What is a common challenge with water recycling in aquaculture systems?

Water recycling in aquaculture systems indeed presents the challenge of potential pathogen buildup. In a closed-loop system where water is reused, there is a risk of pathogens, such as bacteria and viruses, proliferating over time if not properly managed. This occurs because the same water is circulated back into the system, which can allow any pathogens present to remain and multiply rather than being filtered out. Effective biosecurity measures, water treatment technologies, and regular monitoring are necessary to minimize this risk and ensure the health of the aquatic organisms.

The other factors listed, while important considerations in the management of aquaculture systems, do not represent the direct challenge posed by water recycling in the same way that pathogen buildup does.