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1.5 Research gap - Seaweed as a representative of the marine realm

Many ecosystems in our cities have not been studied in enough detail to suggest clear plans of action. It is critical to gain on-the-ground information about urban ecosystems in order to understand the systemic impacts that potential design interventions could have on cities before enacting them.



Kate Orff, SCAPE Studio, Toward an Urban Ecology

(Orff, 2016, p.218).

1.5.1 Why Seaweed? – The forgotten actor

My initial proposal in response to the PhD call was to look through the research call from the lens of seaweed based on an initial hypothesis and a research gap of “Urban Seascaping with seaweed” – i.e., “What if we urban landscaped/seascaped our boundary between city and sea, with seaweed and mussels as we do with flowers and trees on land?” (Refer to Preface – Research motivations). Therefore, the research project argues that macroalgae, more commonly referred to as seaweed, is an overlooked and undervalued coastal ecosystem in the LUDP disciplines[47] that deserves more attention[48]. Much of the focus and research has been on other coastal ecosystems, such as salt marshes, meadows, eelgrass, and wetlands, for restoration or inclusion as part of coastal cities’ protection, adaptation and mitigation strategies (Scott, Frail-Gauthier and Mudie, 2014; Caçador et al., 2016; Narayan et al., 2017; Wiberg, 2019; Zhu et al., 2020; Fairchild et al., 2021; Quintana, Kristensen and Petersen, 2021). For instance, in various state-of-the-art projects related to coastal adaptation projects (i.e., via nature-based solutions), seaweed is either missing or put on the back burner in both the main narrative and implementation[49]. And when there is a focus on seaweed, it is usually for its utilitarian function as food, feed and fuel (see section 1.5.3 Current barriers to integrating and utilising seaweed). Despite occupying a crucial land-to-sea transition space (i.e. the intertidal zone) and providing a range of critical ecological and socio-economic services, seaweed remains under-acknowledged in relation to its important role in tackling the negative impacts of anthropogenic climate change (see section 1.5.2 for more details). Regardless of the importance of these marine ecosystems, the integration and protection of these vital marine habitats are often disregarded at the expense of prioritising the urban environment and its future developments (Galland, Harrould-Kolieb and Herr, 2012; Filbee-Dexter and Wernberg, 2018a; Frontiers, 2018) (refer to the section 3.1.6 “Terrestrial bias). For instance, coastal urban development in the past century in Denmark has prioritised the act of expanding the city out into the sea (refer to section 3.1 for more information). This act has not only increased Danish coastal cities' vulnerability to the impact of rising sea levels but also led to the destruction of former marine habitats and seabed by removing large amounts of boulders, rocks and stones[50] to use for construction on the land, as shown in Figure 11 (Mørk Jørgensen, 2020; Stubgaard, 2020; Svendsen, 2020; Hedrup, 2021). Although these reclaimed areas are relatively small in comparison to the vast coastline of Denmark, they contribute to marine dead zones in the ocean bed because it claims coastal areas that are ideal for the survival of many marine habitats dependent on specific depths below sea level with access to sufficient sunlight to thrive, as shown in Figure 11 (Dahl et al., 2003; Bishop et al., 2017; Palmgren, 2019). The removal of conditions for coastal ecosystems due to land reclamation also removes the opportunities for urbanites to physically and visually interact with marine life forms closer to land, making the nature-culture divide more prominent (as outlined in section 3.1). Thus, there is an opportunity and a gap in research to address the current lack of spaces designed for a meeting place between the residents and the sea/marine life on the harbourfront and waterfront – something that Kanten/The Edge design competition set out to address (i.e., a requirement of a nature-based solution utilising nature underwater). Therefore, the research seeks to address this gap by investigating through Kanten/The Edge competition different ways in which seaweed, as part of a designed intervention at the waterfront, could contribute to the city's nature-based solution and an alternative relation with the nonhuman marine world in the future.

