Question

Why are phytoplankton essential to aquatic life zones? filter pollution from water provide basis of food chains moderate water temperature produce chemicals that can be used against predators

Answer 1

They provide basis of food chains.

Step-by-step explanation:

Phytoplankton are the autotrophic components of the plankton community and a key part of oceans, seas and freshwater basin ecosystems. The name comes from the Greek words φυτόν, meaning "plant", and πλαγκτός, meaning "wanderer" or "drifter".

Answer 2

The answer is provide basis of food chains.

Plankton includes a diverse group of organisms that live in the water, but are not capable of active swimming against the current. They are usually present in the upper part of the ocean, where is enough sunlight.
They are the basis of food chains in water ecosystems. They provide food for different animals, such as jellyfish, shrimps, whales, etc.