The Atchafalaya Basin, the surrounding plain of the river, is filled with bayous, bald cypress swamps, and marshes that give way to more brackish estuarine conditions and end in the Spartina grass marshes, near and at where it meets the Gulf of Mexico.
The Bembridge marls, freshwater, estuarine and marine clays and marls (70–120 ft.) rest upon the Bembridge limestone, a freshwater pool deposit (15–25 ft.), with large land snails (Amphidromus and Helix), freshwater snails (Planorbis, Lymnaea), and the fruits of Chara.
The range of the Colares stingray appears restricted to the mouth of the Amazon River in northern Brazil, in the estuarine area affected by the river's freshwater discharge; it may also occur in adjacent areas as far as Venezuela.
The region south of the yellow line includes Lake Okeechobee, the Everglades, the Big Cypress Swamp, the Atlantic Coastal Ridge, the estuarine mangroves of the Ten Thousand Islands, and Florida Bay.
This is an ancient estuarine woodland of sessile oak Quercus petraea on the steep outer banks of the Western Cleddau estuary.
About its late Whaingaroan (about 27 million years ago) creation, it says, “The change from estuarine, shallow brackish water conditions (Mangakotuku Formation), to fully marine, open sea, aerobic conditions (Glen Massey Formation) is evidenced by near shore accumulation of the bioclastic Elgood Limestone, onlap of the succeeding Dunphail Siltstone, and subsequent deposition of Ahirau Sandstone in an inner to mid shelf environment.”
Kanuka can be found on the slopes of the Te Puru creek (the estuarine Mangrove salt marsh).
Besides, the Windowpane oyster, Mud crab, Mullet, Halfbeak and Green chromide are some of the estuarine fauna present in the marsh.
The roughnose stingray, Pastinachus solocirostris, is a little-known species of stingray in the family Dasyatidae, generally found in shallow, estuarine waters associated with mangroves off Borneo, Sumatra, and possibly Java.
Tallowa Dam has been a barrier to migratory native fish with estuarine/marine juvenile stages, blocking species including Australian bass from more than 80% of their former range in the Shoalhaven system.
Synanceia horrida is a species of venomous fish of the Synanceiidae family, also known as the Estuarine stonefish or regionally as simply stonefish.
Rivers have positive effects in that they carry a significant amount of sediment, which aids in building land in estuarine regions.