An estuary is a semi-enclosed coastal body of brackish water formed by the mixing of freshwater runoff from rivers and streams with saline ocean water. The mixing process creates a unique chemical gradient of salinity, which varies seasonally and spatially, influencing the local geochemistry and physical environment. These bodies of water are characterized by strong tidal flushing and are highly productive ecosystems, serving as critical nursery grounds and habitats for numerous species of organisms. The specific physical and biological conditions within an estuary make it a zone of immense ecological importance, supporting diverse flora and fauna adapted to fluctuating salinity regimes.