A resilience lens to explore seaweed farmers’ responses to the impacts of climate change in Tanzania

Seaweed-based mariculture is an important source of livelihoods for impoverished coastal communities in Tanzania. However, the impacts of climate change across East Africa are putting a strain on the growth of the seaweed industry. Smallholder farmers are already mobilizing strategies to cope with challenges such as disease outbreaks, but they are struggling to maintain seaweed production and derive sufficient income. A better understanding of the challenges they face and the factors inhibiting their ability to build resilience is needed to inform policies and development programmes to achieve the Sustainable Development Goals, particularly Goal 13 on Climate action and Goal 14 on Life Below Water. The global demand for seaweed is expanding rapidly. Strengthening the adaptability of seaweed production to climate change is important for farmers to rely on it as a source of livelihoods on which they can build their own resilience to climate change. Drawing on qualitative data from key informant interviews in four Tanzanian seaweed-producing areas, this paper assesses the long-term resilience capacities of seaweed farmers to respond to one of the main hazards: diseases affecting seaweed crops. While several strategies help farmers maintain their income, most of them only support resilience in the short term. The increasing pressure on marine resources and the lack of regulations for supporting an equitable and sustainable seaweed-based mariculture sector do not bode well for farmers’ long-term adaptation to climate change and environmental degradation. Seaweed farming remains a crucial source of livelihoods for poor coastal communities in Tanzania, but it does not currently lead to positive transformative changes in their socio-economic conditions. Policies aiming to support sustainable aquaculture, particularly in tropical ecosystems that are highly vulnerable to climate change, must address the existing social, economic and knowledge inequities that prevent poor communities from building their resilience

Ice-Ice disease: An environmentally and microbiologically driven syndrome in tropical seaweed aquaculture

Seaweeds account for nearly 30% of global aquaculture production by volume, and their cultivation provides important opportunities for employment and wealth generation, particularly in rural coastal communities. Eucheumatoids (Kappaphycus and Eucheuma spp.) are tropical red algae commercially cultivated as raw material for production of carrageenans, particularly in South-East Asia and the Western Indian Ocean region. Diseases and pests are major limiting factors in eucheumatoid production, particularly a condition known as ‘ice-ice’ disease (IID). IID is characterized by bleaching of the thallus followed by the disintegration of affected tissues, leading to a loss of biomass and reduced carrageenan yield. IID has been associated with unfavourable changes in environmental conditions, particularly an increase in sea water temperature and a decrease in salinity, and infection by opportunistic or pathogenic bacteria. However, given that no single or combined causal agents have been definitely identified, IID may be considered a complex pathobiotic syndrome in which multiple factors contribute to the development of disease signs. Here, we review current knowledge of the abiotic and biotic factors associated with the development of IID, and the strategies employed to mitigate economic losses resulting from disease outbreaks. We discuss syndromic diseases in other marine holobionts, particularly other red algae and corals, in relation to their similarity to IID, and suggest the application of comprehensive and complementary methodologies, including high-throughput sequencing and high-quality microscopy, for enhancing our understanding of the pathological and microbiological processes associated with IID signs.All authors were supported by funding from UKRI for the GlobalSeaweedSTAR project (BB/P027806/1)

Distribution of the tropical seaweed crops Eucheuma spp. and Kappaphycus spp. inside and outside of their native range

Oral presentation presented at the 12th International Phycological Congress Puerto Montt, Chile 22–26 March 2021.Seaweed aquaculture is a fast-growing industry worldwide and has the potential to change the seascape of coastal regions, including the movement of species outside their native range. Two of the crops with the highest global production are the tropical red algal eucheumatoids, Kappaphycus spp. and Eucheuma denticulatum. Cultivation of these species has become an important source of income for coastal communities especially in many areas in South East Asia and the Western Indian Ocean. Low initial investment and a simple vegetative propagation through cutting fostered a rapid expansion of eucheumatoid cultivation and its introduction in diverse tropical and subtropical countries around the world. Despite the economic importance of eucheumatoid cultivation, its relevance for many coastal communities and its global expansion knowledge on genetic variation between and within cultivars of Eucheuma and Kappaphycus and their wild counterparts is yet limited. Through an international consortium we designed a global sampling campaign of cultivated and non-cultivated eucheumatoids from seaweed farms and natural habitats with focus on South East Asia (the Philippines, Malaysia and Indonesia) and the Western Indian Ocean (Tanzania and Madagascar), as well as specimens from non-native areas including islands in the Pacific (Hawaii, Kiribati, Fiji and Solomon Islands). In this talk, we will give an update of this ongoing project and outline initial results from a new initiative to determine diversity within cultivated eucheumatoid specimens from Tanzania. Our project aims at providing novel knowledge on the genetic resources of eucheumatoids in support of a sustainable seaweed industry

Ensuring the sustainable future of the rapidly expanding global seaweed aquaculture industry – a vision:United Nations University Institute on Comparative Regional Integration Studies and Scottish Association for Marine Science Policy Brief

This policy brief highlights key challenges that must be addressed for the long-term sustainability of the global seaweed industry, ensuring its role in providing nature-based solutions within the sustainable ocean economy agenda and in contributing to the UN Decade of Ocean Science for Sustainable Development (2021 – 2030). Seaweed production has grown rapidly over the past 50 years. It currently accounts for over 50 % of total global marine production, equating to ~35 million tonnes. In 2019, the industry’s total value was estimated at USD 14.7 billion. The seaweed value chain supports the livelihoods of approximately 6 million small-scale farmers and processors, both men and women, many of whom live in coastal communities in low- and middle-income countries. The aquaculture sector is increasingly interested in seaweed because of its potential for greater use in food, food supplements, animal feed, fertiliser and biostimulants, and in alternatives to fossil fuels and their derived products, such as plastics. Its cultivation can help restore degraded environments, increase ocean biodiversity and mitigate the effects of climate change and coastal acidification by capturing carbon and other nutrients. In low-, middle- and high-income countries, the seaweed industry has a wide-ranging potential to address the UN Sustainable Development Goals (SDGs) in particular, SDG 14 (life below water), SDG13 (climate action), SDG6 (decent work and economic growth) and SDG5 (gender equality). The global seaweed industry, however, faces significant challenges. For future sustainability, improvements are urgently needed in biosecurity and traceability, pest and disease identification and outbreak reporting, risk analysis to prevent transboundary spread, the establishment of high quality, disease-free seed-banks and nurseries and the conservation of genetic diversity in wild stocks. These improvements require technological innovation, capacity building and effective gender-responsive and co-ordinated policies, incentives and regulations. They will need to enhance occupational safety, whilst increasing the industry’s resilience to the impacts of climate change and production hazards, such as pest and disease outbreaks. To align with the SDGs, particular attentions will need to be paid to small scale farmers and processors to ensure that the globalisation of seaweed aquaculture supports the development of sustainable, resilient and inclusive livelihoods