• Target 2.1: By 2030, end hunger and ensure access by all people, in particular the poor and people in vulnerable situations, including infants, to safe, nutritious and sufficient food all year round;
• Target 2.4: By 2030, ensure sustainable food production systems and implement resilient agricultural practices that increase productivity and production, that help maintain ecosystems, that strengthen capacity for adaptation to climate change, extreme weather, drought, flooding and other disasters and that progressively improve land and soil quality (UN, 2015).
However, the results obtained also show some risks associated with the consumption of seaweeds. The notorious presence of the element Iodine, namely in the Undaria species, means that DRVs are exceeded in most scenarios. In addition to the risks associated with the presence of Iodine, it is also worth noting the risks associated with the presence of some identified contaminants, such as Inorganic Arsenic and Lead. For these two elements, it was possible to identify the existence of risk in both Porphyra and Undaria species, in the three established scenarios. This exposure to the elements mentioned, together with the lack of knowledge in the literature regarding the potential of seaweeds in human health, justifies the apprehension by the consumers of this food. Therefore, greater understanding around this subject would help the perception of people and entities regarding the potential of this food, and may also help to maximize the impact of seaweeds on this SDG.
It is also easy to associate the seaweed industry with many more SDGs, as we have seen.
However, there are several factors that prevent or minimize the success rate in achieving more goals, namely due to some cons presented in Subchapter 2.3 of the present Thesis. For example, in the three forms of macroalgae culture, as well as in wild harvesting, it is possible to notice the use of ropes and nets during the activity. These ropes and nets were previously identified as a problem associated with some seaweed production techniques, in the sense that they belong to the group of materials usually abandoned during the activity. One of the major environmental issues is the presence of waste in the ocean, specifically plastics. The problem is that when plastic is abandoned, it remains in the sea for many years, endangering the lives of many marine life species, including seals, dolphins, and turtles (Lusa, 2019). According to a Greenpeace report (Thomas et al., 2019), more than 85% of the
plastic found on the seafloor in some areas of the oceans is composed of fishing materials such as nets, lines, and traps. These materials are similar to those used for aquaculture fish production. Some of the plastics most used for this activity are polymers such as polypropylene (PP) and polyethylene (PE), for ropes, and polyamide (PA), polyethylene terephthalate (PET), and PP for nets (FAO, 2017). Plastics have the advantage of being low cost, and they also have the ability to be controlled in terms of their resistance, permeability and colour, among other characteristics (Chamas et al., 2020). However, most plastics produced today are made from products derived from fossil oil, natural gas, and coal. As a result, it is critical to address this issue, not only to ensure that activities associated with seaweed production do not contribute to this percentage but also to serve as an example for the other industries. To overcome this problem, a good way of acting is the replacement of the material used in synthetic ropes with others that are more eco-friendly and even capable of resisting the sea conditions such as strong currents and salinity, and the sun exposure.
Bioplastics, for example, appear to be a viable solution to the environmental issues caused by synthetic plastic (Atiwesh et al., 2021). These bioplastics can be biodegradable, oxo-biodegradable, or bio-based, and they are more easily degradable than the more common ones (FAO, 2017). An article of Current Science (by Herlekar, 2015) shows a curious example of a biodegradable material made from macroalgae, that intends to replace the synthetic material used in strings. According with the same article, this material is tolerant to the salinity of the sea, making it very interesting from the point of view of seaweed production in aquaculture. Through the adoption of alternative plastic materials, namely biodegradable plastics, it is possible to contribute to a more sustainable seaweed production, minimizing this global problem caused by fishing industry. The use of alternative materials, including the macroalgae themselves, to make these materials biodegradable, would be a way to reach the following targets of Goal 12 and Goal 14:
• Target 12.5: By 2030, substantially reduce waste generation through prevention, reduction, recycling and reuse
• Target 12.6: Encourage companies, especially large and transnational companies, to adopt sustainable practices and to integrate sustainability information into their reporting cycle;
• Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution (UN, 2015).
Another issue is the fact that aquaculture was found to be one of the main vectors for the appearance of invasive algae species. Regarding this problem, there are already some measures being implemented, namely through the establishment of regulations. Regulation (EU) No 1143/2014 on the prevention and management of the introduction and spread of invasive alien species, establishes a set of guidelines for preventing, minimizing, and mitigating the negative effects of these species. The same regulation also establishes the elaboration of a list where the invasive alien species that reveal some concerns are mentioned, which must be updated when necessary. For species on this list, it is up to the Member States to take actions at the level of their introduction, detection, and eradication vectors (EC, 2021c). At the national level, Decree-Law No 92/2019 establishes guidelines for the possession, cultivation, breeding, and trading of exotic species. Furthermore, the same decree establishes the National List of Invasive Species, and the species described in it are unable to be introduced into nature, sold, transported, or cultivated, among other actions, unless they are licensed. This decree also specifies the parameters that must be met in order to obtain this license. Once this problem is minimized, seaweeds production will become more sustainable, representing a contribution to achieving Goal 6 and Goal 14, specifically the following targets:
• Target 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally;
• Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution (UN, 2015).
