs) and heavy metals in farmed, wild and imported fish in Tanzania and to increase knowledge on potential health risks related to consuming fish contaminated by POPs and heavy metals in Tanzania The main findings from this study were that levels of POPs and heavy metals in farmed and wild fish from Tanzania varied widely between locations indicating exposure from various sources. The levels of DDTs and Pb were higher in wild fish compared to farmed fish in Tanzania. The ratio of p,p’-DDE to p,p’-DDT suggested both recent and historical use of DDT. The study revealed Pb levels above MLs in 100% of the studied fish from Tanzania. In the imported fish from China, significant variation in levels and patterns of POPs and heavy metals were found between the individual fish. The study also suggests that importing commodities from China may be a pathway of introducing compounds like PCB-209 and HBCDD to Tanzania. Assessment of human health risk suggested possible adverse health effect due to DL-PCB-118 and -105 and As from consumption of tilapia from China. The assessment of fish health risk in this study revealed that PBDEs and Hg may pose possible adverse health effects in fish and may pose ecological health risk and threatens biodiversity

Operational Risk Management at Planning Phase and Project Performance in Tanzania

Projects are unique entities that are conducted within a specific start-point and a definite end-point and time constraint is one among its characteristics, because of its uniqueness, projects tend to face a lot of risks as they are unpredictable and inevitable hence the adoption of risk management throughout the project life cycle so that the objectives are achieved. This research intends to examine the relationship between Operational Risk Management at the planning phase and project performance in Tanzania, specifically in the Insurance industry. The objective of the study was to investigate the extent of the risk management practices at planning phase and the effect of these practices on project performance. The study targeted insurers, project managers, actuaries, and regulatory authorities in Tanzania and key clients with major investments in the insurance industry. The study used both qualitative and quantitative methods of data collection. The research project indicated projects in Tanzania had some input from qualified insurers. While the study indicated that risk management was widely practiced at 92%, the process was mainly informal. It is recommended a formal and structured risk management practice during project planning and with the involvement of insurance professionals and end users. The researcher recommends that there is need for continuous development seminars in risk management for all insurance professionals in Tanzania and especially those in insurance projects planning and procurement departments of both private and government developers. This research further recommends that qualified project managers who are either insurers or actuaries be included in all insurance projects. End users and beneficiaries should be involved in needs identification at the early stages of a project

Effects of cadmium uptake on growth and productivity of Chinese cabbage (Brassica rapa subsp. pekinensis) and pumpkin (Cucurbita moschata Duchesne) vegetables

Cadmium (Cd) is recognized as one of the most toxic elements to plants and humans when available in higher concentrations. In the present study, a pot experiment was carried out to investigate the effect of different Cd levels (0, 10, 20, 30, and 40 mg/kg) on the growth, production, and uptake of Cd using Chinese cabbage (Brassica rapa subsp. pekinensis) and pumpkin leaves (Cucurbita moschata Duchesne) vegetables. The study found significant differences (P < 0.05) in all growth parameters in the studied vegetables. The Cd treatments resulted in decreasing number of leaves, shoot fresh weight, shoot dry weight, and total dry weight in both vegetables compared to the control. The total dry weight of Chinese cabbage was decreased by 6.79%, 48.42%, 5.88%, and 5.43%, at 10, 20, 30, and 40 mg/kg respectively compared to the control. In pumpkin leaves total dry weight was decreased by 28.95%, 28.95%, 18.42%, and 14.47% at 10, 20, 30, and 40 mg/kg respectively compared to the control. Increase and decrease effects on root length were observed for all the vegetables. Pumpkin leaves showed increased root length at 10 mg/kg (61.39%), 20 mg/kg (17.87%), and 30 mg/kg (70.03%) while at 40 mg/kg, there was a decrease in root length by 20.13% as compared to the control. The root length of Chinese cabbage decreased by 25.05%, 8.4%, and 7.26% at 20 mg/kg, 30 mg/kg, and 40 mg/kg compared to the control except at 10 mg/kg which was found to be higher by 0.6% compared to the control.The Cd treatment in soil resulted in the increase of shoot Cd concentration in all the vegetables with maximum concentration observed at 20 mg/kg. Therefore, agricultural soil with elevated Cd levels will affect pumpkin and Chinese cabbage cultivation but also the consumption of such vegetables may result to toxic effects on human health

Spatial Variation in Contaminant Occurrence in Marine Fishes and Prawns from Coastal Tanzania

There are limited data on organic contaminants in marine biota from coastal Tanzania, especially on the occurrence of industrial-use contaminants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The present study, performed in 2018–2019 in coastal Tanzania and Zanzibar Island, aimed at assessing spatial variation in the occurrence of PCBs; brominated flame retardants (BFRs), including PBDEs; and organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT), among three locations that differ in degree of anthropogenic activity. Analyzed samples included edible tissues of marine fishes and prawns representing different trophic levels and habitats. The results indicate a mainland–island difference, with fishes and prawns collected on Zanzibar having significantly lower PCB and DDT concentrations but higher concentrations of hexachlorobenzene compared to the two mainland locations. The highest contaminant concentrations were found in fishes and prawns collected around central Dar es Salaam harbor, with median ΣPCBs ranging from 22.3 to 577 ng/g lipid weight and ΣDDTs from 22.7 to 501 ng/g lipid weight, suggesting local sources. Concentrations of PBDEs were similar among locations, suggesting more diffuse sources. None of the “newer-type” BFRs, including compounds introduced as replacements for PBDEs, were detected in the present study. Stable isotope values of carbon (δ13C) and nitrogen (δ15N) varied among locations, and the relationship between contaminants and δ15N varied among locations and habitat (pelagic/demersal). Concentrations measured in the present study are below European guidelines for human consumption of fishes and prawns. However, industrial-use contaminants should be monitored in developing countries because they are contaminants of emerging concern as a result of increasing industrialization and global trade of used products and wastes