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Figure 11. (Top Left image) Illustration of how coastal ecosystems such as seaweed depends on a certain depth below the sea (depending on water clarity) to access sunlight for photosynthesis and is sensitive to thermal stress (Dahl et al., 2003; Harley et al., 2012). Hence, many coastal ecosystems thrive at an ideal depth below sea level, which land reclamation projects have replaced (the shallow areas). Image credit: Dahl et al., (2003).(Top Right image) Sugar Kelp (“sukkertang” in Danish) is brown macroalgae, which like many seaweed species, requires solid substrates like stones or rocks to attach itself to (Mouritsen, 2019). Therefore, they do usually not grow in sandy or muddy areas (unless they are seaweed species that float and thus are not dependent on rocks). Therefore, the removal of stones and rocks from the Danish coastline contributes to the lack of marine biodiversity. Image credit: The photo of the sugar kelp was taken from Aalbæk beach in January 2022.(Bottom image) A section drawing shows before and after the impact of the land reclamation process that replaces biologically productive shallow areas. The leftover areas are too deep for sunlight to reach, preventing the photosynthesis of marine vegetation such as seaweed. Image credit: Soo Ryu and Agnes Jarmund.(Extracted from Kumu Multiscalar map – Cyclic scale node).

The plight of seaweed

Unfortunately, seaweed as a life-supporting part of coastal ecosystems is globally declining due to anthropogenic climate change and human industrial activities (see Figure 12) (Harley et al., 2012; Filbee-Dexter and Wernberg, 2018a; 2018b). The changes in global sea temperatures have already resulted in a mass migration of seaweed to colder waters (i.e. kelp), putting pressure on them to adapt to their changing new environment (ibid.). For Denmark, the majority of coastal water bodies and their lifeforms are in poor ecological conditions due to environmental problems related to high levels of eutrophication from nutrient load from excessive use of fertilisers for agriculture[51] (see Figure 13) (Bredsdorff, 2018a; Filbee-Dexter and Wernberg, 2018b; Miljøstyrelsen, 2022a; n.d.). Excessive levels of eutrophication[52] found in Danish coastal waters lead to ecosystem degradation and hinder the restoration efforts of coastal ecosystems (Riemann et al., 2016). Therefore, there is a need to implement different ways to spread awareness of the impact of climate change and human activity on profoundly altering the ocean[53]. The irony is that these coastal ecosystems, like seaweed, face an uncertain future that needs to be protected from the negative impact of human activities while at the same time requiring proactive human management to survive in challenging conditions (Orff, 2016).

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Figure 12. Various drivers in global kelp forest decline. The map was created by Soo Ryu, combining maps from various sources (Filbee-Dexter and Wernberg 2018; Froehlich et al. 2019; Gundersen et al. 2017; Steneck et al. 2002). Note: Unlike kelp, other seaweed types can grow on the equator.(Extracted from Kumu Multiscalar map – Global scale node).


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Figure 13. The overall ecological status of coastal waters in Denmark from June 2016 (top image) to July 2021 (bottom image) shows some signs of improvement (Miljøstyrelsen, 2016; 2021; 2022b). The maps show the overall ecological condition of coastal waters based on several quality measures[54] with the nitrogen and phosphorous load on land. The poor condition is mainly due to excessive phosphorus and nitrogen load from agricultural farming. Recent efforts to clean up the coastal waters have shown some levels of improvement in water quality over the years. However, only a few coastal water bodies are in good ecological condition (as indicated in green). Jutland has a poorer water quality than Zealand due to a higher concentration of agricultural activity, as indicated by the maps. Maps created by Soo Ryu, GIS data from MiljøGIS (Miljøstyrelsen, 2016; 2021; 2022b).
(Extracted from Kumu Multiscalar map – National scale node).


    Restoring the health of these water bodies is paramount as it directly impacts biodiversity, recreation, climate change mitigation and coastal protection (refer to section 1.5.2 below).  Therefore, coastal adaptation strategies present an opportunity to integrate seaweeds into the urban shorelines so that humans might get more exposure to them, thereby making possible educational efforts that might raise awareness about the plight of the forests of the sea. Coastal zones are important figures of a meeting place that can provide opportunities for interaction and appreciation of the entanglement between land and water. Moreover, as global warming pushes the sea further into coastal cities, the question of how marine life forms could transform these inundated spaces remains an unexplored solution.