Also with regard to these two mentioned targets, it is important to highlight a technique that has gained some prominence in recent times: Integrated multitrophic aquaculture (IMTA). IMTA is an aquaculture method in which organisms belonging to different trophic
levels are produced in the same system (Pereira et al., 2013). Therefore, production is shared through the use of this technique, avoiding the need to search for new areas. In the case of seaweed production, the fish waste present in the system is used as a source of nutrients for macroalgae (Barrington et al., 2010). This represents a double advantage because, in addition to these nutrients being absorbed by the seaweeds and used for their growth, this absorption also allows for a higher quality of water in which the fishes live (Chopin, 2006). This technique has been proposed as a approach that, in addition to being more economically viable, is also more environmentally sustainable (Al Azad et al. 2017; Nobre et al. 2010). At the economic level, a significant advantage is associated with the diversity in the production of species that allows the generation of additional profits (Barrington et al., 2010; García-Poza et al., 2020). Concerning the environmental benefits of this approach, the absorption of nutrients by extractive species (in this case, seaweeds), prevents the occurrence of environmental damage such as eutrophication (Buck et al., 2018).
Another problem is associated with damage to ecosystems caused by seaweed production through wild harvesting. As previously stated, seaweeds are responsible for the provision of various ecosystem services, so an exhaustive collection of this product could compromise their provision. The effects of wild harvesting vary depending on factors such as the length of time the algae grow before being harvested, the cut zone in the seaweed, and the method used (Angus, 2017). At this level, several studies are emerging in order to provide new knowledge that allows a more efficient and sustainable algae production. Even so, in cases of application of the wild harvesting technique, it is essential to have a frequent assessment and monitoring of the availability of the natural algae stock, as well as of the entire surrounding environment, namely of the other species that use the intervention area, in order to guarantee that the ecosystem is not significantly disturbed. An investment in this area would be an asset to achieve Goal 14, namely in a target that, despite having a 2020-time horizon, should be constantly reinforced:
• Target 14.2 By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans (UN, 2015).
The availability of space and competition for it from different sectors also represents a problem of aquaculture. Regarding this issue, there are already some success cases in solving this problem, which although applied to other aquaculture species, could also be applied to macroalgae aquaculture. In these cases, the resolution of the competition problem was made through (MSP, 2021):
• Study of the area and consequently detailed zoning plan on the use of marine space;
• Risk assessment and implementation of mitigation measures (e.g., adaptation and improvement of structures and information to users of the zones);
• Definition of regulation (namely distances between cultures and tourist attractions, security measures to be implemented, promotion of equality between sectors, among others);
• Partnerships between sectors (use of aquaculture as a tourist attraction).
By addressing this issue using the strategies presented, it becomes easier to achieve Goals 8 and 9, namely the following targets:
• Target 8.2: Achieve higher levels of economic productivity through diversification, technological upgrading and innovation, including through a focus on high-value added and labour-intensive sectors;
• Target 9.4: By 2030, upgrade infrastructure and retrofit industries to make them sustainable, with increased resource-use efficiency and greater adoption of clean and environmentally sound technologies and industrial processes, with all countries taking action in accordance with their respective capabilities (UN, 2015).
Finally, it is critical to discuss the potential of seaweeds at the level of the 13th Goal:
Take immediate action to combat climate change and its consequences. As can be seen, there is a significant potential associated not only with the consumption of seaweeds but also with its incorporation into a variety of activities and sectors. However, there is a general lack of knowledge about this product. Several studies discuss the potential of algae in CO2 capture;
however, when the entire life cycle of the algae is considered, some authors are sceptical of this effect. A solid understanding of the potential of seaweeds, as well as good management
of the natural macroalgae community, could highlight the product's potential in combating climate change. This would then be a contribution to Goal 13 (Climate Action), with a focus on the following targets:
• Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries;
• Target 13.3: Improve education, awareness-raising and human and institutional capacity on climate change mitigation, adaptation, impact reduction and early warning (UN, 2015).
6.1 Uncertainty associated with this study
As previously stated, the RBA process has some associated uncertainties as a result of several assumptions made throughout this evaluation. These uncertainties can affect the results and must be identified. Therefore, in this study, these uncertainties are the following:
1. Regarding Inorganic Arsenic, a conversion factor of 70% is generally applied;
however, there is still some doubt for sea foods, such as seaweeds. The EFSA considered for this specific case (EFSA, 2014) a 1% conversion factor for algae. The fact that there is not, for sure, a conversion factor to be used for Inorganic Arsenic present in algae, leads to an uncertainty in the calculations. In the case of this study, the results obtained for the two percentages are quite different between each other;
however, because the values in the two cases do not exceed a MOE of 10000, the presence of risk can be concluded for both, and there is no significant disruption in the results.
2.To assess the risks associated with Porphyra species consumption, data from various studies (Leal et al., 1997; Paiva et al., 2014; Saraiva, 2019) were combined to create a sample that was as representative as possible. However, the same was not possible for the Undaria pinnatifida, so only the data from the study of Saraiva (2019) was considered. As a result, the data analysis was focused on a single sample, which is not satisfactory.
3. Consumption data was assumed, in all the scenarios considered. Future studies should be developed in order to proper characterize the current consumption of these foods products, contributing to a most accurate assessment.