AQUAPHOENIX is funded under a European Union call for projects that work to bring Nitrogen and Phosphorus (N+P) emissions within safe ecological boundaries. Below, we explore this challenge and how AQUAPHOENIX is answering the call by managing N+P emissions from aquaculture, protecting marine health, and recycling aquaculture waste.
The role of Nitrogen and Phosphorus in Marine Life
N+P are critical for marine life. Phytoplankton, small plants suspended in the water that move with the currents, are at the base of the marine food chain and depend on N+P and other nutrients for survival. These floating factories take up carbon dioxide, water and light energy to produce their own sugars and oxygen, a process better known as photosynthesis. Phytoplankton need other chemicals too, some of which only occur in low concentrations at the surface of the water, where the sunlight is still available for photosynthesis. These low concentration chemicals are considered nutrients, and their limited availability keeps the amount of phytoplankton in balance.
However, when levels of N+P in the water exceed certain levels, their impact can change the biodiversity and deteriorate the water quality. A healthy marine ecosystem is biodiverse and dynamic, but stable. In eutrophicated waters, where N+P exceed their limits, phytoplankton flourish and can come to dominate the ecosystem.
The increase of N+P, nutrients and by extension phytoplankton in eutrophic waters has cascading effects on the ecosystem. Because of the thicker layer of phytoplankton at the watersurface, marine life in the water below can miss out on the light they need and struggle to survive. And when the phytoplankton reach the end of their life cycle, they sink to the bottom and their decay takes up oxygen. If the ecosystem cannot replenish the oxygen levels at a high enough rate, bottom-dwelling organisms are deprived of oxygen. Another concern is that some phytoplankton produce toxins that in high amounts hamper human health and food security. These are some of the knock-on effects of excess levels of nutrients. Ultimately the marine biodiversity is altered, and with it the ecosystem functions they provide like water quality regulation.
Today, we see that anthropogenic N+P inputs to the environment exceed planetary boundaries, but that the impacts vary regionally and across different industries including agriculture and aquaculture. Therefore N+P budgeting (which consists of tracking their inputs, outputs and how they move within an ecosystem) requires a careful and regional approach.
Managing nutrient emissions from aquaculture
Collective action is needed to improve nutrient management and protect ecosystems. Food systems can play a major role in solving the nutrient crisis. In Europe efforts to manage nutrients include intervention at multiple points in the N+P cycles, and can include novel technologies for recovering and recycling nutrients, efficient nutrient management, societal change, and policy measures. An umbrella strategy in Europe is the Green Deal, which envisions a resource-efficient and competitive future. The Green Deal encompasses three strategies – the Biodiversity Strategy to 2030, the Zero Pollution Action Plan and the Farm to Fork Strategy – which together lay out a path to reduce nutrient losses to the environment by 50% by 2030. One of these, the Farm to Fork Strategy, specifically focuses on the transition towards sustainable food systems that have a neutral and even positive impact on the environment.
As recognised in the Green Deal, sustainable aquaculture is a source of low-carbon food. Aquaculture has the potential to pave the way towards environmentally-friendly and competitive food production systems while operating within safe ecological boundaries for N+P emissions.
Aquaculture is a contributor to N+P emissions, and additional solutions are needed to keep emissions in check and ensure safe, sustainable growth of the industry to meet growing demand. Traditional aquaculture introduces N+P to the environment through excess fishfeed and waste (sludge). There are several prevention measures like careful site selection, manipulating feed composition, recovering feed, and effluent water treatment that limit the industry’s environmental impacts. All these efforts, combined with strict monitoring, ensure that nutrient losses are within the carrying capacity of a given sea region. In Europe aquaculture is subject to strict licensing and must comply with European and relevant national legislation. Requirements include the assessment, monitoring, and limiting of environmental impacts following nutrient and organic discharge. By reducing emissions from aquaculture with novel technologies, farmed seafood can meet its potential to sustainably feed the growing global population and satisfy increasing food demands.
AQUAPHOENIX: reducing emissions, salvaging nutrients
This is where AQUAPHOENIX comes in as a Horizon Europe project working to reduce N+P emissions from aquaculture. By developing novel technologies to collect aquaculture sludge directly from active fish farms, we are testing the possibilities for a zero-pollution aquaculture industry. Extracted N+P from sludge will be tested for use as green biogas, organic fertiliser and sustainable aquafeed, showcasing the potential of aquaculture waste as a circular resource. The regional impact of sludge collection technologies on marine ecosystems and their restorative potential will also be assessed, with a view to developing a reliable framework for nutrient monitoring and budgeting. AQUAPHOENIX takes a holistic and systematic approach that further increases the sustainability of aquaculture production systems and sets the stage for a circular economy in Europe.
Further reading
FAO. 2024. The State of World Fisheries and Aquaculture 2024 – Blue Transformation in action. Rome.
G.M. Hallegraeff et al. (2021). Global HAB Status Report. A Scientific Summary for Policy Makers. G.M. Hallegraeff, H. Enevoldsen, A. Zingone (Eds). Paris, UNESCO. (IOC Information Document, 1399.)
Grizzetti, B., Vigiak, O., Aguilera, E., Aloe, A., Biganzoli, F., Billen, G., Caldeira, C., De Meij, A., Egle, L., Einarsson, R., Garnier, J., Gingrich, S., Hristov, J., Huygens, D., Koeble, R., Lassaletta, L., Le Noë, J., Liakos, L., Lugato, E., Panagos, P., Pisoni, E., Pistocchi, A., Sanz Cobeña, A., Udias, A., Weiss, F., Wilson, J. and Zanni, M., Knowledge for Integrated Nutrient Management Action Plan (INMAP), EUR 31487 EN, Publications Office of the European Union, Luxembourg, 2023, ISBN 978-92-68-02654-0, doi:10.2760/692320, JRC129059.
Sigman, D. M. & Hain, M. P. (2012) The Biological Productivity of the Ocean. Nature Education Knowledge 3(10):21
World Bank. Harnessing the Waters – Volume I (English). Washington, D.C. : World Bank Group. http://documents.worldbank.org/curated/en/099062325120031041
