Final answer:
Marshes and mangrove forests are found in the estuarine zone, plankton are abundant in the neritic zone, and the aphotic zone contains little plant or animal life.
Step-by-step explanation:
In which zone do you find marshes and mangrove forests? Marshes and mangrove forests are typically found in the estuarine zone, where rivers meet the ocean. This zone provides nourishment and shelter for many young marine species.
In which zone are plankton plentiful, providing plenty of food for the fish that live there? Plankton are particularly plentiful in the neritic zone, where sunlight can penetrate allowing photosynthesis and thus supporting a diverse food web.
In which zone would you find very little plant or animal life compared to other zones? Areas with very little life compared to other zones are typically found in the aphotic zone, where the lack of light prevents photosynthesis, dramatically reducing the amount of life that can be supported.