Seaweed Farming in Tanzania: A Study of Working Practices and Geospatial Analysis of Occupational Hazards and Adverse Health Outcomes.

OBJECTIVE: Work in seafood harvesting and processing has been associated with a range of occupational hazards and associated health problems. However, limited information exists regarding the occupational health risks among workers engaged in seaweed handling. METHODS: A cross-sectional study was conducted to map seaweed co-operatives (n = 45), assess working practices, and identify common work-related symptoms, occupational hazards, and interventions in seaweed farming sites (n = 24), across three regions of Zanzibar, Tanzania. RESULTS: Seaweed farming in Zanzibar primarily involves the cultivation of Eucheuma Spinosum, with the majority of workers being women. Common work-related symptoms identified include musculoskeletal symptoms, mainly affecting the wrist (87%), back (84%) and lower limbs (73%). Furthermore, a significant proportion of workers were reported to have skin problems (80%) as well as heat and asthma-related symptoms (51%). Walk-through hazard evaluations of work sites identified a range of occupational hazards, with ergonomic (58-68%), biological (50-63%) and chemical (55-65%) hazards obtaining higher scores across the three regions. Geospatial analysis revealed regional variations in occupational hazards and work-related symptom prevalence, with Unguja South having a statistically significant (p < .05) higher mean prevalence of skin symptoms (95%) and Mjini Magharibi region reporting a higher prevalence of lower limb pain (100%), back pain (100%), and heat-related symptoms (90%). Despite the high hazard scores, interventions were generally lacking across all regions. CONCLUSION: Occupational health hazards and adverse health outcomes vary across seaweed farming and processing regions. Tailored interventions will be key to improving workplace health and safety of workers engaged in this sector.

Ice-Ice Disease Prevalence and Intensity in Eucheumatoid Seaweed Farms: Seasonal Variability and Relationship with the Physicochemical and Meteorological Parameters.

Since its initial report in the Philippines in 1981, ice-ice disease (IID) remains a substantial threat to the sustainability of eucheumatoid seaweed production. However, comprehensive investigations into the prevalence, intensity, and potential relationships with physicochemical and meteorological parameters are limited, particularly in open-sea farms. This is the first study to conduct a 12-month monitoring of IID prevalence and intensity in eucheumatoid seaweed farms in Tawi-Tawi, Philippines. The research aimed to elucidate seasonal variations and potential associations with physicochemical and meteorological parameters. The findings revealed significant seasonal variations in IID prevalence, with a higher incidence observed during the dry season compared to the wet season. Additionally, deep-water farms exhibited significantly higher prevalence and ice-ice spot numbers per bundle compared to shallow-water farms. Furthermore, Kappaphycus striatus displayed a significantly greater ice-ice spot length per bundle compared to K. alvarezii. Notably, no interaction effects were observed among season, species, and depth. Interestingly, while no correlations were found between ice-ice disease and most measured physicochemical and meteorological parameters (temperature, salinity, pH, water current velocity, wind speed) or nutrient concentrations (phosphate, nitrate, nitrite), an inverse correlation (p < 0.05) emerged between ammonium levels and IID intensity parameters (number and length of ice-ice spot per bundle). Moreover, a positive correlation was observed between monthly rainfall and IID intensity. These findings offer valuable insights into the dynamics of IID in open-sea eucheumatoid seaweed (Kappaphycus) farming, highlighting the influence of seasonality, depth, and species susceptibility, as well as the relationship between IID severity and ammonium levels and rainfall.

A sustainable blue economy may not be possible in Tanzania without cutting emissions.

Balancing blue growth with the conservation of wild species and habitats is a key challenge for global ocean management. This is exacerbated in Global South nations, such as Tanzania, where climate-driven ocean change requires delicate marine spatial planning (MSP) trade-offs to ensure climate resilience of marine resources relied upon by coastal communities. Here, we identified challenges and opportunities that climate change presents to the near-term spatial management of Tanzania's artisanal fishing sector, marine protected areas and seaweed farming. Specifically, spatial meta-analysis of climate modelling for the region was carried out to estimate the natural distribution of climate resilience in the marine resources that support these socially important sectors. We estimated changes within the next 20 and 40 years, using modelling projections forced under global emissions trajectories, as well as a wealth of GIS and habitat suitability data derived from globally distributed programmes. Multi-decadal analyses indicated that long-term climate change trends and extreme weather present important challenges to the activity of these sectors, locally and regionally. Only in few instances did we identify areas exhibiting climate resilience and opportunities for sectoral expansion. Including these climate change refugia and bright spots in effective ocean management strategies may serve as nature-based solutions: promoting adaptive capacity in some of Tanzania's most vulnerable economic sectors; creating wage-gaining opportunities that promote gender parity; and delivering some economic benefits of a thriving ocean where possible. Without curbs in global emissions, however, a bleak future may emerge for globally valuable biodiversity hosted in Tanzania, and for its coastal communities, despite the expansion of protected areas or curbs in other pressures. Growing a sustainable ocean economy in this part of the Global South remains a substantial challenge without global decarbonization.

