Final answer:
Estuaries favor organisms that can tolerate changes in salinity and benefit from abundant nutrients.
Step-by-step explanation:
Estuaries are areas where freshwater from rivers and streams meets and mixes with saltwater from the ocean. They have unique characteristics that make them ideal habitats for various types of organisms.
Because estuaries are partially enclosed and have a mix of freshwater and saltwater, they have a wide range of salinity levels. This makes them favorable for organisms that can tolerate or adapt to changes in salinity, such as brackish water fish, crabs, and mangrove trees.
Estuaries also have abundant nutrients, including sediment from rivers and organic matter from decaying plants and animals. These nutrients support a rich diversity of plant and animal life, including algae, seagrasses, shellfish, and migratory birds.