[47] Of course, much of the research on seaweed is dominated in the field of marine biology, especially phycology, the branch of botany concerned with seaweeds and other algae.

[48] In 2010, the Danish Ministry of Food, Agriculture and Fisheries released a report called “The sea - an untapped resource”. The report concluded that seaweed is an under-utilised, under-researched resource in Denmark and Europe with great potential for the future for its wide range of applications that can be produced in a sustainable way with little environmental impact, such as renewable energy to ease our dependence on fossil fuels and for sustainable food as an alternative to overfishing (Danmark and Ministeriet for Fødevarer, Landbrug og Fiskeri, 2010; Holdt, n.d.).

[49] From the literature review of the most well-known state-of-the-art (S-O-T-A) coastal adaptation projects around the world have either a stronger focus on salt marshes and wetlands than seaweed as “soft approaches/soft infrastructure” with little or no mention of seaweed. The literature review of the S-O-T-A projects covered are (and not limited to): “Rising Currents” – Project for New York’s Waterfront (Bergdoll et al., 2011), “On the Water” – Palisade Bay (Nordenson, Seavitt and Yarinsky, 2010), “Rebuild by design” – The Hurricane Sandy Design Competition for New York (Gendall et al., 2015), “Structures of Coastal Resilience” (Nordenson, Nordenson and Chapman, 2018) and Scape Studio’s works in their book “Towards an Urban Ecology” (Orff, 2016) to name a few for cases in the USA. And for Denmark, Realdania’s “Cities and the rising seawater” pilot projects (Realdania, 2019; Realdania and KU, 2020) and many other reviews of S-O-T-A coastal adaptation/protection projects (e.g. by Wiberg (2019)).

[50] Furthermore, the intensive fishing industry (i.e. bottom trawling) also removed habitat-forming substrates like stones, rocks and boulders (Organo Quintana, 2020).

[51] According to many researchers, agricultural activity is mainly responsible for the emissions of nitrogen (N) and phosphorous (P) responsible for poor Danish coastal conditions (the coastal waters are not impacted by other countries, but purely leaching from Denmark) (Bredsdorff, 2018a; 2018b; Organo Quintana, 2020; Fjeldsø Christensen, 2021). The EU deadline for achieving “good ecological condition” of coastal waters (119 coastal water bodies in Denmark) by 2027 is deemed unrealistic by researchers due to the continuing large amount of leaching of N and P in recent times (Bredsdorff, 2018a). Furthermore, increased rainfall predicted in the latest IPCC assessment report (2021) will carry more excess nutrients from agricultural runoffs to the coastal waters, worsening water quality for marine life and decreasing coastal waters' salinity levels and more algal blooms.

[52] According to Riemann et al. (2016),  since 1985, a number of Danish mitigation measures (i.e. Environmental Water Plan/Vandmiljøplanerne in 1987) have been implemented to reduce nutrient losses from three sectors: (i) agriculture, (ii) urban wastewater treatment plants, and (iii) industries with separate discharge. Since the eighties, there have been efforts to reduce P and N discharges, but the reduction is mainly due to the improvement of industrial and wastewater treatment (Carstensen et al., 2006; Riemann et al., 2016; Bredsdorff, 2018a).

[53] According to the latest report by the IPCC (2021), the ocean is warming rapidly with more frequent marine heatwaves, accelerating ocean acidification and deoxygenation levels. IPCC (2021) issues a warning that “these changes affect both ocean ecosystems and the people that rely on them, and they will continue throughout at least the rest of this century.” Moreover, the negative impacts of global warming and water pollution are responsible for the global degradation of 66% of marine environments (IPBES, 2019).

[54] See footnote 46.




Section 1.5 footnote
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