Dynamic livelihoods, gender and poverty in marine protected areas: Case study from Zanzibar, Tanzania.

Livelihood initiatives are common within marine protected areas (MPAs) aiming for poverty alleviation or higher income opportunities. However, results can be mixed in reality, as well as change over time. Furthermore, who benefits is a key consideration, as results can vary based on inequalities, including gender. Here, the monetary outcomes of different livelihood strategies were investigated across three MPA regions in Zanzibar, Tanzania. Using a quantitative approach, the results show that livelihoods have shifted in a six-year period, with livelihood strategies differing in poverty incidence and income. Livelihood initiatives, namely seaweed farming and tourism, did not provide significantly higher monetary returns compared to long-standing livelihoods, such as fisheries. Seaweed farming showed income stability but a high poverty incidence predominantly within women-headed households. During the study period, men primarily remained in fisheries, whilst women shifted to small-scale businesses and fisheries, largely exiting seaweed farming. This underscores a need for adaptive, gender sensitive management within fast changing coastal contexts.

Spatial and seasonal distribution of cyanobacteria Moorea species in coastal waters of Tanzania.

This study aimed at identifying the presence of harmful cyanobacteria, detecting potential harmful algae toxins and their distribution in three seasons: December to February (hot dry season), March to May (rainy season), and June to November (cool dry season) of 2016. The samples were collected in five study sites in Tanzania: Tumbe, Chwaka, Paje, Bweleo in Zanzibar islands and Songosongo Island, mainland Tanzania, where skin irritation problems were observed in seaweed workers in an earlier study. The cyanobacteria from the Moorea genus were microscopically detected in the seawater, with highest concentrations in the months with the highest seawater temperature or hot dry season, than in the other two seasons. The concentration of Moorea species was significantly higher in Songosongo, Tanzania mainland than in Zanzibar Islands in all three seasons, corresponding to the higher level of nutrients of nutrients (PO43-, NO3- and NH4+) in the prior season. However, the concentrations were considered relatively low and thus not collected during an ongoing algal bloom. This is one of the first studies that detect Moorea sp. in Tanzanian seawater, and complementary studies including genome sequencing to characterize the species are warranted.

Does experimental seaweed cultivation affect benthic communities and shorebirds? Applications for extensive aquaculture.

Extensive seaweed aquaculture is a growing industry expected to expand globally due to its relatively low impact and benefits in the form of ecosystem services. However, seaweeds are ecosystem engineers that may alter coastal environments by creating complex habitats on previously bare mudflats. These changes may scale up to top-consumers, particularly migratory shorebirds, species of conservation concern that regulate trophic webs at these habitats. Understanding how habitats are transformed and how this affects different species is critical to direct ecological applications for commercial seaweed management. We experimentally assessed through a Before-After Control-Impact design the potential changes exerted by Gracilaria chilensis farming on bare mudflats on the abundance, biomass, and assemblage structure of benthic macroinvertebrates, and their scaled-up effects on shorebirds' habitat use and prey consumption. As predicted, experimental cultivation of G. chilensis significantly affects different components of biodiversity that scale-up from lower to upper trophic levels. The total biomass of benthic macroinvertebrates increased with seaweed cultivation and remained high for at least 2 months after harvest, boosted by an increase in the median size of polychaetes, particularly Nereids. Tactile-foraging shorebirds tracked these changes at the patch level increasing their abundance and spending more time foraging at seaweed cultivated plots. These results suggest that seaweed farming has the potential to impact shorebird populations by favoring tactile-foraging species which could lead to a competitive disadvantage to species that rely on visual cues. Therefore, the establishment of new seaweed farms in bare mudflats at key sites for shorebirds must be planned warranting habitat heterogeneity (i.e., cultivated and non-cultivated areas) at the landscape level and based on a previous experimental approach to account for local characteristics. Fostering properly designed extensive seaweed farming over other aquaculture industries with greater negative environmental impacts would provide benefits for human well-being and for ecosystem functions.

Occupational Health and Safety in Tanzanian Aquaculture - Emerging Issues.

