Marine Ecosystem Primary Producers

Cyanobacteria (blue-green algae) and Diatoms are microscopic autotrophic phytoplankton that synthesize organic molecules using solar energy, forming the foundational primary producer base in oceans. Copepods and Foraminifera are heterotrophic organisms; copepods are tiny crustaceans (zooplankton) that consume phytoplankton, while foraminifera are single-celled amoeboid protists. > Phytoplankton like diatoms and photosynthetic cyanobacteria anchor global ocean trophic food webs. Answer: (b).