With a world population estimated at 10 billion people by 2050, the challenge to secure healthy and safe food is evident. Seaweed is a potential answer to this challenge. Expanding the use of seaweed in food systems requires an emphasis on safe practices to avoid adverse human health effects after consumption and irreversible damage to marine ecosystems. This study aims to evaluate relevant food safety and environmental safety hazards, monitoring measures, and mitigation strategies in the seaweed sector. For this study, a literature review, survey (n = 36), and interviews (n = 12) were conducted to identify hazards. The review and interviews aimed at pinpointing monitoring measures and mitigation strategies applied, while the survey revealed data gaps and further actions needed for the sector. Relevant food safety hazards include (inorganic) arsenic, iodine, and heavy metals, among others, such as pathogenic bacteria, while environmental hazards include environmental pathogens and parasites introduced into the ecosystem by domesticated seaweed, among others. Measures applied aim at preventing or mitigating hazards through good hygienic or manufacturing practices, food safety procedures or protocols, or pre-site farm selection. Although the future needs of the seaweed sector vary, for some, harmonized advice and protocols that align with a changing food system and hazard knowledge development as well as information on the benefits of seaweed and regulating climate and water quality may help.

Summary: The EU has proposed a voluntary framework for certification of carbon removals which remains vague on blue carbon and in particular, carbon removal through use of seaweeds. Seaweed is considered an emerging blue carbon option. Various studies have confirmed the potential of seaweed to contribute to long‐term carbon removal, storing it away from the atmosphere for 100 years and more. Certification of seaweed carbon sequestration is promoted, even in other EU communications. This article reviews early experiences with certification of carbon and nutrient removal by aquaculture using the QU.A.L.ITY criteria proposed by the EU. Examples reviewed include the Seaweed Company, Venice Bay, Yokohama Bayside marine, and Chesapeake Bay in the USA. After reviewing these examples, we call on the European Commission to move forward towards certification of blue carbon. If the EU is to lead global climate mitigation efforts, including carbon removal, it should take seaweed blue carbon seriously and include it in its voluntary framework. To enhance the awareness of the relevance and the acceptance of the carbon credits from seaweed, a methodology has to be developed that, building on experiences gained, deals with inherent uncertainties.

Global concerns about climate change were once again expressed at the COP27 in Sharm El‐Sheikh. Seaweed is frequently presented as a solution for climate mitigation. For a proper appraisal of its contribution to mitigating climate change, it is necessary to distinguish between, and critically scrutinize, the various pathways seaweed‐based climate mitigations can take. This article identifies four different climate mitigation pathways and critically reflects on each. First, carbon sequestration, occurring when grown seaweed is left in the seas or, second, purposefully sunk. Third, carbon emission reduction, resulting when seaweed‐based products replace products with a higher carbon footprint, either fossil based products or other organic material. Fourth, carbon emission avoidance, taking place when seaweed products are used to avoid greenhouse gas emissions in other production processes. Each of these pathways requires specific methods to quantify their magnitude and comes with critical questions to ask. The sequestration pathway requires monitoring of net carbon production and the amount of carbon that is eventually exported to the deep sea. Pathways 3 and 4 require Life Cycle Assessment and/or Carbon Footprint with system boundaries set to include the production system itself and installation thereof. We propose an unequivocal categorization in a belief that confusion on the benefits of seaweed will eventually impede development of seaweed‐based solutions.This article is categorized under: The Carbon Economy and Climate Mitigation > Benefits of Mitigation

Seaweed is increasingly discussed as a sustainable biomass source of the future, with applications in agricultural, food and cosmetics products and other areas of the biobased economy. The potential positive environmental impacts of seaweed cultivation have triggered public and private sector interest. This paper outlines the evidence for potential environmental benefits arising from seaweed cultivation focusing on climate change mitigation, biodiversity loss mitigation and improved water quality. Our findings are based on a descriptive literature review, coupled with insights and additional literature established during an expert review meeting. We found that seaweed cultivation can help to mitigate climate change and biodiversity loss and have beneficial impacts on water quality, but management practices may be key to maximizing these benefits and preventing negative environmental impacts. In particular, co-cultivating seaweed in integrated multi-trophic systems can enhance benefits. Other management practices expected to enhance environmental benefits of seaweed cultivation were identified, aligned to recently defined Principles of Restorative Aquaculture, including siting and structure used. Evidence of environmental impacts is often site-specific with considerable variability and uncertainty in the reported environmental benefits, due to the complexity of marine ecosystems and variability in cultivation and harvest practices. Systematic, long-term monitoring efforts are scarce, and more quantitative evidence is needed to support public and private sector decision-making for upscaling seaweed production in support of both bioeconomy and environmental restoration objectives. However, the management principles and practices identified in this paper can be used as interim guidance for decision-making.