Coral reef ecosystems are an essential part of the ocean environment and imperative to the health of the entire ocean. With warming oceans, destructive fishing, marine pollution, and other factors, the coral reefs are dying. Losing coral reefs dramatically affects marine biodiversity and negatively impacts food security, shoreline protection, and essential tourism economies in coastal communities. Globally, more than one billion people directly benefit from coral reefs (Souter et al. (eds), 2021).. Therefore, restoring coral reefs is critical to ensure the well-being of both marine and human communities.
This thesis focuses on the redesign of a floating fish breeding system for the coral reef conservation start up, RoffaReefs. RoffaReefs is working on restoring ecosystem through the breeding of reef fish through a first of its kind floating fish breeding system. This system works by allowing fish eggs collected from the reef to grow into larvae in a protected environment before being released back into nature. The overall aim for the redesign was to design a nature-based fish breeding system for improved performance that can be used in various marine contexts.
The proposed design is a modular design with three separate modules: biological, storage, and float. This new design can improve the system’s operator accessibility and scalability in future contexts. Through the testing of scale models, it has been shown to improve the stability of the system in wavy conditions. At the end of this thesis, the next version is ready to be manufactured, and a full-scale test in context can be completed.

Cyanobacteria are photosynthetic microorganisms found in a variety of environments, including marine water bodies. Some species are able to perform biomineralization, producing minerals such as calcium carbonate (CaCO3) that may act as biocement. The biomineralization capability of cyanobacteria has already been explored in the development of Living Building Materials (LBMs), composed of an inert scaffold of sand and hydrogel, that contributes to CO2 capture.

The offshore industry is a significant user of concrete, contributing to 11% of the global CO2 emissions. Therefore, the application of cyanobacteria biomineralized materials is envisioned as a way to reduce CO2 emissions in this sector.

The cyanobacteria biomineralized material has been studied in the fields of construction and is applied in 3D printing, but its potential for offshore applications still needs to be explored.

This study aims to explores the proprieties of cyanobacteria biomineralized materials to catter some requirements of offshore applications, thereby contributing to a more sustainable practice. This was done by first recreating the material from other studies, assessing its mechanical proprieties and testing it in underwater conditions. This was followed by a tinkering process where material qualities (e.g., cyanobacteria optical density (OD), biomineralization/curing time, type of hydrogel, aditional coating) were adjusted to fullfill its purposes.

The impact of these changes were measured through submerging the material in seawater and assessing its mechanical proprieties.

The use of cyanobacteria at an OD of 2.4, resulted in the strongest material. Using agar as an hydrogel binder, countered the dissolvability of the material with a gelatine binder. On the other hand mechanical tests showed that the agar bonded material was significantly weaker than the gelatine bonded material. Adding a silicone rubber coating to the gelatine bonded material did not make the material resistant to seawater. A prolonged biomineralization time improved the strength of the material significantly but more exploration is required to determine if the biomineralization time is the result of this strength or the adjusted sand/medium ratio.

Overall, this study demonstrated that cyanobacteria biomineralized materials can be applied in offshore applications since the right cyanobacteria OD, binder, coating and biomineralization time are employed.

Namibia has been home to some of the world’s oldest ethnic groups since the dawn of civilization. One of these cultures is the Himba, often referred to as ‘the last true pastoral nomads’ of Africa. They are known for inhabiting the water scarce desert region of Kunene in Namibia for centuries. Now, various factors, including climate change and the absence of governmental support, are forcing the Himba population to decide which aspects of ‘modern’ culture to incorporate into their everyday lives.

After decades of declining rainfall and rising temperatures, drought and omakururukiro yokuti (over-utilized land and vegetation) are the reality. The Himba is therefore forced to rely on their nomadic origins for survival, and to travel southwards, ‘following the water’, to Windhoek which is the capital of Namibia. On arrival, they are confronted with inequality apparent in the African urban built environment and take part in the rapid urbanization of Windhoek. They settle in townships, in shacks, located on the outskirts of the city, where access to water and sanitation is limited. Due to landscape topology, climate change and other factors, the high possibility of flooding poses a new risk. Indeed a life-threatening choice: surviving drought in Kunene or surviving floods in Windhoek.

Flavobacteria are marine organisms that produce vivid, angle-dependent colour as their cells organise into structures that interact with light. These optical structures, resulting in structural colour, are influenced by environmental factors such as temperature and humidity. In this graduation project, the aim was to integrate living Flavobacteria into a flexible, sustainable material, creating labels that communicate environmental signals through changes in the structural colour of the embedded Flavobacteria. Understanding how to maintain Flavobacteria and their structural colour, outside the laboratory can be the steppingstone to make the entry of these microorganisms into the world of design.

The initial phase of the project focused on understanding the requirements for Flavobacteria to make structural colour outside the controlled laboratory environment. This understanding was crucial to design in a way that accommodates the unique characteristics of these microorganisms. Temperature was selected as the primary environmental stimulus to address, given its significant impact on the size and colour of the Flavobacteria colony. Additionally, temperature changes can be transferred through materials and therefore enable a sealed label without the necessity of openings to let environmental stimuli through.

The second phase involved an iterative experimentation process, which aimed to identify a suitable top material of the label that would facilitate the formation of structural colour by Flavobacteria. Additionally, efforts were directed towards finding an appropriate growth medium for Flavobacteria within the living label and devising an activation method that would initiate their growth exclusively during the product’s use phase. The outcomes of this iterative process were then integrated into a vision for the living label.

The project continues by presenting a future vision for the living label and proposing additional guidelines for designing with Flavobacteria. This vision draws upon literature research as well as the findings and insights gained through this graduation project. Further research is recommended regarding the characterization of the temperature influence on Flavobacteria, improving the surface texture of the medium used in the living label

To conclude, by combining existing knowledge with the project’s outcomes, a first proof of concept for a living label is proposed, paving the way for future exploration and application of these living microorganisms in innovative design contexts.