Final answer:
Phytoplankton are the primary producers in aquatic ecosystems, playing a crucial role in oceanic productivity.
Explanation:
Phytoplankton are microscopic plants that are the primary producers in aquatic ecosystems, responsible for a large portion of the world's photosynthesis in oceans. They include diatoms, dinoflagellates, and coccolithophores which make up a significant amount of marine primary productivity.
Learn more about ecosystems and primary producers here:
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