In this wetlands ecosystem, the is/are an important abiotic factor that could limit the underwater organism populations.

D.O

Explanation:

The DO stands for dissolved oxygen. The amount of free oxygen available in water is called dissolved oxygen. The excess increase or decrease in the DO directly harms aquatic organisms. The decrease in the amount of DO causes an sudden increase in population of algae. The algae decomposition uses oxygen present in water and thereby decreasing DO for aquatic organisms.

Thus, the dissolved oxygen is an important abiotic factor that could limit the underwater organism populations.