* Zooplankton are primary consumers: They feed directly on phytoplankton, which are producers (the base of the food chain).

* Trophic Levels: The higher the trophic level, the further an organism is from the primary producers. Predators that eat zooplankton would be at a higher trophic level.

Example:

* Phytoplankton: Producers (trophic level 1)

* Zooplankton: Primary consumers (trophic level 2)

* Small Fish: Secondary consumers (trophic level 3)

* Larger Fish: Tertiary consumers (trophic level 4)

Therefore, zooplankton occupy a relatively low trophic level.