Which of the following methods is a preventive approach in aquatic pest management?

Reducing nutrient input into water bodies serves as a preventive approach in aquatic pest management because excess nutrients, particularly nitrogen and phosphorus, often lead to the overgrowth of algae and aquatic plants. This phenomenon, known as eutrophication, can create severe problems such as oxygen depletion, loss of biodiversity, and the development of harmful algal blooms. By minimizing nutrient pollution through methods such as better agricultural practices, managing runoff, or implementing vegetative buffers, the likelihood of pest outbreaks is significantly decreased. This proactive strategy addresses potential issues before they escalate, promoting a healthier aquatic ecosystem.

In contrast, the other methods, such as installing chemical treatment facilities, spraying pesticides during outbreaks, and monitoring pest populations, tend to be reactive or focused on treatment after problems arise rather than preventing them from occurring in the first place.