Answer with Explanation:
The death of plants in water increases the presence of "organic matter." Bacteria feed on organic matter and decompose it, thus, the sudden presence of organic matter signals the bacterial activity to increase. The number of bacteria increases through "binary fission," which happens in fast rate. Their response to food (organic matter) is very rapid. Once they're able to decompose it, the growth of bacteria slows down until it drops to a low number.