Nearctic Lowland Rivers - Code: Ne11G

For a baseline on river ecological processes, see Nearctic Upland Rivers.
Nearctic Lowland Rivers are the languid, muddy rivers of flat, low-lying areas of the continent. These rivers are often broad with wide floodplains, lower oxygen levels and silty, sandy or muddy riverbeds. The aquatic aspects of these rivers are generally less complex with riffles and glides generally absent. Deep, slow moving, pools do form and are important to a variety of species.  Unlike upland rivers, lowland rivers do have regular aquatic vegetation and an abundance of submerged logs and protruding snags. The animals here are not adapted to swift current and in many ways this aquatic system is more similar to eutrophic lakes and ponds than it is to upland rivers.
Nearctic Lowland Rivers generally fall into two broad categories. The majority of Nearctic Lowland Rivers, including the massive Mississippi, are whitewater or brownwater rivers. Not to be confused with “white-water” rapid systems, whitewater rivers are pH-neutral with large amounts of suspended sediment. Whitewater rivers are the color of milky-coffee.
Blackwater rivers tend to be smaller waterways and in North America, are largely restricted to the Southeast United States. Blackwater rivers originate in flooded swamplands and bottomland forests and often have sandy bottoms. The water in these rivers is heavily stained by tannins and the color resembles a cup of strong tea. Blackwater systems are generally acidic and low in nutrients. Lacking in dissolved minerals blackwater systems don’t have sufficient calcium for shell growth in mollusks and are usually lacking in snails and mussels.
Nearctic Lowland Rivers are often highly variable in width, filling large river basins and regularly flooding huge areas. These rivers are typically associated with swamp forests and wetlands; Bottomland Hardwood Forest, Cypress-Tupelo Gum Swamp, Peten Swamp Forest, Neotropical Mangroves, and Nearctic Sedge and Grassland Marshes are all associated with this habitat.