Which of the following is a negative consequence of using fowls to control aquatic weeds?

Using fowls, such as ducks or geese, to control aquatic weeds can lead to waste products that increase water fertility. When these birds feed on aquatic plants, they also excrete waste into the water, which often contains nutrients like nitrogen and phosphorus. This nutrient influx can enhance the growth of algae and other aquatic plants, resulting in eutrophication—a process where water bodies become overly enriched with nutrients. This can lead to increased plant growth or blooms, ultimately disrupting the aquatic ecosystem by causing oxygen depletion and harming fish populations.

In this context, the other choices do not accurately represent the negative implications associated with the use of fowls in weed management. For example, while increased weed growth might be a concern in other methods of weed control, the specific action of using fowls generally aims to reduce weed presence. Overpopulation of fish is not directly related to the presence of fowls, and the reduction of phytoplankton blooms typically does not arise as a consequence of fowl usage—it’s more about the balance of nutrient levels in the water. Thus, the nutrient contributions from fowl waste are key in understanding why option B highlights a significant negative consequence.