Contributors: Brodie (NHM; Lead), Stentiford (Cefas), Gachon (SAMS), post-doctoral researchers from Cefas, NHM and SAMS, and developing country partner leaders and early career researchers from the Philippines, Tanzania and Malaysia.

Q1: What are the key diagnostic tools yield-limiting seaweed diseases and pests (e.g., epiphytes and endophytes) associated with cultivation sites and the wider environment?

The commercial farming of seaweeds has always been beset with pathogen and pest problems, leading to scarcity, or at times total lack of availability of good quality propagules for re-planting purposes. This scarcity has led to the large-scale movement of seaweeds between regions to re-populate growing areas, thus spreading diseases and pests. For example, ‘ice-ice’ malaise and macro-epiphytes are predominant in Kappaphycus farms and infestations can significantly adversely affect the crop quality and yield. Ice-ice and epiphytism, however, are complex syndromes caused by a variety of poorly known bacteria and algae, respectively. Promoting the use of molecular detection techniques and GIS software, will allow us to diagnose key yield-limiting seaweed diseases and pests and indicate their prevalence/ distribution with unprecedented efficacy and reliability.

Contributors: Cottier-Cook (SAMS, Lead), Stentiford (Cefas), Shaxson (ODI), post-doctoral researchers from Cefas, SAMS and ODI, and developing country partner leaders and early career researchers from the Philippines, Tanzania and Malaysia.

Q2. How can existing biosecurity and legislative frameworks be improved to safeguard the seaweed industry in DAC-list countries from diseases and pests?

The introduction and subsequent spread of disease-prone non-indigenous seaweeds outside their native range is a major factor in halting the expansion of the seaweed industry and in damaging the wider marine environment. Biosecurity is a means of controlling the introduction and spread of crops and pests, ensuring the sustainability of the industry, safeguarding the environment and mitigating any adverse impacts that may result. The rapid expansion of the seaweed industry over the last four decades, however, has preceded the establishment of appropriate biosecurity and legislative structures required to manage the industry sustainably and in a manner consistent with other aquaculture sectors, particularly in our DPs, thus allowing the unchecked spread of pests and diseases (see WP1). In addition, seaweed, being neither plant nor animal, currently falls between the terrestrial and aquatic remits of agencies normally responsible for national biosecurity. Fortunately, lessons can be learnt from where strict biosecurity measures have been introduced to protect farmed stock and wildlife at farm, zone, national, regional and global levels in terrestrial and aquatic animal systems following major disease and pest outbreaks.

Contributors: Gachon (SAMS, lead), Brodie (NHM), post-doctoral researchers from SAMS & NHM, and developing country partner leaders and early career researchers from the Philippines, Malaysia and Tanzania.

Q3: How do commercial seaweed strains respond to biotic and abiotic stresses (short and long term) and can they be improved to offer greater enhanced resilience to disease and pests and growth performance?

Similar to other seaweed crops globally, the early success of open water Kappahycus (sensu lato) cultivation in the developing countries has mostly relied on the vegetative propagation, via cuttings, of a relatively small genetic stock. Little innovation has been applied and after 40 years, problems such as loss of strain vigour, decrease in biomass, susceptibility to disease outbreaks and epiphyte infestations, in part worsened by climate change, have led to decreased growth performance and carrageenan quality (yield, gel strength and molecular weight). To underpin crop improvement, it is necessary to intensify early efforts towards the characterisation of the seaweed bioresource. In parallel, SAMS, notably via GlobalSeaweed, has been pioneering new non-invasive methods for cost-effective algal phenotyping, strain selection, and crop improvement. This WP initiates a holistic strategy towards sustainable crop improvement, starting from the initial identification of existing genetic resources, to the establishment of seedbanks to supply farmers with healthy and high performing stock, and the test of new strains for resistance to abiotic and biotic stresses.

Contributors: Shaxson (ODI, lead), Stentiford (Cefas), Cottier-Cook (SAMS), post-doctoral researchers from ODI, and developing country partner leaders and early career researchers from the Philippines, Malaysia and Tanzania.

Q4: How do different approaches to risk management, gender issues and national and international policies contribute to poverty-reducing economic growth and resilience in seaweed producing DAC-list countries?

Seaweed farming has the potential to contribute significantly to economic growth in coastal communities, but there have been few detailed studies. In Tanzania, seaweed farming has increased incomes, but changes in the world market for seaweed products, and the farming environment, have been disruptive. The productivity of species such as Kappaphycus alvarezii has declined, resulting in the adoption of other species such as Euchema denticulatum, but at reduced prices. As productivity and profitability have declined, the gender balance of the industry has also changed. In some areas, men have left the industry in search of more consistent incomes, though women have seen seaweed farming as an opportunity to earn a good-living, even if only working part time. As the seaweed industry grows and diversifies into new species and geographical areas this will change the socio-economic landscape of the coastal communities where it is farmed, their resilience to climate-induced and economic shocks and the potential for inclusive economic growth. Developing national and international policies (see WP2) and legislation around farm management practices and biosecurity for seaweed cultivation (and other organisms that may carry seaweed or seaweed diseases) must take these potential changes into account.