Seaweed farming, also known as seaweed aquaculture or mariculture, is emerging as a promising source of sustainable biomass with diverse applications (Buschmann et al., 2017; Chopin and Tacon, 2021; Spillias et al., 2023). Compared to terrestrial crops, seaweeds require minimal inputs, such as freshwater, arable land, and fertilizers (Roleda and Hurd, 2019). Conducted in many coastal marine environments worldwide (Food and Agriculture Organization, 2020), seaweed farming primarily takes place in shallow waters but is being trialed at deeper offshore sites (Bak et al., 2020). Cultivated seaweeds include red (phylum Rhodophyta), brown (phylum Ochrophyta including kelps), and green (phylum Chlorophyta) seaweeds, each with distinct properties and commercial value (Food and Agriculture Organization, 2018). The global seaweed farming industry has grown in recent years, driven by increasing demand for seaweed-derived products across sectors such as food, agriculture, cosmetics, and pharmaceuticals (Hafting et al., 2015; Food and Agriculture Organization, 2020; Chopin and Tacon, 2021).

Seaweed farming offers various socioeconomic benefits. For instance, employment across the seaweed value chain (i.e., nursery, harvest, and post-harvest) has diversified livelihoods in coastal communities and empowered women, particularly in regions where the industry is woman-dominated (Sievanen et al., 2005; Larson et al., 2021). However, socioeconomic risks also exist, including adverse health effects on farmers (Fröcklin et al., 2012) and low income due to market volatility and crop failures caused by diseases, pests, and natural disasters (Aslan et al., 2018; Mariño et al., 2019). Additionally, while seaweeds are highly nutritious and rich in dietary fiber and protein (Cherry et al., 2019; Cai et al., 2021), those cultivated in contaminated waters can accumulate heavy metals such as cadmium and inorganic arsenic, posing risks to human health without proper monitoring and regulation (Food and Agriculture Organization and World Health Organization, 2022). Such seaweeds may be more suitable for applications like biofuel production (Fernand et al., 2017).

Seaweed farming also provides environmental benefits (Duarte et al., 2022). Through photosynthesis, seaweeds absorb dissolved carbon dioxide (CO₂) from surrounding waters and release oxygen into the water column, locally mitigating ocean acidification and deoxygenation (Mongin et al., 2016; Jiang et al., 2020; Xiao et al., 2021). At sufficient spatial scales and under suitable oceanographic conditions, seaweed farming could contribute to atmospheric CO₂ mitigation; although this pathway remains under active investigation (Bach et al., 2021; Hurd et al., 2022). Furthermore, seaweed farming improves coastal water quality by removing excess nutrients like nitrogen and phosphorus, reducing risks of eutrophication and harmful algal blooms (Yang et al., 2015). It can also enhance biodiversity by providing habitat and food for marine organisms (Kerrison et al., 2015; Walls et al., 2016, Walls et al., 2017; Wood et al., 2017; Visch et al., 2020; Hancke et al., 2021). However, these benefits can vary across ecosystems, as evidenced by studies reporting negative biodiversity impacts in tropical seagrass meadows (reviewed by United Nations Environment Programme, 2023). Environmental problems such as the introduction of invasive species, habitat alteration, and climate change also pose challenges to the sustainable expansion of the seaweed farming industry (Buschmann et al., 2014; United Nations Environment Programme, 2023).

Efforts to strategically expand seaweed farming aim to maximize its socioeconomic and environmental benefits while minimizing associated risks, necessitating improvements in cultivation practices and regulatory frameworks (Costello et al., 2020; Cottier-Cook et al., 2021; Duarte et al., 2022). One innovative approach is co-locating seaweed farms with other marine activities, such as offshore wind energy production (Buck et al., 2008; 2018). Co-location could offer opportunities to upscale sustainable biomass production, optimize marine space use, and share costs for resources like infrastructure, vessels, and personnel (Buck et al., 2018; O'Shea et al., 2024). However, co-location may exacerbate existing environmental and socioeconomic concerns related to offshore development, such as species declines and conflict among stakeholders (O'Shea et al., 2024). Currently, co-location of seaweed farming with offshore wind remains limited to pilot-scale projects, and the factors hindering large-scale implementation, as well as the specific risks and benefits, are poorly understood (Van den Burg et al., 2020; Falconer et al., 2023).

Here, we conduct a quick scoping review (QSR) to evaluate the state of knowledge surrounding the co-location of seaweed farming with offshore wind energy. By synthesizing data from peer-reviewed scientific articles, we provide an overview of the available evidence on the ecosystem services, constraints, and knowledge gaps associated with this multi-use approach. Our findings provide insights for policymakers, researchers, and stakeholders to advance sustainable co-location practices with offshore wind.

