What are phytoplankton, and how are they affected by the change in seasons?

Phytoplankton; small cells that use photosynthesis to turn sunlight into food that live near the surface of the ocean. There also responsible for about half of the Earth's primary production. The seasons also affect how well there doing, they need the climate best for them to produce right, changing seasons doesn't nearly affect them as much as climate change though.

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