PhD Candidates

Sustainable Aquaculture

Aquaculture still faces major sustainability challenges. Current production systems rely heavily on fish-derived raw materials to produce fish and seafood biomass, making the optimization of feeding strategies and the substitution of fishmeal and fish oil essential. In addition, productivity in closed aquaculture systems is often limited by water eutrophication, caused by the accumulation of nitrates (NO₃⁻) and phosphates (PO₄²⁻), which can negatively affect animal growth and survival over time.

SwitchFloc addresses these challenges by evaluating the contribution of bioflocs to the growth, health, and immune status of farmed species, while developing innovative and sustainable aquaculture feeds with high fishmeal substitution, improved pellet quality, and enhanced digestibility. The inclusion of functional additives and bioactive compounds will further support animal health and resilience.

These solutions will be implemented and validated in combination with low-environmental-impact production systems, such as Integrated Multi-Trophic Aquaculture (IMTA-BFT) and hydroponic-based systems (FlocPonics). This integrated approach aims to reduce nitrate and phosphate accumulation, improve resource efficiency, and contribute to more sustainable and productive aquaculture systems.

Animal Welfare

Intensive aquaculture systems can have a significant impact on animal health and welfare. However, the bacterial and microalgae communities present in Biofloc have demonstrated clear probiotic and prebiotic effects, leading to reduced mortality rates and improved growth performance. These benefits, nevertheless, can vary depending on the species and growth stage, highlighting the need for species-specific welfare assessments and tailored management protocols within Biofloc Technology systems.

Once a pathogen outbreak occurs, effective treatment becomes challenging, emphasizing the importance of developing preventive protocols to minimize the emergence of pathogenic viruses and bacteria, as well as to improve their early detection and control. Within SwitchFloc, the bacterial and microalgae composition of bioflocs will be thoroughly characterized to identify a comprehensive list of potential prebiotic, probiotic, and postbiotic species, supporting healthier and more resilient aquaculture systems.

Environmental Impact

The circular economy, is defined as a model of production and consumption based on sharing, leasing, reusing, repairing, refurbishing, and recycling materials and products for as long as possible. Biofloc Technology (BFT) fits perfectly within this concept and, thanks to its circular nature, is considered a low carbon footprint aquaculture system.

However, the zero or minimal water exchange characteristic of BFT production leads to the accumulation of nitrates and phosphates, as well as an excess of biofloc biomass. These factors represent significant environmental challenges that must be addressed. Developing effective mechanisms for denitrification and dephosphorylation of BF water is therefore essential, not only to reduce nutrient accumulation but also to enable water reuse across multiple production cycles.

Within SwitchFloc, the carbon footprint of BFT will be assessed using a Dynamic Energy Budget approach under different environmental conditions and aquaculture system configurations, including stand-alone BFT and integrated systems such as IMTA-BFT and FlocPonics. In parallel, SwitchFloc will develop biological treatment systems based on denitrifying bacteria and phosphate-accumulating bacteria to reduce NO₃⁻ and PO₄²⁻ levels during and after the BFT aquaculture cycle.

Economic Viability

Sustainability must be addressed not only from an environmental perspective, but also from an economic and social point of view. The economic viability and environmental sustainability of Biofloc Technology are already widely recognized, along with its potential to improve the welfare and health management of aquatic organisms. At the same time, ensuring food quality should remain a cornerstone of aquaculture production, and the optimization of BFT systems must not compromise meat quality.

Within SwitchFloc, a comprehensive assessment of the economic and financial feasibility of BFT production at the European level will be conducted, incorporating the innovations and improvements developed throughout the project. This analysis will use the current status of BFT implementation in countries where the technology has already been developed or adopted as a baseline. In parallel, project partners will explore market opportunities, including consumer acceptance, through participatory approaches that are essential to evaluate willingness to pay.

In addition, SwitchFloc will investigate key biological and nutritional factors, such as BFT nutrient composition under different aquaculture systems, to assess how fishmeal substitution and farming conditions influence meat quality. This integrated approach will ensure that sustainability, economic performance, and product quality advance together.