Spatial Variation in Contaminant Occurrence in Marine Fishes and Prawns from Coastal Tanzania

There are limited data on organic contaminants in marine biota from coastal Tanzania, especially on the occurrence of industrial-use contaminants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The present study, performed in 2018–2019 in coastal Tanzania and Zanzibar Island, aimed at assessing spatial variation in the occurrence of PCBs; brominated flame retardants (BFRs), including PBDEs; and organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT), among three locations that differ in degree of anthropogenic activity. Analyzed samples included edible tissues of marine fishes and prawns representing different trophic levels and habitats. The results indicate a mainland–island difference, with fishes and prawns collected on Zanzibar having significantly lower PCB and DDT concentrations but higher concentrations of hexachlorobenzene compared to the two mainland locations. The highest contaminant concentrations were found in fishes and prawns collected around central Dar es Salaam harbor, with median ΣPCBs ranging from 22.3 to 577 ng/g lipid weight and ΣDDTs from 22.7 to 501 ng/g lipid weight, suggesting local sources. Concentrations of PBDEs were similar among locations, suggesting more diffuse sources. None of the “newer-type” BFRs, including compounds introduced as replacements for PBDEs, were detected in the present study. Stable isotope values of carbon (δ13C) and nitrogen (δ15N) varied among locations, and the relationship between contaminants and δ15N varied among locations and habitat (pelagic/demersal). Concentrations measured in the present study are below European guidelines for human consumption of fishes and prawns. However, industrial-use contaminants should be monitored in developing countries because they are contaminants of emerging concern as a result of increasing industrialization and global trade of used products and wastes

Accumulation and distribution of mercury in agricultural soils, food crops and associated health risks: A case study of Shenda gold mine-Geita Tanzania

Contamination of the environment and foodstuff by potentially harmful elements (PHEs) has become a serious concern due to the associated health risks to the population. In the present study total mercury (Hg) levels in soil and food crops from farms around Shenda gold mine in Geita Tanzania was determined by Cold Vapor Atomic Fluorescence Spectrometry (CVAFS). Generally, it was found that there was significant different of Hg content in soil and food crops (P 1, indicating a potential non-carcinogenic risk to adult population from the consumption of rice grain from the study area. Therefore, people living near Shenda goldmine might be potential victim of Hg accumulation in soil and food crops, thus necessary management options have to be in place

Spatial Variation in Contaminant Occurrence in Marine Fishes and Prawns from Coastal Tanzania

There are limited data on organic contaminants in marine biota from coastal Tanzania, especially on the occurrence of industrial-use contaminants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The present study, performed in 2018–2019 in coastal Tanzania and Zanzibar Island, aimed at assessing spatial variation in the occurrence of PCBs; brominated flame retardants (BFRs), including PBDEs; and organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT), among three locations that differ in degree of anthropogenic activity. Analyzed samples included edible tissues of marine fishes and prawns representing different trophic levels and habitats. The results indicate a mainland–island difference, with fishes and prawns collected on Zanzibar having significantly lower PCB and DDT concentrations but higher concentrations of hexachlorobenzene compared to the two mainland locations. The highest contaminant concentrations were found in fishes and prawns collected around central Dar es Salaam harbor, with median ΣPCBs ranging from 22.3 to 577 ng/g lipid weight and ΣDDTs from 22.7 to 501 ng/g lipid weight, suggesting local sources. Concentrations of PBDEs were similar among locations, suggesting more diffuse sources. None of the “newer-type” BFRs, including compounds introduced as replacements for PBDEs, were detected in the present study. Stable isotope values of carbon (δ13C) and nitrogen (δ15N) varied among locations, and the relationship between contaminants and δ15N varied among locations and habitat (pelagic/demersal). Concentrations measured in the present study are below European guidelines for human consumption of fishes and prawns. However, industrial-use contaminants should be monitored in developing countries because they are contaminants of emerging concern as a result of increasing industrialization and global trade of used products and wastes.publishedVersio

Seasonal rainfall affects occurrence of organohalogen contaminants in tropical marine fishes and prawns from Zanzibar, Tanzania

Seasonal differences in precipitation may affect contaminant dynamics in tropical coastal regions due to terrestrial runoff of contaminants to the marine environment after the rainy seasons. To assess the effect of seasonal rainfall on occurrence of organohalogen contaminants in a coastal ecosystem, marine fishes and prawns were collected off the coast of Zanzibar, Tanzania in January and August 2018, representing pre- and post-rainy season, respectively. Samples were analyzed for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) and emerging BFRs, as well as the dietary descriptors stable isotopes of carbon (δ13C) and nitrogen (δ15N). Across all species and seasons, mean contaminant concentrations ranged from below limit of detection (LOD) to 129 ng/g lipid weight (lw) ΣPCBs; 5.6–336 ng/g lw ΣOCPs; and < LOD –22.1 ng/g lw ΣPBDEs. Most of the emerging BFRs were below LOD. Contaminant concentrations generally increased with higher pelagic carbon signal (δ13C) and higher relative trophic position (δ15N). The ratio of DDE/ΣDDTs in fishes and prawns was lower in August than in January, suggesting runoff of non-degraded DDT into the marine system during or after the seasonal rainfall. Contaminant patterns of OCPs and PCBs, and concentrations of BFRs, differed between seasons in all species. A higher relative concentration-increase in lower halogenated, more mobile PCB and PBDE congeners, compared to higher halogenated congeners with lower mobility, between January and August aligns with a signal and effect of terrestrial runoff following the rainy season