Because phytoplankton are near the bottom of the food chain, it would cause a domino affect where all of the higher levels are impacted. We could expect to see a decreased amount of organisms that eat the plankton and an increased competition for food.
Phytoplankton converts energy from the Sun into usable energy that fuels the rest of the food web. So, the higher levels of the food web won’t be able to sustain themselves if the population of phytoplankton decreases.
