What do phytoplankton primarily produce in marine ecosystems?

Phytoplankton play a crucial role in marine ecosystems as primary producers. Through the process of photosynthesis, they utilize sunlight, carbon dioxide, and water to produce glucose, a simple sugar that serves as an energy source for the organisms that rely on phytoplankton for food. In addition to glucose, this process also generates oxygen as a byproduct, which is vital for the survival of most marine life and contributes significantly to the Earth's atmosphere.

The production of oxygen and glucose by phytoplankton underpins the marine food web, supporting a diverse array of organisms, from small zooplankton to large marine mammals. Furthermore, phytoplankton's role in carbon fixation helps to regulate global carbon levels, making them essential contributors to both the health of marine ecosystems and the planet's climate. This dual production not only sustains marine life but also influences broader ecological and atmospheric processes.