The primary engine of ecosystem metabolism is photosynthesis, where plants, algae, and some bacteria convert sunlight into energy. This process generates organic matter, fueling the food web and supporting life by producing oxygen as a byproduct. In aquatic ecosystems, phytoplankton serves a similar function. The rate of photosynthesis determines the overall productivity of ecosystems, impacting carbon cycling and ecosystem health. Thus, understanding this fundamental process is crucial for assessing biodiversity, ecosystem services, and the responses of ecosystems to environmental changes.