Zooplankton play a critical role in freshwater ecosystems as primary consumers within the food web. They feed on phytoplankton and organic matter, serving as a vital link in transferring energy from primary producers to higher trophic levels, such as fish and other aquatic organisms. By grazing on phytoplankton, zooplankton help regulate plant populations and maintain the balance of the ecosystem. They are integral to nutrient cycling and contribute to the overall productivity and health of freshwater systems. Additionally, zooplankton populations can indicate environmental changes, serving as important bioindicators.