What is the habitat called where fresh water from a river meets salt water from the ocean?

An estuary is the habitat that forms where fresh water from a river mixes with salt water from the ocean. This unique environment is characterized by its brackish water, which has a higher salinity than fresh water but lower salinity than ocean water. Estuaries provide critical ecosystems that support diverse plant and animal life, serve as nurseries for many marine species, and act as important buffers against storms and flooding for surrounding areas.

The mixing of fresh and salt water creates a dynamic habitat that can support a wide variety of organisms adapted to fluctuating salinity levels. Estuaries often contain rich nutrient levels due to the sediment and organic matter carried by rivers, leading to high productivity and biodiversity. This distinctive ecological feature is what sets estuaries apart from lakes, wetlands, and deltas.