OBJECTIVES: The Tanzanian aquaculture industry represents great potential for food production and jobs; however, the potential occupational hazards and health risks associated with the sector have not been assessed. The aim of this study was to conduct a scoping analysis of the status of occupational health and safety based on current Tanzanian aquaculture activities, specifically in the fish farming and seaweed farming sectors. METHODS: Relevant information for the scoping analysis was obtained through aquaculture site visits and worker observation, interviews with key aquaculture stakeholders, and a review of literature relevant to the Tanzanian aquaculture sector published in scientific communications as well as grey literature. RESULTS: The study shows that the Tanzanian aquaculture industry is still in nascent stages, especially in relation to occupational health and safety despite some well-established isolated operations in the country. The industry is dominated by small-scale fish and seaweed farmers, the majority of whom work in the informal and semi-formal sectors. Tanzanian aquaculture workers are exposed to a number of occupational hazards and their associated health effects have been poorly characterized. Substantial gender disparities exist within the sector, which together with climate change, impact worker health and safety. CONCLUSION: Future research should focus on characterizing occupational exposures and documenting the associated health effects in Tanzanian aquaculture workers. Standardized methods should be used for this purpose to take into account gender disparities as well as the impact of climate change on occupational health and safety of these vulnerable workers.

A Retrospective Review of Global Commercial Seaweed Production-Current Challenges, Biosecurity and Mitigation Measures and Prospects.

Commercial seaweed cultivation has undergone drastic changes to keep up with the increasing demand in terms of the quantity and quality of the algal biomass needed to meet the requirements of constant innovation in industrial applications. Diseases caused by both biotic and abiotic factors have been identified as contributing to the economic loss of precious biomass. Biosecurity risk will eventually affect seaweed production as a whole and could cripple the seaweed industry. The current review sheds light on the biosecurity measures that address issues in the seaweed industry pushing towards increasing the quantity and quality of algal biomass, research on algal diseases, and tackling existing challenges as well as discussions on future directions of seaweed research. The review is presented to provide a clear understanding of the latest biosecurity developments from several segments in the seaweed research, especially from upstream cultivation encompassing the farming stages from seeding, harvesting, drying, and packing, which may lead to better management of this precious natural resource, conserving ecological balance while thriving on the economic momentum that seaweed can potentially provide in the future. Recommended breeding strategies and seedling stock selection are discussed that aim to address the importance of sustainable seaweed farming and facilitate informed decision-making. Sustainable seaweed cultivation also holds the key to reducing our carbon footprint, thereby fighting the existential crisis of climate change plaguing our generation.

Assessing the potential for sea-based macroalgae cultivation and its application for nutrient removal in the Baltic Sea.

Marine eutrophication is a pervasive and growing threat to global sustainability. Macroalgal cultivation is a promising circular economy solution to achieve nutrient reduction and food security. However, the location of production hotspots is not well known. In this paper the production potential of macroalgae of high commercial value was predicted across the Baltic Sea region. In addition, the nutrient limitation within and adjacent to macroalgal farms was investigated to suggest optimal site-specific configuration of farms. The production potential of Saccharina latissima was largely driven by salinity and the highest production yields are expected in the westernmost Baltic Sea areas where salinity is >23. The direct and interactive effects of light availability, temperature, salinity and nutrient concentrations regulated the predicted changes in the production of Ulva intestinalis and Fucus vesiculosus. The western and southern Baltic Sea exhibited the highest farming potential for these species, with promising areas also in the eastern Baltic Sea. Macroalgal farming did not induce significant nutrient limitation. The expected spatial propagation of nutrient limitation caused by macroalgal farming was less than 100-250 m. Higher propagation distances were found in areas of low nutrient and low water exchange (e.g. offshore areas in the Baltic Proper) and smaller distances in areas of high nutrient and high water exchange (e.g. western Baltic Sea and Gulf of Riga). The generated maps provide the most sought-after input to support blue growth initiatives that foster the sustainable development of macroalgal cultivation and reduction of in situ nutrient loads in the Baltic Sea.

Carbon Sequestration in the Form of Recalcitrant Dissolved Organic Carbon in a Seaweed (Kelp) Farming Environment.

Under climate change scenarios, the contribution of macroalgae to carbon sequestration has attracted wide attention. As primary producers, macroalgae can release substantial amounts of dissolved organic carbon (DOC) in seawater. However, little is known about the molecular composition and chemical properties of DOC derived from macroalgae and which of them are recalcitrant DOC (RDOC) that can be sequestered for a long time in the ocean. In the most intensive seaweed (kelp) farming area (Sanggou Bay) in China, we found that kelp mariculture not only significantly increased DOC concentration, but also introduced a variety of new DOC molecular species, many of which were sulfur-containing molecules. A long-term DOC degradation experiment revealed that those DOC with strong resistance to microbial degradation, i.e., RDOC, account for approximately 58% of the DOC extracted from kelp mariculture area. About 85% (3587 out of 4224 with different chemical features) of the RDOC molecular species were steadily present throughout the long-term degradation process. 15% (637 out of 4224 with different chemical features) of the RDOC molecular species were likely newly generated by microorganisms after metabolizing macroalgae-derived labile DOC. All these stable RDOC should be included in the blue carbon budgets of seaweed.