This study provides an overview of available evidence on co-locating seaweed farming with offshore wind energy, highlighting key temporal and spatial trends as well as patterns in the emphasis of general seaweed farming literature versus offshore wind-focused studies on various ecosystem services, constraints, and knowledge gaps. The findings demonstrate a small but growing number of studies on the topic of offshore integration, and indicate opportunities and challenges associated with this emerging multi-use system. For instance, a geographical skew in the literature, with most wind-focused studies concentrated in Europe and limited data from Asia—where the majority of farmed seaweed biomass originates—indicates a need for broader regional representation in future research on co-location. Additionally, the identification of 75 seaweed species or taxonomic groups in general seaweed farming studies, compared to only six species mentioned in studies on offshore integration, highlights the need for greater taxonomic representation in future research. These findings amplify a call for interdisciplinary investigations into the socioeconomic and environmental dimensions of seaweed farming in diverse contexts (United Nations Environment Programme, 2023).

Our ecosystem services analysis indicated a predominant emphasis in seaweed farming research on provisioning services, or the material and tangible benefits that humans obtain directly from ecosystems, here focusing on seaweed in food and agricultural applications. Both the general and wind-focused literature emphasized these provisioning services, but they were even more prominent in the wind literature. This focus highlights a strong and consistent interest in the value of seaweed-derived products, and aligns with extensive literature demonstrating the nutritional benefits of seaweeds (Cherry et al., 2019), their role in enhancing agricultural productivity through seaweed extracts (Nabti et al., 2017; Ali et al., 2021), and their use as feed additives for livestock, including cattle and horses (MacArtain et al., 2007; Pereira et al., 2020).

While regulating or habitat services, such as bioremediation and habitat and food provisioning for marine species, were frequently discussed, cultural services received considerably less attention, particularly in offshore contexts. In the wind-focused records, only two types of cultural services were cited: employment or income generation and improved quality of life. This is in comparison to 11 types of cultural services cited in the general seaweed farming literature, which emphasized small-scale, community-based seaweed farming in shallow, coastal areas, often in poor, rural regions of developing countries (Rimmer et al., 2021; Mariño et al., 2019). This limited focus in the wind literature may reflect insufficient research on the cultural benefits of offshore multi-use. Importantly, scaling seaweed farming to offshore facilities would likely industrialize production, potentially altering its cultural services (Rimmer et al., 2021; Larson et al., 2021). Future studies should examine how scaling up production may impact socioeconomic outcomes, focusing on the demographics of seaweed farming communities, and particularly vulnerable groups.

The early stage of offshore seaweed farming was reflected in our analysis of the wind-focused studies, where legal gaps emerged as the predominant knowledge gap. These gaps underscored the need for clear frameworks for shared legal governance (Van den Burg et al., 2020). Indeed, differences in the emphasis on constraints and knowledge gaps between general seaweed farming literature and wind-focused studies likely reflect the differing stages of their implementation. In wind-focused studies, primary constraints centered on risks to species, habitats, and ecosystems, including potential negative interactions with native species, such as nutrient competition with phytoplankton and cascading effects up the food chain (Campbell et al., 2019; Shi et al., 2011). In contrast, general seaweed farming studies predominantly cited the impact of nuisance species—pests, diseases, and epiphytes—which reduce biomass, degrade product quality, and result in economic losses for farmers (Bannister et al., 2019; Hu et al., 2010; Ward et al., 2020). Notably, wider ecosystem effects were more often cited as a knowledge gap in general seaweed farming rather than an immediate constraint. These distinctions suggest that ecosystem degradation is perceived as a more immediate threat in the emerging offshore seaweed farming industry, while risks of production failure, often due to nuisance species, are more pressing in established shallow-water farming systems. Regardless of the context, strategic farming practices and robust biosecurity frameworks are widely recognized as critical for ensuring the sustainability of commercial seaweed farming (Cottier-Cook et al., 2016, Cottier-Cook et al., 2021).

In conclusion, seaweed farm-offshore wind multi-use holds the potential to provide ecosystem services, yet concerns remain regarding potential environmental impacts and a lack of a regulatory framework. Research relating to the environmental impacts of seaweed farming, and specifically mitigating competition for resources, is a clear area of future research need for offshore wind multi-use. Additionally, research is needed on the legal governance of multi-use sites, and next steps could include examinations into regional stakeholder views and values regarding the opportunities and challenges of seaweed farm-offshore wind co-location. Finally, comparative studies that assess the feasibility and sustainability of different seaweed farming models, including integrated multi-trophic aquaculture (IMTA) and offshore wind co-location, can inform evidence-based decision-making and policy development. Addressing these gaps will require collaboration among stakeholders, including policymakers, industry, and local communities, to move towards sustainable co-location practices.