Which organisms use photosynthesis to provide food for zooplankton?

Phytoplankton are the primary organisms that utilize photosynthesis to convert sunlight into energy, which then serves as a food source for zooplankton. These microscopic plants are crucial components of aquatic ecosystems, forming the base of the food web. By absorbing sunlight and nutrients from the water, phytoplankton produce organic material that sustains a variety of marine life, including small animals like zooplankton.

Macroalgae, although they also photosynthesize, are generally larger and do not play the same foundational role in the food web as phytoplankton. Nonnative plants may not be adapted to the local ecosystem and may not contribute significantly to the food network for zooplankton. While some bacteria can perform photosynthesis, the majority of aquatic food production relies on the vast populations of phytoplankton, making them the most significant contributors to the diet of zooplankton in aquatic environments.