Influence of phosphorus on the uptake and biotransformation of arsenic in Porphyra haitanensis at environmental relevant concentrations.

Edible seaweeds are rich in essential vitamins and minerals, which made them a popular food worldwide. Porphyra haitanensis is one of the most commonly consumed seaweeds with the known ability to accumulate a high level of total arsenic (As). A large number of articles have shown arsenic and phosphorus (P) interactions in microalgae due to the plant's inability to differentiate arsenate from phosphate. However, very limited information is available for edible seaweed at environmentally relevant concentrations. In this study, P. haitanensis was treated with arsenic as AsV (As1: 0.06 µM, As2: 0.4 µM, As3: 1.2 µM) and phosphorous (P1: 3.2 µM, P2: 13 µM) in a filtered seawater matrix under laboratory condition for six days. A better growth rate was found in seaweeds grown in P2 treatments. Moreover, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content measurements revealed that a higher P concentration prevent seaweeds from lipid peroxidation and oxidative stress. Transcriptome studies indicated the As replacement to P has the ability to target seaweed cell membrane composition, transmembrane transport, DNA and ATP binding. The inorganic As (iAs) had a concentration of 0.54 to 4.45 mg/kg in P. haitanensis on Day 6 with As1, As2, and As3 treatments under low P regime (P1), which exceeds the limits of iAs concentration (0.1-0.5 mg/kg) in National Food Safety Standard-Limits of Pollutants in Food (GB 2762-2017). High P regime (P2) not only reduced the total As but also iAs effectively, even in the highest As treatment (As3), the iAs concentration was less than 0.5 mg/kg on Day 6. These findings provide a good insight for seafood safety guarantees and are important for the management of coastal artificial seaweed farming.

The Impacts of Urbanization and Dietary Knowledge on Seaweed Consumption in China.

Edible seaweed, a nutrient-rich and sustainable food, has a long dietary history in China. To get a better understanding of the seaweed consumption of consumers in China, this study investigates the quantity and trend of seaweed consumption of Chinese residents and employs a Tobit model to examine the effects of urbanization and dietary knowledge on seaweed consumption among residents. The results show an increasing trend of household seaweed consumption in China, including both seaweeds consumed at home (SAH) and seaweeds consumed away from home (SAFH). Households in urban areas consumed more seaweeds on average than those in rural areas. Urbanization promotes total household seaweed consumption, including SAH and SAFH, whilst dietary knowledge has a significantly positive impact on total household seaweed consumption and SAH. The findings supplement empirical evidence on the seaweed consumption behavior of Chinese residents and have important policy implications for further promoting Chinese seaweeds consumption in the context of urbanization and increasing dietary knowledge.

Knowledge gaps and management recommendations for future paths of sustainable seaweed farming in the Western Indian Ocean.

Farming of eucheumatoid seaweeds is a widespread, promising activity and an important livelihood option in many tropical coastal areas as for example in East Africa, Western Indian Ocean (WIO). Compared to other types of aquaculture, seaweed farming has generally low impact on the environment. Nonetheless, there are potential direct or indirect negative effects of seaweed farming, such as introduction of alien species and changes in local environmental conditions. Although farming has been practiced in this region during several decades, the knowledge concerning the actual environmental impacts from faming non-native eucheumatoid haplotypes and consequently how to manage farming activities to mitigate those is highly limited. In this review, we provide a summary of the current scientific knowledge of potential direct and indirect negative environmental effects linked to eucheumatoid seaweed farming such as alterations of benthic macrophyte habitats and loss of native biodiversity. Furthermore, we highlight knowledge gaps that are of importance to address in the near future, e.g., large-scale ecosystem effects and farms as potential vectors of pathogens. We also provide a number of feasible management recommendations to be implemented for a continued development of environmentally sustainable seaweed farming practices in the WIO region, which includes spatial planning of farms to avoid sensitive areas and farming of native haplotypes of eucheumatoids instead of introduced specimens.

Cultivation of the red algae Kappaphycus alvarezii in Brazil and its pharmacological potential

Kappaphycus alvarezii (Rhodophyta, Gigartinales) is a red algae widely cultivated as the main source of raw material for the carrageenan industry. This hydrocolloid is normally used in the food industry as a gelling and stabilizing agent. The facility of its commercial farming based on vegetative propagation promoted the success of the aquaculture of this macroalgae that consequently stimulated studies focusing on new potential uses of this resource. This work presents a brief review of the studies related to K. alvarezii cultivation in southern and southeastern Brazil, the latest discoveries in the world concerning pharmacological studies with this species and the advantages of the use of carrageenan as a source of dietary fiber, cholesterol reducer, and antioxidant, anti-viral and anti-cancer compounds, as well as the effects in hemagglutination activity.