What defines an estuary?

An estuary is specifically defined by its unique geographical and ecological characteristics, primarily characterized as a body of water where fresh water from rivers and streams meets and mixes with salt water from the ocean. This mixing creates a distinct environment that supports diverse ecosystems, making estuaries crucial habitats for many species of fish, birds, and other wildlife. The brackish water found in estuaries is important for the life cycles of various aquatic organisms, including many commercially important fish species.

While wetlands dominated by grass are important ecosystems, they do not capture the essence of what an estuary is. Similarly, the concepts of land sinking or plants adapted to wet conditions describe different environmental features that are not specific to the mixing of fresh and salt water that defines an estuary. Understanding estuaries is vital, as they serve numerous ecological functions, including acting as nurseries for marine life, providing habitat, and helping filter pollutants from upland sources.