Explain how photosynthesis occurs. What would happen if phytoplankton go extinct?

What would happen if phytoplankton went extinct?  

Nearly all small marine predators eat plankton as their primary food source, so if the plankton were to disappear, then the small predators wouldn't be far behind. Not only would those populations be without a significant food source, but local trade would suffer, and their economies would start to collapse.

Explanation:

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.  

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.