Phytoplankton are microscopic photosynthesizing organisms that typically live in the upper layers of the ocean. what trophic level do phytoplankton belong to?
primary producers
decomposers
primary consumers
secondary producers

Primary producers

A food chain is a linear series of transfer of food and energy when one organism is consumed by the other organism in an ecosystem. The energy is distributed among different tropic levels of the food chains.

Phytoplankton is a class of unicellular simple, autotrophic organisms which are found in water of ocean, lakes and or any other freshwater body. These includes dinoflagellates, diatoms, cynobacteria, green algae and others. These organisms are abundantly present in the ecosystem in the lower most trophic level. They are called as primary producers because they are consumed by other organisms such as zooplanktons, fishes and large sea mammals.